Modular Synthesis of γ-Chloro Ketones through Carbochlorination of Alkenes Mediated by Copper(I) Photoredox Catalysis

Abstract

γ-Chloro ketones are multifunctional synthons that serve as versatile linchpins for the rapid assembly of molecular complexity. Despite this strategic value, their broader adoption remains conspicuously limited as a consequence of the intrinsic challenges associated with their preparation. Herein, we report a visible-light-driven, copper-catalyzed carbochlorination of alkenes that provides γ-chloro ketones from readily available α-chloro analogues. The resulting products engage as versatile building blocks, enabling direct access to a range of heterocycles, (spiro-)cyclopropanes, and γ-functionalized ketones. A key feature of this transformation is the use of heteroleptic Cu(I) photocatalysts, which combine strong reducing power in the excited state with ligand exchange processes that enable terminal bond formation at the copper center. This duality enables reactivity that is not readily accessed with common organic or iridium-based photocatalysts. Mechanistic studies support the involvement of two active photocatalytic species that together enable the challenging access to α-keto radicals from α-chloro ketones. They further underscore the role of the dmp ligand in stabilizing Cu(II) intermediates, thereby facilitating carbon−chlorine bond formation. This simple and efficient methodology provides expedient access to multifunctional building blocks, set up for downstream diversification.