Nitrosation of methyl 2‐cinnamoylamino‐3‐dimethylaminopropenoates. Alkyl N ‐cinnamoyloxalic acid hydroxyimidic amides, intermediates in the synthesis of alkyl 5‐styryl‐1,2,4‐oxadiazole‐3‐carboxylates

Alkyl 2‐(substituted cinnamoylamino)‐3‐dimethylaminopropenoates 5, prepared either from glycine ( 1 ) and substituted cinnamoyl chlorides 2 via oxazol‐5(4 H )‐ones 4 , or from cinnamoylglycinate with t ‐butoxy‐bisdimethylaminomethane, were transformed by nitrosation into 5‐substituted‐1,2,4‐oxadiazole‐3‐carboxylates 8 . The formation of alkyl N ‐cinnamoyloxalic acid hydroxyimidic amides 7, which were isolated as intermediates, represent a novel synthesis of N ‐acyl substituted hydroxyimidic amides.