- A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
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We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
- Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
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p. 4617 - 4629
(2020/05/19)
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- Method for reducing carboxylic acid into aldehyde compounds
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The invention discloses a method for reducing carboxylic acid into aldehyde compounds, and belongs to the field of organic chemical synthesis. Specifically, in an argon atmosphere, a carboxylic acid compound, a transition metal nickel compound, an anhydride compound, a ligand and a reducing agent are dissolved in an organic solvent, the mixture is heated and subjected to stirring reaction, after the reaction is finished, the pressure is reduced to remove the organic solvent, column chromatography separation is performed, and various aldehyde compounds are obtained. The method has the advantages of simple synthesis steps, mild reaction conditions, simplicity and easiness in operation, realization of successful reduction of the carboxylic acid compound into the aldehyde organic compounds, small use amount of the reaction catalyst, high product yield, and provision of a new approach for reduction of the carboxylic acid compound into the aldehyde compounds. Compared with a conventional method, the method has the advantages that raw materials are cheap, easy to obtain and environmentally friendly, substrate universality and functional group compatibility are improved, and the method hascertain innovativeness and unique research significance in organic synthesis methodology.
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Paragraph 0051-0054
(2020/02/27)
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- A Simple, Mild and General Oxidation of Alcohols to Aldehydes or Ketones by SO2F2/K2CO3 Using DMSO as Solvent and Oxidant
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A practical, general and mild oxidation of primary and secondary alcohols to carbonyl compounds proceeds in yields of up to 99% using SO2F2 as electrophile in DMSO as both the oxidant and the solvent at ambient temperature. No moisture- and oxygen-free conditions are required. Stoichiometric amount of inexpensive K2CO3, which generates easy to separate by-products, is used as the base. Thus, 5-gram scale runs proceeded in nearly quantitative yields by a simple filtration as the work-up. The use of a polar solvent such as DMSO, which usually promotes competing Pummerer rearrangement, is also noteworthy. This protocol is compatible with a variety of common N-, O-, and S-functional groups on (hetero)arene, alkene and alkyne substrates (68 examples). The protocol was applied (99% yield) to a formal synthesis of the important cholesterol-lowering drug Rosuvastatin. (Figure presented.).
- Zha, Gao-Feng,Fang, Wan-Yin,Leng, Jing,Qin, Hua-Li
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supporting information
p. 2262 - 2267
(2019/04/17)
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- An Engineered Alcohol Oxidase for the Oxidation of Primary Alcohols
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Structure-guided directed evolution of choline oxidase has been carried out by using the oxidation of hexan-1-ol to hexanal as the target reaction. A six-amino-acid variant was identified with a 20-fold increased kcat compared to that of the wild-type enzyme. This variant enabled the oxidation of 10 mm hexanol to hexanal in less than 24 h with 100 % conversion. Furthermore, this variant showed a marked increase in thermostability with a corresponding increase in Tm of 20 °C. Improved solvent tolerance was demonstrated with organic solvents including ethyl acetate, heptane and cyclohexane, thereby enabling improved conversions to the aldehyde by up to 30 % above conversion for the solvent-free system. Despite the evolution of choline oxidase towards hexan-1-ol, this new variant also showed increased specific activities (by up to 100-fold) for around 50 primary aliphatic, unsaturated, branched, cyclic, benzylic and halogenated alcohols.
- Heath, Rachel S.,Birmingham, William R.,Thompson, Matthew P.,Taglieber, Andreas,Daviet, Laurent,Turner, Nicholas J.
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p. 276 - 281
(2019/01/04)
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- A Transition-Metal-Free One-Pot Cascade Process for Transformation of Primary Alcohols (RCH2OH) to Nitriles (RCN) Mediated by SO2F2
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A new transition-metal-free one-pot cascade process for the direct conversion of alcohols to nitriles was developed without introducing an “additional carbon atom”. This protocol allows transformations of readily available, inexpensive, and abundant alcohols to highly valuable nitriles.
- Jiang, Ying,Sun, Bing,Fang, Wan-Yin,Qin, Hua-Li
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supporting information
p. 3190 - 3194
(2019/05/21)
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- Pd-Catalyzed Dehydrogenative Oxidation of Alcohols to Functionalized Molecules
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A dehydrogenative oxidation reaction of primary alcohols to aldehydes catalyzed by a simple Pd/Xantphos catalytic system was developed under an argon or nitrogen atmosphere without oxidizing agents or hydrogen acceptors. The reaction product could be easily changed: under aerobic conditions, esters were obtained in aprotic solvents, whereas the corresponding carboxylic acids were produced in aqueous media. These oxidizing processes were applicable to the efficient synthesis of useful nitrogen-containing heterocyclic compounds such as indole, quinazoline, and benzimidazole via intramolecular versions of this reaction from amino alcohols.
- Mori, Takamichi,Ishii, Chihiro,Kimura, Masanari
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supporting information
p. 1709 - 1717
(2019/09/04)
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- Synthesis of Renewable meta-Xylylenediamine from Biomass-Derived Furfural
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We report the synthesis of biomass-derived functionalized aromatic chemicals from furfural, a building block nowadays available in large scale from low-cost biomass. The scientific strategy relies on a Diels–Alder/aromatization sequence. By controlling the rate of each step, it was possible to produce exclusively the meta aromatic isomer. In particular, through this route, we describe the synthesis of renewably sourced meta-xylylenediamine (MXD). Transposition of this work to other furfural-derived chemicals is also discussed and reveals that functionalized biomass-derived aromatics (benzaldehyde, benzylamine, etc.) can be potentially produced, according to this route.
- Scodeller, Ivan,Mansouri, Samir,Morvan, Didier,Muller, Eric,de Oliveira Vigier, Karine,Wischert, Raphael,Jér?me, Fran?ois
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supporting information
p. 10510 - 10514
(2018/08/17)
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- Oxidative cyanide-free cyanation on arylboronic acid derivatives using aryl/heteroaryl thiocyanate using novel IL-PdCl4 catalyst under mild condition
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An efficient and simple method is reported for the cyanation on arylboronic acid using various simple/indole thiocyanates using a new IL-PdCl4 catalyst. The cascade process involves a coupling reaction without any additive to give a wide range of cyanide derivatives. Cyanation on various arylboronic acids underwent smoothly affording the corresponding arylnitriles in good to high yields.
- Vaghasiya, Beena K.,Satasia, Shailesh P.,Thummar, Rahul P.,Kamani, Ronak D.,Avalani, Jemin R.,Sapariya, Nirav H.,Raval, Dipak K.
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p. 507 - 515
(2018/05/15)
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- Correlation analysis of reactivity in the oxidation of substituted benzyl alcohols by benzimidazolium dichromate - A kinetic and mechanistic aspects
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The oxidation of a number of para- and meta-substituted benzyl alcohols by benzimidazolium dichromate (BIDC), in dimethyl sulphoxide, leads to the formation of the corresponding benzaldehydes. The reaction is first order with respect to each BIDC and alcohol. The reaction is catalyzed by hydrogen ions and the dependence has the form kobs = a + b[H+]. The oxidation of [1,1-2H2]benzyl alcohol exhibited the presence of a substantial kinetic isotope effect. The rates of the oxidation of meta-substituted benzyl alcohols correlated best with Taft's σ1 and σR0 constants. The para-substituted compounds exhibited excellent correlation with σ1 and σRBA values. The polar reaction constants are negative. The rate of oxidation of benzyl alcohol was determined in nineteen organic solvents. An analysis of the solvent effect by multiparametric equations indicated the greater importance of the cation-solvating power of the solvents. Suitable mechanisms have been discussed.
- Kumar, Pravesh,Panday, Dinesh,Kothari, Seema
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p. 1207 - 1215
(2020/06/27)
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- PRODUCTION OF XYLENE DERIVATIVES
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The present invention relates to the production of xylene derivatives from furfural and its derivatives. The invention describes new routes for converting furfural and its derivatives into xylene derivatives including novel intermediates.
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Page/Page column 21; 22; 23; 24
(2017/07/06)
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- Visible-Light-Promoted Nickel- and Organic-Dye-Cocatalyzed Formylation Reaction of Aryl Halides and Triflates and Vinyl Bromides with Diethoxyacetic Acid as a Formyl Equivalent
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A simple formylation reaction of aryl halides, aryl triflates, and vinyl bromides under synergistic nickel- and organic-dye-mediated photoredox catalysis is reported. Distinct from widely used palladium-catalyzed formylation processes, this reaction proceeds by a two-step mechanistic sequence involving initial in situ generation of the diethoxymethyl radical from diethoxyacetic acid by a 4CzIPN-mediated photoredox reaction. The formyl-radical equivalent then undergoes nickel-catalyzed substitution reactions with aryl halides and triflates and vinyl bromides to form the corresponding aldehyde products. Significantly, besides aryl bromides, less reactive aryl chlorides and triflates and vinyl halides serve as effective substrates for this process. Since the mild conditions involved in this reaction tolerate a plethora of functional groups, the process can be applied to the efficient preparation of diverse aromatic aldehydes.
- Huang, He,Li, Xiangmin,Yu, Chenguang,Zhang, Yueteng,Mariano, Patrick S.,Wang, Wei
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supporting information
p. 1500 - 1505
(2017/02/05)
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- Chloramine-T-mediated oxidation of benzylic alcohols using indium(III) triflate
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The efficient oxidation of benzylic alcohols to carbonyl compounds was performed using chloramine-T and a catalytic amount of indium(III) triflate. The primary benzylic alcohols were converted to the corresponding aldehydes in a good yield, and the secondary benzylic alcohols were oxidized to ketones in a high yield. The optimized reaction conditions required 0.3eq of indium(III) triflate and the use of acetonitrile as a solvent.
- Nakahara, Kazuhide,Kitazawa, Chie,Mineno, Tomoko
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p. 801 - 804
(2017/08/09)
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- One-pot Three-component Synthesis of Furan-based Heterocycles from Benzyl Halides
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An efficient and a novel approach for the synthesis of furochromene and furopyran scaffolds are described. Benzyl halides undergo oxidation in Kornblum conditions to give the corresponding aldehydes, which in turn undergo [4?+?1] cycloaddition reaction with isocyanide to afford the corresponding furan derivatives. The significant attraction of this protocol is simple procedure, mild reaction condition, and good yield.
- Beerappa, Mallappa,Shivashankar, Kalegowda
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p. 2197 - 2205
(2017/07/25)
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- Method for preparing aldehyde/ketone by catalyzing alcohol oxidation with ferric salt
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The invention provides a method for preparing aldehyde/ketone by catalyzing alcohol oxidation with a ferric salt. The method comprises the following steps: mixing a compound shown in a formula (I) of a substrate, a ferric salt catalyst, a cocatalyst TEMPO (tetramethylpiperidinooxy), an amino acid ligand and a solvent; carrying out return flow agitation in an oxygen or air atmosphere for 1 to 60 h; then post-processing a reaction solution to obtain a product, namely a compound shown in a formula (II). According to the method provided by the invention, the ferric acid which is low in cost, easily available and environment-friendly is used as the catalyst; amino acids which are rich in resource, low in cost, easily available and easy to modify in a natural field are used as the ligand; the reaction substrate is high in applicability; first-grade benzyl alcohol, second-grade benzyl alcohol, allyl alcohol, heterocyclic aromatic alcohols and the like can be converted into corresponding aldehyde/ketone at high yield by adopting an oxidation system of the invention.
- -
-
Paragraph 0061; 0062; 0063; 0064; 0065
(2016/10/07)
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- Reactivity-based dynamic covalent chemistry: Reversible binding and chirality discrimination of monoalcohols
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In an effort to develop reactivity-based dynamic covalent bonding and to expand the scope and application of the dynamic covalent chemistry, in situ-generated simple generic iminium ions were utilized for the dynamic covalent binding of monoalcohols with high affinity. Hammett analysis was conducted to manipulate the equilibrium and correlate with the reactivity of reactants. The structural features of aldehydes and secondary amines were identified, and both polar and steric effects have significant impact on the binding. In particular, the substrates which can participate in π-π and polar-π interactions are able to afford apparent equilibrium constants in the magnitude of 104 M-2, demonstrating the power of weak supramolecular forces to stabilize the dynamic covalent assembly. The generality of the assembly was validated with a series of mono secondary alcohols. To showcase the practicality of our system, chirality discrimination and ee measurement of chiral secondary alcohols were achieved.
- Zhou, Yuntao,Ye, Hebo,You, Lei
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p. 2627 - 2633
(2015/03/18)
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- Palladium nanoparticles supported on magnetic copper ferrite nanoparticles: The synergistic effect of palladium and copper for cyanation of aryl halides with K4[Fe(CN)6]
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In this paper, for the first time, palladium nanoparticles were supported on (3-aminopropyl) triethoxysilane-modified copper ferrite nanoparticles. The obtained catalyst was characterized using FT-IR, TEM, EDX, AAS, XRD, and TGA analyses. The prepared heterogeneous catalyst showed superior activity toward cyanation of aryl iodides and bromides with K4[Fe(CN)6] compared to the Fe3O4 supported palladium nanoparticles, unfunctionalized CuFe2O4 nanoparticles, homogeneous Pd(OAc)2, CuCl2, and CuI catalysts. The heterogeneous and low Pd loading catalyst was recycled for four consecutive runs with small drops in catalytic activity.
- Gholinejad, Mohammad,Aminianfar, Afsaneh
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p. 106 - 113
(2015/02/19)
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- Palladium nanoparticles supported on magnetic copper ferrite nanoparticles: The synergistic effect of palladium and copper for cyanation of aryl halides with K4[Fe(CN)6]
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In this paper, for the first time, palladium nanoparticles were supported on (3-aminopropyl) triethoxysilane-modified copper ferrite nanoparticles. The obtained catalyst was characterized using FT-IR, TEM, EDX, AAS, XRD, and TGA analyses. The prepared heterogeneous catalyst showed superior activity toward cyanation of aryl iodides and bromides with K4[Fe(CN)6] compared to the Fe3O4 supported palladium nanoparticles, unfunctionalized CuFe2O4 nanoparticles, homogeneous Pd(OAc)2, CuCl2, and CuI catalysts. The heterogeneous and low Pd loading catalyst was recycled for four consecutive runs with small drops in catalytic activity.
- Gholinejad, Mohammad,Aminianfar, Afsaneh
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- N-Functionalized Amino Acids Promoted Aerobic Copper-Catalyzed Oxidation of Benzylic Alcohols in Water
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Instead of traditional N,N-bidentate ligands, N-functionlized amino acids were used as powerful N,O-bidentate ligands in aerobic copper/TEMPO-catalyzed system for promoting oxidation of benzylic alcohols. Under the optimized reaction conditions, a wide range of primary and secondary benzylic alcohols have been efficiently converted into aldehydes and ketones with good to excellent yields in water.
- Zhang, Guofu,Lei, Jie,Han, Xingwang,Luan, Yuxin,Ding, Chengrong,Shan, Shang
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p. 779 - 784
(2015/03/30)
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- Silver-Mediated Oxidative Trifluoromethylation of Alcohols to Alkyl Trifluoromethyl Ethers
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The development of an efficient and practical method for the preparation of alkyl trifluoromethyl ethers is urgently demanding. The silver-mediated oxidative O-trifluoromethylation of primary, secondary, and tertiary alcohols with TMSCF3 under mild reaction conditions is established to provide a novel approach to a broad range of alkyl trifluoromethyl ethers. Further, this method is applied to the late-stage O-trifluoromethylation of complex natural products and prescribed pharmaceutical agents.
- Liu, Jian-Bo,Xu, Xiu-Hua,Qing, Feng-Ling
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p. 5048 - 5051
(2015/11/03)
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- A practical in situ generation of the schwartz reagent. reduction of tertiary amides to aldehydes and hydrozirconation
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A new, highly efficient in situ protocol (Cp2ZrCl2/LiAlH(OBu-t)3) is described for the generation of the Schwartz reagent which provides a convenient method for the amide to aldehyde reduction and the regioselective hydrozirconation-iodination of alkynes and alkenes. Highlighted are chemoselective reductions of benzamides derived by directed ortho metalation (DoM) chemistry, allowing the synthesis of valuable 1,2,3-substituted benzaldehydes. The single-step, three-component process proceeds in a very short reaction time, shows excellent functional group compatibility, and uses inexpensive and long-storage stable reducing reagents.
- Zhao, Yigang,Snieckus, Victor
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p. 390 - 393
(2014/04/03)
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- Activity enhancement in cyanation of aryl halides through confinement of ionic liquid in the nanospaces of SBA-15 -supported Pd complex
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A novel and practical ionic-liquid mediated route for the synthesis of various aromatic nitriles has been developed via the cyanation of aryl halides with K4[Fe(CN)6] as a low cost, non-toxic and easily handled cyanating reagent in the presence of SBA-15 functionalized palladium complex partially confined with ionic liquids (IL@SBA-15-Pd) as the catalyst. Among the various ionic liquids tested in the cyanation reaction, 1-butyl-3-methylimidazolium hexafluorophosphate was found to provide the best medium for Pd-catalyzed cyanation of aryl halides. A variety of electron-rich and electron-poor aryl iodides and bromides gave the corresponding benzonitrile derivatives in good yield. Moreover, the catalyst was reused in four consecutive cycles with consistent catalytic activity. It was found that the presence of ionic liquid in the mesochannels of the mesoporous support not only provides a means of stabilizing Pd nanoparticles during the reaction but also the salient phase transfer feature of the imidazolium moieties may also serve as handles for faster penetration of Fe(CN)63- into the system pores to achieve highly concentrated reaction sites in close proximity to the catalytic (Pd NPs) centers, which resulted in an enhancement of the catalyst activity performance. This journal is
- Karimi, Babak,Zamani, Asghar,Mansouri, Fariborz
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p. 57639 - 57645
(2015/01/09)
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- Palladium-catalyzed reduction of carboxylic acids to aldehydes with hydrosilanes in the presence of pivalic anhydride
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A palladium catalyst system that allows the reduction of carboxylic acids to the corresponding aldehydes with hydrosilanes as reducing agent and pivalic anhydride as an indispensable reagent has been developed. A simple mixture of commercially available bis(dibenzylideneacetone)palladium(0) [Pd(dba) 2], tri(para-tolyl)phosphane and methylphenylsilane realized the reduction of various aliphatic carboxylic acids as well as benzoic acids to aldehydes in good to high yields. Copyright
- Fujihara, Tetsuaki,Cong, Cong,Terao, Jun,Tsuji, Yasushi
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supporting information
p. 3420 - 3424
(2013/12/04)
-
- Double C-H functionalization in sequential order: Direct synthesis of polycyclic compounds by a palladium-catalyzed C-H alkenylation-arylation cascade
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Palladium-catalyzed cascade C-H alkenylation and arylation provides convenient access to polycyclic aromatic compounds. Treatment of 3-bromoaniline derivatives bearing a bromocinnamyl group on the nitrogen atom with a catalytic amount of [Pd(OAc)2] and PCy3aHBF4 in the presence of Cs2CO3 in dioxane affords naphthalene-fused indole derivatives in good yields. This double cyclization reaction is also applicable to heterocyclic substrates, giving fused indoles containing a heteroaromatic ring such as dibenzofuran, dibenzothiophene, carbazole, indole, or benzofuran through heterocyclic C-H arylation. When using a 2,6-unsubstituted aniline derivative, the first C-H arylation preferentially proceeds at the more hindered position of the aniline ring.
- Ohno, Hiroaki,Iuchi, Mutsumi,Kojima, Naoto,Yoshimitsu, Takehiko,Fujii, Nobutaka,Tanaka, Tetsuaki
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supporting information; experimental part
p. 5352 - 5360
(2012/05/20)
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- Application of flow chemistry to the selective reduction of esters to aldehydes
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The reduction of esters to aldehydes is an important transformation in organic chemistry and several reducing agents have been described. However, the use of this reaction in medicinal and natural product chemistry is limited due to the instability of the intermediates and the high reactivity of the reaction products. In the current article, the general and selective reduction of esters with diisobutyl-tert-butoxyaluminum hydride in flow is reported. This reagent allows esters to be reduced in the presence of different functional groups, including those considered to be of similar or higher reactivity. Copyright
- De Munoz, Juan M.,Alcazar, Jesus,De La Hoz, Antonio,Diaz-Ortiz, Angel
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supporting information; experimental part
p. 260 - 263
(2012/02/16)
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- Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes
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Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium [(P{(NC 5H10)(C6H11)2}) 2PdCl2] (1) is a highly active and generally applicable C-C cross-coupling catalyst. Apart from its high catalytic activity in Suzuki, Heck, and Negishi reactions, compound 1 also efficiently converted various electronically activated, nonactivated, and deactivated aryl bromides, which may contain fluoride atoms, trifluoromethane groups, nitriles, acetals, ketones, aldehydes, ethers, esters, amides, as well as heterocyclic aryl bromides, such as pyridines and their derivatives, or thiophenes into their respective aromatic nitriles with K4[Fe(CN)6] as a cyanating agent within 24 h in NMP at 140 °C in the presence of only 0.05 mol % catalyst. Catalyst-deactivation processes showed that excess cyanide efficiently affected the molecular mechanisms as well as inhibited the catalysis when nanoparticles were involved, owing to the formation of inactive cyanide complexes, such as [Pd(CN)4]2-, [(CN)3Pd(H)]2-, and [(CN)3Pd(Ar)]2-. Thus, the choice of cyanating agent is crucial for the success of the reaction because there is a sharp balance between the rate of cyanide production, efficient product formation, and catalyst poisoning. For example, whereas no product formation was obtained when cyanation reactions were examined with Zn(CN)2 as the cyanating agent, aromatic nitriles were smoothly formed when hexacyanoferrate(II) was used instead. The reason for this striking difference in reactivity was due to the higher stability of hexacyanoferrate(II), which led to a lower rate of cyanide production, and hence, prevented catalyst-deactivation processes. This pathway was confirmed by the colorimetric detection of cyanides: whereas the conversion of β-solvato-α-cyanocobyrinic acid heptamethyl ester into dicyanocobyrinic acid heptamethyl ester indicated that the cyanide production of Zn(CN)2 proceeded at 25 °C in NMP, reaction temperatures of >100 °C were required for cyanide production with K4[Fe(CN) 6]. Mechanistic investigations demonstrate that palladium nanoparticles were the catalytically active form of compound 1. A balancing act: Compound 1 (see scheme) is a highly active cyanation catalyst. Furthermore, a sharp balance between the rates of cyanide generation, efficient product formation, and catalyst deactivation owing to excess cyanide was observed in deactivation processes. Copyright
- Gerber, Roman,Oberholzer, Miriam,Frech, Christian M.
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supporting information; experimental part
p. 2978 - 2986
(2012/04/04)
-
- RuCl 3-DCHA catalyst system: A selective aerobic oxidation of primary benzylic alcohols under mild conditions
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The aerobic oxidation of benzylic alcohols to their corresponding aldehydes was performed in a RuCl3 · 3H2O-dicyclohexylamine (DCHA) catalyst system under ambient atmosphere at room temperature. It is noteworthy that the RuCl3 · 3H2O-DCHA system displayed a preference for the primary versus secondary benzylic alcohols in both intermolecular and intramolecular competition experiments.
- Yu, Kaihui,Ye, Dongnai,Shu, Lei,Zhang, Shiyong,Hu, Qiaosheng,Liu, Liangxian
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experimental part
p. 2318 - 2326
(2012/06/18)
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- A general and efficient zinc-catalyzed oxidation of benzyl alcohols to aldehydes and esters
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Go green: A general and efficient zinc-catalyzed oxidation of benzyl alcohols has been developed. In the presence of a zinc catalyst, various aldehydes and esters have been prepared in good to excellent yields under mild conditions (see scheme).
- Wu, Xiao-Feng
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experimental part
p. 8912 - 8915
(2012/09/22)
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- A mild and efficient palladium-catalyzed cyanation of aryl chlorides with K4[Fe(CN)6]
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An efficient palladium-catalyzed cyanation of aryl chlorides is established. In the presence of a highly effective Pd/CM-phos catalyst, cyanation of aryl chlorides proceeds at 70 °C in general, which is the mildest reaction temperature achieved so far for this process. Common functional groups such as keto, aldehyde, ester, nitrile and-NH2, and heterocyclic coupling partners including N-H indoles are well tolerated. Moreover, a sterically hindered nonactivated ortho,ortho-disubstituted electrophile is shown to be a feasible coupling partner in cyanation.
- Yeung, Pui Yee,So, Chau Ming,Lau, Chak Po,Kwong, Fuk Yee
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supporting information; experimental part
p. 648 - 651
(2011/04/15)
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- Studies on the kinetics of tetraethylammonium bromochromate oxidation of some meta- and para-substituted benzyl alcohols in non-aqueous media
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Tetraethylammonium bromochromate (TEABC) oxidation of 18 meta- and para-substituted benzyl alcohols (BnOH) in dimethylsulphoxide (DMSO) leads to the formation of corresponding aldehydes. The reaction is first order each in TEABC and the alcohols. The reaction is catalyzed by hydrogen ions. The hydrogen ion dependence has the form: kobs = a+b[H+]. The oxidation of αα′-dideuterio benzyl alcohol exhibited a substantial primary kinetic isotope effect (kH/kD = 5.71 at 303 K). Oxidation of benzyl alcohol was studied in 17 different organic solvents. The solvent effect has been analyzed using Kamlet's and Swain's multi parametric equation. A correlation of data with Kamlet-Taft solvatochromic parameters (α, β, π*) suggests that the specific solute-solvent interactions play a major role in governing the reactivity. A mechanism involving a hydride ion transfer via chromate ester is proposed. by Oldenbourg Wissenschaftsverlag, Mu?nchen.
- Mansoor, S. Sheik,Shafi, S. Syed
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scheme or table
p. 249 - 263
(2011/04/17)
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- Experimental evidence of the occurrence of intramolecular electron transfer in catalyzed 1,2-dioxetane decomposition
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The activation parameters for the thermal decomposition of 13 acridinium-substituted 1,2-dioxetanes, bearing an aromatic moiety, were determined and their chemiluminescence emission quantum yields estimated, utilizing in situ photosensitized 1,2-dioxetane generation and observation of its thermal decomposition kinetics, without isolation of these highly unstable cyclic peroxides. Decomposition rate constants show linear free-energy correlation for electron-withdrawing substituents, with a Hammett reaction constant of Φ = 1.3 ± 0.1, indicating the occurrence of an intramolecular electron transfer from the acridinium moiety to the 1,2-dioxetane ring, as postulated by the intramolecular chemically initiated electron exchange luminescence (CIEEL) mechanism. Emission quantum yield behavior can also be rationalized on the basis of the intramolecular CIEEL mechanism, additionally evidencing its occurrence in this transformation. Both relations constitute the first experimental evidence for the occurrence of the postulated intramolecular electron transfer in the catalyzed and induced decomposition of properly substituted 1,2-dioxetanes.
- Ciscato, Luiz Francisco M. L.,Bartoloni, Fernando H.,Weiss, Dieter,Beckert, Rainer,Baader, Wilhelm J.
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supporting information; experimental part
p. 6574 - 6580
(2010/11/17)
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- Palladium nanoparticles stabilized by a copolymer of N-vinylimidazole with N-vinylcaprolactam as efficient recyclable catalyst of aromatic cyanation
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A new recyclable catalytic system was developed based on palladium nanoparticles and a copolymer of N-vinylimidazole and N-vinylcaprolactam for cyanation of aromatic bromides. The source of the cyanide ion was a nontoxic potassium hexacyanoferrate.
- Beletskaya,Selivanova,Tyurin,Matveev,Khokhlov
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experimental part
p. 157 - 161
(2010/07/06)
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- Schwartz Reagents: Methods of In Situ Generation and Use
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Embodiments of the invention provide a method of using Schwartz Reagent, Cp2Zr(H)Cl, without accumulating or isolating it. Methods provide mixtures of Cp2ZrCl2, reductants that selectively reduce Cp2ZrCl2, and substrates. After reaction of Cp2ZrCl2 and the reductant, an intermediate reduction product is formed, apparently Schwartz Reagent. The in situ Schwartz Reagent then selectively reduces certain functional groups on the substrate. Substrates include tertiary amides, tertiary benzamides, aryl O-carbamates, and heteroaryl N-carbamates, which are reduced to aldehydes, benzaldehydes, aromatic alcohols, and heteroaromatics, respectively. Compared to prior methods, reagents are inexpensive and stable, reaction times are short, and reaction temperature in certain cases is conveniently room temperature. It has been estimated that using the in situ method described herein instead of synthesized or commercially obtained Schwartz Reagent provides a 50% reduction in cost.
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Page/Page column 7; 10
(2010/06/19)
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- Low-pressure hydrogenation of arenecarboxylic acids to aryl aldehydes
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A highly effective palladium catalyst has been developed that allows the selective hydrogenation of arenecarboxylic acids to the aryl aldehydes in the presence of pivalic anhydride already at 5 bar hydrogen pressure. With the new catalyst, diversely functionalized aromatic and heteroaromatic aldehydes are conveniently accessible from the corresponding carboxylic acids in a single reaction step without any overreduction to the alcohols.
- Goossen, Lukas J.,Khan, Bilal Ahmad,Fett, Thomas,Treu, Matthias
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supporting information; experimental part
p. 2166 - 2170
(2010/11/04)
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- Correlation analysis of reactivity in the oxidation of substituted benzyl alcohols by morpholinium chlorochromate
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Oxidation of benzyl alcohol and some ortho-, meta- andparo-monosubstitutcd derivatives by morpholinium chlorochromate in dimethyl stilphoxide leads to the formation of corresponding benzaldehydcs. The reaction is first order each in both morpholinium chlorochromate and the alcohol. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kob8 = a + b [H+]. Oxidation of α,α-dideuteriobenzyl alcohol exhibits a substantial primary kinetic isotope effect (kH/kD = 5.86 at 298 K). The reaction has been studied in nineteen organic solvents and the effect of solvent analysed using Taft's and Swain's multi-parametric equations. The rates of oxidation of para- and meta-substituted benzyl alcohols have been correlated in terms of Charton's tripararnetric LDR equation whereas the oxidation of ortho-substituted benzyl alcohols with tetraperametric LDRS equation. The oxidation of para-substituted benzyl alcohols is more susceptible to the derealization effect than that of ortho- and meta- substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism is also proposed.
- Soni, Neelam,Tiwari, Vandana,Sharma, Vinita
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scheme or table
p. 669 - 676
(2009/02/08)
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- Correlation analysis of reactivity in the oxidation of substituted benzyl alcohols by 2,2′-bipyridinium chlorochromate
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Oxidation of benzyl alcohol and some ortho-, meta- and para-monosubstituted ones by 2.2′-bipyridinium chlorochromate (BPCC) in DMSO leads to the formation of corresponding benzaldehydes. The reaction is first order in both BPCC and the alcohol. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form : kobs = a + b [H+]. Oxidation of α,α-dideuteriobenzyl alcohol (PhCD2OH) has exhibited a substantial primary kinetic isotope effect (kH/k D = 5.60 at 298 K). The reaction has been studied in nineteen organic solvents and the effect of solvent analysed using Taft's and Swain's multi-parametric equations. The rates of oxidation of para- and meta-substituted benzyl alcohols have been correlated in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzyl alcohols with tetraparametric LDRS equation. The oxidation of para-substituted benzyl alcohols is more susceptible to the delocalization effect than that of ortho- and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.
- Yajurvedi, Deeksha,Baghmar, Manju,Sharma, Pradeep K.
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body text
p. 496 - 501
(2009/07/18)
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- Convenient oxidation of benzylic and allylic halides to aldehydes and ketones
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Benzylic and allylic halides were conveniently oxidized to aldehydes and ketones by pyridine N-oxide in the presence of silver oxide under mild conditions.
- Chen, David X.,Ho, Chi M.,Rudy Wu,Wu, Peter R.,Wong, Freeman M.,Wu, Weiming
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p. 4147 - 4148
(2008/09/20)
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- Pd/C: A recyclable catalyst for cyanation of aryl bromides
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Aryl cyanides have been prepared from the corresponding aryl bromides with potassium hexacyanoferrate(II) using Pd/C as a catalyst. It is shown that the addition of Bu3N is the key factor in obtaining the corresponding aryl cyanides. Furthermore, the catalyst can be recycled by filtration and washing sequences, making the method also attractive for industrial applications. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Zhu, Yi-Zhong,Cai, Chun
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p. 2401 - 2404
(2008/03/12)
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- Pd/C: A recyclable catalyst for cyanation of aryl halides with K4[Fe(CN)6]
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Aryl nitriles have been prepared from the corresponding aryl halides with potassium hexacyanoferrate(II) using Pd/C as a catalyst. No ligand or cocatalyst is required. This protocol also avoids the use of highly toxic alkali cyanides. Furthermore, the catalyst can be recycled via simple filtration and washing sequences. Copyright Taylor & Francis Group, LLC.
- Zhu, Yi-Zhong,Cai, Chun
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p. 3359 - 3366
(2008/02/12)
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- Indium(III) trifluoromethanesulfonate as an efficient catalyst for the deprotection of acetals and ketals
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(Chemical Equation Presented) Acetals and ketals are readily deprotected under neutral conditions in the presence of acetone and catalytic amounts of indium(III) trifluoromethanesulfonate (0.8 mol %) at room temperature or mild microwave heating conditions to give the corresponding aldehydes and ketones in good to excellent yields.
- Gregg, Brian T.,Golden, Kathryn C.,Quinn, John F.
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p. 5890 - 5893
(2008/02/09)
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- Effect of structure in benzaldehyde oximes on the formation of aldehydes and nitriles under photoinduced electron-transfer conditions
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(Chemical Equation Presented) The mechanistic aspects of the photosensitized reactions of a series of benzaldehyde oximes (1a-o) were studied by steady-state (product studies) and laser flash photolysis methods. Nanosecond laser flash photolysis studies have shown that the reaction of the oxime with triplet chloranil (3CA) proceeds via an electron-transfer mechanism provided the free energy for electron transfer (ΔGET) is favorable; typically, the oxidation potential of the oxime should be below 2.0 V. Substituted benzaldehyde oximes with oxidation potentials greater than 2.0 V quench 3CA at rates that are independent of the substituent and the oxidation potential. The most likely mechanism under these conditions is a hydrogen atom transfer mechanism as this reaction should be dependent on the O-H bond strength only, which is virtually the same for all oximes. Product studies have shown that aldoximes feact to give both the corresponding aldehyde and the nitrile. The important intermediate in the aldehyde pathway is the iminoxyl radical, which is formed via an electron transfer-proton transfer (ET-PT) sequence (for oximes with low oxidation potentials) or via a hydrogen atom transfer (HAT) pathway (for oximes with larger oxidation potentials). The nitriles are proposed to result from intermediate iminoyl radicals, which can be formed via direct hydrogen atom abstraction or via an electron-transfer-proton- transfer sequence. The experimental data seems to support the direct hydrogen atom abstraction as evidenced by the break in linearity in the plot of the quenching rates against the oxidation potential, which suggests a change in mechanism. The nitrile product is favored when electron-accepting substituents are present on the benzene ring of the benzaldehyde oximes or when the hydroxyl hydrogen atom is unavailable for abstraction. The latter is the case in pyridine-2-carboxaldoxime (2), where a strong intramolecular hydrogen bond is formed. Other molecules that form weaker intramolecular hydrogen bonds such as 2-furaldehyde oxime (3) and thiophene-2-carboxaldoxime (4) tend to yield increasing amounts of aldehyde.
- De Lijser, H.J. Peter,Hsu, Susan,Marquez, Bernadette V.,Park, Adriana,Sanguantrakun, Nawaporn,Sawyer, Jody R.
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p. 7785 - 7792
(2007/10/03)
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- Statistical experimental design-driven discovery of room-temperature conditions for palladium-catalyzed cyanation of aryl bromides
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A combination of Pd2(dba)3·CHCl3 (0.5 mol %) and commercially available, air-stable phosphonium salt [(t-Bu) 3PH]BF4 (1.4 mol %) in a presence of Zn powder and Zn(CN)2 as the cyanide source comprises an extremely efficient catalyst system for the cyanation of a diverse array of aryl bromides, at room temperature. This result emerged from an experimental strategy that combines the advantages of parallel, automated experimentation with the design of experiments (DOE) for the effective definition of an optimal set of reaction conditions.
- Stazi, Federica,Palmisano, Giovanni,Turconi, Marco,Santagostino, Marco
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p. 1815 - 1818
(2007/10/03)
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- A convenient procedure for palladium catalyzed cyanation using a unique bidentate phosphorus ligand
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A palladium complex bearing 1,2-diphenyl-3,4-diphosphinidenecyclobutene ligand (DPCB) has been used to facilitate the catalytic cyanation of aryl bromides. A series of substituted benzonitriles was prepared in good to high yields by the treatment of the corresponding aryl bromides with Zn(CN) 2 in N-methyl-2-pyrrolidone in the presence of 2-4 mol % catalyst at 100°C for 16 h.
- Jensen, Rader S.,Gajare, Anil S.,Toyota, Kozo,Yoshifuji, Masaaki,Ozawa, Fumiyuki
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p. 8645 - 8647
(2007/10/03)
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- Potassium hexacyanoferrate(II) - A new cyanating agent for the palladium-catalyzed cyanation of aryl halides
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A new advantageous cyanating agent, potassium hexacyanoferrate(II), is described for the palladium-catalyzed cyanation of aryl halides. All cyanide ions on the iron(II) center can be transferred to the aryl halide using palladium(II) acetate and dppf as the catalyst. Under optimized reaction conditions good yields of benzonitriles and unprecedented catalyst productivities are observed.
- Schareina, Thomas,Zapf, Alexander,Beller, Matthias
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p. 1388 - 1389
(2007/10/03)
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- 4-HYDROXPIPERIDINE DERIVATIVE WITH ANALGETIC ACTIVITY
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A compound represented by the following Formula (I): (wherein A represents oxygen atom or -NR3- (R3 represents hydrogen atom or lower alkyl group); R1 represents nitro group, lower alkoxycarbonyl group, carbamoyl group unsubstituted or mono- or di-substituted by lower alkyl group, unprotected or protected hydroxyl group, unprotected or protected carboxyl group, lower alkyl group substituted by unprotected or protected hydroxyl group, or tetrazolyl group; and R2 represents hydrogen atom, cyano group or lower alkylsulfonyl group, provided that when A is - NR3-, it is excluded that R1 represents unprotected or protected hydroxyl group or lower alkyl group substituted by unprotected or protected hydroxyl group) or its salt, and method for producing the compound, and a pharmaceutical composition containing the compound as active ingredient.
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- Mechanisms of the Aerobic Oxidation of Alcohols to Aldehydes and Ketones, Catalysed under Mild Conditions by Persistent and Non-Persistent Nitroxyl Radicals and Transition Metal Salts - Polar, Enthalpic, and Captodative Effects
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The oxidation of alcohols to aldehydes and ketones by air or oxygen under mild conditions (room temperature and atmospheric pressure), catalysed by persistent and non-persistent nitroxyl radicals in combination with transition metal salts, appears to be the most convenient of the numerous processes developed for these purposes. The thermochemistry, the kinetics, and the Hammett correlations have allowed us to establish, on a quantitative basis, the fundamental difference between the oxidation catalysed by persistent and non-persistent nitroxyl catalysts. In the latter case, an interesting significant captodative effect is displayed for the first time for the oxidation of substituted benzyl alcohols; the importance of enthalpic and polar effects is emphasised.
- Minisci, Francesco,Recupero, Francesco,Cecchetto, Andrea,Gambarotti, Cristian,Punta, Carlo,Faletti, Roberta,Paganelli, Roberto,Pedulli, Gian Franco
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p. 109 - 119
(2007/10/03)
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- Correlation analysis of reactivity in the oxidation of substituted benzyl alcohols by quinolinium bromochromate
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Oxidation of benzyl alcohol and some ortho- meta- and para-monosubstituted ones by quinolinium, bromochromate (QBC) in dimethyl sulphoxide (DMSO) leads to the formation of corresponding benzaldehydes. The reaction is first order each in both QBC and the alcohol. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs = a + b [H+]. Oxidation of α,α-dideuteriobenzyl alcohol (PhCD2OH) has exhibited a substantial primary kinetic isotope effect (kH/k D = 5.60 at 298 K). The reaction has been studied in nineteen organic solvents and the effect of solvent analysed using Taft's and Swain's multi-parametric equations. The rates of oxidation of para- and meta-substituted benzyl alcohols have been correlated in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzyl alcohols with tetraparametric LDRS equation. The oxidation of para-substituted benzyl alcohols is more susceptible to the delocalization effect than that of ortho- and meta-substituted compounds which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.
- Prakash, Om,Sharma, Pradeep K.
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p. 467 - 473
(2007/10/03)
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- New selective metal-free oxidations of primary alcohols by HNO3 or HNO3 and O2, catalyzed by Br2
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Primary benzylic alcohols are selectively oxidized to the corresponding aromatic aldehydes by molecular oxygen at atmospheric pressure, under Br 2-HNO3 catalysis in a biphasic medium (1,2-dichloroethane- water, 5:1) at 60 °C. Under paragonable experimental conditions the aliphatic alcohols are oxidized to esters.
- Minisci, Francesco,Porta, Ombretta,Recupero, Francesco,Punta, Carlo,Gambarotti, Cristian,Pierini, Monica,Galimberti, Laura
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p. 2203 - 2205
(2007/10/03)
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- Aerobic Oxidation of Benzyl Alcohols Catalyzed by Aryl Substituted N-Hydroxyphthalimides. Possible Involvement of a Charge-Transfer Complex
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A series of aryl-substituted N-hydroxyphthalimides (X-NHPIs) containing either electron-withdrawing groups (4-CH3OCO, 3-F) or electron-donating groups (4-CH3, 4-CH8O, 3-CH 3O, 3,6-(CH3O)2) have been used as catalysts in the aerobic oxidation of primary and secondary benzylic alcohols. The selective formation of aromatic aldehydes was observed in the oxidation of primary alcohols; aromatic ketones were the exclusive products in the oxidation of secondary alcohols. O-H bond dissociation enthalpies (BDEs) of X-NHPIs have been determined by using the EPR radical equilibration technique. BDEs increase with increasing the electron-withdrawing properties of the aryl substituent. Kinetic isotope effect studies and the increase of the substrate oxidation rate by increasing the electron-withdrawing power of the NHPI aryl substituent indicate a rate-determining benzylic hydrogen atom transfer (HAT) from the alcohol to the aryl-substituted phthalimide-N-oxyl radical (X-PINO). Besides enthalpic effects, polar effects also play a role in the HAT process, as shown by the negative ρ values of the Hammett correlation with σ + and by the decrease of the ρ values (from -0.54 to -0.70) by increasing the electron-withdrawing properties of the NHPI aryl substituent. The relative reactivity of 3-CH3O-C6H4CH 2OH and 3,4-(CH3O)2-C6H3CH 2OH, which is higher than expected on the basis of the σ + values, the small values of relative reactivity of primary vs secondary benzylic alcohols, and the decrease of the ρ values by increasing the electron-withdrawing properties of the NHPI aryl substituent, suggest that the HAT process takes place inside a charge-transfer (CT) complex formed by the X-PINO and the benzylic alcohol.
- Annunziatini, Claudia,Gerini, Maria Francesca,Lanzalunga, Osvaldo,Lucarini, Marco
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p. 3431 - 3438
(2007/10/03)
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- Highly efficient deprotection of acetals by titanium cation-exchanged montmorillonite as a strong solid acid catalyst
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Deprotection of various kinds of acetals sufficiently occured in the presence of Ti4+-exchanged montmorillonite as a recyclable strong solid acid catalyst.
- Kawabata, Tomonori,Kato, Masaki,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 648 - 649
(2007/10/03)
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