- Efficient Synthesis of α-Hydroxy-β-ketoesters from Methyl Phenylglyoxalate and Acid Chlorides mediated by Titanium Trichloride
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Methyl phenylglyoxalate and acid chlorides undergo rapid condensation reactions on treatment with a TiCl3-THF/CH2Cl2 solution, in the presence of pyridine, at room temperature.
- Araneo, Silvia,Clerici, Angelo,Porta, Ombretta
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- Solvent Effect in the Reduction of α-Keto Esters by Aqueous Titanium Trichloride
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In the reduction of 1 by Ti(III) ion the dimeric 3 or monomeric 4 reduction products could be made to predominate by the choice of the solvent.It is found that (a) dimerization, via coupling of two radicals 2, increases with increasing simultaneously the dielectric constant and the hydrogen ion concentration of the reaction medium and (b) alcohol formation, which occurs via electron transfer between radical species having different redox potentials, increases with decreasing the hydrogen ion concentration of the medium.Under appropriate reaction conditions, the dimerization process is partially stereoselective.Reaction mechanisms are proposed which account for the ratio of both dimer / alcohol and meso / dl under different experimental conditions.
- Clerici, Angelo,Porta, Ombretta
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- A phosphetane catalyzes deoxygenative condensation of α-keto esters and carboxylic acids via PIII/PV=O redox cycling
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A small-ring phosphacycle is found to catalyze the deoxygenative condensation of α-keto esters and carboxylic acids. The reaction provides a chemoselective catalytic synthesis of α-acyloxy ester products with good functional group compatibility. Based on both stoichiometric and catalytic mechanistic experiments, the reaction is proposed to proceed via catalytic PIII/PV=O cycling. The importance of ring strain in the phosphacyclic catalyst is substantiated by an observed temperature-dependent product selectivity effect. The results point to an inherent distinction in design criteria for organophosphorus-based catalysts operating via PIII/PV=O redox cycling as opposed to Lewis base (nucleophilic) catalysis.
- Zhao, Wei,Yan, Patrick K.,Radosevich, Alexander T.
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- Efficient synthesis of α-aryl serine derivatives via three-component reactions of aryldiazoacetates, anilines and formaldehyde
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A three-component reaction based on trapping of ammonium ylides with formaldehyde was first reported. This reaction offers a new strategy for the synthesis of α-aryl serine derivatives and can be extended to the preparation of α-aryl threonine derivatives. Synthetic application of the three component reaction for the preparation of hydroquinoxaline derivative was also demonstrated.
- Wang, Chengjin,Liu, Shunying,Xing, Dong,Wang, Xin,Wu, Xiang,Hu, Wenhao
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- Mechanistic rationale for the NaBH4 reduction of α-keto esters
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An intramolecular hydride delivery process largely contributes during the double reduction of α-keto esters into diols by NaBH4. In the case of enolic α-keto esters, the first step of the process, the reduction of the keto group, occurred exclusively through an 1,2-hydride addition despite the predominance of the tautomeric enolic form. The clear-cut difference of reaction rate between enolic and non enolic substrate 4 for reaction carried out in methanol is interpreted in terms of competitive hydride consumption due to the extremely favorable reaction between this solvent and NaBH4.
- Dalla,Catteau,Pale
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Read Online
- Biocatalysed reductions of α-ketoesters employing CyreneTM as cosolvent
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The search for novel reaction media with environmental friendly properties is an area of great interest in enzyme catalysis. Water is the medium of biocatalysed processes, but due to its properties, sometimes the presence of organic (co)solvents is required. CyreneTM represents one of the newest approaches to this medium engineering. This polar solvent has been employed for the first time in biocatalysed reductions employing purified alcohol dehydrogenases. A set of α-ketoesters has been reduced to the corresponding chiral α-hydroxyesters with high conversions and optical purities, being possible to obtain good results at Cyrene contents of 30% v/v and working at substrate concentrations of 1.0 M in presence of 2.5% v/v of this solvent. At this concentration, the presence of Cyrene has a beneficial effect in the bioreduction conversion.
- de Gonzalo, Gonzalo
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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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p. 12776 - 12779
(2021/12/10)
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- Design, synthesis and antifungal evaluation of novel mandelic acid derivatives containing a 1,3,4-oxadiazothioether moiety
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A series of novel mandelic acid derivatives containing a 1,3,4-oxadiazothioether moiety were designed and synthesized. Bioassay results showed that some target compounds exhibited certain antifungal activity against six kinds of pathogenic fungi in vitro. Among the compounds, the EC50 values of T41 against Gibberella saubinetii, Verticillium dahlia and Sclerotinia sclerotiorum were 31.0, 27.0 and 32.1?μg/ml, respectively, and the EC50 value of T14 against S. sclerotiorum was 14.7?μg/ml. The antifungal activity against the resistant fungus S. sclerotiorum indicated that this series of target compounds may have the similar action modes or sites as the commercialized succinate dehydrogenase inhibitor carboxin. A morphological study with fluorescence microscope demonstrated that T41 can significantly destroy the membrane integrity of G. saubinetii.
- Hou, Shuaitao,Xie, Dewen,Yang, Jingxin,Niu, Xue,Hu, Deyu,Wu, Zhibing
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p. 166 - 174
(2021/05/29)
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- Benzophenone compound containing 1,thiadiazole thioether structure and application thereof
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The invention discloses a benzophenone compound containing 1,thiadiazole thioether structure, its characterized in that: its structural formula is as follows: Herein R is an alkyl group. Benzyl or substituted benzyl. The invention is based on the structure of mandelic acid derivatives containing '1,oxadiazole thioether'. The 'hydroxyl group' in the compound structure is replaced by '1,thiadiazole thioether', and a series of benzophenone compounds containing 1,thiadiazole thioether structures has been synthesized, and the compound has good bacteriostatic activity on various plant pathogenic bacteria. Compared with a high-activity compound reported in early-stage work of a title group, the compound has a novel 'ketone' structure, shows certain bacteriostatic activity, and provides an important scientific basis for research and development and creation of new pesticides.
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Paragraph 0015-0020
(2021/10/30)
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- Preparation method of carboxylic ester compound
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The invention relates to a preparation method of a carboxylic ester compound, which comprises the following steps: reacting carboxylic acid with methanol in air under the catalysis of nitrite to obtain an ester compound, the preparation method disclosed by the invention has the advantages of rich raw material sources, cheap and easily available catalyst, mild reaction conditions, simplicity and convenience in operation and the like, a series of fatty carboxylic acids can be modified with high yield, and particularly, the traditional esterification method is generally not suitable for esterification of drug molecules. By utilizing the method, a series of known drug molecules can be modified, so that a shortcut is provided for discovering new drug molecules.
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Paragraph 0053-0054
(2021/03/30)
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- Green Esterification of Carboxylic Acids Promoted by tert-Butyl Nitrite
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In this work, the green esterification of carboxylic acids promoted by tert-butyl nitrite has been well developed. This transformation is compatible with a broad range of substrates and exhibits excellent functional group tolerance. Various drugs and substituted amino acids are applicable to this reaction under near neutral conditions, with good to excellent yields.
- Cheng, Xionglve,Jiang, Gangzhong,Li, Xingxing,Tao, Suyan,Wan, Xiaobing,Zhao, Yanwei,Zheng, Yonggao
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supporting information
p. 2713 - 2718
(2021/06/25)
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- Visible Light-Promoted Sulfoxonium Ylides Synthesis from Aryl Diazoacetates and Sulfoxides
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A visible light-promoted reaction of donor/acceptor diazoalkanes with sulfoxides towards the synthesis of synthetically useful sulfoxonium ylides was reported. The reaction occurred under sole visible light irradiation without the need of any transition-metals or additives, affording the corresponding sulfoxonium ylides in moderate to good yields. The success of late-stage modification of natural isolates or drug candidates, scale-up reaction and transformation of sulfoxonium ylides to other useful molecules further rendered the approach valuable.
- Lu, Juan,Li, Lei,He, Xiang-Kui,Xu, Guo-Yong,Xuan, Jun
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p. 1646 - 1650
(2021/05/28)
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- Copper on charcoal: Cu0nanoparticle catalysed aerobic oxidation of α-diazo esters
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By using a charcoal supported nano Cu0catalyst (Cu/C), a highly efficient oxidation of α-diazo esters to α-ketoesters with molecular oxygen as the sole oxidant has been developed. In the presence of the Cu/C catalyst, 2-aryl-α-diazo esters with both electron-donating and electron-withdrawing groups can be oxidized to the corresponding α-ketoesters efficiently. Furthermore, this Cu/C catalyst can catalyse the reaction of aryl α-diazo ester with water to form aryl ketoester, 2-aryl-2-hydroxyl acetate ester and 2-aryl acetate ester. In this case, water is split by α-diazo ester, and the diazo group is displaced by the oxygen or hydrogen atom in water. Mechanistic investigation showed that the reaction of α-diazo ester with oxygen proceeds through a radical pathway. In the presence of 2,2,6,6-tetramethyl piperidine nitrogen oxide, the reaction of α-diazo ester with oxygen is dramatically inhibited. Furthermore, the reaction of α-diazo ester with water is investigated by an isotopic tracer method, and GCMS detection showed that a disproportionation reaction occurred between α-diazo ester and water.
- Chu, Changhu,Dong, Wenwen,Lin, Jia,Teng, Jiangge,Wang, Zhiwei,Zhao, Rong
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supporting information
p. 6120 - 6126
(2021/07/21)
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- Silyl Cyanopalladate-Catalyzed Friedel-Crafts-Type Cyclization Affording 3-Aryloxindole Derivatives
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3-Aryloxindole derivatives were synthesized through a Friedel-Crafts-type cyclization. The reaction was catalyzed by a trimethylsilyl tricyanopalladate complex generated in situ from trimethylsilyl cyanide and Pd(OAc) 2. Wide varieties of diethyl phosphates derived from N -arylmandelamides were converted almost quantitatively into oxindoles. When N, N -dibenzylamide was used instead of an anilide substrate, a benzo-fused δ-lactam was obtained. An oxindole product was subjected to substitution reactions to afford 3,3-diaryloxindoles with two different aryl groups.
- Ece, Hamdiye,Tange, Yuji,Yurino, Taiga,Ohkuma, Takeshi
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supporting information
p. 935 - 939
(2021/02/22)
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- Insights into the Substrate Promiscuity of Novel Hydroxysteroid Dehydrogenases
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Hydroxysteroid dehydrogenases (HSDHs) are valuable biocatalysts for the regio- and stereoselective modification of steroids, bile acids and other steroid derivatives. In this work, we investigated the substrate promiscuity of this highly selective class of enzymes. In order to reach this goal, a preliminary search of HSDH homologues in in-house or public available (meta)genomes was carried out. Eight novel NAD(H)-dependent HSDHs, showing either 7α-, 7β-, or 12α-HSDH activity, and including, for the first time, enzymes from extremophilic microorganisms, were identified, recombinantly produced, and characterized. Among the novel HSDHs, four highly active (up to 92 U mg?1) NAD(H)-dependent 7β-HSDHs showing negligible similarity towards previously described 7β-HSDHs, were discovered. These enzymes, along with previously characterized HSDHs, were tested as biocatalysts for the stereoselective reduction of a panel of substrates including two α-ketoesters of pharmaceutical interest and selected ketones that partially resemble the structural features of steroids. All the reactions were coupled with a suitable cofactor regeneration system. Regarding the α-ketoesters, nearly all of the tested HSDHs showed a good activity toward the selected substrates, yielding the reduced α-hydroxyester with up to 99% conversions and enantiomeric excesses. On the other hand, only the 7β-HSDHs from Collinsella aerofaciens and Clostridium absonum showed appreciable activity toward more complex ketones, i. e., (±)-trans-1-decalone, but with interesting as well as different selectivity. (Figure presented.).
- Bertuletti, Susanna,Ferrandi, Erica Elisa,Marzorati, Stefano,Vanoni, Marta,Riva, Sergio,Monti, Daniela
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p. 2474 - 2485
(2020/05/06)
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- Ultralow-Molecular-Weight Stimuli-Responsive and Multifunctional Supramolecular Gels Based on Monomers and Trimers of Hydrazides
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The simpler, the better. A series of simple, neutral and ultralow-molecular-weight (MW: 140–200) hydrazide-derived supramolecular gelators have been designed and synthesized in two straightforward steps. For non-conjugated cyclohexane-derived hydrazides, their monomers can self-assemble to form gels through intermolecular hydrogen bonds and dipole-dipole interactions. Significantly, conjugated phthalhydrazide can self-aggregate into planar and circular trimers through intermolecular hydrogen bonds and then self-assemble to form gels through intermolecular π–π stacking interactions. It is interesting that these simple gelators exhibit unusual properties, such as self-healing, multi-response fluorescence, and visual and selective recognition of chiral (R)/(S)-1,1′-binaphthalene-2,2′-diamine and S2? through much different times of gel re-formation and blue-green color change, respectively. These results underline the importance of supramolecular gels and extend the scope of supramolecular gelators.
- Wu, Dehua,Song, Jintong,Qu, Lang,Zhou, Weilan,Wang, Lei,Zhou, Xiangge,Xiang, Haifeng
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supporting information
p. 3370 - 3378
(2020/10/02)
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- Biomimetic systems involving sequential redox reactions in glycolysis-the sulfur effect
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Magnesium hemithioacetates were used as model cysteine compounds to mimic natural hemithioacetals, and their biomimetic oxidation reactions using a model NAD+ compound were investigated. Cyclic hemithioacetate was found to be the best substrate for the reaction with the model NAD+ compound, which gave the corresponding NADH analog in excellent yield. This journal is
- Ogawa, Narihito,Furukawa, Sei,Kosugi, Yuya,Takazawa, Takayuki,Kanomata, Nobuhiro
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supporting information
p. 12917 - 12920
(2020/11/05)
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- Synthesis method 2- hydroxyl carboxylic ester (by machine translation)
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The method, is simple 2 - energy consumption, energy consumption is low, the production :(1) of waste water can be greatly reduced, the yield of the target product is high 2 - and the production cost ;(2) is greatly reduced (1). 2 - The method comprises the following steps, preparing 2 - hydroxycarboxylate, with an acid ;(3) by a byproduct ammonium salt (2) in step, and filtering the excess acid, to remove the byproduct ammonium salt, to obtain 2 - hydroxyl carboxylic acid ester product, by esterification reaction in step (, and filtering to remove 2 - the excess, alcohol), from, the reaction, solution obtained by the reaction solution; of the catalyst under the, action of, a catalyst, to obtain the product of the compound. (by machine translation)
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Paragraph 0052; 0054; 0055; 0058-0060
(2020/05/05)
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- Cobalt-Catalyzed Transfer Hydrogenation of α-Ketoesters and N-Cyclicsulfonylimides Using H2O as Hydrogen Source
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A Co-catalyzed effective transfer hydrogenation of various α-ketoesters and N-cyclicsulfonylimides by safe and environmentally benign H2O as hydrogen source is described. The reaction used easily available and easy to handle zinc metal as a reductant. Interestingly, the catalytic system does not require ligand for reduction of N-cyclicsulfonylimides. (Figure presented.).
- Gao, Yang,Zhang, Xuexin,Laishram, Ronibala Devi,Chen, Jingchao,Li, Kangkui,Zhang, Keyang,Zeng, Guangzhi,Fan, Baomin
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supporting information
p. 3991 - 3997
(2019/08/02)
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- Kinetic Resolution of Allylic Alcohol with Chiral BINOL-Based Alkoxides: A Combination of Experimental and Theoretical Studies
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The development and characterization of enantioselective catalytic kinetic resolution of allylic alcohols through asymmetric isomerization with chiral BINOL derivatives-based alkoxides as bifunctional Br?nsted base catalysts were described in the study. A number of chiral BINOL derivatives-based alkoxides were synthesized, and their structure-enantioselectivity correlation study in asymmetric isomerization identified a promising chiral Br?nsted base catalyst, which afforded various chiral secondary allylic alcohols (ee up to 99%, S factor up to >200). In the mechanistic study, alkoxide species were identified as active species and the phenol group of BINOL largely affected the high reactivity and enantioselectivity via hydrogen bonding between the chiral Br?nsted base catalyst and substrates. The strategy is the first successful synthesis strategy of various chiral secondary allylic alcohols through enantioselective transition-metal-free base-catalyzed isomerization. The applicability of the strategy had been demonstrated by the synthesis of the bioactive natural product (+)-veraguensin.
- Liu, Yidong,Liu, Song,Li, Dongmei,Zhang, Nan,Peng, Lei,Ao, Jun,Song, Choong Eui,Lan, Yu,Yan, Hailong
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supporting information
p. 1150 - 1159
(2019/01/11)
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- FeII-catalysed insertion reaction of α-diazocarbonyls into X-H bonds (X = Si, S, N, and O) in dimethyl carbonate as a suitable solvent alternative
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The insertion reaction of a broad range of diazo compounds into Si-H bonds was found to be efficiently catalysed by Fe(OTf)2 in an emerging green solvent i.e. dimethyl carbonate (DMC). The α-silylated products were obtained in good to excellent yields (up to 95%). Kinetic studies showed that the extrusion of N2 to form an iron carbene intermediate is rate-limiting. The iron-catalysed insertion reaction of methyl α-phenyl-α-diazoacetate into polar X-H bonds (S-H, N-H, and O-H) was also established in DMC.
- Tanbouza, Nour,Keipour, Hoda,Ollevier, Thierry
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p. 31241 - 31246
(2019/10/19)
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- Bis(imino)pyridine iron complexes for catalytic carbene transfer reactions
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The bis(imino)pyridine iron complex, for the first time, is developed as an effective metal carbene catalyst for carbene transfer reactions of donor-acceptor diazo compounds. Its broad catalytic capability is demonstrated by a range of metal carbene reactions, from cyclopropanation, cyclopropenation, epoxidation, and Doyle-Kirmse reaction to O-H insertion, N-H insertion, and C-H insertion reactions. The asymmetric cyclopropanation of styrene and methyl phenyldiazoacetate was successfully achieved by the new chiral bis(imino)pyridine iron catalyst, which delivers a new gateway for the development of chiral iron catalysis for metal carbene reactions.
- Wang, Ban,Howard, Isaac G.,Pope, Jackson W.,Conte, Eric D.,Deng, Yongming
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p. 7958 - 7963
(2019/09/06)
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- Boron-catalyzed CC functionalization of allyl alcohols
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Tris(pentafluorophenyl)borane-catalyzed CC bond functionalization of arylallyl alcohols using donor-acceptor carbenes is presented. The allylic hydroxyl group is found to assist the product formation by neighboring group participation providing a clue towards mechanistic understanding. This method can also be employed to effect homologation of allyl alcohols to homoallyl alcohols. Overall, this metal-free transformation presents a novel disconnection strategy towards carbon-carbon bond scission and formation.
- Rao, Santhosh,Kapanaiah, Raja,Prabhu, Kandikere Ramaiah
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p. 1301 - 1306
(2019/10/28)
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- Mechanistic Insights into the Chemo- And Regio-Selective B(C6F5)3 Catalyzed C-H Functionalization of Phenols with Diazoesters
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The Lewis acidic B(C6F5)3 was recently demonstrated to be effective for the C-H alkylation of phenols with diazoesters. The method avoids the general hydroxyl activation in transition-metal catalysis. Ortho-selective C-H alkylation occurs regardless of potential para-selective C-H alkylation and O-H alkylation. In the present study, a theoretical calculation was carried out to elucidate the reaction mechanism and the origin of chemo- and regio-selectivity. It is found that the previously proposed B(C6F5)3/N or B(C6F5)3/C bonding-involved mechanisms are not favorable, and a more favored one involves the B(C6F5)3/C=O bonding, rate-determining N2 elimination, selectivity-determining electrophilic attack, and proton transfer steps. Meanwhile, the new mechanism is consistent with KIE and competition experiments. The facility of the mechanism is attributed to two factors. First, the B(C6F5)3/C=O bonding reduces the steric hindrance during electrophilic attack. Second, the bonding forms the conjugated system by which the LUMO energy is reduced via the electron-withdrawing B(C6F5)3. The ortho-selectivity resulted from the greater ortho-C-C (than para-C-C) interaction and the O-H···O and O-H···F hydrogen-bond interaction during electrophilic attack. The greater C-C (than C-O) interaction and the π-πstacking between the benzene rings of phenol and diazoester concerted contribute to the chemo-selective C-H alkylation.
- Zhang, Qi,Zhang, Xiao-Fei,Li, Mo,Li, Cheng,Liu, Jia-Qin,Jiang, Yuan-Ye,Ji, Xin,Liu, Lu,Wu, Yu-Cheng
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supporting information
p. 14508 - 14519
(2019/11/14)
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- Three-Component Synthesis of Isoquinoline Derivatives by a Relay Catalysis with a Single Rhodium(III) Catalyst
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A rhodium(III)-catalyzed one-pot three-component reaction of N-methoxybenzamide, α-diazoester, and alkyne was developed, providing an alternative way to synthesize isoquinoline derivatives. Mechanistically, it is a relay catalysis, and the reaction occurred via successive O-alkylation and C-H activation processes, both of which were promoted by the same catalyst.
- Zhou, Chao,Jiang, Jijun,Wang, Jun
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supporting information
p. 4971 - 4975
(2019/09/03)
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- Boron-Catalyzed C?C Functionalization of Allyl Alcohols
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Tris(pentafluorophenyl)borane-catalyzed C?C bond functionalization of arylallyl alcohols using donor-acceptor carbenes is presented. The allylic hydroxyl group is found to assist the product formation by neighboring group participation providing a clue towards mechanistic understanding. This method can also be employed to effect homologation of allyl alcohols to homoallyl alcohols. Overall, this metal-free transformation presents a novel disconnection strategy towards carbon-carbon bond scission and formation. (Figure presented.).
- Rao, Santhosh,Kapanaiah, Raja,Prabhu, Kandikere Ramaiah
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- Asymmetric Counter-Anion-Directed Aminomethylation: Synthesis of Chiral β-Amino Acids via Trapping of an Enol Intermediate
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A novel enantioselective aminomethylation reaction of diazo compound, alcohol and α-aminomethyl ether enabled by asymmetric counteranion-directed catalysis is disclosed that offers an efficient and convenient access to furnish optically active α-hydroxyl-β-amino acids in high yield with high to excellent enantioselectivities. Control experiments and DFT calculations indicate that the transformation proceeds through trapping the in situ generated enol intermediate with methylene iminium ion, and the asymmetric induction was enabled by chiral pentacarboxycyclopentadiene anion via H-bonding and electrostatic interaction.
- Kang, Zhenghui,Wang, Yongheng,Zhang, Dan,Wu, Ruibo,Xu, Xinfang,Hu, Wenhao
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supporting information
p. 1473 - 1478
(2019/01/26)
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- A benzo b furyl ketone dye synthesis method (by machine translation)
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The invention relates to a of benzodifaradone dye synthesis method, first to the manufacture of chlorine list alkyl esters, aromatic hydrocarbon as the raw material for Friedel-crafts reaction intermediates 1 or 1 ', then the intermediate 1, intermediate 1' hydrogenation reduction for preparing intermediate 2 and intermediate 2 ', intermediate 2 with condensation product of [...] intermediate 3 with the intermediate 2' condensation reaction to produce intermediate 4, intermediate 4 is oxidized to obtain the benzo b butenolides. The present invention provides a process for synthesis of low cost, low risk, low pollution, the process route is simple without a separate purification process; production and cheap, the cost is far lower than the existing technology, and the product higher total yield can be up to 69%, content is greater than 98.5%, has extremely high economic efficiency, and is suitable for large-scale production, it has good industrial application prospect. (by machine translation)
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Paragraph 0024; 0028; 0031; 0042; 0045
(2018/09/11)
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- Electrolysis promoted reductive amination of electron-deficient aldehydes/ketones: a green route to the racemic clopidogrel
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An electrocatalytic reductive amination of electron-deficient aldehydes/ketones was developed, which could be used in the synthesis of functionalized tertiary amines and large scale preparation of racemic clopidogrel. A plausible mechanism involving an iminium cation intermediate was proposed.
- Zhang, Qianyun,Zhu, Wen,Yao, Jinzhong,Zhou, Hongwei,Li, Xiaofang
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supporting information
p. 8462 - 8466
(2018/12/13)
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- Specific Inhibition of the Hydrogenolysis of Benzylic C?O Bonds Using Palladium Nanoparticles Supported on Nitrogen-Doped Carbon Nanofibers
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Palladium nanoparticles supported on 5 %-nitrogen-doped, herringbone-type carbon nanofibers (Pd/N-CNF-H), which are prepared by thermally decomposing [Pd2(dba)3?CHCl3] (dba=dibenzylideneacetone) in toluene in the presence of N-CNF-H, were found to be an efficient catalyst for the chemoselective hydrogenation of alkenyl and nitro moieties in benzyl-protected alcohols and carboxylic acid derivatives with high turnover frequencies: the hydrogenation reactions of these functional groups proceeded smoothly even at ambient temperature under atmospheric H2 pressure, and the benzyl protecting groups in the molecules remained intact. Moreover, the recovered Pd/N-CNF-H catalyst could be reused without loss of its catalytic activity or chemoselectivity. The Pd/N-CNF-H catalyst also acted as an effective hydrogenation catalyst for the reduction of aromatic ketones to the corresponding benzyl alcohol derivatives with good to high product selectivity.
- Motoyama, Yukihiro,Morii, Koshi,Ishizuka, Shoya,Inomoto, Sou,Zhang, Zhenzhong,Yoon, Seong-Ho
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p. 505 - 509
(2018/02/15)
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- New 4-aryl-1,3,2-oxathiazolylium-5-olates: Chemical synthesis and photochemical stability of a novel series of S-nitrosothiols
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S-nitrosothiols (RSNOs) remain one of the most popular classes of NO-donating compounds due to their ability to release nitric oxide (NO) under non-enzymatic means whilst producing an inert disulphide by-product. However, alligning these compounds to the different biological fields of NO research has proved to be problematic due to the inherent instability of such compounds under a variety of conditions including heat, light and the presence of copper ions. 1,3,2-Oxathiazolylium-5-olates (OZOs) represent an interesting subclass of S-nitrosothiols that lock the –SNO moiety into a five membered heterocyclic ring in an attempt to improve the compound's overall stability. The synthesis of a novel series of halogen-containing OZOs was comprehensively studied resulting in a seven-step route and overall yields ranging between 21 and 37%. The photochemical stability of these compounds was assessed to determine if S-nitrosothiols locked within these mesoionic ring systems can offer greater stability and thereby release NO in a more controllable fashion than their non-cyclic counterparts.
- Eilertsen, Monica,Allin, Steve M.,Pearson, Russell J.
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supporting information
p. 1106 - 1110
(2018/02/28)
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- A containing "1, 3, 4 - oxadiazole thioether" mandelic acid derivatives and use thereof
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The invention discloses a containing "1, 3, 4 - oxadiazole thioether" mandelic acid derivatives and their use in the application of the fungi anti-plants sickness, the compound has the general formula (B) structure shown: In the formula, R1 Is H, methyl, fluorine or chlorine, R2 C for containing1 - 3 Straight-chain alkyl, containing C1 - 4 Branched alkyl, propenyl, propynyl or mono-substituted benzyl, wherein the single substituted benzyl substituent is "nitro, methyl, trifluoromethyl, methoxy, three methoxy, fluorine, and bromine". The invention to replace the mandelic acid as the skeleton, mandelic acid introduced in the structure of the "oxadiazole thioether" structure, design synthesizing a containing "1, 3, 4 - oxadiazole thioether" structure of the mandelic acid derivatives, anti-plant disease fungal activity tests show that the class of compounds of plant diseases caused by fungi has good inhibition activity, for the new pesticide research and development and create provide important scientific basis.
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Paragraph 0025-0028
(2019/01/06)
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- Silica-supported HClO4 promotes catalytic solvent- and metal-free O-H insertion reactions with diazo compounds
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Solvent-free O-H insertion reactions in the presence of diazo carbonyl compounds were carried-out in very mild conditions. Unlike the traditional metal-catalysed version, employing rhodium acetate dimer, this method uses eco-friendly silica-supported HClO4 as the catalyst. Only 0.3 mol% of this Br?nsted acid catalyst, that can also be recycled several times, is necessary to guarantee very good yields (up to 97%) in the O-H insertion reactions. Reaction set-up is simple and permitted the preparation of forty-three α-hydroxy and α-alkoxy esters/ketones in just 1 h and at room temperature.
- Gallo, Rafael Douglas C.,Burtoloso, Antonio C. B.
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p. 4547 - 4556
(2018/10/17)
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- Stereospecific Nucleophilic Substitution with Arylboronic Acids as Nucleophiles in the Presence of a CONH Group
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Stereospecific nucleophilic substitution was achieved for the first time with arylboronic acids as nucleophiles. This transition-metal-free coupling between chiral α-aryl-α-mesylated acetamides and arylboronic acids provided access to a series of chiral α,α-diaryl acetamides with excellent enantioselectivity and moderate to good yields. The CONH functionality proved to be crucial for bridging the reactants and promoting the reaction. Efficient syntheses of a cannabinoid CB1 receptor ligand, the antidepressant (S)-diclofensine, and a key chiral building block of the inhibitor implitapide were successfully accomplished by using this method.
- Tian, Duanshuai,Li, Chengxi,Gu, Guoxian,Peng, Henian,Zhang, Xumu,Tang, Wenjun
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supporting information
p. 7176 - 7180
(2018/05/29)
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- Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,β-alkenoic esters to synthesize γ-ketone esters
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This work concerns the Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,β-alkenoic esters with TMEDA as an additive. The isomerization proceeded under mild conditions and afforded γ-keto esters in high yield (up to 96%) within 2 h. Both (Z)- and (E)-γ-hydroxy-α,β-alkenoic esters were tolerated under the reaction conditions. This transformation involves the in situ formation of a dienolate intermediate from the easily accessible γ-hydroxy-α,β-alkenoic ester. The in situ generated dienolate can react with benzaldehyde and undergo a practical, useful tandem allylic isomerization-Aldol reaction to afford more functionalized compounds.
- Lai, Luhao,Li, A-Ni,Zhou, Jiawei,Guo, Yarong,Lin, Li,Chen, Wei,Wang, Rui
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supporting information
p. 2185 - 2190
(2017/03/17)
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- Chemoenzymatic Preparation of Enantiomerically Enriched (R)-(–)-Mandelic Acid Derivatives: Application in the Synthesis of the Active Agent Pemoline
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The enantioselective resolution of several racemic derivatives of mandelic acid methyl ester catalyzed by lipases from Pseudomonas fluorescens (Amano AK) or Burkholderia cepacia (Amano PS-C II and Amano PS-IM) has been achieved. A gram-scale lipase-mediated kinetic resolution approach has been developed that allows the facile synthesis of the corresponding methyl (R)-(–)-mandelates with excellent enantiomeric excesses (up to >99 % ee) and reaction enantioselectivity (E values up to >200). The dopaminergic agent pemoline, used in the treatment of attention-deficit hyperactivity disorder (ADHD) and narcolepsy, was synthesized with 98 % ee in a straightforward route by condensing the prepared methyl (R)-(–)-mandelate with guanidine hydrochloride under basic conditions. The desired (R)-(+)-pemoline in optically pure form (>99 % ee) was obtained after two recrystallizations from ethanol. However, it was confirmed by chiral HPLC that optically active pemoline undergoes racemization in methanol solution.
- Potera?a, Marcin,Dranka, Maciej,Borowiecki, Pawe?
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p. 2290 - 2304
(2017/05/01)
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- Zirconocene-catalyzed direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio under solvent-free conditions
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A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C-Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.
- Tang, Zhi,Jiang, Qiutao,Peng, Lifen,Xu, Xinhua,Li, Jie,Qiu, Renhua,Au, Chak-Tong
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supporting information
p. 5396 - 5402
(2017/11/22)
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- Mandelic acid derived ionic liquids: synthesis, toxicity and biodegradability
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A series of ten ionic liquids (ILs) was synthesised from the renewable resource mandelic acid. The ILs showed low antimicrobial activity towards the thirteen bacterial and twelve fungal strains they were screened against. A general trend of increasing bacterial toxicity in the order methyl ester 60% in 28 days), a series of biodegradation transformation products has been proposed based on the degradation of the ester/amide alkyl chain. This data has allowed for an assessment of the effect of IL structural features on toxicity and biodegradation, particularly allowing for a comparison to earlier work where additional oxygen atoms were present to facilitate biodegradation and attenuate toxicity. The mandelic acid derived ILs did not pass the Closed Bottle test (OECD 301D) and can be included in the rules of thumb for the design of biodegradable ILs.
- Prydderch, Hannah,Haiβ, Annette,Spulak, Marcel,Quilty, Brid,Kümmerer, Klaus,Heise, Andreas,Gathergood, Nicholas
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p. 2115 - 2126
(2017/01/22)
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- Copper-Catalyzed Carbenoid Insertion Reactions of α-Diazoesters and α-Diazoketones into Si-H and S-H Bonds
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An efficient copper-catalyzed carbenoid insertion reaction of α-diazo carbonyl compounds into Si-H and S-H bonds was developed. A wide range of α-silylesters and α-thioesters was obtained in high yields (up to 98%) from α-diazoesters using 5 mol% of a simple copper(I) salt as catalyst. Using 0.05 mol% of the same catalyst, α-diazoketones led to α-silylketones in low to good yields (up to 70%).
- Keipour, Hoda,Jalba, Angela,Delage-Laurin, Léo,Ollevier, Thierry
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p. 3000 - 3010
(2017/03/23)
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- Multinuclear zinc bisamidinate catalyzed asymmetric alkylation of α-ketoesters and its unique chemoselectivity
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The multinuclear Zn-bisamidinate catalyzed enantioselective addition of Et2Zn to α-ketoesters has been developed. The steric tuning of two amidinate units as well as multiple coordination on the Zn atoms play a key role in achieving high enantioselectivity (up to 98% ee) and unique chemoselectivity. The present catalyst exhibited the preferential alkylation of α-ketoesters even in the presence of aldehydes.
- Yamanaka, Masahiro,Inaba, Masamitsu,Gotoh, Ryo,Ueki, Yoshiyuki,Matsui, Kenichiro
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supporting information
p. 7513 - 7516
(2017/07/12)
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- Ru-MACHO-Catalyzed Highly Chemoselective Hydrogenation of α-Keto Esters to 1,2-Diols or α-Hydroxy Esters
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A ruthenium pincer catalyst has been shown to be highly effective for the hydrogenation of a wide range of α-keto esters, affording either diols or hydroxy esters depending on the choice of reaction conditions. Strong base, high temperature, and pressure favor the formation of diols whilst the opposite is true for the hydroxy esters.
- Gao, Shaochan,Tang, Weijun,Zhang, Minghui,Wang, Chao,Xiao, Jianliang
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supporting information
p. 1748 - 1752
(2016/07/06)
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- Ruthenium Nanoparticles in High-Throughput Studies of Chemoselective Carbonyl Hydrogenation Reactions
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Small (≤1.4 nm) and very active Ru nanoparticles, stabilized in a polysiloxane matrix, were prepared and studied in hydrogenation reactions by the integration of catalysis and analysis. We used our strategy to combine catalytic activity and separation selectivity in a capillary microreactor, installed in a GC-MS instrument, to develop a fast and reliable screening tool for catalysis over Ru nanoparticles. A high conversion using a low catalyst loading of 0.3 mol % and temperature and long-term stability of the catalytically active column were observed for the hydrogenation of various carbonyl compounds, which included aldehydes, ketones, and pyruvates. Additionally, we observed a high chemoselectivity for aromatic carbonyl systems. Comprehensive measurements were performed in this high-throughput experimental setup to gain important insights into the kinetics of hydrogenation reactions at the interface between heterogeneous and homogeneous catalysis.
- Gmeiner, Julia,Behrens, Silke,Spliethoff, Bernd,Trapp, Oliver
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p. 571 - 576
(2016/02/20)
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- (C6F5)3B Catalyzed Chemoselective and ortho-Selective Substitution of Phenols with α-Aryl α-Diazoesters
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The development of an efficient method for the site-selective substitution of unprotected phenols has long been considered as an attractive but challenging task. Herein, we describe a highly chemo- and ortho-selective substitution reaction of phenols with α-aryl α-diazoacetates with commercially available (C6F5)3B as the catalyst. This reaction proceeds under simple and mild conditions with high efficiency, it features a wide substrate scope and can be easily scaled up.
- Yu, Zhunzhun,Li, Yongfeng,Shi, Jiameng,Ma, Ben,Liu, Lu,Zhang, Junliang
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supporting information
p. 14807 - 14811
(2016/11/23)
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- Preparation method of 2-hydroxy acid ester
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The invention relates to a preparation method of 2-hydroxy acid ester and belongs to the technical field of organic synthesis. According to the preparation method of 2-hydroxy acid ester, 2-hydroxy alkyl cyanogens is taken as a raw material to be added to a reaction solution formed by hydrogen chloride, alcohol and water, and after reaction, 2-hydroxy acid ester is obtained. According to the preparation method of 2-hydroxy acid ester, use of a large amount of nonpolar solvent is not needed, and a target product can be obtained by a one-pot method, thus lowering production cost, improving production efficiency and the purify of the target product, and having energy-saving and environment-friendly effects.
- -
-
Paragraph 0040; 0042
(2017/04/11)
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- By 2-hydroxy-c b cyanogen synthesis method of a-hydroxy carboxylic acid ester
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The invention relates to synthesis of alpha-hydroxy carboxylic ester with 2-hydroxy propylene cyanide and corresponding aldehyde or ketone. The existing common alpha-hydroxy carboxylic ester generally needs superior cyan such as trimethylsilyl cyanide, and then hydrolysis is carried out on the cyan, so that the reaction operation is relatively complicated, and post treatment is a trouble. According to the method, 2-hydroxy propylene cyanide and corresponding aldehyde or ketone are mixed directly, 4-dimethylamino-pyridne of the catalysis amount is added, alcohol compound is taken as the solvent, and the product can be obtained by stirring for 10-120 minutes. The method for synthesizing the alpha-hydroxy carboxylic ester is safe and has high efficiency.
- -
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Paragraph 0014-0016
(2016/11/09)
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- Formamides as Lewis Base Catalysts in SNReactions—Efficient Transformation of Alcohols into Chlorides, Amines, and Ethers
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A simple formamide catalyst facilitates the efficient transformation of alcohols into alkyl chlorides with benzoyl chloride as the sole reagent. These nucleophilic substitutions proceed through iminium-activated alcohols as intermediates. The novel method, which can be even performed under solvent-free conditions, is distinguished by an excellent functional group tolerance, scalability (>100 g) and waste-balance (E-factor down to 2). Chiral substrates are converted with excellent levels of stereochemical inversion (99 %→≥95 % ee). In a practical one-pot procedure, the primary formed chlorides can be further transformed into amines, azides, ethers, sulfides, and nitriles. The value of the method was demonstrated in straightforward syntheses of the drugs rac-Clopidogrel and S-Fendiline.
- Huy, Peter H.,Motsch, Sebastian,Kappler, Sarah M.
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supporting information
p. 10145 - 10149
(2016/08/16)
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- Copper-Catalyzed O-Methylation of Carboxylic Acids Using DMSO as a Methyl Source
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A copper-catalyzed O-methylation of carboxylic acids using dimethyl sulfoxide (DMSO) as the methyl source is disclosed. This transformation exhibits a broad substrate scope and excellent functional group tolerance. Mechanistic studies indicate that a methyl radical is generated from dimethyl sulfoxide in the reaction process.
- Jia, Jing,Jiang, Qing,Zhao, An,Xu, Bin,Liu, Qiang,Luo, Wei-Ping,Guo, Can-Cheng
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p. 421 - 428
(2016/01/28)
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- Chiral imidazolidinone and proline-derived surface modifiers for the Pt-catalysed asymmetric hydrogenation of activated ketones
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A series of imidazolidinone and proline derivatives have been synthesised and tested with regard to their suitability for the chiral modification of platinum used for the asymmetric hydrogenation of activated ketones. Hydrogenations of ketopantolactone (KPL), methyl benzoylformate (MBF) and trifluoroacetophenone (TFAP) performed at low hydrogen pressures (1 and 10 bar) were selected as test reactions. With some of these synthethic modifiers, encouraging levels of enantioselectivity were achieved (up to 73.5:26.5 e.r.) without optimisation of the reaction conditions. Moreover, performance enhancement of l-proline derived-modifiers, as a consequence of molecular editing with fluorine, was found to be significant (OH → F, Δee up to 23%) contributing to the growing interest in modulating catalyst performance by fluorine introduction.
- Holland, Mareike C.,Meemken, Fabian,Baiker, Alfons,Gilmour, Ryan
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p. 335 - 345
(2015/02/19)
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- P(NMe2)3-Mediated Umpolung Alkylation and Nonylidic Olefination of α-Keto Esters
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A commercial phosphorus-based reagent (P(NMe2)3) mediates umpolung alkylation of methyl aroylformates with benzylic and allylic bromides, leading to either Barbier-type addition or ylide-free olefination products upon workup. The reaction sequence is initiated by a two-electron redox addition of the tricoordinate phosphorus reagent with an α-keto ester compound (Kukhtin-Ramirez addition). A mechanistic rationale is offered for the chemoselectivity upon which the success of this nonmetal mediated C-C bond forming strategy is based.
- Wang, Sunewang Rixin,Radosevich, Alexander T.
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supporting information
p. 3810 - 3813
(2015/08/18)
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- Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene O-H Insertion Reaction
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Copper- or rhodium-catalyzed reactions of diazocarbonyl compounds with β-hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. Under mild conditions, the single-step process starts as a carbene O-H insertion reaction, but is diverted by an intramolecular aldol reaction. Gone astray: Copper- or rhodium-catalyzed reactions of diazocarbonyl compounds with β-hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. The single-step reaction proceeds under mild conditions, starting as a carbene O-H insertion reaction, but then diverting to an intramolecular aldol reaction.
- Nicolle, Simon M.,Lewis, William,Hayes, Christopher J.,Moody, Christopher J.
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p. 8485 - 8489
(2015/11/27)
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- Metal free chemoselective reduction of α-keto amides using TBAF as catalyst
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The metal and ligand free chemoselective reduction of the keto group and complete reduction of the both keto and amide groups of α-keto amide with hydrosilanes using tetrabutylammoniumflouride (TBAF) as catalyst have been accomplished. This methodology affords an efficient and economic route for the synthesis of biologically important α-hydroxy amides and β-amino alcohols. The other important advantage of this TBAF catalyst is chemoselective reduction of ketones to corresponding alcohols in the presence of several other sensitive functional groups.
- Mamillapalli, N. Chary,Sekar, Govindasamy
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p. 61077 - 61085
(2015/02/19)
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- Commutative reduction of aromatic ketones to arylmethylenes/alcohols by hypophosphites catalyzed by Pd/C under biphasic conditions
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An efficient method is reported to reduce aromatic ketones selectively into arylmethylenes or alcohols with hypophosphites and Pd/C, depending on the selected conditions. This study could represent a promising alternative to the classical uses of standard hydrides or molecular hydrogen involved in reduction and deoxygenation procedures.
- Guyon, Carole,Baron, Marc,Lemaire, Marc,Popowycz, Florence,Métay, Estelle
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p. 2088 - 2095
(2014/03/21)
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- Steric vs. electronic effects in the Lactobacillus brevis ADH-catalyzed bioreduction of ketones
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Lactobacillus brevis ADH (LBADH) is an alcohol dehydrogenase that is commonly employed to reduce alkyl or aryl ketones usually bearing a methyl, an ethyl or a chloromethyl as a small ketone substituent to the corresponding (R)-alcohols. Herein we have tested a series of 24 acetophenone derivatives differing in their size and electronic properties for their reduction employing LBADH. After plotting the relative activity against the measured substrate volumes we observed that apart from the substrate size other effects must be responsible for the activity obtained. Compared to acetophenone (100% relative activity), other small substrates such as propiophenone, α,α, α-trifluoroacetophenone, α-hydroxyacetophenone, and benzoylacetonitrile had relative activities lower than 30%, while medium-sized ketones such as α-bromo-, α,α-dichloro-, and α,α-dibromoacetophenone presented relative activities between 70% and 550%. Moreover, the comparison between the enzymatic activity and the obtained final conversions using an excess or just 2.5 equiv. of the hydrogen donor 2-propanol, denoted again deviations between them. These data supported that these hydrogen transfer (HT) transformations are mainly thermodynamically controlled. For instance, bulky α-halogenated derivatives could be quantitatively reduced by LBADH even employing 2.5 equiv. of 2-propanol independently of their kinetic values. Finally, we found good correlations between the IR absorption band of the carbonyl groups and the degrees of conversion obtained in these HT processes, making this simple method a convenient tool to predict the success of these transformations. The Royal Society of Chemistry.
- Rodriguez, Cristina,Borzecka, Wioleta,Sattler, Johann H.,Kroutil, Wolfgang,Lavandera, Ivan,Gotor, Vicente
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supporting information
p. 673 - 681
(2014/01/06)
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- Kinetic resolution of mandelate esters via stereoselective acylation catalyzed by lipase PS-30
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By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic mandelate esters has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 197.5. Substituent effect is briefly discussed.
- Chen, Peiran,Yang, Wenhong
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supporting information
p. 2290 - 2294
(2014/04/17)
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