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[摘要]：The single-crystal X-ray data of akuammigine picrate hydrate (1 center dot Picr center dot H2O) confirm the relative configuration of the indole alkaloid akuammigine (1) as epiallo (Fig. 1). With reference to the known (15S)-configuration due to biosynthesis, the absolute configuration of the other stereogenic centers is thus given by (3R,19S,20S). Four crystallographically independent molecules are observed in the asymmetric unit (Fig. 2). Each of the alkaloid cations forms H-bonds to a H2O and a picrate anion (Fig. 3). The H2O molecules are further associated by a H-bond as indicated by the short O center dot center dot center dot O distance (Table 2). The conformation in the solid state of the picrate hydrate is now firmly established, and a cute H-bonding motif is observed. |
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