Dearomative syn-1,4-hydroalkylation and C(sp²)-H alkylation of arenes controlled by chemoselective electrolysis

Dearomative functionalization of arenes represents a powerful synthetic strategy for the rapid assembly of complex chemical architectures. A significant challenge in this process is overcoming the inherent aromaticity of arenes. Here, leveraging the potential of organic electrolysis, we show the development of a dearomative syn-1,4-hydroalkylation reaction targeting electron-deficient arenes and heteroarenes. This electrochemical approach, conducted under mild, operationally straightforward and scalable conditions, facilitates the synthesis of alkylated syn-1,4-cyclohexadienes with high chemoselectivity, regioselectivity and stereoselectivity. In addition, this alkylation protocol is controllable and switchable. By employing a niobium plate as the anode and nBu₄NBr as the supporting electrolyte, our method enables the para-selective C(sp²)-H alkylation of (hetero)arenes via electrolysis. Both reactions exhibit broad substrate scope and demonstrate excellent compatibility with various electron-deficient arenes and alkyl bromides. Furthermore, preliminary mechanistic studies and density functional theory calculations have been performed to elucidate the reaction mechanism and to rationalize the observed chemoselectivity, regioselectivity and stereoselectivity.