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.
The Silicon–Hydrogen Exchange Reaction: A Catalytic σ-Bond Metathesis Approach to the Enantioselective Synthesis of Enol Silanes
作者:Hui Zhou、Han Yong Bae、Markus Leutzsch、Jennifer L. Kennemur、Diane Bécart、Benjamin List
DOI:10.1021/jacs.0c06677
日期:2020.8.12
stoichiometric chiral reagents. We now describe a catalytic approach in which strongly acidic and confined imidodiphosphorimidates (IDPi) catalyze highly enantioselective interconversions of ketones and enol silanes. These “silicon–hydrogen exchange reactions” enable access to enantiopure enol silanes via tautomerizing σ-bond metatheses, either in a deprotosilylative desymmetrization of ketones with allyl
A triflic imide (Tf(2)NH) catalyzed isomerization of kinetically favourable silyl enol ethers into thermodynamically stable ones was developed. We also demonstrated a one-pot catalytic reaction consisting of (2 + 2) cycloaddition and isomerization. In the reaction sequence, Tf(2)NH catalyzes both of the reactions.
Enantioselective Protonation of Silyl Enol Ethers and Ketene Disilyl Acetals with Lewis Acid-Assisted Chiral Brønsted Acids: Reaction Scope and Mechanistic Insights
Enantioselectiveprotonation is a potent and efficient way to construct chiral carbons. Here we report details of the reaction usingLewisacid-assisted chiral Bronsted acids (chiral LBAs). The 1:1 coordinate complex of tin tetrachloride and optically active binaphthol ((R)- or (S)-BINOL) can directly protonate various silylenolethers and ketene disilyl acetals to give the corresponding α-aryl ketones
The Silicon–Hydrogen Exchange Reaction: Catalytic Kinetic Resolution of 2-Substituted Cyclic Ketones
作者:Benjamin List、Hui Zhou、Pinglu Zhang
DOI:10.1055/a-1670-5829
日期:2021.12
enantiopure enol silanes in a tautomerizing σ-bond metathesis, via deprotosilylation of ketones with allyl silanes as the silicon source. However, until today, this reaction has not been applied to racemic, 2-substituted, cyclic ketones. We show here that these important substrates readily undergo a highly enantioselective kinetic resolution furnishing the corresponding kinetically preferred enol silanes