Radiochemistry for Preclinical Imaging Studies
George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos in Handbook of Small Animal Imaging, 2018
The nucleophilicity of [18F]F− can, however, be increased. For instance, potassium carbonate is added with potassium acting as a counter-cation to fluoride. The counter-cation can be complexed by a phase transfer catalyst such as Kryptofix. This creates the so-called naked fluoride and improves both its reactivity and solubility in the organic reaction solvent. Other phase-transfer systems can be used to modulate the strength of the base in case of sensitive labeling substrates. These [18F]F− methods may rely on potassium bicarbonate, cesium carbonate, oxalate, tetrabutylammonium bicarbonate, 18-crown-6 ether, and others. Fluoride will preferably react with the protons of water and form [18F]HF with no nucleophilic activity. Therefore, in the classical protocol, any macroscopic amount of water will have to be carefully removed by concentration with solid-phase extraction on an ion exchange resin. This is followed by an azeotropic distillation using acetonitrile. This process serves also as the foundation for the preparation of 2-deoxy-2-[18F]fluoro-d–glucose (Figure 16.15).
Operations at the Philadelphia Laboratory
George Winston Smith in Medicines for the Union Army, 2014
Diehl employed open vessels in making a number of his preparations. There was, for example, a crane in the furnace room (see Photo 4.5) that swung large enamelled kettles over one of the fires, heating vinegar of squill, and sugar for Syrup of Squill. The solution was then strained while it was still hot.111 Another large kettle was used to prepare solutions of sodium carbonate, potassium carbonate, and other saline compounds.112 Quinine and a citrate of iron solution were heated in a water bath at 120°F until the quinine was dissolved. The solution was then evaporated to a consistency of a syrup, placed in earthenware jars, and taken to the scaling room on the third floor of the main building to be spread on plates of glass for drying.113
Procedures for Writing Formulas and Naming Compounds
Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk in Survival Guide to General Chemistry, 2019
Example: Name K2CO3Potassium: Direct (unchanged) name of the metal that forms the positive ion.Potassium is in Group I and is a fixed-charged metal; no Roman numeral is required.The name carbonate matches the formula (CO3) as the negative ion (charges are not shown); the name is used directly with no change and is stated last in the complete name of the compound. Name: potassium carbonate
Evaluation of sulphonamide derivatives acting as inhibitors of human carbonic anhydrase isoforms I, II and Mycobacterium tuberculosis β-class enzyme Rv3273
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Tanvi V. Wani, Silvia Bua, Pravin S. Khude, Abdul H. Chowdhary, Claudiu T. Supuran, Mrunmayee P. Toraskar
The key intermediate 1 (ethyl 2-((4-sulphamoylphenyl) amino) acetate) was obtained in good yields by the reaction of sulphanilamide with ethyl bromoacetate in the presence of potassium carbonate (no sulphonamide N-alkylation occurred), Scheme 1. During optimisation, the same reaction was performed with sodium carbonate instead of potassium carbonate. The results were not satisfactory, and whence the equimolar ratio of both the reactants in the presence of K2CO3 and ethanol as a solvent was used to obtain compound 1. 4-((2-Hydrazinyl-2-oxoethyl)amino) benzene sulphonamide (2) was obtained by the reaction of hydrazine hydrate with 1 in equimolar ratios. The reaction was refluxed for 3 h at 70 °C producing the compound with yields of 70–72%. Reaction of 2 with various substituted aromatic aldehydes afforded derivatives 6. When using unsaturated aldehydes, a cyclisation reaction occurred after the Schiff base formation, leading to compounds 5 (Scheme 1).
Novel Quinoxaline-2-Carbonitrile-1,4-Dioxide Derivatives Suppress HIF1α Activity and Circumvent MDR in Cancer Cells
Published in Cancer Investigation, 2018
Alexander M. Scherbakov, Alexander M. Borunov, Galina I. Buravchenko, Olga E. Andreeva, Igor A. Kudryavtsev, Lyubov G. Dezhenkova, Andrey E. Shchekotikhin
The series of 3-aryl/hetaryl-quinoxaline-2-carbo-nitrile-1,4-dioxides 2a-m was synthesized by the Beirut reaction (Figure 2). Target compounds were obtained by condensation of corresponding benzofuroxanes 3a-g and acylacetonitriles 4a-g in the presence of a base (Table 1). These starting mono- or disubstituted benzofuroxanes 3a-g and acylacetonitriles 4a-g were obtained by previously described methods (20,27). Two reaction conditions for the Beirut reaction were examined. First, substoichiometric quantities of potassium carbonate as a base in ethanol at room temperature (Method A) was tested (23). In cases of fluoro derivatives (2c, f, h-m), low yield (15% to 45%) of target products was observed. The second condition tested was substoichiometric quantities of triethylamine as the base in chloroform at room temperature (Method B) (36). This generates notably higher yields of target compounds than method A (Table 1). The structure of final quinoxaline-2-carbonitrile-1,4-dioxides 2a-m was elucidated by NMR and HRMS spectra and their purity (>95%) by HPLC.
Different chemical proteomic approaches to identify the targets of lapatinib
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Tatjana Kovačević, Krunoslav Nujić, Mario Cindrić, Snježana Dragojević, Adrijana Vinter, Amela Hozić, Milan Mesić
A solution of N-[3-chloro-4-[(3-fluorophenyl)methoxy]phenyl]-6-[5-[(2-methylsulfonylethylamino)methyl]-2-furyl]quinazolin-4-amine (1) (70 mg, 0.120 mmol) and sodium hydride, 60% disperse in mineral oil (9.6 mg, 0.240 mmol) in DMF (2 ml) was cooled to 0 °C. 2-[2-(bromomethyl)-5-[3-(trifluoromethyl)diazirin-3-yl]phenyl]ethynyl-trimethyl-silane (45 mg, 0.120 mmol) was then added (Scheme 5). The solution was allowed to stir at room temperature overnight. 2 ml of MeOH and potassium carbonate (49.7 mg, 0.360 mmol) were added. The solution was stirred at room temperature for seven hours. The reaction mixture was quenched with 10 ml of water and extracted with EtOAc (3 × 30 ml). The solvent was evaporated under reduced pressure. The sample was purified by flush chromatography using a BIOTAGE SP1 purification device and a 10 g normal phase silica SNAP column (DCM-EtOH solvent system with a gradient rising from 0–10% of EtOH in 15 CV). After evaporation of the solvent, 15 mg of N-[3-chloro-4-[(3-fluorophenyl)methoxy]phenyl]-6-[5-[[[2-ethynyl-4-[3-(trifluoromethyl)diazirin-3-yl]phenyl]methyl-(2-methylsulfonylethyl)amino]methyl]-2-furyl]quinazolin-4-amine (4) was isolated as a yellow solid (yield = 14.5%).
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