Dimethyl 6-methoxy-4abeta-methyl-9-oxo-1,2,3,4,4a,9,10,10abeta-octahydrophenanthrene-1,1-dicarboxylate.

In the title tricyclic keto-diester, C(20)H(24)O(6), a potential intermediate in the synthesis of bioactive podocarpic acid, the outer cyclohexane ring (in a chair conformation) is cis fused to the central cyclohexanone ring (in a half-chair conformation). The conformational analysis of the compound, investigated by semi-empirical quantum mechanical AM1 calculations, shows a good agreement with the X-ray structure, except for the orientation of the methyl, methoxyphenyl and methoxycarbonyl substituents.