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Halogenated C15 Acetogenin Analogues of Obtusallene III from a Laurenciella sp. Collected in Corsica

Sutour, Sylvain, Therrien, Bruno, von Reuss, Stephan H., Tomi, Félix
Journal of natural products 2018 v.81 no.2 pp. 279-285
X-ray diffraction, acetogenins, biochemical pathways, bromine, metabolites, nuclear magnetic resonance spectroscopy, spectral analysis, Corsica
NMR chemical profiling of a Laurenciella sp. using a computerized method developed in our laboratory resulted in the identification of five new compounds (1–5) and 17 known compounds, among which 3-(E)-laurenyne represented by far the most abundant metabolite. Compounds 1 to 5 were isolated and fully characterized by detailed spectroscopic analysis. The absolute configuration and structural features of compound 1 were determined by single-crystal X-ray diffraction analysis. Compounds 1 to 4 are 12-membered cyclic ether acetogenins that are present in solution as interconverting conformers exhibiting an (aR) configuration of the bromoallene unit together with an S configuration at C-4. Among these, compound 3 is the first obtusallene derivative with bromine substituents at both the C-7 and C-12 positions. Compound 5 is an acetogenin bearing a [5.5.1]bicyclotridecane ring system. A plausible biosynthetic route to 1–4 is proposed.