X=Y-ZH SYSTEMS AS POTENTIAL 1,3-DIPOLES. PART 20. DECARBOXYLATION OF α-IMINO ACIDS. MECHANIZM AND APPLICATIONS TO THIOAMIDE SYNTHESIS

Article abstract of DOI:10.1016/S0040-4020(01)86099-3

α-Imino acids, prepared from α-keto acids and primary amines, undergo facile decarboxylation to the corresponding imines on heating at <=80 deg C in benzene or methylene chloride.Decarboxylation proceeds via a 1,2-ylide which can be trapped by sulphur to give the corresponding secondary thioamides in good yield. 1,2-Ylides from secondary amines and α-keto acids can be generated in situ and trapped with sulphur to give tertiary thioamides in excellent yield.