A Practical Synthesis of (2S, 3R)‐3‐Amino‐2‐methylpentanoic Acid from L‐Aspartic Acid

Abstract 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%.