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.
The Skaggs Institute for Chemical Biology and the Departments of Chemistry and Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Nobuyuki
N
Mase
Fujie
F
Tanaka
Carlos F
CF
Barbas
D000143:Acids / Q000737:chemistry; D000588:Amines / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D013050:Spectrometry, Fluorescence / Q000379:methods*
D000143:Acids; D000588:Amines; D002244:Carbon