(N-Heterocyclic Carbene)2-Pd(0)-Catalyzed Silaboration of Internal and Terminal Alkynes: Scope and Mechanistic Studies

Pd(ITMe)(2)(PhC CPh) acts as a highly reactive precatalyst in the silaboration of terminal and internal alkynes to yield a number of known and novel 1-silyl-2-boryl alkenes. Unprecedented mild reaction temperatures for terminal alkynes, short reaction times, and low catalytic loadings are reported. During mechanistic studies, cis-Pd(ITMe)(2)(SiMe2Ph)(Bpin) was directly synthesized by oxidative addition of PhMe(2)SiBpin to Pd(ITMe)(2)(PhC CPh). This represents a very rare example of a (silyl)(boryl)palladium complex. A plausible catalyst decomposition route was also examined.