- Ground-State Electron Transfer as an Initiation Mechanism for Biocatalytic C-C Bond Forming Reactions
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The development of non-natural reaction mechanisms is an attractive strategy for expanding the synthetic capabilities of substrate promiscuous enzymes. Here, we report an "ene"-reductase catalyzed asymmetric hydroalkylation of olefins using α-bromoketones as radical precursors. Radical initiation occurs via ground-state electron transfer from the flavin cofactor located within the enzyme active site, an underrepresented mechanism in flavin biocatalysis. Four rounds of site saturation mutagenesis were used to access a variant of the "ene"-reductase nicotinamide-dependent cyclohexanone reductase (NCR) from Zymomonas mobiles capable of catalyzing a cyclization to furnish β-chiral cyclopentanones with high levels of enantioselectivity. Additionally, wild-type NCR can catalyze intermolecular couplings with precise stereochemical control over the radical termination step. This report highlights the utility for ground-state electron transfers to enable non-natural biocatalytic C-C bond forming reactions.
- Fu, Haigen,Lam, Heather,Emmanuel, Megan A.,Kim, Ji Hye,Sandoval, Braddock A.,Hyster, Todd K.
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p. 9622 - 9629
(2021/07/01)
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- Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor
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A convergent strategy is reported for the construction of nitrogen-containing heterocycles from common substrates: 1,4-diketones and primary amines. Indeed, by just varying the substrates, the substituents, or the heating mode, it is possible to selectively synthesize indole, indolone (1,5,6,7-tetrahydroindol-4-one), or cinnoline (5,6,7,8-tetrahydrocinnoline) derivatives in moderate to excellent yields.
- Abdelli, Abderrahmen,Efrit, Mohamed Lotfi,El-Marrouki, Dalel,Gros, Philippe C.,M’Rabet, Hédi,Touchet, Sabrina
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supporting information
p. 1722 - 1731
(2021/06/25)
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- Copper-Catalyzed N-O Cleavage of α,β-Unsaturated Ketoxime Acetates toward Structurally Diverse Pyridines
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The copper-catalyzed [4 + 2] annulation of α,β-unsaturated ketoxime acetates with 1,3-dicarbonyl compounds for the synthesis of three classes of structurally diverse pyridines has been developed. This method employs 1,3-dicarbonyl compounds as C2 synthons and enables the synthesis of multifunctionalized pyridines with diverse electron-withdrawing groups in moderate to good yields. The mechanistic investigation suggests that the reactions proceed through an ionic pathway.
- Ding, Xiaojuan,Duan, Jindian,Fang, Zheng,Guo, Kai,Li, Zhenjiang,Mao, Yiyang,Rong, Binsen,Xu, Gaochen,Zhang, Lei,Zhu, Ning
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supporting information
p. 2532 - 2542
(2020/03/13)
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- Visible-light driven synthesis of polycyclic benzo[: D] [1,3]oxazocine from 2-aminochalcone
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Herein, we report a tandem cycloisomerization/nucleophilic addition/cyclization of 2-amino chalcone with bifunctional nucleophiles driven by visible light. This cascade process is realized by the irradiation of a blue LED at room temperature, which provides a concise route to structurally diverse benzo[d][1,3]oxazocine scaffolds. Mechanistic studies show that the reaction is initiated with the E to Z isomerization of a C-C double bond upon the irradiation of visible light, followed by cyclization/rearomatization to generate a transient quinolinium intermediate, which is trapped by the nucleophile and cyclized to produce the polycyclic benzo[d][1,3]oxazocine.
- Chen, Junhan,Gao, Yu-Qi,He, Yu-Peng,Hou, Yi,Li, Ruoxin,Xie, Weiqing,Zhang, Sheng-Yong,Zhu, Liming
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supporting information
p. 6739 - 6742
(2020/07/13)
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- Organocatalytic Enantioselective Selenosulfonylation of a C-C Double Bond to Form Two Stereogenic Centers in an Aqueous Medium
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Organocatalytic selenosulfonylation of the C-C double bond of α,β-unsaturated ketones to construct two contiguous stereogenic centers in an aqueous medium was described. A series of α-selenyl and β-sulfonyl ketones with various functional groups were synthesized in good yields and enantioselectivities with saturated NaCl solution as the solvent. In addition, this protocol had been successfully scaled up to a decagram scale via a simple workup procedure.
- Chen, Zhili,Hu, Fangli,Huang, Shengli,Zhao, Zhengxing,Mao, Hui,Qin, Wenling
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p. 8100 - 8111
(2019/06/17)
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- PYRROLIDINE DERIVATIVES AS PPAR AGONISTS
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The present invention discloses a class of pyrrolidine derivatives as PPAR agonist, and their use for the treatment of some diseases of PPAR receptor-associated pathways (such as nonalcoholic steatohepatitis and concurrent fibrosis, insulin resistance, primary biliary cholgangitis, dyslipidenmia, hyperlipidemia, hypercholesterolemia, atherosclerosis, hypertriglyceridemia, cardiovascular disease, obesity or the like). In particular, the present invention discloses a compound represented by Formula (I) or a pharmaceutically acceptable salt thereof.
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Paragraph 0715; 0719-0721
(2019/08/02)
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- Tandem Wittig Reaction-Ring Contraction of Cyclobutanes: A Route to Functionalized Cyclopropanecarbaldehydes
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An original tandem reaction consisting of a Wittig reaction-ring contraction process between α-hydroxycyclobutanone and phosphonium ylides has been developed. Highly functionalized cyclopropanecarbaldehydes are obtained in good to high yield.
- Aitken, David J.,Caboni, Pierluigi,Cuccu, Federico,Frongia, Angelo,Luridiana, Alberto,Secci, Francesco,Serusi, Lorenzo
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supporting information
(2019/10/08)
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- Fe-Catalyzed Cycloisomerization of Aryl Allenyl Ketones: Access to 3-Arylidene-indan-1-ones
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A cycloisomerization of aryl allenyl ketones to 3-arylidene-indan-1-ones using a cationic Fe-complex as a catalyst is reported. The catalyst opens a synthetically interesting reaction pathway to this surprisingly underrepresented class of indanones that are not accessible using alternative catalytic systems.
- Teske, Johannes,Plietker, Bernd
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p. 2257 - 2260
(2018/04/27)
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- Catalytic Cyclooligomerization of Enones with Three Methylene Equivalents
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Cyclic structures are highly represented in organic molecules, motivating a wealth of catalytic methods targeting their synthesis. Among the various ring-forming processes, cyclooligomerization reactions possess several attractive features but require addressing a unique challenge associated with controlling ring-size selectivity. Here we describe the catalytic reductive cocyclooligomerization of an enone and three carbene equivalents to generate a cyclopentane, a process that constitutes a formal [2 + 1 + 1 + 1]-cycloaddition. The reaction is promoted by a (quinox)Ni catalyst and uses CH2Cl2/Zn as the C1 component. Mechanistic studies are consistent with a metallacycle-based pathway, featuring sequential migratory insertions of multiple carbene equivalents to yield cycloalkanes larger than cyclopropanes.
- Farley, Conner M.,Zhou, You-Yun,Banka, Nishit,Uyeda, Christopher
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supporting information
p. 12710 - 12714
(2018/10/09)
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- Nonenzymatic Dynamic Kinetic Resolution of in situ Generated Hemithioacetals: Access to 1,3-Disubstituted Phthalans
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The first nonenzymatic DKR reaction of hemithioacetals is developed. Hemithioacetals were formed in situ via thiol addition and subsequently underwent an intramolecular oxa-Michael reaction. The scope of the reaction was quite broad ranging from aliphatic to aromatic substituents and 1,3-disubstituted-1,3-dihyroisobenzofuran products were obtained in good yields with moderate diastereoselectivities and high enantioselectivities. (Figure presented.).
- Nath, Utpal,Chowdhury, Deepan,Pan, Subhas Chandra
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supporting information
p. 1628 - 1633
(2018/03/21)
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- Synthesis of trifluoromethyl-/cyclopropyl-substituted 2-isoxazolines by DBU-promoted domino reaction
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NTrifluoromethyl and cyclopropyl substituted 2-isoxazolines were synthesized via a DBU-promoted domino reaction of β-trifluoromethyl-/β-cyclopropyl-substituted enones with hydroxylamine. The domino reaction consists of a Michael addition and the followed cyclization. A wide range of 3-substituted 5-cyclopropyl-5- trifluoromethyl-2-isoxazolines were obtained in good to excellent yields under mild reaction conditions. The method could also apply to other trifluoromethyl-substituted enones.
- Liu, Xiao-Dong,Ma, Hai-Yan,Xing, Chun-Hui,Lu, Long
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supporting information
p. 1780 - 1783
(2017/07/27)
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- 6-exo-trig Michael addition-lactonizations for catalytic enantioselective chromenone synthesis
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The catalytic enantioselective 6-exo-trig Michael addition-lactonization of enone-acid substrates to form cis-chromenones with high diastereo- and enantiocontrol was developed using the commercially available isothiourea tetramisole. An acidic workup prov
- Neyyappadath, Rifahath M.,Cordes, David B.,Slawin, Alexandra M. Z.,Smith, Andrew D.
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p. 2555 - 2558
(2017/03/09)
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- Enantioselective Organocatalytic Cascade Approach to Different Classes of Benzofused Acetals
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A novel enantioselective organocatalytic strategy is presented for the synthesis of tetrahydrofurobenzofuran and methanobenzodioxepine natural product core structures. The strategy is based on a pair of divergent reaction pathways in which hydroxyarenes react with γ-keto-α,β-unsaturated aldehydes, catalyzed by a chiral secondary amine. One reaction pathway, which leads to chiral 5,5-fused acetals with two stereocenters—the tetrahydrofurobenzofuran scaffolds—proceeds in moderate yields and up to 96 % ee. The other reaction pathway provides 5,6-bridged methanobenzodioxepine scaffolds with three stereocenters in moderate to good yields and up to 95 % ee. The reaction is remarkable as it can proceed with catalyst loadings as low as 0.25 mol %, providing one of the highest known turnover numbers in iminium ion catalysis. Furthermore, the hemiacetal tetrahydrofurobenzofuran can undergo functionalizations including reduction, oxidation, and allylation. Finally, the effects involved in the substrate control for the divergent pathways, based on both experimental and computational studies, have been investigated. A model involving steric, electronic and stereoelectronic interactions is discussed to rationalize the observed selectivities.
- Paz, Bruno Matos,Klier, Lydia,N?sborg, Line,Lauridsen, Vibeke Henriette,Jensen, Frank,J?rgensen, Karl Anker
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supporting information
p. 16810 - 16818
(2016/11/16)
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- Iodine-mediated intramolecular amination of ketones: The synthesis of 2-acylindoles and 2-acylindolines by tuning N-protecting groups
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A general method for constructing both 2-acylindoles and 2-acylindolines via I2-mediated intramolecular C-N bond formation is presented, and the selective formation of either 2-acylindoles or 2-acylindolines just depends on the nitrogen protecting groups used in the same substrate skeletons. The Royal Society of Chemistry.
- Gao, Wen-Chao,Jiang, Shan,Wang, Ruo-Lin,Zhang, Chi
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p. 4890 - 4892
(2013/07/05)
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- Identification of novel chromenone derivatives as interleukin-5 inhibitors
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A series of (E)-5-alkoxy-3-(3-phenyl-3-oxoprop-1-enyl)-4H-chromen-4-ones (4) and (E)-5-alkoxy-3-(3-hydroxy-3-phenylprop-1-enyl)-4H-chromen-4-ones (5) were synthesized and evaluated for their IL-5 inhibitory activity. Propenone analogs 4 possess some of the structurally important characteristics of isoflavone 2 and chalcone 3 previously known as potent IL-5 inhibitor. However, the inhibitory activity of 4 was weak and therefore this structural hybridization appears to be ineffective for the design of IL-5 inhibitor. Meanwhile the potent activity profile of compounds 5 was discovered. This enhanced activity of 5 compared to 4 could be due to the effective location of hydroxyl group of allylic alcohol moiety of 5 in the 3D structure. The electron withdrawing substituents at position 4 of phenyl ring of 5 enhances the activity possibly due to an increase in the strength of hydrogen bonding property of hydroxyl group of allylic alcohol moiety.
- Venkateswararao, Eeda,Kim, Min-Seok,Sharma, Vinay K.,Lee, Ki-Cheul,Subramanian, Santhosh,Roh, Eunmiri,Kim, Youngsoo,Jung, Sang-Hun
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- Highly efficient route to functionalized tetrahydrocarbazoles using a tandem cross-metathesis/intramolecular-hydroarylation sequence
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The scope of the novel ruthenium-catalyzed tandem cross-metathesis/ intramolecular-hydroarylation sequence is described. This methodology offers a practical and efficient synthesis of structurally diverse and complex tetrahydrocarbazoles in good to excellent yields (up to 98%). Moreover, preliminary efforts towards the development of an enantioselective version of the current process by sequential catalysis with ruthenium complex and chiral amine are presented, with high yields and enantioselectivities (up to 88% yield and 91% ee).
- An, Xiao-Lei,Chen, Jia-Rong,Li, Chang-Feng,Zhang, Fu-Gen,Zou, You-Quan,Guo, Ying-Cen,Xiao, Wen-Jing
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p. 2258 - 2265
(2011/06/11)
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- New access to trisubstitutea 3-pyrrolines under phosphine catalysis
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Conjugated dienes, properly activated by electron-withdrawing groups on both ends, are shown to be suitable substrates for phosphinepromoted organocatalytic processes. Their reactions with imines, under phosphine catalysis, afford a new and efficient synthetic approach to functionalized 3-pyrrolines.
- Schuler, Marie,Duvvuru, Deepti,Retailleau, Pascal,Betzer, Jean-Francois,Marinetti, Angela
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supporting information; scheme or table
p. 4406 - 4409
(2009/12/26)
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- Synthesis and characterisation of Hg (II) and Ag (I) complexes of 4-fluorobenzoylmethylenetriphenylphosphorane and 4-chlorobenzoyl methylenetriphenylphosphorane, with spectroscopic studies
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4-flourobenzyloxymethylenetriphenylphosphorane ylide [Ph 3PCHCOC6H4F], (FBPPY), and 4- chlorobenzyloxymethylenetriphenylphosphorane ylide [Ph3PCHCOC 6H4Cl](CBPPY), have been synthesised. Th
- Karami, Kazem
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p. 725 - 727
(2008/09/21)
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