BINAM-prolinamides as recoverable catalysts in the direct aldol condensation

Abstract

New BINAM-prolinamides were developed and tested as organocatalysts in the direct aldol condensation between aldehydes and several aliphatic ketones. C2-symmetrical (Sa)-BINAM-L-prolinamide gives the best enantioselectivities for this transformation, being recovered and reused after the reaction by simple extractive techniques. The reaction was performed in DMF/H2O at 0 °C to give the aldol products in up to 95% ee for acetone. For 2-butanone, the corresponding iso-regioisomers were regioselectively obtained in up to 96% ee working in DMF at rt. In the case of cyclohexanone, dr up to 10:1 in favour of the anti products, which were obtained in 90–93% ee, was achieved.