- Gold-catalyzed cyclization of 1-(2′-Azidoaryl) propynols: Synthesis of polysubstituted 4-quinolones
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An unprecedented gold-catalyzed procedure for the synthesis of polysubstituted 4-quinolones from 1-(2′-Azidoaryl) propynols is described. The reaction undergoes an intramolecular nucleophilic attack of the azide group to the Au-Activated triple bonds in a 6-endo-dig manner and subsequent gold-Assisted expulsion of N2 to furnish an α-imino gold carbene intermediate, which triggers a 1,2-carbon migration and finally is converted to 2,3-disubstituted 4-quinolone.
- Wu, Xiang,Zheng, Lang-Lang,Zhao, Li-Ping,Zhu, Cheng-Feng,Li, You-Gui
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supporting information
p. 14769 - 14772
(2019/12/24)
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- Intramolecular Fe(II)-Catalyzed N-O or N-N bond formation from aryl azides
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(Figure presented) Iron(II) bromide catalyzes the transformation of aryl and vinyl azides with ketone or methyl oxime substituents into 2,1-benzisoxazoles, indazoles, or pyrazoles through the formation of an N-O or N-N bond. This transformation tolerates a variety of different functional groups to facilitate access to a range of benzisoxazoles or indazoles. The unreactivity of the Z-methyloxime indicates that N-heterocycle formation occurs through a nucleophilic attack of the ketone or oxime onto an activated planar iron azide complex.
- Stokes, Benjamin J.,Vogel, Carl V.,Urnezis, Linda K.,Pan, Minjie,Driver, Tom G.
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supporting information; experimental part
p. 2884 - 2887
(2010/08/21)
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- An In-depth Study of the Azidobenzophenone-Anthranil-Acridone Transformation
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The title transformation, particularly the conversion of anthranils into acridones, is shown to be critically sensitive to temperature, solvent, substituent, and metal catalysts.Thus the conversion of 3-(p-tolyl)anthranil into an acridone gives a ratio of 2-and 3-methyl derivatives varying from 0.6:1 to 4.7:1 with changing temperature and solvent.In other similar thermolyses, solvents (e.g. 1,2,4-trichlorobenzene) were incorporated into the product and traces of metals and their derivatives had a dramatic effect on the rate and course of the reaction.The most effective catalysts were iron powder and aluminium acetylacetonate. 3-(2,6-Disubstituted phenyl)anthranils gave acridones in which the substituents were either lost or rearranged onto N or C, the last cases involving sequential -sigmatropic shifts. 3-Thienylanthranils gave related thienoquinolones on thermolysis; again the reaction were very sensitive to catalysis.Blocked thienylanthranils also gave rearrangement products, but the non-aromatic intermediates could be isolated.
- Hawkins, David G.,Meth-Cohn, Otto
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p. 2077 - 2087
(2007/10/02)
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