Thermocontrolled benzylimine-benzaldimine rearrangement over Nafion-H catalysts for efficient entry into α-trifluoromethylbenzylamines

Nafion-H and Nafion SAC-13 are efficient solid Brønsted acid catalysts for the preparation of trifluoromethyl ketimines from benzylamines and trifluoromethylated ketones in high yields. A finely tuned benzylimine-benzaldimine rearrangement by facile 1,3-hydrogen shift has been achieved for the formation of fluorinated benzaldimines in high yields by careful optimization of reaction conditions including attempts under microwave conditions and a flow system. These α-trifluoromethylated benzaldimines are efficient precursors for pharmaceutically important α-trifluoromethylated benzylamines, accessed through their direct acid hydrolysis.