DEGRADATION AND ABSOLUTE CONFIGURATIONAL ASSIGNMENT TO C-34-BOTRYOCOCCENE

C34-Botryococcene, the major hydrocarbon constituent of the B race of Botryoeoccus braunii, was degraded by ozonolysis of its dihydro derivative followed by Baeyer-Villiger oxidation to gamma-valerolactone, 2,5-dimethylhexanolactone, and 2-ethyl-2,5-dimethylhexanolactone. These three lactones were correlated with enantiomerically pure, synthesized materials using a progressive induced chemical shift technique with the chiral shift reagent Eu(hfc)3. The lactones were found to possess 4S, 2R,5S, and 2R,5S configurations respectively, thereby specifying a 3S,7S,10R,13S,16S,20S configuration for C34-botryococcene. A biogenesis for botryococcene from 1R,2R,3R presqualene diphosphate is proposed to account for the observed 10R,13S configuration.