Synthesis of the tricyclic core of alkaloid securinol B using a cascade of vilsmeier-haack and mannich cyclizations
Larouche-Gauthier, Robin; Bélanger, Guillaume
Abstract: The Securinega alkaloids are a family of approximately 20 tetracyclic compounds isolated from diverse Securinega, Phyllanthus, and Margaritaria species of the Euphorbiaceae plant family. Most of these alkaloids possesses an indolizidine skeleton fused with an azabicyclo[3.2.1]octane system, as in securinine (1), the major Securinega alkaloid, and in viroallosecurinine (2) (Figure 1). These compounds exhibit interesting biological activity, such as acting on the central nervous system as γ-aminobutyric acid receptor antagonists. In 1965, Tamura and Iwamoto isolated much rarer hydroxy-substituted Securinega alkaloids, securinol A and B (0.0005% and 0.00009%, respectively), from S. suffriticosa. The structure of these alkaloids was first assigned as 3 and 4. In 1991, Arbain and Sargent identified 5 as the revised structure of securinol A, from X-ray analysis of its crystalline hydrobromide salt. Since both securinol A and B give viroallosecurinine (2) upon treatment with mesyl chloride and pyridine, it was therefore suggested that securinol B has structure 6.
The following license files are associated with this document: