Cation Radical Newman‐Kwart Rearrangement Enabled by Heterogeneous Photocatalysis under Mild Conditions

Abstract

A photochemical rearrangement of O‐aryl thiocarbamates to the corresponding S‐aryl compounds that is triggered by heterogeneous electron transfer between the substrate and photo‐excited titanium dioxide is presented. The rearrangement is the key‐reaction in the three‐step conversion of phenols into the corresponding thiophenols. The described procedure can be performed at room temperature under aerobic conditions using violet LEDs. The rearrangement has been achieved for 24 electron‐rich substrates with yields up to 99 %. A plausible mechanism is proposed based on the substrate scope, spectroscopic studies, and control experiments.