Halogen-atom and group transfer reactivity enabled by hydrogen tunneling.

Autor: Constantin T; Department of Chemistry, University of Manchester, Manchester M13 9PL, UK., Górski B; Department of Chemistry, University of Manchester, Manchester M13 9PL, UK., Tilby MJ; Department of Chemistry, University of Manchester, Manchester M13 9PL, UK., Chelli S; CNRS/Université Toulouse III-Paul Sabatier, Laboratoire Hétérochimie Fondamentale et Appliquée, LHFA UMR 5069, 31062 Toulouse Cedex 09, France., Juliá F; Department of Chemistry, University of Manchester, Manchester M13 9PL, UK., Llaveria J; Global Discovery Chemistry, Therapeutics Discovery, Janssen Research & Development, Janssen-Cilag S.A., 45007 Toledo, Spain., Gillen KJ; LifeArc, Accelerator Building, Open Innovation Campus, Stevenage SG1 2FX, UK., Zipse H; Department Chemie, LMU München, D-81377 München, Germany., Lakhdar S; CNRS/Université Toulouse III-Paul Sabatier, Laboratoire Hétérochimie Fondamentale et Appliquée, LHFA UMR 5069, 31062 Toulouse Cedex 09, France., Leonori D; Institute of Organic Chemistry, RWTH Aachen University, 52056 Aachen, Germany.
Jazyk: angličtina
Zdroj: Science (New York, N.Y.) [Science] 2022 Sep 16; Vol. 377 (6612), pp. 1323-1328. Date of Electronic Publication: 2022 Sep 15.
DOI: 10.1126/science.abq8663
Abstrakt: The generation of carbon radicals by halogen-atom and group transfer reactions is generally achieved using tin and silicon reagents that maximize the interplay of enthalpic (thermodynamic) and polar (kinetic) effects. In this work, we demonstrate a distinct reactivity mode enabled by quantum mechanical tunneling that uses the cyclohexadiene derivative γ-terpinene as the abstractor under mild photochemical conditions. This protocol activates alkyl and aryl halides as well as several alcohol and thiol derivatives. Experimental and computational studies unveiled a noncanonical pathway whereby a cyclohexadienyl radical undergoes concerted aromatization and halogen-atom or group abstraction through the reactivity of an effective H atom. This activation mechanism is seemingly thermodynamically and kinetically unfavorable but is rendered feasible through quantum tunneling.
Databáze: MEDLINE
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