- A donor-acceptor complex enables the synthesis of: E -olefins from alcohols, amines and carboxylic acids
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Olefins are prevalent substrates and functionalities. The synthesis of olefins from readily available starting materials such as alcohols, amines and carboxylic acids is of great significance to address the sustainability concerns in organic synthesis. Metallaphotoredox-catalyzed defunctionalizations were reported to achieve such transformations under mild conditions. However, all these valuable strategies require a transition metal catalyst, a ligand or an expensive photocatalyst, with the challenges of controlling the region- and stereoselectivities remaining. Herein, we present a fundamentally distinct strategy enabled by electron donor-acceptor (EDA) complexes, for the selective synthesis of olefins from these simple and easily available starting materials. The conversions took place via photoactivation of the EDA complexes of the activated substrates with alkali salts, followed by hydrogen atom elimination from in situ generated alkyl radicals. This method is operationally simple and straightforward and free of photocatalysts and transition-metals, and shows high regio- and stereoselectivities.
- Chen, Kun-Quan,Shen, Jie,Wang, Zhi-Xiang,Chen, Xiang-Yu
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p. 6684 - 6690
(2021/05/31)
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- Synthesis, antiepileptic effects, and structure-activity relationships of α-asarone derivatives: In vitro and in vivo neuroprotective effect of selected derivatives
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In the present study, we compared the antiepileptic effects of α-asarone derivatives to explore their structure-activity relationships using the PTZ-induced seizure model. Our research revealed that electron-donating methoxy groups in the 3,4,5-position on phenyl ring increased antiepileptic potency but the placement of other groups at different positions decreased activity. Besides, in allyl moiety, the optimal activity was reached with either an allyl or a 1-butenyl group in conjugation with the benzene ring. The compounds 5 and 19 exerted better neuroprotective effects against epilepsy in vitro (cell) and in vivo (mouse) models. This study provides valuable data for further exploration and application of these compounds as potential anti-seizure medicines.
- Zhang, Jian,Mu, Keman,Yang, Peng,Feng, Xinqian,Zhang, Di,Fan, Xiangyu,Wang, Qiantao,Mao, Shengjun
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- Iron-catalyzed regiodivergent alkyne hydrosilylation
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Although tremendous effort has been devoted to the development of methods for iron catalysis, few of the catalysts reported to date exhibit clear superiority to other metal catalysts, and the mechanisms of most iron catalysis remain unclear. Herein, we report that iron complexes bearing 2,9-diaryl-1,10-phenanthroline ligands exhibit not only unprecedented catalytic activity but also unusual ligand-controlled divergent regioselectivity in hydrosilylation reactions of various alkynes. The hydrosilylation protocol described herein provides a highly efficient method for preparing useful di- and trisubstituted olefins on a relatively large scale under mild conditions, and its use markedly improved the synthetic efficiency of a number of bioactive compounds. Mechanistic studies based on control experiments and density functional theory calculations were performed to understand the catalytic pathway and the observed regioselectivity.
- Hu, Meng-Yang,He, Peng,Qiao, Tian-Zhang,Sun, Wei,Li, Wen-Tao,Lian, Jie,Li, Jin-Hong,Zhu, Shou-Fei
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supporting information
p. 16894 - 16902
(2020/10/09)
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- Cobalt-Catalyzed Z to e Isomerization of Alkenes: An Approach to (E)-β-Substituted Styrenes
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An efficient cobalt-catalyzed Z to E isomerization of β-substituted styrenes using the amido-diphosphine ligand was developed, delivering the (E)-isomers with good functional tolerance and high stereoselectivity. The reaction could be scaled up to gram-scale with a catalyst loading of 0.1 mol %, using a mixture of (Z)- and (E)-alkene as the starting material. Preliminary mechanistic studies indicated that cobalt(I)-hydride and a benzylic-cobalt species were probably involved in the reaction, as supported by experiments and DFT calculations.
- Liu, Hongmei,Xu, Man,Cai, Cheng,Chen, Jianhui,Gu, Yugui,Xia, Yuanzhi
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supporting information
p. 1193 - 1198
(2020/02/04)
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- Method for synthesizing E-methyl styrene compound
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The method for preparing E-pyridyl or alkyl-substituted,bipyridine, in a solvent, in the presence of nitrogen protection, in, reaction 0 °C -50 °C in the presence of a metal nickel salt 24 - 36h, ligand and an additive is E, and the preparation method disclosed by the invention has the advantages, cheap 2,2 ’ - raw materials, easiness in obtaining 2,2 ’ - and the like. The ligand is,bipyridine or an alkyl-substituted bipyridyl compound, in the. presence of a nitrogen, protection agent, in a solvent.
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Page/Page column 6
(2020/03/25)
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- Radical Cation Diels-Alder Reactions by TiO2 Photocatalysis
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Radical cation Diels-Alder reactions by titanium dioxide (TiO2) photocatalysis in lithium perchlorate/nitromethane solution are described. TiO2 photocatalysis promotes reactions between electron-rich dienes and dienophiles, which would otherwise be difficult to accomplish due to electronic mismatching. The reactions are triggered by hole oxidation of the dienophile and are completed by the excited electron reduction of the radical cation intermediate at the dispersed surface in the absence of any sacrificial substrate.
- Nakayama, Kaii,Maeta, Naoya,Horiguchi, Genki,Kamiya, Hidehiro,Okada, Yohei
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supporting information
p. 2246 - 2250
(2019/04/10)
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- E-Olefins through intramolecular radical relocation
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Full control over the selectivity of carbon-carbon double-bond migrations would enable access to stereochemically defined olefins that are central to the pharmaceutical, food, fragrance, materials, and petrochemical arenas. The vast majority of double-bond migrations investigated over the past 60 years capitalize on precious-metal hydrides that are frequently associated with reversible equilibria, hydrogen scrambling, incomplete E/Z stereoselection, and/or high cost. Here, we report a fundamentally different, radical-based approach.We showcase a nonprecious, reductant-free, and atom-economical nickel (Ni)(I)-catalyzed intramolecular 1,3-hydrogen atom relocation to yield E-olefins within 3 hours at room temperature. Remote installations of E-olefins over extended distances are also demonstrated.
- Kapat, Ajoy,Sperger, Theresa,Guven, Sinem,Schoenebeck, Franziska
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p. 391 - 396
(2019/02/03)
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- Concise access toward chiral hydroxy phenylpropanoids: formal synthesis of virolongin B; kigelin; kurasoin A; 4-hydroxysattabacin, and actinopolymorphol A
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A simple, two step strategy consisting of Sharpless asymmetric dihydroxylation followed by regioselective breaking of [Formula presented] bond is utilized to target key chiral intermediates of natural products virolongin B, kigelin, kurasoin A, 4-hydroxy-sattabacin, and actinopolymorphol A. Derivatives of enantiopure hydroxy phenyl propanoids and α-hydroxy Weinreb amides are synthesized. The reductive cleavage of [Formula presented] bond in a regioselective manner is obtained using Pd/C in methanol.
- Patil, Sagar N.,Tilve, Santosh G.
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p. 3371 - 3375
(2016/07/11)
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- A Facile, Convenient, and Green Route to (E)-Propenylbenzene Flavors and Fragrances by Alkene Isomerization
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(E)-Propenylbenzene flavors and fragrances can be made and isolated in high yield and selectivity by using bifunctional catalyst 1, and the heterogenized analogues. Multigram-scale reactions can be performed neat and the products isolated either by distillation, using homogeneous catalyst 1 (0.1-0.5 mol%, r.t., 10-45 min), or by decantation from heterogeneous catalysts PS-1 or PSL-1 (0.5 mol%, 70 °C, 24 h; catalyst separation and re-use shown for 3-4 cycles; 10 cycles using distilled eugenol feedstock). Both purified starting materials and essential oil feedstocks could be used. Z Isomers were present at very low levels (from 0.4% to less than 0.1%) in the products.
- Larsen, Casey R.,Paulson, Erik R.,Erdogan, Gulin,Grotjahn, Douglas B.
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supporting information
p. 2462 - 2466
(2015/10/19)
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- Iron-catalyzed decarboxylative methylation of α,β-unsaturated acids under ligand-free conditions
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It is the first time to find that iron-catalyzed decarboxylative methylation of α,β-unsaturated acids could be performed in the absence of any ligands. During the reaction, the configuration of the double bond could be retained. It is noteworthy that di-t
- Rong, Guangwei,Liu, Defu,Lu, Linhua,Yan, Hong,Zheng, Yang,Chen, Jie,Mao, Jincheng
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p. 5033 - 5037
(2014/07/08)
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- SINGLE-STEP PROCESS FOR THE PREPARATION OF ARYL OLEFINS
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The present invention relates to the single-step process for the synthesis of aryl olefin compounds of Formula (1) by reacting aryl aldehydes with alkyl aldehydes in presence of malononitrile and acid or base or salt, optionally in presence of solvent.
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Page/Page column 12-13; 15-16
(2014/05/24)
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- Euodenine A: A small-molecule agonist of human TLR4
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A small-molecule natural product, euodenine A (1), was identified as an agonist of the human TLR4 receptor. Euodenine A was isolated from the leaves of Euodia asteridula (Rutaceae) found in Papua New Guinea and has an unusual U-shaped structure. It was synthesized along with a series of analogues that exhibit potent and selective agonism of the TLR4 receptor. SAR development around the cyclobutane ring resulted in a 10-fold increase in potency. The natural product demonstrated an extracellular site of action, which requires the extracellular domain of TLR4 to stimulate a NF-κB reporter response. 1 is a human-selective agonist that is CD14-independent, and it requires both TLR4 and MD-2 for full efficacy. Testing for immunomodulation in PBMC cells shows the induction of the cytokines IL-8, IL-10, TNF-α, and IL-12p40 as well as suppression of IL-5 from activated PBMCs, indicating that compounds like 1 could modulate the Th2 immune response without causing lung damage.
- Neve, Juliette E.,Wijesekera, Hasanthi P.,Duffy, Sandra,Jenkins, Ian D.,Ripper, Justin A.,Teague, Simon J.,Campitelli, Marc,Garavelas, Agatha,Nikolakopoulos, George,Le, Phuc V.,De A. Leone, Priscila,Pham, Ngoc B.,Shelton, Philip,Fraser, Neil,Carroll, Anthony R.,Avery, Vicky M.,McCrae, Christopher,Williams, Nicola,Quinn, Ronald J.
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p. 1252 - 1275
(2014/03/21)
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- Iron-catalyzed decarboxylative methylation of α,β-unsaturated acids under ligand-free conditions
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It is the first time to find that iron-catalyzed decarboxylative methylation of α,β-unsaturated acids could be performed in the absence of any ligands. During the reaction, the configuration of the double bond could be retained. It is noteworthy that di-t
- Rong, Guangwei,Liu, Defu,Lu, Linhua,Yan, Hong,Zheng, Yang,Chen, Jie,Mao, Jincheng
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p. 5033 - 5037
(2014/12/10)
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- Ultrasound-assisted convenient synthesis of hypolipidemic active natural methoxylated (E)-arylalkenes and arylalkanones
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An ultrasound-assisted convenient method was developed for the conversion of toxic methoxylated cis-isomer of arylalkenes into its hypolipidemic active trans-isomer. Treatment of cis-isomer or mixture of all three isomers (1a-1j) with ammonium formate and 10% Pd/C gave arylalkanes (2a-2j), which upon oxidation with DDQ in anhydrous dioxane containing a little amount of silica gel, provided (E)-arylalkenes (3a-3g) in 42-72% yield depending upon the substituents attached at the aryl ring. The same method, upon addition of a few drops of water, provided hypolipidemic active arylalkanones (3h-3j) in 59-65% yield.
- Joshi, Bhupendra P.,Sharma, Anuj,Sinha, Arun K.
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p. 3075 - 3080
(2007/10/03)
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- An effective system to synthesize hypolipidemic active α-asarone and related methoxylated (E)-arylalkenes
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Methoxylated (E)-arylalkenes (1a-1k) were prepared in two steps by an improved Grignard reaction comprising the reverse addition of alkylmagnesium bromide to benzaldehydes (2a-2k) in anhydrous ether and toluene into arylalkanols (3a-3k) in high yield, followed by dehydration with silica gel under microwave irradiation for 3-12 min, depending upon the substituents attached to the aromatic ring to afford hypolipidemic active α-asarone (1a) and related methoxylated (E)-arylalkenes (1b-1k).
- Sharma, Anuj,Joshi, Bhupendra P.,Sinha, Arun K.
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p. 2231 - 2235
(2007/10/03)
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- The synthesis of the anti-malarial natural product polysphorin and analogues using polymer-supported reagents and scavengers.
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A general asymmetric route to both enantiomers of polysphorin has been developed. The route utilizes polymer-supported reagents, catalysts and scavengers to minimise the need for aqueous work-up and chromatography. This includes application of a method to scavenge 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and a "catch-and-release" procedure to extract the resultant diol following Sharpless asymmetric dihydroxylation. A novel enzymatic selective protection and investigations of a new asymmetric dihydroxylation using microencapsulated osmium tetroxide were also investigated during the course of this study.
- Lee, Ai-Lan,Ley, Steven V
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p. 3957 - 3966
(2007/10/03)
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- Synthesis and hypolipidemic and antiplatelet activities of α-asarone isomers in humans (in vitro), mice (in vivo), and rats (in vivo)
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A series of α-asarone isomers was synthesized and investigated for their hypolipidemic and antiplatelet activity. Considering the hypolipidemic activity in rats at a dose of 80 mg/kg/day, some isomers were more potent than clofibrate at 150 mg/kg. Compoun
- Poplawski,Lozowicka,Dubis,Lachowska,Witkowski,Siluk,Petrusewicz,Kaliszan,Cybulski,Strzalkowska,Chilmonczyk
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p. 3671 - 3676
(2007/10/03)
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- Feeding-deterrent activity of α-asarone isomers against some stored Coleoptera
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All isomers of α-asarone [(E)-4-prop-1-enyl-1,2,5-trimethoxybenzene] were tested for their feeding deterrent activity against adults of Sitophilus granarius and Tribolium confusum and larvae of Trogoderma granarium and Tribolium confusum. (E)-2-prop-1-eny
- Poplewski, Janusz,Lozowicka, Bozena,Dubis, Alina T.,Lachowska, Barbara,Winiecki, Zbigiew,Nawrot, Jan
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p. 560 - 564
(2007/10/03)
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- Trans stereoselectivity in the reaction of cyclic phosphonium salts with aromatic aldehydes
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The Wittig olefination of substituted aromatic aldehydes with ylides from phosphorinanium salts [RCH2P(Ph)(CH2)5]+Br- in which the phosphorus atom is incorporated into a six-membered ring, is E-selective.
- Lawrence, Nicholas J.,Beynek, Hayrettin
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p. 497 - 498
(2007/10/03)
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- The Synthesis of Megaphone
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Condensation of 4,4,5-trimethoxy-2-propyl>-2,5-cyclohexadien-1-one (7) with 1,2,3-trimethoxy-5-(1-(Z)-propenyl)benzene in dichloromethane, in the presence of 1 equiv. of stannic chloride, gave (2β,3β,3aα)-3,3a-dihydro-5-methoxy-3-m
- Buechi, George,Chu, Ping-Sun
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p. 2718 - 2721
(2007/10/02)
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