N-Alkylation andN-Methylation of Amines with Alcohols Catalyzed by Nitrile-Substituted NHC–Ir(III) and NHC–Ru(II) Complexes

Abstract

A series of nitrile-modified N-heterocyclic carbene (NHC) complexes of Ir(III) (2a−e) and Ru(II) (3a−d) have been prepared by transmetallation of [IrCp*Cl 2 ] 2 and [RuCl 2 (pcymene)] 2 forming an in situ NHC−Ag complex. The structures of all complexes were characterized by 1 H NMR, 13 C NMR, and Fourier transform infrared (FT-IR) spectroscopies. And the structures were clearly elucidated by performing X-ray diffraction studies on 2b, 3a, and 3c single crystals. The complexes of NHC− Ir(III) (2a−e) and NHC−Ru(II) (3a−d) were investigated in the N-alkylation reaction of aniline derivatives with benzyl alcohols to form N-benzyl amines and in the N-methylation reaction of aniline derivatives with methanol. Both reactions were performed in solvent-free media. The Ir(III) complexes (2a−e) were found to perform essentially better than similar Ru(II) complexes (3a−d) in the N-alkylation and N-methylation reactions. Among the Ir(III) complexes (2a−e), the best results were obtained with 2b. The catalytic mechanisms of both reactions were revealed by 1 H NMR study. Formation of Ir-hydride species was observed for both reactions. This new report provides useful information to evaluate the activity of complexes and the differences in sensitivity between the NHCs.

Construction of biomass-based amines via Ir-mediated N-alkylation: kinetic analysis

“…The resulting kinetic parameters were denoted as k″ (reaction rate constant), E″ a (activation energy) and A″ ( pre-exponential factor), so as to distinguish these from k′, E′ a and A′, respectively, for the cases in the absence of HCOONa. Under such conditions, eqn (34) (Scheme S3 †) is still valid for the calculation of the corresponding k″ 1 (eqn (40), Scheme S3 †), as shown in Fig. 10a (and Tables S14-17 in the ESI †).…”

“…Therefore, a plot of ln([2a] t 1 /[2a] t 2 ) against (t 2 − t 1 ) affords a line with the slope of k′ 1 (eqn (34), Scheme S3 †). Fig.…”

“…Typically, N-alkylation of tetrahydrofurfurylamine (1a, amine) using furfuryl alcohol (2a, alcohol) as an alkylating agent was investigated for the synthesis of 1-(2furanyl)-N-[(2-tetrahydrofuranyl)methyl]methanamine (5a, secondary amine) in this research study (Scheme 1c). Due to the excellent catalytic performance of Ir-based homogeneous catalysts in the previously reported N-alkylation reaction (Table S1, ESI †), [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Ir complexes immobilized in N,N-bidentate ligandfunctionalized covalent triazine frameworks (CTF, Fig. 1a) were well designed as heterogeneous catalysts (Ir/CTF, Fig.…”

Magnetic Nickel Nanoparticles Supported on Oxidized Charcoal as a Recoverable Catalyst for N-Alkylation of Amines with Alcohols

“…8 The tunable properties of N−H bondcontaining amines facilitate the designing of tailored nanocatalysts with exclusive functions of targeted applications in a wide spectrum of industries, including agrochemicals, pharmaceuticals, surfactants, and bioactive species. 9 The general synthetic procedure for this moiety is N-alkylation/ arylation of amines. These reactions contribute up to 57% of all of the chemical reactions conducted in research and development (R&D) of the top pharmaceutical companies.…”

N-Alkylation of substituted alcohols through self-supported mesoporous CuMn2O4

“…16,17 Typically, iridium (Ir), rhodium (Rh), and ruthenium (Ru) complexes are common homogeneous complexes that have been reported before. [18][19][20][21] Due to the global emphasis on sustainable chemistry, earthabundant metals have greatly aroused the interest of chemists. [22][23][24] In addition, the first-row transition-metal complexes, including manganese, cobalt, and copper can also achieve noble metal activity in the N-alkylation of alcohols with amines.…”