Synthesis of Benzothiazoles from 2-Aminobenzenethiols in the Presence of a Reusable Polythiazolium Precatalyst Under Atmospheric CO2

Abstract

First, the functionalization of phenol was done in an aqueous medium. Phenol was halogenated, and followed by an in situ Suzuki cross coupling with benzeneboronic acid. The reaction conditions were mild (low temperature and no use of ligands) with high yields. Next, synthesis of benzothiazoles from 2-aminobenzenethiols and carbon dioxide was carried out using poly(3,4-dimethyl-5-vinylthiazolium) iodide as a precatalyst. The reaction was successfully held under mild conditions (1 atm of CO2 and 60–70 ºC) with broad substrate scope and functional group tolerance. The precatalyst salt was recovered and reused for several times without any loss of activity.

Keywords: Phenol, Water, Suzuki Coupling, Benzothiazole, Poly (NHC), Carbon dioxide