Rhodium-Catalyzed Asymmetric [2+2+2] Cycloaddition Reactions of 1,6-Enynes and Oxabenzonorbornadienes

The asymmetric [2+2+2] cycloaddition reactions of 1,6-enynes and oxabenzonorbornadienes was accomplished by using the complex of [Rh(COD)(2)]BF4 and (R)-Xyl-P-Phos as chiral catalyst. A range of 1,6-enynes and oxabenzonorbornadienes were well tolerated in the cycloaddition reaction, which afforded various polycyclic products with asymmetric quaternary carbon centers generally in excellent enantioselectivities.