Direct and Transfer Hydrosilylation Reactions Catalyzed by Fully or Partially Fluorinated Triarylboranes: A Systematic Study

The present survey serves several purposes. Selected electron-deficient boron Lewis acids catalyze the release of hydrosilanes from cyclohexa-2,5-dien-1-yl-substituted silanes. The two-step process consists of a hydride abstraction to generate a silicon-stabilized Wheland complex and capture of the arene-stabilized silicon cation by the borohydride formed in the previous step. The same boron catalyst will then activate the Si–H bond for the reaction with representative π- and σ-donating substrates, alkenes/alkynes and ketones/ketimines, respectively. The net transformation is a transfer hydrosilylation, and the effect that the substitution pattern of the cyclohexa-1,4-diene core and the subsituents at the silicon atom exert on these hydrosilane surrogates is systematically investigated. The results are compared with those obtained employing the hydrosilane directly. Another part of this comprehensive analysis is dedicated to the comparison of literature-known fully or partially fluorinated triarylboranes ...