Sulfurmediated

Sulfur-mediated describes chemical and biochemical processes in which sulfur-containing species play a central mediating role in reaction development, transformation, or catalysis. In organic chemistry, sulfur-mediated transformations often involve thiols, thioethers, sulfonium intermediates, or thiyl radicals that steer bond formation or activation of substrates. Mechanistically, sulfur can act as a nucleophile (via thiolate), an electrophile (through sulfonium), or as a radical mediator (thiyl radical). Sulfur-containing catalysts and ligands can stabilize key intermediates, enable redox cycling, or facilitate selective C–S and C–C bond formation. In biological systems, sulfur mediates redox chemistry and catalysis through cysteine residues, iron-sulfur clusters, and cofactor systems, enabling enzyme catalysis and electron transfer.

Applications are diverse. In organic synthesis, sulfur mediation underpins strategies such as thiol–ene or thiol–yne additions, thioester-based ligations, and transient desulfurization strategies that temporarily install or remove sulfur handles to reprogram reactivity. In polymer science, sulfur-mediated processes underlie vulcanization and related crosslinking, which confer mechanical strength and elasticity. In materials and medicinal chemistry, sulfur mediation supports radical relay, sulfonium-assisted C–H functionalization, and sulfur transfer reactions.

Challenges include controlling selectivity and stability of reactive sulfur species, avoiding off-target oxidation, and managing odor and safety concerns of sulfur reagents. Ongoing research seeks to broaden scope, understand mechanisms, and apply sulfur mediation to sustainable and selective synthesis.