Photocatalyzed Cascade Hydrogen Atom Transfers for Assembly of Multi‐Substituted α‐SCF₃ and α‐SCF₂H Cyclopentanones

Abstract

A photocatalyzed formal (3+2) cycloaddition has been developed to construct original polysubstituted α‐SCF3 cyclopentanones in a regio‐ and diastereoselective manner. This building block approach leverages trifluoromethylthio alkynes and branched / linear aldehydes, as readily available reaction partners, in consecutive hydrogen atom transfers and C–C bond formations. Difluoromethylthio alkynes are also compatible subtrates. Furthermore, the potential for telescoped reaction starting from alcohols instead of aldehydes was demonstrated, as well as process automatization and scale‐up under continuous microflow conditions. This prompted density functional theory calculations to support a free radical‐mediated cascade hydrogen atom transfer process.