Arylation and alkenylation of aromatic aldehydes with silanediols is shown to proceed by use of a catalytic amount of rhodium complex. Treatment of ethyl(4-methoxyphenyl)silanediol with benzaldehyde in the presence of 3 mol% of [Rh(OH)(cod)]2 affords 4-methoxyphenyl(phenyl)methanol in 59% yield after stirring at 70 °C for 24 hours. On the other hand, diarylketone was also obtained at elevated temperature via β-hydride elimination from intermediary rhodium alkoxide.
Aryl- and alkenylsilanediols, which possess two hydroxy groups on the silicon atom, undergo the rhodium-catalyzed addition of an organic group on silicon to internal alkynes. Treatment of several internal alkynes with aryl- or alkenylsilanediols in the presence of 3 mol% of [Rh(OH)(cod)]2 affords the hydroarylated or hydroalkenylated products in good yields. A crucial role of the hydroxy group of silanediol for the catalytic reaction is also discussed with the related aryltin reagent.