Sequential Photocatalytic Reactions for the Diastereoselective Synthesis of Cyclobutane Scaffolds

The synthesis of densely functionalized cyclobutanes containing all-carbon quaternary stereocenters in high regio- and diastereoselectivity remains synthetically challenging. Herein, we show that this can be achieved by using a sequential photocatalysis strategy, wherein 3-chloromaleimides undergo triplet sensitized [2 + 2] photocycloadditions with alkynes or alkenes followed by photoredox-catalyzed dechlorinative C-C bond forming reactions to install quaternary stereocenters. This allows the rapid assembly of structurally complex and sterically congested 3-azabicyclo[3.2.0] heptane scaffolds from readily available starting materials.

Automated summary

This study demonstrates a method for the synthesis of densely functionalized cyclobutanes with high regio- and diastereoselectivity, utilizing a sequential photocatalysis strategy to rapidly assemble structurally complex 3-azabicyclo[3.2.0] heptane scaffolds. The installation of all-carbon quaternary stereocenters is achieved through triplet sensitized [2 + 2] photocycloadditions followed by photoredox-catalyzed dechlorinative C-C bond forming reactions.