Wang Z.-X,
Li BJ.
* Tsinghua University, Beijing, P. R. of China
Construction of Acyclic Quaternary Carbon Stereocenters by Catalytic Asymmetric Hydroalkynylation of Unactivated Alkenes.
J. Am. Chem. Soc. 2019;
141: 9312-9320
Key words
iridium catalysis - hydroalkynylation - enantioselectivity
Significance
The authors have developed an enantioselective iridium-catalyzed hydroalkynylation reaction. The reaction transforms trisubstituted β,γ-unsaturated amides with excellent γ-selectivity, forming new alkyne-substituted acyclic quaternary carbon stereocenters.
Comment
The kinetic isotope experiments of the alkenes resulted in an inverse KIE; suggesting that the migratory insertion of the alkene is related to the turnover-limiting step. Notably, the authors propose that the selectivity arises from both a facial preference as well as an alkene isomerization process.
