title: Organocatalyzed enantioselective aldol reaction of 1H-pyrrole-2,3-diones.
abstract: The enantioselective cross aldol reaction of 1-benzyl 4,5-dioxo-2-aryl-4,5-dihydro-1H-pyrrole-3-carboxylates and ketones was studied with proline derivatives or cinchona alkaloid-derived primary amines as the catalysts for the first time. trans-4-Benzoyloxy-L-proline (15) was found to be the best catalyst for acyclic ketones. For cyclohexanone, the best results were achieved with 9-deoxy-9-epi-aminoquinine (18) as the catalyst in the presence of racemic 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (19) as the cocatalyst. Using these protocols, 3-alkyl-3-hydroxy-1H-pyrrol-2(3H)-one derivatives were obtained in excellent yields and good to high ee values (up to 94% ee).
authors.affiliation: Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249, USA.
authors.forename: Mayur
authors.initials: M
authors.lastname: Bhanushali
authors.forename: Cong-Gui
authors.initials: CG
authors.lastname: Zhao