Simple and stereospecific homologation of urethane-protected α-amino acids to their higher homologs using HBTU

Abstract

A simple, efficient and stereospecific approach for the homologation of urethane-protected α-amino acids to β-amino acids by the Arndt-Eistert method employing Fmoc-/Boc-α-amino acid and 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyl-uronium hexafluorophosphate mixture for the acylation of diazomethane synthesizing the key intermediates Fmoc-/Boc-α-aminodiazomethanes as crystalline solids is described.