yields (up to 99 %) and excellent diastereo- (up to >99:1 dr) and enantioselectivities (up to 95 % ee) using a low catalyst loading. Most importantly, these results show that the concept of DNA-basedasymmetriccatalysis can be expanded to new synthetic transformations offering an efficient, sustainable, and highly selective tool for the construction of chiral building blocks.
Enantioselective Conjugate Addition of 2-Acylimidazoles with Nitroalkenes Promoted by Chiral-at-Metal Rhodium(III) Complexes
作者:Ganesh Kumar Thota、Gui-Jun Sun、Tao Deng、Yi Li、Qiang Kang
DOI:10.1002/adsc.201701377
日期:2018.3.20
An enantioselective conjugate addition of 2‐acylimidazoles with nitroalkenes catalyzed by chiral‐at‐metal rhodium(III) complex under mild reaction conditions was developed, affording versatile γ‐nitro ketone skeletons in good yields with excellent enantioselectivities (up to >99% ee).
A new strategy, a transient homocoupling dimer strategy, for direct catalytic oxidative cross-enolate coupling reactions is developed. Cross-enolate coupling products bearing a (contiguous) tetrasubstituted carbon center were obtained chemoselectively without the need for stoichiometric amounts of strong bases/metal oxidants, and thus, the present catalysis provides a general method for the synthesis
An efficient asymmetric 1,3-dipolar cycloaddition of α,β-unsaturated 2-acyl imidazoles with N,N′-cyclic azomethine imines catalyzed by a chiral-at-metal rhodium complex is reported. The corresponding N,N′-bicyclic pyrazolidine derivatives with three contiguous tertiary stereocenters were obtained in good yields (up to 99%) with excellent stereoselectivities (>20:1 dr and >99% ee). Remarkably, as little
Enantioselective Mukaiyama-Michael Reaction Catalyzed by a Chiral Rhodium Complex Based on Pinene-Modified Pyridine Ligands
作者:Jun Gong、Qian Wan、Qiang Kang
DOI:10.1002/asia.201800318
日期:2018.9.4
rhodium complex Λ‐Rh1 containing chiral pinene‐modified pyridine ligands is prepared through a two‐step synthetic procedure; it exhibits excellent reactivity and enantiocontrol towards the enantioselective Mukaiyama–Michael reaction of α,β‐unsaturated 2‐acyl imidazoles with silyl enolethers, affording enantioenriched 1,5‐dicarbonyl compounds in good yields (up to 99 %) with excellent enantioselectivities