Studies on reactions of the N-phosphonium salts of pyridines—VII : Preparation of peptides and active esters of amino acids by means of diphenyl and triphenyl phosphites in the presence of tertiary amines

Peptides and active esters of amino acids were produced in high yields from carboxyl and amino or hydroxyl components in pyridine with an equivalent amount of diphenyl phosphite or half an equivalent amount of triphenyl phosphite and tertiary amines. Condensation reactions competed with the reaction with a phenoxy group of the phosphite to produce the phenyl ester and were governed by the tertiary amine employed in the reaction. The reactions are assumed to proceed via the N- phosphonium salts of pyridines, similar to those obtained by the oxidation of phosphorus compounds with mercuric salts in pyridine.