Reductive Alkylation of Azides and Nitroarenes with Alcohols: A Selective Route to Mono- and Dialkylated Amines

Ruthenium-Catalyzed Selective Mono N-Ethylation of Arylamines and Tandem Reduction/N-Ethylation of Nitroarenes Using Triethylamine and Formic Acid

The mono N-alkylation of arylamines using alkylamines as alkyl group donors has been scarcely investigated. In this work, we report the mono N-alkylation of several arylamines (52-95%) catalyzed by the complex ruthenium-triphos in the presence of Al(OTf)3. Moreover, the highly reductant ability of the catalyst system allows the tandem reduction/N-alkylation of nitrobenzenes in good yields (up to 80%). In addition, the catalyst can be recycled after three reaction cycles without loss of catalyst activity.

Metal-organic framework-derived CoNx nanoparticles on N-doped carbon for selective N-alkylation of aniline

N-alkylation of anilines by alcohols can be used as an efficient strategy to synthesise a wide range of secondary amines. In this respect, a hydrogen borrowing methodology has been explored using precious metal-based catalysts. However, the utilisation of cheap and readily available transition metal based catalysts is required for large-scale applications. In this work, we have reported metal-organic framework-derived CoNx@NC catalysts for the selective N-alkylation of anilines with different types of alcohols. The Co-N coordination in CoNx@NC was found to be extremely important to improve the conversion efficiency and yield of the product. As a result, CoNx@NC produced 99% yield of the desired amines, which is far better than that of Co@C (yield = 65%). In addition, CoNx@NC showed remarkable recyclability for six cycles with a minimum drop in the yield of the desired product.

Ruthenium-catalyzed reductive amination of ketones with nitroarenes and nitriles

The Ru(dppbsa)-catalyzed reductive amination of ketones with nitroarenes and nitriles using H₂ as the environmentally benign hydrogen surrogate is developed in this study. Cross-experiments demonstrated that both reactions are initiated by the reduction of nitroarenes or nitriles to the corresponding amines, followed by condensation with ketones to give imines and thereafter hydrogenation. However, the route to the formation of an amino-ligated Ru complex during the reduction of nitroarenes or nitriles, followed by in situ nucleophilic C-N coupling, cannot be completely excluded. This newly developed versatile method features good functional group tolerance, which provides a novel design platform for homogeneous catalysts in constructing motifs of secondary amines.

Tandem synthesis of N-methylated tertiary amines via three-component coupling of carbonyl compounds, amines, and methanol

An Ir-catalyzed tandem synthesis of various N-methylated tertiary amines from three-component coupling of carbonyl compounds, amines, and methanol following reductive amination/N-methylation is reported for the first time. A wide array of substrates with tolerance of different functional groups was demonstrated. The protocol was extended to the synthesis of N-methyl containing pharmaceutically important drug molecules. A probable catalytic cycle was proposed based on various control experiments and different analytical techniques such as NMR, IR and ESI-MS.