Synthesis of Amines by Nucleophilic 1،2-Addition of Organo Boron Reagents to the C-N Double Bond of Aldimines

Chiral amines are essential precursor to preparation of pharmaceuticals and natural products. Hence, the methods for synthesis of these compounds have been considerable interest. Among methods for the synthesis of amines, the catalytic addition of dialkalzinc reactants on the imines and catalytic ethylation of imines by using different catalysts has been reported. Wei-Ming Huang and Biing-Jiun Uang used amino alcohol as ligands for the addition of dialkylzinc to imines[1]. Methylation of imines reported by Tamioka and colleagues using dimethylzinc reagent in the presence of amidophosphin-copper catalysts [2]. Hayashi and co-workers reported the first example of methylation of imines by using trimethylboroxine in the presence of rhodium catalyst[3]. In this project, we tried to prepare methyl amines by addition of methylboronic acid to aromatic aldimines in the presence of phosphine ligands and various copper salts (Scheme 1). The desired products were produced in good yield and were characterized by IR, 1H NMR and 13C NMR.