Curcubit[8]uril-modulated asymmetric electroreductive hydrodimerization of coumarins with supramolecular encapsulation

Abstract

The development of electrocatalytic methods for stereoselective reductive functionalization remains a challenge in organic synthesis. Herein, a novel strategy of supramolecule-modulated electrocatalytic stereoselectivity within the macrocyclic cavity is developed using a hybrid electrode prepared from the layer-by-layer assembly of Cu nanoparticles (CuNPs) and curcubit[8]uril (Q[8]). The hydrodimers with good yields of 71%-83% and superior stereoselectivity of up to 96% were afforded. The results of theoretical calculation and control experiments demonstrate that the hydrophobic cavity of Q[8] provides a microenvironment to accommodate two coumarin molecules via host–guest interactions. Q[8] plays a crucial role in modulating product stereoselectivity by controlling the assembly direction of coumarin toward “Head to Head” mode. The designed CuNPs-Q[8] electrode is remarkably stable, which can be reused five times at least without obvious loss of electrocatalytic activity.