Chiral Brønsted Acid from a Cationic Gold(I) Complex: Catalytic Enantioselective Protonation of Silyl Enol Ethers of Ketones
作者:Cheol Hong Cheon、Osamu Kanno、F. Dean Toste
DOI:10.1021/ja204331w
日期:2011.8.31
developed from a cationic gold(I) disphosphine complex in the presence of alcoholic solvent and applied to the enantioselective protonation reaction of silylenolethers of ketones. Various optically active cyclic ketones were obtained in excellent yields and high enantioselectivities, including cyclic ketones bearing aliphatic substrates at the α-position. Furthermore, the application of this Brønsted acid
A novel, catalytic enantioselective route to synthesize a variety of a-tertiary aryl ketones via a boron Lewis acid promoted formal insertion of aryldiazoalkane into the C-H bond of both aromatic and aliphatic aldehydes is described. In the presence of chiral (S)-oxazaborolidinium ion catalyst 1, the reaction proceeded in good yields (up to 94%) with excellent enantioselectivities (up to 99% ee).