Asymmetric synthesis of alpha,alpha-disubstituted amino acids by diastereoselective functionalization of enantiopure phenyloxazinones, derivatives of asymmetric Strecker reaction products of aldehydes
Ding, K.; Ma, D.
Tetrahedron 57(30): 6361-6366, 23 July
Esterification of the asymmetric Strecker reaction products of a suitable and aldehyde and (R)-phenylglycinol followed by lactonization and alkylation provides chiral oxazinones 5. Treatment of the enolates 5 with active alkyl halides, or aldehydes provided the corresponding functionalization products with high diastereoselectivity. The configuration of newly created quaternary carbon is S for the products coupled with simple alkyl halides and aldehydes, and R for the products coupled with methyl bromoacetate. Deprotection of these products afforded the corresponding enantiopure alpha,alpha-dialkyl amino acids.