Isolation, characterisation and synthesis of an insecticidal tetramethyltetrahydrochromenedione-spiro-bicyclo[3.1.1]cycloheptane from two species of Myrtaceae

A new moderately insecticidal compound, named ficifolidione, has been isolated from the hexane extract of the aerial parts of two species of Myrtaceae, Eucalyptus ficifolia and Kunzea ericoides. Its structure, (1′R,2′R,4R)-4-isobutyl- 6,6,8,8-tetramethyl-2,3,4,8-tetrahydrochromene-5,7-dione-2-spiro-2′-6,6-dimethyl-bicyclo[3.1.1]heptane (), was confirmed by synthesis from syncarpic acid, isovaleraldehyde and (1S)-β-pinene.