Postulated biogenesis of WS9885B and progress toward an enantioselective synthesis

WS9885B promotes the assembly of microtubules in vitro and displays cytotoxicity as potent as paclitaxel against several cancer cell lines. In this Letter, we propose a biogenesis for this architecturally complex bacterial metabolite from a much simpler, polyunsaturated precursor. We also present significant progress toward a convergent, enantioselective synthesis of WS9885B, Our work features a chemoselective palladium-catalyzed cross coupling of two advanced building blocks and an uncommon Claisen-like cyclization.