H-1 and C-13 NMR assignments and conformational analysis of some podocarpene derivatives

This paper reports on the assignment of the H-1 and C-13 NMR spectra of fiv e podocarpene derivatives. Resonance assignments were made on the basis of one- and two-dimensional NMR techniques which included H-1, C-13, DEFT and HMQC and also 1D NOE difference spectroscopy. The ratio of the different co nformers in the six-membered C-ring of the podocarpene system was determine d by molecular mechanics calculations and analysis of proton spin-spin coup ling constants. Copyright (C) 2000 John Wiley & Sons, Ltd.