The Synthesis of 7-Isopropyl-2,4-dimethylazulene (Se-Guaiazulene) from 4-Isopropyltropolone

Abstract

7-Isopropyl-2,4-dimethylazulene (Se-guaiazulene) (I) was synthesized from 4-isopropyl-7-methyltropolone (II), which had itself been derived from 4-isopropyltropolone. The tropolone, II, was then converted to 3-acetyl-5-isopropyl-8-methyl-2H-cyclohepta[b]furan-2-one (VI) via the p-tolylsulfonyloxytropone derivative derived from II. The application of the azulene synthesis to VI gave 3-cyano-7-isopropyl-2,4-dimethylazulene-1-carboxylic acid (VII), from which I was obtained by the removal of the carboxyl and cyano groups.