Total Synthesis and Structure Confirmation of ( E ) and ( Z )-Ocellenyne.

The ( E / Z )-ocellenynes are C 15 dibrominated Laurencia natural products whose structures have been subject to several reassignments on the basis of extensive NMR analysis, biosynthetic postulates, and DFT calculations. Herein, we report the synthesis of both ( E )- and ( Z )-ocellenyne, which, in combination with single crystal X-ray diffraction studies, allows their absolute configuration to be established and defines the configuration of the syn -12,13-dibromide as being ( S , S ) in keeping with their proposed biogenesis from the (6 S , 7 S )-laurediols.