Electroreductive hydrodimerization of allylbenzenes and vinylarenes enables the diversified synthesis of 1,4-diarylbutanes

Abstract

A site-selective hydrodimerization of alkenes has emerged as a powerful strategy for C–C bond formation from readily available feedstocks. While current reductive coupling methods typically rely on activated electron-deficient alkenes, the coupling of neutral or electron-rich alkenes, particularly challenging internal alkenes, remains underdeveloped. Herein, we report an electrochemical reductive coupling protocol that enables selective homo- and cross-dimerization of unactivated allylbenzenes and vinylarenes to construct diverse 1,4-diarylbutanes in good yields. The transformation demonstrates remarkable substrate generality, successfully accommodating conjugated and non-conjugated alkenes with varying electronic properties and substitution patterns. And the protocol tolerates complex substrates containing fused ring, heterocycle and bioactive motifs. Mechanistic investigations reveal that initial electrochemical isomerization of allylbenzene generates a vinylarene intermediate, which undergoes cathodic reduction to form an alkene radical anion. Subsequent protonation produces a carbon-centered radical that participates in intermolecular addition with a second alkene, ultimately yielding the product through proton transfer or hydrogen atom transfer. This operationally simple and mild method establishes a versatile platform for the efficient assembly of biorelevant 1,4-diarylbutane architectures.