Switching Amine Oxidation from Imines to Nitriles by Carbon-Hydrogen Bond Activation via Strong Base Modified Strategy

Precisely controlling the product selectivity from the complex reaction is always an attractive topic in the catalysis field. In this paper, the Ru/strong base junction formed by the redox strategy was demonstrated as an efficient catalyst to switch the selectivity in aerobic oxidation of benzylamines. The zirconia-supported ruthenium (Ru-ZrO2) catalyst could catalyze benzylamine oxidation coupling to imines; however, the potassium oxide strong base modified zirconia-supported ruthenium (Ru-K-ZrO2) catalyst could catalyze benzylamine oxidation dehydrogenation to nitriles. Insight into the mechanism showed that the base modified catalyst had excellent dehydrogenation ability which was assisted by the C-H bond activation and changed the reaction pathway. The strong base modified strategy may provide a new approach for controlling the performance of heterogeneous catalysts and product selectivity.