- The tremulanes, a new group of sesquiterpenes from the aspen rotting fungus Phellinus tremulae
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A series of new sesquiterpenes, the tremulanes, possessing a previously unreported substituted perhydroazulene carbon skeleton, has been isolated from liquid cultures of the aspen (Populus tremuloides) rotting fungus Phellinus tremulae. The structures were determined by NMR techniques (1H- 1H COSY, HMQC, and HMBC) and other physical methods including, in the case of tremulenolide A (6), X-ray crystallography. The chemical correlation of tremulenediol A (10) with tremulenolide A (6) is described as is the correlation of tremulenedial (8) with tremulenediol B (11). The absolute configuration of the compounds is assigned by application of the olefin octant rule to the allylic alcohol tremulenediol A (10). These new sesquiterpenes do not obey the biogenetic isoprene rule and it is suggested that they may not be derived from farnesyl pyrophosphate.
- Ayer,Cruz
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- Ni-NiO heterojunctions: a versatile nanocatalyst for regioselective halogenation and oxidative esterification of aromatics
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Herein, we report a facile method for the synthesis of Ni-NiO heterojunction nanoparticles, which we utilized for the nuclear halogenation reaction of phenol and substituted phenols usingN-bromosuccinimide (NBS). A remarkablepara-selectivity was achieved for the halogenated products under semi-aqueous conditions. Interestingly, blocking of thepara-position of phenol offeredortho-selective halogenation. In addition, the Ni-NiO nanoparticles catalyzed the oxidative esterification of carbonyl compounds with alcohol, diol or dithiol in the presence of a catalytic amount of NBS. It was observed that the aromatic carbonyls substituted with an electron-donating group favoured nuclear halogenation, whereas an electron-withdrawing group substitution in carbonyl compounds facilitated the oxidation reaction. In addition, the catalyst was magnetically separated and recycled 10 times. The tuned electronic structure at the Ni-NiO heterojunction controlled selectivity and activity as no suchpara-selectivity was observed with commercially available NiO or Ni nanoparticles.
- Bhardwaj, Nivedita,Goel, Bharat,Indra, Arindam,Jain, Shreyans K.,Singh, Ajit Kumar,Tripathi, Nancy
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p. 14177 - 14183
(2021/08/16)
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- Electro-Oxidative Selective Esterification of Methylarenes and Benzaldehydes
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A mild and green electro-oxidative protocol to construct aromatic esters from methylarenes and alcohols is herein reported. Importantly, the reaction is free of metals, chemical oxidants, bases, acids, and operates at room temperature. Moreover, the design of the electrolyte was found critical for the oxidation state and structure of the coupling products, a rarely documented effect. This electro-oxidative coupling process also displays exceptional tolerance of many fragile easily oxidized functional groups such as hydroxy, aldehyde, olefin, alkyne, as well as neighboring benzylic positions. The enantiomeric enrichment of some chiral alcohols is moreover preserved during this electro-oxidative coupling reaction, making it overall a promising synthetic tool.
- Yu, Congjun,?zkaya, Bünyamin,Patureau, Frederic W.
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supporting information
p. 3682 - 3687
(2021/02/01)
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- The Highly Effective Cobalt Based Metal–Organic Frameworks Catalyst for One Pot Oxidative Esterification Under Mild Conditions
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The cobalt-based metal organic frameworks (Co-MOFs) catalyst has been prepared with using terephthalic acid and 4,4′-bipyridine as organic linkers by facile solvothermal method for one pot oxidative esterification. The prepared catalyst was pyrolysed at different temperature and then applied for oxidation of aldehyde using molecular oxygen as benign oxidant under mild conditions. The Co-MOFs pyrolysed at 800?°C (denoted as Co-MOFs-800) catalyst exhibited excellent catalytic activity, selectivity and recyclability toward the oxidative esterification of benzaldehydes. Furthermore, it can be reused up to 5 runs without significant loss of activity. Graphic Abstract: [Figure not available: see fulltext.]
- Chindawong, Chakkresit,Mekrattanachai, Pagasukon,Setthaya, Naruemon,Song, Wei Guo,Zhu, Lei
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- Di(hydroperoxy)adamantane adducts: Synthesis, characterization and application as oxidizers for the direct esterification of aldehydes
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The di(hydroperoxy)adamantane adducts of water (1) and phosphine oxides p-Tol3PO·(HOO)2C(C9H14) (2), o-Tol3PO·(HOO)2C(C9H14) (3), and Cy3PO·(HOO)2C(C9H14) (4), as well as a CH2Cl2 adduct of a phosphole oxide dimer (8), have been created and investigated by multinuclear NMR spectroscopy, and by Raman and IR spectroscopy. The single crystal X-ray structures for 1-4 and 8 are reported. The IR and 31P NMR data are in accordance with strong hydrogen bonding of the di(hydroperoxy)adamantane adducts. The Raman ν(O-O) stretching bands of 1-4 prove that the peroxo groups are present in the solids. Selected di(hydroperoxy)alkane adducts, in combination with AlCl3 as catalyst, have been applied for the direct oxidative esterification of n-nonyl aldehyde, benzaldehyde, p-methylbenzaldehyde, p-bromobenzaldehyde, and o-hydroxybenzaldehyde to the corresponding methyl esters. The esterification takes place in an inert atmosphere, under anhydrous and oxygen-free conditions, within a time frame of 45 minutes to 5 hours at room temperature. Hereby, two oxygen atoms per adduct assembly are active with respect to the quantitative transformation of the aldehyde into the ester.
- Arp, Fabian F.,Ashirov, Rahym,Bhuvanesh, Nattamai,Blümel, Janet
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supporting information
p. 15296 - 15309
(2021/11/16)
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- Method for preparing carboxylic ester compounds by oxidizing and breaking carbon-carbon bonds of secondary alcohol compounds
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The invention discloses a method for preparing carboxylic ester compounds by oxidizing and breaking carbon-carbon bonds of secondary alcohol compounds. The method comprises the following steps: adding a secondary alcohol compound, an additive and a nitrogen-doped mesoporous carbon loaded monatomic catalyst into a fatty primary alcohol solvent, putting into a pressure container, sealing, introducing oxygen source gas with a certain pressure, controlling the pressure of the oxygen source gas to be 0.1-1 MPa and the reaction temperature to be 80-150 DEG C, and obtaining a product after the reaction to be the carboxylic ester compound. The nitrogen-doped mesoporous carbon-loaded monatomic catalyst adopted by the invention is high in activity, the highest separation yield of the carboxylic ester compound as a reaction product reaches 99%, the method is wide in application range, the reaction conditions are easy to control, the catalyst can be recycled, the post-treatment is simple, and the method is suitable for industrial production.
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Paragraph 0056-0057; 0092
(2021/06/02)
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- Br?nsted acid-catalyzed chlorination of aromatic carboxylic acids
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The chlorination of aromatic carboxylic acids with SOCl2 has been effectively performed by reacting with a Br?nsted acid as the catalyst. Based on this discovery, an efficient catalytic method that is cheaper than traditional catalytic methods was developed. 20 substrates were chlorinated offering excellent yields in a short reaction time. And the SOCl2/Br?nsted acid system has been used in a larger scale preparative reaction. A dual activation mechanism was proposed to prove the irreplaceable system of SOCl2/Br?nsted acid.
- Yu, Zhiqun,Yao, Hongmiao,Xu, Qilin,Liu, Jiming,Le, Xingmao,Ren, Minna
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p. 685 - 689
(2021/04/09)
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- Oxidative esterification of alcohols by a single-side organically decorated Anderson-type chrome-based catalyst
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The direct esterification of alcohols with non-noble metal-based catalytic systems faces great challenges. Here, we report a new chrome-based catalyst stabilized by a single pentaerythritol decorated Anderson-type polyoxometalate, [N(C4H9)4]3[CrMo6O18(OH)3C{(OCH2)3CH2OH}], which can realize the efficient transformation from alcohols to esters by H2O2oxidation in good yields and high selectivity without extra organic ligands. A variety of alcohols with different functionalities including some natural products and pharmaceutical intermediates are tolerated in this system. The chrome-based catalyst can be recycled several times and still keep the original configuration and catalytic activity. We also propose a reasonable catalytic mechanism and prove the potential for industrial applications.
- Wang, Jingjing,Jiang, Feng,Tao, Chaofu,Yu, Han,Ruhlmann, Laurent,Wei, Yongge
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supporting information
p. 2652 - 2657
(2021/04/21)
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- Efficient aerobic oxidation of alcohols to esters by acidified carbon nitride photocatalysts
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Photocatalytic aerobic oxidation of alcohols for the direct synthesis of esters has received significant attention in recent years, but the relatively low efficiency and selectivity under visible light irradiation is the main challenge for their practical applications. Here, surface acidic sites were imparted onto metal-free heterogeneous photocatalysts by the protonation of carbon nitride (HMCN) to promote the activity for the esterification reaction through further adsorption and activation of the intermediate aldehyde. The activation of the substrate could be remarkably modulated through tuning the acidic sites on the surface of the photocatalyst, leading to a controllable reactivity of the catalytic reaction. The one-pot process for the direct aerobic oxidative esterification of alcohol exhibits high efficiency and selectivity under mild and additive-free conditions and the apparent quantum yield (AQY) of the photocatalytic esterification reaction is 0.41% at 420 nm. Moreover, a scalable photocatalytic process by the merging of a continuous flow system with the heterogeneous HMCN photocatalyst is demonstrated, combining high catalytic efficiency and stability at ambient temperatures and being promising for larger-scale applications.
- Antonietti, Markus,Cheng, Jiajia,Lin, Sen,Savateev, Aleksandr,Wan, Qiang,Wang, Chong,Wang, Xinchen
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p. 116 - 125
(2020/12/21)
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- Preparation method of methyl benzoate compound
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A preparation method of a methyl benzoate compound comprises the step that the methyl benzoate compound is prepared by carrying out esterification reaction on a benzoic acid compound and methyl alcohol under the catalysis of dihalogen hydantoin, and the molar ratio of the benzoic acid compound to the dihalogen hydantoin to the methyl alcohol is 1: (0.01-0.4): (2-30). According to the preparation method, the methyl benzoate compound can be efficiently prepared under mild conditions, the operation is safe, no acid waste liquid exists, meanwhile, raw materials are easy to obtain, and the production cost is low.
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Paragraph 0019; 0033-0034
(2021/08/14)
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- Design, synthesis and stepwise optimization of nitrile-based inhibitors of cathepsins B and L
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Human cathepsin B (CatB) is an important biological target in cancer therapy. In this work, we performed a knowledge-based design approach and the synthesis of a new set of 19 peptide-like nitrile-based cathepsin inhibitors. Reported compounds were assayed against a panel of human cysteine proteases: CatB, CatL, CatK, and CatS. Three compounds (7h, 7i, and 7j) displayed nanomolar inhibition of CatB and selectivity over CatK and CatL. The selectivity was achieved by using the combination of a para biphenyl ring at P3, halogenated phenylalanine in P2 and Thr-O-Bz group at P1. Likewise, compounds 7i and 7j showed selective CatB inhibition among the panel of enzymes studied. We have also described a successful example of bioisosteric replacement of the amide bond for a sulfonamide one [7e → 6b], where we observed an increase in affinity and selectivity for CatB while lowering the compound lipophilicity (ilogP). Our knowledge-based design approach and the respective structure–activity relationships provide insights into the specific ligand-target interactions for therapeutically relevant cathepsins.
- Cianni, Lorenzo,Rocho, Fernanda Dos Reis,Bonatto, Vinícius,Martins, Felipe Cardoso Prado,Lameira, Jer?nimo,Leit?o, Andrei,Montanari, Carlos A.,Shamim, Anwar
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supporting information
(2020/12/02)
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- Creative Construction of a Series of Chiral 3D Indium-Organic Frameworks with a umy Topology
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Using 2,2′-R2-biphenyl-4,4′-dicarboxylic acid to bind with a cis-[InO4(μ2-OH)2] octahedron, three novel chiral 3D indium-organic frameworks, [In(μ2-OH)L] [1, L1, R = N(CH3)2; 2, L2, R = OCH3; 3, L3, R = CH3], have been hydrothermally synthesized without chiral reagents. Crystal structure analyses reveal that 1-3 show an unprecedented 4-connected umy topology with the Schl?fli symbol (42·64). 1 exhibits high water stability and good sorption selectivity of CO2 over N2, while 3 displays high C2H2, C2H4, and C2H6 uptake capacity at 273 K.
- He, Xin,Wang, Xin,Xiao, Tianyu,Zhang, Shunlin,Zhu, Dunru
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supporting information
p. 9 - 13
(2021/01/11)
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- NOVEL PROCESS FOR THE PREPARATION OF ACALABRUTINIB AND ITS INTERMEDIATES
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The present invention relates to an improved and industrially viable process for the preparation of Acalabrutinib and its Intermediates. The present invention involves less expensive reagents, solvents and the process conditions can be easily adopted for commercial scale. The present invention relates to process for the preparation Acalabrutinib of formula (1) and process for the preparation of Acalabrutinib key starting material.
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Page/Page column 17-18
(2021/06/11)
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- Hydroxyl radical-mediated oxidative cleavage of CC bonds and further esterification reaction by heterogeneous semiconductor photocatalysis
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A hydroxyl radical-mediated aerobic cleavage of alkenes and further sequence esterification reaction for the preparation of carbonyl compounds have been developed by using tubular carbon nitride (TCN) as a general heterogeneous photocatalyst under an oxygen atmosphere with visible light irradiation. This protocol has an excellent substrate scope and gives the desired aldehydes, ketones and esters in moderate to high yields. Importantly, this metal-free procedure employed photogenerated hydroxyl radicals in situ as green oxidation active species, avoiding the present additional initiators. The reaction could be carried out under solar light irradiation and was applicable to large-scale reactions. Furthermore, the recyclable TCN catalyst could be used several times without a significant loss of activities.
- Hong, Mei,Jia, Rui,Miao, Hongyan,Ni, Bangqing,Niu, Tengfei,Wang, Hui
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p. 6591 - 6597
(2021/09/10)
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- Acetyl nitrate mediated conversion of methyl ketones to diverse carboxylic acid derivatives
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The development of a novel acetyl nitrate mediated oxidative conversion of methyl ketones to carboxylic acid derivatives is described. By analogy to the haloform reaction and supported by experimental and computational investigation we propose a mechanism for this transformation.
- Bernard, Josephine,Capilato, Joseph N.,Hoy, Erik P.,Mattiucci, Joseph,Pellegrinelli, Peter J.,Perez, Lark J.,Philippi, Shane,Schnorbus, Logan
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supporting information
p. 5298 - 5302
(2021/06/30)
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- Mild Copper-Catalyzed Addition of Arylboronic Esters to Di- tert -butyl Dicarbonate: An Easy Access to Methyl Arylcarboxylates
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An efficient copper-catalyzed addition of arylboronic esters to (Boc) 2O was developed. The reaction can be conducted under exceedingly mild conditions and is compatible with a variety of synthetically relevant functional groups. It therefore represents a useful alternative route for the synthesis of methyl arylcarboxylates. A preliminary mechanistic study indicated the involvement of an addition-elimination mechanism.
- Xu, Jin-Di,Su, Xiao-Bo,Wang, Cai,Yao, Li-Wei,Liu, Jing-Hui,Hu, Guo-Qin
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supporting information
p. 833 - 837
(2021/02/26)
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- N-Heterocyclic Carbene Catalyzed Ester Synthesis from Organic Halides through Incorporation of Oxygen Atoms from Air
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Oxygenation reactions with molecular oxygen (O2) as the oxygen source provides a green and straightforward strategy for the construction of O-containing compounds. Demonstrated here is a novel N-heterocyclic carbene (NHC) catalyzed oxidative transformation of simple and readily available organic halides into valuable esters through the incorporation of O-atoms from O2. Mechanistic studies prove that the deoxy Breslow intermediate generated in situ is oxidized to a Breslow intermediate for further transformation by this oxidative protocol. This method broadens the field of NHC catalysis and promotes oxygenation reactions with O2.
- Tan, Hui,Wang, Shen-An,Yan, Zixi,Liu, Jianzhong,Wei, Jialiang,Song, Song,Jiao, Ning
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supporting information
p. 2140 - 2144
(2020/12/01)
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- Direct bromodeboronation of arylboronic acids with CuBr2 in water
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An efficient and practical method has been developed for the preparation of aryl bromides via the direct bromodeboronation of arylboronic acids with CuBr2 in water. This strategy provides several advantages, such as being ligand-free, base-free, high yielding, and functional group tolerant.
- Tang, Yan-Ling,Xia, Xian-Song,Gao, Jin-Chun,Li, Min-Xin,Mao, Ze-Wei
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supporting information
(2021/01/05)
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- Cobalt Nanoparticles-Catalyzed Widely Applicable Successive C?C Bond Cleavage in Alcohols to Access Esters
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Selective cleavage and functionalization of C?C bonds have important applications in organic synthesis and biomass utilization. However, functionalization of C?C bonds by controlled cleavage remains difficult and challenging because they are inert. Herein, we describe an unprecedented efficient protocol for the breaking of successive C?C bonds in alcohols to form esters with one or multiple carbon atoms less using heterogeneous cobalt nanoparticles as catalyst with dioxygen as the oxidant. A wide range of alcohols including inactive long-chain alkyl aryl alcohols undergo smoothly successive cleavage of adjacent ?(C?C)n? bonds to afford the corresponding esters. The catalyst was used for seven times without any decrease in activity. Characterization and control experiments disclose that cobalt nanoparticles are responsible for the successive cleavage of C?C bonds to achieve excellent catalytic activity, while the presence of Co-Nx has just the opposite effect. Preliminary mechanistic studies reveal that a tandem sequence reaction is involved in this process.
- Dai, Wen,Gao, Shuang,Li, Guosong,Luo, Huihui,Lv, Ying,Shang, Sensen,Wang, Lianyue
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supporting information
p. 19268 - 19274
(2020/08/26)
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- Nickel salt of phosphomolybdic acid as a bi-functional homogeneous recyclable catalyst for base free transformation of aldehyde into ester
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A Ni salt of phosphomolybdic acid (NiHPMA) was synthesized and characterized by various physico-chemical techniques such as EDX, UV-Visible spectroscopy, FT-IR, Raman spectroscopy and XPS. FT-IR and Raman spectroscopy confirm the presence of Ni as a counter cation while UV-Visible and XPS studies to confirm the presence of Ni(ii) in the catalyst. The catalyst was evaluated for its bi-functional activity towards the tandem conversion of benzaldehyde to ethyl benzoate and it was found that very small amounts of Ni (2.64 × 10?3mmol) enhance the selectivity towards benzoate. A detailed mechanistic study was carried out by UV-Visible and Raman spectroscopy to confirm that both intermediate species, Mo-peroxo and Ni-oxo, are responsible for higher selectivity towards esters. Further, a study to determine the effect of addenda atoms (heteropoly acid) was also carried out. The catalyst was also found to be viable for a number of aldehydes under optimized conditions.
- Patel, Anjali,Patel, Jay
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p. 22146 - 22155
(2020/07/03)
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- Sodium pyruvate as a peroxide scavenger in aerobic oxidation under carbene catalysis
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NHC-Catalyzed aerobic oxidative reactions of imines and aldehydes have been developed by using sodium pyruvate as a novel and efficient peroxide scavenger. A structurally diverse set of imidates and amidines has been prepared from imines using this strategy. This general and efficient strategy features the use of sodium pyruvate as a novel and efficient peroxide scavenger and ambient air as the sole oxidant to efficiently control the NHC-catalyzed aerobic reaction pathway (selective realization of the oxidative pathway) under mild and green conditions. This journal is
- Fu, Zhenqian,Hong, Xianfang,Huang, Wei,Wang, Guanjie,Wei, Chenlong
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supporting information
p. 6819 - 6826
(2020/11/09)
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- Methoxylation of Acyl Fluorides with Tris(2,4,6-trimethoxyphenyl)phosphine via C-OMe Bond Cleavage under Metal-Free Conditions
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Acyl fluorides are subjected to methoxylation with tris(2,4,6-trimethoxyphenyl)phosphine (TMPP) to afford the corresponding methyl esters in good to excellent yields. This transformation is featured by C(sp2)-OMe bond cleavage under metal-free conditions. Unprecedented utilization of TMPP as a methoxylating agent realized the installation of an OMe group into the desired products.
- Ishida, Takumi,Nishihara, Yasushi,Wang, Xiu,Wang, Zhenhua
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p. 7526 - 7533
(2020/06/27)
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- C-C Bond Cleavage of Unactivated 2-Acylimidazoles
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2-Acylimidazoles are widely used as post-Transformable carboxylic acid equivalents in chemoselective and enantioselective reactions. Their transformations, however, require pretreatment with highly reactive, toxic methylating reagents to facilitate C-C bond cleavage. Here, we demonstrate that such pretreatment can be avoided and the C-C bond cleaved under neutral conditions without the use of additional reagents or catalysts. The scope of the reaction, including the use of products reported in the literature as substrates, and some mechanistic insights are described.
- Xin, Hai-Long,Pang, Bo,Choi, Jeesoo,Akkad, Walaa,Morimoto, Hiroyuki,Ohshima, Takashi
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p. 11592 - 11606
(2020/10/23)
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- Palladium-Catalyzed Chlorocarbonylation of Aryl (Pseudo)Halides Through In Situ Generation of Carbon Monoxide
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An efficient palladium-catalyzed chlorocarbonylation of aryl (pseudo)halides that gives access to a wide range of carboxylic acid derivatives has been developed. The use of butyryl chloride as a combined CO and Cl source eludes the need for toxic, gaseous carbon monoxide, thus facilitating the synthesis of high-value products from readily available aryl (pseudo)halides. The combination of palladium(0), Xantphos, and an amine base is essential to promote this broadly applicable catalytic reaction. Overall, this reaction provides access to a great variety of carbonyl-containing products through in situ transformation of the generated aroyl chloride. Combined experimental and computational studies support a reaction mechanism involving in situ generation of CO.
- Bismuto, Alessandro,Boehm, Philip,Morandi, Bill,Roediger, Sven
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supporting information
p. 17887 - 17896
(2020/08/19)
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- Synthesis of Some Aromatic and Aliphatic Esters Using WO3/ZrO2 Solid Acid Catalyst under Solvent Free Conditions
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A simple method is delineated for the synthesis of substituted ester products in superior yields by esterification reaction under solvent unbound condition using tungsten upgraded ZrO2 solid acid catalyst at 353 K. The WO3/ZrO2 catalyst has been prepared by using impregnation method followed by calcination at 923 K over a period of 6 h in air atmosphere. SEM, XRD, FTIR, and BET surface area techniques were used to categorize this catalyst. Zirconia has both acidic and basic possessions which can be changed by incorporating suitable promoter atom like tungsten which in turn increases the surface area thereby enhancing the surface acidity. Impregnation of W6+ ions exhibits a strong influence on phase modification of zirconia from thermodynamically solid monoclinic to metastable tetragonal phase. Amalgamation of promoter W6+ will stabilize tetragonal phase which is active in catalyzing reactions. In esterification reaction WO3/ZrO2 catalyst was found to be stable, efficient and environmental friendly, effortlessly recovered by filtration, excellent yield of product and can be reusable efficiently.
- Guguloth, Vijaya Charan,Battu, Satyanarayana
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p. 2153 - 2157
(2020/09/16)
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- Design, synthesis, and in vitro evaluation of novel 1,3,4-oxadiazolecarbamothioate derivatives of Rivastigmine as selective inhibitors of BuChE
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Rivastigmine has been prescribed for the therapy of Alzheimer’s disease (AD) symptoms. This drug is classified in the carbamate derivative group that has dual activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). According to the structure of Rivastigmine and its performance, a new series of 5-aryl-1,3,4-oxadiazole-2-carbamothioate compounds I–XI was synthesized using structure-based drug discovery approaches. For this purpose a set of these compounds were designed with computational docking method and their interactions with amino acid residues in the active sites of AChE and BuChE checked out. The structures of synthesized compounds were established by physicochemical and spectroscopic methods. The carbamoyl moiety of Rivastigmine structure was modified to carbamothioate and the effects of 1,3,4-oxadiazole heterocycle as a pharmacophoric nucleus were investigated. The potential of the synthesized compounds I–XI was evaluated against two most known agents of AD (AChE and BuChE) to determine their IC50 values. The results of the docking showed the range of binding affinity for the best poses of ten individual conformers for any compounds (I–XI) was between ?7.81 (VI) and ?6.75 (II) kcal/mol. The results of biological experiments displayed that most synthetic compounds (I–VIII) showed moderate to excellent selective activity range against BuChE (0.51–69.44 μM). In vitro cytotoxicity evaluation of these compounds (I–XI) by MTT assay on human dermal fibroblast (HDF) cell line exhibited no activity against HDF. The compound VI [S-(5-(p-tolyl)-1,3,4-oxadiazol-2-yl) ethyl(methyl)carbamothioate] showed the most stable binding affinity (?7.81 kcal/mol) and the lowest IC50 value (0.51 μM) in comparison with Rivastigmine with 7.72 μM and Donepezil with 5.20 μM against BuChE.
- Fallah, Akram,Mohanazadeh, Farajollah,Safavi, Maliheh
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p. 341 - 355
(2019/12/30)
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- Discovery of [1,2,4]triazole derivatives as new metallo-β-lactamase inhibitors
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The emergence and spread of metallo-β-lactamase (MBL)-mediated resistance to β-lactam antibacterials has already threatened the global public health. A clinically useful MBL inhibitor that can reverse β-lactam resistance has not been established yet. We here report a series of [1,2,4]triazole derivatives and analogs, which displayed inhibition to the clinically relevant subclass B1 (Verona integron-encoded MBL-2) VIM-2. 3-(4-Bromophenyl)-6,7-dihydro-5H-[1,2,4]triazolo [3,4-b][1,3]thiazine (5l) manifested the most potent inhibition with an IC50 (half-maximal inhibitory concentration) value of 38.36 μM. Investigations of 5l against other B1 MBLs and the serine β-lactamases (SBLs) revealed the selectivity to VIM-2. Molecular docking analyses suggested that 5l bound to the VIM-2 active site via the triazole involving zinc coordination and made hydrophobic interactions with the residues Phe61 and Tyr67 on the flexible L1 loop. This work provided new triazole-based MBL inhibitors and may aid efforts to develop new types of inhibitors combating MBL-mediated resistance.
- Yuan, Chen,Yan, Jie,Song, Chen,Yang, Fan,Li, Chao,Wang, Cheng,Su, Huiling,Chen, Wei,Wang, Lijiao,Wang, Zhouyu,Qian, Shan,Yang, Lingling
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- Discovery of carboxyl-containing biaryl ureas as potent RORγt inverse agonists
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GSK805 (1) is a potent RORγt inverse agonist, but a drawback of 1 is its low solubility, leading to a limited absorption in high doses. We have explored detailed structure-activity relationship on the amide linker, biaryl and arylsulfonyl moieties of 1 trying to improve solubility while maintaining RORγt activity. As a result, a novel series of carboxyl-containing biaryl urea derivatives was discovered as potent RORγt inverse agonists with improved drug-like properties. Compound 3i showed potent RORγt inhibitory activity and subtype selectivity with an IC50 of 63.8 nM in RORγ FRET assay and 85 nM in cell-based RORγ-GAL4 promotor reporter assay. Reasonable inhibitory activity of 3i was also achieved in mouse Th17 cell differentiation assay (76percent inhibition at 0.3 μM). Moreover, 3i had greatly improved aqueous solubility at pH 7.4 compared to 1, exhibited decent mouse PK profile and demonstrated some in vivo efficacy in an imiquimod-induced psoriasis mice model.
- Sun, Nannan,Huang, Yafei,Yu, Mingcheng,Zhao, Yunpeng,Chen, Ji-An,Zhu, Chenyu,Song, Meiqi,Guo, Huimin,Xie, Qiong,Wang, Yonghui
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- Modulation of estrogen-related receptors subtype selectivity: Conversion of an ERRβ/γ selective agonist to ERRα/β/γ pan agonists
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Estrogen Related Receptors (ERRs) are key regulators of energy homeostasis and play important role in the etiology of metabolic disorders, skeletal muscle related disorders, and neurodegenerative diseases. Among the three ERR isoforms, ERRα emerged as a potential drug target for metabolic and neurodegenerative diseases. Although ERRβ/γ selective agonist chemical tools have been identified, there are no chemical tools that effectively target ERRα agonism. We successfully engineered high affinity ERRα agonism into a chemical scaffold that displays selective ERRβ/γ agonist activity (GSK4716), providing novel ERRα/β/γ pan agonists that can be used as tools to probe the physiological roles of these nuclear receptors. We identified the structural requirements to enhance selectivity toward ERRα. Molecular modeling shows that our novel modulators have favorable binding modes in the LBP of ERRα and can induce conformational changes where Phe328 that originally occupies the pocket is dislocated to accommodate the ligands in a rather small cavity. The best agonists up-regulated the expression of target genes PGC-1α and PGC-1β, which are necessary to achieve maximal mitochondrial biogenesis. Moreover, they increased the mRNA levels of PDK4, which play an important role in energy homeostasis.
- Avdagic, Amer,Billon, Cyrielle,Burris, Sheryl L.,Burris, Thomas P.,Elagawany, Mohamed,Elgendy, Bahaa,Goher, Shaimaa S.,Hegazy, Lamees,Sanders, Ryan,Shahien, Mohamed,Sitaula, Sadichha
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- Exploring the physicochemical and antiproliferative properties of biaryl-linked [13]-macrodilactones
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A macrocyclic motif fosters productive protein-small molecule interactions. There are numerous examples of both natural product and designed, synthetic macrocycles that modulate the immune system, slow microbial infection, or kill eukaryotic cells. Reported here are the synthesis, physicochemical characterization, and antiproliferative activity of a group of [13]-macrodilactones decorated with a pendant biaryl moiety. Biaryl analogs were prepared by Suzuki reactions conducted on a common intermediate that contained a bromophenyl unit alpha to one of the carbonyls of the [13]-macrodilactone. Principal component analysis placed the new compounds in physicochemical context relative to a variety of pharmaceuticals and natural products. Modest inhibition of proliferation was observed in ASZ cells, a murine basal cell carcinoma line. This work underscores the value of an approach toward the identification of bioactive compounds that places the evaluation of physicochemical parameters early in the search process.
- Chen, Chengsheng,Bosko, Cristin,McGeough, Catherine P.,McLean, Ryan,Zaino, Angela M.,Kyle Hadden,Peczuh, Mark W.
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- Catalytic conversion of ketones to esters: Via C(O)-C bond cleavage under transition-metal free conditions
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The catalytic conversion of ketones to esters via C(O)-C bond cleavage under transition-metal free conditions is reported. This catalytic process proceeds under solvent-free conditions and offers an easy operational procedure, broad substrate scope with excellent selectivity, and reaction scalability. This journal is
- Subaramanian, Murugan,Ramar, Palmurukan M.,Rana, Jagannath,Gupta, Virendra Kumar,Balaraman, Ekambaram
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supporting information
p. 8143 - 8146
(2020/09/09)
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- Palladium-Catalyzed, Copper(I)-Promoted Methoxycarbonylation of Arylboronic Acids with O-Methyl S-Aryl Thiocarbonates
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Here, we report O-methyl S-aryl thiocarbonates as a versatile esterification reagent for palladium-catalyzed methoxycarbonylation of arylboronic acid in the presence of copper(I) thiophene-2-carboxylate (CuTC). The reaction condition is mild, and a variety of substituents including sensitive-Cl,-Br, and free-NH2 could be tolerated. Further applications in the late-stage esterification of some pharmaceutical drugs demonstrate the broad utility of this method.
- Cao, Ya-Fang,Li, Ling-Jun,Liu, Min,Xu, Hui,Dai, Hui-Xiong
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p. 4475 - 4481
(2020/04/10)
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- Visible-light-induced selective aerobic oxidation of sp3 C-H bonds catalyzed by a heterogeneous AgI/BiVO4 catalyst
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An efficient oxidation of sp3 C-H bonds to esters and ketones has been developed using AgI/BiVO4 as the photocatalyst and O2 as the oxidant in water. Various substrates can be transformed into the desired esters and ketones in moderate to good yields. The synthetic utility of this approach has been demonstrated by gram-level experiments and consecutive oxidation experiments. A plausible mechanism has been proposed.
- Jiang, Li-Ya,Ming, Jing-Jing,Wang, Lian-Yue,Jiang, Yuan-Yuan,Ren, Lan-Hui,Wang, Zi-Cheng,Cheng, Wen-Chen
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supporting information
p. 1156 - 1163
(2020/03/11)
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- Facile synthesis of a highly efficient Co/Cu@NC catalyst for base-free oxidation of alcohols to esters
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The direct oxidation of alcohols to esters is an environmentally benign and cost-effective organic synthetic strategy, but it is still a great challenge to discover an economic, highly active, and long-term stable catalyst for efficient transformation of alcohols to esters under milder conditions. Herein, we developed cobalt and copper nanoparticle -co-decorated nitrogen-doped carbon catalysts (CoCu@NCn) through two steps of ball milling and calcination. It was found that CoCu@NCn could catalyze the oxidation of alcohols to esters effectively in the absence of basic additives. The catalytic activity was much higher than those of monometallic Co@NC2 and Cu@NC2 samples, and the catalyst can be conveniently recovered and quite steadily reused. Through a series of control experiments and characterizations, it is concluded that the remarkable catalytic performance of CoCu@NC2 was associated with the synergistic effect between the two metal components, the enhanced basic active sites and the active surface area.
- Jiang, Jiusheng,Li, Xiang,Du, Shengyu,Shi, Langchen,Jiang, Pingping,Zhang, Pingbo,Dong, Yuming,Leng, Yan
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p. 7780 - 7785
(2020/06/09)
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- Aldehydes as potential acylating reagents for oxidative esterification by inorganic ligand-supported iron catalysis
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The oxidative esterification of various aldehydes with alcohols could be achieved by a heterogeneous iron(iii) catalyst supported on a ring-like POM inorganic ligand under mild conditions, affording the corresponding esters, including several drug molecules and natural products, in high yields. ESI-MS and control experiments demonstrated that POM-FeV(O) was the active catalytic species and the plausible mechanism was presented. More importantly, the 6th run of the iron catalyst recycles shows only a slight decrease in the yield.
- Yu, Han,Wang, Jingjing,Wu, Zhikang,Zhao, Qixin,Dan, Demin,Han, Sheng,Tang, Jiangjiang,Wei, Yongge
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supporting information
p. 4550 - 4554
(2019/08/21)
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- Dehydrogenative Coupling of Aldehydes with Alcohols Catalyzed by a Nickel Hydride Complex
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A nickel hydride complex, {2,6-(iPr2PO)2C6H3}NiH, has been shown to catalyze the coupling of RCHO and R′OH to yield RCO2R′ and RCH2OH, where the aldehyde also acts as a hydrogen acceptor and the alcohol also serves as the solvent. Functional groups tolerated by this catalytic system include CF3, NO2, Cl, Br, NHCOMe, and NMe2, whereas phenol-containing compounds are not viable substrates or solvents. The dehydrogenative coupling reaction can alternatively be catalyzed by an air-stable nickel chloride complex, {2,6-(iPr2PO)2C6H3}NiCl, in conjunction with NaOMe. Acids in unpurified aldehydes react with the hydride to form nickel carboxylate complexes, which are catalytically inactive. Water, if present in a significant quantity, decreases the catalytic efficiency by forming {2,6-(iPr2PO)2C6H3}NiOH, which causes catalyst degradation. On the other hand, in the presence of a drying agent, {2,6-(iPr2PO)2C6H3}NiOH generated in situ from {2,6-(iPr2PO)2C6H3}NiCl and NaOH can be converted to an alkoxide species, becoming catalytically competent. The proposed catalytic mechanism features aldehyde insertion into the nickel hydride as well as into a nickel alkoxide intermediate, both of which have been experimentally observed. Several mechanistically relevant nickel species including {2,6-(iPr2PO)2C6H3}NiOC(O)Ph, {2,6-(iPr2PO)2C6H3}NiOPh, and {2,6-(iPr2PO)2C6H3}NiOPh·HOPh have been independently synthesized, crystallographically characterized, and tested for the catalytic reaction. While phenol-containing molecules cannot be used as substrates or solvents, both {2,6-(iPr2PO)2C6H3}NiOPh and {2,6-(iPr2PO)2C6H3}NiOPh·HOPh are efficient in catalyzing the dehydrogenative coupling of PhCHO with EtOH.
- Eberhardt, Nathan A.,Wellala, Nadeesha P. N.,Li, Yingze,Krause, Jeanette A.,Guan, Hairong
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p. 1468 - 1478
(2019/04/17)
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- Analyzing the Relation between Structure and Aggregation Induced Emission (AIE) Properties of Iridium(III) Complexes through Modification of Non-Chromophoric Ancillary Ligands
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Unconventionally modified dibenzoylmethane (dbm) ligands have been synthesized and successfully utilized as ancillary ligands for neutral iridium(III) complexes of the formula [Ir(dFppy)2(LX)], where dFppyH is 2-(2,4-difluorophenyl)pyridine and LX is tribenzoylmethane (tbm) or 1-phenyl-3-(4-(pyridin-2-yl)phenyl)propane-1,3-dione (pydbm). The modification of the ligands aims to prevent or enhance possible intermolecular interactions between the dFppy and/or the LX moiety in comparison with the previously reported [Ir(dFppy)2(dbm)] complex. The aggregation induced emission (AIE) properties of these complexes are significantly modulated, as a consequence of the different π–π interactions revealed by X-ray crystallography.
- Galán, Laura Abad,Cordes, David B.,Slawin, Alexandra M. Z.,Jacquemin, Denis,Ogden, Mark I.,Massi, Massimiliano,Zysman-Colman, Eli
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p. 152 - 163
(2018/11/23)
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- Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
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The presence of different aldehydes is found to have a significant influence on the catalytic performance when using PN(H)P type ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted the observed high chemoselectivity.
- Jiang, Xiaolin,Zhang, Jiahui,Zhao, Dongmei,Li, Yuehui
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p. 2797 - 2800
(2019/03/27)
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- Dehydrogenative cross-coupling of primary alcohols to form cross-esters catalyzed by a manganese pincer complex
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Base-metal-catalyzed dehydrogenative cross-coupling of primary alcohols to form cross-esters as major products, liberating hydrogen gas, is reported. The reaction is catalyzed by a pincer complex of earth-abundant manganese in the presence of catalytic base, without any hydrogen acceptor or oxidant. Mechanistic insight indicates that a dearomatized complex is the actual catalyst, and indeed this independently prepared dearomatized complex catalyzes the reaction under neutral conditions.
- Das, Uttam Kumar,Ben-David, Yehoshoa,Leitus, Gregory,Diskin-Posner, Yael,Milstein, David
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p. 479 - 484
(2019/01/11)
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- Method for preparing carboxylic ester by alcohol direct oxidation esterification method
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The invention discloses a method for preparing a carboxylic ester by an alcohol direct oxidation esterification method. The method comprises the following steps: taking an aromatic alcohol compound ora saturated linear aliphatic alcohol as a reaction substrate, taking an Au-Co composite particle carrier as a catalyst, adding a low catalytic amount of alkali, reacting for 0.5-15 h in a methanol solvent at the temperature of 25-150 DEG C in air or oxygen or a mixed atmosphere of the air or the oxygen, and performing aftertreatment to obtain a target product carboxylic ester. According to the preparation method disclosed by the invention, the process steps are reduced, conditions are mild, catalyst consumption is less, atom economy is high, the method is simple to operate, the application range of the substrate is wide, and industrial practicability is achieved.
- -
-
Paragraph 0060; 0061
(2019/06/30)
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- Pd-Colloids-Catalyzed/Ag2O-Oxidized General and Selective Esterification of Benzylic Alcohols
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Palladium colloids obtained from the degradation of Hermann–Beller palladacycle proved to be an efficient catalytic system in combination with silver oxide as a selective oxidant for the oxidative esterification of differently substituted benzyl alcohols in MeOH as solvent. Excellent reactivity exhibited by the catalytic system also allowed the alcoholic coupling partner to be changed from MeOH to a wide range of alcohols having diverse functionalities. The mildness of the developed protocol also made it possible to employ propargyl alcohol as the coupling partner without any observation of any interference of the terminal alkyne. Selective oxidative coupling of a primary alcoholic functional group over secondary in the case of glycols and glycerols was also made possible using the developed catalyst system. To test the relevancy of Pd/Ag combined catalysis mixed Pd/Ag colloids were synthesized, characterized by TEM, XRD and XPS and applied to oxidative-esterification successfully.
- Sable, Vaibhav,Shah, Jagrut,Sharma, Anuja,Kapdi, Anant R.
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supporting information
p. 2639 - 2647
(2019/07/08)
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- METHOD FOR THE SYNTHESIS AND PURIFICATION OF ARYL ACID ESTERS
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The general inventive concepts are directed to the discovery that certain aryl acids can be esterified under particular conditions to provide the resulting ester as a solid that precipitates in good yield from the reaction mixture. The esters may then be isolated and purified with relative ease. Accordingly, a method for the esterification, isolation, and purification of aryl acids is provided.
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Paragraph 0028
(2019/10/17)
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- Development of novel liver?X?receptor modulators based on a 1,2,4-triazole scaffold
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Liver X Receptor (LXR) agonists have been reported as a potential treatment for atherosclerosis, Alzheimer's disease and hepatitis C virus (HCV) infection. We have designed and synthesized a series of potent compounds based on a 1,2,4-triazole scaffold as novel LXR modulators. In cell-based cotransfection assays these compounds generally functioned as LXR agonists and we observed compounds with selectivity towards LXRα (7-fold) and LXRβ (7-fold) in terms of potency. Assessment of the effects of selected compounds on LXR target gene expression in HepG2 cells revealed that compounds 6a-b and 8a-b behaved as inverse agonists on FASN expression even though they were agonists in the LXRα and LXRβ cotransfection assays. Interestingly, these compounds had no effect on the expression of SREBP-1c confirming a unique LXR modulator pharmacology. Molecular docking studies and evaluation of ADME properties in-silico show that active compounds possess favorable binding modes and ADME profiles. Thus, these compounds may be useful for in vivo characterization of LXR modulators with unique profiles and determination of their potential clinical utility.
- Goher, Shaimaa S.,Griffett, Kristine,Hegazy, Lamees,Elagawany, Mohamed,Arief, Mohamed M.H.,Avdagic, Amer,Banerjee, Subhashis,Burris, Thomas P.,Elgendy, Bahaa
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supporting information
p. 449 - 453
(2019/01/04)
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- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
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Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
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p. 3931 - 3943
(2018/09/11)
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- Phosphite-catalyzed alkoxycarbonylation of aryl diazonium salts
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In this communication, an interesting phosphite-catalyzed alkoxycarbonylation of aryl diazonium salts has been reported. At room temperature and under CO pressure, moderate to good yields of the desired esters can be produced in the absence of bases or an
- Xu, Jian-Xing,Franke, Robert,Wu, Xiao-Feng
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supporting information
p. 6180 - 6182
(2018/09/10)
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- Methylation of Aliphatic and Aromatic Carboxylic Acids with Dimethyl Carbonate under the Influence of Manganese and Iron Carbonyls
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The synthesis of methyl esters has been carried out via the reaction of aliphatic and aromatic carboxylic acids with dimethyl carbonate in the presence of manganese and iron carbonyls. The optimal ratio of catalyst and reagents and other conditions for the synthesis of methyl esters of carboxylic acids with high yield have been found.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.
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- Superior performance of Co-N/m-C for direct oxidation of alcohols to esters under air
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A convenient, expeditious, and high-efficiency protocol for the transformation of alcohols into esters using a Co-modified N-doped mesoporous carbon material (Co-N/m-C) as the catalyst is proposed. The catalyst was prepared through direct pyrolysis of a macromolecular precursor. The catalyst prepared using a pyrolysis temperature of 900 °C (labeled Co-N/m-C-900) exhibited the best performance. The strong coordination between the ultra-dispersed cobalt species and the pyridine nitrogen as well as the large area of the mesoporous surface resulted in a high turnover frequency value (107.6 mol methyl benzoate mol?1 Co h?1) for the direct aerobic oxidation of benzyl alcohol to methyl benzoate. This value is much higher than those of state-of-the-art transition-metal-based nanocatalysts reported in the literature. Moreover, the catalyst exhibited general applicability to various structurally diverse alcohols, including benzylic, allylic, and heterocyclic alcohols, achieving the target esters in high yields. In addition, a preliminary evaluation revealed that Co-N/m-C-900 can be used six times without significant activity loss. In general, the process was rapid, simple, and cost-effective.
- Li, Ning,Shang, Sensen,Wang, Lianyue,Niu, Jingyang,Lv, Ying,Gao, Shuang
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p. 1249 - 1257
(2018/06/14)
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- Development of N-Doped Carbon-Supported Cobalt/Copper Bimetallic Nanoparticle Catalysts for Aerobic Oxidative Esterifications Based on Polymer Incarceration Methods
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Heterogeneous nitrogen-doped carbon-incarcerated cobalt/copper bimetallic nanoparticle (NP) catalysts, prepared from nitrogen-containing polymers, were developed, and an efficient catalytic process for aerobic oxidative esterification was achieved in the presence of a low loading (1 mol %) of catalyst that could be reused and easily reactivated. This protocol enabled diverse conditions for the bimetallic NP formation step to be screened, and significant rate acceleration by inclusion of a copper dopant was discovered. The catalytic activity of the bimetallic Co/Cu catalysts is much higher than that for cobalt catalysts reported to date and is even comparable with noble-metal NP catalysts.
- Yasukawa, Tomohiro,Yang, Xi,Kobayashi, Shu
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supporting information
p. 5172 - 5176
(2018/09/12)
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- Cobalt-entrenched N-, O-, and S-tridoped carbons as efficient multifunctional sustainable catalysts for base-free selective oxidative esterification of alcohols
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We report the synthesis of sustainable and reusable non-noble transition-metal (cobalt) nanocatalysts containing N-, O-, and S-tridoped carbon nanotube (Co@NOSC) composites. The expensive and benign carrageenan served as the source of carbon, oxygen, and sulfur, whereas urea served as the nitrogen source. The material was prepared via direct mixing of precursors and freeze-drying followed by carbonization under nitrogen at 900 °C. Co@NOSC catalysts comprising a Co inner core and outer electron-rich heteroatom-doped carbon shell were thoroughly characterized using various techniques, namely, TEM, HRTEM, STEM elemental mapping, XPS, BET, and ICP-MS. The utility of the Co@NOSC catalyst was explored for base-free selective oxidative esterification of alcohols to the corresponding esters under mild reaction conditions; excellent conversions (up to 97%) and selectivities (up to 99%) were discerned. Furthermore, the substrate scope was explored for the cross-esterification of benzyl alcohol with long-chain alcohols (up to 98%) and lactonization of diols (up to 68%). The heterogeneous nature and stability of the catalyst facilitated by its ease of separation for long-term performance and recycling studies showed that the catalyst was robust and remained active even after six recycling experiments. EPR measurements were performed to deduce the reaction mechanism in the presence of POBN (α-(4-pyridyl-1-oxide)-N-tert-butylnitrone) as a spin-trapping agent, which confirmed the formation of CH2OH radicals and H radicals, wherein the solvent plays an active role in a nonconventional manner. A plausible mechanism was proposed for the oxidative esterification of alcohols on the basis of EPR findings. The presence of a cobalt core along with cobalt oxide and the electron-rich N-, O-, and S-doped carbon shell displayed synergistic effects to afford good to excellent yields of products.
- Nandan, Devaki,Zoppellaro, Giorgio,Med?ík, Ivo,Aparicio, Claudia,Kumar, Pawan,Petr, Martin,Tomanec, Ond?ej,Gawande, Manoj B.,Varma, Rajender S.,Zbo?il, Radek
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p. 3542 - 3556
(2018/08/07)
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- Microwave assisted synthesis and evaluation of some substituted 1,3,4-oxadiazoles as free radical scavenger
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A series of 5-(4-substituted phenyl)-1,3,4-oxadiazoles (4a-h) were prepared from 4-substituted benzoic acid hydrazides (3a-h). Structures of the synthesized compounds were confirmed on the basis of IR, 13C NMR, Mass spectral methods and elemental analysis. The compounds were screened for antioxidant activities using hydrogen peroxide scavenging method comparing with ascorbic acid as standard antioxidant. The results reveal that the compounds possess significant free radical scavenging activities. It is recommended that these compounds might be used in future to generate derivatives for emerging free radical scavenger.
- Upadhyay, Prabhat Kumar,Mishra, Pradeep
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p. 661 - 666
(2020/07/02)
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- Efficient synthesis of esters through oxone-catalyzed dehydrogenation of carboxylic acids and alcohols
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Since esters are important organic synthesis intermediates, an environmentally friendly oxone catalyzed-esterification of carboxylic acids with alcohols has been developed. A series of carboxylic acid esters are obtained in high yield. This strategy requires mild reaction conditions, providing an attractive alternative for the construction of valuable carbonyl esters. Electron-rich and electron-deficient groups are compatible with the standard conditions and a variety of substrates are demonstrated. Moreover, the reaction could easily be adapted to typical prodrugs, drugs and gram-scale synthesis.
- Hou, Fei,Wang, Xi-Cun,Quan, Zheng-Jun
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supporting information
p. 9472 - 9476
(2019/01/03)
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