Alkaloids from aspidosperma family

The Aspidosperma family of indole alkaloids has inspired many synthetic strategies for the construction of their pentacyclic framework of the parent compound aspidospermidine (366), since the initial clinical success of two derivatives, vinblastine (10) and vincristine, as anticancer agents. The alkaloids such as (-)-rhazinal (369) and (-)-rhazinilam (6) have been identified as novel leads for the development of new generation anticancer agents [10,11]. Bis-lactams (-)-leucunolam (370) and (-t-)-epi-leucunolam (371) have bio-genetic and structural relationships with these compounds [236]. Recently, enantioselective or racemic total syntheses of some of the these natural product were achieved. One successful synthesis was the preparation of the tricyclic ketone 365, an advanced intermediate in the synthesis of aspidospermidine (366), from pyrrole (1) (Scheme 76) [14]. The key step is the construction of the indolizidine 360, which represents the first example of the equivalent intramolecular Michael addition process [14,237,238]. The DIBAL-H mediated reduction product was subject to mesylation under the Crossland-... 

From 26 they could access a series of structurally related alkaloids from the Strychnos (Strychnine), Aspidosperma, and Kopsia families and from 27 Minliesine was accessible, which is structurally different alkaloid from the Strychnos family. 

Aspidospermidine, one of the simplest of Aspidosperma alkaloids containing a pentacyclic ring system, was isolated from Aspidosperma quebracho bianco and other Aspidosperma species. Aspidosperma is a genus of flowering plant in the family Apocynaceae. The alkaloids aspidosper-mine were first synthesized by Stork and Dolfini in 1963. " Since then the compound has had many extensive investigations, and more than 30 research groups have synthesized... 

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