Studies on Ketene and Its Derivatives. CXX. Preparation of Acetyldipeptides Using Acetoacetyl Amino Acids

Abstract

Ethyl N-acetoacetylglycinate (1a), which was easily prepared from ethyl glycinate and diketene, was treated with hydrogen azide in concentrated sulfuric acid (Schmidt reaction) to give ethyl N-(N-acetylglycyl) glycinate (2a). Similarly, N-(α-alkylated acetoacetyl) glycinates 1b-f were transformed into the corresponding N-acetyldipeptides 2b-f by the Schmidt reaction. Treatment of optically active N-acetoacetyl-l-3-phenylalanine (3a) and N-acetoacetyl-l-leucine (3b) with hydrogen azide afforded N-(N-acetylglycyl)-3-phenylalanine (4a) and N-(N-acetylglycyl)-leucine (4b), respectively.