Catalytic Enantioselective [3 + 2] Cycloaddition of α-Keto Ester Enolates and Nitrile Oxides
作者:Samuel L. Bartlett、Yoshihiro Sohtome、Daisuke Hashizume、Peter S. White、Miki Sawamura、Jeffrey S. Johnson、Mikiko Sodeoka
DOI:10.1021/jacs.7b03782
日期:2017.6.28
An enantioselective [3 + 2] cycloaddition reaction between nitrileoxides and transiently generated enolates of α-keto esters has been developed. The catalyst system was found to be compatible with in situ nitrile oxide-generation conditions. A versatile array of nitrileoxides and α-keto esters could participate in the cycloaddition, providing novel 5-hydroxy-2-isoxazolines in high chemical yield
Reaction design in asymmetric catalysis has traditionally been predicated on a structurally robust scaffold in both substrates and catalysts, to reduce the number of possible diastereomeric transition states. Herein, we present the stereochemical dynamics in the Ni(II)-catalyzed diastereoconvergent (3 + 2) cycloadditions of isomerizable nitrile-conjugated nitrones with α-ketoesterenolates. Even in
Acetyl cyanide adds to alkyl benzoylformates and to 2-oxoalkanoates to yield enantioenriched acylated cyanohydrins in one step in the presence of a catalytic amount of a chiral base. The reaction i ...
When activated with Takemoto’scatalyst, 1,2‐keto esters constitute versatile nucleophiles in the Michaeladdition reaction with nitroalkenes affording synthetically valuable, optically active anti‐adducts in very good yields and high enantiomeric excesses.
Facile Synthesis of Chiral Spirooxindole-Based Isotetronic Acids and 5-1<i>H</i>-Pyrrol-2-ones through Cascade Reactions with Bifunctional Organocatalysts
作者:Wengang Guo、Xu Wang、Boyu Zhang、Shuai Shen、Xin Zhou、Peng Wang、Yan Liu、Can Li
DOI:10.1002/chem.201402945
日期:2014.7.7
organocatalyzed asymmetric cascade reactions have been developed for the facile synthesis of chiral spirooxindole‐based isotetronic acids and 5‐1H‐pyrrol‐2‐ones.The asymmetric 1,2‐addition reactions of α‐ketoesters to isatins and imines by using an acid–base bifunctional 6′‐OH cinchona alkaloid catalyst, followed by cyclization and enolization of the resulting adducts, gave chiral spiroisotetronic acids and 5‐1H‐pyrrol‐2‐ones