Enantioselective Mannich Reaction of Malonates with N-tert-Butoxycarbonyl Imines

Karimi et al. have reported the enantioselective Mannich reaction of malonates with N-tert-butoxycarbonyl imines. According to their results, this enantioselective reaction successfully proceeds at room temperature by using Yb(OTf)₃ catalyst and (R,R)-2,6-bis(4-isopropyl-2-oxazolin-2-yl)pyridine as a chiral ligand. The corresponding β-aminocarbonyl compounds are obtained in high yields. After this reaction, the formed products can be available for chain elongation reactions due to remaining active methine moieties and subsequent decarbonations affording β-amino acids. Thus, it is expected that this synthetic method can be applied to the synthesis of various chiral building blocks.