Transformations of 5-chloro-2-hydrazino-4- p-tolylsulfonyl-1,3-thiazole.

Accessible 2,2-dichloro-1- p-tolylsulfonylethenyl isothiocyanate reacted with hydrazine hydrate to give 5-chloro-2-hydrazino-4- p-tolylsulfonyl-1,3-thiazole whose reactions with thiols and amines followed a complicated pattern. Treatment of 5-chloro-2-hydrazino-4- p-tolylsulfonyl-1,3-thiazole with acetylacetone led to the formation of previously unknown 5-chloro-2-(3,5-dimethyl-1 H-pyrazol-1-yl)-4- p-tolylsulfonyl-1,3-thiazole which reacted with O-, S-, and N-centered nucleophiles at the C5 atom with high regioselectivity. [ABSTRACT FROM AUTHOR]