抄録
A new tetracyclic sesquiterpene ketone, solanascone (1), was isolated from Nicotiana tabacum cv. Burley. ^1H and ^<13>C NMR, mass and IR spectra indicated that (1) was tetracyclic, and contained six or higher membered saturated ketone, a methylene adjacent to the ketonic function, two methyl groups attached to quaternary carbons and a methyl group attached to a tertiary carbon. A partial structure (I) was obtained from the double irradiation ^1H NMR experiments carried out on the europium shifted spectrum. The complete structure and stereochemistry of (1) was elucidated by X-ray crystallography of its oxime. Irradiation of (-)-solavetivone (2) in the methanol produced solanascone (1) by a [2+2] photocyclization. This result suggests that (2) may be a direct precursor of (1) and the absolute configuration of (+)-solanascone was shown to be as in the stereostructure (1).
