Asymmetric Diels-Alder reaction of unsymmetrical maleates: a chemical access to chiral, unsymmetrical cis-cyclohexene-1,2-dicarboxylates

Asymmetric Lewis acid-catalyzed Diels-Alder reaction of chiral, unsymmetrical maleates yields optically-active, unsymmetrical cis-cyclohexane-1,2-dicarboxylate derivatives. The high diastereoselectivity of the reaction indicates an attractive pi-pi interaction between the maleate C double bond C and the phenyl groups of chiral supplements such as alpha-phenethyl and trans-2-phenylcyclohexyl groups.