- A novel synthetic method for β-keto esters
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A novel synthetic method for the preparation of β-keto esters has been developed. α-Phenylseleno acetate was treated with LDA to produce a selenium-stabilised carbanion, which reacted with aldehydes, followed by selenoxide syn-elimination, to give β-keto esters.
- Qian, Hao,Ge, Chunrong,Huang, Xian
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- Iron Lewis Acid Catalyzed Reactions of Aromatic Aldehydes with Ethyl Diazoacetate: Unprecedented Formation of 3-Hydroxy-2-arylacrylic Acid Ethyl Esters by a Unique 1,2-Aryl Shift
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The iron Lewis acid [η5-(C5H5)Fe(CO)2(THF)]BF 4 (1) was found to catalyze reactions of ethyl diazoacetate (EDA) and aromatic aldehydes, yielding 3-hydroxy-2-arylacrylie acid ethyl esters and the corresponding β-keto esters. According to the literature, this is the first report of the formation of enol esters from EDA and aromatic aldehydes. The yield of the enol esters increased with electronrich aldehydes. With 2,4-dimethoxybenzaldehyde the only product isolated was the corresponding enol ester in 80% yield. However, in the presence of electron-deficient aldehydes such as p-nitrobenzaldehyde, formation of enol ester decreased to 32%. The most unique feature of these reactions is that enol esters are formed by an unusual 1,2-aryl shift, from a possible intermediate 8, which in turn is formed from the reaction of the iron aldehyde complex 7 and EDA.
- Mahmood, Syed J.,Hossain, M. Mahmun
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- Preparation of polystyrene-supported α-seleno acetate and application to solid-phase synthesis of β-keto esters
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A novel polystyrene-supported α-seleno acetate has been developed. This novel resin was treated with LDA to produce a selenium-stabilized carbanion, which reacted with aldehydes, followed by selenoxide syn-elimination to give β-keto esters. Georg Thieme Verlag Stuttgart.
- Qian, Hao,Huang, Xian
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- Amide/Ester Cross-Coupling via C-N/C-H Bond Cleavage: Synthesis of β-Ketoesters
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Activated primary, secondary, and tertiary amides were coupled with enolizable esters in the presence of LiHMDS to obtain good yields of β-ketoesters at room temperature. Notably, this protocol provides an efficient, mild, and high chemoselectivity method
- Chen, Jiajia,Joseph, Devaneyan,Xia, Yuanzhi,Lee, Sunwoo
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p. 5943 - 5953
(2021/04/02)
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- Electrochemical Oxidative Cyclization: Synthesis of Polysubstituted Pyrrole from Enamines
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A conceptually novel method for the preparation of pyrrole is described by electrochemical-oxidation-induced intermolecular annulation via enamines. In a simple undivided cell, based on a sodium acetate-facilitated, polysubstituted pyrrole derivations has been facilely synthesized under external oxidant-free condition. This electrosynthetic approach providing an environmentally benign protocol for C?C bond cross-coupling and oxidative annulation, which features unparalleled broad scope of substrates and practicality.
- Chen, Zhiwei,Shi, Guang,Tang, Wei,Sun, Jie,Wang, Wenxing
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supporting information
p. 951 - 955
(2021/02/03)
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- Construction of isoxazolone-fused phenanthridinesviaRh-catalyzed cascade C-H activation/cyclization of 3-arylisoxazolones with cyclic 2-diazo-1,3-diketones
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A Rh(iii)-catalyzed cascade C-H activation/intramolecular cyclization of 3-aryl-5-isoxazolones with cyclic 2-diazo-1,3-diketones was described, leading to the formation of isoxazolo[2,3-f]phenanthridine skeletons. The protocol features the simultaneous one-pot formation of two new C-C/C-N bonds and one heterocycle in moderate-to-good yields with good functional group compatibility. It is amenable to large-scale synthesis and further transformation.
- Hu, Wangcheng,He, Xinwei,Zhou, Tongtong,Zuo, Youpeng,Zhang, Shiwen,Yang, Tingting,Shang, Yongjia
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supporting information
p. 552 - 556
(2021/02/06)
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- Sulfur-controlled and rhodium-catalyzed formal (3 + 3) transannulation of thioacyl carbenes with alk-2-enals and mechanistic insights
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A rhodium-catalyzed denitrogenative formal (3 + 3) transannulation of 1,2,3-thiadiazoles with alk-2-enals is achieved, producing 2,3-dihydrothiopyran-4-ones in moderate to excellent yields. An inverse KIE of 0.49 is obtained, suggesting the reversibility of the oxidative addition of thioacyl Rh(i) carbenes to alk-2-enals. The late-stage structural modifications of steroid compounds are realized. Moreover, our studies show that thioacyl carbenes have different reactivities to those of α-oxo and α-imino carbenes, and highlight the importance of heteroatoms in deciding the reactivities of heterovinyl carbenes.
- Wu, Qiuyue,Dong, Ziyang,Xu, Jiaxi,Yang, Zhanhui
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supporting information
p. 3173 - 3180
(2021/04/21)
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- Aromaticity-Driven Access to Cycloalkyl-Fused Naphthalenes
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We report the efficient synthesis of cycloalkyl-fused naphthalenes through the [4 + 2]-cycloaddtion/decarboxylative aromatization of alkyne-tethered aryne insertion adducts. These scaffolds were difficult to synthesize using conventional reactions. The reaction proceeds via the formation of a benzopyrylium intermediate followed by intramolecular [4 + 2] cycloaddition and a subsequent decarboxylation pathway. This method is also compatible with allene-tethered substrates to afford similar products. In addition, the one-pot synthesis of polysubstituted naphthalenes via aryne insertion/benzannulation has also been developed in good yield.
- Sanjeev, Karekar,Raju, Silver,Chandrasekhar, Srivari
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supporting information
p. 4013 - 4017
(2021/05/29)
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- Iridium-Catalyzed Enantioselective and Diastereoselective Hydrogenation of Racemic β’-Keto-β-Amino Esters via Dynamic Kinetic Resolution
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An iridium/f-diaphos catalytic system for the enantioselective hydrogenation of α-substituted β-ketoesters via dynamic kinetic resolution is reported. The desired anti β’-hydroxy-β-amino esters were obtained in moderate to good yields (60–95%) with 72–99% ees and 91:9 to 99:1 drs. This protocol tolerates various functional groups and could be easily conducted on gram scale with lower catalyst loading (TON up to 9100). (Figure presented.).
- He, Jiayin,Huang, An,Ling, Fei,Wang, Shiliang,Wang, Yifan,Wang, Ze,Zhao, Xianghua,Zhong, Weihui
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supporting information
p. 4714 - 4719
(2021/09/02)
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- Photoinduced Diverse Reactivity of Diazo Compounds with Nitrosoarenes
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A diverse reactivity of diazo compounds with nitrosoarene in an oxygen-transfer process and a formal [2 + 2] cycloaddition is reported. Nitosoarene has been exploited as a mild oxygen source to oxidize an in situ generated carbene intermediate under visible-light irradiation. UV-light-mediated in situ generated ketenes react with nitosoarenes to deliver oxazetidine derivatives. These operationally simple processes exemplify a transition-metal-free and catalyst-free protocol to give structurally diverse α-ketoesters or oxazetidines.
- Roy, Sourav,Kumar, Gourav,Chatterjee, Indranil
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supporting information
p. 6709 - 6713
(2021/09/08)
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- A Hammett Study of Clostridium acetobutylicum Alcohol Dehydrogenase (CaADH): An Enzyme with Remarkable Substrate Promiscuity and Utility for Organic Synthesis
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Described is a physical organic study of the reduction of three sets of carbonyl compounds by the NADPH-dependent enzyme Clostridium acetobutylicum alcohol dehydrogenase (CaADH). Previous studies in our group have shown this enzyme to display broad substrate promiscuity, yet remarkable stereochemical fidelity, in the reduction of carbonyl compounds, including α-, β- and γ-keto esters (d -stereochemistry), as well as α,α-difluorinated-β-keto phosphonate esters (l -stereochemistry). To better mechanistically characterize this promising dehydrogenase enzyme, we report here the results of a Hammett linear free-energy relationship (LFER) study across three distinct classes of carbonyl substrates; namely aryl aldehydes, aryl β-keto esters and aryl trifluoromethyl ketones. Rates are measured by monitoring the decrease in NADPH fluorescence at 460 nm with time across a range of substrate concentrations for each member of each carbonyl compound class. The resulting v 0 versus [S] data are subjected to least-squares hyperbolic fitting to the Michaelis-Menton equation. Hammett plots of log(V max) versus σ X yield the following Hammett parameters: (i) for p -substituted aldehydes, ρ = 0.99 ± 0.10, ρ = 0.40 ± 0.09; two domains observed, (ii) for p -substituted β-keto esters ρ = 1.02 ± 0.31, and (iii) for p -substituted aryl trifluoromethyl ketones ρ = -0.97 ± 0.12. The positive sign of ρ indicated for the first two compound classes suggests that the hydride transfer from the nicotinamide cofactor is at least partially rate-limiting, whereas the negative sign of ρ for the aryl trifluoromethyl ketone class suggests that dehydration of the ketone hydrate may be rate-limiting for this compound class. Consistent with this notion, examination of the 13 C NMR spectra for the set of p -substituted aryl trifluo romethyl ketones in 2percent aqueous DMSO reveals significant formation of the hydrate (gem -diol) for this compound family, with compounds bearing the more electron-withdrawing groups showing greater degrees of hydration. This work also presents the first examples of the CaADH-mediated reduction of aryl trifluoromethyl ketones, and chiral HPLC analysis indicates that the parent compound α,α,α-trifluoroacetophenone is enzymatically reduced in 99percent ee and 95percent yield, providing the (S)-stereoisomer, suggesting yet another compound class for which this enzyme displays high enantioselectivity.
- Berkowitz, David B.,Kudalkar, Gaurav P.,Lee, Joshua D.,Tiwari, Virendra K.
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supporting information
p. 237 - 247
(2020/02/18)
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- Radical Aza-Cyclization of α-Imino-oxy Acids for Synthesis of Alkene-Containing N-Heterocycles via Dual Cobaloxime and Photoredox Catalysis
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Nitrogen-containing heterocycles are prevalent in both naturally and synthetically bioactive molecules. We report herein an unprecedented protocol for radical aza-cyclization of α-imino-oxy acids with pendant alkenes via synergistic photoredox and cobaloxime catalysis. With or without alkenes as the intermolecular cross-coupling partners, the transformation provides a variety of corresponding alkene-containing dihydropyrrole products in satisfactory yields. In the presence of external alkenes, the tandem reaction generates E-selective coupling products with excellent chemo- and stereoselectivity.
- Tu, Jia-Lin,Liu, Jia-Li,Tang, Wan,Su, Ma,Liu, Feng
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supporting information
p. 1222 - 1226
(2020/02/15)
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- Cu-Mediated Expeditious Annulation of Alkyl 3-Aminoacrylates with Aryldiazonium Salts: Access to Alkyl N2-Aryl 1,2,3-Triazole-carboxylates for Druglike Molecular Synthesis
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Alkyl N-aryl 1,2,3-triazole-carboxylates are important molecules or intermediates in medicinal chemistry, but the synthesis of N2-aryl counterparts remains elusive. Herein, we describe a Cu-mediated annulation reaction of alkyl 3-aminoacrylates with aryldiazonium salts, both of which are readily available substrates. Furthermore, alkyl 2-aminoacrylates are also viable substrates. Diverse alkyl N2-aryl 1,2,3-triazole-carboxylates and their analogues can be rapidly prepared under mild conditions. Especially, this protocol allows one to access several druglike variants of carbonic anhydrase inhibitors and celecoxib.
- Liu, Hao-Nan,Cao, Hao-Qiang,Cheung, Chi Wai,Ma, Jun-An
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supporting information
p. 1396 - 1401
(2020/02/22)
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- An efficient route for the synthesis of N-(1H-benzo[d]imidazol-2-yl)benzamide derivatives promoted by CBr4 in one pot
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A metal-free one-pot method for the synthesis of N-(1H-benzo[d]imidazol-2-yl)benzamide derivatives was proposed mediated by CBr4. The reaction went through ring formation and opening processes with only two protons leaving and the thermodynamically favorable products were selectively formed in moderate to good yields.
- Li, Songhua,Li, Yunyi,Ma, Chen,Xie, Caixia
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- Double Enzyme-Catalyzed One-Pot Synthesis of Enantiocomplementary Vicinal Fluoro Alcohols
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A double-enzyme-catalyzed strategy for the synthesis of enantiocomplementary vicinal fluoro alcohols through a one-pot, three-step process including lipase-catalyzed hydrolysis, spontaneous decarboxylative fluorination, and subsequent ketoreductase-catalyzed reduction was developed. With this approach, β-ketonic esters were converted to the corresponding vicinal fluoro alcohols with high isolated yields (up to 92percent) and stereoselectivities (up to 99percent). This new cascade process addresses some issues in comparison with traditional methods such as environmentally hazardous reaction conditions and low stereoselectivity outcome.
- Fan, Jiajie,Lin, Xianfu,Peng, Yongzhen,Wang, Anlin,Wu, Qi,Xu, Jian,Xu, Weihua,Yu, Huilei
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supporting information
(2020/07/24)
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- Desymmetrization of meso-dicarbonatecyclohexene with β-Hydrazino carboxylic esters via a Pd-catalyzed allylic substitution cascade
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The desymmetrization of meso-dicarbonatecyclohexene with β-hydrazino carboxylic esters has been achieved via a RuPHOX/Pd-catalyzed allylic substitution cascade for the construction of chiral hexahydrocinnoline derivatives with high performance. Mechanistic studies reveal that the reaction exploits a pathway different from that of our previous work and that the first nitrogen nucleophilic process is the rate-determining step. The protocol could be conducted on a gram scale without any loss of catalytic behavior, and the corresponding chiral hexahydrocinnolines can undergo diverse transformations.
- Xu, Kai,Zheng, Yan,Ye, Yong,Liu, Delong,Zhang, Wanbin
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supporting information
p. 8836 - 8841
(2020/11/30)
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- Direct synthesis of 2,3,5-trisubstituted pyrroles: via copper-mediated one-pot multicomponent reaction
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We have developed a copper-mediated one-pot synthesis of 2,3,5-trisubstituted pyrroles from 1,3-dicarbonyl compounds and acrylates using ammonium acetate as a nitrogen source. The reaction achieves C-C and C-N bond formation and provides an efficient approach to access highly functionalized pyrroles without further raw material preparation. This method is operationally simple, compatible with a wide range of functional groups, and provides the target products in moderate to good yields. This journal is
- He, Jian-Ping,Huang, Guo-Sheng,Luo, Nan,Zhan, Zhen-Zhen,Zhang, Ming-Ming
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supporting information
p. 9831 - 9835
(2021/01/05)
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- Synthesis of Dithiolethiones and Identification of Potential Neuroprotective Agents via Activation of Nrf2-Driven Antioxidant Enzymes
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Oxidative stress is implicated in the pathogenesis of a wide variety of neurodegenerative disorders, and accordingly, dietary supplement of exogenous antioxidants or/and upregulation of the endogenous antioxidant defense system are promising for therapeutic intervention or chemoprevention of neurodegenerative diseases. Nrf2, a master regulator of the cellular antioxidant machinery, cardinally participates in the transcription of cytoprotective genes against oxidative/electrophilic stresses. Herein, we report the synthesis of 59 structurally diverse dithiolethiones and evaluation of their neuroprotection against 6-hydroxydopamine-or H2O2-induced oxidative damages in PC12 cells, a neuron-like rat pheochromocytoma cell line. Initial screening identified compounds 10 and 11 having low cytotoxicity but conferring remarkable protection on PC12 cells from oxidative-mediated damages. Further studies demonstrated that both compounds upregulated a battery of antioxidant genes as well as corresponding genes' products. Significantly, silence of Nrf2 expression abolishes cytoprotection of 10 and 11, indicating targeting Nrf2 activation is pivotal for their cellular functions. Taken together, the two lead compounds discovered here with potent neuroprotective functions against oxidative stress via Nrf2 activation merit further development as therapeutic or chemopreventive candidates for neurodegenerative disorders.
- Bai, Feifei,Fang, Jianguo,Song, Zi-Long,Zhang, Baoxin
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p. 2214 - 2231
(2020/03/06)
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- General [4 + 1] Cyclization Approach to Access 2,2-Disubstituted Tetrahydrofurans Enabled by Electrophilic Bifunctional Peroxides
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A general [4 + 1] cyclization reaction of carbonyl nucleophiles with 2-iodomethylallyl peroxides, which function as unique electrophilic oxygen synthons, for the synthesis of a broad range of 2,2-disubstituted tetrahydrofurans is achieved under operationally simple conditions. The unprecedented asymmetric version of such reaction is also realized via chiral auxiliary-assisted cyclization, thus providing a distinct approach to access chiral tetrahydrofurans with high diastereoselectivities. The new method can be applied to the synthesis of core structure of posaconazole drug.
- Gao, Min,Zhao, Yukun,Zhong, Chen,Liu, Shengshu,Liu, Pengkang,Yin, Qi,Hu, Lin
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supporting information
p. 5679 - 5684
(2019/08/01)
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- Switching of Sulfonylation Selectivity by Nature of Solvent and Temperature: The Reaction of β-Dicarbonyl Compounds with Sodium Sulfinates under the Action of Iron-Based Oxidants
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Selectivity of sulfonylation of β-keto esters with sodium sulfinates under the action of iron(III) salts as oxidants can be regulated by the type of solvent used and the reaction temperature. α-Sulfonyl β-keto esters are obtained when the process is conducted in THF/H2O solution at 40 °C. The change of the solvent to iPrOH/H2O and refluxing of a reaction mixture provides α-sulfonyl esters – the products of successive sulfonylation-deacylation. When β-diketones are applied as starting materials, only α-sulfonyl ketones are formed. The reaction pathway includes sulfonylation of dicabonyl compounds under the action of Fe(III) to form α-sulfonylated dicarbonyl compounds, which are then attacked by a solvent as the nucleophile, resulting in the products of successive sulfonylation-deacylation. Participation of the solvent in the reaction pathway determines the products structure.
- Mulina, Olga M.,Pirgach, Dmitry A.,Nikishin, Gennady I.,Terent'ev, Alexander O.
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supporting information
p. 4179 - 4188
(2019/05/08)
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- Synthesis and biochemical evaluation of lid-open D-amino acid oxidase inhibitors
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Most of the known inhibitors of D-amino acid oxidase (DAAO) are small polar molecules recognized by the active site of the enzyme. More recently a new class of DAAO inhibitors has been disclosed that interacts with loop 218?224 at the top of the binding pocket. These compounds have a significantly larger size and more beneficial physicochemical properties than most reported DAAO inhibitors, however, their structure-activity relationship is poorly explored. Here we report the synthesis and evaluation of this type of DAAO inhibitors that open the lid over the active site of DAAO. In order to collect relevant SAR data we varied two distinct parts of the inhibitors. A systematic variation of the pendant aromatic substituents according to the Topliss scheme resulted in DAAO inhibitors with low nanomolar activity. The activity showed low sensitivity to the substituents investigated. The variation of the linker connecting the pendant aromatic moiety and the acidic headgroup revealed that the interactions of the linker with the enzyme were crucial for achieving significant inhibitory activity. Structures and activities were analyzed based on available X-ray structures of the complexes. Our findings might support the design of drug-like DAAO inhibitors with advantageous physicochemical properties and ADME profile.
- Szilágyi, Bence,Hargitai, Csilla,Kelemen, ádám A.,Rácz, Anita,Ferenczy, Gy?rgy G.,Volk, Balázs,Keser?, Gy?rgy M.
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supporting information
(2019/01/31)
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- Two Competitive but Switchable Organocatalytic Cascade Reaction Pathways: The Diversified Synthesis of Chiral Acetal-Containing Bridged Cyclic Compounds
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The organocatalytic enantioselective synthesis of methanobenzodioxepine derivatives bearing a 6,6,5-bridged ring system is presented. The m-CPBA-triggered in situ α-oxidation of β-oxoesters to provide the required but unstable α-hydroxy-β-dicarbonyl substrates is the key to this three-step sequence, providing the desired cyclic acetals with excellent stereoselectivities containing two bridgehead and one fully substituted stereocenters. It is noteworthy that the absence of m-CPBA furnished the acetal products bearing a 6,6,6-bridged ring system with similar good results from the same starting materials.
- Lv, Xue-Jiao,Chen, Ying-Han,Liu, Yan-Kai
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supporting information
p. 190 - 195
(2019/01/11)
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- Catalytic Mechanism Study on the 1,2- and 1,4-Transfer Hydrogenation of Ketimines and β-Enamino Esters Catalyzed by Axially Chiral Biscarboline-Based Alcohols
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Axial N-O alcohols, which have two large carboline moieties connected to the axis were synthesized and used in catalytic enantioselective 1,2- and 1,4-transfer hydrogenations of total 26 ketimines and β-enamino esters. Excellent levels of enantioselectivity ranging from 91% to 99% were achieved by using catalyst (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide. Interestingly, a mixture of (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide and (aR)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide was also able to provide high enantioselectivities up to 95% that is the same as that using pure (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide. A plausible catalytic mechanism was suggested and total four kinds of transition states (TS) including almost 60 TS structures were investigated using density functional theory (DFT) with different basis sets such as 6-311G(2d,p). The predicted activation energy data are consistent with the experimental results. (Figure presented.).
- Dong, Mengxian,Wang, Jie,Wu, Shijie,Zhao, Yang,Ma, Yangyang,Xing, Yongfei,Cao, Fei,Li, Longfei,Li, Zhenqiu,Zhu, Huajie
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supporting information
p. 4602 - 4610
(2019/08/30)
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- Toward Continuous-Flow Synthesis of Biologically Interesting Pyrazole Derivatives
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A two-step continuous-flow synthesis of substituted pyrazole derivatives has been developed via the formation of vinylidene keto esters as key intermediates. Heterogeneous Ni2+-montmorillonite was found to be an efficient catalyst for orthoester condensation of 1,3-dicarbonyls under flow conditions. The intermediate reacted with methylhydrazine to afford pyrazole derivatives, for which suitable selection of a solvent played a key role in achieving high yields and excellent regioselectivities of the desired products. An application of this protocol has been demonstrated by the synthesis of a key intermediate for biologically active pyrazoles such as Bixafen. (Figure presented.).
- Das, Amrita,Ishitani, Haruro,Kobayashi, Shū
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supporting information
p. 5127 - 5132
(2019/11/13)
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- Pyrazole alcohol compound, pharmaceutical composition thereof and application thereof to drugs
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The invention discloses a 1-(3,5,6-trimethyl pyrazine-2-yl)-5-pyrazole alcohol compound, a tautomer thereof, a pharmaceutical composition thereof and application thereof to drugs. The 1-(3,5,6-trimethyl pyrazine-2-yl)-5-pyrazole alcohol compound has double effects of resisting platelet aggregation and protecting nerve cells, and comprises a compound as shown in the formula (I), a tautomer (Ia) thereof, or a stereoisomer, a geometrical isomer, a hydrate or a solvate thereof, or a pharmaceutically acceptable salt or prodrug as shown in the description. The 1-(3,5,6-trimethyl pyrazine-2-yl)-5-pyrazole alcohol compound and the pharmaceutical composition thereof provided by the invention can be used for preparing drugs for prevention and/or treatment and/or auxiliary treatment of cerebral apoplexy, cardiovascular and cerebrovascular diseases, senile dementia and complications thereof caused by thrombosis and excessive free radicals.
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Paragraph 0128; 0134
(2018/10/19)
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- Substituted phenyl pyrazolone derivatives and preparation and application (by machine translation)
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The present invention provides a substituted phenyl pyrazolone derivatives, in particular to a 2 - phenyl - pyrazoline - 3 - ketone compound and its pharmaceutically acceptable salt, solvate. The substituted acetic acid ethyl ester with sodium hydroxide in aqueous solution in the [...] reflux reaction, then in the palladium-carbon and hydrogen under the action of the hydrogenolysis benzyl, phenyl [...] obtained, with the bromochlorodifluoromethane alkane reaction to obtain the chloro, finally with the secondary amine on the condensation to obtain the target compound. The invention substituted phenyl pyrazoline compounds in vitro exhibits excellent capability of eliminating the free radicals, and have more strongly inhibit H3 receptor activity, exhibits excellent penetration of the blood brain barrier capacity, has a unique dual active, therefore, its for cerebral apoplexy, Alzheimer's disease, Parkinson's disease, progressive neurodegenerative diseases such as frozen sickness treatment has a unique clinical effect. The compound of the invention for treating central system system related disease and inflammatory disease application of the medicament. The formula structure is as follows: (by machine translation)
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Paragraph 0034; 0039; 0040
(2019/01/08)
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- Identification of Novel Coumestan Derivatives as Polyketide Synthase 13 Inhibitors against Mycobacterium tuberculosis
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Inhibition of the mycolic acid pathway has proven a viable strategy in antitubercular drug discovery. The AccA3/AccD4/FadD32/Pks13 complex of Mycobacterium tuberculosis constitutes an essential biosynthetic mechanism for mycolic acids. Small molecules targeting the thioesterase domain of Pks13 have been reported, including a benzofuran-based compound whose X-ray cocrystal structure has been very recently solved. Its initial inactivity in a serum inhibition titration (SIT) assay led us to further probe other structurally related benzofurans with the aim to improve their potency and bioavailability. Herein, we report our preliminary structure-activity relationship studies around this scaffold, highlighting a natural product-inspired cyclization strategy to form coumestans that are shown to be active in SIT. Whole genome deep sequencing of the coumestan-resistant mutants confirmed a single nucleotide polymorphism in the pks13 gene responsible for the resistance phenotype, demonstrating the druggability of this target for the development of new antitubercular agents.
- Zhang, Wei,Lun, Shichun,Wang, Shu-Huan,Jiang, Xing-Wu,Yang, Fan,Tang, Jie,Manson, Abigail L.,Earl, Ashlee M.,Gunosewoyo, Hendra,Bishai, William R.,Yu, Li-Fang
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p. 791 - 803
(2018/02/17)
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- In situ generation of nitrile oxides from copper carbene and tert -butyl nitrite: Synthesis of fully substituted isoxazoles
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Herein, we present a novel [3 + 2] cycloaddition reaction of β-keto esters with nitrile oxides, which were generated in situ from copper carbene and tert-butyl nitrite. This three-component reaction provides new methodology for the direct synthesis of fully substituted isoxazole derivatives, featuring mild reaction conditions, readily accessible starting materials and simple operation. The experimental studies and DFT calculations suggest that the reaction starts with the generation of the key intermediate nitrile oxides, followed by a [3 + 2] cycloaddition reaction of β-keto esters to give the final isoxazole products.
- Chen, Rongxiang,Ogunlana, Abosede Adejoke,Fang, Shangwen,Long, Wenhao,Sun, Hongmei,Bao, Xiaoguang,Wan, Xiaobing
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supporting information
p. 4683 - 4687
(2018/07/06)
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- Iridium-Catalyzed Asymmetric Hydrogenation of Tetrasubstituted α-Fluoro-β-enamino Esters: Efficient Access to Chiral α-Fluoro-β-amino Esters with Two Adjacent Tertiary Stereocenters
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An iridium-catalyzed highly efficient asymmetric hydrogenation of challenging tetrasubstituted α-fluoro-β-enamino esters was successfully developed using bisphosphine-thiourea (ZhaoPhos) as the ligand, which prepared a series of chiral α-fluoro-β-amino esters containing two adjacent tertiary stereocenters with high yields and excellent diastereoselectivities/enantioselectivities (73%-99% yields, >25:1 dr, 91%>99% ee, and turnover number (TON) values up to 8600), and no defluorinate byproduct was detected.
- Han, Zhengyu,Guan, Yu-Qing,Liu, Gang,Wang, Rui,Yin, Xuguang,Zhao, Qingyang,Cong, Hengjiang,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 6349 - 6353
(2018/10/15)
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- One-pot multistep mechanochemical synthesis of fluorinated pyrazolones
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Solventless mechanochemical synthesis represents a technique with improved sustainability metrics compared to solvent-based processes. Herein, we describe a methodical process to run one solventless reaction directly into another through multistep mechanochemistry, effectively amplifying the solvent savings. The approach has to consider the solid form of the materials and compatibility of any auxiliary used. This has culminated in the development of a two-step, one-jar protocol for heterocycle formation and subsequent fluorination that has been successfully applied across a range of substrates, resulting in 12 difluorinated pyrazolones in moderate to excellent yields.
- Howard, Joseph L.,Nicholson, William,Sagatov, Yerbol,Browne, Duncan L.
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supporting information
p. 1950 - 1956
(2017/09/27)
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- The synthesis and evaluation of triazolopyrimidines as anti-tubercular agents
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We identified a di-substituted triazolopyrimidine with anti-tubercular activity against Mycobacterium tuberculosis. Three segments of the scaffold were examined rationally to establish a structure-activity relationship with the goal of improving potency and maintaining good physicochemical properties. A number of compounds displayed sub-micromolar activity against Mycobacterium tuberculosis with no cytotoxicity against eukaryotic cells. Non-substituted aromatic rings at C5 and a two-carbon chain connecting a terminal aromatic at C7 were preferred features; the presence of NH at C7 and a lack of substituent at C2 were essential for potency. We identified compounds with acceptable metabolic stability in rodent and human liver microsomes. Our findings suggest that the easily-synthesized triazolopyrimidines are a promising class of potent anti-tubercular agents and warrant further investigation in our search for new drugs to fight tuberculosis.
- Zuniga, Edison S.,Korkegian, Aaron,Mullen, Steven,Hembre, Erik J.,Ornstein, Paul L.,Cortez, Guillermo,Biswas, Kallolmay,Kumar, Naresh,Cramer, Jeffrey,Masquelin, Thierry,Hipskind, Philip A.,Odingo, Joshua,Parish, Tanya
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p. 3922 - 3946
(2017/07/05)
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- Rhodium-catalyzed asymmetric hydrogenation of tetrasubstituted β-acetoxy-α-enamido esters and efficient synthesis of droxidopa
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A rhodium-catalyzed asymmetric hydrogenation of challenging tetrasubstituted β-acetoxy-α-enamido esters was developed, giving chiral β-acetoxy-α-amido esters in high yields with excellent enantioselectivities (up to >99% ee). The products could be easily transformed to β-hydroxy-α-amino acid derivatives which are valuable chiral building blocks and a novel route for the synthesis of droxidopa was also developed.
- Guan, Yu-Qing,Gao, Min,Deng, Xu,Lv, Hui,Zhang, Xumu
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supporting information
p. 8136 - 8139
(2017/07/24)
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- Bromide-Mediated C-H Bond Functionalization: Intermolecular Annulation of Phenylethanone Derivatives with Alkynes for the Synthesis of 1-Naphthols
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Bromide-mediated intermolecular annulation of phenylethanone derivatives with alkynes has been developed, which allows for the regioselective formation of polysubstituted 1-naphthols. The usage of readily available bromine catalyst, broad substrate scope, and mild conditions make this protocol very practical. Mechanistic investigations reveal that the bromination of phenylethanone derivatives occurs to yield bromo-substituted intermediates, which react in situ with alkynes to furnish the desired 1-naphthols.
- Lu, Tao,Jiang, Ya-Ting,Ma, Feng-Ping,Tang, Zi-Jing,Kuang, Liu,Wang, Yu-Xuan,Wang, Bin
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supporting information
p. 6344 - 6347
(2017/12/08)
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- Reformatsky and Blaise reactions in flow as a tool for drug discovery. One pot diversity oriented synthesis of valuable intermediates and heterocycles
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The application of Reformatsky and Blaise reactions for the preparation of a diverse set of valuable intermediates and heterocycles in a one-pot protocol is described. To achieve this goal, a greener activation protocol for zinc in flow conditions has been developed to introduce this metal efficiently into α-bromoacetates. The organozinc compounds were added to a diverse set of ketones and nitriles to obtain a wide range of functional groups and heterocyclic systems.
- Huck,Berton,De La Hoz,Díaz-Ortiz,Alcázar
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supporting information
p. 1420 - 1424
(2017/05/12)
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- Enantioselective Synthesis of 3,5,6-Substituted Dihydropyranones and Dihydropyridinones using Isothiourea-Mediated Catalysis
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The scope of dihydropyranone and dihydropyridinone products accessible by isothiourea-catalyzed processes has been expanded and explored through the use of 2-N-tosyliminoacrylates and 2-aroylacrylates in a Michael addition-lactonization/lactamization cascade reaction. Notably, to ensure reproducibility it is essential to use homoanhydrides as ammonium enolate precursors with 2-aroyl acrylates, while carboxylic acids can be used with 2-N-tosyliminoacrylates, delivering a range of 3,5,6-substituted dihydropyranones and dihydropyridinones with high enantioselectivity (typically >90 % ee). The derivatization of the heterocyclic core of a 3,5,6-substituted dihydropyranone through hydrogenation is also reported.
- Stark, Daniel G.,Morrill, Louis C.,Cordes, David B.,Slawin, Alexandra M. Z.,O'Riordan, Timothy J. C.,Smith, Andrew D.
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supporting information
p. 395 - 400
(2016/05/19)
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- Regioselective Synthesis of Dihydrothiophenes and Thiophenes via the Rhodium-Catalyzed Transannulation of 1,2,3-Thiadiazoles with Alkenes
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A method for the regioselective synthesis of a wide range of dihydrothiophenes was developed from the rhodium-catalyzed transannulation of 1,2,3-thiadiazoles with aliphatic, aromatic, and heteroaromatic alkenes. Tandem rhodium-catalyzed transannulation of 1,2,3-thiadiazoles with alkenes followed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) oxidation was also demonstrated for the one-pot regioselective synthesis of various thiophenes. Advantages of the present method include a broad substrate scope, wide functional group compatibility, and high regioselectivity.
- Son, Jeong-Yu,Kim, Jonghye,Han, Sang Hoon,Kim, Sung Hong,Lee, Phil Ho
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supporting information
p. 5408 - 5411
(2016/11/06)
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- A one-pot copper(II)-catalyzed tandem synthesis of 2-substituted pyrrolo[1,2-b]pyridazin-4(1H)-ones
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A one-pot copper(II)-catalyzed tandem synthesis of 2-substituted pyrrolo[1,2-b]pyridazin-4(1H)-ones from N-aminopyrroles was developed. This tandem reaction involves a Conrad-Limpach-type reaction, including the thermal condensation of N-aminopyrroles with the carbonyl group of β-oxo esters followed by the cyclization of Schiff base intermediates. Compared to the traditional Conrad-Limpach quinoline synthesis, we herein successfully applied copper(II) as a catalyst in this transformation to furnish 2-substituted pyrrolo[1,2-b]pyridazin-4(1H)-ones for the first time. Most of the substrates bearing electron-donating (EDG) and electron-withdrawing (EWG) groups worked well with this procedure. The corresponding products could be converted directly into diverse pyrrolo[1,2-b]pyridazine for drug discovery and materials science. A copper(II)-catalyzed tandem synthesis of 2-substituted pyrrolo[1,2-b]pyridazin-4(1H)-ones from N-aminopyrroles was developed, and the corresponding products could be converted directly into diverse pyrrolo[1,2-b]pyridazine for drug discovery and materials science.
- Tan, Cun,Xiang, Haoyue,He, Qian,Yang, Chunhao
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supporting information
p. 3656 - 3660
(2015/06/16)
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- 1,5-Diketones Synthesis via Three-Component Cascade Reaction
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A mild and efficient cascade synthesis of 1,5-diketones from readily available N,N-dicyclohexylmethylamine, 1,3-dicarbonyl compounds, and trifluoromethyl β-diketones has been developed. This cascade reaction occurs via an oxidation/Mannich reaction/Cope elimination/Michael addition/retro-Claisen reaction sequence, and provides multiple C-C bond formations in one pot. In addition, exquisite chemoselectivity is achieved in the reaction between 1,3-dicarbonyl compounds and trifluoromethyl β-diketones.
- Xing, Li-Juan,Lu, Tao,Fu, Wei-Li,Lou, Mei-Mei,Chen, Bo,Wang, Zhi-Shen,Jin, Yang,Li, Dan,Wang, Bin
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supporting information
p. 3076 - 3080
(2015/11/03)
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- Synthesis and biological evaluation of pyrazolo[3,4-b]pyridin-4-ones as a new class of topoisomerase II inhibitors
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A series of 1,3,6-triphenylpyrazolo[3,4-b]pyridin-4-one derivatives was designed, synthesized and evaluated for cytotoxic activity in A375 human melanoma and human erythroleukemia (HEL) cells. The new pyrazolopyridones displayed comparable activities to the antitumor compound etoposide. The inhibitory effect of compounds 17, 18, 27 and 32 against topoisomerase II-mediated cleavage activities was measured finding good correlation with the results obtained from MTS assay. Docking studies into bacterial topoisomerase II (DNA Gyrase), topoisomerase IIα and topoisomerase IIβ binding sites in the DNA binding interface were performed.
- Tabrizi, Mojgan Aghazadeh,Baraldi, Pier Giovanni,Baraldi, Stefania,Prencipe, Filippo,Preti, Delia,Saponaro, Giulia,Romagnoli, Romeo,Gessi, Stefania,Merighi, Stefania,Stefanelli, Angela,Fazzi, Debora,Borea, Pier Andrea,Maia, Rodolfo Couto,Romeiro, Nelilma C.,Fraga, Carlos A.M.,Barreiro, Eliezer J.
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p. 342 - 353
(2016/10/11)
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- A copper-mediated oxidative coupling route to 3H- and 1H-indoles from N-aryl-enamines
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A facile copper(II)-mediated C-H bond oxidation and C-C bond formation procedure has been applied to the synthesis of indole derivatives. Intramolecular oxidative coupling of 3,3-disubstituted enamines proceeded using a non-expensive and air-stable copper
- Drouhin, Pauline,Taylor, Richard J. K.
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supporting information
p. 2333 - 2336
(2015/04/22)
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- Enantioselective Mannich reaction of β-keto esters with aromatic and aliphatic imines using a cooperatively assisted bifunctional catalyst
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An efficient urea-enhanced thiourea catalyst enables the enantioselective Mannich reaction between β-keto esters and N-Boc-protected imines under mild conditions and minimal catalyst loading (1-3 mol %). Aliphatic and aromatic substituents are tolerated on both reaction partners, affording the products in good enantiomeric purity. The corresponding β-amino ketones can readily be accessed via decarboxylation without loss of enantiomeric purity.
- Neuvonen, Antti J.,Pihko, Petri M.
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supporting information
p. 5152 - 5155
(2015/01/08)
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- Manganese(III)-mediated direct Csp2-H radical trifluoromethylation of coumarins with sodium trifluoromethanesulfinate
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Mn(OAc)3-mediated direct Csp2-H radical trifluoromethylation of coumarins with CF3SO2Na (Langlois reagent) to afford selective 3-trifluoromethyl coumarins in moderate to good yields is described. This methodology can also be applied to the trifluoromethylation of quinolinones and pyrimidinones. The Royal Society of Chemistry 2014.
- Cao, Xiao-Hui,Pan, Xiangqiang,Zhou, Peng-Jun,Zou, Jian-Ping,Asekun, Olayinka Taiwo
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supporting information
p. 3359 - 3362
(2014/03/21)
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- Synthesis and spectroscopic studies of N,N'-dialkyl derivatives of antisymmetrical 2h,5h-dihydropyrrolo[3,4-c]pyrrole-1,4-diones
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2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione derivatives (DPP) are chemically stable, fluorescent molecules, known as High Performance Pigments. Preparation of the soluble derivatives of DPPs provides great advantage in designing the optic sensor for new and existing applications and overcoming aggregation problems in solid matrices. For this purpose, the synthesis of antisymmetric DPPs and the formation of new organic dyes through N,N'-dialkylation and their spectroscopic studies have been carried out both in solutions and in solid phase.
- Erbas, Secil Celik,Alp, Serap
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p. 329 - 335
(2014/05/06)
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- Base initiated aromatization/CO bond formation: A new entry to O-pyrazole polyfluoroarylated ethers
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A base initiated intermolecular SNAr reaction of pyrazolones with polyfluoroarenes was developed. The process involved the isomerization aromatization of pyrazolone followed by the CO bond formation via the selective CF bond cleavage. With this strategy, a wide range of O-pyrazole polyfluoroarylated ethers bearing diverse functional groups were synthesized in mild to good yields. Additionally, our method was also applied to the isoxazol substrates.
- Tang, Xiangyang,Chang, Jing,Liu, Cuibo,Zhang, Bin
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supporting information
p. 6534 - 6537
(2015/01/08)
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- One pot direct synthesis of β-ketoesters via carbonylation of aryl halides using cobalt carbonyl
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A direct method for the synthesis of β-ketoesters from aryl halides (iodide, bromide) has been described by using cobalt carbonyl as carbon monoxide source in microwave irradiation. Using this protocol, a wide variety of substituted aryl halides has been successfully converted to corresponding β-ketoesters.
- Baburajan, Poongavanam,Elango, Kuppanagounder P.
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supporting information
p. 3525 - 3528
(2014/06/10)
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- Novel photosensitized cyclization reactions of ethyl 3-amino-3-phenyl-2- propenoate derivatives to highly substituted pyrroles
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Irradiation of nitrogen-saturated acetonitrile solutions containing ethyl 3-amino-3-phenyl-2-propenoate derivatives with the (Z)-configuration [(Z)- 1] and 10-methylacridinium perchlorate (MAP) at wavelengths longer than 340 nm afforded the corresponding pyrrole derivatives in good to high yields without exhibiting a profound effect related to the substituents. An analysis of the Stern-Volmer plots for the fluorescence quenching of MAP by (Z)-1 showed that this sensitizer fluorescence is efficiently quenched, and hence electron transfer is confirmed to be involved in the primary process of the MAPsensitized cyclization reactions of 1.
- Ishida, Yohsuke,Yoshida, Yuhki,Igarashi, Tetsutaro,Sakurai, Tadamitsu
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p. 1691 - 1698
(2013/09/12)
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- Tert-BuOK-Catalyzed condensation of ethyl diazoacetate to aldehydes and palladium-catalyzed 1,2-hydrogen migration for the synthesis of β-ketoesters under solvent-free conditions
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A mild and convenient method for the condensation of ethyl diazoacetate (EDA) with aldehydes catalyzed by tert-BuOK under solvent-free conditions was developed. The corresponding α-diazo-β-hydroxy esters were further converted into β-ketoesters through palladium-catalyzed 1,2-hydrogen migration under neat conditions. The two-step transformation exemplifies a simple method for the efficient and green synthesis of β-ketoesters. The Royal Society of Chemistry 2013.
- Chen, Shufeng,Yuan, Fang,Zhao, Haiying,Li, Baoguo
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p. 12616 - 12620
(2013/08/23)
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- TEMPO-catalyzed aerobic oxygenation and nitrogenation of olefins via C=C double-bond cleavage
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A novel TEMPO-catalyzed aerobic oxygenation and nitrogenation of hydrocarbons via C=C double-bond cleavage has been disclosed. The reaction employs molecular oxygen as the terminal oxidant and oxygen-atom source by metal-free catalysis under mild conditions. This method can be used for the preparation of industrially and pharmaceutically important N- and O-containing motifs, directly from simple and readily available hydrocarbons.
- Wang, Teng,Jiao, Ning
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p. 11692 - 11695
(2013/09/02)
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- Novel 5-substituted benzyloxy-2-arylbenzofuran-3-carboxylic acids as calcium activated chloride channel inhibitors
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Transmembrane protein 16A (TMEM16A) channels are recently discovered membrane proteins that functions as a calcium activated chloride channel (CaCC). CaCCs are major regulators of various physiological processes, such as sensory transduction, epithelial secretion, smooth muscle contraction and oocyte fertilization. Thirty novel 5-substituted benzyloxy-2-arylbenzofuran-3- carboxylic acids (B01-B30) were synthesized and evaluated for their TMEM16A inhibitory activity by using short circuit current measurements in Fischer rat thyroid (FRT) cells expressing human TMEM16A. IC50 values were calculated using YFP fluorescence plate reader assay. Final compounds, having free carboxylic group displayed significant inhibition. Eight of the novel compounds B02, B13, B21, B23, B25, B27, B28, B29 exhibit excellent CaCCs inhibition with IC50 value 50 value of 2.8 ± 1.3 μM. None of the tested ester analogs of final benzofuran derivatives displayed TMEM16A/CaCCs inhibition.
- Kumar, Satish,Namkung, Wan,Verkman,Sharma, Pawan K.
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experimental part
p. 4237 - 4244
(2012/08/27)
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- Mechanism and scope of the MnIII-initiated oxidation of β-ketocarbonyl compounds: Furan synthesis
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Unless the MnIII-produced carbon-radical from β-ketocarbonyl compounds undergoes smooth intramolecular addition to alkenes, it traps molecular oxygen in the reaction medium to produce a peroxy radical, which reacts with the neighbouring carbonyl group to form 1,2-dioxetane. Thermal decomposition of 1,2-dioxetane completes the oxidation to produce α-oxo ester. This oxidation seems to be general at 50°C under aerobic conditions, and can be catalytic for MnIII in AcOH with ultrasonic irradiation. Thus, the development of a new synthetic method for diversely substituted furans has been accomplished based on a couple of the MnIII-initiated domino oxidation of β-ketocarbonyl compounds with a suitable α-allylic substitution. Copyright
- Wang, Chao,Li, Zhilong,Ju, Yeming,Koo, Sangho
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p. 6976 - 6985
(2013/03/13)
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- Enantioselective titanium(III)-catalyzed reductive cyclization of ketonitriles
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Reduction, please! The title reaction affords ?-hydroxyketones, a common structural motif in biologically active natural products, in good yields and high enantioselectivities at room temperature. The commercially available ansa-titanocene 1 was found to be an efficient catalyst for this process, which presumably proceeds by addition of a ketyl radical to a nitrile.
- Streuff, Jan,Feurer, Markus,Bichovski, Plamen,Frey, Georg,Gellrich, Urs
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supporting information; experimental part
p. 8661 - 8664
(2012/09/21)
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- Highly diastereoselective and enantioselective synthesis of α-hydroxy β-amino acid derivatives: Lewis base catalyzed hydrosilylation of α-acetoxy β-enamino esters
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By design: A series of α-acetoxy-β-enamino esters 1 were synthesized and then subjected to catalytic asymmetric hydrosilylation. In the presence of a chiral Lewis base catalyst, the reactions proceeded smoothly to provide a wide range of chiral α-acetoxy β-amino acid derivatives in high yields with good diastereoselectivities and enantioselectivities. Copyright
- Jiang, Yan,Chen, Xing,Zheng, Yongsheng,Xue, Zhouyang,Shu, Chang,Yuan, Weicheng,Zhang, Xiaomei
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supporting information; experimental part
p. 7304 - 7307
(2011/09/16)
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- Gold/copper-catalyzed activation of the aci-form of nitromethane in the synthesis of methylene-bridged bis-1,3-dicarbonyl compounds
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Activation of the aci-form of nitromethane using Lewis acids for the attack of carbon nucleophiles was studied. 1,3-Dicarbonyl compounds in the presence of catalytic amounts of AuCl3 or Cu(OTf)2 in nitromethane solvent could be converted into methylene-bridged bis-1,3-dicarbonyl compounds.
- Balamurugan, Rengarajan,Manojveer, Seetharaman
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supporting information; experimental part
p. 11143 - 11145
(2011/11/05)
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