Jm. Harris et al., SYNTHESIS OF CHIRAL DIAZANEDICARBOXYLATE AND DIAZENEDICARBOXYLATE ESTERS - ELECTROPHILIC AMINATION REACTIONS OF ACHIRAL ESTER AND AMIDE ENOLATES, Journal of the Chemical Society. Perkin transactions. I, (15), 1995, pp. 1945-1950
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.