Photochemical halogen-bonding assisted generation of vinyl radicals: stereoselective cross coupling between thiols and vinyl halides Manuel Plaza Martínez, Helena Fernández Piedra University of Oviedo, Spain The photochemical halogen-bonding assisted generation of radicals has risen in the last years as a powerful synthetic tool for the creation of radical intermediates under mild reaction conditions. 1 However, this reactivity has up to date been restricted to the generation of aryl and alkyl radicals. The formation of vinyl radicals from the corresponding alkenyl halides stands as a challenging approach under operationally simple and mild conditions, given the low stability for the first ones and high reduction potentials of the second ones. 2 We envisioned that the halogen bonding assisted generation of vinyl radicals would be a feasible process in the photochemical cross coupling reaction between vinyl halides and thiols under basic conditions. The reaction indeed shows a very broad functional group tolerance, is stereoselective, simple and scalable. In-depth mechanistic studies point at the formation of vinyl radical intermediates and DFT calculations support the formation of a halogen-bonding complex as the initiator of the photochemical reaction under visible light irradiation (440 nm). This new methodology could also be applied to the synthesis and modification of biologically active molecules. 3 References 1. For some recent and relevant examples, see: a) C. Zhang, H. Zuo, G. Y. Lee, Y. Zou, Q.-D. Dang, K. N. Houk, D. Niu. Nature Chemistry 2022 , 14 , 686-694. b) N. Kato, T. Nanjo, Y. Takemoto. ACS Catal. 2022 , 12 , 7843-7849. 2. S K. Pagire, T. F ll, O. Reiser. Acc. Chem. Res. 2020 , 53 , 782-791. 3. H. Fernández-Piedra, C. Valdés, M. Plaza. 2022 , manuscript under preparation .
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