Visible light-induced C–H sulfenylation using sulfinic acids

Abstract

The direct use of sulfinic acids as an odorless sulfur source to construct hetroaryl sulfides through a photoredox process has been realized at room temperature for the first time.

Unconventional Reactivity with DABCO‐Bis(sulfur dioxide): C–H Bond Sulfenylation of Imidazopyridines

“…3‐[(2‐Chlorophenyl)thio]‐2‐phenylimidazo[1,2‐ a ]pyridine (4j): Yellow solid (97 mg, 56 %); 1 H NMR (300 MHz, CDCl 3 ): δ = 8.24 (d, J = 6.8 Hz, 1H), 8.16 (d, J = 7.8 Hz, 2H), 7.79 (d, J = 9.0 Hz, 1H), 7.49–7.32 (m, 5H), 7.08 (td, J = 7.8, 1.5 Hz, 1H), 7.01–6.88 (m, 2H), 6.40 (dd, J = 7.9, 1.4 Hz, 1H); 13 C NMR (75 MHz, CDCl 3 ): δ = 152.3, 147.6, 134.4, 133.2, 131.2, 130.2, 128.9, 128.6, 128.41, 127.7, 127.1, 127.0, 125.6, 124.6, 117.9, 113.4, 104.7; MS (ES + ): m/z (%) = 336.9 (100) [M + H] + …”

Recent Advances in Radical C−H Bond Functionalization of Imidazoheterocycles

“…[77] A wide range of ethers/alkanes 13 reacted with substituted imidazo [1,2-a] Wang and co-workers investigated a visible lightinduced, Eosin B-catalyzed sulfenylation of imidazo-[1,2-a]pyridines 1 using arylsulfinic acids 80 in DCE at room temperature (Scheme 51). [78] Imidazo[1,2-a]pyridines 1 and benzo [d]imidazo [2,1-b]thiazoles 2 reacted smoothly with diverse arylsulifinic acids 80 and produced respective products 81 in 62-89% yields. Arylsulfinic acids with EDGs provided relatively better yields as compared to those with EWGs.…”

“…Wang and co‐workers investigated a visible light‐induced, Eosin B‐catalyzed sulfenylation of imidazo[1,2‐ a ]pyridines 1 using arylsulfinic acids 80 in DCE at room temperature (Scheme ) . Imidazo[1,2‐ a ]pyridines 1 and benzo[ d ]imidazo[2,1‐ b ]thiazoles 2 reacted smoothly with diverse arylsulifinic acids 80 and produced respective products 81 in 62–89% yields.…”

A Facile Synthesis of 3‐(Arylthio)imidazo[1,2‐a]pyridin‐2(3H)‐ones from 2‐Aminopyridinium Bromides and Sodium Arenesulfinates

“…[ 2 ] Among them, the development of efficient synthetic methods for sulfenylation has attracted increasing attention of chemists due to considerable therapeutic value of sulfenylated heteroarenes against a variety of diseases. [ 3 ] Several reagents such as thiols, [ 4 ] disulfides, [ 5 ] sulfonyl hydrazides, [ 6 ] thiosulfate salts, [ 7 ] sulfonyl halides, [ 8 ] sulfinates, [ 9 ] sulfinic acid, [ 10 ] dithiocarbamates, [ 11 ] sulfenyl chloride, [ 12 ] S‐phenyl benzenesulfonothioate, [ 13 ] sodium sulfide, [ 14 ] thiocyanate, [ 15 ] DABSO [DABCO · (SO 2 ) 2 ] [ 16 ] and elemental sulfur [ 17 ] have been utilized for sulfenylation of Imidazo‐heterocycles under transition metal catalyzed and metal‐free conditions. [ 18 ] Among different sulfur sources, sodium benzenesulfinate is a stable and odorless sulfur source.…”