Synthesis of trifluoromethyl-imines by solid acid/superacid catalyzed microwave assisted approach

A new solid acid/superacid catalyzed microwave assisted synthesis of trifluoromethyl-imines is described. Various alpha,alpha,alpha-trifluoromethylketones react readily with primary amines to produce the corresponding imines. Two different strategies have been employed; one is the application of microwave irradiation coupled with solvent-free solid acid catalysis. The other method, for highly deactivated substrates includes the use of a pressure vessel at 175 degrees C temperature, with solid superacid catalysis. Using the solid acid K-10 montmorillonite or the superacidic perfluorinated resinsulfonic acid Nafion-H, a wide variety of trifluoromethylated imines have been synthesized using the above methods. The products have been isolated in good to excellent yields and high selectivities. This new environmentally friendly synthetic methodology provides significantly higher yields than traditional methods during relatively short reaction times for the preparation of the target compounds. (c) 2007 Elsevier B.V. All rights reserved.