SYNTHESIS OF CHIRAL DIAZANEDICARBOXYLATE AND DIAZENEDICARBOXYLATE ESTERS - ELECTROPHILIC AMINATION REACTIONS OF ACHIRAL ESTER AND AMIDE ENOLATES

A series of chiral dialkyl (bornyl, isobornyl, menthyl) diazenedicarbo xylates 4a-c were prepared by conversion of the corresponding alcohols into chloroformates, condensation with hydrazine, and oxidation of th e corresponding dialkyl diazanedicarboxylates 3a-c with N-bromosuccini mide and pyridine (50-90% yield). Their reaction with achiral enolates of esters and N,N-dimethyl amides at - 78 degrees C gave alpha-hydraz ino acid derivatives with little or no stereoselectivity. Analogous am inations of chiral oxazolidinone (Evans enolate) anions were highly se lective, but were controlled exclusively by enolate geometry.