- [3+2]-cycloaddition of in situ generated nitrile imines and acetylene for assembling of 1,3-disubstituted pyrazoles with quantitative deuterium labeling
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A novel synthetic methodology for the preparation of 1,3-disubstituted pyrazoles from in situ generated nitrile imines and acetylene is reported. The reactions are performed in a simple two-chamber reactor. One part of the reactor is loaded with hydrazonoyl chloride precursors of active nitrile imine species and a base. The other part is used to generate acetylene from CaC2 and water. Partitioning of the reactants improves the yields of desired pyrazoles up to 99% and simplifies their isolation to a simple procedure of solvent evaporation. The approach requires no complex equipment and utilizes inexpensive, safe, and easy to handle calcium carbide as a starting material. A model deuterium incorporation is carried out according to the developed methodology, producing a series of novel 4,5-dideuteropyrazoles with excellent deuterium enrichment. Theoretical calculations on reaction mechanism and characterization of possible intermediate structures were performed.
- Voronin, Vladimir V.,Ledovskaya, Maria S.,Gordeev, Evgeniy G.,Rodygin, Konstantin S.,Ananikov, Valentine P.
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p. 3819 - 3828
(2018/04/14)
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- A [4 + 3] Annulation Reaction of aza- o-Quinone Methides with Arylcarbohydrazonoyl Chlorides for Synthesis of 2,3-Dihydro-1 H-benzo[ e][1,2,4]triazepines
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An unprecedented [4 + 3] annulation reaction of aza-ortho-quinone methides with arylcarbohydrazonoyl chlorides has been achieved under mild conditions. The annulation underwent a sequential conjugate addition/intramolecular annulation/rearrangement, providing a useful method for the synthesis of biologically interesting 2,3-dihydro-1H-benzo[e][1,2,4]triazepine.
- Guo, Zhenyan,Jia, Hao,Liu, Honglei,Wang, Qijun,Huang, Jiaxing,Guo, Hongchao
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supporting information
p. 2939 - 2943
(2018/05/28)
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- Exploiting the Electrophilic and Nucleophilic Dual Role of Nitrile Imines: One-Pot, Three-Component Synthesis of Furo[2,3-d]pyridazin-4(5H)-ones
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An expeditious multicomponent reaction to synthesize tetrasubstituted furo[2,3-d]pyridazin-4(5H)-ones is reported. In brief, hydrazonoyl chlorides react with isocyanoacetamides, in the presence of TEA, to give 1,3-oxazol-2-hydrazones which, without being isolated, can react with dimethylacetylene dicarboxylate to afford furo[2,3-d]pyridazin-4(5H)-ones with an unprecedented level of complexity in a triple domino Diels-Alder/retro-Diels-Alder/lactamization reaction sequence.
- Giustiniano, Mariateresa,Mercalli, Valentina,Amato, Jussara,Novellino, Ettore,Tron, Gian Cesare
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supporting information
p. 3964 - 3967
(2015/09/01)
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- Copper(ii)-catalyzed coupling reaction: An efficient and regioselective approach to N′,N′-diaryl acylhydrazines
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Using N′-aryl acylhydrazines as aryl donors, a novel copper(ii)-catalyzed homo-coupling reaction of N′-aryl acylhydrazines has been developed for the synthesis of N′,N′-diaryl acylhydrazines. We also provided a complementary procedure for the preparation of unsymmetrical diaryl acylhydrazines via cross-coupling reaction. These protocols featured mild reaction conditions, wide functional group tolerance and highly regioselective products. Control experiments indicated that this kind of coupling reaction might undergo a transient acyl diazene intermediate. This journal is
- Zhang, Ji-Quan,Huang, Gong-Bin,Weng, Jiang,Lu, Gui,Chan, Albert S. C.
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supporting information
p. 2055 - 2063
(2015/03/05)
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- KOt-Bu promoted homocoupling and decomposition of N'-aryl acylhydrazines: synthesis of unsymmetric N',N'-diaryl acylhydrazines
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The KOt-Bu promoted homocoupling and decomposition of N'-aryl acylhydrazines has been achieved. The method allows for a novel and efficient synthesis of unsymmetric N',N'-diaryl acylhydrazines under mild reaction conditions. The reaction probably proceeds via the generation of N'-centered acylhydrazine radicals and the subsequent homolytic aromatic substitution.
- Wang, Wei-Juan,Zhang, Ting,Duan, Li-Jun,Zhang, Xue-Jing,Yan, Ming
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p. 9073 - 9080
(2015/11/09)
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- 1,3-Diarylcycloalkanopyrazoles and diphenyl hydrazides as selective inhibitors of cyclooxygenase-2
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Novel 1,3-diarylcycloalkanopyrazoles 1, and diphenyl hydrazides 2 were identified as selective inhibitors of cyclooxygenase-2. The 1,3-diaryl substitution pattern of the pyrazole ring in 1 differentiates these compounds from most of the known selective COX-2 inhibitors that contain two aryl rings at the adjacent positions on a heterocyclic or a phenyl ring. Similarly, the two phenyl rings in 2 are also separated by three atoms. SAR of both phenyl rings in 1 and 2, and the aliphatic ring in 1 will be discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.
- Sui, Zhihua,Guan, Jihua,Ferro, Michael P.,McCoy, Kathy,Wachter, Michael P.,Murray, William V.,Singer, Monica,Steber, Michele,Ritchie, Dave M.,Argentieri, Dennis C.
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p. 601 - 604
(2007/10/03)
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- Addition of Semidione Radicals to Arenediazonium Ions: Synthesis of 1,1-Diacyl-2-arylhydrazines
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The α-dicarbonyl compounds 1 are selectively reduced to semidione radicals 2 by aqueous Ti3+, via inner-sphere electron transfer (ET).When an equimolar amount of an arenediazonium salt (3) is present, 2 adds to the nitrogen-nitrogen triple bond of 3 to afford the intermediate azo radical cation C, which, depending on the nature of the para substituent of the N-phenyl ring, undergoes rearrangement to a 1,1-diacyl-2-arylhydrazine (4) or preferentially reduction to a hydrazone (5).A mechanism that accounts for both the rearrangement and the substituent effects that are observed is proposed.
- Clerici, Angelo,Porta, Ombretta
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p. 6813 - 6818
(2007/10/02)
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- Acylation Reactions of Phenylhydrazines. Preparation and Properties of New Diacylphenylhydrazines
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Anhydride acylation reactions of a variety of substituted arylhydrazines under mild conditions led to controlled formation of the acid phenylhydrazides I (Table I).The procedures were tallored to the particular state of the starting arylhydrazine.Second-s
- Hearn, Michael J.,Magee, Debra J.,Alhart, Randi,Gleva, Marye,Goldstein, Susan,et al.
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p. 129 - 131
(2007/10/02)
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- Method of use, composition, and compounds
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Certain benzoyl chloride phenylhydrazones have been found to be active against insects and mites. The benzoyl ring and the phenylhydrazone ring can be substituted with a halogen atom, a nitro group, or an alkyl group of from 1 to 6 carbon atoms, inclusive
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