PREPARATION OF SECONDARY-AMINES BY REDUCTIVE AMINATION WITH METALLIC MAGNESIUM

A novel and efficient method for the preparation of secondary amines b y reductive amination of carbonyl compounds with primary amines has be en developed, The reduction, effected with metallic magnesium in metha nol, utilizing triethylamine-acetic acid as a buffer, gave pure second ary amines, mostly in good yields (65-80%). No formation of tertiary a mines or alcohols was observed. Use of ammonium acetate as an amino co mponent gave primary amines in modest yields (ca. 50%), together with variable amounts of secondary amines. Enamines failed to undergo reduc tion. The method is inexpensive, relatively rapid, operationally simpl e and suitable for large-scale preparations, In addition, a simple met hod for separation of primary amines from secondary ones has been deve loped.