Brønsted Acid-Catalyzed, Highly Enantioselective Addition of Enamides to In Situ<i>-</i>Generated<i>ortho</i>-Quinone Methides: A Domino Approach to Complex Acetamidotetrahydroxanthenes
作者:Satyajit Saha、Christoph Schneider
DOI:10.1002/chem.201406044
日期:2015.2.2
The highly enantioselective conjugate addition of enamides and enecarbamates to in situ‐generated ortho‐quinone methides, upon subsequent N,O‐acetalization, gives rise to acetamido‐substituted tetrahydroxanthenes with generally excellent enantio‐ and diastereoselectivities. A chiral BINOL‐based phosphoric acid catalyst controls the enantioselectivity of the carbon–carbon bond‐forming event. The products
Enantiomeric Separations of Chiral Sulfonic and Phosphoric Acids with Barium-Doped Cyclofructan Selectors via an Ion Interaction Mechanism
作者:Jonathan P. Smuts、Xin-Qi Hao、Zhaobin Han、Curran Parpia、Michael J. Krische、Daniel W. Armstrong
DOI:10.1021/ac403686a
日期:2014.1.21
(CF6)-based chiral stationary phases (CSPs) bind barium cations. As a result, the barium-complexed CSPs exhibit enantioselectivity toward 16 chiral phosphoric and sulfonic acids in the polar organic mode (e.g., methanol or ethanol mobile phase containing a bariumsalt additive). Retention is predominantly governed by a strong ionic interaction between the analyte and the complexed barium cation as well as hydrogen
Phosphate ligands in the gold(<scp>i</scp>)-catalysed activation of enynes
作者:Mihai Raducan、María Moreno、Christophe Bour、Antonio M. Echavarren
DOI:10.1039/c1cc15739f
日期:——
Gold(I) forms neutral complexes with binol phosphates that are unreactive in the catalytic cyclisation of enynes. Reaction in protic solvents or activation by silver(I) restores the catalytic activity.
Enantioselective counter-anions in photoredox catalysis: The asymmetric cation radical Diels-Alder reaction
作者:Peter D. Morse、Tien M. Nguyen、Cole L. Cruz、David A. Nicewicz
DOI:10.1016/j.tet.2018.03.052
日期:2018.6
comprised of an oxidizing pyrilium salt bearing a chiral N-triflyl phosphoramide anion. This class of chiral organic photoredox catalysts is able to catalyze the formation of cation radical-mediated Diels-Alder transformations in up to 75:25 e.r. in both intramolecular and intermolecular examples.
Synthesis of Novel Chiral Phosphoric Acid-Bearing Two Acidic Phenolic Hydroxyl Groups and its Catalytic Evaluation for Enantioselective Friedel-Crafts Alkylation of Indoles and Enones
A novel chiral phosphoric acid catalyst bearing two acidic phenolic hydroxyl groups was synthesized. Its catalytic activity as a chiral Brøsted acid has been examined in the enantioselective Friedel‐Crafts alkylation of indoles and enones as a model reaction. In comparison with the other chiral phosphoric acid catalysts, the reaction catalyzed by the novel chiral catalyst afforded the desired 3‐substituted