Synthesis of (S)‐2‐Methylproline: A General Method for the Preparation of α‐Branched Amino Acids

Abstract Synthesis of (S)‐2‐methylproline: A general method for the preparation of α‐branched amino acids intermediate: 20.0 g (0.109 mol) of (2R,5S)‐2‐tert‐butyl‐1‐aza‐3‐oxabicyclo[3.3.0]octan‐4‐one intermediate: 20.1 g (0.102 mol) of (2R,5S)‐2‐tert‐butyl‐5‐methyl‐1‐aza‐3‐oxabicyclo[3.3.0]octan‐4‐one product: (S)‐2‐methylproline product: (R)‐2‐methylproline