Diastereo- and enantioselective construction of spirooxindole scaffolds through a catalytic asymmetric [3 + 3] cycloaddition

A chiral phosphoric acid-catalyzed asymmetric [3 + 3] cycloaddition of C3-substituted 2-indolylmethanols with isatin-derived azomethine ylides has been established, which afforded chiral spirooxindoles in considerable yields, moderate to good enantioselectivities and excellent diastereoselectivities (up to 85% yield, 96 : 4 er, all >95 : 5 dr).