A new and simple synthesis of fluoren-9-ones

Article abstract of DOI:10.1055/s-1993-25908

Ethyl cyclohexene-1-carboxylate (1) undergoes reaction with various aromatic substrates in presence of concentrated sulfuric acid to give cis-1,2,3,4,4a,9a-hexahydrofluoren-9-ones 3a-f which on dehydrogenation afforded the corresponding fluoren-9-ones 4a-f in good yield. Fluorenones with an alkoxy group in the meta-orientation with respect to carbonyl group have also been prepared.