Asymmetric Diels-Alder and inverse-electron-demand hetero-Diels-Alder reactions of β,γ-unsaturated α-ketoesters with cyclopentadiene catalyzed by N,N'-dioxide copper(II) complex.
Highly enantioselective Diels-Alder (DA) and inverse-electron-demand hetero-Diels-Alder (HDA) reactions of β,γ-unsaturated α-ketoesters with cyclopentadiene catalyzed by chiral N,N'-dioxide-Cu(OTf)(2) (Tf=triflate) complexes have been developed. Quantitative conversion of β,γ-unsaturated α-ketoesters and excellent diastereoselectivities (up to 99:1) and enantioselectivities (up to >99% ee) were observed for a broad range of substrates. Both aromatic and aliphatic β,γ-unsaturated α-ketoesters were found to be suitable substrates for the reactions. Moreover, the chemoselectivity of the DA and HDA adducts were improved by regulating the reaction temperature. Good to high chemoselectivity (up to 94%) of the DA adducts were obtained at room temperature, and moderate chemoselectivity (up to 65%) of the HDA adducts were achieved at low temperature. The reaction also featured mild reaction conditions, a simple procedure, and remarkably low catalyst loading (0.1-1.5 mol%). A strong positive nonlinear effect was observed.
Zhu
Yin
Y
Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, P.R. of China.
Chen
Xiaohong
X
Xie
Mingsheng
M
Dong
Shunxi
S
Qiao
Zhen
Z
Lin
Lili
L
Liu
Xiaohua
X
Feng
Xiaoming
X
D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D003517:Cyclopentanes / Q000737:chemistry*; D004952:Esters; D007659:Ketones / Q000737:chemistry*; D058116:Lewis Acids / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D003517:Cyclopentanes; D004952:Esters; D007659:Ketones; D058116:Lewis Acids; D003300:Copper