- Synthesis of 3H-pyrazoles by reaction of methyl and p-tolyl phenylethynyl sulfones with diphenyldiazomethane and their thermal and acid-catalyzed transformations
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Methyl and p-tolyl phenylethynyl sulfones reacted with diphenyldiazomethane in diethyl ether at 20° C to give 1,3-dipolar cycloaddition products both according and contrary to the von Auwers rule, sulfonyl-substituted 3H-pyrazoles at a ratio of 1 : 1.5 and 1.3 : 1, respectively. On heating in toluene for 2 h, the Auwers adducts underwent van Alphen-Hüttel rearrangement with 1,5-sigmatropic shift of one phenyl substituent to afford sulfonyl-substituted 4H-pyrazoles. Under analogous conditions, the anti-Auwers adducts rearranged into sulfonyl-substituted N-phenyl-1H-pyrazoles containing a small amount of the denitrogenation product, sulfonyl-substituted cyclopropene. The Auwers adducts, as well as 4H-pyrazoles resulting from their thermal rearrangement, were converted in 5-7 days at 20°C into 3,4,4-triphenyl-1H-pyrazol-5(4H)-one by the action of a catalytic amount of sulfuric acid in acetic acid. Under analogous conditions, the regioisomeric anti-Auwers adducts gave rise to 3,4,5-triphenyl-1H-pyrazole with an impurity of 4-(R-sulfonyl)-1,3,5-triphenyl-1H-pyrazoles.
- Vasin,Masterova, Yu.Yu.,Bezrukova,Razin,Somov
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- Similarity and Differences in the Regioselectivities of Thermal and Acid-Catalyzed van Alphen–Hüttel Rearrangements in the Series of 3,3-Diphenyl-3H-pyrazoles Containing Electron-Withdrawing Substituents on C4 and C5
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3,3-Diphenyl-3H-pyrazoles containing an electron-withdrawing substituent in the 5-position undergo van Alphen–Hüttel rearrangement with migration of one phenyl group to C4 on heating in an aprotic solvent (benzene, toluene), as well as on keepi
- Vasin,Razin,Bezrukova
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p. 1045 - 1054
(2018/09/11)
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- Y(OTf)3-Catalyzed Cascade Propargylic Substitution/Aza-Meyer-Schuster Rearrangement: Stereoselective Synthesis of α,β-Unsaturated Hydrazones and Their Conversion into Pyrazoles
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A straightforward and concise method for the highly stereoselective synthesis of α,β-unsaturated hydrazones by the Y(OTf)3-catalyzed cascade propargylic substitution/aza-Meyer-Schuster rearrangement reaction of tertiary propargylic alcohols and
- Liu, Wenfei,Wang, Han,Zhao, Haiying,Li, Baoguo,Chen, Shufeng
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supporting information
p. 2170 - 2174
(2015/09/15)
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- Functionalized pyrazoles as agents in C-C cross-coupling reactions
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The 1-tetrahydropyranyl-(THP-)protected pyrazoles 4-R-pz(THP) (R=pinacolatoboryl=Bpin (3a(THP)), Me3Si (4a(THP)), Me3Sn (5a(THP)), and 4-R-3,5-Ph2pz (R=Bpin (3b(THP)), Me3Si (4b(THP)), Me3Sn (5b(THP))
- Pejic, Marijana,Popp, Sebastian,Bolte, Michael,Wagner, Matthias,Lerner, Hans-Wolfram
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- One-pot synthesis of pyrazoles through a four-step cascade sequence
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A one-pot synthesis of 3,4,5- and 1,3,5-pyrazoles from tertiary propargylic alcohols and para-tolylsulfonohydrazide has been accomplished. The pyrazoles are formed through a four-step cascade sequence, including FeCl 3-catalyzed propargylic substitution, aza-Meyer-Schuster rearrangement, base-mediated 6πelectrocyclization, and thermal [1,5] sigmatropic shift. In this reaction, the 3,4,5- and 1,3,5-pyrazoles are produced selectively according to different substituents in the starting alcohols. A one-pot recipe: The synthesis of 3,4,5- and 1,3,5-pyrazoles from tertiary propargylic alcohols and para-tolylsulfonohydrazide has been accomplished. The pyrazoles are formed through a four-step cascade sequence (see figure), and are produced selectively according to different substituents in the starting alcohols.
- Hao, Lu,Hong, Jun-Jie,Zhu, Jun,Zhan, Zhuang-Ping
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supporting information
p. 5715 - 5720
(2013/06/04)
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- NITROGEN-CONTAINING HETEROCYCLIC COMPOUNDS
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Nitrogen-containing heterocyclic compounds represented by the following Formula (1) are provided. The compounds or salts thereof have a strong EP1 antagonistic activity when they are administered to a human or an animal, and they are useful as an effective component of a pharmaceutical agent for prophylaxis and/or treatment of an overactive bladder, for example. Furthermore, they are useful as an effective component of a pharmaceutical agent for the prophylaxis and/or treatment of symptoms including frequent urination, urinary urgency and urinary incontinence.
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Page/Page column 46
(2010/03/02)
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- Thermal and acid-catalyzed transformations of 3H-pyrazoles obtained from diphenyldiazomethane and methyl phenylpropiolate
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Reaction of diphenyldiazomethane with methyl phenylpropiolate in diethyl ether alongside the expected methyl triphenyl-3H-pyrazole-4-and-5-carboxylates (I and II) (38 and 24%) gave rise also to 8% of methyl 3,5-diphenyl-1-(1- ethoxyethyl)-1H-pyrazole-4-ca
- Fedorov,Duisenbaev,Razin,Kuznetsov,Linden
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p. 231 - 240
(2007/10/03)
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- Photochemistry of N-heterocycles, 5: A comparison of chemical and photochemically induced reduction of some 2(4),5-dihydro-1,2,4-triazines and aromatic 1,2,4-triazines
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Chemical reduction (Zn/AcOH) of the arene 1 and of 2(4),5-dihydro-1,2,4- triazine 7 has been reinvestigated, resulting in the amendment of literature data concerning this reaction. Chemical, electrochemical, and photochemically induced reductions and ring contractions of 1,2,4-triazine derivatives have been compared. The first example of a triaryl-1,4-dihydrotriazine has been prepared. Some further evidence is presented that supports the proposed mechanism of the photochemically induced reduction and ring contraction of 1,2,4-triazines.
- Nagy, Jozsef,Horvath, Aniko,Szoelloesy, Aron,Nyitrai, Jozsef
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p. 685 - 689
(2007/10/03)
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- Photochemistry of N-Heterocycles. Part 3. Synthesis and Photochemistry of some New Dihydro-1,2,4-triazines and their Quaternary Salts
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Several new dihydro-1,2,4-triazines, 1b, 4, 5, 16 and 19, have been synthesized and their structures unambiguously determined.The existence of 1,2- and 1,4-dihydrotriazines, 20 and 22, described in the literature was ruled out.Irradiation of the aromatic triazines 6 and 15 and the novel quaternary dihydro-1,2,4-triazinium salts 4, 5, 19 furnished new evidence for both the reduction pathways and the mechanism of ring-contraction reactions.
- Nagy, Jozsef,Rapp, Rudolf,Alexovics, Maria,Doepp, Dietrich,Nyitrai, Jozsef,et al.
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p. 661 - 666
(2007/10/02)
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- PHOTOCHEMISTRY OF N-HETEROCYCLES, II PHOTOCHEMICALLY INDUCED REDUCTION AND OXIDATION OF SOME 2(4),5-DIHYDRO-1,2,4-TRIAZINES, HIGH PRESSURE LIQUID CHROMATOGRAPHY STUDIES
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The salts 1a-1c, 2a, and 3a of the 3,5,6-triphenyl-2(4),5-dihydro-1,2,4-triazines 1-3 were irradiated with a high pressure mercury immersion lamp (λ300 nm) in various alcohols and the reactions were followed by HPLC.The singlet excited states of the cations of the salts 1a-1c, 2a and 3a are thought to act as single electron acceptors.The resulting radicals A are converted by proton transfer into the radical cations B, which may become stabilized either by recombination with a hydroxyalkyl radical and proton loss to give the adduct 10, or by successive reduction and ring contractions to yield the corresponding pyrazoles 4 and 5, or the imidazoles 6 and 7.The latter are smoothly photodehydrogenated to the corresponding phenanthro-imidazoles 8 and 9.The photoexcited cation of salt 1a is able to dehydrogenate the base 1 to the aromatic triazine 11.When irradiated in alcohol possessing α-hydrogen atoms, compound 11 is reduced and furnishes the ring contraction products 4 and 8.The relative amounts of the pyrazole 4 and of the phenanthroimidazole 8 depend on whether compound 1 or 11 is used as the starting material.This observation suggests two independent pathways for the formation of compound 8.A mechanistic interpretation of the total photochemical process is presented.
- Nagy, Jozsef,Nyitrai, Jozsef,Lempert, Karoly,Fekete, Jeno,Kocsi, Emilia
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p. 733 - 742
(2007/10/02)
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- PHOTOCHEMISTRY OF N-HETEROCYCLES. PART 1. SYNTHESIS AND PHOTOCHEMISTRY OF SOME 2(4),5-DIHYDRO-1,2,4-TRIAZINES. X-RAY MOLECULAR STRUCTURE OF 1-(4-METHYL-3,5,6-TRIPHENYL-1,4,5,6-TETRAHYDRO-1,2,4-TRIAZIN-6-YL)ETHANOL
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Ethanolic solution of the hydrochlorides of the mostly new 2(4),5-dihydro-1,2,4-triazines (1)-(4) were irradiated with a high-pressure mercury immersion lamp (λ>=300 nm).The salts (1a)-(3a) underwent reductions, ring contractions, and dehydrogenations upo
- Nagy, Jozsef,Nyitrai, Jozsef,Kolonits, Pal,Lempert, Karoly,Gergely, Anna,et al.
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p. 3267 - 3274
(2007/10/02)
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- Nonacarbonyldiiron-Induced Reaction of 3-Azido-1,2,3-triphenyl-cyclopropene and 4,5,6-Triphenyl-1,2,3-triazine
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The -induced reaction of 3-azido-1,2,3-triphenylcyclopropene (1) undergoes elimination of a nitrogen molecule and C-C bond cleavage to result in the formation of benzonitrile, diphenylacetylene, 2,3-diphenyl-inden-1-one, and 1,2,3-triphenylprope
- Kobayashi, Tomoshige,Murata, Naoki,Nitta, Makoto
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p. 3062 - 3064
(2007/10/02)
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- Oxidative Rearrangement of N-Aminopyrazoles to 1,2,3-Triazines
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When 1-amino-3,5-dimethylpyrazole or 1-amino-3-methoxyindazole is oxidised with lead(IV) acetate, the N-amino group forms the central nitrogen (N-2) of the triazine which is formed.
- Boulton, A. J.,Fruttero, Roberta,Saka, J. D. Kalenga,Williams, Michael T.
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p. 1249 - 1254
(2007/10/02)
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