beta-triketones from myrtaceae: isoleptospermone from leptospermum scoparium and papuanone from corymbia dallachiana

Naturally occurring beta-triketones, isoleptospermone [3, 5-hydroxy-4-(2-methyl-1-oxopentyl)-2,2,6, 6-tetramethyl-4-cyclohexene-1,3-dione) from Leptospermum scoparium] and papuanone [6, 5-hydroxy-4-(1-oxohexyl)-2,2,6, 6-tetramethyl-4-cyclohexene-1,3-dione from Corymbia dallachiana], have been synthesized. Full spectral data are reported for the first time. The 13C NMR spectra of 3, 6, and the other triketones flavesone (2), leptospermone (4), and grandiflorone (5) found in Myrtaceous plants are fully assigned.