Enantioselective Cyanosilylation of Alkynyl Ketones Catalyzed by Combined Systems Consisting of Chiral Ruthenium(II) Complex and Lithium Phenoxide

Abstract

Abstract Asymmetric cyanosilylation of alkynyl ketones with the catalyst systems consisting of amino acid/2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (BINAP)/ruthenium(II) complex and lithium phenoxide (Ru⋅Li cat.) was studied. The reaction was conducted in tert ‐butyl methyl ether (TBME) at −78 °C with a substrate‐to‐catalyst molar ratio (S/C) as high as 2000. A series of simple and functionalized ketones was converted into the alkynyl tertiary cyanohydrin derivatives in up to 99% ee. Appropriate selection of an amino‐acid ligand of the catalyst according to the substrate structure was crucially important to achieve high enantioselectivity and a wide scope of substrates. Transformation of the chiral cyanohydrin product into a functionalized lactone was also examined. magnified image