Compound 6 had the molecular formula C22H26N2O4, as suggested by HREIMS. The 13C NMR spectrum showed similar
patterns to those of 5 with an additional methoxy group (δH 3.78; δC 61.5) in 6. The connectivity between the methoxy group and C-11 was established by the HMBC correlation of the protons of methoxy group with δC 142.9 (s, C-11).The ROESY correlations of H-19 to H-21 and of H-15 to H-18 indicated that the configuration of the C-19C-20 double bond was E. Thus, the structure of 6 was established as 19(E)-11-methoxy-9,18-didemethoxygardneramine