All 2D NMR data were recorded using standard pulse programs. GC–MS analyses
in the scan mode were performed on a HP-5890 series II GC, equipped with EPC coupled to a HP-5972 MS. Samples were injected using a splitless injector at 250◦C on an Rtx-5MS column (30m×0.25?m×0.25mm). The carrier gas was helium. The temperature program was as follows: initial 170◦C with a 1-min hold; ramp0.083◦Cs−1to185◦C,1-minhold;ramp0.25◦Cs−1to330◦C; 10-min hold; and scanning from 29 to 500u. The compounds were characterised by comparisons of their spectral data with known samples (Lall et al., 2006).