SILICA-SUPPORTED IRIDIUM-PHOSPHINE CATALYSTS FOR THE REACTION OF SILANES WITH ALCOHOLS

Article abstract of DOI:10.1016/S0022-328X(00)87097-7

Silica-supported iridium catalysts have been evaluated in the reactions of HSiR3 (R = Et, OEt) and Me3SiOnSiMe3 (PS1, n = 1; PS50, n <*> 50) with a wide variety of primary alcohols.Catalysts obtained by reaction of IrCl(CO)2 with silica are rapidly deactivated in a manner similar to the related homogeneous systems.More active catalysts are obtained by treating the silica first with Ph2P(CH2)2Si(OEt)3 and then with 2.The order of reactivity of the silanes is PS50 <*> HSi(OEt)3 > HSiEt3 <*> PS1, and that of the alcohols reflects principally the bulk of the organic group.Kinetic analysis indicates two pathways involving iridium bound to the phosphine and directly to the silica.The 29Si<1H> NMR spectra of PS50 and the product of its reaction with Ph(CH2)2OH are reported.