Enantioselective Synthesis of β,γ-Unsaturated α-Fluoroesters Catalyzed by N-Heterocyclic Carbenes
作者:Yu-Ming Zhao、Man Sing Cheung、Zhenyang Lin、Jianwei Sun
DOI:10.1002/anie.201204521
日期:2012.10.8
NHC meets F: NHC‐bound enolates undergo a catalytic asymmetric fluorination reaction to β,γ‐unsaturatedα‐fluoroesters, which are obtained with good efficiency and stereoselectivity (see scheme, NFSI=N‐fluorobenzenesulfonimide). The strategy overcomes possible challenges, such as fluorination in the γ position and difluorination. Experimental evidence combined with DFT calculations provides insight
Photo-induced energy transfer relay of N-heterocyclic carbene catalysis: an asymmetric α-fluorination/isomerization cascade
作者:Xinhang Jiang、En Li、Jiean Chen、Yong Huang
DOI:10.1039/d0cc07264h
日期:——
transfer process that leads to selective access of chiral allylic fluorides with a cis-olefin geometry. In the absence of a photocatalyst or light, the reaction proceeds smoothly to give (E)-olefin products, while the (Z)-isomer can be obtained under photosensitizing conditions. Preliminary mechanistic experiments suggest that an energy transfer process might be operative.