- Functionalization at Will of Rim-Differentiated Pillar[5]arenes
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The development of an efficient synthetic route toward rim-differentiated C5-symmetric pillar[5]arenes (P[5]s), whose two rims are decorated with different chemical functionalities, opens up successive transformations of this macrocyclic scaffo
- Demay-Drouhard, Paul,Du, Ke,Samanta, Kushal,Wan, Xintong,Yang, Weiwei,Srinivasan, Rajavel,Sue, Andrew C.-H.,Zuilhof, Han
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- Synthesis of Bidentate Nitrogen Ligands by Rh-Catalyzed C-H Annulation and Their Application to Pd-Catalyzed Aerobic C-H Alkenylation
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A new class of bidentate ligands was prepared by a modular approach involving Rh-catalyzed C-H annulation reactions. The resulting conformationally constrained ligands enabled the Pd-catalyzed C-H alkenylation at electron-rich and sterically less hindered positions of electron-rich arenes while promoting the facile oxidation of Pd(0) intermediates by oxygen. This newly introduced ligand class is complementary to the ligands developed for Pd-catalyzed oxidative reactions and may find broad application in transition-metal-catalyzed reactions.
- Kim, Hyun Tae,Kang, Eunsu,Kim, Minkyu,Joo, Jung Min
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supporting information
p. 3657 - 3662
(2021/05/10)
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- Silicon-Free SuFEx Reactions of Sulfonimidoyl Fluorides: Scope, Enantioselectivity, and Mechanism
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SuFEx reactions, in which an S?F moiety reacts with a silyl-protected phenol, have been developed as powerful click reactions. In the current paper we open up the potential of SuFEx reactions as enantioselective reactions, analyze the role of Si and outline the mechanism of this reaction. As a result, fast, high-yielding, “Si-free” and enantiospecific SuFEx reactions of sulfonimidoyl fluorides have been developed, and their mechanism shown, by both experimental and theoretical methods, to yield chiral products.
- Baggerman, Jacob,Jordaan, Daan,Liang, Dong-Dong,Streefkerk, Dieuwertje E.,Wagemakers, Jorden,Zuilhof, Han
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supporting information
p. 7494 - 7500
(2020/03/23)
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- Ligand-Promoted Non-Directed C?H Cyanation of Arenes
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This article reports the first example of a 2-pyridone accelerated non-directed C?H cyanation with an arene as the limiting reagent. This protocol is compatible with a broad scope of arenes, including advanced intermediates, drug molecules, and natural products. A kinetic isotope experiment (kH/kD=4.40) indicates that the C?H bond cleavage is the rate-limiting step. Also, the reaction is readily scalable, further showcasing the synthetic utility of this method.
- Liu, Luo-Yan,Yeung, Kap-Sun,Yu, Jin-Quan
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supporting information
p. 2199 - 2202
(2019/01/24)
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- H-D Exchange Deuteration of Arenes at Room Temperature
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Arene nuclei efficiently underwent the hydrogen (H)-deuterium (D) exchange reaction catalyzed by platinum group metals on carbon in a mixed solvent of 2-propanol and D2O at room temperature to produce deuterium-labeled arenes. Platinum on carbon (Pt/C) and iridium on carbon (Ir/C) were applicable catalysts, and the various arenes bearing a carbonyl group, fluorine, phenolic hydroxy group, amino group, or phosphonic acid on the aromatic nucleus were effectively deuterated. Nonheating conditions are valuable for the scalable industrial preparation.
- Sawama, Yoshinari,Nakano, Akihiro,Matsuda, Takumi,Kawajiri, Takahiro,Yamada, Tsuyoshi,Sajiki, Hironao
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supporting information
p. 648 - 653
(2019/02/14)
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- A general copper-based photoredox catalyst for organic synthesis: Scope, application in natural product synthesis and mechanistic insights
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Organic transformations can broadly be classified into four categories including cationic, anionic, pericyclic and radical reactions. While the last category has been known for decades to provide remarkably efficient synthetic pathways, it has long been hampered by the need for toxic reagents, which considerably limited its impact on chemical synthesis. This situation has come to an end with the introduction of new concepts for the generation of radical species, photoredox catalysis – which simply relies on the use of a catalyst that can be activated upon visible light irradiation – certainly being the most efficient one. The state-of-the-art catalysts mostly rely on the use of ruthenium and iridium complexes and organic dyes, which still considerably limits their broad implementation in chemical processes: alternative readily available catalysts based on inexpensive, environmentally benign base metals are therefore strongly needed. Furthermore, expanding the toolbox of methods based on photoredox catalysis will facilitate the discovery of new light-mediated transformations. This article details the use of a simple copper complex which, upon activation with blue light, can initiate a broad range of radical reactions.
- Deldaele, Christopher,Michelet, Bastien,Baguia, Hajar,Kajouj, Sofia,Romero, Eugenie,Moucheron, Cecile,Evano, Gwilherm
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p. 621 - 629
(2018/10/04)
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- Mild synthesis of silyl ethers: Via potassium carbonate catalyzed reactions between alcohols and hydrosilanes
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A method has been developed for the silanolysis of alcohols using an abundant and non-corrosive base K2CO3 as a catalyst. Reactions between a variety of alcohols and hydrosilanes generate silyl ethers under mild conditions. The use of hydrosilanes leads to the formation of H2 as the only byproduct thus avoiding the formation of stoichiometric strong acids. The mild conditions lead to a wide scope of possible alcohol substrates and good functional group tolerance. Selective alcohol silanolysis is also observed in the presence of reactive C-H bonds, lending this method for extensive use in protection group chemistry.
- Delucia, Nicholas A.,Das, Nivedita,Vannucci, Aaron K.
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p. 3415 - 3418
(2018/05/23)
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- A General Copper Catalyst for Photoredox Transformations of Organic Halides
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A broadly applicable copper catalyst for photoredox transformations of organic halides is reported. Upon visible light irradiation in the presence of catalytic amounts of [(DPEphos)(bcp)Cu]PF6 and an amine, a range of unactivated aryl and alkyl halides were shown to be smoothly activated through a rare Cu(I)/Cu(I)?/Cu(0) catalytic cycle. This complex efficiently catalyzes a series of radical processes, including reductions, cyclizations, and direct arylation of arenes.
- Michelet, Bastien,Deldaele, Christopher,Kajouj, Sofia,Moucheron, Cécile,Evano, Gwilherm
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supporting information
p. 3576 - 3579
(2017/07/17)
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- Minimal Self-Immolative Probe for Multimodal Fluoride Detection
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Two single-molecule, self-immolative fluoride probes, namely tert-butyldimethylsilyl-protected 2- and 4-difluoromethylphenol, are described. Compared to similar systems previously described, the probes are characterized by a simpler structure and straightforward, two-step preparation. Nevertheless, they allow the detection of fluoride ions at micromolar concentration by the naked eye, UV-vis absorption, and fluorescence. A detailed investigation of the self-immolative reaction reveals that the rate-limiting step is the release of the first fluoride ion from the difluoromethylphenolate intermediate. Moreover, the mutual position of the difluoromethyl- and tert-butyldimethylsilyl-protected residues has a relevant effect on the reactivity. Likely, a CF2H-O hydrogen bond in the 2-isomer increases the reactivity of the silyl ether toward hydrolytic cleavage but also stabilizes the phenolate intermediate, slowing the release of fluoride ions.
- Gabrielli, Luca,Mancin, Fabrizio
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p. 10715 - 10720
(2016/11/29)
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- The Hexachlorocerate(III) Anion: A Potent, Benchtop Stable, and Readily Available Ultraviolet A Photosensitizer for Aryl Chlorides
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The hexachlorocerate(III) anion, [CeIIICl6]3-, was found to be a potent photoreductant in acetonitrile solution with an estimated excited-state reduction potential of - 3.45 V versus Cp2Fe0/+. Despite a short lifetime of 22.1(1) ns, the anion exhibited a photoluminescence quantum yield of 0.61(4) and fast quenching kinetics toward organohalogens allowing for its application in the photocatalytic reduction of aryl chloride substrates.
- Yin, Haolin,Jin, Yi,Hertzog, Jerald E.,Mullane, Kimberly C.,Carroll, Patrick J.,Manor, Brian C.,Anna, Jessica M.,Schelter, Eric J.
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supporting information
p. 16266 - 16273
(2016/12/27)
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- Tert-Butyldimethylsilyl Amine (TBDMS-NH2): A Mild and Green Reagent for the Protection of Benzyl Alcohols, Phenols, and Carboxylic Acids under Solvent-Free Conditions
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Herein, we present the use of the tert-butyldimethylsilyl amine (TBDMS-NH2) as a silylating reagent for phenols, benzyl alcohols, and carboxylic acids. Unlike other silyl protection reactions, this reported process with TBDMS-NH2 does not involve the form
- Duczynski, Jeremy A.,Fuller, Rebecca,Stewart, Scott G.
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p. 1172 - 1179
(2016/10/13)
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- Palladium-Catalyzed Directed para C?H Functionalization of Phenols
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Various practical methods for the selective C?H functionalization of the ortho and recently also of the meta position of an arene have already been developed. Following our recent development of the directing-group-assisted para C?H functionalization of toluene derivatives, we herein report the first remote para C?H functionalization of phenol derivatives by using a recyclable silicon-containing biphenyl-based template. The effectiveness of this strategy was illustrated with different synthetic elaborations and by the synthesis of various phenol-based natural products.
- Patra, Tuhin,Bag, Sukdev,Kancherla, Rajesh,Mondal, Anirban,Dey, Aniruddha,Pimparkar, Sandeep,Agasti, Soumitra,Modak, Atanu,Maiti, Debabrata
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supporting information
p. 7751 - 7755
(2016/07/07)
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- Preparation of nano silica supported sodium hydrogen sulfate: As an efficient catalyst for the trimethyl, triethyl and t-butyldimethyl silylations of aliphatic and aromatic alcohols in solution and under solvent-free conditions
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Nano silica supported sodium hydrogen sulfate has been prepared by mixing NaHSO4 with activated Nano silicagel. We wish to report a new method for the synthesis of trimethyl (TMS), triethyl (TES) and t-butyldimethyl silyl (TBS) ethers from benzylic, allylic, propargylic alcohols, phenols, naphtholes and some of phenolic drugs in the solution and under solvent-free conditions.
- Abri, Abdolreza,Ranjdar, Somayeh
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p. 929 - 934
(2014/10/16)
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- A mild and highly efficient method for the preparation of silyl ethers using Fe(HSO4)3/Et3N by chlorosilanes
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Avery efficient and mild procedure for preparation of silyl ethers from benzylic, allylic, propargilic alcohols, phenols, naphtoles and some of phenolic drugs with trimethylsilylchloride (TMSCl), triethylsilylchloride (TESCl) and t-buthyldimethylsilyl chloride (TDSCl) ethers in the presence of Fe(HSO 4)3/Et3N in roomtemperature in excellent yields is reported. This procedure also allows the excellent selectivity for silylation of alcohols and phenols.
- Abri, Abdolreza,Assadi, Mohammad Galeh,Pourreza, Samira
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p. 1449 - 1454
(2013/03/13)
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- The effect of solvent accessible surface on Hammett-type dependencies of infinite dilution 29Si and 13C NMR shifts in ring substituted silylated phenols dissolved in chloroform and acetone
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Infinite dilution 29Si and 13C NMR chemical shifts were determined from concentration dependencies of the shifts in dilute chloroform and acetone solutions of para substituted O-silylated phenols, 4-R-C6H4-O-SiR′2R″ (R = Me, MeO, H, F, Cl, NMe2, NH2, and CF3), where the silyl part included groups of different sizes: dimethylsilyl (R′ = Me, R″ = H), trimethylsilyl (R′ = R″ = Me), tert-butyldimethylsilyl (R′ = Me, R″ = CMe3), and tert-butyldiphenylsilyl (R′ = C6H5, R″ = CMe3). Dependencies of silicon and C-1 carbon chemical shifts on Hammett substituent constants are discussed. It is shown that the substituent sensitivity of these chemical shifts is reduced by association with chloroform, the reduction being proportional to the solvent accessible surface of the oxygen atom in the Si-O-C link. Copyright
- Blechta, Vratislav,Sabata, Stanislav,Sykora, Jan,Hetflejs, Jiri,Soukupova, Ludmila,Schraml, Jan
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experimental part
p. 128 - 134
(2012/08/07)
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- A two-component small molecule system for activity-based detection and signal amplification: Application to the visual detection of threshold levels of Pd(II)
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A detection and signal amplification strategy aimed toward threshold diagnostic assays for use in resource-limited settings is described. The strategy employs two small molecule reagents that work in tandem. One reagent detects a specific analyte, while the second amplifies a colorimetric readout autocatalytically. The strategy is demonstrated using palladium(II) as a model analyte.
- Baker, Matthew S.,Phillips, Scott T.
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supporting information; experimental part
p. 5170 - 5173
(2011/05/19)
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- Enol silyl ethers via copper(II)-catalyzed C-O bond formation
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Copper(II) acetate catalyzes the coupling of pinacol vinylboronates with silanols producing enol silyl ethers. This represents a novel enol silyl ether synthesis via formation of the C-O bond instead of the conventional Si-O bond. This also constitutes the first transition-metal-catalyzed oxidative cross-coupling with silanols.
- Chan, Daniel G.,Winternheimer, David J.,Merlic, Craig A.
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supporting information; experimental part
p. 2778 - 2781
(2011/08/02)
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- Nickel-catalyzed Kumada cross-coupling reactions of tertiary alkylmagnesium halides and aryl bromides/triflates
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We report a Ni-catalyzed process for the cross-coupling of tertiary alkyl nucleophiles and aryl bromides. This process is extremely general for a wide range of electrophiles and generally occurs with a ratio of retention to isomerization >30:1. The same procedure also accommodates the use of aryl triflates, vinyl chlorides, and vinyl bromides as the electrophilic component.
- Joshi-Pangu, Amruta,Wang, Chao-Yuan,Biscoe, Mark R.
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supporting information; experimental part
p. 8478 - 8481
(2011/06/25)
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- Cationic Au(I)- and Pt(II)-catalyzed silylation of alcohols using allylsilanes
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The silylation of alcohols using allylsilanes was catalyzed by cationic Au(I) and Pt(II) species, which were prepared in situ from the metal chlorides ([AuCl(PPh3)], PtCl2) and a silver salt. TBS-, TES-, and TIPS-protections of vario
- Shibata, Takanori,Kanda, Kazumasa,Ueno, Yasunori,Fujiwara, Ryo
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p. 1146 - 1147
(2007/10/03)
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- An Effective Approach for the Silylation of Hydroxyl Compounds in Room Temperature Ionic Liquids
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The room temperature ionic liquid (RTIL) 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6) is used as a "green" recyclable alternative to conventional solvents for the silylation of a series of hydroxyl compounds (alcohols and phenols
- Xu, Zhen-Yuan,Xu, Dan-Qian,Liu, Bao-You,Luo, Shu-Ping
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p. 4143 - 4149
(2007/10/03)
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- A Convenient Method for Protection and Deprotection of Alcohols and Phenols as Alkylsilyl Ethers Catalyzed by Iodine under Microwave Irradiation
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Irradiation of alcohols or phenols with tert-butyldimethylsilyl chloride (TBDMSCl) or trimethylsilyl chloride (TMSCl) in presence of catalytic amount (20 mol%) of iodine in a microwave oven for 2 min gives the corresponding silyl ethers in excellent yield. Iodine in methanol deprotects the silyl ether into its parent alcohol or phenol under similar reaction conditions.
- Saxena, Ira,Deka, Nabajyoti,Sarma, Jadab C.,Tsuboi, Sadao
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p. 4185 - 4191
(2007/10/03)
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- Effective silylation of carboxylic acids under solvent-free conditions with tert-butyldimethylsilyl chloride (TBDMSCL) and triisopropylsilyl chloride (TIPSCL)
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Varions types of carboxylic acids can be converted effectively to their corresponding TBDMS and TIPS esters using TBDMSCI and TIPSCI in the presence of imidazole under solvent-free conditions. The advantage of this modified method in comparison with that reported by Corey is the elimination of DMF, which eliminates aqueous work-up. The method is not a time-consuming process and the reactions proceed spontaneously. By this method, absolute chemoselectivity for the protection of carboxylic acid functions in the presence of 2°, 3° hydroxyl groups are observed.
- Firouzabadi, Habib,Iranpoor, Naser,Shaterian, Hamid Reza
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- Efficient and chemoselective protection of alcohols and phenols with tert-butyldimethylchlorosilane (TBDMCS) under solvent-free conditions
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Various types of primary and secondary alcohols and phenols can be converted efficiently to their corresponding TBDMS ethers using TBDMCS/imidazole under solvent-free conditions. Elimination of DMF, accompanied with an easy non-aqueous work-up and a high rate enhancement of the reaction are worthy to be mentioned for the presented method. The reactions show absolute chemoselectivity for the protection of primary in the presence of secondary alcohols.
- Firouzabadi, Habib,Etemadi, Shahrad,Karimi, Babak,Jarrahpour, Ali Asghar
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- 29Si NMR spectra of tert-butyldimethylsilylated alcohols
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29Si NMR spectra of a series of tert-butyldimethylsilyl derivatives of simple alcohols were measured under standard conditions in chloroform-d. The chemical shifts are linearly related to those in analogous trimethylsilyl derivatives. The corre
- Schraml, Jan,Kvi?c?alova?, Magdalena,Blechta, Vratislav,C?erma?k, Jan
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p. 659 - 662
(2007/10/03)
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- A convenient method for the protodesilylation of aryltrimethylsilanes
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A mild and highly effective procedure for the removal of aromatic trimethylsilyl groups involving treatment of ArSiMe3 with Me3SiCl, KI and H2O in acetonitrile, is reported.
- Radner, Finn,Wistrand, Lars-G.
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p. 5093 - 5094
(2007/10/02)
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- Polymer-supported reactions in organic synthesis: Part 1 - Protection and deprotection of phenols using anion exchange resin.
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Phenoxide ions supported on Amberlite IRA-400 (chloride form) are protected as t-butyl(dimethyl)silyl (TBDMS) ethers in good to excellent yields and subsequently deprotected by fluoride ions supported on Amberlite IRA-400 (chloride form).
- Bandgar, B. P.,Unde, S. D.,Unde, D. S.,Kulkarni, V. H.,Patil, S. V.
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p. 782 - 784
(2007/10/03)
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- 1,8-DIAZABICYCLOUNDEC-7-ENE(DBU): AN EFFECTIVE BASE FOR THE INTRODUCTION OF t-BUTYLDIMETHYLSILYL GROUP IN ORGANIC COMPOUNDS.
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Reaction of alcohols, thiols, amines, carboxylic acids, phenols, hydroquinones, ketoesters and amides with equimolecular amounts of t-butyldimethylchlorosilane and DBU, even in solvents other than dimethylformamide affords the corresponding t-butyldimethy
- Aizpurua, Jesus M.,Palomo, Claudio
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p. 475 - 476
(2007/10/02)
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- Organic Reactions at High Pressure. Dipolar Cycloaddition-Ring Contraction Reactions of Hindered Silyl Enol Ethers and Arylsulfonyl Azides
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Dipolar cycloaddition of arylsulfonyl azides with sterically congested silyl enol ethers at 15 kbar (1.5 GPa) in acetonitrile/methylene chloride cleanly affords good yields of one-carbon ring-contracted products.
- Dauben, William G.,Bunce, Richard A.
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p. 5042 - 5044
(2007/10/02)
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