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Tritium
Selected Abstracts10th international symposium on the synthesis and applications of isotopes and isotopically labelled compounds,Professor John R. Jones memorial lectures, Monday, June 15, 2009JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5-6 2010David Hesk Session Chair Abstract The first Session of the Conference was dedicated to the memory of Professor John R. Jones. Labelling with Deuterium and Tritium was the common theme. William J.S. Lockley, Frank Tang and Shuiyu Lu gave presentations. Copyright © 2010 John Wiley & Sons, Ltd. [source] Synthesis and characterization of tritium labeled 2,3,4,9-tetrahydro-1H -carbazoles as potent DP receptor antagonistsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 2 2004Carl Berthelette Abstract Tritium labeled 2,3,4,9-tetrahydro-1H -carbazole 1a and 2a were prepared in good yields with a specific activity of 7.0 Ci/mmol (214 GBq/mmol) and 4.2 Ci/mmol (155 GBq/mmol), respectively. Both compounds have been synthesized in high radiochemical purity by catalytic tritium,bromine exchange of the corresponding aryl bromide precursors. The 6-bromocarbazole precursors 7 and 8 were prepared as a mixture by a three step process, involving regioselective bromination of 3c with pyridinium tribromide, oxidation of thioether 4c using m -CPBA and hydrolysis of acylsultamcarbazole 5c. Finally, HPLC separation of the enantiomers afforded the 6-bromo precursors 7 and 8 in high diastereomeric ratio (dr 99% and dr 93% respectively). Copyright © 2004 John Wiley & Sons, Ltd. [source] Mitigation of Electromagnetic Instabilities in Fast Ignition ScenarioCONTRIBUTIONS TO PLASMA PHYSICS, Issue 3-4 2005C. Deutsch Abstract We address the issues of collective stopping for intense relativistic electron beams (REB) used to selectively ignite precompressed deuterium + tritium (DT) fuels. We investigate the subtle interplay of electron collisions in target as well as in beam plasmas with quasi-linear electromagnetic growth rates. Intrabeam scattering is found effective in taming those instabilities, in particular for high transverse temperatures. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] 5,7-dihydroxytryptamine lesions enhance and serotonergic grafts normalize the evoked overflow of acetylcholine in rat hippocampal slicesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2002Anja Birthelmer Abstract Adult rats were subjected to intracerebroventricular injections of 5,7-dihydroxytryptamine (5,7-DHT; 150 µg) and, 15 days later, to intrahippocampal grafts of fetal raphe cell suspensions. About 11 months later, we assessed baseline and electrically evoked release of tritium ([3H]) in hippocampal slices, preloaded with tritiated ([3H])choline or [3H]serotonin (5-HT), in the presence or absence of the 5-HT1B receptor agonist CP-93,129 and the 5-HT receptor antagonist methiothepine. HPLC determinations of monoamine concentrations were also performed. The lesions reduced the concentration of 5-HT (,90%) and the accumulation (,80%) as well as the evoked release (,90%) of [3H]5-HT. They also decreased the inhibitory effects of CP-93,129 on the evoked release of [3H]5-HT. Most interestingly, they facilitated the evoked release of [3H]acetylcholine (+20%). In slices from rats subjected to lesions and grafts, the responsiveness of the serotonergic autoreceptors (presumably located on the terminals of the grafted neurons) and the release of acetylcholine were close to normal. These results confirm that grafts rich in serotonergic neurons may partially compensate for the dramatic effects of 5,7-DHT lesions on serotonergic hippocampal functions. The lesion-induced reduction of the 5-HT1B autoreceptor-mediated inhibition of evoked 5-HT release may be an adaptation enhancing serotonergic transmission in the (few) remaining terminals. The facilitated release of acetylcholine is probably caused by a reduced serotonergic tone on the inhibitory 5-HT1B heteroreceptors of the cholinergic terminals. When related to data in the literature, this facilitation may be of particular interest in terms of transmitter-based strategies developed to tackle cognitive symptoms related to neurodegenerative diseases. [source] Utilization of Decadal Tritium Variation for Assessing the Residence Time of Base FlowGROUND WATER, Issue 3 2007S. Rose An iterative algorithm is presented that allows the user to model the subsurface residence time of shallow ground water comprising stream base flow based on decadal scale variation of tritium concentrations. The algorithm accounts for the effects of radioactive decay, the shallow subsurface mixing of ground water with precipitation, and ground water flux. The inverse of the best-fitting modeled flux through the saturated zone is equivalent to the residence time. The data required for this model include at least two measurements of tritium in base flow for a given stream location made at least a decade apart and the long-term tritium input in precipitation for the region of interest. The model is sensitive to relatively small changes in tritium concentrations and is limited by analytic uncertainties to an accuracy of approximately ±5 years. The algorithm was applied to stream base flow for several basins in the Piedmont Province of Georgia in which tritium concentrations were measured during the early 1990s and again in the 2000s. The model results produced highly concordant residence times for three hydrogeologically similar basins in the Upper Ocmulgee Basin in North Central Georgia. The best estimate of the average residence time for ground water comprising base flow in this Piedmont basin using this new method is between approximately 14 and 18 years. These results are generally consistent with calculations made in previous studies, and these relatively long residence times can be attributed to the storage of water in the clay soils that dominate Piedmont Province watersheds. [source] Chemical and Isotopic Constraints on the Origin of Wadi El-Tarfa Ground Water, Eastern Desert, EgyptGROUND WATER, Issue 5 2000M. Sultan We evaluated the use of the renewable ground water resources of the Eastern Desert to develop sustainable agriculture in Upper Egypt, an alternative that could alleviate some of Egypt's dependence on water from the Nile River. Ground water from shallow aquifers in the Eastern Desert of Egypt, near the intersection of Wadi El-Tarfa and the Nile River, was analyzed for chemical compositions, stable isotope ratios, and tritium activities. The ground water has a range in total dissolved solids of 300 to 5000 mg/L. Values of ,D and ,18O range from -10 to +34 %o and -2 to +5.2 %o, respectively, and defines a line having a slope of 5.7 that intersects the meteoric water line at about ,D = -15 %o on a plot of 8D versus ,18O. These findings indicate that the water might have been derived by a combination of evaporation of and salt addition to regional precipitation. Only one sample could have been derived directly by evaporation and transpiration of modern Nile River water. Salinization of the ground water could have occurred through dissolution of marine aerosol dry fallout, carbonate minerals, gypsum, and other trace evaporitic minerals at and near the ground surface. Tritium activities ranged from 0.04 to 12.9 TU (tritium unite), indicating that all but one of the samples were derived at least partly from precipitation that occurred within the last 45 years. These data indicate that Nubian Aquifer paleowater is not a significant component of the shallow aquifers of this portion of the Eastern Desert. The most likely source of this ground water is sporadic flash flood events yielding locally voluminous recharge that accumulates in coarse sediments and fractured rock beneath alluvial channels. The magnitude of this renewable ground water resource and its potential for supporting sustainable agriculture require further investigation. [source] Environmental isotopic and hydrochemical characteristics of groundwater systems in Daying and Qicun geothermal fields, Xinzhou Basin, Shanxi, ChinaHYDROLOGICAL PROCESSES, Issue 22 2010Dongmei Han Abstract The conceptual hydrogeological model of the low to medium temperature Daying and Qicun geothermal fields has been proposed, based on hydrochemical characteristics and isotopic compositions. The two geothermal fields are located in the Xinzhou basin of Shanxi, China and exhibit similarities in their broad-scale flow patterns. Geothermal water is derived from the regional groundwater flow system of the basin and is characterized by Cl·SO4 -Na type. Thermal water is hydrochemically distinct from cold groundwater having higher total dissolved solids (TDS) (>0·8 g/l) and Sr contents, but relatively low Ca, Mg and HCO3 contents. Most shallow groundwater belongs to local flow systems which are subject to evaporation and mixing with irrigation returns. The groundwater residence times estimated by tritium and 14C activities indicate that deep non-thermal groundwater (130,160 m) in the Daying region range from modern (post-1950s) in the piedmont area to more than 9·4 ka BP (Before Present) in the downriver area and imply that this water belong to an intermediate flow system. Thermal water in the two geothermal fields contains no detectable active 14C, indicating long residence times (>50 ka), consistent with this water being part of a large regional flow system. The mean recharge elevation estimated by using the obtained relationship Altitude (m) = , 23·8 × ,2H (, ) , 121·3, is 1980 and 1880 m for the Daying and Qicun geothermal fields, respectively. The annual infiltration rates in the Daying and Qicun geothermal fields can be estimated to be 9029 × 103 and 4107 × 103 m3/a, respectively. The variable 86Sr/87Sr values in the thermal and non-thermal groundwater in the two fields reflect different lithologies encountered along the flow path(s) and possibly different extents of water-rock interaction. Based on the analysis of groundwater flow systems in the two geothermal fields, hydrogeochemical inverse modelling was performed to indicate the possible water-rock interaction processes that occur under different scenarios. Copyright © 2010 John Wiley & Sons, Ltd. [source] Steady- and unsteady-state lumped parameter modelling of tritium and chlorofluorocarbons transport: hypothetical analyses and application to an alpine karst aquiferHYDROLOGICAL PROCESSES, Issue 17 2005N. Nur Ozyurt Abstract Determination of a groundwater's mean residence time with the aid of environmental tracers is common in hydrogeology. Many of the lumped parameter (LP) applications used for this purpose have been based on steady-state models. However, the results may be misleading if a steady LP model is used to simulate the environmental tracer transport in an unsteady aquifer. To test this hypothesis, the results of steady and unsteady versions of several LP models were evaluated theoretically and in an alpine karst aquifer case by using tritium, oxygen-18 and chlorofluorocarbons (CFCs). The results reveal that the mean residence times obtained may be significantly different between the steady and unsteady versions of the same model. For the karst aquifer investigated, a serially connected exponential and a plug flow model were run under unsteady conditions. It is shown that outflux calibration with an unsteady model provides a firm basis in evaluating the results of models. An outflux-calibrated unsteady model predicted reasonably the observed series of water isotopes. The calibrated model's CFCs output overpredicts the observed concentrations, probably because of the time lag in the unsaturated zone of the alpine karst aquifer. Copyright © 2005 John Wiley & Sons, Ltd. [source] A simple hermetic sample holder for X-ray diffraction analysis of uranium hydrideJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2007Bingyun Ao In order to help resolve unknowns regarding aging effects of uranium during long-term storage of tritium, a number of experiments have been carried out by several researchers. However, almost no literature is available on the structural change of uranium tritide, mainly because its high toxicity and air-sensitivity render appropriate experiments very difficult. In this paper, a simple hermetic sample holder that fits the Philips X'Pert Pro X-ray diffractometer is described. It may be used to study the aging effects of uranium tritide during storage. The sample holder mainly consists of an aluminium container for sample storage and a Mylar window for X-ray measurements. This sample holder can also be used with other air-sensitive, radioactive and toxic materials. In this paper, the first results obtained from X-ray diffraction analysis of uranium hydride are presented. [source] Labelling of the guanylate cyclase activator cinaciguat (BAY 58-2667) with carbon-14, tritium and stable isotopesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 3 2010D. Seidel Abstract For studies of pharmacokinetics and drug metabolism of the new soluble guanylate cyclase activator cinaciguat (BAY 58-2667) the 14C-labelled compound was synthesized. The tritiated compound was required to elucidate the mode of action and the stable labelled compound was required for bio-analytical studies by quantitative mass spectrometry as well. Two radiosyntheses are described with different formation of the labelled intermediate 1-(chloro[14C]methyl)-4-(2-phenylethyl)benzene. The first one started with 14C-carboxylation of 1-bromo-4-(2-phenylethyl)benzene yielding the desired product in 5 steps. In the second synthesis intermediate 1-(chloro[14C]methyl)-4-(2-phenylethyl)benzene was formed by chloromethylation of bibenzyl with [14C]paraformaldehyde/hydrochloric acid subsequently resulting in the final product in three steps. Tritium labelling was performed by tritium exchange of the diester intermediate using an organo-iridium catalyst and subsequent saponification. The stable labelled compound was synthesized via a convergent synthesis starting with 13C,15N-cyanation of 1-(chloromethyl)-2-{[4-(2-phenylethyl)benzyl]oxy}benzene and 13C-cyanation of methyl 4-bromobenzoate, respectively. The labelled product was obtained after 7 chemical steps. Copyright © 2010 John Wiley & Sons, Ltd. [source] Preparation of high specific activity tritium labeled 6,,9,-difluoro-11,,21-dihydroxy-16,,17-[(1-methylethylidene)bis(oxy)]pregna-1,4-diene-3,20-one, fluocinolone acetonideJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 4 2009D. Zhong Abstract Fluocinolone acetonide was tritiated by selective reduction of the 1,2-double bond of the O -protected analog under tritium, followed by re-establishment of the 1,2-double bond and deprotection. Protection of both hydroxyl functionalities was required. The product was obtained with specific activity 36.8,Ci/mmol. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis of tritium- and deuterium-labeled budesonideJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2008Bachir Latli Abstract Tritium-labeled budesonide was prepared by the selective reduction of a double bond in the butenylenedioxy side chain using carrier-free tritium and palladium on carbon as a catalyst in absolute ethanol. Although the reduction gave a mixture of the desired product and the expected byproducts resulting from over reduction of the other double bonds in ring A, the desired tritium-labeled budesonide was easily isolated by reverse phase HPLC and with specific activity of 54,Ci/mmol. [D8]-budesonide was prepared from 16,-hydroxyprednisolone and D8 -butyraldehyde in 1,4-dioxane in the presence of perchloric acid. The isotopic enrichment was found to be more than 99,atom% D. Copyright © 2008 John Wiley & Sons, Ltd. [source] Solid-phase reactions as approach to the synthesis of organic compounds labelled with tritium,JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 9-10 2007Nikolay F. Myasoedov Abstract The solid-phase method for hydrogenolysis, hydrogenation and isotope exchange reactions is described. Its potential for tritium labelling of organic compounds including lipids, nucleotides, amino acids, peptides and pharmaceuticals is demonstrated. The influence of the reaction conditions on the yield and specific radioactivity of the labelled compounds is considered. It is shown that results can be interpreted by the dependence of tritium spillover reactions on the nature of the initial compound and other factors. Copyright © 2007 John Wiley & Sons, Ltd. [source] The synthesis of dopaminergic radioligands labelled with tritium and iodine-125JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 8 2007Crist N. Filer Abstract The preparation of dopaminergic ligands radiolabelled with either tritium or iodine-125 has been an extremely important undertaking to advance understanding of this critical receptor class and the topic is reviewed from 1976 through 2006. Although not an exhaustive compilation of references, the cited examples highlight the many methods employed to prepare these useful reagents. Copyright © 2007 John Wiley & Sons, Ltd. [source] A novel asymmetric synthesis of tritium and carbon-14 labeled (R)-ibuprofenJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 3 2006Yinsheng Zhang Abstract An efficient asymmetric synthesis of tritium and carbon-14 labeled R -ibuprofen was achieved in good overall yield (15% and 47%, respectively) and excellent enantiomerical excess (>98% e.e.), using (4R, 5S)-4-methyl-5-phenyl-2-oxazolidinone as a chiral auxiliary. Copyright © 2006 John Wiley & Sons, Ltd. [source] High specific activity tritium labeling of vitamin D derivative RO275646,JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 14 2005Steve A. de Keczer Abstract The octahydroindenone intermediate was tritium labeled using T2O isotope exchange labeling, and then elaborated to the vitamin D derivative RO275646. Though this method of labeling was expected to give the minor isomer, it was the shortest and most convenient route to the high specific activity metabolically stable labeled sites. A total of 34 mCi (from two separate runs) at 64 Ci/mmol of [3H]-RO275646 were prepared by this method. Copyright © 2005 John Wiley & Sons, Ltd. [source] Synthesis of tritium labelled CHS 828 and its prodrug EB 1627JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 11 2005Søren Christian Schou Abstract The potent antitumoral cyanoguanidine CHS 828 and its prodrug EB 1627 have successfully been labelled with tritium. The pyridyl-3,5-dibromo derivative of CHS 828 was debrominated with tritium-gas using Pd/C catalyst to give [pyridyl -3,5- 3H2]-CHS 828 with a radiochemical purity of 99.3% and a specific activity of 1960 GBq/mmol. Similarly, the pyridyl-3-bromo derivative of the prodrug EB 1627 was debrominated with tritium-gas to give [pyridyl -3- 3H]-EB 1627 with a radiochemical purity of 98.1% and a specific activity of 894 GBq/mmol. Copyright © 2005 John Wiley & Sons, Ltd. [source] Fast and efficient tritium labelling of the nonsteroidal anti-inflammatory drugs naproxen, tolmetin, and zomepiracJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 8 2005Steen K. Johansen Abstract Fast and efficient tritium labelling of the nonsteroidal anti-inflammatory drugs naproxen, tolmetin and zomepirac is reported. Naproxen along with its (R)-enantiomer were labelled by catalytic tritium,halogen exchange of the corresponding 5-bromo derivatives providing [3H]naproxen with a specific activity of 25.4 Ci/mmol. Tolmetin and zomepirac were labelled by the hydrogen isotope exchange reaction using Crabtree's catalyst. This provided [3H]tolmetin and [3H]zomepirac with specific activities of 80.8 and 64.3 Ci/mmol, respectively. All compounds were obtained in high radiochemical purity (>98%). Copyright © 2005 John Wiley & Sons, Ltd. [source] Synthesis of deuterium, tritium, and carbon-14 labeled BIRB 796, a p38 MAP kinase inhibitorJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 12 2004Bachir Latli Abstract 1-(5- tert -Butyl-2- p -tolyl-2H-pyrazol-3-yl)-3-[4-(2-morpholin-4-yl-ethoxy)naphthalen-1-yl]urea (BIRB 796), currently in clinical trials for the treatment of inflammatory diseases, is a potent inhibitor of p38 MAP kinase. Labeled BIRB 796 with stable and radioactive isotopes was required for metabolism, distribution, and absorption studies. We first report the synthesis of carbon-14 labeled BIRB 796 with a specific activity of 2 GBq/mmol (54.2 mCi/mmol), using [14C]-phosgene under modified Schotten,Baumann conditions; second the preparation of tritium-labeled BIRB 796 with a specific activity of 659 GBq/mmol (17.81 Ci/mmol) by reductive dehalogenation of iodo-BIRB 796 with tritium gas; and finally, the synthesis of 2H8 -BIRB 796 using morpholine-2,2,3,3,5,5,6,6- 2H8 with isotopic enrichment of 98.9 at% 2H. Copyright © 2004 John Wiley & Sons, Ltd. [source] The synthesis of tritium labelled neurokinin-1 receptor ligandsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 2 2004Terence G. Hamill Abstract Radiolabelled neurokinin-1 (NK1) receptor antagonists 1b and 2b were required for in vitro/in vivo characterization to support the development of 1a and 2a as fluorine-18 labelled PET ligands. These tritium labelled compounds were synthesized from aryl iodide precursors giving the final tritiated tracers with specific activities of 28 (1b) and 14 (2b) Ci/mmol. Copyright © 2004 John Wiley & Sons, Ltd. [source] Synthesis and characterization of tritium labeled 2,3,4,9-tetrahydro-1H -carbazoles as potent DP receptor antagonistsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 2 2004Carl Berthelette Abstract Tritium labeled 2,3,4,9-tetrahydro-1H -carbazole 1a and 2a were prepared in good yields with a specific activity of 7.0 Ci/mmol (214 GBq/mmol) and 4.2 Ci/mmol (155 GBq/mmol), respectively. Both compounds have been synthesized in high radiochemical purity by catalytic tritium,bromine exchange of the corresponding aryl bromide precursors. The 6-bromocarbazole precursors 7 and 8 were prepared as a mixture by a three step process, involving regioselective bromination of 3c with pyridinium tribromide, oxidation of thioether 4c using m -CPBA and hydrolysis of acylsultamcarbazole 5c. Finally, HPLC separation of the enantiomers afforded the 6-bromo precursors 7 and 8 in high diastereomeric ratio (dr 99% and dr 93% respectively). Copyright © 2004 John Wiley & Sons, Ltd. [source] Synthesis of tritium labelled 3(R)-HETE and 3(R),18(R/S)-DiHETE through a common synthetic routeJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2004Natalya V. Groza Abstract An efficient procedure for the synthesis of 3-hydroxyoxylipins labelled with tritium on all double bond positions is reported. The synthetic scheme involves a joint route for the formation of tetraacetylenic precursors followed by stereoselective reduction of the triple bonds either with hydrogen or tritium. The final tritiated products were obtained with specific activities ranging from 1.65 to 1.80 Ci/mmol. Copyright © 2003 John Wiley & Sons, Ltd. [source] Synthesis and evaluation of tritium labelled 10-methylgalanthamine iodide: a novel compound to examine the mechanism of interaction of galanthamine derivatives with the nicotinic acetylcholine receptorsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 12 2003Andreas Schildan Abstract A new promising galanthamine derivative, 10-[3H]methylgalanthamine iodide, was synthesized for binding studies to nicotinic acetylcholine receptors expressed in Torpedo electric ray electroplaques. Galanthamine was reacted with [3H]methyl iodide to yield 10-[3H]methylgalanthamine iodide with a radiochemical yield of >70% and a specific activity of 32 Ci/mmol after purification via solid phase extraction. To test the ligand properties of the radioligand, calcium imaging and electrophysiology of the non-radioactive analogue were performed to obtain an EC50 of 270 nM, a Hill coefficient of 1.9 and the induced cell current. Copyright © 2003 John Wiley & Sons, Ltd. [source] Enzymatic synthesis of l-tryptophan and 5prime-hydroxy-l-tryptophan labeled with deuterium and tritium at the alpha-carbon positionJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 8 2003E. Boroda Abstract The enzymatic synthesis of l-tryptophan and its derivative 5,-hydroxy-l-tryptophan labeled with deuterium and tritium at the ,-carbon position is reported. The mixture containing S -methyl-l-cysteine, indole or 5-hydroxyindole dissolved in deuteriated or tritiated water has been converted to [2- 2H]-l-tryptophan, [2- 3H]-l-tryptophan, 5,-hydroxy-[2- 2H]-l-tryptophan, and 5,-hydroxy-[2- 3H]-l-tryptophan, respectively, in a one-pot reaction using the enzyme tryptophanase. The same reaction carried out in heavy water with THO added yielded either doubly labeled [2- 2H/3H]-l-tryptophan or 5,-hydroxy-[2- 2H/3H]-l-tryptophan. Copyright © 2003 John Wiley & Sons, Ltd. [source] Preparation of tritium-labelled BIIL 260 of high specific radioactivityJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 3 2003V.P. Shevchenko Abstract Various approaches to the synthesis of tritium-labelled BIIL 260 with high specific radioactivity were investigated. Attempts to incorporate tritium directly into BIIL 260 were made by solid-phase isotope exchange with tritium gas and by isotope exchange with tritiated water which yielded a final product with specific activities ranging from 2 to 7 Ci/mmol. However, the solid-phase and liquid-phase dehalogenations of an appropriate synthon fragment of BIIL 260 followed by its subsequent conversion to the final product via chemical synthesis yielded the desired tritium-labelled BIIL 260 with specific activities of 25 or 71 Ci/mmol, depending upon the precursors and methods used in the dehalogenation step. Copyright © 2002 John Wiley & Sons, Ltd. [source] Synthesis of tritium labelled zaleplonJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 11 2002V.P. Shevchenko Abstract The reaction conditions for the incorporation of tritium into zaleplon have been investigated. The methods studied were the catalytic isotope exchange reaction with tritium gas and catalytic isotope exchange reaction with tritiated water. The results showed that the latter method was the method of choice giving a compound with a higher specific activity and a better yield. Copyright © 2002 John Wiley & Sons, Ltd. [source] A new practical tritium labelling procedure using sodium borotritide and tetrakis(triphenylphosphine)palladium(0)JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 14 2001Tohru Nagasaki Abstract A simple, mild and versatile new tritium (3H) labelling method on a micro scale using sodium borotritide (NaB3H4) and a transition,metal complex catalyst is described. 3H-labelled compounds were prepared effectively by 3H hydrogenolysis of appendant functional groups in target compounds. The appendant functional group such as bromo, iodo or sulfonate in various target compounds can be replaced by tritium (3H) in moderate yields. The new method was established by optimization of the reaction conditions and examination of its applicability using four types of model substrates in tracer runs. Then, various drug candidates and ligands for drug discovery were labelled with tritium on a micro scale. The specific radioactivity of the 3H-labelled compounds used for the studies on receptor binding ranged from 12 to 20 Ci/mmol. Copyright © 2001 John Wiley & Sons, Ltd. [source] Synthesis of tritium labelled delta sleep-inducing peptideJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 7 2001Matthieu Giraud Abstract The ,,, -dehydro precursor of the delta sleep-inducing peptide (DSIP) for tritiation was prepared prior to tritiation using a 3+6 fragment coupling strategy on a solid support. The first fragment, ,,, -dehydrotripeptide, was prepared in solution in five steps in 79% overall yield while the second fragment was obtained by a step by step peptide synthesis on a Wang resin using an Fmoc strategy. The ,,, -dehydrotripeptide was coupled to the fragment linked to the resin, followed by a deprotection/cleavage step to yield the ,,, -dehydro-DSIP, 7. Catalytic reduction of unsaturated DSIP using tritium gas and palladium oxide as catalyst gave [3H]DSIP having a specific activity of 1.184 TBq/mmol(32 Ci/mmol). Copyright © 2001 John Wiley & Sons, Ltd. [source] Synthesis and characterization of [phenyl- 3H] clonidine hydrochloride at high specific activityJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2001Crist N. Filer Abstract p-Aminoclonidine hydrochloride 1 was converted to m-dibromo-p-iodoclonidine 3 and the latter was used as a precursor to prepare [phenyl- 3H] clonidine hydrochloride 4 at high specific activity via a selective catalytic dehalogenation with tritium. Copyright © 2001 John Wiley & Sons, Ltd. [source] Synthesis of [phenyl-2- 3H]-travoprost: isopropyl ester prodrug of a selective prostaglandin FP receptor agonistJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 3 2001Robert Selliah Abstract A method for the preparation of tritium labeled travoprost, a new ocular hypotensive prostaglandin, is described. A highly selective catalytic deiodination has been identified which provides [phenyl-2- 3H]-travoprost in a single synthetic step from 2,-iodo-travoprost. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||||||||