Highly enantioselective immobilized prolinamide-catalyzed aldol reactions in continuous-flow systems: effect of water on the catalyst lifetime and application in the synthesis of a chiral fenpentadiol analogue
Catalytic enantioselective aldol reactions of trifluoroacetophenones with ketones under continuous-flow conditions have been developed for the first time by using polystyrene-supported prolinamides. The robustness of the flow system was demonstrated by the continuous synthesis of a variety of trifluoromethyl carbinols in high yields with high enantioselectivities. The unusually long lifetimes (>195 h) of this flow process were achieved by facilitating H2O-promoted hydrolysis of iminium intermediates on the polymer. Mechanistic study revealed a racemization phenomenon and an inherent reversible property of the aldol reactions in a conventional batch system, both of which were suppressed under continuous-flow conditions. The synthetic utility of this flow process was further demonstrated by the formal continuous-flow synthesis of a chiral fenpentadiol analogue.
Fine-tuning the structures of chiral diamine ligands in the catalytic asymmetric aldol reactions of trifluoromethyl aromatic ketones with linear aliphatic ketones
In this work, we thoroughly investigated the effect of structural differentiation of a series of N,N-disubstituted chiral diamine ligands on the catalytic asymmetric aldol reactions between trifluoromethyl ketones and linear aliphatic ketones for the cons
Construction of tertiary alcohols bearing perfluoroalkyl chains catalyzed by prolinamide-thioureas
A systematic study to evaluate the ability of various organocatalysts to catalyze the aldol reaction between acetone and 2,2,2-trifluoromethyl-1- phenylethanone was undertaken. Benchmark organocatalysts failed to catalyzethis reaction. However, a prolinam
Kokotos, Christoforos G.
experimental part
p. 1131 - 1135
(2012/03/12)
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