FURTHER-STUDIES OF ALKALOIDS FROM RENIERA-SARAI - STRUCTURES OF SARAINE-3 AND ISOSARAINE-3 - ABSOLUTE STEREOCHEMISTRY OF SARAINE-1 AND SARAINE-2

A new macrocyclic diamine alkaloid, named isosaraine-3 (9), has been i solated from the Mediterranean sponge Reniera sarai. The structures of both this new compound and saraine-3 (6), until now only partially cl arified, have been completely elucidated by extensive spectroscopic st udies. The absolute stereochemistry of the quinolizidone systems prese nt in the co-occurring major alkaloids, saraine-1 (4) and saraine-2 (5 ), has been determined by applying advanced Mosher's method to the alc ohol derivatives (10-13). Copyright (C) 1996 Elsevier Science Ltd