Brönsted acid-surfactant-combined ionic liquid catalyzed green synthesis of 2-alkyl and 2-arylbenzothiazoles in water: Reusable catalyst and metal-free conditions.

An efficient Brönsted acid-surfactant-combined ionic liquid (BASILs) catalyzed cyclocondensation of 2-aminothiophenol with a variety of aldehydes in water is described. This protocol was successfully conducted under metal-free conditions at ambient temperature and produced 2-alkyl and 2-arylbenzothiazole products in high to excellent yields (up to 98%). The catalyst was reusable at least four times without significant loss of activity. [Display omitted] • Brönsted acid-surfactant-combined ionic liquid was used as reusable catalyst for the green synthesis of 2-alkyl and 2-arylbenzothiazoles. • The novel method was successfully achieved under water media at ambient temperature. • High and excellent yields of the desired products were obtained from a variety of aliphatic, aromatic and heteroaromatic aldehyde substrates. An efficient Brönsted acid-surfactant-combined ionic liquid (BASILs) catalyzed cyclocondensation of 2-aminothiophenol with a variety of aldehydes in water is described. This protocol was successfully conducted under metal-free conditions at ambient temperature and produced 2-alkyl and 2-arylbenzothiazole products in high to excellent yields (up to 98%). The catalyst was reusable at least four times without significant loss of activity. [ABSTRACT FROM AUTHOR]