2-Hydroxy-2-(polyhaloalkyl)chroman-4-ones react with diethoxymethyl acetate at 140-150 °C for 15 minutes to give 3-(polyhaloacyl)chromones in good yields. The reactions of these compounds with amines proceeds at C-2 with pyrone ring-opening and formation of 2-(alkyl/arylaminomethylene)-2-hydroxy-2-(polyfluoroalkyl)chroman-4-ones.
chroman-4-ones - diethoxymethyl acetate - formylation - 3-(polyhaloacyl)chromones - amines