Mannich reaction of secondary amines,aldehydes and alkynes in water using Cu/C nanoparticles as a heterogeneous catalyst

The use of 2 mol% of Cu/C nanoparticles, as an easily accessible and inexpensive heterogeneous catalyst, promoted a one-pot three-component condensation of an amine, aldehyde, and an alkyne in water to produce the corresponding propargylamine in good to high yields. This method was proved to be applicable to a wide range of substrates and is especially practical for the synthesis of new azacrown ether derivatives. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for at least ten times with almost consistent activity.