Selective catalytic hydrogenation in the presence of lanthanide tris-β-diketonates as “protecting” reagents

Abstract

The selectivity of > C<C double bonds catalytic hydrogenation increases considerably in the presence of some lanthanide tris-β-diketonates for unsaturated aldehydes and ketones possessing highly susceptible to reduction carbonyl group. It is a result of the selective co-ordination between the lanthanide complex added and the carbonyl group of a substrate. In most cases the complete protection of carbonyl groups is observed if the complex is added in equimolar amount to the substrate. A number of tris-β-diketonates have been tested; the complexes with flourinated ligands were demonstrated to ensure the highest selectivity of the hydrogenation. The correlation between the constants of equilibrium in reaction mixture and “protecting” activity of the complexes is discussed. A few examples demonstrate the practical utilization of the lanthanum tris-β-diketonates to the selective hydrogenation of unsaturated aldehydes and ketones.