New synthetic routes to optically active α-quaternary α-aryl amino acid derivatives via the diastereoselective Stevens and Sommelet–Hauser rearrangements

The Stevens rearrangement of N-allylic α-aryl amino acid-derived ammonium salts and the Sommelet–Hauser rearrangement of N-benzylic α-alkyl amino acid-derived ammonium salts are shown to proceed with remarkably high levels of diastereoselectivity. The methods presented in this work provide new routes to optically active α-quaternary α-aryl amino acid derivatives