Abstract: A brief introduction to metallacycle-mediated cross-coupling will be followed by a discussion focused on the use of alkenes and alkynes in these processes.  Building on basic observations regarding reactivity and selectivity, a collection of complex convergent annulation reactions will be described.  Finally, the value of these annulation reactions will be presented within a broad program aimed at establishing a unified asymmetric approach to the synthesis of diverse tetracyclic terpenoids.  This final portion of the lecture will introduce a number of stereoselective reactions that accomplish powerful bond forming reactions in complex settings typically encountered in natural product total synthesis.