Extensive 1D, 2D NMR spectra of some [7.0]metacyclophanes and X-ray analysis of (+/-)-myricanol

From the hexane extract of the bark of Myrica cerifera, the pentacyclic triterpenes taraxerol and myricadiol were isolated. The EtOH extract afforded the [7.0]metacyclophanes, (+/-)-myricanol(4), and myricanone (7). Accurate H-1- and C-13-NMR spectral assignments have been made for (+/-)-myricanol (4), 5,11,17-tri-O-acetyl-(+/-)-myricanol (5), 11-O-methyl-(+/-)-myricanol (6), and myricanone (7) by a study of the H-1-H-1-COSY, H-1-C-13-COSY (HETCOR), selective INEPT, and 1D NOE experiments. The structure of (+/-)-myricanol was established by a single crystal X-ray analysis. Molecular mechanics MM-3(94) calculations have been made for (R,Sa)- and (S,Sa)-myricanol, and the bond lengths, bond angles, and the torsion angles have been calculated for the energy-minimized conformation.