- Base-Catalysed Hydrogenation of Sulphur-Containing Aldehydes
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The present work reports the first selective catalytic hydrogenation of bifunctional compounds containing a carbonyl and sulphur moieties, using hydrogen transfer from alcohols and a basic catalyst. The reaction was performed in batch at 371 K at atmospheric pressure with 3- mercaptopropionaldehyde, thiophene-2-carboxaldehyde, 5-bromothiophene-2- carboxaldehyde and 4-methylthiobenzaldehyde. The only product of reaction was the alcohol, formed with yields > 80%, except with 3-mercaptopropionaldehyde which did not give the alcohol but rather afforded unidentified heavy products. 5-Bromothiophenemethanol was obtained with 100% yield in 3 h. The reaction obeys a mechanism of competitive adsorption of the reactants, and the reaction rates are higher than those reported for supported rhodium catalysts.
- Vu, Thi-Thu-Ha,Kumbhar, Pramod S.,Figueras, Francois
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Read Online
- Nickel-Catalyzed Reversible Functional Group Metathesis between Aryl Nitriles and Aryl Thioethers
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We describe a new functional group metathesis between aryl nitriles and aryl thioethers. The catalytic system nickel/dcype is essential to achieve this fully reversible transformation in good to excellent yields. Furthermore, the cyanide- and thiol-free reaction shows high functional group tolerance and great efficiency for the late-stage derivatization of commercial molecules. Finally, synthetic applications demonstrate its versatility and utility in multistep synthesis.
- Delcaillau, Tristan,Boehm, Philip,Morandi, Bill
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supporting information
p. 3723 - 3728
(2021/04/07)
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- Reduction over Condensation of Carbonyl Compounds through a Transient Hemiaminal Intermediate Using Hydrazine
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Reduction of carbonyl moieties to the corresponding alcohol using simply hydrazine hydrate has been considerably unfeasible until now due to the well-known condensation reaction. However, herein, we report that using an excess of 20-fold equivalents, the reduction proceeds in excellent yields. 1H NMR study of the reaction and density functional theory (DFT) calculations indicate that the final fate of the hemiaminal intermediate is crucial to obtain the alcohol or the hydrazone.
- Vilches-Herrera, Marcelo,Gallardo-Fuentes, Sebastián,Aravena-Opitz, Mauricio,Yá?ez-Sánchez, Mauricio,Jiao, Haijun,Holz, Jens,B?rner, Armin,Lühr, Susan
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p. 9213 - 9218
(2020/08/14)
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- Synthetic Strategy for Tetraphenyl-Substituted All-E-Carotenoids with Improved Molecular Properties
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The synthetic method of tetraphenyl-substituted all-E-carotenes 1 with improved properties of antioxidant and molecular electronic conductance was developed through the formation of tetraphenyl-substituted all-E-apocarotenedial 4. The synthesis highlighted the preparation of novel subunits containing phenyl substituent(s) with E-configuration starting from the key (E)-4-chloro-2-phenylbut-2-enal (10), utilizing conjugation effect with formyl group or easy recrystallization of sulfone compounds. Sulfone-mediated coupling methods of Julia and modified Julia–Kocienski olefinations utilizing the subunits were demonstrated to produce tetraphenyl-substituted apocarotenedials 4. The major all-E-forms (73–85 % selectivity) were easily purified by SiO2 chromatography and trituration with Et2O due to the presence of the polar formyl groups. The olefination of all-E-apocarotenedials 4 and Wittig salt 5 provided all-E-9,9',13,13'-tetraphenylcarotenes 1.
- Chung, Wook-Jin,Jung, Hyunuk,Koo, Sangho,Lim, Boram,Park, Myeongnam,Yang, Huijeong,Yoo, Hyebin
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supporting information
(2020/03/13)
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- BORON CONTAINING COMPOUNDS AND THEIR USES
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The present disclosure contemplates novel boron-containing compounds and their uses as active agents that exhibit pesticidal activity such as antimicrobial, insecticidal, arachnicidal, and/or anti parasitic activity. An agrochemical composition containing such a compound and its use in, animal health, agriculture, or horticulture is also contemplated. A method for promoting plant performance and/or controlling, reducing, preventing, ameliorating, or inhibiting microbes, insects, arachnids, and/or parasites on or in an animal, a plant, a plant part, plant propagation material, and/or harvested fruits or vegetables is also contemplated.
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-
Paragraph 0314; 0315
(2020/03/29)
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- Polypyridyl iridium(III) based catalysts for highly chemoselective hydrogenation of aldehydes
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Iridium-catalyzed transfer hydrogenation (TH) of carbonyl compounds using HCOOR (R = H, Na, NH4) as a hydrogen source is a pivotal process as it provides the clean process and is easy to execute. However, the existing highly efficient iridium catalysts work at a narrow pH; thus, does not apply to a wide variety of substrates. Therefore, the development of a new catalyst which works at a broad pH range is essential as it can gain a broader scope of utilization. Here we report highly efficient polypyridyl iridium(III) catalysts, [Ir(tpy)(L)Cl](PF6)2 {where tpy = 2,2′:6′,2′'-Terpyridine, L = phen (1,10-Phenanthroline), Me2phen (4,7-Dimethyl-1,10-phenanthroline), Me4phen (3,4,7,8-Tetramethyl-1,10-phenanthroline), Me2bpy (4,4′-Dimethyl-2–2′-dipyridyl)} for the chemoselective reduction of aldehydes to alcohols in aqueous ethanol and sodium formate as the hydride source. The reaction can be carried out efficiently in broad pH ranges, from pH 6 to 11. These catalysts are air stable, easy to prepare using commercially available starting materials, and are highly applicable for a wide range of substrates, such as electron-rich or deficient (hetero)arenes, halogens, phenols, alkoxy, ketones, esters, carboxylic acids, cyano, and nitro groups. Particularly, acid and hydroxy groups containing aldehydes were reduced successfully in basic and acidic reaction conditions, demonstrating the efficiency of the catalyst in a broad pH range with high conversion rates under microwave irradiation.
- Pandrala, Mallesh,Resendez, Angel,Malhotra, Sanjay V.
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p. 283 - 288
(2019/09/30)
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- Regio- A nd chemoselective deprotection of primary acetates by zirconium hydrides
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A combination of DIBAL-H and Cp2ZrCl2 is shown to promote the regioselective cleavage of primary acetates on a broad scope of substrates, ranging from carbohydrates to terpene derivatives, with a high tolerance toward protecting groups and numerous functionalities found in natural products and bioactive compounds. Apart from providing highly valuable building blocks in only two steps from biosourced raw materials, this selective de-O-acetylation should also be strongly helpful to solve selectivity issues in organic synthesis.
- Gavel, Marine,Courant, Thibaut,Joosten, Antoine Yvan Philippe,Lecourt, Thomas
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supporting information
p. 1948 - 1952
(2019/04/10)
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- General and Phosphine-Free Cobalt-Catalyzed Hydrogenation of Esters to Alcohols
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Catalytic hydrogenation of esters is essential for the sustainable production of alcohols in organic synthesis and chemical industry. Herein, we describe the first non-noble metal catalytic system that enables an efficient hydrogenation of non-activated esters to alcohols in the absence of phosphine ligands (with a maximum turnover number of 2391). The general applicability of this protocol was demonstrated by the high-yielding hydrogenation of 39 ester substrates including aromatic/aliphatic esters, lactones, polyesters and various pharmaceutical molecules.
- Shao, Zhihui,Zhong, Rui,Ferraccioli, Raffaella,Li, Yibiao,Liu, Qiang
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supporting information
p. 1125 - 1130
(2019/10/22)
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- Cyclopentadienyl-ruthenium(II) complexes as efficient catalysts for the reduction of carbonyl compounds
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This work reports the reduction of a large variety of aldehydes and ketones with the system PhSiH3/[CpRu(PPh3)2Cl] in good to excellent yields and high chemoselectivity. The catalyst [CpRu(PPh3)2Cl] can be used in at least 12 catalytic cycles with excellent catalytic activity and several substrates were reduced under solvent free conditions.
- Cabrita, Ivania R.,Florindo, Pedro R.,Fernandes, Ana C.
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p. 1511 - 1516
(2017/02/18)
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- The Cu(i)-catalysed Huisgen 1,3-dipolar cycloaddition route to (bio-)organic functionalisation of polyoxovanadates
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The [V6O13{(OCH2)3CCH2OCH2CCH}2]2- with two terminal alkyne functionalities exhibits excellent reactivity towards (bio-)organic azides. The designed synthetic protocol for the generation of triazol-modified Lindqvist hexavanadates grants access to bio-"clicked" polyoxometalates with spectroscopically detectable 51V nuclei.
- Linnenberg, Oliver,Kondinski, Aleksandar,St?cker, Cornelia,Monakhov, Kirill Yu.
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supporting information
p. 15636 - 15640
(2017/12/02)
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- Efficient Water Reduction with sp3-sp3 Diboron(4) Compounds: Application to Hydrogenations, H–D Exchange Reactions, and Carbonyl Reductions
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A series of crystalline sp3-sp3 diboron(4) compounds were synthesized and shown to promote the facile reduction of water with dihydrogen formation. The application of these diborons as simple and effective dihydrogen and dideuterium sources was demonstrated by conducting a series of selective reductions of alkynes and alkenes, and hydrogen–deuterium exchange reactions using two-chamber reactors. Finally, as the water reduction reaction generates an intermediate borohydride species, a range of aldehydes and ketones were reduced by using water as the hydride source.
- Flinker, Mathias,Yin, Hongfei,Juhl, René W.,Eikeland, Espen Z.,Overgaard, Jacob,Nielsen, Dennis U.,Skrydstrup, Troels
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supporting information
p. 15910 - 15915
(2017/11/23)
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- Ruthenium-Catalyzed Deaminative Hydrogenation of Aliphatic and Aromatic Nitriles to Primary Alcohols
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The deaminative hydrogenation of nitriles towards alcohols is a useful reaction to transform nitriles into alcohols with NH3 as the sole byproduct. Using the simple and robust RuHCl(CO)(PPh3)3 complex as a catalyst, at low H2 pressures a series of aliphatic and aromatic nitriles could be transformed into the corresponding alcohols. Suitable solvent systems for these reactions were 1,4-dioxane/water and EtOH/water mixtures. In most cases, the selectivity for the alcohols was excellent, and the corresponding amines were formed only in trace amounts.
- Molnár, István Gábor,Calleja, Pilar,Ernst, Martin,Hashmi, A. Stephen K.,Schaub, Thomas
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p. 4175 - 4178
(2017/10/09)
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- Indium(III) Isopropoxide as a Hydrogen Transfer Catalyst for Conversion of Benzylic Alcohols into Aldehydes or Ketones via Oppenauer Oxidation
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Indium(III) isopropoxide [In(Oi-Pr)3] was applicable as an Oppenauer oxidation catalyst, and the conversion of primary or secondary alcohols into the corresponding aldehydes or ketones was promoted at room temperature using pivalaldehyde as an oxidant.
- Ogiwara, Yohei,Ono, Yuji,Sakai, Norio
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p. 4143 - 4148
(2016/11/26)
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- Reduction of aldehydes catalyzed by oxo-rhenium(V) complexes containing heterocyclic ligands
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This work describes the catalytic activity of several oxo-rhenium complexes containing the heterocyclic ligands 2-(2-hydroxy-5-methylphenyl)benzotriazole (Hhmpbta), 2-(2-hydroxyphenyl)benzothiazole (Hhpbt), 2-(2-hydroxyphenyl)benzoxazole (Hhpbo), 2-(2-hydroxyphenyl)-1H-benzimidazole (Hhpbi), isoquinoline-1-carboxylic acid (iqcH), and 4-methoxy-2-quinolinecarboxylic acid (mqcH) in the reduction of 4-nitrobenzaldehyde using phenylsilane as reducing agent. In general, all of the catalysts tested gave good to excellent yields of the 4-nitrobenzyl alcohol. Although, the best result was obtained with the catalytic system PhSiH3/[ReOBr2(hmpbta)(PPh3)] (5 mol %). This system was also applied to the reduction of a large variety of aldehydes, producing the corresponding primary alcohols in good to excellent yields and good chemoselectivity.
- Bernando, Joana R.,Florindo, Pedro R.,Wolff, Mariusz,Machura, Barbara,Fernandes, Ana C.
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p. 414 - 418
(2015/03/30)
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- Iron-catalyzed reduction of aromatic aldehydes with paraformaldehyde and H2O as the hydrogen source
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In this Letter, we report a novel, general, convenient, and inexpensive method for the reduction of aromatic aldehydes to the corresponding benzylic alcohols. Various aromatic aldehydes were reduced in good to excellent yields by using well-defined iron-complex as the catalyst precursor and using paraformaldehyde and water as the hydrogen source.
- Natte, Kishore,Li, Wanfang,Zhou, Shaolin,Neumann, Helfried,Wu, Xiao-Feng
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supporting information
p. 1118 - 1121
(2015/02/19)
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- Experimental and Mechanistic Understanding of Aldehyde Hydrogenation Using Au25 Nanoclusters with Lewis Acids: Unique Sites for Catalytic Reactions
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The catalytic activity of Au25(SR)18 nanoclusters (R = C2H4Ph) for the aldehyde hydrogenation reaction in the presence of a base, e.g., ammonia or pyridine, and transition-metal ions Mz+, such as Cu+, Cu2+, Ni2+ and Co2+, as a Lewis acid is studied. The addition of a Lewis acid is found to significantly promote the catalytic activity of Au25(SR)18/CeO2 in the hydrogenation of benzaldehyde and a number of its derivatives. Matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry in conjunction with UV-vis spectroscopy confirm the generation of new species, Au25-n(SR)18-n (n = 1-4), in the presence of a Lewis acid. The pathways for the speciation of Au24(SR)17 from its parent Au25(SR)18 nanocluster as well as its structure are investigated via the density functional theory (DFT) method. The adsorption of Mz+ onto a thiolate ligand -SR- of Au25(SR)18, followed by a stepwise detachment of -SR- and a gold atom bonded to -SR- (thus an Au-SR unit) is found to be the most likely mechanism for the Au24(SR)17 generation. This in turn exposes the Au13-core of Au24(SR)17 to reactants, providing an active site for the catalytic hydrogenation. DFT calculations indicate that Mz+ is also capable of adsorbing onto the Au13-core surface, producing a possible active metal site of a different kind to catalyze the aldehyde hydrogenation reaction. This study suggests, for the first time, that species with an open metal site like adducts [nanoparticle-M](z-1)+ or fragments Au25-n(SR)18-n function as the catalysts rather than the intact Au25(SR)18.
- Li, Gao,Abroshan, Hadi,Chen, Yuxiang,Jin, Rongchao,Kim, Hyung J.
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p. 14295 - 14304
(2015/11/28)
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- Bimetallic zinc complex-active species in coupling of terminal alkynes with aldehydes via nucleophilic addition/Oppenauer oxidation
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A mechanistic study on the zinc-promoted coupling between aldehydes and terminal alkynes via nucleophilic addition/Oppenauer oxidation using operando IR, XANES/EXAFS techniques and DFT calculations was demonstrated. It was determined that a bimetallic zinc complex was the active species. This journal is
- Yuan, Jiwen,Wang, Jing,Zhang, Guanghui,Liu, Chao,Qi, Xiaotian,Lan, Yu,Miller, Jeffrey T.,Kropf, A. Jeremy,Bunel, Emilio E.,Lei, Aiwen
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supporting information
p. 576 - 579
(2015/02/19)
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- Identification of a marine NADPH-dependent aldehyde reductase for chemoselective reduction of aldehydes
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A putative aldehyde reductase gene from Oceanospirillum sp. MED92 was overexpressed in Escherichia coli. The recombinant protein (OsAR) was characterized as a monomeric NADPH-dependent aldehyde reductase. The kinetic parameters Km and kcat of OsAR were 0.89 ± 0.08 mM and 11.07 ± 0.99 s-1 for benzaldehyde, 0.04 ± 0.01 mM and 6.05 ± 1.56 s-1 for NADPH, respectively. This enzyme exhibited high activity toward a variety of aromatic and aliphatic aldehydes, but no activity toward ketones. As such, it catalyzed the chemoselective reduction of aldehydes in the presence of ketones, as demonstrated by the reduction of 4-acetylbenzaldehyde or the mixture of hexanal and 2-nonanone, showing the application potential of this marine enzyme in such selective reduction of synthetic importance.
- Li, Guangyue,Ren, Jie,Wu, Qiaqing,Feng, Jinhui,Zhu, Dunming,Ma, Yanhe
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- A molecularly defined iron-catalyst for the selective hydrogenation of α,β-unsaturated aldehydes
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A selective iron-based catalyst system for the hydrogenation of α,β-unsaturated aldehydes to allylic alcohols is presented. Applying the defined iron-tetraphos complex [FeF(L)][BF4] (L=P(PhPPh 2)3) in the presence of trifluoroacetic acid a broad range of aldehydes are reduced in high yields using low catalyst loadings (0.05-1 mol %). Excellent chemoselectivity for the reduction of aldehydes in the presence of other reducible moieties, for example, ketones, olefins, esters, etc. is achieved. Based on the in situ detected hydride species [FeH(H 2)(L)]+ a catalytic cycle is proposed that is supported by computational calculations. Copyright
- Wienh?fer, Gerrit,Westerhaus, Felix A.,Junge, Kathrin,Ludwig, Ralf,Beller, Matthias
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supporting information
p. 7701 - 7707
(2013/07/11)
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- Fast and selective iron-catalyzed transfer hydrogenations of aldehydes
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An efficient iron-based catalyst system consisting of Fe(BF)4$6H2O and P(CH2CH2PPh2)3 [tetraphos, (PP3)] is presented for the highly selective transfer hydrogenation of aromatic, aliphatic, and a,b-unsaturated aldehydes. A wide range of substrates including aldehydes with other reducible functional groups gave the corresponding alcohols in good yields. Formic acid is applied as a cheap, environmentally benign and easy to handle hydrogen source. Notable features of the presented methodology are the fast reactions under mild conditions. Advantageously compared to most transfer hydrogenations, no stoichiometric amounts of base additives are required.
- Wienh?fer, Gerrit,Westerhaus, Felix A.,Junge, Kathrin,Beller, Matthias
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p. 156 - 159
(2013/10/01)
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- Searching for local biocatalysts: Bioreduction of aldehydes using plant roots of the Province of Cordoba (Argentina)
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A screening for the capacity of wild plants growing in the Province of Cordoba to bioreduce benzaldehyde was carried out. From this study, thirteen species showed quantitative reduction yields to benzyl alcohol, with Conium maculatum showing the best reduction efficiency. This plant was also tested against different substituted benzaldehydes, and quantitative yields of substituted benzylic alcohols were obtained, except for vanillin, where only 27% of vanillic alcohol was formed (main product: 2-methoxyphenol at a 73% yield). A scaling study of the reaction using C. maculatum and benzaldehyde was carried out, and it was observed that high substrate-catalyst relationships reduced the efficiency of the reaction due to side reactions of oxidation. The bioreduction method presented here permits substituted benzylic alcohols to be obtained using an environmentally friendly methodology, with excellent yields produced on a laboratory scale.
- Salvano, Mario S.,Cantero, Juan J.,Vazquez, Ana M.,Formica, Stella M.,Aimar, Mario L.
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experimental part
p. 16 - 21
(2012/02/01)
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- A convenient and general iron-catalyzed hydrosilylation of aldehydes
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A general and highly chemoselective hydrosilylation of aldehydes using iron catalysts is reported. Fe(OAc)2 in the presence of tricyclohexylphosphine as ligand and polymethylhydrosiloxane (PMHS) as an economical hydride source forms an efficient catalyst system for the hydrosilylation of a variety of aldehydes. Aryl, heteroaryl, alkyl and α,β-unsaturated aldehydes are successfully reduced to the corresponding primary alcohols. Broad substrate scope and high tolerance against several functional groups make the process synthetically useful.
- Shaikh, Nadim S.,Junge, Kathrin,Beller, Matthias
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p. 5429 - 5432
(2008/09/19)
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- Self-catalyzed oxidation of sulfides with hydrogen peroxide: A green and practical process for the synthesis of sulfoxides
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A self-catalyzed selective oxidation of sulfides to sulfoxides has been developed. The scope of the protocol is demonstrated in the selective oxidation of 17 different substrates. High yields and chemoselectivity (in general > 90 % ) are achieved in most cases.
- Shi, Feng,Tse, Man Kin,Kaiser, Hanns Martin,Beller, Matthias
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p. 2425 - 2430
(2008/09/19)
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- On water and in air: Fast and highly chemoselective transfer hydrogenation of aldehydes with iridium catalysts
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(Chemical Equation Presented) Water as solvent: A fast, selective, and high-yielding transfer hydrogenation of a wide range of aldehydes is achieved using IrIII catalysts containing simple ethylene-diamine (en) ligands (see scheme; Ts = p-toluenesulfonyl, TOF = turnover frequency). This procedure is suitable for aldehydes with a wide range of functional groups.
- Wu, Xiaofeng,Liu, Jianke,Li, Xiaohong,Zanotti-Gerosa, Antonio,Hancock, Fred,Vinci, Daniele,Ruan, Jiwu,Xiao, Jianliang
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p. 6718 - 6722
(2007/10/03)
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- NOVEL BENSOPHENONE DERIVATIVES OR SALTS THEREOF
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A benzophenone derivative represented by the following formula: whereinR1 represents, for example, an optionally substituted heterocyclic group, or a substituted phenyl group; Z represents, for example, an alkylene group; R2 represents, for example, a carboxyl group optionally protected with alkyl;R3 represents, for example, an optionally protected hydroxyl group; R4 represents, for example, an optionally substituted cycloalkyloxy group; and R5 represents, for example, a hydrogen atom, ???or a salt thereof has anti-arthritic activity, inhibits bone destruction caused by arthritis, and provides high safety and excellent pharmacokinetics and thus is useful as therapeutic agent for arthritis. These compounds have inhibitory effect on AP-1 activity and are useful as preventive or therapeutic agent for diseases in which excessive expression of AP-1 is involved.
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Page 129-130
(2010/02/07)
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- An efficient and highly selective deprotecting method for β-(trimethylsilyl)ethoxymethyl ethers
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A series of β-(trimethylsilyl)ethoxymethyl ethers were hydrolyzed to their corresponding alcohols in high yields by using a catalytic amount of CBr4 (15%) in MeOH under refluxing reaction conditions. The chemoselective deprotection between trialkylsilyl and β-(trimethylsilyl)-ethoxymethyl-protected alcohols can be achieved by using an alcohol with steric hindrance such as iPrOH. The selectivity also can be achieved in the CBr4/MeOH reaction mixture under ultrasonic reaction conditions.
- Chen, Ming-Yi,Lee, Adam Shih-Yuan
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p. 1384 - 1387
(2007/10/03)
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- Efficient o-trimethylsilylation of alcohols and phenols with trimethylsilyl azide catalyzed by tetrabutylammonium bromide under neat conditions
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A very efficient procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols is reported. The reactions were carried out under neat conditions with trimethylsilyl azide (TMSN3) and, when necessary, in the presence of a catalytic amount (20 mol %) of tetrabutylammonium bromide (TBABr) at 30 or 70 °C. Under catalytic conditions, the yields of the corresponding trimethylsilyl ethers were greater than 91%. This procedure also allows the selective protection of primary and secondary alcohols in the presence of tertiary ones.
- Amantini,Fringuelli,Pizzo,Vaccaro
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p. 6734 - 6737
(2007/10/03)
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- Spectral, kinetics, and redox studies on the transients formed on pulse radiolysis of aqueous solution of (4-methylthiophenyl)methanol
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Pulse radiolysis technique has been employed to investigate the nature and the redox properties of the transient species generated on radiolysis of aqueous solution of (4-methylthiophenyl)methanol (MTPM). Pulse radiolysis in 1,2-dichloroethane, reaction with specific one-electron oxidants (Cl2-, SO4-, Tl2+, Br) and reaction of OH radicals in acidic solution showed absorption bands at 320 and 545 nm; these are assigned to solute radical cation with positive charge on the benzene ring. OH-adduct was observed in neutral solution. The oxidation potential for MTPM/MTPM+ couple is determined to be 1.55 ± 0.04 V vs NHE. eaq- reacts with a bimolecular rate constant of 1.5 × 109 dm3 mol-1 s-1 and the transient absorption bands (λax = 320, 470 nm) are assigned to the solute radical anion. E0 value for MTPM/MTPM- couple is determined to be -1.84 ± 0.04 V vs NHE. The redox properties of the transient species formed on reaction with OH, H, and O- have been evaluated.
- Mohan,Mittal
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p. 1649 - 1659
(2007/10/03)
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- A simple and highly efficient deprotecting method for methoxymethyl and methoxyethoxymethyl ethers and methoxyethoxymethyl esters
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A series of methoxyethoxymethyl (MEM)- and methoxymethyl (MOM)-ethers and MEM-esters were hydrolyzed to their corresponding alcohols and carboxylic acids by a catalytic amount of CBr4 (10%) in iPrOH under refluxing reaction condition. The chemoselective hydrolysis between R3Si- and MEM-protected alcohols can be achieved by using different steric bulkness solvents such as MeOH or iPrOH.
- Shih-Yuan Lee, Adam,Hu, Yi-Jung,Chu, Shu-Fang
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p. 2121 - 2126
(2007/10/03)
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- An immobilized homogeneous catalyst for efficient and selective hydrogenation of functionalized aldehydes, alkenes, and alkynes
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An immobilized cationic rhodium(I) catalyst bearing the diphosphine 1,1′-bis(diisopropylphosphino)-ferrocene (DiPFc, 1) allows efficient and chemoselective hydrogenation of a range of functionalized aldehydes, as well as alkenes and alkynes, under mild conditions. This heterogenized catalyst system is convenient to prepare, is stable to air and moisture over extended periods, and is readily recycled.
- Burk,Gerlach,Semmeril
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p. 8933 - 8939
(2007/10/03)
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- 2-amino-1,3-propanediol compound and immunosuppressant
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2-Amino-1,3-propanediol compounds of the formula (I) STR1 wherein R is an optionally substituted straight- or branched carbon chain, an optionally substituted aryl, an optionally substituted cycloalkyl or the like, and R2, R3, R4 and R5 are the same or different and each is a hydrogen, an alkyl, an aralkyl, an acyl or an alkoxycarbonyl, pharmaceutically acceptable salts thereof and immunosuppressants comprising these compounds as active ingredients. The 2-amino-1,3-propanediol compounds of the present invention show immunosuppressive action and are useful for suppressing rejection in organ or bone marrow tranplantation, prevention and treatment of autoimmune diseases or as reagents for use in medicinal and pharmaceutical fields.
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- Correlation Analysis of Reactivity in the Oxidation of Substituted Benzyl Alcohols by Pyridinium Hydrobromide Perbromide
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Oxidation of monosubstituted benzyl alcohols by pyridinium hydrobromide perbromide (PHPB) leads to the formation of the corresponding benzaldehydes.The reaction is first order with respect to PHPB.Michaelis-Menten-type kinetics were observed with respect to he alcohol.The oxidation of α,α-dideuteriobenzyl alcohol indicated the presence of a substantial kinetic isotope effect.The rates of oxidation of meta- and para-substituted benzyl alcohols were correlated in terms of Taft's and Swain's dual substituent-parameter equations.The rates of the meta compounds correlated best with Taft's ?1 and ?0R values whereas the para-compounds showed an excellent correlation with Taft's ?1 and ?R + constants.The rates of the otho-substituted alcohols showed very good correlation with Charton's triparametric equation.The rate increased with an increase in the polarity of the solvent.A mechanism involving a rapid reversible formation of an intermediate complex and its subsequent decomposition in the rate-determining step has been proposed.
- Suri, Deepa,Banerji, Kalyan K.,Kothari, Seema
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p. 1734 - 1758
(2007/10/03)
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- Sulfonamides and uses
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Sulfonamides of formula I, in which the symbols R1 -R6, X, Y and n have the significance given in the description and which are in part novel compounds, and salts thereof, which can be used as active ingredients for the manufacture of medicaments for the treatment of circulatory disorders, especially hypertension, ischemia, vasospasms and angina pectoris, are described.
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- Penem derivatives
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There are provided compounds of formula I: STR1 wherein R1 is hydrogen or a C1 -C4 alkyl group either unsubstituted or substituted by one or more substituents chosen from a free or protected hydroxy or halogen atom; R2 is a free or esterified carboxy group or carboxylate anion; R3 and R4 are each independently hydrogen or organic group, X is --O--, STR2 --S--, Q is either (a") free or protected hydroxy, or (b") a C1 -C1 acyloxy, or (c") carbamoyloxy OCONH2, or (d") an optionally substituted heterocyclylthio group, or (e") an optionally substituted imido group, or (f") an optionally substituted quaternary ammonium group or (g") a halogen atom, A and the pharmaceutically or veterinarily acceptable salts thereof. There are provided also methods for preparing compounds of formula I. The compounds of formula I are useful as antibacterial agents.
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- Synthesis and antirhinovirus activity of 6-(dimethylamino)-2-(trifluoromethyl)-9-(substituted benzyl)-9H-purines
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A series of 6-(dimethylamino)-2-(trifluoromethyl)-9-(substituted benzyl)purines was synthesized and tested for antirhinovirus activity. Most of the compounds were synthesized by alkylation of 6-chloro-2-(trifluoromethyl)-9H-purine with the appropriate benzyl halide followed by displacement of the chloro group with dimethylamine. Alternatively, 6-(dimethylamino)-2-(trifluoromethyl)purine was alkylated with the appropriate benzyl halide. Although several different aryl substituents provided compounds with IC50's = 0.03 μM against rhinovirus serotype 1B, no congener was significantly more active than the parent 2. Twenty-three compounds were tested against 18 other serotypes, but none exhibited a uniform profile of activity.
- Kelley,Linn,Selway
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p. 1757 - 1763
(2007/10/02)
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- A CONVENIENT PROCEDURE FOR THE REDUCTIVE DESULPHURISATION OF THIOETHERS WITH NICKEL BORIDE
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Nickel boride, conveniently prepared in situ from nickel (II) chloride hexahydrate and sodium borohydride, cleanly desulphurises thioethers in excellent yields.
- Euerby, Melvin R.,Waigh, Roger D.
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p. 779 - 784
(2007/10/02)
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- 1-Substituted aralkyl imidazoles
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This disclosure describes novel aralkyl imidazoles, their acid addition salts, their metal complex salts and processes for their preparation. These compounds possess biological activity and in particular are useful as systemic protectant/eradicant fungicidal agents for controlling plant diseases caused by fungi and as plant growth regulators. The metal complex salts of these compounds are particularly useful in their ability to reduce undesirable plant growth regulatory activity and phytotoxicity while retaining their ability for controlling plant diseases caused by fungi.
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