7,11-cyclobotryococca-5,12,26-triene, a novel botryococcene-related hydrocarbon occurring in natural environments

With the unambiguous structural characterization of 7,11-cyclobotryococca-5 ,12,26-triene 1 by NMR, a novel C-30 botryococcene-related hydrocarbon skel eton bearing a midchain five-membered ring has been identified in organic-r ich sediments from Lake Cadagno (Switzerland), This compound may originate from the green alga Botryococcus braunii (race B) widespread in recent and past environments. Alternatively, it may also be a yet unreported lipid of green sulfur photosynthetic bacteria (Chlorobiaceae) or a microbial transfo rmation product of the farnesol produced by the latter.