24475-92-1Relevant academic research and scientific papers
Enantioselective Cyanosilylation of Alkynyl Ketones Catalyzed by Combined Systems Consisting of Chiral Ruthenium(II) Complex and Lithium Phenoxide
Ohkuma, Takeshi,Kurono, Nobuhito,Sakaguchi, Yusuke,Yamauchi, Kohei,Yurino, Taiga
, p. 1517 - 1522 (2018)
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. (Figure presented.).
Catalytic asymmetric cyanosilylation of ketones with chiral Lewis base
Tian, Shi-Kai,Hong, Ran,Deng, Li
, p. 9900 - 9901 (2007/10/03)
The development of broadly applicable and practical catalytic approaches for the enantioselective creation of quaternary stereocenters remains a highly desirable yet challenging goal. In this Communication, we describe a highly enantioselective cyanosilylation of acetal ketones (α,α-dialkoxy ketones) catalyzed by modified cinchona alkaloids. This reaction is the first highly enantioselective cyanosilylation of ketones catalyzed by an organic chiral Lewis base and is found to be highly efficient with acetal ketones bearing a broad range of alkyl, aryl, alkenyl, and alkynyl substituents. This new catalytic asymmetric reaction, coupled with the versatility of the acetal functionality, provides a broadly useful synthetic method for chiral building blocks bearing quaternary stereocenters. Acetal ketones, readily accessible but previously unexplored in asymmetric synthesis, demonstrate unusual reactivity and selectivity toward the nucleophilic cyanosilylation, thereby suggesting that they may be interesting substrates for other catalytic enantioselective reactions. Copyright
