Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, P.R. of China.
Chemistry. 2010 Oct 18;16(39):11963-8. doi: 10.1002/chem.201001365.
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.
已开发出通过手性 N,N'-二氧化物-Cu(OTf)(2)(Tf=三氟甲磺酸根)配合物催化的β,γ-不饱和α-酮酯与环戊二烯的高对映选择性 Diels-Alder(DA)和逆电子需求杂 Diels-Alder(HDA)反应。β,γ-不饱和α-酮酯的定量转化率和优秀的非对映选择性(高达 99:1)和对映选择性(高达>99%ee)观察到广泛的底物范围。芳香族和脂肪族β,γ-不饱和α-酮酯均被发现是反应的合适底物。此外，通过调节反应温度可以提高 DA 和 HDA 加合物的化学选择性。在室温下获得了高达 94%的 DA 加合物的良好至高化学选择性，并且在低温下获得了高达 65%的 HDA 加合物的适度化学选择性。该反应还具有温和的反应条件、简单的程序和显著低的催化剂负载量(0.1-1.5mol%)。观察到强烈的正非线性效应。
