Syntheses and absolute configurations of the marine sponge purines (+)-agelasimine-A and (+)-agelasimine-B

The first total syntheses of (+)-agelasimine-A and (+)-agelasimine-B, adenine-related bicyclic diterpenoids isolated from the marine sponge Agelas mauritiana, have been achieved via a highly stereoselective route. On the basis of the present results, the absolute configurations of both alkaloids have been defined as shown in stereoformulas (+)-1a and (+)-1b, respectively. (C) 1997 Elsevier Science Ltd.