Highly Enantioselective Phase‐Transfer‐Catalytic Alkylation of 2‐Phenyl‐2‐oxazoline‐4‐carboxylic Acid <i>tert</i>‐Butyl Ester for the Asymmetric Synthesis of α‐Alkyl Serines

Abstract

A facile synthesis of chiral α-alkyl serines 3 involves the asymmetric alkylation of substrates 1 with alkyl halides (RX) under phase-transfer catalysis (PTC), followed by acidic hydrolysis of the alkylation products 2. The phenyl oxazoline moiety enhances the acidity of the α proton of the ester and is an excellent protecting group for both the amino and hydroxy functions of the serine ester.