Preparation of 6-Acetyl-2,2-dimethyl-4-chromanone as Constituents of Tussilago farfara LINN.

Masayuki NOMURA*,†, Masao KATO, Kanji SATO and Nobuo ABE

Department of Chemistry, Faculty of Education and Human Studies, Akita University; Tegata, Gakuen-cho, Akita-shi 010-8502 Japan
Department of Materials-process Engineering and Applied Chemistry for Environments, Faculty of Engineering and Resource Science, Akita University; Tegata, Gakuen-cho, Akita-shi 010-8502 Japan

6-Acetyl-2,2-dimethyl-4-chromanone(6), isolated from Tussilago farfara LINN., was prepared by oxidation of 6-ethyl-2,2-dimethyl-4-chromanone(4) using chromium(VI) oxide in acetic anhydride and acetic acid.
The compound 4 was obtained, via the intermediate of ester 3, by condensation of p-ethylphenol and 3-methylcrotonic acid using diphosphorus pentaoxide in polyphsphoric acid.
The conversion of 3 to 4 also proceeds efficiently by stirring of the reaction mixture with glass globes in the absence of diphosphorus pentaoxide.

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