- Synthesis of Enantioenriched 3,4-Disubstituted Chromans through Lewis Base Catalyzed Carbosulfenylation
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A method for the catalytic, enantioselective, carbosulfenylation of alkenes to construct 3,4-disubstituted chromans is described. Alkene activation proceeds through the intermediacy of enantioenriched, configurationally stable thiiranium ions generated from catalytic, Lewis base activation of an electrophilic sulfenylating agent. The transformation affords difficult-to-generate, enantioenriched, 3,4-disubstituted chromans in moderate to high yields and excellent enantioselectivities. A variety of substituents are compatible including electronically diverse functional groups as well as several functional handles such as aryl halides, esters, anilines, and phenols. The resulting thioether moiety is amenable to a number of functional group manipulations and transformations. Notably, the pendant sulfide was successfully cleaved to furnish a free thiol which readily provides access to most sulfur-containing functional groups which are present in natural products and pharmaceuticals.
- Denmark, Scott E.,Laverny, Aragorn,Menard, Travis
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p. 14290 - 14310
(2021/11/12)
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- Thermal proteome profiling efficiently identifies ribosome destabilizing oxazolidinones
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Identifying the targets of bioactive small molecules is a challenging endeavor for which no general solution currently exists. Classical affinity purification experiments suffer from the need to functionalise a bioactive compound and link it to a solid support, which may interfere with target binding. A modern mass spectrometry-based proteomics technique that has partially circumvented this problem is thermal proteome profiling (TPP), which determines the effect of an unmodified small molecule on the thermal stability of the whole proteome simultaneously. Here, we use TPP to identify the mode-of-action of a newly-discovered autophagy inhibitor based on oxazolidinones often employed as chiral auxiliaries. Surprisingly, a significant portion of all ribosomal proteins were found to be destabilized by the inhibitor, highlighting the utility of this technology for determining a challenging mode-of-action.
- N?cker, Christina,Kaiser, Nadine,Foley, Daniel,Sievers, Sonja,Janning, Petra,Waldmann, Herbert,Laraia, Luca
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supporting information
(2021/04/22)
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- Larvicidal activity and in silico studies of cinnamic acid derivatives against Aedes aegypti (Diptera: Culicidae)
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Cinnamic acid derivatives (CAD's) represent a great alternative in the search for insecticides against Aedes aegypti mosquitoes since they have antimicrobial and insecticide properties. Ae. aegypti is responsible for transmitting Dengue, Chikungunya, and Zika viruses, among other arboviruses associated with morbimortality, especially in developing countries. In view of this, in vitro analyses of n-substituted cinnamic acids and esters were performed upon 4th instar larvae (L4) of Ae. aegypti, as well as, molecular docking studies to propose a potential biological target towards this mosquitoes species. The larvicide assays proved that n-substituted ethyl cinnamates showed a more pronounced activity than their corresponding acids, in which p-chlorocinnamate (3j) presented a LC50 value of 8.3 μg/mL. Thusly, external morphologic alterations (rigid and elongated body, curved bowel, and translucent or darkened anal papillae) of mosquitoes’ group exposed to compound 3j, were observed by microscopy. In addition, an analytical method was developed for the quantification of the most promising analog by using high-performance liquid chromatography with UV detection (HPLC-UV). Molecular docking studies suggested that the larvicide action is associated with inhibition of acetylcholinesterase (AChE) enzyme. Therefore, expanding the larvicidal study with the cinnamic acid derivatives against the vector Ae. aegypti is important for finding search for more effective larvicides and with lower toxicity, since they have already shown good larvicidal properties against Ae. aegypti.
- Bezerra Fran?a, Saraliny,Carine Barros de Lima, Luana,Rychard da Silva Cunha, Cristhyan,Santos Anuncia??o, Daniela,Ferreira da Silva-Júnior, Edeildo,Ester de Sá Barreto Barros, Maria,José da Paz Lima, Dimas
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- Asymmetric synthesis of piperidines using the nitro-Mannich reaction☆
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A method for the synthesis of functionalized piperidines containing 3 contiguous stereocentres in the 2-,3- and 4- positions uses a diastereoselective nitro-Mannich to control stereochemistry. The nitro-Mannich reaction between a β-aryl/heteroaryl substituted nitroalkanes and glyoxylate imine provides β-nitro-amines with good selectivity (70:30 to >95:5) for the syn, anti-diastereoisomers. Reductive cyclisation with BF3.OEt2 and Et3SiH gave, after purification, stereochemically pure piperidines in 19–57% yield for ten examples with different 4-aryl/heteroaryl substituents.
- Anderson, James C.,Bouvier-Israel, Eva,Rundell, Christopher D.,Zhang, Xiangyu
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- Intramolecular Sakurai Allylation of Geminal Bis(silyl) Enamide with Indolenine. A Diastereoselective Cyclization to Form Functionalized Hexahydropyrido[3,4- b]Indole
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A fluoride-promoted intramolecular Sakurai allylation of geminal bis(silyl) enamide with indolenine has been developed. The reaction facilitates an efficient cyclization to give hexahydropyrido[3,4-b]indoles in good yields with high diastereoselectivity. The resulted cis, trans-stereochemistry further enables the ring-closing metathesis (RCM) reaction of two alkene moieties, giving a tetracyclic N-hetereocycle widely found as the core structure in akuammiline alkaloids.
- Chen, Yi,Gao, Lu,Song, Xuanyi,Song, Zhenlei
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supporting information
p. 124 - 128
(2021/01/13)
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- Synthesis method of beta-chloro acid ester and alpha, beta-unsaturated acid ester compound
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The invention belongs to the technical field of organic chemistry, and particularly relates to a synthesis method of beta-chloro acid ester and an alpha, beta-unsaturated acid ester compound. The structure of the compound is characterized by 1H NMR and 13C NMR and is confirmed. The method comprises the steps of by taking acetonitrile as a solvent, carrying out fragmentation on olefin, chlorooxalic acid monoester and 2, 6-dimethyl pyridine under a photocatalytic condition to generate an alkoxyacyl free radical intermediate, carrying out free radical addition reaction on the alkoxyacyl free radical intermediate and the olefin to generate carbon free radicals, then carrying out chlorination reaction to obtain the beta-chloro acid ester compound, and carrying out dehydrochlorination reaction under a DBU condition to generate the alpha, beta-unsaturated acid ester compound. The preparation method of the compound disclosed by the invention has the advantages of starting from olefin, being mild in condition, simple and efficient, strong in functional group compatibility and wide in substrate application range, and various beta-chloro acid ester and alpha, beta-unsaturated acid ester compounds can be synthesized from highly commercialized raw materials. On the basis of photoreaction of fluid chemistry, a target product can also be obtained with a relatively good yield, and the method has very good industrial and medicinal chemistry application values.
- -
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Paragraph 0123-0127
(2021/08/11)
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- A One-Pot Synthesis of α,β-Unsaturated Esters From Esters
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A convenient method for reductive Horner–Wadsworth–Emmons (HWE) olefination is described. The E-selective HWE homologation of various esters to α,β-unsaturated esters was readily achieved and gave the desired products in good-to-moderate yields under mild conditions. The one-pot reaction proceeds through an in situ generated aldehyde, formed via the partial reduction of an ester with lithium diisobutyl-t-butoxyaluminum hydride. The formation of cyclized metal acetal and subsequent decompose to the aldehyde for the olefination was found to be a crucial step in this C2-carbon homologation protocol.
- Hong, Chang Whee,Lee, Yong Jin,An, Duk Keun
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p. 1121 - 1125
(2021/06/01)
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- Hypervalent iodine(iii) induced oxidative olefination of benzylamines using Wittig reagents
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We have developed hypervalent iodine(iii) induced oxidative olefination of primary and secondary benzylamines using 2C-Wittig reagents, which provides easy access to α,β-unsaturated esters. Mild reaction conditions, good to excellent yields with high (E) selectivity, and a broad substrate scope are the key features of this reaction. We have successfully carried out the gram-scale synthesis of α,β-unsaturated esters.
- Ramavath, Vijayalakshmi,Rupanawar, Bapurao D.,More, Satish G.,Bansode, Ajay H.,Suryavanshi, Gurunath
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p. 8806 - 8813
(2021/05/26)
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- Photoinduced Oxidative Alkoxycarbonylation of Alkenes with Alkyl Formates
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A photoinduced oxidative alkoxycarbonylation of alkenes initiated by intermolecular addition of alkoxycarbonyl radicals has been demonstrated. Employing alkyl formates as alkoxycarbonyl radical sources, a range of α,β-unsaturated esters were obtained with good regioselectivity and E selectivity under ambient conditions.
- Tang, Wan-Ying,Chen, Ling,Zheng, Ming,Zhan, Le-Wu,Hou, Jing,Li, Bin-Dong
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supporting information
p. 3939 - 3943
(2021/05/26)
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- Regioselective Br?nsted Acid-Catalyzed Annulation of Cyclopropane Aldehydes with N′-Aryl Anthranil Hydrazides: Domino Construction of Tetrahydropyrrolo[1,2- a]quinazolin-5(1 H)ones
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A highly regioselective synthesis of tetrahydropyrrolo[1,2-a]quinazolin-5(1H)one derivatives was achieved by reacting cyclopropane aldehydes with N′-aryl anthranil hydrazides in the presence of p-toluene sulfonic acid (PTSA). The transformation involves domino imine formation and intramolecular cyclization to form 2-arylcyclopropyl-2,3-dihydroquinolin-4(1H)-one, followed by nucleophilic ring opening of the cyclopropyl ring to form desired tetrahydropyrrolo[1,2-a]quinazolin-5(1H)one in good to excellent yield with complete regioselectivity. This protocol tolerates a great variety of functional groups and thus provides a simple and step-efficient method for pyrroloquinazolinone synthesis.
- Banerjee, Prabal,Kaur, Navpreet,Singh, Priyanka
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p. 3393 - 3406
(2020/03/23)
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- Enantioselective Syntheses of Strychnos and Chelidonium Alkaloids through Regio- and Stereocontrolled Cooperative Catalysis
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We describe enantioselective syntheses of strychnos and chelidonium alkaloids. In the first case, indole acetic acid esters were established as excellent partner nucleophiles for enantioselective cooperative isothiourea/Pd catalyzed α-alkylation. This provides products containing indole-bearing stereocenters in high yield and with excellent levels of enantioinduction in a manner that is notably independent of the N-substituent. This led to concise syntheses of (?)-akuammicine and (?)-strychnine. In the second case, the poor performance of ortho-substituted cinnamyl electrophiles in the enantioselective cooperative isothiourea/Ir catalyzed α-alkylation was overcome by appropriate substituent choice, leading to enantioselective syntheses of (+)-chelidonine, (+)-norchelidonine, and (+)-chelamine.
- Fyfe, James W. B.,Hutchings-Goetz, Luke S.,Snaddon, Thomas N.,Yang, Chao
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supporting information
p. 17556 - 17564
(2020/08/14)
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- Systematic Study on the Catalytic Arsa-Wittig Reaction
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Efficient catalytic arsa-Wittig reactions have been developed by using 1-phenylarsolane as a catalyst. A wide array of aldehydes was converted to the corresponding olefins in high yields with moderate to excellent E stereoselectivity in the presence of a catalytic amount of 1-phenylarsolane. Moreover, density functional theory calculations were carried out to afford insight into the E/Z selectivity.
- Inaba, Ryoto,Kawashima, Ikuo,Fujii, Toshiki,Yumura, Takashi,Imoto, Hiroaki,Naka, Kensuke
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supporting information
p. 13400 - 13407
(2020/09/21)
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- Selective Synthesis of Z-Cinnamyl Ethers and Cinnamyl Alcohols through Visible Light-Promoted Photocatalytic E to Z Isomerization
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A photocatalytic E to Z isomerization of alkenes using an iridium photosensitizer under mild reaction conditions is disclosed. This method provides scalable and efficient access to Z-cinnamyl ether and allylic alcohol derivatives in high yields with excellent stereoselectivity. Importantly, this method also provides a powerful strategy for the selective synthesis of Z-magnolol and honokiol derivatives possessing potential biological activity.
- Li, Hengchao,Chen, Hang,Zhou, Yang,Huang, Jin,Yi, Jundan,Zhao, Hongcai,Wang, Wei,Jing, Linhai
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supporting information
p. 555 - 559
(2020/02/05)
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- A photoredox catalysed Heck reaction: Via hole transfer from a Ru(ii)-bis(terpyridine) complex to graphene oxide
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The attachment of homoleptic Ru bis-terpy complexes on graphene oxide significantly improved the photocatalytic activity of the complexes. These straightforward complexes were applied as photocatalysts in a Heck reaction. Due to covalent functionalization on graphene oxide, which functions as an electron reservoir, excellent yields were obtained. DFT investigations of the charge redistribution revealed efficient hole transfer from the excited Ru unit towards the graphene oxide. This journal is
- Rosenthal, Marta,Lindner, J?rg K. N.,Gerstmann, Uwe,Meier, Armin,Schmidt, W. Gero,Wilhelm, René
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p. 42930 - 42937
(2020/12/18)
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- Atomically precise palladium nanocluster catalyzed tandem oxidation processes of alcohols and phosphorous ylides: Facile access to α,β-unsaturated esters
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The mesoporous silica nanosphere supported palladium nanocluster was synthesized through a simple impregnation method and well characterized. The as prepared catalyst shows excellent catalytic performance in tandem oxidation process (TOP) of alcohol and phosphorous ylide, which provides an efficient access to α,β-unsaturated esters with high yields utilizes 1 atmosphere of molecular oxygen as sole oxidant. This work represents the first example of atomically precise palladium nanocluster catalyzed tandem oxidation process of alcohol and phosphorous ylide and is expected to open new horizons for nanoclusters in the tandem reactions.
- Gao, Taiping,Du, Jialei,Liu, Wenyan,Ren, Mingxia
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supporting information
(2020/09/17)
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- A Sequential Acyl Thiol-Ene and Thiolactonization Approach for the Synthesis of δ-Thiolactones
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A novel strategy for the synthesis of δ-thiolactones from inexpensive and readily available ?-unsaturated esters has been developed. This strategy incorporates a radical acyl thiol-ene reaction as the key C-S bond forming step. Cyclization is achieved via a Steglich-type thiolactonization of 5-mercaptopentanoic acids. We report the facile and scalable synthesis of δ-thiolactones in moderate to good yield under mild reaction conditions with tolerance for a range of functional groups.
- McCourt, Ruairí O.,Scanlan, Eoin M.
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supporting information
p. 3460 - 3464
(2019/05/10)
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- Synthesis of Nitrogen-Containing Goniothalamin Analogues with Higher Cytotoxic Activity and Selectivity against Cancer Cells
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Two series of racemic goniothalamin analogues displaying nitrogen-containing groups were designed and synthesized. A total of 19 novel analogues were evaluated against a panel of four different cancer cell lines, along with the normal prostate cell line PNT2 to determine their selectivity. Among them, goniothalamin chloroacrylamide 13 e displayed the lowest IC50 values for both MCF-7 (0.5 μm) and PC3 (0.3 μm) cells, about 26-fold more potent than goniothalamin (1). Besides its higher potency, compound 13 e also displayed much higher selectivity than goniothalamin. In contrast, goniothalamin isobutyramide 13 c was the most potent analogue against Caco-2 cells (IC50=0.8 μm), about 10-fold more potent and 17-fold more selective than 1. These results reveal the potential of compounds 13 c and 13 e for further in vivo studies, representing the first goniothalamin analogues with IC50 values in the low micromolar range and high selectivity against MCF-7, Caco-2, and PC3 cancer cell lines.
- Meirelles, Matheus A.,Braga, Carolyne B.,Ornelas, Catia,Pilli, Ronaldo A.
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supporting information
p. 1403 - 1417
(2019/08/01)
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- Biocatalytic dynamic kinetic reductive resolution with ketoreductase from: Klebsiella pneumoniae: The asymmetric synthesis of functionalized tetrahydropyrans
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Ketoreductase from growing cells of Klebsiella pneumoniae (NBRC 3319) acts as an efficient reagent for converting racemic α-benzyl/cinnamyl substituted-β-ketoesters to the corresponding β-hydroxy esters with excellent yields and stereoselectivities (ee and de >99 %). The reactions described herein followed a biocatalytic dynamic kinetic reductive resolution (DKRR) pathway, which is reported for the first time with such substrates. It was found that the enzyme system can accept substituted mono-aryl rings with different electronic natures. In addition, it also accepts a substituted naphthyl ring and heteroaryl ring in the α-position of the parent β-ketoester. The synthesized enantiopure β-hydroxy esters were then synthetically manipulated to valuable tetrahydropyran building blocks.
- Barik, Rasmita,Halder, Joydev,Nanda, Samik
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supporting information
p. 8571 - 8588
(2019/10/02)
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- Sequential Palladium-Catalyzed Allylic Alkylation/retro-Dieckmann Fragmentation Strategy for the Synthesis of α-Substituted Acrylonitriles
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A straightforward synthesis of α-substituted acrylonitriles is described using 4-cyano-3-oxotetrahydro-thiophene (c-THT) as an acrylonitrile surrogate. This unprecedented two-step sequence featuring a palladium-catalyzed allylic alkylation (Pd-AA) and a retro-Dieckmann fragmentation provides a general entry into diversely substituted 1,4-dienes.
- Katsina, Tania,Sharma, Sachi Prem,Buccafusca, Roberto,Quinn, Derek J.,Moody, Thomas S.,Arseniyadis, Stellios
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supporting information
p. 9348 - 9352
(2019/11/20)
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- Synthesis of Allylsilanes via Nickel-Catalyzed Cross-Coupling of Silicon Nucleophiles with Allyl Alcohols
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NiCl2(PMe3)2-catalyzed reaction of allyl alcohols with silylzinc reagents, including PhMe2SiZnCl, Ph2MeSiZnCl, and Ph3SiZnCl, was performed, achieving allylsilanes in high yields. Aryl- and heteroaryl-substituted allyl alcohols, (E)-3-arylprop-2-en-1-ols, 1-aryl-prop-2-en-1-ols, and (E)-1-phenylpent-1-en-3-ol can be employed in the transformation. A range of functional groups as well as heteroaryl groups were tolerated. Reaction exhibited high regioselectivity and E/Z-selectivity when 1- or 3-aryl-substituted allyl alcohols were used as the substrates. Reaction of chiral allyl alcohol, (S,E)-1-phenylpent-1-en-3-ol, yielded a configuration-inversion product (R,E)-dimethyl(phenyl)(1-phenylpent-1-en-3-yl)silane.
- Yang, Bo,Wang, Zhong-Xia
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supporting information
p. 7965 - 7969
(2019/10/19)
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- Boron-Templated Dimerization of Allylic Alcohols to Form Protected 1,3-Diols via Acid Catalysis
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We report an unprecedented boron-templated dimerization of allylic alcohols that generates a 1,3-diol product with two stereogenic centers in high yield and diastereoselectivity. This acid-catalyzed reaction is achieved via in situ formation of a boronic ester intermediate that facilitates selective cyclization and formation of a cyclic boronic ester product. High yields are observed with a variety of allylic alcohols, and mechanistic studies confirm the role of boron as a template for the reaction.
- Nazari, S. Hadi,Forson, Kelton G.,Martinez, Erin E.,Hansen, Nicholas J.,Gassaway, Kyle J.,Lyons, Nathan M.,Kenney, Karissa C.,Valdivia-Berroeta, Gabriel A.,Smith, Stacey J.,Michaelis, David J.
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supporting information
p. 9589 - 9593
(2019/12/02)
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- METHODS FOR MAKING BACTERIOCHLORIN MACROCYCLES COMPRISING AN ANNULATED ISOCYCLIC RING AND RELATED COMPOUNDS
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Described herein are bacteriochlorins comprising an annulated isocyclic ring. Also described are methods and intermediates for the synthesis of bacteriochlorins comprising an annulated isocyclic ring, and methods of using such bacteriochlorins for, among
- -
-
Page/Page column 80; 100
(2018/06/21)
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- Rh(III)-Catalyzed Enaminone-Directed C-H Coupling with α-Diazo-α-phosphonoacetate for Reactivity Discovery: Fluoride-Mediated Dephosphonation for C-C Coupling Reactions
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Rh(III)-catalyzed enaminone-directed C-H coupling with α-diazo-α-phosphonoacetate has been used for the identification of fluoride-mediated dephosphonation C-C coupling reactivity for the synthesis of 4-hydroxy-1-naphthoates. Intermolecular C-C coupling of α-phosphonoacetate and benzaldehyde for (E)-selective α,β-unsaturated ester synthesis has also been achieved.
- Song, Chao,Yang, Chen,Zeng, Hua,Zhang, Wenjing,Guo, Shan,Zhu, Jin
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supporting information
p. 3819 - 3823
(2018/07/22)
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- Catalytic Diastereo- and Enantioselective Fluoroamination of Alkenes
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The stereoselective synthesis of syn-β-fluoroaziridine building blocks via chiral aryl iodide-catalyzed fluorination of allylic amines is reported. The method employs HF-pyridine as a nucleophilic fluoride source together with mCPBA as a stoichiometric oxidant, and affords access to arylethylamine derivatives featuring fluorine-containing stereocenters in high diastereo- and enantioselectivity. Catalyst-controlled diastereoselectivity in the fluorination of chiral allylic amines enabled the preparation of highly enantioenriched 1,3-difluoro-2-amines bearing three contiguous stereocenters. The enantioselective catalytic method was applied successfully to other classes of multifunctional alkene substrates to afford anti-β-fluoropyrrolidines, as well as a variety of 1,2-oxyfluorinated products.
- Mennie, Katrina M.,Banik, Steven M.,Reichert, Elaine C.,Jacobsen, Eric N.
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supporting information
p. 4797 - 4802
(2018/04/17)
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- Exploitation of Cyclopropane Carbaldehydes to Prins Cyclization: Quick Access to (E)-Hexahydrooxonine and Octahydrocyclopenta[ b]pyran
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A single-step TiX4-mediated Prins-type cyclization of cyclopropane carbaldehydes with 3-buten-1-ol for the highly stereoselective construction of relatively strained (E)-hexahydrooxonines is reported. Switching the alcohol to 3-butyn-1-ol prompted a similar route, augmented by another cyclization within a nine-membered ring to afford a bicyclized product (4,4-dihalo-5-aryloctahydrocyclopenta[b]pyran). Easy transformation of the resulting geminal dihalide to a vinyl halide and a ketone further supplemented the substance of this approach.
- Kumar, Pankaj,Dey, Raghunath,Banerjee, Prabal
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supporting information
p. 5163 - 5166
(2018/09/13)
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- trans-Cyclooctenes as Halolactonization Catalysts
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The strained olefins in trans-cyclooctenes serve as efficient catalysts for halolactonizations, including bromolactonizations and iodolactonizations. The trans-cyclooctene framework is essential for excellent catalytic performance, and the substituents also play important roles in determining efficiency. These results are the first demonstration of catalysis by a trans-cyclooctene.
- Einaru, Shunsuke,Shitamichi, Kenta,Nagano, Tagui,Matsumoto, Akira,Asano, Keisuke,Matsubara, Seijiro
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supporting information
p. 13863 - 13867
(2018/09/27)
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- Highly Enantioselective, Base-Free Synthesis of α-Quaternary Succinimides through Catalytic Asymmetric Allylic Alkylation
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The synthesis of diversely substituted five-membered ring succinimide derivatives is reported featuring a direct, base-free, palladium-catalyzed asymmetric allylic alkylation. The method allows a straightforward access to the desired heterocyclic scaffold bearing an all-carbon α-quaternary stereogenic center in high yields and good to excellent enantioselectivities. To further demonstrate the synthetic utility of the method, the allylated products were further converted to various versatile chiral building blocks, including a chiral pyrrolidine and a spirocyclic derivative, using selective transformations.
- Song, Tao,Arseniyadis, Stellios,Cossy, Janine
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supporting information
p. 8076 - 8080
(2018/06/15)
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- Catalytic Geminal Difluorination of Styrenes for the Construction of Fluorine-rich Bioisosteres
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A geminal difluorination of alkenes based on I(I)/I(III) catalysis is disclosed, which is compatible with a range of electronically and substitutionally diverse styrenes (27 examples, up to 89% yield). Employing inexpensive p-TolI as the organocatalyst, turnover is enabled by Selectfluor-mediated oxidation to generate the ArIF2 species in situ. Extension to include α-substituted styrenes bearing fluorine-containing groups is disclosed and provides an expansive platform for the generation of fluorine-rich architectures.
- Scheidt, Felix,Neufeld, Jessica,Sch?fer, Michael,Thiehoff, Christian,Gilmour, Ryan
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supporting information
p. 8073 - 8076
(2019/01/04)
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- One-Pot Synthesis of α,β-Unsaturated Esters, Ketones, and Nitriles from Alcohols and Phosphonium Salts
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A general method for the synthesis of α,β-unsaturated esters, ketones, and nitriles is successfully achieved by a one-pot copper-catalyzed oxidation with O 2 in air as oxidant. The solvent mixture of acetonitrile and formamide (1:1) is optimized to ensure the oxidation of alcohols, deprotonation of phosphonium salt, and Wittig reaction occur efficiently in one pot. A broad range of substrates has been explored for this process, including three electron-withdrawing group (CO 2 Et, COPh, CN) functionalized phosphonium salts. They reacted not only with benzylic and heteroaromatic alcohols, but also with aliphatic alcohols, forming the corresponding α,β-unsaturated esters, ketones, and nitriles in moderate to excellent yields.
- Ding, Weijie,Hu, Juan,Jin, Huile,Yu, Xiaochun,Wang, Shun
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p. 107 - 118
(2017/09/28)
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- Facile synthesis of α, β-unsaturated esters through a one-pot copper-catalyzed aerobic oxidation-Wittig reaction
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An efficient one-pot synthesis of α, β-unsaturated esters through the aerobic oxidation – Wittig tandem reaction of alcohols and phosphorous ylide is developed. This new method operates under mild reaction conditions, and uses CuI/TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) as co-catalyst and air (O2) as the oxidant. It tolerates a wide range of functionalized benzylic alcohol and aliphatic alcohols.
- Ren, Cheng,Shi, Zhenyu,Ding, Weijie,Liu, Zhiqing,Jin, Huile,Yu, Xiaochun,Wang, Shun
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supporting information
p. 14 - 17
(2017/12/06)
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- Gold catalyzed Heck-coupling of arenediazonium o-benzenedisulfonimides
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Diazonium salts, and precisely arenediazonium o-benzenedisulfonimides, have been used for the first time as efficient electrophilic partners in gold catalyzed Heck-coupling reactions. The synthetic protocol was general, easy and gave the target products in satisfactory yields. Mechanistic insights revealed the fundamental roles of the o-benzenedisulfonimide anion as an electron transfer agent thath promotes a radical pathway that does not require the presence of photocatalysts or external oxidants.
- Barbero, Margherita,Dughera, Stefano
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p. 295 - 301
(2018/01/12)
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- Highly efficient and green esterification of carboxylic acids in deep eutectic solvents without any other additives
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A protocol that carboxylic acids esterifies with the quaternary ammonium salt of deep eutectic solvent (DES) is presented, which opens a new access to ester using DES as alkylating agent, solvent, and catalyst. The reaction runs smoothly in DES without any other additives. Substituted cinnamic acids, aromatic acids, and aliphatic acids can be esterified in moderate to good yields. The advantages of this reaction include excellent functional group compatibility and simple reaction procedure.
- Yasmin, Sumera,Sheng, Wen-Bing,Peng, Cai-Yun,Rahman, Atta-ur,Liao, Duan-Fang,Choudhary, M. Iqbal,Wanga, Wei
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supporting information
p. 68 - 75
(2017/12/26)
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- Construction of the Bacteriochlorin Macrocycle with Concomitant Nazarov Cyclization To Form the Annulated Isocyclic Ring: Analogues of Bacteriochlorophyll a
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Bacteriochlorophylls contain a bacteriochlorin macrocycle bearing an annulated fifth ring. The fifth ring, termed the isocyclic ring or ring E, is equipped with 131-oxo and 132-carbomethoxy substituents. Herein, a general route to st
- Zhang, Shaofei,Lindsey, Jonathan S.
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p. 2489 - 2504
(2017/03/14)
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- Bioactivity and structure-activity relationship of cinnamic acid esters and their derivatives as potential antifungal agents for plant protection
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A series of cinnamic acid esters and their derivatives were synthesized and evaluated for antifungal activities in vitro against four plant pathogenic fungi by using the mycelium growth rate method. Structure-activity relationship was derived also. Almost all of the compounds showed some inhibition activity on each of the fungi at 0.5 mM. Eight compounds showed the higher average activity with average EC50 values of 17.4-28.6 μg/mL for the fungi than kresoxim-methyl, a commercial fungicide standard, and ten compounds were much more active than commercial fungicide standards carbendazim against P. grisea or kresoxim-methyl against both P. grisea and Valsa Mali. Compounds C1 and C2 showed the higher activity with average EC50 values of 17.4 and 18.5 μg/mL and great potential for development of new plant antifungal agents. The structure-activity relationship analysis showed that both the substitution pattern of the phenyl ring and the alkyl group in the alcohol moiety significantly influences the activity. There exists complexly comprehensive effect between the substituents on the phenyl ring and the alkyl group in the alcohol moiety on the activity. Thus, cinnamic acid esters showed great potential the development of new antifungal agents for plant protection due to high activity, natural compounds or natural compound framework, simple structure, easy preparation, low-cost and environmentally friendly.
- Zhou, Kun,Chen, Dongdong,Li, Bin,Zhang, Bingyu,Miao, Fang,Zhou, Le
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- Bu 4 N + -Controlled Addition and Olefination with Ethyl 2-(Trimethylsilyl)acetate via Silicon Activation
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Catalytic Bu 4 NOAc as silicon activator of ethyl 2-(trimethylsilyl)acetate, in THF, was utilized for the synthesis of β-hydroxy esters, whereas employing catalytic Bu 4 NOTMS gave α,β-unsaturated esters. The established reaction conditions were applicable to a diverse range of aromatic, heteroaromatic, aliphatic aldehydes and ketones. Reactions were achieved at room temperature without taking any of the specialized precautions that are in place for other organometallics. A stepwise olefination pathway via silylated β-hydroxy esters with subsequent elimination to form the α,β-unsaturated ester has been demonstrated. The key to selective product formation lies in use of the weaker acetate activator which suppresses subsequent elimination whereas stronger TMSO - activator (and base) facilitates both addition and elimination steps. The use of tetrabutyl ammonium salts for both acetate and trimethylsilyloxide activators provide enhanced silicon activation when compared to their inorganic cation counterparts.
- Das, Manas,Manvar, Atul,Fox, Ian,Roberts, Dilwyn J.,O'Shea, Donal F.
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supporting information
p. 2401 - 2406
(2017/09/30)
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- Copper(i)-catalysed transfer hydrogenations with ammonia borane
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Highly Z-selective alkyne transfer semihydrogenations and conjugate transfer hydrogenations of enoates can be effected by employing a readily available and air-stable copper(i)/N-heterocyclic carbene (NHC) complex, [IPrCuOH]. As an easy to handle and potentially recyclable H2 source, ammonia borane (H3NBH3) is used.
- Korytiaková, Eva,Thiel, Niklas O.,Pape, Felix,Teichert, Johannes F.
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supporting information
p. 732 - 735
(2017/01/13)
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- Indazole-6-phenylcyclopropylcarboxylic Acids as Selective GPR120 Agonists with in Vivo Efficacy
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GPR120 agonists have therapeutic potential for the treatment of diabetes, but few selective agonists have been reported. We identified an indazole-6-phenylcyclopropylcarboxylic acid series of GPR120 agonists and conducted SAR studies to optimize GPR120 potency. Furthermore, we identified a (S,S)-cyclopropylcarboxylic acid structural motif which gave selectivity against GPR40. Good oral exposure was obtained with some compounds displaying unexpected high CNS penetration. Increased MDCK efflux was utilized to identify compounds such as 33 with lower CNS penetration, and activity in oral glucose tolerance studies was demonstrated. Differential activity was observed in GPR120 null and wild-type mice indicating that this effect operates through a mechanism involving GPR120 agonism.
- McCoull, William,Bailey, Andrew,Barton, Peter,Birch, Alan M.,Brown, Alastair J. H.,Butler, Hayley S.,Boyd, Scott,Butlin, Roger J.,Chappell, Ben,Clarkson, Paul,Collins, Shelley,Davies, Robert M. D.,Ertan, Anne,Hammond, Clare D.,Holmes, Jane L.,Lenaghan, Carol,Midha, Anita,Morentin-Gutierrez, Pablo,Moore, Jane E.,Raubo, Piotr,Robb, Graeme
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p. 3187 - 3197
(2017/04/19)
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- New Class of Anion-Accelerated Amino-Cope Rearrangements as Gateway to Diverse Chiral Structures
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We report useful new lithium-assisted asymmetric anion-accelerated amino-Cope rearrangement cascades. A strategic nitrogen atom chiral auxiliary serves three critical roles, by (1) enabling in situ assembly of the chiral 3-amino-1,5-diene precursor, (2) facilitating the rearrangement via a lithium enolate chelate, and (3) imparting its influence on consecutive inter- or intramolecular C-C or C-X bond-forming events via resulting chiral enamide intermediates or imine products. The mechanism of the amino-Cope rearrangement was explored with density functional theory. A stepwise dissociation-recombination mechanism was found to be favored. The stereochemistry of the chiral auxiliary determines the stereochemistry of the Cope product by influencing the orientation of the lithium dienolate and sulfinylimine fragments in the recombination step. These robust asymmetric anion-accelerated amino-Cope enabled cascades open the door for rapid and predictable assembly of complex chiral acyclic and cyclic nitrogen-containing motifs in one pot.
- Chogii, Isaac,Das, Pradipta,Fell, Jason S.,Scott, Kevin A.,Crawford, Mark N.,Houk,Njardarson, Jon T.
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supporting information
p. 13141 - 13146
(2017/09/26)
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- Macrocycles All Aflutter: Substitution at an Allylic Center Reveals the Conformational Dynamics of [13]-Macrodilactones
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The shapes adopted by large-ring macrocyclic compounds play a role in their reactivity and their ability to be bound by biomolecules. We investigated the synthesis, conformational analysis, and properties of a specific family of [13]-macrodilactones as models of natural-product macrocycles. The features of our macrodilactones enabled us to study the relationship between stereogenic centers and planar chirality through the modular synthesis of new members of this family of macrocycles. Here we report on insights gained from a new [13]-macrodilactone that is substituted at a position adjacent to the alkene in the molecule. Analysis of the compound, in comparison to an α-substituted regioisomer, by using X-ray crystallography, NMR coupling constants, and reaction-product characterization in concert with computational chemistry, revealed that the alkene unit is dynamic. That is, the data support a model in which the alkene in our [13]-macrodilactones oscillates between two conformations. A difference in reactivity of one conformation compared to the other leads to manifestation of this dynamic behavior. The results underscore the local conformational dynamics observed in some natural-product macrocycles, which could have implications for biomolecule binding.
- Rutledge, Kelli M.,Hamlin, Trevor A.,Baldisseri, Donna M.,Bickelhaupt, F. Matthias,Peczuh, Mark W.
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supporting information
p. 2623 - 2633
(2017/10/07)
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- Stereodivergent allylic substitutions with aryl acetic acid esters by synergistic iridium and lewis base catalysis
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The preparation of all possible stereoisomers of a given chiral molecule bearing multiple stereocenters by a simple and unified method is a significant challenge in asymmetric catalysis. We report stereodivergent allylic substitutions with aryl acetic acid esters catalyzed synergistically by a metallacyclic iridium complex and benzotetramisole. Through permutations of the enantiomers of the two chiral catalysts, all four stereoisomers of the products bearing two adjacent stereocenters are accessible with high diastereoselectivity and enantioselectivity. The resulting chiral activated ester products can be converted readily to enantioenriched amides, unactivated esters, and carboxylic acids in a onepot manner.
- Jiang, Xingyu,Beiger, Jason J.,Hartwig, John F.
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supporting information
p. 87 - 90
(2017/05/16)
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- Iridium-Catalyzed Enantioselective Allylic Substitution of Aliphatic Esters with Silyl Ketene Acetals as the Ester Enolates
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Enantioselective allylic substitution with enolates derived from aliphatic esters under mild conditions remains challenging. Herein we report iridium-catalyzed enantioselective allylation reactions of silyl ketene acetals, the silicon enolates of esters, to form products containing a quaternary carbon atom at the nucleophile moiety and a tertiary carbon atom at the electrophile moiety. Under relatively neutral conditions, the allylated aliphatic esters were obtained with excellent regioselectivity and enantioselectivity. These products were readily converted into primary alcohols, carboxylic acids, amides, isocyanates, and carbamates, as well as tetrahydrofuran and γ-butyrolactone derivatives, without erosion of enantiomeric purity.
- Jiang, Xingyu,Hartwig, John F.
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supporting information
p. 8887 - 8891
(2017/07/17)
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- Piperidine-appended imidazolium ionic liquid as task-specific basic-IL for Suzuki and Heck reactions and for tandem Wittig-Suzuki, Wittig-Heck, Horner-Emmons-Suzuki, and Horner-Emmons-Heck protocols
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Facile, high yielding, one-pot methods for the synthesis of a library of diversely substituted bi-aryls, diarylethenes, and aryl-enoates, via Suzuki and Heck reactions, and by sequential Wittig-Suzuki, Wittig-Heck, Horner-Emmons-Suzuki, and Horner-Emmons-Heck reactions are reported. The reactions employ piperidine-appended imidazolium ionic liquid [PAIM][NTf2] as a task-specific basic-IL, butyl-methyl-imidazolium ionic liquid [BMIM][X] (X?=?PF6, BF4) as solvent, and catalytic amounts of Pd(OAc)2 with no other additives. Wittig and Horner-Emmons reactions are effected by reacting substituted benzaldehydes with 4-bromobenzyl-PPh3 (or bromomethyl-PPh3) phosphonium salts, or diethylphosphonate with bromobenzaldehydes respectively, to form the corresponding ethenes. Subsequent cross-coupling reactions are accomplished by addition of aryl-boronic acid or phenyl-ethenes along with Pd(OAc)2 to bring about the aforementioned hyphenated transformations. The feasibility to perform double-olefination via Wittig and Horner-Emmons reactions with dialdehydes to form highly conjugated bis-styryl and bis-enoate compounds is also shown. The [BMIM][X] solvent is recycled and reused.
- Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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p. 150 - 161
(2017/06/30)
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- A class of 1, 2, 5 - oxadiazole - 2 oxide analogs, its preparation and use
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The invention provides 1,2,5-oxadiazole-2 oxide analogue with a structure shown as general formula I, and a preparation method and an application thereof. The 1,2,5-oxadiazole-2 oxide analogue has the activity for resisting schistosome thioredoxin glutathione reductase, kills schistosome by blocking a normal redox equilibrium physiological metabolism process of schistosome cells, can be used as a drug lead for development of drugs for treating schistosomiasis, and provides novel means for preventing and treating schistosomiasis. The general formula I is shown in the description.
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Paragraph 0091; 0092; 0093; 0094
(2017/04/21)
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- General and Efficient Intermolecular [2+2] Photodimerization of Chalcones and Cinnamic Acid Derivatives in Solution through Visible-Light Catalysis
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[2+2] Photocycloaddition, for example, the dimerization of chalcones and cinnamic acid derivatives, is a unique strategy to construct cyclobutanes, which are building blocks for a variety of biologically active molecules and natural products. However, most attempts at the above [2+2] addition have focused on solid-state, molten-state, or host–guest systems under ultraviolet-light irradiation in order to overcome the competition of facile geometric isomerization of nonrigid olefins. We report a general and simple method to realize the intermolecular [2+2] dimerization reaction of these acyclic olefins to construct cyclobutanes in a highly regio- and diastereoselective manner in solution under visible light, which provides an efficient solution to a long-standing problem.
- Lei, Tao,Zhou, Chao,Huang, Mao-Yong,Zhao, Lei-Min,Yang, Bing,Ye, Chen,Xiao, Hongyan,Meng, Qing-Yuan,Ramamurthy, Vaidhyanathan,Tung, Chen-Ho,Wu, Li-Zhu
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p. 15407 - 15410
(2017/11/13)
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- N-heterocyclic carbene-catalysed Peterson olefination reaction
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N-heterocyclic carbenes (NHCs) have been utilised as highly efficient organocatalysts to catalyse Peterson olefination reaction of aldehydes with trimethylsilylketene ethyl trimethylsilyl acetal or fluoro(trimethylsilyl)ketene ethyl trimethylsilyl acetal to produce the corresponding functionalized olefines in 34-93% yields with excellent stereoselectivities.
- Wang, Ying,Du, Guang-Fen,Gu, Cheng-Zhi,Xing, Fen,Dai, Bin,He, Lin
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p. 472 - 478
(2015/12/31)
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- Iridium(I) N-Heterocyclic Carbene (NHC)/Phosphine Catalysts for Mild and Chemoselective Hydrogenation Processes
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The directed chemoselective hydrogenation of olefins has been established by using iridium(I) catalysts, which feature a tuned NHC/phosphine ligand combination. This selective reduction process has been demonstrated in a wide array of solvents, including more environmentally acceptable media, also allowing further refinement of hydrogenation selectivity. The directed, chemoselective hydrogenation of olefins has been established by using iridium(I) catalysts, which feature a tuned NHC/phosphine ligand combination. This selective reduction process has been demonstrated in a wide array of solvents, including more environmentally acceptable media, also allowing further refinement of hydrogenation selectivity.
- Kerr, William J.,Mudd, Richard J.,Brown, Jack A.
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supporting information
p. 4738 - 4742
(2016/04/05)
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- Ketenimines from Isocyanides and Allyl Carbonates: Palladium-Catalyzed Synthesis of β,γ-Unsaturated Amides and Tetrazoles
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The reaction of allyl ethyl carbonates with isocyanides in the presence of a catalytic amount of Pd(OAc)2provided ketenimines through β-hydride elimination of the allyl imidoylpalladium intermediates. The insertion of the isocyanide into the π-allyl Pd complex proceeded via an unusual η1-allyl Pd species. The resulting ketenimines were hydrolyzed to β,γ-unsaturated carboxamides during purification by flash column chromatography on silica gel or converted in situ into 1,5-disubstituted tetrazoles by [3+2] cycloaddition with hydrazoic acid or trimethylsilyl azide.
- Qiu, Guanyinsheng,Mamboury, Mathias,Wang, Qian,Zhu, Jieping
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supporting information
p. 15377 - 15381
(2016/12/06)
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- Solvent-free, one-pot synthesis of α,β-unsaturated esters in the presence of a C3-symmetric arsine
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An efficient synthesis of α, β-unsaturated esters is achieved via a one-pot reaction in the presence of a C3-symmetric arsine. The key advantages are the short reaction time, simple workup, mild reaction conditions, and high yields.
- Wang, Changqing,Yang, Liu,Zhou, Rong,Mei, Guangquan
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supporting information
p. 1074 - 1079
(2016/07/16)
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- Oxidative ring-opening of ferrocenylcyclopropylamines to N-ferrocenylmethyl β-hydroxyamides
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The in situ reduction of ferrocenyl cyclopropylimines to the corresponding amines triggers a facile oxidative ring-opening to yield the formal four-electron oxidation products: N-ferrocenylmethyl β-hydroxyamides. This process is believed to proceed via generation of a ferrocinium ion in the presence of air, leading to facile formation of a distonic radical cation that is ultimately trapped by oxygen.
- Gee, Yi Sing,Goertz, Neils J. M.,Gardiner, Michael G.,Hyland, Christopher J. T.
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supporting information
p. 2498 - 2503
(2016/03/01)
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- Nucleophile promoted gold redox catalysis with diazonium salts: C-Br, C-S and C-P bond formation through catalytic Sandmeyer coupling
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Gold-catalyzed C-heteroatom (C-X) coupling reactions are evaluated without using sacrificial oxidants. Vital to the success of this methodology is the nucleophile-assisted activation of aryldiazonium salts, which could be an effective oxidant for converting Au(i) to Au(iii) even without the addition of an assisting ligand or photocatalyst. By accelerating the reaction kinetics to outcompete C-C homo-coupling or diazonium dediazoniation, gold-catalyzed Sandmeyer reactions were achieved with different nucleophiles, forming C-Br, C-S and C-P bonds in high yields and selectivities.
- Peng, Haihui,Cai, Rong,Xu, Chang,Chen, Hao,Shi, Xiaodong
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p. 6190 - 6196
(2016/09/03)
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