C-N and N-H Bond Metathesis Reactions Mediated by Carbon Dioxide

Amino Acid-Based Ionic Liquids-Aided CO2 Hydrogenation to Methanol

This study explored the use of amino acid-based ionic liquids to facilitate the conversion of carbon dioxide (CO2) into methanol through catalytic hydrogenation. Combining tetrabutylammonium L-argininate (TBA⋅Arg) with the ruthenium Ru-MACHO-BH complex allowed achieving significant yields of methanol under optimized conditions, with a turnover number (TON) up to 700. By systematically varying key reaction parameters, we demonstrated that the TBA⋅Arg ionic liquid promotes the efficient hydrogenation pathway leading to methanol formation, thus offering a sustainable approach to CO2 valorization. These findings underscore the potential of amino acid-based ionic liquids in catalyzing the transformation of CO2 into valuable chemicals, contributing to carbon mitigation efforts.

Tuning Ionic Liquid-Based Catalysts for CO2 Conversion into Quinazoline-2,4(1H,3H)-diones

Carbon capture and storage (CCS) and carbon capture and utilization (CCU) are two kinds of strategies to reduce the CO2 concentration in the atmosphere, which is emitted from the burning of fossil fuels and leads to the greenhouse effect. With the unique properties of ionic liquids (ILs), such as low vapor pressures, tunable structures, high solubilities, and high thermal and chemical stabilities, they could be used as solvents and catalysts for CO2 capture and conversion into value-added chemicals. In this critical review, we mainly focus our attention on the tuning IL-based catalysts for CO2 conversion into quinazoline-2,4(1H,3H)-diones from o-aminobenzonitriles during this decade (2012~2022). Due to the importance of basicity and nucleophilicity of catalysts, kinds of ILs with basic anions such as [OH], carboxylates, aprotic heterocyclic anions, etc., for conversion CO2 and o-aminobenzonitriles into quinazoline-2,4(1H,3H)-diones via different catalytic mechanisms, including amino preferential activation, CO2 preferential activation, and simultaneous amino and CO2 activation, are investigated systematically. Finally, future directions and prospects for CO2 conversion by IL-based catalysts are outlined. This review is benefit for academic researchers to obtain an overall understanding of the synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and o-aminobenzonitriles by IL-based catalysts. This work will also open a door to develop novel IL-based catalysts for the conversion of other acid gases such as SO2 and H2S.

A CO2-Catalyzed Transamidation Reaction

Transamidation reactions are often mediated by reactive substrates in the presence of overstoichiometric activating reagents and/or transition metal catalysts. Here we report the use of CO₂ as a traceless catalyst: in the presence of catalytic amounts of CO₂, transamidation reactions were accelerated with primary, secondary, and tertiary amide donors. Various amine nucleophiles including amino acid derivatives were tolerated, showcasing the utility of transamidation in peptide modification and polymer degradation (e.g., Nylon-6,6). In particular, N,O-dimethylhydroxyl amides (Weinreb amides) displayed a distinct reactivity in the CO₂-catalyzed transamidation versus a N₂ atmosphere. Comparative Hammett studies and kinetic analysis were conducted to elucidate the catalytic activation mechanism of molecular CO₂, which was supported by DFT calculations. We attributed the positive effect of CO₂ in the transamidation reaction to the stabilization of tetrahedral intermediates by covalent binding to the electrophilic CO₂.

MoS2-Catalyzed transamidation reaction

The MoS2-catalyzed transamidation reaction with high yields using N,N-dimethylformamide and other amides as carbonyl sources is developed here. The protocol is simple, does not require any additive such as acid, base, ligand, etc., and encompasses a broad substrate scope for primary, secondary and heterocyclic amines. Moreover, the acetylation and propanylation of amines also can be achieved with good to excellent yield by this strategy.

Recent Uses of N,N-Dimethylformamide and N,N-Dimethylacetamide as Reagents

N,N-Dimethylformamide and N,N-dimethylacetamide are multipurpose reagents which deliver their own H, C, N and O atoms for the synthesis of a variety of compounds under a number of different experimental conditions. The review mainly highlights the corresponding literature published over the last years.

Photocatalytic N-formylation of amines via a reductive quenching cycle in the presence of air

Photochemical N-formylation of amines was achieved without any additional formylating agents in the presence of air. Mechanistic investigations suggest a reaction pathway proceeding via the addition of in situ formed radical cations of enamines with photochemically generated superoxide radical anions.

Atmospheric CO2 promoted synthesis of N-containing heterocycles over B(C6F5)3 catalyst

CO₂ gas greatly promoted the cyclization of various o-substituted anilines with N,N-dimethylformamide, producing N-containing heterocycles in high yields.