Structures of some botryococcenes: branched hydrocarbons from the b-race of the green alga Botryococcus braunii

Nine branched hydrocarbons of the botryococcene type (C_nH_2n-10 30 ? n ? 37) have been isolated from the green alga Botryococcus braunii. Hydrocarbon mixtures were recovered from wild algae collected in fresh water lakes or from the same strains growing in laboratory; they were further separated by reversed-phase, and in some cases by normal phase, HPLC. From chemical investigations, GC/MS analyses, ¹H and ¹³C NMR spectroscopy, the structures of four new botryococcenes (one C₃₃H₅₆, two C₃₄H₅₈ and one C₃₇H₆₄) were elucidated.