Aryl Radical‐Mediated Alkenylation of Alkyl Halides

Abstract

The free‐radical alkenylation of a range of alkyl iodides with a vinyldisulfones has been carried out, leading to the desired vinylsulfones in moderate to good yields under mild conditions. The process is initiated by an aryl radical which abstracts the iodine atom from the alkyl iodide to form a C‐centered radical intermediate, the addition of which onto the vinyldisulfone providing the final vinylsulfone. The aryl radical is generated in situ through a single‐electron transfer from an electron donor‐acceptor complex (EDA) formed between a diaryliodonium salt (Ph2I+ PF6−) and triethylamine.

1,2-Bis(phenylsulfonyl)ethylene (BPSE): A Potent Radical C2 Synthon Available in the Radical and Electron-Transfer-Based Organic Synthesis

“…Landais and co-workers have investigated the use of electron-donor-acceptor (EDA) complexes to create a radical initiation system. 25 Specifically, they focused on diaryliodonium salts, hypervalent iodine compounds that form EDA complexes on treatment with electron-donating agents such as amines. Under heating or light irradiation conditions, electron transfer occurs between the components, leading to the generation of aryl radicals.…”

Beyond classical sulfone chemistry: metal- and photocatalytic approaches for C–S bond functionalization of sulfones

“…27 Therefore, the generation of radical precursors from alkyl halides typically relies on the use of tin reagents or other stoichiometric initiators. 28 Pd/light-initiated radical reactions, 29 in which a SET reaction between alkyl iodides and Pd(0) under photoirradiation allows the generation of the initial alkyl radical is a practical way to solve this problem. Based on this design principle, Ryu and co-workers have devised a protocol for the alkenylation of alkyl iodides with alkenyl sulfones under Pd/photoirradiation (Xe, 800 W m −2 ) catalyst system (Scheme 14).…”

Copper-Catalyzed Difluoromethylation of Alkyl Halides Enabled by Aryl Radical Activation of Carbon–Halogen Bonds

“…44 Nonetheless, such a reactivity has received little attention in synthetic applications. [45][46][47] We hypothesize that various alkyl iodides could be converted to alkyl radicals for copper catalysis via the use of the transient aryl radicals that could be readily generated via copper-catalyzed pathways, e.g., from arenediazonium salts. The SET to arenediazonium salts is a unique reactivity of Cu I complexes and has been widely involved in transformations of arenediazonium salts, including Sandmeyer reaction and Meerwein arylation.…”