Differentiating allylic and vinylic leaving groups for Pd catalysis. The use of vinyl iodide to facilitate room temperature activation of a vinyl CX bond in the presence of allyl carbonate

Ionization of allylic, stabilized leaving groups by Pd catalysis is a very facile process at or below room temperature, whereas oxidative addition of many vinyl or aryl CX bonds requires heating. There are only a handful of examples in the literature where a vinyl leaving group can be activated in a competitive fashion in the presence of a suitable allylic one. In this report a series of polyfunctional olefin building blocks have been constructed that allow vinyl halides to be selectively and routinely activated in the presence of highly active allylic leaving groups. This differentiation is dependent solely on the bond strengths of the leaving groups involved and shows no temperature dependence to differentiate the two processes.