Support Effect on Stereoselectivities of Vinylogous Mukaiyama–Michael Reactions Catalyzed by Immobilized Chiral Copper Complexes
作者:José M. Fraile、Nuria García、Clara I. Herrerías
DOI:10.1021/cs400743n
日期:2013.12.6
Chiralbis(oxazoline)- and azabis(oxazoline)-copper complexes, used as homogeneous catalysts or immobilized onto laponite, are able to catalyze vinylogous Mukaiyama–Michael reactions between 2-(trimethylsilyloxy)furan and several electron-deficient alkenes. A study of the support effect has been conducted and different changes on the diastereoselectivities and enantioselectivities has been observed
手性双(恶唑啉)和氮杂双(恶唑啉)-铜配合物,用作均相催化剂或固定在锂皂石上,能够催化2-(三甲基甲硅烷氧基)呋喃与几种电子不足的烯烃之间的乙烯基Mukaiyama-Michael反应。已经进行了支持作用的研究,并且观察到非对映选择性和对映选择性的不同变化。取决于底物(迈克尔受体)的结构,催化剂的行为是不同的。当使用亚苄基丙二酸二乙酯时,主要的非对映异构体是具有顺式构型的异构体,但均相和非均相催化剂会导致相反的对映异构体(溶液中-80%ee,异相中38%ee)。这种变化表示约1.8 kcal / mol的支持作用。和N-(E)-but-2-enoyloxazolidinone,最相关的变化是非对映异构体的喜好。在溶液中,反异构体是主要异构体(anti / syn = 98/2);反异构体是主要异构体。然而,相反,固定的催化剂优选顺式异构体(anti / syn = 19/81)。先前在文献
Asymmetric vinylogous Michael reaction of α,β-unsaturated ketones with γ-butenolide under multifunctional catalysis
作者:Huicai Huang、Feng Yu、Zhichao Jin、Wenjun Li、Wenbin Wu、Xinmiao Liang、Jinxing Ye
DOI:10.1039/c0cc01054e
日期:——
general and directorganocatalytic asymmetric vinylogousMichael reaction of gamma-butenolide with alpha,beta-unsaturated ketones was investigated with a multifunctional primary amine salt as catalyst. The reaction enables straightforward access toward synthetically versatile gamma-substituted butenolides from simple 2(5H)-furanone with satisfactory yields, diastereo- and enantioselectivities (up to 30:1
Highly Effective Vinylogous Mukaiyama−Michael Reaction Catalyzed by Silyl Methide Species Generated from 1,1,3,3-Tetrakis(trifluoromethanesulfonyl)propane
Silyl methide species in situ generated from 1,1,3,3-tetrakis(trifluoromethanesulfonyl)propane (Tf2CHCH2CHTf2) performed as an excellent acid catalyst for the vinylogous Mukaiyama-Michael reaction of alpha,beta-unsaturated ketones with 2-silyloxyfurans. Notably, the required loading of Tf2CHCH2CHTf2 to obtain the 1,4-adducts in reasonable yield was significantly low (from 0.05 to 1.0 mol %). This carbon acid-mediated VMM reaction provides a powerful synthetic methodology to construct highly substituted gamma-butenolide structure.
Iodine-catalyzed 1,4-addition of 2-(trimethylsilyloxy)furan to α,β-unsaturated ketones: a facile synthesis of γ-butenolides
The alpha,beta-unsaturated compounds undergo smooth conjugate addition with 2-(trimethylsilyloxy)furan (TMSF) in the presence of 10 mol % of iodine under mild and neutral conditions to afford the corresponding gamma-substituted butenolides in high yields and with good diastereoselectivity. The use of iodine makes this procedure simple, convenient and cost effective. (C) 2009 Published by Elsevier Ltd.
Switchable Diastereoselectivity in the Fluoride-Promoted Vinylogous Mukaiyama–Michael Reaction of 2-[(Trimethylsilyl)oxy]furan Catalyzed by Crown Ethers
作者:Giorgio Della Sala、Marina Sicignano、Rosaria Schettini、Francesco De Riccardis、Luigi Cavallo、Yury Minenkov、Chloé Batisse、Gilles Hanquet、Frédéric Leroux、Irene Izzo
DOI:10.1021/acs.joc.7b00743
日期:2017.7.7
Mukaiyama–Michael reaction of 2-[(trimethylsilyl)oxy]furan with diverse α,β-unsaturated ketones is described. The TBAF-catalyzed VMMR afforded high anti-diastereoselectivity irrespective of the solvents used. The KF/crown ethers catalytic systems proved to be highly efficient in terms of yields and resulted in a highly diastereoselective unprecedented solvent/catalyst switchable reaction. Anti-adducts