Electrochemical 1,2-Diarylation of Alkenes Enabled by Direct Dual C-H Functionalizations of Electron-Rich Aromatic Hydrocarbons

A cobalt-promoted electrochemical 1,2-diarylation of alkenes with electron-rich aromatic hydrocarbons via direct dual C-H functionalizations is described, which employs a radical relay strategy to produce polyaryl-functionalized alkanes. Simply by using graphite rod cathode instead of platinum plate cathode, chemoselectivity of this radical relay strategy is shifted to the dehydrogenative [2+2+2] cycloaddition via 1,2-diarylation, annulation, and dehydrogenation cascades leading to complex 11,12-dihydroindolo[2,3-a]carbazoles. Mechanistical studies indicate that a key step for the radical relay processes is transformations of the aromatic hydrocarbons to the aryl sp(2)-hybridized carbon-centered radicals via deprotonation of the corresponding aryl radical cation intermediates with bases.

Automated summary

This study describes a cobalt-promoted electrochemical method for 1,2-diarylation of alkenes with electron-rich aromatic hydrocarbons, producing polyaryl-functionalized alkanes. Utilizing a radical relay strategy, the chemoselectivity is shifted to dehydrogenative [2+2+2] cycloaddition via 1,2-diarylation by using a graphite rod cathode, resulting in the formation of complex 11,12-dihydroindolo[2,3-a]carbazoles.