Studies on thiazolopyridines.: Part 1:: Antimicrobial activity of some novel fluorinated thiazolo[3,2-a]pyridines and thiazolo[2′,3′:1,6]pyrido[2,3-d]pyrimidines

Ternary condensation of aromatic aldehydes, malononitrile and thioglycolic acid (2:2:1 molar ratio) in ethanol/piperidine afforded the corresponding thiazolo[3,2-a]pyridines 1a-d. Thiazolo[2',3':1,6]-pyrido[2,3-d]pyrimidine 4 was obtained by refluxing of compound la with acetic anhydride. Also, thiazolopyrido pyrimidine 6 was produced by refluxing of la with triethylorthoformate followed by treatment with hydrazine hydrate, Refluxing la with formic acid yielded the thiazolopyridopyrimidine 8 which on chlorination with thionyl chloride furnished the chloro derivative 9. Finally, amino thiazolo[2',3':1,6]pyrido[2,3-d]pyrimidine 10 was obtained by treatment of la with formamide. The structures of these compounds were established on the basis of elemental analyses, IR, H-1 NMR, and mass spectral data. Also, the antimicrobial activity of some synthesized compounds is reported.