- Bis(pertrifluoromethylcatecholato)silane: Extreme Lewis Acidity Broadens the Catalytic Portfolio of Silicon
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Given its earth abundance, silicon is ideal for constructing Lewis acids of use in catalysis or materials science. Neutral silanes were limited to moderate Lewis acidity, until halogenated catecholato ligands provoked a significant boost. However, catalytic applications of bis(perhalocatecholato)silanes were suffering from very poor solubility and unknown deactivation pathways. In this work, the novel per(trifluoromethyl)catechol, H2catCF3, and adducts of its silicon complex Si(catCF3)2 (1) are described. According to the computed fluoride ion affinity, 1 ranks among the strongest neutral Lewis acids currently accessible in the condensed phase. The improved robustness and affinity of 1 enable deoxygenations of aldehydes, ketones, amides, or phosphine oxides, and a carbonyl-olefin metathesis. All those transformations have never been catalyzed by a neutral silane. Attempts to obtain donor-free 1 attest to the extreme Lewis acidity by stabilizing adducts with even the weakest donors, such as benzophenone or hexaethyl disiloxane.
- Thorwart, Thadd?us,Roth, Daniel,Greb, Lutz
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supporting information
p. 10422 - 10427
(2021/05/27)
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- Method for synthesizing ether by catalyzing alcohol through trimethyl halosilane
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The invention discloses a method for synthesizing ether by catalyzing alcohol through trimethyl halosilane. According to the method, under the conditions of air or nitrogen atmosphere, no solvent andno transition metal catalyst, an alcohol compound is directly used as a raw material, trimethyl halosilane is used as a catalyst, and symmetric or asymmetric ether is synthesized through one-step selective dehydration reaction. According to the method, the use of strong acid, strong base and organic primary halides with high toxicity, instability and higher price is avoided, the synthesis steps are shortened, the synthesis efficiency is improved, the reaction has good selectivity, and a target ether product can be obtained preferentially.
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Paragraph 0043-0046
(2020/12/29)
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- Aryl Boronic Acid Catalysed Dehydrative Substitution of Benzylic Alcohols for C?O Bond Formation
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A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C?O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the aryl boronic acid and oxalic acid.
- Estopi?á-Durán, Susana,Donnelly, Liam J.,Mclean, Euan B.,Hockin, Bryony M.,Slawin, Alexandra M. Z.,Taylor, James E.
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p. 3950 - 3956
(2019/02/16)
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- Silver/NBS-Catalyzed Synthesis of α-Alkylated Aryl Ketones from Internal Alkynes and Benzyl Alcohols via Ether Intermediates
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The silver hexafluoroantimonate/N-bromosuccinimide (NBS)-catalyzed synthesis of α-alkylated aryl ketones with a tertiary carbon center from internal alkynes and benzyl alcohols is reported. This reaction proceeds via the etherification of benzyl alcohols with an in situ generated benzyl bromide, formed by the reaction of benzyl alcohol with a catalytic amount of NBS and AgSbF6. Ag-catalyzed C-O cleavage of the ether leads to a tolyl radical, which undergoes addition to the alkyne, ultimately leading to the α-alkylated aryl ketone products.
- Chun, Supill,Chung, Young Keun
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supporting information
p. 5583 - 5586
(2018/09/21)
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- Efficient carbon-supported heterogeneous molybdenum-dioxo catalyst for chemoselective reductive carbonyl coupling
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Reductive coupling of various carbonyl compounds to the corresponding symmetric ethers with dimethylphenylsilane is reported using a carbon-supported dioxo-molybdenum catalyst. The catalyst is air- and moisture-stable and can be easily separated from the reaction mixture for recycling. In addition, the catalyst is chemoselective, thus enabling the synthesis of functionalized ethers without requiring sacrificial ligands or protecting groups.
- Liu, Shengsi,Li, Jiaqi,Jurca, Titel,Stair, Peter C.,Lohr, Tracy L.,Marks, Tobin J.
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p. 2165 - 2169
(2017/07/22)
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- Synthesis of ethers from carbonyl compounds by reductive etherification catalyzed by iron(III) and silyl chloride
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A simple iron- and silyl chloride catalyzed method for the preparation of symmetrical and nonsymmetrical ethers is presented. Various aldehydes and ketones were reductively etherified by using triethylsilane as a reducing agent in the presence of 2 mol% of iron(III) oxo acetate and 8 mol% of chloro(trimethyl)silane. The reactions can be carried out at ambient temperatures and pressures with ethyl acetate as the solvent.
- Savela, Risto,Leino, Reko
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p. 1749 - 1760
(2015/06/16)
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- Organohalide-catalyzed dehydrative O-alkylation between alcohols: A facile etherification method for aliphatic ether synthesis
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Organohalides are found to be effective catalysts for dehydrative O-alkylation reactions between alcohols, providing selective, practical, green, and easily scalable homo- and cross-etherification methods for the preparation of useful symmetrical and unsymmetrical aliphatic ethers from the readily available alcohols. Mechanistic studies revealed that organohalides are regenerated as reactive intermediates and recycled to catalyze the reactions.
- Xu, Qing,Xie, Huamei,Chen, Pingliang,Yu, Lei,Chen, Jianhui,Hu, Xingen
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supporting information
p. 2774 - 2779
(2015/05/27)
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- Reductive coupling reaction of aldehydes using indium(III) triflate as the catalyst
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A reductive coupling reaction was effectively developed to convert an aldehyde to its symmetrical ether. The successful reactions required Et 3SiH and CH2Cl2 as the suitable solvent in the presence of a catalytic amount of In(OTf)3. Various aldehydes were subjected to the method, and each afforded the expected ethers in good to excellent yields.
- Mineno, Tomoko,Tsukagoshi, Rie,Iijima, Tsubasa,Watanabe, Kazuki,Miyashita, Hiroyuki,Yoshimitsu, Hitoshi
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p. 3765 - 3767
(2014/07/07)
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- Influence of lewis acid and solvent in the hydrosiylation of aldehydes and ketones with Et3SiH; Tris(pentafluorophenyl)borane B(C 6F5)3 versus Metal inflates [M(OTf) 3; M = Sc, Bi, Ga, and Al] - Mecha
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The scope of the B(C6F5)3-catalyzed hydrosilylation of (X)Ph- CH=O and (X)Ph-C(R)=O was expanded to include a large set of subslitulents (X =H, p-Me, o-Me, p-F, o-F, p-Cl, p-Br, p-NO2m, m-NO2, p-Et; R
- Bach, Peter,Albright, Andrea,Laali, Kenneth K.
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scheme or table
p. 1961 - 1966
(2009/09/06)
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- One-step reductive etherification of 4-[18F]fluoro-benzaldehyde with decaborane
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Reductive coupling reactions between 4-[18F]fluoro-benzaldehyde ([18F]1) and different alcohols by use of decaborane (B 10H14) as reducing agent have the potential to synthesize 4-[18F]fluoro-benzylet
- Funke, Uta,Jia, Hongmei,Fischer, Steffen,Scheunemann, Matthias,Steinbach, Joerg
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p. 745 - 755
(2007/10/03)
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- Reactions of Thianthrene Cation Radical with Acyclic and Cyclic Alcohols
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Thianthrene cation radical perchlorate (Th(.+)*ClO4(-)) reacted readily with cycloalkanols (C5, C7, C8, and C12), alkan-2-ols (C3, C5, C6, and C8), 3-hexanol, neopentyl alcohol, a number of benzyl alcohols, dl- and (S)-1-phenylethanol, cyclopentyl- and cyclohexylmethanols, the exo- and endo-borneols, and norborneols.Reactions were carried out with an excess of the alcohol in acetonitrile solution containing 2,6-di-tert-butyl-4-methylpyridine.Products were alkenes, ethers, and N-substituted acetamides, depending on the structure of the alcohol.Thianthrene (Th) and its 5-oxide (ThO) were formed in equal amounts.The sum of amounts of products from the alcohol was equal to the amount of ThO.All reactions are interpretable on the basis of the ultimate formation and further reactions of a 5-alkoxythianthreniumyl ion (ROTh(+)).The predominant formation of nortricyclene from the norborneols is striking and is discussed.Swern-Moffatt-type oxidations of the alcohols were not observed.
- Shine, Henry J.,Yueh, Wang
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p. 3553 - 3559
(2007/10/02)
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- Metal Complex and Phase Transfer Catalysed Nitric Oxide Reactions
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Benzyl bromides are converted into oxime ethers by bubbling nitric oxide through a solution of the bromide in t-pentyl alcohol-3 M aqueous sodium hydroxide containing a palladium or ruthenium complex as catalyst and a quaternary ammonium salt as phase transfer agent; this provides the first example of a catalytic reaction of halides which involves free or co-ordinated nitric oxide and is also the first report of a phase transfer reaction utilizing nitric oxide as a reactant.
- Falicky, Slavomir,Alper, Howard
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p. 1039 - 1041
(2007/10/02)
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