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Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido(2,3- d )-pyrimidines

Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some... Acta Phm. 58 (2008) 359­378 10.2478/v10007-008-0024-1 Original resech paper HEND N. HAFEZ HEBAT-ALLAH S. ABBAS ABDEL-RAHMAN B. A. EL-GAZZ* National Resech Centre Photochemistry Deptment (Heterocyclic Unit), Dokki 12622 Cairo, Egypt New series of 2-hydrazino-7,8-dihydro-6H-cyclopenta[5,6] pyrido[2,3-d]pyrimidines and its 1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine, 1,7, 8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,3,4]tetrazolo[4,5-a]pyrimidine, 8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidine, 2-(pyrazol-1-yl)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidine derivatives were preped in order to obtain new compounds with potential anti-inflammatory and analgesic activity and low ulcerogenic effect. The compounds possessing potent anti-inflammatory activity were further tested for their analgesic and ulcerogenic activities. Compounds 3-amino-6-(4-yl)-9-(4-ylmethylene)-cyclopenta[5,6]pyrido[2,3 -d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4c), 1-amino-2-methyl-6-(4-yl)-9-(4-yl-methylene)-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidin-5(H)-one (6a), 2-amino-5-(4-yl)-8-(4-ylmethylene)-cyclopenta[5,6]pyrido[2,3-d]pyrimidine-4(H)-one (9), 2-(3-amino-5-hydroxypyrazol-1-yl)-5-(4-yl)-8-(4-ylmethylene)-cyclopenta[5,6] -pyrido[2,3-d]pyrimidin-4(H)-one (10a) and 3-thioxo-6-(4-yl)-9-(4-ylmethylene)-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (13) showed significant analgesic effects. Compound 2-(3-amino-5-hydroxypyrazol-1-yl)-5-(4-yl)-8-(4-ylmethylene)-cyclopenta [5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10a) was evaluated as the lead compound having higher anti-inflammatory activity (82.8%) than ibuprofen (79.5%) and lower ulcerogenic effect. Keywords: pyrido[2,3-d]pyrimidines, [1,2,4]triazole anellation, anti-inflammatory, analgesic activity Accepted September 18, 2008 It is already known that some pyrimido[4,5-b]quinolin-4-one derivatives display an interesting analgesic action in the writhing syndrome and hotplate tests and e not to* Correspondence, e-mail: profelgazz@yahoo.com H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. R2 R1 R3 N N H R4 Fig. 1. Pyrido[2,3-d]pyrimidin-7(8H)-one xic (1). Also, pyrido[2,3-d]pyrimidin-7(8H)-ones have attracted interest of phmaceutical companies due to the wide range of biological activities associated with this scaffold. Thus, a sech revealed that more than 3000 structures of type A (Fig. 1) have been described; they show biological activities ranging from kinase inhibition (platelet-derived growth factor, PDGFr, fibroblast growth factor, FGFr, and epidermal growth factor, EGFr) (2), CSP/p38 kinase inhibition (3), Src tyrosine kinase inhibition (4, 5), cdk4 inhibition (6), p38 MAP kinase inhibition (7), cyclin dependent kinase inhibition (8, 9) telomerase inhibition (10) for the treatment of thritis, Crohn's disease, irritable bowel syndrome, adult respiratory distress syndrome, chronic obstructive pulmony disease, or Alzheimer's disease (11). Moreover, due to their biological properties, which mainly depend on the nature and position of substituents, pyridopyrimidine derivatives e phmaceutically active (12­17), including bactericidal (13), anticancer (14) and anti-inflammatory (17) activity. This prompted us to synthesize and identify new compounds derived from pyrido[2,3-d]pyrimidin-4-ones and to screen them for analgesic and anti-inflammatory activities. EXPERIMENTAL All melting points were measured using an Electrothermal IA 9100 appatus (Shimadzu, Japan) (Table I). 1H NMR (Table II) and 13C NMR spectra (Table III) were recorded on JEOL EX-270 and JEOL ECA-500 (Jeol, Japan) and chemical shifts were expressed as d values against Si(CH3)4 as internal standd. IR spectra were recorded as KBr pellets on a Perkin-Elmer 1430 spectrometer (USA). Mass spectra (Table II) were recorded on a Hewlett-Packd-5988A GC/MS (USA) at ionization potential of 70 eV. Synthesis of 5-yl-8-ylmethylene-7,8-dihydro-2-thioxo-6H-cyclopenta[5,6]pyrido-[2,3-d]-pyrimidin-4(H)-ones (1a-c) The title compounds were preped according to El-Gazz et al. (18). Synthesis of 5-yl-8-ylmethylene-2-hydrazino-7,8-dihydro-6H-cyclopentena-[5,6]-pyrido[2,3-d]pyrimidin-4(H)-one (2a-c). General procedure A suspension of compound 1a-c (0.01 mol) in hydrazine hydrate (99­100 %) (25 mL) was stirred under reflux. The insoluble solid went into solution within 10 minutes with copious evolution of mercaptan to form a cle solution. After 30 minutes, heating was H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. continued for 8 h and the reaction mixture was allowed to cool to room temperature. The solid sepated was filtered off, washed with ethanol and dried to produce 2a-c. 5-Phenyl-8-phenylmethylene-2-hydrazino-7,8-dihydro-6H-cyclopentena[5,6]pyrido-[2,3-d] pyrimidin-4(H)-one (2a). ­ Compound 2a was obtained from 1a as a yellow powder which was crystallized from DMF. 5-(4-Chlorophenyl)-8-(4-chlorophenylmethylene)-2-hydrazino-7,8-dihydro-6H-cyclo-penta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (2b). ­ Compound 2b was obtained from 1b as a yellow powder which crystallized from dioxane. 5-(4-Methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-hydrazino-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (2c). ­ Compound 2c was obtained from 1c as a yellow powder crystallized from ethanol/dioxane (1:1). Synthesis of 5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-acethydrazido-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (3) A solution of compound 2c (0.01 mol) in glacial acetic acid, was refluxed for 3 h. The reaction mixture was allowed to cool to room temperature and was poured into cold water (100 mL). The solid formed was collected by filtration, dried and crystallized from ethanol (dk yellow powder). Synthesis of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4a) A mixture of 2c (0.01 mol) and formic acid (10 mL) and 2 mL of concentrated hydrochloric acid was heated under reflux for 8 h. The reaction mixture was allowed to cool to room temperature and was poured into water (100 mL). The solid formed was collected by filtration, washed with ethanol (20 mL), dried and crystallized from DMF as an orange powder. Synthesis of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-3-methyl-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4b) Method A. ­ A mixture of 2c (0.01 mol) and glacial acetic acid (50 mL) was stirred under reflux for 10 h (TLC). The reaction mixture was allowed to cool to room temperature an was then poured into water (100 mL). The solid formed was collected by filtration, washed with ethanol (20 mL), dried, and crystallized from dioxane as an orange powder. Method B. ­ A mixture of 3 (0.01 mol) and glacial acetic acid (30 mL) was stirred under reflux for 7 h (TLC). The reaction mixture was allowed to cool to room temperature and was then poured into water (100 mL). The solid formed was collected by filtration, washed with ethanol (20 mL) and crystallized. Synthesis of 3-amino-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4c) A mixture of 2c (0.01 mol) and potassium thiocyanate (0.15 mol) was heated under reflux in glacial acetic acid (30 mL) for 6 h. The reaction mixture was allowed to cool to room temperature and was poured into water. The precipitate formed was collected by filtration, dried and crystallized from ethanol/dioxane (2:1) as a yellow powder. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Synthesis of 3-yl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4d-f). General procedure A mixture of compound 7a-c (0.01 mol), anhydrous sodium acetate (1.64 g, 0.02 mol) and bromine (1.60 g, 0.01 mol) was stirred under reflux in glacial acetic acid (30 mL) in a water-bath at 80 °C for 20 h (under TLC control). The reaction mixture was allowed to cool to room temperature, was poured into water (100 mL) and the solid formed was collected by filtration and crystallized from appropriate solvent to afford 4d-f. 6-(4-Methoxyphenyl)-9-(4-methoxyphenylmethylene)-3-phenyl-1,7,8,9-tetrahydro-cyclopen ta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4d). ­ Compound 4d was obtained from 7a, as a yellow powder crystallized from dioxane. 3-(4-Chlorophenyl)-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4e). ­ Compound 4e was obtained from 7b as a yellow powder crystallized from dioxane. 3,6-Di-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclo-penta[5,6] pyrido[2,3-d][1,2,4] triazolo[4,3-a]pyrimidin-5(H)-one (4f). ­ Compound 4f was obtained from 7c as a yellow powder which was crystallized from DMF. Synthesis of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta-[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (5a,b). General procedure To a wmed ethanolic sodium ethoxide solution (preped by dissolving 0.01 mol of sodium metal in 30 mL ethanol), each of 4a,b (0.01 mol), was added, the heating was continued for 30 min and the mixture was allowed to cool to room temperature. Then methyl iodide (0.012 mol) was added. The mixture was stirred under reflux for 3 h, cooled to room temperature and poured into cold water (100 mL). The solid precipitated was filtered off, washed with water and dried to produce 5a,b. 1-Methyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (5a). ­ Compound 5a was obtained from 4a (10 mmol) and methyl iodide (0.012 mol) as yellow crystals crystallized from dioxane. 1,3-Dimethyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (5b). ­ Compound 5b was obtained from 4b (10 mmol) and methyl iodide (0.012 mol) as a yellow powder, crystallized from dioxane. Synthesis of 1-amino-2-methyl- or phenyl-6-(4-methoxyphenyl)-9-(4-methoxyphenyl-methylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidin-5(H)-one (6a,b). General procedure A mixture of compound 2c (0.01 mol) and chloroacetone or 2-bromoacetophenone (0.01 mol) was heated under reflux for 12 h in dry xylene (30 mL). The solid that sepated upon cooling was filtered off and crystallized from appropriate solvent to produce 6a,b. 1-Amino-2-methyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidin-5(H)-one (6a). ­ Compound 6a was obtained from compound 2c (0.01 mol) and chloroacetone (0.01 mol) as white crystals crystallized from ethanol. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. 1-Amino-2-phenyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidin-5(H)-one (6b). ­ Compound 6b was obtained from compound 2c (0.01 mol) and 2-bromoacetophenone (0.01 mol) as a yellow powder crystallized from ethanol. Synthesis of 2-ylmethylenehydrazone-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (7a-c). General procedure A mixture of 2c (0.01 mol), the appropriate omatic aldehyde (0.01 mol) and anhydrous sodium acetate (0.02 mol) was stirred under reflux in glacial acetic acid (30 mL) for 30 min. The reaction mixture was allowed to cool to room temperature. The solid formed was filtered off and crystallized from appropriate solvent to produce 7a-c. 2-Phenylmethylenehydrazone-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (7a). ­ Compound 7a was obtained from compound 2c (0.01 mol) and benzaldehyde (0.01 mol) as pale yellow crystals crystallized from DMF. 2-(4-Chlorophenyl)methylenehydrazone-5-(4-methoxyphenyl)-8-(4-methoxyphenyl-methylene)7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (7b). ­ Compound 7b was obtained from compound 2c (0.01 mol) and 4-chlorobenzaldehyde (0.01 mol) as pale yellow crystals crystallized from DMF. 2-(4-Methoxyphenyl)methylenehydrazone-5-(4-methoxyphenyl)-8-(4-methoxyphenyl-methylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (7c). Compound 7c was obtained from compound 2c (0.01 mol) and 4-methoxybenzaldehyde (0.01 mol) as a yellow powder which was crystallized from DMF. Synthesis of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydro-cyclopenta[5,6]pyrido[2,3-d][1,2,3,4]tetrazolo[4,5-a]pyrimidin-5(H)-one (8) To an ice-cold solution of compound 2c (0.01 mol) in glacial acetic acid (10 mL), a solution of sodium nitrite (0.15 mol) in a small amount of water was added dropwise in an ice bath at ­5 °C. The reaction mixture was allowed to stand overnight at room temperature and was then poured into water (100 mL). The solid precipitated was filtered off and crystallized from ethanol as a yellow powder. Synthesis of 2-amino-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (9) To a well stirred solution of compound 8 (0.01 mol) in glacial acetic acid (30 mL), activated zinc dust (5.00 g) was added portion-wise at room temperature over a period of 30 min. Stirring was continued for additional 3 h. Thereafter, the reaction mixture was heated on a water bath (80­90 °C) for 3 h. The reduction progress was monitored by TLC. After allowing the reaction mixture to cool to room temperature, it was poured into cold water (100 mL). The insoluble solid which sepated was filtered, washed with water and dried. The crude solid was extracted with hot diethyl ether and the solid obtained after the removal of ether under reduced pressure was crystallized from ethanol. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Synthesis of 2-(3-amino-5-hydroxypyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10a) To a wm ethanolic sodium ethoxide solution (preped by dissolving (0.01 mol) sodium metal in absolute ethanol (30 mL), compound 2c (0.01 mol) and ethyl cyanoacetate (0.01 mol) were added. The mixture was stirred under reflux for 8 h, the reaction mixture was allowed to cool to room temperature was then poured into cold water (100 mL) and neutralized with acetic acid. The solid product precipitated was filtered off, washed with water, ethanol, dried and crystallized from dioxane as a pale yellow powder. Synthesis of 2-(sub-pyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10b,c). General procedure A mixture of compound 2c (0.01 mol) and b-diketone (0.01 mol) in absolute ethanol (30 mL) was stirred under reflux for 5 h. The reaction mixture was allowed to cool to 0 °C for 3 h, the precipitate was filtered off, dried and crystallized from an appropriate solvent to produce 10b,c. 2-(3,5-Dimethyl-pyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10b). ­ Compound 10b was obtained from 2c (0.01 mol) with pentan-2,4-dione (0.01 mol) as pale light crystals crystallized from dioxane. 2-(3,5-Dimethyl-4-chloropyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10c). ­ Compound 10c was obtained from 2c with 3-chloropentan-2,4-dione (0.01 mol) as a light yellow powder crystallized from ethanol. Synthesis of 2-[ethyl-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6Hcyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one acetate hydrazone (11) A mixture of compound 2c (0.01 mol) and ethyl acetoacetate (0.01 mol) was refluxed in absolute ethanol (30 mL) for 6 h. The reaction mixture was allowed to cool to room temperature and the solid precipitate produced was filtered off and crystallized from ethanol as a pale brown powder. Synthesis of 5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-(3-methyl-4H-pyrazol-5-one-1-yl)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (12) Method A. ­ A solution of compound 2c (0.01 mol) and ethyl acetoacetate (0.01 mol) in sodium ethoxide solution (preped by dissolving 0.01 mol of sodium metal in 30 mL absolute) ethanol was heated under reflux with stirring for 6 h. The reaction mixture was allowed to cool and was poured into cold water (100 mL) and neutralized by acetic acid, whereby a solid was precipitated, filtered off and crystallized from ethanol to produce 12 as a yellow powder in 65% yield (m.p. 257­259 °C, dec.). Method B. ­ A solution of compound 11 (0.01 mol) was heated under reflux with sodium ethoxide solution (preped by dissolving 0.01 mol of sodium metal in 30 mL absolute ethanol) for 3 h. The reaction mixture was allowed to cool, was poured into water (100 mL) and neutralized by acetic acid; the precipitate formed was filtered off and crystallized from ethanol. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Synthesis of 3-thioxo-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,2,8,9-tetrahydro-7H-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (13) To a wmed ethanolic sodium hydroxide solution preped by dissolving 0.01 mol of sodium hydroxide in 50 mL ethanol, compound 2c (0.01 mol) and excess cbon disulphide (10 mL) were added. The mixture was heated on a water-bath at 80 °C under reflux for 12 h, was then allowed to cool to room temperature, poured onto water (100 mL), neutralized by dilute acetic acid and the formed precipitate was filtered off and dried. The product was crystallized from ethanol as a yellow powder. Phmacological screening Animals. ­ Adult male Sprague-Dawley rats, weighing 150­200 g, were used for anti-inflammatory and ulcerogenic activity testing, and Swiss albino mice of both sex, weighing 25­30 g, were used for analgesic activity testing. International principles and local regulations concerning the ce and use of laboratory animals were observed (19). The animals had free access to standd commercial diet and water ad libitum and were kept in rooms maintained at 22 ± 1 °C with a 12 h light dk cycle. The experimental protocol was approved by the Animal Ethics Committee of the National Resech Center, Cairo, Egypt. Anti-inflammatory assay. ­ The compounds synthesized were evaluated for their anti-inflammatory activity using the crageenean induced hind paw edema method (20). The animals were randomly allocated to groups of six animals each and were fasted for 24 h before the experiment, with free access to water. Control group received only 0.5% (m/V) cboxymethyl cellulose solution. Standd drug ibuprofen was administrated orally at a 30 mg kg­1 dose. Crageenean solution in saline (1%, 0.1 mL) was injected subcutaneously into the sub-plant region of the left hind paw of each rat, one hour after the administration of the test compounds or standd drug (30 mg kg­1). The left hind paw volume was measured before and after 3 and 4 h of crageenean treatment by means of a plethysmometer. The percent edema inhibition was calculated from the mean effect in the control and treated animals. Each value represents the mean ± SEM relative to the standd and data were analyzed by ANOVA followed by Dunnett's test. Analgesic assay. ­ Analgesic activity was evaluated by the tail immersion method (21). Swiss albino mice allocated to different groups consisting of six animals each were used for the experiment. Analgesic activity was evaluated after oral administration of the test compounds at a dose of 30 mg kg­1 of ibuprofen and the test compounds. Test compounds and the standd drug were administered orally as a suspension in cboxylmethyl cellulose solution in water (0.5%, m/V). The analgesic activity was assessed before and after 4 h following administration of test compounds and standd drug. The lower 5-cm portion of the tail was gently immersed into thermostatically controlled water at 55 ± 0.5 °C. The time in seconds for tail withdrawal from water was taken to be the reaction time with a cut off time of immersion, set at 100 seconds for both control as well as treated groups of animals. Ulcerogenicity. ­ Acute ulcerogenicity was determined according to the method of Cioli et al. (22). The animals were allocated to different groups consisting of six animals each. Ulcerogenic activity was evaluated after oral administration of the test compounds H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. at a dose of 30 mg kg­1. Control group received only 0.5% (m/V) cboxymethyl cellulose solution. After the drug treatment, the rats were fed normal diet for 17 h and were then sacrificed. The stomach was removed and opened along the greater curvature, washed with distilled water and cleaned gently by dipping in normal saline. The mucosal damage was examined by means of a magnifying glass. Mucosal damage was assessed for each stomach according to the following scoring system: 0.5: redness, 1.0: spot ulcers, 1.5: hemorrhagic streaks, 2.0: 3 < ulcers £ 5, 3.0: ulcers > 5. The mean score of each treated group minus the mean score of the control group was regded as the severity index of gastric mucosal damage. RESULTS AND DISCUSSION 5-yl-8-ylmethylene-7,8-dihydro-2-thioxo-6H-cyclopenta[5,6]pyrido[2,3-d]-pyrimidin-4(H)-ones (1a-c) were synthesized previously (18). Beside the correct values in elemental analyses and spectral data, structures were established chemically. Upon treatment with hydrazine hydrate (Scheme 1), thay gave 5-yl-8-ylmethylene-2-hydrazino-7,8-dihydro-6H-cyclopenta[5,6]pyrido-[2,3-d] pyrimidin-4(H)-ones (2a-c), with the evolution of mercaptan. O NH N H N H S H N2H4·H2O O NH N H NH2 1a-c : a = C6H5 b = 4-ClC6H4 c = 4-OCH3C6H4 2a-c Scheme 1 Compound 2c could be considered as a stting material for the synthesis of new polynucle heterocycles such as azolopyridopyrimidines, as well as the synthesis of some pyrazolopyridopyrimidine derivatives. Thus, heating compound 2c with aliphatic acids, namely, formic and acetic acid, resulted in the formation of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydro-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo-[4,3-a]pyrimidin-5(H)-ones (4a,b). On the other hand, heating of compound 2c with acetic acid for 3 hours only yielded 2-acetylhydrazino derivative 3, which on further long heating with acetic acid gave 4b. Moreover, alkylation of 4a,b in ethanolic sodium ethoxide solution with methyl iodide afforded 1-methyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a] pyrimidin-5(H)-ones (5a,b) as shown in Scheme 2. All the synthesized compounds were chacterized by their physical, chemical and spectral data (Tables I­III). IR spectra of compounds 4a,b showed the presence of chacteristic absorption peaks ound 3385­3400 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Table I. Physical and chemical properties of synthesized compounds Mol. formula (Mr) C23H19N5O (381.4) C23H17Cl2N5O (450.3) C25H23N5O3 (441.5) C27H25N5O4 (483.5) C26H21N5O3 (451.5) C27H23N5O3 (465.5) C26H22N6O3 (466.5) C32H25N5O3 (527.5) C32H24ClN5O3 (562.1) C33H27N5O4 (557.6) C27H23N5O3 (465.5) C28H25N5O3 (479.5) C28H25N5O3 (479.5) C33H27N5O3 (541.6) C32H27N5O3 (529.6) C32H26ClN5O3 (564.1) C33H29N5O4 (559.6) C25H20N6O3 (452.5) C25H22N4O3 (426.4) C28H24N6O4 (508.5) Found/calcd. (%) N 72.42 72.37 61.34 61.29 68.01 68.03 67.06 67.04 69.16 69.13 69.66 69.63 66.94 66.91 72.85 72.83 68.38 68.35 71.08 71.05 69.66 69.62 70.13 69.98 70.13 70.09 73.17 73.19 72.57 72.54 68.14 68.09 70.83 70.79 66.36 66.34 70.40 70.38 66.13 66.09 H 5.02 5.00 3.81 3.79 5.25 5.28 5.21 5.18 4.69 4.71 4.98 4.96 4.75 4.69 4.78 4.75 4.30 4.27 4.88 4.87 4.97 4.98 5.25 5.20 5.26 5.19 5.02 4.99 5.14 5.09 4.65 4.62 5.22 5.23 4.46 4.47 5.20 5.17 4.76 4.74 C 18.36 18.29 15.55 15.58 15.86 15.79 14.48 14.51 15.51 15.48 15.04 15.07 18.02 18.04 13.27 13.25 12.46 12.43 12.56 12.59 15.04 15.01 14.60 14.58 14.60 14.63 12.93 12.94 13.22 13.18 12.41 12.39 12.51 12.48 18.57 18.59 13.14 13.09 16.53 16.49 Compd. No. 2a 2b 2c 3 4a 4b 4c 4d 4e 4f 5a 5b 6a 6b 7a 7b 7c 8 9 10a Yield (%) 86 89 87 75 67 64 73 60 63 64 68 70 68 65 89 83 81 53 49 73 M.p. (°C) 248­250 233­236 282­284 267­270 309­311 339­341 336­338 320­322 300­302 343­345 278­280 263­265 264­266 248­250 295­297 288­290 330­332 260­262 280­282 258­260 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. 10b 10c 11 12 13 240­242 266­268 235­237 257­259 311­313 C30H27N5O3 (505.5) C30H26ClN5O3 (540.0) C31H31N5O5 (553.6) C29H25N5O4 (507.5) C26H21N5O3S (483.5) Table II. Spectral data of synthesized compounds Compd. No. 2a 1H NMR (d, ppm) IR (DMSO-d6) (n, cm­1) 3400 (br, NH), 2.05 (br, 2H, NH2), 2.71­2.75 (m, 2H, CH2), 2.84­2.95 (t, MS (m/z), 1687 (CO), 2H, CH2), 5.15 (br, NH), 7.07­7.11 (m, 2H, -H), 381 (M+) 7.32­7.39 (m, 3H, -H), 7.45­7.59 (m, 5H, -H) and 1625 (C=N) 8.22 (s, 1H, CH), 9.10 (br, NH) 3410 (brs, NH), 2.10 (br, 2H, NH2), 2.73­2.76 (m, 2H, CH2), 2.80­2.92 (m, MS (m/z), 2H, CH2), 3.80 (br, NH), 6.98­7.05 (d, 2H, J = 8.43 Hz, 452 (M++2), 1686 (CO), 1640 (C=N) 450 (M+) -H), 7.10­7.19 (d, 2H, J = 8,42 Hz, -H), 7.43­7.50 (d, 2H, J = 8.40 Hz, -H), 7.54­7.60 (d, 2H, J = 8.40 Hz, -H), 8.02 (s, 1H, CH), 12.00 (br, NH) (2NH, NH2, D2O exchangeable) 3395 (br, NH), 2.00 (br, 2H, NH2), 2.70­2.72 (m, 2H, CH2), 2.80­2.90 (m, MS (m/z), 2H, CH2), 3.80, 3.83 (2s, 6H, 2OCH3), 5.15 (br, NH), 1689 (CO), 441 (M+) 1646 (C=N) 6.92­6.98 (d, 2H, J = 8.41 Hz, -H), 7.00­7.19 (d, 2H, J = 8.41 Hz, -H), 7.50­7.53 (d, 2H, J = 8.39 Hz, -H), 7.56­7.61 (d, 2H, J = 8.40 Hz, -H), 8.16 (s, 1H, CH), 11.50 (br, NH) (2NH, NH2, D2O exchangeable) 3400 (br, NH), 2.73­2.78 (m, 2H, CH2), 2.82­2.91 (m, 2H, CH2), 2.86 (s, MS (m/z), 1688, 1680 3H, CH3), 3.82, 3.86 (2s, 6H, 2OCH3), 6.96 (d, 2H, J = 468 (2CO), 8.39 Hz, -H), 7.11 (d, 2H, J = 8.40 Hz, -H), 7.49 (d, (M+-CH3) 2H, J = 8.39 Hz, -H), 7.60 (d, 2H, J = 8.40 Hz, -H), 1620 (C=N) 8.19 (s, 1H, CH), 8.90, 9.30, 11.10 (3br, 3NH, D2O exchangeable) 3385 (br, NH), 2.72­2.76 (m, 2H, CH2), 2.85­2.91 (m, 2H, CH2), 3.83, MS (m/z), 1687 (CO), 3.89 (2s, 6H, 2OCH3), 6.98­7.04 (d, 2H, -H), 7.08­7.15 451 (M+) 1615 (C=N) (d, 2H, -H), 7.45­7.50 (d, 2H, -H), 7.56­7.63 (d, 2H, -H), 8.12 (s, 1H, CH), 8.54 (s, 1H, triazole proton) 9.50 (br, NH, D2O exchangeable) 3400 (br, NH), 2.25 (s, 3H, CH3), 2.71­2.77 (m, 2H, CH2), 2.85­2.91 (m, MS (m/z), 1685 (CO), 2H, CH2), 3.86, 3.91 (2s, 6H, 2OCH3), 7.04 (d, 2H, J = 465 (M+) 1620 (C=N) 8.39 Hz, -H), 7.15 (d, 2H, J = 8.38 Hz, -H), 7.47 (d, 2H, J = 8.38 Hz, -H), 7.59 (d, 2H, J = 8.38 Hz, -H), 8.08 (s, 1H, CH), 10.20 (br, NH, D2O exchangeable) Mass (m/z) 2b 2c 4a 4b H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. 4c MS (m/z), 466 (M+) 4d 4e 4f 5a MS (m/z), 465 (M+) 5b MS (m/z), 479 (M+) 6a 6b MS (m/z). 541 (M+) 7a MS (m/z), 529 (M+) 3420 (br, NH), 2.74­2.78 (m, 2H, CH2), 2.84­2.90 (m, 2H, CH2), 3.85, 1686 (CO), 3.88 (2s, 6H, 2OCH3), 5.54 (br, NH2), 6.99 (d, 2H, J = 1646 (C=N) 8.38 Hz, -H), 7.10 (d, 2H, J = 8.39 Hz, -H), 7.49 (d, 2H, J = 8.40 Hz, -H), 7.61 (d, 2H, J = 8.40 Hz, -H), 8.22 (s, 1H, CH), 10.50 (br, NH) (NH, NH2 D2O exchangeable) 3410 (br, NH), 2.73­2.82 (m, 2H, CH2), 2.84­2.92 (m, 2H, CH2), 3.85, 3.90 (2s, 6H, 2OCH3), 6.95­6.99 (d, 2H, -H), 7.03­7.15 1698 (CO), (m, 2H, -H), 7.18­7.21 (d, 2H, -H), 7.33­7.43 (m, 1615 (C=N) 3H, -H), 7.54­7.58 (d, 2H, -H), 7.60­7.64 (d, 2H, -H), 8.20 (s, 1H, CH), 10.70 (br, NH, D2O exchangeable) 3420 (br, NH), 2.72­2.78 (m, 2H, CH2), 2.81­2.89 (m, 2H, CH2), 3.84, 3.89 (2s, 6H, 2OCH3), 6.94­7.00 (d, 2H, -H), 7.03­7.12 1695 (CO), (d, 2H, -H), 7.16­7.22 (d, 2H, -H), 7.38­7.42 (d, 2H, 1595 (C=N) -H), 7.50­7.58 (d, 2H, -H), 7.62­7.67 (d, 2H, -H), 8.14 (s, 1H, CH), 11.00 (br, NH, D2O exchangeable) 3400 (br, NH), 2.74­2.80 (m, 2H, CH2), 2.83­2.90 (m, 2H, CH2), 3.82, 3.85, 3.89 (3s, 9H, 3OCH3), 6.90­6.96 (d, 2H, -H), 1700 (CO), 7.01­7.11 (d, 2H, -H), 7.15­7.20 (d, 2H, -H), 1640 (C=N) 7.36­7.40 (d, 2H, -H), 7.52­7.57 (d, 2H, -H), 7.59­7.65 (d, 2H, -H), 8.18 (s, 1H, CH), 11.30 (br, NH, D2O exchangeable) 3385 (br, NH), 2.74­2.78 (m, 2H, CH2), 2.86­2.94 (m, 2H, CH2), 3.49 (s, 1687 (CO), 3H, N-CH3), 3.84, 3.90 (2s, 6H, 2OCH3), 7.00 (d, 2H, J = 1615 (C=N) 8.38 Hz, -H), 7.12 (d, 2H, J = 8.42 Hz, -H), 7.47 (d, 2H, J = 8.39 Hz, -H), 7.58 (d, 2H, J = 8.41 Hz, -H), 8.19 (s, 1H, CH), 8.49 (s, 1H, triazole proton) 1688 (CO), 2.23 (s, 3H, CH3), 2.73­2.79 (m, 2H, CH2), 2.83­2.90 (m, 1615 (C=N) 2H, CH2), 3.67 (s, 3H, N-CH3), 3.88, 3.93 (2s, 6H, 2OCH3), 7.07 (d, 2H, J = 8.37 Hz, -H), 7.14 (d, 2H, J = 8.38 Hz, -H), 7.48 (d, 2H, J = 8.40 Hz, -H), 7.63 (d, 2H, J = 8.40 Hz, -H), 8.13 (s, 1H, CH) 3405 (br, NH), 2.35 (s, 3H, CH3), 2.74­2.78 (m, 2H, CH2), 2.84­2.91 (m, 2H, CH2), 3.86, 3.90 (2s, 6H, 2OCH3), 5.50 (br, NH2, D2O 1685 (CO), exchangeable), 7.01 (d, 2H, J = 8.41 Hz, -H), 7.14 (d, 1610 (C=N) 2H, J = 8.40 Hz, -H), 7.48 (d, 2H, J = 8.39 Hz, -H), 7.61 (d, 2H, J = 8.40 Hz, -H), 8.13 (s, 1H, imidazole proton), 8.21 (s, 1H, CH) 3410 (brs, NH), 2.72­2.76 (m, 2H, CH2), 2.85­2.90 (m, 2H, CH2), 3.87, 1686 (CO), 3.91 (2s, 6H, 2OCH3), 5.62 (br, NH2, D2O exchangeable), 1642 (C=N) 6.96­7.05 (m, 4H, -H), 7.15 (d, 2H, J = 8.42 Hz, -H), 7.34­7.43 (m, 3H, -H), 7.50 (d, 2H, J = 8.41 Hz, -H), 7.62 (d, 2H, J = 8.39 Hz, -H), 8.09 (s, 1H, imidazole proton), 8.19 (s, 1H, CH) 3980 (brs, NH), 2.75­2.81 (m, 2H, CH2), 2.87­2.94 (m, 2H, CH2), 3.88, 3.93 (2s, 6H, 2OCH3), 7.02 (d, 2H, J = 8.39, Hz, -H), 1687 (CO), 1625 (C=N) 7.13­7.20 (m, 4H, -H), 7.30­7.38 (m, 3H, -H), 7.48 (d, 2H, J = 8.38 Hz, -H), 7.62 (d, 2H, J = 8.40 Hz, -H), 8.19 (s, 1H, CH), 8.30 (s, 1H, azomethine proton), 9.00, 10.80 (br, 2H, 2NH, D2O exchangeable) 369 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. 7b 7c 10a 10b 10c 2.71­2.77 (m, 2H, CH2), 2.80­2.86 (m, 2H, CH2), 3.83, 3.88 (2s, 6H, 2OCH3), 6.97 (d, 2H, J = 8.37 Hz, -H), 7.08 (d, 2H, J = 8.38 Hz, -H), 7.26 (d, 2H, J = 8.40 Hz, -H), 7.51 (d, 2H, J = 8.41 Hz, -H), 7.59 (d, 2H, J = 8.42 Hz, -H), 7.69 (d, 2H, J = 8.40 Hz, -H), 8.06 (s, 1H, azomethine proton), 8.17 (s, 1H, CH), 9.70, 11.00 (2brs, 2NH, D2O exchangeable) 3375 (brs, NH), 2.69­2.76 (m, 2H, CH2), 2.83­2.89 (m, 2H, CH2), 3.79, 3.86, 3.91 (3s, 9H, 3OCH3), 7.09­7.10 (d, 2H, -H), 1676 (CO), 7.13­7.17 (d, 2H, -H), 7.34­7.40 (d, 2H, -H), 1605 (C=N) 7.43­7.49 (d, 2H, -H), 7.52­7.57 (d, 2H, -H), 7.65­7.70 (d, 2H, -H), 8.05 (s,1H, azomethine proton), 8.17 (s, 1H, CH), 9.25, 10.30 (brs, 2NH, D2O exchangeable) 3340 (br, NH), 2.71­2.78 (m, 2H, CH2), 2.82­2.90 (m, 2H, CH2), 3.86, MS (m/z), 2320 (N3), 3.90 (2s, 6H, 2OCH3), 6.93­6.98 (d, 2H, -H), 7.11­7.17 452 (M+) (d, 2H, -H), 7.37­7.42 (d, 2H, -H), 7.56­7.60 (d, 2H, 1702 (CO), -H), 8.21 (s, 1H, CH), 11.60 (br, NH, D2O exchange1625 (N=N), able) 1585 (C=N) 3410 (br, NH), 2.75­2.82 (m, 2H, CH2), 2.84­2.93 (m, 2H, CH2), 3.86, MS (m/z), 1687 (CO), 3.89 (2s, 6H, 2OCH3), 7.03­7.10 (d, 2H, -H), 7.16­7.22 426 (M+) 1589 (C=N) (d, 2H, -H), 7.38­7.42 (d, 2H, -H), 7.58­7.64 (d, 2H, -H), 8.23 (s, 1H, CH), 8.56 (br, 2H, NH2), 11.30 (br, NH) (NH2, NH, D2O exchangeable) 3480 (br, OH), 2.74­2.82 (m, 2H, CH2), 2.86­2.93 (m, 2H, CH2), 3.55 (br, MS (m/z), 3318 (brs, NH), 1H, OH coupled with H2O of DMSO), 3.85, 3.90 (2s, 6H, 508 (M+) 1687, (CO), 2OCH3), 5.67 (br, NH2, D2O exchangeable), 6.68 (s, 1H, pyrazole proton), 7.00 (d, 2H, J = 8.41 Hz, -H), 7.26 1601 (C=N) (d, 2H, J = 8.40 Hz, -H), 7.34 (d, 2H, J = 8.40 Hz, -H), 7.53 (d, 2H, J = 8.40 Hz, -H), 8.14 (s, 1H, CH), 9.10 (brs, NH, D2O exchangeable) 3380 (br, NH), 2.21 (s, 3H, CH3), 2.68­2.73 (m, 2H, CH2), 2.86 (s, 3H, MS (m/z), 1690 (CO), CH3), 2.89­2.96 (m, 2H, CH2), 3.85, 3.89 (2s, 6H, 505 (M+) 1625 (C=N) 2OCH3), 6.25 (s, 1H, pyrazole proton), 7.11 (d, 2H, J = 8.38 Hz, -H), 7.31 (d, 2H, J = 8.39 Hz, -H), 7.45 (d, 2H, J = 8.40 Hz, -H), 7.64 (d, 2H, J = 8.40 Hz, -H), 8.17 (s, 1H, CH), 10.20 (br, NH, D2O exchangeable) 3380 (br, NH), 2.19 (s, 3H, CH3), 2.67­2.74 (m, 2H, CH2), 2.87 (s, 3H, MS (m/z), CH3), 2.90­2.97 (m, 2H, CH2), 3.86, 3.90 (2s, 6H, 542 (M++2), 1690 (CO), 541 (M++1), 1625 (C=N) 2OCH3), 7.12 (d, 2H, J = 8.39 Hz, -H), 7.33 (d, 2H, J = 540 (M+) 8.39 Hz, -H), 7.47 (d, 2H, J = 8.41 Hz, -H), 7.65 (d, 2H, J = 8.41 Hz, -H), 8.09 (s, 1H, CH), 10.35 (br, NH, D2O exchangeable) 3250 (br, NH), 1.24­1.31 (t, 3H, CH3), 2.15 (s, 3H, CH3), 2.71­2.78 (m, MS (m/z), 1730, 1685 2H, CH2), 2.85­2.92 (m, 2H, CH2), 3.42 (s, 2H, CH2), 553 (M+) (2CO), 3.84, 3.86 (2s, 6H, 2OCH3), 4.00­4.10 (q, 2H, CH2), 7.01 (d, 2H, J = 8.39 Hz, -H), 7.13 (d, 2H, J = 8.40 Hz, 1580 (C=N) -H), 7.45 (d, 2H, J = 8.39 Hz, -H), 7. 62 (d, 2H, J = 8.41 Hz, -H), 8.17 (s, 1H, CH), 9.40, 11.00 (2br, 2NH, D2O exchangeable) MS 566 565 564 3395 (br, NH), (m/z), (M++2), 1678 (CO), (M++1), 1636 (C=N) (M+) H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. MS (m/z), 507 (M+) MS, [M+], m/z 482 (100%) 2.03 (s, 3H, CH3), 2.78­2.83 (m, 2H, CH2), 2.86­2.92 (m, 2H, CH2), 3.87, 3.92 (2s, 6H, 2OCH3), 4.31 (s, 2H, CH2), 7.06 (d, 2H, J = 8.36 Hz, -H), 7.35 (d, 2H, J = 8.38 Hz, -H), 7.45 (d, 2H, J = 8.39 Hz, -H), 7.70 (d, 2H, J = 8.38 Hz, -H), 8.23 (s, 1H, CH), 10.30 (brs, NH, D2O exchangeable) 3465 (br, NH), 2.79­2.85 (m, 2H, CH2), 2.88­2.93 (m, 2H, CH2), 3.88, 3.93 (2s, 6H, 2OCH3), 7.07 (d, 2H, J = 8.38 Hz, -H), 1686 (CO), 7.38 (d, 2H, J = 8.39 Hz, -H), 7.48 (d, 2H, J = 8.41 Hz, 1620 (C=N) -H), 7.68 (d, 2H, J = 8.42 Hz, -H), 8.16 (s, 1H, CH), 10.00, 11.50 (2brs, 2NH, D2O exchangeable) 3400 (brs, NH), 1697, 1684 (2CO), 1550 (C=N) cm­1 (N-H stretching). Also, 1H NMR spectra of compounds 4a,b showed broad bands at d 9.50 and 10.20 ppm, while IR and NMR spectra of compound 5a,b revealed the absence of NH absorption peaks (Table II). O NH N H N O N N H N N NH2 R AcOH 3h NHNHCOCH3 O R N N N N N CH3 6a,b a: R = CH3 b: R = C6H5 O N H N H ' N H 2c 'CHO N H Br2/NaOAc 5a,b 7a-c a: R = H b: R = CH3 CH3I HCOOH (a) AcOH (b) KSCN (c) a: ' = C6H5 b: ' = 4-ClC6H4 c: ' = 4-OCH3C6H O ' N N N H O R N N N H H N H 4a-c 4d-f a: R = H c: R = NH2 e: ' = 4-ClC6H4 b: R = CH3 d: ' = C6H5 f: ' = 4-OCH3C6H4 = 4-OCH3C6H4 Scheme 2 371 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Also, the 2-hydrazino- derivative 2c reacted with potassium thiocyanate in boiling acetic acid to give 3-amino-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8, 9-tetrahydro-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4c). Beside correct values in elemental analyses, the spectral data of 4c e in agreement with the assigned structure (Scheme 2). When compound 2c was heated under reflux with a-haloketones, namely, chloroacetone or 2-bromoacetophenone in dry xylene, it yielded the respective 1-amino-6-yl-9-ylidene-1H,5H-imidazo[1',2'-a]cyclopenta[5,6]pyrido-[2,3-d]pyrimidin-5-one (6a,b). The 1H NMR spectrum of 6a, for example, showed that singlet signals at 2.35 ppm supported the methyl protons, two signals ound 2.74­2.91 ppm corresponded to the two methylene groups, two singlets ound 3.85­3.90 ppm due to the two methoxy groups and the broad absorption signal (D2O exchangeable) supported the amino group. In addition to the pyrazole proton at 8.13 ppm, the spectrum showed four doublet signals due to the p-substituted phenyl groups with the coupling constant ound 8.40 Hz and the methylenic proton at 8.21 ppm. Also, the 13C NMR showed that, in addition to the methyl group (18.39 ppm), two methylene groups (27.21 and 27.90 ppm), two methoxy groups (54.97 and 55.33 ppm) and cbonyl groups (163.8 ppm), eighteen lines ound 111.0­158.5 ppm corresponding to 22 sp2 cbon atoms were obtained (Table III). Table III. Compd. No. 2c 13C NMR of some new compounds 13C NMR (d, ppm) (DMSO-d6) 27.01, 27.95 (2C, 2CH2), 54.98, 55.17, (2C, 2OCH3), 108.5, 112.9, 113.1, 114.2, 124.4, 128.9, 129.5, 130.6, 130.7, 130.8, 132.9, 138.9, 148.2, 154.7, 158.3, 158.8 (16 line for 20 sp2 cbon atoms) and 163.9 (CO) 27.12, 27.93 (2C, 2CH2), 54.95, 55.21, (2C, 2OCH3), 110.2, 112.9, 113.8, 118.5, 125.4, 127.3, 129.1, 131.7, 132.3, 133.8, 134.9, 137.6, 147.5, 153.4, 155.3, 157.2, 158.3 (17 line for 21 sp2 cbon atoms) and 165.2 (CO) 13C-NMR: 4a 4c 27.11, 27.96 (2C, 2CH2), 54.96, 55.18, (2C, 2OCH3), 110.4, 112.3, 113.6, 118.2, 124.5, 127.9, 128.4, 129.3, 130.7, 130.2, 131.8, 134.9, 138.5, 148.1, 154.4, 158.2, 158.8 (17 line for 21 sp2 cbon atoms) and 163.5 (CO) 4f 27.11, 27.94 (2C, 2CH2), 54.96, 55.15, 56.23 (3C, 3OCH3), 108.3, 112.5, 113.5, 114.7, 124.7, 128.6, 129.5, 130.9, 131.2, 131.8, 132.3, 132.7, 134.8, 138.9, 140.2, 144.6, 148.2, 154.7, 167.0, 158.3, 158.8 (21 line for 27 sp2 cbon atoms) and 163.9 (CO) 18.39 (CH3), 27.21, 27.90 (2C, 2CH2), 54.97, 55.33, (2C, 2OCH3), 111.0, 112.7, 114.2, 118.6, 125.7, 127.7, 128.5, 129.5, 131.3, 132.5, 133.8, 135.6, 137.8, 147.4, 152.9, 154.3, 157.4, 158.5 (18 line for 22 sp2 cbon atoms) and 163.8 (CO) 24.31, 26.58 (2 CH2), 109.3, 127.0, 127.5, 127.6, 127.7, 127.8, 129.2, 129.4, 130.9, 132.1, 133.1, 136.6, 138.7, 150.5, 153.7, 158.4 (16 line for 20 sp2 cbon atoms), 163.8 (CO) and 174.2 (C=S) 6a Further, compound 2c gave the 2-ylmethylene hydrazone derivatives 7a-c when treated with the appropriate aldehyde in boiling glacial acetic acid. The latter compounds were cyclized when gently heated in a mixture of bromine and sodium acetate in acetic acid to afford 3-yltriazolo[4',3':1,2]cyclopentenopyrido[2,3-d]pyrimidines (4d-f). Beside H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. correct values in elemental analysis, the spectral data of 7a-c and 4d-f e in agreement with the assigned structures. The 1H NMR spectra revealed the absence of azomethine protons. Also, the formation of triazolopyridopyrimidine 4d-f from 7a-c may be accomplished via brominating the methylenic proton or N-3 of the pyrimidine ring followed by elimination of hydrogen bromide, as shown in Scheme 3. O N N H N Br N N H ' H 7a-c Br2 AcONa ­HBr 4d-f Scheme 3 Treatment of compound 2c with nitrous acid led to the formation of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]-pyrido[2,3-d][1, 2,3,4]tetrazolo[4,5-a]pyrimidin-5(H)-one (8) (Scheme 4). The IR spectrum of 8 displayed absorption bands at 3240 cm­1 (NH) and 1702 cm­1 (CO). The latter compound was reduced to 2-amino-5-(4-methoxyphenyl)-8-(4-methoxyphenyl-methylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidine-4(H)-one (9) by zinc dust and acetic acid. O N N H N N H N N Zn dust acetic acid H N N O NH NH2 = 4-OCH3C6H4 Scheme 4 5-(4-Methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-hydrazino-7,8-dihydro-6H-cyclopenta [5,6]pyrido[2,3-d]pyrimidin-4(H)-one (2c) reacted with b-cyano-ester, b-diketones and b-ketoesters to form 2-(1-pyrazolyl) derivatives. Thus, heating compound 2c with ethylcyanoacetate, pentane-2,4-dione and/or 3-chloropentane-2,4-dione, yielded the respective 2-(3,5-substituted-4-(un)substituted-pyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxy-phenyl-methylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-ones 10a-c, respectively (Scheme 5). Compound 2c condensed with ethyl acetoacetate upon heating in boiling ethanol to afford 2-[ethyl-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one]acetatehydrazone (11), which could be cyclized either by prolonged heating in ethanol or by heating in sodium ethoxide solution to give 5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-(3-methyl-4H-pyrazol-5-one-1-yl)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (12). Finally, heating 2c with cbon disulphide in ethanolic potassium hydroxide solution gave 3-thioxo-6-(4-methoxyphenyl)-9-(methoxyphenylmethylene)-1,2,8,9-tetrahydro373 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. O NH O NH CH3 N H N R N N N H N 11 NH-N=CCH2COOC2H5 10a-c Method B 2c O NH a: R = OH R = NH2 X = H 1 b: R = R = CH3 X=H 1 c: R = R = CH3 X = Cl O N N H N N H S N H Method A N H N O N N CH3 CS2 = 4-OCH3C6H15 Scheme 5 Table IV. Percent inflammatory activity of the tested compounds (crageenean-induced paw odema test in rats) Inhibition (%)a 3 hours 27.29 ± 2.64 56.82 ± 2.53 52.28 ± 2.18 27.28 ± 2.73 75.01 ± 2.52 63.70 ± 1.93 75.00 ± 2.79 76.08 ± 2.67 31.80 ± 3.45 15.90 ± 2.73 52.27 ± 2.80 56.81 ± 1.94 ­ 75.00 ± 2.53 4 hours 28.27 ± 2.75b 56.81 ± 2.16b 54.55 ± 2.62b 29.54 ± 2.79b 77.26 ± 1.92b 63.62 ± 1.92 79.53 ± 3.72 82.79 ± 2.18 31.80 ± 3.69b 19.04 ± 2.24 52.27 ± ­ 79.54 ± 2.25 2.79b 59.09 ± 2.74b Potency 0.34 0.71 0.67 0.37 0.98 0.80 1.00 1.03 0.39 0.24 0.65 0.74 ­ 1.00 Compd. No. 2a 2b 2c 4a 4c 6a 9 10a 10b 11 12 13 Control Ibuprofen kg­1 Dose: 30 mg b.m. of the tested compound and standd drug. a Mean ± SEM (n = 6). b Significant difference relative to ibuprofen: p < 0.01. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. -7H-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (13) (Scheme 5). The IR spectrum of 13 displayed absorption bands at 3465­3400 cm­1 (2NH) and 1686 cm­1 (CO). The 13C NMR spectrum (DMSO-d6) of 13 showed two signals due to the sp3 cbon atoms, sixteen lines assigned to 20 sp2 cbon atoms and, in addition to the signal for the cbonyl group, the spectrum showed a strong peak corresponding to C=S at 174.2 ppm. The phmacological screening of the tested compounds showed anti-inflammatory activity ranging from 19.0 to 82.8% (Table IV), whereas the standd drug ibuprofen showed 79.5% inhibition after 4 h. The anti-inflammatory activity of 2-pyrazolyl-pyridopyrimidine derivatives 10a, 10b and 12 ranged from 31.8 to 82.8%. The aminopyrazolyl derivative 10a with hydroxyl and amino groups showed higher activity than the standd drug ibuprofen, whereas when these groups were replaced by a methyl group, the anti-inflammatory activity decreased. Also, it was observed that the triazolopyrido-pyrimidine derivatives 4a, 4c and 13 showed activity ranging from 29.5 to 77.3%, and 3-aminotriazolopyridopyrimidine 4c showed activity nely equivalent to the standd drug. 2-Aminopyrido[2,3-d]pyrimidine (9) showed activity (79.5%) equivalent to that of ibuprofen. Other tested compounds showed moderate anti-inflammatory activity. It is cle from Table IV that the presence of amino group in triazolo-/or pyrazolo-pyridopyrimidine increases the anti-inflammatory activity. Compounds 4c, 6a, 9 and 10a which showed anti-inflammatory activity compable or equal to that of the standd were further tested for their analgesic activity at a dose of 30 mg kg­1 ibuprofen (Table V). Compounds showed analgesic activity ranging from 58.4 to 72.7%, whereas the standd drug ibuprofen showed 69.5% inhibition. Compounds 4c, 9 and 10a showed the highest anti-inflammatory activity, 72.7, 59.3 and 70.2%, resp. The remaining compounds showed reduced analgesic activity. These compounds were further screened for their acute ulcerogenic activity. The tested compounds showed significant reduction in ulcerogenic activity ranging from 0.7 ± 0.15 to 1.06 ± 0.17, whereas Table V. Analgesic and ulcerogenic activity of the selected compounds Analgesic activity Group Pre-treatment normal (0 h) 1.40 ± 0.150 1.34 ± 0.137 1.34 ± 0.136 1.41 ± 0.150 1.80 ± 0.188 1.15 ± 0.060 ­ Post-treatment after (4 h) 2.42 ± 0117b 2.13 ± 0145b 2.12 ± 1.86 ± 0.146b 0.094b Inhibition (%)a 72.7 58.4 59.3 70.2 31.2 69.5 Potency 1.04 0.84 0.85 1.02 1.02 1.00 Ulcerogenic index 1.064 ± 0.17c 0.670 ± 0.21c 0.732 ± 0.18c 0.667 ± 0.15c 0.668 ± 0.22c 1.665 ± 0.25 ­ 4c 6a 9 10a 13 Ibuprofen Control kg­1 2.35 ± 0.180b 1.95 ± 0.097 ­ Dose: 30 mg b.m. of the tested compound and standd drug. a Mean ± SEM (n = 6). b Significant difference relative to ibuprofen: p < 0.0001. c Significant difference from ibuprofen: p < 0.05. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. the standd drug ibuprofen showed a severity index of 1.66 ± 0.25. Maximum reduction in ulcerogenic activity was found for compound 10a having the hydroxyl and amino groups of 2-pyrazolo-pyridopyrimidine ring (0.66 ± 0.15). The rest of the compounds also showed a better gastro interact safety profile than ibuprofen. CONCLUSIONS The present investigation offers new, rapid and effective procedures for the synthesis of new poly-condensed heterocyclic pyrido[2,3-d]pyrimidine ring systems. Compounds 3-amino-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-cyclopenta-[5,6]pyrido [2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4c), 1-amino-2-methyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-cyclopenta[5,6]pyrido[2,3-d]imidazolo-[1,2-a]pyrimidin-5 (H)-one (6a) and 2-amino-5-(4-methoxy-phenyl)-8-(4-methoxyphenyl-methylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (9) exhibited a potent anti-inflammatory activity whereas 2-(3-amino-5-hydroxypyrazol-1-yl)-pyrido[2,3-d]pyrimidin-4-one derivative 10a was the most active. Acknowledgements. ­ The authors e thankful to the National Resech Center for providing laboratory facilities, Micro-analytical Centre, Cairo University and the Phmacological Unit National Resech Centre, for microanalyses and phmacological screening of the compounds. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Acta Pharmaceutica de Gruyter

Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido(2,3- d )-pyrimidines

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Abstract

Acta Phm. 58 (2008) 359­378 10.2478/v10007-008-0024-1 Original resech paper HEND N. HAFEZ HEBAT-ALLAH S. ABBAS ABDEL-RAHMAN B. A. EL-GAZZ* National Resech Centre Photochemistry Deptment (Heterocyclic Unit), Dokki 12622 Cairo, Egypt New series of 2-hydrazino-7,8-dihydro-6H-cyclopenta[5,6] pyrido[2,3-d]pyrimidines and its 1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine, 1,7, 8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,3,4]tetrazolo[4,5-a]pyrimidine, 8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidine, 2-(pyrazol-1-yl)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidine derivatives were preped in order to obtain new compounds with potential anti-inflammatory and analgesic activity and low ulcerogenic effect. The compounds possessing potent anti-inflammatory activity were further tested for their analgesic and ulcerogenic activities. Compounds 3-amino-6-(4-yl)-9-(4-ylmethylene)-cyclopenta[5,6]pyrido[2,3 -d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4c), 1-amino-2-methyl-6-(4-yl)-9-(4-yl-methylene)-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidin-5(H)-one (6a), 2-amino-5-(4-yl)-8-(4-ylmethylene)-cyclopenta[5,6]pyrido[2,3-d]pyrimidine-4(H)-one (9), 2-(3-amino-5-hydroxypyrazol-1-yl)-5-(4-yl)-8-(4-ylmethylene)-cyclopenta[5,6] -pyrido[2,3-d]pyrimidin-4(H)-one (10a) and 3-thioxo-6-(4-yl)-9-(4-ylmethylene)-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (13) showed significant analgesic effects. Compound 2-(3-amino-5-hydroxypyrazol-1-yl)-5-(4-yl)-8-(4-ylmethylene)-cyclopenta [5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10a) was evaluated as the lead compound having higher anti-inflammatory activity (82.8%) than ibuprofen (79.5%) and lower ulcerogenic effect. Keywords: pyrido[2,3-d]pyrimidines, [1,2,4]triazole anellation, anti-inflammatory, analgesic activity Accepted September 18, 2008 It is already known that some pyrimido[4,5-b]quinolin-4-one derivatives display an interesting analgesic action in the writhing syndrome and hotplate tests and e not to* Correspondence, e-mail: profelgazz@yahoo.com H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. R2 R1 R3 N N H R4 Fig. 1. Pyrido[2,3-d]pyrimidin-7(8H)-one xic (1). Also, pyrido[2,3-d]pyrimidin-7(8H)-ones have attracted interest of phmaceutical companies due to the wide range of biological activities associated with this scaffold. Thus, a sech revealed that more than 3000 structures of type A (Fig. 1) have been described; they show biological activities ranging from kinase inhibition (platelet-derived growth factor, PDGFr, fibroblast growth factor, FGFr, and epidermal growth factor, EGFr) (2), CSP/p38 kinase inhibition (3), Src tyrosine kinase inhibition (4, 5), cdk4 inhibition (6), p38 MAP kinase inhibition (7), cyclin dependent kinase inhibition (8, 9) telomerase inhibition (10) for the treatment of thritis, Crohn's disease, irritable bowel syndrome, adult respiratory distress syndrome, chronic obstructive pulmony disease, or Alzheimer's disease (11). Moreover, due to their biological properties, which mainly depend on the nature and position of substituents, pyridopyrimidine derivatives e phmaceutically active (12­17), including bactericidal (13), anticancer (14) and anti-inflammatory (17) activity. This prompted us to synthesize and identify new compounds derived from pyrido[2,3-d]pyrimidin-4-ones and to screen them for analgesic and anti-inflammatory activities. EXPERIMENTAL All melting points were measured using an Electrothermal IA 9100 appatus (Shimadzu, Japan) (Table I). 1H NMR (Table II) and 13C NMR spectra (Table III) were recorded on JEOL EX-270 and JEOL ECA-500 (Jeol, Japan) and chemical shifts were expressed as d values against Si(CH3)4 as internal standd. IR spectra were recorded as KBr pellets on a Perkin-Elmer 1430 spectrometer (USA). Mass spectra (Table II) were recorded on a Hewlett-Packd-5988A GC/MS (USA) at ionization potential of 70 eV. Synthesis of 5-yl-8-ylmethylene-7,8-dihydro-2-thioxo-6H-cyclopenta[5,6]pyrido-[2,3-d]-pyrimidin-4(H)-ones (1a-c) The title compounds were preped according to El-Gazz et al. (18). Synthesis of 5-yl-8-ylmethylene-2-hydrazino-7,8-dihydro-6H-cyclopentena-[5,6]-pyrido[2,3-d]pyrimidin-4(H)-one (2a-c). General procedure A suspension of compound 1a-c (0.01 mol) in hydrazine hydrate (99­100 %) (25 mL) was stirred under reflux. The insoluble solid went into solution within 10 minutes with copious evolution of mercaptan to form a cle solution. After 30 minutes, heating was H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. continued for 8 h and the reaction mixture was allowed to cool to room temperature. The solid sepated was filtered off, washed with ethanol and dried to produce 2a-c. 5-Phenyl-8-phenylmethylene-2-hydrazino-7,8-dihydro-6H-cyclopentena[5,6]pyrido-[2,3-d] pyrimidin-4(H)-one (2a). ­ Compound 2a was obtained from 1a as a yellow powder which was crystallized from DMF. 5-(4-Chlorophenyl)-8-(4-chlorophenylmethylene)-2-hydrazino-7,8-dihydro-6H-cyclo-penta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (2b). ­ Compound 2b was obtained from 1b as a yellow powder which crystallized from dioxane. 5-(4-Methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-hydrazino-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (2c). ­ Compound 2c was obtained from 1c as a yellow powder crystallized from ethanol/dioxane (1:1). Synthesis of 5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-acethydrazido-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (3) A solution of compound 2c (0.01 mol) in glacial acetic acid, was refluxed for 3 h. The reaction mixture was allowed to cool to room temperature and was poured into cold water (100 mL). The solid formed was collected by filtration, dried and crystallized from ethanol (dk yellow powder). Synthesis of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4a) A mixture of 2c (0.01 mol) and formic acid (10 mL) and 2 mL of concentrated hydrochloric acid was heated under reflux for 8 h. The reaction mixture was allowed to cool to room temperature and was poured into water (100 mL). The solid formed was collected by filtration, washed with ethanol (20 mL), dried and crystallized from DMF as an orange powder. Synthesis of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-3-methyl-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4b) Method A. ­ A mixture of 2c (0.01 mol) and glacial acetic acid (50 mL) was stirred under reflux for 10 h (TLC). The reaction mixture was allowed to cool to room temperature an was then poured into water (100 mL). The solid formed was collected by filtration, washed with ethanol (20 mL), dried, and crystallized from dioxane as an orange powder. Method B. ­ A mixture of 3 (0.01 mol) and glacial acetic acid (30 mL) was stirred under reflux for 7 h (TLC). The reaction mixture was allowed to cool to room temperature and was then poured into water (100 mL). The solid formed was collected by filtration, washed with ethanol (20 mL) and crystallized. Synthesis of 3-amino-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4c) A mixture of 2c (0.01 mol) and potassium thiocyanate (0.15 mol) was heated under reflux in glacial acetic acid (30 mL) for 6 h. The reaction mixture was allowed to cool to room temperature and was poured into water. The precipitate formed was collected by filtration, dried and crystallized from ethanol/dioxane (2:1) as a yellow powder. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Synthesis of 3-yl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4d-f). General procedure A mixture of compound 7a-c (0.01 mol), anhydrous sodium acetate (1.64 g, 0.02 mol) and bromine (1.60 g, 0.01 mol) was stirred under reflux in glacial acetic acid (30 mL) in a water-bath at 80 °C for 20 h (under TLC control). The reaction mixture was allowed to cool to room temperature, was poured into water (100 mL) and the solid formed was collected by filtration and crystallized from appropriate solvent to afford 4d-f. 6-(4-Methoxyphenyl)-9-(4-methoxyphenylmethylene)-3-phenyl-1,7,8,9-tetrahydro-cyclopen ta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4d). ­ Compound 4d was obtained from 7a, as a yellow powder crystallized from dioxane. 3-(4-Chlorophenyl)-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4e). ­ Compound 4e was obtained from 7b as a yellow powder crystallized from dioxane. 3,6-Di-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclo-penta[5,6] pyrido[2,3-d][1,2,4] triazolo[4,3-a]pyrimidin-5(H)-one (4f). ­ Compound 4f was obtained from 7c as a yellow powder which was crystallized from DMF. Synthesis of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta-[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (5a,b). General procedure To a wmed ethanolic sodium ethoxide solution (preped by dissolving 0.01 mol of sodium metal in 30 mL ethanol), each of 4a,b (0.01 mol), was added, the heating was continued for 30 min and the mixture was allowed to cool to room temperature. Then methyl iodide (0.012 mol) was added. The mixture was stirred under reflux for 3 h, cooled to room temperature and poured into cold water (100 mL). The solid precipitated was filtered off, washed with water and dried to produce 5a,b. 1-Methyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (5a). ­ Compound 5a was obtained from 4a (10 mmol) and methyl iodide (0.012 mol) as yellow crystals crystallized from dioxane. 1,3-Dimethyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (5b). ­ Compound 5b was obtained from 4b (10 mmol) and methyl iodide (0.012 mol) as a yellow powder, crystallized from dioxane. Synthesis of 1-amino-2-methyl- or phenyl-6-(4-methoxyphenyl)-9-(4-methoxyphenyl-methylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidin-5(H)-one (6a,b). General procedure A mixture of compound 2c (0.01 mol) and chloroacetone or 2-bromoacetophenone (0.01 mol) was heated under reflux for 12 h in dry xylene (30 mL). The solid that sepated upon cooling was filtered off and crystallized from appropriate solvent to produce 6a,b. 1-Amino-2-methyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidin-5(H)-one (6a). ­ Compound 6a was obtained from compound 2c (0.01 mol) and chloroacetone (0.01 mol) as white crystals crystallized from ethanol. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. 1-Amino-2-phenyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydro-7H-cyclopenta[5,6]pyrido[2,3-d]imidazolo[1,2-a]pyrimidin-5(H)-one (6b). ­ Compound 6b was obtained from compound 2c (0.01 mol) and 2-bromoacetophenone (0.01 mol) as a yellow powder crystallized from ethanol. Synthesis of 2-ylmethylenehydrazone-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (7a-c). General procedure A mixture of 2c (0.01 mol), the appropriate omatic aldehyde (0.01 mol) and anhydrous sodium acetate (0.02 mol) was stirred under reflux in glacial acetic acid (30 mL) for 30 min. The reaction mixture was allowed to cool to room temperature. The solid formed was filtered off and crystallized from appropriate solvent to produce 7a-c. 2-Phenylmethylenehydrazone-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (7a). ­ Compound 7a was obtained from compound 2c (0.01 mol) and benzaldehyde (0.01 mol) as pale yellow crystals crystallized from DMF. 2-(4-Chlorophenyl)methylenehydrazone-5-(4-methoxyphenyl)-8-(4-methoxyphenyl-methylene)7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (7b). ­ Compound 7b was obtained from compound 2c (0.01 mol) and 4-chlorobenzaldehyde (0.01 mol) as pale yellow crystals crystallized from DMF. 2-(4-Methoxyphenyl)methylenehydrazone-5-(4-methoxyphenyl)-8-(4-methoxyphenyl-methylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (7c). Compound 7c was obtained from compound 2c (0.01 mol) and 4-methoxybenzaldehyde (0.01 mol) as a yellow powder which was crystallized from DMF. Synthesis of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydro-cyclopenta[5,6]pyrido[2,3-d][1,2,3,4]tetrazolo[4,5-a]pyrimidin-5(H)-one (8) To an ice-cold solution of compound 2c (0.01 mol) in glacial acetic acid (10 mL), a solution of sodium nitrite (0.15 mol) in a small amount of water was added dropwise in an ice bath at ­5 °C. The reaction mixture was allowed to stand overnight at room temperature and was then poured into water (100 mL). The solid precipitated was filtered off and crystallized from ethanol as a yellow powder. Synthesis of 2-amino-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (9) To a well stirred solution of compound 8 (0.01 mol) in glacial acetic acid (30 mL), activated zinc dust (5.00 g) was added portion-wise at room temperature over a period of 30 min. Stirring was continued for additional 3 h. Thereafter, the reaction mixture was heated on a water bath (80­90 °C) for 3 h. The reduction progress was monitored by TLC. After allowing the reaction mixture to cool to room temperature, it was poured into cold water (100 mL). The insoluble solid which sepated was filtered, washed with water and dried. The crude solid was extracted with hot diethyl ether and the solid obtained after the removal of ether under reduced pressure was crystallized from ethanol. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Synthesis of 2-(3-amino-5-hydroxypyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10a) To a wm ethanolic sodium ethoxide solution (preped by dissolving (0.01 mol) sodium metal in absolute ethanol (30 mL), compound 2c (0.01 mol) and ethyl cyanoacetate (0.01 mol) were added. The mixture was stirred under reflux for 8 h, the reaction mixture was allowed to cool to room temperature was then poured into cold water (100 mL) and neutralized with acetic acid. The solid product precipitated was filtered off, washed with water, ethanol, dried and crystallized from dioxane as a pale yellow powder. Synthesis of 2-(sub-pyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10b,c). General procedure A mixture of compound 2c (0.01 mol) and b-diketone (0.01 mol) in absolute ethanol (30 mL) was stirred under reflux for 5 h. The reaction mixture was allowed to cool to 0 °C for 3 h, the precipitate was filtered off, dried and crystallized from an appropriate solvent to produce 10b,c. 2-(3,5-Dimethyl-pyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10b). ­ Compound 10b was obtained from 2c (0.01 mol) with pentan-2,4-dione (0.01 mol) as pale light crystals crystallized from dioxane. 2-(3,5-Dimethyl-4-chloropyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (10c). ­ Compound 10c was obtained from 2c with 3-chloropentan-2,4-dione (0.01 mol) as a light yellow powder crystallized from ethanol. Synthesis of 2-[ethyl-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6Hcyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one acetate hydrazone (11) A mixture of compound 2c (0.01 mol) and ethyl acetoacetate (0.01 mol) was refluxed in absolute ethanol (30 mL) for 6 h. The reaction mixture was allowed to cool to room temperature and the solid precipitate produced was filtered off and crystallized from ethanol as a pale brown powder. Synthesis of 5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-(3-methyl-4H-pyrazol-5-one-1-yl)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (12) Method A. ­ A solution of compound 2c (0.01 mol) and ethyl acetoacetate (0.01 mol) in sodium ethoxide solution (preped by dissolving 0.01 mol of sodium metal in 30 mL absolute) ethanol was heated under reflux with stirring for 6 h. The reaction mixture was allowed to cool and was poured into cold water (100 mL) and neutralized by acetic acid, whereby a solid was precipitated, filtered off and crystallized from ethanol to produce 12 as a yellow powder in 65% yield (m.p. 257­259 °C, dec.). Method B. ­ A solution of compound 11 (0.01 mol) was heated under reflux with sodium ethoxide solution (preped by dissolving 0.01 mol of sodium metal in 30 mL absolute ethanol) for 3 h. The reaction mixture was allowed to cool, was poured into water (100 mL) and neutralized by acetic acid; the precipitate formed was filtered off and crystallized from ethanol. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Synthesis of 3-thioxo-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,2,8,9-tetrahydro-7H-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (13) To a wmed ethanolic sodium hydroxide solution preped by dissolving 0.01 mol of sodium hydroxide in 50 mL ethanol, compound 2c (0.01 mol) and excess cbon disulphide (10 mL) were added. The mixture was heated on a water-bath at 80 °C under reflux for 12 h, was then allowed to cool to room temperature, poured onto water (100 mL), neutralized by dilute acetic acid and the formed precipitate was filtered off and dried. The product was crystallized from ethanol as a yellow powder. Phmacological screening Animals. ­ Adult male Sprague-Dawley rats, weighing 150­200 g, were used for anti-inflammatory and ulcerogenic activity testing, and Swiss albino mice of both sex, weighing 25­30 g, were used for analgesic activity testing. International principles and local regulations concerning the ce and use of laboratory animals were observed (19). The animals had free access to standd commercial diet and water ad libitum and were kept in rooms maintained at 22 ± 1 °C with a 12 h light dk cycle. The experimental protocol was approved by the Animal Ethics Committee of the National Resech Center, Cairo, Egypt. Anti-inflammatory assay. ­ The compounds synthesized were evaluated for their anti-inflammatory activity using the crageenean induced hind paw edema method (20). The animals were randomly allocated to groups of six animals each and were fasted for 24 h before the experiment, with free access to water. Control group received only 0.5% (m/V) cboxymethyl cellulose solution. Standd drug ibuprofen was administrated orally at a 30 mg kg­1 dose. Crageenean solution in saline (1%, 0.1 mL) was injected subcutaneously into the sub-plant region of the left hind paw of each rat, one hour after the administration of the test compounds or standd drug (30 mg kg­1). The left hind paw volume was measured before and after 3 and 4 h of crageenean treatment by means of a plethysmometer. The percent edema inhibition was calculated from the mean effect in the control and treated animals. Each value represents the mean ± SEM relative to the standd and data were analyzed by ANOVA followed by Dunnett's test. Analgesic assay. ­ Analgesic activity was evaluated by the tail immersion method (21). Swiss albino mice allocated to different groups consisting of six animals each were used for the experiment. Analgesic activity was evaluated after oral administration of the test compounds at a dose of 30 mg kg­1 of ibuprofen and the test compounds. Test compounds and the standd drug were administered orally as a suspension in cboxylmethyl cellulose solution in water (0.5%, m/V). The analgesic activity was assessed before and after 4 h following administration of test compounds and standd drug. The lower 5-cm portion of the tail was gently immersed into thermostatically controlled water at 55 ± 0.5 °C. The time in seconds for tail withdrawal from water was taken to be the reaction time with a cut off time of immersion, set at 100 seconds for both control as well as treated groups of animals. Ulcerogenicity. ­ Acute ulcerogenicity was determined according to the method of Cioli et al. (22). The animals were allocated to different groups consisting of six animals each. Ulcerogenic activity was evaluated after oral administration of the test compounds H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. at a dose of 30 mg kg­1. Control group received only 0.5% (m/V) cboxymethyl cellulose solution. After the drug treatment, the rats were fed normal diet for 17 h and were then sacrificed. The stomach was removed and opened along the greater curvature, washed with distilled water and cleaned gently by dipping in normal saline. The mucosal damage was examined by means of a magnifying glass. Mucosal damage was assessed for each stomach according to the following scoring system: 0.5: redness, 1.0: spot ulcers, 1.5: hemorrhagic streaks, 2.0: 3 < ulcers £ 5, 3.0: ulcers > 5. The mean score of each treated group minus the mean score of the control group was regded as the severity index of gastric mucosal damage. RESULTS AND DISCUSSION 5-yl-8-ylmethylene-7,8-dihydro-2-thioxo-6H-cyclopenta[5,6]pyrido[2,3-d]-pyrimidin-4(H)-ones (1a-c) were synthesized previously (18). Beside the correct values in elemental analyses and spectral data, structures were established chemically. Upon treatment with hydrazine hydrate (Scheme 1), thay gave 5-yl-8-ylmethylene-2-hydrazino-7,8-dihydro-6H-cyclopenta[5,6]pyrido-[2,3-d] pyrimidin-4(H)-ones (2a-c), with the evolution of mercaptan. O NH N H N H S H N2H4·H2O O NH N H NH2 1a-c : a = C6H5 b = 4-ClC6H4 c = 4-OCH3C6H4 2a-c Scheme 1 Compound 2c could be considered as a stting material for the synthesis of new polynucle heterocycles such as azolopyridopyrimidines, as well as the synthesis of some pyrazolopyridopyrimidine derivatives. Thus, heating compound 2c with aliphatic acids, namely, formic and acetic acid, resulted in the formation of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydro-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo-[4,3-a]pyrimidin-5(H)-ones (4a,b). On the other hand, heating of compound 2c with acetic acid for 3 hours only yielded 2-acetylhydrazino derivative 3, which on further long heating with acetic acid gave 4b. Moreover, alkylation of 4a,b in ethanolic sodium ethoxide solution with methyl iodide afforded 1-methyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-8,9-dihydrocyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a] pyrimidin-5(H)-ones (5a,b) as shown in Scheme 2. All the synthesized compounds were chacterized by their physical, chemical and spectral data (Tables I­III). IR spectra of compounds 4a,b showed the presence of chacteristic absorption peaks ound 3385­3400 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Table I. Physical and chemical properties of synthesized compounds Mol. formula (Mr) C23H19N5O (381.4) C23H17Cl2N5O (450.3) C25H23N5O3 (441.5) C27H25N5O4 (483.5) C26H21N5O3 (451.5) C27H23N5O3 (465.5) C26H22N6O3 (466.5) C32H25N5O3 (527.5) C32H24ClN5O3 (562.1) C33H27N5O4 (557.6) C27H23N5O3 (465.5) C28H25N5O3 (479.5) C28H25N5O3 (479.5) C33H27N5O3 (541.6) C32H27N5O3 (529.6) C32H26ClN5O3 (564.1) C33H29N5O4 (559.6) C25H20N6O3 (452.5) C25H22N4O3 (426.4) C28H24N6O4 (508.5) Found/calcd. (%) N 72.42 72.37 61.34 61.29 68.01 68.03 67.06 67.04 69.16 69.13 69.66 69.63 66.94 66.91 72.85 72.83 68.38 68.35 71.08 71.05 69.66 69.62 70.13 69.98 70.13 70.09 73.17 73.19 72.57 72.54 68.14 68.09 70.83 70.79 66.36 66.34 70.40 70.38 66.13 66.09 H 5.02 5.00 3.81 3.79 5.25 5.28 5.21 5.18 4.69 4.71 4.98 4.96 4.75 4.69 4.78 4.75 4.30 4.27 4.88 4.87 4.97 4.98 5.25 5.20 5.26 5.19 5.02 4.99 5.14 5.09 4.65 4.62 5.22 5.23 4.46 4.47 5.20 5.17 4.76 4.74 C 18.36 18.29 15.55 15.58 15.86 15.79 14.48 14.51 15.51 15.48 15.04 15.07 18.02 18.04 13.27 13.25 12.46 12.43 12.56 12.59 15.04 15.01 14.60 14.58 14.60 14.63 12.93 12.94 13.22 13.18 12.41 12.39 12.51 12.48 18.57 18.59 13.14 13.09 16.53 16.49 Compd. No. 2a 2b 2c 3 4a 4b 4c 4d 4e 4f 5a 5b 6a 6b 7a 7b 7c 8 9 10a Yield (%) 86 89 87 75 67 64 73 60 63 64 68 70 68 65 89 83 81 53 49 73 M.p. (°C) 248­250 233­236 282­284 267­270 309­311 339­341 336­338 320­322 300­302 343­345 278­280 263­265 264­266 248­250 295­297 288­290 330­332 260­262 280­282 258­260 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. 10b 10c 11 12 13 240­242 266­268 235­237 257­259 311­313 C30H27N5O3 (505.5) C30H26ClN5O3 (540.0) C31H31N5O5 (553.6) C29H25N5O4 (507.5) C26H21N5O3S (483.5) Table II. Spectral data of synthesized compounds Compd. No. 2a 1H NMR (d, ppm) IR (DMSO-d6) (n, cm­1) 3400 (br, NH), 2.05 (br, 2H, NH2), 2.71­2.75 (m, 2H, CH2), 2.84­2.95 (t, MS (m/z), 1687 (CO), 2H, CH2), 5.15 (br, NH), 7.07­7.11 (m, 2H, -H), 381 (M+) 7.32­7.39 (m, 3H, -H), 7.45­7.59 (m, 5H, -H) and 1625 (C=N) 8.22 (s, 1H, CH), 9.10 (br, NH) 3410 (brs, NH), 2.10 (br, 2H, NH2), 2.73­2.76 (m, 2H, CH2), 2.80­2.92 (m, MS (m/z), 2H, CH2), 3.80 (br, NH), 6.98­7.05 (d, 2H, J = 8.43 Hz, 452 (M++2), 1686 (CO), 1640 (C=N) 450 (M+) -H), 7.10­7.19 (d, 2H, J = 8,42 Hz, -H), 7.43­7.50 (d, 2H, J = 8.40 Hz, -H), 7.54­7.60 (d, 2H, J = 8.40 Hz, -H), 8.02 (s, 1H, CH), 12.00 (br, NH) (2NH, NH2, D2O exchangeable) 3395 (br, NH), 2.00 (br, 2H, NH2), 2.70­2.72 (m, 2H, CH2), 2.80­2.90 (m, MS (m/z), 2H, CH2), 3.80, 3.83 (2s, 6H, 2OCH3), 5.15 (br, NH), 1689 (CO), 441 (M+) 1646 (C=N) 6.92­6.98 (d, 2H, J = 8.41 Hz, -H), 7.00­7.19 (d, 2H, J = 8.41 Hz, -H), 7.50­7.53 (d, 2H, J = 8.39 Hz, -H), 7.56­7.61 (d, 2H, J = 8.40 Hz, -H), 8.16 (s, 1H, CH), 11.50 (br, NH) (2NH, NH2, D2O exchangeable) 3400 (br, NH), 2.73­2.78 (m, 2H, CH2), 2.82­2.91 (m, 2H, CH2), 2.86 (s, MS (m/z), 1688, 1680 3H, CH3), 3.82, 3.86 (2s, 6H, 2OCH3), 6.96 (d, 2H, J = 468 (2CO), 8.39 Hz, -H), 7.11 (d, 2H, J = 8.40 Hz, -H), 7.49 (d, (M+-CH3) 2H, J = 8.39 Hz, -H), 7.60 (d, 2H, J = 8.40 Hz, -H), 1620 (C=N) 8.19 (s, 1H, CH), 8.90, 9.30, 11.10 (3br, 3NH, D2O exchangeable) 3385 (br, NH), 2.72­2.76 (m, 2H, CH2), 2.85­2.91 (m, 2H, CH2), 3.83, MS (m/z), 1687 (CO), 3.89 (2s, 6H, 2OCH3), 6.98­7.04 (d, 2H, -H), 7.08­7.15 451 (M+) 1615 (C=N) (d, 2H, -H), 7.45­7.50 (d, 2H, -H), 7.56­7.63 (d, 2H, -H), 8.12 (s, 1H, CH), 8.54 (s, 1H, triazole proton) 9.50 (br, NH, D2O exchangeable) 3400 (br, NH), 2.25 (s, 3H, CH3), 2.71­2.77 (m, 2H, CH2), 2.85­2.91 (m, MS (m/z), 1685 (CO), 2H, CH2), 3.86, 3.91 (2s, 6H, 2OCH3), 7.04 (d, 2H, J = 465 (M+) 1620 (C=N) 8.39 Hz, -H), 7.15 (d, 2H, J = 8.38 Hz, -H), 7.47 (d, 2H, J = 8.38 Hz, -H), 7.59 (d, 2H, J = 8.38 Hz, -H), 8.08 (s, 1H, CH), 10.20 (br, NH, D2O exchangeable) Mass (m/z) 2b 2c 4a 4b H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. 4c MS (m/z), 466 (M+) 4d 4e 4f 5a MS (m/z), 465 (M+) 5b MS (m/z), 479 (M+) 6a 6b MS (m/z). 541 (M+) 7a MS (m/z), 529 (M+) 3420 (br, NH), 2.74­2.78 (m, 2H, CH2), 2.84­2.90 (m, 2H, CH2), 3.85, 1686 (CO), 3.88 (2s, 6H, 2OCH3), 5.54 (br, NH2), 6.99 (d, 2H, J = 1646 (C=N) 8.38 Hz, -H), 7.10 (d, 2H, J = 8.39 Hz, -H), 7.49 (d, 2H, J = 8.40 Hz, -H), 7.61 (d, 2H, J = 8.40 Hz, -H), 8.22 (s, 1H, CH), 10.50 (br, NH) (NH, NH2 D2O exchangeable) 3410 (br, NH), 2.73­2.82 (m, 2H, CH2), 2.84­2.92 (m, 2H, CH2), 3.85, 3.90 (2s, 6H, 2OCH3), 6.95­6.99 (d, 2H, -H), 7.03­7.15 1698 (CO), (m, 2H, -H), 7.18­7.21 (d, 2H, -H), 7.33­7.43 (m, 1615 (C=N) 3H, -H), 7.54­7.58 (d, 2H, -H), 7.60­7.64 (d, 2H, -H), 8.20 (s, 1H, CH), 10.70 (br, NH, D2O exchangeable) 3420 (br, NH), 2.72­2.78 (m, 2H, CH2), 2.81­2.89 (m, 2H, CH2), 3.84, 3.89 (2s, 6H, 2OCH3), 6.94­7.00 (d, 2H, -H), 7.03­7.12 1695 (CO), (d, 2H, -H), 7.16­7.22 (d, 2H, -H), 7.38­7.42 (d, 2H, 1595 (C=N) -H), 7.50­7.58 (d, 2H, -H), 7.62­7.67 (d, 2H, -H), 8.14 (s, 1H, CH), 11.00 (br, NH, D2O exchangeable) 3400 (br, NH), 2.74­2.80 (m, 2H, CH2), 2.83­2.90 (m, 2H, CH2), 3.82, 3.85, 3.89 (3s, 9H, 3OCH3), 6.90­6.96 (d, 2H, -H), 1700 (CO), 7.01­7.11 (d, 2H, -H), 7.15­7.20 (d, 2H, -H), 1640 (C=N) 7.36­7.40 (d, 2H, -H), 7.52­7.57 (d, 2H, -H), 7.59­7.65 (d, 2H, -H), 8.18 (s, 1H, CH), 11.30 (br, NH, D2O exchangeable) 3385 (br, NH), 2.74­2.78 (m, 2H, CH2), 2.86­2.94 (m, 2H, CH2), 3.49 (s, 1687 (CO), 3H, N-CH3), 3.84, 3.90 (2s, 6H, 2OCH3), 7.00 (d, 2H, J = 1615 (C=N) 8.38 Hz, -H), 7.12 (d, 2H, J = 8.42 Hz, -H), 7.47 (d, 2H, J = 8.39 Hz, -H), 7.58 (d, 2H, J = 8.41 Hz, -H), 8.19 (s, 1H, CH), 8.49 (s, 1H, triazole proton) 1688 (CO), 2.23 (s, 3H, CH3), 2.73­2.79 (m, 2H, CH2), 2.83­2.90 (m, 1615 (C=N) 2H, CH2), 3.67 (s, 3H, N-CH3), 3.88, 3.93 (2s, 6H, 2OCH3), 7.07 (d, 2H, J = 8.37 Hz, -H), 7.14 (d, 2H, J = 8.38 Hz, -H), 7.48 (d, 2H, J = 8.40 Hz, -H), 7.63 (d, 2H, J = 8.40 Hz, -H), 8.13 (s, 1H, CH) 3405 (br, NH), 2.35 (s, 3H, CH3), 2.74­2.78 (m, 2H, CH2), 2.84­2.91 (m, 2H, CH2), 3.86, 3.90 (2s, 6H, 2OCH3), 5.50 (br, NH2, D2O 1685 (CO), exchangeable), 7.01 (d, 2H, J = 8.41 Hz, -H), 7.14 (d, 1610 (C=N) 2H, J = 8.40 Hz, -H), 7.48 (d, 2H, J = 8.39 Hz, -H), 7.61 (d, 2H, J = 8.40 Hz, -H), 8.13 (s, 1H, imidazole proton), 8.21 (s, 1H, CH) 3410 (brs, NH), 2.72­2.76 (m, 2H, CH2), 2.85­2.90 (m, 2H, CH2), 3.87, 1686 (CO), 3.91 (2s, 6H, 2OCH3), 5.62 (br, NH2, D2O exchangeable), 1642 (C=N) 6.96­7.05 (m, 4H, -H), 7.15 (d, 2H, J = 8.42 Hz, -H), 7.34­7.43 (m, 3H, -H), 7.50 (d, 2H, J = 8.41 Hz, -H), 7.62 (d, 2H, J = 8.39 Hz, -H), 8.09 (s, 1H, imidazole proton), 8.19 (s, 1H, CH) 3980 (brs, NH), 2.75­2.81 (m, 2H, CH2), 2.87­2.94 (m, 2H, CH2), 3.88, 3.93 (2s, 6H, 2OCH3), 7.02 (d, 2H, J = 8.39, Hz, -H), 1687 (CO), 1625 (C=N) 7.13­7.20 (m, 4H, -H), 7.30­7.38 (m, 3H, -H), 7.48 (d, 2H, J = 8.38 Hz, -H), 7.62 (d, 2H, J = 8.40 Hz, -H), 8.19 (s, 1H, CH), 8.30 (s, 1H, azomethine proton), 9.00, 10.80 (br, 2H, 2NH, D2O exchangeable) 369 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. 7b 7c 10a 10b 10c 2.71­2.77 (m, 2H, CH2), 2.80­2.86 (m, 2H, CH2), 3.83, 3.88 (2s, 6H, 2OCH3), 6.97 (d, 2H, J = 8.37 Hz, -H), 7.08 (d, 2H, J = 8.38 Hz, -H), 7.26 (d, 2H, J = 8.40 Hz, -H), 7.51 (d, 2H, J = 8.41 Hz, -H), 7.59 (d, 2H, J = 8.42 Hz, -H), 7.69 (d, 2H, J = 8.40 Hz, -H), 8.06 (s, 1H, azomethine proton), 8.17 (s, 1H, CH), 9.70, 11.00 (2brs, 2NH, D2O exchangeable) 3375 (brs, NH), 2.69­2.76 (m, 2H, CH2), 2.83­2.89 (m, 2H, CH2), 3.79, 3.86, 3.91 (3s, 9H, 3OCH3), 7.09­7.10 (d, 2H, -H), 1676 (CO), 7.13­7.17 (d, 2H, -H), 7.34­7.40 (d, 2H, -H), 1605 (C=N) 7.43­7.49 (d, 2H, -H), 7.52­7.57 (d, 2H, -H), 7.65­7.70 (d, 2H, -H), 8.05 (s,1H, azomethine proton), 8.17 (s, 1H, CH), 9.25, 10.30 (brs, 2NH, D2O exchangeable) 3340 (br, NH), 2.71­2.78 (m, 2H, CH2), 2.82­2.90 (m, 2H, CH2), 3.86, MS (m/z), 2320 (N3), 3.90 (2s, 6H, 2OCH3), 6.93­6.98 (d, 2H, -H), 7.11­7.17 452 (M+) (d, 2H, -H), 7.37­7.42 (d, 2H, -H), 7.56­7.60 (d, 2H, 1702 (CO), -H), 8.21 (s, 1H, CH), 11.60 (br, NH, D2O exchange1625 (N=N), able) 1585 (C=N) 3410 (br, NH), 2.75­2.82 (m, 2H, CH2), 2.84­2.93 (m, 2H, CH2), 3.86, MS (m/z), 1687 (CO), 3.89 (2s, 6H, 2OCH3), 7.03­7.10 (d, 2H, -H), 7.16­7.22 426 (M+) 1589 (C=N) (d, 2H, -H), 7.38­7.42 (d, 2H, -H), 7.58­7.64 (d, 2H, -H), 8.23 (s, 1H, CH), 8.56 (br, 2H, NH2), 11.30 (br, NH) (NH2, NH, D2O exchangeable) 3480 (br, OH), 2.74­2.82 (m, 2H, CH2), 2.86­2.93 (m, 2H, CH2), 3.55 (br, MS (m/z), 3318 (brs, NH), 1H, OH coupled with H2O of DMSO), 3.85, 3.90 (2s, 6H, 508 (M+) 1687, (CO), 2OCH3), 5.67 (br, NH2, D2O exchangeable), 6.68 (s, 1H, pyrazole proton), 7.00 (d, 2H, J = 8.41 Hz, -H), 7.26 1601 (C=N) (d, 2H, J = 8.40 Hz, -H), 7.34 (d, 2H, J = 8.40 Hz, -H), 7.53 (d, 2H, J = 8.40 Hz, -H), 8.14 (s, 1H, CH), 9.10 (brs, NH, D2O exchangeable) 3380 (br, NH), 2.21 (s, 3H, CH3), 2.68­2.73 (m, 2H, CH2), 2.86 (s, 3H, MS (m/z), 1690 (CO), CH3), 2.89­2.96 (m, 2H, CH2), 3.85, 3.89 (2s, 6H, 505 (M+) 1625 (C=N) 2OCH3), 6.25 (s, 1H, pyrazole proton), 7.11 (d, 2H, J = 8.38 Hz, -H), 7.31 (d, 2H, J = 8.39 Hz, -H), 7.45 (d, 2H, J = 8.40 Hz, -H), 7.64 (d, 2H, J = 8.40 Hz, -H), 8.17 (s, 1H, CH), 10.20 (br, NH, D2O exchangeable) 3380 (br, NH), 2.19 (s, 3H, CH3), 2.67­2.74 (m, 2H, CH2), 2.87 (s, 3H, MS (m/z), CH3), 2.90­2.97 (m, 2H, CH2), 3.86, 3.90 (2s, 6H, 542 (M++2), 1690 (CO), 541 (M++1), 1625 (C=N) 2OCH3), 7.12 (d, 2H, J = 8.39 Hz, -H), 7.33 (d, 2H, J = 540 (M+) 8.39 Hz, -H), 7.47 (d, 2H, J = 8.41 Hz, -H), 7.65 (d, 2H, J = 8.41 Hz, -H), 8.09 (s, 1H, CH), 10.35 (br, NH, D2O exchangeable) 3250 (br, NH), 1.24­1.31 (t, 3H, CH3), 2.15 (s, 3H, CH3), 2.71­2.78 (m, MS (m/z), 1730, 1685 2H, CH2), 2.85­2.92 (m, 2H, CH2), 3.42 (s, 2H, CH2), 553 (M+) (2CO), 3.84, 3.86 (2s, 6H, 2OCH3), 4.00­4.10 (q, 2H, CH2), 7.01 (d, 2H, J = 8.39 Hz, -H), 7.13 (d, 2H, J = 8.40 Hz, 1580 (C=N) -H), 7.45 (d, 2H, J = 8.39 Hz, -H), 7. 62 (d, 2H, J = 8.41 Hz, -H), 8.17 (s, 1H, CH), 9.40, 11.00 (2br, 2NH, D2O exchangeable) MS 566 565 564 3395 (br, NH), (m/z), (M++2), 1678 (CO), (M++1), 1636 (C=N) (M+) H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. MS (m/z), 507 (M+) MS, [M+], m/z 482 (100%) 2.03 (s, 3H, CH3), 2.78­2.83 (m, 2H, CH2), 2.86­2.92 (m, 2H, CH2), 3.87, 3.92 (2s, 6H, 2OCH3), 4.31 (s, 2H, CH2), 7.06 (d, 2H, J = 8.36 Hz, -H), 7.35 (d, 2H, J = 8.38 Hz, -H), 7.45 (d, 2H, J = 8.39 Hz, -H), 7.70 (d, 2H, J = 8.38 Hz, -H), 8.23 (s, 1H, CH), 10.30 (brs, NH, D2O exchangeable) 3465 (br, NH), 2.79­2.85 (m, 2H, CH2), 2.88­2.93 (m, 2H, CH2), 3.88, 3.93 (2s, 6H, 2OCH3), 7.07 (d, 2H, J = 8.38 Hz, -H), 1686 (CO), 7.38 (d, 2H, J = 8.39 Hz, -H), 7.48 (d, 2H, J = 8.41 Hz, 1620 (C=N) -H), 7.68 (d, 2H, J = 8.42 Hz, -H), 8.16 (s, 1H, CH), 10.00, 11.50 (2brs, 2NH, D2O exchangeable) 3400 (brs, NH), 1697, 1684 (2CO), 1550 (C=N) cm­1 (N-H stretching). Also, 1H NMR spectra of compounds 4a,b showed broad bands at d 9.50 and 10.20 ppm, while IR and NMR spectra of compound 5a,b revealed the absence of NH absorption peaks (Table II). O NH N H N O N N H N N NH2 R AcOH 3h NHNHCOCH3 O R N N N N N CH3 6a,b a: R = CH3 b: R = C6H5 O N H N H ' N H 2c 'CHO N H Br2/NaOAc 5a,b 7a-c a: R = H b: R = CH3 CH3I HCOOH (a) AcOH (b) KSCN (c) a: ' = C6H5 b: ' = 4-ClC6H4 c: ' = 4-OCH3C6H O ' N N N H O R N N N H H N H 4a-c 4d-f a: R = H c: R = NH2 e: ' = 4-ClC6H4 b: R = CH3 d: ' = C6H5 f: ' = 4-OCH3C6H4 = 4-OCH3C6H4 Scheme 2 371 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. Also, the 2-hydrazino- derivative 2c reacted with potassium thiocyanate in boiling acetic acid to give 3-amino-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8, 9-tetrahydro-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4c). Beside correct values in elemental analyses, the spectral data of 4c e in agreement with the assigned structure (Scheme 2). When compound 2c was heated under reflux with a-haloketones, namely, chloroacetone or 2-bromoacetophenone in dry xylene, it yielded the respective 1-amino-6-yl-9-ylidene-1H,5H-imidazo[1',2'-a]cyclopenta[5,6]pyrido-[2,3-d]pyrimidin-5-one (6a,b). The 1H NMR spectrum of 6a, for example, showed that singlet signals at 2.35 ppm supported the methyl protons, two signals ound 2.74­2.91 ppm corresponded to the two methylene groups, two singlets ound 3.85­3.90 ppm due to the two methoxy groups and the broad absorption signal (D2O exchangeable) supported the amino group. In addition to the pyrazole proton at 8.13 ppm, the spectrum showed four doublet signals due to the p-substituted phenyl groups with the coupling constant ound 8.40 Hz and the methylenic proton at 8.21 ppm. Also, the 13C NMR showed that, in addition to the methyl group (18.39 ppm), two methylene groups (27.21 and 27.90 ppm), two methoxy groups (54.97 and 55.33 ppm) and cbonyl groups (163.8 ppm), eighteen lines ound 111.0­158.5 ppm corresponding to 22 sp2 cbon atoms were obtained (Table III). Table III. Compd. No. 2c 13C NMR of some new compounds 13C NMR (d, ppm) (DMSO-d6) 27.01, 27.95 (2C, 2CH2), 54.98, 55.17, (2C, 2OCH3), 108.5, 112.9, 113.1, 114.2, 124.4, 128.9, 129.5, 130.6, 130.7, 130.8, 132.9, 138.9, 148.2, 154.7, 158.3, 158.8 (16 line for 20 sp2 cbon atoms) and 163.9 (CO) 27.12, 27.93 (2C, 2CH2), 54.95, 55.21, (2C, 2OCH3), 110.2, 112.9, 113.8, 118.5, 125.4, 127.3, 129.1, 131.7, 132.3, 133.8, 134.9, 137.6, 147.5, 153.4, 155.3, 157.2, 158.3 (17 line for 21 sp2 cbon atoms) and 165.2 (CO) 13C-NMR: 4a 4c 27.11, 27.96 (2C, 2CH2), 54.96, 55.18, (2C, 2OCH3), 110.4, 112.3, 113.6, 118.2, 124.5, 127.9, 128.4, 129.3, 130.7, 130.2, 131.8, 134.9, 138.5, 148.1, 154.4, 158.2, 158.8 (17 line for 21 sp2 cbon atoms) and 163.5 (CO) 4f 27.11, 27.94 (2C, 2CH2), 54.96, 55.15, 56.23 (3C, 3OCH3), 108.3, 112.5, 113.5, 114.7, 124.7, 128.6, 129.5, 130.9, 131.2, 131.8, 132.3, 132.7, 134.8, 138.9, 140.2, 144.6, 148.2, 154.7, 167.0, 158.3, 158.8 (21 line for 27 sp2 cbon atoms) and 163.9 (CO) 18.39 (CH3), 27.21, 27.90 (2C, 2CH2), 54.97, 55.33, (2C, 2OCH3), 111.0, 112.7, 114.2, 118.6, 125.7, 127.7, 128.5, 129.5, 131.3, 132.5, 133.8, 135.6, 137.8, 147.4, 152.9, 154.3, 157.4, 158.5 (18 line for 22 sp2 cbon atoms) and 163.8 (CO) 24.31, 26.58 (2 CH2), 109.3, 127.0, 127.5, 127.6, 127.7, 127.8, 129.2, 129.4, 130.9, 132.1, 133.1, 136.6, 138.7, 150.5, 153.7, 158.4 (16 line for 20 sp2 cbon atoms), 163.8 (CO) and 174.2 (C=S) 6a Further, compound 2c gave the 2-ylmethylene hydrazone derivatives 7a-c when treated with the appropriate aldehyde in boiling glacial acetic acid. The latter compounds were cyclized when gently heated in a mixture of bromine and sodium acetate in acetic acid to afford 3-yltriazolo[4',3':1,2]cyclopentenopyrido[2,3-d]pyrimidines (4d-f). Beside H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. correct values in elemental analysis, the spectral data of 7a-c and 4d-f e in agreement with the assigned structures. The 1H NMR spectra revealed the absence of azomethine protons. Also, the formation of triazolopyridopyrimidine 4d-f from 7a-c may be accomplished via brominating the methylenic proton or N-3 of the pyrimidine ring followed by elimination of hydrogen bromide, as shown in Scheme 3. O N N H N Br N N H ' H 7a-c Br2 AcONa ­HBr 4d-f Scheme 3 Treatment of compound 2c with nitrous acid led to the formation of 6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-1,7,8,9-tetrahydrocyclopenta[5,6]-pyrido[2,3-d][1, 2,3,4]tetrazolo[4,5-a]pyrimidin-5(H)-one (8) (Scheme 4). The IR spectrum of 8 displayed absorption bands at 3240 cm­1 (NH) and 1702 cm­1 (CO). The latter compound was reduced to 2-amino-5-(4-methoxyphenyl)-8-(4-methoxyphenyl-methylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidine-4(H)-one (9) by zinc dust and acetic acid. O N N H N N H N N Zn dust acetic acid H N N O NH NH2 = 4-OCH3C6H4 Scheme 4 5-(4-Methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-hydrazino-7,8-dihydro-6H-cyclopenta [5,6]pyrido[2,3-d]pyrimidin-4(H)-one (2c) reacted with b-cyano-ester, b-diketones and b-ketoesters to form 2-(1-pyrazolyl) derivatives. Thus, heating compound 2c with ethylcyanoacetate, pentane-2,4-dione and/or 3-chloropentane-2,4-dione, yielded the respective 2-(3,5-substituted-4-(un)substituted-pyrazol-1-yl)-5-(4-methoxyphenyl)-8-(4-methoxy-phenyl-methylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-ones 10a-c, respectively (Scheme 5). Compound 2c condensed with ethyl acetoacetate upon heating in boiling ethanol to afford 2-[ethyl-5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one]acetatehydrazone (11), which could be cyclized either by prolonged heating in ethanol or by heating in sodium ethoxide solution to give 5-(4-methoxyphenyl)-8-(4-methoxyphenylmethylene)-2-(3-methyl-4H-pyrazol-5-one-1-yl)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (12). Finally, heating 2c with cbon disulphide in ethanolic potassium hydroxide solution gave 3-thioxo-6-(4-methoxyphenyl)-9-(methoxyphenylmethylene)-1,2,8,9-tetrahydro373 H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. O NH O NH CH3 N H N R N N N H N 11 NH-N=CCH2COOC2H5 10a-c Method B 2c O NH a: R = OH R = NH2 X = H 1 b: R = R = CH3 X=H 1 c: R = R = CH3 X = Cl O N N H N N H S N H Method A N H N O N N CH3 CS2 = 4-OCH3C6H15 Scheme 5 Table IV. Percent inflammatory activity of the tested compounds (crageenean-induced paw odema test in rats) Inhibition (%)a 3 hours 27.29 ± 2.64 56.82 ± 2.53 52.28 ± 2.18 27.28 ± 2.73 75.01 ± 2.52 63.70 ± 1.93 75.00 ± 2.79 76.08 ± 2.67 31.80 ± 3.45 15.90 ± 2.73 52.27 ± 2.80 56.81 ± 1.94 ­ 75.00 ± 2.53 4 hours 28.27 ± 2.75b 56.81 ± 2.16b 54.55 ± 2.62b 29.54 ± 2.79b 77.26 ± 1.92b 63.62 ± 1.92 79.53 ± 3.72 82.79 ± 2.18 31.80 ± 3.69b 19.04 ± 2.24 52.27 ± ­ 79.54 ± 2.25 2.79b 59.09 ± 2.74b Potency 0.34 0.71 0.67 0.37 0.98 0.80 1.00 1.03 0.39 0.24 0.65 0.74 ­ 1.00 Compd. No. 2a 2b 2c 4a 4c 6a 9 10a 10b 11 12 13 Control Ibuprofen kg­1 Dose: 30 mg b.m. of the tested compound and standd drug. a Mean ± SEM (n = 6). b Significant difference relative to ibuprofen: p < 0.01. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. -7H-cyclopenta[5,6]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (13) (Scheme 5). The IR spectrum of 13 displayed absorption bands at 3465­3400 cm­1 (2NH) and 1686 cm­1 (CO). The 13C NMR spectrum (DMSO-d6) of 13 showed two signals due to the sp3 cbon atoms, sixteen lines assigned to 20 sp2 cbon atoms and, in addition to the signal for the cbonyl group, the spectrum showed a strong peak corresponding to C=S at 174.2 ppm. The phmacological screening of the tested compounds showed anti-inflammatory activity ranging from 19.0 to 82.8% (Table IV), whereas the standd drug ibuprofen showed 79.5% inhibition after 4 h. The anti-inflammatory activity of 2-pyrazolyl-pyridopyrimidine derivatives 10a, 10b and 12 ranged from 31.8 to 82.8%. The aminopyrazolyl derivative 10a with hydroxyl and amino groups showed higher activity than the standd drug ibuprofen, whereas when these groups were replaced by a methyl group, the anti-inflammatory activity decreased. Also, it was observed that the triazolopyrido-pyrimidine derivatives 4a, 4c and 13 showed activity ranging from 29.5 to 77.3%, and 3-aminotriazolopyridopyrimidine 4c showed activity nely equivalent to the standd drug. 2-Aminopyrido[2,3-d]pyrimidine (9) showed activity (79.5%) equivalent to that of ibuprofen. Other tested compounds showed moderate anti-inflammatory activity. It is cle from Table IV that the presence of amino group in triazolo-/or pyrazolo-pyridopyrimidine increases the anti-inflammatory activity. Compounds 4c, 6a, 9 and 10a which showed anti-inflammatory activity compable or equal to that of the standd were further tested for their analgesic activity at a dose of 30 mg kg­1 ibuprofen (Table V). Compounds showed analgesic activity ranging from 58.4 to 72.7%, whereas the standd drug ibuprofen showed 69.5% inhibition. Compounds 4c, 9 and 10a showed the highest anti-inflammatory activity, 72.7, 59.3 and 70.2%, resp. The remaining compounds showed reduced analgesic activity. These compounds were further screened for their acute ulcerogenic activity. The tested compounds showed significant reduction in ulcerogenic activity ranging from 0.7 ± 0.15 to 1.06 ± 0.17, whereas Table V. Analgesic and ulcerogenic activity of the selected compounds Analgesic activity Group Pre-treatment normal (0 h) 1.40 ± 0.150 1.34 ± 0.137 1.34 ± 0.136 1.41 ± 0.150 1.80 ± 0.188 1.15 ± 0.060 ­ Post-treatment after (4 h) 2.42 ± 0117b 2.13 ± 0145b 2.12 ± 1.86 ± 0.146b 0.094b Inhibition (%)a 72.7 58.4 59.3 70.2 31.2 69.5 Potency 1.04 0.84 0.85 1.02 1.02 1.00 Ulcerogenic index 1.064 ± 0.17c 0.670 ± 0.21c 0.732 ± 0.18c 0.667 ± 0.15c 0.668 ± 0.22c 1.665 ± 0.25 ­ 4c 6a 9 10a 13 Ibuprofen Control kg­1 2.35 ± 0.180b 1.95 ± 0.097 ­ Dose: 30 mg b.m. of the tested compound and standd drug. a Mean ± SEM (n = 6). b Significant difference relative to ibuprofen: p < 0.0001. c Significant difference from ibuprofen: p < 0.05. H. N. Hafez et al.: Synthesis and evaluation of analgesic, anti-inflammatory and ulcerogenic activities of some triazolo- and 2-pyrazolyl-pyrido[2,3-d]-pyrimidines, Acta Phm. 58 (2008) 359­378. the standd drug ibuprofen showed a severity index of 1.66 ± 0.25. Maximum reduction in ulcerogenic activity was found for compound 10a having the hydroxyl and amino groups of 2-pyrazolo-pyridopyrimidine ring (0.66 ± 0.15). The rest of the compounds also showed a better gastro interact safety profile than ibuprofen. CONCLUSIONS The present investigation offers new, rapid and effective procedures for the synthesis of new poly-condensed heterocyclic pyrido[2,3-d]pyrimidine ring systems. Compounds 3-amino-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-cyclopenta-[5,6]pyrido [2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5(H)-one (4c), 1-amino-2-methyl-6-(4-methoxyphenyl)-9-(4-methoxyphenylmethylene)-cyclopenta[5,6]pyrido[2,3-d]imidazolo-[1,2-a]pyrimidin-5 (H)-one (6a) and 2-amino-5-(4-methoxy-phenyl)-8-(4-methoxyphenyl-methylene)-7,8-dihydro-6H-cyclopenta[5,6]pyrido[2,3-d]pyrimidin-4(H)-one (9) exhibited a potent anti-inflammatory activity whereas 2-(3-amino-5-hydroxypyrazol-1-yl)-pyrido[2,3-d]pyrimidin-4-one derivative 10a was the most active. Acknowledgements. ­ The authors e thankful to the National Resech Center for providing laboratory facilities, Micro-analytical Centre, Cairo University and the Phmacological Unit National Resech Centre, for microanalyses and phmacological screening of the compounds.

Journal

Acta Pharmaceutica – de Gruyter

Published: Dec 1, 2008

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