Halogen-atom and group transfer reactivity enabled by hydrogen tunneling

Constantin, Timothee; Gorski, Bartosz; Tilby, Michael J.; Chelli, Saloua; Julia, Fabio; Llaveria, Josep; Gillen, Kevin J.; Zipse, Hendrik; Lakhdar, Sami and Leonori, Daniele (2022): Halogen-atom and group transfer reactivity enabled by hydrogen tunneling. In: Science, Vol. 377, No. 6612: pp. 1323-1328

Abstract

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 g-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.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Subjects: 500 Science > 540 Chemistry
• ISSN: 0036-8075
• Language: English