Mechanochemical Nickel‐Catalyzed Carbon‐Sulfur Bond Formation between Aryl Iodides and Aromatic Sulfur Surrogates

Abstract

The formation of aromatic thioethers from C‐S coupling is of great importance in synthetic chemistry. Traditional solution strategies through transition‐metal catalysis generally require bulk solution, heat, and longer reaction time. Herein, a mechano‐promoted sulfenylation of aryl iodides with nickel catalysis is described. The active aromatic sulfide agents are in‐situ generated from aromatic thiol or disulfide and subsequently adapted in the nickel catalytic cycle, with a tolerance of broad substituted groups under optimized conditions. In addition to the gram‐scale synthesis that reveals the application potential of the method, the radical trap‐ping and competitive experiments are also conducted for the mechanistic study, thus proposing the plausible mechanism rationally. Furthermore, the proposed methodology is certificated as being versatile and following the green principles with ideal calculated values of green chemistry matrix and the comparison with other approaches for C‐S bond formation.

A nickel-catalyzed carbon–sulfur cross-coupling reaction with disulfides enabled by mechanochemistry

“…Our investigation began following the reaction conditions established for the thiolation of aryl iodides. 16 According to the reported Ni-catalyzed halogen exchange process, NaI was initially employed as an additive for potential halogen exchange. Utilizing NiCl 2 ·6H 2 O, 2,2′-bipyridine (Bpy), and N , N -dimethyl formamide (DMF) as the catalyst, ligand, and grinding auxiliary, respectively, we successfully synthesized the desired aromatic thiol product ( 3a ) through the cross-coupling between bromobenzene (PhBr, 1a ) and phenyl disulfide ( 2a ) at a 3 : 1 ratio (the yield was calculated using disulfide as the standard substrate with 1 mmol as 1 equivalent).…”

Mechanochemical Cascade Synthesis of Zinc Complexes for Catalytic C–S Coupling in One-Pot

“…In addition, reduced Schiff base ligands exhibit greater flexibility than pristine ones, affording them increased coordination versatility. Given that zinc complexes are heterogeneous, nontoxic, noncorrosive, cost-effective, stable, and environmentally benign catalysts, − as well as our continuing interest in mechanochemistry, − the Zn(II) complexes bearing reduced Schiff base ligands, N , N′ - diphenylethylenediamine (L 1 ) , were initially synthesized by grinding. Subsequently, an appropriate amount of the reactant substrate was employed in a mechanochemical C–S bond cross-coupling within the same vessel, thereby achieving a continuous mechanochemical process from synthesis to catalysis in a one-pot, two-step approach and avoiding the catalyst purification procedures (Figure B).…”