Lamellarins, structures

Banwell has developed a new approach to the core associated with several members of the lamellarin class of marine natural products. This approach utilized some interesting pyrrole arylation reactions including a Negishi. cross coupling of the iodopyrrole 46 followed by a double-barrelled Heck cyclization of the resultant arylpyrrole 47 yielding the core structure 48... 

The lamellarins constitute an important group of natural products isolated from marine invertebrates such as sponges, molluscs and tunicates with structures without precedents in natural or synthetic compounds. They are characterized for possessing important biological activities. The aim of this review is to provide an overview of the work published since the isolation of the first group of lamellarins <85JA5492> from the marine prosobranch mollusc Lamellaria sp, imtil the beginning of 2004. 

The structures of the lamellarins, except for A and E, were established by a combination of H and C NMR analyses using heteronuclear correlation techniques. New procedures for differentiation of HMBC at two- and three-bond correlation <96TL363> in combination with ADEQUATE experiments <96JMR282> and with coi-refocused 1,1-ADEQUATE <96JMR295> experiments were developed for a comprehensive identification of Vch and Vch... 

From a synthetic point of view, lamellarins are rather complex molecules. In the literature, there are described several approaches, which fall into two main synthetic categories (i) by pyrrole formation as the key step of the synthesis and (ii) by transformation of a pre-existent pyrrole derivative through cross-coupling reactions. Although and due to the structural... 

In this chapter, the structures, the source, and bioactivity of selected classes of typical marine alkaloids are described. The emphasis is on compounds that have emerged as novel leads, such as lamellarins (pyrroles), cephalostatins/ritterazines (pyrazines) and ecteinascidins (isoquinolines), and manzamines (P-carbolines) to give relevance to the role of marine alkaloids as an important source of leads for drug discovery. 

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