- Palladium-Catalyzed Aerobic Oxygenation of Allylarenes
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An efficient and practical protocol for the synthesis of (E)-allylethers from readily available olefins with alcohols or phenols was developed. This aerobic oxidative allylic C-H oxygenation protocol features mild conditions, broad substrate scope, and hi
- Li, Chunsheng,Li, Meng,Li, Jianxiao,Liao, Jianhua,Wu, Wanqing,Jiang, Huanfeng
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p. 10912 - 10919
(2017/10/27)
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- Step-economy etherification of acylated alcohols
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An efficient and convenient protocol has been developed for ether bond formation in mild conditions. A mixture of primary/secondary ester and allylic/benzylic halide in tetrahydrofuran was treated with KOtBu at room temperature to give ether in high yield. This step economic method enabled direct alkylation of the acyl group masked O-nucleophiles. Application of this method in carbohydrate synthesis was feasible and chemo-selectivity can be achieved.
- Xu, Hua-Dong,Xu, Ke,Zheng, Qing,He, Wei-Jie,Shen, Mei-Hua,Hu, Wen-Hao
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supporting information
p. 6836 - 6838
(2015/01/09)
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- Expanded substrate scope and improved reactivity of ether-forming cross-coupling reactions of organotrifluoroborates and acetals
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Mixed acetals and organotrifluoroborates undergo BF3· OEt2-promoted cross-couplings to give dialkyl ethers under simple, mild conditions. A survey of reaction partners identified a hydroxamate leaving group that improves the regioselectivity and product yield in the BF 3·OEt2-promoted coupling reaction of mixed acetals and potassium alkynyl-, alkenyl-, aryl- and heteroaryltrifluoroborates to access substituted dialkyl ethers. This leaving group enables the reaction to proceed rapidly under mild conditions (0 °C, 5-60 min) and permits reactions with electron-deficient potassium aryltrifluoroborates that are less reactive with other acetal substrates. A study of the reaction mechanism and characterization of key intermediates by NMR spectroscopy and X-ray crystallography identified a role for the hydroxamate moiety as a reversible leaving group that serves to stabilize the key oxocarbenium intermediate and the need for a slight excess of organodifluoroborane to serve as a catalyst. A secondary role for the boron nucleophile as an activating ligand was also considered. These studies provide the basis for a general class of reagents that lead to dialkyl ethers by a simple, predictable cross-coupling reaction.
- Vo, Cam-Van T.,Mitchell, T. Andrew,Bode, Jeffrey W.
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p. 14082 - 14089
(2011/10/12)
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- Regio- and stereoselective Au(I)-catalyzed intermolecular hydroalkoxylation of aryl allenes
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In the presence of a catalytic amount of Ph3PAuNO3 and H2SO4, the hydroalkoxylation of allenes with alcohols has been shown to proceed smoothly and give allylic ethers in good yields and high regio- and stereoselectivity. Georg Thieme Verlag Stuttgart.
- Cui, Dong-Mei,Yu, Ke-Rui,Zhang, Chen
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scheme or table
p. 1103 - 1106
(2009/09/30)
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- Pd(O)-PhCOOH catalyzed addition of oxygen pronucleophiles to allenes and internal alkynes
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We have developed a catalytic system that enables the addition of alcohols to allenes using a combination of 5 mol% Pd(PPh3)4 and 10 mol% benzoic acid. Likewise, the addition reaction of carboxylic acids to alkynes is described. In all cases the reaction proceeded well, giving the corresponding allylation products in good-to-high yields with high regio- and stereoselectivities.
- Patil, Nitin T.,Pahadi, Nirmal K.,Yamamoto, Yoshinori
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p. 569 - 573
(2007/10/03)
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- Microwave-enhanced Pd(0)/acetic acid catalyzed allylation reactions of C, N, and O-pronucleophiles with alkynes
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An efficient method for the allylation of C, N, and O-nucleophiles with alkynes under solvent-free conditions and by microwave activation is established. The process can be termed as a real eco-chemical process since no waste elements are produced in the
- Patil, Nitin T.,Nawaz Khan,Yamamoto, Yoshinori
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p. 8497 - 8499
(2007/10/03)
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- Iridium-catalyzed intermolecular allylic etherification with aliphatic alkoxides: Asymmetric synthesis of dihydropyrans and dihydrofurans
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Hindered chiral ethers with one or two stereocenters are now readily available by allylic etherification of primary and secondary alkoxides (see reaction). When an Ir-phosphoramidite complex is used as the catalyst, the reaction proceeds with high regio-, enantio-, and diastereoselectivity. Np = 1-naphthyl.
- Shu, Chutian,Hartwig, John F.
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p. 4794 - 4797
(2007/10/03)
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- Palladium/benzoic acid-catalyzed hydroalkoxylation of alkynes
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The reaction of the internal alkyne 1 with alcohols 2 in the presence of a catalytic amount of Pd(PPh3)4 and benzoic acid in dioxane at 100°C gave the allylic ethers 3 in good to high yields. The reaction proceeds via the palladium/benzoic acid-catalyzed isomerization of the alkyne 1 to allene 6, followed by the addition of alcohols 2 to the π-allylpalladium intermediate 7 formed by the hydropalladation of the resulting allene 6. Furthermore, the intramolecular reaction of alkynes having a hydroxy group at the terminus of the carbon chain gave five- and six-membered cyclic ethers in good yields.
- Kadota, Isao,Lutete, Leopold Mpaka,Shibuya, Akinori,Yamamoto, Yoshinori
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p. 6207 - 6210
(2007/10/03)
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- MERCURY(II) OXIDE/TETRAFLUOROBORIC ACIDPROMOTED VICINAL HYDROXY- AND ALKOXYLATION OF ALKENES
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The reaction of alkenes with mercury(II) oxide/tetrafluoroboric acid and alcohols or water involves reduction to Hg(O) and vicinal diethers or diols are produced in good yields.Olefins bearing benzylic hydrogens in an α position lead to cinnamyl ethers.Mechanisms are proposed to account for the products and their stereochemistry.
- Barluenga, Jose,Alonso-Cires, Luisa,Campos, Pedro J.,Asensio, Gregorio
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p. 2563 - 2568
(2007/10/02)
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- MERCURY(II) OXIDE/TETRAFLUOROBORIC ACID. AN UNUSUAL BEHAVIOR IN THE OXIDATION OF ALKENES. SYNTHESIS OF trans-CINNAMYLETHERS
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The synthesis of trans-cinnamylethers by oxidation of allylbenzene is described.The reaction cannot be explained by formation of an allylic mercurial.A new type of mechanism in the oxidation of alkenes by mercury(II) salts is proposed.
- Barluenga, Jose,Alonso-Cires, Luisa,Asensio, Gregorio
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p. 2239 - 2240
(2007/10/02)
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