(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 PhMe2SiBpin 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.