Rapid Fluorescent Screening for Bifunctional Amine−Acid Catalysts:  Efficient Syntheses of Quaternary Carbon-Containing Aldols under Organocatalysis

reaction: see text Direct catalytic aldol reactions of alpha,alpha-dialkylaldehyde donors and arylaldehyde acceptors have been performed using pyrrolidine-acetic acid bifunctional catalysts. This general and practical amine-acid combination was identified by screening catalysts using a new fluorescent detection system for carbon-carbon bond formation. Using 0.05 equiv of pyrrolidine and 0.25 equiv of acetic acid as catalyst, we obtained alpha,alpha-dialkylaldol product in 96% yield after 2 h at ambient temperature. Proline was a poor catalyst of this reaction.