- Total synthesis of (±)-Eusiderin K and (±)-Eusiderin J
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(±)-Eusiderin K and (±)-Eusiderin J were first synthesized from pyrogallol, in which the Claisen Rearrangement was used to afford two important C6-C3 units.
- Jing, Xiaobi,Gu, Wenxin,Bie, Pingyan,Ren, Xinfeng,Pan, Xinfu
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- Total synthesis of six natural products of benzodioxane neolignans
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(±)-Eusiderin E, (±)-Eusiderin F, (±)-Eusiderin K, (±)-Eusiderin J, (±)-Eusiderin M and (±)-Eusiderin G were first synthesized from pyrogallol, in which the Claisen Rearrangement was used to afford two important C6-C3 units.
- Jing, Xiao-Bi,Wang, Li,Han, Ying,Shi, Yao-Cheng,Liu, Yong-Hong,Sun, Jing
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Read Online
- Photoacid-Enabled Synthesis of Indanes via Formal [3 + 2] Cycloaddition of Benzyl Alcohols with Olefins
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An environmentally friendly and highly diastereoselective method for synthesizing indanes has been developed via a metastable-state photoacid system containing catalytic protonated merocyanine (MEH). Under visible-light irradiation, MEH yields a metastable spiro structure and liberated protons, which facilitates the formation of carbocations from benzyl alcohols, thus delivering diverse molecules in the presence of various nucleophiles. Mainly, a variety of indanes could be easily obtained from benzyl alcohols and olefins, and water is the only byproduct.
- Yang, Biao,Dong, Kui,Li, Xiang-Sheng,Wu, Li-Zhu,Liu, Qiang
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supporting information
p. 2040 - 2044
(2022/03/17)
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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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- Controllable synthesis of 2- And 3-aryl-benzomorpholines from 2-aminophenols and 4-vinylphenols
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We present herein a method for the controllable synthesis of 3-aryl-benzomorpholine and 2-aryl-benzomorpholine cycloadducts via cross-coupling/annulation between electron-rich 2-aminophenols and 4-vinylphenols. Molecular oxygen was successfully used in the reaction as the terminal oxidant and the complete inversion of chemoselectivity was achieved by the adjustment of the solvents and bases at room temperature.
- Dong, Kui,Jin, Xiao-Ling,Chen, Shihao,Wu, Li-Zhu,Liu, Qiang
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supporting information
p. 7941 - 7944
(2020/08/14)
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- A Next-Generation Air-Stable Palladium(I) Dimer Enables Olefin Migration and Selective C?C Coupling in Air
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We report a new air-stable PdI dimer, [Pd(μ-I)(PCy2tBu)]2, which triggers E-selective olefin migration to enamides and styrene derivatives in the presence of multiple functional groups and with complete tolerance of air. The same dimer also triggers extremely rapid C?C coupling (alkylation and arylation) at room temperature in a modular and triply selective fashion of aromatic C?Br, C?OTf/OFs, and C?Cl bonds in poly(pseudo)halogenated arenes, displaying superior activity over previous PdI dimer generations for substrates that bear substituents ortho to C?OTf.
- Kundu, Gourab,Rissanen, Kari,Schoenebeck, Franziska,Sperger, Theresa
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supporting information
p. 21930 - 21934
(2020/10/02)
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- Lignin Valorization by Cobalt-Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds
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Herein, a catalytic reductive fractionation of lignocellulose is presented using a heterogeneous cobalt catalyst and formic acid or formate as a hydrogen donor. The catalytic reductive fractionation of untreated birch wood yields monophenolic compounds in up to 34 wt % yield of total lignin, which corresponds to 76 % of the theoretical maximum yield. Model compound studies revealed that the main role of the cobalt catalyst is to stabilize the reactive intermediates formed during the organosolv pulping by transfer hydrogenation and hydrogenolysis reactions. Additionally, the cobalt catalyst is responsible for depolymerization reactions of lignin fragments through transfer hydrogenolysis reactions, which target the β-O-4′ bond. The catalyst could be recycled three times with only negligible decrease in efficiency, showing the robustness of the system.
- Rautiainen, Sari,Di Francesco, Davide,Katea, Sarmad Naim,Westin, Gunnar,Tungasmita, Duangamol N.,Samec, Joseph S. M.
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p. 404 - 408
(2019/01/04)
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- Hydrophilic (ν6-Arene)-Ruthenium(II) Complexes with P-OH ligands as catalysts for the isomerization of allylbenzenes and C-H bond arylation reactions in water
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Half-sandwich ruthenium(II) complexes containing ν6-coordinated 3-phenylpropanol and phosphinous-acid-type ligands, namely, [RuCl2(ν6-C6H5CH2CH2CH2OH){P(OH)R2}] (R = Me (2a), Ph (2b), 4-C6H4CF3 (2c), 4-C6H4OMe (2d), OMe (2e), OEt (2f), and OPh (2g), have been synthesized in 44-88% yield by reacting [RuCl2{ν6:κ1(O)-C6H5CH2CH2CH2OH}] (1) with the appropriate pentavalent phosphorus oxide R2P(═O)H. The structure of [RuCl2(ν6-C6H5CH2CH2CH2OH){P(OH)Me2}] (2a) was unequivocally confirmed by X-ray diffraction methods. Compounds 2a-g proved to be catalytically active in the isomerization of allylbenzenes into the corresponding (1-propenyl)benzene derivatives employing water as the sole reaction solvent, with [RuCl2(ν6-C6H5CH2CH2CH2OH){P(OH)(OPh)2}] (2g) showing the best performance and a broad substrate scope (73-93% isolated yields with E/Z ratios around 90:10 employing 1 mol % of 2g and 3 mol % of K2CO3, and performing the catalytic reactions at 80 °C for 4-24 h). The results herein presented show for the first time the utility of phosphinous acids as auxiliary ligands for metal-catalyzed olefin isomerization processes, reactions in which a cooperative role for the P - OH unit is proposed. On the other hand, the utility of complexes 2a-g as catalysts for ortho-arylation reactions of 2-phenylpyridine in water is also briefly discussed.
- González-Fernández, Rebeca,Crochet, Pascale,Cadierno, Victorio
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p. 3696 - 3706
(2019/10/11)
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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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supporting information
p. 3371 - 3375
(2016/07/11)
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- Streamlined, asymmetric synthesis of 8,4′-oxyneolignans
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Highly direct, modular syntheses of several natural 8,4′- oxyneolignans [(-)-1, (+)-1, (-)-2, and (-)-3] and some related variants [(-)-26, (+)-26, (+)-27, and (-)-28] are reported. Utilizing (S)- or (R)-methyl lactate as the chiral sources, two complementary syn- or anti-oriented routes were designed, encompassing nine and five steps, which were carried out to deliver the targets in an enantiomerically pure form. The embodiment of the two independent aryl and aryloxy moieties onto the lactate frame was performed according to a diversity-oriented protocol from the common precursors, aldehydes 6 and ent-6 for the syn-oriented routes and mesyl esters 19 and ent-19 for the anti-oriented routes. These syntheses set the stage for the generation of a wide and diverse repertoire of 8,4′-oxyneolignan compounds and the broad biological interrogation of its members.
- Curti, Claudio,Zanardi, Franca,Battistini, Lucia,Sartori, Andrea,Rassu, Gloria,Pinna, Luigi,Casiraghi, Giovanni
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p. 8552 - 8558
(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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- A concise synthesis of carpanone using solid-supported reagents and scavengers
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The synthesis of the natural product carpanone by utilization of polymer supported reagents, eliminating the need for conventional purification techniques was reported. The synthesis and crystal structure of a polymer-supported iridium catalyst for isomerization was also reported. The observations showed that isomerization of electron-rich aromatic compounds by the catalyst resulted in products with predominantly trans alkene geometry. However, the electron-poor derivatives were found to be less prone to rearrangement.
- Baxendale, Ian R.,Lee, Ai-Lan,Ley, Steven V.
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p. 1850 - 1857
(2007/10/03)
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- A polymer-supported iridium catalyst for the stereoselective isomerisation of double bonds
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A polymer-supported iridium catalyst has been prepared and used in the isomerisation of the double bonds in aryl allylic derivatives with excellent trans selectivity and without the need for conventional work-up procedures.
- Baxendale, Ian R.,Lee, Ai-Lan,Ley, Steven V.
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p. 516 - 518
(2007/10/03)
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- Total synthesis of (±)-Eusiderin G and (±)-Eusiderin M
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(±)-Eusiderin G and (±)-Eusiderin M were first synthesized from pyrogallol, in which the Claisen Rearrangement was used to afford two important C6-C3 units.
- Jing, Xiaobi,Gu, Wenxin,Ren, Xinfeng,Bie, Pingyan,Pan, Xinfu
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- Methoxyphenols from burning of Scandinavian forest plant materials
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Semivolatile compounds in smoke from gram-scale incomplete burning of plant materials were assessed by gas chromatography and mass spectrometry. Gas syringe sampling was shown to be adequate by comparison with adsorbent sampling. Methoxyphenols as well as 1,6-anhydroglucose were released in amounts as large as 10 mg kg-1 of dry biomass at 90% combustion efficiency. Wood, twigs, bark and needles from the conifers Norway spruce and Scots pine emitted 12 reported 2-methoxyphenols in similar proportions. Grass, heather and birchwood released the same 2-methoxyphenols but also the corresponding 2,6-dimethoxyphenols which are characteristic of angiosperms. The methoxyphenols are formed from lignin and differ in structure by the group in para position relative to the phenolic OH group. Prominent phenols were those with trans-l-propenyl and ethenyl groups in that position. Vanillin, 4- hydroxy-3-methoxybenzaldehyde, was a prominent carbonyl compound from the conifer materials. (C) 2000 Elsevier Science Ltd.
- Kjaellstrand, Jennica,Ramnaes, Olle,Petersson, Goeran
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p. 735 - 741
(2007/10/03)
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- NEOLIGNANS AND A PHENYLPROPANOID FROM VIROLA PAVONIS LEAVES
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Pavonisol, a new C-1/C-2 oxygenated phenylpropanoid, together with the known eusiderin-E and an 8,4'-oxyneolignan, were isolated from Virola pavonis leaves.Their structures were established by spectroscopic methods and chemical transformations. Key Word I
- Ferri, Pedro H.,Barata, Lauro E. S.
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p. 1375 - 1378
(2007/10/02)
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- Synthesis and Reactivity of Vinyl Quinone Methides
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Vinyl quinone methides 4a and 4b were obtained in high yields by Ag2O oxidation of eugenol (3a) and of 2,6-dimethoxy-4-(2-propenyl)phenol (3b).Vinyl quinone methides (VQMs) reacted with alcohols, with phenols, and with acetic acid giving compounds 5 and 6.As the former rearranged to the latter in the reaction medium, the addition of the reported substrates to VQMs turned out to be wholly regioselective toward the formation of coniferyl and sinapyl derivatives 6.In contrast, addition of carbon nucleophiles (acetylacetone and EtNO2) to VQMs gave both compounds 7 and 8.By reaction of the acetates 6a and 6b (CR=CH3CO) with LiAlH4 it was possible to perform a novel synthesis of coniferyl and sinapyl alcohols (1a and 1b).Treatment of the same acetates with an aqueous solution of NaHCO3 reproduced VQMs 4, which by subsequent reduction with NaBH4, gave propenylphenols 2 and allylphenols 3.Formation of the latter compounds from coniferyl and sinapyl acetates via VQM is here proposed as a possible biosynthetic pathway.
- Zanarotti, Antonio
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p. 941 - 945
(2007/10/02)
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- PREPARATION AND REACTIVITY OF 2,6-DIMETHOXY-4-ALLYLIDENE-2,5-CYCLOHEXADIEN-1-ONE (VINYL QUINONE METHIDE) A NOVEL SYNTHESIS OF SINAPYL ALCOHOL
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Title compound (3b), prepared in concentrated CHCl3 or benzene solution and spectroscopically characterized, is shown to be an useful intermediate for the synthesis of sinapyl alcohol (1b) and its derivatives.
- Zanarotti, A.
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p. 3815 - 3818
(2007/10/02)
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