Sulfination

Sulfination is a broad term for chemical processes that introduce a sulfinate group into a molecule or generate sulfinate species. The sulfinate functionality encompasses the sulfinyl-sulfonyl motif, typically described as the sulfinate anion R–SO2− in salts or the related esters R–SO2–OR′. Sulfinates arise from sulfinic acids (R–SO2H) and serve as versatile intermediates in organic synthesis.

In practice, sulfination methods aim to install the SO2R group or convert substrates into sulfinate esters or salts that can be further transformed. Sulfinates are useful as nucleophiles in substitution reactions and can act as handles for subsequent functional-group manipulations. Through additional steps, sulfinate-derived intermediates can be converted into sulfones, sulfonamides, sulfonate esters, and related sulfur-containing functionalities.

Common strategies for sulfination include: (1) nucleophilic sulfination, where a sulfinate salt reacts with electrophiles such as aryl or alkyl halides to form aryl or alkyl sulfinates; (2) electrophilic sulfination, which uses reagents that generate a sulfinylating species that adds to a substrate; and (3) radical or catalytic approaches that generate sulfinyl radicals or equivalents to add to unsaturated substrates. These approaches enable installation of the sulfinate or sulfinyl motif under varying conditions and substrate scopes, often with functional-group tolerance.

Applications of sulfination chemistry include the preparation of sulfinates for cross-coupling and other C–S bond-forming processes, synthesis of sulfonyl-containing pharmaceuticals, dyes, and polymers, and use as intermediate steps toward broader sulfur-oxide chemistries. The field intersects with related transformations such as sulfonation and sulfinylation, while maintaining distinct goals focused on the sulfinate functionality.