Siloxycarbenium Tetrakis[3,5-bis(trifluoromethyl)phenyl]borates and Their Role in Reactions of Ketones with Nucleophiles

The intermediacy of trialkylsiloxycarbenium ions was demonstrated by NMR spectroscopy during the reduction of ketones with hydrosilanes catalyzed by trityl tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. It is suggested that the non-nucleophilic nature of the counter anion plays an important part in the modification of the reaction courses.