Poranthera corymbosa, alkaloids

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 (/). The related tricyclic alkaloid porantheiidine (416) is included here as an obvious carbinolamine derivative of the simple bicyclic system. 

In previous Reports the perhydro-9b-azaphenalene alkaloids derived from species of Coccinellidae (ladybird beetles) were discussed in the quinolizidine chapters while those isolated from the Australian shrub Poranthera corymbosa were included in the section devoted to miscellaneous alkaloids. In this Report the two groups of closely related alkaloids are considered together. 

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. ... 

Porantherin (1) is an alkaloid from the Australian plant Poranthera corymbosa and possesses an interesting tetracyclic skeleton of the 9b-azaphenalene type [167]. In an instructive biomimetic synthesis of 1 developed by Corey [168] the key intermediate (X) was subjected to the following reactions (a) and (b) leading via A to B, which was further transformed to the target molecule 1 ... 

Certain other groups of alkaloids that coincidentally have a quinolizidine ring system are discussed in other chapters. For example, the alkaloids of the Lythraceae are discussed in Chapter 37 and those of the genus Nuphar are discussed in Chapter 36. Yet other quinolizidine alkaloids (18 and 19) are known from the Ericaceae (Vaccinium myrtillus) and the Euphorbiaceae (Poranthera corymbosa) (see Piperidine... 

Porantherine is a Euphorbaceae alkaloid isolated from the woody shrub Poranthera corymbosa Brogn. It is known to poison cattle wherever it grows. It came to light for poisoning cattle in New South Wales and Queensland, Australia. Some other members o( this iamily oi alkaloids are shown below. 

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... 

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