Sarylation

Sarylation, often written as S-arylation, is a chemical process in which an aryl group is transferred to sulfur to form an aryl sulfide, also known as a thioether. The term is not uniformly used in textbooks, and in many contexts the reaction is described as S-arylation of thiols or arylation of sulfur.

Two broad approaches predominate. One involves nucleophilic S-arylation of thiols with activated aryl electrophiles, such as aryl sulfonates or aryl diazonium salts, under suitable conditions to forge the C–S bond. The other, more widely used in modern synthesis, is transition-metal-catalyzed cross-coupling between thiols and aryl halides or related aryl pseudohalides. Palladium-, copper-, and nickel-catalyzed variants have been developed, often employing ligands or copper co-catalysts to promote efficient C–S bond formation. These methods enable the preparation of diverse aryl sulfides from readily available thiols and aryl partners.

Substrates commonly include aliphatic or benzenyl thiols (R-SH) and various aryl partners (Ar–X, where X is I, Br, Cl, or a pseudohalide). Reaction conditions vary widely, from room temperature to elevated temperatures, and from polar aprotic to alcoholic solvents, with bases or bases-free systems depending on the electrophile.

Applications of sarylation products are broad, spanning pharmaceuticals, agrochemicals, and materials science. Aryl sulfides serve as motifs in drug candidates, ligands for metal catalysts, and functional components in organic electronics. Limitations include the need to control mono- versus diarylation, sensitivity of thiols to oxidation, and sometimes harsh conditions or limited substrate scope.

See also: arylation, thioethers, Chan–Lam coupling.