REGIOSELECTIVE SYNTHESIS AND SPECTRAL CHARACTERIZATION OF ETHYL (Z)-2-ALKYLIDENE-4-OXOTHIAZOLIDINE-5-ACETATE DERIVATIVE AND (E)-2-ALKYLIDENE-4-OXOTHIAZOLIDINE-5-ACETATE DERIVATIVES - SOLVENT EFFECTS ON THE Z-EISOMERIZATION

The title compounds containing an exocyclic double bond of exclusively the Z-configuration were prepared in anhydrous ethanol by the regiose lective base catalyzed reaction of diethyl 2-mercaptobutanedioate with nitrile precursors possessing an acidic a-hydrogen. The H-1 NMR data indicating the presence of both geometrical isomers in primarily nonpo lar media favoring the form are presented in terms of the solvent infl uence on intra- and intermolecular H-bonding and stereochemical outcom e of the reaction.