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The condensation of dehydroacetic acid with RFCO2Et in the presence of LiH in THF afforded fluorine-containing 3-acetoacetyl- 4-hydroxy-6-methylpyrones, which underwent cyclization to 2-polyfluoroalkyl-7-methylpyrano[4,3-b]pyran-4,5-diones on treatment with concentrated sulfuric acid at room temperature.
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Sosnovskikh et al. (2001) studied this question.
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