- Efficient catalytic activity of transition metal ions in Vilsmeier-Haack reactions with acetophenones
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Vilsmeier-Haack (VH) formylation reactions with acetophenones are sluggish in acetonitrile medium even at elevated temperatures. However, millimolar concentrations of transition metal ions such as Cu(II), Ni(II), Co(II), and Cd(II) were found to exhibit efficient catalytic activity in Vilsmeier-Haack Reactions with acetophenones. Reactions are accelerated remarkably in the presence of transition metal ions. The VH reactions followed second order kinetics and afforded acetyl derivatives under kinetic conditions also irrespective of the nature of oxychloride (POCl3 or SOCl2) used for the preparation of VH reagent along with DMF. On the basis of UV-vis spectroscopic studies and kinetic observations, participation of a ternary precursor [M(II) S (VHR)] in the rate-limiting step has been proposed to explain the mechanism of the metal ion-catalyzed VH reaction.
- Aneesa,Rajanna,Venkateswarlu,Reddy, K. Rajendar,Kumar, Y. Arun
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Read Online
- Asymmetric Synthesis of Functionalized 9-Methyldecalins Using a Diphenylprolinol-Silyl-Ether-Mediated Domino Michael/Aldol Reaction
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Substituted 9-methyldecalin derivatives containing an all carbon quaternary chiral center were synthesized with excellent enantioselectivity via an organocatalyst-mediated domino reaction. The first reaction is a diphenylprolinol silyl ether-mediated Michael reaction, and the second reaction is an intramolecular aldol reaction. The enantiomerically pure catalyst is involved in both reactions.
- Hayashi, Yujiro,Salazar, Hugo A.,Koshino, Seitaro
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p. 6654 - 6658
(2021/09/11)
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- Enantioselective Organocatalytic Synthesis of 1,2,3-Trisubstituted Cyclopentanes
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An organocatalytic asymmetric domino Michael/α-alkylation reaction between enals and non-stabilized alkyl halides has been developed. Chiral secondary amine catalyzed cyclization reaction of 1-bromo-3-nitropropane with α,β-unsaturated aldehydes provides 1,2,3-trisubstituted cyclopentane carbaldehydes with high diastereo- (dr up to 8 : 1) and enantioselectivities (ee up to 96 %).
- ?otolová, Martina,Kamlar, Martin,Reme?, Marek,Géant, Pierre-Yves,Císa?ová, Ivana,?tícha, Martin,Vesely, Jan
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p. 5080 - 5089
(2021/09/30)
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- Highly Regio- A nd Enantioselective Hydrogenation of Conjugated α-Substituted Dienoic Acids
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Highly regio- A nd enantioselective hydrogenation of conjugated α-substituted dienoic acids was realized for the first time using Trifer-Rh complex, providing a straightforward method for the synthesis of chiral α-substituted ?,?′-unsaturated acids. DFT calculations revealed N+H-O hydrogen bonding interaction is formed to stabilize the transition state and the coordination of 4,5-double bond to Rh(III) center would facilitate the reductive elimination process. This hydrogenation provided a gram-scale synthesis of the precursor of sacubitril.
- Liu, Xian,Liu, Song,Wang, Quanjun,Zhou, Gang,Yao, Lin,Ouyang, Qin,Jiang, Ru,Lan, Yu,Chen, Weiping
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p. 3149 - 3154
(2020/04/09)
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- Biocatalytic reduction of α,β-unsaturated carboxylic acids to allylic alcohols
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We have developed robust in vivo and in vitro biocatalytic systems that enable reduction of α,β-unsaturated carboxylic acids to allylic alcohols and their saturated analogues. These compounds are prevalent scaffolds in many industrial chemicals and pharmaceuticals. A substrate profiling study of a carboxylic acid reductase (CAR) investigating unexplored substrate space, such as benzo-fused (hetero)aromatic carboxylic acids and α,β-unsaturated carboxylic acids, revealed broad substrate tolerance and provided information on the reactivity patterns of these substrates. E. coli cells expressing a heterologous CAR were employed as a multi-step hydrogenation catalyst to convert a variety of α,β-unsaturated carboxylic acids to the corresponding saturated primary alcohols, affording up to >99percent conversion. This was supported by the broad substrate scope of E. coli endogenous alcohol dehydrogenase (ADH), as well as the unexpected CC bond reducing activity of E. coli cells. In addition, a broad range of benzofused (hetero)aromatic carboxylic acids were converted to the corresponding primary alcohols by the recombinant E. coli cells. An alternative one-pot in vitro two-enzyme system, consisting of CAR and glucose dehydrogenase (GDH), demonstrates promiscuous carbonyl reductase activity of GDH towards a wide range of unsaturated aldehydes. Hence, coupling CAR with a GDH-driven NADP(H) recycling system provides access to a variety of (hetero)aromatic primary alcohols and allylic alcohols from the parent carboxylates, in up to >99percent conversion. To demonstrate the applicability of these systems in preparative synthesis, we performed 100 mg scale biotransformations for the preparation of indole-3-aldehyde and 3-(naphthalen-1-yl)propan-1-ol using the whole-cell system, and cinnamyl alcohol using the in vitro system, affording up to 85percent isolated yield.
- Aleku, Godwin A.,Leys, David,Roberts, George W.
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p. 3927 - 3939
(2020/07/09)
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- Boosting multiple photo-assisted and temperature controlled reactions with a single redox-switchable catalyst: Solvents as internal substrates and reducing agent
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An alternative and economically viable process for the synthesis of β-aryl enals, enones and the aryl amines has been developed by partial oxidation of ethanol, isopropanol and N, N-dimethyl formamide (DMF). The formation of β-aryl enals, enones and the aryl amines was catalyzed by a mixed metal oxides layer of cobalt and chromium supported on halloysite nanotubes, designated as CoCr2O4-HNT. The C[sbnd]C and C[sbnd]N bond formation reactions were found to be influenced by temperature and the nature of base. The condensation of aldehyde with in situ generated acetaldehyde by ethanol oxidation forming β-aryl enals occurred selectively at 120 °C. The partial oxidation of isopropanol to acetone and its condensation with aldehydes forming β-aryl enones occurred at room temperature. Increase in temperature caused the liberation of hydrogen gas from isopropanol and allowed the reversible reduction of aldehydes to alcohols. Increase in temperature in isopropanol and increase in base concentration in ethanol causes the selective reduction of aldehydes to alcohols. Besides being active for the Claisen-Schmidt type of reactions and the aryl halides amination process, the synthesized catalyst was also found to be highly active for the photocatalytic oxidation of benzyl alcohols in absence of any external oxidizing agent. The positive holes (h+) generated at the Co(II) site as evident from EPR analysis was considered to be responsible for high photocatalytic activity of the material reducing the recombination rate of holes and electrons (e?). Density Functional Theory calculations were performed to understand the mechanism of ethanol oxidation to acetaldehyde.
- Bania, Kusum K.,Baruah, Manash J.,Bhattacharyya, Pradip K.,Das, Biraj,Karunakar, Galla V.,Roy, Subhasish,Saikia, Lakshi,Saikia, Pinku,Sharma, Mukesh
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p. 104 - 121
(2020/06/01)
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- Evolution of physical and photocatalytic properties of new Zn(II) and Ru(II) complexes
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Synthesis of Zn(II) and Ru(II) complexes were reported by using N4-macrocyclic Schiff base ligands under solvothermal conditions. The newly synthesized Zn(II) and Ru(II) complexes have been characterized by various physico-chemical techniques such as elemental analysis, molar conductance, HRMS, TGA, FESEM, UV–Vis, FT-IR, 1H NMR, and cyclic voltammetry. By using molar conductance studies, the complexes are formulated as [Zn(TPTTP)]Cl2 and [Ru(TPTTP)Cl2]. C–H bond activation of an sp3 group of methylstyrenes (converted into cinnamaldehydes) and C–H bond activation of the sp2 bond of polycyclic aromatic hydrocarbons through photooxidation was examined in the presence of Zn(II) and Ru(II) complexes. Reusable activity studies and photostability of catalyst are investigated by using UV–Vis spectra. Based on the results, higher catalytic activity of [Ru(TPTTP)Cl2] complex than [Zn(TPTTP)]Cl2 complex in both C–H bond activation and photooxidation of aromatic hydrocarbons has been reported.
- Gugulothu, Venkanna,Ahemed, Jakeer,Subburu, Mahesh,Yadagiri, Bhongiri,Mittal, Ritu,Prabhakar, Chetti,Pola, Someshwar
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p. 412 - 423
(2019/06/27)
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- Pd-Au-Y as Efficient Catalyst for C-C Coupling Reactions, Benzylic C-H Bond Activation, and Oxidation of Ethanol for Synthesis of Cinnamaldehydes
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Pd-Au nanoalloy supported on zeolite-Y (Pd-Au-Y) matrix was found to be an effective catalyst for C-Cl bond activation and oxidative coupling of 2-naphthol, leading to the formation of various biaryl products and 1,1′-bi-2-naphthol, BINOL. The same catalyst was also highly efficient for selective oxidation of benzylic alcohols to benzaldehydes. Cinnamaldehydes were obtained directly from benzaldehydes by aldol condensation with acetaldehyde generated in situ by partial oxidation of ethanol in the presence of Pd-Au-Y catalyst at 120 °C under basic condition. The biaryl products were also obtained directly from benzylic alcohols in a one-pot system by reacting with phenylboronic acid. The formation of biaryls from benzylic alcohols was believed to occur via one-pot benzylic C-H and C-Cl bond activation. A high % yield of biaryls, BINOL, aldehydes, and cinnamaldehydes was obtained by performing different reactions using the single Pd-Au-Y catalyst. The strong interaction of chloro-benzylic alcohol was predominantly located at active gold species. X-ray photoelectron and diffuse reflectance spectroscopic studies revealed the strong interaction between Pd and Au particles. Electrochemical studies provided proper evidence for the individual role of the nanoparticles (NPs) in one-pot synthesis of biaryls from benzylic alcohols.
- Sharma, Mukesh,Das, Biraj,Baruah, Manash J.,Biswas, Subir,Roy, Subhasish,Hazarika, Anil,Bhargava, Suresh K.,Bania, Kusum K.
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p. 5860 - 5875
(2019/06/17)
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- Palladium-Catalyzed Cascade Double C—N Bond Activation: A New Strategy for Aminomethylation of 1,3-Dienes with Aminals
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A new palladium-catalyzed selective aminomethylation of conjugated 1,3-dienes with aminals via double C—N bond activation is described. This simple method provides an effective and rapid approach for the synthesis of linear α,β-unsaturated allylic amines with perfect regioselectivity. Mechanistic studies disclosed that one palladium catalyst cleaved two distinct C—N bond to furnish a cascade double C—N bond activation, in which an allylic 1,3-diamine and allylic 1,2-diamine were initially formed as key intermediates through the palladium-catalyzed C—N bond activation of aminal and the α,β-unsaturated allylic amine was subsequently produced via palladium-catalyzed C—N bond activation of the allylic diamines.
- Qiao, Cuifang,Chen, Anrong,Gao, Bingjian,Liu, Yang,Huang, Hanmin
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supporting information
p. 929 - 933
(2018/09/22)
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- Secondary amine-catalyzed [3 + 3] benzannulation to access polysubstituted benzenes through iminium activation
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An organocatalytic [3 + 3] benzannulation to access polysubstituted benzenes from readily available α,β-unsaturated aldehydes and 1,3-bis(phenylsulfonyl)propene or 4-sulfonylcrotonates is described. The key reaction step is considered to be the iminium ac
- Jiang, Lin,Li, Hang,Zhou, Jiang-Feng,Yuan, Ming-Wei,Li, Hong-Li,Chuan, Yong-Ming,Yuan, Ming-Long
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supporting information
p. 336 - 343
(2018/02/09)
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- Lewis Acid-Mediated Ring-Opening Reactions of trans-2-Aroyl-3-styrylcyclopropane-1,1-dicarboxylates: Access to Cyclopentenes and E,E-1,3-Dienes
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The ring-opening reaction of trans-2-aroyl-3-styrylcyclopropane-1,1-dicarboxylates was investigated with different Lewis acids. With SnCl4, the cyclopropane dicarboxylates afforded cyclopentene derivatives through ring opening followed by cyclization (vinylcyclopropane-cyclopentene rearrangement). With TiCl4, they furnished E,E-1,3-diene derivatives stereoselectively via ring opening followed by proton elimination.
- Thangamani, Murugesan,Srinivasan, Kannupal
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p. 571 - 577
(2018/01/27)
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- CO2-Catalyzed oxidation of benzylic and allylic alcohols with DMSO
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CO2-catalyzed transition-metal-free oxidation of alcohols has been achieved. Earlier, several methodologies have been explored for alcohol oxidations based on transition-metal catalysts. However, owing to the cheaper price, easy separation and nontoxicity, transition-metal-free systems are in high demand to the pharmaceutical industries. For this reason, various primary and secondary alcohols have been selectively oxidized to the corresponding carbonyl compounds using CO2 as a catalyst in the presence of different functional groups such as nitrile, nitro, aldehyde, ester, halogen, ether, and so on. At the end, transition-metal-free syntheses of pharmaceuticals have also been achieved. Finally, the role of CO2 has been investigated in detail, and the mechanism is proposed on the basis of experiments and DFT calculations.
- Riemer, Daniel,Mandaviya, Bhavdip,Schilling, Waldemar,G?tz, Anne Charlotte,Kühl, Torben,Finger, Markus,Das, Shoubhik
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p. 3030 - 3034
(2018/04/14)
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- Heck arylation of allyl alcohol catalyzed by Pd(0) nanoparticles
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Pd(0) nanoparticles ca. 2 nm in diameter were obtained by the reduction of PdCl2 and Pd(OAc)2 in water at 80 °C in the presence of a PVP-stabilizing polymer. Pd(0) NPs were successfully used in the Heck coupling of allyl alcohol with iodo- and bromobenzenes. Iodobenzenes reacted under solventless conditions or in DMF solution producing 3-arylpropanals and 2-arylpropanals as the main products. The same products were obtained in the reaction of bromobenzene in TBAB as the reaction medium. The stability of Pd(0) NPs was evidenced in recycling experiments. Similar Heck coupling results were also obtained with the palladium compounds PdCl2(cod) and Pd(OAc)2 under the same conditions.
- Tarnowicz, Stanis?awa,Alsalahi, Waleed,Mieczyńska, Ewa,Trzeciak, Anna M.
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p. 5605 - 5612
(2017/08/26)
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- Expanding the substrate scope of phenylalanine ammonia-lyase from: Petroselinum crispum towards styrylalanines
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This study focuses on the expansion of the substrate scope of phenylalanine ammonia-lyase from Petroselinum crispum (PcPAL) towards the l-enantiomers of racemic styrylalanines rac-1a-d-which are less studied and synthetically challenging unnatural amino acids-by reshaping the aromatic binding pocket of the active site of PcPAL by point mutations. Ammonia elimination from l-styrylalanine (l-1a) catalyzed by non-mutated PcPAL (wt-PcPAL) took place with a 777-fold lower kcat/KM value than the deamination of the natural substrate, l-Phe. Computer modeling of the reactions catalyzed by wt-PcPAL indicated an unproductive and two major catalytically active conformations and detrimental interactions between the aromatic moiety of l-styrylalanine, l-1a, and the phenyl ring of the residue F137 in the aromatic binding region of the active site. Replacing the residue F137 by smaller hydrophobic residues resulted in a small mutant library (F137X-PcPAL, X being V, A, and G), from which F137V-PcPAL could transform l-styrylalanine with comparable activity to that of the wt-PcPAL with l-Phe. Furthermore, F137V-PcPAL showed superior catalytic efficiency in the ammonia elimination reaction of several racemic styrylalanine derivatives (rac-1a-d) providing access to d-1a-d by kinetic resolution, even though the d-enantiomers proved to be reversible inhibitors. The enhanced catalytic efficiency of F137V-PcPAL towards racemic styrylalanines rac-1a-d could be rationalized by molecular modeling, indicating the more relaxed enzyme-substrate complexes and the promotion of conformations with higher catalytic activities as the main reasons. Unfortunately, ammonia addition onto the corresponding styrylacrylates 2a-d failed with both wt-PcPAL and F137V-PcPAL. The low equilibrium constant of the ammonia addition, the poor ligand binding affinities of 2a-d, and the non-productive binding states of the unsaturated ligands 2a-d within the active sites of either wt-PcPAL or F137V-PcPAL-as indicated by molecular modeling-might be responsible for the inactivity of the PcPAL variants in the reverse reaction. Modeling predicted that the F137V mutation is beneficial for the KRs of 4-fluoro-, 4-cyano- and 4-bromostyrylalanines, but non-effective for the KR process of 4-trifluoromethylstyrylalanine.
- Bencze, László Csaba,Filip, Alina,Bánóczi, Gergely,To?a, Monica Ioana,Irimie, Florin Dan,Gellért, ákos,Poppe, László,Paizs, Csaba
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p. 3717 - 3727
(2017/07/07)
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- Highly Enantioselective Synthesis of Alkylpyridine Derivatives through a Michael/Michael/Aldol Cascade Reaction
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A method for the synthesis of pyridine derivatives based on a triple cascade reaction catalyzed by chiral secondary amines was developed. The resulting cyclohexenes (three C–C bonds were formed) were obtained in good yields with good diastereoselectivities and excellent enantioselectivities.
- Meazza, Marta,Potter, Michael,Pitak, Mateusz B.,Coles, Simon J.,Mazzanti, Andrea,Rios, Ramon
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supporting information
p. 719 - 725
(2017/02/05)
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- Enantioselective Aldol Reactions in Water by a Proline-Derived Cryptand and Fixation of CO2 by Its Exocyclic Co(II) Complex
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The secondary amine donors present in the bridges of a laterally nonsymmetric oxa-aza cryptand have been derivatized with l-proline to obtain the chiral cryptand L. The cryptand L efficiently catalyzed aldol reactions in water with up to 75% ee. On reacting with Co(II) perchlorate in the presence of KSCN, L readily formed the trinuclear complex {[Co3(L)2(NCS)6]·(15CH3CN)(5acetone)(6H2O)} (1). The complex 1 in combination with the cocatalyst tetrabutylammonium bromide (TBAB) formed an efficient catalytic system in the synthesis of cyclic carbonates from CO2 and epoxides at room temperature and atmospheric pressure.
- De, Dinesh,Bhattacharyya, Aditya,Bharadwaj, Parimal K.
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p. 11443 - 11449
(2017/09/25)
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- One-Pot l-Proline-Mediated Stereoselective α-C(sp2)–H Fluorination of α,β-Unsaturated Aldehydes through Methoxyfluorination–Elimination
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A one-pot, two-step l-proline-mediated stereoselective α-C(sp2)–H fluorination of α,β-unsaturated aldehydes towards their corresponding (Z)-α-fluoro-α,β-unsaturated aldehydes has been developed. The first step utilises Selectfluor as a fluorinating agent in CH3NO2/MeOH forming (Z)-α-fluoro-α,β-unsaturated aldehydes and their corresponding dimethyl acetals through methoxyfluorination-elimination. In the second step, water is added to promote the hydrolytic cleavage of the dimethyl acetals. The obtained (Z)-α-fluoro-α,β-unsaturated aldehydes were smoothly reduced to the corresponding alcohols by using NaBH4.
- Zhou, Jiadi,Jiang, Xinpeng,Jin, Can,Guo, Zhicheng,Su, Bin,Su, Weike
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supporting information
p. 3631 - 3634
(2017/07/22)
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- One-Pot Synthesis of (S)-Baclofen via Aldol Condensation of Acetaldehyde with Diphenylprolinol Silyl Ether Mediated Asymmetric Michael Reaction as a Key Step
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An efficient asymmetric total synthesis of (S)-baclofen was accomplished via a one-pot operation from commercially available materials using sequential reactions, such as aldol condensation of acetaldehyde, diphenylprolinol silyl ether mediated asymmetric Michael reaction of nitromethane, Kraus-Pinnick oxidation, and Raney Ni reduction. Highly enantioenriched baclofen was obtained in one pot with a good yield over four reactions.
- Hayashi, Yujiro,Sakamoto, Daisuke,Okamura, Daichi
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supporting information
p. 4 - 7
(2016/01/15)
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- Visible-Light-Induced Efficient Selective Oxidation of Nonactivated Alcohols over {001}-Faceted TiO2 with Molecular Oxygen
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In the presence of molecular oxygen, a {001}-faceted nanocrystalline anatase TiO2 catalyst enabled the selective oxidation of nonactivated aliphatic alcohols to the corresponding aldehydes or ketones under visible light. The reaction shows excellent conversion and selectivity towards the formation of the carbonyl products without over-oxidation to the corresponding carboxylic acids. The exceptional reactivity of the catalyst is possibly due to the absorption of visible light originating from a stronger interaction of alcohol with the {001} facet, which facilitates the modification of the band structure of TiO2, thus facilitating the photogenerated hole transfer and subsequent oxidation processes. The experimental results have also been corroborated by first-principles quantum chemical DFT calculations.
- Vadakkekara, Raji,Biswas, Abul Kalam,Sahoo, Tapan,Pal, Provas,Ganguly, Bishwajit,Ghosh, Subhash Chandra,Panda, Asit Baran
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supporting information
p. 3084 - 3089
(2016/11/13)
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- Bi (NO3)3·5H2O and cellulose mediated Cu-NPs - A highly efficient and novel catalytic system for aerobic oxidation of alcohols to carbonyls and synthesis of DFF from HMF
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A highly efficient and versatile catalytic system for oxidation of primary and secondary aromatic alcohols to carbonyls has been developed. High efficiency, general synthetic applicability, broader functional group tolerance and versatility towards oxidation of both primary and secondary aromatic alcohols are the key features of this green and sustainable protocol. Selective oxidation of 5-hydroxymethyl furfural (HMF) to biofuel 2,5-diformylfuran (DFF) has been observed in excellent yields. Use of sustainable bio-polymer cellulose as a Cu-nanoparticle support makes the catalytic system environmentally benign.
- Baruah, Diganta,Hussain, Farhaz L.,Suri, Mrinaly,Saikia, Ujwal Pratim,Sengupta, Pinaki,Dutta, Dipak Kumar,Konwar, Dilip
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- Fullerene pyrrolidine derivative and preparation method thereof
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The invention belongs to the technical field of chemical synthesis, particularly relates to a N-methyl-2-(4-nitrobenzene vinyl)-3,4-fullerene pyrrolidine derivative, and further discloses a preparation method of the fullerene pyrrolidine derivative. The method for preparing N-methyl-2-(4-nitrobenzene vinyl)-3,4-fullerene pyrrolidine comprises the steps that the existing 1,3-dipolar-cycloaddition reaction is utilized, methylbenzene is used as a solvent for a reaction, and the target product N-methyl-2-(4-nitrobenzene vinyl)-3,4-fullerene pyrrolidine is obtained. It is surprised to find that after the whole reaction system is cooled to indoor temperature, an organic solvent comprising trichloromethane, carbon disulfide and orthodichlorobenzene is added, the reaction continues to be carried out to the end, the synthetic yield of the product is far higher than that of the product obtained through the solvent only comprising methylbenzene, and the unexpected technical effect is obtained.
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Paragraph 0042-0044
(2017/03/25)
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- Highly regio- And enantioselective synthesis of g,d-unsaturated amido esters by catalytic hydrogenation of conjugated enamides
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An efficient and highly regio- and enantioselective catalytic asymmetric hydrogenation of a,γ-dienamido esters to g,d-unsaturated amido esters has been achieved using Rh/ TangPhos as the catalyst. A series of γ,δ-unsaturated amido acids were furnished in excellent yields with up to 99%ee. This effective methodology was applied in the asymmetric synthesis of key intermediate of Ramipril, an ACE inhibitor.
- Min, Gao,Jing-jing, Meng,Hui, Lv,Xumu, Zhang
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supporting information
p. 1885 - 1887
(2015/02/19)
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- Proline-catalyzed asymmetric Diels-Alder reactions of an o-quinodimethane
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Catalytic asymmetric Diels-Alder reaction of α-amino-o-quinodimethane with α,β-unsaturated aldehydes was achieved with high diastereo- and enantioselectivities in the presence of l-proline, which acts as a promoter to generate the quinodimethane from the corresponding precursor as well as a chiral catalyst for the enantioselective Diels-Alder reaction.
- Shirakawa, Hidenori,Sano, Hiroshi
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p. 4095 - 4097
(2014/07/22)
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- Combined heterogeneous metal/chiral amine: Multiple relay catalysis for versatile eco-friendly synthesis
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Herein is described a versatile and broad synergistic strategy for expansion of chemical space and the synthesis of valuable molecules (e.g. carbocycles and heterocycles), with up to three quaternary stereocenters, in a highly enantioselective fashion from simple alcohols (31 examples, 95:5 to >99.5:0.5 e.r.) using integrated heterogeneous metal/chiral amine multiple relay catalysis and air/O2 as the terminal oxidant. A novel highly 1,4-selective heterogeneous metal/amine co-catalyzed hydrogenation of enals was also added to the relay catalysis sequences. Relay switch: A versatile strategy for expansion of chemical space and the synthesis of valuable molecules, having up to three quaternary stereocenters, in a highly enantioselective fashion from simple alcohols is described. The method employs integrated heterogeneous metal/chiral amine multiple relay catalysis and air/O2 as the terminal oxidant.
- Deiana, Luca,Jiang, Yan,Palo-Nieto, Carlos,Afewerki, Samson,Incerti-Pradillos, Celia A.,Verho, Oscar,Tai, Cheuk-Wai,Johnston, Eric V.,C?rdova, Armando
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supporting information
p. 3447 - 3451
(2014/04/03)
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- Novel unsymmetrical leuco-TAM, (2E, 2′E)-2,2′-{(E)-4- phenylpent-2-ene-1,5-diylidene}bis(1,3,3-trimethylindoline) derivatives: Synthesis and structure elucidation
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Novel unsymmetrical leuco-TAM, (2E, 2′E)-2,2′-{(E)-4- phenylpent-2-ene-1,5-diylidene}bis(1,3,3-trimethylindoline) derivatives were synthesized from a reaction of commercially available 2-methylene-1,3,3- trimethylindoline (FB) and substituted cinnamaldehyde derivatives. The chemical structures of the resulting molecules were determined using 1D and 2D NMR spectroscopy experiments, including COSY, HMBC and NOESY. The compounds had the EEE configuration and were potent precursors for Cy5 TAM+ dyes. This is different from the Malachite green FB-analogs, which generally have a ZE configuration and are precursors to Cy3 TAM+ dyes. The formation of unsymmetrical LTAM molecules as the sole product suggests that the Michael-type addition of a FB molecule occurs on the δ-carbon of the α, β, γ, δ-unsaturated imminium salts, which were formed as an intermediate at the first step.
- Keum, Sam-Rok,Lee, Min-Hyung,Ma, So-Young,Kim, Do-Kyung,Roh, Se-Jung
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experimental part
p. 233 - 238
(2011/12/21)
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- Oxidative and enantioselective cross-coupling of aldehydes and nitromethane catalyzed by diphenylprolinol silyl ether
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Synthetically important β-substituted γ-nitro aldehydes have been synthesized with excellent enantioselectivity by the cross-coupling reaction of β-aryl substituted aldehydes or Y γ-unsaturated aldehydes and nitromethane using 2,3-dichloro-5,6-dicyanoquinone (DDQ) and diphenylprolinol silyl ether as an oxidant and catalyst, respectively (see scheme; TMS=trimethylsilyl).
- Hayashi, Yujiro,Itoh, Takahiko,Ishikawa, Hayato
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supporting information; experimental part
p. 3920 - 3924
(2011/05/15)
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- Towards greener solvents for the bleach oxidation of alcohols catalysed by stable N-oxy radicals
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We conducted a solvent screening study aimed at identifying greener alternatives for the commonly used solvent dichloromethane in N-oxy catalysed bleach oxidations of various alcohol substrates. We found that environmentally acceptable ester solvents, notably isopropyl acetate and methyl acetate, gave results comparable to or better than dichloromethane. However, there was no apparent correlation between common solvent properties and performance. A comparison of two co-catalysts, NaBr and borax, revealed that borax gave better results with cinnamyl alcohols whereas NaBr was generally better with the other alcohols. We also studied the effect of catalyst loading. In the oxidation of 3-phenyl-1-propanol the amount of N-oxy catalyst could be effectively reduced to a mere 0.1 mol%. Overall, we conclude that due to the complex nature of these systems, there is not a single set of conditions that gives good results for all alcohols. However, by employing a simple screening approach to assess solvent, catalyst and co-catalyst combinations, similar or even better results can often be achieved in solvents other than dichloromethane. The Royal Society of Chemistry.
- Janssen, Michiel H. A.,Chesa Castellana, Juan F.,Jackman, Hayley,Dunn, Peter J.,Sheldon, Roger A.
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experimental part
p. 905 - 912
(2011/06/20)
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- Pd-catalyzed cascade Heck-Saegusa: Direct synthesis of enals from aryl iodides and allyl alcohol
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A new efficient Pd-catalyzed cascade Heck-Saegusa protocol for the synthesis of synthetically useful α,β-unsaturated aldehydes in high yields from readily available aryl iodides and allyl alcohol has been developed.
- Liu, Jie,Zhu, Jin,Jiang, Hualiang,Wang, Wei,Li, Jian
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supporting information; experimental part
p. 415 - 417
(2010/04/04)
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- Palladium-catalyzed oxidative tandem reaction of allylamines with aryl halides leading to α,β-unsaturated aldehydes
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A novel tandem protocol involving a Heck reaction process for the synthesis of α,β-unsaturated aldehydes has been developed. In the presence of Pd(OAc), PPh3, NaOAc, TBAB and air, N-allylbenzenamines underwent the reaction with various aryl hal
- Jiang, Tao-Shan,Li, Jin-Heng
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supporting information; experimental part
p. 7236 - 7238
(2010/03/25)
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- Direct oxidation of β-aryl substituted aldehydes to α,β-unsaturated aldehydes promoted by an o-anisidine-Pd(OAc) 2 Co-catalyst
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An o-anisidine-Pd(OAc)2 catalytic system for the direct co-catalytic Saegusa oxidation of β-aryl substituted aldehydes to α,β-unsaturated aldehydes has been developed. The use of o-anisidine in place of (S)-diphenylprolinol made the process more simply and cost-effective. The process not only features the use of unmodified aldehydes rather than enol silyl ethers, but also gives moderate to good yields (44-72%).
- Liu, Jie,Zhu, Jin,Jiang, Hualiang,Wang, Wei,Li, Jian
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experimental part
p. 1712 - 1716
(2010/04/30)
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- A direct amine-palladium acetate cocatalyzed saegusa oxidation reaction of unmodified aldehydes to α,β-unsaturated aldehydes
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A direct preparation of synthetically useful α,β-unsaturated aldehydes from readily available aldehydes has been developed. The process is effectively cocatalyzed by an amine-palladium acetate to give rise to α,β-unsaturated aldehydes in moderate to good yields (41-62%). The reaction features the use of unmodified aldehydes rather than enol silyl ethers, which are used in a typical Saegusa oxidation reaction.
- Zhu, Jin,Liu, Jie,Ma, Ruoqun,Xie, Hexin,Li, Jian,Jiang, Hualiang,Wang, Wei
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supporting information; experimental part
p. 1229 - 1232
(2009/12/07)
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- A simple and efficient oxidation of alcohols with ruthenium on carbon
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A simple, efficient, and environmentally-friendly heterogeneous Ru/C-catalyzed oxidation of secondary and primary alcohols without additives under an atmosphere of oxygen has been established. The Royal Society of Chemistry 2009.
- Mori, Shigeki,Takubo, Masato,Makida, Kazuya,Yanase, Takayoshi,Aoyagi, Satoka,Maegawa, Tomohiro,Monguchi, Yasunari,Sajiki, Hironao
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supporting information; experimental part
p. 5159 - 5161
(2009/12/08)
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- Acrolein diethyl acetal: A three-carbon homologating reagent for the synthesis of β-arylpropanoates and cinnamaldehydes by heck reaction catalyzed by a Kaiser oxime resin derived palladacycle
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A polymer palladacycle derived from Kaiser oxime resin was used as a source of palladium(0) in the chemoselective Heck reaction of acrolein diethyl acetal with aryl halides under ligand-free conditions. The use of typical Heck conditions afforded 3-arylpropionic esters, and the process can be directed to the synthesis of cinnamaldehydes under Cacchi conditions. These processes take place with rather low loading of the catalyst, which can be recovered by simple filtration and reused for at least five runs without competitive dehalogenation. This is the first time that a supported palladium complex has been reused under Cacchi conditions. ICP-OES analyses of the Pd content of the crude products in both transformations indicated lower leaching for the esters than for the aldehydes in the range up to 0.08 ppm for the esters and 0.8 ppm for the aldehydes. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Alacid, Emilio,Najera, Carmen
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experimental part
p. 3102 - 3106
(2009/04/11)
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- [Ce(NO3)3]3-H2IO6: Efficient oxidation reactions under solvent-free conditions
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Efficient solvent-free oxidation of alcohols, deprotection and oxidative deprotection of trimethylsilyl ethers and oxidative deprotection of oximes using tris [trinitratocerium (IV)] paraperiodate (TTCPP) is reported.
- Shirini,Esm-Hosseini,Hejazi,Mohammadpoor-Baltork
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- N-hydroxyformamidine derivatives
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An N-hydroxyformamidine derivative of the following formula or a pharmaceutically acceptable salt thereof: (wherein R1 represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group or a halogen atom, A represents a C1-10 alkylene group or a group of the following formula: (wherein m, n and p each represent an integer of 0 to 4), and R represents an N,N-di-C1-6 alkylamino group, a dioxanyl group, a C1-4 alkyl-substituted dioxanyl group, a C1-4 alkoxy-C1-4 alkoxy group or a group of the following formula: (wherein s and t each represent an integer of 1 to 4, B represents a methylene group, an oxygen atom, a sulfur atom, a nitrogen atom, a C1-4 alkyl-substituted nitrogen atom, a phenyl-substituted nitrogen atom or a benzyl-substituted nitrogen atom, R2 represents a hydrogen atom or a C1-4 alkyl group, and r represents an integer of 0 to 2)). The present invention aims to provide an agent for inhibiting 20-HETE-producing enzymes, 20-HETE being involved in the effects of causing microvascular constriction or dilation in major organs (e.g., kidneys, cerebral blood vessels) or of inducing cell proliferation, etc.
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Page/Page column 7
(2010/02/15)
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- Solid state cleavage of oximes with potassium permanganate supported on alumina
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A manipulatively simple and rapid method for conversion of oximes to the corresponding carbonyl compounds is described. The reaction is conducted under solvent-less conditions using alumina-supported permanganate. According to the reaction system and conditions used, different ketones and aldehydes are obtained in moderate and good yields.
- Imanzadeh,Hajipour,Mallakpour
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p. 735 - 740
(2007/10/03)
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- Highly selective oxidation of allylic alcohols catalysed by monodispersed 8-shell Pd nanoclusters in the presence of molecular oxygen
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Treatment of Pd4phen2(CO)2(OAc)4 with metal nitrates such as Cu(NO3)2 produced monodispersed Pd nanoclusters with a mean diameter and standard deviation (d±σ) of 38±2.1 A (σ/d = 6%). The Pd nanoclusters act as heterogeneous catalysts for the selective oxidation of primary aromatic allylic alcohols using molecular oxygen as an oxidant. This unique catalysis can be ascribed to multiple interactions between the alcohol and specific ensemble sites consisting of Pd0, Pd+, and Pd2+ on the cluster surface.
- Choi, Kwang-Min,Akita, Tomoki,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 324 - 328
(2007/10/03)
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- Organic reactions under solid-state conditions
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Manipulatively simple and rapid methods are described for the synthesis of: chiral sulfinate esters from sulfonyl chlorides and sufonic acids; aldehydes and ketones from oximes, alcohols, hydrozones; sulfoxides from sulfides; and disulfides from thiols. The chemical yields are good to excellent and diastereoselectivity is high.
- Hajipour,Mallakpour
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p. 371 - 387
(2007/10/03)
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- Benzyltriphenylphosphonium peroxymonosulfate: As a novel and efficient reagent for oxidation of alcohols under solvent-free conditions
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This paper describes the oxidation of alcohols under solvent-free conditions using benzyltriphenylphosphonium peroxymonosulfate, which has been prepared by mixing an aqueous solution of benzyltriphenylphosphonium chloride with oxone at room temperature. This reagent is stable white powder, which may be stored for months without loss of its activity. This compound is readily soluble in organic solvents such as acetonitrile, chloroform, and dichloromethane and slightly soluble in carbon tetrachloride, ether, and hexane.
- Hajipour, Abdol Reza,Mallakpour, Shadpour E.,Adibi, Hadi
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p. 460 - 461
(2007/10/03)
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- Oxidation of alcohols with benzyltriphenylphosphonium peroxymonosulfate under non-aqueous conditions
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Oxidation of allylic and benzylic alcohols with benzyltriphenylphosphonium peroxymonosulfate (PhCH2Ph3P+HSO5-) 1 (BTPPMS) in refluxing acetonitrile is reported. The oxidation in the presence of a catalytic amount of bismuth chloride enhances the rate.
- Hajipour,Mallakpour,Adibi
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- Solid-phase oxidation of organic compounds with benzyltriphenylphosphonium dichromate
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Benzyltriphenylphosphonium dichromate could be used for oxidation of organic compounds such as alcohols, thiols and sulfides to the corresponding carbonyl, disulfide and sulfoxide derivatives under solid-phase conditions. This reagent is very easily prepared from an aqueous solution of benzyltriphenylphosphonium chloride with CrO3 in 3 N HCl at room temperature. The reagent, is a stable orange powder, which may be stored for month without loss of its activity.
- Hajipour,Mohammadpoor-Baltork, Iraj
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p. 145 - 151
(2007/10/03)
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- Benzyltriphenylphosphonium chlorochromate: A mild and novel reagent for oxidation of benzylic and allylic alcohols under non-aqueous and aprotic conditions or microwave conditions
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This paper describes the oxidation of benzylic and allylic alcohols under non-aqueous and aprotic conditions or microwave conditions using benzyltriphenylphosphonium chlorochromate (1) PhCH2PPh3CrO3.HCl which has been prepared by mixing an aqueous solution of benzyltriphenylphosphonium chloride with CrO3 in 6 N HCl at room temperature. This reagent is stable orange powder which may be stored for months without loss of its activity. This compound is readily soluble in organic solvents such as acetonitrile, chloroform and dichloromethane and slightly soluble in carbon tetrachloride, ether and hexane, the oxidation under microwave conditions is much more faster.
- Hajipour,Mallakpour,Backnejad
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p. 3855 - 3864
(2007/10/03)
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- Oxidation of alcohols to carbonyl compounds under solvent-free conditions using permanganate supported on alumina
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A manupulatively simple and rapid method for oxidation of alcohols to the corresponding carbonyl compounds is described. The reaction is conduced under solventless 'dry' conditions using alumina-supported permanganate.
- Hajipour, Abdol Reza,Mallakpour, Shadpour E.,Imanzadeh, Gholamhasan
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- Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) peroxodisulfate: A mild and efficient oxidant for cleavage of nitrogen double bonds and oxidation of alcohols under anhydrous conditions
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Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) peroxodisulfate (1), is readily prepared as an orange solid from commercially available 1,4- diazabicyclo[2.2.2]octane and potassium peroxodisulfate. This reagent easily converts hydrazones, semicarbazones, oximes, and alcohols to the corresponding carbonyl compounds with excellent yields.
- Hajipour, Abdol Reza,Baltork, Iraj Mohammadpoor,Kianfar, Godaraz
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p. 2655 - 2659
(2007/10/03)
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- An efficient C2-homologation of aromatic aldehydes via 5-hydroxyisoxazolidines
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The reaction of lithium enolate of acetaldehyde (generated by the known cycloreversion of THF in the presence of n-BuLi) with a number of aryl N-phenylnitrones affords 2-phenyl-3-aryl-5-hydroxyisoxazolidines (trans + cis) in high yields. A low conversion or no reaction at all were instead observed with some N-alkylnitrones (methyl and t-butyl, respectively). Base (or acid) induced decomposition of 5-hydroxyisoxazolidines allows cinnamaldehydes to be obtained in high yields. Thus the combination of the synthesis and decomposition of 5-hydroxyisoxazolidines provides a new efficient way for the C2-homologation of aromatic aldehydes.
- Di Nunno,Scilimati
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p. 4121 - 4132
(2007/10/02)
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- PREPARATION OF CONJUGATED AROMATIC POLYENALS BY WITTIG OXOPROPENYLATION
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Heteroaromatic, or aromatic polyenals containing either electron-donating or withdrawing substituents can now be prepared easily in excellent yield by Wittig oxopropenylation with 1,3-dioxan-2-ylmethyltributyl phosphorane
- Spangler, Charles W.,McCoy, Ray K.
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- ISOMERS OF 3-(4-NITROPHENYL)ACROLEIN OXIME
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The Z and E isomers of 3-(4-nitrophenyl)acrolein oxime were obtained and characterized.The assignment was made on the basis of the geminal hetero constants 2J(15N = C-1N) and 2J(15N = C-13C).
- Leitis, L.Ya.,Liepin'sh, E.E.,Yansone, D.P.,Dreibante, I.I.,Shimanskaya, M.V.,et al.
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