共查询到20条相似文献,搜索用时 15 毫秒
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Dr. Alessandro Livieri Dr. Massimo Boiocchi Prof. Giovanni Desimoni Prof. Giuseppe Faita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(37):11662-11668
Asymmetric reactions involving (E)‐3‐aryl‐1‐(pyridin‐2‐yl‐N‐oxide)prop‐2‐en‐1‐ones and cyclic enol silyl ethers show good yields and excellent enantioselectivities (up to 99.9 % ee) when catalysed by bis(oxazoline)–CuII complexes. Different reaction pathways can be followed by different enol silyl ethers: with 2‐(trimethylsilyloxy)furan, a Mukaiyama–Michael adduct is obtained, whereas a hetero Diels–Alder cycloadduct was formed by using (1,2‐dihydronaphthalen‐4‐yloxy)trimethylsilane. In the latter reaction, the absolute configuration of the product is consistent with a reagent approach to the less hindered Re face of the coordinated substrate in the reactive complex. 相似文献
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Enol ethers have been used for the protection of alcohols (la) and acids (1b,2). The addition of the hydroxyl group on the double bond of the enol ether has been performed, so far, in the presence of a Brönsted acid. 相似文献
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“受阻路易斯酸碱对”(FLPs)催化的烯醇硅醚氢化反应是一类重要的直接合成醇类化合物的方法, 然而目前其反应机理仍不明确. 基于此, 以乙基取代的全氟苯基硼作为路易斯酸(Et-B(C6F5)2), 三叔丁基膦(t-Bu3P)作为路易斯碱, 烯醇硅醚化的苯乙酮(Me-TMS)作为底物建立了模型反应, 并使用密度泛函理论系统研究了其催化氢化反应机理. 结果显示: FLPs催化的烯醇硅醚氢化反应从Et-B(C6F5)2和t-Bu3P形成B-P-FLPs开始, 随后会依次经过H2裂解, H+和H-转移等过程, 其中H+转移为决速步, H-转移无势垒, B-P-FLPs生成及H+转移是吸热反应. 升高温度不利于氢化反应发生, 但是增大压力可促进反应进行. 底物取代基效应会影响H-转移过程, 可能使反应不发生. 相似文献
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黄烷酮烯醇硅醚氧化重排成异黄酮 总被引:7,自引:1,他引:6
3,3″-偶联的双黄烷酮类化合物自1979年首次从瑞香狼毒中分离得到以来,对于它们的合成一直受到重视。我们试图应用Moriarty等人发现的用氧化碘苯氧化酮的烯醇硅醚合成1,4-二芳基-1,4-二酮的方法。 相似文献
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Tri-2-furanylgermane in the presence of a catalytic amount of Et(3)B adds to internal alkenes as well as terminal alkenes effectively to give the corresponding adducts in good to excellent yields. The addition of tri-2-furanylgermane to silyl enol ethers followed by elimination of germyl and siloxy moieties provides a new route for the conversion of ketones into alkenes. 相似文献
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Khalilova Y. A. Faizullina L. Kh. Valeev F. A. 《Russian Journal of Organic Chemistry》2019,55(8):1088-1092
Russian Journal of Organic Chemistry - The addition of lithium enolates and TMS ethers of cyclohexanone and cyclododecanone to levoglucosenone in the presence of Lewis acids was studied. It was... 相似文献
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Tengfei Kang Weidi Cao Liuzhen Hou Qiong Tang Sijia Zou Xiaohua Liu Xiaoming Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2486-2490
A new catalytic asymmetric tandem α‐alkenyl addition/proton shift reaction of silyl enol ethers with ketimines was serendipitously discovered in the presence of chiral N,N′‐dioxide/ZnII complexes. The proton shift preferentially proceeded instead of a silyl shift after α‐alkenyl addition of silyl enol ether to the ketimine. A wide range of β‐amino silyl enol ethers were synthesized in high yields with good to excellent ee values. Control experiments suggest that the Mukaiyama–Mannich reaction and tandem α‐alkenyl addition/proton shift reaction are competitive reactions in the current catalytic system. The obtained β‐amino silyl enol ethers were easily transformed into β‐fluoroamines containing two vicinal tetrasubstituted carbon centers. 相似文献
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Itai Massad Dr. Heiko Sommer Prof. Dr. Ilan Marek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15679-15683
An in situ generated cationic Ir-catalyst isomerizes simple allylic silyl ethers into valuable, fully substituted aldehyde-derived silyl enol ethers. Importantly, by judicious choice of substrate, either of the two possible stereoisomers of a given enolate derivative is accessible with complete stereoselectivity. One-pot isomerization-aldol and isomerization-allylation processes illustrate the synthetic utility of this method. 相似文献
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Michael Addition Catalyzed by Chiral Secondary Amine Phosphoramide Using Fluorinated Silyl Enol Ethers: Formation of Quaternary Carbon Stereocenters 下载免费PDF全文
Jin‐Sheng Yu Fu‐Min Liao Wei‐Ming Gao Kui Liao Run‐Lin Zuo Prof. Dr. Jian Zhou 《Angewandte Chemie (International ed. in English)》2015,54(25):7381-7385
A chiral secondary amine phosphoramide was developed and identified as a powerful catalyst for the Mukaiyama–Michael addition of fluorinated enol silyl ethers to tetrasubstituted olefins. The resulting products are obtained with high enantioselectivities and contain a quaternary carbon stereocenter bearing either a difluoroalkyl or monofluoroalkyl group. 相似文献
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Kui Liao Xiao‐Si Hu Ren‐Yi Zhu Ruo‐Han Rao Jin‐Sheng Yu Feng Zhou Jian Zhou 《中国化学》2019,37(8):799-806
Described herein is an organocatalytic enantioselective protonation of monofluorinated silyl enol ethers, affording an array of optically active α‐secondary α‐fluoroketones in good to high yields and enantioselectivities, under the catalysis of bifunctional cinchonidine derived squaramide C4 . It represents a rare example of facile synthesis of enantioenriched α‐secondary α‐fluoroketones. With D2O as the deuterium source and MeOD as the solvent, the first highly enantioselective preparation of chiral α‐deuterated α‐fluoroketones in >92% deuteration is developed. 相似文献