Lewis Base and Brønsted Base Dual-Catalyzed Formal [4+3] Cycloaddition Reaction: Synthesis of Aza-Spirocycloheptane Oxindole.

An intermolecular, quaternary carbon center forming [4+3] cycloaddition reaction catalyzed by Lewis base and Brønsted base has been successfully developed. The dual catalysis exhibits a superior ability to enable a previously challenging reaction, and the corresponding quaternary aza-spirocycloheptane oxindole scaffolds are efficiently synthesized with moderate to high yields. [ABSTRACT FROM AUTHOR]