1.2- Dehydro-2-norlimacusine

There are three alkaloids in this group, two of which are the secobisbenzylisoquinolines auroramine (390) and maroumine (391). These two bases, that have only been found as metabolites of Gyrocarpus americanus (Hemandiaceae), differ only in the nature of their C(6 ) groups, with the former being a methoxy while the latter is a hydroxy. The remaining alkaloid is 1.2-dehydro-2-norlimacusine (291) from Caryomene olivascens (Menispermaceae). 

The above-ground parts of C. olivascens Bameby et Krukoff have yielded the bis-benzyltetrahydroisoquinolines (—)-2-norlimacine (20a), a new base (—)-caryolivine (20c), and l,2-dehydro-2-norlimacusine (21a) as the principal components of the alkaloid mixture (412). On the other hand, the fruits have furnished eight non-quaternary bases, including (H-)-coclaurine (26a), (—)-stepharine (27b), the protoberberine (+)-pseudopalmatine (34f), and a series of 2,3,10,11-tetra-substituted tetrahydroprotoberberines (34a-e). Bis-benzyltetrahydroisoquinoline alkaloids appear to be absent from the fruit (413). 

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