N-alkylation of amines with alcohols over alumina-entrapped Ag catalysts using the “borrowing hydrogen” methodology

‘‘Hydrogen-Free’’ Hydrogenation of Nitrobenzene Over Cu/SiO2 Via Coupling with 2-Butanol Dehydrogenation

“…Nagaraja et al[10] and Sawadjoon et al[56] reached a similar conclusion in their analysis of the gas phase coupling of cyclohexanol dehydrogenation with furfural hydrogenation (T = 453-523 K, P = 1 atm) over Cu-MgO-Cr 2 O 3 and liquid phase coupling of alcohol hydrogenolysis with formic acid as hydrogen donor (T = 353 K, P = 1 atm) over Pd/carbon, respectively. Moreover, there is evidence in the literature for the formation of transitory metal-H (Cu-H[57], Ru-H[58], Ag-H[59] and Ni-H[60]) species (via interaction with hydrogen abstracted from alcohols) that can serve as a source of reactive hydrogen. In this study, the abstracted hydrogen associated with copper (Cu-H) must participate in the nitrobenzene hydrogenation step.…”

Self-coupling of benzylamines over a highly active and selective supported copper catalyst to produce N-substituted amines by the borrowing hydrogen method

“…With alcohols as the initial source of the electrophile, this reaction sequence can be initialized by several catalysts such as Pd [5], Pt [6], Ru [7], Ir [8], Ag [9], Au [10] and CuAg bimetallic catalysts [11]. The same methodology has also been applied for N-alkylation of nitroaromatics [12], N-alkylation of amines [5,7,9,10], transamidation of carboxyamides and ureas [13], and CAC bond formation [14]. Compared to the use of alcohols as the source of electrophiles, the alkylation of amines with other amines is much less developed.…”

“…We have described a procedure for the synthesis of secondary amines starting from the corresponding primary amines or nitroarenes using Ag/Al 2 O 3 catalysts [9]. Using this method, we successfully achieved the N-alkylation of amines with different alcohols as the electrophile.…”

Reusable Supported Ruthenium Catalysts for the Alkylation of Amines by using Primary Alcohols

“…However, a higher reaction temperature (140 8C) and a long reaction time (50 h) were needed for the alkylation of cyclic amines such as pyrrolidine. Ag/Al 2 O 3 [18] catalysts were found to be active in the presence of Cs 2 CO 3 (30 mol %) for the N-alkylation of anilines at 120 8C and gave up to 99 % yield. Other heterogeneous catalysts such as Pd/MgO, Cu-Ag/ Al 2 O 3 , g-Al 2 O 3 /Ag, NiCu-FeO x , CuAl-hydrotalcite, and Ru(OH) x / Al 2 O 3 are also known [16] for the alkylation of aniline derivatives at temperatures > 135 8C.…”