Reduction of Sulfoxides and Sulfones to Sulfides
Reduction of Sulfones to Sulfoxides: Mechanism
Sulfones can be reduced to sulfoxides using an indirect procedure. Initially, the sulfone is reacted with 4-chlorophenyldiazonium tetrafluoroborate. Subsequently, the product of the reaction is treated with borohydride to yield the sulfoxide.
In the first step, the reaction mixture is heated and reaction of the diazonium salt with the sulfone under loss of nitrogen takes place.
Subsequently, a hydride ion transfers from sodium borohydride to the positively charged sulfur. At the same time, the aromatic fragment which was added during the first step is eliminated. .
The protonated sulfoxide then loses H+ .