Imine Synthesis in Strictly Neutral Conditions

Abstract

Many methods are described for the synthesis of ketimines of cyclanones by direct reaction between an amine and the corresponding carbonyl derivative, but the efficiency of the process is largely dependent on the steric hindrance of the starting ketone. For instance, potassium hydroxide (1) can be used as a catalyst for the less hindered ketones (method A), azeotropic distillation with (method C) or without (method B) acid catalysis is to be prefered if the first way does not give the expected result (2,3) and for the most hindered ketones, reaction in the presence of titanium tetrachloride was claimed to lead to better results (method D (4)).