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.
Arene CHO Hydrogen Bonding: A Stereocontrolling Tool in Palladium-Catalyzed Arylation and Vinylation of Ketones
作者:Zhiyan Huang、Li Hui Lim、Zuliang Chen、Yongxin Li、Feng Zhou、Haibin Su、Jianrong Steve Zhou
DOI:10.1002/anie.201300621
日期:2013.4.26
Weak is powerful: For the arylation of tin enolates, the palladium catalyst engages in weak CHOhydrogen bonds to control stereoselectivity (see scheme). Similar catalysts capable of NHOhydrogenbonding also works well.
Reaction of lithium enolates of 2-arylcycloalkanones 2 with (R,R)-aminoborane 1, prepared from (1R,2R)-1,2-diaminocyclohexane 4 and PhBCl2, gives the corresponding optically active ketones 3 with up to 93% ee; this is the first example of enantioselective protonation using a metal-containing chiral proton source.
Enantioselective Protonation of Silyl Enol Ethers Catalyzed by a Chiral Pentacarboxycyclopentadiene-Based Brønsted Acid
作者:Jun Li、Shaoyu An、Chao Yuan、Pingfan Li
DOI:10.1055/s-0037-1611849
日期:2019.7
The enantioselectiveprotonation of silyl enol ethers was realized in the presence of a pentacarboxycyclopenta-1,3-diene-based chiral Bronsted acid catalyst with water as an achiral proton source to give the corresponding α-aryl ketones in good yields and up to 75% ee.
Chiral Sulfinamide/Achiral Sulfonic Acid Cocatalyzed Enantioselective Protonation of Enol Silanes
作者:Elizabeth M. Beck、Alan M. Hyde、Eric N. Jacobsen
DOI:10.1021/ol201608a
日期:2011.8.19
The application of chiral sulfinamides and achiral sulfonic acids as a cocatalyst system for enantioselective protonation reactions is described. Structurally simple, easily accessible sulfinamides were found to Induce moderate-to-high ee's in the formation of 2-aryl-substituted cycloalkanones from the corresponding trimethylsilyl enol ethers.