Exploration of Routes Leading to Derivatives of α‐Hydroxyalanine and its Precursors

The preparation of fully protected derivatives of DL‐α‐hydroxyalanine is described. Several possible routes leading to protected DL‐α‐hydroxyalanine and α‐hydroxyglycine were explored. Attempts to remove the protecting groups led in most cases to the disruption of the molecule. The N‐carboxyanhydride of O‐benzyl‐DL‐α‐hydroxyalanine was prepared and trimerised to give dehydroalanyl‐O‐benzyl‐DL‐α‐hydroxyalanyldehydroalanine. This is a novel type of polymerization of N‐carboxyanhydrides concurrent with elimination of benzyl alcohol. A generally useful method of purification of oily half esters of dicarboxylic acids through their crystalline dibenzylamine salts has been developed.