Remarkable solvent effect on the enantioface selectivity in the Diels- Alder reaction catalyzed by an aluminum complex of a newly prepared chiral menthol derivative

Reversal of enantioface selectivity was observed by merely switching the solvent from CH₂Cl₂ (enantiomer ratio of the adduct = 91:9) to THF (14:86) in the asymmetric Diels-Alder reaction catalyzed by the aluminum complex of a newly prepared chiral menthol derivative. Negative nonlinear effect on the relationship between enantiomeric excesses of the reaction product and optical purities of the ligand was observed for the reaction in CH₂Cl₂ whilst linear relationship for that in THF.