A Chiral Nonracemic Enolate with Dynamic Axial Chirality: Direct Asymmetric Alkylation of α-Amino Acid Derivatives (SYNTHETIC ORGANIC CHEMISTRY-Fine Organic Synthesis)

Abstract

The structure of enolate was long believed to be achiral. However, a chiral nonracemic enolate with a racemization barrier of 16 kcal/mol at -78 oC was found to be the crucial intermediate for the asymmetric -methylation of 1 to give 2 in 81% ee and 96% yield. The asymmetric -methylation occurs in other amino acid derivatives (Val, Leu, Trp, His, Tyr, Dopa) in 78-93% ee.