Rhodium-catalyzed enantio- and diastereoselective intramolecular [2+2+2] cycloaddition of unsymmetrical dienynes

A cationic rhodium(I)/(R)-H-8-BINAP or (R)-Segphos complex catalyzes an intramolecular 12 + 2 + 21 cycloaddition of unsymmetrical dienynes, leading to fused tri- and tetracyclic cyclohexenes bearing two tertiary or quaternary carbon centers in high yields with high enantio- and diastereoselectivity.