- Method for preparing 2-bromo-5-fluoroaniline
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The invention discloses a method for preparing 2-bromo-5-fluoroaniline, belonging to the field of organic chemical synthesis. The preparation method comprises the following steps: with 4-fluoroanilineas a raw material, reacting 4-fluoroaniline with acetic anhydride to generate 4-fluoroacetanilide; performing nitrification; replacing acetamido groups with bromine; and reducing nitro groups. Thus,the 2-bromo-5-fluoroaniline with high yield and high purity is prepared. The method has the advantages of high product yield, high purity, easy availability of raw materials and simple operation, andis beneficial to industrial production.
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- Regioselective nitration of anilines with Fe(NO3)3·9H2O as a promoter and a nitro source
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An efficient Fe(NO3)3·9H2O promoted ortho-nitration reaction of aniline derivatives has been developed. This reaction may go through a nitrogen dioxide radical (NO2) intermediate, which is generated by the thermal decomposition of iron(iii) nitrate. The practicality of the present method using nontoxic and inexpensive iron reagents has been shown by the broad substrate scope and applications.
- Gao, Yang,Mao, Yuanyou,Zhang, Biwei,Zhan, Yingying,Huo, Yanping
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p. 3881 - 3884
(2018/06/08)
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- Harnessing the pyrroloquinoxaline scaffold for FAAH and MAGL interaction: Definition of the structural determinants for enzyme inhibition
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This paper describes the development of piperazine and 4-aminopiperidine carboxamides/carbamates supported on a pharmacogenic pyrroloquinoxaline scaffold as inhibitors of the endocannabinoid catabolizing enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). Structure-activity relationships and molecular modelling studies allowed the definition of the structural requirements for dual FAAH/MAGL inhibition and led to the identification of a small set of derivatives (compounds 5e, i, k, m) displaying a balanced inhibitory profile against both enzymes, with compound 5m being the frontrunner of the subset. Favorable calculated physico-chemical properties suggest further investigation for specific analogues.
- Brindisi, Margherita,Brogi, Simone,Maramai, Samuele,Grillo, Alessandro,Borrelli, Giuseppe,Butini, Stefania,Novellino, Ettore,Allarà, Marco,Ligresti, Alessia,Campiani, Giuseppe,Di Marzo, Vincenzo,Gemma, Sandra
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p. 64651 - 64664
(2016/07/23)
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- Discovery and optimization of benzotriazine Di-N-oxides targeting replicating and nonreplicating mycobacterium tuberculosis
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Compounds bactericidal against both replicating and nonreplicating Mtb may shorten the length of TB treatment regimens by eliminating infections more rapidly. Screening of a panel of antimicrobial and anticancer drug classes that are bioreduced into cytotoxic species revealed that 1,2,4-benzotriazine di-N-oxides (BTOs) are potently bactericidal against replicating and nonreplicating Mtb. Medicinal chemistry optimization, guided by semiempirical molecular orbital calculations, identified a new lead compound (20q) from this series with an MIC of 0.31 μg/mL against H37Rv and a cytotoxicity (CC 50) against Vero cells of 25 μg/mL. 20q also had equivalent potency against a panel of single-drug resistant strains of Mtb and remarkably selective activity for Mtb over a panel of other pathogenic bacterial strains. 20q was also negative in a L5178Y MOLY assay, indicating low potential for genetic toxicity. These data along with measurements of the physiochemical properties and pharmacokinetic profile demonstrate that BTOs have the potential to be developed into a new class of antitubercular drugs.
- Chopra, Sidharth,Koolpe, Gary A.,Tambo-Ong, Arlyn A.,Matsuyama, Karen N.,Ryan, Kenneth J.,Tran, Tran B.,Doppalapudi, Rupa S.,Riccio, Edward S.,Iyer, Lalitha V.,Green, Carol E.,Wan, Baojie,Franzblau, Scott G.,Madrid, Peter B.
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p. 6047 - 6060
(2012/09/05)
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- Mild, efficient and selective nitration of anilides, non-activated and moderately activated aromatic compounds with ammonium molybdate and nitric acid as a new nitrating agent
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Ammonium molybdate [Mo(VI)] is operationally simple, environmentally safe and inexpensive reagent. Regioselective nitration of anilides, non-activated and moderately activated aromatic compounds could be afforded by employing ammonium molybdate and nitric acid as mild and effective nitrating agent. This procedure works efficiently under reflux conditions to prepare mononitroderivatives of anilides, non-activated and moderately activated aromatic compounds in good to excellent yield with high regioselectivity.
- Sana, Sariah,Rajanna,Ali, Mir Moazzam,Saiprakash
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- Structure-activity relationship of omeprazole and analogues as Helicobacter pylori urease inhibitors
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Helicobacter pylori urease belongs to a family of highly conserved urea- hydrolyzing enzymes. A common feature of these enzymes is the presence of two Lewis acid nickel ions and a reactive cysteine residue in the active site. The H+/K+-ATPase inhibitor omeprazole is a prodrug of a sulfenamide which covalently modifies cysteine residues on the luminal side of the H+/K+- ATPase of gastric parietal cells. Omeprazole and eight analogues were selected based on their chemical, electronic, and kinetic properties, and each was incubated with viable H. pylori in phosphate-buffered saline at pH 7.4 for 30 min, after which 100 mM urea was added and the amount of ammonia formed analyzed after a further 10 min. Inhibition between 0% and 100% at a 0.1 mM concentration was observed for the different analogues and could be expressed as a function of the pK(a)-value of the pyridine, the pK(a)-value of the benzimidazole, the overall lipophilicity, and, most importantly, the rate of sulfenamide formation, in a quantitative structure-activity relationship. The inhibition was potentiated by a lower pH (favoring the formation of the sulfenamide) but abolished in the presence of β- mercaptoethanol (a scavenger of the sulfenamide). Structural analogues incapable of yielding the sulfenamide did not inhibit ammonia production. Treatment of Helicobacter felis-infected mice with 230 μmol/kg flurofamide b.i.d. for 4 weeks, known to potently inhibit urease activity in vivo, as a means of eradicating the infection, was tested and compared with the effect of 125 μmol/kg omeprazole b.i.d. for 4 weeks. Neither treatment proved efficacious.
- Kuhler,Fryklund,Bergman,Weilitz,Lee,Larsson
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p. 4906 - 4916
(2007/10/03)
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- Hypoxia-Selective Agents Derived from Quinoxaline 1,4-Di-N-oxides
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Hypoxic cells, which are a common feature of solid tumors, but not normal tissues, are resistant to both anticancer drugs and radiation therapy.Thus the identification of drugs with selective toxicity toward hypoxic cells is an important objective in anticancer chemotherapy.The benzotriazine di-N-oxide (SR 4233, Tirapazamine) has been shown to be an efficient and selective cytotoxin for hypoxic cells.Since the bioreductive activation of Tirapazamine is thought to be due to the presence of the 1,4-di-N-oxide moiety, a series of 3-aminoquinoxaline-2-carbonitrile 1,4-di-N-oxides with a range of electron-donating and -withdrawing substituents in the 6- and /or 7- positions has been synthesized and evaluated for toxicity to hypoxic cells.Electrochemical studies of the quinoxaline di-N-oxides and Tirapazamine showed that as the electron-withdrawing nature of the 6(7)-substituent increases, the reduction potential becomes more positive and the compound is more readily reduced.Apart from the unsubstituted 6a and the 6,7-dimethyl derivative 6c, the quinoxaline di-N-oxide have reduction potentials significantly more positive than Tirapazamine (Epc -0.90 V).The most potent cytotoxins to cells in culture were the 6,7-dichloro and 6,7-difluoro derivatives 6i and 6l, which were 30-fold more potent than Tirapazamine.The 6(7)-fluoro and 6(7)-chloro compounds, 6e and 6h, showed the greatest hypoxia selectivity.Four of the compounds, 6e, 6f, 6h and 6i, killed the inner cells of multicellular tumor spheroids in vitro.In vivo Balb/c mice tolerated a dose of these four compounds twice the size of that of Tirapazamine.This study demonstrates that quinoxaline 1,4-di-N-oxides could provide useful hypoxia-selective therapeutic agents.
- Monge, Antonio,Palop, Juan A.,Cerain, Adela Lopez de,Senador, Virginia,Martinez-Crespo, Francisko J.,et al.
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p. 1786 - 1792
(2007/10/02)
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- Polyaza Heterocycles. Part 2. Nucleophilic Substitution of Halogens in Halogenoquinoxalinocinnolines
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10-Chloroquinoxalinocinnoline readily undergoes methoxydechlorination when treated with sodium methoxide.The 1-, 2-, 3-, 4- and 9-chloro isomers are unreactive towards this reagent, but the 9,10-dichloro derivative undergoes substitution of both chlorines (the 10-position being much the more reactive).The 9- and 10-bromo analogues are both unreactive towards sodium methoxide, but the 9- and 10-fluoro analogues are both highly reactive, to the extent that it has not been possible even to isolate the 10-fluoro compound.Routes to 9- and 10-piperidinoquinoxalinocinnolines are described.
- Ahmad, Arshad,Dunbar, Linda J.,Green, Iain G.,Harvey, Ian W.,Shepherd, Thomas,et al.
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p. 2751 - 2758
(2007/10/02)
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- HETEROCYCLIC SYSTEMS CONTAINING BRIDGEHEAD NITROGEN ATOMS. PART LXVIII. REACTION OF 5-FLUOROBENZIMIDAZOLYL-2-THIONE WITH CHLOROACETIC ACID: STUDIES OF ORIENTATION OF CYCLIZATION IN THE SYNTHESES OF 6-FLUORO- AND 7-FLUOROTHIAZOLOBENZIMIDAZOL-3(2H)-ONES
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4-Fluoroaniline on successive acetylation, nitration and hydrolysis affords 4-fluoro-2-nitroaniline which on reduction with Raney nickel and hydrazine hydrate followed by treatment of the resulting diamine with carbon disulphide in situ gives 5-fluorobenzimidazolyl-2-thione.The thione on condensation with chloroacetic acid yields acetic acid which on cyclization in a mixture of acetic anhydride and pyridine furnishes two isomers viz. 6-fluoro- and 7-fluorothiazolobenzimidazol-3(2H)-ones.The condensation of thione with 1,2-dibromoethane affords sym-bis-(5-fluorobenzimidazo-2-yl-mercapto)ethane.The structural assignments for the 6-fluoro- and 7-fluorothiazolobenzimidazol-3(2H)-ones have been made by 1H-NMR spectral data using two different methods.
- Pujari, H. K.,Sharma, B. R.,Dahiya, Rajender,Kumar, Sudhir,Murakami, Yasuoki,Tani, Masanobu
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p. 343 - 355
(2007/10/02)
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- Hydroxylamine derivative of 5-nitro-8-hydroxy quinoline
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Novel hydroxylamino derivatives of the formula wherein Ar is selected from the group consisting of mono- and polycyclic aromatics and hetero-aromatics, both optionally substituted with at least one member of the group consisting of --OH, halogen, --NO2, --CN, STR1 --R7, --OR8, STR2 --SO2 R12, --SO3 R13, --COOR14, aryl of 6 to 14 carbon atoms, --OR16, --CH2 --CN and --CH2 SO2 --R15, R1, R2, R3, R4, R5 and R6 are individually selected from the group consisting of hydrogen and alkyl of 1 to 8 carbon atoms, R7 and R8 are optionally unsaturated alkyl of 1 to 8 carbon atoms optionally substituted with at least one member of the group consisting of halogen and cyano, R9, R10, R11, R12 and R13 are alkyl of 1 to 8 carbon atoms, Z is selected from the group consisting of hydrogen, optionally unsaturated alkyl of 1 to 8 carbon atoms and acyl of an organic carboxylic acid of 2 to 18 carbon atoms, R14 is selected from the group consisting of hydrogen and alkyl of 1 to 8 carbon atoms, R15 is selected from the group consisting of alkyl of 1 to 8 carbon atoms and aryl of 6 to 14 carbon atoms optionally substituted with an alkyl of 1 to 8 carbon atoms, R16 is aryl of 6 to 14 carbon atoms optionally substituted with a member of the group consisting of alkyl of 1 to 8 carbon atoms, halogen and --NO2, the substituents of Ar being able to form rings containing at least one heteroatom selected from the group consisting of oxygen, nitrogen and sulfur and their non-toxic agriculturally acceptable acid addition salts with the proviso Ar is not phenyl nor phenyl with one methyl in the 2,3 or 4 position, a nitro in the 2- or 4-position, a chlorine in the 3- or 4-position, a bromine in the 4-position or a --CF3 in the 4-position nor 2,4-dinitrophenyl nor 2-nitro-4-trifluoromethylphenyl nor 2,6-dinitrophenyl nor 2,4,6-trinitrophenyl nor 2,4-dinitro-6-trifluoromethylphenyl useful for increasing vegetation growth and increasing crop yields and their preparation.
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