- Exceedingly Efficient Synthesis of (±)-Grandifloracin and Acylated Analogues
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A highly efficient regio- and stereoselective total synthesis of (±)-grandifloracin via a tandem dearomative epoxidation/spontaneous Diels-Alder cyclodimerization from salicylic acid in only four steps is reported. The synthetic route allows for late-stage diversification of the core structure to give ready access to analogues of this promising agent against pancreatic cancer.
- Bergner, Magnus,Duquette, Douglas C.,Chio, Linda,Stoltz, Brian M.
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- Reaction of cresyl saligenin phosphate, the organophosphorus agent implicated in aerotoxic syndrome, with human cholinesterases: Mechanistic studies employing kinetics, mass spectrometry, and X-ray structure analysis
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Aerotoxic syndrome is assumed to be caused by exposure to tricresyl phosphate (TCP), an antiwear additive in jet engine lubricants and hydraulic fluid. CBDP (2-(ortho-cresyl)-4H-1,2,3-benzodioxaphosphoran-2-one) is the toxic metabolite of triortho-cresylphosphate, a component of TCP. Human butyrylcholinesterase (BChE; EC 3.1.1.8) and human acetylcholinesterase (AChE; EC 3.1.1.7) are irreversibly inhibited by CBDP. The bimolecular rate constants of inhibition (ki), determined under pseudo-first-order conditions, displayed a biphasic time course of inhibition with ki of 1.6 ×108 M-1 min-1 and 2.7 ×10 7 M-1 min-1 for E and E′ forms of BChE. The inhibition constants for AChE were 1 to 2 orders of magnitude slower than those for BChE. CBDP-phosphorylated cholinesterases are nonreactivatable due to ultra fast aging. Mass spectrometry analysis showed an initial BChE adduct with an added mass of 170 Da from cresylphosphate, followed by dealkylation to a structure with an added mass of 80 Da. Mass spectrometry in 18O-water showed that 18O was incorporated only during the final aging step to form phospho-serine as the final aged BChE adduct. The crystal structure of CBDP-inhibited BChE confirmed that the phosphate adduct is the ultimate aging product. CBDP is the first organophosphorus agent that leads to a fully dealkylated phospho-serine BChE adduct.
- Carletti, Eugenie,Schopfer, Lawrence M.,Colletier, Jacques-Philippe,Froment, Marie-Therese,Nachon, Florian,Weik, Martin,Lockridge, Oksana,Masson, Patrick
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- Zirconium and hafnium polyhedral oligosilsesquioxane complexes-green homogeneous catalysts in the formation of bio-derived ethers: Via a MPV/etherification reaction cascade
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The polyhedral oligosilsesquioxane complexes, {[(isobutyl)7Si7O12]ZrOPri·(HOPri)}2 (I), {[(cyclohexyl)7Si7O12]ZrOPri·(HOPri)}2 (II), {[(isobutyl)7Si7O12]HfOPri·(HOPri)}2 (III) and {[(cyclohexyl)7Si7O12]HfOPri·(HOPri)}2 (IV), were synthesized in good yields from the reactions of M(OPri)4 (M = Zr, Hf) with R-POSS(OH)3 (R = isobutyl, cyclohexyl), resp. I-IV were characterized by 1H, 13C and 29Si NMR spectroscopy and their dimeric solid-state structures were confirmed by X-ray analysis. I-IV catalyze the reductive etherification of 2-hydroxy- and 4-hydroxy and 2-methoxy and 4-methoxybenzaldehyde and vanillin to their respective isopropyl ethers in isopropanol as a "green"solvent and reagent. I-IV are durable and robust homogeneous catalysts operating at temperatures of 100-160 °C for days without significant loss of catalytic activity. Likewise, I-IV selectively catalyze the conversion of 5-hydroxymethylfurfural (HMF) into 2,5-bis(isopropoxymethyl)furane (BPMF), a potentially high-performance fuel additive. Similar results were achieved by using a combination of M(OPri)4 and ligand R-POSS(OH)3 as a catalyst system demonstrating the potential of this "in situ"approach for applications in biomass transformations. A tentative reaction mechanism for the reductive etherification of aldehydes catalysed by I-IV is proposed. This journal is
- Garg, Shipra,Unruh, Daniel K.,Krempner, Clemens
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p. 211 - 218
(2021/01/28)
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- A PROCESS FOR SELECTIVE OXIDATION OF ORTHO-CRESOL AND CATALYST THEREOF
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The present invention relates to process for selective oxidation of o-cresol using heterogeneous catalyst. More particularly, the present invention relates to a selectively salicylaldehyde by oxidation of o-cresol, comprising steps of treating o-cresol with heterogeneous catalyst consisting of 3-7 % cobalt doped octahedral molecular sieves (OMS-2) support having Surface area between 80- 140 m2/g and pore size between 5 to 20 nm, the treatment is in presence of methanol and molecular oxygen at temperature between 60-85°C and pressure between 3 to 5 atm for time between 1 to 2 h. The process of present invention is to achieve high yield and conversion at mild reaction conditions.
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Page/Page column 10
(2021/02/12)
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- PNO ligand containing planar chiral ferrocene and application thereof
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The invention discloses a PNO ligand containing planar chiral ferrocene and application thereof. The PNO ligand containing planar chiral ferrocene is a planar chiral ferrocene-containing and phenol-containing PNO ligand as shown in a general formula (I) or (II) which is described in the specification, or a planar chiral ferrocene-containing and aryl-phosphoric-acid-containingPNO ligand containing as shown in a general formula (III) or (IV) which is described in the specification, or a planar chiral ferrocene-containing and carbon-chiral-phenol-containingPNO ligand as shown in a general formula (V) or (VI) which is described in the specification. The invention provides tridentate PNO ligands and processes for their complexation with transition metal salts or transition metal complexes; the introduction of salicylaldehyde and derivatives thereof, which are simple and easy to obtain, enables the ligands to have a bifunctionalization effect, and -OH in a formed catalyst has stronger acidity and is beneficial to combination with N/O in polar double bonds. Therefore, due to the bifunctionalization effect of the catalyst, the interaction between the catalyst and a substrate can be greatly improved, so a reaction can obtain higher catalytic activity and stereoselectivity.
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Paragraph 0114-0118
(2021/06/21)
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- Hydroboration Reaction and Mechanism of Carboxylic Acids using NaNH2(BH3)2, a Hydroboration Reagent with Reducing Capability between NaBH4and LiAlH4
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Hydroboration reactions of carboxylic acids using sodium aminodiboranate (NaNH2[BH3]2, NaADBH) to form primary alcohols were systematically investigated, and the reduction mechanism was elucidated experimentally and computationally. The transfer of hydride ions from B atoms to C atoms, the key step in the mechanism, was theoretically illustrated and supported by experimental results. The intermediates of NH2B2H5, PhCH= CHCOOBH2NH2BH3-, PhCH= CHCH2OBO, and the byproducts of BH4-, NH2BH2, and NH2BH3- were identified and characterized by 11B and 1H NMR. The reducing capacity of NaADBH was found between that of NaBH4 and LiAlH4. We have thus found that NaADBH is a promising reducing agent for hydroboration because of its stability and easy handling. These reactions exhibit excellent yields and good selectivity, therefore providing alternative synthetic approaches for the conversion of carboxylic acids to primary alcohols with a wide range of functional group tolerance.
- Wang, Jin,Ju, Ming-Yue,Wang, Xinghua,Ma, Yan-Na,Wei, Donghui,Chen, Xuenian
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p. 5305 - 5316
(2021/04/12)
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- Homoleptic cobalt(II) phenoxyimine complexes for hydrosilylation of aldehydes and ketones without base activation of cobalt(II)
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Air-stable, easy to prepare, homoleptic cobalt(II) complexes bearing pendant-modified phenoxyimine ligands were synthesized and determined. The complexes exhibited high catalytic performance for reducing aldehydes and ketones via catalytic hydrosilylation, where a hydrosilane and a catalytic amount of the cobalt(II) complex were added under base-free conditions. The reaction proceeded even in the presence of excess water, and excellent functional-group tolerance was observed. Subsequent hydrolysis gave the alcohol in high yields. Moreover, H2O had a critical role in activation of the Co(II) catalyst with hydrosilane. Several additional results also indicated that the cobalt(II) center acts as an active catalyst in the hydrosilylation of aldehydes and ketones.
- Hori, Momoko,Ishikawa, Ryuta,Koga, Yuji,Matsubara, Kouki,Mitsuyama, Tomoaki,Shin, Sayaka
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p. 1379 - 1387
(2021/05/29)
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- KB3H8: An environment-friendly reagent for the selective reduction of aldehydes and ketones to alcohols
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Selective reduction of aldehydes and ketones to their corresponding alcohols with KB3H8, an air- and moisture-stable, nontoxic, and easy-to-handle reagent, in water and THF has been explored under an air atmosphere for the first time. Control experiments illustrated the good selectivity of KB3H8 over NaBH4 for the reduction of 4-acetylbenzaldehyde and aromatic keto esters. This journal is
- Li, Xinying,Mi, Tongge,Guo, Wenjing,Ruan, Zhongrui,Guo, Yu,Ma, Yan-Na,Chen, Xuenian
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supporting information
p. 12776 - 12779
(2021/12/10)
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- Construction of diverse peptide structural architectures: Via chemoselective peptide ligation
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Herein, we report the development of a facile synthetic strategy for constructing diverse peptide structural architectures via chemoselective peptide ligation. The key advancement involved is to utilize the benzofuran moiety as the peptide salicylaldehyde ester surrogate, and Dap-Ser/Lys-Ser dipeptide as the hydroxyl amino functionality, which could be successfully introduced at the side chain of peptides enabling peptide ligation. With this method, the side chain-to-side chain cyclic peptide, branched/bridged peptides, tailed cyclic peptides and multi-cyclic peptides have been designed and successfully synthesized with native peptidic linkages at the ligation sites. This strategy has provided an alternative strategic opportunity for synthetic peptide development. It also serves as an inspiration for the structural design of PPI inhibitors with new modalities. This journal is
- Bierer, Donald,Cheung, Carina Hey Pui,Huang, Xuhui,Lee, Chi Lung,Li, Xuechen,Wei, Ruohan,Xu, Jianchao,Zhang, Yanfeng
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p. 7091 - 7097
(2021/06/02)
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- Reduction of carbonyl compounds via hydrosilylation catalyzed by well-defined PNP-Mn(I) hydride complexes
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Reduction reactions of unsaturated compounds are fundamental transformations in synthetic chemistry. In this context, the reduction of polarized double bonds such as carbonyl or C=C motifs can be achieved by hydrogenation reactions. We describe here a highly chemoselective Mn(I)-based PNP pincer catalyst for the hydrosilylation of aldehydes and ketones employing polymethylhydrosiloxane (PMHS) as inexpensive hydrogen donor. Graphic abstract: [Figure not available: see fulltext.]
- Weber, Stefan,Iebed, Dina,Glatz, Mathias,Kirchner, Karl
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p. 635 - 639
(2021/06/17)
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- Mechanically Strong Heterogeneous Catalysts via Immobilization of Powderous Catalysts to Porous Plastic Tablets
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Main observation and conclusion: We describe a practical and general protocol for immobilization of heterogeneous catalysts to mechanically robust porous ultra-high molecular weight polyethylene tablets using inter-facial Lifshitz-van der Waals Interactions. Diverse types of powderous catalysts, including Cu, Pd/C, Pd/Al2O3, Pt/C, and Rh/C have been immobilized successfully. The immobilized catalysts are mechanistically robust towards stirring in solutions, and they worked well in diverse synthetic reactions. The immobilized catalyst tablets are easy to handle and reused. Moreover, the metal leaching of immobilized catalysts was reduced significantly.
- Li, Tingting,Xu, Bo
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supporting information
p. 2673 - 2678
(2021/08/03)
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- A Water/Toluene Biphasic Medium Improves Yields and Deuterium Incorporation into Alcohols in the Transfer Hydrogenation of Aldehydes
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Deuterium labeling is an interesting process that leads to compounds of use in different fields. We describe the transfer hydrogenation of aldehydes and the selective C1 deuteration of the obtained alcohols in D2O, as the only deuterium source. Different aromatic, alkylic and α,β-unsaturated aldehydes were reduced in the presence of [RuCl(p-cymene)(dmbpy)]BF4, (dmbpy=4,4′-dimethyl-2,2′-bipyridine) as the pre-catalyst and HCO2Na/HCO2H as the hydrogen source. Moreover, furfural and glucose, were selectively reduced to the valuable alcohols, furfuryl alcohol and sorbitol. The processes were carried out in neat water or in a biphasic water/toluene system. The biphasic system allowed easy recycling, higher yields, and higher selective D incorporation (using D2O/toluene). The deuteration took place due to an efficient effective M–H/D+ exchange from D2O that allows the inversion of polarity of D+ (umpolung). DFT calculations that explain the catalytic behavior in water are also included.
- Ruiz-Casta?eda, Margarita,Santos, Lucía,Manzano, Blanca R.,Espino, Gustavo,Jalón, Félix A.
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supporting information
p. 1358 - 1372
(2021/03/16)
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- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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- Synthesis and in vitro study of nitro- and methoxy-2-phenylbenzofurans as human monoamine oxidase inhibitors
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A new series of 2-phenylbenzofuran derivatives were designed and synthesized to determine relevant structural features for the MAO inhibitory activity and selectivity. Methoxy substituents were introduced in the 2-phenyl ring, whereas the benzofuran moiety was not substituted or substituted at the positions 5 or 7 with a nitro group. Substitution patterns on both the phenyl ring and the benzofuran moiety determine the affinity for MAO-A or MAO-B. The 2-(3-methoxyphenyl)-5-nitrobenzofuran 9 was the most potent MAO-B inhibitor (IC50 = 0.024 μM) identified in this series, whereas 7-nitro-2-phenylbenzofuran 7 was the most potent MAO-A inhibitor (IC50 = 0.168 μM), both acting as reversible inhibitors. The number and position of the methoxyl groups on the 2-phenyl ring, have an important influence on the inhibitory activity. Molecular docking studies confirmed the experimental results and highlighted the importance of key residues in enzyme inhibition.
- Delogu, Giovanna L.,Kumar, Amit,Gatto, Gianluca,Bustelo, Fernando,Saavedra, Lucía M.,Rodríguez-Franco, Maria Isabel,Laguna, Reyes,Vi?a, Dolores
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- Synthesis, inhibition properties against xanthine oxidase and molecular docking studies of dimethyl N-benzyl-1H-1,2,3-triazole-4,5-dicarboxylate and (N-benzyl-1H-1,2,3-triazole-4,5-diyl)dimethanol derivatives
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This study focused on synthesis various dimethyl N-benzyl-1H-1,2,3-triazole-4,5-dicarboxylate and (N-benzyl-1H-1,2,3-triazole-4,5-diyl)dimethanol derivatives under the conditions of green chemistry without the use of solvent and catalysts. Their inhibition properties were also investigated on xanthine oxidase (XO) activity. All dimethanol and dicarboxylate derivatives exhibited significant inhibition activities with IC50 values ranging from 0.71 to 2.25 μM. Especially, (1-(3-bromobenzyl)-1H-1,2,3-triazole-4,5-diyl)dimethanol (5c) and dimethyl 1-(4-chlorobenzyl)-1H-1,2,3-triazole-4,5-dicarboxylate (6 g) compounds were found to be the most promising derivatives on the XO enzyme inhibition with IC50 values 0.71 and 0.73 μM, respectively. Moreover, the double docking procedure was to evaluate compound modes of inhibition and their interactions with the protein (XO) at atomic level. Surprisingly, the docking results showed a good correlation with IC50 [correlation coefficient (R2 = 0.7455)]. Also, the docking results exhibited that the 5c, 6f and 6 g have lowest docking scores ?4.790, ?4.755, and ?4.730, respectively. These data were in agreement with the IC50 values. These results give promising beginning stages to assist in the improvement of novel and powerful inhibitor against XO.
- Yagiz, Güler,Noma, Samir Abbas Ali,Altundas, Aliye,Al-khafaji, Khattab,Taskin-Tok, Tugba,Ates, Burhan
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- α-D-Mannoside ligands with a valency ranging from one to three: Synthesis and hemagglutination inhibitory properties
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Six mono-, di-, and trivalent α-D-mannopyranosyl conjugates built on aromatic scaffolds were synthesized in excellent yields by Cu(I) catalyzed azide-alkyne cycloaddition reaction (CuAAC). These conjugates were designed to have unique, flexible tails that combine a mid-tail triazole ring, to interact with the tyrosine gate, with a terminal phenyl group armed with benzylic hydroxyl groups to avoid solubility problems as well as to provide options to connect to other supports. Biological evaluation of the prepared conjugates in hemagglutination inhibition (HAI) assay revealed that potency increases with valency and the trivalent ligand 6d (HAI = 0.005 mM) is approximately sevenfold better than the best meta-oriented monovalent analogues 2d and 4d (HAI ≈ 0.033 mM) and so may serve as a good starting point to find new lead ligands.
- Al-Mughaid, Hussein,Khazaaleh, Maha
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- The development of a Cu(I)/pyrazolylpyridineamine catalyst system for the hydroxylation of aryl halides
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A catalyst system comprising of pyrazolylpyridineamine/Cu(I)/CsOH is reported. for the hydroxylation of aryl iodides and bromides with moderate to outstanding yields, without the use of an inert atmosphere. A comprehensive parameter optimisation study established optimum component concentrations: [Cu(MeCN)4]BF4 and 2-(1H-pyrazol-1-yl)-N-(pyridine-2-ylmethyl)ethan-1-amine (L01) (2 mol %), substrate (1 mmol), CsOH (4 mmol) and DMSO:H2O (1:1, 3 mL). Monitoring substrate conversion as a function of time revealed an induction period of 90 min, which could be eliminated through the initial in situ formation of the proposed [(L01)Cu-OH] intermediate. Eliminating the induction period resulted in complete conversion within one hour, with turnover numbers exceeding that of the benchmark catalyst system operating at an optimal catalyst loading of 0.05 mol %.
- Marais, Lindie,Vosloo, Hermanus C.M.,Swarts, Andrew J.
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- Synthesis of salicylaldehyde through oxidation of o-cresol: Evaluation of activity and selectivity of different metals supported on OMS-2 nanorods and kinetics
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Octahedral molecular sieve (OMS-2) was synthesized by the hydrothermal method and modified by the impregnation of different metals to give M/OMS-2 catalysts (where M = V, Cr, Fe, Co, and Mo). All these catalysts were tested in the oxidation of o-cresol to 2-hydroxybenzaldehyde (or salicylaldehyde, SAL). Among all M/OMS-2 catalysts, 5% Co/OMS-2 was found to be the most active catalyst for selective oxidation of o-cresol to SAL. Effect of several oxygen sources such as air, hydrogen peroxide (H2O2), molecular oxygen (O2), and tert-butyl hydroperoxide (TBHP) was studied for the oxidation of o-cresol. There was a complete conversion of o-cresol with 98% yield of SAL at 5 atm O2 pressure and 80 °C in 2 h. Additionally, the catalysts (virgin as well as reused forms) were characterized by FESEM, EDS, HR-TEM, XRD, CO2-TPD, TPR, Raman Spectra, BET surface area analysis, XPS, and DSC-TGA. The reaction kinetic model was developed using Mars van Krevelen mechanism. The catalyst was found to be inexpensive, robust, active, and showed very good reusability of 4 cycles, which makes it an attractive choice for o-cresol oxidation to SAL. The atom economy of the oxidation process is 98.15%. Thus, this process is an example of the synthesis of a vital chemical entity, salicylaldehyde, at mild reaction condition by a novel clean and green route.
- Pisal, Devendra S.,Yadav, Ganapati D.
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- Zinc-mediated reactions on salicylaldehyde for Botrytis cinerea control
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Botrytis cinerea is a necrotrophic fungus that affects various plant species. Chemical control is a necessity and as much as possible, eco-friendly conditions and bioresources to obtain these chemicals should be used. In this context, a series of products was obtained from salicylaldehyde using zinc as a powerful reagent and tested for antifungal activity against Botrytis cinerea
- Franche, Antoine,Imbs, Claire,Fayeulle, Antoine,Merlier, Franck,Billamboz, Muriel,Léonard, Estelle
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p. 706 - 710
(2019/09/13)
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- Carbon isotope labeling of carbamates by late-stage [11C], [13C] and [14C]carbon dioxide incorporation
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A general procedure for the late-stage [11C], [13C] and [14C]carbon isotope labeling of cyclic carbamates is reported. This protocol allows the incorporation of carbon dioxide, the primary source of carbon-14 and carbon-11 radioisotopes, in a direct, cost-effective and sustainable manner. A disconnection/reconnection strategy, involving ring opening/isotopic closure, was also implemented.
- Del Vecchio, Antonio,Talbot, Alex,Caillé, Fabien,Chevalier, Arnaud,Sallustrau, Antoine,Loreau, Olivier,Destro, Gianluca,Taran, Frédéric,Audisio, Davide
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supporting information
p. 11677 - 11680
(2020/10/19)
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- Boosting multiple photo-assisted and temperature controlled reactions with a single redox-switchable catalyst: Solvents as internal substrates and reducing agent
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An alternative and economically viable process for the synthesis of β-aryl enals, enones and the aryl amines has been developed by partial oxidation of ethanol, isopropanol and N, N-dimethyl formamide (DMF). The formation of β-aryl enals, enones and the aryl amines was catalyzed by a mixed metal oxides layer of cobalt and chromium supported on halloysite nanotubes, designated as CoCr2O4-HNT. The C[sbnd]C and C[sbnd]N bond formation reactions were found to be influenced by temperature and the nature of base. The condensation of aldehyde with in situ generated acetaldehyde by ethanol oxidation forming β-aryl enals occurred selectively at 120 °C. The partial oxidation of isopropanol to acetone and its condensation with aldehydes forming β-aryl enones occurred at room temperature. Increase in temperature caused the liberation of hydrogen gas from isopropanol and allowed the reversible reduction of aldehydes to alcohols. Increase in temperature in isopropanol and increase in base concentration in ethanol causes the selective reduction of aldehydes to alcohols. Besides being active for the Claisen-Schmidt type of reactions and the aryl halides amination process, the synthesized catalyst was also found to be highly active for the photocatalytic oxidation of benzyl alcohols in absence of any external oxidizing agent. The positive holes (h+) generated at the Co(II) site as evident from EPR analysis was considered to be responsible for high photocatalytic activity of the material reducing the recombination rate of holes and electrons (e?). Density Functional Theory calculations were performed to understand the mechanism of ethanol oxidation to acetaldehyde.
- Bania, Kusum K.,Baruah, Manash J.,Bhattacharyya, Pradip K.,Das, Biraj,Karunakar, Galla V.,Roy, Subhasish,Saikia, Lakshi,Saikia, Pinku,Sharma, Mukesh
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p. 104 - 121
(2020/06/01)
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- A tannin-derived zirconium-containing porous hybrid for efficient Meerwein-Ponndorf-Verley reduction under mild conditions
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Both the use of renewable natural sources to prepare catalytic materials and the Meerwein-Ponndorf-Verley (MPV) reduction for carbonyl compounds are very attractive topics in catalysis. In this study, tannins were simply assembled with zirconium in water for the scalable preparation of a heterogeneous zirconium-tannin hybrid catalyst (Zr-tannin). Various characterizations demonstrated the formation of robust porous inorganic-organic frameworks and strong Lewis acid-base sites in Zr-tannin. The cooperative effect of these acid-base sites and the abundant porosity endowed Zr-tannin with a remarkable catalytic performance for the MPV reduction of a broad range of carbonyl compounds to alcohols with 2-propanol under mild conditions. Moreover, Zr-tannin exhibited good recyclability for at least five reaction cycles. This novel strategy using tannins as the raw materials to construct heterogeneous catalytic materials may have a huge potential for green chemical synthesis due to low cost, nontoxicity, and sustainability.
- Leng, Yan,Shi, Langchen,Du, Shengyu,Jiang, Jiusheng,Jiang, Pingping
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p. 180 - 186
(2020/01/13)
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- Looking for new xanthine oxidase inhibitors: 3-Phenylcoumarins versus 2-phenylbenzofurans
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Overproduction of uric acid in the body leads to hyperuricemia, which is also closely related to gout. Uric acid production can be lowered by xanthine oxidase (XO) inhibitors. Inhibition of XO has also been proposed as a mechanism for improving cardiovascular health. Therefore, the search for new efficient XO inhibitors is an interesting topic in drug discovery. 3-Phenylcoumarins and 2-phenylbenzofurans are privileged scaffolds in medicinal chemistry. Their structural similarity makes them interesting molecules for a comparative study. Methoxy and nitro substituents were introduced in both scaffolds. The current study gives some insights into the synthesis and biological activity of these molecules against this important target. For the best compound of the series, the 3-(4-methoxyphenyl)-6-nitrocoumarin (4), the IC50 value, type of inhibition, cytotoxicity on B16F10 cells and ADME theoretical properties, were determined. Docking studies were also performed in order to better understand the interactions of this molecule with the XO binding pocket. This work is a preliminary screening for further design and synthesis of new non-purinergic derivatives as potential compounds involved in the inflammatory suppression, specially related to gout.
- Borges, Fernanda,Delogu, Giovanna L.,Era, Benedetta,Fais, Antonella,Gatto, Gianluca,Kumar, Amit,Matos, Maria J.,Pintus, Francesca,Uriarte, Eugenio
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p. 774 - 780
(2020/07/07)
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- Homogeneous Hydrogenation with a Cobalt/Tetraphosphine Catalyst: A Superior Hydride Donor for Polar Double Bonds and N-Heteroarenes
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The development of catalysts based on earth abundant metals in place of noble metals is becoming a central topic of catalysis. We herein report a cobalt/tetraphosphine complex-catalyzed homogeneous hydrogenation of polar unsaturated compounds using an air- and moisture-stable and scalable precatalyst. By activation with potassium hydroxide, this cobalt system shows both high efficiency (up to 24 000 TON and 12 000 h-1 TOF) and excellent chemoselectivities with various aldehydes, ketones, imines, and even N-heteroarenes. The preference for 1,2-reduction over 1,4-reduction makes this method an efficient way to prepare allylic alcohols and amines. Meanwhile, efficient hydrogenation of the challenging N-heteroarenes is also furnished with excellent functional group tolerance. Mechanistic studies and control experiments demonstrated that a CoIH complex functions as a strong hydride donor in the catalytic cycle. Each cobalt intermediate on the catalytic cycle was characterized, and a plausible outer-sphere mechanism was proposed. Noteworthy, external inorganic base plays multiple roles in this reaction and functions in almost every step of the catalytic cycle.
- Duan, Ya-Nan,Du, Xiaoyong,Cui, Zhikai,Zeng, Yiqun,Liu, Yufeng,Yang, Tilong,Wen, Jialin,Zhang, Xumu
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supporting information
p. 20424 - 20433
(2019/12/27)
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- Green synthesis of metal oxide nanoparticles and their catalytic activity for the reduction of aldehydes
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In the present work, a green synthesis of Metal Oxide nanoparticles was demonstrated using the freshly prepared aqueous extract of the immature fruit of Cocos nucifera and the MO nanoparticles were characterized by the analytical techniques such as UV–vis, FT-IR, XRD, SEM, TEM and EDAX. Characterization techniques confirmed that the biomolecules involved in the formation of nanoparticles and also they stabilized the nanoparticles. The synthesized MO nanoparticles were used as catalysts for the reduction of aromatic aldehydes. The reduction was done at mild reaction conditions using ammonium formate as a green hydrogen donor and the corresponding alcohols were obtained in 2–24 h with excellent yields. The reduction reaction was optimized using various solvents, loading of catalyst and at different temperatures.
- Muthuvinothini,Stella
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- Low-temperature catalytic hydrogenation of bio-based furfural and relevant aldehydes using cesium carbonate and hydrosiloxane
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Selective hydrogenation of unsaturated compounds is mainly carried out by using high-pressure hydrogen in the presence of a precious or transition metal catalyst. Here, we describe a benign approach to efficiently catalyze the hydrogenation of furfural (FUR) to furfuryl alcohol (FFA) over commercially available cesium carbonate using nontoxic and cheap polymethylhydrosiloxane (PMHS) as hydrogen source. Good to excellent FFA yields (≥90%) could be obtained at 25-80 °C by appropriate control of the catalyst dosage, reaction time, and the hydride amount. FUR-to-FFA hydrogenation was clarified to follow a pseudo-first order kinetics with low apparent activation energy of 20.6 kJ mol-1. Mechanistic insights manifested that PMHS was redistributed to H3SiMe, which acted as the active silane for the hydrogenation reactions. Importantly, this catalytic system was able to selectively reduce a wide range of aromatic aldehydes to the corresponding alcohols in good yields of 81-99% at 25-80 °C in 2-6 h.
- Long, Jingxuan,Zhao, Wenfeng,Xu, Yufei,Wu, Weibo,Fang, Chengjiang,Li, Hu,Yang, Song
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p. 3063 - 3071
(2019/02/10)
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- Easy-handling and low-leaching heterogeneous palladium and platinum catalysts via coating with a silicone elastomer
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We have developed a practical protocol for coating of commercial Pd/Al2O3 and Pt/Al2O3 catalysts in micro-powders with a silicone elastomer. Compared to original catalysts, the treated catalysts are easier to weight and transfer, and they are easier to recover by simple filtration. More importantly, the metal leaching of treated catalysts was significantly reduced. The treated catalysts worked very well in diverse hydrogenation reactions.
- Zhou, Mi,Li, Tingting,Xu, Bo
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supporting information
p. 948 - 952
(2019/03/08)
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- An acid-stable β-glucosidase from Aspergillus aculeatus: Gene expression, biochemical characterization and molecular dynamics simulation
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β-Glucosidases hydrolyze terminal, non-reducing β-D-glucosyl residues and thereby release β-D-glucose. They have applications in the production of biofuels, beverages and pharmaceuticals. In this study, a β-glucosidase derived from Aspergillus aculeatus (BGLA) was expressed, characterized, and the molecular mechanism of its acid denaturation was comprehensively probed. BGLA exhibited maximal activity at pH 5.0–6.0. Its optimal temperature was 70 °C. Its enzyme activity was enhanced by Mg2+, Ca2+ and Ba2+, while Cu2+, Mn2+, Zn2+, Fe2+ and Fe3+ had a negative effect. BGLA showed activity on a broad range of substrates including salicin, cellobiose, arbutin, geniposide and polydatin. Finally, the acid-denaturation mechanism of BGLA was probed using molecular dynamics (MD) simulations. The results of simulation at pH 2.0 imply that the contact number, solvent accessible surface area and number of hydrogen bonds in BGLA decreased greatly. Moreover, the distance between the residues Asp280 and Glu509 that are part of the active site increased, which eventually destroyed the enzyme's catalytic activity. These MD results explain the molecular mechanism of acid denaturation of BGLA, which will greatly benefit the rational design of more acid-stable β-glucosidase variants in the future.
- Li, Yu,Hu, Xiaoyan,Sang, Jingcheng,Zhang, Ying,Zhang, Huitu,Lu, Fuping,Liu, Fufeng
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p. 462 - 469
(2018/08/03)
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- Lewis Base Catalyzed Intramolecular Reduction of Salicylaldehydes by Pinacol-Derived Chlorohydrosilane
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A newly developed stable chlorohydrosilane derived from pinacol is herein described. This was successfully used in the reduction of salicylaldehydes in reasonable to excellent yields (51–97 %). The ability of the hydrosilane to react as a reducing agent is increased upon the in situ formation of a trialkoxyhydrosilane and activation with a Lewis base, as further indicated by density functional theory studies. 1,3-Dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) was identified to be a suitable catalyst for this metal-free reduction, promoting the regio- and chemoselective reduction of aldehydes in ortho-position to phenols, despite the presence of vicinal ketones. The performance of pinacol-derived chlorohydrosilane in the reduction of salicylaldehydes was further observed to be superior to that of well-established commercially available chlorohydrosilanes.
- Assoah, Benedicta,Vale, Jo?o R.,Kalenius, Elina,Veiros, Luis F.,Candeias, Nuno R.
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supporting information
p. 2910 - 2917
(2018/06/27)
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- Salbutamol impurity and impurity synthesizing method thereof
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The invention discloses an impurity in starting material of salbutamol sulfate and an impurity synthesizing method. The impurity is specifically 3-(2-bromoacetyl)-2-hydroxybenzaldehyde. The impurity has the advantages that a novel reference product is provided for the detection of impurity in the starting material, crude drug and preparations thereof of the salbutamol sulfate; the quality study and quality control are favorably performed on the starting material of the salbutamol sulfate; the qualities of the crude drug and the preparation of the salbutamol sulfate can be controlled.
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Paragraph 0055-0059
(2018/12/13)
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- A Pseudodearomatized PN3P?Ni-H Complex as a Ligand and σ-Nucleophilic Catalyst
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In contrast to the conventional strategy of modifying the reactivities and selectivities of the transition metal and organocatalysts by varying the steric and electronic properties of organic substituent groups, we hereby demonstrate a novel approach that the sigma (σ) nucleophilicity of the imine arm can be significantly enhanced in a pseudodearomatized PN3P? pincer ligand platform to reach unprecedented N-heterocyclic carbene-like reactivity. Accordingly, the imine arm of the PN3P?Ni-H pincer complex efficiently catalyzes the hydrosilylation of aldehydes, cycloaddition of carbon dioxide (CO2) to epoxides, and serves as a ligand in the Ru-catalyzed dehydrogenative acylation of amines with alcohols.
- Li, Huaifeng,Gon?alves, Théo P.,Hu, Jinsong,Zhao, Qianyi,Gong, Dirong,Lai, Zhiping,Wang, Zhixiang,Zheng, Junrong,Huang, Kuo-Wei
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p. 14969 - 14977
(2019/01/03)
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- Selective Hydrogenation of Aldehydes Using a Well-Defined Fe(II) PNP Pincer Complex in Biphasic Medium
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A biphasic process for the hydrogenation of aldehydes was developed using a well-defined iron (II) PNP pincer complex as model system to investigate the performance of various ionic liquids. A number of suitable hydrophobic ionic liquids based on the N(Tf)2? anion were identified, allowing to immobilize the iron (II) catalyst in the ionic liquid layer and to facilitate the separation of the desired alcohols. Further studies showed that targeted Br?nsted basic ionic liquids can eliminate the need of an external base to activate the catalyst.
- Weber, Stefan,Brünig, Julian,Zeindlhofer, Veronika,Schr?der, Christian,St?ger, Berthold,Limbeck, Andreas,Kirchner, Karl,Bica, Katharina
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p. 4386 - 4394
(2018/09/14)
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- A porous metal-organic aerogel based on dirhodium paddle-wheels as an efficient and stable heterogeneous catalyst towards the reduction reaction of aldehydes and ketones
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A new metal-organic aerogel (MOA-Rh-2) containing dirhodium paddle-wheels has been prepared from the reaction of dirhodium(ii) tetracarboxylate (Rh2(OAc)4) and tetrakis(4-carboxyphenyl)porphyrin (TCPP) in a mixed solvent of DMF and water, followed by supercritical CO2 extraction. MOA-Rh-2 has been fully characterized by ICP-OES, EDS, XPS, PXRD, SEM, TEM and TGA. Its porosity has been confirmed by N2 adsorption isotherms at 77 K, and the Barrett-Joyner-Halenda pore size is centered at 3.5 nm. The existence of mesopores has been further verified by dye adsorption tests using methylene blue (14.4 × 6.1 ?2) and rhodamine B (15.8 × 11.8 × 6.8 ?3). MOA-Rh-2 is air and moisture-stable. The catalytic results show that, under an air atmosphere and at ambient temperature, a low loading (0.1-0.4 mol%) of MOA-Rh-2 can efficiently promote the hydrosilylation of aldehydes and ketones with the commercially available silane of PhSiH3. After catalytic reactions, MOA-Rh-2 can be recycled and reused for 5 runs without significant loss of the activity, and the reaction conversions are in the range of 89-99%.
- Liu, Gang,Wang, Yanhu,Zhu, Baofu,Zhang, Li,Su, Cheng-Yong
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p. 11358 - 11363
(2018/07/24)
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- Highly selective hydrogenation of Α, Β-unsaturated carbonyl compounds over supported Co nanoparticles
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A nitrogen-doped porous carbon materials (CPNs) with supported Co nanoparticles (Co@CPNs) with lamellar structure, high surface area and excellent magnetic properties was synthesized successfully by one-pot method. The Co@CPNs exhibited an excellent catalytic activity with 99% conversion and selectivity for hydrogenation of furfural (FAL) to furfuryl alcohol (FOL) under the pressure of H2. In addition, the Co@CPNs were further investigated in the kinetic study and selective hydrogenation of the other α, β unsaturated carbonyl compounds. The study of the Co@CPNs indicated that it was suitable for selective hydrogenation of the α, β unsaturated carbonyl compounds in the industry.
- Jiang, Pengbo,Li, Xinlin,Gao, Wenbin,Wang, Xiang,Tang, Yu,Lan, Kai,Wang, Bin,Li, Rong
-
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- Rhodium-Catalyzed Annulations of 1,3-Dienes and Salicylaldehydes/2-Hydroxybenzyl Alcohols Promoted by 2-Ethylacrolein
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A rhodium-catalyzed 2-ethylacrolein-promoted protocol enables the annulation reactions of 1,3-dienes with either salicylaldehydes or 2-hydroxybenzyl alcohols leading to 2-alkylchroman-4-ones with high regioselectivity. This research highlights the use of 2-ethylacrolein which probably serves as a tool of bidentate coordination to rhodium intermediates. Mechanistic studies reveal that the transformation proceeds through the 1,4-hydroacylation pathway to access unsaturated linear ketones with subsequent oxo-Michael addition. (Figure presented.).
- Li, Hong-Shuang,Xiong, Yang,Zhang, Guozhu
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supporting information
p. 4246 - 4251
(2018/10/02)
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- Benzopyrans compound as well as preparation method and application thereof
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The invention relates to the field of the agricultural fungicide, and specifically relates to a benzopyrans compound as well as a preparation method and application thereof. The benzopyrans compound provided by the invention is simple in structure, easy to synthesize, low in production cost, and has a good inhibiting effect on the strawberry botrytis cinerea, potato altemaria solani, and watermelon fusarium oxysporum.
- -
-
Paragraph 0038-0041
(2018/11/27)
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- Syntheses, characterisation, and catalytic role of (η5-C5Me5)Rh(III) guanidinato complexes in transfer hydrogenation (TH) and TH-etherification
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A family of air stable half sandwich meal guanidinato complexes ([(η5-Cp?)MCl{κ2(N,N′)((ArN)2C-N(H)Ar)}]) (M = Rh and Ir; Cp? = C5Me5; Ar = aryl) were synthesized in good yield and characterised by elemental analyses, IR, and NMR (1H, 13C, and 19F) spectroscopy. The geometry of the metal and the conformations of the guanidinate ligands in the complexes were studied by single crystal X-ray diffraction. The solution behaviour of representative complexes was investigated by detailed NMR studies including variable temperature and variable concentration 1H NMR measurements. The new complexes were screened as catalysts for transfer hydrogenation (TH) of acetophenone under basic and base free conditions and from these experiments, ([(η5-Cp?)RhCl{κ2(N,N′)((ArN)2C-N(H)Ar)}]) (Ar = 3,5-(CF3)2C6H3; 3) was chosen as the preferred catalyst due to its slightly better catalytic activity than other complexes. The utility of 3 in TH of a variety of carbonyl compounds was explored under basic and base free conditions. Tandem catalysis involving TH of a carbonyl group and etherification of the resulting -CH2OH group in reduction products of salicylaldehyde, 2-hydroxy-1-naphthaldehyde and 5-(hydroxymethyl)furfural was achieved in the presence of 3 under base free conditions. The role of the guanidinate ligands in the complexes for basic and base free TH of carbonyl compounds and TH-etherification tandem catalysis is discussed. Plausible mechanisms for TH and TH-etherification are outlined.
- Kumar, Robin,Thirupathi, Natesan
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p. 33890 - 33904
(2017/07/17)
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- Probing cobalt sites in CoAPO-11 via spectroscopic and activity studies
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A systematic study undertaken for the oxidation state, coordination, stability of cobalt in CoAPO-11 structure by means of spectroscopic and catalytic activity, is presented. AlPO-11 containing Co(II) in the tetrahedral coordination was indicated by powder diffraction, electronic and EPR data. During calcination of Co(II) was partly converted to Co(III) and reverted back to Co(II) upon exposure to atmosphere. Apart from micropores, CoAPO-11 sample contains mesopores, which possibly arise from interparticle void space. The tetrahedral location of Co(II) was inferred from EPR data. The rectangular to spherical shapes of CoAPO-11 material was evident from electron micrographs. Activity studies revealed that o-cresol can selectively be converted to o-hydroxy benzoic acid. Moderate activity of CoAPO-11 along with spectroscopic analysis supports the fact that Co(II) is predominantly located in tetrahedral framework and do not convert to Co(III) effectively, as a consequence Co(II) are stable and do not display appreciable oxidative ability under mild reaction conditions.
- Sahoo,Badamali
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p. 2197 - 2202
(2017/10/05)
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- Nano Fe3O4@ZrO2/SO42?: A highly efficient catalyst for the protection and deprotection of hydroxyl groups using HMDS under solvent-free condition
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In this work, we introduce a new procedure for the protection and deprotection process of various types of alcohols and phenols by HMDS in the presence of nano magnetic sulfated zirconia (Fe3O4@ZrO2/SO42?) as a solid acid catalyst under very mild and solvent-free condition. This method has interesting advantages like short reaction times and a simple workup process. With regard to some outstanding benefits of this new heterogeneous catalyst such as excellent yield, reusability of the catalyst and easy thermal stability, high acidity, strong and excellent magnetic properties, this method can be very interesting in aspect of green chemistry Principles.
- Ghafuri, Hossein,Paravand, Fatemeh,Rashidizadeh, Afsaneh
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supporting information
p. 129 - 135
(2016/12/24)
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- Aqueous Oxidations Started by TiO2 Photoinduced Holes Can Be a Rate-Determining Step
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In aqueous TiO2 photocatalytic hydroxylation of weakly polar aromatics, a series of inverse H/D KIEs of 0.7–0.8 were observed, which is different than the normal H/D kinetic isotope effects (KIEs) usually observed for polar aromatics. This result indicated that the oxidation started by photo-induced hvb + can be the rate-determining step.
- Gong, Yuanzheng,Yang, Chun,Ji, Hongwei,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
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supporting information
p. 2048 - 2051
(2017/08/23)
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- Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source
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A water-soluble highly efficient iridium catalyst is developed for the chemoselective reduction of aldehydes to alcohols in water. The reduction uses formic acid as the traceless reducing agent and water as a solvent. It can be carried out in air without the need for inert atmosphere protection. The products can be purified by simple extraction without any column chromatography. The catalyst loading can be as low as 0.005 mol% and the turn-over frequency (TOF) is as high as 73 800 mol mol-1 h-1. A wide variety of functional groups, such as electron-rich or deficient (hetero)arenes and alkenes, alkyloxy groups, halogens, phenols, ketones, esters, carboxylic acids, cyano, and nitro groups, are all well tolerated, indicating excellent chemoselectivity.
- Yang, Zhanhui,Zhu, Zhongpeng,Luo, Renshi,Qiu, Xiang,Liu, Ji-Tian,Yang, Jing-Kui,Tang, Weiping
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supporting information
p. 3296 - 3301
(2017/07/28)
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- Zinc-Mediated Efficient and Selective Reduction of Carbonyl Compounds
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We herein describe for the first time that an optimized combination of Zn and NH4Cl can be used for the selective reduction of aldehydes and ketones to the corresponding alcohols. The aldehyde and keto groups are selectively reduced in the presence of azide, cyano, epoxy, ester, and carbon–carbon double-bond functional groups. A broad functional-group compatibility, chemoselective reduction of aldehydes in the presence of ketones, and selective reduction of isatins at the C3 carbonyl group are the highlights of the present method.
- Mandal, Tirtha,Jana, Snehasish,Dash, Jyotirmayee
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p. 4972 - 4983
(2017/09/13)
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- MAO inhibitory activity of bromo-2-phenylbenzofurans: Synthesis,: in vitro study, and docking calculations
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Monoamine oxidase (MAO) is an enzyme responsible for metabolism of monoamine neurotransmitters which play an important role in brain development and function. This enzyme exists in two isoforms, and it has been demonstrated that MAO-B activity, but not MAO-A activity, increases with aging. MAO inhibitors show clinical value because besides the monoamine level regulation they reduce the formation of by-products of the MAO catalytic cycle, which are toxic to the brain. A series of 2-phenylbenzofuran derivatives was designed, synthesized and evaluated against hMAO-A and hMAO-B enzymes. A bromine substituent was introduced in the 2-phenyl ring, whereas position 5 or 7 of the benzofuran moiety was substituted with a methyl group. Most of the tested compounds inhibited preferentially MAO-B in a reversible manner, with IC50 values in the low micro or nanomolar range. The 2-(2′-bromophenyl)-5-methylbenzofuran (5) was the most active compound identified (IC50 = 0.20 μM). In addition, none of the studied compounds showed cytotoxic activity against the human neuroblastoma cell line SH-SY5Y. Molecular docking simulations were used to explain the observed hMAO-B structure-activity relationship for this type of compounds.
- Delogu,Pintus,Mayán,Matos,Vilar,Munín,Fontenla,Hripcsak,Borges,Vi?a
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p. 1788 - 1796
(2017/09/29)
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- METHOD TO PREPARE PHENOLICS FROM BIOMASS
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The present invention is directed to a method for preparing a final phenolic product from biomass comprising the steps of providing a furanic compound obtainable from biomass; reacting the furanic compound with a dienophile to obtain a phenolic compound; reacting the phenolic compound further to obtain the final phenolic product.
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Page/Page column 44
(2016/08/10)
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- NOVEL IMINES WITH TUNABLE NUCLEOPHILICITY AND STERIC PROPERTIES THROUGH METAL COORDINATION: APPLICATIONS AS LIGANDS AND METALLOORGANOCATALYSTS
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The invention describes phospho-amino pincer-type ligands, metal complexes thereof, and catalytic methods comprising such metal complexes for conversion of carbon dioxide to methanol, conversion of aldehydes into alcohols, conversion of aldehydes in the presence of a trifluoromethylation agent into trifluorinated secondary alcohols, cycloaddition of carbon dioxide to an epoxide to provide cyclic carbonates or preparation of an amide from the combination of an alcohol and an amine.
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-
Paragraph 0179; 0187
(2016/04/20)
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- Cobalt-Catalyzed Annulation of Salicylaldehydes and Alkynes to Form Chromones and 4-Chromanones
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A unique cobalt(I)-diphosphine catalytic system has been identified for the coupling of salicylaldehyde (SA) and an internal alkyne affording a dehydrogenative annulation product (chromone) or a reductive annulation product (4-chromanone) depending on the alkyne substituents. Distinct from related rhodium(I)- and rhodium(III)-catalyzed reactions of SA and alkynes, these annulation reactions feature aldehyde C-H oxidative addition of SA and subsequent hydrometalation of the C=O bond of another SA molecule as common key steps. The reductive annulation to 4-chromanones also involves the action of Zn as a stoichiometric reductant. In addition to these mechanistic features, the CoI catalysis described herein is complementary to the RhI- and RhIII-catalyzed reactions of SA and internal alkynes, particularly in the context of chromone synthesis.
- Yang, Junfeng,Yoshikai, Naohiko
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supporting information
p. 2870 - 2874
(2016/02/27)
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- Porous Ge@C materials via twin polymerization of germanium(II) salicyl alcoholates for Li-ion batteries
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The germylenes, germanium(ii) 2-(oxidomethyl)phenolate (1), germanium(ii) 4-methyl-2-(oxidomethyl)phenolate (2) and germanium(ii) 4-bromo-2-(oxidomethyl)phenolate (3) were synthesized and their thermally induced twin polymerization to give organic-inorganic hybrid materials was studied. The compounds 1-3 form oligomers including dimers, trimers and tetramers as a result of intermolecular coordination of the benzylic oxygen atom to germanium. The structural motifs were studied by single crystal X-ray diffraction analysis and DFT-D calculations. Thermally induced twin polymerization of these germylenes gave hybrid materials based on germanium-containing phenolic resins. Carbonization of these resins under reductive conditions resulted in porous materials that are composed of germanium and carbon (Ge@C materials), while oxidation with air provided non-porous germanium dioxide. The porous Ge@C materials were tested as potential anode materials for rechargeable Li-ion batteries. Reversible capacities of 540 mA h g-1 were obtained at a current density of 346 mA g-1 without apparent fading for 100 cycles, which demonstrates that germanium is well accessible in the hybrid material.
- Kitschke, Philipp,Walter, Marc,Rüffer, Tobias,Seifert, Andreas,Speck, Florian,Seyller, Thomas,Spange, Stefan,Lang, Heinrich,Auer, Alexander A.,Kovalenko, Maksym V.,Mehring, Michael
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supporting information
p. 2705 - 2719
(2016/02/20)
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- Reversing aggregation: direct synthesis of nanocatalysts from bulk metal. Cellulose nanocrystals as active support to access efficient hydrogenation silver nanocatalysts
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A highly atom-economical synthetic method to access nanocatalysts from bulk metal is described. A water suspension of cellulose nanocrystals was exposed to an Ag wire, under air and light exposure. In 2 weeks, Ag nanoparticles of size 1.3 nm ± 0.3 nm were deposited onto the biopolymer. These species were active for the hydrogenation of aldehydes, 4-nitrophenol, alkenes and alkynes.
- Kaushik, Madhu,Li, Alain You,Hudson, Reuben,Masnadi, Mitra,Li, Chao-Jun,Moores, Audrey
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p. 129 - 133
(2015/12/31)
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- 2-Phenylbenzofuran derivatives as butyrylcholinesterase inhibitors: Synthesis, biological activity and molecular modeling
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A series of 2-phenylbenzofurans compounds was designed, synthesized and evaluated as cholinesterase inhibitors. The biological assay experiments showed that most of the compounds displayed a clearly selective inhibition for butyrylcholinesterase (BChE), while a weak or no effect towards acetylcholinesterase (AChE) was detected. Among these benzofuran derivatives, compound 16 exhibited the highest BChE inhibition with an IC50 value of 30.3 μM. This compound was found to be a mixed-type inhibitor as determined by kinetic analysis. Moreover, molecular dynamics simulations revealed that compound 16 binds to both the catalytic anionic site (CAS) and peripheral anionic site (PAS) of BChE and it displayed the best interaction energy value, in agreement with our experimental data.
- Delogu, Giovanna L.,Matos, Maria J.,Fanti, Maura,Era, Benedetta,Medda, Rosaria,Pieroni, Enrico,Fais, Antonella,Kumar, Amit,Pintus, Francesca
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p. 2308 - 2313
(2016/04/20)
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- Palladium-catalyzed three-component coupling reactions of 2-(cyanomethyl)phenol, aryl halides, and carbon monoxide
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Three-component coupling reactions of 2-(cyanomethyl)phenol, aryl halides, and carbon monoxide (CO) in orthogonal-tandem catalysis were investigated. In the reactions, 2-(cyanomethyl)phenyl esters, which are produced through Pd(PPh3)4-catalyzed alkoxycarbonylation of aryl halides with 2-(cyanomethyl)phenol, undergo cycloisomerization in situ catalyzed by Pd(PCy3)2 as a co-catalyst to give 3-acyl-2-aminobenzofurans. Palladium species with homoleptic tertiary phosphines, such as Pd(PPh3)4 and Pd(PCy3)2, can catalyze the mechanistically distinct reactions in an orthogonal-tandem manner without interference. By switching the base used in this reaction, 3-acyl-2-(N-acylamino)benzofurans were obtained as major products instead of 3-acyl-2-aminobenzofurans. Given that 2-(cyanomethyl)phenols can be synthesized from commercially available salicylic acid derivatives in two steps, the present method thus provides facile access to synthetically useful 3-acyl-2-aminobenzofurans.
- Murai, Masahito,Okamoto, Kazuhiro,Miki, Koji,Ohe, Kouichi
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supporting information
p. 4432 - 4437
(2015/06/08)
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- Highly chemoselective hydrogenation of active benzaldehydes to benzyl alcohols catalyzed by bimetallic nanoparticles
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By using novel Pd/Ni bimetallic nanoparticles as a catalyst, the active benzaldehydes were hydrogenated to the corresponding benzyl alcohols as unique products in practical quantitative yields. The undesired catalytic hydrogenolysis of the benzyl alcohol was inhibited completely. By using this hydrogenation as a key step, the total synthesis of the natural product gastrodin was achieved with less total steps and a higher total yield.
- Liu, Chulong,Bao, Hailin,Wang, Dingsheng,Wang, Xinyan,Li, Yadong,Hu, Yuefei
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p. 6460 - 6462
(2015/11/16)
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