Counteranion-Controlled Chemodivergent Transfer-Hydrothiolation/Carbothiolation Using Thioethers as Bifunctional Reagents

The pursuit of catalysis capable of forging C(sp³)─S bonds is extremely desired because these bonds have substantial importance in pharmaceuticals, functional materials, and organic synthesis. Hydrothiolation and carbothiolation of feedstock alkenes are among the most straightforward and prominent approaches to C(sp³)─S bond formations. However, hydrothiolation of alkyl-substituted alkenes typically proceeds in an anti-Markovnikov fashion, and carbothiolation predominantly relies on three-component coupling strategies using highly reactive pre-functionalized electrophilic sulfur sources and nucleophilic carbon sources. Herein, by strategically using heterolytic cleavage of C(sp³)─S bond, we report a chemodivergent transfer-hydrothiolation and carbothiolation of alkenes with thioethers serving as bifunctional reagents. The chemo-control is achieved through careful selection of the counteranion associated with the Rh-center. Counteranions with relatively strong coordinating ability, such as TfO⁻, promote an unusual Markovnikov transfer-thiol-ene reaction. Conversely, noncoordinating counteranions, such as BF₄⁻, enable an unprecedented intermolecular thioether-ene reaction that adds thioethers directly across alkenes. Mechanistic and computational studies elucidated that the coordination or noncoordination of counteranions on Rh can alter the basicity of the thiolate, resulting in chemodivergence.