 Also, augmented secondary orbital interactions have been postulated as the source of enhanced endo diastereoselection.The addition of a CLA selectively activates one component of the reaction (the diene or dienophile) while providing a stereodefined environment that permits unique enantioselectivity.Koga and coworkers disclosed the first practical example of a catalytic enantioselective Diels-Alder reaction promoted by a CLA - menthoxyaluminum dichloride - derived from menthol and ethylaluminum dichloride.