Vinca major elegantissima

Vincarpin and Dihydrovincarpin are two additional examples of pseudo-cross-conjugated mesomeric betaines. They were isolated from Vinca major elegantissima (76TL4887) (Scheme 82). 

Two new zwitterionic alkaloids with a 5,6-dihydroindolo[2,3-a]quinolizine ring system have been isolated from Vinca major L. var. elegantissima Hort (13). The structures of vincarpine (4) and dihydrovincarpine (5) have been determined on the basis of their spectral data and via some derivatives obtained by either catalytic or hydride reduction. Interestingly, the H-NMR spectrum of vincarpine in TFA solution corresponds to structure 6 derived by lactonization of 4 in the presence of acid. 

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