Diastereodivergent synthesis of trisubstituted alkenes through protodeboronation of allylic boronic esters: application to the synthesis of the Californian red scale beetle pheromone.

E-allylic boronic esters undergo a highly diastereoselective protodeboronation with TBAF⋅3 H(2)O to give Z-trisubstituted alkenes. The selectivity can be switched to give predominantly the E-alkene instead by using KHF(2)/TsOH (see scheme). The utility of the methodology has been illustrated in a short synthesis of a component of the sex pheromone of the Californian red scale beetle.