An insecticidal mixture of tetramethylcyclohexenedione isomers from Kunzea ambigua and Kunzea baxterii

A mixture of isomers, all 4-[1-(5,7-dihydroxy-6-methyl-4-oxo-2-phenyl-chroman-8-yl)-3-methyl-butyl]-5-hydroxy-2,2,6,6-tetramethyl-cyclohex-4-en-1,3-diones, which comprises a pair of epimers, each of which is a pair of conformers, has been isolated from the hexane extract of the aerial parts of Kunzea ambigua and K. baxterii (Myrtaceae). The mixture exhibits moderate insecticidal activity in comparison with natural pyrethrum extract. Two Australasian species of Myrtaceae contain a mixture, which has insecticidal activity. It comprises two epimers (at C-1′) each of which exists as a pair of conformers.