was subjected to the standard reaction conditions using chemical oxidant without 2a, and notably, the 1a-d2 was recovered without any loss of deuterium, indicating that C-H activation in our method is irreversible (Figure ). Next, kinetic isotope effect (KIE) experiments were conducted, and the KIE value was determined to be 3.4, indicating that the C-H bond cleavage might be the rate-determining step (Figure ). Furthermore, the nonlinear effects of enantioselective C-H alkynylation was studied under the condition of electrolysis. A plot of ee3aa as a function of eeL1 was found to be linear, suggesting the active catalytic species might be a monomeric copper-catalyst with a single bound BINOL ligand L1 (Figure ). Figure