- Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
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Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
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supporting information
p. 9029 - 9039
(2021/06/28)
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- Ruthenium-catalyzed ester reductions applied to pharmaceutical intermediates
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Ruthenium pincer complexes were synthesized and used for catalytic ester reductions under mild conditions (~5 bar of hydrogen). An experimental design approach was used to optimize the conditions for yield, purity, and robustness. Evidence for the catalytically active ruthenium dihydride species is presented. Observed intermediates and side products, as well as time-course data, were used to build mechanistic insight. The optimized procedure was further demonstrated through scaled-up reductions of two pharmaceutically relevant esters, both in batch and continuous flow.
- Shaalan, Youssef,Boulton, Lee,Jamieson, Craig
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supporting information
p. 2745 - 2751
(2020/11/30)
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- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- Hydrosilylation of carbonyl and carboxyl groups catalysed by Mn(i) complexes bearing triazole ligands
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Manganese(i) complexes bearing triazole ligands are reported as catalysts for the hydrosilylation of carbonyl and carboxyl compounds. The desired reaction proceeds readily at 80 °C within 3 hours at catalyst loadings as low as 0.25 to 1 mol%. Hence, good to excellent yields of alcohols could be obtained for a wide range of substrates including ketones, esters, and carboxylic acids illustrating the versatility of the metal/ligand combination.
- Martínez-Ferraté, Oriol,Chatterjee, Basujit,Werlé, Christophe,Leitner, Walter
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p. 6370 - 6378
(2019/11/20)
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- Nickel-Catalyzed Stereodivergent Synthesis of E- and Z-Alkenes by Hydrogenation of Alkynes
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A convenient protocol for stereodivergent hydrogenation of alkynes to E- and Z-alkenes by using nickel catalysts was developed. Simple Ni(NO3)2?6 H2O as a catalyst precursor formed active nanoparticles, which were effective for the semihydrogenation of several alkynes with high selectivity for the Z-alkene (Z/E>99:1). Upon addition of specific multidentate ligands (triphos, tetraphos), the resulting molecular catalysts were highly selective for the E-alkene products (E/Z>99:1). Mechanistic studies revealed that the Z-alkene-selective catalyst was heterogeneous whereas the E-alkene-selective catalyst was homogeneous. In the latter case, the alkyne was first hydrogenated to a Z-alkene, which was subsequently isomerized to the E-alkene. This proposal was supported by density functional theory calculations. This synthetic methodology was shown to be generally applicable in >40 examples and scalable to multigram-scale experiments.
- Murugesan, Kathiravan,Bheeter, Charles Beromeo,Linnebank, Pim R.,Spannenberg, Anke,Reek, Joost N. H.,Jagadeesh, Rajenahally V.,Beller, Matthias
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p. 3363 - 3369
(2019/06/28)
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- Mechanistic Study of Palladium-Catalyzed Hydroesterificative Copolymerization of Vinyl Benzyl Alcohol and CO
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The copolymerization of vinyl benzyl alcohol (VBA) and carbon monoxide (CO) to give a new polyester poly(VBA-CO) has been achieved via palladium-catalyzed hydroesterification. Reaction conditions involve moderate temperatures, moderate to low CO pressures, and low catalyst loadings to give a low molar mass (Mn 3-4 kg/mol) polymer as a 2:1 mixture of linear to branched repeat units. The polymer molar mass increase is consistent with a step-growth polymerization mechanism, and ester yields of >97% are achieved within 24 h. However, increases in Mn cease beyond 16 h. Control experiments indicate that the degree of polymerization is limited due to a combination of side reactions such as alcoholic end-group oxidation, hydroxycarbonylation, and alcohol acetylation, which lead to the degradation of monomeric and polymeric end groups. When a less promiscuous substrate is used such as 10-undecenol, higher molar masses (Mn 16 kg/mol) are achieved. This method has the potential to be a mild route to new polyester architectures with appropriate mitigation of side reactions.
- Yee, Gereon M.,Wang, Tong,Hillmyer, Marc A.,Tonks, Ian A.
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p. 1778 - 1786
(2019/04/30)
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- Polymer-Anchored Bifunctional Pincer Catalysts for Chemoselective Transfer Hydrogenation and Related Reactions
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A series of polymer-supported cooperative PC(sp3)P pincer catalysts was synthesized and characterized. Their catalytic activity in the acceptorless dehydrogenative coupling of alcohols and the transfer hydrogenation of aldehydes with formic acid as a hydrogen source was investigated. This comparative study, examining homogeneous and polymer-tethered species, proved that carefully designing a link between the support and the catalytic moiety, which takes into consideration the mechanism underlying the target transformation, might lead to superior heterogeneous catalysis.
- Mujahed, Shrouq,Valentini, Federica,Cohen, Shirel,Vaccaro, Luigi,Gelman, Dmitri
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p. 4693 - 4699
(2019/10/28)
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- Nickel boride mediated chemoselective deprotection of 1,1-diacetates to aldehydes and deprotection with concomitant reduction to alcohols at ambient temperature
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A variety of 1,1-diacetates have been chemoselectively and efficiently deprotected to the corresponding aldehydes as well as deprotected and concomitantly reduced to the corresponding alcohols in high yields at ambient temperature with nickel boride generated in situ using different molar ratios of sodium borohydride and nickel (II) chloride in methanol at room temperature. Deprotection and reduction of a variety of aromatic, aliphatic and heterocyclic acylals have been achieved efficiently. Mild reaction conditions, easy work-up, high yields and chemoselectivity demonstrate the efficiency of this new method.
- Bartwal, Gaurav,Saroha, Mohit,Khurana, Jitender.M.
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- Palladium Nanoparticle Loaded Bifunctional Silica Hybrid Material: Preparation and Applications as Catalyst in Hydrogenation Reactions
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Bifunctional mesoporous silica was prepared by co-condensation of tetraethyl orthosilicate (TEOS) with functionalized organosilanes containing azides or alkoxyamines. Orthogonal functional groups at the particles were selectively addressed in subsequent chemical modifications through “click”-chemistry (“click to ligand” strategy) and radical nitroxide exchange. Palladation with PdCl2 delivered Pd nanoparticle-loaded silica material bearing sulfoxides and additional aminoamides as stabilizing ligands by means of in situ reduction of the PdII-salt. These functional particles were successfully applied to the hydrogenation of alkynes and alkenes. Aldehyde hydrodeoxygenation and benzyl ether cleavage were achieved with these hybrid catalysts under mild conditions. Particles were analyzed by IR, TEM/STEM, EDX, and solid-state NMR spectroscopy.
- Surmiak, Sabrina K.,Doerenkamp, Carsten,Selter, Philipp,Peterlechner, Martin,Sch?fer, Andreas H.,Eckert, Hellmut,Studer, Armido
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p. 6019 - 6028
(2017/05/05)
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- An Efficient, Stable and Reusable Palladium Nanocatalyst: Chemoselective Reduction of Aldehydes with Molecular Hydrogen in Water
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Palladium nanoparticles (Pd-BNP) stabilized by a binaphthyl-backbone can be efficiently used for the chemoselective reduction of aldehydes in the presence of hydrogen at room temperature in water. The Pd-BNP catalyst is easily recovered and reused for five catalytic cycles. (Figure presented.).
- Kotha, Surya Srinivas,Sharma, Nidhi,Sekar, Govindasamy
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supporting information
p. 1694 - 1698
(2016/10/13)
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- Tandem catalytic C(sp3)-H amination/sila-sonogashira-hagihara coupling reactions with iodine reagents
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A new tandem C-N and C-C bond-forming reaction has been achieved through RhII/Pd0 catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by-product is used as a coupling partner. The overall process demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations. I(003) is a double agent: A tandem C-N and C-C bond-forming reaction has been achieved through RhII/Pd0 catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by-product is used as a coupling partner. The overall process affords complex building blocks with high yields, and demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations.
- Buendia, Julien,Darses, Benjamin,Dauban, Philippe
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supporting information
p. 5697 - 5701
(2015/06/16)
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- Role of sterically demanding chiral dirhodium catalysts in site-selective C-H functionalization of activated primary C-H bonds
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The influence of sterically demanding dirhodium tetracarboxylate catalysts on the site selectivity of C-H functionalization by means of rhodium carbene-induced C-H insertion is described. The established dirhodium tetraprolinate-catalyzed reactions of aryldiazoacetates cause preferential C-H functionalization of secondary C-H bonds as a result of competing steric and electronic effects. The sterically more demanding dirhodium tetrakis(triarylcyclopropanecarboxylate) catalysts, exemplified by dirhodium tetrakis[(R)-(1-(biphenyl)-2,2-diphenylcyclopropanecarboxylate)] [Rh 2(R-BPCP)4], favor C-H functionalization of activated primary C-H bonds. Highly site-selective and enantioselective C-H functionalization of a variety of simple substrates containing primary benzylic, allylic, and methoxy C-H bonds was achieved with this catalyst. The utility of this approach has been demonstrated by the late-stage primary C-H functionalization of (-)-∝-cedrene and a steroid.
- Qin, Changming,Davies, Huw M. L.
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supporting information
p. 9792 - 9796
(2014/07/22)
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- Electrophilicity and nucleophilicity of commonly used aldehydes
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The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
- Pratihar, Sanjay
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p. 5781 - 5788
(2014/07/22)
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- Oxidative degradation of fragrant aldehydes. Autoxidation by molecular oxygen
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The oxidative degradation of fragrant aldehydes by molecular oxygen has been investigated. The oxygen consumption was monitored and the bond dissociation energy (BDE) of the aldehyde C(O)-H bond were calculated by DFT method. The oxidation products were identified by GC/MS. The different pathways accounting for the oxidative degradation are discussed. The main product is the acid, beside the formate ester. Both oxidation products result from the Baeyer-Villiger reaction involving a peracid R(CO)OOH whereas minor products arise from the hydroperoxide ROOH intermediate derived either from the acyl peroxy radical, R(CO)OO or from the decarboxylation of the peracid RC(O)OOH.
- Marteau,Ruyffelaere,Aubry,Penverne,Favier,Nardello-Rataj
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p. 2268 - 2275
(2013/04/10)
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- Facile and efficient hydrolysis of organic halides, epoxides, and esters with water catalyzed by ferric sulfate in a PEG1000-DAIL[BF 4]/toluene temperature-dependent biphasic system
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An efficient and environmentally friendly procedure for the hydrolysis of organic halides, epoxides, and esters with water catalyzed by ferric sulfate in a PEG1000-DAIL[BF4]/toluene temperature-dependent biphasic system has been developed. The product can be easily isolated by a simple decantation, and the catalytic system can be recycled and reused without loss of catalytic activity.
- Hu, Yu Lin,Jiang, Hui,Zhu, Jie,Lu, Ming
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experimental part
p. 292 - 298
(2011/04/21)
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- Discovery and development of thiazolo[3,2-a]pyrimidinone derivatives as general inhibitors of Bcl-2 family proteins
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A class of compounds with a common thiazolo[3,2-a]pyrimidinone motif has been developed as general inhibitors of Bcl-2 family proteins. The lead compound was originally identified in a random screening of a small compound library using a fluorescence polarization-based competitive binding assay. Its binding to the Bcl-xL protein was further confirmed by 15N-HSQC NMR experiments. Structural modifications on the lead compound were guided by the outcomes of molecular modeling studies. Among the 42 compounds obtained, a number of them exhibited much improved binding affinities to Bcl-2 family proteins as compared to the lead compound. The most potent compound, BCL-LZH-40, inhibited the binding of BH3 peptides to Bcl-xL, Bcl-2, and Mcl-1 with inhibition constants (Ki) of 17, 534, and 200nM, respectively. Keeping it in the family! Compounds with a common thiazolo[3,2-a]pyrimidinone motif have been developed as general inhibitors of Bcl-2 family proteins. The lead compound BCL-LZH-01 (shown in green) was identified as a Bcl-xL protein binder in a random screening using a fluorescence polarization-based binding assay, and further confirmed by 15N-HSQC NMR experiments. Of the 42 derivative described, BCL-LZH-40 (shown in blue) is the most potent, inhibiting the binding of BH3 peptides to Bcl-xL, Bcl-2, and Mcl-1 with inhibition constants (Ki) of 17, 534, and 200nM, respectively.
- Zhou, Bingcheng,Li, Xun,Li, Yan,Xu, Yaochun,Zhang, Zhengxi,Zhou, Mi,Zhang, Xinglong,Liu, Zhen,Zhou, Jiahai,Cao, Chunyang,Yu, Biao,Wang, Renxiao
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experimental part
p. 904 - 921
(2012/01/06)
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- Making a difference on excited-state chemistry by controlling free space within a nanocapsule: Photochemistry of 1-(4-alkylphenyl)-3-phenylpropan-2-ones
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The free space within a reaction cavity plays a determining role during the excited-state reaction of 1-(4-alkylphenyl)-3-phenylpropan-2-ones included within a capsule formed by two molecules of a deep cavity cavitand. By controlling the free space within the reaction cavity through remote alkyl substitution on the reactant ketone it is possible to control the yield of the rearrangement product shown above.
- Sundaresan, Arun Kumar,Ramamurthy
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p. 3575 - 3578
(2008/02/12)
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- Multi-armed, TEMPO-functionalized unimolecular initiators for starburst dendrimer synthesis via stable free radical polymerization. 1. Tri azo-functionalized unimer
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The synthesis of azobenzene-functionalized multi-armed unimolecular initiators or "unimers" that can be polymerized using styrene or styrenic derivatives via TEMPO (2,2,6,6-tetramethylpiperidenyl-1-oxyl) mediated stable free radical polymerization (SFRP) is described. The unimers are composed of an azobenzene-functionalized core and a TEMPO-modified unit. Homopolymers and copolymers of styrene and acetoxystyrene were synthesized using the mono-and trifunctionalized unimers as initiators under bulk conditions with average molecular weights and polydispersities reported. The studies lay the groundwork for further investigations involving SFRP towards building a light harvesting system by introducing chromophores onto the polymer chains for capturing light and thence transferring it to the azobenzene core.
- Abdallah, Dalia,Ghani, Mohmad Asri Abd,Cunningham, Michael F.,Kazmaier, Peter M.,Keoshkerian, Barkev,Buncel, Erwin
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p. 1393 - 1402
(2007/10/03)
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- Nighttime tropospheric chemistry: Kinetics and product studies in the reaction of 4-Alkyl- and 4-Alkoxytoluenes with NO3 in gas phase
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Alkylbenzenes are important constituents of gasoline and industrial solvents and contribute to the formation of tropospheric ozone. The removal of these compounds from the troposphere is due to reaction with OH during the day and with NO3 during the night. Five para-substituted toluenes are reacted with the nitrate radical in gas phase. Samples to be used for product analysis were preconcentrated and analyzed by GC-MSD analysis with the use of a reference curve. The yields of methanol, ethanol, and formaldehyde were determined by FTIR analysis of the reaction mixture in the chamber. Carbonyl compounds, benzyl alcohols, and nitroderivatives were formed. In the case of the alkoxytoluenes, products were also an alkanol, benzyl alcohols, and nitrophenols. Indirect rate constants measurements were performed by comparing by FTIR measurements the decay of the aromatic compound under investigation to that of a reference compound, with a known rate constant for the reaction with NO3 added to the gas mixture. Wall loss constants were evaluated by FTIR. A Hammett correlation with ρ = - 4.3 ± 0.6; r2-= 0.87 was obtained. This and the kinetic isotope effect of 1.5-1.8 suggest a reaction mechanism occurring via an addition-elimination pathway.
- Bolzacchini, Ezio,Meinardi, Simone,Orlandi, Marco,Rindone, Bruno,Hjorth, Jens,Restelli, Gianbattista
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p. 461 - 468
(2007/10/03)
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- Synthesis and characterization of stilbene derivatives for possible incorporation as smart additives in polymers used as packaging films
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Several series of stilbene derivatives for possible use as smart additives in polymers used as packaging films have been prepared and characterized. Differential scanning calorimetry was performed on some of the stilbenes in order to determine any liquid crystal properties. Those compounds which had multiple phase transitions were also shown to have two liquid crystalline phases according to optical microscopy.
- Day, Gary M.,Howell, Owen T.,Metzler, Michael R.,Woodgate, Paul D.
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p. 425 - 434
(2007/10/03)
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- Carbonyl reductase activity exhibited by pig testicular 20β- hydroxysteroid dehydrogenase
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The carbonyl reductase activity exhibited by pig testicular 20β- hydroxysteroid dehydrogenase (20β-HSD) was examined using a recombinant enzyme. Kinetic parameters were obtained for 48 carbonyl group-containing substrates, including aromatic aldehydes, aromatic ketones, cycloketones, quinones, aliphatic aldehydes and aliphatic ketones. 20β-HSD showed a high affinity towards quinones, such as 9,10-phenanthrenequinone, α- naphthoquinone and menadione (K(m) values of 4, 2 and 5 μM, respectively), and the substrate utilization efficiency (V(max)/K(m)) of the enzyme against these quinones was very high. Cyclohexanone and 2-methylcyclohexanone were also reduced with a high V(max)/K(m) value, but not cyclopentanone or 2- methylcyclopentanone. Various aromatic aldehydes and ketones including benzaldehyde- and acetophenone-derivatives were reduced by 20β-HSD. Especially, 4-nitrobenzaldehyde and 4-nitroacetophenone were reduced with high V(max)/K(m) values in the related compounds. The enzyme also reduced the pyridine-derivatives, 2-, 3-, and 4-benzoylpyridine, with the V(max)/K(m) value for 2-benzoylpyridine being the highest. 20β-HSD reduced aliphatic aldehydes and aliphatic ketones, but was more effective on the former. The correlation between the structure of carbonyl compounds and their substrate V(max)/K(m) is discussed.
- Nakajin, Shizuo,Tamura, Fumihiro,Takase, Noriko,Toyoshima, Satoshi
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p. 1215 - 1218
(2007/10/03)
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- Novel Reduction of Carboxylic Acids, Esters, Amides and Nitriles Using Samarium Diiodide in the Presence of Water
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Aromatic carboxylic acids, esters, amides, nitriles, chlorides, ketones and nitro compounds were rapidly reduced by the samarium diiodide-H2O system to the corresponding products at room temperature in good yields.
- Kamochi, Yasuko,Kudo, Tadahiro
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p. 1495 - 1498
(2007/10/02)
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- Synthesis of 4-Alkyl-2-iodosobenzoic Acids: Potent Catalysts for the Hydrolysis of Phosphorous Esters
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The syntheses of five new 4-alkyl-2-iodosobenzoic acids (3) are described.The iodine atom was introduced by ortho-directed lithiation of 4-alkylbenzyl alcohols followed by treatment with I2.The catalytic effectiveness of each of the products in the hydrolysis of 4-nitrophenyl diphenyl phosphate in microemulsions was studied.The 4-methyl- and 4-ethyl-substituted products were each found to be significantly better catalysts than the standard nonalkylated 2-iodosobenzoic acid (3, R=H).These results would indicate that microemulsions of these materials may find use in detoxification procedures.
- Panetta, Charles A.,Garlick, Stephanie M.,Durst, H. Dupont,Longo, Frederick R.,Ward, J. Richard
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p. 5202 - 5205
(2007/10/02)
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- The Hammett Relationship in the Reduction of Aldehydes with 2-Propanol by Catalysis with Hydrous Zirconium Oxide
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A linear correlation of the Hammett relationship was obtained for a catalytic reduction of substituted benzaldehydes with 2-propanol with hydrous zirconium oxide.The reaction constant p was 1.35, indicating that the electronic effect on the reaction is larger than on the standard one.
- Shibagaki, Makoto,Kuno, Hideyuki,Takahashi, Kyoko,Matsushita, Hajime
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p. 4153 - 4154
(2007/10/02)
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- Studies on the Regioselectivities in the Oxidation of Simple Alkyl Aromatic Hydrocarbons by Molecular Oxygen
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The products of the autoxidation of various simple alkyl aromatic hydrocarbons were reduced by LiAlH4, and the alcohols formed were determined by gas chromatography.In the cases of 2-phenylbutane, 3-phenylpentane, and 2-p-tolylbutane a considerable fragmentation of the intermediate tertiary alkoxy radicals was proved.On the basis of the analytical results relative reaction rates of the various C-H bonds in the hydrocarbons studied were calculated.It is shown that the attack at C-H bonds which are not activated by the aromatic nucleus cannot be neglected and may be of great importance for the kinetics of the oxidation of alkyl aromatic hydrocarbons.
- Pritzkow, Wilhelm,Thomas, Gerda,Willecke, Lothar
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p. 847 - 851
(2007/10/02)
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- The Autoxidation of Some Asymmetric p-Dialkylbenzenes
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The autoxidation mixtures of p-ethyltoluene, p-isopropyltoluene, and p-ethylcumene were reduced with lithium alanate and the alcohols formed analyzed gaschromatographically.From the results obtained the relative reaction rates of primary, secondary, and tertiary C-H-bonds with the chain-propagating peroxy radicals were estimated to 1:7:15.
- Blau, K.,Pritzkow, W.
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- ipso Nitration. XXIII. Reactions of cyclohexadiene adducts from nitration of 4-ethyltoluene in acetic anhydride
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The diastereoisomers of 4-ethyl-1-methyl-4-nitrocyclohexa-2,5-dienyl acetate (1) and 1-ethyl-4-methyl-4-nitrocyclohexa-2,5-dienyl acetate (2) are stereospecifically reduced to the corresponding nitrocyclohexadienols with aluminum hydride.Each dienol is stereospecifically methylated to the corresponding methyl ether with methyl iodide, silver oxide, and potassium hydroxide.Acid-catalysed solvolysis of the acetates 1 and 2 results in the substitution of the acetate moiety by other nucleophiles and these reactions are not stereospecific.The products of rearomatization of dienyl acetates, dienols and dienyl methyl ethers depend on the acidity and ionizing power of the solvents and are readily explained in terms of reactions involving a nitrocyclohexadienyl cation or acetoxy- (hydroxy-, methoxy-)cyclohexadienyl cation as key intermediates.In the 4-acetoxy-4-alkylcyclohexadienyl cation 1,2-migration of the acetoxyl group is more rapid then alkyl migration, but 1,2-alkyl migration is faster then migration of the hydroxyl or methoxyl groups in the corresponding cations. 1-Ethyl-4-methoxy-4-methylcyclohexa-2,5-dien-1-ol and 4-ethyl-3-nitrotoluene are significant minor products in the solvolysis of 1-ethyl-4-methyl-4-nitrocyclohexa-2,5-dien-1-ol in aqueous methanol.Nitration of p-ethyltoluene in the presence of sulfuric acid or in trifluoracetic anhydride gives a mixture of 4-ethyl-2-nitro- and 4-ethyl-3-nitrotoluene in a 2:1 ratio.
- Fischer, Alfred,Henderson, George N.
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p. 2314 - 2327
(2007/10/02)
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