Formation of 8-epi-9(11)-podocarpen-12-one in the course of the preparation of 9(11)-podocarpen-12-one from O-methylpodocarpane and related studies

The preparation of podocarp-9(11)-en-12-one (1a) from O-methylpodocarpane (2) was investigated with the aim of clarifying whether 8-epipodocarp-9(11)-en-12-one (1b) is formed to any extent during the early stages of the process. This study, supported by molecular-mechanics calculations, resulted in the preparation, along with 1a, of the previously undescribed 1b, which could be fully characterized by means of 2D-NMR experiments. Significant differences recorded in the NMR and NOESY spectra of 1a and 1b were of diagnostic value in establishing the relative configuration at C(8) and possibly might be helpful to solve similar problemson podocarp-9(11)-en-12-one derivatives.