Merrifield resin-supported N-heterocyclic carbene-silver complex appended with caffeine for Sonogashira cross-coupling reaction

A novel Merrifield resin-supported N-heterocyclic carbene (NHC)-silver(I) complex, utilizing caffeine as an environmentally friendly NHC precursor, has been synthesized by a multi-step approach. The confirmation of the formation of the complex was achieved through the utilization of a number of analytical methods, including Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), electron dispersive X-ray (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. The complex was efficiently used as a highly effective heterogeneous catalyst for the Sonogashira coupling reaction involving aryl halides and terminal alkynes. The complex was retrieved through a straightforward filtration technique, significantly simplifying the purification step and allowed successive reuse for multiple times with minimal loss in activity. © 2024 Elsevier B.V.