- N-Heterocyclic carbene based catalytic platform for Hauser-Kraus annulations
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The venerable Hauser-Kraus annulation is an effective and convergent method for generating oxygenated polycyclic aromatic compounds. Despite its application in complex molecule synthesis, the harsh and strongly basic conditions can limit its utility in more functionalized molecular settings. We have developed the first catalytic Hauser-Kraus annulation based on N-heterocyclic carbene catalysis that proceeds under milder conditions. We demonstrate the scope of the transformation in the presence of several functional groups. We also propose a concerted mechanism for the annulation that proceeds through a non-canonical Breslow intermediate. This journal is
- Sharique, Mohammed,Tambar, Uttam K.
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p. 7239 - 7243
(2020/07/23)
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- Synthesis method of 1,4-dyhydroxyl-2,3-naphthyldinitrile and derivative thereof
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The invention discloses a synthesis method of 1,4-dyhydroxyl-2,3-naphthyldinitrile and a derivative thereof. The method takes ninhydrin and a derivative thereof as raw materials, and the ninhydrin and the derivative thereof react with malononitrile in water to generate 2-(dicyanomethylene)indene-1,3-diketone and a derivative thereof; the 2-(dicyanomethylene)indene-1,3-diketone and the derivative thereof further react with anhydrous potassium iodide and are isomerized to generate potassium salt of the 1,4-dyhydroxyl-2,3-naphthyldinitrile; and after the potassium salt of the 1,4-dyhydroxyl-2,3-naphthyldinitrile is acidified and then is separated, the high-purity product (the 1,4-dyhydroxyl-2,3-naphthyldinitrile) is obtained. The method disclosed by the invention has the advantages of wide raw material resource and low price; the cost is low and the method is green and environmentally friendly; and the method is convenient for industrialized large-scale production.
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Paragraph 0039; 0040
(2017/07/04)
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- Studies on charge-transfer complexes of 2,3-dicyano-1,4-naphthoquinone with some ring and N-substituted anilines
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The charge-transfer complexes (CT-complexes) between 2,3-dicyano-1,4- naphthoquinone (DCNQ) and some aromatic anilines, both ring and N-substituted, were studied spectrophotometrically in three chlorinated solvents, viz. chloroform, dichloromethane, and 1,2-dichloroethane at different temperatures. All the donors are known to form stable 1:1 stoichiometric complexes with DCNQ and their stoichiometry was unaffected by the variation of temperature over the studied range. The change in polarity of the solvent also doesn't affect the stoichiometry of the complexes. The determined formation constant values are in the range of 0.49-10.8 dm3 mol-1, the highest is for the N-benzylaniline and the lowest is for o-chloroaniline. The effect of functional groups on the aniline moiety towards the strength and its electron releasing property has been discussed. The ΔH, ΔS, and ΔG values are all negative, so the studied complexes are reasonably stable and exothermic in nature. The ionization potentials of the donors were determined using the charge-transfer (CT) absorption bands of the complexes. The dissociation energies (W) of the charge-transfer excited state for the CT-complexes were also determined and are found to be constant. Springer-Verlag 2004.
- Neelgund, Gururaj M.,Budni
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p. 1395 - 1407
(2007/10/03)
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- A new synthesis of quinoxaline, imidazolidine, indole and carbazole derivatives
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Reactions of bis-benzalethylenediamine (1), N,N'-bis(aryl)- and N,N'-bis(cyclohexyl)ethane-1,2-diylidenediamines as well as N,N'-bis(aryl)benzene-1,4-diyldimethylidenediamines 2 with benzo- and naphthoquinones as well as α,β-unsaturated ketones such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ); 2,3,5,6-tetrachloro-1,4-benzoquinone (CHl-p); 3,4,5,6-tetrachloro-1,2-benzoquinone (CHl-o); 2,3-dichloro-1,4-naphthoquinone (DCNQ); 2,3-dicyano- l,4-naphthoquinone (DCNQ) and dicyanomethyleneindane-1,3-dione (CNIND) afforded quinoxaline, pyrazinoquinoxaline, imidazolidine, indole and carbazole derivatives as well as arylaminobenzo-, and napthoquinones.
- Aly,Hassan,Mohamed,Mourad
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p. 282 - 287
(2007/10/03)
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- Octa-alkoxy Phthalocyanine and Naphthalocyanine Derivatives: Dyes with Q-band Absorption in the Far Red or Near Infrared
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The lithium alkoxide-catalysed cyclic tetramerisation of various 3,6-dialkoxy-4,5-dichlorophthalonitriles, 1,4-dialkoxynaphthalene-2,3-dicarbonitriles and 3,6-dialkoxyphthalonitriles to give the corresponding metal-free octa-alkoxyoctachlorophthalocyanines, octa-alkoxynaphthalocyanines and octa-alkoxyphthalocyanines is described.An unexpected trans-alkoxylation reaction occurs during the cyclisation of the first two series of precursors.Metal-free phthalocyanines and naphthalocyanines have been converted into derivatives containing various metal ions.Compounds show Q-band absorption in the region 739-862 nm in toluene solution.The fluorescence spectra of selected examples are reported.The solubility of some of the compounds has been measured in a formulation of liquid crystal materials.
- Cook, Michael J.,Dunn, Adrian J.,Howe, Steven D.,Thomson, Andrew J.,Harrison, Kenneth J.
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p. 2453 - 2458
(2007/10/02)
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- A spectrophotometric study of molecular complexes of 2,3-dicyano-1,4-naphthoquinone
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Molecular complexes of 2,3-dicyano-1,4-naphthoquinone with various aromatic anilines were studied spectrophotometrically in dichloromethane solvent at different temperatures.All these complexes show a new broad charge-transfer band in the visible region of the electromagnetic spectrum.All the donors are known to form strong 1:1 complexes with the acceptor and their stoichiometry was unaffected by the variation of temperature over a small interval.The thermodynamic and spectroscopic parameters were evaluated.The order of donor strength followed the sequence: 2,5-dimethylaniline>2,3-dimethylaniline>N,N-dimethylaniline>p-toluidine>o-toluidine>m-toluidine>N-methylaniline>aniline.
- Budni, M. L.,Jayadevappa, E. S.
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p. 607 - 612
(2007/10/02)
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