Observation of guanidine–carbon dioxide complexation in solution and its role in the reaction of carbon dioxide and propargylamines

Nicholls, Rachel; Kaufhold, Simon; Nguyen, Bao

doi:10.1039/c4cy00480a

Cited by 61 publications

(36 citation statements)

References 44 publications

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“…Therefore, we propose that the basicity of the NH 2 groups in catalyst MOF‐1 a is important to the catalytic reaction. The mechanism is proposed as follows: CO 2 is activated by propargylamines; then, the NH 2 groups in MOF‐1 a promoted an efficient ring closure to the oxazolidinones derivative, which was rather stable under the reaction conditions (Figure ) …”

Section: Resultsmentioning

confidence: 99%

Efficient and Reusable Metal–Organic Framework Catalysts for Carboxylative Cyclization of Propargylamines with Carbon Dioxide

et al. 2017

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Carbon dioxide (CO2) capture and transformation are important for decreasing the concentration of atmospheric CO2. To effectively capture CO2 and further fix it into valuable chemical products, functionalized dynamic metal–organic frameworks (MOFs) have been utilized not only because of their inherent cavity for accommodating CO2 but also owing to their reversible structural transformations in response to external stimuli for regulating the reaction. Herein, we report a dynamic and functional MOF [Cd3(L)2(BDC)3]2⋅16 DMF (MOF‐1 a; DMF=N,N‐dimethylformamide) achieved by reaction of the amino tripodal imidazole ligand N1‐(4‐(1 H‐imidazol‐1‐yl)benzyl)‐N1‐ (2‐aminoethyl)ethane‐1,2‐diamine (L) and 1,4‐benzenedicarboxylic acid (H2BDC) with cadmium salt. MOF‐1 a not only shows unprecedented high catalytic activity [initial turnover number (TON) up to 9300] and broad substrate scope for the carboxylative cyclization of propargylamines with CO2, but also can be switched on and off upon reversible structural transformation owing to its dynamic five‐fold interpenetrating structure. Further studies demonstrate that MOF‐1 a shows selective catalytic properties depending on the size of substrates, similarly to sophisticated biological systems.

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Section: Resultsmentioning

confidence: 99%

Efficient and Reusable Metal–Organic Framework Catalysts for Carboxylative Cyclization of Propargylamines with Carbon Dioxide

et al. 2017

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“…Hence, our calculations suggest that the guanidine‐catalyzed coupling reaction of CO 2 with alkynyl indole would proceed preferentially through a specific‐base mechanism rather than the CO 2 activation mechanism, which involves the formation of a TBD‐CO 2 adduct. This theoretical finding is consistent with the experimental results of a similar CO 2 coupling reaction with propargylamines …”

Section: Resultsmentioning

confidence: 99%

“…For example, Villers et al demonstrated the existence of a TBD‐CO 2 adduct in the solid state . More recently, Nguyen and co‐workers reported the first account of guanidine‐CO 2 complexes in solution . Based on the correlation between the catalytic activity and basicity properties of amines/guanidines in the reactions of CO 2 with propargylamines, the authors concluded that the basicity of the catalyst, rather than the formation of the CO 2 adduct, was responsible for the catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

Coupling Reactions of Alkynyl Indoles and CO₂ by Bicyclic Guanidine: Origin of Catalytic Activity?

Kee

Peh

Wong

2017

Chemistry An Asian Journal

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Density functional theory calculations were used to investigate the three possible modes of activation for the coupling of CO with alkynyl indoles in the presence of a guanidine base. The first of these mechanisms, involving electrophilic activation, was originally proposed by Skrydstrup et al. (Angew. Chem. Int. Ed. 2015, 54, 6682). The second mechanism involves the nucleophilic activation of CO . Both of these electrophilic and nucleophilic activation processes involve the formation of a guanidine-CO zwitterion adduct. We have proposed a third mechanism involving the bifunctional activation of the bicyclic guanidine catalyst, allowing for the simultaneous activation of the indole and CO by the catalyst. We demonstrated that a second molecule of catalyst is required to facilitate the final cyclization step. Based on the calculated turnover frequencies, our newly proposed bifunctional activation mechanism is the most plausible pathway for this reaction under these experimental conditions. Furthermore, we have shown that this bifunctional mode of activation is consistent with the experimental results. Thus, this guanidine-catalyzed reaction favors a specific-base catalyzed mechanism rather than the CO activation mechanism. We therefore believe that this bifunctional mechanism for the activation of bicyclic guanidine is typical of most CO coupling reactions.

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“…[32][33][34] As earlya s1 931, alkanolamines were utilized to capture carbon dioxide from natural gas. [28,29,31] Chemical conversion of CO 2 under atmosphericp ressure and metal-free conditions remains ag reat challenge. At present, it is widely recognized that only superbases and their derivatives can serve as single catalysts or can coordinate with metal catalysts to catalyze the transformation of CO 2 and propargylic amines.…”

Section: Introductionmentioning

confidence: 99%

An Experimental and Theoretical Study on the Unexpected Catalytic Activity of Triethanolamine for the Carboxylative Cyclization of Propargylic Amines with CO₂

Zhang

Qiu

et al. 2017

ChemSusChem

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Chemical conversion of CO under atmospheric pressure and metal-free conditions remains a great challenge. In this work, a series of alkanolamines, low-cost and biodegradable bases, were used to catalyze the carboxylative cyclization of propargylic amines with CO . Among these alkanolamines, triethanolamine (TEOA) was found to be a highly efficient organocatalyst for this important transformation at atmospheric pressure, and a series of desired products were synthesized in good to excellent yields. After the reactions, TEOA could be easily recovered and reused without obvious reduction in the efficiency. DFT studies revealed that TEOA may activate CO to form a ring-shaped carbonate intermediate that plays an important role in the catalysis of the reaction. This finding provides an effective and environmentally friendly alternative route for the production of 2-oxazolidinones.

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Observation of guanidine–carbon dioxide complexation in solution and its role in the reaction of carbon dioxide and propargylamines

Abstract: The first observation of guanidine–CO2 ‘activation’ complexes in solution and their implications on the catalytic activity of guanidines are reported.

Cited by 61 publications

References 44 publications

Efficient and Reusable Metal–Organic Framework Catalysts for Carboxylative Cyclization of Propargylamines with Carbon Dioxide

Efficient and Reusable Metal–Organic Framework Catalysts for Carboxylative Cyclization of Propargylamines with Carbon Dioxide

Coupling Reactions of Alkynyl Indoles and CO₂ by Bicyclic Guanidine: Origin of Catalytic Activity?

An Experimental and Theoretical Study on the Unexpected Catalytic Activity of Triethanolamine for the Carboxylative Cyclization of Propargylic Amines with CO₂

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Observation of guanidine–carbon dioxide complexation in solution and its role in the reaction of carbon dioxide and propargylamines

Abstract: The first observation of guanidine–CO2 ‘activation’ complexes in solution and their implications on the catalytic activity of guanidines are reported.

Cited by 61 publications

References 44 publications

Efficient and Reusable Metal–Organic Framework Catalysts for Carboxylative Cyclization of Propargylamines with Carbon Dioxide

Efficient and Reusable Metal–Organic Framework Catalysts for Carboxylative Cyclization of Propargylamines with Carbon Dioxide

Coupling Reactions of Alkynyl Indoles and CO2 by Bicyclic Guanidine: Origin of Catalytic Activity?

An Experimental and Theoretical Study on the Unexpected Catalytic Activity of Triethanolamine for the Carboxylative Cyclization of Propargylic Amines with CO2

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Product

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Coupling Reactions of Alkynyl Indoles and CO₂ by Bicyclic Guanidine: Origin of Catalytic Activity?

An Experimental and Theoretical Study on the Unexpected Catalytic Activity of Triethanolamine for the Carboxylative Cyclization of Propargylic Amines with CO₂