Copper-doped carbon nitride as a practical heterogeneous metallaphotocatalyst for aerobic oxidative cross-coupling of tertiary amines with terminal alkynes

Abstract

Heterogeneous metallaphotocatalytic chemical transformations with a recyclable catalyst are highly desirable and challenging for sustainable organic synthesis. Herein, we constructed a Cu-doped carbon nitride (CN–Cu) material that functions as a Cu–photo dual catalytic system. The heterogeneous CN–Cu catalyst can be applied to direct α-alkynylation of tertiary amines using air as an oxidant, allowing for the construction of diverse valuable propargylamines in good to excellent yields. The endogenous proximity and synergistic effect between Cu and the photocatalytic center in CN–Cu significantly enhance the Cu–photo dual catalytic activity, thus further improving the reaction efficiency and selectivity. Remarkably, this heterogeneous catalyst exhibits high chemical stability and can be recycled at least five times without loss of activity.