Rhodium(I) complexes of β-diketonates and related ligands as hydrosilylation catalysts

The complexes (O---O)Rh(CH₂CH₂)₂ ((O---OH) = FcC(O)CH₂C(O)CH₃, PhC(O)CH₂C(O)CH₃, 1,2-(CH₃CO)(OH)C₆H₄, 3-benzoyl-(+)-camphor) are catalysts for the hydrosilylation of PhMeCO with Ph₂SiH₂. The optical yield from the reaction catalyzed by the camphor derivative is too low to measure. Only low optical yields (max 8.7% e.e.) are obtained from the same reaction by using similar in situ catalysts with ligands prepared from (+)-PhCH(Me)NH₂. Bases such as H⁻ and PhCH(Me)NH⁻ catalyze the hydrosilylation reaction in the absence of rhodium salts, but only low optical yields are obtained. Ph₂SiH₂ reacts with 2-cyclohexen-1-one under these conditions and the mode of reaction depends on the reaction conditions.