A Facile Synthesis of Some New Thiazolo[3, 2]pyridines Containing Pyrazolyl Moiety and Their Antimicrobial Activity

Abstract

Condensation of 2-cyanomethyl-4-thiazolinone 1 with 1,3-diphenyl-pyrazole-4-carboxaldehyde 2 in ethanol containing a few drops of piperidine yielded the novel methylene derivative 3 . Compound 3 was refluxed with malononitrile to give the corresponding thiazolo[ ^[3] , ^[2] ]pyridine derivative 5 . Also, treatment of compound 3 with benzylidenemalononitriles gave the thiazolo[ ^[3] , ^[2] ]pyridine derivatives 6a–e . Refluxing of compound 6d with triethyl orthoformate furnished the ethoxymethylideneamino derivative 7 . Formic acid and malononitrile were reacted with compound 6d to produce thiazolo[ ^[3] , ^[2] ][ ^[1] , ^[8] ]naphthyridine derivative 8 and 11 , respectively. Condensation of 2 with cyanoacetohydrazide in ethanol containing piperidine as catalyst gave the hydrazone derivative 12 which, on treatment with salicyaldehyde and 2-cyano-3-(4-fluorophenyl)acrylic acid ethyl ester, yielded the novel chromene 13 and pyridinone 14 , respectively. Structures of the synthesized compounds have been established by elemental analysis and spectral data. Compounds 3 , 5 , 6a–d , 8 , 11 , 13 , and 14 have been screened for antimicrobial activities.

Key Words:

• 1,3-Diphenyl-pyrazole
• thiazolo[3, 2]pyridines
• thiazolo-naphthyridines and antimicrobial activity