Reactions of 3-nitro-2-trihalomethyl-2H-chromenes with C-nucleophiles. Synthesis of 3-nitro-4-(pyrazol-4-yl)-2-trihalomethylchromanes |
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| Authors: | V Yu Korotaev V Ya Sosnovskikh I B Kutyashev M I Kodess |
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| Institution: | (1) A. M. Gorky Ural State University, 51 prosp. Lenina, 620083 Ekaterinburg, Russian Federation;(2) I. Ya. Postovsky Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, 20 ul. S. Kovalevskoi, 620041 Ekaterinburg, Russian Federation |
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| Abstract: | The nucleophilic addition of acetylacetone and ethyl acetoacetate at the double bond of 3-nitro-2-trihalomethyl-2H-chromenes in the presence of NaH affords 2,3,4-trisubstituted chromanes containing the β-dicarbonyl fragment at position
4. The trans-trans configuration and the enol structure of the reaction products were confirmed by 1H NMR spectroscopy and X-ray diffraction. Treatment of these compounds with hydrazine gives the corresponding 3-nitro-4-(pyrazol-4-yl)-2-trihalomethylchromanes.
The reactions of 3-nitro-2-trihalomethyl-2H-chromenes with nitromethane and nitroethane in the presence of K2CO3 produce 1,3-dinitro derivatives of the chromane series.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1945–1955, November, 2006. |
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| Keywords: | chromenes chromanes nitro compounds pyrazoles Michael reaction diastereomers NMR spectroscopy X-ray diffraction study |
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