Enantioselective direct aldol reaction of α-keto esters catalyzed by (Sa)-binam-D-prolinamide under quasi solvent-free conditions

(Sa)-Binam-D-prolinamide (20 mol%), instead of (Sa)-binam-L-prolinamide, in combination with chloroacetic acid (100 mol%) is an efficient organocatalyst for the direct aldol reaction between α-keto esters as electrophiles and alkyl and α-functionalised ketones, under quasi solvent-free conditions, providing access to highly functionalised chiral quaternary γ-keto α-hydroxyesters with up to 92% ee.

This research was supported by the Ministerio de Ciencia e Innovación (MICINN: Projects CTQ2007-62771/BQU, CTQ2010-20387, and Consolider Ingenio2010 CSD2007-00006,), FEDER, the Generalitat Valenciana (Project PROMETEO/2009/039), and the EU (ORCA action CM0905). A.B.-C. thanks the Spanish MICINN for a predoctoral fellowship (FPU AP2009-3601).