Modular Enantioselective Synthesis of cis-Cyclopropanes through Self-Sensitized Stereoselective Photodecarboxylation with Benzothiazolines

Chiral cis-cyclopropanes are strained rigid analogues of alkyl chains, whose study and application are limited by their difficult synthesis. A modular approach from olefin materials is enabled by the discovery of the electron donor-acceptor (EDA) interaction between 2-substituted benzothiazolines and N-hydroxyphthalimide esters. These complexes are activated by visible light without photocatalysts, and the benzothiazoline reagent plays a triple role as a photoreductant, a stereoselective hydrogen-atom donor, and a Bronsted acid. Beyond the enantioselective synthesis of cis-cyclopropanes, these results introduce benzothiazolines as accessible and easily tunable self-sensitized photoreductants.

Automated summary

A modular approach from olefin materials to the synthesis of chiral cis-cyclopropanes is enabled by the discovery of the electron donor-acceptor interaction between 2-substituted benzothiazolines and N-hydroxyphthalimide esters. These complexes are activated by visible light without photocatalysts, with benzothiazoline reagent serving as a photoreductant, stereoselective hydrogen-atom donor, and a Bronsted acid. This study introduces benzothiazolines as accessible and easily tunable self-sensitized photoreductants, expanding their potential applications beyond enantioselective synthesis of cis-cyclopropanes.