Hypervalent Iodine Catalyzed Cascade C–H Functionalization: An Atom-Economical Strategy to Access Diverse 2-Substituted Benzothiazoles

Abstract

A metal-free, 4,5-difluoro-2-iodobenzoic acid-catalyzed C–H functionalization strategy is developed for the synthesis of 2-(hetero)aryl benzothiazoles from aryl isothiocyanates and unfunctionalized arenes/thiophenes/furans at room temperature. The procedure entails a one-pot, cascade carbon–carbon and carbon–sulfur bond formation facilitated by triflic acid, which serves as both a Bronsted acid and a ligand source at the in situ generated I(III) centre. 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.