Enantioselective Diels–Alder reactions catalyzed by samarium iodo binaphthoxides

Two trivalent samarium iodo binaphthoxide complexes have been investigated as catalysts for enantioselective Diels–Alder reactions. Enantiomeric excesses were improved using 3,3′-bis-orthoanisyl binaphthol as ligand compared to binaphthol, with values up to 81% for the major endo-isomer. Performing reactions at different temperatures gave a reversal in the prevailing product configuration.