trans-4-hydroxy-L-proline hydrazide-trifluoroacetic acid as highly stereoselective organocatalyst for the asymmetric direct aldol reaction of cyclohexanone

摘要

Protonated A,-benzyl-N '-L-prolyl-trans-4-hydroxy-L-proline hydrazide has been found to be superior to the L-proline hydrazide counterpart as the catalyst for the asymmetric aldol reaction of cyclohexanone and aromatic aldehydes, resulting in excellent diastereoselectivities (up to > 99:1 dr) and enantioselectivities (up to > 99% ee).