Halogen-atom and group transfer reactivity enabled by hydrogen tunneling.
Science
; 377(6612): 1323-1328, 2022 09 16.
Article
in En
| MEDLINE
| ID: mdl-36108027
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 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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Science
Year:
2022
Document type:
Article
Affiliation country:
United kingdom