B(C6F5)3: a robust catalyst for the activation of CO2 and dimethylamine borane for the N-formylation reactions

Saptal, Vitthal B.; Juneja, Gaurav; Bhanage, Bhalchandra M.

doi:10.1039/c8nj02816h

“…Recent progress in coordination chemistry and catalysis could provide an effective means for the chemical transformation of CO 2 and its longer‐term incorporation into organic molecules under mild conditions [42, 43] . In this regard, much attention has been paid to the synthesis of cyclic carbonates or polycarbonates from epoxides and CO 2 (Scheme 1) owing to the their useful properties [44–47] …”

Section: Introductionmentioning

confidence: 99%

Zinc Imine Polyhedral Oligomeric Silsesquioxane as a Quattro‐Site Catalyst for the Synthesis of Cyclic Carbonates from Epoxides and Low‐Pressure CO₂

Janeta

¹

,

Lis

²

,

Szafert

³

2020

Chemistry A European J

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In the present research, the synthesis, spectroscopic characterization, and structural investigations of a unique ZnII complex of imine‐functionalized polyhedral oligomeric silsesquioxane (POSS) is designed, and hereby described, as a catalyst for the synthesis of cyclic carbonates from epoxides and CO2. The uncommon features of the designed catalytic system is the elimination of the need for a high pressure of CO2 and the significant shortening of reaction times commonly associated with such difficult transformations like that of styrene oxide to styrene carbonate. Our studies have shown that imine‐POSS is able to chelate metal ions like ZnII to form a unique coordination complex. The silsesquioxane core and the hindrance of the side arms (their steric effect) influence the construction process of the homoleptic Zn4@POSS‐1 complex. The compound was characterized in solution by NMR (1H, 13C, 29Si), ESI‐MS, UV/Vis spectroscopy and in the solid state by thermogravimetric/differential thermal analysis (TG‐DTA), elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), cross‐polarization magic angle spinning (CP MAS) NMR (13C, 29Si) spectroscopy, and X‐ray crystallography.

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“…[15,20] In contrast, the reaction with hydroboranes is less well understood and the involvement of formoxyboranes remains rather speculative. [21][22][23][24] In all cases,t he CO 2 reduction stage is regarded as rate determining and is the focus of catalyst development. [25] Catalysts for the N-formylation reaction can be divided into six groups ( Figure 2).…”

Section: N-formylationmentioning

confidence: 99%

“…Thec atalyst was proposed to promote carbamate salt formation by B(C 6 F 5 ) 3 binding to the carbamate oxygen atom followed by the direct reduction of the carbamate with the hydroborane reducing agent. [24] Overall, with the exception of 1,3,2-diazaphospholene, [53] B(C 6 F 5 ) 3 [24] and insufficiently basic nucleophiles, [39] the Nformylation reaction appears to proceed by ag eneral base catalyzed reaction mechanism. Thebase promotes carbamate salt formation, which acts as an ucleophile activating the hydrosilane reducing agent for CO 2 reduction.…”

Section: Angewandte Chemiementioning

confidence: 99%

“…Nevertheless, in some cases the reaction follows a different pathway and the formoxysilane intermediate is replaced by silylcarbamate (see below) . In contrast, the reaction with hydroboranes is less well understood and the involvement of formoxyboranes remains rather speculative . In all cases, the CO 2 reduction stage is regarded as rate determining and is the focus of catalyst development …”

Section: N‐formylationmentioning

confidence: 99%

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Pivotal Role of the Basic Character of Organic and Salt Catalysts in C−N Bond Forming Reactions of Amines with CO₂

Hulla

¹

,

Dyson

²

2019

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Organocatalysts promote a range of C−N bond forming reactions of amines with CO2. Herein, we review these reactions and attempt to identify the unifying features of the catalysts that allows them to promote a multitude of seemingly unrelated reactions. Analysis of the literature shows that these reactions predominantly proceed by carbamate salt formation in the form [BaseH][RR′NCOO]. The anion of the carbamate salt acts as a nucleophile in hydrosilane reductions of CO2, internal cyclization reactions or after dehydration as an electrophile in the synthesis of urea derivatives. The reactions are enhanced by polar aprotic solvents and can be either promoted or hindered by H‐bonding interactions. The predominant role of all types of organic and salt catalysts (including ionic liquids, ILs) is the stabilization of the carbamate salt, mostly by acting as a base. Catalytic enhancement depends on the combination of the amine, the base strength, the solvent, steric factors, ion pairing and H‐bonding. A linear relationship between the base strength and the reaction yield has been demonstrated with IL catalysts in the synthesis of formamides and quinazoline‐2,4‐diones. The role of organocatalysts in the reactions indicates that all bases of sufficient strength should be able to catalyze the reactions. However, a physical limit to the extent of a purely base catalyzed reaction mechanism should exist, which needs to be identified, understood and overcome by synergistic or alternative methods.

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“…B(C 6 F 5 ) 3 was used in combination with a hydroborane reducing agent. The catalyst was proposed to promote carbamate salt formation by B(C 6 F 5 ) 3 binding to the carbamate oxygen atom followed by the direct reduction of the carbamate with the hydroborane reducing agent …”

Section: N‐formylationmentioning

confidence: 99%

Pivotal Role of the Basic Character of Organic and Salt Catalysts in C−N Bond Forming Reactions of Amines with CO₂

Hulla

¹

,

Dyson

²

2019

View full text Add to dashboard Cite

Organocatalysts promote a range of C−N bond forming reactions of amines with CO2. Herein, we review these reactions and attempt to identify the unifying features of the catalysts that allows them to promote a multitude of seemingly unrelated reactions. Analysis of the literature shows that these reactions predominantly proceed by carbamate salt formation in the form [BaseH][RR′NCOO]. The anion of the carbamate salt acts as a nucleophile in hydrosilane reductions of CO2, internal cyclization reactions or after dehydration as an electrophile in the synthesis of urea derivatives. The reactions are enhanced by polar aprotic solvents and can be either promoted or hindered by H‐bonding interactions. The predominant role of all types of organic and salt catalysts (including ionic liquids, ILs) is the stabilization of the carbamate salt, mostly by acting as a base. Catalytic enhancement depends on the combination of the amine, the base strength, the solvent, steric factors, ion pairing and H‐bonding. A linear relationship between the base strength and the reaction yield has been demonstrated with IL catalysts in the synthesis of formamides and quinazoline‐2,4‐diones. The role of organocatalysts in the reactions indicates that all bases of sufficient strength should be able to catalyze the reactions. However, a physical limit to the extent of a purely base catalyzed reaction mechanism should exist, which needs to be identified, understood and overcome by synergistic or alternative methods.

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B(C₆F₅)₃: a robust catalyst for the activation of CO₂ and dimethylamine borane for the N-formylation reactions

Abstract: In this work, B(C6F5)3 is utilized as an organocatalyst for the transition-metal-free N-formylation of amines using carbon dioxide (CO2) as a C1 source and dimethylamine borane (Me2NH·BH3) as a green hydrogen transfer source at 80 °C.

Cited by 35 publications

References 83 publications

Zinc Imine Polyhedral Oligomeric Silsesquioxane as a Quattro‐Site Catalyst for the Synthesis of Cyclic Carbonates from Epoxides and Low‐Pressure CO₂

Zinc Imine Polyhedral Oligomeric Silsesquioxane as a Quattro‐Site Catalyst for the Synthesis of Cyclic Carbonates from Epoxides and Low‐Pressure CO₂

Pivotal Role of the Basic Character of Organic and Salt Catalysts in C−N Bond Forming Reactions of Amines with CO₂

Pivotal Role of the Basic Character of Organic and Salt Catalysts in C−N Bond Forming Reactions of Amines with CO₂

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B(C6F5)3: a robust catalyst for the activation of CO2 and dimethylamine borane for the N-formylation reactions

Abstract: In this work, B(C6F5)3 is utilized as an organocatalyst for the transition-metal-free N-formylation of amines using carbon dioxide (CO2) as a C1 source and dimethylamine borane (Me2NH·BH3) as a green hydrogen transfer source at 80 °C.

Cited by 35 publications

References 83 publications

Zinc Imine Polyhedral Oligomeric Silsesquioxane as a Quattro‐Site Catalyst for the Synthesis of Cyclic Carbonates from Epoxides and Low‐Pressure CO2

Zinc Imine Polyhedral Oligomeric Silsesquioxane as a Quattro‐Site Catalyst for the Synthesis of Cyclic Carbonates from Epoxides and Low‐Pressure CO2

Pivotal Role of the Basic Character of Organic and Salt Catalysts in C−N Bond Forming Reactions of Amines with CO2

Pivotal Role of the Basic Character of Organic and Salt Catalysts in C−N Bond Forming Reactions of Amines with CO2

Contact Info

Product

Resources

About

B(C₆F₅)₃: a robust catalyst for the activation of CO₂ and dimethylamine borane for the N-formylation reactions

Zinc Imine Polyhedral Oligomeric Silsesquioxane as a Quattro‐Site Catalyst for the Synthesis of Cyclic Carbonates from Epoxides and Low‐Pressure CO₂

Zinc Imine Polyhedral Oligomeric Silsesquioxane as a Quattro‐Site Catalyst for the Synthesis of Cyclic Carbonates from Epoxides and Low‐Pressure CO₂

Pivotal Role of the Basic Character of Organic and Salt Catalysts in C−N Bond Forming Reactions of Amines with CO₂

Pivotal Role of the Basic Character of Organic and Salt Catalysts in C−N Bond Forming Reactions of Amines with CO₂