The Behavior of (cyclic-alkylidene)hydrazinecarbothioamides in Cyclization with Dimethyl acetylenedicarboxylate.

A series of ( Z)-methyl 2( Z)-3-substituted-2-(cycloalkylidenehydrazono)-4-oxothiazolidin-5-ylidene)-acetate derivatives were synthesized via condensation alkylidene- N-substituted hydrazinecarbothioamides with dimethyl acetylenedicarboxylate. The synthesized compounds were characterized by using different spectroscopic methods and confirmed by single crystal X-ray analysis. The behavior of (cyclic-alkylidene) hydrazinecarbothioamides in cyclization was presented. The mechanism of transformation of ( Z)-methyl 2-(( Z)-3-(cyclopentylideneamino)-4-oxo-2-(phenylimino)thiazolidin-5-ylidene)acetate ( 14) into the more stable ( Z)-Methyl 2-[( Z)-2-(cyclopentylidenehydrazono)-4-oxo-3-phenylthiazolidin-5-ylidene]acetate ( 5a) was discussed and confirmed. [ABSTRACT FROM AUTHOR]