Catalytic Asymmetric Hydroalkenylation of Vinylarenes: Electronic Effects of Substrates and Chiral N-Heterocyclic Carbene Ligands.
- Resource Type
- Article
- Authors
- Ho, Chun-Yu; Chan, Chun-Wa; He, Lisi
- Source
- Angewandte Chemie International Edition. Apr2015, Vol. 54 Issue 15, p4512-4516. 5p.
- Subject
- *ALKENYLATION
*HETEROCYCLIC chemistry
*CARBENES
*LIGANDS (Chemistry)
*NICKEL
*ALKENES
*ENANTIOSELECTIVE catalysis
- Language
- ISSN
- 1433-7851
An asymmetric tail-to-tail cross-hydroalkenylation of vinylarenes with terminal olefins was achieved by catalysis with NiH complexes bearing chiral N-heterocyclic carbenes (NHCs). The reaction provides branched gem-disubstituted olefins with high enantioselectivity (up to 94 % ee) and chemoselectivity (cross/homo product ratio: up to 99:1). Electronic effects of the substituents on the vinylarenes and on the N-aryl groups of the NHC ligands, but not a π,π-stacking mechanism, assist the steric effect and influence the outcome of the cross-hydroalkenylation. [ABSTRACT FROM AUTHOR]