Radical–Radical Cross-Coupling for C–S Bond Formation

Abstract

A new method was demonstrated to overcome the selectivity issue of radical-radical cross-coupling toward the synthesis of asymmetric diaryl thioethers. The preliminary mechanism was revealed by radical-trapping experiments, DFT calculations, and kinetics, etc., indicating that the C-S bond formed through cross-coupling of a thiyl radical and an aryl radical cation. Moreover, the formation of an aryl radical cation instead of the C-H bond cleavage was determined as the rate-limiting step.

Electrocatalytic Oxidant‐Free Dehydrogenative C−H/S−H Cross‐Coupling

“…At the same time, N ‐methylindole can also be oxidized by the anode to generate a radical‐cation intermediate. The generated indole radical‐cation intermediate can undergo either direct coupling with the sulfur radical or radical substitution with the generated disulfide 5 a to afford a hydroindole cation intermediate . Final deprotonation of the cation intermediate leads to the formation of the C−S bond‐formation product.…”

Tuning radical reactivity for selective radical/radical cross-coupling

“…On the other hand, overactive intermediate could not play the role of radical pool. In 2016, we successfully synthesized non-symmetric diaryl thioethers through radical/radical cross-coupling (Scheme 5) [30]. The preliminary mechanistic studies showed that the CAS bond formation achieved through the cross-coupling of thiyl radical and aryl radical.…”

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

“…However, the protocols require prefunctionalized sulfenylating reagents. Recently Lei and co-workers reported a DDQ-mediated selective radical–radical cross coupling between electron-rich arenes and thiols [ 40 ]. Miyake et al reported the visible light-promoted cross-coupling reaction between aryl halides and arylthiols via an intermolecular charge transfer using Cs 2 CO 3 as base [ 41 ].…”