Chiral Ruthenium Lewis Acid Catalyzed Intramolecular Diels−Alder Reactions

Single point binding ruthenium Lewis acid catalysts [Ru(acetone)(S,S)-BIPHOP-F)Cp][SbF6] ((S,S)-1b) and [Ru(acetone)(S,S)-BIPHOP-F)(indenyl)][SbF6] ((S,S)-1c) efficiently catalyze intramolecular Diels−Alder (IMDA) reactions under mild conditions to afford the endo cycloaddition products as the major product in excellent yields with high diastereo- and enantioselectivities.