Asymmetric Synthesis of Optically Active 3-Cyclohexene-1-carboxylic Acid Utilizing Lactic Ester as a Chiral Auxiliary in the Diastereoselective Diels–Alder Reaction

The optically active 3-cyclohexene-1-carboxylic acid was synthesized through a TiCl4-catalyzed diastereoselective Diels–Alder reaction utilizing lactic acid ester as a chiral auxiliary, which can be removed by washing with H2O. The (S)- and (R)-isomers were both derived from easily available ethyl l-lactate.