Betaine Catalysis for Hierarchical Reduction of CO2 with Amines and Hydrosilane To Form Formamides, Aminals, and Methylamines

Catalytic Conversion of Carbon Dioxide through C-N Bond Formation

From the viewpoint of green chemistry and sustainable development, it is of great significance to synthesize chemicals from CO₂ as C₁ source through C-N bond formation. During the past several decade years, many studies on C-N bond formation reaction were involved, and many efforts have been made on the theory. Nevertheless, several great challenges such as thermodynamic limitation, low catalytic efficiency and selectivity, and high pressure etc. are still suffered. Herein, recent advances are highlighted on the development of catalytic methods for chemical fixation of CO₂ to various chemicals through C-N bond formation. Meanwhile, the catalytic systems (metal and metal-free catalysis), strategies and catalytic mechanism are summarized and discussed in detail. Besides, this review also covers some novel synthetic strategies to urethanes based on amines and CO₂. Finally, the regulatory strategies on functionalization of CO₂ for N-methylation/N-formylation of amines with phenylsilane and heterogeneous catalysis N-methylation of amines with CO₂ and H₂ are emphasized.

Synthesis of renewable acetic acid from CO2and lignin over an ionic liquid-based catalytic system

Renewable acetic acid can be synthesized from CO₂and lignin over an ionic liquid-based catalytic system containing Ru–Rh bimetal catalyst.

Recent advances in nucleophile-triggered CO2-incorporated cyclization leading to heterocycles

CO₂, as a sustainable, feasible, abundant one-carbon synthon, has been utilized in carboxylative cyclization, carbonylative cyclization, and reductive cyclization.

The dilemma between acid and base catalysis in the synthesis of benzimidazole from o-phenylenediamine and carbon dioxide

Synthesis of azoles from ortho-substituted anilines and CO₂ is limited by the cyclization reaction and not by CO₂ reduction.

Zwitterionic Covalent Organic Frameworks as Catalysts for Hierarchical Reduction of CO2 with Amine and Hydrosilane

Controllable hierarchical reduction of carbon dioxide (CO₂) to selectively afford versatile chemicals with specific carbon oxidation state is important but still remains a huge challenge to be realized. Here, we report new zwitterionic covalent organic frameworks ([BE] _X%-TD-COFs), prepared by introducing betaine groups (BE) onto the channel walls of presynthesized frameworks via pore surface engineering methodology, as the heterogeneous organocatalysts for CO₂ reduction. The adjustable density of immobilized BE groups as well as good preservation of crystallinity and porosity inherited from their parent COFs endow [BE] _X%-TD-COFs with highly ordered catalytic site distribution and one-dimensional mass transport pathway in favor of catalysis. By controlling the reaction temperature and amount of CO₂, [BE] _X%-TD-COFs present high activity in catalyzing reduction of CO₂ with amine and phenylsilane (PhSiH₃) to produce formamides, aminals, and methylamines, respectively, with high yield and selectivity. Furthermore, high stability and insolubility bring excellent reusability to [BE]_X%-TD-COFs with well-maintained catalytic performance after four cycles of use. Notably, this is a novel example that COFs are developed as heterogeneous catalysts for hierarchical two-, four-, and six-electron reduction of CO₂ with amines and PhSiH₃ to form C-N bonds as well as afford C^+II, C⁰, and C^-II species efficiently and selectively.

Diverse catalytic reactivity of a dearomatized PN3P*-nickel hydride pincer complex towards CO2 reduction

A dearomatized PN3P*-nickel hydride complex has been prepared using an oxidative addition process. The first nickel-catalyzed hydrosilylation of CO2 to methanol has been achieved, with unprecedented turnover numbers. Selective methylation and formylation of amines with CO2 were demonstrated by such a PN3P*-nickel hydride complex, highlighting its versatile functions in CO2 reduction.

Integrative Photoreduction of CO2 with Subsequent Carbonylation: Photocatalysis for Reductive Functionalization of CO2

Efficient conversion of CO₂ into fuels and chemicals with solar energy would be promising, but also faces great challenge. In this context, we describe the photoreductive functionalization of CO₂ to construct new C-C, C-N, and C-O bonds through the respective Pd-catalyzed Suzuki carbonylation, aminocarbonylation, and alkoxycarbonylation of aryl iodides with CO in situ generated through the photoreduction of CO₂ . This protocol opens up an alternative avenue for CO₂ utilization by harnessing solar energy.

1,4-Dioxane-Tuned Catalyst-Free Methylation of Amines by CO2 and NaBH4

A catalyst-free reductive functionalization of CO₂ with amines and NaBH₄ was developed. The N-methylation of amines was carried out with CO₂ as a C₁ building block and 1,4-dioxane as the solvent. Notably, the six-electron reduction of CO₂ to form the methyl group occurred simultaneously with formation of the C-N bond to give the N-methylated amine.

Catalyst-free N-formylation of amines using BH3NH3 and CO2 under mild conditions

The catalyst-free N-formylation of amines using CO₂ as the C₁ source and BH₃NH₃ as the reductant has been developed for the first time. The corresponding formylated products of both primary and secondary amines are obtained in good to excellent yields (up to 96% of isolated yield) under mild conditions.

Ethanol-mediated N-formylation of amines with CO2/H2 over cobalt catalysts

A cobalt-based system was developed for the selective formylation of amines with CO₂/H₂ using ethanol as the solvent.

A comparative DFT study of TBD-catalyzed reactions of amines with CO2 and hydrosilane: the effect of solvent polarity on the mechanistic preference and the origins of chemoselectivities

A DFT comparative mechanistic study unveils that the TBD-catalyzed reactions of amines with CO₂ and hydrosilanes may either undergo a neutral mechanism or a mechanism involving free ions, depending on the polarity of the solvent.