Ruthenium‐Catalyzed Direct Methylation of Primary and Secondary Aromatic Amines Using Carbon Dioxide and Molecular Hydrogen

Abstract

The effective catalytic N-methylation of anilines using CO₂ as C₁ source and molecular hydrogen as reducing agent was demonstrated using the well-defined [Ru(triphos)(tmm)] catalyst. Secondary and primary (shown) aromatic amines were mono- or dialkylated, respectively, in high yields. N-methylation of amides coupled with the amide hydrogenation offers an efficient approach to unsymmetrical tertiary methyl/alkyl/aromatic amines

Light-promoted N,N-dimethylation of amine and nitro compound with methanol catalyzed by Pd/TiO2 at room temperature

“…The results of the N-methylation of secondary amines were summarized in Table 2. 74-98%, were generally gained (entries [12][13][14][15][16]. Except for cyclic aliphatic secondary amines, the reaction was also successful for the N-methylation of dicyclohexylamine.…”

“…[1][2][3][4][5] Compared with other N-alkyl amines, N-methyl and N,Ndimethyl amines have attracted extensive attention in industry. [12][13][14] Unfortunately, these methods are oen problematic from synthetic or environmental standpoints. [12][13][14] Unfortunately, these methods are oen problematic from synthetic or environmental standpoints.…”

Hydrogenation of Polar Bonds Catalysed by Ruthenium-Pincer Complexes

“…hydrogen directly as reducing agent was also reported by Klankermayer and Leitner using the Ru(II)-complex 26 and an acid (HNTf 2 ) (Scheme 13) [96]. Sanford and co-workers subjected our catalyst (2) for highly efficient catalytic hydrogenation of CO 2 to formate salts [97] and displays similar activity to known Nozaki's Ir(III) pincer catalyst 27 (TON ¼ 3,500,000 and TOF ¼ 150,000 h À1 for CO 2 to HC(O)OK) [98,99].…”

Hydrogen

“…In a related reaction, direct methylation of amines has been achieved using CO 2 and hydrogen. 81,82 This approach allowed selective monomethylation of diamines and also the formation of 13 C methylated amines using 13 …”