Characterization data (1H NMR, 13C NMR, αD and HRMS) for diterpenes

These data were used to elucidate the chemical structures for the new compounds and also to confirm the structures of the known molecules and compare them with the literature available data. 1H and proton-decoupled 13C NMR spectra were recorded at 400 MHz (1H) and 100 MHz (13C), and 500 MHz (1H) and 125 MHz (13C).

Chemical shifts (δ) are reported in ppm using residual undeuterated solvent signals as internal standards (CHCl3 at 7.26 ppm, MeOH at 3.31 for 1H NMR spectra and CDCl3 at 77.1 ppm, CD3OD at 49.0 ppm for 13C NMR spectra). In case of C5D5N, TMS was used as internal standard in 0.00 ppm. Multiplicity data are reported as follows: s = singlet, d = doublet, t = triplet, br s = broad singlet, br d = broad doublet, dd = doublet of doublets, dt = doublet of triplets, td = triplet of doublets, ddd = doublet of doublet of doublets, and m = multiplet.