Peptide and active ester formation by means of diaryl sulfites in pyridines

Abstract Peptides and active esters of amino acids were obtained under mild conditions by mixing sulfites with a mixture of carboxyl and amino or hydroxyl components in tertiary amines. Of several sulfites and tertiary amines examined, diphenyl sulphite and pyridine and 3- or 4-methylpyridines were most effective. The reaction mechanism is discussed.