ABSTRACT
Our recent contributions in the development of alkyne X-boration and hydrofunctionalization reactions that are enabled by 1,4-azaborine-biaryl phosphine (Senphos)-supported Pd catalysts and B(C6F5)3 are described. Specifically, the site- and stereoselective hydroboration, carboration, hydroalkylation, hydroalkynylation, and hydrothiolation of 1,3-enynes will be discussed along with an analysis of possible reaction mechanisms underlying these reactions. Experimental mechanistic data are corroborated by DFT calculations. An outer-sphere oxidative addition reaction where a Pd(0)/Senphos and an electrophile cooperatively activate the 1,3-enyne substrate has emerged as a general mechanism to furnish a Pd-π-allyl species that can engage in subsequent bond forming reactions. However, differences in catalyst resting states and the rate-limiting transition states are observed.
