- Enabling the Use of Alkyl Thianthrenium Salts in Cross-Coupling Reactions by Copper Catalysis
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Alkyl groups are one of the most widely used groups in organic synthesis. Here, a a series of thianthrenium salts have been synthesized that act as reliable alkylation reagents and readily engage in copper-catalyzed Sonogashira reactions to build C(sp3)?C(sp) bonds under mild photochemical conditions. Diverse alkyl thianthrenium salts, including methyl and disubstituted thianthrenium salts, are employed with great functional breadth, since sensitive Cl, Br, and I atoms, which are poorly tolerated in conventional approaches, are compatible. The generality of the developed alkyl reagents has also been demonstrated in copper-catalyzed Kumada reactions.
- Chen, Cheng,Lu, Hongjian,Shi, Zhuangzhi,Wang, Minyan,Zhao, Binlin
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p. 21756 - 21760
(2021/08/30)
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- Zirconium-catalysed direct substitution of alcohols: enhancing the selectivity by kinetic analysis
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Kinetic analysis was used as a tool for rational optimization of a catalytic, direct substitution of alcohols to enable the selective formation of unsymmetrical ethers, thioethers, and Friedel-Crafts alkylation products using a moisture-tolerant and commercially available zirconium complex (2 to 8 mol%). Operating in air and in the absence of dehydration techniques, the protocol furnished a variety of products in high yields, including glycosylated alcohols and sterically hindered ethers. In addition, the kinetic studies provided mechanistic insight into the network of parallel transformations that take place in the reaction, and helped to elucidate the nature of the operating catalyst.
- Camaj, David,Carlsson, Robin,Dalla-Santa, Oscar,Lill, Malin,Lundberg, Helena,Margarita, Cristiana,Ramstr?m, Anja,Tu?on, Hernando,Villo, Piret
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p. 7420 - 7430
(2021/11/23)
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- Intramolecular activation of imidate with cationic gold(I) catalyst: A new benzylation reaction of alcohols
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Benzylation of alcohols with benzyl (Z)-2,2,2-trifluoro-N-(2-alkynylphenyl)acetimidates 5a-f in the presence of a cationic gold(I) catalyst was investigated. Reagent 5f was the most effective, affording benzyl ethers in good yields. Our results indicate that these gold(I)-activated imidates are effective leaving groups.
- Ban, Shintaro,Endo, Tomotake,Matsui, Rikako,Morita, Nobuyoshi,Hashimoto, Yoshimitsu,Tanaka, Kosaku,Tamura, Osamu
-
-
- Hydrogenation reaction method
-
The invention relates to a hydrogenation reaction method, and belongs to the technical field of organic synthesis. The hydrogenation reaction method provided by the invention comprises the following steps: carrying out a hydrogen transfer reaction on a hydrogen acceptor compound, pinacol borane and a catalyst in a solvent in the presence of proton hydrogen, so that the hydrogen acceptor compound is subjected to a hydrogenation reaction; the catalyst is one or more than two of a palladium catalyst, an iridium catalyst and a rhodium catalyst; the hydrogen acceptor compound comprises one or morethan two functional groups of carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogentriple bonds and epoxy. The method is mild in reaction condition, easy to operate, high in yield, short in reaction time, wide in substrate application range, suitable for carbon-carbon double bonds,carbon-carbon triple bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, nitrogen-nitrogen double bonds, nitryl, carbon-nitrogen triple bonds and epoxy functional groups, good in selectivity and high in reaction specificity.
- -
-
Paragraph 0034; 0177-0180
(2020/05/14)
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- Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration
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A generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene'diphenylmethanimine'benzaldehyde'azobenzene'nitrobenzene'quinoline'acetophenone'benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano-palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti-Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination. (Figure presented.).
- Wang, Yong,Cao, Xinyi,Zhao, Leyao,Pi, Chao,Ji, Jingfei,Cui, Xiuling,Wu, Yangjie
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supporting information
p. 4119 - 4129
(2020/08/10)
-
- p-Methylbenzyl 2,2,2-Trichloroacetimidate: Simple Preparation and Application to Alcohol Protection
-
A method for p-methylbenzyl (MBn) protection of alcohols by using MBn 2,2,2-trichloroacetimidate is described. The trichloroacetimidate can easily be prepared and isolated as a stable white powder without purification by silica gel chromatography. Catalytic use of zinc(II) triflate in diethyl ether activates the trichloroacetimidate to enable MBn protection of various alcohols.
- Arai, Tomoki,Ikeuchi, Kazutada,Murasawa, Kentaro,Yamada, Hidetsohi
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supporting information
p. 1034 - 1037
(2020/09/16)
-
- Superior activity and selectivity of multifunctional catalyst Pd-DTP@ZIF-8 in one pot synthesis of 3-phenyl propyl benzoate
-
The catalytic efficiency of zeolitic imidazolate framework (ZIF-8) has been explored by making it multifunctional. Dual active sites were incorporated such as acid (dodecatungstophosphoric acid, DTP) and metal (Pd°) to prepare 5% Pd-DTP@ZIF-8. DTP was encapsulated inside the cage of ZIF-8 by in-situ and bottle around the ship approach whereas Pd was loaded ex-situ by simple wet impregnation method. The catalytic efficiency was tested for one pot synthesis of 3-phenyl propyl benzoate (3-PPB), a perfumery compound, from cinnamyl alcohol and benzoic anhydride. Trans-esterification of cinnamyl alcohol with benzoic anhydride gives cinnamyl benzoate which on further hydrogenation gives 3-PPB. Three different supports were screened such as ZIF-8, K10 and MCF out of which ZIF-8 showed the maximum activity because of its high surface area and smaller pore diameter. Further Pd, Ni and Cu metals were studied for selective hydrogenation of C[dbnd]C bond among which 5% Pd-DTP@ZIF-8 gave almost 98% conversion of cinnamyl benzoate to 3-PPB with 93% selectivity. Fresh and spent catalysts were characterized by various techniques. 5% Pd-DTP@ZIF-8 showed anti-leaching property with great thermal stability. The turn over frequency and turn over number of the catalyst was observed to be 0.058 s?1 and 835, respectively. A kinetic model was developed with good fit using LHHW mechanism and the activation energy calculated as 17.45 kcal/mol for hydrogenation step. Thus, the reaction was found to be kinetically controlled. The entire process is green.
- Malkar, Radhika S.,Yadav, Ganapati D.
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p. 282 - 293
(2019/04/01)
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- Preparation of Alkyl Ethers with Diallyltriazinedione-Type Alkylating Agents (ATTACKs-R) Under Acid Catalysis
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Diallyltriazinedione-type acid-catalyzed alkylating agents (ATTACKs-R) with 10 different alkyl groups (R), including benzyl, substituted benzyl, allyl, and methyl groups were synthesized. The palladium-catalyzed intramolecular O-to-N allylic rearrangement of 2,4-bis(allyloxy)-6-chloro-1,3,5-triazine was developed to introduce various alkoxy groups into the N,N′-dialkylated triazinedione skeleton. O-Alkylation of alcohols with ATTACKs-R was carried out in 1,4-dioxane in the presence of 2,6-di-tert-butylpyridinium trifluoromethanesulfonate or trifluoromethanesulfonic acid as a catalyst. Six selected ATTACKs-R bearing benzylic R groups were employed to prepare alkyl ethers from primary, secondary, and tertiary alcohols. The reactions of ATTACKs-R bearing an o-nitro-substituted benzyl group tended to afford low yields. Comparison of four different triazinedione-based benzylating reagents suggested that the N,N′-substituents affected the reactivity.
- Fujita, Hikaru,Yamashita, Rina,Fujii, Takanori,Yamada, Kohei,Kitamura, Masanori,Kunishima, Munetaka
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p. 4436 - 4446
(2019/07/03)
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- Specific Inhibition of the Hydrogenolysis of Benzylic C?O Bonds Using Palladium Nanoparticles Supported on Nitrogen-Doped Carbon Nanofibers
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Palladium nanoparticles supported on 5 %-nitrogen-doped, herringbone-type carbon nanofibers (Pd/N-CNF-H), which are prepared by thermally decomposing [Pd2(dba)3?CHCl3] (dba=dibenzylideneacetone) in toluene in the presence of N-CNF-H, were found to be an efficient catalyst for the chemoselective hydrogenation of alkenyl and nitro moieties in benzyl-protected alcohols and carboxylic acid derivatives with high turnover frequencies: the hydrogenation reactions of these functional groups proceeded smoothly even at ambient temperature under atmospheric H2 pressure, and the benzyl protecting groups in the molecules remained intact. Moreover, the recovered Pd/N-CNF-H catalyst could be reused without loss of its catalytic activity or chemoselectivity. The Pd/N-CNF-H catalyst also acted as an effective hydrogenation catalyst for the reduction of aromatic ketones to the corresponding benzyl alcohol derivatives with good to high product selectivity.
- Motoyama, Yukihiro,Morii, Koshi,Ishizuka, Shoya,Inomoto, Sou,Zhang, Zhenzhong,Yoon, Seong-Ho
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p. 505 - 509
(2018/02/15)
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- Cooperation of the Neutral and the Cationic Leaving Group Pathways in Acid-Catalyzed O-Benzylation of TriBOT
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The reaction profile of acid-catalyzed O-benzylation with 2,4,6-tris(benzyloxy)-1,3,5-triazine (TriBOT) was analyzed to study the reaction kinetics. The first-order kinetic constant for the formation of benzyl cation species from N-protonated TriBOT (neutral leaving group pathway) was estimated and compared with that of the model compound for TriBOT. Since rapid consumption of TriBOT in the late stage could not be explained solely by this pathway, cooperation of another reaction mechanism, the cationic leaving group pathway, was proposed to rationalize the rate acceleration.
- Fujita, Hikaru,Hayakawa, Naoko,Kunishima, Munetaka
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p. 10684 - 10687
(2018/07/25)
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- Triazine-Based Cationic Leaving Group: Synergistic Driving Forces for Rapid Formation of Carbocation Species
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A new triazine-based cationic leaving group has been developed for the acid-catalyzed alkylation of O- and C-nucleophiles. There are two synergistic driving forces, namely, stable C=O bond formation and charge-charge repulsive effects, involved in the rapid generation of the carbocation species in the presence of trifluoromethanesulfonic acid (~200 mol %). Considerable rate acceleration of benzylation, allylation, and p-nitrobenzylation was observed as compared to the reactions with less than 100 mol % of the acid catalyst. The triazine-based leaving group showed superior p-nitrobenzylation yield and stability in comparison to common leaving groups, trichloroacetimidate and bromide. A plausible reaction mechanism (the cationic leaving group pathway) was proposed on the basis of mechanistic and kinetic studies, NMR experiments, and calculations.
- Fujita, Hikaru,Kakuyama, Satoshi,Fukuyoshi, Shuichi,Hayakawa, Naoko,Oda, Akifumi,Kunishima, Munetaka
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p. 4568 - 4580
(2018/04/26)
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- Development of triazine-based benzylating reagents possessing T-butyl group on the triazine core: Thermally controllable reagents for the initiation of reaction
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Benzylating reagents, 4-(4,6-di-t-butyl-1,3,5-triazin-2-yl)-4-benzylmorpholinium triflate, and related derivatives have been developed. The reagents release benzyl triflate as a benzyl cation equivalent upon heating the solution to 40°C under neutral conditions. The O-benzylation of alcohols using a stoichiometric amount of these reagents afforded corresponding benzyl ethers in good to high yields. This was due to the presence of a bulky t-butyl group on the triazine ring of these reagents that prevents the consumption of benzyl triflate via a side reaction with a morpholinotriazine derivative.
- Karuo, Yukiko,Yamada, Kohei,Kunishima, Munetaka
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p. 303 - 308
(2018/03/09)
-
- TRIAZINE DIONE COMPOUND
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PROBLEM TO BE SOLVED: To provide a novel triazine dione compound useful as an alkylating agent for a nucleophilic compound. SOLUTION: This invention relates to a compound represented by formula (I) [where each symbol is as defined in the specification] and an alkylating agent comprising the compound, and a method for alkylating a nucleophilic compound using the alkylating agent. SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
- -
-
Paragraph 0119; 0120
(2017/07/11)
-
- N,N′-Dimethylated Benzyloxytriazinedione: A Stable Solid Reagent for Acid-Catalyzed O-Benzylation
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N,N′-Dimethylated 6-(benzyloxy)-1,3,5-triazine-2,4(1H,3H)-dione (DMBOT) has been developed as a triazinedione-based, stable solid reagent for acid-catalyzed O-benzylation. The conceptual basis of the design was to fix the core triazinedione skeleton, and
- Fujita, Hikaru,Kakuyama, Satoshi,Kunishima, Munetaka
-
supporting information
p. 833 - 839
(2017/02/15)
-
- Cobalt-Catalyzed Asymmetric Sequential Hydroboration/Hydrogenation of Internal Alkynes
-
A highly regio- and enantioselective cobalt-catalyzed hydroboration/hydrogenation of internal alkynes with HBpin and a hydrogen balloon in one pot was developed. A new type of chiral imidazoline iminopyridine (IIP) ligand was introduced for the first time in this novel and efficient strategy. This protocol used relatively simple and available starting materials with good functional group tolerance to construct more valuable chiral secondary organoboronates. The primary mechanistic studies illustrated that the cobalt-catalyzed regioselective hydroboration of alkynes did initially occur followed by HBpin-promoted and cobalt-catalyzed enantioselective hydrogenation of alkenylboronates.
- Guo, Jun,Cheng, Biao,Shen, Xuzhong,Lu, Zhan
-
supporting information
p. 15316 - 15319
(2017/11/06)
-
- Tetrahydroxydiboron-Mediated Palladium-Catalyzed Transfer Hydrogenation and Deuteriation of Alkenes and Alkynes Using Water as the Stoichiometric H or D Atom Donor
-
There are few examples of catalytic transfer hydrogenations of simple alkenes and alkynes that use water as a stoichiometric H or D atom donor. We have found that diboron reagents efficiently mediate the transfer of H or D atoms from water directly onto unsaturated C-C bonds using a palladium catalyst. This reaction is conducted on a broad variety of alkenes and alkynes at ambient temperature, and boric acid is the sole byproduct. Mechanistic experiments suggest that this reaction is made possible by a hydrogen atom transfer from water that generates a Pd-hydride intermediate. Importantly, complete deuterium incorporation from stoichiometric D2O has also been achieved.
- Cummings, Steven P.,Le, Thanh-Ngoc,Fernandez, Gilberto E.,Quiambao, Lorenzo G.,Stokes, Benjamin J.
-
supporting information
p. 6107 - 6110
(2016/06/09)
-
- Catalytic Iodination of the Aliphatic C-F Bond by YbI3(THF)3: Mechanistic Insight and Synthetic Utility
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A facile iodination protocol of unactivated alkyl fluorides using catalytic amounts of YbI3(THF)3 in the presence of iodotrimethylsilane as a stoichiometric fluoride trapping agent is presented. 1H NMR spectroscopy demonstrates a two-step catalytic cycle where TMSI regenerates active YbI3(THF)3. Finally, the catalytic reaction is extended into a one-pot procedure to demonstrate a potential application of the method. Overall, the findings present a distinct strategy for C-F bond transformations in the presence of catalytic YbI3(THF)3.
- Janjetovic, Mario,Ekebergh, Andreas,Tr?ff, Annika M.,Hilmersson, G?ran
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p. 2804 - 2807
(2016/07/06)
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- Visible-light-promoted conversion of alkyl benzyl ether to alkyl ester or alcohol via O-α-sp3 C-H cleavage
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A mild and high-yielding visible-light-promoted conversion of alkyl benzyl ethers to the alkyl esters or alkyl alcohols was developed. Mechanistic studies provided evidence for a radical chain reaction involving the homolytic cleavage of O-α-sp3 C-H bonds in the substrate as one of the propagation steps. We propose that α-bromoethers are key intermediates in the transformation.
- Lu, Ping,Hou, Tianyuan,Gu, Xiangyong,Li, Pixu
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supporting information
p. 1954 - 1957
(2015/04/27)
-
- Development of chelate resin-supported palladium catalysts for chemoselective hydrogenation
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Abstract Two kinds of palladium catalysts immobilized on a chelate resin bearing diiminoacetate or polyamine moieties on the polystyrene-divinylbenzene polymer were newly prepared by the adsorption of palladium (II) ions on these resins followed by the reduction to palladium (0) with hydrazine monohydrate. Both catalysts showed a similar activity for hydrogenation. A variety of reducible functionalities, except for benzylic alcohol, alkyl benzyl ether, silyl ether, and epoxide, could be reduced under the hydrogenation conditions using either catalyst. Since the palladium metal elution from the immobilized catalysts was never observed, the catalysts could be reused without any decrease in the catalyst activity for at least 5 runs.
- Monguchi, Yasunari,Ichikawa, Tomohiro,Nozaki, Kei,Kihara, Kensuke,Yamada, Yuuko,Miyake, Yutaka,Sawama, Yoshinari,Sajiki, Hironao
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supporting information
p. 6499 - 6505
(2015/08/18)
-
- Study of the Reactivities of Acid-Catalyzed O-Benzylating Reagents Based on Structural Isomers of 1,3,5-Triazine
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We have demonstrated O-benzylating abilities of both 4,6-bis(benzyloxy)-1,3,5-triazin-2(1H)-one (DiBOT) and 6-(benzyloxy)-1,3,5-triazine-2,4(1H,3H)-dione (MonoBOT), which have been previously suggested as reaction intermediates of the acid-catalyzed benzylation of 2,4,6-tris(benzyloxy)-1,3,5-triazine (TriBOT). We studied the effect on the reactivity of acid-catalyzed O-benzylation caused by the isomeric core triazine structures in these compounds by carrying out a kinetic study and estimating relative basicities using model compounds. Since MonoBOT showed superior reactivity, 1,3,5-triazine-2,4(1H,3H)-dione is a promising core structure for acid-catalyzed alkylating reagents.
- Fujita, Hikaru,Hayakawa, Naoko,Kunishima, Munetaka
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p. 11200 - 11205
(2015/11/18)
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- Development of a new benzylating reagent spontaneously releasing benzyl cation equivalents at room temperature
-
A new O-benzylating reagent, that is, 4-(4,6-diphenoxy-1,3,5-triazin-2-yl)-4-benzylmorpholinium trifluoromethanesulfonate (DPT-BM), has been developed. Benzyl cation equivalents are generated from DPT-BM by dissolving the compound in a solvent at room tem
- Yamada, Kohei,Tsukada, Yuichi,Karuo, Yukiko,Kitamura, Masanori,Kunishima, Munetaka
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p. 12274 - 12278
(2015/03/31)
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- HYDROXY GROUP PROTECTING AGENT AND HYDROXY GROUP PROTECTION METHOD
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To provide: a hydroxy group protecting agent which is stable and easy to use, does not have carcinogenicity, a tearing property or the like, and is inexpensive; and a hydroxy group protection method which enables the protection of a hydroxy group under acidic conditions. [Solution] A hydroxy group protecting agent in which at least one protecting group is bound to a nitrogen-containing electron-withdrawing heterocyclic ring through any one of an oxygen atom, a sulfur atom and a nitrogen atom. The heterocyclic ring is a triazine ring or the like, and the protecting group is a benzyl group or the like. Specifically, the hydroxy group protecting agent is 2,4,6-tribenzyloxy-1,3,5-triazine, 2,4,6-tris(4-methoxybenzyloxy)-1,3,5-triazine or the like. In addition, 2,4,6-tris(t-butoxy)-1,3,5-triazine or the like can also be used. For protecting a hydroxy group, a compound of interest which has a hydroxy group is reacted with the hydroxy group protecting agent under acidic conditions.
- -
-
Paragraph 0036; 0037; 0038; 0039; 0040
(2015/01/07)
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- Oxidation of acyclic alkenes and allyl and benzyl ethers with DIB/t-BuOOH/Mg(OAc)2
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Oxidation of (11Z)-1′,2′-didehydrostemofoline with DIB/TBHP/Mg(OAc)2·4H2O resulted in oxidative cleavage of the C-11-C-12 double bond instead of the desired allylic oxidation of the 1-butenyl side chain. Stemofoline gave a similar result. The oxidation of more simple terminal alkenes was regioselective and gave vinyl ketones while allyl and benzyl ethers gave acrylate and benzoate esters, respectively. Allyl and benzyl ethers could be chemoselectively oxidized in the presence of a terminal alkene or benzyl group. Oxidation of an internal alkene was poorly regioselective, in contrast to the oxidation of 1-substituted cyclohexenes.
- Sastraruji, Thanapat,Pyne, Stephen G.,Ung, Alison T.
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body text
p. 598 - 602
(2012/01/05)
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- A novel acid-catalyzed O-benzylating reagent with the smallest unit of imidate structure
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Formal trimerization of the smallest unit of benzyl imidate leads to 2,4,6-tris(benzyloxy)-1,3,5-triazine (TriBOT), which can be used as an acid-catalyzed O-benzylating reagent. The reaction of various functionalized alcohols with 0.4 equiv of TriBOT in the presence of trifluoromethanesulfonic acid afforded the benzyl ethers in good yields. TriBOT is an inexpensive stable crystalline solid with high atom economy.
- Yamada, Kohei,Fujita, Hikaru,Kunishima, Munetaka
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p. 5026 - 5029,4
(2012/12/12)
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- A novel acid-catalyzed O-benzylating reagent with the smallest unit of imidate structure
-
Formal trimerization of the smallest unit of benzyl imidate leads to 2,4,6-tris(benzyloxy)-1,3,5-triazine (TriBOT), which can be used as an acid-catalyzed O-benzylating reagent. The reaction of various functionalized alcohols with 0.4 equiv of TriBOT in the presence of trifluoromethanesulfonic acid afforded the benzyl ethers in good yields. TriBOT is an inexpensive stable crystalline solid with high atom economy.
- Yamada, Kohei,Fujita, Hikaru,Kunishima, Munetaka
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p. 5026 - 5029
(2013/01/15)
-
- Palladium-supported ionic liquid catalyst (Pd-SH-SILC) immobilized on mercaptopropyl silica gel as a chemoselective, reusable and heterogeneous catalyst for catalytic hydrogenation
-
Palladium acetate was immobilized as Pd-SH-SILC (Pd-supported ionic liquid catalyst) in the pores of amorphous mercaptopropyl silica gel with the aid of an ionic liquid [bmim]BF4. The heterogeneous Pd-SH-SILC was effective for catalytic hydrogenation of a variety of olefins at atmospheric pressure and room temperature. It withstood recycling up to 10 times by decantation.
- Hagiwara, Hisahiro,Nakamura, Tomomi,Hoshi, Takashi,Suzuki, Toshio
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scheme or table
p. 1133 - 1137
(2011/06/26)
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- Simple one-pot synthesis of Rh-Fe3O4 heterodimer nanocrystals and their applications to a magnetically recyclable catalyst for efficient and selective reduction of nitroarenes and alkenes
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A simple synthesis of Rh-Fe3O4 heterodimer nanocrystals was achieved by controlled one-pot thermolysis. The nanocrystals exhibited excellent activities for the selective reduction of nitroarenes and alkenes. Furthermore the nanocrystal catalyst could be easily separated by a magnet, and recycled eight times without losing the catalytic activity.
- Jang, Youngjin,Kim, Seyoung,Jun, Samuel Woojoo,Kim, Byung Hyo,Hwang, Sunhwan,Song, In Kyu,Kim, B. Moon,Hyeon, Taeghwan
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supporting information; experimental part
p. 3601 - 3603
(2011/04/26)
-
- A useful, reliable and safer protocol for hydrogenation and the hydrogenolysis of o-benzyl groups: The in situ preparation of an active Pd 0/C catalyst with well-defined properties
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A simple, highly reproducible protocol for the hydrogenation of alkenes and alkynes and for the hydrogenolysis of O-benzyl ethers has been developed. The method features the in situ preparation of an active Pd0/C catalyst from Pd(OAc)2 and charcoal, in methanol. The mild reaction conditions (25°C) and low catalyst loading required (0.025 mol%), as well as the absence of contamination of the product by palladium residues (0/C: It's a kind of magic! A sustainable, simple and highly reproducible protocol for the hydrogenation of alkenes and alkynes (see scheme) and for the hydrogenolysis of O-benzyl ethers has been developed with an in situ generated Pd0/C catalyst. The homemade Pd0/C catalyst allows mild reaction conditions (25°C, 1 atm H2) and low catalyst loading (as low as 0.025 mol%), without any contamination of the product by palladium residues (4 ppb).
- Felpin, Francois-Xavier,Fouquet, Eric
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supporting information; experimental part
p. 12440 - 12445
(2011/01/05)
-
- Pd-MCM-48: A novel recyclable heterogeneous catalyst for chemo- and regioselective hydrogenation of olefins and coupling reactions
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A novel, heterogeneous Pd-MCM-48 catalyst has been developed by encapsulating palladium nanoparticles into the cubic phase of mesoporous MCM-48 matrix at room temperature. The catalyst demonstrated excellent chemo- and regioselectivity for the hydrogenation of olefins at room temperature within 30-80 min. The turnover frequency for the hydrogenation is very high (4400 h-1). Interestingly, selectivity of the catalyst was significantly influenced by the mode of addition of palladium precursor. Moreover, the catalyst was also very effective for the coupling reactions with the formation of carbon-carbon and carbon-nitrogen bonds under ligand-free and aerobic conditions.
- Banerjee, Subhash,Balasanthiran, Vagulejan,Koodali, Ranjit T.,Sereda, Grigoriy A.
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scheme or table
p. 4316 - 4321
(2010/11/04)
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- Compounds and methods of arylmethylation (benzylation) as protection for alcohol groups during chemical synthesis
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A process for benzylating an alcohol includes mixing 2-benzyloxy-1-methylpyridinium triflate in an aromatic hydrocarbon solvent having a predetermined boiling point; adding an acid scavenger to the mixture; combining the alcohol to be benzylated with the mixture; reacting the alcohol with the 2-benzyloxy-1-methylpyridinium triflate by heating above ambient temperature to generate the benzylated alcohol; and separating the benzylated alcohol from the mixture.
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Page/Page column 8; 11-12
(2010/07/14)
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- Efficient and convenient heterogeneous palladium-catalyzed regioselective deuteration at the benzylic position
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The Pd/C-catalyzed efficient and regioselective hydrogen-deuterium (H-D) exchange reaction on the benzylic site proceeded in D2O in the presence of a small amount of H2 gas. The use of the Pd/C-ethylenediamine complex [Pd/C(en)] as a catalyst instead of Pd/C led to the efficient deuterium incorporation into the benzylic site of Obenzyl protective groups without hydrogenolysis. These H-D exchange reactions provide a post synthetic and D2-gas-free deuterium-labeling method on a wide variety of benzylic sites using D2O as the deuterium source and heterogeneous Pd/C or Pd/C(en) as a reusable heterogeneous palladium catalyst under mild and neutral conditions.
- Kurita, Takanori,Hattori, Kazuyuki,Seki, Saori,Mizumoto, Takuto,Aoki, Fumiyo,Yamada, Yuki,Ikawa, Kanoko,Maegawa, Tomohiro,Monguchi, Yasunari,Sajiki, Hironao
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p. 664 - 673
(2008/12/21)
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- A one-pot tandem oxidation-reduction protocol for the synthesis of cyclic ethers from their diols
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A novel and an efficient one-pot cyclization method for the preparation of cyclic ethers from their diols via a tandem oxidation-reduction protocol using a cocktail of MnO2/Et3SiH/CF3COOH is reported.
- Panda, Biswajit,Sarkar, Tarun K.
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scheme or table
p. 6701 - 6703
(2009/04/07)
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- Palladium nanoparticles-catalyzed chemoselective hydrogenations, a recyclable system in water
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Chemoselective hydrogenation of double bonds in the presence of various functional groups occurred in high yields using water or toluene as solvent, and Pd nanoparticles as catalyst. Up to nine recyclings were achieved in water without decrease of the catalyst activity.
- Callis, Nuria Miro,Thiery, Emilie,Le Bras, Jean,Muzart, Jacques
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p. 8128 - 8131
(2008/03/13)
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- Facile cleavage of ethers in ionic liquid
-
Various alkyl ethers were efficiently cleaved by treating them with pyridinium halides in ionic liquid, and the desired products were obtained in excellent yields.
- Cheng, Lili,Aw, Carlin,Ong, Siew Siang,Lu, Yixin
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supporting information; experimental part
p. 2008 - 2010
(2009/08/14)
-
- Iron(III) chloride-catalyzed reductive etherification of carbonyl compounds with alcohols
-
A facile reductive etherification of carbonyl compounds can be performed by the reaction with alcohols and triethylsilane catalyzed by iron(III) chloride. The corresponding alkyl ethers are obtained in good to excellent yields under mild reaction conditions. Copyright
- Iwanami, Katsuyuki,Yano, Kentaro,Oriyama, Takeshi
-
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- Mix-and-heat benzylation of alcohols using a bench-stable pyridinium salt
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2-Benzyloxy-1-methylpyridinium inflate (1) is a stable, neutral organic salt that converts alcohols into benzyl ethers upon warming. The synthesis and reactivity of 1 are described herein. Benzylation of a wide range of alcohols occurs in good to excellent yield.
- Poon, Kevin W. C.,Dudley, Gregory B.
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p. 3923 - 3927
(2007/10/03)
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- Practical access to the polymer incarcerated platinum (PI Pt) catalyst and its application to hydrogenation
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Polymer incarcerated platinum catalysts (PI Pt) were conveniently prepared from PtCl2(COD) or H2PtCl6·6H 2O and styrene copolymers via reduction of the Pt sources with triethylamine, coacervation, and cross-linking. The Pt catalysts have been successfully applied to catalytic hydrogenation including saturation of heterocyclic compounds. The Royal Society of Chemistry 2006.
- Miyazaki, Yoji,Hagio, Hiroyuki,Kobayashi, Sh
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p. 2529 - 2531
(2008/02/07)
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- A bench-stable organic salt for the benzylation of alcohols
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2-Benzyloxy-1-methylpyridinium inflate (Bn-OPT) effects the benzylation of alcohols in the absence of acidic or basic promoters. Solutions of Bn-OPT and primary, secondary, or tertiary alcohols give rise to the corresponding benzyl ethers upon mild heating. Acid scavengers are generally included in the reaction mixture. Bn-OPT is crystalline and bench-stable. Georg Thieme Verlag Stuttgart.
- Poon, Kevin W. C.,House, Sarah E.,Dudley, Gregory B.
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p. 3142 - 3144
(2007/10/03)
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- An efficient and convenient method for the direct conversion of alkyl silyl ethers into the corresponding alkyl ethers catalyzed by iron(III) chloride
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Various alcohol silyl ethers were readily and efficiently transformed into the corresponding alkyl ethers in high yields by the use of aldehydes combined with triethylsilane in the presence of a catalytic amount of iron(III) chloride. Georg Thieme Verlag Stuttgart.
- Iwanami, Katsuyuki,Yano, Kentaro,Oriyama, Takeshi
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p. 2669 - 2672
(2007/10/03)
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- A highly efficient method for the reductive etherification of carbonyl compounds with triethylsilane and alkoxytrimethylsilane catalyzed by iron(III) chloride
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Facile reductive etherification of carbonyl compounds can be conveniently performed by reaction with triethylsilane and alkoxytrimethylsilane catalyzed by iron(III) chloride. The corresponding alkyl ethers, including benzyl and allyl ethers, of the reduced alcohols were obtained in good to excellent yields under mild reaction conditions.
- Iwanami, Katsuyuki,Seo, Hana,Tobita, Yuki,Oriyama, Takeshi
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p. 183 - 186
(2007/10/03)
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- Hydrogenation reactions using scCO2 as a solvent in microchannel reactors
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We have developed an effective microfluidic system for hydrogenation reactions in ScCO2; the reactions proceeded very rapidly (within 1 second), by making the best use of ScCO2 and utilizing the large specific interfacial area of the microchannel reactor, and high reaction productivity was attained in each channel. The Royal Society of Chemistry 2005.
- Kobayashi, Juta,Mori, Yuichiro,Kobayashi, Shu
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p. 2567 - 2568
(2007/10/03)
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- Immobilization of a platinum catalyst using the polymer incarcerated (PI) method and application to catalytic reactions
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Immobilization of a platinum catalyst was carried out on the basis of the polymer incarcerated (PI) method. The PI platinum catalyst thus prepared showed high activity in hydrosilylation, and recovery and reuse of the catalyst were attained without loss of activity. Application of this catalyst to hydrogenation is also reported.
- Hagio, Hiroyuki,Sugiura, Masaharu,Kobayashi, Shu
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p. 813 - 816
(2007/10/03)
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- Palladium nanoparticles obtained from palladium salts and tributylamine in molten tetrabutylammonium bromide: Their use for hydrogenolysis-free hydrogenation of olefins
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Carbon-carbon double bonds have been selectively hydrogenated at room temperature in the presence of benzyloxy groups using an atmospheric pressure of hydrogen, toluene or [bmim]PF6 as the solvent and palladium nanoparticles stabilized with tetrabutylammonium bromide. The system [bmim]PF6/palladium nanoparticles can be recycled without noticeable decrease of activity.
- Le Bras, Jean,Mukherjee, Deb Kumar,Gonzalez, Sara,Tristany, Mar,Ganchegui, Benjamin,Moreno-Manas, Marcial,Pleixats, Roser,Henin, Francoise,Muzart, Jacques
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p. 1550 - 1553
(2007/10/03)
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- Reductive etherification of carbonyl compounds with alkyl trimethylsilylethers using polymethylhydrosiloxane (PMHS) and catalytic B(C 6F5)3
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A facile synthesis of symmetrical and unsymmetrical ethers is achieved by reductive coupling of carbonyl compounds with alkoxysilanes. This reaction is performed using inert polymethylhydrosiloxane as the hydride source and B(C 6F5)
- Chandrasekhar,Chandrashekar,Nagendra Babu,Vijeender,Venkatram Reddy
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p. 5497 - 5499
(2007/10/03)
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- Regioselectivity of the ring opening in the reaction of phenyloxirane, (phenylmethyl)oxirane and (2-phenylethyl)oxirane with K-, K+(15-crown-5)2
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The electron from potassium anion of K-, K+ (15-crown-5)2 (1) is initially transferred to the aromatic ring of phenyloxirane and (phenylmethyl)oxirane. The oxirane ring is then opened exclusively in the α-position. Two dimeric products, i.e. dipotassium 2,3-diphenylbutane-1,4-dioxide and dipotassium 1,3-diphenylbutane-1,4-dioxide are formed in the case of phenyloxirane. A mixture of several potassium alkoxides involving 3-phenylpropoxide, 3-phenylallyloxide, tetraethylene glycoxide vinyl ether, and appropriate alcohols, i.e. 3-phenyl-1-propanol, 3-phenylallyl alcohol, and tetraethylene glycol vinyl ether, is obtained in the reaction of 1 with (phenylmethyl)oxirane. However, introduction of the second CH2 group into the substituent results in the β-opening of the oxirane ring in (2-phenylethyl)oxirane. Potassium 4-phenylbutane-2-oxide, and potassium tetraethylene glycoxide vinyl ether are the main reaction products in this case. Organometallic intermediates take part in all these processes.
- Grobelny, Zbigniew,Stolarzewicz, Andrzej,Morejko-Buz, Barbara,Maercker, Adalbert,Krompiec, Stanis?aw,Bieg, Tadeusz
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- Bismuth trichloride catalyzed efficient reductive etherification of carbonyl compounds with alcohols: A novel method for preparation of symmetrical and unsymmetrical ethers
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The reductive homocoupling of a carbonyl compound and heterocoupling of a carbonyl compound with a non-protected alcohol were both effected smoothly at room temperature with triethylsilane in the presence of a catalytic amount of bismuth trichloride to afford the corresponding ethers in good yields.
- Wada, Makoto,Nagayama, Sonoe,Mizutani, Kaori,Hiroi, Ryoichi,Miyoshi, Norikazu
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p. 248 - 249
(2007/10/03)
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- Lewis acid-catalyzed reductive etherification of carbonyl compounds with alkoxyhydrosilanes
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The TMSI-catalyzed reaction of aldehydes and ketones with alkoxydimethylsilanes gave unsymmetrical ethers in good to high yields. This reductive etherification is superior to the conventional method using two kinds of silicon reagents in terms of atom eff
- Miura, Katsukiyo,Ootsuka, Kazunori,Suda, Shuntaro,Nishikori, Hisashi,Hosomi, Akira
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p. 313 - 315
(2007/10/03)
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- New reactivity of a reducing reagent generated from a copper(I) salt and a hydrosilane: Selective reduction of ketones and olefins conjugated with an aromatic group
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Aromatic ketones and olefins were selectively converted to the corresponding alcohols and alkanes by a reagent prepared from a copper(I) salt and a hydrosilane. Excess use of the hydrosilane is most important to attain the high reactivities. One-electron transfer process as well as nucleophilic reaction of hydride would contribute to the selectivity.
- Ito, Hajime,Yamanaka, Hiroshi,Ishizuka, Tomoko,Tateiwa, Jun-Ichi,Hosomi, Akira
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p. 479 - 482
(2007/10/03)
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