Asymmetric Synthesis of Amines by Nucleophilic 1,2-Addition of Organo Boron Reagents on C-N Double Bond of Aldimines

Asymmetric synthesis of organic molecules such as amines are important in the pharmaceutical and agrochemical industries.1 The efficient methods for the asymmetric methylation of imines have been reported. The breakthrough first methyl addition to an achiral imine using copper catalysts was reported by Tomioka et al in 1990.2 Hoveyda et al. described a zirconium-catalyzed imine methylation using a peptide based chiral ligand to afford arylimines.3 Hayashi and co-workers reported the first example of a rhodium catalyzed methylation of imines.4 Herein, we tried to prepare methyl amines 3 by addition of methylboronic acid 2 to aromatic aldimines 1 in the presence of phosphine-cobalt catalysts (Scheme 1). The desired products were produced in good yields and were characterized by IR, 1H NMR and 13C NMR. The enantiomeric excess (ee) of chiral products is detected by polarimeter.

کلیدواژه ها:

Methylation reactions ، Phosphine ligands ، Cobalt catalysts