Bilateral Unsymmetrical Disulfurating Reagent Design for Polysulfide Construction

Polysulfides are significant compounds in life science, pharmaceutical science, and materials science. Therefore, polysulfide construction is in great demand. The controllable sequential installation of groups on both ends of a S−S motif faces an enormous challenge owing to the reversible nature of the covalent S−S bond. A library was established with two divergent mask groups for bilateral unsymmetrical disulfurating reagents (R¹O−SS−SO₂R²). Sequential coupling with preferential activation of the S−SO₂ bond (37.6 kcal/mol) and controllable activation of the S−O bond (54.8 kcal/mol) in the presence of the S−S bond (62.0 kcal/mol) enabled successive reactions at each end of the S−S motif to afford unsymmetrical disulfides and trisulfides, even for the cross-linkage of natural products, pharmaceuticals, peptides, and a protein (bovine serum albumin).