Preparation of Ag2S Nanoparticles and using as Catalyst for the A3-coupling (Aldehyde-Amine-Alkyne) Reaction

Microwave assisted facile one-step approach was adopted to prepare mono-dispersed silver sulfide nanoparticles. The structures of the synthesized Ag2S nanoparticles were confirmed by Fourier-transform infrared spectroscopy (FT-IR), diffuse reflectance UV-vis spectroscopy (DRS), X-ray diffractometer (XRD), energy dispersive X-ray analysis (EDX) and transmission electron microscope (TEM). The prepared Ag2S nanoparticles (NPs) were successfully used as a heterogeneous catalyst in the one-pot three-component coupling reaction of aldehydes, amines and alkynes (A3-coupling) toward propargylamines. In this protocol, both aromatic and aliphatic aldehydes and secondary amines were reacted with terminal alkynes in the presence of Ag2S NPs at low catalytic loading (0.5 mol %) that led to the rapid and efficient formation of propargylamines with good to excellent yields. The A3-coupling reaction occurred effectively at 80 oC under solvent-free conditions. The catalyst is easy to prepare and is perfectly stable under the reaction conditions. Also, the Ag2S NPs catalyst can be easily recovered and reused several times and exhibited higher catalytic activity than other some commercially catalysts.