Poranthera corymbosa Porantheridine

The structures of the azaphenalene alkaloids of Poranthera corymbosa, poran-therine, porantheridine, poranthericine (51), and O-acetylporanthericine (52) and a related quinolizidine were determined by X-ray analysis (Vol. 5 of these Reports). The isolation and characterization of these alkaloids has now been described in full, and the structure of a new base, porantheriline (53), has been established. ... 

Porantherilidine (415), the only bicyclic member of a group of quinolizidine alkaloids from the Australian shrub Poranthera corymbosa, was described in the previous chapter on simple indolizidine and quinolizidine alkaloids in Volume 28 of this series (7). The related tricyclic alkaloid porantheridine (416) is included here as an obvious carbinolamine derivative of the simple bicyclic system. 

Porantheridine (1188) is included among the simple quinoHzidine alkaloids in this review as it can be viewed as the internal aminal of a hydroxy-quinohzidinium system. It is one of a handful of rare natural products obtained from the AustraHan shmb Poranthera corymbosa (Euphorbiaceae), most of which are 9b-azaphenalenes. Three enantioselective syntheses... 

The Kouklovsky/Vincent and co-workers formal synthesis of ( )-porantheridine 197 (discovered from the Australian bush Poranthera corymbosa) is complementary to the work of Kibayashi (Scheme 41.41). ° The treatment of hydroxamic acid 192 with sodium periodate in the presence of cyclopentadiene 33 in methanol and water at 0°C delivered the bicyclic 3,6-dihydro-oxazine 193 in 61% yield. Ring-rearrangement metathesis (ring opening/ring... 

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