排序方式: 共有59条查询结果,搜索用时 93 毫秒
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Antonio L. Braga Helmoz R. Appelt Claudio C. Silveira Ludger A. Wessjohann Paulo H. Schneider 《Tetrahedron》2002,58(52):10413-10416
The enantioselective alkynylation reaction of aldehydes with alkynes and diethylzinc, catalyzed by chiral disulfide–oxazolidine ligands, provides a simple, practical and inexpensive method to access chiral propargylic alcohols in good yields and satisfactory ee's. 相似文献
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Marie-Luise Lechner Roland Fischer Frank Uhlig 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1341-1345
Abstract The reaction of dialkyltinhydrides with dialkylzinc results in a tin metal bond formation. Crystal structures of 1,1,1,2,3,3,3-hepta-phenyl-2-(ethylzincio)tristannane *TMEDA 1, 1,1,2,2,3,3,4,4-octaphenyl-1,4-(ethylzincio)tetrastannane*2TMEDA 2, and triphenyl(phenylzincio)stannane*TMEDA 3 could be obtained. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT 相似文献
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The synthesis of several novel three-dentate sulfonamide alcohol ligands is described, starting from camphorsulfonyl chloride. The influence of temperature and ligand structure on the asymmetric addition of dietylzinc to aromatic aldehydes has been studied. Enantioselectivities up to 76% have been obtained. 相似文献
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A new series of chiral 3‐hydroxyazetidines has been prepared from (S)‐1‐(4‐methoxyphenyl)ethylamine. These ligands have shown excellent catalytic activities and enantiomeric selectivities in asymmetric addition of diethylzinc to aromatic aldehydes. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Zhiyong Gong Qingwen Liu Pengchong Xue Kechang Li Zhiguang Song Zaiqun Liu Yinghua Jin 《应用有机金属化学》2012,26(3):121-129
Several novel chiral thiazoline primary and tertiary alcohols were easily synthesized from commercially available l ‐cysteine in three steps and with high yield. These ligands were subsequently applied to the asymmetric addition of diethylzinc (Et2Zn) to various aldehydes. Products with S configuration were obtained when thiazoline‐containing tertiary alcohol ligands were used as catalysts. The primary alcohol induced corresponding products with R configuration in 68% enantiomeric excess, which was a higher value relative to other N―O ligands possessing a primary alcohol unit in the literature. Furthermore, a plausible transition state model was proposed to explain the observed enantioselectivities. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Enantioselective addition of diethylzinc to a series of aromatic aldehydes was developed using a modular amino acid amide chiral ligand (2S)‐3‐phenyl‐N‐((R)‐1‐phenyl‐ethyl)‐2‐(tosylamino)propanamide without using titanium complex. The catalytic system employing 10 mol% of 1g was found to promote the addition of diethylzinc (ZnEt2) to a wide range of aromatic aldehydes with electron‐donating and electron‐withdrawing substituents, giving up to 82% ee of the corresponding secondary alcohol under mild conditions. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Enantioselective addition of diethylzinc to a series of aromatic aldehydes was developed using a modular amino acids and ${\bf \beta}$ ‐amino alcohol‐based chiral ligand (2R)‐N‐[(1R,2S)‐1‐hydroxy‐1‐phenylpropan‐2‐yl]‐3‐phenyl‐2‐(tosylamino) propanamide ( 1f ) without using titanium complex. The catalytic system employing 15 mol% of 1f was found to promote the addition of diethylzinc (ZnEt2) to a wide range of aromatic aldehydes with electron‐donating and electron‐withdrawing substituents, giving up to 97% ee of the corresponding secondary alcohol under mild conditions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献