Photocatalysis Enables Chemodivergent Radical Polar Crossover: Ritter-Type Amidation vs Heck-Type Olefin...

Three-component alkene difunctionalization reactions constitute an ideal platform to rapidly build molecular complexity, enabling the simultaneous introduction of two distinct, orthogonal functional groups into the C═C bond in a single step. Herein, a photoredox catalyzed Ritter-type carboamidation of electronically diverse styrenes harnessing non-stabilized, nucleophilic primary radicals generated from readily-accessible carboxylic acid-derived redox active esters is reported. Furthermore, it is found that Heck-type products are chemoselectively obtained by simply switching aryl olefin acceptors with 1,1-diarylolefins. In the context of photocatalytic chemodivergent radical polar crossover, the synthesis of various trisubstituted alkenes was achieved, simultaneously revealing a divergence in the activation of redox-active esters toward reduction. In-depth mechanistic studies demonstrated both transformation pathways, while DFT calculations indicated the origin of product switchability. Both Ritter-type and Heck-type olefin carbofunctionalizations are scalable up to 4 mmol scale in batch and continuous flow, proving the synthetic utility of the methodology.