Abstract O-phosphorylated peptide and amino acid are important in living system. In this paper, Dialkyl-N, N-dialkyl phosphoramidites (DDPA) 3 were synthesized using two methods. The reaction of DDPA with the hydroxyl group of the corresponding amino acids in the presence of tetrazole, followed by oxidation, gave O-phosphoryl amino acid methyl esters in a good yield. A systematical study of the reactivity of DDPA was presented too.
