- Nitration of deactivated aromatic compounds via mechanochemical reaction
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A variety of deactivated arenes were nitrated to their corresponding nitro derivatives in excellent yields under high-speed ball milling condition using Fe(NO3)3·9H2O/P2O5 as nitrating reagent. A radical involved mechanism was proposed for this facial, eco-friendly, safe, and effective nitration reaction.
- Wu, Jian-Wei,Zhang, Pu,Guo, Zhi-Xin
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supporting information
(2021/05/05)
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- Total Synthesis of Marine Alkaloid Hyellazole and its Derivatives
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The total synthesis of the naturally occurring marine alkaloids hyellazole and chlorohyellazole was attempted from the corresponding easily accessible 2-methyl-1-ketotetrahydrocarbazoles obtained through the Japp–Klingemann reaction, followed by Fischer indole cyclization and subsequent Grignard coupling with phenylmagnesium bromide. Grignard coupling with 2-methyl-1-ketotetrahydrocarbazole unfortunately led directly to 2-methyl-1-phenylcarbazole through dehydration followed by aromatization through aerial oxidation, but application of the same reaction conditions to 6-chloro-2-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-one, with careful treatment, led to the isolation of 6-chloro-2-methyl-1-phenyl-4,9-dihydro-3H-carbazole. However, selenium dioxide oxidation of this dihydrochloro derivative led to the formation of 6-chloro-2-methyl-1-phenyl-9H-carbazole. A different route was then adopted: a suitably substituted aromatic amine was used to establish the substitution pattern of the required carbazole derivative with a bromo group at C-1, and the required phenyl group at the 1-postion was then attached through Suzuki–Miyaura cross-coupling to furnish hyellazole.
- Chakraborty, Suchandra,Saha, Chandan
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p. 2013 - 2021
(2018/05/15)
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- Synthesis and Antibacterial Activity of Novel 4-Bromo-1H-Indazole Derivatives as FtsZ Inhibitors
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A series of novel 4-bromo-1H-indazole derivatives as filamentous temperature-sensitive protein Z (FtsZ) inhibitors were designed, synthesized, and assayed for their in vitro antibacterial activity against various phenotypes of Gram-positive and Gram-negative bacteria and their cell division inhibitory activity. The results indicated that this series showed better antibacterial activity against Staphylococcus epidermidis and penicillin-susceptible Streptococcus pyogenes than the other tested strains. Among them, compounds 12 and 18 exhibited 256-fold and 256-fold more potent activity than 3-methoxybenzamide (3-MBA) against penicillin-resistant Staphylococcus aureus, and compound 18 showed 64-fold better activity than 3-MBA but 4-fold weaker activity than ciprofloxacin in the inhibition of S. aureus ATCC29213. Particularly, compound 9 presented the best activity (4 μg/mL) against S. pyogenes PS, being 32-fold, 32-fold, and 2-fold more active than 3-MBA, curcumin, and ciprofloxacin, respectively, but it was four times less active than oxacillin sodium. In addition, some synthesized compounds displayed moderate inhibition of cell division against S. aureus ATCC25923, Escherichia coli ATCC25922, and Pseudomonas aeruginosa ATCC27853, sharing a minimum cell division concentration of 128 μg/mL.
- Wang, Yi,Yan, Mi,Ma, Ruixin,Ma, Shutao
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p. 266 - 274
(2015/04/14)
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- Synthesis and SAR of acyclic HCV NS3 protease inhibitors with novel P4-benzoxaborole moieties
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We have synthesized and evaluated a new series of acyclic P4-benzoxaborole-based HCV NS3 protease inhibitors. Structure-activity relationships were investigated, leading to the identification of compounds 5g and 17 with low nanomolar potency in the enzymatic and cell-based replicon assay. The linker-truncated compound 5j was found to exhibit improved absorption and oral bioavailability in rats, suggesting that further reduction of molecular weight and polar surface area could result in improved drug-like properties of this novel series.
- Li, Xianfeng,Zhang, Suoming,Zhang, Yong-Kang,Liu, Yang,Ding, Charles Z.,Zhou, Yasheen,Plattner, Jacob J.,Baker, Stephen J.,Bu, Wei,Liu, Liang,Kazmierski, Wieslaw M.,Duan, Maosheng,Grimes, Richard M.,Wright, Lois L.,Smith, Gary K.,Jarvest, Richard L.,Ji, Jing-Jing,Cooper, Joel P.,Tallant, Matthew D.,Crosby, Renae M.,Creech, Katrina,Ni, Zhi-Jie,Zou, Wuxin,Wright, Jon
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supporting information; experimental part
p. 2048 - 2054
(2011/04/24)
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- Studies toward diazonamide A: Initial synthetic forays directed toward the originally proposed structure
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A brief introduction into the chemistry of diazonamide A (1) is followed by first-generation sequences to access the originally proposed structure for this unusual marine natural product. These explorations identified a route capable of delivering a model compound possessing the complete heteroaromatic core of the natural product, highlighting in the process several unanticipated synthetic challenges which led both to new methodology as well as an improved synthetic plan that was successfully applied to fully functionalized intermediates.
- Nicolaou,Snyder, Scott A.,Huang, Xianhai,Simonsen, Klaus B.,Koumbis, Alexandros E.,Bigot, Antony
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p. 10162 - 10173
(2007/10/03)
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- Polyaza heterocycles. Part 3. Halogenation of 1-substituted quinoxalinocinnolines: mechanistic implications
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Since it has been proposed that halogenation of quinoxalinocinnolines at C-10, using hydrogen chloride or bromide in chloroform, occurs through initial protonation of the substrate at N-12, attempts have been made to inhibit this protonation by the introduction of an additional substituent at C-1.Where this substituent is chloro, bromo or methyl, chlorination still occurs preferentially at C-10, although the yield and the reaction rate decrease along the series, lending weight to the mechanistic proposal.
- Harvey, Ian W.,Smith, David M.,White, Charles R.
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p. 1699 - 1704
(2007/10/03)
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- Benzazepine formation by the 1.7 electrocyclisations of diene-conjugated nitrile ylides: studies on relative rates of cyclisation via intramolecular competition reactions
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A series of reactions has been carried out using reactants of the type 19 in which nitrile ylide cyclisation on to the substituent at the 6 position is in competition with cyclisation on to the unsubstituted phenyl group at the 2 position.The relative reactivity of the two groups, determined by measuring the product ratio 20:21, was determined for a series of 6-substituents as shown in Table 8.This is the first collection of such data for the electrocyclisation of 1,3-dipolar intermediates.Alkenyl groups and the thiophene ring were found to be > 100 x more reactive than phenyl.In cases where the 6-substituent was a substituted aryl group it was found that all aromatic substituents at the 3' and 4' positions, irrespective of their electronic nature, increased the reactivity of the ring relative to that of the unsubstituted phenyl group.In contrast, a methyl group at the 2' position produced strong deactivation.The results are discussed in terms of the steric and electronic effects of the substituents.
- Cullen, Kevin E.,Sharp, John T.
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p. 2565 - 2580
(2007/10/02)
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- Synthesis and some reactions of 6-bromooxindole
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An efficient synthesis of 4- and 6-bromooxindoles, previously unknown compounds, from 6- and 4-amino-2-nitrotoluenes and the transformation of 6-bromooxindole to 3-acylated derivatives are described.
- Kosuge,Ishida,Inaba,Nukaya
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p. 1414 - 1418
(2007/10/02)
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- Palladium-Catalyzed Reactions in the Synthesis of 3- and 4-Substituted Indoles. Approaches to Ergot Alkaloids
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An efficient synthesis of 4-bromo-1-tosylindole (10) based on the Pd(II)-catalyzed cyclization of an o-ethenylaniline p-toluenesulfonamide has been developed.A Pd(0) oxidative addition-olefin insertion-β-hydride elimination cycle converted 10 to a number of 4-substituted 1-tosylindoles.Selective electrophilic substitutions at the 3-position of 10 provided access to the 3-(chloromercurio)- (18) and 3-iodo-1-tosylindoles (22).Transmetalation to palladium and allyl chloride insertion converted 18 to 3-allyl-4-bromo-1-tosylindole (20) which could be cyclized to the benzindoline 21.A Pd(0) oxidative addition-olefin insertion-β-hydride elimination cycle converted the 3-iodo compound 22 to a number of 4-bromo-3-substituted 1-tosylindoles including 24, a potential precursor to optically active tryptophans.
- Harrington, Peter J.,Hegedus, Louis S.
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p. 2658 - 2662
(2007/10/02)
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- Electrophilic aromatic substitution. Part 24. The nitration of isopropylbenzene, 2- and 4-isopropyltoluene, 1-chloro-4-isopropylbenzene, 4-isopropylanisole, and 2-bromotoluene: Nitrodeisopropylation
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The kinetics and products of nitration in aqueous sulphuric acid of the title compounds have been studied. 4-Isopropyl-phenol and -anisole are nitrated at or near the encounter rate. In 65-79% H2SO4 2-isopropyltoluene suffers ca. 25% ipso-attack; the only fate of W iPri (ipso-Wheland intermediate) is nitrodeisopropylation. From 4-isopropyltoluene WiPri is also nitrodeisopropylated, but some 1,2-nitro-migration may occur. From the same compound WiMe may be captured by water, rearrange, or give 4-methylacetophenone; a mechanism is proposed for the formation of the last compound. Nitrodeisopropylation occurs without the assistance of water. With 4-isopropylanisole, demethoxylation and nitrodeisopropylation are consequences of the formation of WiPri. The results are consistent with increasing attack at C-4 with increasing acidity, loss of isopropyl without assistance from water, and decomposition of the unobserved intermediate, 4-isopropyl-4-nitrocyclohexa-2,5-dienone, by two processes. One, acid-catalysed process gives 4-nitrophenol and possibly 4-isopropyl-2-nitrophenol. The other, probably radical, process gives 4-isopropyl-2-nitrophenol. In contrast to 4-bromotoluene, 2-bromotoluene is not nitrodebrominated.
- Manglik, Ajay K.,Moodie, Roy B.,Schofield, Kenneth,Tobin, Geoffrey D.,Coombes, Robert G.,Hadjigeorgiou, Panicos
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p. 1606 - 1616
(2007/10/02)
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