An activated carboxylic acid derivative of formula 5, for example an acid chloride, wherein Q is chloro, and wherein L is a leaving group such as a halide, can be reacted with an imine of formula 3 in the presence of a base such as a trialkylamine (e.g., triethylamine or tri-n-butylamine) at room temperature or elevated temperature in an inert solvent such as CH2 Cl2 or toluene.