- Synthesis of new Copper Catalyst with Pyrazole Based Tridentate Ligand and Study of Its Activity for Azide Alkyne Coupling
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Synthesis of new copper catalyst with pyrazole based tridentate ligand and study of its activity for azide alkyne coupling were investigated by researchers. To a solution of acetyl acetone (2.002 g, 20 mmol), 2- nitrophenylhydrazine in ethanol was added five drops of con. HCl and heated at 50° for 1 hour. After confirming the formation of 3, 5-dimethyl-1-(2-nitrophenyl)- 1H-pyrazole by TLC, ice cooled water was added in to the reaction mixture. The precipitate was filtered, washed with water and then hexane. The product formed as yellow precipitate, that precipitate had been filtered by normal filter paper. The product was recrystallized in ethanol. For synthesis, was suspended in 6 mL of deionized and stirred for 4 h until a clear solution was obtained in 50 ml round bottom flask Cu(OAc) 2. The reaction mixture was diluted with water, filtered, washed sequentially with water, methanol and n-hexane. Then dark greenish blue color crystal were formed and used for the reactions. The solid was crystallized in CH2Cl2 to get crystal whose structure was confirmed by single crystal XRD.
- Rajeswari, Panneer Selvam,Nagarajan, Rajendran,P, Sujith K,Emmanuvel, Lourdusamy
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- Pyrazole-tethered heteroditopic ligands and their transition metal complexes: Synthesis, structure, and reactivity
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Various pyrazole-based P,N (2a-c) and N,N (3a-b) ligands have been synthesized. Using representative ligands, NiII, CoII, CuII, and CuI complexes have been prepared and structurally characterized by crystallogra
- Mukherjee, Anuradha,Subramanyam,Puranik, Vedavati G.,Mohandas, Thekke P.,Sarkar, Amitabha
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p. 1254 - 1263
(2007/10/03)
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- Photodecomposition of some para-substituted 2-pyrazolylphenyl azides. Substituents affect the phenylnitrene S-T gap more than the barrier to ring expansion
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A series of para-substituted (H, Me, Cl, F, CF3, OMe, NMe2) phenyl azides bearing a dimethylpyrazolyl group in position 2 allowing intramolecular trapping of singlet nitrene have been photolyzed at both 295 and 90 K in ethanol. For t
- Albini, Angelo,Bettinetti, Gianfranco,Minoli, Giovanna
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p. 3104 - 3113
(2007/10/03)
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- Reactivity of singlet and triplet arylnitrenes: Temperature-dependent photodecomposition of 1-(2-azidophenyl)-3,5-dimethylpyrazole
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At >200 K photolysis of 1-(2-azidophenyl)-3,5-dimethylpyrazole (5) gives 1,3-dimethylpyrazolobenzotriazole (6, by electrophilic cyclization of singlet nitrene 4) or, in the presence of diethylamine, aminoazepine 8 (by addition of the nucleophile and rearr
- Albini, Angelo,Bettinetti, Gianfranco,Minoli, Giovanna
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p. 7308 - 7315
(2007/10/03)
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- SYNTHESIS OF DIMETHYLPYRAZOLOBENZOTRIAZOLES AND OF METHYLPYRAZOLOQUINOXALINES BY CYCLIZATION OF 3,5-DIMETHYL-1-(2-NITRENOPHENYL)PYRAZOLES
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The thermal and photochemical decomposition of a series of 5-substituted 1-(2-azidophenyl)-3,5-dimethylpyrazoles has been examined under a homogeneous set of conditions.Cyclization to pyrazolobenzotriazole (via singlet nitrene) is an efficient process except when the phenyl substituent induces intersystem crossing to the azide triplet or compensates for its electrophilicity.On the contrary, cyclization to pyrazoloquinoxaline (via triplet nitrene) is not a preparatively useful process, due to competition with dimerization to the azo derivatives and reduction to aminophenylpyrazoles.
- Albini, Angelo,Bettinetti, Gianfranco,Minoli, Giovanna
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p. 597 - 606
(2007/10/02)
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- Chemistry of Nitrenes Generated by the Photocleavage of Both Azides and a Five-Membered Heterocycle
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Pyrazolobenzotriazole and some of its derivatives (2a-c) are photochemically cleaved to form 2-(1-pyrazolyl)phenylnitrenes, which are also obtained through a more conventional path by photodecomposition of the pyrazolylphenyl azides (1a-c).Product
- Albini, A.,Bettinetti, G.,Minoli, G.
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p. 6928 - 6934
(2007/10/02)
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- Synthesis of 7-Substituted Indoles as Potential Ligand Precursors
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Some 7-(pyridin-2'-yl)- and 7-(pyrazol-1'-yl)-indole-2-carboxylic esters (14)-(16) and the related acids (17) and (18) have been synthesized through the Fischer indole cyclizations of the ethyl pyruvate hydrazones (9)-(12), which were in turn derived from
- Black, David St.C.,Deacon, Glen B.,Edwards, Gavin L.
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p. 1771 - 1781
(2007/10/02)
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- Heteropentalenes. The Thermal Addition of 1,3-Dimethylpyrazolobenzotriazole to Dimethyl Acetylenedicarboxylate
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The title compound (3) reacts with dimethyl acetylenedicarboxylate with addition onto the azomethinimine moiety to give dimethyl 2a,4-dimethyl-4a,8b,8c-triazapentalenoindene-1,2-dicarboxylate (7) via a zwitterionic intermediate which can be trapped by protic solvents, e.g. methanol or water to give dimethyl 2--3-methoxymaleate (8) or tetramethyl 3,3'-bis-2,2'-oxydimaleate (9), respectively.The cycloadduct (7) undergoes spontaneous retrocycloaddition to dimethyl 3-methylpyrazolobenzo triazole-1,2-dicarboxylate (12) and radical cleavage to yield, unexpectedly, methyl 4,5-dihydro-2-methyl-4-oxopyrazoloquinoxaline-3-carboxylate (17) as the main product together with small amounts of two benzotriazolylpentenones (14) and (15).
- Albini, Angelo,Bettinetti, Gianfranco,Minoli, Giovanna
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p. 2491 - 2494
(2007/10/02)
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- Heteropentalenes. The Oxidation of Pyrazolobenzotriazoles
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The dye-sensitized photo-oxidation of 1,3-dimethylpyrazolobenzotriazole (3) affords 4-benzotriazol-1-yl-3,4-epoxypentan-2-one (5) and 4-benzotriazol-1-ylpent-3-en-2-one (6), as well as the corresponding benzotriazol-2-yl derivatives (7) and (8), in
- Albini, Angelo,Bettinetti, Gianfranco,Minoli, Giovanna
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p. 581 - 585
(2007/10/02)
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- DIMETHYLBENZOPYRAZOLOTRIAZOLE vs METHYLPYRAZOLOQUINOXALINE FROM 3,5-DIMETHYL-1-(2-NITRENOPHENYL)PYRAZOLE
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The chemistry of singlet and triplet 3,5-dimethyl-1-(2-nitrenophenyl)pyrazole is examined.Intramolecular electron transfer is found to play a key role in determining the easy reaction to the ylide (VII) from the singlet state and the "lazyness" of the triplet state.
- Albini, Angelo,Bettinetti, Gian Franco,Minoli, Giovanna
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p. 331 - 334
(2007/10/02)
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- Competitive Cyclisations of Singlet and Triplet Nitrenes. Part 8. The 1-(2-Nitrenophenyl)pyrazoles and Related Systems
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The title nitrenes, derived by nitro-group deoxygenation with triethyl phosphite or by thermolysis or photolysis of the corresponding azide, have been studied.The effect of substituents (Cl, Br, OMe, NMe2, Me, CF3, and NO2) both meta and para to the nitrene has been examined as a determinant of the preferred mode of cyclisation to either a pyrazolobenzotriazole or a pyrazoloquinoxaline.Similarly, the role of solvents, sensitisers, and quenchers has been studied.Routes to the isomeric 1- and 2-(2-nitrophenyl)-4,5,6,7-tetrahydroindazoles have been defined and the literature corrected by studing the nitrene-mediated cyclisation of these products.The chemistry of the analogous 1-(2-carbenophenyl)- and the 1-(2-nitrenosulphonylphenyl)-3,5-dimethylpyrazoles has also been examined, the former giving 2-(3,5-dimethylpyrazol-1-yl)-benzaldazine and -benzyl alcohol while the latter gave products of intramolecular nitrene attack (a pyrazolobenzothiatriazine) and intermolecular reaction.Rationalisations for all the reaction pathways have been advanced.
- Lindley, John M.,McRobbie, Ian M.,Meth-Cohn, Otto,Suschitzky, Hans
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p. 982 - 994
(2007/10/02)
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