Preparation of 11C-Urea from No-carrier-added 11C-Cyanide

Emran, Ali M.; Boothe, Thomas E.; Finn, Ronald D.; Vora, Manhar M.; Kothari, Paresh

doi:10.1016/0020-708x(83)90082-0

Cited by 16 publications

(2 citation statements)

References 9 publications

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“…Conversion of [ 11 C]HCN to [ 11 C]urea 184,185 provides a labeled precursor for heterocycles including hydantoins 186 and nucleosides. 187 Oxidation of K 11 CN with potassium permanganate produces the 11 C-cyanate salt, which can be converted into hydroxyurea or isohydroxyurea (Scheme 11A).…”

Section: [11c]hcn Cyanationmentioning

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]hcn Cyanationmentioning

confidence: 99%

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

et al. 2016

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“…Firstly, [ 11 C]KCN was converted to [ 11 C]KOCN by catalytic oxidation with Cu(OH) 2 and successively converted to its ammonium salt with ammonium hydroxide to achieve final [ 11 C]urea (Figure ). After HPLC purification, RCY was higher than 85% from no-carrier-added [ 11 C]KCN in 20–25 min with A m of 129.5 ± 29.6 GBq/μmol at EOB. , Further optimizations by increasing the pH and temperature and using an appropriate vessel to reduce urea decomposition provided RCY of 95.0 ± 2.5%, decreasing the total synthesis time to approximately 16 min from EOB . Lastly, [ 11 C]urea was also obtained directly from [ 11 C]CO 2 by reaction with lithium bis(trimethylsilyl)amide (LBTMSA) in THF, followed by a process with aqueous NH 4 Cl solution.…”

Section: Other Compoundsmentioning

confidence: 99%

Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds

et al. 2022

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The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.

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