- Recyclable and reusable PdCl2(PPh3)2/PEG-400/H2O system for the hydrophenylation of alkynes with sodium tetraphenylborate
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A stable and efficient PdCl2(PPh3)2/PEG-400/H2O catalytic system for the hydrophenylation reaction of alkynes has been developed. In the presence of 3 mol% PdCl2(PPh3)2 and 2 equiv. of HOAc, the hydrophenylation of both terminal and internal alkynes with sodium tetraphenylborate proceeded smoothly in a mixture of PEG-400 and water at room temperature or 50 °C to afford a variety of phenyl-substituted alkenes in moderate to high yields. The isolation of the products was easily performed by extraction with petroleum ether, and the PdCl2(PPh3)2/PEG-400/H2O system could be readily recycled and reused six times without apparent loss of catalytic activity.
- Liu, Rong,Zhang, Tingli,Huang, Bin,Cai, Mingzhong
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p. 172 - 178
(2020/07/04)
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- Copper(i)-catalysed asymmetric allylic reductions with hydrosilanes
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A copper(i)-catalysed asymmetric allylic reduction enables a regio- and stereoselective transfer of a hydride nucleophile in an SN2′-fashion onto allylic bromides. This transformation represents a conceptually orthogonal approach to allylic substitution reactions with carbon nucleophiles. A copper(i) complex based upon a chiral N-heterocyclic carbene (NHC) ligand allows for stereoselectivity reaching 99% ee. The catalyst enables a stereoconvergent reaction irrespective of the double bond configuration of the starting materials.
- Thanh Nguyen,Thiel, Niklas O.,Teichert, Johannes F.
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supporting information
p. 11686 - 11689
(2017/11/03)
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- 1,3,4-ALKENYL OXADIAZOLE AMINO ACID DERIVATIVES AS SPHINGOSINE-1-PHOSPHATE RECEPTORS' MODULATORS
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The present invention relates to 1,3,4-alkenyl oxadiazole amino acid derivatives of formulae I and II, processes for preparing them, pharmaceutical compositions containing them and their use as pharmaceuticals as modulators of sphingosine-1-phosphate receptors.
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Page/Page column 21; 22
(2015/06/03)
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- Effect of multinuclear copper/aluminum complexes in highly asymmetric conjugate addition of trimethylaluminum to acyclic enones
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Al and friends: Asymmetric conjugate addition of Me3Al to β,β-disubstituted α,β-unsaturated ketones in the presence copper and L1 leads to a highly efficient construction of an all-carbon-substituted chiral quaternary center. This result is the first example of an asymmetric conjugate addition of Me3Al to acyclic enones to give a chiral quaternary carbon center with excellent yield and enantioselectivity under mild reaction conditions. Copyright
- Endo, Kohei,Hamada, Daisuke,Yakeishi, Sayuri,Shibata, Takanori
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supporting information
p. 606 - 610
(2013/02/23)
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- Palladium-catalyzed hydrophenylation of alkynes with sodium tetraphenylborate under mild conditions
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(Chemical Equation Presented) In an aqueous solution of acetic acid, PdCl2(PPh3)2 showed high catalytic activity for the hydrophenylation of both terminal and internal alkynes with sodium tetraphenylborate (NaBPh4) under mild conditions, affording phenyl alkenes in moderate to excellent yields.
- Zeng, Hanxiang,Hua, Ruimao
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p. 558 - 562
(2008/09/17)
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- Novel syntheses of α,β-unsaturated esters, α,β-unsaturated γ-lactones, and 2-alkoxypyrroles via 1,2,4-triazole-stabilized allenic anions
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The dianion 12 (?13) of 1-(1,2,4-triazol-1-yl)phenylpropargyl ethyl ether 11 (readily prepared from phenylpropargylaldehyde diethyl acetal 8 and 1,2,4-triazole) reacts with alkyl halides, aldehydes, ketones, and α,β-unsaturated ketones to give exclusively γ-substituted allenic products of type 10. These adducts underwent mild in situ hydrolysis enabling convenient syntheses of α,β-unsaturated esters 9a-c and α,β-unsaturated γ-lactones 16, 18, 20, and 22. Reactions of dianion 13 with imines generated the 1,3,4-trisubstituted 2-alkoxypyrroles 27, 30, and 31 in high yields. The alkylsubstituted analog 34 underwent similar reactions to give predominantly the γ-products 39, 40, and 42 along with a small proportion of α-analogs.
- Katritzky, Alan R.,Feng, Darning,Lang, Hengyuan
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p. 715 - 720
(2007/10/03)
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- New reaction mode of the Horner-Wadsworth-Emmons reaction using Sn(OSO2CF3)2 and N-ethylpiperidine
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Excellent Z or E selectivity is observed in the Horner-Wadsworth-Emmons reactions of methyl bis(trifluoroethyl)phosphonoacetate 2 with aryl alkyl ketones 3a-d or aldehydes 3f,g using Sn(OSO2CF3)2 in the presence of N-ethylpiperidine, which should have a different reaction mode to those using sodium hydride.
- Sano, Shigeki,Yokoyama, Kenji,Fukushima, Mari,Yagi, Tetsuo,Nagao, Yoshimitsu
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p. 559 - 560
(2007/10/03)
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