Sulfonylcarbamates as Amino Protecting Groups in Peptide Chemistry

Abstract

In a search for new peptide coupling agents N-acetyl-L-phenylalanine and methyl L-alaninate were treated with p-tosylisocyanate in the hope of obtaining the model racemization peptide methyl N-acetyl-L-phenylalanyl-L-alaninate and benzenesulfonamide.¹ Instead, the reaction gave in moderate yield alanyl tosylhydantoin, identified by an independent synthesis and spectral data. This result suggested that the treatment of an amino acid (1) with p-tosyliso-cyanate (2) would yield the corresponding p-tosyl-aminocarbonyl derivative (3) or Tac-Amino acid.