- Water Can Accelerate Homogeneous Gold Catalysis
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A selection of gold-catalyzed reactions was examined in a kinetic study on the influence of water on the rate constant. Two intramolecular reactions and one intermolecular reaction, which proceed via proton transfer and/or protodeauration steps, were inve
- Hashmi, A. Stephen K.,Rudolph, Matthias,Stein, Philipp M.
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supporting information
p. 4264 - 4271
(2021/08/03)
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- From Pyridine- N-oxides to 2-Functionalized Pyridines through Pyridyl Phosphonium Salts: An Umpolung Strategy
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The reactions of pyridine-N-oxides with Ph3P under the developed conditions provide an unprecedented route to (pyridine-2-yl)phosphonium salts. Upon activation with DABCO, these salts readily serve as functionalized 2-pyridyl nucleophile equivalents. This umpolung strategy allows for the selective C2 functionalization of the pyridine ring with electrophiles, avoiding the generation and use of unstable organometallic reagents. The protocol operates at ambient temperature and tolerates sensitive functional groups, enabling the synthesis of otherwise challenging compounds.
- Bugaenko, Dmitry I.,Yurovskaya, Marina A.,Karchava, Alexander V.
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supporting information
p. 6099 - 6104
(2021/08/03)
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- Reaction of Pyridine-N-Oxides with Tertiary sp2-N-Nucleophiles: An Efficient Synthesis of Precursors for N-(Pyrid-2-yl)-Substituted N-Heterocyclic Carbenes
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N-(Pyrid-2-yl)-substituted azolium and pyridinium salts, precursors for hybrid NHC-containing ligands, were obtained with excellent regioselectivity, employing a deoxygenative CH-functionalization of pyridine-N-oxides with substituted imidazoles, thiazoles, and pyridine. Unlike the traditional SNAr-based methods, this approach provides high yields for substrates bearing substituents of different electronic nature. The utility of azolium and pyridinium salts thus prepared was also highlighted by the synthesis of pyridyl-substituted imidazolyl-2-thione, benzodiazepine as well as 2-aminopyridines.
- Bugaenko, Dmitry I.,Karchava, Alexander V.,Yurovskaya, Marina A.
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supporting information
p. 5777 - 5782
(2020/12/01)
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- Strategic Approach on N-Oxides in Gold Catalysis – A Case Study
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An extensive kinetic study of selected key reactions of (oxidative) gold catalysis concentrates on the decrease of the catalytic activity due to inhibition of the gold(I) catalyst caused by pyridine derivatives that are obtained as by-products if N-oxides are applied as oxygen donors. The choice of the examined pyridine derivatives and their corresponding N-oxides has been made regardless of their commercial availability; particular attention has been paid to the practical benefit which up to now has been neglected in most of the reaction screenings. The test reactions were monitored by GC and 1H NMR spectroscopy. The received reaction constants provide information concerning a correlation between the electronic structure of the heterocycle and the catalytic activity. Based on the collected kinetic data, it was possible to develop a basic set of three N-oxides which have to be taken into account in further oxidative gold(I)-catalyzed reactions. (Figure presented.).
- Schie?l, Jasmin,Stein, Philipp M.,Stirn, Judith,Emler, Kirsten,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 725 - 738
(2018/10/20)
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- A 3, 5 - dibromo pyridine - N - oxide preparation method
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The invention discloses a preparation method of 3,5-dibromopyridine-N-oxide. The preparation method comprises the following steps: A), an organic solvent is added to 3,5-dibromopyridine to prepare a 3,5-dibromopyridine solution which is taken as a reaction liquid I, and a hydrogen peroxide solution with certain concentration is prepared to serve as a reaction liquid II; and B), the reaction liquid I and the reaction liquid II react sufficiently in a microreactor, off-white crystals, namely, 3,5-dibromopyridine-N-oxide, are obtained after separation and purification, wherein in the step B, the temperature of the microreactor is controlled in a range from 40 DEG C to 80 DEG C, and the pressure is 0-2 MPa. The preparation method of 3,5-dibromopyridine-N-oxide has the advantages as follows: the reaction yield is high, and the raw material utilization rate is increased; the method is simple and easy to operate, the production process is safe, and the reaction speed and the temperature are easy to control; the productivity is high, a flow reactor does not have an amplification effect, and the repeatability is good; few impurities are generated, and purification is easy; and little three wastes are generated, and the preparation method is a typical green technology.
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Paragraph 0038; 0039; 0040; 0041; 0042; 0043; 0044-0061
(2017/08/24)
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- Metal organic frame based on pyridine oxide ligand, and preparation method and application thereof
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The invention discloses a metal organic frame based on a pyridine oxide ligand, and a preparation method and application thereof. The structural formula of the metal organic frame Zn-MOF is (ZnLBr2)n, wherein L refers to the pyridine oxide ligand L with the structural formula shown as below, and n refers to a non-zero natural number. A preparation method of the pyridine oxide ligand L includes (1), preparing 3, 5-dihalogenated pyridine into 3, 5-dihalogenated pyridine-N-oxide; (2), subjecting the 3, 5-dihalogenated pyridine-N-oxide to Suzuki reaction to obtain the pyridine oxide ligand L. According to the preparation method of the metal organic frame based on the pyridine oxide ligand, ZnBr2 liquor is laid on pyridine oxide ligand L liquor, and standing is performed to obtain a colorless monocrystal, namely the metal organic frame Zn-MOF. When the metal organic frame serves as a catalyst, reaction temperature is mild, reaction time is short, activity is high, catalyst consumption is low, the catalyst is easy to recycle, catalyst utilization rate is increased, and cost is reduced.
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Paragraph 0055; 0056; 0057; 0058
(2017/08/28)
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- C2-Alkenylation of N-heteroaromatic compounds: Via Br?nsted acid catalysis
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Substituted heteroaromatic compounds, especially those based on pyridine, hold a privileged position within drug discovery and medicinal chemistry. However, functionalisation of the C2 position of 6-membered heteroarenes is challenging because of (a) the difficulties of installing a halogen at this site and (b) the instability of C2 heteroaryl-metal reagents. Here we show that C2-alkenylated heteroaromatics can be accessed by simple Br?nsted acid catalysed union of diverse heteroarene N-oxides with alkenes. The approach is notable because (a) it is operationally simple, (b) the Br?nsted acid catalyst is cheap, non-toxic and sustainable, (c) the N-oxide activator disappears during the reaction, and (d) water is the sole stoichiometric byproduct of the process. The new protocol offers orthogonal functional group tolerance to metal-catalysed methods and can be integrated easily into synthetic sequences to provide polyfunctionalised targets. In broader terms, this study demonstrates how classical organic reactivity can still be used to provide solutions to contemporary synthetic challenges that might otherwise be approached using transition metal catalysis.
- Crisenza, Giacomo E. M.,Dauncey, Elizabeth M.,Bower, John F.
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supporting information
p. 5820 - 5825
(2016/07/06)
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- Synthesis, Structure, and Ligand-Centered Catalytic Properties of MII Coordination Polymers (M=ZnII, CdII, HgII) with Open Pyridyl N-Oxide Sites
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Four MII (M=ZnII, CdII, HgII) coordination polymers were designed and synthesized based on two pyridine N-oxide bridging ligands: 3,5-bis(4-pyridyl)pyridine N-oxide and 2,6-bis(3-pyridyl)pyridine N-oxide. The re
- Cheng, Jun-Yan,Ding, Feng-Wen,Wang, Peng,Zhao, Chao-Wei,Dong, Yu-Bin
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p. 743 - 751
(2016/08/11)
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- Base free regioselective synthesis of α-triazolylazine derivatives
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A regioselective α-heteroarylation followed by deoxygenation towards the synthesis of variety of azine triazole from simple azine N-oxides derivatives and N-tosyl-1,2,3-triazoles has been described. The reaction is metal free and base free with shorter reaction time, high yields and a broad substrate scope.
- Harisha, Mysore Bhyrappa,Nagaraj, Muthupandi,Muthusubramanian, Shanmugam,Bhuvanesh, Nattamai
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p. 58118 - 58124
(2016/07/06)
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- HIV INTEGRASE INHIBITORS
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The present invention features compounds that are HIV integrase inhibitors and therefore are useful in the inhibition of HIV replication, the prevention and/or treatment of infection by HIV, and in the treatment of AIDS and/or ARC.
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- PICOLINAMIDE INHIBITORS OF KINASES
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The present invention relates to compounds of formula (I) or pharmaceutical acceptable salts, wherein R1, R2, R3, A, B, Z, n, and m are defined in the description. The present invention relates also to compositions contain
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Page/Page column 20
(2012/07/31)
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- HIV INTEGRASE INHIBITORS
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The present infention features compounds that are HIV integrase inhibitors and may be useful in the inhibition of HIV replication, the prevention and/or treatment of infection by HIV, and in the treatment of AIDS and/or ARC.
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Page/Page column 56
(2008/06/13)
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- Cyclic compounds
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1. A cyclic compound of the formula (I) or a pharmacologically acceptable salt thereof, wherein X is ═CH— or ═N—, Y is —NH—, —NR4—, —S—, —O—, —CH═N—, —N═CH—, —N═N—, —CH═CH—, etc., R1 is a lower alkoxy group, an amino group, a heterocyclic ring containing N atom(s), or a hydroxy group substituted by a heterocyclic ring containing N atom(s) (each of which is optionally substituted), R2 is a lower alkylamino group which is optionally substituted by an aryl group, a lower alkoxy group which is optionally substituted by an aryl group, a lower alkoxy group substituted by an aromatic heterocyclic ring containing N atom(s), R3 is an aryl group, a heterocyclic ring containing N atom(s), a lower alkyl group, a lower alkoxy group, a cyclo lower alkoxy group, a hydroxy group substituted by a heterocyclic ring containing N atom(s), or an amino group (each of which is optionally substituted), and R3 and a substituent in Y may be combined to form a lactone ring. The compound of the present invention has excellent selective PDE V inhibitory activity and therefore, is useful as a therapeutic or prophylactic drug for treating various diseases due to functional disorders on cGMP-signaling.
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- A simple and efficient method for the preparation of pyridine-N-oxides II
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Oxidation of pyridines with bis(trimethylsilyl)peroxide in the presence of catalytic amounts of inorganic rhenium derivatives gives high yields of their analytically pure N-oxides by simple work-ups, typically a filtration or a Kugelrohr distillation.
- Coperet, Christophe,Adolfsson, Hans,Chiang, Jay P.,Yudin, Andrei K.,Sharpless, K. Barry
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p. 761 - 764
(2007/10/03)
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- An Excellent Method for the Mild and Safe Oxidation of N-Heteroaromatic Compounds and Tertiary Amines
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Selective, mild and safe N-oxidation of N-heteroaromatic compounds and tertiary amines affording high product yields was achieved by using the H2O2-urea/phthalic anhydride system. Key Words: N-Oxidation / Hydrogen peroxide / Urea / Phthalic anhydride
- Kaczmarek, Lukasz,Balicki, Roman,Nantka-Namirski, Pawel
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p. 1965 - 1966
(2007/10/02)
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