Catalysis Letters, Vol.61, No.3-4, 143-149, 1999
Reductive transamination of methoxyacetone with benzylamine over Pd/SiO2 catalyst modified with anchored chiral compounds
Methoxyacetone was transaminated with benzylamine to methoxyisopropylamine over a Pd/SiO2 catalyst modified with L-alaninol or L-phenylalaninol covalently anchored to the surface of the support via an organo-silicon spacer group. In the first step of transamination a Schiff base was formed from the ketone and benzylamine, and then it was hydrogenated in the second step on the chirally modified Pd/SiO2 catalysts to an asymmetric secondary amine (N-benzyl-methoxyisopropylamine). In the third step the hydrogenolysis of the asymmetric secondary amine resulting in methoxyisopropylamine and toluene was carried out over a 10 wt% Pd/C catalyst. The highest enantiomeric excess of (S)-methoxyisopropylamine was observed in cyclohexane (ee = -20-21%) using anchored L-alaninol as a chiral modifier.
Keywords:enantioselective amination;reductive transamination;enantioselective hydrogenation;Schiff base;methoxyisopropylamine;chiral modifiers;methoxyacetone;palladium catalysts