The COSY and NOESY (Figure 1) experiments
were useful in establishing the structure of 1.
Significant correlated sequences of OMe-1/OMe-2/H-3/H-
4/H-5, H-6a/H-7/H-8/H-9, and H-11/H-12 were observed in
the NOESY spectrum (Figure 1). The 13C NMR spectrum,
showed 10 aromatic carbons between ä 153.5 and 112.3;
two methoxys at ä 60.4 and 55.9; three methylenes at ä
53.8, 30.3, and 28.5; two carbonyl carbons at ä 185.1 and
155.4; one carboxylic methyl carbon at ä 53.2; one quaternary
carbon at ä 38.8; and one methine at ä 54.5, in
agreement with structure 1. Compound 1 is a novel
alkaloid, which has been named promucosine and is the
first example of a natural N-(methoxycarbonyl)proaporphine.