Visible light-driven α-sulfonylation of ketone-derived silyl enol ethers via an electron donor–acceptor complex†

Abstract

The diverse utility of β-ketosulfones in pharmaceuticals and bioactive compounds has generated considerable interest in their synthesis. However, existing synthetic approaches often depend on transition-metal catalysts, which require extensive purification and result in low yields. Herein, we present a cost-effective, metal- and photocatalyst-free, visible light electron donor–acceptor (EDA) complex-mediated sulfonylation of ketone-derived silyl enol ethers with thiosulfonates (acceptor) and DABCO as an electron donor under mild conditions, offering a more efficient and straightforward approach. Our method enables the synthesis of a diverse range of β-ketosulfone derivatives, including biologically active and late-stage molecules, in good yields. Our strategy offers several significant advantages over existing techniques, which include (i) transition-metal and photoredox catalyst-free conditions; (ii) no need for an external SO₂ source; (iii) broad substrate scope; (iv) recyclable and reusable by-products; and (v) excellent atom economy, reaction mass efficiency, process mass intensity, and E-factor and EcoScale scores, highlighting its efficiency and economic sustainability. Detailed mechanistic studies confirm the involvement of an EDA-complex-mediated radical process that operates without a catalyst.