Highly Efficient Single A3-Coupling (Aldehyde-Amine-Alkyne) Reaction Catalyzed by Air Stable Silver-(N-Heterocyclic Carbene) Complexes: Synthesis and Characterization

The interaction of N,N-disubstituted benzimidazolium salts 2a–e with Ag2O formed new silver-(N-heterocyclic carbene) complexes 3a–e. Structural characterization of silver-(N-heterocyclic carbene) complexes was conducted by using NMR, FT-IR and elemental analysis. Preliminary catalytic studies using all the silver complexes 3a–e were performed on three-component coupling reaction of a series of aldehydes with alkynes and amines was demonstrated. Most of these reactions led to formation of the expected propargylamines in good conversions using low amounts catalyst and obviating both the use of purified reagents as employ of a glovebox. Complexes 3a and 3c exhibited good catalytic activities under neat conditions. The silver complexes 3a–e showed luminescence properties in CH3CN at room temperature.