Enantioselective rare-earth catalyzed quinone Diels-Alder reactions.

A highly enantioselective, quinone Diels-Alder reaction catalyzed by chiral samarium and gadolinium pyridyl-bis(oxazoline) (pybox) complexes has been developed. The reaction scope has been extended to include three quinones and five dienes, all of which exclusively provide the expected endo product in excellent yields and enantioselectivities.