As demonstrated by
Laszlo Kürti′s lab, the sterically hindered di-isopropyl keto malonate and its hydrate (
902764) are excellent
N-umpolung reagents for both aliphatic and aromatic primary amines via a simple condensation reaction. The steric hindrance in ester moiety allows the preparation of the corresponding iminomalonates in high yield and lends these imines sufficient hydrolytic stability during the purification process. The
N-alkyl as well as
N-aryl iminomalonates act as singly N-electrophilic reagents towards strong
C-nucleophiles such as alkyl- and arylmetals (e.g., Grignard reagents). Thus, unsymmetrical secondary amines may be readily prepared at low temperatures and in the absence of transition metal catalysts.
