Catalytic asymmetric [3+2] cycloaddition of isomünchnones with methyleneindolinones.

An efficient enantioselective [3+2] cycloaddition of isomünchnones with methyleneindolinones that are generated by an in situ intramolecular addition of the carbonyl group to rhodium carbenes is realized with a chiral N , N '-dioxide/Zn(II) complex as a Lewis acid. A series of chiral oxa-bridged 3-spiropiperidines are obtained in high yields with excellent dr and excellent ee values.