Regioselective synthesis and spectral characterization of ethyl (Z)- and (E)-2-alkylidene-4-oxothiazolidine-5-acetate derivatives. Solvent effects on the Z-E isomerization

Article abstract of DOI:10.3987/COM-97-8094

The title compounds containing an exocyclic double bond of exclusively the Z-configuration were prepared in anhydrous ethanol by the regio-selective base catalyzed reaction of diethyl 2-mercaptobutanedioate with nitrile precursors possessing an acidic α-hydrogen. The ¹H NMR data indicating the presence of both geometrical isomers in primarily nonpolar media favoring the E-form are presented in terms of the solvent influence on intra- and intermolecular H-bonding and stereochemical outcome of the reaction.