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-dihydroindolo2,3-acarbazoles. Mechanistical studies indicate that a key step for the radical relay processes is transformations of the aromatic hydrocarbons to the aryl sp2 -hybridized carbon-centered radicals via deprotonation of the corresponding aryl radical cation intermediates with bases.