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

Abstract

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 ¹H- and ¹³C-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 ¹H-¹H-COSY, ¹H-¹³C-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.