A Mitsunobu-based procedure for the preparation of alkyl and hindered aryl isocyanates from primary amines and carbon dioxide under mild conditions

Horvath, Michael J.; Saylik, Dilek; Elmes, Patricia S.; Jackson, W. R.; Lovel, Craig G.; Moody, K.

doi:10.1016/s0040-4039(98)02312-0

Cited by 34 publications

(12 citation statements)

References 8 publications

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“…Mitsunobu chemistry could also be employed to convert ionic carbamates into isocyanates using phosphines and azo compounds (Scheme 2B). 46,47 In the presence of an additional amine, the isocyanate could be transformed in situ to a urea. 48 To accommodate this reaction to radiolabeling conditions, the reaction temperature was carefully controlled at 50 °C to promote the reaction and prevent premature release of [ 11 C]CO 2 .…”

Section: [11c]co2-fixationmentioning

confidence: 99%

¹¹CO bonds made easily for positron emission tomography radiopharmaceuticals

et al. 2016

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The positron-emitting radionuclide carbon-11 (11C, t1/2 = 20.3 minutes) possesses the unique potential for radiolabeling of any biological, naturally occurring, or synthetic organic molecule for in vivo positron emission tomography (PET) imaging. Carbon-11 is most often incorporated into small molecules by methylation of alcohol, thiol, amine or carboxylic acid precursors using [11C]methyl iodide or [11C]methyl triflate (generated from [11C]CO2). Consequently, small molecules that lack an easily substituted 11C-methyl group are often considered to have non-obvious strategies for radiolabeling and require a more customized approach. [11C]Carbon dioxide, [11C]carbon monoxide, [11C]cyanide, and [11C]phosgene represent alternative carbon-11 reactants to enable 11C-carbonylation. Methodologies developed for preparation of 11C-carbonyl groups have had a tremendous impact on the development of novel PET radiopharmaceuticals and provided key tools for clinical research. 11C-Carbonyl radiopharmaceuticals based on labeled carboxylic acids, amides, carbamates, and ureas now account for a substantial number of important imaging agents that have seen translation to higher species and clinical research of previously inaccessible targets, which is a testament to the creativity, utility, and practicality of the underlying radiochemistry.

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Section: [11c]co2-fixationmentioning

confidence: 99%

¹¹CO bonds made easily for positron emission tomography radiopharmaceuticals

et al. 2016

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“…Because of chemical inertness of CO 2 , there are relatively few reports concerning carbonylation reactions of nitrogen‐containing compounds by using carbon dioxide in comparison with those that make use of CO . Very recently, a versatile method of the synthesis of non‐isocyanate renewable polyurethanes was proposed by Unverferth et al The polycondensation reaction of fatty acid derived bis(methyl dicarbamate)s with diols was catalyzed by 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD; Scheme ).…”

Section: Nipu Obtained By Polycondensation Methodsmentioning

confidence: 99%

Non‐isocyanate polyurethanes: synthesis, properties, and applications

Rokicki

Parzuchowski

Mazurek

2015

Polymers for Advanced Techs

311

233

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Conventional polyurethanes are typically obtained from polyisocyanates, polyols, and chain extenders. The main starting materials-isocyanates used in this process-raise severe health hazard concerns. Therefore, there is a growing demand for environment-friendly processes and products. This review article summarizes progress that has been made in recent years in the development of alternative methods of polyurethane synthesis. In most of them, carbon dioxide is applied as a sustainable feedstock for polyurethane production directly or indirectly. The resulting nonisocyanate polyurethanes are characterized by a solvent-free synthesis, resistance to chemical degradation, 20% more wear resistance than conventional polyurethane, and can be applied on wet substrates and cured under cold conditions. Three general polymer synthetic methods, step-growth polyaddition, polycondensation, and ring-opening polymerization, are presented in the review. Much attention is given to the most popular and having potential industrial importance method of obtaining non-isocyanate polyurethanes, poly(hydroxy-urethane)s, based upon multicyclic carbonates and aliphatic amines. It is evident from the present review that considerable effort has been made during the last years to develop environmentally friendly methods of obtaining polyurethanes, especially those with the use of carbon dioxide or simple esters of carbonic acid. Scheme 1. [n,m]-Polyurethane synthesis from alkylene bis(chloroformate)s and diamines. Scheme 2. Synthesis of NIPU in the reaction of alkylene bis(phenyl carbonate) with diamine. Scheme 3. Synthesis of [n]-polyurethane from aminoalkyl chloroformate.Scheme 4. Synthesis of [6]-polyurethane from 6-amino-1-hexanol. Scheme 5. Synthesis of allylcarbamate monomer and poly(thioether-urethane).708 Scheme 8. Synthesis of NIPU via AB-type self-polycondensation.Scheme 7. Multistep synthesis of isosorbide-based polyurethane (polycondensation mode). Scheme 6. Multistep synthesis of isosorbide-based polyurethane (polyaddition mode).

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“…Solvents were distilled over appropriate drying agents prior to use. ILs were synthesized according to the literature procedures: 1-butyl-3-methylimidazolium chloride ([BMIm]Cl), 1-butyl-3-methylimidazolium bromide ([BMIm]Br), 1-butyl-3-methylimidazolium iodide ([BMIm]I), 22 1-butyl-3methylimidazolium tetrafluoroborate ([BMIm]BF 4 ), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm]PF 6 ), 23 1-butyl-3-methylimidazolium acetate ([BMIm]OAc), 24 1-butyl-3-methylimidazolium hydroxide ([BMIm]OH), 21 1-butyl-3methylimidazolium dimethylphosphate ([BMIm]Me 2 PO 4 ), 25 1-butyl-3-methylimidazolium methylphosphite ([BMIm]-MePHO 3 ), 26 1-butyl-3-methylimidazolium methylsulfate ([BMIm]MeSO 4 ), 27 1-butyl-3-methylimidazolium methane sulfonate ([BMIm]MeSO 3 ), 28,29 N-butyl-N-methylpyrrolidinium chloride ([BMPyrr]Cl), 30 N-butyl-N-methylpiperidinium chloride ([BMPip]Cl), 31 and 1-butylpyridinium chloride ([BPy]Cl). 32 Molten salts, such as choline chloride ([Choline]Cl), tetran-butylphosphonium chloride (n-Bu 4 PCl), tetra-n-butylphosphonium bromide (n-Bu 4 PBr), tetra-n-butylammonium chloride (n-Bu 4 NCl), and tetra-n-butylammonium bromide (n-Bu 4 NBr), were obtained from Aldrich Chemical Co.…”

Section: Methodsmentioning

confidence: 99%

Ionic liquid-assisted carboxylation of amines by CO2: a mechanistic consideration

Shim

Lee

et al. 2011

Phys. Chem. Chem. Phys.

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The catalytic roles of ionic liquids (ILs) in the syntheses of 1,3-disubstituted ureas from the carboxylation of amines by CO(2) were experimentally and theoretically investigated. The carboxylation reaction of n-butylamine was greatly facilitated by the presence of an IL and the catalytic activity of the IL was strongly affected by the nucleophilicity of the anion. Computational study on the mechanistic aspects of the carboxylation with methylamine with or without the presence of an IL, 1-ethyl-3-methylimidazolium chloride, implies that the activation energies of the transition states and the intermediate ionic species could be lowered significantly through the multi-interactions of the carbonyl group of CO(2) with both cations and anions of the ILs.

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A Mitsunobu-based procedure for the preparation of alkyl and hindered aryl isocyanates from primary amines and carbon dioxide under mild conditions

Cited by 34 publications

References 8 publications

¹¹CO bonds made easily for positron emission tomography radiopharmaceuticals

¹¹CO bonds made easily for positron emission tomography radiopharmaceuticals

Non‐isocyanate polyurethanes: synthesis, properties, and applications

Ionic liquid-assisted carboxylation of amines by CO2: a mechanistic consideration

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A Mitsunobu-based procedure for the preparation of alkyl and hindered aryl isocyanates from primary amines and carbon dioxide under mild conditions

Cited by 34 publications

References 8 publications

11CO bonds made easily for positron emission tomography radiopharmaceuticals

11CO bonds made easily for positron emission tomography radiopharmaceuticals

Non‐isocyanate polyurethanes: synthesis, properties, and applications

Ionic liquid-assisted carboxylation of amines by CO2: a mechanistic consideration

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Product

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¹¹CO bonds made easily for positron emission tomography radiopharmaceuticals

¹¹CO bonds made easily for positron emission tomography radiopharmaceuticals