The Asymmetric Synthesis of α-Amino and α-Hydrazino Acid Derivatives via The Stereoselective Amination of Chiral Enolates with Azodicarboxylate Esters.
The utility of azodicarboxylate esters as (+)NH2 and (+)NH-NH2 synthons in highly diastereoselective reactions with chiral carboximide-derived enolates has been demonstrated.The lithium enolates derived from 4-substituted N-acyl 2-oxazolidinones were found to react with di-tert-butyl azodicarboxylate (DBAD) to afford the derived 2-hydrazido carboxylic acid derivetives in yields in excess of 90 percent.The diastereoselectivities of these reactions ranged from 97percent to greater than 99percent.The subsequent transformation of these adducts to both α-hydrazino and α-amino acids in enantiomeric purities in excess of 99percent is described.
Evans, David A.,Britton, Thomas C.,Dorow, Roberta L.,Dellaria, Joseph F.