HETEROCYCLIC SYNTHESIS WITH ISOTHIOCYANATES - AN EXPEDITIOUS SYNTHETIC ROUTE FOR POLYFUNCTIONALLY SUBSTITUTED 3-(THIAZOL-2'-YLIDENE)PYRIDINES AND THEIR FUSED DERIVATIVES

The reaction of phenyl isothiocyanate with the Knovenagel condensated active methylene compounds 1a-d gave the non-isolable salts 3a-d. The latter underwent in-situ heterocyclization on treatment with some halo genated compounds e.g. phenacycl bromide, ethyl bromoacetate, gamma-br omoacetoacetanilide, ethyl gamma-bromoacetoacetate and gamma-bromo-bet a-oxo-butyronitrile into the corresponding polyfunctionally substitute d 3-(thiazol-2'-yliene)pyridine derivatives, which could also be annul ated into fused heterocyclic ring systems. Chemical and spectroscopic evidences for the structure of the new compounds are described.