Anchoring of Fmoc‐amino acids to hydroxymethyl resins

A method to anchor Fmoc‐amino acids to p ‐alkoxybenzyl ester resins without using DMAP is described. Esterification takes place with 3–4 equiv. of Fmoc‐amino acid plus DCC and a slightly lower excess of HOBt in good yields, without racemization or dipeptide formation. Addition of N ‐methylmorpholine to the reaction medium enhances the reaction yield but is accompanied by a small amount of racemization and dipeptide formation. Coupling via Fmoc‐amino acid chlorides has also been evaluated.