- Sequential multicomponent catalytic synthesis of pyrrole-3-carboxaldehydes: Evaluation of antibacterial and antifungal activities along with docking studies
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A sequential multicomponent synthesis of highly substituted pyrrole-3-carboxaldehydes has been developed under metal-free conditions. This one-pot protocol involves proline-catalyzed direct chemoselective Mannich reaction-cyclization between 1,4-ketoaldehyde and in situ generated Ar/HetAr-imines followed by aerobic oxidative-aromatization at room temperature. A series of fully substituted pyrrole-3-carboxaldehydes and other diverse fused heterocycles have been synthesized. These compounds were tested for in vitro antibacterial and antifungal activities, and the selected ones display significant activity against the tested bacterial strains with a MIC value of 16 μg mL-1, which is close to that of the standard drug chloramphenicol. The bioactivity outcome was further analyzed using docking studies.
- Choudhary, Sachin,Kant, Rajni,Kumar, Indresh,Mir, Nisar A.,Ramaraju, Panduga,Sankaranarayanan, Murugesan,Sharma, Preetika,Singh, Rajnish P.,Singh, Rajpal,Vanaparthi, Satheeshvarma
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supporting information
p. 16329 - 16339
(2020/10/14)
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- Photochemical generation of acyl and carbamoyl radicals using a nucleophilic organic catalyst: Applications and mechanism thereof
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We detail a strategy that uses a commercially available nucleophilic organic catalyst to generate acyl and carbamoyl radicals upon activation of the corresponding chlorides and anhydrides via a nucleophilic acyl substitution path. The resulting nucleophilic radicals are then intercepted by a variety of electron-poor olefins in a Giese-type addition process. The chemistry requires low-energy photons (blue LEDs) to activate acyl and carbamoyl radical precursors, which, due to their high reduction potential, are not readily prone to redox-based activation mechanisms. To elucidate the key mechanistic aspects of this catalytic photochemical radical generation strategy, we used a combination of transient absorption spectroscopy investigations, electrochemical studies, quantum yield measurements, and the characterization of key intermediates. We identified a variety of off-the-cycle intermediates that engage in a light-regulated equilibrium with reactive radicals. These regulated equilibriums cooperate to control the overall concentrations of the radicals, contributing to the efficiency of the overall catalytic process and facilitating the turnover of the catalyst. This journal is
- Balletti, Matteo,De Pedro Beato, Eduardo,Mazzarella, Daniele,Melchiorre, Paolo
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p. 6312 - 6324
(2020/08/24)
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- Visible-Light-Mediated Ring-Opening Strategy for the Regiospecific Allylation/Formylation of Cycloalkanols
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Here we describe a straightforward and efficient approach for regiospecific introduction of an allyl group into cycloalkanol molecules employing a visible-light-mediated ring-opening strategy. A wide range of distally allylated or formylated ketones is fu
- Wang, Junlei,Huang, Binbin,Shi, Chengcheng,Yang, Chao,Xia, Wujiong
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p. 9696 - 9706
(2018/09/06)
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- Development of a Palladium-Catalyzed Carbonylative Coupling Strategy to 1,4-Diketones
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We report on a three-component palladium-catalyzed coupling strategy for accessing a wide range of 1,4-diketones, which represent important precursors to heterocycles. Our method relies on a carbonylative Heck reaction employing substituted allylic alcohols, aryl iodides, and carbon monoxide. The reaction conditions are mild and do not require high CO pressure, and a wide functional group tolerance is revealed, providing the desired 1,4-diketones in moderate to good yields. Furthermore, the methodology is adaptable to the selective installment of 13C-carbon isotopes at either one or both of the carbonyl positions.
- Yin, Hongfei,Nielsen, Dennis U.,Johansen, Mette K.,Lindhardt, Anders T.,Skrydstrup, Troels
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p. 2982 - 2987
(2016/07/06)
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- Organocatalytic Redox Isomerization of Electron-Deficient Allylic Alcohols: Synthesis of 1,4-Ketoaldehydes
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An organocatalytic redox isomerization strategy has been developed for the synthesis of 1,4-ketoaldehydes. DABCO was found to be the best catalyst for the isomerization of -hydroxy enones. With 20 mol % of DABCO as catalyst and DMSO as the solvent high yi
- Mondal, Keshab,Mondal, Buddhadeb,Pan, Subhas Chandra
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p. 4835 - 4840
(2016/07/06)
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- New rhodium(II) catalyzed synthesis of 1,4-dicarbonyl compounds from α-diazo ketones using vinyl ethers as two-carbon synthons
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Rhodium(II) acetate catalyzed reactions of various α-diazo ketones, and vinyl ethers afforded γ-ketoaldehydes or 1,4-diketones in a facile manner. In this process, oxycyclopropanes are formed as intermediates, and are subsequently ring opened in the prese
- Muthusamy, Sengodagounder,Srinivasan, Pandurangan
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p. 6297 - 6300
(2007/10/03)
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- ORGANOTIN HOMOENOLATE EQUIVALENTS - ACCESS TO β-ACYL- AND β-ARYL-PROPIONALDEHYDES THROUGH HETEROSUBSTITUTED ALLYLTINS AND VINYLTINS
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Although, α-ethoxycrotyltributyltin can be used as an equivalent of the homoenolate anion CH3-CHCH2CHO in reactions with acyl chlorides, the non-substituted α-ethoxyallyltributyltin could not be employed in this way. γ-Methoxyvinyltins, easily prepared by hydrostannation of propargylic ethers, are successfully employed as synthetic equivalents of the homoenolate anions -CH2CH2CHO and -CH2CH2COCH3 in reactions with acyl chlorides.A silylated γ-methoxyvinyltin, which is both a vinyltin and an allylsilane, reacts with acyl chlorides and aryl bromides as a promising equivalent of the homoenolate anion -CH2CH2CHO and tolerates a wide range of other reactive functional groups.
- Verlhac, Jean-Baptiste,Pereyre, Michel,Quintard, Jean-Paul
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p. 6399 - 6412
(2007/10/02)
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- Marine Bacteria, I. - Synthesis of Pentabromopseudiline, a Cytotoxic Phenylpyrrole from Alteromonas luteo-violaceus
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A new synthesis of 2,3,4-tribromo-5-(3,5-dibromo-2-hydroxyphenyl)pyrrole (1a, pentabromopseudiline), an antibiotic, enzymeinhibitory and cytotoxic active constituent of the marine bacterium Alteromonas luteo-violaceus, is described.For investigation of structure-activity relationships further 2-phenylpyrroles are investigated.Key step in their synthesis is the Grignard reaction of 2-(1,3-dioxan-2-yl)ethylmagnesium bromide (9d) with benzoyl chlorides yielding γ-phenyl-γ-ketoaldehydes 24, and the Paal-Knorr cyclisation of the latter. - Key Words: Alteromonas luteo-violaceus / Bromopyrrole / Marine bacteria / Pentabromopseudiline
- Laatsch, Hartmut,Pudleiner, Heinz
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p. 863 - 882
(2007/10/02)
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