Complete Catalytic Deoxygenation of CO<sub>2</sub> into Formamidine Derivatives

Jacquet, Olivier; Gomes, Christophe Das Neves; Ephritikhine, Michel; Cantat, Thibault

doi:10.1002/cctc.201200732

Cited by 131 publications

(82 citation statements)

References 56 publications

(19 reference statements)

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“…Some similar cyclizations have also been described with non‐radioactive CO 2 . Described conditions did not use any metal catalysts with a reaction time of 24 h. Nevertheless, in our case, the use of ZnCl 2 appeared to be crucial to observe cyclization in a reaction time of only 20 min, more consistent with carbon‐11 half‐life (entry 5).…”

Section: Resultssupporting

confidence: 83%

¹¹C‐Labeling: Intracyclic Incorporation of Carbon‐11 into Heterocycles

et al. 2019

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Labeling of heterocycles with carbon‐11 is generally performed through peripheral functionalizations and more scarcely inside heterocyclic core. Such less common approach usually requires preliminary multi‐step synthesis of reactive species. Herein, a cyclization reaction by direct use of cyclotron‐produced [11C]CO2 is described to obtain various heterocycles intracyclically labeled in only 10 minutes.

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Section: Resultssupporting

confidence: 83%

¹¹C‐Labeling: Intracyclic Incorporation of Carbon‐11 into Heterocycles

et al. 2019

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“…3,5 Two types of activation modes, i.e., silane-activation (mode A 3b,5a,5b ) and CO 2 -activation modes (mode B, 3b,5a,5b C 5c and D 5b,6g ) with NHC as the catalyst species have been reported. However, based on comprehensive DFT studies, we found new activation modes E and F that are much more favorable than modes A to D. In activation modes E and F, the thermodynamically more stable NHC-CO 2 adduct and the ionic liquid [NHCH] + [Carbamate] -rather than NHC, are the real catalytic species, respectively.…”

Section: Scheme 1 Reaction 1: Reductive Functionalization Of Co 2 Inmentioning

confidence: 99%

The Real Role of N-Heterocyclic Carbene in Reductive Functionalization of CO₂: An Alternative Understanding from Density Functional Theory Study

Zhou

2015

J. Am. Chem. Soc.

107

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The mechanisms of reductive functionalization of CO 2 to formamide catalyzed by N-heterocyclic carbene (NHC) were comprehensively studied with DFT calculations. New activation mode with much lower energy barrier than those proposed before was discovered. In this reaction, NHC acts as neither a CO 2 nor a silane activator, but as a precursor of the real catalyst, i.e., the in situ formed ionic liquid [NHCH] + [Carbamate] -. In this loose contact ion pair, the negatively charged O atom of the carbamate anion becomes the new active site, and is free to do nucleophilic attack. When amine is absent, CO 2 will be converted into methanol. In this case, the NHC-CO 2 adduct is the real catalytic species, the active site shifted from the carbene C atom to the negatively charged O atom. These new activation modes follow a pattern of "S N 2@Si-Acceptor", in which the Si-H bond is activated via concerted backside S N 2 nucleophilic attack by the negatively charged O atom, and the leaving hydride is directly accepted by a free CO 2 molecule. The advantages of these new activation modes originate from the following points: (1) the ionic liquid [NHCH] + [Carbamate] -and NHC-CO 2 adduct are thermodynamically more stable than NHC; (2) the active site of the NHC catalyst is extended outside a lot. Consequently, the large steric effect between the NHC arms and the substrates in transition state can be avoided to some extent; (3) O atom has good silicon-affinity. In addition, a free CO 2 molecule, whose carbon atom is more electrophilic than those of the CO 2 moieties in NHC-CO 2 adduct and carbamate, acts as an efficient hydride acceptor.

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“…Although silanes are well reported and active reducing agents for these types of reactions, they are low atom‐economical and require an expensive catalyst . In the case of silane, most of the reaction systems are non‐recyclable and expensive compared with borane . In the case of heterogeneous catalysts, the use of silane as reducing agents is problematic owing to the generation of solid waste, which is not soluble in water and common solvents.…”

Section: Resultsmentioning

confidence: 99%

Ru@PsIL‐Catalyzed Synthesis of N‐Formamides and Benzimidazole by using Carbon Dioxide and Dimethylamine Borane

2018

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This work reports the synthesis and characterization of ruthenium nanoparticles (Ru NPs) supported on polymeric ionic liquids (PILs). This catalyst shows high catalytic activity towards the N‐formylation of amines and synthesis of benzimidazoles from 1,2‐diamines and carbon dioxide (CO2) by reductive dehydrogenation of dimethylamine borane. This methodology shows excellent functional group tolerance with broad substrate scope towards the synthesis of N‐formamides and benzimidazoles. Interestingly, this protocol also provides the tandem reduction of 2‐nitroamines and CO2 to synthesize benzimidazoles. It was proposed that the ionic liquid phase of the polymer plays pivotal roles such as assisting the stabilization of nanoparticles electrostatically, providing an ionic environment, and controlling the easy access of the substrates/reagents to the active sites. The developed methodology utilizes CO2 as a C1 source and water/ethanol as a green solvent system. Additionally, the catalyst was found to be recyclable in nature and shows five consecutive recycling runs without significant loss in its activity.

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Complete Catalytic Deoxygenation of CO₂ into Formamidine Derivatives

Cited by 131 publications

References 56 publications

¹¹C‐Labeling: Intracyclic Incorporation of Carbon‐11 into Heterocycles

¹¹C‐Labeling: Intracyclic Incorporation of Carbon‐11 into Heterocycles

The Real Role of N-Heterocyclic Carbene in Reductive Functionalization of CO₂: An Alternative Understanding from Density Functional Theory Study

Ru@PsIL‐Catalyzed Synthesis of N‐Formamides and Benzimidazole by using Carbon Dioxide and Dimethylamine Borane

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Complete Catalytic Deoxygenation of CO2 into Formamidine Derivatives

Cited by 131 publications

References 56 publications

11C‐Labeling: Intracyclic Incorporation of Carbon‐11 into Heterocycles

11C‐Labeling: Intracyclic Incorporation of Carbon‐11 into Heterocycles

The Real Role of N-Heterocyclic Carbene in Reductive Functionalization of CO2: An Alternative Understanding from Density Functional Theory Study

Ru@PsIL‐Catalyzed Synthesis of N‐Formamides and Benzimidazole by using Carbon Dioxide and Dimethylamine Borane

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Complete Catalytic Deoxygenation of CO₂ into Formamidine Derivatives

¹¹C‐Labeling: Intracyclic Incorporation of Carbon‐11 into Heterocycles

¹¹C‐Labeling: Intracyclic Incorporation of Carbon‐11 into Heterocycles

The Real Role of N-Heterocyclic Carbene in Reductive Functionalization of CO₂: An Alternative Understanding from Density Functional Theory Study