The transformations of 4‐heteroarylaminomethylene‐5(4H)‐oxazolones into dehydropeptide derivatives

Abstract
2‐Phenyl‐4‐heteroarylaminomethylene‐5(4H)‐oxazolones 3, which were prepared from the corresponding N,N‐dimethyl‐N'‐heteroarylformamidines 1 and hippuric acid 2 in acetic anhydride, react with amino acids giving dehydropeptide derivatives 4, 5, and 6 as products. Dehydration of N‐protected peptides 7–10, containing glycine at the C‐terminal, followed by the reaction with formamidines 1 gave 2‐substituted‐4‐heteroarylaminomethylene‐5(4H)‐oxazolones 11–14.