Login / Signup

Observation of unusual outer-sphere mechanism using simple alkenes as nucleophiles in allylation chemistry.

Yaxin ZengHan GaoZhong-Tao JiangYulei ZhuJinqi ChenHan ZhangGang LuYing Xia
Published in: Nature communications (2024)
Transition-metal catalyzed allylic substitution reactions of alkenes are among the most efficient methods for synthesizing diene compounds, driven by the inherent preference for an inner-sphere mechanism. Here, we present a demonstration of an outer-sphere mechanism in Rh-catalyzed allylic substitution reaction of simple alkenes using gem-difluorinated cyclopropanes as allyl surrogates. This unconventional mechanism offers an opportunity for the fluorine recycling of gem-difluorinated cyclopropanes via C - F bond cleavage/reformation, ultimately delivering allylic carbofluorination products. The developed method tolerates a wide range of simple alkenes, providing access to secondary, tertiary fluorides and gem-difluorides with 100% atom economy. DFT calculations reveal that the C - C bond formation goes through an unusual outer-sphere nucleophilic substitution of the alkenes to the allyl-Rh species instead of migration insertion, and the generated carbon cation then forms the C - F bond with tetrafluoroborate as a fluoride shuttle.
Keyphrases
  • transition metal
  • room temperature
  • density functional theory
  • electron transfer
  • ionic liquid
  • transcription factor