asymmetric α‐hydroxylation of β‐indanone esters and β‐indanone amides using peroxide as the oxidant was realized with a new C‐2′ substituted Cinchona alkaloid derivatives. The two enantiomers of α‐hydroxy‐β‐indanone esters could be obtained by simply changing the oxidant. This protocol allows a convenient access to the corresponding α‐hydroxy‐β‐indanone esters and α‐hydroxy‐β‐indanone amides with up to
Bifunctional Ammonium Salt Catalyzed Asymmetric α-Hydroxylation of β-Ketoesters by Simultaneous Resolution of Oxaziridines
作者:Johanna Novacek、Joseph A. Izzo、Mathew J. Vetticatt、Mario Waser
DOI:10.1002/chem.201604153
日期:2016.11.21
Chiral bifunctional urea‐containing ammonium salts were found to be very efficient catalysts for asymmetric α‐hydroxylation reactions of β‐ketoesters with oxaziridines under base‐free conditions. The reaction is accompanied by a simultaneous kinetic resolution of the oxaziridine and a plausible and so far unprecedented bifunctional transition‐state model has been obtained by means of DFT calculations
Development of C-6′-modified quinine-derived phase-transfer catalysts and their application in the enantioselective α-hydroxylation of β-dicarbonyl compounds
We have developed C-6'-modified quinine quaternary ammonium salts as phase transfer catalysts for alpha-hydroxylation of beta-dicarbonyl compounds. The quinine quaternary ammonium salts, which was modified at C-6' and the N atom, had good activity for alpha-hydroxylation of B-dicarbonyl compounds. By using 5 mol % of 6-hydroxyl-N-(4'-fluoro-2'-trifluoromethyl)quinine quaternary ammonium salt as the organocatalyst, cumene hydroperoxide as the oxidant, toluene as the solvent, and 50% K2HPO4 as the aqueous alkali at room, temperature, the yield and enantioselectivity of the alpha-hydroxylation of beta-keto esters were 95% and 88%, respectively. This catalytic system was also applicable for beta-keto amides (92% yield and 76% ee). (C) 2016 Elsevier Ltd. All rights reserved.