(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.