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

Abstract

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%).

Borrowing Hydrogen Amination Reactions: A Complex Analysis of Trends and Correlations of the Various Reaction Parameters

“…The 2-phenyldihydrothiazolylmethyl alcohol-based Ir catalyst ( Ir-M-6 ) (0.5 mol %) showed moderate activity, but high selectivity in the aniline alkylation by benzyl alcohol at 110 °C in toluene, in the presence of tBuOK. The yield of N- benzylaniline was 65% (TON 130) . (Scheme , Table ).…”

“…A tabular comparison of the reaction conditions of the target process is provided in the SI (Table S8). The literature cited includes refs , , , , , − , , − , , , − , , , , , , , − , , , , − , , − , , , ,, − , , − , − , − , ,, , , , , , , , , , , − , , , and − . At the end of this block, diagrams are presented, which show the correlations between bases and temperatures (Figure ), and between bases and metal-based catalysts (Figure ) used in this process.…”

“…A tabular comparison of the reaction conditions of the target process for different reaction types (Figure ) is provided in the SI (Table S9). The cited literature includes refs − , − , − , − , − , − , − , − , − …”

“…A tabular comparison of the reaction conditions for different reaction types (Figure ) of the target process is provided in SI (Table S10). The literature cited included refs , , , , , , , , , , − , − , , , − , , , − , , , , − , , , , , − , , , , , ,,, , , , − , , , , , , , , , , , , , , − , , − …”

“…The yield of N-benzylaniline was 65% (TON 130). 44 (Scheme 22, Table 2). The use of 1 mol % Ir-M-6 at 110 °C allowed one to increase the target amine yield to 96% (TON = 96).…”