Asymmetric Aldol Reaction of 3-Acetyl-2-chromen-2-ones and Isatins Catalyzed by a Bifunctional Quinidine Urea Catalyst.

The asymmetric aldol reaction of 3-acetyl-2-chromen-2-ones and isatins has been realized by using a bifunctional quinidine-derived urea as the catalyst. The corresponding 3-hydroxyoxindole derivatives containing a 2-chromen-2-one moiety were obtained in good yields and high enantioselectivities. When ()-ethyl 2-benzylideneacetoacetate was used as the substrate, a mixture of two diastereomers (both and ) was obtained due to the isomerization of the double bond under the reaction conditions.