Ent-Chromazonarol

Assignment of the trivial name 8-epichromazonarol to the metabolite 3 7 isolated from Smenospongia aurea is misleading since it implies a stereochemical relationship with chromazonarol (an algal metabolite) that has not be established. The arbitrary absolute stereochemistry depicted in this review is more closely related to that of the known sponge metabolite ent-chromazonarol, rather than the algal metabolite chromazonarol. In fact the absolute stereochemistry of 37 remains unknown. 

Barrero, A.F., Alvarez-Manzaneda, E.J., Herrador, M.M., Chahbotm, R., and Galera, P. (1999) Synthesis and antitumoral activities of marine ent-chromazonarol and related compounds. Bioorg. Med. Chem., 9, 2325-2328. 

Originally presented as derivatives of drimane (Fenical et al., 1973), it was established and confirmed by stereoselective synthesis, that zonarol and its derivatives have the carbon skeleton of ent-drimane (Welch and Rao, 1977a, 1978). Zonarone and isozonarone - the quinonic equivalents of zonarol and isozonarol - were prepared by oxidation of the latter, but could be intermediates in the biosynthesis of cyclozonarone, chromazonarol, and iso-chromazonarol which were isolated from Dictyopteris undulata (Fenical and McConnell, 1975). The probable biogenetic relationships between these compounds are summarized in Figure 14.13 (Kurata, Taniguchi, and Suzuki, 1996). 

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