| Abstract
| - Arenosclerins A (2), B (3), and C (4), as well as haliclonacyclamine E (1), are new tetracyclic alkylpiperidinealkaloids isolated from a new species of marine sponge belonging to the order Haplosclerida, Arenosclerabrasiliensis, a species endemic to the southeastern Brazilian coast. The alkaloids were isolated as theirhydrochloride salts and identified by analysis of spectroscopic data. Data obtained from 1H−H COSY,HMBC, and HSQC−TOCSY NMR experiments allowed complete assignment of the 1H and 13C resonances,and analysis of the NOESY and ROESY spectra showed that the only differences between 2, 3, and 4were the relative stereochemistries of the bispiperidine ring system. Arenosclerins A−C are the firsthaliclonacyclamine/halicyclamine-related alkaloids with a hydroxy group in the bridging alkyl chain.
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