- The total synthesis of berberine and selected analogues, and their evaluation as amyloid beta aggregation inhibitors
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The total synthesis of berberine and selected analogues. And their evaluation as amyloid β (Aβ) aggregation inhibitors is described. The key step in the synthesis, the assembly of the berberine framework, was accomplished using an intermolecular Heck reaction. Berberine analog 17 incorporating a tertiary amine moiety showed good anti Aβ aggregation activity, water solubility, and almost no toxicity to nerve cells.
- Tajiri, Misato,Yamada, Ryo,Hotsumi, Mayumi,Makabe, Koki,Konno, Hiroyuki
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- Efficient and rapid method for the oxidation of electron-rich aromatic aldehydes to carboxylic acids using improved basic hydrogen peroxide
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An efficient and rapid method for oxidation of electron-rich aromatic aldehydes to their corresponding carboxylic acids in excellent yields was developed. It is based on the oxidation of methoxy-substituted benzaldehydes in methanol with an improved aqueous basic hydrogen peroxide system. Benzaldehydes with electronwithdrawing substituents are oxidized to the corresponding carboxylic acid in excellent yields under mild reaction conditions. Copyright Taylor & Francis Group, LLC.
- Cong, Zhi-Qi,Wang, Chun-Ian,Chen, Tie,Yin, Bing-Zhu
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- Dihydroxylation Studies of Isoquinolinones: Synthesis of the EF-Ring of Lysolipin i
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Inspired by the potent polycyclic xanthone antibiotic lysolipin I, a general study on asymmetric dihydroxylation reactions of variously substituted isoquinolinones was performed. Different isoquinolinones were efficiently prepared, either by a Pomeranz-Fritsch type condensation or a Curtius rearrangement. Under a broad variety of conventional oxygenation procedures, they proved very unreactive. However, either by suitable substitution of the appending aromatic ring or more forcing conditions a dihydroxylation could finally be performed, which allowed the synthesis of the EF-ring of lysolipin I.
- Heinemann, Maximilian J. B.,Voigt, Thomas,Menche, Dirk
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p. 465 - 474
(2021/10/25)
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- Efficient aerobic photooxygenation of aldehydes to carboxylic acids using cobalt(II) phthalocyanine sulfonate as a photosensitizer in organic-water biphasic media
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The aerobic oxidation of a variety of aromatic aldehydes to the corresponding carboxylic acids by molecular oxygen in the presence of 4-carboxyl tetraphenylporphyrin (H2TCPP), methylene blue (MB), cobalt(II) phthalocyanine sulfonate (CoPcS) and FeTCPPCl as water-soluble photosensitizers in organic-water biphasic media at room temperature under either visible light or sunlight is described. The products were obtained with 25–100% conversion and 100% selectivity. This method has a wide range of applicabilities, has a straightforward workup procedure, is chemoselective and proceeds under mild reaction conditions. The resulting products were obtained in good yields in reasonable times.
- Hajimohammadi, Mahdi,Ahmadi Khamesi, Zahra,Nosrati, Parisa
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p. 167 - 173
(2018/10/31)
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- A High Mobility Reactor Unit for R&D Continuous Flow Transfer Hydrogenations
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A suitcase sized mobile reactor unit (MRU) weighing in at less than 10 kg was designed for laboratory scale transfer hydrogenations in continuous flow. Simple cyclohexene and a cosolvent in combination with a palladium-on-charcoal packed bed reactor provided a setup with isolation of nearly all products without the need for further purification. Several functional groups including olefins, triple bonds, nitro-groups, carbonyls, and so forth were effectively reduced with retention times as low as 2 min. Additionally, standard protection groups such as Cbz, benzyl, and allyl ether or esters were removed in high yields. To prove the flexibility of the setup an example of the Mizoroki-Heck reaction was also performed on the MRU. Finally, two scale-up transfer hydrogenation experiments were performed affording isolation of the desired target compounds in 0.5 and 0.8 mol scales with less than 4 h of continuous operation on the MRU.
- Jensen, Rasmus K.,Thykier, Nikolaj,Enevoldsen, Martin V.,Lindhardt, Anders T.
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supporting information
p. 370 - 376
(2017/03/24)
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- Directed ortho-metalation, a new insight into organosodium chemistry
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Finely dispersed metallic sodium in combination with an alkyl chloride RCcan replace organolithium reagents in the ortho-metalation of aromatic compounds (see scheme). The in situ generated base is consumed as soon as it is formed, which avoids Wurtz coupling, the usual side reaction, and the handling and storage of highly reactive alkyl sodium bases. Reaction conditions are mild, the reaction is easy to scale up, and the reagents needed are inexpensive.
- Gissot, Arnaud,Becht, Jean-Michel,Desmurs, Jean Roger,Pevere, Virginie,Wagner, Alain,Mioskowski, Charles
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p. 340 - 343
(2007/10/03)
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- Method for orthometalation of a carbocyclic aromatic derivative bearing at least an electron donor group
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The invention concerns a method for orthometalation of a carbocyclic aromatic derivative bearing at least an electron donor group, characterised in that it consists in reacting said carbocyclic aromatic derivative with an efficient amount of at least one alkaline metal in the presence of a compound of formula (I): RX, wherein: R represents a hydrocarbon radical having 1 to 20 carbon atoms which can be a saturated or unsaturated, linear or branched, acyclic aliphatic radical; a saturated or unsaturated, monocyclic or polycyclic cycloaliphatic radical; a saturated or unsaturated, linear or branched aliphatic radical bearing a cyclic substituent; and X represents a bromine or chlorine atom.
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Page column 9
(2010/01/31)
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- Baeyer-Villiger oxidation of β-aryl substituted unsaturated carbonyl compounds with hydrogen peroxide and catalytic selenium dioxide
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A simple and cheap oxidative procedure using 30% H2O2 and catalytic SeO2 allows to transform 2-aralkylidenecycloalkanones and hydroxy- or alkoxybenzaldehydes to give, in high yields, enollactones and arylformates, respectively.
- Guzman,Mendoza,Garcia,Garibay,Oliveras,Maldonado
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p. 2121 - 2133
(2007/10/02)
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