2-Polyfluoroalkylchromones. 12. Nitration of 5,7-dimethyl-2-polyhaloalkylchromones and complete assignment of signals in the 1H and 13C NMR spectra of 5,7-dimethyl-2-trifluoromethylchromone and its mono- and dinitro derivatives |
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| Authors: | Sosnovskikh V Ya Usachev B I Kodess M I |
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| Institution: | (1) A. M. Gorky Ural State University, 51 prosp. Lenina, 620083 Ekaterinburg, Russian Federation;(2) Ural Branch of the Russian Academy of Sciences, Institute of Organic Synthesis, 20 ul. S. Kovalevskoi, 620219 Ekaterinburg, Russian Federation |
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| Abstract: | The nitration of 5,7-dimethyl-2-polyhaloalkylchromones affords either 5,7-dimethyl-6-nitro- or 5,7-dimethyl-6,8-dinitro-2-polyhaloalkylchromones, depending on the reaction conditions. Signals in the 1H and 13C NMR spectra of the sterically hindered chromones were completely assigned using the 2D NOESY, HETCOR, and COLOC spectra. The influence of nonplanar nitro groups on chemical shifts of carbon atoms was studied. Some spectral peculiarities of the peri-methyl group were revealed. The 1H-1H and 13C-1H spin-spin coupling constants, including the extreme six-bond long-range coupling between the protons of the Me(5) group and H(8), were determined. |
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| Keywords: | 2-polyhaloalkylchroman-4-ones 2-polyhaloalkylchromones nitration 1H and 13C NMR spectroscopy spin-spin coupling constants increments of substituent chemical shifts peri-methyl group sterically hindered nitro groups |
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