A Cut-and-Sew Strategy with Rongalite: Sulfonylmethylation Relay of Two Distinct Alkenes to Access Lactam-Chromone...

Over the past few decades, radical relay reactions of distinct alkenes have emerged as a pivotal strategy for constructing functional molecules. However, developing functional groups that can link two distinct alkenes simultaneously remains a significant challenge. Herein, we report an efficient rongalite-induced sulfonylmethylation relay reaction of N-allylbromoacetamides with o-hydroxyaryl enaminones using rongalite as the "SO₂" and "C1" sources to access lactam-chromone hybrid alkyl-alkyl sulfones. Notably, this transformation employs a novel "cut-and-sew" strategy, where rongalite is "cut" into sulfur and carbon fragments, which subsequently undergo selective "sew" with two distinct alkenes to access the target product. This sulfonylmethylation relay reaction demonstrates high efficiency, broad substrate tolerance, and excellent scalability and enables the conversion of products into valuable heterocyclic skeletons. Mechanistic studies revealed that this reaction proceeded through a radical pathway, with rongalite serving triple roles: as a super electron donor to initiate the reaction, as both "SO₂" and "C1" sources.