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
Quantum chemical DFT calculations (B3LYP/6−31+G*) have been used to gain insight into the conformational and energy properties of the 1-aza- and 1-oxapentadienyl and -heptatrienyl cations 1, 2, 3, and 4. The calculated thermodynamic and kinetic data of the ring-closure reactions giving the cyclic products 5−14 are reported and discussed with respect to the experimental results. Experimentally, synthetic