•A novel and efficient method for synthesis of 2-sulfenylindoles.•Copper-catalyzed the formation of C–S bond.•Extend to synthesize benzothiophene fused indoles.A novel and efficient method for synthesis of 2-sulfenylindole via copper-catalyzed coupling reaction of indoline-2-thiones with aryl iodides has been developed. A series of N-substituted and N-free 2-sulfenylindole were obtained in high yields. Furthermore, the method was employed to synthesis of benzothieno[2,3-b]indoles from indoline-2-thiones with 1,2-diiodobenzene in the presence of CuI and Pd(OAc)2 as catalysts.

The sulfuration reaction of 2-(2-iodobenzoyl) substituted, or 2-(2-iodobenzyl) substituted 1,2,3,4-tetrahydroisoquinolines with potassium sulfide proceeded in the presence of copper catalysts to give tetrahydroisoquinoline-fused 1,3-benzothiazine scaffolds in moderate to appropriate yields. This protocol provided an efficient and simple strategy to construct the corresponding benzothiazine derivatives via formation of C(sp3)–S bond and C(sp2)–S bond, which the C–S bonds formed via different routes in this reaction (traditional cross-coupling reaction via the cleavage of C–I bond and oxidative cross-coupling reaction via C(sp3)–H bond functionalization).

A novel, atom economic, and environmentally friendly method for the synthesis of 2-substituted benzothiazoles and 2-substituted naphtho[2,1-d]thiazoles from N-substituted arylamines and elemental sulfur has been developed under metal-free conditions. The reaction underwent the process of double C–S bond formation through C–H bond functionalization.

An efficient and practical procedure for the synthesis of 2-benzyl- and 2-benzylidene-substituted benzo[b]thiazinones from easily available 2-iodophenylcinnamamides and potassium sulfide has been developed. In the presence of DBU, the reaction proceeds via electrophilic addition, followed by dehydrogenation and reduction to give 2-benzyl benzo[b]thiazinones. Furthermore, 2-benzylidenebenzo[b]thiazinones were obtained in moderate to good yields without the addition of DBU.

An efficient palladium-catalyzed strategy for the synthesis of dibenzo[a,c]carbazole derivatives has been developed. In the presence of Pd(OAc)2, 2-(2-halophenyl)-indoles and iodobenzenes proceeded smoothly to obtain the corresponding dibenzo[a,c]carbazoles in moderate to good yields. This methodology constructs two new C–C bonds via a palladium-catalyzed dual C–H functionalization.

A new and straightforward approach to synthesize benzo[b]thiophene-fused imidazopyridines has been developed by tandem cross-coupling reaction of K2S with 2-(2-bromophenyl)imidazo[1,2-a]pyridines, and K2S as sulfur source constructed double C–S bonds via the cleavage of the C–H bond and the C–X bond. In addition, the optical properties of a library of benzo[b]thiophene-fused imidazopyridines were for the first time fully characterized. Moreover, this synthetic strategy could be applied in the preparation of benzo[b]thiophene-fused indoles.

An efficient copper catalyzed strategy for the synthesis of a variety of benzothiazolethione derivatives has been developed. In the presence of CuCl, the three-component reaction of o-iodoanilines and K2S with p-toluenesulfonylmethyl isocyanide proceeded smoothly to obtain the corresponding benzothiazolethiones in good to excellent isolated yields. Notably, isocyanide functioned as a carbon source and K2S functioned as a sulfur source in this reaction.

A new, highly efficient procedure for the synthesis of benzothiazoles from easily available N-benzyl-2-iodoaniline and potassium sulfide has been developed. The results show copper-catalyzed double C–S bond formation via a traditional cross-coupling reaction and an oxidative cross-coupling reaction.

A novel and efficient procedure for the synthesis of N-substituted phenanthridinones via palladium-catalyzed annulation of benzynes with N-substituted-N-(2-halophenyl)formamides has been developed. This methodology constructs two new C–C bonds via an arylation/annulation process, and provides the desired products in good yields.

A copper catalyzed three-component reaction was developed for the synthesis of benzothiazolones. In the presence of CuBr2, the reaction of o-iodoanilines and K2S with DMF proceeded smoothly and generated the corresponding benzothiazolones with good isolated yields. DMF functioned both as the carbon monoxide source and as the reaction medium in this reaction.

A metal-free decarboxylative amination of 4-(ethoxycarbonyl)-2,3-allenols by TsNCO via base-induced aza-Michael addition/elimination has been developed. A variety of substituted N-tosyl 1,3-dien-2-yl amines were obtained in good yields and excellent regio- and stereoselectivity. Moreover, this transformation could be applied in preparation of 2-amino-trienes.

A novel and efficient procedure for the synthesis of N-substituted phenanthridinones via palladium-catalyzed annulation of benzynes with N-substituted-N-(2-halophenyl)formamides has been developed. This methodology constructs two new C–C bonds via an arylation/annulation process, and provides the desired products in good yields.

A simple and practically useful synthetic method for the synthesis of a variety of 2-aminobenzothiazoles was developed. This methodology could construct one C–N bond and two C–S bonds in a step reaction and provide the desired products in good to perfect yields.