This work describes the configurational and conformational analyses of 1,6,7-triacetoxy-8,13-epoxy-14-labden-
11-one, a labdane diterpenoid isolated from Plectranthus ornatus. Its relative stereochemistry was previously proposed by
comparison with 1H and 13C NMR data of forskolin (2); however, the configurations of C-8 and C-13 have not been confirmed.
Correlations between 13C NMR experimental data and HF/6-31G* calculated values of carbon chemical shifts
were performed for configurational and conformational analyses. This procedure was formerly applied to the configurational
analysis of 2. Among the seven different forskolin-type structures investigated, the 13C NMR data of 2 correlated
best with those with the same stereochemistry of 2 described in the literature. Thus, the same procedure was considered
valid for configurational analysis of the labdane diterpenoid isolated from P. ornatus. The relative stereochemistry of this
compound based on theoretical calculations was similar to the structure previously proposed, but the best results were obtained
considering configurational inversion at C-13.