Electrochemical Radical Addition-Initiated Ring-Opening/Functionalization of 2-Alkylidenecyclobutanols toward γ,δ-Unsaturated Ketone Synthesis

γ,δ-Unsaturated carbonyl compounds bearing halogen/sulfonyl groups are valuable in medicinal chemistry, but their efficient synthesis remains a considerable challenge. Here, we report an electrochemical radical addition-initiated ring-opening/functionalization of 2-alkylidenecyclobutanols with readily available halogen radical (nBu4NCl, nBu4NBr) and sulfonyl radical (TsNHNH2) sources, enabling the efficient synthesis of γ-halogenated and γ-sulfonylated γ,δ-unsaturated carbonyl compounds. It features broad substrate scope, operational simplicity, practical utility, and is free of transition metals and stoichiometric oxidants. Based on the mechanistic studies, distinct reaction pathways are presented that account for observed reactivity and stereoselectivity differences.