Author(s): Rekha Parmesh, Lohitha P, Saravanan J
In this present work, a series of new 2-[(substituted benzylidene) imino]-3-(N-cyclohexl carboxamido)-4,5-di substituted thiophenes were synthesized in a multi step method and its structure has been elucidated by elemental analysis and spectral tools.. In the first step N-cyclohexyl cyano acetamide MSR-5 was synthesized by the condensation of Cyclohexylamine and Ethyl cyano acetate. Reaction of compound MSR-5 with methylenic ketone using ammonium acetate and glacial acetic acid as an acidic catalyst was carried out by refluxation in benzene for 8hrs by employing Dean Stark apparatus afforded 2-Cyano –2- (alkylidene)-N-cyclohexyl carboxamides [I]. Compound [I] represents the important key intermediate from which all the new target polysubstituted thiophenes were synthesized thus compound  was introduced in reaction by dissolving in alcohol react with elemental sulfur in the presence of basic catalyst, diethyl amine in ethanol to form 2-amino-3-(cyclohexyl carboxamido)-4,5-di substituted thiophenes MSR-11 & 12. In the final step a new series of compounds were synthesized from 2-amino-3-N-cyclohexyl carboxamido-4,5-disubstituted thiophenes (MSR-11&12) by heating in a microwave oven with various substituted aromatic aldehydes in isopropyl alcohol with glacial acetic acid as a catalyst to yield 2-[(substituted benzylidene) imino]-3-(N-cyclohexl carboxamido)-4,5-disustituted thiophenes MSR-11a-11k & MSR-12a-12k.