N'-dioxide-Sc(III) complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active ε- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratoryaptitude, were
An aqueous chemoenzymatic cascade reaction combining Pd-catalyzed C–C formation and enzymatic CC asymmetric hydrogenation (AH) was developed for enantioselective synthesis of tertiary α-aryl cycloketones in good yields and excellent enantioselectivities. The stereopreference of the enzyme in AH of α-aryl cyclohexenones was studied. An enantiocomplementary enzyme was obtained by site-directed mutation
A Brønsted Acid Catalyst for the Enantioselective Protonation Reaction
作者:Cheol Hong Cheon、Hisashi Yamamoto
DOI:10.1021/ja8041542
日期:2008.7.1
A highly reactive and robust chiral Brønstedacidcatalyst, chiral N-triflyl thiophosphoramide, was developed. The first metal-free Brønstedacid catalyzed enantioselective protonation reaction of silyl enol ethers was demonstrated using this chiral Brønstedacidcatalyst. The catalyst loading could be reduced to 0.05 mol % without any deleterious effect on the enantioselectivity.
Development of a new Lewis base-tolerant chiral LBA and its application to catalytic asymmetric protonation reaction
作者:Cheol Hong Cheon、Tatsushi Imahori、Hisashi Yamamoto
DOI:10.1039/c0cc02492a
日期:——
A new Lewis base-tolerant LBA (LewisAcidAssistedBronstedAcid) derived from La(OTf)(3) and (S)-HOP has been developed as a new chiralBronstedacid. This acid has been successfully applied as a catalyst to asymmetric protonation reactions of silylenolethers of 2-substituted cyclic ketones.
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