Plumeran-type alkaloid

B. Plumeran-Type Alkaloids 1. Voaphylline-Subtype Alkaloids... 

Alkaloids of the plumeran type are interesting because compounds with opposite stereochemistry were isolated from different plants. In some cases, a racemic form was also found besides the optically active one. The racemic forms are indicated by the prefix rac before the name and relative number. The generally accepted biogenetic numbering system proposed by Le Men and Taylor (76) is used through this article. This chapter refers to literature through June 1984. 

A greater number of compounds has been found among plumeran, cory-nanthean and ibogan alkaloids. The last type seems to be characteristic of all Tabemaemontana plants, being contained in almost all species. 

Alkaloids of plumeran, aspidospermatan, corynanthean, and ibogan types are conveniently subdivided into subtypes depending on further variations of the terpenic portion or, in very few cases, of the indole portion of the fundamental skeleton. The subtypes are named according to the most representative member, even if this is not found in Tabemaemontana. 

The great number of different alkaloids found in Tabemaemontana precludes a discussion of the structure elucidation and chemistry of all of them. To keep the treatment concise, a major compromise was necessary. The alkaloids that have been reported in previous volumes of this treatise (as indicated in Table I) and their trivial modification will not be mentioned here. This compromise eliminates from the discussion well-established and long-known alkaloids that were isolated not only from Tabemaemontana but also from other genera. Moreover, the plumeran alkaloids isolated up to 1976 and ebuman-type and bisindole alkaloids isolated up to 1979 are covered in Volumes XVII and XX. The main efforts of this chapter will be focused on more recently isolated compounds, some of which are structurally and biogenetically relevant and have been found only in plants of the genus Tabemaemontana. 

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