Synthesis of chiral diazanedicarboxylate and diazenedicarboxylate esters: electrophilic amination reactions of achiral ester and amide enolates

Abstract

A series of chiral dialkyl (bornyl, isobornyl, menthyl) diazenedicarboxylates 4a–c were prepared by conversion of the corresponding alcohols into chloroformates, condensation with hydrazine, and oxidation of the corresponding dialkyl diazanedicarboxylates 3a–c with N-bromosuccinimide and pyridine (50–90% yield). Their reaction with achiral enolates of esters and N,N-dimethyl amides at –78 °C gave α-hydrazino acid derivatives with little or no stereoselectivity. Analogous animations of chiral oxazolidinone (Evans enolate) anions were highly selective, but were controlled exclusively by enolate geometry.