- Mechanism of Pd(OAc)2/DMSO-catalyzed aerobic alcohol oxidation: Mass-transfer-limitation effects and catalyst decomposition pathways
-
Pd(OAc)2 in DMSO is an effective catalyst for the aerobic oxidation of alcohols and numerous other organic substrates. Kinetic studies of the catalytic oxidation of primary and secondary benzylic alcohol substrates provide fundamental insights into the catalytic mechanism. In contrast to the conclusion reached in our earlier study (J. Am. Chem. Soc. 2002, 124, 766-767), we find that Pd(II)-mediated alcohol oxidation is the turnover-limiting step of the catalytic reaction. At elevated catalyst loading, however, the rate of catalytic turnover is limited by the dissolution of oxygen gas into solution. This mass-transfer rate is measured directly by using gas-uptake methods, and it correlates with the maximum rate observed during catalysis. Initial-rate studies were complemented by kinetic analysis of the full-reaction timecourses at different catalyst concentrations. Kinetic fits of these traces reveal the presence of unimolecular and bimolecular catalyst decomposition pathways that compete with productive catalytic turnover.
- Steinhoff, Bradley A.,Stahl, Shannon S.
-
-
Read Online
- Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids
-
Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal-organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.
- Tiburcio, Estefanía,Greco, Rossella,Mon, Marta,Ballesteros-Soberanas, Jordi,Ferrando-Soria, Jesús,López-Haro, Miguel,Hernández-Garrido, Juan Carlos,Oliver-Meseguer, Judit,Marini, Carlo,Boronat, Mercedes,Armentano, Donatella,Leyva-Pérez, Antonio,Pardo, Emilio
-
p. 2581 - 2592
(2021/02/16)
-
- Preparation method of 2,5-dimethoxyphenylacetic acid
-
The invention belongs to the technical field of drug synthesis, and particularly relates to a preparation method of 2,5-dimethoxyphenylacetic acid, wherein the method comprises the following steps: A,reacting 1,4-dimethoxybenzene in a formylation system to obtain 2,5-dimethoxybenzaldehyde; B, reacting the 2,5-dimethoxybenzaldehyde obtained in the step A with a reducing agent, extracting a reaction system, then combining organic phases, drying, concentrating under reduced pressure and distilling a crude product to obtain 2,5-dimethoxybenzyl alcohol; C, reacting the 2,5-dimethoxybenzyl alcoholobtained in the step B with a bromination reagent to obtain 2-bromomethyl-1,4-dimethoxybenzene; and D, reacting the 2-bromomethyl-1,4-dimethoxybenzene obtained in the step C with magnesium or butyl lithium and carbon dioxide in a solvent to obtain the 2,5-dimethoxyphenylacetic acid. The yield and the total yield of the 2,5-dimethoxyphenylacetic acid obtained by the method disclosed by the invention are both higher than those of 2,5-dimethoxyphenylacetic acid synthesized by a Willegerdt-Kindler method.
- -
-
Paragraph 0024-0026; 0032-0034; 0040-0042; 0047-0049; 0055
(2021/02/06)
-
- Mechanistic insight into concerted proton-electron transfer of a Ru(IV)-oxo complex: A possible oxidative asynchronicity
-
We have thoroughly investigated the oxidation of benzyl alcohol (BA) derivatives by a RuIV(O) complex (RuIV(O)) in the absence or presence of Br?nsted acids in order to elucidate the proton-coupled electron-transfer (PCET) mechanisms in C-H oxidation on the basis of a kinetic analysis. Oxidation of BA derivatives by RuIV(O) without acids proceeded through concerted proton-electron transfer (CPET) with a large kinetic isotope effect (KIE). In contrast, the oxidation of 3,4,5-trimethoxy- BA ((MeO)3-BA) by RuIV(O) was accelerated by the addition of acids, in which the KIE value reached 1.1 with TFA (550 mM), indicating an alteration of the PCET mechanism from CPET to stepwise electron transfer (ET) followed by proton transfer (PT). Although the oxidized products of BA derivatives were confirmed to be the corresponding benzaldehydes in the range of acid concentrations (0-550 mM), a one-electron-reduction potential of RuIV(O) was positively shifted with increases in the concentrations of acids. The elevated reduction potential of RuIV(O) strongly influenced the PCET mechanisms in the oxidation of (MeO)3-BA, changing the mechanism from CPET to ET/PT, as evidenced by the driving-force dependence of logarithms of reaction rate constants in light of the Marcus theory of ET. In addition, dependence of activation parameters on acid concentrations suggested that an oxidative asynchronous CPET, which is not an admixture of the CPET and ET/PT mechanisms, is probably operative in the boundary region (0 mM [TFA] 50 mM) involving a one-protoninteracted RuIV(O) H+ as a dominant reactive species.
- Kojima, Takahiko,Kotani, Hiroaki,Shimomura, Hinatsu,Ikeda, Kei,Ishizuka, Tomoya,Shiota, Yoshihito,Yoshizawa, Kazunari
-
p. 16982 - 16989
(2020/11/09)
-
- Chemoselective Cross-Coupling between Two Different and Unactivated C(aryl)-O Bonds Enabled by Chromium Catalysis
-
We report here the first example of cross-coupling between two different and unactivated C(aryl)-O bonds with chromium catalysis. The combination of a low-cost Cr(II) salt, 4,4′-di-tert-butyl-2,2′-dipyridyl (dtbpy) as the ligand, and magnesium as the reductant shows high reactivity in promoting the reductive cross-coupling of aryl methyl ether derivatives with aryl esters by cleavage and coupling of two different C(aryl)-O bonds under mild conditions. The formation of active low-valent Cr species by reduction of CrCl2 with Mg can be considered, which prefers to initially activate the C(aryl)-O bond of phenyl methyl ether with the chelation help of dtbpy and an o-imine auxiliary. The subsequent consecutive reduction, second C(aryl)-O activation, and reductive elimination allow for the achievement of selective cross-coupling of C(aryl)-O/C(aryl)-O bonds.
- Tang, Jinghua,Liu, Liu Leo,Yang, Shangru,Cong, Xuefeng,Luo, Meiming,Zeng, Xiaoming
-
supporting information
p. 7715 - 7720
(2020/05/20)
-
- SUBSTITUTED CHROMEN-4-ONE FOR THE TREATMENT AND PROPHYLAXIS OF HEPATITIS B VIRUS INFECTION
-
The present invention provides novel compounds having the general formula: (I) wherein R1 to R10, Gi, G2 and m are as described herein, compositions including the impounds and methods of using the compounds for the treatment of hepatitis B.
- -
-
Page/Page column 26
(2020/07/31)
-
- Regioselective synthesis of gentisyl alcohol-type marine natural products
-
Gentisyl alcohol-type natural products, possessing various important biological properties, have been synthesized from 4-methoxyphenol by using a selective phenol monohydroxymethylation/monochlorination, a CAN oxidation and a sodium dithionite reduction as the key steps. The natural product synthesis is efficient, atom- and step-economical, and requires no protecting groups.
- Wang, Hong-Shuang,Li, Hui-Jing,Wang, Long-Fei,Shen, Zhi-Lun,Wu, Yan-Chao
-
supporting information
p. 1891 - 1896
(2018/05/29)
-
- Preparation method of 2,5-dihydroxybenzaldehyde
-
The invention provides a method for synthesizing 2,5-dihydroxybenzaldehyde. The method comprises the following steps: with p-dimethoxybenzene as a raw material, carrying out bromination reaction, Grignard reaction and demethylation reaction to obtain the 2,5-dihydroxybenzaldehyde. The preparation conditions are mild, the process is simple, and the industrial application value is high.
- -
-
-
- Synthesis of Novel Diaziridinyl Quinone Isoxazole Hybrids and Evaluation of Their Anti-Cancer Activity as Potential Tubulin-Targeting Agents
-
Two series of diaziridinyl quinone isoxazole derivatives were prepared and evaluated for their cytotoxic activity against MCF7, HeLa, BT549, A549 and HEK293 cell lines and interaction with tubulin. Compounds (6a-m) showed promising activity against all the 5 human cancer cell lines. Compounds 6a, 6e and 6 m were potent [IC 50 ranging between 2.21 μg to 2.87 μg] on ER-positive MCF7 cell line similar to the commercially available drug molecule Doxorubicin. The results from docking models are in consistent with the experimental values which demonstrated the favourable binding modes of compounds 6a-m to the interface of α- and β-tubulin dimer.
- Kumar, P. Ravi,Yennam, Satyanarayana,Raghavulu,Velatooru, Loka Reddy,Kotla, Siva Reddy,Penugurti, Vasudevarao,Hota, Prasanta K.,Behera, Manoranjan,Jaya Shree
-
p. 406 - 414
(2019/07/10)
-
- A transition metal free expedient approach for the C[dbnd]C bond cleavage of arylidene Meldrum's acid and malononitrile derivatives
-
A transition metal free expedient approach for the C[dbnd]C bond cleavage of electron deficient alkenes such as arylidene Meldrum's acid and malononitrile derivatives are discussed. The C[dbnd]C bond of these compound were cleaved to benzoic acid in good yield at high temperature. Most importantly, with oxone in CH3CN/H2O at 45 °C or m-CPBA in DCM or NaClO2 in THF/H2O or PIDA in THF at room temperature furnished benzaldehyde derivatives selectively in excellent yields.
- Suresh, Muthiah,Kumari, Anusueya,Singh, Raj Bahadur
-
-
- Production of (S)-β-Nitro Alcohols by Enantioselective C?C Bond Cleavage with an R-Selective Hydroxynitrile Lyase
-
Hydroxynitrile lyase (HNL)-catalysed stereoselective synthesis of β-nitro alcohols from aldehydes and nitroalkanes is considered an efficient biocatalytic approach. However, only one S-selective HNL—Hevea brasiliensis (HbHNL)—exists that is appropriate for the synthesis of (S)-β-nitro alcohols from the corresponding aldehydes. Further, synthesis catalysed by HbHNL is limited by low specific activity and moderate yields. We have prepared a number of (S)-β-nitro alcohols, by kinetic resolution with the aid of an R-selective HNL from Arabidopsis thaliana (AtHNL). Optimization of the reaction conditions for AtHNL-catalysed stereoselective C?C bond cleavage of racemic 2-nitro-1-phenylethanol (NPE) produced (S)-NPE (together with benzaldehyde and nitromethane, largely from the R enantiomer) in up to 99 % ee and with 47 % conversion. This is the fastest HNL-catalysed route known so far for the synthesis of a series of (S)-β-nitro alcohols. This approach widens the application of AtHNL for the synthesis not only of (R)- but also of (S)-β-nitro alcohols from the appropriate substrates. Without the need for the discovery of a new enzyme, but rather by use of a retro-Henry approach, it was used to generate a number of (S)-β-nitro alcohols by taking advantage of the substrate selectivity of AtHNL.
- Rao, D. H. Sreenivasa,Padhi, Santosh Kumar
-
p. 371 - 378
(2019/01/08)
-
- Sulfuric Acid-Promoted Oxidation of Benzylic Alcohols to Aromatic Aldehydes in Dimethyl Sulfoxide: An Efficient Metal-Free Oxidation Approach
-
An efficient metal-free oxidation of benzylic alcohols to Aaromatic aldehydes is described. Heating a solution of the benzylic alcohol in DMSO in the presence of H 2 SO 4 afforded the corresponding aldehyde in excellent yield. This oxidation reaction, which proceeds with a short reaction time and no side products, is akin to the Pfitzner-Moffatt oxidation, but without the need for N, N ′-dicyclohexylcarbodiimide.
- Sheikhi, Ehsan,Adib, Mehdi,Karajabad, Morteza Akherati,Gohari, Seyed Jamal Addin
-
p. 974 - 978
(2018/04/23)
-
- Design, synthesis and evaluation of curcumin-based fluorescent probes to detect Aβ fibrils
-
Amyloid β fibrillation is an early event in Alzheimer's disease, so its detection is important to understand its roles in Alzheimer's disease. Curcumin, which has poor water solubility, has been reported to have many pharmacological activities including potent anti-amyloid β fibril activity in Alzheimer's disease. In this study, we found that curcumin analogues with the fluorescence property instead of non-inhibition of amyloid β fibrils. The development of new curcumin analogue, Me-CUR (9), as fluorescent switchable probe to detect amyloid β fibrils is described. Me-CUR (9) shows excellent fluorescence, especially higher than ThT (4), in the presence of amyloid β fibrils. These results suggest that Me-CUR (9) can become a useful in vitro amyloid fluorescence sensor for diagnosis of Alzheimer's disease.
- Sato, Taki,Hotsumi, Mayumi,Makabe, Koki,Konno, Hiroyuki
-
supporting information
p. 3520 - 3525
(2018/10/15)
-
- Cytotoxicity of Synthesized 1,4-Naphthoquinone Oxime Derivatives on Selected Human Cancer Cell Lines
-
In an effort to develop potent and selective antitumor agents, a series of 1,4-naphthoquinone oxime derivatives were designed and synthesized. The cytotoxicity of these compounds were evaluated against five human cancer cell lines (colorectal cancer cell: HCT-15, breast cancer cell: MDA-MB-231, liver cancer cell: BEL-7402, colorectal cancer cell: HCT-116 and ovarian cancer cell: A2780) in vitro. Among them, compound 14 was found to be the most potent cytotoxic compound against three cell lines (MDA-MB-231, BEL-7402 and A2780) with IC50 values of 0.66±0.05, 5.11±0.12 and 8.26±0.22μM, respectively. Additionally, the length of the side chains and the position of the substituent may also affect the cytotoxic activity of the naphthoquinone oxime derivatives. In general, compound 14 effectively inhibited breast cancer cell proliferation and may become a promising anticancer agent.
- Zhang, Qijing,Dong, Jinyun,Cui, Jiahua,Huang, Guang,Meng, Qingqing,Li, Shaoshun
-
p. 612 - 619
(2018/06/11)
-
- Dehydrogenation of 5-hydroxymethylfurfural to diformylfuran in compressed carbon dioxide: An oxidant free approach
-
The dehydrogenation of biomass-based 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) was achieved utilizing an activated carbon supported rhodium (Rh/C) catalyst under mild reaction conditions. The developed method successfully afforded complete conversion and the highest selectivity of DFF (>99%) without any additive, conventional hydrogen acceptor and oxidant. The efficiency of the method is achieved by the addition of compressed carbon dioxide (scCO2) and the synergistic effect of scCO2 and Rh/C, where scCO2 plays a pivotal role in accelerating the reaction by removing hydrogen, and consequently shifting the equilibrium to the forward direction. Optimization of different reaction parameters ensures the achievement of high conversion and selectivity. Characterization of the catalyst using different spectroscopic techniques suggests an interaction between the substrate and the catalyst and provides an indication of the possible reaction pathway, thus a mechanism would be outlined. The rate determining step of the reaction was calculated through mechanistic investigations involving theoretical calculations together with experimental analysis. One of the most attractive features of the method developed in this study is the reverse reaction of DFF, which can be achieved in one-pot without the addition of any external hydrogen. This process has successful application to the dehydrogenation of a variety of alcohols with different substituents.
- Chatterjee, Maya,Ishizaka, Takayuki,Chatterjee, Abhijit,Kawanami, Hajime
-
p. 1315 - 1326
(2017/08/15)
-
- Catalytic oxidation of primary aromatic alcohols using half sandwich Ir(III), Rh(III) and Ru(II) complexes: A practical and theoretical study
-
The complexes [Cp*IrCl(N-(pyridin-2-ylmethylene)aniline)]PF6 (1), [Cp*RhCl(N-(pyridin-2-ylmethylene)aniline)]PF6 (2), (where Cp*?=?1,2,3,4,5-pentamethylcyclopentadiene) and [η6-areneRuCl(N-(pyridin-2-ylmethylene)aniline)]PF6 (3) have been synthesized and the structure and purity of these were confirmed by single crystal XRD and elemental analyses. Iridium and rhodium complexes exhibit the P21/n space group, the ruthenium complex the P21/c space group and all three complexes show the expected pseudo octahedral “piano-stool” geometry. The catalytic performance of these complexes for the dehydrogenation of primary alcohols to their respective aldehydes with different bases and solvents was investigated. The complexes of iridium and ruthenium give good conversions in different alkaline solutions. Density functional theory was applied to determine the respective MO energy levels, bond lengths, bond angles and binding energies of all the metal complexes. It was also used to study the activity, stability and intermediates of the complexes. A Gibbs free energy (ΔG) DFT calculation was carried out to help understand the reaction mechanism/catalytic cycle of the Rh complex (2). The energy barrier for oxidation of aromatic alcohols by the rhodium hydride complex is much lower (10.32?kcal/mol) than the barrier for hydride transfer of the corresponding Rh benzyloxo species (15.19?kcal/mol), in agreement with mechanisms proposed for related systems.
- Thangavel, Saravanan,Boopathi, Subramaniam,Mahadevaiah,Kolandaivel, Ponmalai,Pansuriya, Pramod B.,Friedrich, Holger B.
-
p. 160 - 171
(2016/07/19)
-
- Method of manufacturing calbonyl compd.
-
PROBLEM TO BE SOLVED: To provide a method of manufacturing a carbonyl compound by smoothly performing a dehydrogenation reaction while preventing side reactions.SOLUTION: A method of manufacturing a carbonyl compound includes a process of converting alcohol to aldehyde or ketone by irradiating visible light to a reaction system containing a primary alcohol or a secondary alcohol, SrTiOcarrying a Ru atom and doped with Rh atom, and water.
- -
-
Paragraph 0051; 0052
(2018/06/30)
-
- A Facile and Selective Procedure for Oxidation of Hydroquinones using Silica Gel Supported Catalytic Cerium(IV) Ammonium Nitrate
-
A new procedure for oxidation of hydroquinones to quinones using a silica gel supported cerium(IV) ammonium nitrate-NaBrO3 reagent has been developed. This simple, easy to prepare and use, heterogeneous reagent is highly selective towards oxidation of 1,4-dihydroxybenzenes and produces high yields of quinones. Waste generated by using this procedure is minimal.
- Ali, Mohammed Hashmat,Welker, Andrea,York, Crystal
-
p. 3207 - 3211
(2015/10/19)
-
- An expedient osmium(vi)/K3Fe(CN)6-mediated selective oxidation of benzylic, allylic and propargylic alcohols
-
A chemoselective osmium(vi) catalyzed oxidation of benzylic, allylic and propargylic alcohols using K3Fe(CN)6as a secondary oxidant is described. This protocol is operationally simple and exhibits excellent chemoselectivity favouring the oxidation of benzylic alcohols over the aliphatic alcohols. A larger scale reaction was also found to be compatible. This journal is
- Fernandes, Rodney A.,Bethi, Venkati
-
p. 40561 - 40568
(2015/02/18)
-
- Aerobic oxidation of alcohols by using a completely metal-free catalytic system
-
A metal-free reaction system of air, NH4NO3(cat), 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)(cat), and H +(cat) is introduced as a simple, safe, inexpensive, efficient and chemoselective mediator for aerobic oxidation of various primary and secondary benzyl and alkyl alcohols, including those bearing oxidizable heteroatoms (N, S, O) to the corresponding aldehydes or ketones. Air oxygen under slight overpressure plays the role of the terminal oxidant, which is catalytically activated by redox cycles of nitrogen oxides released from a catalytic amount of NH4NO3 and cocatalyzed by TEMPO (nitroxyl radical compound), under acidic conditions, which are essential for an overall activation of the reaction system. The synthetic value of this reaction system and its green chemical profile was illustrated by a 10 g scale-up experiment, performed in an open-air system by using a renewable and reusable polymer-supported form of TEMPO (OXYNITROXS100). The reaction solvent was recovered by distillation under atmospheric pressure, and the pure final product was isolated under reduced pressure; the acid activators (HCl or H 2SO4) were recovered as ammonium salts. A metal-free reaction system of air/NH4NO3(cat)/TEMPO (cat)/H+(cat) is introduced as a simple, safe, inexpensive, efficient and chemoselective mediator for aerobic oxidation of various primary and secondary benzyl, alkyl and allyl alcohols, including those bearing oxidizable heteroatoms (N, S, O) to the corresponding aldehydes or ketones. Copyright
- Prebil, Rok,Stavber, Gaj,Stavber, Stojan
-
supporting information
p. 395 - 402
(2014/01/23)
-
- Aerobic Oxidation of Alcohols by Using a Completely Metal-Free Catalytic System
-
A metal-free reaction system of air, NH4NO3(cat), 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)(cat), and H+(cat) is introduced as a simple, safe, inexpensive, efficient and chemoselective mediator for aerobic oxidation of various primary and secondary benzyl and alkyl alcohols, including those bearing oxidizable heteroatoms (N, S, O) to the corresponding aldehydes or ketones. Air oxygen under slight overpressure plays the role of the terminal oxidant, which is catalytically activated by redox cycles of nitrogen oxides released from a catalytic amount of NH4NO3 and cocatalyzed by TEMPO (nitroxyl radical compound), under acidic conditions, which are essential for an overall activation of the reaction system. The synthetic value of this reaction system and its green chemical profile was illustrated by a 10 g scale-up experiment, performed in an open-air system by using a renewable and reusable polymer-supported form of TEMPO (OXYNITROXS100). The reaction solvent was recovered by distillation under atmospheric pressure, and the pure final product was isolated under reduced pressure; the acid activators (HCl or H2SO4) were recovered as ammonium salts.
- Prebil, Rok,Stavber, Gaj,Stavber, Stojan
-
supporting information
p. 395 - 402
(2015/10/05)
-
- Redox-selective generation of aldehydes and H2 from alcohols under visible light
-
Photosynthetic dehydrogenation: Potential usefulness of visible-light-induced dehydrogenation of alcohols in organic synthesis was demonstrated, in which aldehydes and H2 were afforded by using Ru/SrTiO3:Rh and water (see scheme). Water was essential for the reaction. High efficiency (TON: up to 15 400 based on Rh; H2 and aldehyde evenly generated) and high selectivity were achieved. Copyright
- Liu, Zijun,Caner, Joaquim,Kudo, Akihiko,Naka, Hiroshi,Saito, Susumu
-
supporting information
p. 9452 - 9456
(2013/07/26)
-
- Mechanistic borderline of one-step hydrogen atom transfer versus stepwise Sc3+-coupled electron transfer from benzyl alcohol derivatives to a non-heme iron(IV)-oxo complex
-
The rate of oxidation of 2,5-dimethoxybenzyl alcohol (2,5-(MeO) 2C6H3CH2OH) by [Fe IV(O)(N4Py)]2+ (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2- pyridyl)methylamine) was enhanced significantly in the presence of Sc(OTf) 3 (OTf- = trifluoromethanesulfonate) in acetonitrile (e.g., 120-fold acceleration in the presence of Sc3+). Such a remarkable enhancement of the reactivity of [FeIV(O)(N4Py)] 2+ in the presence of Sc3+ was accompanied by the disappearance of a kinetic deuterium isotope effect. The radical cation of 2,5-(MeO)2C6H3CH2OH was detected in the course of the reaction in the presence of Sc3+. The dimerized alcohol and aldehyde were also produced in addition to the monomer aldehyde in the presence of Sc3+. These results indicate that the reaction mechanism is changed from one-step hydrogen atom transfer (HAT) from 2,5-(MeO)2C6H3CH2OH to [Fe IV(O)(N4Py)]2+ in the absence of Sc3+ to stepwise Sc3+-coupled electron transfer, followed by proton transfer in the presence of Sc3+. In contrast, neither acceleration of the rate nor the disappearance of the kinetic deuterium isotope effect was observed in the oxidation of benzyl alcohol (C6H5CH2OH) by [FeIV(O)(N4Py)]2+ in the presence of Sc(OTf) 3. Moreover, the rate constants determined in the oxidation of various benzyl alcohol derivatives by [FeIV(O)(N4Py)]2+ in the presence of Sc(OTf)3 (10 mM) were compared with those of Sc 3+-coupled electron transfer from one-electron reductants to [Fe IV(O)(N4Py)]2+ at the same driving force of electron transfer. This comparison revealed that the borderline of the change in the mechanism from HAT to stepwise Sc3+-coupled electron transfer and proton transfer is dependent on the one-electron oxidation potential of benzyl alcohol derivatives (ca. 1.7 V vs SCE).
- Morimoto, Yuma,Park, Jiyun,Suenobu, Tomoyoshi,Lee, Yong-Min,Nam, Wonwoo,Fukuzumi, Shunichi
-
p. 10025 - 10036
(2012/10/29)
-
- Synthesis of novel isoxazole-benzoquinone hybrids via 1,3-dipolar cycloaddition reaction as key step
-
An efficient method for the preparation of novel 2-(5-arylisoxazol-3-yl) cyclohexa-2,5-diene-1,4-dione hybrids via 1,3-dipolar cycloaddition followed by an oxidation reaction using ceric ammonium nitrate (CAN) has been described. Using this method, various aryl as well as alkyl substituted isoxazole-benzoquinone hybrids were synthesized in high yields.
- Ravi Kumar,Behera, Manoranjan,Raghavulu,Jaya Shree,Yennam, Satyanarayana
-
scheme or table
p. 4108 - 4113
(2012/08/28)
-
- Facile preparation of aromatic esters from aromatic bromides with ethyl formate or DMF and molecular iodine via aryllithium
-
Various aromatic bromides were treated with n-BuLi and subsequently with ethyl formate, followed by the reaction with ethanol and molecular iodine in the presence of K2CO3 to provide the corresponding aromatic ethyl esters in good yields. Moreover, aromatic bromides could be transformed into the corresponding aromatic methyl esters in good yields by the treatment with n-BuLi and subsequently with DMF, followed by the reaction with methanol, molecular iodine, and K2CO3. Some aromatics could be also converted into the corresponding aromatic esters in good yields by the treatment with n-BuLi, and subsequently with ethyl formate or DMF, followed by the reaction with molecular iodine and K2CO3. The present reactions offer a novel route for the transition-metal-free, carbon-monoxide-free, and therefore environmentally benign one-pot conversion of aromatic bromides and aromatics into aromatic esters.
- Ushijima, Sousuke,Moriyama, Katsuhiko,Togo, Hideo
-
experimental part
p. 4701 - 4709
(2012/07/28)
-
- Nanocrystalline magnesium oxide stabilized palladium(0): An efficient reusable catalyst for room temperature selective aerobic oxidation of alcohols
-
Nanocrystalline magnesium oxide-stabilized palladium(0) [NAP-Mg-Pd(0)], as an efficient catalytic system has been employed for the selective oxidation of alcohols using atmospheric oxygen as a green oxidant at room temperature. Various alcohols could be transformed into their corresponding aldehydes or ketones in good to excellent yields using a set of optimal conditions. NanoActive Magnesium Oxide Plus, [NAP-MgO] with its three-dimensional structure and well-defined shape acts as an excellent support for well dispersed palladium(0) nanoparticles. This catalyst can be recovered and reused for several cycles without any significant loss of catalytic activity.
- Layek, Keya,Maheswaran,Arundhathi,Kantam, M. Lakshmi,Bhargava, Suresh K.
-
supporting information; experimental part
p. 606 - 616
(2011/04/25)
-
- Oxidation of benzylic alcohols to their corresponding carbonyl compounds using ceric ammonium nitrate (CAN)/broensted acidic ionic liquid
-
A chemoselective and efficient procedure for the oxidation of alcohols to the corresponding carbonyl compounds is reported using ceric ammonium nitrate in the presence of 3-methylimidazolium hydrogensulfate as Broensted acidic ionic liquid ([Hmim]HSO4) as the solvent under mild conditions. The use of non-toxic and inexpensive materials, straightforward procedure, short reaction times and good yields of the products are the major advantages of this method.
- Hajipour,Khazdooz,Ruoho
-
experimental part
p. 382 - 387
(2012/06/18)
-
- A practical chemo-enzymatic approach to highly enantio-enriched cyanohydrin acetates
-
The preparation of enantiopure cyanohydrin acetates via enzymatic hydrolysis has been investigated by screening a range of biocatalysts and reaction conditions. Enzymatic resolution has been optimised through variation of the hydrolase biocatalyst and reaction conditions leading to synthetically useful routes to enantiopure cyanohydrin acetates.
- Maguire, Nuala M.,Ford, Alan,Clarke, Sarah L.,Eccles, Kevin S.,Lawrence, Simon E.,Brossat, Maude,Moody, Thomas S.,Maguire, Anita R.
-
experimental part
p. 2144 - 2150
(2012/05/04)
-
- Mild and chemoselective synthesis and deprotection of geminal diacetates catalyzed by titanium(IV) halides
-
A novel, mild, and chemoselective method was developed for the preparation of gem-diacetates from aldehydes and acetic anhydride in the presence of titanium(IV) fluoride (1-5 mol%) under solvent-free conditions at room temperature. The reaction showed a high chemoselectivity toward aldehydes in the presence of ketones. Moreover, titanium(IV) fluoride also catalyzed the deprotection of gem-diacetates to the corresponding aldehydes in water. This efficient and simple method has several benefits, including the use of an inexpensive catalyst, solvent-free conditions, mild reaction temperatures, and high yields, which make it both cost-effective and environmentally friendly. Georg Thieme Verlag Stuttgart.
- Jung, Misuk,Yoon, Jieun,Kim, Hak Sung,Ryu, Jae-Sang
-
experimental part
p. 2713 - 2720
(2010/10/02)
-
- Oxidative decarboxylation of 2-aryl carboxylic acids using (Diacetoxyiodo)benzene for preparation of aryl aldehydes, ketones, and nitriles
-
A novel synthetic application of the hypervalent iodine reagent, (diacetoxyiodo)benzene, and catalytic amount of sodium azide in acetonitrile for oxidative decarboxylation of 2-aryl carboxylic acids into corresponding aldehydes, ketones, and nitriles at room temperature is described. The advantages of this protocol are shorter reaction times and mild reaction conditions to obtain moderate to good yields.
- Telvekar, Vikas N.,Sasane, Kulbhushan A.
-
scheme or table
p. 2778 - 2780
(2010/12/25)
-
- Improved synthesis of diquinones
-
Preparation of a series of substituted diquinones is reported. In most examples, inverse order of addition (addition of a dimethoxybenzene derivative to a CAN solution) has been found to produce higher yields of diquinones than the traditional protocol in which the oxidant is added to the arene. Georg Thieme Verlag Stuttgart.
- Love, Brian E.,Bonner-Stewart, Jeffrey,Forrest, Lori A.
-
body text
p. 813 - 817
(2009/06/19)
-
- Reusable copper-aluminum hydrotalcite/rac-BINOL system for room temperature selective aerobic oxidation of alcohols
-
An efficient catalyst system consisting of copper-aluminum hydrotalcite/rac-BINOL ligand has been developed for the oxidation of alcohols using air as a green oxidant at room temperature. Various alcohols could be transformed into their corresponding aldehydes or ketones in good to excellent yields using the set of optimal conditions. This composite catalytic system can also be recovered and reused for several cycles without a significant loss of catalytic activity.
- Lakshmi Kantam,Arundhathi,Likhar, Pravin R.,Damodara
-
supporting information; experimental part
p. 2633 - 2637
(2009/12/30)
-
- Solvent-free oxidation of alcohols with potassium persulphate in the presence of bronsted acidic ionic liquids
-
An efficient conversion of alcohols to aldehydes was achieved using potassium persulphate and 3-methylimidazolinium methane sulfonate. Copyright Taylor & Francis Group, LLC.
- Chaskar,Bhandari,Patil,Sharma,Mayeker
-
experimental part
p. 366 - 370
(2009/04/07)
-
- Synthesis of photosynthesis-inhibiting nostoclide analogues
-
A series of 34 3-benzyl-5-(arylmethylene)furan-2(5H)-ones, designed using the naturally occurring toxins nostoclides as a lead structure, was synthesized as potential inhibitors of the photosynthetic electron transport. All compounds were fully characterized by IR, NMR (1H and 13C), and MS spectrometry. HMBC and HSQC bidimensional experiments allowed 13C and 1H assignments. Their biological activities were evaluated in vitro as the ability to interfere with light-driven reduction of ferricyanide by isolated spinach chloroplasts. About two-thirds of the compounds exhibited inhibitory properties in the micromolar range against the basal electron flow from water to K3[Fe(CN)6]. The inhibitory potential of these 3-benzyl-5-(arylmethylene)furan-2(5H)-one lactones is higher than that of other nostoclide analogues previously synthesized in the same laboratories.
- Teixeira, Robson R.,Barbosa, Luiz C. A.,Forlani, Giuseppe,Pilo-Veloso, Dorila,Carneiro, Jose Walkimar De Mesquita
-
experimental part
p. 2321 - 2329
(2009/12/29)
-
- Facile and selective oxidation of benzylic alcohols to their corresponding carbonyl compounds with sodium nitrate in the presence of Br?nsted acidic ionic liquids
-
A chemoselective and effective procedure for the conversion of benzylic and allylic alcohols into the corresponding carbonyl compounds using sodium nitrate-3-methylimidazolinium hydrogensulfate is reported. Georg Thieme Verlag Stuttgart.
- Hajipour, Abdol R.,Rafiee,Ruoho
-
p. 1118 - 1120
(2008/03/11)
-
- TEMPO-copper(II) diimine-catalysed oxidation of benzylic alcohols in aqueous media
-
In situ generated copper(II)-diimine complexes combined with TEMPO (2,2,6,6-tetramethyl-piperidinyl-1-oxyl radical) were studied in the oxidation of benzylic alcohols, the focus being on enviromentally benign reaction conditions. In this respect, reactions were studied in aqueous alkaline solutions and dioxygen was used as an end oxidant. This simple catalytic system turned out to be highly efficient and selective in the oxidation of primary and secondary benzylic alcohols to their corresponding carbonyl compounds. Under optimised reaction conditions [5 mol% of TEMPO, 3 mol% of copper(II) diimine, pH 12.6-13.5, 80°C, 10 bar O2] benzyl alcohol was quantitatively and selectively oxidised to benzaldehyde. According to ESI-MS studies, coordination of TEMPO, as well as deprotonated benzyl alcohol to the parent copper-diimine complex in aqueous solutions is feasible. Supported by these observations a plausible reaction mechanism is proposed for the oxidation reaction.
- Figiel, Pawel J.,Leskelae, Markku,Repo, Timo
-
p. 1173 - 1179
(2008/03/27)
-
- Oxidation of benzylic alcohols to their corresponding carbonyl compounds using KIO4 in ionic liquid by microwave irradiation
-
A chemoselective, straightforward, and rapid method for oxidation of alcohols to the corresponding carbonyl compounds using microwave irradiation and a catalytic amount of ionic liquid is reported. The reaction has been carried out with excellent yields and short reaction times. Copyright Taylor & Francis Group, LLC.
- Hajipour, Abdol Reza,Rafiee, Fatemeh,Ruoho, Arnold E.
-
p. 2563 - 2568
(2007/10/03)
-
- Catalytic oxidations of alcohols to carbonyl compounds by oxygen under solvent-free and transition-metal-free conditions
-
A green catalytic oxidation of alcohols to carbonyl compounds by oxygen was developed by using catalytic amounts of [bis(acetoxy)iodo]benzene/TEMPO/ KNO2. In addition, the use of a catalytic amount of poly[4-(bis(acetoxy)iodo)]styrene led to yields (up to 99%) comparable to the non-supported hypervalent iodine reagent, while offering the advantage of an efficient recovery and the subsequent recycling of the hypervalent iodine reagent.
- Herrerías, Clara I.,Zhang, Tony Y.,Li, Chao-Jun
-
-
- Deprotection of oximes using lodosobenzene in the presence of β-cyclodextrin in water
-
A mild and efficient method for the regeneration of carbonyl compounds from oximes at room temperature in impressive yields has been developed using iodosobenzene/KBr in the presence of β-cyclodextrin in water. Copyright Taylor & Francis Group, LLC.
- Narender,Somi Reddy,Srilakshmi Krishnaveni,Surendra,Nageswar,Rama Rao
-
p. 1463 - 1470
(2007/10/03)
-
- Synthesis of 5,8-dimethoxynaphtho[2,3-c]furan-4(9H)-one
-
The synthesis of the title compound, which shares its skeleton with a number of biologically active natural products, is described. The key steps are construction of a 3,4-disubstituted furan by a tandem Diels-Alder-retro-Diels- Alder reaction of an alkyne with 4-phenyloxazole, and an intramolecular Friedel-Crafts acylation.
- Piggott, Matthew J.,Wege, Dieter
-
p. 3550 - 3556
(2007/10/03)
-
- Synthesis of deuterium labeled phenethylamine derivatives
-
The synthesis of a series of five deuterium labeled phenethylamine derivatives, 4-bromo-2,5-[2H6]-dimethoxyphenethylamine (2C-B), 4-chloro-2,5-[2H6]-dimethoxyphenethylamine (2C-C), 2,5-[2H6]-dimethoxy-4-iodophenethylamine (2C-I), 2,5-[2H6]-dimethoxy-4-ethylthiophenethylamine (2C-T-2) and 2,5-[2H6]-dimethoxy-4-n-propylthiophenethylamine (2C-T-7) from 1,4-[2H6]-dimethoxybenzene is described. The isotopically labeled compounds are used as internal standards in gas chromatography-mass spectrometry (GC-MS) assays. Copyright
- Xu, Ya-Zhu,Chen, Chinpiao
-
p. 1187 - 1200
(2008/04/18)
-
- Kinetics of oxidation of benzyl alcohols by the dication and radical cation of ABTS. Comparison with laccase-ABTS oxidations: An apparent paradox
-
Laccase, a blue copper oxidase, in view of its moderate redox potential can oxidise only phenolic compounds by electron-transfer. However, in the presence of ABTS (2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) as a redox mediator, laccase reacts with the more difficult to oxidise non-phenolic substrates, such as benzyl alcohols. The role of ABTS in these mediated oxidations is investigated. Redox interaction with laccase could produce in situ two reactive intermediates from ABTS, namely ABTS++ or ABTS ?+. These species have been independently generated by oxidation with Ce(IV) or Co(III) salts, respectively, and their efficiency as monoelectronic oxidants tested in a kinetic study towards a series of non-phenolic substrates; a Marcus treatment is provided in the case of ABTS ++. On these grounds, intervention of ABTS++ as a reactive intermediate in laccase-ABTS oxidations appears unlikely, because the experimental conditions under which ABTS++ is unambiguously generated, and survives long enough to serve as a diffusible mediator, are too harsh (2 M H2SO4 solution) and incompatible with the operation of the enzyme. Likewise, ABTS?+ seems an intermediate of limited importance in laccase-ABTS oxidations, because this weaker monoelectronic oxidant is unable to react directly with many of the non-phenolic substrates that laccase-ABTS can oxidise. To solve this paradox, it is alternatively suggested that degradation by-products of either ABTS ++ or ABTS?+ are formed in situ by hydrolysis during the laccase-ABTS reactions, and may be responsible for the observed oxidation of non-phenolics. The Royal Society of Chemistry 2005.
- Branchi, Barbara,Galli, Carlo,Gentili, Patrizia
-
p. 2604 - 2614
(2007/10/03)
-
- A facile β-cyclodextrin-catalyzed oxidative deprotection of tert-butyldimethylsilyl (TBDMS) ethers with NBS in water
-
Treatment of TBDMS ethers with NBS in the presence of β-cyclodextrin in water results, for the first time, in the cleavage of the silicon-oxygen bond, carbonyl compounds are obtained upon oxidation.
- Reddy, M. Somi,Narender,Nageswar,Rao, K. Rama
-
p. 714 - 716
(2007/10/03)
-
- Synthesis of aromatic aldehydes by oxidative hydroxymethylation
-
A new high yield method for the synthesis of aromatic aldehydes has been developed. The procedure is based on an acid catalyzed hydroxymethylation of an arene substrate by paraformaldehyde with concurrent selective oxidation of the intermediate aromatic carbinol by 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) to the aldehyde product.
- Branytska, Oiena,Neumann, Ronny
-
p. 1575 - 1576
(2007/10/03)
-
- Regeneration of carbonyl compounds by oxidative cleavage of oximes with NBS in the presence of β-cyclodextrin in water
-
The conversion of different oximes to the corresponding carbonyl compounds was carried out at room temperature in good to high yields with N-bromosuccinimide in water in the presence of β-cyclodextrin.
- Reddy, M. Somi,Narender,Rao, K. Rama
-
p. 3875 - 3881
(2007/10/03)
-
- 2,6-Dicarboxypyridinium chlorochromate. An efficient and selective reagent for the mild deprotection of acetals, thioacetals, and 1,1-diacetates to carbonyl compounds
-
2,6-Dicarboxypyridinium chlorochromate (2,6-DCPCC) was found to be an efficient reagent for the conversion of acetals, thioacetals, and 1,1-diacetates to their corresponding carbonyl compounds under neutral and anhydrous conditions in good to excellent yields. Selective deprotection of acetals or 1,1-diacetates in the presence of thioacetals at room temperature is also observed with this reagent. Springer-Verlag 2004.
- Hosseinzadeh, Rahman,Tajbakhsh, Mahmood,Shakoori, Alireza,Niaki, Mohammad Yazdani
-
p. 1243 - 1249
(2007/10/03)
-
- New Applications of 2,4,6-Trichloro-1,3,5-triazine (TT) in Synthesis: Highly Efficient and Chemoselective Deprotection and Ring-Enlargement of Dithioacetals and Oxathioacetals
-
Efficient deprotection of a wide variety of 1,3-dithioacetals and 1,3-oxathiolanes to the corresponding carbonyl compounds at room temperature using a combination of 2,4,6-trichloro-1,3,5-triazine (TT) and dimethyl sulfoxide (DMSO) was investigated. In this way, 1,3-oxathioacetals and 1,3-dithioacetals of enolizable ketones were converted to the corresponding 1,4-oxathiepine and 1,4-dithiepine derivatives, respectively.
- Karimi, Babak,Hazarkhani, Hassan
-
p. 2547 - 2551
(2007/10/03)
-
- Process for preparing 2,5-dimethoxy benzaldehyde
-
The present invention recites a process for the of 2,5-dimethoxy-benzaldehyde by reacting a 2-hydroxy-5 methoxy-benzaldehyde with a suitable metal hydroxide in the presence of a suitable solvent to make a metal salt of 2-hydroxy-5-methoxy benzaldehyde comprising. The invention further provides a method for alkylating said metal salts with dimethylsulfate in the presence of a suitable solvent so as to provide a 2,5-dimethoxy benzaldehyde.
- -
-
Page/Page column 5
(2008/06/13)
-
- Deoximation of oximes with 2-iodylbenzoic acid in water in the presence of β-cyclodextrin
-
Oximes of various aldehydes and ketones can be converted to the corresponding carbonyl compounds at room temperature in impressive yields with 2-iodylbenzoic acid in water in the presence of β-cyclodextrin.
- Krishnaveni, N. Srilakshmi,Surendra,Nageswar,Rao, K. Rama
-
p. 1968 - 1970
(2007/10/03)
-
