Sarain A is a complex macrocyclic marine alkaloid extracted from sponges of the order Haplosclerida. It is likely that this alkaloid shares a common origin with manzamine alkaloids, also extracted from sponges of the same order. In this paper, new concepts concerning this origin are presented and constitute the basis for a synthetic strategy. A preliminary evaluation of this strategy is presented and
Zerumbone 1, having powerful latent reactivity and containing two conjugated double bonds and a double conjugated carbonyl group is the major component of the essential oil of wild ginger, Zingiber zerumbet Smith. The conjugation system plays an important role in the expression of biological activity. N-Bromosuccinimide (NBS) reaction of 1 gave high reactive intermediate 2 with an exo-methylene group, which was obtained from 1 quantitatively. Treatment of 2 with nucleophiles gave various zerumbonependant derivatives, including C-H, C-O, C-N, and C-C bond formation, maintaining the conjugation system through S(N)2'-type reaction. Almost all zerumbone-pendant derivatives showed a good value of IC50 against the suppressive effect of NO generation. Among them, amine derivative 5, binding with 2 mol of zerumbone, showed the strongest activity (IC50: 0.24 mu M). (C) 2013 Elsevier Ltd. All rights reserved.
Eberson,L. et al., Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry, 1976, vol. 30, p. 906 - 907