Takayuki Shioiri

Phosphorus in organic synthesis—VII : Diphenyl phosphorazidate (DPPA). A new convenient reagent for a modified curtius reaction☆☆☆

Abstract A simple one-step conversion of carboxylic acids to urethanes was achieved by diphenyl phosphorazidate (DPPA). The reaction procedure is quite simple, occurring by refluxing an equimolecular mixture of a carboxylic acid, DPPA, and triethylamine in the presence of a hydroxyl component. Aromatic, aliphatic, and heterocyclic carboxylic acids underwent rearrangements in satisfactory yields. As this modified Curtins reaction is much simpler and less laborious than the classical Curtius reaction and proceeds under mild conditions, it may have a broad synthetic utility.

Phosphorus in organic synthesis—XI Amino acids and peptides—XXI : Reaction of diethyl phosphorocyanidate(DEPC) with carboxylic acids. A new synthesis of carboxylic esters and amides☆☆☆★

Abstract Diethyl phosphorocyanidate(DEPC) reacts with carboxylic acids in the presence of triethylamine leading to transient formation of acyl cyanides, but in presence of alcohols or amines, carboxylic esters or amides are produced. DEPC is especially effective for the synthesis of amides and peptides, and showed a satisfactory result on the Young racemization test.

Synthetic simulation of nonribosomal peptide biosynthesis. A dual role of alkylthiol esters in peptide synthesis

Coupling of peptide alkylthiol esters with amino acid derivatives in the presence of pivalic acid or 2-hydroxypyridine proceeds without racemization. A dual role of alkylthiol esters as protective and reactive functions in peptide synthesis was well proved.

A method for sequencing peptides: A co-operation of diphenyl phosphorazidate and 2-mercapto- or 2-hydroxypyridine for N-acyldiketopiperazine formation

A new method for sequencing peptides is proposed. As a model experiment for this, Bz-Gly-Pro-OH and Bz-Gly-Sar-OH were conveniently converted to their diketopiperazine derivatives by a co-operation of diphenyl phosphorazidate and 2-mercapto- or 2-hydroxypyridine.