Asymmetric α-Hydroxylation of β-Indanone Esters and β-Indanone Amides Catalyzed by C-2′ Substituted Cinchona Alkaloid Derivatives
The highly catalytic 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 99% yield and 98% ee.
Stereoselective glycosylation of 2-nitrogalactals catalyzed by a bifunctional organocatalyst
The use of a bifunctional cinchona/thiourea organocatalyst for the direct and α-stereoselective glycosylation of 2-nitrogalactals is demonstrated for the first time. The conditions are mild, practical, and applicable to a wide range of glycoside acceptors with products being isolated in good to excellent yields. The method is exemplified in the synthesis of mucin type Core 6 and 7 glycopeptides.
Medina, Sandra,Harper, Matthew J.,Balmond, Edward I.,Miranda, Silvia,Crisenza, Giacomo E. M.,Coe, Diane M.,McGarrigle, Eoghan M.,Galan, M. Carmen
p. 4222 - 4225
(2016/09/09)
A new class of urea-substituted cinchona alkaloids promote highly enantioselective nitroaldol reactions of trifluoromethylketones
The first class of bifunctional cinchona-alkaloid catalysts incorporating a urea moiety at C-5′ has been developed. These materials catalyze the efficient and highly enantioselective 1,2-addition of nitromethane to trifluoromethylketones to form synthetically pliable products incorporating a quaternary stereocenter. Excellent product yields and levels of enantiomeric excess are possible, and the optimum catalyst structure is capable of promoting the Henry reaction involving alkyl trifluoromethylketones with unprecedented enantioselectivity.
Palacio, Carole,Connon, Stephen J.
supporting information; experimental part
p. 1298 - 1301
(2011/05/03)
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