1 H-NMR, 13 C-NMR, mass spectroscopy and elemental analyses. The anti-inflammatory activity of all the newly synthesized compounds was evaluated using the carrageenaninduced paw oedema test in rats using indomethacin as the reference drug. Compound 11 and the two derivatives 7f and 8b were the most active compounds, showing an activity comparable to indomethacin. Also, the synthesized compounds were evaluated for their antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) using chloramphenicol as control. The pyrazolotriazolopteridin-2-thione 11, 6-hydroxyethyl6a, 6-(4-nitrophenyl)-7g, and 6-(phenylamino) 8b derivatives were found to be the most active compounds against the Gram-positive species. None of them showed any activity against Gram-negative species.Key words pyrazolo [3,4-b]pyrazine; pyrazolopyrazinoxazinone; pyrazolo [4,3-g]pteridine; anti-inflammatory; antibacterial Pyrazolo[4,3-g] pteridines represent a class of fused triheterocyclic system scarcely reported in the literature. Literature survey revealed that some derivatives of these heterocycles were published for the first time in the sixties as potential diuretic drugs.1,2) Their synthesis has increased noticeably in recent years owing to their diverse biological activities such as antimicrobial and antiparasitic ones. [3][4][5] In continuation to our research work on the synthesis of new pyrazole-based heterocycles with potential biological activities as antimicrobial, [6][7][8][9][10][11][12] as anticonvulsant, 13,14) as β 1 -adrenergic blocking agents, 15) we wish to report herein the synthesis of some novel pyrazolo [4,3-g] pteridines and evaluating their anti-inflammatory and antibacterial activities. Results and DiscussionChemistry The key intermediate,2) was obtained via the reaction of the pyrazolo[3,4-b]-pyrazine amino acid 1 with boiling acetic anhydride. The IR spectrum of 2 displayed a characteristic absorption band at 1750 cm −1 attributed to the C=O function of the six membered lactone and also showed the disappearance of absorption bands of the acidic OH and NH 2 groups and that refers to its involvement in the cyclization process. The reaction of 2 with ammonium acetate at 160-170°C led to the formation of the parent pyrazolopteridinone 3. Its IR spectrum showed characteristic absorption bands at 3210 and 1665 cm −1 due to NH and C=O functions. Also, the structure of 3 was fully supported by its 1 H-NMR spectrum, which displayed a characteristic singlet at δ 8.9 ppm integrating for one NH proton (D 2 O exchangeable). The protons of the methyl group were observed as two singlets at δ 2.66, 1.95 ppm. The reaction of 2 with ethyl glycinate in refluxing pyridine gave ethyl 2-(3,7-dimethyl-5-oxo-1H-1-pheny-5,6-dihydropyrazolo[4,3-g]-pteridin-6-yl) acetate (4) (Method A). The same product could be obtained unequivocally by reacting 3 with ethyl chloroacetate in boiling pyridine (Method B). However when the latter reactio...
5-(2-Aminothiazol-4-yl)-8-hydroxyquinoline 2 has been synthesized by treating thiourea with 5-chloroacetyl-8-hydroxyquinoline 1. The amine 2 was treated with aromatic aldehydes to furnish schiff bases 6a-c which on treatment with phenyl isothiocyanate gave the corresponding thiazolo-s-triazines 7a-c. Reaction of 2 with phenyl isothiocyanate gave the corresponding aminocarbothiamide derivative 8 which on reaction with malonic acid in acetyl chloride afforded thiobarbituric acid derivative 9. Coupling of 9 with diazonium salt gave the phenyl hydrazono derivative 10. However, reaction of 2 with carbon disulphide and methyl iodide afforded dithiocarbamidate 12 which on treatment with ethylenediamine, o-aminophenol and/or phenylenediamine gave the aminoazolo derivatives 13-15, respectively. Other substituted fused thiazolopyrimidines 16-20 have been also prepared by the reaction of 2 with some selected dicarbonyl reagents. The characterisation of synthesized compounds has been done on the basis of elemental analysis, IR, 1 H-NMR and mass spectral data. All the newly synthesized compounds have been screened for their antimicrobial activities.
The present work describes the synthesis of a novel series of heterocyclic moieties derived from 5-acetylpyrazolo[3,4-b]pyridine (1). The formation of chalcones (2a-d) was utilized to synthesize pyrazoline, isoxazoline and pyrimidine derivatives (3-10). Thiosemicarbazone and semicarbazone (11, 17) were utilized to synthesize other new triazolethiones, thiadiazole and selenadiazole derivatives (11-19). Some new spiro derivatives (22-25) were synthesized by the reaction of chalcone (21) of 1 and isatine with hydrazines, hydroxyl amines and thiourea. Also, The reaction of 1 with cyanoacetyl hydrazine gave the hydrazide-hydrazone derivative 26, which was allowed to react with aromatic aldehydes and α-cyanocinnamonitrile to afford coumarine and substituted pyridine derivatives (28, 29). The structures of all the new compounds have been established on the basis of their analytical and spectral data. Twenty two of the synthesized compounds were also evaluated for their antibacterial and antifungal activity against various strains of bacteria and fungi and most are found to possess promising antimicrobial activity when compared with Chloramphenicol and Clotrimazole
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