Plumeran

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. 

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. 

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. 

PLUMERAN-PLUMERAN TYPE PLUMERAN IBOGAN TYPE... 

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

Among plumeran alkaloids isolated from the leaves of T. coffeoides (Hazunta modesta), two minor compounds were not previously discussed (70). One was recognized as 3-oxotabersonine (68, C21H22N203, MP 151.5-153°C, [a]D -11.4°) identical to the product isolated by Sakai from the seeds of Amsonia elliptica (198). Compound 68 was also obtained in 32% yield by KMn04 oxidation of tabersonine (67). 

Plumeran alkaloids containing a lactone ring are present only in T. apoda from Cuba (43). In addition to apodine (24), a novel alkaloid of structure 86 (C21H22N205) assigned on the basis of mass spectroscopic studies, has been isolated,... 

Aspidospermine-Aspidofractine-Eburnamine Group. The structural and biosynthetic relationships between the various alkaloids in this group, which are referred to by the authors as the plumerane alkaloids, since they occur exclusively in plants of the subfamily Plumerioidae of the Apocynaceae, have been discussed in some detail.1110... 

Vindesine Hip (plumeran) Catharanthus roseus Substructure of vinblastine... 

Guimaraes HA, Vieira UC, Braz R, Crotti AEM, Almeida VD, de Paula RC. Two novel plumeran indole alkaloids isolated from Aspidospoma cylindrocarptm (Apoc-ynaceae). Helv Chim Acta 2013 96(9) 1793-800. 

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