- XRD studies, vibrational spectra, andmolecular structure of 1h-imidazo [4,5-b]pyridine based on DFT quantum chemical calculations
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The molecular structures and vibrational properties of 1H-imidazo[4,5-b]pyridine in its monomeric and dimeric forms are analyzed and compared to the experimental results derived from the X-ray diffraction (XRD), infrared (IR), and Raman studies. The theoretical data are discussed on the basis of density functional theory (DFT) quantum chemical calculations using Lee-Yang-Parr correlation functional (B3LYP) and 6-31G(d,p) basis. This compound crystallizes in orthorhombic structure, space group Pna21(C2v9) and Z = 4. The planar conformation of the skeleton and presence of the N-H· · ·N hydrogen bond was found to be characteristic for the studied system. The temperature dependence of IR and Raman modes was studied in the range 4-294 K and 8-295 K, respectively. The normal modes, which are unique for the imidazopyridine derivatives are identified.
- Dyminska,Gagor,Maczka,Weglinskia,Hanuzaa
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Read Online
- Convenient synthesis of imidazo[1,5-a]pyrimidine derivatives and their unusual recyclization into 3H-imidazo[4,5-b]pyridine derivatives
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[Figure not available: see fulltext.] New derivatives of imidazo[1,5-a]pyrimidine have been synthesized by cyclization of in situ generated 1H-imidazol-4(5)-amine with 1,3-diketones or malondialdehyde derivatives. Utilization of asymmetrical 1,3-diketones leads to the formation of a mixture of regioisomers. The discovered conversion of imidazo[1,5-a]pyrimidine core into 3H-imidazo[4,5-b]pyridine that takes place only under acidic conditions can be considered as a new version of Dimroth rearrangement involving cleavage of C–N bond and formation of C–C bond.
- Smirnova, Olga V.,Tolkunov, Andrew S.,Tolkunov, Sergei V.,Tolkunov, Valery S.
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p. 554 - 559
(2021/06/14)
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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- In Situ Formation of Frustrated Lewis Pairs in a Water-Tolerant Metal-Organic Framework for the Transformation of CO2
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Frustrated Lewis pairs (FLPs) consist of sterically hindered Lewis acids and Lewis bases, which provide high catalytic activity towards non-metal-mediated activation of “inert” small molecules, including CO2 among others. One critical issue of homogeneous FLPs, however, is their instability upon recycling, leading to catalytic deactivation. Herein, we provide a solution to this issue by incorporating a bulky Lewis acid-functionalized ligand into a water-tolerant metal-organic framework (MOF), named SION-105, and employing Lewis basic diamine substrates for the in situ formation of FLPs within the MOF. Using CO2 as a C1-feedstock, this combination allows for the efficient transformation of a variety of diamine substrates into benzimidazoles. SION-105 can be easily recycled by washing with MeOH and reused multiple times without losing its identity and catalytic activity, highlighting the advantage of the MOF approach in FLP chemistry.
- Shyshkanov, Serhii,Nguyen, Tu N.,Ebrahim, Fatmah Mish,Stylianou, Kyriakos C.,Dyson, Paul J.
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supporting information
p. 5371 - 5375
(2019/03/17)
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- Cobalt-catalyzed synthesis of N-containing heterocycles: Via cyclization of ortho -substituted anilines with CO2/H2
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The CO2-involved synthesis of chemicals is of great significance from the green and sustainable chemistry viewpoint. Herein, we report a non-noble metal catalytic system composed of CoF2, CsF and P(CH2CH2PPh2)3 (denoted as PP3) for the synthesis of N-containing heterocycles from ortho-substituted anilines and CO2/H2. Mechanism investigation indicates that [Co(PP3)H(CO2)]+ is a catalytically active intermediate under working conditions; and CsF plays important roles in activating ortho-substituted anilines via hydrogen bond interactions, thus promoting the formation of the final products. This catalytic system is highly efficient, and allows a wide scope of ortho-substituted anilines, together with excellent functional group tolerance, affording various N-containing heterocycles in good to excellent yields.
- Ke, Zhengang,Yu, Bo,Wang, Huan,Xiang, Junfeng,Han, Juanjuan,Wu, Yunyan,Liu, Zhenghui,Yang, Peng,Liu, Zhimin
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p. 1695 - 1701
(2019/04/10)
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- Fluorescing Isofunctional Ribonucleosides: Assessing Adenosine Deaminase Activity and Inhibition
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The enzymatic conversion of isothiazolo[4,3-d]pyrimidine-based adenosine (tzA) and 2-aminoadenosine (tz2-AA) analogues to the corresponding isothiazolo[4,3-d]pyrimidine-based inosine (tzI) and guanosine (tzG) derivatives is evaluated and compared to the conversion of native adenosine to inosine. Henri–Michaelis–Menten analyses provides the foundation for a high-throughput screening assay, and the efficacy of the assay is showcased by fluorescence-based analysis of tzA conversion to tzI in the presence of known and newly synthesized inhibitors.
- Ludford, Paul T.,Rovira, Alexander R.,Fin, Andrea,Tor, Yitzhak
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p. 718 - 726
(2019/03/05)
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- Synthesis and Antibacterial Activity of Novel 4″-O-desosaminyl clarithromycin derivatives with 11, 12-arylalkyl side chains
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A series of novel 4″-O-desosaminyl clarithromycin derivatives with 11, 12-arylalkyl side chains was synthesized by coupling 6-deoxy-desosamine donors (18, 19) with 4″-OH of compounds 5a–c. The activities of the target compounds were tested against a series of macrolide-sensitive and macrolide-resistant pathogens. Some of them showed activities against macrolide sensitive and resistant pathogens, and compounds 21d and 21e displayed significant improvement of activities against resistant pathogens.
- Zhao, Zhe-Hui,Zhu, Di,Zhang, Xiao-Xi,Luo, Zhi-Gang,Lei, Ping-Sheng
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- Atom-Specific Mutagenesis Reveals Structural and Catalytic Roles for an Active-Site Adenosine and Hydrated Mg2+ in Pistol Ribozymes
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The pistol RNA motif represents a new class of self-cleaving ribozymes of yet unknown biological function. Our recent crystal structure of a pre-catalytic state of this RNA shows guanosine G40 and adenosine A32 close to the G53–U54 cleavage site. While the N1 of G40 is within 3.4 ? of the modeled G53 2′-OH group that attacks the scissile phosphate, thus suggesting a direct role in general acid–base catalysis, the function of A32 is less clear. We present evidence from atom-specific mutagenesis that neither the N1 nor N3 base positions of A32 are involved in catalysis. By contrast, the ribose 2′-OH of A32 seems crucial for the proper positioning of G40 through a H-bond network that involves G42 as a bridging unit between A32 and G40. We also found that disruption of the inner-sphere coordination of the active-site Mg2+ cation to N7 of G33 makes the ribozyme drastically slower. A mechanistic proposal is suggested, with A32 playing a structural role and hydrated Mg2+ playing a catalytic role in cleavage.
- Neuner, Sandro,Falschlunger, Christoph,Fuchs, Elisabeth,Himmelstoss, Maximilian,Ren, Aiming,Patel, Dinshaw J.,Micura, Ronald
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supporting information
p. 15954 - 15958
(2017/11/21)
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- Microwave-Assisted C-2 Direct Alkenylation of Imidazo[4,5-b]pyridines: Access to Fluorescent Purine Isosteres with Remarkably Large Stokes Shifts
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We describe herein the first C-2 direct alkenylation of the valuable 3H-imidazo[4,5-b]pyridine promoted by microwave-assisted Pd/Cu co-catalysis. The reaction is rapid and compatible with a wide range of functional groups either on the imidazo[4,5-b]pyridine ring or on the styryl bromides thereby leading to the isolation of 23 compounds with moderate to good yields. The relevance of this method is demonstrated by its application to the synthesis of new cross-conjuguated push-pull 2-vinyl- and 2-alkynylimidazo[4,5-b]pyridines characterized by satisfactory fluorescence quantum yields and remarkable solvatofluorochromic properties.
- Baladi, Tom,Granzhan, Anton,Piguel, Sandrine
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p. 2421 - 2434
(2016/06/01)
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- Direct Alkynylation of 3H-Imidazo[4,5-b]pyridines Using gem-Dibromoalkenes as Alkynes Source
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C2 direct alkynylation of 3H-imidazo[4,5-b]pyridine derivatives is explored for the first time. Stable and readily available 1,1-dibromo-1-alkenes, electrophilic alkyne precursors, are used as coupling partners. The simple reaction conditions include an inexpensive copper catalyst (CuBr·SMe2 or Cu(OAc)2), a phosphine ligand (DPEphos) and a base (LiOtBu) in 1,4-dioxane at 120 °C. This C-H alkynylation method revealed to be compatible with a variety of substitutions on both coupling partners: heteroarenes and gem-dibromoalkenes. This protocol allows the straightforward synthesis of various 2-alkynyl-3H-imidazo[4,5-b]pyridines, a valuable scaffold in drug design.
- Aziz, Jessy,Baladi, Tom,Piguel, Sandrine
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p. 4122 - 4133
(2016/06/09)
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- Atmospheric CO2 promoted synthesis of N-containing heterocycles over B(C6F5)3 catalyst
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B(C6F5)3 combined with atmospheric CO2 was found to be highly effective for the cyclization of ortho-substituted aniline derivatives with N,N-dimethylformamide (DMF), and a series of N-containing heterocycles including benzothiazoles, benzimidazoles, quinazolinone and benzoxazole were obtained in good to excellent yields.
- Gao, Xiang,Yu, Bo,Mei, Qingqing,Yang, Zhenzhen,Zhao, Yanfei,Zhang, Hongye,Hao, Leiduan,Liu, Zhimin
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p. 8282 - 8287
(2016/10/11)
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- Diversified facile synthesis of benzimidazoles, quinazolin-4(3H)-ones and 1,4-benzodiazepine-2,5-diones via palladium-catalyzed transfer hydrogenation/condensation cascade of nitro arenes under microwave irradiation
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A highly efficient diversified methodology for preparation of benzimidazole, quinazolin-4(3H)-ones and 1,4-benzodiazepine-2,5-diones is established using a palladium-catalyzed transfer hydrogenation (CTH)/condensation cascade of o-nitroaniline and o-nitrobenzamides in a triethylamine-formic acid azeotropic mixture (2:5) under microwave irradiation.
- Zhu, Kaicheng,Hao, Jian-Hong,Zhang, Cheng-Pan,Zhang, Jiajun,Feng, Yiqing,Qin, Hua-Li
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p. 11132 - 11135
(2015/03/05)
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- Efficient aerobic oxidative synthesis of benzimidazoles with Fe(III) based PEG1000 dicationic imidazolium ionic liquid/toluene temperature-dependent biphasic system
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A green protocol for the synthesis of benzimidazoles with Fe(III) based PEG1000 dicationic imidazolium ionic liquid ([PEG1000mim2][FeCl4]2)/toluene temperature-dependent biphasic system was described. Conformed by IR analysis, FeCl4-is the dominating anion species. It could be seen that aldehydes arylamines and aromatic aldehydes bearing electron-deficient group (-Cl,-Br,-NO2) and electron-rich groups(-OH, -N(CH3)2) on the aromatic rings gave good yields (78-96%). Moreover, the Fe(III) based PEG1000 dicationic imidazolium ionic liquid could be recycled and reused without significant loss of catalytic activity after seven runs.
- Wang, Zhao-Gang,Xia, Yong-Gen,Jin, Yong,Lu, Ming
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p. 103 - 106
(2015/04/21)
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- Supercritical methanol as solvent and carbon source in the catalytic conversion of 1,2-diaminobenzenes and 2-nitroanilines to benzimidazoles
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Benzimidazoles and N-methylbenzimidazoles were synthesized by simply heating 1,2-diaminobenzenes in supercritical methanol over copper-doped porous metal oxides. These catalysts were derived from synthetic hydrotalcites that only contain earth-abundant starting materials. The carbon equivalents needed for the construction of the benzimidazole core originated from the solvent itself, which is known to undergo reforming to hydrogen and carbon monoxide through the formation of a formaldehyde intermediate. A variety of 1,2-diaminobenzenes were converted to the corresponding mixtures of benzimidazoles and N-methylated analogues in good yields. Interestingly, the more challenging, but readily available 2-nitroanilines, which require an additional reduction step prior to cyclization, could also be successfully converted to benzimidazoles in high selectivity. Furthermore, various other alcohols were applied besides methanol, to obtain 2-alkyl- and 1,2-dialkylbenzimidazoles. Preliminary mechanistic insights into the origins of N-alkylation as well as the reactivity of the nitro derivatives are discussed.
- Sun, Zhuohua,Bottari, Giovanni,Barta, Katalin
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p. 5172 - 5181
(2015/12/08)
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- Method For Preparing Nitrogen Compounds
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The present invention relates to a method for preparing nitrogen compounds using carbon dioxide, and to the use of the method in the production of vitamins, pharmaceutical products, adhesives, acrylic fibres, synthetic leathers, pesticides, herbicides, antifungal agents and fertilisers. The invention also relates to a method for producing vitamins, pharmaceutical products, adhesives, acrylic fibres, synthetic leathers, pesticides, herbicides, antifungal agents and fertilisers, which includes a step of preparing nitrogen compounds using the method of the invention. The invention further relates to a method for preparing labelled nitrogen compounds using carbon dioxide and to the uses thereof.
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Paragraph 0192; 0193
(2015/06/03)
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- A green and efficient method for synthesis of benzimidazoles using nano-Fe3O4 in PEG-400/H2O aqueous system under ambient conditions at room temperature
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In this paper, a green and facile protocol was described which was efficient for synthesis of benzimidazoles using nano-Fe3O4 catalyst with continuous bubbling of air as the oxidant in PEG-400/H 2O aqueous system at room temperature. This protocol afforded the target products in good to excellent yields and the catalytic system could be recycled and reused without significant loss of catalytic activity. Copyright
- Wang, Zhao-Gang,Zhu, Jie,Zhu, Zhou-Shuo,Xu, Jian,Lu, Ming
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p. 436 - 440
(2014/06/09)
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- Controlling molecular tautomerism through supramolecular selectivity
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We have isolated the stable as well as the metastable tautomers of 1-deazapurine in the solid state by exploiting principles of supramolecular selectivity in the context of cocrystal design.
- Epa, Kanishka,Aakeroey, Christer B.,Desper, John,Rayat, Sundeep,Chandra, Kusum Lata,Cruz-Cabeza, Aurora J.
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p. 7929 - 7931
(2013/09/02)
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- An efficient one-pot synthesis of condensed imidazoles using pentafluorophenylammonium triflate as novel, metal-free and reusable catalyst
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A superior method of synthesis of condensed imidazoles by the catalytic action of pentafluorophenylammonium triflate on the reaction of 1,2-diaminoaromatics with orthoesters is described. The catalyst is reusable and can be applied several times without considerable decrease in the yields and rates of the reaction.
- Montazeri, Naser,Esmaeili, Abbas
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p. 3446 - 3448
(2013/05/21)
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- Influence of the nucleobase and anchimeric assistance of the carboxyl acid groups in the hydrolysis of amino acid nucleoside phosphoramidates
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Nucleoside phosphoramidates (NPs) are a class of nucleotide analogues that has been developed as potential antiviral/antitumor prodrugs. Recently, we have shown that some amino acid nucleoside phosphoramidates (aaNPs) can act as substrates for viral polymerases like HIV-1 RT. Herein, we report the synthesis and hydrolysis of a series of new aaNPs, containing either natural or modified nucleobases to define the basis for their differential reactivity. Aqueous stability, kinetics, and hydrolysis pathways were studied by NMR spectroscopy at different solution pD values (5-7) and temperatures. It was observed that the kinetics and mechanism (P-N and/or P-O bond cleavage) of the hydrolysis reaction largely depend on the nature of the nucleobase and amino acid moieties. Aspartyl NPs were found to be more reactive than Gly or β-Ala NPs. For aspartyl NPs, the order of reactivity of the nucleobase was 1-deazaadenine>7- deazaadenine>adenine>thymine≥3-deazaadenine. Notably, neutral aqueous solutions of Asp-1-deaza-dAMP degraded spontaneously even at 4°C through exclusive P-O bond hydrolysis (a 50-fold reactivity difference for Asp-1-deaza-dAMP vs. Asp-3-deaza-dAMP at pD 5 and 70°C). Conformational studies by NMR spectroscopy and molecular modeling suggest the involvement of the protonated N3 atom in adenine and 1- and 7-deazaadenine in the intramolecular catalysis of the hydrolysis reaction through the rare syn conformation. Touching (nucleo)base: A dual intramolecular catalytic influence is demonstrated by the nucleobase and carboxyl groups in the chemical hydrolysis of amino acid nucleoside phosphoramidate prodrugs (see scheme). The replacement of the adenine N1 or N7 atoms instead of the N3 atom is shown to have a conformational role in which the protonated N3 is crucial in regulating the kinetics and mechanism of nucleotide (P-N pathway) versus nucleoside (P-O pathway) formation. Copyright
- Maiti, Munmun,Michielssens, Servaas,Dyubankova, Natalia,Maiti, Mohitosh,Lescrinier, Eveline,Ceulemans, Arnout,Herdewijn, Piet
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supporting information; experimental part
p. 857 - 868
(2012/03/26)
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- A new and green synthesis of formamidines by γ-Fe2O 3@SiO2-HBF4 nanoparticles as a robust and magnetically recoverable catalyst
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A series of Bronsted acids (HA) were immobilized on superparamagnetic γ-Fe2O3@SiO2. The synthesized [γ-Fe2O3@SiO2-HA] nanocrystallites were fully characterized by spectroscopic techniques (FT-IR, XRD, SEM, EDX) and used as solid acid catalysts in the synthesis of biologically important formamidines. The results were excellent in yield and time of reaction. Activity of various Bronsted acids on superparamagnetic support as catalyst were also evaluated and among them immobilized HBF4 showed the best catalytic properties.
- Sheykhan, Mehdi,Mohammadquli, Mohsen,Heydari, Akbar
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p. 156 - 161
(2013/01/14)
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- Synthesis and modulation properties of imidazo[4,5-b]pyridin-7-one and indazole-4,7-dione derivatives towards the Cryptosporidium parvum CpABC3 transporter
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The syntheses of new N-polysubstituted imidazo[4,5-b]pyridine-7-one (IP, 5 and 8a-8f) and indazole-4,7-dione (ID, 9 and 10) derivatives are described. The binding affinity of IP and ID towards the recombinant Nucleotide Binding Domain NBD1 of Cryptosporidium parvum CpABC3 was evaluated by intrinsic fluorescence quenching. IP induced a moderate quenching of the intrinsic fluorescence of H6-NBD1 whereas IDs 9 and 10 showed a binding affinity comparable to the ATP analogue TNP-ATP. In addition, 8d, 8e and 10 were shown to be competitive inhibitors of the ATPase activity, but with low affinity. These compounds could thus act like some flavonoid derivatives, which can partly overlap both the nucleotide-binding site and the adjacent hydrophobic steroid-binding region of mammalian P-glycoproteins.
- Zeinyeh, Wa?l,Xia, Hexue,Lawton, Philippe,Radix, Sylvie,Marminon, Christelle,Nebois, Pascal,Walchshofer, Nadia
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scheme or table
p. 2480 - 2488
(2010/07/09)
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- Regioselective N-alkylation of imidazo[4,5-b]pyridine-4-oxide derivatives: an experimental and DFT study
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Regioselectivities were determined for N-alkylations of imidazo[4,5-b]pyridine-4-oxide and 2-methyl-imidazo[4,5-b]pyridine-4-oxide with benzyl bromide or benzyl iodide at RT using K2CO3 in DMF as a base. Experimental attempts have shown that N-1/N-3 ratios slightly varied according to the substitution on C-2 position. This was confirmed by DFT calculations in solvent phase. This computational study has shown first that this N-benzylation reaction passed through a SN2 mechanism. Moreover, regioselectivity of N-benzylation has appeared essentially governed by 'steric approach control'. It explained that opposite N-1/N-3 ratios were obtained with imidazo[4,5-b]pyridine-4-oxide and its 2-methyl-substituted analog. Finally, regioselectivities slightly varied with the nature of benzyl halide.
- Zeinyeh, Wael,Pilmé, Julien,Radix, Sylvie,Walchshofer, Nadia
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scheme or table
p. 1828 - 1833
(2009/07/17)
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- New (1-deaza)purine derivatives via efficient C-2 nitration of the (1-deaza)purine ring
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Nitration of substituted (1-deaza)purines using a mixture of tetrabutylammonium nitrate (TBAN) and trifluoracetic acid anhydride (TFAA) was applied to prepare nitrosubstituted (1-deaza)purines at low temperature. The nitro group influences the system twofold: 1) it activates other substituents towards nucleophilic aromatic substitution and 2) it can be substituted itself leading to a variety of di-substituted (1-deaza)purines, also via solid phase syntheses. Several of the molecules obtained were studied for their antiprotozoal activity and for interactions with the different human adenosine receptors.
- Wanner,Rodenko,Koch,Koomen
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p. 1313 - 1320
(2007/10/03)
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- Structure-based design, synthesis, and antimicrobial activity of purine derived SAH/MTA nucleosidase inhibitors
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The structure-based design, synthesis, and biological activity of novel inhibitors of S-adenosyl homocysteine/methylthioadenosine (SAH/MTA) nucleosidase are described. Using 6-substituted purine and deaza purines as the core scaffolds, a systematic and structure guided series of modifications provided low nM inhibitors with broad-spectrum antimicrobial activity.
- Tedder, Martina E.,Nie, Zhe,Margosiak, Stephen,Chu, Shaosong,Feher, Victoria A.,Almassy, Robert,Appelt, Krzysztof,Yager, Kraig M.
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p. 3165 - 3168
(2007/10/03)
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- Zeolite-induced heterocyclization: A superior method of synthesis of condensed imidazoles
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A superior method of synthesis of condensed imidazoles by the catalytic action of H-Y zeolite on the reaction of 1,2-diaminoaromatics with orthoesters is described.
- Heravi,Montazeri,Rahmizadeh,Bakavoli,Ghassemzadeh
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p. 584 - 585
(2007/10/03)
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- Antagonists of gonadotropin releasing hormone
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There are disclosed compounds of formula (I) and pharmaceutically acceptable salts thereof which are useful as antagonists of GnRH and as such may be useful for the treatment of a variety of sex-hormone related and other conditions in both men and women.
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- Synthesis of 6-substituted 1-deazapurine 2'-deoxyribonucleosides
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The synthesis of 6-substituted 1-deazapurine 2'-deoxyribonucleosides is described. Glycosylation of the 1-deazapurine (imidazo[4,5-b]pyridine) anions with the α-D-halogenose 5 gives stereoselectively N7- and N9-regioisomers. 1H-NMR NOE and 13C-NMR spectroscopy are used for unambiguous assignment of isomers, and 15N-NMR chemical shifts are correlated with σ(para) Hammett constants and point charges.
- Wenzel,Seela
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p. 169 - 178
(2007/10/03)
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- Facile desulfurization of cyclic thioureas by hydrogen peroxide in acetic acid.
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A simple, mild and synthetically useful method for the desulfurization of cyclic thioureas and related compounds, existing as thiol-thione tautomeric mixtures, by hydrogen peroxide in acetic acid is proposed. The effect of substituting different solvents for the acetic acid was investigated.
- Grivas,Ronne
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p. 225 - 229
(2007/10/02)
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- Process for the preparation of imidazolutidine
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This invention relates to a method for the preparation of a compound of formula I: STR1 a key intermediate in the synthesis of a series of Angiotensin II receptor antagonists. The invention also relates to a selective reagent for conducting the Hofmann rearrangement, particularly in the formation of a pyridinoimidazolone, which is a percursor to the formation of an imidazopyfidine of formula I. This invention also relates to a method for the preparation of imidazolutidine, a key intermediate in the synthesis of 3-(2''-(N-benzoyl)sulfonamidobiphen-4-yl)-methyl-5,7 -dimethyl-2-ethyl-3H-imidazo[4,5-b]pyridine, using pyridinoimidazolone, an unreactive urea.
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- SIX MEMBERED RING FUSED IMIDAZOLES SUBSTITUTED WITH PHENOXYPHENYLACETIC ACID DERIVATIVES USED TO TREAT ASTHMA
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Phenoxyphenylacetic acids and derivatives of general structural formula I STR1 have endothelin antagonist activity and are therefore useful in treating cardiovascular disorders, such as hypertension, congestive heart failure, postischemic renal failure, vasospasm, cerebral and cardiac ischemia, myocardial infarction, inflammatory diseases, Raynaud's disease, and endotoxic shock, and asthma.
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- Ethoxymethylenemalonates and Malononitriles (EMM reagents) as formic acid equivalents: Synthesis of fused-imidazoles under neutral or mildly acidic con
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The use of ethoxymethylenemalonates and malononitriles (EMM reagents) for the efficient synthesis of fused imidazoles and related compounds is describe.
- Segelstein, Barb E.,Chenard, Bert L.,Macor, John E.,Post, Ronald J.
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p. 1897 - 1900
(2007/10/02)
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- Deaza analogues of adenosine as inhibitors of blood platelet aggregation
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A number of deaza analogues of adenosine were prepared and tested as inhibitors of platelet aggregation induced by ADP and collagen to investigate the structure-activity relationships in this class of nucleoside analogues. The results showed that the presence of a 6-amino group and nitrogen atoms at positions 3 and 7 of the purine moiety are required for inhibitory activity.
- Antonini,Cristalli,Franchetti,Grifantini,Martelli,Petrelli
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p. 366 - 369
(2007/10/02)
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- N,N-DIMETHYLCHLOROFORMIMINIUM CHLORIDE IN THE SYNTHESIS OF HETEROCYCLIC COMPOUNDS. THE SYNTHESIS OF N-HETEROARYLFORMAMIDINE HYDROCHLORIDES, OXAZOLO/5,4-D/PYRIMIDINES, FUSED IMIDAZOLES AND OTHER SYSTEMS
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N,N-Dimethylchloroformiminium chloride (DCFC) was used for preparation of N-heteroarylformamidine hydrochlorides (2), fused oxazoles (4), imidazoles (6,8) and thiazoles (10).DCFC is advantageous in those cases in which the undesired further methylation of NH, OH, and SH groups could occur by using N,N-dimethylformamide dimethyl acetal (DMFDMA).
- Stanovnik, Branko,Bajt, OLiver,Balcic, Branko,Koren, Bozidar,Prhavc, Marija,et al.
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p. 1545 - 1554
(2007/10/02)
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