- Optimized catalytic enantioselective aryl transfer process gives access to mGlu2 receptor potentiators
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An asymmetric enantioselective aryl transfer reaction was developed to give access to the diarylmethanol 7 and ultimately acetate 2 which is useful for the preparation of mGlu2 receptor potentiators (Scheme 3). The aryl transfer chemistry involved the pre
- Magnus, Nicholas A.,Anzeveno, Peter B.,Coffey, D. Scott,Hay, David A.,Laurila, Michael E.,Schkeryantz, Jeffrey M.,Shaw, Bruce W.,Staszak, Michael A.
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Read Online
- Efficient method for the t-butyldimethylsilylation of alcohols with N,O-bis(t-butyldimethylsilyl)acetamide
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The efficient t-butyldimethylsilylation of alcohols - including tertiary and sterically hindered secondary alcohols - can be achieved using N,O-bis(t-butyldimethylsilyl)acetamide (BTBSA) in the presence of catalytic amounts (0.01-0.05 equiv) of tetrabutyl
- Johnson, David A.,Taubner, Lara M.
-
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Read Online
- Cationic Dirhodium Complexes Bridged by 2-Phosphinopyridines Having an Exquisitely Positioned Axial Shielding Group: A Molecular Design for Enhancing the Catalytic Activity of the Dirhodium Core
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This report describes a strategy to create highly electrophilic dirhodium catalysts. The electrophilicity of lantern-Type dirhodium complexes is generally decreased by the coordination of a ligand to the axial site, which often causes a reduction in the catalytic activity. We designed and synthesized a series of cationic dirhodium complexes bridged by 2-diarylphosphinopyridines having a bulky 2,4,6-Triisopropylphenyl (Tip) group that can prevent the attack of external molecules to the closest axial site. Theoretical calculations indicated that the Tip group weakly interacts with the axial site but hardly reduces the electrophilicity of the dirhodium core. The complexes served as excellent catalyst precursors for the dehydrogenative silylation of alcohols using hydrosilanes under mild conditions and a low metal loading, producing the silyl ethers in higher yields in comparison to conventional dirhodium complexes.
- Ohnishi, Ryuhei,Ohta, Hidetoshi,Mori, Shigeki,Hayashi, Minoru
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p. 2678 - 2690
(2021/07/31)
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- Synergistic Catalysis by Br?nsted Acid/Carbodicarbene Mimicking Frustrated Lewis Pair-Like Reactivity
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Carbodicarbene (CDC), unique carbenic entities bearing two lone pairs of electrons are well-known for their strong Lewis basicity. We demonstrate herein, upon introducing a weak Br?nsted acid benzyl alcohol (BnOH) as a co-modulator, CDC is remolded into a Frustrated Lewis Pair (FLP)-like reactivity. DFT calculation and experimental evidence show BnOH loosely interacting with the binding pocket of CDC via H-bonding and π-π stacking. Four distinct reactions in nature were deployed to demonstrate the viability of proof-of-concept as synergistic FLP/Modulator (CDC/BnOH), demonstrating enhanced catalytic reactivity in cyclotrimerization of isocyanate, polymerization process for L-lactide (LA), methyl methacrylate (MMA) and dehydrosilylation of alcohols. Importantly, the catalytic reactivity of carbodicarbene is uniquely distinct from conventional NHC which relies on only single chemical feature of nucleophilicity. This finding also provides a new spin in diversifying FLP reactivity with co-modulator or co-catalyst.
- Bai, Yuna,Chan, Yi-Chen,Chen, Hsing-Yin,Chen, Hsuan-Ying,Chen, Wen-Ching,Li, Chen-Yu,Ong, Tiow-Gan,Tseng, Mei-Chun,Wu, Ying-Yann,Yap, Glenn P. A.,Zhao, Lili
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supporting information
p. 19949 - 19956
(2021/08/03)
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- Use of Silylated Formiates as Hydrosilane Equivalents
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The present invention relates to a method for preparing organic compounds of formula (I) by reaction between a silylated formiate of formula (II) and an organic compound in the presence of a catalyst and optionally of an additive. The invention also relates to use of the method for preparing organic compounds of formula (I) for the preparation of reagents for fine chemistry and for heavy chemistry, as well as in the production of vitamins, pharmaceutical products, adhesives, acrylic fibres, synthetic leathers, and pesticides.
- -
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Paragraph 0514
(2021/09/26)
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- Silylation of Alcohols, Phenols, and Silanols with Alkynylsilanes – an Efficient Route to Silyl Ethers and Unsymmetrical Siloxanes
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The formation of several silyl ethers (alkoxysilanes, R3Si-OR') and unsymmetrical siloxanes (R3Si-O-SiR'3) can be catalyzed by the commercially available potassium bis(trimethylsilyl)amide (KHMDS). The reaction proceeds via direct dealkynative coupling between various alcohols or silanols and alkynylsilanes, with a simultaneous formation of gaseous acetylene as the sole by-product. The dehydrogenative and dealkenative coupling of alcohols or silanols are well-investigated, whilst the utilization of alkynylsilanes as silylating agents has never been comprehensively studied in this context. Overall, the presented system allows the synthesis of various attractive organosilicon compounds under mild conditions, making this approach an atom-efficient, environmentally benign, and sustainable alternative to existing synthetic solutions.
- Kuciński, Krzysztof,Stachowiak, Hanna,Hreczycho, Grzegorz
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p. 4042 - 4049
(2020/07/04)
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- Catalytic reduction of aryl trialkylammonium salts to aryl silanes and arenes
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A new approach for the reduction of aryl ammonium salts to arenes or aryl silanes using nickel catalysis is reported. This method displays excellent ligand-controlled selectivity based on the N-heterocyclic carbene (NHC) ligand employed. Utilizing a large NHC in non-polar solvents generates aryl silanes, while small NHCs in polar solvents promote reduction to arenes. Several classes of aryl silanes can be accessed from simple aniline building blocks, including those useful for cross-couplings, oxidations, and halogenations. The reaction conditions are mild, functional group tolerant, and provide efficient access to a variety of benzene derivatives.
- Rand, Alexander W.,Montgomery, John
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p. 5338 - 5344
(2019/05/29)
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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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- HYDROXIDE-CATALYZED FORMATION OF SILICON-OXYGEN BONDS BY DEHYDROGENATIVE COUPLING OF HYDROSILANES AND ALCOHOLS
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The present disclosure is directed to methods for dehydrogenatively coupled hydrosilanes and alcohols, the methods comprising contacting an organic substrate having at least one organic alcohol moiety with a mixture of at least one hydrosilane and sodium and/or potassium hydroxide, the contacting resulting in the formation of a dehydrogenatively coupled silyl ether. The disclosure further described associated compositions and methods of using the formed products.
- -
-
Paragraph 0148; 0152
(2017/02/28)
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- Iron-Catalyzed Silylation of Alcohols by Transfer Hydrosilylation with Silyl Formates
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An iron catalyst is shown for the first time to promote transfer hydrosilylation with silyl formates and is utilized for the silylation of alcohols. Attractive features of this protocol include the use of an earth-abundant transition-metal catalyst, mild reaction conditions, and the release of gases as the only byproducts (H 2 and CO 2).
- Godou, Timothé,Chauvier, Clément,Thuéry, Pierre,Cantat, Thibault
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supporting information
p. 2473 - 2477
(2017/10/26)
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- Silylation of O-H bonds by catalytic dehydrogenative and decarboxylative coupling of alcohols with silyl formates
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The silylation of O-H bonds is a useful methodology in organic synthesis and materials science. While this transformation is commonly achieved by reacting alcohols with reactive chlorosilanes or hydrosilanes, we show herein for the first time that silylformates HCO2SiR3 are efficient silylating agents for alcohols, in the presence of a ruthenium molecular catalyst.
- Chauvier, Clément,Godou, Timothé,Cantat, Thibault
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supporting information
p. 11697 - 11700
(2017/11/03)
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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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- Sodium Hydroxide Catalyzed Dehydrocoupling of Alcohols with Hydrosilanes
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An O-Si bond construction protocol employing abundantly available and inexpensive NaOH as the catalyst is described. The method enables the cross-dehydrogenative coupling of an alcohol and hydrosilane to directly generate the corresponding silyl ether under mild conditions and without the production of stoichiometric salt byproducts. The scope of both coupling partners is excellent, positioning the method for use in complex molecule and materials science applications. A novel Si-based cross-coupling reagent is also reported.
- Toutov, Anton A.,Betz, Kerry N.,Haibach, Michael C.,Romine, Andrew M.,Grubbs, Robert H.
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supporting information
p. 5776 - 5779
(2016/11/29)
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- Amine-free silylation of alcohols under 4-methylpyridine N-oxide-catalyzed conditions
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Amine-free silylation of various alcohols catalyzed by 4-methylpyridine N-oxide in the presence of MS4A at room temperature was developed. This simple method gave various silyl ethers in a high yield.
- Yoshida, Keisuke,Fujino, Yuta,Itatsu, Yukihiro,Inoue, Hiroki,Kanoko, Yohei,Takao, Ken-Ichi
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p. 627 - 631
(2016/01/20)
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- Selective Hydrogenolysis of Arenols with Hydrosilanes by Nickel Catalysis
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Nickel-catalyzed hydrogenolysis of arenols has been developed through the use of hydrosilane as a reductant. Sterically demanding N-heterocyclic carbene (NHC) ligands are crucial for the reaction. The present protocol allows selective cleavage of ArO bonds of arenols over aryl and benzyl ethers.
- Ohgi, Akito,Nakao, Yoshiaki
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supporting information
p. 45 - 47
(2016/01/20)
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- Radical Hydrodeiodination of Aryl, Alkenyl, Alkynyl, and Alkyl Iodides with an Alcoholate as Organic Chain Reductant through Electron Catalysis
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A simple and efficient method for radical hydrodeiodination is reported. The novel approach uses electron catalysis. In situ generated Na-alcoholates are introduced as radical chain reducing reagents and reactions work with O2as cheap initiator. Hydrodeiodination works on aryl, alkenyl, alkynyl iodides and a tert-alkyl iodide also gets reduced applying the method. Albeit less general, the method is also applicable to the reduction of aryl bromides. The novel reagent is successfully used to conduct typical reductive radical cyclization reactions and mechanistic studies are reported.
- Dewanji, Abhishek,Mück-Lichtenfeld, Christian,Studer, Armido
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supporting information
p. 6749 - 6752
(2016/06/09)
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- Gold(I)-catalyzed synthesis of unsymmetrical ethers using alcohols as alkylating reagents
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A microwave-irradiated alcohol-protecting strategy based on gold catalysis utilizing benzyl alcohol, tert-butyl alcohol and triphenylmethanol as alkylating reagents has been developed. This protecting strategy has wide functional group tolerance with satisfactory yields for the majority of the selected alcohols. The mechanism of this transformation was probed with oxygen-18 isotope labelled alcohols assisted by GC-MS techniques and chemical kinetic experiments. This strategy provides an efficient, straightforward and alternative approach to the preparation of benzyl, tert-butyl and trityl ethers in organic synthesis.
- Liu, Yongxiang,Wang, Xiaoyu,Wang, Yanshi,Du, Chuan,Shi, Hui,Jin, Shengfei,Jiang, Chongguo,Xiao, Jianyong,Cheng, Maosheng
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p. 1029 - 1036
(2015/03/30)
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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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- Carboxylation with CO2 via brook rearrangement: Preparation of α-hydroxy acid derivatives
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In the presence of CsF, a wide range of α-substituted α-siloxy silanes were carboxylated under a CO2 atmosphere (1 atm) via Brook rearrangement. A variety of α-substituents including aryl, alkenyl, and alkyl groups were tolerated to afford α-hydroxy acids in moderate-to-high yields. One-pot synthesis from aldehydes using PhMe2SiLi and CO 2 was also possible, providing α-hydroxy acids without the isolation of an α-hydroxy silane.
- Mita, Tsuyoshi,Higuchi, Yuki,Sato, Yoshihiro
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supporting information
p. 14 - 17
(2014/01/23)
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- Total synthesis of the postulated structure of fulicineroside
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A total synthesis of the proposed structures of fulicineroside and its aglycone fulicinerine is reported. The tetrasubstituted dibenzofuran substructure was accessible either through a Pd-mediated ortho-metalation or by an Ir-catalyzed meta-borylation. The synthesis of the β,β,α- linked trisaccharide consisting of D-olivose, L-rhodinose, and L-rhamnose was challenged by the unprecedented β-linked rhodinose. A Pd-catalyzed β-selective glycosylation of a 4-epi-rhodinose and a subsequent Mitsunobu inversion provided selectively the β-linked L-rhodinose-L-rhamnose disaccharide. Comparison with the reported data for the natural product and the aglycone suggests a misassignment of the structure of the natural product. Natural product reassignment: Total synthesis of the proposed structures for fulicineroside and its aglycone fulicinerine has been achieved (see figure). Key issues were the tetrasubstituted dibenzofuran and the trisaccharide with its β-linkage between L-rhodinose and L-rhamnose. A comparison with the reported data for the natural product and the aglycone suggests a misassignment of the structure of the natural product. Copyright
- Bartholom?us, Ruben,Dommershausen, Fabian,Thiele, Markus,Karanjule, Narayan S.,Harms, Klaus,Koert, Ulrich
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supporting information
p. 7423 - 7436
(2013/06/27)
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- Trioxorhena(VII)carborane anion and its methyl-substituted analogue: Synthesis, structure, DFT, and catalytic studies
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Synthesis and characterization of trioxorhena(VII)carborane [Bu 4N][(η1-C2B9H 11)ReO3] (1a) and its methyl-substituted analogue [Bu 4N][(7,8-Me2-η1-C2
- Pichaandi, Kothanda Rama,Fanwick, Phillip E.,Abu-Omar, Mahdi M.
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scheme or table
p. 1888 - 1896
(2012/04/23)
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- Rhodium carbene complexes as versatile catalyst precursors for Si-H bond activation
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Rhodium(III) complexes comprising monoanionic C,C,C-tridentate dicarbene ligands activate Si-H bonds and catalyse the hydrolysis of hydrosilanes to form silanols and siloxanes with concomitant release of H2. In dry MeNO2, selective formation of siloxanes takes place, while changing conditions to wet THF produces silanols exclusively. Silyl ethers are formed when ROH is used as substrate, thus providing a mild route towards the protection of alcohols with H2 as the only by-product. With alkynes, comparably fast hydrosilylation takes place, while carbonyl groups are unaffected. Further expansion of the Si-H bond activation to dihydrosilanes afforded silicones and polysilyl ethers. Mechanistic investigations using deuterated silane revealed deuterium incorporation into the abnormal carbene ligand and thus suggests a ligand-assisted mechanism involving heterolytic Si-H bond cleavage. Ligand-assisted Si-H bond cleavage: Rhodium-catalysed Si-H bond activation provides a methodology for the silyl group to be transferred to oxygen centres, thus providing access to siloxanes and silanols (using H 2O), alkoxysilanes (using ROH) and to polysiloxanes, such as silicones, when using difunctional silanes. The process is pH neutral, avoids sensitive silylating agents and produces H2 as useful and exclusive side product. Copyright
- Krueger, Anneke,Albrecht, Martin
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scheme or table
p. 652 - 658
(2012/03/08)
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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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- 4-(N,N-dimethylamino)pyridine-embedded nanoporous conjugated polymer as a highly active heterogeneous organocatalyst
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We report herein for the first time the incorporation of a versatile organocatalyst, 4-(N,N-dimethylamino)pyridine (DMAP), into the network of a nanoporous conjugated polymer (NCP) by the "bottom-up" approach. The resulting DMAP-NCP material possesses highly concentrated and homogeneously distributed DMAP catalytic sites (2.02 mmol g-1). DMAP-NCP also exhibits enhanced stability and permanent porosity due to the strong covalent linkage and the rigidity of the "bottom-up" monomers. As a result, DMAP-NCP shows excellent catalytic activity in the acylation of alcohols with yields of 92-99 %. The DMAP-NCP catalyst could be easily recovered from the reaction mixture and reused in at least 14 consecutive cycles without measurable loss of activity. Moreover, the catalytic acylation reaction could be performed under neat and continuous-flow conditions for at least 536 h of continuous work with the same catalyst activity. Copyright
- Zhang, Yuan,Zhang, Yong,Sun, Ya Lei,Du, Xin,Shi, Jiao Yi,Wang, Wei,Wang, Wei David
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experimental part
p. 6328 - 6334
(2012/06/18)
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- Highly efficient and chemoselective ruthenium-catalyzed hydrosilylation of aldehydes
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The highly chemoselective hydrosilylation of aldehydes was achieved using a ruthenium catalyst activated by a household fluorescent light (30 W) at or below room temperature. The hydrosilylation was almost exclusive to aldehydes over ketones and olefins.
- Do, Youngshil,Han, Junghoon,Rhee, Young Ho,Park, Jaiwook
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experimental part
p. 3363 - 3366
(2012/02/01)
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- Metal-free relay oxidation: Valuable synthesis of acylsilane and ketones under aerobic oxidation
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In this letter, an example of interesting metal-free relay air oxidation of -hydroxysilanes, promoted by the hydroperoxidated carbonyl compounds derived from the Michael reaction of 5,5-dimethylcyclohexane-1,3-dione and chalcone, is reported. A series of aromatic acylsilanes with TBDPS were obtained in promising isolated yields. In addition, as an extension of the relay oxidation under aerobic conditions, this catalyst-free relay oxidation induced by diketone can be applied to the oxidation of general aromatic alcohols (up to 75% yield). Georg Thieme Verlag Stuttgart · New York.
- Bai, Xing-Feng,Gao, Guang,Zheng, Zhan-Jiang,Li, Fei,Lai, Guo-Qiao,Jiang, Kezhi,Li, Fuwei,Xu, Li-Wen
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supporting information; scheme or table
p. 3031 - 3035
(2012/01/05)
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- Asymmetric hydrogenation of aromatic, aliphatic, and α,β- unsaturated acyl silanes catalyzed by tol-binap/pica ruthenium(II) complexes: Practical synthesis of optically active α-hydroxysilanes
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(Chemical Equation Presented) A catalytic system of RuII complex (see scheme; Ar = 4-CH3C6H4; R = H, t-C 4H9) and t-C4H9OK or NaBH 4 activator has been used in the hydrogenation of aromatic and aliphatic acyl silanes to give α-hydroxysilanes with high enantioselectivity (R1 = aryl, alkyl, alkenyl; R2 = t-C4H9, C6H5). Optically active allylic α-hydroxysilanes are obtained in the 1,2-reduction of α,β-unsaturated acyl silanes. These chiral α-hydroxysilanes are converted into 4-substituted 2-cyclopentenones without loss of enantioselectivity.
- Arai, Noriyoshi,Suzuki, Ken,Sugizaki, Satoshi,Sorimachi, Hiroko,Ohkuma, Takeshi
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supporting information; scheme or table
p. 1770 - 1773
(2009/02/06)
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- Protecting groups transfer: Unusual method of removal of tr and TBDMS groups by transetherification
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The triphenylmethyl (Tr) group undergoes a transfer (transetherification or disproportionation) between the molecules of 5'-O-Tr-2'-deoxynucleosides in a process mediated by anhydrous sulfates of Cu+2, Fe+2, or Ni+2 to yield mixtures of 3',5'-bis-O-Tr and 3'-O-Tr products. If phenylmethanol is present in a reaction medium, detritylation results with concomitant formation of phenylmethyl triphenylmethyl ether. The behavior of t-butyldimethylsilyl (TBDMS) group in 5'-O-TBDMS-2'-deoxynucleosides is exactly the same. Such type of transetherifications was not observed before for the O-Tr and O-TBDMS groups. Copyright Taylor & Francis Group, LLC.
- Cabral, Nadia L. D.,Thiessen, Luciano Hoeltgebaum,Doboszewski, Bogdan
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p. 931 - 948
(2008/12/21)
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- Cationic carboxylato complexes of dirhodium(II) with oxo thioethers: Catalysts for silane alcoholysis under homogeneous and liquid-liquid biphasic conditions
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A set of cationic dirhodium(II) complexes with oxo thioethers was prepared and employed as catalysts for the silane alcoholysis reaction. The complexes were found to be highly active under homogeneous conditions, both in the absence and in the presence of a solvent, including coordinating solvents such as N,N-dimethylformamide ; the catalysts could be conveniently employed in concentrations as low as 0.01 mol%, and a maximum TON of 30000 was recorded after 24 h. The same catalysts were also employed under liquid-liquid biphasic conditions with an ionic liquid as the catalyst-containing phase: comparable catalytic activity was observed under these conditions, and the catalyst-containing phase could be recovered and recycled. A chiral cationic dirhodium(II) complex was also prepared in the frame of this work; kinetic resolution of a racemic alcohol was attempted with this catalyst, unfortunately without success.
- Biffis, Andrea,Basato, Marino,Brichese, Marianna,Ronconi, Luca,Tubaro, Cristina,Zanella, Alessandra,Graiff, Claudia,Tiripicchio, Antonio
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p. 2485 - 2492
(2008/09/19)
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- Removal, recovery, and recycling of triarylphosphonium-supported tin reagents for various organic transformations
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Phosphonium-supported tin reagents and catalysts were prepared and were shown to be effective in Stille couplings, radical dehalogenations, radical cyclizations, and carbonyl allylations. Not only could the tin residues be removed from the crude reaction mixture through a phase separation process but also they could be recovered and recycled.
- Poupon, Jean-Christophe,Marcoux, David,Cloarec, Jean-Manuel,Charette, Andre B.
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p. 3591 - 3594
(2008/02/12)
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- Zinc mediated reactions in organic synthesis: Efficient synthesis of silyl ethers under mild conditions
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General and practical method for the syn the sis of silyl ethers in the presence of zinc powder under mild conditions has been described.
- Bandgar, Babasaheb Pandurang,Chavare, Satish Navnath,Pandit, Shivaji Sandu
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p. 125 - 128
(2007/10/03)
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- Selective oxidation of benzylic alcohols and TBDMS ethers to carbonyl compounds with CrO3-H5IO6
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Benzyl alcohols and benzyl TBDMS ethers were efficiently oxidized to the corresponding carbonyl compounds in high yield with periodic acid catalyzed by CrO3 at low temperature (-78°C). The oxidation procedure was highly functional group tolerant and very selective for the TBDMS group over the TBDPS group. Georg Thieme Verlag Stuttgart.
- Zhang, Suhong,Xu, Liang,Trudell, Mark L.
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p. 1757 - 1760
(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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- Activation of silanes by Grubbs' carbene complex Cl2(PCy3)2Ru=CHPh: Dehydrogenative condensation of alcohols and hydrosilylation of carbonyls
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This manuscript describes two catalytic methods for silyl ether synthesis using Grubbs' catalyst Cl2(PCy3)2Ru=CHPh. Silyl ethers are obtained from the reaction of a variety of silanes with alcohols by dehydrogenative conde
- Maifeld, Sarah V,Miller, Reagan L,Lee, Daesung
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p. 6363 - 6366
(2007/10/03)
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- Electron-Rich 0 = PR3 compounds: Catalysts for alcohol silylation
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The catalytic effect of a group of R3P = O compounds was studied in a mild procedure for the silylation of primary alcohols, secondary alcohols, hindered secondary alcohols, and of hindered phenols in the presence of t-butyldimethylsilyl chlori
- Liu, Xiaodong,Verkade, John G.
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- Alkoxyallylsilanes: Functional protecting groups
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Allyl-t-butylmethylsilyl groups were shown to function as alcohol protecting groups whose hydrolytic stability was greater than t- butyldimethylsilyl (TBS) and Si(SiMe3)3 (sisyl) groups. Pseudo-first-order rate constants for the acid
- Balduzzi, Sonya,Brook, Michael A.
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p. 1617 - 1622
(2007/10/03)
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- The photolytic and hydrolytic lability of sisyl (Si(SiMe3)3) ethers, an alcohol protecting group
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The tris(trimethylsilyl)silyl (sisyl) group is a photolabile protecting group for primary and secondary alcohols. Sisyl (tris(trimethylsilyl)silyl) ethers 2b-11b of a number of primary and secondary alcohols 2a-11a were prepared in yields ranging from 70-97%. The resulting silyl ethers were stable to aqueous bases, Grignard reagents and Wittig reagents as would be expected for bulky alkoxysilanes. They were also stable to selected fluoride salts including CsF. The sisyl ethers could be cleaved using photolysis at 254 nm in under 30 minutes to give the starting alcohols in yields ranging from 62-95%. The photolytic behaviour of sisyl ethers was examined in more detail using 2,3-dimethyl-1,3-butadiene as a silylene trap. The regiochemistry of the oligosilane fragmentation to silylenes was shown to be dependent upon the alkoxy group. The hydrolytic stability of three was compared with the analogous t-butyldimethylsilyl ethers. The relative stability of the two silyl groups can be altered by choice of solvent: in acetic acid/water the ease of hydrolysis followed the order ROSi(SiMe3)3 > ROSiMe2t-Bu; the inverse order was observed in CDCl3 using p-TsOH·H2O. Pseudo-first-order rate constants for the acidic hydrolysis of primary, benzylic, and secondary sisyl ether in AcOH/THF/H2O were determined to be 3.74 x 10-2 s-1, 1.94 x 10-2 s-1, and 1.30 x 10-2 s-1, respectively. The analogous rate constants for the TBS ethers were determined to be 6.04 x 10-3 s-1, 3.53 x 10-3 s-1, and 3.49 x 10-3 s-1, respectively.
- Brook,Balduzzi,Mohamed,Gottardo
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p. 10027 - 10040
(2007/10/03)
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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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- An Efficient and Highly Chemoselective Method to Desilylate Silyl Ethers
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An efficient and highly chemoselective desilylating method is described.Trimethylsilyl ethers (0.25 M) in a CH3OH/CCl4 (1:1) solvent mixture are deprotected to their corresponding alcohols with ultrasound in a commercial ultrasonic cleaning bath.Selective deprotection of tert-butyldimethylsilyl ethers of benzyl alcohols and phenols is achieved under ultrasonic conditions.We deprotected also tert-butyldimethylsilyl ethers of primary alcohols, whereas tert-butyldimethylsilyl ethers of secondary and tertiary alcohols are stable under these conditions. - Key words: Sonochemistry; Ultrasound; Cavitation; Desilylation; Chemoselection; Deprotection.
- Lee, Adam Shih-Yuan,Yeh, Hsiu-Chih,Yeh, Ming-Kuo,Tsai, Ming-Hung
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p. 919 - 922
(2007/10/03)
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- A novel method for direct conversion of tetrahydropyranyl ethers into t-butyldimethylsilyl ethers with t-butyldimethylsilyl triflate and dimethyl sulfide
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Direct conversion of THP ethers into TBS ethers has been achieved with TBSOTf and dimethyl sulfide in dichloromethane.
- Kim,Kee
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p. 2899 - 2900
(2007/10/02)
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- The Utility of t-Butyldimethylsilane as an Effective Silylation Reagent for the Protection of Functional Groups
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Treatment of compounds containing functional groups, such as alcohols, amines, and carboxylic acids, with t-butyldimethylsilane in the presence of a catalytic amount of palladium on carbon is described to provide a new, convenient method for the introduction of a t-butyldimethylsilyl (TBDMS) group.
- Yamamoto, Keiji,Takemae, Makoto
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p. 2111 - 2113
(2007/10/02)
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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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- 1,1,3,3-TETRAMETHYLGUANIDINE: AN EFFECTIVE CATALYST FOR THE t-BUTYLDIMETHYLSILYLATION OF ALCOHOLS
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Reaction of alcohols with equimolar amounts of t-butyldimethylchlorosilane and triethylamine in the presence of 1,1,3,3-tetramethylguanidine as a catalyst affords the t-butyldimethylsilyl ethers in high yields.
- Kim, Sunggak,Chang, Heung
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p. 899 - 904
(2007/10/02)
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