Homologation of alpha-amino acids to beta-amino acids:9-Fluorenylmethyl chloroformate as a carboxyl group activating agent for the synthesis of N~(alpha)-protected aminoacyldiazomethanes

摘要

An efficient and stereospecific homologation of urethane-protected or-amino acids to beta-amino acids by Arndt-Eistert approach using an equimolar mixture of Fmoc-/Boc-/Z-or-amino acid and 9-fluorenylmethyl chloroformate for the acylation of diazomethane synthesizing the key intermediates Fmoc-/Boc-/Z-ar-aminoacyldiazo-methanes as crystalline solids is described.They are then converted to the corresponding beta-amino acids using silver benzoate/l,4-dioxane-water under microwave irradiation.All the protected beta-amino acids prepared have been obtained in good yield as well as purity.