Chiral phosphine-squaramides as enantioselective catalysts for the intramolecular Morita–Baylis–Hillman reaction
作者:Hong-Liang Song、Kui Yuan、Xin-Yan Wu
DOI:10.1039/c0cc03187a
日期:——
squaramides containing tertiary phosphine were developed as chiral bifunctional organic catalysts to promote the asymmetric intramolecularMorita-Baylis-Hillmanreaction of omega-formyl-enones. The adducts were obtained in high yields with good-to-excellent enantioselectivity (up to 93% ee).
A series of chiral bifunctional phosphinothioureas derived from l-amino acids have been developed to promote the enantioselectiveintramolecularMorita–Baylis–Hillmanreaction. The process afforded the cyclic hydroxyl enones with up to 84% ee and good yields under mild conditions.
Asymmetric Sequential Aza-Diels-Alder and<i>O</i>-Michael Addition: Efficient Construction of Chiral Hydropyrano[2,3<i>-b</i>]pyridines
作者:Xiang Yin、Qingqing Zhou、Lin Dong、Yingchun Chen
DOI:10.1002/cjoc.201200942
日期:2012.11
An asymmetric aza‐Diels‐Alder and O‐Michael addition sequence has been developed to construct chiral hydropyrano[2,3‐b]pyridine derivatives with good yields and excellent stereoselectivity, by starting with N‐Ts‐1‐aza‐1,3‐butadienes and aliphatic aldehydes tethered to an α,β‐unsaturated ketone motif. A tandem O‐Michael addition reaction was completed via acid catalysis.
已经开发了一种不对称的aza-Diels-Alder和O - Michael加成序列,从N -Ts-1-aza-1,3开始,构建了具有良好收率和优异立体选择性的手性氢吡喃并[2,3- b ]吡啶衍生物。-α,β-不饱和酮基拴系的丁二烯和脂族醛。通过酸催化完成了O- Michael串联反应。
Enantioselective intramolecular Morita–Baylis–Hillman reaction using chiral bifunctional phosphinothiourea as an organocatalyst
Chiral cyclohexane-based phosphinothioureas were found to be efficient organocatalysts for the enantioselective intramolecular Morita–Baylis–Hillmanreaction of ω-formyl-enone. Among the solvents screened, t-BuOH was the best one which provided good yield and enantioselectivity. Moreover in the presence of 3 mol % of phosphinothiourea 2b, the desired products were obtained in good-to-excellent yields
available hydroxamic acids were leveraged to access challenging nitrones in the presence of H3PO4 as a Brønsted acid catalyst and engaged in an intramolecular (3+2) annulation reaction to make valuable cyclopentane-fused isoxazolidines with high yields and excellent diastereoselectivity. The products were further utilized in a unique base-promoted benzilic amide rearrangement to provide cyclopentane-fused
在 H 3 PO 4作为布朗斯台德酸催化剂存在下,利用容易获得的异羟肟酸来获得具有挑战性的硝酮,并进行分子内 (3+2) 成环反应,以高产率和优异的非对映选择性制备有价值的环戊烷稠合异恶唑烷。该产品进一步用于独特的碱促进的二苯乙醇酰胺重排,以提供带有三个连续立体中心的环戊烷稠合γ-内酰胺作为单一非对映体。