Vindoline and 16‐de­methoxy­vin­doline: two catharanthus‐derived alkaloids

Vindoline, C₂₅H₃₂N₂O₆, and 16‐de­methoxy­vindoline, C₂₄H₃₀N₂O₅, both of which are naturally occurring biologically active products derived from plants, are important as possible starting materials for the synthesis of valuable anticancer antibiotics, viz. vincristine and vinblastine, and other pharmaceuticals. The vindoline framework consists of two five‐ and three six‐membered condensed rings. One of the six‐membered rings adopts a boat conformation, one adopts a sofa conformation and the third is planar. Both five‐membered rings have envelope structures. The intramolecular hydrogen bonds present in the structures are characteristic of vinca alkaloids.