Recent Advances in Nucleophilic Lewis Base-Catalyzed Cycloadditions for Synthesis of Spirooxindoles

Spirooxindoles are privileged scaffolds in diverse bioactive natural products and pharmaceuticals, significant achievements for the construction of these molecules have thus been made in the past years. Among them, organocatalysis, in particular, nucleophilic Lewis base catalysis, has recently emerged as an efficient and reliable method for the preparation of diverse and valuable functionalized spirooxindoles. According to different kinds of nucleophilic catalysts, we summarize and classify three catalytic strategies; these are tertiary amine-catalyzed cycloadditions, NHC-catalyzed cycloadditions, and tertiary phosphine-catalyzed cycloadditions, respectively. Through these methods, potential bioactive spirooxindole skeletons owning various functional groups can be produced to enrich the small organic molecule library. In this review, we describe a comprehensive and updated advances of nucleophilic Lewis base catalytic cycloaddition reactions for the construction of spirooxindoles. Meanwhile, the related mechanism and the application of these annulation strategies in natural product total synthesis will be highlighted in detail. image