- Kinetic Modeling of Ethylene Glycol Monoesterification
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The monoesterification of ethylene glycol under isothermal conditions was conducted using benzoic acid in methane-sulfonic acid/Al2O3 as a catalyst. Using this reagent, glycol was selectively monoesterified with high yield. The reactions were performed within an automated batch reactor under equimolar conditions, constant rotational frequency of the stirrer, and within the temperature range from 65 to 85°C. The rate constant related to this reaction and to the corresponding reverse reaction, activation energy, and preexponential factor was derived from experimental data. It has been concluded that under these conditions the formation of dibenzoate was successfully prevented.
- Pe?ar, Darja,Gor?ek, Andreja
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Read Online
- Fast Addition of s-Block Organometallic Reagents to CO2-Derived Cyclic Carbonates at Room Temperature, Under Air, and in 2-Methyltetrahydrofuran
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Fast addition of highly polar organometallic reagents (RMgX/RLi) to cyclic carbonates (derived from CO2 as a sustainable C1 synthon) has been studied in 2-methyltetrahydrofuran as a green reaction medium or in the absence of external volatile organic solvents, at room temperature, and in the presence of air/moisture. These reaction conditions are generally forbidden with these highly reactive main-group organometallic compounds. The correct stoichiometry and nature of the polar organometallic alkylating or arylating reagent allows straightforward synthesis of: highly substituted tertiary alcohols, β-hydroxy esters, or symmetric ketones, working always under air and at room temperature. Finally, an unprecedented one-pot/two-step hybrid protocol is developed through combination of an Al-catalyzed cycloaddition of CO2 and propylene oxide with the concomitant fast addition of RLi reagents to the in situ and transiently formed cyclic carbonate, thus allowing indirect conversion of CO2 into the desired highly substituted tertiary alcohols without need for isolation or purification of any reaction intermediates.
- Elorriaga, David,de la Cruz-Martínez, Felipe,Rodríguez-álvarez, María Jesús,Lara-Sánchez, Agustín,Castro-Osma, José Antonio,García-álvarez, Joaquín
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p. 2084 - 2092
(2021/04/02)
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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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- Expanding the Tool Kit of Automated Flow Synthesis: Development of In-line Flash Chromatography Purification
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Recent advancements in in-line extraction and purification technology have enabled complex multistep synthesis in continuous flow reactor systems. However, for the large scope of chemical reactions that yield mixtures of products or residual starting materials, off-line purification is still required to isolate the desired compound. We present the in-line integration of a commercial automated flash chromatography system with a flow reactor for the continuous synthesis and isolation of product(s). A proof-of-principle study was performed to validate the system and test the durability of the column cartridges, performing an automated sequence of 100 runs over 2 days. Three diverse reaction systems that highlight the advantages of flow synthesis were successfully applied with in-line normal- or reversed-phase flash chromatography, continuously isolating products with 97-99% purity. Productivity of up to 9.9 mmol/h was achieved, isolating gram quantities of pure product from a feed of crude reaction mixture. Herein, we describe the development and optimization of the systems and suggest guidelines for selecting reactions well suited to in-line flash chromatography.
- Thomson, Christopher G.,Banks, Colin,Allen, Mark,Barker, Graeme,Coxon, Christopher R.,Lee, Ai-Lan,Vilela, Filipe
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supporting information
p. 14079 - 14094
(2021/07/31)
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- Design and synthesis of tricyclic terpenoid derivatives as novel PTP1B inhibitors with improved pharmacological property and in vivo antihyperglycaemic efficacy
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Overexpression of protein tyrosine phosphatase 1B (PTP1B) induces insulin resistance in various basic and clinical research. In our previous work, a synthetic oleanolic acid (OA) derivative C10a with PTP1B inhibitory activity has been reported. However, C10a has some pharmacological defects and cytotoxicity. Herein, a structure-based drug design approach was used based on the structure of C10a to elaborate the smaller tricyclic core. A series of tricyclic derivatives were synthesised and the compounds 15, 28 and 34 exhibited the most PTP1B enzymatic inhibitory potency. In the insulin-resistant human hepatoma HepG2 cells, compound 25 with the moderate PTP1B inhibition and preferable pharmaceutical properties can significantly increase insulin-stimulated glucose uptake and showed the insulin resistance ameliorating effect. Moreover, 25 showed the improved in vivo antihyperglycaemic potential in the nicotinamide–streptozotocin-induced T2D. Our study demonstrated that these tricyclic derivatives with improved molecular architectures and antihyperglycaemic activity could be developed in the treatment of T2D.
- Chen, Feng,Chen, Jiabao,Gao, Cheng,Li, Junyan,Liu, Siyan,Qian, Shan,Wang, Zhouyu,Yang, Lingling,Zhang, Yuanyuan
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p. 152 - 164
(2019/11/25)
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- Stannous chloride as a low toxicity and extremely cheap catalyst for regio-/site-selective acylation with unusually broad substrate scope
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This work reports stannous chloride (SnCl2)-catalyzed regio-/site-selective acylation with unusually broad substrate scope. In addition to 1,2- and 1,3-diols and glycosides containing cis-vicinal diol, the substrate scope also includes glycosides without cis-vicinal diol. For such a substrate scope, usually, only methods using stoichiometric amounts of organotin reagents can lead to the same protection pattern with high selectivities and highly isolated yields (84-97% in most cases). Therefore, SnCl2, as a low toxicity and extremely cheap reagent, should be the best catalyst for regio-/site-selective acylation compared with any previously reported reagents. This journal is
- Dong, Hai,Feng, Guang-Jing,Luo, Tao,Lv, Jian,Yu, Jian-Cheng
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supporting information
p. 6936 - 6942
(2020/11/09)
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- Selective Acylation of Aryl- A nd Heteroarylmagnesium Reagents with Esters in Continuous Flow
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A selective acylation of readily accessible organomagnesium reagents with commercially available esters proceeds at convenient temperatures and short residence times in continuous flow. Flow conditions allow us to prevent premature collapse of the hemiacetal intermediates despite noncryogenic conditions, thus furnishing ketones in good yields. Throughout, the coordinating ability of the ester and/or Grignard was crucial for the reaction outcome. This was leveraged by the obtention of several bisaryl ketones using 2-hydroxy ester derivatives as substrates.
- Heinz, Benjamin,Djukanovic, Dimitrije,Ganiek, Maximilian A.,Martin, Benjamin,Schenkel, Berthold,Knochel, Paul
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supporting information
p. 493 - 496
(2020/01/31)
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- Electrochemical esterification reaction of alkynes with diols: Via cleavage of carbon-carbon triple bonds without catalyst and oxidant
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A novel electrochemical esterification of alkynes for the synthesis of esters was developed in which diols and their derivatives were used as the partners. This method is green as it is catalyst-free, oxidant-free, and additive-free and shows atom-economy. This is the first example of an electrochemical reaction via cleavage of carbon-carbon triple bonds. Meanwhile, this is also the first example of a carbon-carbon triple bond cleavage reaction of alkynes with diols. This journal is
- Cheng, Hui-Hui,Gao, Hui,Li, Pin-Hua,Shen, Hui-Zhi,Wang, Pei-Long
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supporting information
p. 6783 - 6791
(2020/11/09)
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- Protecting-group-free synthesis of hydroxyesters from amino alcohols
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The synthesis of hydroxyesters from carboxylic acids and unprotected amino alcohols in both continuous flow and batch processes is reported. The formation of a transient diazonium species with a dinitrite reagent is key in this transformation. The reaction conditions are compatible with a variety of functional groups.
- Joseph-Valcin, Eve-Marline,Lebel, Hélène,Reynard, Guillaume
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supporting information
p. 10938 - 10941
(2020/10/02)
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- Luminescent tungsten(vi) complexes as photocatalysts for light-driven C-C and C-B bond formation reactions
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The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.
- Chan, Kaai-Tung,Che, Chi-Ming,Du, Lili,Liu, Yungen,Phillips, David Lee,To, Wai-Pong,Tong, Glenna So Ming,Wu, Liang-Liang,Yu, Daohong
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p. 6370 - 6382
(2020/07/15)
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- Selective Monoacylation of Diols and Asymmetric Desymmetrization of Dialkyl meso-Tartrates Using 2-Pyridyl Esters as Acylating Agents and Metal Carboxylates as Catalysts
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With 2-pyridyl benzoates as acylating agents and Zn(OAc)2 as a catalyst, 1,2-diols, 1,3-diols, and catechol were selectively monoacylated. Furthermore, the highly enantioselective desymmetrization of meso-tartrates was achieved for the first time, utilizing 2-pyridyl esters and NiBr2/AgOPiv/Ph-BOX in CH3CN or CuCl2/AgOPiv/Ph-BOX in EtOAc catalyst systems (up to 96% ee). The latter catalyst system was also effective for the kinetic resolution of dibenzyl dl-tartrate.
- Hashimoto, Yuki,Michimuko, Chiaki,Yamaguchi, Koki,Nakajima, Makoto,Sugiura, Masaharu
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p. 9313 - 9321
(2019/08/12)
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- Dabigatran etexilate derivative and pharmaceutical use thereof
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The invention discloses a compound shown as formula (II), a hydrate, isomer, solvate, prodrug or a mixture thereof, and pharmaceutically acceptable salts thereof. The invention also discloses a pharmaceutical composition and a combination preparation containing the compounds as active ingredients, and use of the compounds, the pharmaceutical composition and the combination preparation as thrombininhibitors.
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Paragraph 0338; 0343-0345
(2019/07/04)
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- Mechanistic and Synthetic Implications of the Diol-Ritter Reaction: Unexpected Yet Reversible Pathways in the Regioselective Synthesis of Vicinal-Aminoalcohols
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The Ritter reaction of 1,2-diolmonoesters with nitriles to 1-vic-amido-2-esters proceeds through dioxonium and nitrilium cation intermediates. To provide the basis for the reaction mechanism, novel forms of these cations were isolated, characterized, and studied by spectroscopic methods and single crystal X-ray analysis. Ground and transition state energies were determined both experimentally and theoretically. Taken together, these data suggest that the reaction proceeds via rapid formation of the dioxonium cation 9, followed by rate determining yet reversible ring opening by acetonitrile to the corresponding nitrilium cation 10 (computed ΔG∞ = 24.7 kcal at 50 °C). Rapid, irreversible hydration of the latter affords the corresponding vic-acetamido ester. Controlled addition of H2O to the dioxonium cation 9 in acetonitrile-d3 results in near-quantitative production of deuterated acetamido ester 13a. Kinetics of this conversion (9 to 13a) are biphasic, and the slow phase is ascribed to either direct cation 9 attack by acetamide to form cation 16 via O-alkylation or by reversible ether formation. Deuterium labeling studies suggest O-alkylated cation 16 does not directly isomerize to N-alkylated cation 18; instead, it reverts to vic-amidoester 13a via the nitrilium pathway. Preliminary results indicate high regioselectivity for primary amide formation in the diol-Ritter sequence.
- Ondari, Mark E.,Klosin, Jerzy,Froese, Robert D. J.,Kruper, William R.,Macdonald, Jason,Arriola, Dan J.,Bell, Bruce M.,Briggs, John R.,Kruper, William J.
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supporting information
p. 4715 - 4722
(2018/12/14)
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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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- Woody species: A new bio-based material for dual Ca/Mg catalysis with remarkable Lewis acidity properties
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Advances in green catalysis have promoted the development of ecocatalysis encountered in most of the main transformations of organic chemistry. Taking advantage of the remarkable capacity of certain plants to hyperaccumulate transition metals into shoots or roots, we have addressed the direct use of metals derived from contaminated plant wastes as supported Lewis acid catalysts, coupling agents, oxidative and reducing catalysts in green chemistry. This approach constituted the first example of chemical catalyst based on phytotechnologies. Herein, we show that the concept can be extended to common and abundant plant species that are surprisingly appropriated for chemical catalysis. We present that willow, birch, plane and linden trees can be used to produce bio-based and original Lewis acid catalysts. The catalytic potential of these species will be illustrated through two representative transformations, acetalisation and oxidative esterification. Thanks to their original polymetallic composition, ecocatalysts provided better results compared to classical metal chlorides such as MgCl2, CaCl2 or ZnCl2. This illustrates the interest of the ecocatalysis and is incorporated within the green and sustainable chemistry concept.
- Deyris, Pierre-Alexandre,Adler, Pauline,Petit, Eddy,Legrand, Yves-Marie,Grison, Claude
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p. 3133 - 3142
(2019/06/18)
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- Domino Two-Step Oxidation of β-Alkoxy Alcohols to Hemiacetal Esters: Linking a Stoichiometric Step to an Organocatalytic Step with a Common Organic Oxidant
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Primary and secondary β-alkoxy alcohols can be cleanly and efficiently oxidized into hemiacetal esters in a cascade two-step process. mCPBA serves both as a stoichiometric oxidant in the first TEMPO-catalyzed step, converting alcohols to aldehydes/ketones, and as a reagent in the second Baeyer–Villiger stoichiometric oxidation, transforming the aldehydes/ketones into hemiacetal esters. The use of an oxidant common to both steps enables the domino reaction to proceed under a single experimental setting. Longer oxidative cascade sequences are possible when this new methodology is applied to suitable substrates.
- Targel, Tom,Ramesh, Palakuri,Portnoy, Moshe
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supporting information
p. 3017 - 3021
(2018/06/27)
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- An inexpensive catalyst, Fe(acac)3, for regio/site-selective acylation of diols and carbohydrates containing a 1,2-: Cis -diol
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This work describes the [Fe(acac)3] (acac = acetylacetonate)-catalyzed, regio/site-selective acylation of 1,2- and 1,3-diols and glycosides containing a cis-vicinal diol. The iron(iii) catalysts initially formed cyclic dioxolane-type intermediates with substrates between the iron(iii) species and vicinal diols, and the efficient and selective acylation of one hydroxyl group was subsequently achieved by adding acylation reagents in the presence of diisopropylethylamine (DIPEA) under mild conditions. This reaction generally produced high selectivities and highly isolated yields with the same protection pattern as that achieved with dibutyl tinoxide-mediated schemes.
- Lv, Jian,Ge, Jian-Tao,Luo, Tao,Dong, Hai
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supporting information
p. 1987 - 1991
(2018/05/23)
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- ANTIBACTERIAL COMPOSITION INCLUDING BENZOIC ACID ESTER AND METHODS OF INHIBITING BACTERIAL GROWTH UTILIZING THE SAME
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Antibacterial compositions and methods for inhibiting bacterial growth are disclosed. The antibacterial compositions can include a carrier and an antibacterial agent including a benzoic acid ester. The benzoic acid ester can have a carbon chain having a length of two to ten. The benzoic acid ester can have a hydroxyl group on the carbon chain.
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Page/Page column 22
(2018/08/26)
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- Fe-catalyzed esterification of amides via C-N bond activation
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An efficient Fe-catalyzed esterification of primary, secondary, and tertiary amides with various alcohols for the preparation of esters was performed. The esterification process was accomplished with FeCl3$6H2O, which is a stable, inexpensive, environmentally friendly catalyst with high functional group tolerance.
- Chen, Xiuling,Hu, Siying,Chen, Rongxing,Wang, Jian,Wu, Minghu,Guo, Haibin,Sun, Shaofa
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p. 4571 - 4576
(2018/02/09)
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- Graphene Oxide: An Efficient Acid Catalyst for the Construction of Esters from Acids and Alcohols
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Graphene oxide was found to be an efficient and reusable acid catalyst for the esterification reaction. A wide range of aliphatic and aromatic acids and alcohols were compatible with the standard conditions and afforded the corresponding products in good yields. The heterogeneous catalyst can be easily recovered and recycled in dichloro-ethane solvent with good catalytic activity.
- Chen, Zhengwang,Wen, Yuelu,Fu, Yejuan,Chen, Hai,Ye, Min,Luo, Guotian
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supporting information
p. 981 - 985
(2017/05/05)
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- Ruthenium-catalyzed oxidative decyanative cross-coupling of acetonitriles with amines in air: A general access to primary to tertiary amides under mild conditions
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Catalyzed by Ru and in the presence of air and nucleophiles such as amines or ammonia, activation of the C-CN bond could be easily achieved under mild conditions to produce primary to tertiary amides in good to excellent yields. The use of accessible and functional-group-tolerant starting materials, a cheap, low-loading and recyclable catalyst, ligand-free conditions and excellent product yields are the advantages of the method. Moreover, compared with the Ritter reaction and hydration methods, this novel reaction has more comprehensive application scope.
- Wang, Yuguang,Wu, Zhongli,Li, Qin,Zhu, Bingchun,Yu, Lei
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p. 3747 - 3757
(2017/09/07)
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- Amberlyst-15 catalysed oxidative esterification of aldehydes using a H2O2 trapped oxidant as a terminal oxidant
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A simple and efficient method has been developed for the selective oxidative esterification of aldehydes using commercially available Amberlyst-15 as a catalyst. H2O2 released from a clathrate structured 4Na2SO4·2H2O2·NaCl oxidant serves as an efficient source of terminal oxidants. Various aromatic, heteroaromatic, and aliphatic aldehydes undergo selective esterification to give good to excellent yield. The heterogeneous catalyst, Amberlyst-15, exhibits high reactivity and can be recycled over several runs. The 4Na2SO4·2H2O2·NaCl oxidant was found to be superior to commonly used oxidizing agents providing an anhydrous, easy to handle and stable form of H2O2
- Gayakwad, Eknath M.,Patil, Vilas V.,Shankarling, Ganapati S.
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p. 2695 - 2701
(2017/04/03)
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- Benzo [1, 2, 3] thiadiazole -7 - carboxylic acid ester derivatives as activator for plant disease agent application
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The invention relates to application of naphtho-[1, 2 and 3] benzothiadiazola-7-carboxylic ester derivative serving as a plant disease-resistant activating agent as shown in a formula (I). Chemical compounds in the series have certain control efficiency on various diseases of plants.
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Paragraph 0098-0099; 0102-0103
(2017/04/29)
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- Palladium on Carbon-Catalyzed Chemoselective Oxygen Oxidation of Aromatic Acetals
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The development of an unprecedented chemoselective transformation has contributed to forming a novel synthetic process for target molecules. Chemoselective oxidation of aromatic acetals has been accomplished using a reusable palladium on carbon catalyst under atmospheric oxygen conditions to form ester derivatives with tolerance of aliphatic acetals and ketals.
- Yasukawa, Naoki,Asai, Shota,Kato, Maho,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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supporting information
p. 5604 - 5607
(2016/11/17)
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- The Development of an Effective Synthetic Route of Belinostat
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A practical synthetic route of belinostat is reported. Belinostat was obtained via a five-step process starting from benzaldehyde and including addition reaction with sodium bisulfite, sulfochlorination with chlorosulfonic acid, sulfonamidation with aniline, Knoevenagel condensation, and the final amidation with hydroxylamine. Key to the strategy is the preparation of 3-formylbenzenesulfonyl chloride using an economical and practical protocol. The main advantages of the route include inexpensive starting materials and acceptable overall yield. The scale-up experiment was carried out to provide 169 g of belinostat with 99.6% purity in 33% total yield.
- Bao, Xuefei,Song, Dake,Qiao, Xuejun,Zhao, Xuan,Chen, Guoliang
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p. 1482 - 1488
(2016/08/30)
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- Facile and efficient synthesis of hydroxyalkyl esters from cyclic acetals through aerobic photo-oxidation using anthraquinone-2-carboxylic acid
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Abstract A convenient metal-free oxidation protocol of various cyclic acetals with molecular oxygen and anthraquinone-2-carboxylic acid under visible light irradiation by a fluorescent lamp afforded their corresponding hydroxyalkyl esters.
- Yamaguchi, Tomoaki,Kudo, Yasuhisa,Hirashima, Shin-ichi,Yamaguchi, Eiji,Tada, Norihiro,Miura, Tsuyoshi,Itoh, Akichika
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p. 1973 - 1975
(2015/03/18)
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- Solid-phase lanthanum catalysis of monoacylation of diols in water by acyl phosphate monoesters
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Lanthanide ions are readily bound to ion-exchange resins. The lanthanide-containing resins serve as immobilized catalysts for the biomimetic monoacylation of diols in water using acyl phosphate monoesters as acylation agents. This method provides an efficient route for recovering the catalyst in the process of modifying RNA derivatives and carbohydrates.
- Dhiman, Raj S.,Wang, Aizhou,Kluger, Ronald
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p. 445 - 450
(2015/04/14)
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- Photoredox removal of p-methoxybenzyl ether protecting group with hydrogen peroxide as terminal oxidant
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We report a mild protocol for removal of the p-methoxybenzyl ether protecting group under acidic conditions with eosin Y combined with LEDs as a photoredox catalysis system and hydrogen peroxide as the terminal oxidant. This protocol is compatible with ethers derived from primary, secondary, and tertiary alcohols, as well as with various functional groups. The protocol showed unusual selectivity for a tertiary ether over a primary ether. The scale up to gram scale is also explored and identical reactivity is observed.
- Liu, Zheng,Zhang, Yi,Cai, Zheren,Sun, Hao,Cheng, Xu
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supporting information
p. 589 - 593
(2015/03/05)
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- New organic nitrate-containing benzyloxy isonipecotanilide derivatives with vasodilatory and anti-platelet activity
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Abstract A number of new nitric oxide (NO)-precursors were synthesized by grafting nitrate-containing moieties on the structures of the benzyloxy isonipecotanilide derivatives 1 and 2 already reported as moderately potent antiplatelet agents. Various nitrooxy (ONO2)-alkyl side chains were covalently linked to the piperidine nitrogen of the parent compounds through carbamate and amide linkage, and the synthesis of a benzyl nitrate analog (15) of compound 1 was also achieved. The in vitro vasodilatory activities, as well as platelet anti-aggregatory effects, of the newly synthesized organic nitrates were assessed. The (ONO2)methyl carbamate-based derivative 5a and the benzyl nitrate analog 15, which on the other hand retain activity as inhibitors of ADP-induced platelet aggregation, exhibited strong NO-mediated vasodilatory effects on pre-contracted rat aorta strips, with EC50 values in the low nanomolar range (13 and 29 nM, respectively). Experiments carried out with the selectively inhibited soluble guanylate cyclase (sGC), which is the key enzyme of the NO-mediated pathway leading to vascular smooth muscle relaxation, confirmed the involvement of NO in the observed vasodilation. The nitrate derivatives proved to be stable in acidic aqueous solution and at pH 7.4. In human serum, unlike 5a, which showed not to undergo enzyme-catalyzed decomposition, the other tested (ONO2)-alkyl carbamate-based compounds (5b and 5e) and benzyl nitrate 15 underwent a faster degradation. However, their decomposition rates in serum were quite slow (t1/2 > 2.6 h), which suggests that nitrate moiety is poorly metabolized in blood plasma and that much of the in vitro anti-platelet activity has to be attributed to the intact (ONO2)-containing molecules.
- De Candia, Modesto,Marini, Elisabetta,Zaetta, Giorgia,Cellamare, Saverio,Di Stilo, Antonella,Altomare, Cosimo D.
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- Tandem catalysis by palladium nanoclusters encapsulated in metal-organic frameworks
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A bifunctional Zr-MOF catalyst containing palladium nanoclusters (NCs) has been developed. The formation of Pd NCs was confirmed by transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS). Combining the oxidation activity of Pd NCs and the acetalization activity of the Lewis acid sites in UiO-66-NH2, this catalyst (Pd@UiO-66-NH2) exhibits excellent catalytic activity and selectivity in a one-pot tandem oxidation-acetalization reaction. This catalyst shows 99.9% selectivity to benzaldehyde ethylene acetal in the tandem reaction of benzyl alcohol and ethylene glycol at 99.9% conversion of benzyl alcohol. We also examined various substituted benzyl alcohols and found that alcohols with electron-donating groups showed better conversion and selectivity compared to those with electron-withdrawing groups. We further proved that there was no leaching of active catalytic species during the reaction and the catalyst can be recycled at least five times without significant deactivation.
- Li, Xinle,Guo, Zhiyong,Xiao, Chaoxian,Goh, Tian Wei,Tesfagaber, Daniel,Huang, Wenyu
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p. 3490 - 3497
(2015/02/19)
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- Efficient and simple approaches towards direct oxidative esterification of alcohols
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The present article describes novel oxidative protocols for direct esterification of alcohols. The protocols involve successful demonstrations of both "cross" and "self" esterification of a wide variety of alcohols. The cross-esterification proceeds under a simple transition-metal-free condition, containing catalytic amounts of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/TBAB (tetra-n-butylammonium bromide) in combination with oxone (potassium peroxo monosulfate) as the oxidant, whereas the self-esterification is achieved through simple induction of Fe(OAc)2/dipic (dipic=2,6-pyridinedicarboxylic acid) as the active catalyst under an identical oxidizing environment. One-pot oxidative esterification: A wide variety of alcohols undergo transition-metal-free (in the presence of oxone/2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)/tetra-n-butylammonium bromide (TBAB)) selective "cross" esterification in moderate to excellent yields (see Figure). The "self" esterification process has however been achieved in the presence of Fe(OAc)2/2,6-pyridinedicarboxylic acid (dipic) as the active catalytic species under a similar oxidizing environment.
- Ray, Ritwika,Jana, Rahul Dev,Bhadra, Mayukh,Maiti, Debabrata,Lahiri, Goutam Kumar
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supporting information
p. 15618 - 15624
(2016/02/18)
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- Transition metal-free oxidative esterification of benzylic alcohols in aqueous medium
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Oxidative esterification of benzylic alcohols with a catalytic amount of HBr-H2O2 in aqueous medium under mild conditions is reported with a wide range of substrate scope for both benzylic and aliphatic alcohols. The conditions are also suitable for selective mono-esterification of ethylene glycol and glycerol. With catalytic amounts of HBr (20 mol%) and H2O2, the generation of reactive intermediate species BrOH has been ascertained by UV-visible spectra.
- Samanta, Supravat,Pappula, Venkatanarayana,Dinda, Milan,Adimurthy, Subbarayappa
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supporting information
p. 9453 - 9456
(2014/12/11)
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- Towards a sustainable synthesis of aniline-derived amides using an indirect chemoenzymatic process: Challenges and successes
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A general, catalytic and sustainable synthesis of amides has been targeted which utilises a chemoenzymatic step to generate an activated amide coupling partner in situ. A screen of a series of known activating agents was performed and the successful agents taken forward to determine their utility in such a one-pot enzyme-catalysed process. In these studies, a new chemoselective reagent ((isopropylideneamino) 2-phenylacetate) has been identified, which demonstrates excellent selectivity for the acylation of primary anilines over secondary anilines, unlike the more conventional acid chloride equivalent, which is unselective. The development of a chemoenzymatic synthesis of 2-hydroxyethyl benzoates (ethylene glycol mono-benzoate esters) has also been achieved.
- Lal, Samridhi,Snape, Timothy J.
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p. 1609 - 1615
(2014/01/06)
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- One-step hydrothermal amino-grafting of graphene oxide as an efficient solid base catalyst
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A one-step hydrothermal route is developed to prepare amino-grafted graphene oxide as an environmentally benign heterogeneous solid base catalyst.
- Zhang, Yicheng,Chen, Chunlin,Wu, Guangjun,Guan, Naijia,Li, Landong,Zhang, Jian
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supporting information
p. 4305 - 4308
(2014/04/17)
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- Reductive removal of methoxyacetyl protective group using sodium borohydride
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Herein, we have developed a mild and selective reductive deprotection method for the MAc protected alcohols using sodium borohydride. The new deprotection conditions provide a complete orthogonality between O-MAc and other protecting groups such as tert-butyl ester, N-Boc, Fmoc, Cbz, O-TBDMS, N-benzyl, O-benzyl, O-acetyl, N-acetyl, N-MAc, etc. In addition to O-MAc deprotection, this method is also applicable for S-MAc deprotection.
- Gadekar, Pradip K.,Hoermann, Maryann,Corbo, Faith,Sharma, Rajiv,Sarveswari,Roychowdhury, Abhijit
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p. 503 - 506
(2014/01/06)
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- Towards a comprehensive hydride donor ability scale
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Rates of hydride transfer from several hydride donors to benzhydrylium ions have been measured at 20 °C and used for the determination of empirical nucleophilicity parameters N and sN according to the linear free energy relationship log k20 °C=sN(N+E). Comparison of the rate constants of hydride abstraction by tritylium ions with those calculated from the reactivity parameters sN, N, and E showed fair agreement. Therefore, it was possible to convert the large number of literature data on hydride abstraction by tritylium ions into N and sN parameters for the corresponding hydride donors, and construct a reactivity scale for hydride donors covering more than 20 orders of magnitude.
- Horn, Markus,Schappele, Ludwig H.,Lang-Wittkowski, Gabriele,Mayr, Herbert,Ofial, Armin R.
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supporting information
p. 249 - 263
(2013/02/25)
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- Novel benzo-1,2,3-thiadiazole-7-carboxylate derivatives as plant activators and the development of their agricultural applications
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Plant activators are a novel kind of agrochemicals that could induce resistance in many plants against a broad spectrum of diseases. To date, only few plant activators have been commercialized. In order to develop novel plant activators, a series of benzo-1,2,3-thiadiazole-7-carboxylate derivatives were synthesized, and the structures were characterized by 1H NMR, IR, elemental analyses, and HRMS or MS. Their potential systemic acquired resistance as plant activators was evaluated as well. Most of them showed good activity, especially, fluoro-containing compounds 3d and 3e, which displayed excellent SAR-inducing activity against cucumber Erysiphe cichoracearum and Colletotrichum lagenarium in assay screening. Field test results illustrated that compounds 3d and 3e were more potent than the commercial plant activator, S-methyl benzo[1,2,3]thiadiazole-7-carbothioate (BTH) toward these pathogens. Further, the preparation of compound 3d is more facile than BTH with lower cost, which will be helpful for further applications in agricultural plant protection.
- Du, Qingshan,Zhu, Weiping,Zhao, Zhenjiang,Qian, Xuhong,Xu, Yufang
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scheme or table
p. 346 - 353
(2012/04/10)
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- Regioselective, borinic acid-catalyzed monoacylation, sulfonylation and alkylation of diols and carbohydrates: Expansion of substrate scope and mechanistic studies
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Synthetic and mechanistic aspects of the diarylborinic acid-catalyzed regioselective monofunctionalization of 1,2- and 1,3-diols are presented. Diarylborinic acid catalysis is shown to be an efficient and general method for monotosylation of pyranoside derivatives bearing three secondary hydroxyl groups (7 examples, 88% average yield). In addition, the scope of the selective acylation, sulfonylation, and alkylation is extended to 1,2- and 1,3-diols not derived from carbohydrates (28 examples); the efficiency, generality, and operational simplicity of this method are competitive with those of state-of-the-art protocols including the broadly applied organotin-catalyzed or -mediated reactions. Mechanistic details of the organoboron-catalyzed processes are explored using competition experiments, kinetics, and catalyst structure-activity relationships. These experiments are consistent with a mechanism in which a tetracoordinate borinate complex reacts with the electrophilic species in the turnover-limiting step of the catalytic cycle.
- Lee, Doris,Williamson, Caitlin L.,Chan, Lina,Taylor, Mark S.
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supporting information; experimental part
p. 8260 - 8267
(2012/07/14)
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- Imidazol(in)ium-2-carboxylates as latent, thermally activated organocatalysts for transesterification reactions
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1,3-Disubstituted imidazol(in)ium-2-carboxylates (ImCO2) were used as precatalysts for transesterification reactions of unactivated ethyl benzoate with monohydric alcohols, dihydric alcohols, and amino alcohols. Highly active N-heterocyclic carbenes (NHCs) are usually not used directly as catalysts because of their air and moisture sensitivity. Here they were liberated in situ by thermal decarboxylation of ImCO2 at designated temperatures. The results showed that the yield of the reactions reached up to 95 within 3 h using only 0.5 mol catalyst. No active enol esters, molecular sieves, or a 20-fold excess of alcohol were used to drive the reaction to completion. It was proved that unsaturated imidazolium-2-carboxylates have a better activity than saturated species in this type of reaction. Different types of substituting groups of ImCO2 exhibited varied transesterification activity.
- Wang, Yanqin,Li, Zhenjiang
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experimental part
p. 502 - 507
(2012/07/17)
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- Imidazol(in)ium-2-carboxylates as Latent, Thermally Activated Organocatalysts for Transesterification Reactions
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1,3-Disubstituted imidazol(in)ium-2-carboxylates (ImCO2) were used as precatalysts for transesterification reactions of unactivated ethyl benzoate with monohydric alcohols, dihydric alcohols, and amino alcohols. Highly active N-heterocyclic carbenes (NHCs) are usually not used directly as catalysts because of their air and moisture sensitivity. Here they were liberated in situ by thermal decarboxylation of ImCO2 at designated temperatures. The results showed that the yield of the reactions reached up to 95% within 3 h using only 0.5 mol% catalyst. No active enol esters, molecular sieves, or a 20-fold excess of alcohol were used to drive the reaction to completion. It was proved that unsaturated imidazolium-2-carboxylates have a better activity than saturated species in this type of reaction. Different types of substituting groups of ImCO2 exhibited varied transesterification activity.
- Wang, Yanqin,Li, Zhenjiang
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p. 502 - 507
(2016/04/10)
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- OPTICAL DEVICES
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The invention relates to optical devices; especially intraocular lens made from high refractive index polymers produced from hydroxyalkyl acrylates and methacrylates containing aromatic groups and carbonyl groups. The invention also relates to the starting monomers, the polymers produced; the application of the same for the manufacture of optical devices and the products derived therefrom.
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Page/Page column 11
(2012/02/05)
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- An efficient photoinduced deprotection of aromatic acetals and ketals
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A novel type of photodeprotection reaction of simple aromatic acetals and ketals is described. The deprotection is highly efficient under optimized conditions. The aromatic ring confers the photoreactivity to the compounds. The efficiency of the process depends on the structure of the acetal moiety. The common minor side reaction, the photooxidation, becomes the major reaction pathway in the cases of cyclic acetals. The use of photon as only reagent makes this procedure especially attractive for acetal deprotection.
- Thevenet, Damien,Neier, Reinhard
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scheme or table
p. 331 - 346
(2011/04/22)
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- Rate-acceleration in gold-nanocluster-catalyzed aerobic oxidative esterification using 1,2- and 1,3-diols and their derivatives
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Aerobic oxidation of aldehydes to 1,2- and 1,3-diol monoesters was catalyzed by polymer-incarcerated gold nanoclusters under ambient conditions. The esterification proceeded much faster with 1,2- and 1,3-diols and their derivatives rather than with methanol. Magnum PI: Gold-nanocluster catalysts, PI-Au, that were immobilized on polystyrene-based polymers with cross-linking moieties, were used to catalyze the syntheses of 1,2 and 1,3-diol monoesters and their derivatives from aldehydes. The effect of neighboring-group participation in the esterification reaction is also described. Copyright
- Yasukawa, Tomohiro,Miyamura, Hiroyuki,Kobayashi, Shu
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experimental part
p. 621 - 627
(2011/10/12)
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- Environmentally friendly transesterification and transacylation reactions under libr catalysis
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A room-temperature, convenient transesterification of various esters, induced by catalytic amounts of lithium bromide and diethylamine in a solvent-free environment, is described. Products are obtained in good purity by simple filtration to remove the catalyst and evaporation of the volatile portion. The procedure has also been successfully applied to transacetylation and aminolysis of esters. Springer-Verlag 2010.
- Abaee, M. Saeed,Akbarzadeh, Elahe,Sharifi, Roholah,Mojtahedi, Mohammad M.
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experimental part
p. 757 - 761
(2011/07/08)
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- Selective mono-acylation of 1,2- and 1,3-diols using (α,α- difluoroalkyl)amines
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In the reaction of N,N-diethyl-α,α-difluorobenzylamine (DFBA) with 1,2- or 1,3-diols, selective mono-benzoylation occurs to afford mono-esters of the diols in good yield. The reaction is completed under mild conditions in a short reaction time. Further, prim-, sec-, and tert-diols and catechol can be converted to the corresponding mono-benzoates. DFBA is used for the protection of the hydroxy group in sugars. The selective mono-nicotinylation, formylation and pivaloylation of diols are also performed by using the corresponding difluoroalkylamines.
- Wakita, Natsumi,Hara, Shoji
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experimental part
p. 7939 - 7945
(2010/10/19)
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- 2-Iodoxybenzoic acid/tetraethylammonium bromide/water: An efficient combination for oxidative cleavage of acetals
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A simple and efficient procedure has been developed for the oxidation of cyclic and acyclic acetals to the corresponding hydroxyalkyl carboxylic esters and simple esters, respectively. 2-Iodoxybenzoic acid (IBX) in the presence of tetraethylammonium bromide was employed for the reaction in aqueous media. The salient features of the protocol include short reaction time, environmentally benign reagents and solvent, and moderate to high yields. Georg Thieme Verlag Stuttgart.
- Kuhakarn, Chutima,Panchan, Waraporn,Chiampanichayakul, Supanimit,Samakkanad, Natthapol,Pohmakotr, Manat,Reutrakul, Vichai,Jaipetch, Thaworn
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experimental part
p. 929 - 934
(2009/10/14)
-
- Experimental and DFT studies on competitive heterocyclic rearrangements. 3. A cascade isoxazole-1,2,4-oxadiazole-oxazole rearrangement
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(Figure Presented) The thermal rearrangements of 3-acylamino-5- methylisoxazoles 1 have been investigated under basic and neutral conditions and interpreted with the support of computational data. The density functional theory (DFT) study on the competitive routes available for the base-catalyzed thermal rearrangement of isoxazoles 1 showed that the Boulton-Katritzky (BK) rearrangement, producing the less stable 3-acetonyl-1,2,4-oxadiazoles 5, is a much more favored process than either the migration-nucleophilic attack-cyclization (MNAC) or the ring contraction-ring expansion (RCRE). In turn, an increase in reaction temperature will promote the MNAC of oxadiazoles 5, producing the more stable 2-acylaminooxazoles 8. The thermal rearrangement of 3-acylaminoisoxazoles 1 into oxazoles 8 can therefore be interpreted in terms of a cascade BK-MNAC rearrangement involving 3-acetonyl-1,2,4-oxadiazoles 5 as ancillary intermediates.
- Pace, Andrea,Pierro, Paola,Buscemi, Silvestre,Vivona, Nicolò,Barone, Giampaolo
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experimental part
p. 351 - 358
(2009/04/11)
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- Highly efficient cyanoimidation of aldehydes
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"Chemical Equation Presented" Cyanoimidation of aldehydes using cyanamide as a nitrogen source and using NBS as an oxidant was achieved in high yields without the addition of a catalyst. The method has several advantages, Including mild conditions, simple workflow, and inexpensive reagents. The reaction proceeds in a one-pot manner, giving rise to the formation of intermolecular C-N and C-O bonds. Subsequently, the substituted W-cyanobenimidate products may also undergo a cyclization reaction to give 1,2,4-triazole derivatives in high yields.
- Yin, Ping,Wen-Bo, Ma.,Chen, Yue,Huang, Wen-Cal,Deng, Yong,He, Ling
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supporting information; experimental part
p. 5482 - 5485
(2010/02/27)
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- Spiro compounds and methods of use
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The present invention relates to spiro compounds of formula I, processes for their preparation, pharmaceutical compositions containing them as active ingredient, methods for the treatment of disease states such as cancers associated with protein tyrosine kinases, especially epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF), to their method of use as medicaments and to their method of use in the manufacture of medicaments for use in the production of inhibition of tyrosine kinase reducing effects in warm-blooded animals such as humans.
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Page/Page column 11
(2010/11/27)
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- PREVENTION AND TREATMENT OF CANCER AND OTHER DISEASES
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Nucleoside chemical compounds, which interact with specific structures of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) are disclosed. The compounds interfere with the activities of telomerase and reverse transcriptase, and are useful as antivirals, antibacterials and anticancer agents. Methods of treating or preventing cancers in patients involving administration of a therapeutically effective amount of a composition having an inhibitor or antagonist of the reverse transcriptases (RTs) expressed in cells of the patients are also disclosed. Method of using nucleoside analogs and other inhibitors of RTs in conjunction with DNA damaging agents such as genotoxic agents or radiation or photodynamic therapy or combinations these for the treatment of various cancers are also disclosed.
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Page/Page column 58-59
(2008/06/13)
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