Green carbon disulfide surrogate: Via a combination of potassium sulfide and chloroform for benzothiazine-thione and benzothiazole-thione construction

An efficient and green carbon disulfide surrogate via facile combination of potassium sulfide and chloroform has been developed. A variety of benzothiazine-thiones and benzothiazole-thiones were straightforwardly established along with the formation of five new chemical bonds in one pot from readily available starting materials, in which the widely used 2-mercaptobenzothiazole (MBT) was synthesized through this method in gram scale. Dichlorocarbene was demonstrated to be a carbon source intermediate from chloroform on the basis of control experimental studies. Meanwhile, potassium sulfide, as a trisulfur radical anion (S₃ ^-) source, was confirmed through UV-visible spectroscopy and an EPR study.