Derivatives of N-phosphorylamino acids and low-molecular weight peptides are of pharmaceutical interest1'4 and several methods for their synthesis are known. In general, esters of the amino acids or peptides were phosphorylated with phosphoryl chloride or with dialkyl or diaryl phosphorochloridates in nonaqueous solution.'''6 However, N- (dialkoxyphosphoryl) amino acids have hardly been used for the synthesis of N-( ...