GW-610

A metal‐free 4,5‐difluoro‐2‐iodobenzoic acid catalyzed C−H functionalization strategy has been developed for the synthesis of 2‐(hetero)aryl benzothiazoles from aryl isothiocyanates and unfunctionalized arenes/thiophenes/furans at room temperature. The procedure entails one‐pot cascade carbon−carbon and carbon−sulfur bond formation facilitated by triflic acid, which serves as both a Brønsted acid and a ligand source at the in situ generated I(III) center. This process is atom‐economical and offers benefits over existing protocols for synthesizing benzothiazoles in terms of ease of use, eco‐friendliness, and not requiring the typical use of aryl aldehyde/carboxylic acid precursors. Mechanistic studies were carried out, and the synthetic utility of the protocol was demonstrated for the synthesis of the benzothiazole‐based antitumor drug GW‐610.

We report herein a direct synthetic route for the preparation of 2-arylbenzothiazoles using aryl isothiocyanates and electron-rich arenes. The synthetic route involves triflic acid promoted addition of the arenes to aryl isothiocyanates followed by FeCl₃-catalyzed C-S bond formation via C-H functionalization. The approach provides the advantage of synthesis of benzothiazoles without the conventional use of aryl aldehyde/carboxylic acid precursors employing the less expensive iron(III) catalyst.