Efficient synthesis of E-1,2-bis(silyl)ethenes via ruthenium-catalyzed homocoupling of vinylsilanes carried out in ionic liquids
A series of ruthenium complexes (RuCl3 × 3H2O, [C5H5Ru(CH3CN)3]+[PF6]−, [RuCl2(PPh3)3], [RuHCl(CO)(PPh3)3], [RuHCl(CO)(PCy3)2]) immobilized in [bmim][Tf2N] were tested in homocoupling of vinylsilanes (H2CCHSi(OEt)3, H2CCHSi(OiPr)3, H2CCHSi(OSiMe3)3, H2CCHSiMe(OSiMe3)2, and H2CCHSiPh(OSiMe3)2) performed in a biphasic system. The highest catalytic activity and selectivity of homocoupling product was observed for [RuHCl(CO)(PCy3)2]. The complex [RuHCl(CO)(PCy3)2] immobilized in a variety ionic liquids ([bmim][PF6], [bmim][BF4], [bmim][Tf2N], [bmim][TfO], [bmim][HSO4], [bmim][Cl], [trimim][MeSO4], [NBu3Me][MeSO4], [PBu4][Cl], [bpy][PF6], [bpy][BF4], [bpy][Cl]) exhibits high catalytic activity in homocoupling of H2CCHSiMe2Ph, H2CCHSi(OEt)3 and H2CCHSiMe(OSiMe3)2 and enables high-yield stereoselective synthesis of the corresponding E-1,2-bis(silyl)ethenes. The immobilized complex can be easily recycled up to 12 times in the homocoupling of H2CCHSiMe2Ph and up to 10 times in the homocoupling of H2CCHSiMe(OSiMe3)2 without a significant drop in activity and selectivity. Results of a split test indicate that the source of catalytic activity is the catalyst immobilized in ionic liquid phase.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (154 K)Download as PowerPoint slideHighlights► Highly efficient and selective synthesis in biphasic system. ► Recyclability of the immobilized catalyst. ► Compatibility of ruthenium hydride to a variety of ionic liquids. ► Immobilization of catalyst in ionic liquid was demonstrated by a split test.
Journal: Applied Catalysis A: General - Volumes 445–446, 28 November 2012, Pages 261–268