- A Chiral Phenanthroline Ligand with a Hydrogen-Bonding Site: Application to the Enantioselective Amination of Methylene Groups
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A silver-catalyzed amination is reported that occurs at the aliphatic C3-substituent of various quinolones and pyridones. The C-H amination reaction proceeded with high site-and enantioselectivity (14 examples, 83-97% ee). The key to its success is the use of a chiral phenanthroline ligand that is attached via an ethynyl linker to the 8-position of octahydro-1H-4,7-methanoisoindol-1-one. AgPF6 (10 mol %) served as the silver source, PhI.NNs as the nitrene precursor, and 1,10-phenanthroline as the coligand. The reaction outcome can be understood by assuming a nitrene C-H insertion within a hydrogen-bonded silver complex in which a single C-H bond is exposed to the catalytic reaction center.
- Annapureddy, Rajasekar Reddy,Jandl, Christian,Bach, Thorsten
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supporting information
p. 7374 - 7378
(2020/08/06)
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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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- Environmentally benign, one-pot synthesis of pyrans by domino Knoevenagel/6π-electrocyclization in water and application to natural products
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In water medium, environmentally benign, facile, and efficient synthesis of pyrans was achieved in good yields by the reactions of a variety of cyclic 1,3-dicarbonyls with several α,β-unsaturated aldehydes. The key strategy was a formal [3+3] cycloaddition by domino Knoevenagel/6π- electrocyclization. This methodology was applied to the synthesis of biologically interesting pyranocoumarin, pyranoquinolinone, and pyranonaphthoquinone derivatives along with selected natural and non-natural products. The Royal Society of Chemistry 2010.
- Jung, Ene Jin,Park, Byung Ho,Lee, Yong Rok
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experimental part
p. 2003 - 2011
(2011/02/19)
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- Simple efficient synthesis of pyranoquinoline alkaloids: Flindersine, khaplofoline, haplamine and their analogues
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An efficient two step synthesis of pyranoquinoline alkaloids is described. Direct treatment of isoprene with 4-hydroxyquinolin-2(1H)-one in the presence of polyphosphoric acid furnished dihydroflindersine in good yield, and which on dehydrogenation led to a new synthesis of flindersine. Khaplofoline, a linear pyranoquinoline alkaloid, was obtained as a minor product. The syntheses of derivatives are also documented.
- Thangavel, Dhanabal,Ravindran, Sangeetha,Moonsamy, Gengan Robert,Palathurai, Mohan Subramaniam
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p. 124 - 126
(2008/02/11)
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- Efficient synthesis of substituted pyranoquinolinones from 2,4-dihydroxyquinoline: Total synthesis of zanthosimuline, cis-3′, 4′-dihydroxy-3′,4′-dihydroflindersine, and orixalone D
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A convenient and efficient synthesis of pyranoquinolinones was achieved using the ethylenediamine diacetate catalyzed reactions of 2,4- dihydroxyquinoline and a variety of α,β-unsaturated aldehydes in good yield. The key feature of these reactions is the
- Wang, Xue,Yong, Rok Lee
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p. 3044 - 3050
(2008/03/14)
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- Synthesis of pyranoquinoline alkaloids via (4+2) cycloaddition reaction
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An easy route to synthesize pyranoquinoline based alkaloids like flindersine, haplamine, N-methylflindersine and its derivatives were performed from the respective 4-hydroxyquinolin-2(1H)-one, dimethyl acrylic acid and para formaldehyde through generation of O-quinone methide intermediates and subjecting (4+2) cycloaddition. Further, dihydro intermediates were oxidized by DDQ.
- Suresh,Dhanabal,Nandha Kumar,Mohan
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- Reactions of heterocyclic quinone methides: A facile entry to synthesize the alkaloid, flindersine and its analogues
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A concise synthesis of pyranoquinoline based alkaloids, flindersine, 8-methoxy flindersine and N-methyl flindersine, from the respective 4-hydroxy-3-methyl-2(1H)-quinolines, using 2,3-dichloro-5,6-dicyano-p-benzoquinone and dimethyl acrylic acid generated through quinone methide intermediates is reported.
- Kumar, R. Nandha,Selvi, S. Thamarai,Suresh,Mohan
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p. 187 - 188
(2007/10/03)
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- One-Pot Preparation of Pyranoquinolinones by Ytterbium(III) Trifluoromethanesulfonate-Catalyzed Reactions: Efficient Synthesis of Flindersine, N-Methylflindersine, and Zanthosimuline Natural Products
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An efficient synthesis of pyranoquinolinones is achieved by ytterbium(III) triflate-catalyzed reaction of 4-hydroxy-2-quinolones with a variety of α,β-unsaturated aldehydes in moderate yields. This new method has been applied to the synthesis of pyranoqui
- Lee, Yong Rok,Kweon, Hyuk Il,Koh, Wha Soo,Min, Kyung Rak,Kim, Youngsoo,Lee, Seung Ho
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p. 1851 - 1855
(2007/10/03)
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- Quinoline Alkaloids. Synthesis of Khaplofoline, Ribalinine, and Flindersine
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Reaction of 4-hydroxy-3-prenylquinolin-2(1H)one (5a) with iodine and silver acetate gave a iodopyranoquinoline (6a), which was then converted into the alkaloids khaplofoline (1) and ribalinine (2).Reaction of 5a with iodine and mercuric oxide afforded a mixture of 6a and its angular isomer 7a; the conversion of latter into flindersine (10) is described.Keywords: Pyranoquinoline Alkaloids, Khaplofoline, Ribalinine, Flindersine
- Subramanian, M.,Mohan, P. S.,Shanmugam, P.,Prasad, K. J. Rajendra
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p. 1016 - 1020
(2007/10/02)
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- A new synthesis of flindersine
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Ketene S,N-acetal from the carbethoxylated isobutyl methyl ketone undergoes thermal cyclization with N-phenyl to give 4-hydroxy-3-(3-methylbutanoyl)-2-thiomethylquinoline (III) which is transformed into the corresponding 4-chloro derivative (IV).The carbonyl group in the side chain at 3-position of VI is converted into the α,β-unsaturated ketone (V) followed by acid hydrolysis to afford 4-keto-2,2-dimethyl-3,4,5,6-tetrahydro-2H-pyranoquinolin-5-one (VI).Reduction of 4-keto group of VI and subsequent dehydration of the resulting alcohol furnishes flindersine (I).
- Anand, R C,Sinha, A K
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p. 560 - 562
(2007/10/02)
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- A CONVENIENT APPROACH TO THE SYNTHESIS OF PRENYL-, FURO- AND PYRANO-QUINOLINE ALKALOIDS OF THE RUTACEAE
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A convenient method for the synthesis of 4-hydroxy-3-prenyl-2-quinolones, wjich have been recognised as precursors to prenyl-, furo- and pyranoquinoline alkaloids of the Rutaceae is described.The methodology involves C,C-diprenylation of 2,4-dihydroxyquinoline followed by partial deallylation using sodium hydrogen telluride reagent.
- Shobana, N.,Yeshoda, P.,Shanmugam, P.
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p. 757 - 762
(2007/10/02)
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- Acetylenchemie. 4 Mitt. Synthese von Haplophyllin und N-Methylflindersin, zwei Wege zu N-funktionalisierten Pyranochinolin-Alkaloiden
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Pyranochinolin-Alkaloide (3), geeignete Vorstufen fuer photobiomimetische Dimerisierungen, sind durch PTC-Reaktion eines 4-Hydroxychinolin-2-ons (1) mit 3-Chlor-3-methylbut-1-in zugaenglich, wobei als Nebenprodukt die Furochinolin-2-on-isomere (5) anfallen.Bei der Synthese von Flindersin (3a) wurde zusaetzlich das Oxazolochinolin-5-on (4) gewonnen; bei der vom N-Methylflindersin (3b) das Bis-(N-methyl-4'-hydroxychinolin-2'-on-3'-yl)-isopenten (7).Alkaloiddimere, deren Bildung aus Intermediaten formulierbar ist, traten nicht auf.Die Entstehung von7 bestaetigt bislang diskutierte Reaktionsablaeufe.Haplophyllin (3c) wurde durch N-Alkylierung von 3a mit 3-Methylcrotonsaeurechlormethylester erstmalig synthetisch dargestellt.
- Reisch, Johannes,Bathe, Andreas,Rosenthal, Bernd H. W.,Salehi-Artimani, Reza A.
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p. 869 - 872
(2007/10/02)
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- Acetylene Chemistry, III: A Simple Approach to Flindersine by Phase-Transfer Reaction
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Reaction of 4-hydroxyquinolin-2-one (4) with 3-chloro-3-methylbut-1-yne by phase-transfer catalysis affords flindersine (3) and 2,3-dihydro-3,3-dimethyl-2-methylenefuroquinolin-4-one (5), whereas indolin-2-one (4g) yields N-(1,1-dimethylprop-2-yn-1-yl)indolin-2-one (19).The reaction mechanism is discussed and studied by varying the reaction conditions.
- Reisch, Johannes,Bathe, Andreas,Salehi-Artimani, Reza A.
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p. 720 - 727
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF FLINDERSINE, ATANINE AND THEIR ANALOGUES
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A new synthesis of the pyranoquinolone alkaloids flindersine (8a), 8-methoxyflindersine (8c), N-methylflindersine (9a), zanthobunglanine (9c), oricine (9d) and veprisine (9e) and the prenylquinolone alkaloids atanine (13a), preskimmianine (13e), N-methylatanine (14a), O-methylglycosolone (14c) and N-methylpreskimmianine (14e) is described.
- Ramesh, M.,Mohan, P. S.,Shanmugam, P.
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p. 4041 - 4050
(2007/10/02)
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