Triumphalone, a diketone from the volatile oil of the leaves of Melaleuca triumphalis, and its spontaneous conversion into isotriumphalone

The major component of the volatile oil from the leaves of Melaleuca triumphalis was identified as (rel)-1β-pentyl-1α,6α-dihydroxy-3,3,5,5-tetramethyl-cyclohexa-2,4-dione (trivial name triumphalone 1). Relative stereochemistry was established by nuclear Overhauser experiments and X-ray studies on the 3,5-dinitrobenzoic acid ester. On prolonged standing the presence of a rearrangement product was observed which was characterized as (rel)-1β-pentyl-1α,3α-dihydroxy-4,4,6,6-tetramethylcyclohexa-2,5-dione (trivial name isotriumphalone 2), presumably arising from an acid catalyzed shift of the pentyl group from C-1 to C-2.