- Oxidation of certain 4-substituted phenethyl alcohols with Collins reagent: On the mechanism of a carbon-carbon bond cleavage
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A mechanism is proposed for a carbon-carbon bond cleavage observed in the oxidation of certain 4-substituted phenethyl alcohols with Collins reagent.
- Li,Johnson
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Read Online
- Synthetic Access to gem-Difluoropropargyl Vinyl Ethers and Their Application to Propargyl Claisen Rearrangement
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With the increasing importance of fluorine to medicinal chemistry and other areas, methods to access various fluorinated compounds are needed. Herein, we report the synthesis of difluoropropargyl vinyl ethers from ketones and aldehydes using difluoropropargyl bromide dicobalt complexes. We applied difluoropropargyl vinyl ethers to the synthesis of difluorodienone or difluoroallene under thermal conditions and trifluoro-pyran under acid-catalyzed conditions.
- Okamura, Toshitaka,Koyamada, Kenta,Kanazawa, Junichiro,Miyamoto, Kazunori,Iwabuchi, Yoshiharu,Uchiyama, Masanobu,Kanoh, Naoki
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p. 1911 - 1924
(2020/12/23)
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- Regioselective, Diastereoselective, and Enantioselective One-Pot Tandem Reaction Based on an in Situ Formed Reductant: Preparation of 2,3-Disubstituted 1,5-Benzodiazepine
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The 1,5-benzodiazepines are important skeletons frequently contained in medicinal chemistry. Herein, we described an unexpected tandem cyclization/transfer hydrogenation reaction for obtaining chiral 2,3-disubstituted 1,5-benzodiazepines. The enolizable aryl aldehydes were chosen as substrates to react with symmetric and unsymmetric o-phenylenediamines. The unforeseen tandem reaction occurred among many possible latent side reactions under chiral phosphoric acid catalysis and affords the corresponding products in moderate yields and regioselectivities, good diastereoselectivities, and enantiomeric ratio (up to 99:1).
- Yang, Gao-Feng,Li, Guang-Xun,Huang, Jin,Fu, Ding-Qiang,Nie, Xiao-Kang,Cui, Xin,Zhao, Jin-Zhong,Tang, Zhuo
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p. 5110 - 5119
(2021/04/12)
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- High-Level Production of Phenylacetaldehyde using Fusion-Tagged Styrene Oxide Isomerase
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An order-of-magnitude improvement in the production of phenylacetaldehyde to 3.37 M (405 g L?1) from the enzymatic isomerisation of styrene oxide was achieved. A small ubiquitin-related modifier (SUMO) tag increases the productivity of the whole-cell biocatalytic system by enhancing the expression of active membrane-bound styrene oxide isomerase (SOI) while retaining enzyme catalytic efficiency and broad natural substrate scope. The isomerisation was performed by using Escherichia coli expressing SUMO-tagged SOI in an organic-aqueous biphasic system to yield 96% of phenylacetaldehyde. (Figure presented.).
- Choo, Joel P. S.,Kammerer, Richard A.,Li, Xiaodan,Li, Zhi
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p. 1714 - 1721
(2021/02/12)
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- Structural and Biochemical Studies Enlighten the Unspecific Peroxygenase from Hypoxylon sp. EC38 as an Efficient Oxidative Biocatalyst
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Unspecific peroxygenases (UPOs) are glycosylated fungal enzymes that can selectively oxidize C-H bonds. UPOs employ hydrogen peroxide as the oxygen donor and reductant. With such an easy-to-handle cosubstrate and without the need for a reducing agent, UPOs are emerging as convenient oxidative biocatalysts. Here, an unspecific peroxygenase from Hypoxylon sp. EC38 (HspUPO) was identified in an activity-based screen of six putative peroxygenase enzymes that were heterologously expressed in Pichia pastoris. The enzyme was found to tolerate selected organic solvents such as acetonitrile and acetone. HspUPO is a versatile catalyst performing various reactions, such as the oxidation of prim- and sec-alcohols, epoxidations, and hydroxylations. Semipreparative biotransformations were demonstrated for the nonenantioselective oxidation of racemic 1-phenylethanol rac-1b (TON = 13 000), giving the product with 88% isolated yield, and the oxidation of indole 6a to give indigo 6b (TON = 2800) with 98% isolated yield. HspUPO features a compact and rigid three-dimensional conformation that wraps around the heme and defines a funnel-shaped tunnel that leads to the heme iron from the protein surface. The tunnel extends along a distance of about 12 ? with a fairly constant diameter in its innermost segment. Its surface comprises both hydrophobic and hydrophilic groups for dealing with substrates of variable polarities. The structural investigation of several protein-ligand complexes revealed that the active site of HspUPO is accessible to molecules of varying bulkiness with minimal or no conformational changes, explaining the relatively broad substrate scope of the enzyme. With its convenient expression system, robust operational properties, relatively small size, well-defined structural features, and diverse reaction scope, HspUPO is an exploitable candidate for peroxygenase-based biocatalysis.
- Ebner, Katharina,Glieder, Anton,Kroutil, Wolfgang,Mattevi, Andrea,Rinnofner, Claudia,Rotilio, Laura,Swoboda, Alexander
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p. 11511 - 11525
(2021/09/22)
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- Oxoiron(v) mediated selective electrochemical oxygenation of unactivated C-H and CC bonds using water as the oxygen source
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An efficient electrochemical method for the selective oxidation of C-H bonds of unactivated alkanes (BDE ≤97 kcal mol-1) and CC bonds of alkenes using a biomimetic iron complex, [(bTAML)FeIII-OH2]-, as the redox mediator in an undivided electrochemical cell with inexpensive carbon and nickel electrodes is reported. The O-atom of water remains the source of O-incorporation in the product formed after oxidation. The products formed upon oxidation of C-H bonds display very high regioselectivity (75:1, 3°:2° for adamantane) and stereo-retention (RC ~99% for cyclohexane derivatives). The substrate scope includes natural products such as cedryl acetate and ambroxide. For alkenes, epoxides were obtained as the sole product. Mechanistic studies show the involvement of a high-valent oxoiron(v) species, [(bTAML)FeV(O)]- formed via PCET (overall 2H+/2e-) from [(bTAML)FeIII-OH2]- in CPE at 0.80 V (vs. Ag/AgNO3). Moreover, electrokinetic studies for the oxidation of C-H bonds indicate a second-order reaction with the C-H abstraction by oxoiron(v) being the rate-determining step.
- Chandra, Bittu,Gupta, Sayam Sen,Hellan, K. M.,Pattanayak, Santanu
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p. 11877 - 11885
(2020/11/18)
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- Magnetically recoverable porphyrin-based nanocatalysts for the effective oxidation of olefins with hydrogen peroxide: A comparative study
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In this paper, preparation, characterization and catalytic applications of metalloporphyrin-based magnetic nanocatalysts were investigated. meso-Tetrakis(4-carboxyphenyl)porphyrinatoiron(iii) chloride (Fe(TCPP)Cl) and meso-tetrakis(4-carboxyphenyl)porphyrinatomanganese(iii) acetate (Mn(TCPP)OAc) were separately immobilized onto the surface of amine functionalized magnetic nanoparticles (Fe3O4/SiO2/NH2) via covalent attachment. The obtained nanocatalysts were characterized using FT-IR and UV-Vis and atomic absorption spectroscopy, X-ray powder diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The catalytic efficiency of Fe3O4/SiO2/NH2-Fe(TCPP)Cl and Fe3O4/SiO2/NH2-Mn(TCPP)OAc for the green oxidation of alkenes with H2O2 was investigated in a comparative manner. The Mn-porphyrin based magnetic nanocatalyst shows higher catalytic efficiency compared to the Fe-porphyrin. In addition, the prepared magnetic nanocatalyst exhibited excellent reusability and could be reused at least five times without significant leaching or loss of activity. This journal is
- Rayati, Saeed,Moradi, Dana,Nejabat, Fatemeh
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p. 19385 - 19392
(2020/11/23)
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- Manganese and rhenium-catalyzed selective reduction of esters to aldehydes with hydrosilanes
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The selective reduction of esters to aldehydes, via the formation of stable alkyl silyl acetals, was, for the first time, achieved with both manganese, -Mn2(CO)10- and rhenium -Re2(CO)10- catalysts in the presence of triethylsilane as reductant. These two methods provide a direct access to a large variety of aliphatic and aromatic alkyl silyl acetals (30 examples) and to the corresponding aldehydes (13 examples) upon hydrolysis. The reactions proceeded in excellent yields and high selectivity at room temperature under photo-irradiation conditions (LED, 365 nm, 40 W, 9 h).
- Wei, Duo,Buhaibeh, Ruqaya,Canac, Yves,Sortais, Jean-Baptiste
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p. 11617 - 11620
(2020/10/19)
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- Deoxygenation of Epoxides with Carbon Monoxide
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The use of carbon monoxide as a direct reducing agent for the deoxygenation of terminal and internal epoxides to the respective olefins is presented. This reaction is homogeneously catalyzed by a carbonyl pincer-iridium(I) complex in combination with a Lewis acid co-catalyst to achieve a pre-activation of the epoxide substrate, as well as the elimination of CO2 from a γ-2-iridabutyrolactone intermediate. Especially terminal alkyl epoxides react smoothly and without significant isomerization to the internal olefins under CO atmosphere in benzene or toluene at 80–120 °C. Detailed investigations reveal a substrate-dependent change in the mechanism for the epoxide C?O bond activation between an oxidative addition under retention of the configuration and an SN2 reaction that leads to an inversion of the configuration.
- Maulbetsch, Theo,Jürgens, Eva,Kunz, Doris
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p. 10634 - 10640
(2020/07/30)
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- Copper-Catalyzed Ring-Opening/Reconstruction of Anthranils with Oxo-Compounds: Synthesis of Quinoline Derivatives
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A copper-catalyzed protocol for the construction of various 2-aryl(alkyl)-3-acylquinolines or 3-arylquinolines using readily available anthranils and 1,3-diketones or aldehydes as starting materials is reported herein. Dioxygen as the sole oxidant and hexafluoroisopropanol as the solvent play an important role in both procedures. This ring-opening/reconstruction strategy involving N-O bond cleavage and C-N/C-C bond formation features high yields and broad substrate scope.
- Zou, Liang-Hua,Zhu, Hao,Zhu, Shuai,Shi, Kai,Yan, Cheng,Li, Ping-Gui
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p. 12301 - 12313
(2019/10/11)
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- Stereoselective Synthesis of Vinylboronates by Rh-Catalyzed Borylation of Stereoisomeric Mixtures
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The stereoselective preparation of vinylboronates via rhodium-catalyzed borylation of E/Z mixtures of vinyl actetates is described, and this method was also extended to synthesis of vinyldiboronates. These transformations feature high functional group compatibility and mild reaction conditions. Control experiments support a mechanism that involved a Rh-catalyzed borylation-isomerization sequence. The isomerization of (Z)-vinylboronates to (E)-isomers was also demonstrated.
- Li, Shenhuan,Li, Jie,Xia, Tianlai,Zhao, Wanxiang
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supporting information
p. 462 - 468
(2019/03/28)
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- Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
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Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
- Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
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- Synthesizing method for oxidizing cobalt and manganese-based composite oxide catalyzed alcohol into aldehyde or ketone
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The invention discloses a synthesizing method for oxidizing cobalt and manganese-based composite oxide catalyzed alcohol into aldehyde or ketone and belongs to the technical field of aldehyde or ketone synthesis. According to the method, under the action
- -
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Paragraph 0051; 0052; 0053; 0054; 0055
(2018/07/15)
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- An efficient oxidation of alcohols by aqueous H2O2 with 1,3-dibromo-5,5-dimethylhydantoin
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An efficient protocol is described for the oxidation of alcohols to the corresponding aldehydes or ketones with 1,3-dibromo-5,5-dimethylhydantoin in the presence of aqueous H2O2.
- Lee, Jieun,Lee, Jong Chan
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p. 895 - 898
(2018/11/06)
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- Photoredox Cyanomethylation of Indoles: Catalyst Modification and Mechanism
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The direct cyanomethylation of indoles at the 2- or 3-position was achieved via photoredox catalysis. The versatile nitrile synthon is introduced as a radical generated from bromoacetonitrile, a photocatalyst, and blue LED as a light source. The mechanism of the reaction is explored by determination of the Stern-Volmer quenching constants. By combining photophysical data and mass spectrometry to follow the catalyst decomposition, the catalyst ligands were tuned to enable synthetically useful yields of radical coupling products. A range of indole substrates with alkyl, aryl, halogen, ester, and ether functional groups participate in the reaction, affording products in 16-90% yields. The reaction allows the rapid construction of synthetically useful cyanomethylindoles, products that otherwise require several synthetic steps.
- O'Brien, Connor J.,Droege, Daniel G.,Jiu, Alexander Y.,Gandhi, Shivaani S.,Paras, Nick A.,Olson, Steven H.,Conrad, Jay
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p. 8926 - 8935
(2018/07/05)
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- Manganese-Catalyzed Dual-Deoxygenative Coupling of Primary Alcohols with 2-Arylethanols
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Reported herein is a general and efficient dual-deoxygenative coupling of primary alcohols with 2-arylethanols catalyzed by a well-defined Mn/PNP pincer complex. This reaction is the first example of the catalytic dual-deoxygenation of alcohols using a non-noble-metal catalyst. Both deoxygenative homocoupling of 2-arylethanols (17 examples) and their deoxygenative cross-coupling with other primary alcohols (20 examples) proceeded smoothly to form the corresponding alkenes by a dehydrogenation and deformylation reaction sequence.
- Wang, Yujie,Shao, Zhihui,Zhang, Kun,Liu, Qiang
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supporting information
p. 15143 - 15147
(2018/11/01)
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- Stereoselective synthesis of 3,4-di-substituted mercaptolactones via photoredox-catalyzed radical addition of thiophenols
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A visible light mediated radical addition of thiophenols on 4-phenylbut-3-enoic acids to give diastereoselective synthesis of 3,4-disubstituted γ-lactones is reported. The reaction precludes the conventional prerequisite of conjugate addition. Furthermore, the lactones were successfully utilized in the synthesis of γ-ketoamides.
- Kouser, Farzana,Sharma, Vijay Kumar,Rizvi, Masood,Sultan, Shaista,Chalotra, Neha,Gupta, Vivek K.,Nandi, Utpal,Shah, Bhahwal Ali
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supporting information
p. 2161 - 2166
(2018/05/05)
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- Photochemical Homologation for the Preparation of Aliphatic Aldehydes in Flow
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Cheap and readily available aqueous formaldehyde was used as a formylating reagent in a homologation reaction with nonstabilized diazo compounds, enabled by UV photolysis of bench-stable oxadiazolines in a flow photoreactor. Various aliphatic aldehydes were synthesized along with the corresponding derivatized alcohols and benzimidazoles. No transition-metal catalyst or additive was required to affect the reaction, which proceeded at room temperature in 80 min.
- Chen, Yiding,Leonardi, Marco,Dingwall, Paul,Labes, Ricardo,Pasau, Patrick,Blakemore, David C.,Ley, Steven V.
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p. 15558 - 15568
(2019/01/04)
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- Application of an electron-transfer catalyst in light-induced aerobic oxidation of alcohols
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The first heterogeneous photocatalysis system including a bipyridinium-based complex as the electron-transfer catalyst was developed for aerobic oxidation of alcohols without the use of any noble-metal, external N-oxide or peroxide co-oxidant. The current work provides an efficient strategy for alcohol oxidation through a cost-effective, convenient and eco-friendly route.
- Guo, Rui-Yun,Sun, Li,Pan, Xin-Yi,Yang, Xiao-Dong,Ma, Shuai,Zhang, Jie
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p. 12614 - 12617
(2018/11/20)
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- Synthesis of Substrates for Aldolase-Catalysed Reactions: A Comparison of Methods for the Synthesis of Substituted Phenylacetaldehydes
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Methods for the synthesis of phenylacetaldehydes (oxidation, one-carbon chain extension) were compared by using the synthesis of 4-methoxyphenylacetaldehyde as a model example. Oxidations of 4-methoxyphenylethanol with activated DMSO (Swern oxidation) or manganese dioxide gave unsatisfactory results; whereas oxidation with 2-iodoxybenzoic acid (IBX) produced 4-methoxyphenylacetaldehyde in reasonable (75%) yield. However, Wittig-type one-carbon chain extension with methoxymethylene-triphenylphosphine followed by hydrolysis gave an excellent (81% overall) yield of 4-methoxyphenylacetaldehyde from 4-methoxybenzaldehyde (a cheap starting material). This approach was subsequently used to synthesise a set of 10 substituted phenylacetaldehydes in good to excellent yields.
- Al-Smadi, Derar,Enugala, Thilak Reddy,Norberg, Thomas,Kihlberg, Jan,Widersten, Mikael
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supporting information
p. 1187 - 1190
(2018/03/26)
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- Reductive activation of O2 by a bioinspired Fe complex for catalytic epoxidation reactions
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Aerobic epoxidation of olefins catalyzed by iron complexes without the use of a sacrificial coreductant is unknown. We report the reductive activation of O2 by a bioinspired [(bTAML)FeIII(H2O)]- (1) complex to catalyze the epoxidation of alkenes with TONs of up to 80. Spectroscopic and kinetic evidence indicates the involvement of FeV(O) as the active oxidant during the reaction.
- Singh, Kundan K.,Gupta, Sayam Sen
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supporting information
p. 5914 - 5917
(2017/07/11)
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- Biocatalytic Formal Anti-Markovnikov Hydroamination and Hydration of Aryl Alkenes
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Biocatalytic anti-Markovnikov alkene hydroamination and hydration were achieved based on two concepts involving enzyme cascades: epoxidation-isomerization-amination for hydroamination and epoxidation-isomerization-reduction for hydration. An Escherichia coli strain coexpressing styrene monooxygenase (SMO), styrene oxide isomerase (SOI), ω-transaminase (CvTA), and alanine dehydrogenase (AlaDH) catalyzed the hydroamination of 12 aryl alkenes to give the corresponding valuable terminal amines in high conversion (many ≥86%) and exclusive anti-Markovnikov selectivity (>99:1). Another E. coli strain coexpressing SMO, SOI, and phenylacetaldehyde reductase (PAR) catalyzed the hydration of 12 aryl alkenes to the corresponding useful terminal alcohols in high conversion (many ≥80%) and very high anti-Markovnikov selectivity (>99:1). Importantly, SOI was discovered for stereoselective isomerization of a chiral epoxide to a chiral aldehyde, providing some insights on enzymatic epoxide rearrangement. Harnessing this stereoselective rearrangement, highly enantioselective anti-Markovnikov hydroamination and hydration were demonstrated to convert α-methylstyrene to the corresponding (S)-amine and (S)-alcohol in 84-81% conversion with 97-92% ee, respectively. The biocatalytic anti-Markovnikov hydroamination and hydration of alkenes, utilizing cheap and nontoxic chemicals (O2, NH3, and glucose) and cells, provide an environmentally friendly, highly selective, and high-yielding synthesis of terminal amines and alcohols.
- Wu, Shuke,Liu, Ji,Li, Zhi
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p. 5225 - 5233
(2017/08/17)
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- NEW TRPA1 ANTAGONISTS
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The present invention relates to compounds of Formula (I), to the process for preparing such compounds and to their use in the treatment of a pathological condition or disease susceptible to amelioration by TRPA1 channel inhibition or antagonism.
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Page/Page column 136
(2017/08/01)
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- One-Pot Preparation of C1-Homologated Aliphatic Nitriles from Aldehydes through a Wittig Reaction under Metal-Cyanide-Free Conditions
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A one-pot protocol to obtain C1-homologated aliphatic nitriles was achieved by treating aromatic and aliphatic aldehydes with the (methoxymethyl)triphenylphosphonium ylide followed by hydrolysis of the resulting methyl vinyl ethers with pTsOH (Ts = para-toluenesulfonyl) and treatment with molecular iodine and aqueous ammonia under metal cyanide free conditions. Neopentyl-type nitriles, which could not be obtained by conventional methods that involved conversion of the neopentyl alcohol into a tosylate and treatment with metal cyanide, were successfully obtained by using the present method.
- Ezawa, Masatoshi,Togo, Hideo
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p. 2379 - 2384
(2017/05/01)
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- Synthesis of a novel six membered CNS palladacycle; TD-DFT study and catalytic activity towards microwave-assisted selective oxidation of terminal olefin to aldehyde
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This article documented synthesis of a Schiff base, E-2-(benzylthio)-N-{(2-methoxynaphthalene-1-yl)methylene}benzenamine (HL) by the treatment of 2-meyhoxynaphthaldehyde and 2-(benzylthio)aniline. Reaction of this synthesized Schiff base with Na2PdCl4has been investigated, which gave a novel six membered Pd(II) complex (PdLCl) through C,N,S-donor atom of Schiff base. These two newly synthesized compounds were characterized by1H NMR, FTIR and UV–Vis spectra and structure of the Pd(II) complex was confirmed by X-ray crystallography. The catalyst (PdLCl) displayed considerable reactivity (up to 99% selectivity and 90% yield) in the selective oxidation of terminal [Formula presented] bond in aryl substituted olefin to aldehyde. The method shows good functional groups compatibility, no ketone byproducts and is operationally simple. Time dependent density functional study (TD-DFT) of representative cyclopalladated complex has been undertaken. The simulated optical spectrum of the complex is in good agreement with the experimentally observed spectrum.
- Sarma, Kuladip,Devi, Namita,Sutradhar, Dipankar,Sarma, Bipul,Chandra, Asit K.,Barman, Pranjit
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- Maleimide-assisted anti-Markovnikov Wacker-type oxidation of vinylarenes using molecular oxygen as a terminal oxidant
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Arylacetaldehydes were successfully synthesized by the anti-Markovnikov Wacker-type oxidation of vinylarenes using 1 atm O2 as a terminal oxidant under mild conditions. Electron-deficient alkenes, such as maleic anhydride and maleimides, were effective additives and would operate as ligands to stabilize the Pd(0) species during the reaction.
- Nakaoka, Sonoe,Murakami, Yuka,Kataoka, Yasutaka,Ura, Yasuyuki
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supporting information
p. 335 - 338
(2016/01/09)
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- Synthesis and Catalytic Properties of New Metalloporphyrin-Based Porous Organic Framework Materials with Single and Accessible Sites
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It is a big challenge to homogenize heterogeneous catalysts with molecular catalytic performance. With this target in mind, herein, we describe a facile strategy for direct incorporation of single catalytic sites in 3D open porous aromatic frameworks (PAFs). The synthesis of the PAF (denoted as PAF-76) as well as its derivatives (PAF-76-M, M=Fe, Mn, Zn) was achieved by the use of tetrakis(4-bromophenyl)methane as tetrahedral nodes and tetrakis(4-bromophenyl)porphyrin as planar nodes. The connection of monomers into an extended network of PAF-76 was monitored by 13C NMR and FTIR spectroscopies. The prepared PAF-76s showed 3D porous structures with surface areas of 450–700 m2 g?1, pore volumes of 0.3–0.4 cm3 g?1, and pore sizes around 1.2 nm. The direct incorporation of metalloporphyrin components into the PAF-76-M frameworks has allowed the uniform distribution of metal ionic sites throughout the PAF-76-M particles. The combined merits of isolated metal sites and suitable pore size make PAF-76 a good candidate for heterogeneous catalysis. The catalytic performances of the porphyrin/metalloporphyrin-based active sites in the PAF-76s were evaluated by aerobic oxidation reactions of styrene, which are usually carried out with homogeneous systems. Metal-functionalized PAF-76s (PAF-76-M) exhibit enhanced turnover frequencies for styrene conversion (16.9–50.9 mol mol(M)?1 h?1) compared with molecular catalysts (0–35.0 mol mol(M)?1 h?1), and improved selectivity toward phenylacetaldehyde (85.7–99 %) in contrast to their corresponding monomers (0–75.5 %). The robustness of PAF-76 in terms of high thermal stability, good recyclability, and excellent solvent resistance showed that these PAF-76 materials hold great promise for developing heterogeneous catalysts.
- Meng, Shuang,Zou, Xiaoqin,Liu, Chuanfang,Ma, Heping,Zhao, Nian,Ren, Hao,Jia, Mingjun,Liu, Jia,Zhu, Guangshan
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p. 2393 - 2400
(2016/07/28)
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- Anti-Markovnikov Oxidation of β-Alkyl Styrenes with H2O as the Terminal Oxidant
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Oxygenation of alkenes is one of the most straightforward routes for the construction of carbonyl compounds. Wacker oxidation provides a broadly useful strategy to convert the mineral oil into higher value-added carbonyl chemicals. However, the conventional Wacker chemistry remains problematic, such as the poor activity for internal alkenes, the lack of anti-Markovnikov regioselectivity, and the high cost and chemical waste resulted from noble metal catalysts and stoichiometric oxidant. Here, we describe an unprecedented dehydrogenative oxygenation of β-alkyl styrenes and their derivatives with water under external-oxidant-free conditions by utilizing the synergistic effect of photocatalysis and proton-reduction catalysis that can address these challenges. This dual catalytic system possesses the single anti-Markovnikov selectivity due to the property of the visible-light-induced alkene radical cation intermediate.
- Zhang, Guoting,Hu, Xia,Chiang, Chien-Wei,Yi, Hong,Pei, Pengkun,Singh, Atul K.,Lei, Aiwen
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supporting information
p. 12037 - 12040
(2016/09/28)
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- Design of a novel thiophene inhibitor of 15-lipoxygenase-1 with both anti-inflammatory and neuroprotective properties
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The enzyme 15-lipoxygenase-1 (15-LOX-1) plays a dual role in diseases with an inflammatory component. On one hand 15-LOX-1 plays a role in pro-inflammatory gene expression and on the other hand it has been shown to be involved in central nervous system (CNS) disorders by its ability to mediate oxidative stress and damage of mitochondrial membranes under hypoxic conditions. In order to further explore applications in the CNS, novel 15-LOX-1 inhibitors with favorable physicochemical properties need to be developed. Here, we present Substitution Oriented Screening (SOS) in combination with Multi Component Chemistry (MCR) as an effective strategy to identify a diversely substituted small heterocyclic inhibitors for 15-LOX-1, denoted ThioLox, with physicochemical properties superior to previously identified inhibitors. Ex?vivo biological evaluation in precision-cut lung slices (PCLS) showed inhibition of pro-inflammatory gene expression and in?vitro studies on neuronal HT-22?cells showed a strong protection against glutamate toxicity for this 15-LOX-1 inhibitor. This provides a novel approach to identify novel small with favorable physicochemical properties for exploring 15-LOX-1 as a drug target in inflammatory diseases and neurodegeneration.
- Eleftheriadis, Nikolaos,Poelman, Hessel,Leus, Niek G.J.,Honrath, Birgit,Neochoritis, Constantinos G.,Dolga, Amalia,D?mling, Alexander,Dekker, Frank J.
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p. 786 - 801
(2016/08/30)
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- Efficient epoxide isomerization within a self-assembled hexameric organic capsule
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The isomerization of epoxides to the corresponding carbonyl compounds is efficiently catalyzed by the supramolecular organic nano-capsule formed by the self-assembly of six resorcin[4]arene units. The capsule provides a combination of weak Br?nsted acidity and a suitable nano-environment that favors the metal-free isomerization reaction.
- Caneva, Thomas,Sperni, Laura,Strukul, Giorgio,Scarso, Alessandro
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p. 83505 - 83509
(2016/11/01)
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- Pd-catalyzed C-N coupling of vinylbromides and sulfonimidamides: A facile synthesis of N′-vinylsulfonimidamides
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N′-Vinyl sulfonimidamides have been synthesized through a Pd-catalyzed C-N cross coupling between the N′-(imine nitrogen) of N′-deprotected sulfonimidamides and vinyl bromides. The hitherto unreported products were obtained in moderate to excellent yield, and the C-C double bond geometry of the vinylic substrates were retained during the course of reaction. Single crystal X-ray crystallographic analysis confirmed the product structure. Furthermore, we demonstrate that the formed N′-vinyl sulfonimidamides could undergo hydrogenation with Pd-C/H2 to provide N′-alkyl sulfonimidamides.
- Nandi, Ganesh C.,Kota, Sudhakar R.,Wakchaure, Prasad B.,Chinthakindi, Praveen K.,Govender, Thavendran,Kruger, Hendrick G.,Naicker, Tricia,Arvidsson, Per I.
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p. 62084 - 62090
(2015/08/03)
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- Hypoiodite-catalyzed regioselective oxidation of alkenes: An expeditious access to aldehydes in aqueous micellar media
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A highly anti-Markovnikov selective oxidation of alkenes based on in situ generated hypoiodite catalysis in aqueous micellar media under mild conditions has been described. This novel catalytic system realizes an efficient synthesis of aldehydes from alkenes in an economically viable and environmentally safe fashion. The preliminary mechanistic studies suggest that the reaction proceeds via tandem iodofunctionalization/1,2-aryl or alkyl migration. The scope and limitations of this tandem process are demonstrated with various mono- and disubstituted (terminal and internal) olefins.
- Swamy, Peraka,Reddy, Marri Mahender,Naresh, Mameda,Kumar, Macharla Arun,Srujana, Kodumuri,Durgaiah, Chevella,Narender, Nama
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p. 1125 - 1130
(2015/04/22)
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- 2-AMINOQUINOLINE-BASED COMPOUNDS FOR POTENT AND SELECTIVE NEURONAL NITRIC OXIDE SYNTHASE INHIBITION
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Various 2-aminoquinoline compounds as can be used, in vivo or in vitro, for selective inhibition of neuronal nitric oxide synthase.
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Paragraph 0082
(2015/08/04)
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- 2-aminoquinoline-based compounds for potent and selective neuronal nitric oxide synthase inhibition
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Various 2-aminoquinoline compounds as can be used, in vivo or in vitro, for selective inhibition of neuronal nitric oxide synthase.
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Page/Page column 11; 12; 38
(2016/01/09)
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- DDQ-mediated Direct C(sp3)-H Cyanation of Benzyl Ethers and 1,3-Diarylpropenes under Solvent- and Metal-free Conditions
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A direct cyanation of benzyl ethers and 1,3-diarylpropenes with TMSCN was performed under solvent- and metal-free conditions. This oxidative cross dehydrative coupling (CDC) reaction was promoted by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and provided rapid access to a broad range of nitriles in good to excellent yields.
- Kong, Shanshan,Zhang, Lingqiong,Dai, Xiaoli,Tao, Lianzhi,Xie, Chunsong,Shi, Lei,Wang, Min
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supporting information
p. 2453 - 2456
(2015/08/18)
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- Ring Expansion of Epoxides under Br?nsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ-Epoxy Esters with Imines Providing 2,4,5-Trisubstituted 1,3-Oxazolidines
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A novel ring-expansion reaction of epoxides under Br?nsted base catalysis was developed. The formal [3+2] cycloaddition reaction of β,γ-epoxy esters with imines proceeds in the presence of triazabicyclodecene (TBD) as a superior Br?nsted base catalyst to afford 2,4,5-trisubstituted 1,3-oxazolidines in a highly diastereoselective manner. This reaction involves the ring opening of the epoxides with the aid of the Br?nsted base catalyst to generate α,β-unsaturated esters having an alkoxide at the allylic position, which would formally serve as a synthetic equivalent of the 1,3-dipole, followed by a cycloaddition reaction with imines in a stepwise fashion. This methodology enables the facile synthesis of enantioenriched 1,3-oxazolidines from easily accessible enantioenriched epoxides.
- Kondoh, Azusa,Odaira, Kenta,Terada, Masahiro
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supporting information
p. 11240 - 11244
(2016/07/06)
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- Homogeneous catalytic oxidation of styrene and styrene derivatives with hydrogen peroxide in the presence of transition metal-substituted polyoxotungstates
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The tetrabutylammonium (TBA) salts of the Keggin-type polyoxotungstates with general formula [XW11M(H2O)O39](n-m)-, where X = P, B or Si and M = Mn, Fe or Co, were evaluated as catalysts in the oxidation of styrene, α-methylstyrene, p-methylstyrene, α,p-dimethylstyrene, p-chlorostyrene, p-nitrostyrene, and p-methoxystyrene under mild conditions, using aqueous H2O2 as an eco-sustainable oxidant. In this study, the influence of the catalysts and of the different styrene substituents on the oxidation reaction profile was evaluated in terms of conversion and selectivity. For all the performed catalytic studies, the main product results from the oxidative cleavage of the vinyl double bond, except in the case of the oxidation of p-methoxystyrene catalysed by BW11Mn, for which p-methoxyphenol is the main product. The catalysts BW11Mn and SiW11Co give rise to 100% conversion for almost all of the substrates, excluding p-methoxystyrene and p-nitrostyrene for both catalysts and α,p-dimethylstyrene only in the case of BW11Mn. The selectivity for C=C cleavage products resulting from the oxidative cleavage of the vinyl double bond can be as high as 98%, reaching 98% conversion for p-nitrostyrene when SiW11Co was used as a catalyst. Possible pathways are discussed and the oxidation of a few presumed intermediates was carried out. The systematic study of several substituted styrene derivatives suggests a possible reactivity order for these compounds in the catalytic system considered.
- Duarte, Tiago A. G.,Estrada, Ana C.,Simes, Mrio M. Q.,Santos, Isabel C. M. S.,Cavaleiro, Ana M. V.,Neves, M. Graca P. M. S.,Cavaleiro, Jos A. S.
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p. 351 - 363
(2015/02/18)
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- Simplified 2-aminoquinoline-based scaffold for potent and selective neuronal nitric oxide synthase inhibition
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Since high levels of nitric oxide (NO) are implicated in neurodegenerative disorders, inhibition of the neuronal isoform of nitric oxide synthase (nNOS) and reduction of NO levels are therapeutically desirable. Nonetheless, many nNOS inhibitors mimic l-arginine and are poorly bioavailable. 2-Aminoquinoline-based scaffolds were designed with the hope that they could (a) mimic aminopyridines as potent, isoform-selective arginine isosteres and (b) possess chemical properties more conducive to oral bioavailability and CNS penetration. A series of these compounds was synthesized and assayed against purified nNOS enzymes, endothelial NOS (eNOS), and inducible NOS (iNOS). Several compounds built on a 7-substituted 2-aminoquinoline core are potent and isoform-selective; X-ray crystallography indicates that aminoquinolines exert inhibitory effects by mimicking substrate interactions with the conserved active site glutamate residue. The most potent and selective compounds, 7 and 15, were tested in a Caco-2 assay and showed good permeability and low efflux, suggesting high potential for oral bioavailability.
- Cinelli, Maris A.,Li, Huiying,Chreifi, Georges,Martásek, Pavel,Roman, Linda J.,Poulos, Thomas L.,Silverman, Richard B.
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p. 1513 - 1530
(2014/03/21)
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- Expanding the scaffold for bacterial RNA polymerase inhibitors: Design, synthesis and structure-activity relationships of ureido-heterocyclic-carboxylic acids
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The emergence of bacterial resistance requires the development of new antibiotics with an alternative mode of action. Based on class I, developed in our previous study, a new series of RNA polymerase (RNAP) inhibitors targeting the switch region was desig
- Elgaher, Walid A. M.,Fruth, Martina,Groh, Matthias,Haupenthal, Joerg,Hartmann, Rolf W.
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p. 2177 - 2194
(2014/01/06)
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- Photocatalytic oxidation of organic compounds in a hybrid system composed of a molecular catalyst and visible light-absorbing semiconductor
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Photocatalytic oxidation of organic compounds proceeded efficiently in a hybrid system with ruthenium aqua complexes as catalysts, BiVO4 as a light absorber, [Co(NH3)5Cl]2+ as a sacrificial electron acceptor and
- Zhou, Xu,Li, Fei,Li, Xiaona,Li, Hua,Wang, Yong,Sun, Licheng
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supporting information
p. 475 - 479
(2015/02/19)
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- Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
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A new member of the CYP116B subfamily - P450LaMO - was discovered in Labrenzia aggregata by genomic data mining. It was successfully overexpressed in Escherichia coli, purified, and subsequently characterized spectroscopically, and its catalytic properties were assessed. Substrate profiling of the P450LaMO revealed that it was a versatile catalyst, exhibiting hydroxylation and epoxidation activities as well as O-dealkylation and asymmetric sulfoxidation activities. Diverse compounds, including alkylbenzenes, aromatic bicyclic molecules, and terpenoids, were shown to be hydroxylated by P450LaMO. Such diverse catalytic activities are uncommon for the bacterial P450s, and the P450LaMO -mediated stereoselective hydroxylation of inactivated C - H bonds - ubiquitous and relatively unreactive in organic molecules - is particularly unusual. The self-sufficient nature of P450LaMO, coupled with its broad substrate range, highlights it as an ideal template for directed evolution towards various applications.
- Yin, Yue-Cai,Yu, Hui-Lei,Luan, Zheng-Jiao,Li, Ren-Jie,Ouyang, Peng-Fei,Liu, Jing,Xu, Jian-He
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p. 2443 - 2449
(2015/03/03)
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- Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
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A new member of the CYP116B subfamily - P450LaMO - was discovered in Labrenzia aggregata by genomic data mining. It was successfully overexpressed in Escherichia coli, purified, and subsequently characterized spectroscopically, and its catalytic properties were assessed. Substrate profiling of the P450LaMO revealed that it was a versatile catalyst, exhibiting hydroxylation and epoxidation activities as well as O-dealkylation and asymmetric sulfoxidation activities. Diverse compounds, including alkylbenzenes, aromatic bicyclic molecules, and terpenoids, were shown to be hydroxylated by P450LaMO. Such diverse catalytic activities are uncommon for the bacterial P450s, and the P450LaMO -mediated stereoselective hydroxylation of inactivated C-H bonds - ubiquitous and relatively unreactive in organic molecules - is particularly unusual. The self-sufficient nature of P450LaMO, coupled with its broad substrate range, highlights it as an ideal template for directed evolution towards various applications.
- Yin, Yue-Cai,Yu, Hui-Lei,Luan, Zheng-Jiao,Li, Ren-Jie,Ouyang, Peng-Fei,Liu, Jing,Xu, Jian-He
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p. 2443 - 2449
(2015/08/24)
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- Simultaneous presence of both open metal sites and free functional organic sites in a noncentrosymmetric dynamic metal-organic framework with bimodal catalytic and sensing activities
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Assimilation of open metal sites (OMSs) and free functional organic sites (FOSs) with a framework strut has opened up a new route for the fabrication of novel metal-organic materials, thereby providing a unique opportunity to explore their multiple functionalities. A new metal-organic framework (MOF), {[Cu(ina)2(H2O)][Cu(ina)2(bipy)]·2 H2O}n (1) (ina=isonicotinate, bipy=4,4′-bipyridine), has been synthesized and characterized. Complex 1 is crystallized in the orthorhombic noncentrosymmetric space group Aba2 and consists of two different 2D coordination polymers, [Cu(ina)2(H2O)]n and [Cu(ina)2(bipy)]n, with entrapped solvent water molecules. Hydrogen-bonding interactions assemble these two different 2D coordination layers in a single-crystal structure with interdigitation of pendant 4,4′-bipy from one layer into the groove of another. Upon removal of guest molecules, 1 undergoes a structural transformation in single-crystal-to-single- crystal fashion with expansion of the effective void space. Each metal center is five-coordinated and thus can potentially behave as an OMS, and the free pyridyl groups of pendant 4,4′-bipy moieties and free -C=O groups can act as free FOSs. Thus, owing to presence of both OMSs and free FOSs, the framework exhibits multifunctional properties. Owing to the presence of OMSs, the framework can act as a Lewis acid catalyst as well as a small-molecule sensor material, and in a similar way, owing to the presence of free FOSs, it performs as a Lewis base catalyst and a cation sensor material. Furthermore, owing to noncentrosymmetry with large polarity along a particular direction, it shows strong second-harmonic generation/nonlinear optical (SHG-NLO) activity.
- Saha, Rajat,Joarder, Biplab,Roy, Anupam Singha,Manirul Islam, Sk.,Kumar, Sanjay
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supporting information
p. 16607 - 16614
(2014/01/06)
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- Removal of human ether-à-go-go related gene (hERG) K+ channel affinity through rigidity: A case of clofilium analogues
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Cardiotoxicity is a side effect that plagues modern drug design and is very often due to the off-target blockade of the human ether-à-go-go related gene (hERG) potassium channel. To better understand the structural determinants of this blockade, we design
- Louvel, Julien,Carvalho, Jo?o F.S.,Yu, Zhiyi,Soethoudt, Marjolein,Lenselink, Eelke B.,Klaasse, Elisabeth,Brussee, Johannes,Ijzerman, Adriaan P.
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supporting information
p. 9427 - 9440
(2014/01/06)
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- Glass wool catalysed regioselective isomerization of styrene oxides
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Glass wool is widely used as an insulating material. Here we report for the first time, the function of glass wool as a mild heterogeneous catalyst under vapor phase conditions - particularly for the rearrangement of styrene oxides including halogen-substituted styrene oxides to the corresponding phenyl acetaldehydes. Using this methodology, 4-isobutyl-α-methyl styrene oxide is smoothly converted to 4-isobutyl α-methyl phenyl acetaldehyde which is the precursor of the API "Ibuprofen" - an important pharmaceutical agent.
- Ramaswamy, Govindarajan K.,Somasundaram, Angalan,Kuppuswamy, Balasubramanian K.,Velayudham, Murugesan
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- A continuous flow solution to achieving efficient aerobic anti-Markovnikov Wacker oxidation
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An aerobic anti-Markovnikov Wacker oxidation for the flow-synthesis of arylacetaldehydes is reported. In the process, flow chemistry techniques have provided a means to control and minimise the over-oxidation of sensitive products. The reaction showed general applicability to various functionalised styrenes and provided a process capable of a multi-gram scale. Copyright
- Bourne,Ley
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supporting information
p. 1905 - 1910
(2013/08/23)
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- Biarylphosphonite gold(I) complexes as superior catalysts for oxidative cyclization of propynyl arenes into indan-2-ones
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Striking gold: A series of variously functionalized propynyl arenes was smoothly converted into indan-2-ones by a new gold(I)-catalyzed oxidative cyclization process. [LAu]NTf2 (Tf=trifluoromethanesulfonyl) is a superior catalyst both in terms of yield and kinetics for the present transformation. Copyright
- Henrion, Guilhem,Chavas, Thomas E. J.,Le Goff, Xavier,Gagosz, Fabien
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supporting information
p. 6277 - 6282
(2013/07/11)
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- An iron catalyzed regioselective oxidation of terminal alkenes to aldehydes
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Fe(BF4)2·6H2O with pyridine-2,6-dicarboxylic acid and PhIO can efficiently catalyze the regioselective oxidation of terminal alkene derivatives to aldehydes under mild and benign reaction conditions.
- Chowdhury, Abhishek Dutta,Ray, Ritwika,Lahiri, Goutam Kumar
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supporting information; experimental part
p. 5497 - 5499
(2012/07/01)
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- Regioselective synthesis of substituted naphthalenes and phenanthrenes by FeCl3-promoted annulation of aryl and naphthyl acetaldehydes with alkynes
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The FeCl3-promoted annulation reaction of aryl acetaldehydes with alkynes has been established, which provides a new and versatile straightforward procedure for the regioselective synthesis of mono-, di-, and polysubstituted naphthalenes under mild conditions. Interestingly, the present catalytic system not only differentiates between internal and terminal alkynes but also shows unprecedented complete Me3SiOH elimination selectivity for silyl alkyne substrates. Furthermore, the synthesis of a series of substituted phenanthrenes via reactions of nathphyl acetaldehydes with internal alkynes is also achieved for the first time in good yields with excellent regioselectivity.
- Bu, Xiuli,Hong, Longcheng,Liu, Ruiting,Hong, Jianquan,Zhang, Zhengxing,Zhou, Xigeng
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experimental part
p. 7960 - 7965
(2012/09/21)
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- Continuous-flow synthesis of monoarylated acetaldehydes using aryldiazonium salts
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Anilines and ethyl vinyl ether can be used as precursors for a process that is the synthetic equivalent of the α-arylation of acetaldehyde enolate. The reaction manifests a high level of functional group compatibility, allowing the ready preparation of a number of synthetically valuable compounds.
- Chernyak, Natalia,Buchwald, Stephen L.
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supporting information; experimental part
p. 12466 - 12469
(2012/09/05)
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