Tailoring halogen-atom transfer (XAT) methods for overcoming challenging transformations at unactivated c(sp³)-centers Lewis Caiger 1 , Timothée Constantin 1 , James J. Douglas 2 , Daniele Leonori* 3 1 Department of Chemistry, University of Manchester, UK, 2 Early Chemical Development, Pharmaceutical Sciences RD, AstraZeneca, UK, 3 Institute of Organic Chemistry, RWTH Aachen University, Germany Organic halides are integral synthetic intermediates, routinely used both in academia and industry for the preparation of high-value materials. While aryl halides are unparalleled substrates for transition metal catalysed cross-coupling reactions, [1] alkyl halides are still a remarkable challenge. These derivatives suffer from comparatively slower rates of oxidative addition and are susceptible to deleterious β-H elimination from the corresponding alkyl-[M] species (M = metal), leading to a lack of general and effective methods for their functionalisation. Activating alkyl halides by single-electron transfer (SET) is far from facile due to their highly negative reduction potentials ( E red <lt; -2.0 V vs SCE), and thus require strong reductants. Halogen-atom transfer (XAT) however, offers an alternative route for alkyl radical generation without the need of SET. Current XAT strategies are based on tin and silicon reagents that are toxic and expensive. [2] In this poster I will present the applications of α-aminoalkyl and aryl radicals as effective, yet mild and selective XAT agents. [3] The approaches discussed here will highlight the versatile nature of these XAT agents and the orthogonal reactivity offered by the resulting open- shell chemistry.
References 1. (a) A. Suzuki, Angew. Chem., Int. Ed., 2011, 50 , 6723-6737. (b) E.-i. Negishi, Angew. Chem., Int. Ed. , 2011, 50 , 6738-6764. F. Juliá, T. Constantin and D. Leonori, Chem. Rev. , 2022, 122 , 2292-2352. 2. (a) L. Caiger, C. Sinton, T. Constantin, J. J. Douglas, N. S. Sheikh, F. Juliá and D. Leonori, Chem. Sci. , 2021, 12 , 10448- 10454. (b) L. Caiger, H. Zhao, T. Constantin, J. J. Douglas and D. Leonori, ACS Catal. , 2023, 13 , 4985-4991.
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