- Indium(III) chloride/chlorotrimethylsilane as a highly active Lewis acid catalyst system for the Sakurai-Hosomi reaction
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The indium(III) chloride/chlorotrimethylsilane system acts as a catalyst for the Sakurai-Hosomi reaction between allylsilanes and aldehydes. When γ-substituted allylsilanes such as crotylsilane and prenylsilane are used a high regioselectivity for γ-addit
- Onishi, Yoshiyuki,Ito, Takeshi,Yasuda, Makoto,Baba, Akio
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- Benzylic intermolecular carbon-carbon bond formation by selective anodic oxidation of dithioacetals.
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[reaction: see text]. Novel anodic intermolecular carbon-carbon bond formation has been accomplished by the oxidative carbon-sulfur bond fission of benzylic dithioacetals to give a wide variety of aromatic compounds. The substitution reaction successfully
- Chiba,Uchiyama,Kim,Kitano,Tada
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Read Online
- Ytterbium trichloride-catalyzed allylation of aldehydes with allyltrimethylsilane
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Ytterbium chloride (YbCl3) is found to be an effective catalyst for the allylation of both aromatic and aliphatic aldehydes using allyltrimethylsilane.
- Fang, Xinggao,Watkin, John G.,Warner, Benjamin P.
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- Arylboronic Acid Catalyzed C-Alkylation and Allylation Reactions Using Benzylic Alcohols
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The arylboronic acid catalyzed dehydrative C-alkylation of 1,3-diketones and 1,3-ketoesters using secondary benzylic alcohols as the electrophile is reported, forming new C-C bonds (19 examples, up to 98% yield) with the release of water as the only byproduct. The process is also applicable to the allylation of benzylic alcohols using allyltrimethylsilane as the nucleophile (12 examples, up to 96% yield).
- Estopi?á-Durán, Susana,McLean, Euan B.,Donnelly, Liam J.,Hockin, Bryony M.,Taylor, James E.
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supporting information
p. 7547 - 7551
(2020/10/09)
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- Cationic Cobalt Porphyrin-Catalyzed Allylation of Aldehydes with Allyltrimethylsilanes
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Cationic cobalt porphyrin-catalyzed allylation of aldehydes with allyltrimethylsilanes is developed. The formation of the aldehyde-cobalt porphyrin complex, the key intermediate for the addition of allylsilanes, is confirmed by theoretical studies and syn
- Tomifuji, Rei,Masuda, Shota,Kurahashi, Takuya,Matsubara, Seijiro
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supporting information
p. 3834 - 3837
(2019/05/24)
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- Scandium as a pre-catalyst for the deoxygenative allylation of benzylic alcohols
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Scandium triflate is an effective pre-catalyst for the deoxygenative allylation of benzylic alcohols with a narrow substrate window. The reaction is shown to proceed through a "hidden Br?nsted acid" mechanism. The reaction is efficient provided that the aryl group is neither too electron rich nor too electron poor. It is shown that this allows useful selectivity. The reaction also works for benzyhydryl alcohols with broader scope. The reaction may also be catalysed by Nafion.
- ?oli?, Ivan,Seankongsuk, Pattarakiat,Loh, Joanna Kejun,Vilaivan, Tirayut,Bates, Roderick W.
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supporting information
p. 119 - 123
(2017/12/27)
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- Catalytic Performance of Al-MCM-41 Catalyst for the Allylation of Aromatic Aldehydes with Allyltrimethylsilane: Comparison with TiCl4 as Lewis acid
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Mesoporous Al-MCM-41 molecular sieve with Si/Al ratio equal to 12.5 was synthesized under hydrothermal condition using cetyltrimithylammonium bromide (CTAB) as surfactant. This solid was characterized using several techniques e.g. powder X-ray diffraction (XRD), N2 adsorption-desorption, FT-IR, TG/DTG and pyridine adsorption-desorption followed by IR spectroscopy. The catalytic performance of Al-MCM-41 catalyst as Lewis acid was used without treatment and was compared with TiCl4 in the allylation of aromatic aldehydes with allyltrimethylsilane. The results showed that in presence of Al-MCM-41, homoallyl silyl ether is obtained regardless of the nature of aromatic aldehydes at a temperature of 35?°C. When TiCl4 was used, the reactions require temperature of ?85?°C and all the products obtained were due to the diallylation. To explain this different allylation in the presence of the Al-MCM-41 or TiCl4, two plausible reaction mechanisms are proposed. The Al-MCM-41 was used in four consecutive experiments without important loss of activity, confirming it stability. Finally, a new method for preparing single allylation in the short timeframe and mild conditions are presented.
- Brahmi, Lamia,Ali-Dahmane, Tewfik,Hamacha, Rachida,Hacini, Salih
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- Trifluoromethanesulfonic acid catalyzed Friedel-Crafts alkylations of 1,2,4-trimethoxybenzene with aldehydes or benzylic alcohols
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Trifluoromethanesulfonic acid in acetonitrile was found to efficiently catalyze Friedel-Crafts alkylations of 1,2,4-trimethoxybenzene with a variety of simple or functionalized aldehydes to provide di- or triarylmethanes in high yields. The operationally
- Wilsdorf, Michael,Leichnitz, Daniel,Reissig, Hans-Ulrich
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supporting information
p. 2494 - 2497
(2013/07/05)
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- HClO4-supported on silica gel: A mild and efficient catalyst for Hosomi-Sakurai reaction
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Perchloric acid supported on silica gel was found to be an efficient catalyst (2 mol %) for the Hosomi- Sakurai allylation of numerous aldehydes with allyltrimethylsilane in the presence of benzyl alcohol. This method was also effective for the allylation of secondary alcohols under mild experimental conditions.
- Murugan, Kaliyappan,Chen, Chinpiao
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experimental part
p. 5827 - 5830
(2011/12/03)
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- Silicomolybdic acid supported on silica gel: An efficient catalyst for Hosomi-Sakurai reactions
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Silicomolybdic acid that is supported on silica gel (50 wt %) efficiently catalyzes the high-yielding Hosomi-Sakurai allylation of carbonyl compounds by allyltrimethylsilane in the presence of benzyl alcohol. The reaction rates of inactive substrates and the yields were greatly increased when preformed acetals were used as substrates.
- Murugan, Kaliyappan,Srimurugan, Sankareswaran,Chen, Chinpiao
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experimental part
p. 5621 - 5629
(2011/08/09)
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- Design, synthesis and structure-activity relationship of novel [3.3.1] bicyclic sulfonamide-pyrazoles as potent γ-secretase inhibitors
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The structure-activity relationship (SAR) of a novel, potent and metabolically stable series of sulfonamide-pyrazoles that attenuate β-amyloid peptide synthesis via γ-secretase inhibition is detailed herein. Sulfonamide-pyrazoles that are efficacious in reducing the cortical Aβx-40 levels in FVB mice via a single PO dose, as well as sulfonamide-pyrazoles that exhibit selectivity for inhibition of APP versus Notch processing by γ-secretase, are highlighted.
- Aubele, Danielle L.,Truong, Anh P.,Dressen, Darren B.,Probst, Gary D.,Bowers, Simeon,Mattson, Matthew N.,Semko, Chris M.,Sun, Minghua,Garofalo, Albert W.,Konradi, Andrei W.,Sham, Hing L.,Zmolek, Wes,Wong, Karina,Goldbach, Erich,Quinn, Kevin P.,Sauer, John-Michael,Brigham, Elizabeth F.,Wallace, William,Nguyen, Lan,Bova, Michael P.,Hemphill, Susanna S.,Basi, Guriqbal
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scheme or table
p. 5791 - 5794
(2011/10/19)
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- Lithium naphthalenide-induced reductive alkylation and addition of aryl-and heteroaryl-substituted dialkylacetonitriles
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Lithium naphthalenide (LN)-induced reductive alkylation/addition reactions of aryl-, pyridyl-, and 2-thienyl-substituted dialkylacetonitriles have been investigated. Upon treatment with LN in THF at -40°C, both aryl and pyridyl precursors could undergo the reductive decyanation smoothly, and the in situ generated carbanions could be readily trapped by alkyl halides, ketones, aldehydes, or even oxygen to afford a wide range of functionalized aromatic derivatives bearing a newly established quaternary carbon. To effect the desired reductive alkylation of 2-thienyldialkylacetonitriles, a much lower temperature such as -100°C was required. Also with these substrates, an interesting ring-opening/S-alkylation process was observed when the reductive alkylation were performed at -78°C to give 1-alkylsulfanyl-1,3,4-trienes. A mechanistic discussion is given for this observation.
- Tsao, Jing-Po,Tsai, Ting-Yueh,Chen, I-Chia,Liu, Hsing-Jang,Zhu, Jia-Liang,Tsao, Sheng-Wei
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experimental part
p. 4242 - 4250
(2011/02/25)
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- Preparation of 4-arylcyclopentenes by sequential diallylation of arylaldehydes and ring-closing metathesis
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Allylsilane diallylation of aryl aldehydes followed by ring closure metathesis leads to 4-arylcyclopentenes in good yields. Copyright Taylor & Francis, Inc.
- Durand, Anne-Catherine,Brahmi, Lamia,Lahrech, Mokhtar,Hacini, Salih,Santelli, Maurice
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p. 1825 - 1833
(2007/10/03)
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- Bismuth compounds in organic synthesis. A one-pot synthesis of homoallyl ethers and homoallyl acetates from aldehydes catalyzed by bismuth triflate
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(Chemical Equation Presented) Three one-pot methods for the conversion of aldehydes to homoallyl ethers catalyzed by Bi(OTf)3? xH 2O (1 x 4) have been developed. The one-pot synthesis of homoallyl ethers can be achieved either by
- Anzalone, Peter W.,Baru, Ashvin R.,Danielson, Eric M.,Hayes, Patrick D.,Nguyen, Mai P.,Panico, Ambrose F.,Smith, Russell C.,Mohan, Ram S.
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p. 2091 - 2096
(2007/10/03)
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- Sc(OTf)3, an efficient catalyst for addition of allyltrimethysilane to aldehydes: Chemoselective addition to aldehydes in presence of ketone and in situ acylation (3-component coupling)
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Scandium triflate (2-10 mol%) have been found to be a highly efficient catalyst for the addition of allyltrimethylsilane to both activated aromatic and aliphatic aldehydes. However, deactivated (electron rich) aromatic aldehydes gave double allylated products instead. Using a stoichiometric amount of Ac2O in the allylation reaction led directly to homoallylic acetates [in situ acylation catalysed by Sc(OTf)3] and for the first time gave high yields of adducts with moderately electron rich aromatic aldehydes.
- Aggarwal, Varinder K.,Vennall, Graham P.
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p. 1822 - 1826
(2007/10/03)
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- Highly diastereoselective intramolecular allylation reactions of mixed silyl-substituted acetals
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The reaction of preformed mixed acetals derived from (α-hydroxyalkyl)dimethylallylsilane with a number of aromatic and aliphatic aldehydes in the presence of Lewis acids results in a highly diastereoselective intramolecular allylation reaction. The reaction proceeds through a cyclic synclinal SE′ addition of the allylsilane to an intermediate oxocarbenium ion. The reaction occurs exclusively by an intramolecular process as determined by means of a cross-over experiment. The relative stereochemistry was determined by the conversion of one of the allylation products to a known (stereodefined) aldol-type product. A greater degree of diastereoselectivity is obtained by in-situ formation of an oxocarbenium ion from (α-hydroxyhexyl)dimethylallylsilane and an aldehyde in the presence of boron trifluoride etherate. The diastereoselectivity of the in-situ allylation reaction typically exceeds 100:1 in favor of the syn adduct. However, reactions with electron rich aryl aldehydes resulted in a diminished degree of diastereoselectivity. The initial product of the in-situ reaction is an unstable silyl fluoride which is readily hydrolyzed to a silanol derivative upon reaction with methanolic potassium hydroxide. The overall yield of the two-step process is greater than 80%. A method for the synthesis of more highly substituted (α-alkoxyalkyl)dimethylallylsilanes by allyl anion displacement of methoxide from silicon is also described. The methyl siloxane derivatives were obtained by ozonolytic cleavage of an unsubstituted allyl group in methanol.
- Linderman, Russell J.,Chen, Kangyi
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p. 2441 - 2453
(2007/10/03)
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- Kinetics of the reactions of carboxonium ions and aldehyde boron trihalide complexes with alkenes and allylsilanes
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Second order rate constants for the reactions of carboxonium ions Ar(MeO)CH+ and aldehyde-boron trihalide complexes ArCH=O→BX3 with allylsilanes and alkenes have been determined in CH2Cl2 solution. The relative reactivities of these electrophiles are almost independent of the nature of the π-nucleophiles, and it is possible to give an averaged reactivity order. For the electrophiles PhCH=O→BF3, PhCH=O→BCl3, Ph(p-MeOC6H4)CH+, and Ph(MeO)CH+, i.e., for PhCHX+ with X = F3BO-, Cl3BO-, p-MeOC6H4, MeO relative averaged reactivities of 1 : 5 × 102 : 1 × 104 : 4 ×105 (CH2Cl2, -70 °C) are determined indicating that the electrophilicities of aldehydeBHal3 complexes are only 3-6 orders of magnitude smaller than those of the corresponding carboxonium ions. The α-methoxy substituted benzyl cations Ar(MeO)CH+ are 3-16 times more reactive (CH2Cl2, 20 °C) than their phenylogous benzhydryl analogues Ar(P-MeOC6H4)CH+.
- Mayr, Herbert,Gorath, Gorden
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p. 7862 - 7867
(2007/10/02)
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- BARBIER-TYPE ALLYLATION OF ACETALS WITH ALLYL BROMIDE IN A Pb/Al BIMETAL REDOX SYSTEM
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A novel mono and/or double allylation of acetals is achieved by the action of allyl bromide, aluminium metal, and a catalytic amount of PbBr2 and AlBr3 in tetrahydrofuran.
- Tanaka,Hideo,Yamashita, Shiro,Ikemoto, Youichi,Torii, Sigeru
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p. 1721 - 1724
(2007/10/02)
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