摘要:

AbstractA range of organic substrates was successfully exchanged with tritium gas using NaBH4‐reduced palladium oxide or chloride as catalyst. Exchange conditions involved a reaction temperature of 100 °C, a reaction time of 3 days, and products were analyzed by radio‐gas chromatography and3H NMR spectroscopy. Both aromatic and aliphatic compounds underwent exchange, 18 of the 22 substrates incorporated>35% of the available tritium, and most products showed high radiochemical purity.3H NMR analyses showed that both alkanes and the alkyl chains of alkylbenzenes were rapidly and evenly labelled. Some aromatic compounds showed general ring exchange while others showed high specificity. These results for bulk palladium catalyst are strikingly different from those obtained with bulk platinum and supported palladium catalysts. The results are discussed in terms of currently accepted mechanisms of heterogeneous metal catalyzed hydrogen isotope exchange react

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360102

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA practical method for the solid‐phase synthesis and purification of14C labeled oligonucleotides is described. A streamlined procedure for the synthesis of 5′‐O‐dimethoxytrityl‐2‐(14C)‐thymidine 3′‐(2‐cyanoethyl‐N,N‐diisopropyl) phosphoramidite from commercially available 2‐(14C) labeled thymidine nucleoside is detailed. Methodology for the manual synthesis, isolation, and purification of a high specific activity oligonucleotide phosphorothioate 20‐mer

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360103

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe paper describes the first method for n.c.a11C‐ring labelling of benzenioid compounds having a reactive group for further derivatization by use of the known principle of synchronous six‐electron cyclization of hexatriene systems into aromatics. Nitro‐[11C]methane (1) prepared from cyclotron‐produced [11C]carbon dioxide reacts in the presence of t‐BuOK with 5‐dimethylaminopenta‐2,4‐dienylidene‐dimethylammonium perchlorate (2) to form 6‐nitro‐1‐dimethylamino‐[6‐11C]hexatriene (3) follow by cyclization/ aromatization into nitro‐[1‐11C]‐benzene (4) at increased temperatures. Starting from1, nitro‐[1‐11C]benzene of a radiochemical purity of about 92 % and a mean specific radioactivity of 1 Ci/μmol was obtained within 7 min. Related to [11C]CO2, the reproducible radiochemical yield of4(decay‐corrected) was 80±5 %. Reduction of4by heating the above reaction mixture with aqueous Na2S gave [1‐11C]aniline (5) of aradiochemical purity of about 81 %. The reproducible radiochemical yield of5(decay‐corrected) in relation to [11C]CO2w

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360104

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractRadiolabelled raloxifene (LY156758) has been prepared by tritium gas hydrogenolysis of a 3‐aroyl‐bis‐brominated precursor. The requisite halogenated intermediate was accessed by regioselective aroylation of benzothiophene6with the acid chloride of 3,5‐dibromo‐4‐[2‐(1‐piperdinyl)ethoxy]benzoic acid (5). Selective deprotection of the aryl methyl ethers in the presence of the ethoxy side‐chain followed by palladium catalyzed halogen‐tritium exchange provided the target compound with a specific activ

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360105

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractA facile synthesis of the antiinflammatory agent RS‐42169‐14C, based on a carbonation/cycloaddition sequence is described. The product was obtained in 36% yield from Ba14CO3at a specific activity of 52 mCi/mmole. The design of the six step sequence was such that pure intermediates were isolated by extractive workup, and only a single chromatographic purification was requi

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360106

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

Abstract1,2,3,6‐Tetrahydro‐4‐[U‐14C]phenylpyridine (12) was synthesized and coupled to (R)‐3‐phenyl‐3‐cyclohexene‐1‐carboxylic acid to make the titled compound7in 21% overall yield. Purification considerations were an important factor in the choice of a reaction sequence to7, and successful synthesis was facilitated by the superiority of BF3.OEt2as dehydrating reagent in this system. This otherwise problematic sequence offers an efficient and simple route to c

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360107

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractAn experimental method is described for the synthesis of195mPt‐radiolabeledcis‐diammine(1,1‐eyclobutanedicarboxylatio) platinum(II) (carboplatin). 10 mg of 95 % enriched194PT was irradiated for 75 h in the hydraulic conveyer of KUR at a thermal neutron flux of approx.8.15 × 1013n'cm−2'sec−1, and the195mPt‐radiolabeled carboplatin was synthesized and purified using HPLC (column; C18‐ODS). The chemical yield was higher than 59.1 %, its chemical purity was greater than 99.3 %, the radionuclidic purity was nearly 100 % and the specific activity was 6.0 MBq, m

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360108

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

Abstract2H and3H labeledZ‐ andE‐1,1‐dichloro‐2,3‐diphenylcyclopropane (1and2) were synthesized starting from NaB2H4and NaB3H4reduction of benzil. The resulting glycols were transformed to the 1,2‐labeled Z‐ and E‐stilbenes by thermolysis of their cyclic thionocarbonates in trimethylphosphite. The stilbenes were reacted with phase transfer‐generated dichlorocarbene to form the title compounds. The dideuterio isomers were separated by fractional crystallization in yields of 60 and 48%. Each was greater than 99 % geometrically and 98 % isotopically pure. The ditritio isomers were separated by C‐18 JPLC. The radiochemical yields, on a molar basis using benzil as the limiting reagent, were 42 % and 23 %, each with specific activity of 88.5 mCi/mmol and radioche

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360109

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractTritium labelling of buprenorphine, a mixed agonist‐antagonist opioid ligand, was performed with a specific activity of 2.35 TBq/mmol (63.6 Ci/mmol) starting with 15,16‐didehydrobuprenorphine. Labels at positions 15 and 16 of the morphine skeleton proved to be sufficiently stable under strong acidic or basic conditi

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360110

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

Abstract4‐15N‐2,3,5‐Trimethylpyrazine (1) was synthesized by dechlorination of 4‐15N‐6‐chloro‐2, 3, 5‐trimethylpyrazine (5) the key intermediate, derived from15N‐DL‐alanine (3).1‐15N‐2,3,5‐Trimethylpyrazine (2) was prepared by decarboxylation of 1‐15N‐2, 3, 5‐trimethyl‐pyrazine‐6‐carboxylic acid (10) obtained by the Pummerer type rearrangement of 1‐15N‐tetramethylpyrazine 1‐oxide (1) followed by oxidation.1‐ And 4‐oxides and 1,4‐dioxides of the above15Ntrimethylpyrazines were also obtained by treatment with sodium perborate in acetic acid.15N NMR spectra of the compounds thus prepared were measured an

ISSN:0362-4803    

DOI:10.1002/jlcr.2580360111

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY