Assembly of (Hetero)aryl Thioethers via Simple Nucleophilic Aromatic Substitution and Cu-Catalyzed Coupling Reaction with (Hetero)aryl Chlorides and Bromides under Mild Conditions

The requirement of higher reaction temperatures for an SNAr reaction between thiols and less reactive electron-poor aryl halides described in earlier reports has triggered intensive studies on the development of metal- and photo-catalyzed methods to promote this transformation. We report here that an SNAr reaction of thiols with most electron-poor aryl halides takes place at RT–60 °C under the action of K2CO3 and DMAc. Both the bases and the solvents play an essential role in such mild conditions. For (hetero)aryl halides that are unreactive toward an SNAr reaction, two oxalic diamide ligands that are more powerful were identified to make their Cu-catalyzed coupling reactions proceed with low catalytic loadings. A combination of these two methods offers a very attractive approach for preparing (hetero)aryl thioethers.