One-pot three-component synthesis of 1-amidoalkyl naphthols and polyhydroquinolines using a deep eutectic solvent: a green method and mechanistic insight

Abstract

The multicomponent synthesis of 1-amidoalkyl naphthols and polyhydroquinolines has been developed as an atom-economic procedure catalyzed by a deep eutectic solvent ([CholineCl][ZnCl₂]₃). The reactions proceed smoothly at low temperatures for a short reaction time without the use of toxic and volatile organic solvents. Deep eutectic solvents are capable of not only allowing multicomponent reactions to proceed in high yield but also controlling the selectivity towards desired products. The mechanistic insight was examined by HRMS (ESI) to propose a plausible mechanism. Furthermore, [CholineCl][ZnCl₂]₃ can be recycled in up to three consecutive cycles with an insignificant loss of catalytic activity under the optimized conditions.