A Stepwise, Nitrosonium-Catalyzed Aerobic Oxidation of Thiols to Disulfides and Thiosulfonates

A selective and controllable oxidation of thiols to disulfides
or thiosulfonates has been developed using molecular oxygen, trifluoroacetic
acid, and catalytic NaNO3. Both aromatic and aliphatic
thiols afford high yields. Sequential oxidation from thiols to disulfides
and then to thiosulfonates was observed, with the second step governed
by the acid concentration and substrate steric and electronic effects.
Acid and oxygen cooperatively enable in situ generation
and turnover of the active nitrosonium species.