Asymmetric [4 + 3] cycloaddition of hydroxyphenyl indolinones to synthesize novel spirooxindoles†

The first asymmetric [4 + 3] cycloaddition of hydroxyphenyl indolinones has been reported to afford a new series of multisubstituted spirooxindole derivatives embedded with an oxadiazepine scaffold with high stereoselectivities. The reaction proceeds via o-QM intermediates produced in situ from hydroxyphenyl indolinones, which could undergo cyclization with azomethine imines under CPA catalysis to deliver a new class of seven-membered spirocyclic oxindole compounds. High yields, exclusive diastereoselectivities, and excellent enantioselectivities as well as wide substrate scope were obtained in this organocatalytic reaction.