Silylcarbonylation of styrenes catalyzed by iridium(I) siloxide complexes Original Research Article

This paper reports the study of iridium(I) catalyzed the incorporation of HSiMe2Ph and carbon monoxide to styrene and its derivatives. Comparative catalytic tests performed for the various iridium(I) precursors [{Ir(μ-X)(diene)}2] (where X = OMe, OAc, OSiMe3; diene = 1,5-cyclooctadiene (cod), tetrafluorobenzobarrelene (tfb)) and [Ir(CO)3(PCy3)(SiPh3)] showed that the binuclear complex [{Ir(μ-OSiMe3)(cod)}2] is the most efficient catalyst of the process studied and gives the main silylcarbonylation product, i.e. enol silyl ethers of acylsilanes (RCH2CHdouble bond; length as m-dashC(OSiMe2Ph)SiMe2Ph, where R = Ph, aryl) with relatively good yield. It enabled us to synthesize and isolate the exemplary acylsilane silyl enolates illustrating the potential application of binuclear siloxide iridium(I) complex in the synthesis of so useful in organic synthesis unsaturated organosilicon derivatives. Catalytic results as well as the detailed study of stoichiometric reaction of [{Ir(μ-OSiMe3)(cod)}2] and [Ir(CO)2(PCy3)(OSiMe3)] with the reaction substrates also under pressure of CO enabled us to propose a general catalytic scheme of the silylcarbonylation process including the formation of enol silyl ethers of acylsilanes as a main product accompanied by silyl enol ethers of aldehydes and products of styrene hydrosilylation.