A New Class of Urea-Substituted Cinchona Alkaloids Promote Highly Enantioselective Nitroaldol reactions of Trifluoromethylketones
作者:Carole Palacio、Stephen J. Connon
DOI:10.1021/ol103089j
日期:2011.3.18
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
Bianthryl-based organocatalysts for the asymmetric Henry reaction of fluoroketones
作者:Jan Otevrel、David Svestka、Pavel Bobal
DOI:10.1039/c9ob00884e
日期:——
catalytic system based on bianthrylbis(thiourea) for the asymmetric Henry reaction of fluoroketones and nitroalkanes that resulted from the screening of a library containing 31 chiral non-racemic organocatalysts. The corresponding adducts were isolated in up to 6 times shorter reaction time in comparison with the previously published organocatalysts. High levels of stereocontrol have been generally observed