- Divergent Synthesis of Quinolones and Dihydroepindolidiones via Cu(I)-Catalyzed Cyclization of Anilines with Alkynes
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A unique and efficient method for one-pot synthesis of diverse 4-quinolones from simple and readily available primary anilines and alkynes via Cu(I)-catalyzed direct cyclization has been developed. The (thio)phenols were also found to visible substrates for this reaction. Moreover, an unprecedented synthesis of dihydroepindolidiones has been demonstrated by using secondary anilines as the versatile substrates.
- Xu, Xuefeng,Sun, Ruzhong,Zhang, Sheng,Zhang, Xu,Yi, Wei
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supporting information
p. 1893 - 1897
(2018/04/16)
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- Regiospecific carbonylative annulation of iodophenol acetates and acetylenes to construct the flavones by a new catalyst of palladium-thiourea-dppp complex
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(matrix presented) Regiospecific carbonylative annulation of o-iodophenol acetates and acetylenes mediated by palladium-thiourea-dppp complex in the presence of base at 40°C under a balloon pressure of CO generates diversified flavones in high yields. This newly developed synthetic technology provides a highly efficient method for potential application to the combinatorial synthesis of those heterocycles on the solid support.
- Miao, Hua,Yang, Zhen
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p. 1765 - 1768
(2007/10/03)
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- PHOTOLYSIS OF CYCLIC ACETALS OF ARYL BENZOYLACETATES AS THE KEY STEP IN A NEW SYNTHESIS OF FLAVONES
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Although the yields found for the photo-Fries rearrangement of the aryl benzoylacetates 1 are poor, blocking of the carbonyl group, as in the related acetal derivatives 3, results in a substantial preparative improvement.Thus, the o-hydroxydibenzoylmethanes 2 are obtained from 1 with an average yield of 18percent, while the corresponding acetals 4 are obtained from 3 with an average yield of 58 percent.Compounds 4 are efficiently converted into flavones 8 by means of wet silica gel, through hydrolysis of the acetal moiety and subsequent cyclization of the resulting o-hydroxydibenzoylmethanes 2.
- Garcia, Hermenegildo,Iborra, Sara,Miranda, Miguel A.,Primo, Jaime
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p. 2511 - 2517
(2007/10/02)
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- 6-Endo-Dig vs. 5-Exo-Dig Ring Closure in o-Hydroxyaryl Phenylethynyl Ketones. A New Approach to the Synthesis of Flavones and Aurones
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The aryl phenylpropynoates 3a-c, prepared by esterification of phenylpropynoic acid with the corresponding phenols, by means of N,N'-dicyclohexylcarbodiimide, give upon irradiation the o-hydroxyaryl phenylethynyl ketones 4a-c.The cyclization of these compounds in basic media follows two alternative pathways: 6-endo-dig ring closure, to give the flavones 8a-c, and /or 5-exo-dig ring closure , to give the aurones 9a-c.The predominance of one or the other cyclization mode is strongly influenced by the reaction conditions.Thus, the use of potassium carbonate in acetoneas cyclizing reagent favors the 6-endo-dig process, while the 5-exo-dig process becomes clearly enhanced when using sodium ethoxide or potassium carbonate in ethanol.The mechanistic implications of these facts are discussed within the framework of Baldwin's rules.From the preparative point of view, the above results disclose the synthetic possibilities of the key ketones 4 as precursors of flavones and aurones.
- Garcia, Hermenegildo,Iborra, Sara,Primo, Jaime,Miranda, Miguel A.
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p. 4432 - 4436
(2007/10/02)
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