With acetyl chloride as the solvent, the condensation reaction of p-toluenesulfonamide, an aromatic aldehyde and phenyldichlorophosphine gives a reactive intermediate, a-(p-toluenesulfonyl)-aminobenzylphosphinic chloride, which reacts with glycine ethyl ester to give the corresponding phos-phinopeptide (6) containing a P-N bond directly.