NITRILIUM SALTS - A NEW METHOD FOR SYNTHESIS OF SECONDARY AMINES

A new method for the synthesis of secondary amines is described involving the sodium borohydride reduction of imino esters prepared from nitrilium salts. This conversion of nitriles into secondary amines proceeds in high yield and has been applied to a variety of compounds. The nitrilium salts are easily prepared from nitriles and dialkoxycarbonium fluoroborates (5), which are readily available from the corresponding ortho esters. Although most of the compounds examined gave the corresponding secondary amines as exclusive products, alkylation with di-n-propoxycarbonium fluoroborate (5c) gave the rearranged isopropylamine as the major product. The mechanism of the over-all reaction is discussed in light of intermediates observed, and a mechanism for the rearrangement is suggested. © 1969, American Chemical Society. All rights reserved.