Reusable proline-based ionic liquid catalyst for the simple synthesis of 2-arylbenzothiazoles in a biomass medium

A simple, efficient, and eco-friendly aerobic procedure for synthesis of 2-substituted benzothiazoles catalyzed by facile prepared [N 2222 ][Pro] in a biomass medium (ethyl lactate) has been developed. The reactions afford the target 2-arylbenzothiazoles in good to excellent yields (>80 %) under air condition and was observed without use of chromatography. In addition, this proline-based ionic liquid catalyst can be easily recycled six times without loss of catalytic activity in gram scale synthesis.