New diterpenes from the Caribbean sponge Epipolasis reiswigi

Four New Pregnane-10,2-carbolactones from an Epipolasis sp. Marine Sponge

Four new pregnane steroids, 3β,4β,16β-trihydroxypregna-5,17-diene-10,2-carbolactone (1), 16β-acetoxy-3β,4β-dihydroxypregna-5,17-diene-10,2-carbolactone (2), 12β-acetoxy-3β,4β,16β-trihydroxypregna-5,17-diene-10,2-carbolactone (3), and 12β,16β-diacetoxy-3β,4β-dihydroxypregna-5,17-diene-10,2-carbolactone (4) were isolated from an extract of an Epipolasis sp. marine sponge. The structures of the new compounds were determined by extensive NMR spectroscopic analysis and comparison with data from previously reported compounds.

A unified approach to the daucane and sphenolobane bicyclo[5.3.0]decane core: enantioselective total syntheses of daucene, daucenal, epoxydaucenal B, and 14-para-anisoyloxydauc-4,8-diene

Access to the bicyclo[5.3.0]decane core found in the daucane and sphenolobane terpenoids via a key enone intermediate enables the enantioselective total syntheses of daucene, daucenal, epoxydaucenal B, and 14-para-anisoyloxydauc-4,8-diene. Central aspects include a catalytic asymmetric alkylation followed by a ring contraction and ring-closing metathesis to generate the five- and seven-membered rings, respectively.

Stereochemical determination and bioactivity assessment of (S)-(+)-curcuphenol dimers isolated from the marine sponge Didiscus aceratus and synthesized through laccase biocatalysis

Electrospray ionization mass spectrometry-guided isolation of extracts from Didiscus aceratus led to the discovery of several new derivatives of the bioactive bisabolene-type sponge metabolite (S)-(+)-curcuphenol (1). The compounds obtained by this method included a mixture of known (2) and new (3) dihydroxylated analogs as well as a novel family of dimeric derivatives, dicurcuphenols A-E (4-8), and dicurcuphenol ether F (9). Dimers 4-9 were also subsequently obtained through a hemisynthetic method in which 1 was incubated with the enzyme laccase. Atropisomeric dimers 5 and 6 were subjected to vibrational circular dichroism analysis thereby establishing their absolute biaryl axial chirality as P and M, respectively. In contrast to 1, metabolites 2-9 exhibited weak or no cytotoxic or lipoxygenase inhibitory effects.