Electrochemical cascade access to hetero[8]circulenes as potent organophotocatalysts for diverse C–X bond formations
The chemistry of hetero[8]circulenes has been limited to three types due to challenges in making unsymmetrical variants. We introduce an electrochemical approach to a hetero[8]circulene bearing five hexagons and three pentagons. Exploiting electrochemistry’s selectivity, differential oxidation enables selective inter- and intramolecular couplings, giving dioxaza[8]circulenes in up to 83% yield with good functional-group tolerance. A one-pot protocol from commercially available substrates forges six new bonds. Structural, optical, and electrochemical characterizations (X-ray crystallography, spectrophotometric analysis) with DFT calculations elucidate properties. Motivated by these features, we demonstrate transition-metal-free organophotocatalysis under 365-nm LED irradiation, effecting diverse C–X (X = C, B, P) bond formations in up to 97% yield.