Natural phosphate and potassium fluoride doped natural phosphate: efficient catalysts for the construction of a carbon–nitrogen bond

The application of natural phosphates doped with potassium fluoride as heterogeneous catalysts for the Michael addition of aromatic and aliphatic amines to α,β-unsaturated carbonyl compounds is presented. The natural phosphate catalyst can be regenerated and reused without loss of activity, which makes it an attractive alternative to homogeneous basic reagents. Doping natural phosphate with potassium fluoride significantly enhances the rate and yield of the reaction.