Visible‐Light‐Accelerated C−H Sulfinylation of Heteroarenes

Abstract

Heteroaromatic sulfoxides are a frequent structural motif in natural products, drugs, catalysts, and materials. We report a metal-free visible-light-accelerated synthesis of heteroaromatic sulfoxides from sulfinamides and peroxodisulfate. The reaction proceeds at room temperature with blue-light irradiation and allows the C-H sulfinylation of electron-rich heteroarenes, such as pyrroles and indoles. An electrophilic aromatic substitution mechanism is proposed based on the substrate scope, substitution selectivity, and competition experiments with different nucleophiles.

Photocatalytic Oxidation of Sulfinates to Vinyl Sulfones with Cyanamide‐Functionalised Carbon Nitride

“…Under oxygen, a yield of 30 % was obtained (Table , Entry 10). Hydrogen peroxide, sodium persulfate and ammonium persulfate were found not to be suitable oxidants for this reaction and gave the product in only small yields (Table , Entries 11–13). The photocatalytic oxidation of sulfinates also depends strongly on the solvent , .…”

Visible‐Light Photocatalysis: Does It Make a Difference in Organic Synthesis?

“…The visible‐light accelerated C−H sulfinylation of heteroarenes starts from bench‐stable, easy to handle, and commercially available sulfinamides 132 and electron‐rich aromatic compounds 133 , with persulfate used as the stoichiometric oxidant (Scheme a) . The reaction gave moderate to good yields with N ‐butylarylsulfonamides bearing electron‐donating or ‐withdrawing substituents, while the presence of electron‐donating substituents in the aromatic or heteroaromatic partner afforded excellent results.…”

Ultrafast Observation of a Photoredox Reaction Mechanism: Photoinitiation in Organocatalyzed Atom-Transfer Radical Polymerization

“…[15][16][17][18][19][20][21][22] To circumvent the problems of natural scarcity and toxicity associated with the transition metals in these photoredox systems, [23][24] researchers are replacing metal-based catalysts with highly conjugated organocatalysts; [25][26][27] applications, and associated mechanistic studies, include oxidation using molecular oxygen, [28][29][30] cross-coupling, 31 cyanation, 32 addition to alkenes, 33 trifluoromethylation, 34 hydroxylation, 35 N-formylation, 36 and sulfinylation. 37 In addition to these synthetic uses, selected organic PCs such as perylene, phenothiazine, dihydrophenazine and phenoxazine derivatives have recently been applied in the development of organocatalysed atom-transfer radical polymerization (O-ATRP). [38][39][40][41] Initiation in O-ATRP depends upon the reductive dehalogenation of an alkyl halide initiator via an outer-sphere electron transfer from a photoexcited organocatalyst; this process forms a reactive radical species, which instigates the propagation stage of polymerization.…”