Ligand‐Free Palladium(II)‐Catalyzed ortho‐C–H Chalcogenations of N‐Arylsulfonamide via Weak Coordination

Abstract

The first palladium(II)‐catalyzed direct ortho‐C(sp2)–H chalcogenations of N‐arylsulfonamide via weak coordination have been achieved, affording the corresponding mono‐chalocgenated products in good to excellent yields. This strategy features ligand/additive‐free conditions, broad substrate scope with excellent functional group tolerance and a high position selectivity.

Chelation-assisted transition metal-catalysed C–H chalcogenylations

“…of Cu(OAc) 2 in toluene at 125 °C proved to be optimal for this transformation. 114 The reaction tolerated a wide range of valuable electrophilic functional groups in both the arylsulfonamide and disulfide moieties, and delivered selectively mono-chalcogenated products in good yields with excellent chemo-and positional-selectivities, thus providing a novel and stepeconomical access to diversely selenylated and thiolated sulfonamides. Further mechanistic studies also revealed a palladium(II)/palladium(IV) process, likely initiated by the coordination of the palladium(II) catalyst with the weakly coordinating O-atom of the sulfonamide, followed by ortho-C-H activation to furnish six-membered palladacycle intermediate A.…”

Recent developments in palladium-catalyzed C–S bond formation

“…Recently, Ma and co-workers have disclosed the first ligandfree palladium-catalyzed ortho-C-H chalcogenation reactions of sulfonamides (23) via weak coordination (Scheme 8). 32 The limitations and scope of the sulfonamide substrates bearing diverse substituents at sulfonyl moiety were then comprehensively investigated. The N-alkylsulfonyl-and N-arylsulfonyl-substituted substrates were good candidates in this chalcogenation reaction.…”

Palladium‐Catalyzed Distal C−H Selenylation of 2‐Aryl Acetamides with Diselenides and Selenyl Chlorides

“…[8] Our group then disclosed the selective ortho-thiolation and selenylation of N-arylsulfonamides with disulfides and diselenides via weak coordination. [9] Nishihara and coworkers developed a palladium-catalyzed periselective CÀ H chalcogenation of naphthylamines with the assistance of picolinamide bidentate directing groups. [10] Inspired by this work, more recently, Xie's group further achieved the γ-C(sp 3 )À H chalcogenation of alkylamines with diaryl disulfides and diselenide in good yield (Scheme 1b).…”

“…Subsequently, Law, Wong and Anbarasan further extended the substrate scope with different chalcogenide reagents under the palladium catalysis (Scheme 1a) [8] . Our group then disclosed the selective ortho ‐thiolation and selenylation of N ‐arylsulfonamides with disulfides and diselenides via weak coordination [9] . Nishihara and coworkers developed a palladium‐catalyzed peri ‐selective C−H chalcogenation of naphthylamines with the assistance of picolinamide bidentate directing groups [10] .…”