Thiazoline‐Iridium (III) Complexes and Immobilized Nanomaterials as Selective Catalysts in N‐Alkylation of Amines with Alcohols

In this research, a new series of thiazoline‐iridium (III) complexes (4–7) derived from cysteine were prepared and fully characterized by conventional methods. The molecular structure of complex 5 was also determined by single‐crystal X‐ray diffraction. These complexes were evaluated as catalysts for hydrogen‐borrowing reactions of amines with alcohols. In particular, complex 5 showed the best activity as catalyst. Various amines have been alkylated with alcohols affording moderate to good yield (33–99%). Moreover, the immobilized nanomaterials (M1,2) were fabricated by sonication process from the best catalyst 5 with the multi‐walled carbon nanotubes (MWCNTs) and graphene oxide (GO), respectively, and characterized by X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) spectroscopy, field emission scanning electron microscopy (FE‐SEM), energy dispersive X‐ray (EDX) spectroscopy, and inductively coupled plasma‐mass spectrometry (ICP‐MS). The M1,2 nanomaterials were also tested as catalysts in model catalytic reaction for N‐alkylation. The M1 nanomaterial showed significantly higher activity than the M2 nanomaterial. The M1 catalyst was recovered by filtration and reused for four catalytic cycles with high conversion (99%, 97%, 96%, and 86%). For the first time, thiazoline‐iridium (III) complexes, which can catalyze N‐alkylation of amines with alcohols, have been synthesized. The immobilized nanomaterials of the most active catalyst 5 were also prepared using GO (M1) and MWCNT (M2).