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-a]pyridine derivative 5. Also, treatment of compound 3 with benzylidenemalononitriles gave the thiazolo[3,2-a]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-a][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. Copyright © Taylor & Francis Inc.