Rhodium-Catalyzed Asymmetric [2+2+2] Cycloaddition of Unsymmetrical α,ω-Diynes with Acenaphthylene

It has been established that a cationic rhodium-(I)/(R)-BINAP complex catalyzes the asymmetric [2 + 2 + 2] cycloaddition of unsymmetrical alpha,omega-drynes with acenaphthylene at room temperature to give the corresponding chiral multicyclic compounds with high yields and ee values. Interestingly, enan-tioselectivity highly depended on the structures of alpha,omega-diynes used. The structural requirements of alpha,omega-diynes for high enan-tioselectivity were opposite to those in our previously reported cationic rhodium(I)/(R)-Difluorphos complex-catalyzed asymmetric [2 + 2 + 2] cycloaddition of alpha,omega-diynes with indene.