beta-triketones from Myrtaceae: Isoleptospermone from Leptospermum scoparium and papuanone from Corymbia dallachiana

Naturally occurring beta-triketones, isoleptospermone [3, 5-hydroxy-4-(2-me thyl-1-oxopentyl)-2,2,6 methyl-4-cyclohexene-1,3-dione) from Leptospermum s coparium] and papuanone [6, 5-hydroxy-4-(loxohexyl)-2,2,6,6-tetramethyl-4-c yclohex from Corymbia dallachiana], have been synthesized. Full spectral da ta are reported for the first time. The C-13 NMR spectra of 3, 6, and the o ther triketones flavesone (2), leptospermone (4), and grandiflorone (5) fou nd in Myrtaceous plants are fully assigned.