Amphilectane

Shortly after amphilectanes 96 and 97 were reported, other metabolites from Amphimedon were isolated, with the majority of their structures supported by the corresponding spectral and X-ray data. Although the gross structures of the series, 98-100, are regio isomers with respect to one of the isocyano functions, they also exhibit minor differences in the C4 moiety attached to C-l. X-ray determination of 98 led to assignment of its relative stereochemistry, thereby securing assignments for 99 and 100 by comparison of spectroscopic data [61]. 

Compounds from Pseudopterogorgia elisabethae can be classified according to their carbon skeletons. So far 15 carbon skeletons have been identified which are based on the serrulatane skeleton. Various cyclizations (see also Sect. 3.1, Scheme 1) of this precursor lead to newpolycycHc structures (e.g., amphilectanes, ehsabethanes, etc.) that are starting points for new degradation products (seco-, nor-, bisnor-, etc. compoimds). 

A C9-C14 cycHzation forms the ring C and leads to the amphilectane skeleton which is foimd for instance in pseudopterosins A-F (10, aglycone) [10] isolated from Pseudopterogorgia elisabethae extracts stemming from a Bahamian collection site (Fig. 5). This class of natural products can be characterized as... 

Elisabethol (13) [4] shows the same stereochemistry as the pseudopterosin aglycone 10. Elisabatins A-C (14,15,16) [ 14] have the same amphilectane skeleton found in the aglycone portion of the pseudopterosins. The elisabatins are unique among the amphilectane-type diterpenoids because they possess an unusually high unsaturation number that leads to extended aromatic conjugation. 

Diterpene isothiocyanates fall into three distinct structural categories regarding their carbon skeletons the acyclic tetraenes (220 and 221), the biflorane framework (including the kalihinol family) (222-238), and the amphilectane framework (including the cyclo- and isocycloamphilectanes) (239-241). Like the sesquiterpene isothiocyanates, most of these compounds were isolated along with the corresponding isocyanate and formamide compounds. 

Rearranged Pseudopterosins seco- Amphilectanes Serrulatanes Other... 

The amphilectane derivatives 18-20 showed generally a lower activity, with IC50 values going from 100 to 800 ng/mL, the less active compound of the series being the isothiocyanate 20. This is in line with the lower activities of isothiocyanate derivatives, as observed also in other studies... 

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