Electrooxidative Allene Annulations by Mild Cobalt-Catalyzed C–H Activation

Abstract

Versatile cobalt catalysis enabled electrochemical C–H activation with allenes. Thus, allene annulations were accomplished in terms of C–H/N–H functionalizations with excellent levels of chemoselectivity, site selectivity, and regioselectivity under exceedingly mild conditions. Detailed mechanistic studies were conducted, including reactions with isotopically labeled compounds, kinetic investigations, and in-operando infrared spectroscopic studies. Further, computational studies were supportive of a non-rate-determining C–H cleavage and gave key insights into the regioselectivity of the allene annulation. The practical utility of the user-friendly approach was furthermore highlighted by gram-scale electrocatalysis.

Cobalt‐Catalyzed Direct C(sp2)–H Alkylation with Unactivated Alkenes

“…Despite the considerable progress in C–H bond functionalization achieved by precious transition metals, there is a continuous interest in developing direct functionalization using abundant 3d late‐transition metals. Owing to the pioneering studies by Kanai, Glorius, and Ackermann, cobalt has emerged as an excellent catalyst for various useful C–H bond functionalizations. Cp*Co III ‐catalyzed linear‐selective C–H alkylation with alkenes has also been developed and demonstrates high regioselectivity and efficiency.…”

Recent Advances in Electrochemical Oxidative Cross‐Coupling of Alkenes with H2 Evolution

“…Same year, Ackermann group disclosed electrochemical method to the cyclization of allenes (Scheme ) . This transformation could be carried out using a simple undivided cell under mild conditions without metal precipitation from the cathode.…”

“…Same year, Ackermann group disclosed electrochemical method to the cyclization of allenes (Scheme 35). [43] This transformation could be carried out using a simple undivided cell under mild conditions without metal precipitation from the cathode. DFT calculation experiments showed that allene insertion was the rate-determining step and was the reason of excellent regioselectivity.…”

Reaching Green: Heterocycle Synthesis by Transition Metal‐Catalyzed C−H Functionalization in Sustainable Medium

“…In as imilar manner,a llenes also participated in the Co-catalyzed annulation reaction with amides to give isoquinolones via electrochemicaloxidation in methanolsolvent. [57] 2.9.4. Dihydroisoquinolones…”