18076-30-7Relevant academic research and scientific papers
Synthesis of 3H-pyrazoles by reaction of methyl and p-tolyl phenylethynyl sulfones with diphenyldiazomethane and their thermal and acid-catalyzed transformations
Vasin,Masterova, Yu.Yu.,Bezrukova,Razin,Somov
, p. 890 - 899 (2015)
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.
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
Vasin,Razin,Bezrukova
, p. 1045 - 1054 (2018/09/11)
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
Y(OTf)3-Catalyzed Cascade Propargylic Substitution/Aza-Meyer-Schuster Rearrangement: Stereoselective Synthesis of α,β-Unsaturated Hydrazones and Their Conversion into Pyrazoles
Liu, Wenfei,Wang, Han,Zhao, Haiying,Li, Baoguo,Chen, Shufeng
supporting information, p. 2170 - 2174 (2015/09/15)
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
Functionalized pyrazoles as agents in C-C cross-coupling reactions
Pejic, Marijana,Popp, Sebastian,Bolte, Michael,Wagner, Matthias,Lerner, Hans-Wolfram
, p. 83 - 97 (2014/06/09)
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))
One-pot synthesis of pyrazoles through a four-step cascade sequence
Hao, Lu,Hong, Jun-Jie,Zhu, Jun,Zhan, Zhuang-Ping
supporting information, p. 5715 - 5720 (2013/06/04)
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.
NITROGEN-CONTAINING HETEROCYCLIC COMPOUNDS
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Page/Page column 46, (2010/03/02)
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.
Thermal and acid-catalyzed transformations of 3H-pyrazoles obtained from diphenyldiazomethane and methyl phenylpropiolate
Fedorov,Duisenbaev,Razin,Kuznetsov,Linden
, p. 231 - 240 (2007/10/03)
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
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
Nagy, Jozsef,Horvath, Aniko,Szoelloesy, Aron,Nyitrai, Jozsef
, p. 685 - 689 (2007/10/03)
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.
Photochemistry of N-Heterocycles. Part 3. Synthesis and Photochemistry of some New Dihydro-1,2,4-triazines and their Quaternary Salts
Nagy, Jozsef,Rapp, Rudolf,Alexovics, Maria,Doepp, Dietrich,Nyitrai, Jozsef,et al.
, p. 661 - 666 (2007/10/02)
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.
