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

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.