Synthesis of N-alkoxycarbonyl-3-substituted tetramic acids and functionalized enols via C-acylation reactions of active methylene compounds with N-hydroxysuccinimide esters of N-alkoxycarbonyl-α-amino acids

The N-hydroxysuccinimide esters of N-alkoxycarbonyl-alpha-amino acids react with active methylene compounds (malonic and acyl acetic esters),under basic conditions, to produce N-alkoxycarbonyl-3-substituted tetramic acids 7-17; in the case of the N-hydroxysuccinimide ester of L-alanine, the corresponding optically active tetramic acids 15 and 16 are obtained. In addition, the C-acylation reactions of cyanoacetic esters furnishes the functionalized enols 18-23 in very good yields. Spectral data and physical characteristics for all compounds:are reported.