Synthesis and resolution of dhcga, a new conformationally rigid 3,4-dehydroglutamic acid analogue

Abstract (±)-1-amino-2-cyclohexene-1,3-dicarboxylic acid (DHCGA),an unsaturated cyclic analogue of glutamic acid, was prepared from 3-carboxy-4-cyclohexenone by a Bucherer-Bergs reaction. Resolution was performed through coupling with L-leucine and separation of the resulting diastereoisomeric dipeptides. Spectral data, including optical rotation and circular dichroism of both enantiomers of DHCGA are reported.