Visible light-induced 3-sulfenylation of N-methylindoles with arylsulfonyl chlorides

Abstract

The synthesis of 1-methyl-3-(arylthio)-1H-indoles has been achieved by the photoredox reaction of N-methylindoles with readily available arylsulfonyl chlorides in moderate yields.

Metal- and base-free syntheses of aryl/alkylthioindoles by the iodine-induced reductive coupling of aryl/alkyl sulfonyl chlorides with indoles

“…Thus far sulfenylating agents for the thiolation of C(sp 2 )-H bonds have included disulfides, 3 sodium sulfinates, 4 sulfenyl halides, 5 N-thioarylphthalimides, 6 and sulfonyl hydrazides, 7 catalyzed by metal-free salts such as iodine or metal salts (Scheme 1). 10 Scheme 1. The thiolation can be achieved in principle, by means of aryl-/ alkyl-/ heteroarylsulfonyl chlorides as a sulphur source.…”

Copper‐Catalyzed Regioselective Sulfenylation of Indoles with Arylsulfonyl Chlorides

“…[15] Although there are af ew examples of sulfenylation of indoles by using arylsulfonylc hlorides, these methods still suffer from low yields and narrow substrate scope. [16,17] Herein, we describe ac opper-catalyzed, convenient, and highly efficient protocolf or the sulfenylation of indoles by using arylsulfonyl chlorides as sulfenylation reagents (Scheme 1, route b).The initial study on the sulfenylating reaction of indole was conducted by using indole (1a)a nd p-toluenesulfonyl chloride (2a)i nt he presence of 0.2 equivalents of CuCl,2 .0 equivalents of Na 2 CO 3 and 3.0 equivalents of PPh 3 under an itrogen atmosphere (Table 1). Preliminary experiments with various solvents were screened for their influence on the reactionb ehavior (entries 1-6).…”

“…As shown in Ta ble 3, various electron-withdrawing substituents such as F, Cl, I, and CN groups (entries 1-4) ande lectron-donating substituents Me and tBu (entries6 and7 )w ere well tolerated in the process. The reactiono ft he former gave as lightly lower yield than the latter.Previously arylsulfonylc hlorides have been used as agents for the sulfenylation of indoles induced by av isible light; [16] however,t he protocol was mainly effective for N-protected indoles,g iving the corresponding products in low to moderate yields.A lthough the procedure was successfully applied to an indole containing af ree NÀH, the required loading of relatively expensive indole was up to four equivalents. In another communication by the Youg roup, [17] although the reaction worked without ac opperc atalyst, the process suffered from not only low yields but also required ah igh temperature.…”

“…[15] Although there are af ew examples of sulfenylation of indoles by using arylsulfonylc hlorides, these methods still suffer from low yields and narrow substrate scope. [16,17] Herein, we describe ac opper-catalyzed, convenient, and highly efficient protocolf or the sulfenylation of indoles by using arylsulfonyl chlorides as sulfenylation reagents (Scheme 1, route b).…”

Sulfide and Sulfonyl Chloride as Sulfonylating Precursors for the Synthesis of Sulfone‐Containing Isoquinolinonediones

“…However, to the best of our knowledge, visible light‐induced reactions, in which widely used sulfonyl chlorides participate, are quite rare for C−S or C−C bond formation . For instance, in 2012, the Zheng group discovered a visible light‐induced 3‐sulfenylation of N‐methylindoles with arylsulfonyl chlorides . In 2013, Li et al .…”