K₂S as Sulfur Source and DMSO as Carbon Source for the Synthesis of 2-Unsubstituted Benzothiazoles

Abstract

We describe a three-component reaction of o-iodoanilines with K2S and DMSO that provides 2-unsubstituted benzothiazoles in moderate to good isolated yields with good functional group tolerance. Electron-rich aromatic amines and o-phenylenediamines instead of o-iodoanilines provided 2-unsubstituted benzothiazoles and 2-unsubstituted benzimidazoles with and without K2S under similar conditions. Notably, DMSO plays three vital roles: carbon source, solvent, and oxidant.

Hydrogenative coupling of nitriles with diamines to benzimidazoles using lignin-derived Rh2P catalyst

“…The above results thus demonstrated that the developed Rh 2 P/LC 400 catalyst enables highly selective and efficient synthesis of various 2-alkylbenzimidazoles by the hydrogenative coupling of the corresponding nitriles and aromatic 1,2-diamines ( Figures S10–S20 ). In addition to 2-alkylbenzimidazoles, 2-unsubstituted benzimidazoles were recently reported in 35–86% yields with a wide tolerance of functional groups by a direct coupling of 1 with dimethyl sulfoxide (DMSO), in which DMSO functions as methyne source, oxidant, and solvent ( Zhu et al., 2020 ). These two synthetic methods thus highlight a powerful and important extension to benzimidazoles in a sustainable and green way.…”

Copper(I) Complex of Dihydro Bis(2‐Mercapto Benzimidazolyl) Borate as an Efficient Homogeneous Catalyst for the Synthesis of 2H‐Indazoles and 5‐Substituted 1H‐Tetrazoles

“…[31] Based on these facts, Cu-based complexes have been applied for a widespread variety of organic transformations such as cross-coupling, click chemistry, tandem and multicomponent reactions, reduction, and oxidation reactions, CÀ H functionalization, borylation, and oxidative coupling. [32][33][34][35][36][37][38][39][40][41] In recent years, literature reports in regards to enabling certain regioselective synthetic paths towards 2H-indazoles have appeared. [1,[42][43][44][45][46][47][48][49][50][51][52][53][54] A common way for the formation of highly regioselective 2H-indazoles is based on the intramolecular coupling of properly pre-functionalized substrates including 2halobenzaldehydes.…”

“…The structural diversity of copper(I) complexes provided a huge potential for the development of catalytic systems with tunable properties [31] . Based on these facts, Cu‐based complexes have been applied for a widespread variety of organic transformations such as cross‐coupling, click chemistry, tandem and multicomponent reactions, reduction, and oxidation reactions, C−H functionalization, borylation, and oxidative coupling [32–41] …”

Synthesis of novel benzimidazoles and benzothiazoles via furan‐2‐carboxaldehydes, o‐phenylenediamines, and 2‐aminothiophenol using Cu(II) Schiff‐base@SiO2 as a nanocatalyst

“…[ 40 ] Cu‐based compounds have been used as catalysts for a wide range of organic transformations such as multicomponent reactions, reduction and oxidation reactions, cross‐coupling, click chemistry, C–H functionalization, and oxidative coupling. [ 41–46 ] Also, there are various reports about metal complexes stabilized on inorganic supports for the preparation of heterocyclic compounds. [ 47–58 ]…”