Preparation of a Protected (2S,3S)-β-Hydroxyaspartic Acid Suitable for Solid-Phase Peptide Synthesis

Article abstract of DOI:10.1021/jo00313a015

(2S,3S)-N-Boc-3-(benzyloxy)aspartic acid β-benzyl ester (2), a β-hydroxyaspartic acid derivative suitably protected for incorporation into peptides by solid-phase synthesis, was synthesized from N-Boc-(R)-serine via the intermediate, <4R-(R*,R*)>-4->hydroxy>2-(trimethylsilyl)ethynyl>methyl>-2,2-dimethyl-3-oxazolidinecarboxylic acid 1,1-dimethylethyl ester (5).Key transformations involved the ruthenium tetraoxide mediated oxidation of the ethynyl moiety to form the β-carboxylic acid and, after esterification and oxazolidine ring hydrolysis, dichromate oxidation of the resulting primary alcohol to the α-carboxylic acid.The method is suitable for the preparation of gram quantities of 2.