- Novel reduction of carbonyl compounds with Al/NH3/halide under irradiation of ultrasonic wave
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Various carbonyl compounds, such as benzophenones and acetophenones, were reduced by Al/NH3/halide under ultrasonic wave irradiation to give the corresponding monohydric alcohols and/or pinacols in satisfactory yields. The addition of inorganic halides improved the selectivity in the formation of monohydric alcohols and pinacols.
- Sato,Nagaoka,Goto,Saito
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- Efficient synthesis of antihistamines clocinizine and chlorcyclizine
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A simple and efficient route has been developed for the synthesis of anti-histamine drugs clocinizine and chlorcyclizine. The common intermediate 1-[(4-chloro phenyl) (phenyl)-methyl]-piperazine (8), is prepared from (4-chlorophenyl) (phenyl)-methanone (5), in three steps with excellent yields. All the reactions proceeded smoothly and the products were also isolated easily. Springer Science+Business Media, LLC 2011.
- Venkat Narsaiah,Narsimha
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- Novel azolinium/rhodium system catalyzed addition of arylboronic acids to aldehydes
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There novel 1,3-dialkylperhydrobenzimidazolinium (2a-c) and two 1,3-dialkylimidazolinium salts (4a,b) as NHC precursors were synthesized from N,N′-dialkyl-1,2-cyclohexanediamine dihydrochloride and 1,2-dialkylpropanediamine dihydrochloride. The in situ prepared three component system [RhCl(COD)]2 / imidazolinium salts (2, 4) and KOBut catalyses the addition of phenylboronic acid to sterically hindered aldehydes affording the corresponding arylated secondary alcohols in good yields.
- Oezdemir, Ismail,Yigit, Murat,Cetinkaya, Engin,Cetinkaya, Bekir
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- Surface modification of CdS quantum dots with fluorinated thiophenol
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CdS nanocrystallites prepared by capping with pentafluorothiophenol, 2,3,5,6-tetrafluorothiophenol or 4-fluorothiophenol are characterized as quantum dots by TEM, FTIR, NMR, UV-VIS and fluorescence spectroscopy. The crystalline size tends to increase with an increase in the number of fluorine atoms in the capping molecules while maintaining high solubility in organic solvents, with solubility in alcohols depending on the number of fluorine atoms in the capping molecules. Pentafluorophenyl-capped CdS nanocrystallites have the highest solubilities in alcohols, and exhibit quantum dot photocatalysis in methanol, leading to the efficient two-electron transfer photoreduction under visible-light irradiation.
- Hosokawa, Hiroji,Ogata, Tomoyuki,Wada, Yuji,Murakoshi, Kei,Sakata, Takao,Mori, Hirotaro,Yanagida, Shozo
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- Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst
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The cobalt/chromium-catalyzed three-component coupling of aryl iodides, allenes, and aldehydes has been developed to afford multi-substituted homoallylic alcohols in a diastereoselective manner. Control experiments for understanding the reaction mechanism reveal that the cobalt catalyst is involved in the oxidative addition and carbometalation steps in the reaction, whereas the chromium salt generates highly nucleophilic allylchromium intermediates from allylcobalt species, without the loss of stereochemical information, to allow the addition to aldehydes.
- Komeyama, Kimihiro,Sakiyama, Shunsuke,Iwashita, Kento,Osaka, Itaru,Takaki, Ken
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- Tuning the reactivity of dirhodium(II) complexes with axial N-heterocyclic carbene ligands: The arylation of aldehydes
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(Chemical Equation Presented) Efficient dinuclear catalysts: A complex of {Rh2(OAc)4} with two N-heterocyclic carbenes (NHCs) at the axial positions catalyzes the arylation of aldehydes (see picture; R = alkyl, aryl). DFT calculations reveal subtle stereoelectronic effects resulting from the NHC coordination to the dirhodium(II) complex and suggest that complexes with one axial NHC ligand are the catalytically active species.
- Gois, Pedro M. P.,Trindade, Alexandre F.,Veiros, Luis F.,Andre, Vania,Duarte, M. Teresa,Afonso, Carlos A. M.,Caddick, Stephen,Cloke, F. Geoffrey N.
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- Nucleofugality of aliphatic carboxylates in mixtures of aprotic solvents and water
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The leaving group ability (nucleofugality) of fluoroacetate, chloroacetate, bromoacetate, dichloroacetate, trifluoroacetate, trichloroacetate, heptafluorobutyrate, formate, isobutyrate, and pivalate have been derived from the solvolysis rate constants of the corresponding X,Y-substituted benzhydryl carboxylates in 60 % and 80 % aqueous acetonitrile and 60 % aqueous acetone, applying the LFER equation: log k = sf(Ef + Nf). The experimental barriers (ΔG?,exp) for solvolyses of 11 reference dianisylmethyl carboxylates in these solvents correlate very well (r = 0.994 in all solvents) with ΔG?,model of the model σ-assisted heterolytic displacement reaction of cis-2,3-dihydroxycyclopropyl trans-carboxylates calculated earlier. Linear correlation observed between the log k for the reference dianisylmethyl carboxylates and the sf values enables estimation of the reaction constant (sfestim). Using the ΔG?,exp vs. ΔG?,model correlation, and taking the estimated sfestim, the nucleofugality parameters for other 34 aliphatic carboxylates have been determined in 60 % and 80 % aqueous acetonitrile and 60 % aqueous acetone. The most important variable that determines the reactivity of aliphatic carboxylates in aprotic solvent/water mixtures is the inductive effect of the group(s) attached onto the carboxylate moiety.
- Mati, Mirela,Denegri, Bernard,Kronja, Olga
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- Semiconductor Photocatalysis: Size Control of Surface-Capped CdS Nanocrystallites and the Quantum Size Effect in Their Photocatalysis
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Size-controlled CdS nanocrystallites were prepared by using thiophenol or hexanethiol as a capping reagent by controlling the ratio of Cd2+ to bis(trimethylsilyl) sulfide (S(TMS)2) as a source of the sulfide ion in reversed micelles.Their solubility and photocatalysis were examined.A series of size-controlled phenyl-capped CdS nanocrystallites catalyze the photoreduction of aromatic ketones in the presence of triethylamine as an electron donor under visible-light irradiation.The photocatalytic activity is affected by the particle size, i.e., the reducing power of the photogenerated electron on CdS nanocrystallites toward the ketones increases with decreasing the particle size.The enhancement of photocatalytic activity observed by reducing the particle size should be ascribed to not only a negative shift of the conduction band edge, but also suppression of the formation of surface defects.
- Yanagida, Shozo,Ogata, Tomoyuki,Shindo, Akihiro,Hosokawa, Hiroji,Mori, Hirotaro,et al.
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- Comparative Mechanistic Study of the Reaction of Benzophenone with n-BuMgBr and n-BuLi
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Substituent effects on reactivity and product distribution (addition vs reduction) were determined for the reactions of benzophenones with n-BuMgBr and n-BuLi at 0 deg C.In case of the reaction with n-BuMgBr, meta and para-substituted benzophenones gave a reasonably linear Hammet plot, from which the ρ value of 1.45 was calculated, while ortho-substituted derivatives deviated downward from the correlation line.In contrast, the reaction with n-BuLi exhibit very small substituent effects on reactivity.The product distrubution is highly dependent on substituents in the n-BuMgBr reaction, whereas it is essentially independent of substituents in the n-BuLi reaction.Mechanistic differences between the reactions of these two reagents are discussed on the basis of these experimental results.
- Yamataka, Hiroshi,Miyano, Nobutaka,Hanafusa, Terukiyo
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- Novel rhodium-1,3-dialkyl-3,4,5,6-tetrahydropyrimidin-2-ylidene complexes as catalysts for arylation of aromatic aldehydes
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Six new rhodium-tetrahydropyrimidin-2-ylidene complexes (2a-f) have been prepared and characterized by C, H, N analysis, 1H NMR and 13C NMR. Phenylboronic acid reacts with aldehydes in the presence of a catalytic amount of the new rhodium(I)-carbene complexes, RhCl(COD)(1,3- dialkyl-3,4,5,6-tetrahydropyrimidin-2-ylidene), (2a-f), to give the corresponding secondary aryl alcohols in good yields (72-96%).
- ?zdemir, Ismail,Demir, Serpil,?etinkaya, Bekir,?etinkaya, Engin
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- [Ir(COD)Cl]2/tris(2,4-di-t-butylphenyl)phosphite-catalyzed addition reactions of arylboronic acids with aldehydes
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[Ir(COD)Cl]2/tris(2,4-di-t-butylphenyl)phosphite-catalyzed addition reactions of arylboronic acids with aldehydes were described. The Ir(I) catalyst, generated from [Ir(COD)Cl]2 and tris(2,4-di-t-butylphenyl)phosphite, was an efficient catalyst system for the addition reactions of a variety of arylboronic acids with aromatic and aliphatic aldehydes. The easy availability of the catalyst and good yields make these reactions potentially useful in organic synthesis.
- Liao, Yuan-Xi,Dong, Jie,Hu, Qiao-Sheng
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- An anionic rhodium η4-quinonoid complex as a multifunctional catalyst for the arylation of aldehydes with arylboronic acids
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The π-bonded rhodium quinonoid complex, K+[(1,4-benzoquinone)Rh(COD)]-, functions as a good catalyst for the coupling of arylboronic acid and aldehydes to afford diaryl alcohols. The catalysis is heterobimetallic in that both the transition metal and concomitant alkali metal counterion play an integral part in the reaction. In addition, the anionic quinonoid catalyst itself plays a bifunctional role by acting as a ligand to the boronic acid and as a Lewis acid receptor site for the transferring aryl group. Copyright
- Son, Seung Uk,Kim, Sang Bok,Reingold, Jeffrey A.,Carpenter, Gene B.,Sweigart, Dwight A.
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- Formation of Secondary Alcohols from the Reaction of Trimethyl- and Methyldiphenyl-telluronium Salts with Aldehydes by Use of Organolithium Reagents
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The telluronium salts (1) and (2), precursors of the non-stabilized telluronium ylide, on treatment with organolithium reagents, reacted with aldehydes to afford secondary alcohols via tetraorganyl tellurium intermediates.
- Shi, Li-Lan,Zhou, Zhang-Lin,Huang, Yao-Zeng
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- Nickel-catalyzed 1,2-addition of arylboroxines to aromatic aldehydes
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Development of Ni-Et-Duphos-catalyzed 1,2-addition of arylboroxines to aromatic aldehydes is described. The dramatic effect of boron reagent and phosphine ligand is observed. This method with a phosphine ligand allows asymmetric arylation of aromatic aldehydes (up to 78% ee).
- Arao, Takafumi,Kondo, Kazuhiro,Aoyama, Toyohiko
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- The remarkable role of water during the chemoselective reduction of ketones mediated by metallic aluminium
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Diaryl ketones are reduced selectively to the corresponding benzhydrols in good yield by aluminium powder in the presence of sodium hydroxide in the solvent system MeOH:H2O=2:1 whereas dialkyl ketones, α-tetralone, aryl alkyl ketones and cycloalkanones remain mostly unaffected. Interestingly, diaryl ketones remain totally unchanged by the present reagent combination in the absence of water, that is in anhydrous methanol.
- Bhar, Sanjay,Guha, Sharmistha
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- Highly efficient C-C coupling reactions using metallated benzylphosphine complexes of palladium
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Phosphapalladacyclic complexes synthesised from orthobromobenzylphosphine ligands are effective catalysts for carbon-carbon bond forming reactions, exhibiting activity that compares with, and in several examples exceeds, that of existing systems.
- Gibson,Foster,Eastham,Tooze,Cole-Hamilton
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- In situ generated rhodium-based catalyst for addition of phenylboronic acid to aldehydes
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New 1,3-dialkylperhydrobenzimidazolinium and 1,3-dialkylimidazolinium salts (2,4) as NHC precursors have been synthesized and characterized. These salts in combination with [RhCl(COD)]2 provided active catalysts for the addition of phenylboronic acid to aldehydes under mild conditions. The in situ prepared three-component system [RhCl(COD)]2/imidazolinium salts (2,4) and KOBut catalyse the addition of phenylboronic acid to sterically hindered aldehydes affording the corresponding arylated secondary alcohols in good yields
- Yigit, Murat,Oezdemir, Ismail,Cetinkaya, Engin,Cetinkaya, Bekir
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- A simple procedure for the polymer-supported N-heterocyclic carbene-rhodium complex via click chemistry: A recyclable catalyst for the addition of arylboronic acids to aldehydes
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A novel polymer-supported carbene-rhodium complex was prepared using a simple procedure via click chemistry. This polymer-supported N-heterocyclic carbene-rhodium complex was characterized and used as a catalyst for the addition of arylboronic acids to aldehydes in good to excellent yields.
- He, Ying,Cai, Chun
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- Nucleophilic substitution reactions of aminoalkylbenzotriazoles with ytterbium metal umpoled diaryl ketones
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The reaction of diaryl ketones such as benzophenone with aminoalkylbenzotriazoles in the presence of ytterbium metal at room temperature has been found to give 2-amino alcohols in good yields under mild and neutral conditions.
- Su, Weike,Yang, Bibo,Zhang, Yongmin
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- Nonmetallised CdS-catalised Photoreduction of Aromatic Ketones to Alcohols and/or Pinacols
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In acatonitrile containing triethylamine as a sacrificial electron donor, non-metallized CdS shows photocatalytic activity for reduction of benzophenone derivatives whose reduction potentials are larger than -1.90 V vs. standard calomel electrode (SCE), giving alcohols and/or pinacols under visible light irradiation.
- Shiragami, Tsutomu,Pac, Chyongjin,Yanagida, Shozo
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- Evidence for rate limiting C-H bond cleavage in the leuckart reaction
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A rho value of +0.21 is reported for the reaction of mono 4-substi- tuted benzophenones with formamide. This, in conjunction with a kinetic iso- tope effect value of 1.80 obtained for the system, suggests a rate-limiting C-H bond cleavage.
- Awachie, Peter I.,Agwada, Vincent C.
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- Heterogenization of cobalt nanoparticles on hollow carbon capsules: Lab-in-capsule for catalytic transfer hydrogenation of carbonyl compounds
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Incorporation of cobalt nanoparticles (Co NPs) in porous iron oxide nanospheres (Fe3O4 NSs) templated, glucose derived hollow carbon capsules (HCCs), with an objective to achieve activity and stability simultaneously, facilitates higher catalytic activity of Co NPs in transfer hydrogenation of ketones and aldehydes. A variety of ketones and aldehydes are hydrogenated successfully with excellent yields and high turnover number (TON). This system constitutes one of the most general, heterogeneous, highly stable catalyst, which does not require additives for activation and employs mild reaction conditions. Other significant advantages are low Co content (0.38 mol%) for a catalytic hydrogenation reaction, functional-group tolerance, inexpensive, environmentally benign nature and reusability.
- Kumar, Basuvaraj Suresh,Amali, Arlin Jose,Pitchumani, Kasi
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- Nickel salt-catalyzed addition reaction of arylboronic acids to aromatic aldehydes
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Arylation reaction of aromatic aldehydes with arylboronic acids proceeded smoothly in the presence of a base and catalytic amount of a nickel salt, Ni(ClO4)2·6H2O, in toluene/IPA = 5:1 or IPA to afford corresponding diarylmethanols in good to excellent yields.
- Zhou, Li,Du, Xin,He, Ren,Ci, Zhenhua,Bao, Ming
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- Synthesis and use of mono- or bisxylyl linked bis(benzimidazolium) bromides as carbene precursors for C-C bond formation reactions
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Two benzimidazolium moieties linked by one or two xylyls (m- and p-) have been synthesized, characterized and then they were used for Heck coupling reactions as in situ formed catalysts. Mono bridged salts are more efficient as compared to bisbridged salts. In addition, mono bridged salts were converted to Rh-NHC complexes which were tested as catalysts for the arylation of aldehydes.
- Türkmen, Hayati,Denizalti, Serpil,?zdemir, Ismail,?etinkaya, Engin,?etinkaya, Bekir
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- Semiconductor Photocatalysis: Effect of Light Intensity on Nanoscale CdS-Catalyzed Photolysis of Organic Substrates
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The relationship between light intensity and product distribution in semiconductor photocatalysis was investigated by using nanoscale CdS microcrystallites (CdS-0) as photocatalysts, triethylamine (TEA) as the electron donor, and either aromatic ketones, electron-deficient alkenes, or 1-benzylnicotinamide (BNA+) as substrates.In the case of the ketones and BNA+, the yield of their respective one-electron reduction products, pinacols and the dimer, (BNA)2, increases with decreasing light intensity.When alkenes are employed in the CdS-0 system, cis-trans photoisomerization always occur regardless of the light intensity.The kinetics for the photocatalysis of the alkanes and the measuement of the inital formation rate of active lattice Cd atoms (Cd0) (which act as catalytic sites for two-electron-transfer reductions) reveal that Cd0 formation is proportional to the square of the relative light intensity, Ir2.The chemoselectivity in the photocatalysis using nanoscale CdS should be affected by the quantity of the Cd0, whose formation strongly depends on the light intensity.
- Shiragami, Tsutomu,Fukami, Shinako,Wada, Yuji,Yanagida, Shozo
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- Melamine-Based Porous Organic Polymers Supported Pd(II)-Catalyzed Addition of Arylboronic Acids to Aromatic Aldehydes
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Abstract: A new type melamine-based porous organic polymers (SZU-1) has been synthesized with melamine and 2,2′-bipyridyl-5,5′-dialdehyde by a one-pot method and fully characterized. Divalent palladium salts were coordinated to this polymer network which successfully catalyzed the nucleophilic addition reaction of arylboronic acids to aromatic aldehydes. With only 1.0?mol% heterogeneous catalyst loading, high reaction yields (>?85%) can be achieved in most cases. The scope of substrates was also investigated and the catalyst showed universal applicability. Graphic Abstract: The loose and porous melamine-based porous organic polymers (SZU-1) are synthesized by melamine and 2,2′-bipyridyl-5,5′-dialdehyde. The performance of SZU-1 was characterized and most of the substrates achieved high yield (> 85%) in the catalytic performance test.[Figure not available: see fulltext.]
- Shen, Kai,Wen, Min,Fan, Chaogang,Lin, Shaohui,Pan, Qinmin
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p. 2612 - 2621
(2021/01/15)
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- Tunable System for Electrochemical Reduction of Ketones and Phthalimides
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Herein, we report an efficient, tunable system for electrochemical reduction of ketones and phthalimides at room temperature without the need for stoichiometric external reductants. By utilizing NaN3 as the electrolyte and graphite felt as both the cathode and the anode, we were able to selectively reduce the carbonyl groups of the substrates to alcohols, pinacols, or methylene groups by judiciously choosing the solvent and an acidic additive. The reaction conditions were compatible with a diverse array of functional groups, and phthalimides could undergo one-pot reductive cyclization to afford products with indolizidine scaffolds. Mechanistic studies showed that the reactions involved electron, proton, and hydrogen atom transfers. Importantly, an N3/HN3 cycle operated as a hydrogen atom shuttle, which was critical for reduction of the carbonyl groups to methylene groups.
- Chen, Gong,Qiao, Tianjiao,Wang, Yaxin,Zhang, Jian,Zhao, Jianyou
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supporting information
p. 3297 - 3302
(2021/10/14)
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- Ruthenium complexes of phosphine-amide based ligands as efficient catalysts for transfer hydrogenation reactions
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This work presents three mononuclear Ru(ii) complexes of tridentate phosphine-carboxamide based ligands providing a NNP coordination environment. The octahedral Ru(ii) ion shows additional coordination with co-ligands; CO, Cl and CH3OH. All three Ru(ii) complexes were thoroughly characterized including their crystal structures. These Ru(ii) complexes were utilized as catalysts for the transfer hydrogenation of assorted carbonyl compounds, including some challenging biologically relevant substrates, using isopropanol as the hydrogen source. The binding studies illustrated the coordination of the isopropoxide ion by replacing a Ru-ligated chloride ion followed by the generation of the Ru-H intermediate that was isolated and characterized and was found to be involved in the catalysis.
- Yadav, Samanta,Vijayan, Paranthaman,Yadav, Sunil,Gupta, Rajeev
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p. 3269 - 3279
(2021/03/16)
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- Enhanced catalytic activity of one-dimensional CdS @TiO2 core-shell nanocomposites for selective organic transformations under visible LED irradiation
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In this study, we are interested in the photocatalytic activity under visible LED irradiation of one- dimensional (1D) CdS @TiO2 core–shell nanocomposites (CSNs) prepared through a facile and convenient method. For the synthesis of 1D CdS@TiO2 core/shell structure, titania source (Tetrabutyl titanate) was hydrolyzed by water vapor transmission on the surface of CdS nanowires (NWs) which were prepared via solvothermal method. The characterization of 1D CdS@TiO2 core–shell nanocomposites (CdS@TiO2 CSNs) was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis spectroscopy, and UV–Vis diffuse reflectance spectroscopy (DRS). The as-synthesized sample was utilized for the selective reduction of nitro compounds to benzimidazole and anilide, and also the reduction of benzophenones to alcohol under blue LED irradiation. The 1D CdS@TiO2 CSNs exhibited enhanced photoactivity compared with the pure TiO2, CdS nanowires and commercial TiO2-P25. The excellent reusability of the photocatalyst was examined for six runs. The results demonstrated that the prepared sample has the potential to provide a promising visible light-driven photocatalyst for other organic transformations.
- Eskandari, Parvin,Kazemi, Foad,Ramdar, Moosa,Zand, Zahra
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- Polyoxometalate-Incorporated Framework as a Heterogeneous Catalyst for Selective Oxidation of C-H Bonds of Alkylbenzenes
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Developing new catalysts for highly efficient and selective oxidation of saturated C-H bonds is significant due to their thermodynamic strength. Via incorporation of PW12O403-, pyridine-2,5-dicarboxylic acids (pydc), and Fe(III) ions into one framework, a new polyoxometalate-based metal-organic framework, [HFe4O2(H2O)4(pydc)3PW12O40]·10.5H2O (FeW-PYDC), was successfully prepared by a hydrothermal method. Interestingly, FeW-PYDC features a three-dimensional porous structure with {Fe4O2} interconnecting with PW12O403- units. FeW-PYDC displayed excellent performance in the selective oxidation of C-H bonds of alkylbenzenes with high conversion (95.7%) and selectivity (96.6%). As an effective heterogeneous catalyst, FeW-PYDC demonstrates good reusability and structural stability.
- Hu, Xin,Ma, Pengtao,Niu, Jingyang,Wang, Hui,Wang, Jingping,Wang, Quanzhong,Wang, Yingyue,Xu, Baijie
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p. 7753 - 7761
(2021/06/27)
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- Bulky N-Heterocyclic-Carbene-Coordinated Palladium Catalysts for 1,2-Addition of Arylboron Compounds to Carbonyl Compounds
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The synthesis of primary, secondary, and tertiary alcohols by the 1,2-addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible N-heterocyclic carbene (NHC)-coordinated 2,6-di(pentan-3-yl)aniline (IPent)-based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS-IPent-CYP-catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2-addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
- Okuda, Yuta,Nagaoka, Masahiro,Yamamoto, Tetsuya
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p. 6291 - 6300
(2020/11/30)
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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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- Candida zeylanoides as whole-cell biocatalyst to perform asymmetric bioreduction of benzophenone derivatives
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Candida zeylanoides P1 was investigated as whole cell biocatalyst for the bioreduction of biaryl prochiral ketones into chiral carbinols, which can be used as pharmaceutical intermediate. Bioreduction of different biaryl ketones was carried out to their corresponding chiral biaryl carbinols such as (S)-(4-chlorophenyl) (phenyl) methanol (2a), which can be used in the synthesis of L-cloperastine drug, with antitussive, antiepidemic activity and bronchial musculature relaxant characteristics, in gram scale, enantiopure form (>99%) and excellent yields. The selectivity of C. zeylanoides P1 in enantioselective reduction of biaryl ketones was not affected by the steric and electronic effects of substrates. The current method demonstrates an encouraging green chemistry approach for the production of biaryl secondary chiral alcohols of pharmaceutical importance in mild, inexpensive and environmentally friendly process. The present study has many benefits since this yeast biocatalyst were successfully applied bioreduction of structurally bulky prochiral substrates, which cannot be reducted by chemical catalysis.
- ?ahin, Engin
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p. 612 - 619
(2020/01/22)
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- Capturing the Monomeric (L)CuH in NHC-Capped Cyclodextrin: Cavity-Controlled Chemoselective Hydrosilylation of α,β-Unsaturated Ketones
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The encapsulation of copper inside a cyclodextrin capped with an N-heterocyclic carbene (ICyD) allowed both to catch the elusive monomeric (L)CuH and a cavity-controlled chemoselective copper-catalyzed hydrosilylation of α,β-unsaturated ketones. Remarkably, (α-ICyD)CuCl promoted the 1,2-addition exclusively, while (β-ICyD)CuCl produced the fully reduced product. The chemoselectivity is controlled by the size of the cavity and weak interactions between the substrate and internal C?H bonds of the cyclodextrin.
- Bistri-Aslanoff, Olivia,Derat, Etienne,Leloux, Sébastien,Leyssens, Tom,Ménand, Micka?l,Meijide Suárez, Jorge,Riant, Olivier,Roland, Sylvain,Sollogoub, Matthieu,Xu, Guangcan,Zhang, Pinglu,Zhang, Yongmin
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supporting information
p. 7591 - 7597
(2020/03/23)
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- Nickel-Catalyzed Addition of Aryl Bromides to Aldehydes to Form Hindered Secondary Alcohols
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Transition-metal-catalyzed addition of aryl halides across carbonyls remains poorly developed, especially for aliphatic aldehydes and hindered substrate combinations. We report here that simple nickel complexes of bipyridine and PyBox can catalyze the addition of aryl halides to both aromatic and aliphatic aldehydes using zinc metal as the reducing agent. This convenient approach tolerates acidic functional groups that are not compatible with Grignard reactions, yet sterically hindered substrates still couple in high yield (33 examples, 70% average yield). Mechanistic studies show that an arylnickel, and not an arylzinc, adds efficiently to cyclohexanecarboxaldehyde, but only in the presence of a Lewis acid co-catalyst (ZnBr2).
- Garcia, Kevin J.,Gilbert, Michael M.,Weix, Daniel J.
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supporting information
p. 1823 - 1827
(2019/02/14)
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- Silver-Catalyzed Hydrogenation of Ketones under Mild Conditions
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The silver-catalyzed hydrogenation of ketones using H2 as hydrogen source is reported. Silver nanoparticles are generated from simple silver (I) salts and operate at 25 °C under 20 bar of hydrogen pressure. Various aliphatic and aromatic ketones, including natural products were reduced into the corresponding alcohols in high yields. This silver catalyst allows for the selective hydrogenation of ketones in the presence of other functional groups. (Figure presented.).
- Wang, Shengdong,Huang, Haiyun,Tsareva, Svetlana,Bruneau, Christian,Fischmeister, Cédric
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supporting information
p. 786 - 790
(2019/01/04)
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- I2/Li2CO3-promoted cyanation of diarylalcohols through a dual activation process
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One-step base promoted strategy for cyanation of α,α-diaryl alcohols has been developed under mild and transition metal-free conditions. This method provides a straightforward and facile way towards the synthesis of β,γ-unsaturated nitriles and α-phenylnitiriles from α-vinyl carbinols and α,α-diaryl methanols, respectively, up to 99% yield. Moreover, various azides and ethers could also be accessed from their respective nucleophiles under standard reaction conditions.
- Hu, Liangzhen,Hussain, Muhammad Ijaz,Deng, Qingfu,Liu, Qing,Feng, Yangyang,Zhang, Xiaohui,Xiong, Yan
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p. 308 - 314
(2018/12/11)
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- Synthesis and biological evaluation of new N-substituted 4-(arylmethoxy)piperidines as dopamine transporter inhibitors
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The library of new N-substituted 4-(arylmethoxy)piperidines as dopamine transporter inhibitors was designed and synthesized. H-Bond donors in piperidine ring were found to be important for reduced locomotor activity in mice. 4-[Bis(4-fluorophenyl)methoxy]piperidine has IC50 17.0 ± 1.0 nm for dopamine transporter and locomotor activity, which is lower than that for cocaine.
- Lapa, Gennady B.,Lapa, Alla A.
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p. 203 - 205
(2019/04/25)
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- Nickel Catalyzed Intermolecular Carbonyl Addition of Aryl Halide
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In this study, we develop a nickel-catalyzed carbonyl arylation reaction employing aldehydes with aryl and allyl halides. Various aryl, α,β-unsaturated aldehyde and aliphatic aldehydes can be converted into their corresponding secondary alcohols in moderate-to-high yields. In addition, we extended this approach to develop an asymmetric reductive coupling reaction that combines nickel salts with chiral bisoxazoline ligands to give secondary alcohols with moderate enantioselectivity.
- Ishida, Seima,Suzuki, Hiroyuki,Uchida, Seiichiro,Yamaguchi, Eiji,Itoh, Akichika
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supporting information
p. 7483 - 7487
(2019/12/11)
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- Diaryl hydroxylamines as pan or dual inhibitors of indoleamine 2,3-dioxygenase-1, indoleamine 2,3-dioxygenase-2 and tryptophan dioxygenase
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Tryptophan (Trp) catabolizing enzymes play an important and complex role in the development of cancer. Significant evidence implicates them in a range of inflammatory and immunosuppressive activities. Whereas inhibitors of indoleamine 2,3-dioxygenase-1 (IDO1) have been reported and analyzed in the clinic, fewer inhibitors have been described for tryptophan dioxygenase (TDO) and indoleamine 2,3-dioxygenase-2 (IDO2) which also have been implicated more recently in cancer, inflammation and immune control. Consequently the development of dual or pan inhibitors of these Trp catabolizing enzymes may represent a therapeutically important area of research. This is the first report to describe the development of dual and pan inhibitors of IDO1, TDO and IDO2.
- Winters, Maria,DuHadaway, James B.,Pham, Khoa N.,Lewis-Ballester, Ariel,Badir, Shorouk,Wai, Jenny,Sheikh, Eesha,Yeh, Syun-Ru,Prendergast, George C.,Muller, Alexander J.,Malachowski, William P.
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supporting information
p. 455 - 464
(2018/11/25)
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- Effect of Ancillary Ligand in Cyclometalated Ru(II)-NHC-Catalyzed Transfer Hydrogenation of Unsaturated Compounds
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In an effort to develop efficient Ru(II)-NHC-based catalyst considering their stereoelectronic effect for hydride-transfer reaction, we found that the ancillary NHC ligand can play a significant role in its catalytic performance. This effect is demonstrated by comparing the activity of two different types of orthometalated precatalysts of general formula [(p-cymene)(NHC)RuII(X)] (NHC = an imidazolylidene-based ImNHC, compound 2a-c, or a mesoionic triazolylidene-based tzNHC, compound 4) in transfer hydrogenation of carbonyl substrates. The electron-rich precatalyst, 2c, containing p-OMe-substituted NHC ligand performed significantly better than both unsubstituted complex 2a and p-CF3 substituted electron-poor complex 2b in ketone reduction. Whereas bulky mesoionic triazolylidene ligand containing complex 4 was found to be superior catalyst for aldehyde reduction and the precatalyst 2a is more suitable for the selective transfer hydrogenation of a wide range of aromatic aldimines to amines. To the best of our knowledge, this is the first systematic study on the effect of stereoelectronic tuning of ancillary orthometalated NHC ligand in Ru(II)-catalyzed transfer hydrogenations of various types of unsaturated compounds with broad substrate scope.
- Bauri, Somnath,Donthireddy,Illam, Praseetha Mathoor,Rit, Arnab
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supporting information
p. 14582 - 14593
(2018/11/25)
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- Rhenium and manganese complexes bearing amino-bis(phosphinite) ligands: Synthesis, characterization, and catalytic activity in hydrogenation of ketones
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A series of rhenium and manganese complexes supported by easily accessible and easily tunable amino-bisphosphinite ligands was prepared and characterized by NMR and IR spectroscopy, HR mass spectrometry, elemental analysis, and X-ray diffraction studies. These complexes have been tested in the hydrogenation of ketones. Notably, one of the rhenium complexes, bearing an NH moiety, proved significantly more active than the rest of the series. The reaction proceeds well at 120 °C, under 50 bar of H2, in the presence of 0.5 mol % of catalyst and 1 mol % of tBuOK. Interestingly, activation of the precatalyst could be followed stepwise by NMR and a rhenium hydride was characterized by X-ray diffraction studies.
- Li, Haoran,Wei, Duo,Bruneau-Voisine, Antoine,Ducamp, Maxime,Henrion, Micka?l,Roisnel, Thierry,Dorcet, Vincent,Darcel, Christophe,Carpentier, Jean-Fran?ois,Soulé, Jean-Fran?ois,Sortais, Jean-Baptiste
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supporting information
p. 1271 - 1279
(2018/04/30)
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- Kinetic studies on tetrabutylammonium bromochromate oxidation of some mono-and di-substituted benzhydrols
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The oxidation of 12 mono- and di-substituted benzhydrols (BH) by tetrabutylammonium bromochromate (TBABC) have been studied in aqueous acetic acid medium. Absence of any effect of added acrylonitrile on the reaction discounts the possibility of a one-electron oxidation, leading to the formation of free radicals. The tetrabutylammonium bromochromate oxidation of 12 mono- and di-substituted benzhydrols complies with the isokinetic relationship and Hammett relationship. The overall mechanism is proposed to involve a cyclic concerted symmetrical transition state leading to the product.
- Hemalatha,Asghar, Basim H.,Mansoor, S Sheik
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p. 821 - 826
(2018/03/13)
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- Employing Arynes for the Generation of Aryl Anion Equivalents and Subsequent Reaction with Aldehydes
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Arynes are highly reactive intermediates, which are utilized for the electrophilic arylation of various X-H bonds (X = O, N, S etc.). Herein, a new synthetic strategy is demonstrated, where arynes are converted into aryl anion equivalents by treatment with phosphines and a base. The addition of phosphines to arynes form the phosphonium salts, which in the presence of a carbonate base generates the aryl anion equivalent. Subsequent addition of the aryl anions with aldehydes afforded the secondary alcohols.
- Gaykar, Rahul N.,Bhunia, Anup,Biju, Akkattu T.
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supporting information
p. 11333 - 11340
(2018/07/21)
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- An Efficient Ga(OTf)3/Isopropanol Catalytic System for Direct Reduction of Benzylic Alcohols
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This study aims to report the first gallium-catalyzed direct reduction of benzylic alcohols using isopropanol as a reductant. The reaction proceeds via gallium catalyst-assisted hydride transfer of the in situ-generated benzylic isopropyl ether. The method generates only water and acetone as byproducts and thus provides an atom-economic and environmentally friendly approach to the synthesis of di- and triarylmethanes, which are important substructures in various bioactive compounds and functional materials. (Figure presented.).
- Sai, Masahiro
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supporting information
p. 4330 - 4335
(2018/10/15)
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- Substrate- and temperature-controlled divergence in reactions of alcohols with TosMIC catalyzed by BF3 · Et2O: Facile access to sulfinates and sulfones
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An efficient BF3 · Et2O-catalyzed divergent synthesis of sulfinate esters and sulfones through C–O and C–S bond formation has been achieved from alcohols and p-toluenesulfonylmethyl isocyanide (TosMIC). Various alcohols reacted smoothly with TosMIC under the present conditions at room temperature providing sulfinate esters exclusively. By tuning the reaction temperature, the alcohols that provide highly stabilized carbocation in the reaction medium afforded sulfones as sole products. This study was aimed at understanding the regioselectivity of ambidentate sulfinate ion and to elucidate the interpretation of sulfinate/sulfone scaffolds.
- Pogaku, Naresh,Krishna, Palakodety Radha,Prapurna, Y. Lakshmi
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supporting information
p. 1239 - 1249
(2017/07/06)
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- Method for preparing 4-chlorobenzhydrol
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The embodiment of the invention discloses a method for preparing 4-chlorobenzhydrol. The method comprises the following steps: (1) weighing 25 weight parts of sodium hydroxide to prepare 40% sodium hydroxide solution, adding 25 weight parts of 4- chlorobenzophenone into the sodium hydroxide solution, constantly stirring and heating in an oil bath; (2) adding zinc powder when the mixture in the step (1) is heated to 100 DEG C, constantly stirring and heating to 110-120 DEG C, and refluxing for 8 hours; (3) cooling and standing the reaction liquid for 30 minutes after the reaction is completed, separating the liquid to obtain an oil layer, and washing until the pH value is 6.5 with hot water, hydrochloric acid and hot water respectively and sequentially; (4) obtaining a crude product of 4-chlorobenzhydrol; and (5) recrystallizing and purifying the 4-chlorobenzhydrol. By implementing the embodiment, the method has the beneficial effects that the yield and purification of 4-chlorobenzhydrol can be effectively improved through experimental detection by combining actual preparation, thereby having an important actual meaning.
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Paragraph 0015; 0016; 0017; 0018; 0019; 0020; 0021-0028
(2017/06/02)
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- AlCl3 catalyzed coupling of: N-benzylic sulfonamides with 2-substituted cyanoacetates through carbon-nitrogen bond cleavage
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A new cross-coupling reaction of N-benzylic sulfonamides with 2-substituted cyanoacetates for the synthesis of 2-substituted benzylbenzene was reported. In the presence of AlCl3, a broad range of N-benzylic sulfonamides reacted smoothly with 2-substituted cyanoacetates to afford structurally diverse benzylbenzenes in moderate to excellent yields. The conversion could be enlarged to gram-scale efficiently. The practicability of this approach was further manifested in the synthesis of a related bioactive agent with high anti-inflammatory activity.
- Hu, Chen,Hong, Gang,Qian, Xiaofei,Kim, Kwang Rim,Zhu, Xiaoyan,Wang, Limin
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supporting information
p. 4984 - 4991
(2017/07/10)
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- Synthesis and Catalytic Asymmetric Applications of Quinazolinol Ligands
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A range of chiral quinazolinol ligands were efficiently synthesized and subsequently investigated for catalytic chiral induction in both the asymmetric phenylation of aryl aldehydes and the asymmetric epoxidation of chalcones. Encouragingly, high enantioselectivities (up to 95%) and yields (up to 98%) were achieved under the optimized reaction conditions.
- Karakaya, Idris,Karabuga, Semistan,Mart, Mehmet,Altundas, Ramazan,Ulukanli, Sabri
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p. 1719 - 1726
(2016/05/24)
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- Newly synthesized furanoside-based NHC ligands for the arylation of aldehydes
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New furanoside-based NHC precursor salts (2) were synthesized using amino alcohols from the chloralose derivatives of glucose (a), galactose (b), and mannose (c). The novel compounds were fully characterized by 1H NMR, 13C NMR, and elemental analyses. The catalytic activities of these salts were tested in the arylation of aldehydes as catalysts that were generated in situ from [RhCl(COD)]2. In addition, 2a was converted to the rhodium complex 3a in order to compare the results obtained in situ. The newly synthesized compounds were very efficient in terms of yield; nevertheless they did not exhibit a chiral induction.
- Denizalti, Serpil,?etin Telli, Fatma,Yildiran, Selin,Salman, Azize Ye?im,?etinkaya, Bekir
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p. 689 - 697
(2016/11/09)
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- Hydroxyl group effect in novel NNN type pyridine based ruthenium (II) complex for the transfer hydrogenation of ketones
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The new NNN type pyridine ligands were prepared by using low cost and readily available starting materials and metalated with RuCl2(PPh3)3 to obtain ruthenium(II) complexes. All structures were illuminated by NMR, HRMS, and FT-IR spectroscopy. The complexes exhibited good catalytic activity in transfer hydrogen reaction of ketones and it was found that a hydroxyl group on β-position of the pyridine ring had a dramatic effect on the catalyst efficiency.
- Sahin, Irfan,Emir, Sedat,Ispir, Esin,Karakaya, Idris,Gumus, Selcuk,Ulusoy, Mahmut,Karabuga, Semistan
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- Synthesis and Anticancer Activity of 1-(1H -Indol-3-yl)-2-(4-diarylmethylpiperazine-1-yl)ethane-1,2-dione Derivatives
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Several new 1-(4-diarylmethylpiperazine-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione derivatives were synthesized by acylation of 1-diarylmethylpiperazine with 2-(1H-indol-3-yl)-2-oxoacetyl chloride. Their structures were confirmed by 1H NMR, IR, mass spectra, and elemental analysis. These compounds were further evaluated for their anticancer activity, and most of them were found to have moderate-to-potent antiproliferative activities against Hela, A-549, and ECA-109 cancer cell lines in vitro.
- Jiang, Jun-Rong,Xu, Feng,Wu, Han-Gui
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- Highly selective direct azidation of alcohols over a heterogeneous povidone-phosphotungstic solid acid catalyst
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A simple protocol for the selective azidation of alcohols is developed using a solid acid hybrid of a povidone and phosphotungstic acid (PVP-PWA) using azidotrimethylsilane as an azide source at room temperature. In a broad substrate scope, various activated as well as unactivated benzylic and diphenyl alcohols were treated smoothly with TMS-N3 to selectively produce only azide products with excellent yields in a very short reaction time of 2 h. FT-IR confirmed the stability of the catalyst with retention of the Keggins structure after the reaction. Recycling experiments demonstrated the reusability of the PVP-PWA (3?:?1) several times without losing its original activity.
- Kamble, Sumit,More, Sagar,Rode, Chandrashekhar
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supporting information
p. 10240 - 10245
(2016/12/06)
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- Synthetic method of diaryl methanol compound
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The invention discloses a synthetic method of a diaryl methanol compound. Compared with a reported method for obtaining the diaryl methanol compound through catalytic reduction by taking diaryl ketone as an initial raw material, the method is characterized by taking substituted benzyl bromide and substituted phenylboronic acid which are cheap and easy to obtain as initial raw materials, reacting for 4 hours in an alkaline solution, water or a mixed solvent of the water and an organic solvent under room temperature in air, and carrying out simple separation and purification operation, thus obtaining a pure product. A catalyst adopted in the method is a palladium compound/an in-situ catalytic system prepared from phosphorus- and oxygen-containing carboxylic acids ligands, the catalytic system is cheap in price, high in catalytic activity and good in selectivity and is stable in the air and a water solution, the diaryl methanol compound is compounded through a method of catalyzing the substituted benzyl bromide and the substituted phenylboronic acid and a 'one-pot reaction method' of hydrogen peroxide, the reaction steps are less, after-treatment is simple, the product is easy to separate and purify, the yield is high, and the mixed solvent is prepared from cheap and easy-to-obtain water and the organic solvent, so that the environment is not polluted, and environment protection is realized.
- -
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Paragraph 0056-0058
(2017/04/03)
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- Exploring the Reactivity of α-Lithiated Aryl Benzyl Ethers: Inhibition of the [1,2]-Wittig Rearrangement and the Mechanistic Proposal Revisited
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By carefully controlling the reaction temperature, treatment of aryl benzyl ethers with tBuLi selectively leads to α-lithiation, generating stable organolithiums that can be directly trapped with a variety of selected electrophiles, before they can undergo the expected [1,2]-Wittig rearrangement. This rearrangement has been deeply studied, both experimentally and computationally, with aryl α-lithiated benzyl ethers bearing different substituents at the aryl ring. The obtained results support the competence of a concerted anionic intramolecular addition/elimination sequence and a radical dissociation/recombination sequence for explaining the tendency of migration for aryl groups. The more favored rearrangements are found for substrates with electron-poor aryl groups that favor the anionic pathway.
- Velasco, Rocío,Silva López, Carlos,Nieto Faza, Olalla,Sanz, Roberto
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p. 15058 - 15068
(2016/10/11)
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- Recyclable and reusable Pd(OAc)2/P(1-Nap)3/[bmim][PF6]/H2O system for the addition of arylboronic acids to aldehydes
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A stable and efficient Pd(OAc)2/P(1-Nap)3[tri(1-naphthyl)phosphine] catalytic system for the addition of arylboronic acids to aldehydes has been developed. In the presence of Pd(OAc)2 and P(1-Nap)3, the addition reaction of arylboronic acids with aldehydes was carried out smoothly at 65 °C to give a variety of carbinol derivatives in good to excellent yields using a mixture of [bmim][PF6] and water as the solvent. The isolation of the products was readily performed by the extraction with diethyl ether, and the Pd(OAc)2/P(1-Nap)3/[bmim][PF6]/H2O system could be easily recycled and reused six times without significant loss of catalytic activity. Our system not only avoids the use of easily volatile THF or toluene as solvent but also solves the basic problem of palladium catalyst and these phosphine ligand reuse.
- Zhao, Hong,Cheng, Mingzhu,Zhang, Tinli,Cai, Mingzhong
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- The carbonyl group tuned electron-deficient phosphorus ligands and their application in Rhodium catalyzed arylation to aldehydes
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Acylphosphines, which could be efficiently prepared from acid chlorides and secondary phosphines, were developed as a type of carbonyl group tuned electron-deficient phosphorus ligand. They were found to be a kind of efficient ligand in Rhodium catalyzed arylation to aldehydes through accelerating the transmetalation process. Chiral acylphosphine ligands could be generated from carboxylic acids bearing the chiral framework correspondingly.
- Yang, Jiefang,Chen, Xingyu,Wang, Zhiqian
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supporting information
p. 5673 - 5675
(2015/09/15)
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- Boron Trifluoride?Diethyl Ether-Catalyzed Etherification of Alcohols: A Metal-Free Pathway to Diphenylmethyl Ethers
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A novel boron trifluoride?diethyl ether (BF3?OEt2)-catalyzed etherification procedure has been developed in which primary and secondary alcohols are easily converted into diphenylmethyl ethers with yields of up to 99%.
- Li, Jiaqiang,Zhang, Xiaohui,Shen, Hang,Liu, Qing,Pan, Jing,Hu, Wen,Xiong, Yan,Chen, Changguo
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supporting information
p. 3115 - 3120
(2015/11/03)
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- UV light-mediated difunctionalization of alkenes through aroyl radical addition/1,4-/1,2-Aryl shift cascade reactions
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UV light-mediated difunctionalization of alkenes through an aroyl radical addition/1,4-/1,2-aryl shift has been described. The resulted aroyl radical from a photocleavage reaction added to acrylamide compounds followed by cyclization led to the formation of oxindoles, whereas the addition to cinnamic amides aroused a unique 1,4-aryl shift reaction. Furthermore, the difunctionalization of alkenes of prop-2-en-1-ols was also achieved through aroyl radical addition and a sequential 1,2-aryl shift cascade reaction.
- Zheng, Lewei,Huang, Hongli,Yang, Chao,Xia, Wujiong
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supporting information
p. 1034 - 1037
(2015/03/30)
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- An unusual chemoselective oxidation strategy by an unprecedented exploration of an electrophilic center of DMSO: A new facet to classical DMSO oxidation
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A conceptually new dimethyl sulfoxide (DMSO) based oxidation process without the use of any activator has been demonstrated for the oxidation of active methylenes and benzhydrols. The developed protocol utilizes the electrophilic center of DMSO for oxidation, which was unexplored before. Mechanistic investigation has confirmed that the source of oxygen is DMSO.
- Chebolu, Rajesh,Bahuguna, Ashish,Sharma, Reena,Mishra, Vivek Kumar,Ravikumar
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supporting information
p. 15438 - 15441
(2015/10/20)
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- Palladium-catalyzed arylation of aldehydes with bromo-substituted 1,3-diaryl-imidazoline carbene ligand
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The combination of 0 valent palladium precursor and bromo-substituted 1,3-diaryl-imidazoline carbene ligand precursor such as 1-(2-bromophenyl)-3-(2,6-diisopropylphenyl)-imidazolinium chloride 1a exhibited high catalytic activity for the 1,2-addition of arylboronic acids to aldehydes including aqueous formaldehyde.
- Yamamoto, Tetsuya,Furusawa, Takuma,Zhumagazin, Azamat,Yamakawa, Tetsu,Oe, Yohei,Ohta, Tetsuo
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- Enantioselective transfer reaction of phenyl to aldehydes using L-Proline-derived amino alcohols as chiral ligands
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((S)-1-(1,3,5-trimethyl)benzylpyrrolidin-2-yl)diphenylmethanol (1d) was found to be an effective chiral ligand in the asymmetric transfer reaction of phenyl to aldehydes to give the corresponding adducts in excellent enantioselectivity (up to 98% ee) with very high yields (up to 99%).
- Liu, Yongmin,Bo, Rongcheng,Wu, Nan,Qiao, Yuehua,Li, Yong,Wu, Hui,Xu, Zhou
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p. 356 - 360
(2014/05/20)
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- Chelating alkoxy NHC-Rh(I) complexes and their applications in the arylation of aldehydes
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In this study, new rhodium(I) complexes (5 and 6) have been prepared by the reaction of [RhCl(COD)]2 with a series of imidazolium salts (3 and 4), which were obtained from a chiral amino alcohol. The catalytic activities of these complexes were tested in the arylation of aldehydes. It was found that the synthesized rhodium complexes were highly effective catalysts for the arylation of aldehydes in short reaction times (5 min, TOF = 1193 h -1). However, the obtained ee values (up to 32% ee) remained low. We have proposed a mechanism for the arylation reaction of aldehydes, which is confirmed via 19F NMR spectroscopy.
- Denizalti, Serpil,Türkmen, Hayati,?etinkaya, Bekir
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supporting information
p. 4129 - 4132
(2014/07/22)
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- Highly efficient homogeneous and heterogenized ruthenium catalysts for transfer hydrogenation of carbonyl compounds
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[Ru(acac)2(CH3CN)2] was synthesized from [Ru(acac)3] by refluxing it with zinc powder in ethanol-acetonitrile mixture. The prepared catalyst was characterized by FT-IR, 1H and 13C NMR techniques. The silica supported catalyst ('SiO 2'-NH2-RuII) was prepared by stirring [Ru(acac)2(CH3CN)2] with 'SiO 2'-NH2 in a 1:1 mixture of CH2Cl 2-toluene for 3 days at room temperature. It was characterized by FT-IR, SEM, solid state NMR, ICP and BET surface area methods. The transfer hydrogenation reaction of carbonyl compounds was carried out separately using [Ru(acac)2(CH3CN)2] and 'SiO 2'-NH2-RuII as catalysts. The reaction conditions were optimized with different solvents, bases, catalyst amounts and temperatures using acetophenone as a model system. The scope of the reaction was extended to various substituted aryl ketones including heteroaryl ketones. This journal is the Partner Organisations 2014.
- Ganesamoorthy,Jerome,Shanmugasundaram,Karvembu
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p. 27955 - 27962
(2014/07/21)
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- Stereoselective synthesis of (z)-1-benzhydryl-4-cinnamylpiperazines via the wittig reaction
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A synthetic method of producing (E)- and (Z)-isomers of 1-benzhydryl-4-cinnamylpiperazines in a specific ratio from corresponding benzhydrylpiperazine is described. Of the three compounds synthesized (5a-c), the ratio of E/Z-isomers remained around 15:85. The key intermediates, 1-benzhydryl-4-(2,2-dimethoxyethyl)piperazine derivatives (3a-c), were prepared by nucleophilic substitution reaction of benzhydrylpiperazines (2a-c) with chloroacetaldehyde dimethylacetal in good yield (up to 88%). Hydrolysis of 3a-c gave the corresponding aldehydes 4a-c, which when subjected to the Wittig reaction followed by column purification to afford 1a-c (E-isomers) and 6a-c (Z-isomers) in pure form. The isolated compounds were characterized by NMR and mass spectral analysis. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.] Copyright
- Shivprakash,Reddy, G. Chandrasekara
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supporting information
p. 600 - 609
(2014/01/17)
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- Synthesis and cytotoxicity studies of novel benzhydrylpiperazine carboxamide and thioamide derivatives
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Synthesis and cytotoxic activities of 32 benzhydrylpiperazine derivatives with carboxamide and thioamide moieties were reported. In vitro cytotoxic activities of compounds were screened against hepatocellular (HUH-7), breast (MCF-7) and colorectal (HCT-116) cancer cell lines by sulphorhodamine B assay. In general, 4-chlorobenzhydrylpiperazine derivatives were more cytotoxic than other compounds. In addition, thioamide derivatives (6a-g) have higher growth inhibition than their carboxamide analogs.
- Gurdal, Enise Ece,Durmaz, Irem,Cetin-Atalay, Rengul,Yarim, Mine
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p. 205 - 214
(2014/04/03)
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- A mild and efficient flow procedure for the transfer hydrogenation of ketones and aldehydes using hydrous zirconia
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A flow chemistry Meerwein-Ponndorf-Verley (MPV) reduction procedure using partially hydrated zirconium oxide via a machine-assisted approach is reported. The heterogeneous reductive system could be applied to a wide range of functionalized substrates, allowing clean and fast delivery of the alcohol products within a few minutes (6-75 min). In three examples the system was scaled to deliver 50 mmol of product.
- Battilocchio, Claudio,Hawkins, Joel M.,Ley, Steven V.
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supporting information
p. 2278 - 2281
(2013/06/05)
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- Half-sandwich ruthenium(II) complexes of click generated 1,2,3-triazole based organosulfur/-selenium ligands: Structural and donor site dependent catalytic oxidation and transfer hydrogenation aspects
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1-Benzyl-4-((phenylthio)-/(phenylseleno)methyl)-1H-1,2,3-triazole (L1/L2) and 4-phenyl-1-((phenylthio)-/(phenylseleno)methyl)-1H-1,2,3-triazole (L3/L4) synthesized using the click reaction have been reacted for the first time with [{(η6-C6H6)RuCl(μ-Cl)}2] and NH4PF6 to design the half-sandwich complexes [(η6-benzene)RuLCl]PF6 (1-4 for L = L1-L4), which have been characterized by single-crystal X-ray diffraction and explored for the catalytic oxidation of alcohols with N-methylmorpholine N-oxide (NMO) and transfer hydrogenation of ketones with 2-propanol. There is a pseudo-octahedral "piano-stool" disposition of donor atoms around Ru in 1-4. In 1 and 2, N(3) of the triazole skeleton coordinates with Ru, whereas in other complexes the nitrogen involved is N(2). The Ru-S and Ru-Se bond distances are 2.3847(11)/2.3893(10) and 2.497(5)/2.4859(9) A, respectively. The catalytic processes are more efficient with 3 and 4 (compared to 1 and 2), in which N(2) of the triazole is involved in coordination with Ru. The nature of the chalcogen and steric factors together also appear to affect the efficiency of complexes. HOMO-LUMO energy gaps are lower for 3 and 4 than for 1 and 2. The formation of RuIV=O species probably results in oxidation and transfer hydrogenation involves an intermediate containing Ru-H. Bond distances and angles based on DFT calculations are generally consistent with experimental values.
- Saleem, Fariha,Rao, Gyandshwar Kumar,Kumar, Arun,Mukherjee, Goutam,Singh, Ajai K.
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p. 3595 - 3603
(2013/07/26)
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- Mg/Triethylammonium formate: A useful system for reductive dimerization of araldehydes into pinacols; Nitroarenes into azoarenes and azoarenes into hydrazoarenes
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Studies are reported which describes the effectiveness of triethylammonium formate in the presence of magnesium for the efficient intermolecular pinacol coupling using MeOH as solvent, Various aromatic carbonyls underwent smooth reductive coupling to give the corresponding I ,2-diols. A series of azo compounds were obtained by the reductive coupling of nitroaromatics while azo compounds were reduced to the corresponding hydrazoarenes by this system. There was no adverse effect on the other reducible and hydrogenolysable groups such as ether linkage, hydroxy and halogens. The reactions are clean, high yielding and inexpensive. All the reactions proceeded smoothly at ambient temperature.
- Pamar, M. Geeta,Govender,Muthusamy,Krause, Ruiw M.,Nanjundaswamy
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p. 969 - 974
(2014/03/21)
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- Engineering an enantioselective amine oxidase for the synthesis of pharmaceutical building blocks and alkaloid natural products
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The development of cost-effective and sustainable catalytic methods for the production of enantiomerically pure chiral amines is a key challenge facing the pharmaceutical and fine chemical industries. This challenge is highlighted by the estimate that 40-45% of drug candidates contain a chiral amine, fueling a demand for broadly applicable synthetic methods that deliver target structures in high yield and enantiomeric excess. Herein we describe the development and application of a "toolbox" of monoamine oxidase variants from Aspergillus niger (MAO-N) which display remarkable substrate scope and tolerance for sterically demanding motifs, including a new variant, which exhibits high activity and enantioselectivity toward substrates containing the aminodiphenylmethane (benzhydrylamine) template. By combining rational structure-guided engineering with high-throughput screening, it has been possible to expand the substrate scope of MAO-N to accommodate amine substrates containing bulky aryl substituents. These engineered MAO-N biocatalysts have been applied in deracemization reactions for the efficient asymmetric synthesis of the generic active pharmaceutical ingredients Solifenacin and Levocetirizine as well as the natural products (R)-coniine, (R)-eleagnine, and (R)-leptaflorine. We also report a novel MAO-N mediated asymmetric oxidative Pictet-Spengler approach to the synthesis of (R)-harmicine.
- Ghislieri, Diego,Green, Anthony P.,Pontini, Marta,Willies, Simon C.,Rowles, Ian,Frank, Annika,Grogan, Gideon,Turner, Nicholas J.
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supporting information
p. 10863 - 10869
(2013/08/23)
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- Direct electrosynthesis of ketones from benzylic methylenes by electrooxidative C-H activation
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Electrify your chemistry! Direct electrosynthesis of ketones from benzylic methylenes in an undivided cell was realized in moderate to good yields (see scheme). In this electrosynthesis, electrons instead of conventional oxidants and catalysts are employed to make the reaction environmentally benign. Moreover, the reaction intermediate radical was detected by ESR spectroscopy and the reaction mechanism was clarified.
- Meng, Li,Su, Jihu,Zha, Zhenggen,Zhang, Li,Zhang, Zhenlei,Wang, Zhiyong
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supporting information
p. 5542 - 5545
(2013/05/23)
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