Simple Methodology for the Aerobic N-Methylation of Substituted Anilines Catalyzed by Zirconium Oxychloride Octahydrate, ZrOCl₂·8H₂O

Abstract

A highly chemoselective methodology is described for the N-methylation of functionalized anilines with dimethyl carbonate (MeOCO 2 Me, DMC) in the presence of ZrOCl 2 •8H 2 O. Dimethyl carbonate, which usually promotes methylation at T > 120 °C and eventually under inert atmosphere, was activated in the presence of zirconium oxychloride for the desired transformation at 90 °C under aerobic conditions. Aminophenols showed good reactivity in this transformation and produced the corresponding N-methylanilines, as the major products, with high selectivity. Catalyst reusability study confirmed that ZrOCl 2 •8H 2 O is a recyclable catalyst and its catalytic activity was remained unchanged at least after eight runs. Effect of some reaction parameters such as catalyst concentration, aniline/DMC mole ratio, reaction time, and temperature were also investigated.

Selective N-Alkylation of Amines with DMC over Biogenic Cu–Zr Bimetallic Nanoparticles

“…The results obtained are clearly in agreement with those reported in the literature. 37 On the contrary, with bimetallic NPs, both the products were isolated under similar conditions. Best yields of methylated products (82% of mono- and dimethylated and 15% of carbamoylated products) were obtained with Cu–Zr combined in a 1:2 ratio (entry 5, Table 1 ).…”

“…However, it can be inferred from Table that carbamoylation of amines was preferred over methylation in the presence of CuO NPs (entry 1), while the methylated product dominated with ZrO 2 NPs (entry 2). The results obtained are clearly in agreement with those reported in the literature . On the contrary, with bimetallic NPs, both the products were isolated under similar conditions.…”

“…The coordination of DMC to Zr 4+ has been reported to activate carbonyl and O–CH 3 functional moieties of the DMC, and thus it promotes both the methylation and carbomethoxylation of the amine involved. , By combining the NPs of Zr 4+ with Cu 2+ , the selectivity toward N -methylation enhanced as presented in Table . Thus, the tentative mechanism followed during the reaction can be described as per Scheme .…”

A new inorganic–organic hybrid material Al-SBA-15-TPI/H6P2W18O62 catalyzed one-pot, three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones

“…In extension of our investigations to explore more effective catalysts in green organic synthesis using simple and cost effective nanohybrid materials, [11][12][13] Al-SBA-15-TPI/H 6 P 2 W 18 O 62 as a new inorganic-organic hybrid material was prepared, characterized, and used as an efficient catalyst in the synthesis of 2H-indazolo[2,1-b] phthalazine-trione derivatives via onepot, three-component condensation of phthalhydrazide, aromatic aldehydes, and dimedone under solvent free conditions (Scheme 1).…”

N-Monomethylation of Aromatic Amines with Methanol via PNHP-Pincer Ru Catalysts

“…Common methylating reagents such as methyl iodide, dimethyl sulfate, and diazomethane are operationally problematic because they are toxic, harmful, and hazardous. As a result, catalytic methylation by dimethyl carbonate over solid catalysts, reductive amination of formaldehyde, and reductive methylation with CO 2 or formic acid have been studied as viable N -alkylation methods. Nevertheless, successive methylation often proceeds, inevitably leading to the formation of tertiary dimethylated amines as byproducts, because the monomethylated amines are more reactive than the starting primary amines.…”