Sulfinylation

Sulfinylation is a chemical process in which a sulfinyl group (−S(=O)−) is introduced into a molecule. In common usage it refers to the formation of sulfoxides (R–S(=O)–R′), but the term can also describe reactions that append sulfinyl fragments to substrates. The sulfinyl group is the defining feature of sulfoxides, in which sulfur bears a partial double bond to oxygen and resides in the +4 oxidation state.

Two principal modes characterize sulfinylation. Oxidative sulfinylation converts sulfur-containing substrates, such as thioethers, into sulfoxides by oxidation with reagents like hydrogen peroxide, m-chloroperbenzoic acid, or other peracids, often under catalytic or controlled conditions to influence stereochemistry. Direct sulfinylation employs sulfinylating reagents to attach a −SO− fragment to carbon centers or heteroatoms, enabling formation of sulfinylated products that may be further transformed into sulfoxides or related derivatives.

Scope and selectivity vary with the method. Oxidative sulfinylation is widely used to convert sulfides to sulfoxides, frequently delivering high chemoselectivity for the sulfur center. Direct sulfinylation can target arenes, alkenes, or nucleophiles and may involve sulfur dioxide surrogates or specialized sulfinylating agents to install the sulfinyl group before subsequent oxidation or functionalization.

Applications of sulfinylation products are broad. Sulfoxides are important in organic synthesis as intermediates, chiral auxiliaries, and ligands for catalysis. They also appear in pharmaceuticals, agrochemicals, and materials, and in flavors and fragrances. Ongoing developments aim to improve selectivity, scope, and atom economy in sulfinylation protocols.