An economically and environmentally sustainable synthesis of 2-aminobenzothiazoles and 2-aminobenzoxazoles promoted by water

Abstract

Tandem reactions of isothiocyanates (1) with 2-aminothiophenols (2), or isothiocyanates (1) with 2-aminophenols (4), were carried out rapidly and efficiently in water. A significant rate acceleration of the reaction between 1a and 2a in water compared with commonly used volatile organic solvents was observed. Through these reactions, a variety of structurally and pharmaceutically interesting 2-aminobenzothiazoles (3) and 2-aminobenzoxazoles (5) were synthesized in good yields. This novel synthetic approach toward 3 and 5 has advantages such as high efficiency, readily available starting materials, environmentally benign solvent, and highly simple and practical experimental procedures.