Enantioselective Synthesis of Dihydropyrans. Catalysis of Hetero Diels−Alder Reactions by Bis(oxazoline) Copper(II) Complexes
作者:David A. Evans、Jeffrey S. Johnson、Edward J. Olhava
DOI:10.1021/ja992175i
日期:2000.3.1
C2-symmetric bis(oxazoline)−Cu(II) complexes 1 and 2 catalyze the inverse electron demand hetero Diels−Alder reaction of α,β-unsaturated carbonyl compounds (heterodiene) with electron-rich olefins (heterodienophile) in high diastereo- and enantioselectivity. α,β-Unsaturated acyl phosphonates and β,γ-unsaturated α-keto esters and amides are effective heterodienes, while enol ethers and sulfides function
Air-stable and recyclable, the CuII -(bis)oxazoline complex 1 efficiently catalyzes diastereo- and enantioselective hetero-Diels-Alder reactions between β,γ-unsaturated α-keto acid derivatives 2 and vinyl ethers for the synthesis of substituted dihydropyrans 3 [Eq. (1)]. Results of the crystalstructure analysis of 1 in combination with calculations on model compounds indicate the formation of a reactive
Cu II-(双)恶唑啉络合物1空气稳定且可回收,可有效催化β,γ-不饱和α-酮酸衍生物2和乙烯基醚之间的非对映和对映选择性杂Diels-Alder反应,用于合成取代的二氢吡喃3 [等式 (1)]。1的晶体结构分析结果与对模型化合物的计算相结合,表明通过用螯合底物取代两个H 2 O配体,形成了反应性中间体。X = OEt,N(OMe)Me;R =烷基,芳基,烷氧基,硫代苄基。
Modular Chiral Bisoxalamide–Copper-Catalyzed Asymmetric Oxo-Diels–Alder Reaction: Carbonyl Coordination for High Enantio- and Diastereocontrols
作者:Jun-Bo Chen、Man Xu、Jun-Qi Zhang、Bing-Bing Sun、Jia-Ming Hu、Jie-Qiang Yu、Xing-Wang Wang、Yuanzhi Xia、Zheng Wang
DOI:10.1021/acscatal.9b05606
日期:2020.3.20
of efficient C2-symmetric chiral ligands for copper(II)-catalyzed asymmetric inverse-electron demand oxo-Diels–Alder reactions between β,γ-unsaturatedα-ketoesters and 2,3-dihydrofuran or 3,4-dihydro-2H-pyran. The reactions proceeded smoothly under mild conditions to afford the corresponding [4 + 2] cycloadducts in high yields with good enantioselectivities (up to 94% ee) and diastereoselectivities (up
Enantioselective Organocopper-Catalyzed Hetero Diels–Alder Reaction through <i>in Situ</i> Oxidation of Ethers into Enol Ethers
作者:Ahmet Yesilcimen、Na-Chuan Jiang、Felix H. Gottlieb、Masayuki Wasa
DOI:10.1021/jacs.2c01656
日期:2022.4.13
We demonstrate that a chiral Cu–BOX complex catalyzes the efficient oxidation of ethers into enol ethers in the presence of trityl acetate. Then, the organocopper promotes stereoselective heteroDiels–Alderreaction between the in situ generated enol ethers and β,γ-unsaturated ketoesters, allowing for rapid access to an array of dihydropyran derivatives possessing three vicinal stereogenic centers.
Asymmetric Cycloaddition of β,γ-Unsaturated α-Ketoesters with Electron-Rich Alkenes Catalyzed by a Chiral Er(OTf)3/N,N′-Dioxide Complex: Highly Enantioselective Synthesis of 3,4-Dihydro-2 H-pyrans
The asymmetric inverse‐electron‐demand hetero‐Diels–Alder (HDA) reactions of β,γ‐unsaturated α‐ketoesters with electron‐rich alkenes were investigated, with an N,N′‐dioxide/erbium(III) complex employed as the catalyst. Quantitative conversion of the β,γ‐unsaturated α‐ketoesters and excellent enantioselectivities (up to >99 % ee) and diastereoselectivities (up to >99:1 d.r.) were observed for a broad