Ring-closing metathesis of allylsilanes/electrophilic desilylation to prepare exo-methylidenecycloalkanes. Short syntheses of teucladiol and poitediol.

A general strategy for the synthesis of exo-methylidenecycloalkanes, which are salient features of many terpenoid natural products, is presented. Ring-closing alkene metathesis of allylsilanes provides intermediates that can be protodesilylated with alkene transposition to afford the exocyclic alkene; alternatively, the reactivity of the cyclic allylsilane intermediate can be harnessed to introduce allylic functionality. These two modes of reactivity are showcased in short syntheses of the sesquiterpene natural products teucladiol and poitediol, respectively.