L-Aspartic acid by successive N-tosylation, anhydride formation, and reduction was converted into (3 S)-3-(tosylamino)butano-4-lactone ( 4). Electrophilic methylation of 4, subsequent iodo-esterification and nucleophilic methylation, followed by saponification and deprotection, gave (2 S, 3 R)-3-amino-2-methylpentanoic acid ( 2) with an ee of > 99% in seven steps and in an overall yield of 34%.