NOESY unknown structure

With the completion of the two-dimensional structural elucidation of the unknown compound, questions arise concerning its three-dimensional shape [i.e., the relative orientations of substituents (e.g., Hm or methyl 24) at various carbons). For a molecule with MW = 466, the NOESY experiment can provide a wealth of such stereochemical information. The NOESY spectrum of the 15-mg sample of the compound is shown in Figure 7-22. The data from these contour plots are summarized in Table 8-5 and illustrated, in part, in structure 8-6. 

Compound 1 was the major alkaloid present and compounds 2 and 3 were previously unknown as natural products. The related naphthylisoquinoline alkaloids ancistrocladine (5) and its atropisomer hamatine (6) were previously known from other Asian Ancistrocladus species [25] while the 7,3 -linked naphthyl-isoquinoline, ancistrotectorine (8), has been previously isolated from Ancistrocladus lectorius from Thailand [26]. The structure of I was deduced from spectral data (UV, MS, NMR) as well as by its ready conversion to the known 2 through successive mesylation and LiAIH4 reduction. Likewise the structure and relative stereochemistry of 4 were established by spectral analysis (HMBC, NOESY) and by conversion to the known (-)-N-formyl-O-methylancistrocladine derivative 7 via successive formylation followed by methylation (Mel, NaH-DMF). 

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