Spectroscopic and Density Functional Theory Studies of a New Rosane Type Diterpenoid from Stachys parviflora

A rosane type diterpenoid has been isolated from the ethyl acetate soluble fraction of Stachys parviflora. The structure elucidation was based primarily on 1Dand 2D-NMR techniques including correlation spectroscopy (COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple bond correlation (HMBC), and nuclear Overhauser effect spectroscopy (NOESY). Density functional theory calculations have been performed to gain insight into the geometric, electronic and spectroscopic properties of the isolated diterpenoid. The geometries, vibrational spectrum and electronic properties were modeled at B3LYP/6-31G(d) and the theoretical data correlated nicely with the experimental values. Simulated chemical shifts at B3LYP/6-311+G(2d,p) showed much better correlation with the experimental chemical shifts, compared to B3LYP/6-31G(d) and WP04/6-31G(d).