Regio- and Stereoselective Oxidation of (+)-Δ3-Carene by the Larvae of Common Cutworm (Spodoptera litura)

Biotransformation of (+)-Δ3-carene (1) and (+)-(1S,3S,4R,6R)-3,4-epoxycarane (1-1) by larvae of Spodoptera litura was investigated. Compound 1 was transformed to (+)-(1S,3S,4R,6R,7S)-3,4-epoxycaran-9-ol (1-2) by S. litura. This structure was established by infrared, electron impact−mass spectrometry, one- and two-dimensional NMR spectral studies, and (+)-(1S,3S,4R,6R)-3,4-epoxycarane (1-1) was transformed for confirmation of a metabolic pathway. The results indicate that the metabolic reaction of compound 1 by the larvae of S. litura was regioselective hydroxylation at the methyl group of the geminal dimethyl (C-9 position) followed by stereoselective epoxidation at the carbon−carbon double bands (C-3 position). (+)-(1S,3S,4R,6R,7S)-3,4-Epoxycaran-9-ol (1-2) was a new compound.