The Active Centres of Agelastatin A, a Strongly Cytotoxic Alkaloid of the Coral Sea Axinellid SpongeAgelas dendromorpha, as Determined by Comparative Bioassays with Semisynthetic Derivatives
Agelastatin A (1), an unusual alkaloid of the axinellid sponge Agelas dendromorpha from the CoralSea, can be selectively acetylated (7) or methylated at OHC(8a) (4), peracetylated (8) or permethylated at OHC(8a), NH(5), and NH(6) (5), or, finally, subjected to C(9)C(8a) (14) or C(5b)C(8a) β-elimination (11–13), in a regiospecific manner or not, depending on the reaction conditions. Under acidic conditions