Efficient multicomponent synthesis of propargylamines catalyzed by Cu(I) complexes encompassing hydrazone ligands under solvent-free condition

A series of copper(I) complexes with hydrazone ligands of the type [Cu(PPh3)(2)(L)] (1-3) were synthesized by the reacting [Cu(PPh3)(2)(CH3COO)] with hydrazone ligands (L1-3) [L-1 = 2-(oxoacenaphthylen-1, 2-ylidene)benzohydrazone (BHy-BIAN), L-2 = 2-(oxoacenaphthylen-1, 2-ylidene)thiophene-2-carbohydrazone (FHy-BIAN), and L3 = 2-(oxoacenaphthylen-1,2-ylidene)isonicotinohydrazone (NHy-BIAN). The formation of synthesized complexes were characterized by micro analyses and spectral (IR, UV-Vis, H-1 & C-13 NMR, ESI-mass and single crystal XRD) studies. Specifically, the solid state structural study demonstrates distorted tetrahedral geometry of donor atoms around copper atom. The synthesized copper complexes were utilized as reusable homogeneous catalysts in A(3) coupling reactions involving aldehydes, amines and phenyl acetylene for the synthesis of propargylamines under solvent-free conditions. Particularly, complex 2 has been found to be highly efficient in the synthesis of propargylamines. Many novel compounds have been synthesized based on A(3) coupling reaction and the formation of new compounds was confirmed by TLC as well as H-1 and C-13 NMR spectroscopy.