Efficient Cobalt‐Catalyzed Methylation of Amines Using Methanol

Abstract

The methylation of amines using methanol is a promising route to synthesize N-methylamines, and the development of cheap and efficient catalytic system for this reaction is of great significance. Herein, we reported a cobalt (Co)based catalytic system, which was in situ formed from commercially available Co precursor and a tetradentate phosphine ligand P(CH 2 CH 2 PPh 2 ) 3 combined with K 3 PO 4 . This catalystic system was very effective for the selective production of dimethylated products from aliphatic amines and monomethylated ones from aromatic amines. The reaction mechanism was further investigated by control and isotope labelling experiments.

Selective N‐Monomethylation of Amines and Nitroarenes using Methanol over an Encapsulated Iridium Nanocatalyst

“…The transfer hydrogenation and successive cyclization coupling reaction of ortho-phenylenediamine with methanol to afford benzimidazole and Nmethylbenzimidazole was also efficiently realized under moderate reaction conditions. [8] As for the catalytic system, homogeneous Ru, [9] Ir, [10] Mn, [11] Co [12] and Fe [13] complexes and the photocatalysts, such as Ag/TiO 2 [14] were reported to be effective for the N-monomethylation of amines (Scheme 1b). N-methylated amines, in particular, are recognized as the key intermediates for pharmaceuticals, biologically active products, dyes and agrochemicals synthesis.…”

“…Advantages for this protocol are as follows: 1) no additional external hydrogen source is required as methanol acts as the hydrogen donor; 2) the transformation is environmental benign as water is the only by-product and the atom economy is high. [8] As for the catalytic system, homogeneous Ru, [9] Ir, [10] Mn, [11] Co [12] and Fe [13] complexes and the photocatalysts, such as Ag/TiO 2 [14] were reported to be effective for the N-monomethylation of amines (Scheme 1b). [6] Nevertheless, the application of methanol is still challenging as it possess a high dehydrogenation energy (DH = + 84 kJ/mol) compared with that of other higher alcohols (e. g. DH (EtOH) = + 68 kJ/mol).…”

Recent Advances in Methylation: A Guide for Selecting Methylation Reagents

“…In arecent work by Liu et al,Co(acac) 2 was used as the catalyst for mono N-methylation. [234] Under the optimal conditions, as shown in Ta ble 40, the dimethylated products were formed from benzylic and aliphatic amines, whereas the aromatic amines formed monomethylated products. 3 )a sacatalyst for selective mono N-alkylation of primary amines by using dialkylp hosphite as the alkylating agent and solventu nder microwavei rradiation conditions.…”

“…In a recent work by Liu et al., Co(acac) 2 was used as the catalyst for mono N‐methylation . Under the optimal conditions, as shown in Table , the dimethylated products were formed from benzylic and aliphatic amines, whereas the aromatic amines formed monomethylated products.…”

Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas

“…Ligands play a decisive role in adjusting the catalytic ability of metal cations [12,13,[41][42][43][44][45][46][47][48][49][50][51]. Different ligands coordinating with the same metal cations could make a difference between full conversion with nearly quantitative yields and no reactions.…”