bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthese biologique des acides ferulique et sinapique marques AU 14C
Authors: Marigo G. , Boudet D. Riviere 
Published: October 2006

Abstract14CH3 labelled ferulic and sinapic acids have been synthesized through an enzymic methylation of caffeic and 5‐hydroxyferulic acids using labelled S‐adenosyl methionine as 14CH3 donor. The methyltransferases involved which were extracted from stems of Poplar catalyse these reactions with a good efficiency. A purification procedure of 14C S‐adenosyl methionine is described which allows the recycling of 14CH3 donor. The yield of the overall process is therefore greatly improved. This method allows the synthesis of products with high specific radioactivity.Les acides férulique et sinapique marqués au 14C sur le groupement méthyle ont été synthétisés par voie enzymatique à partir des acides caféique et 5‐hydroxyférulique en utilisant la S‐adénosyl méthionine radioactive comme donneur de 14CH3. Le biocatalyseur utilisé, la O‐méthyltransférase, est issu de tiges de Peuplier. Dans les conditions optimales de la réaction, cette enzyme est capable d'assurer la formation des deux acides phénoliques avec un rendement intéressant. La mise au point d'un protocole de purification du donneur de 14CH3 permettant sa réutilisation, améliore la rentabilité de ce mode de synthèse dont l'intérět consiste en l'obtention de produits d'activité spécifique élevée.
Yellow mustrad oil as a latent quinone methide: A conventient preparation of p‐hydroxybenzyl [14C]cyanide
Authors: Jaroszewski Jerzy W. , Szancer Joseph , Ettlinger Martin G. 
Published: October 2006

AbstractNaturally derived p‐hydroxybenzyl isothiocyanate, a hitherto unconsidered example of the rare class of stable p‐hydroxybenzylating agents, was used for preparation of labelled p‐hydroxybenzyl cyanide.
Synthesis of 77Br‐labelled 2‐(4‐bromo‐2,5‐dimethoxyphenyl)‐isopropylamine with high specific activity
Authors: Coenen H. H. 
Published: October 2006

AbstractThe tagging of 2,5‐dimethoxyphenylisopropylamine (DPIA) with bromine‐77 (T1/2 = 56 hrs) was reinvestigated in order to achieve high specific activities which are necessary for in‐vivo application of this centrally acting drug. A fast one‐pot synthesis was developed using N‐chlorotetrafluorosuccinimide (NCTFS) and practically carrier‐free bromide to introduce radiobromide into the aromatic ring. Trifluoroacetic anhydride (TFA) was applied both as solvent and as a reversible blocking agent of the free amino group. TFA was also shown to suppress chlorinating sidereactions. Rapid separation of 4‐77Br‐2,5‐dimethoxyphenylisopropylamine was achieved by reverse phase high pressure liquid chromatography. The total labelling and separation procedure takes about two hours, and 4‐77Br‐DOB is obtained with an overall radiochemical yield of 25% and a specific activity of <8 Ci/μmole.
Synthesis of 6,7‐dihydro‐10‐trideuteromethyl‐6, 8, 8‐trimethyl‐8H‐pyrano[3,2‐g]chromone‐2‐carboxylic acid
Authors: Minami Norio 
Published: October 2006

AbstractSynthesis of 6,7‐dihydro‐10‐trideuteromethyl‐6,8,8‐trimethyl‐8H‐pyrano[3,2‐g] chromone‐2‐carboxylic acid (10) in high isotopic purity is described. The trideuteromethylation was achieved by sodium borodeuteride reduction of the ethoxycarbonyl derivative (5) of 7‐hydroxy‐2,2,4‐trimethylchroman‐8‐carboxylic acid (4). This labelled compound (10) is required for use as mass spectrometric stable isotope internal standard for the study of metabolic fate of 6,7‐dihydro‐6,8,8,10‐tetramethyl‐8H‐pyrano[3,2‐g] chromone‐2‐carboxylic acid (9), which is an orally active antiallergic agent.
Biosynthetic methods for incorporating positron‐emitting radionuclides into compounds of biomedical interest
Authors: Gelbard Alan S. 
Published: October 2006

AbstractThe progress that has been made in incorporating the short‐lived, positron‐emitting isotopes N‐13 and C‐11, into biologically active compounds by biosynthetic means is reviewed. These methods include the use of whole cells or plant leaves to carry out a sequence of metabolic reactions, such as nitrogen fixation or photosynthesis, and the use of purified enzymes to catalyze specific chemical reactions, to form the labeled compounds.
Synthesis of (2S, 5R) ‐ [5‐2H] Proline
Authors: Gramatica Paola , Manitto Paolo , Manzocchi Ada , Santaniello Enzo 
Published: October 2006

AbstractThe title compound was obtained by preferential crystallisation of (2RS,5R)‐[5‐2H]proline. The labelled racemic amino acid was synthesized in five steps from (5R)‐[5‐2H]‐2‐pyrrolidone, which was prepared by cyclisation of (4R)‐[4‐2H] GABA. The stereospecific label was introduced into GABA enzymatically decarboxylating in 2H2O (2S)‐glutamic acid, in the presence of glutamate decarboxy lase from E. coli.
Synthese de la pentamethylmelamine (noyau 14C‐4,6), un nouvel agent antitumoral
Authors: Do‐cao‐thang  , Nguyen‐hoang‐nam  , Hoellinger H. , Pichat L. 
Published: October 2006

Abstract(ring‐4,6‐14C) Pentamethylmelamine (14C‐PMM), a new antitumor agent, was prepared from barium (14C) carbonate by a 6 step synthesis. (14CN) Dimethylcyanamide, prepared from sodium (14C) cyanide with 71% yield and treated with phosgene in the presence of hydrogen chloride, was cyclized to (ring‐4,6‐14C)‐2‐chloro‐4,6‐bis (dimethylamino)‐s‐triazine. The latter was purified by silicagel low pressure liquid chromatography (15% yield based on nitrile) and condensed with monomethylamine to give 14C‐PMM. After purification 14C‐PMM was obtained with 91% yield, specific activity = 38 mCi/mMole. The mechanism of the reaction of nitrile with phosgene was discussed.
A simple synthesis of L‐[35S]cysteine sulfinic acid
Authors: Spears Ronald M. , Martin David L. 
Published: October 2006

AbstractThe synthesis of L‐[35S]cysteine sulfinic acid (L‐2‐amino‐3‐[35S] sulfino‐propanoic acid) in 65% yield from S‐[35S]cystine is described. The procedure was designed for use with milligram quantities of starting material and requires no purification of intermediates. L‐[35S]Cystine was converted first to its thiosulfonate. Subsequent reaction of the thiosulfonate with ammonium hydroxide generated L‐[35S]cysteine sulfinic acid and L‐[35S]cystine as the major products. The L‐[35S]cystine was recovered and reprocessed thereby increasing the yield.
Synthesis of 14C‐labeled N‐nitrosobis (2‐oxopropyl) amine
Authors: Nagel D. , Kupper R. 
Published: October 2006

AbstractN‐Nitrosobis (2‐oxopropyl) amine (BOP), a potent and selective pancreatic carcinogen in the Syrian golden hamster was synthesized with a 14C label in the alpha carbon. Oxidation of 2‐hydroxypropyl‐2‐hydroxypropyl‐1‐14C‐amine followed by nitrosation with sodium nitrite and hydrochloric acid gave radiolabeled BOP in 60% yield.
Potential drugs labelled with 14C. II. Synthesis of 1‐cyano‐3‐imino‐8, 9‐dimethoxy‐3, 4,5,6‐ ‐tetrahydro‐thiazolo[4, 3‐a]isoquinoline hydrochloride
Authors: Koltai E. , Zólyomi G. , Komáromy P. , Bánfi D. , Szüts T. , Takács K. 
Published: October 2006

AbstractThe synthesis of 1‐cyano‐3‐imino‐8,9‐dimethoxy‐ ‐3,4, 5,6‐tetrahydro‐thiazolo [4,3‐a]isoquinoline hydrochloride labelled with 14C in five different positions: in position 3 (1a), in the cyano group at position 1 (1b), in position 5 (1c), in position 10b (1d) and in the methoxy groups at position 8 and 9 (1e) was carried out.
Adaptation de methodes classiques a la synthese de glycerophospholipides marques au carbone 14
Authors: Dana J. L. , Pichat L. 
Published: October 2006

AbstractClassical phospholipids syntheses were selected and adapted to the preparation of natural glycerophospholipids labelled with carbon 14 in the acyl moiety. 1,2‐(14C) diacyl‐3‐bromo sn‐glycerol was the starting material.Saturated 14C‐phosphatidyl‐ethanolamine, choline and serine were obtained in 30 %, 25 % and 11 % yields relative to the 14C‐fatty acid, by condensation of a suitably protected amino‐alcohol with a (14C‐diacyl) phosphatidic acid in presence of triisopropyl‐benzenesulfonyl‐chloride followed by deprotection of the amino group.The synthesis of unsaturated (or mixed) 14C phosphatidyl ethanolamine was achieved, with a 28 % yield, by condensation of the 14C‐diacyl‐bromoglycerol with the silver salt of the N‐trityl aminoethyl and benzyl diester of phosphoric acid and subsequent deprotections.
Tritium labelled compounds of high specific activity I. Tofizopam
Authors: Zólyomi G. , Horváth Gy. , Láng T. , Kórösi J. 
Published: October 2006

AbstractThe possibilities of tritium labelling of tofizopam (1) at high specific activity were investigated. Two methods, one by isotopic exchange, and one by catalysed halogen‐tritium replacement were developed. The latter was found to be more rational, and 1 specifically labelled with tritium at a specific activity of 12 Ci/mmole was prepared by applying this route. An attempted labelling by catalysed multiple bond reduction with tritium is also described.
Preparation of selectively side‐chain deuteriated pyridines via pyrylium salts
Authors: Balaban Alexandru T. 
Published: October 2006

AbstractIsotopic exchange of benzylic hydrogens in α‐ and β‐alkyl side‐chains of pyrylium salts occurs readily by heating in deuterium oxide at normal pressure. As β‐hydrogens exchange faster than α‐hydrogens, one may obtain selective (about 90 % isotopic purity) β‐ or α‐deuteriation of side‐chains by direct or reverse isotope exchange. The deuteriated pyrylium salts are converted by aqueous ammonia into the corresponding pyridines without loss of deuterium. Examples presented are : 2,4,6‐tri‐(d3‐methyl)‐, 2,6‐di‐(d3‐methyl)‐4‐methyl‐, 2,6‐dimethyl‐4‐(d3‐methyl)‐, 2,6,‐di‐(d3‐methyl)‐3,5‐dimethyl‐, 2,4,6‐tri‐(d3‐methyl)‐3,5‐di‐methyl‐, 2,6‐di‐(α‐d2‐ethyl)‐4‐(d3‐methyl)‐, 2,6‐diethyl‐4‐(d3‐methyl)‐, and 2,6‐di‐(α‐d2‐ethyl)‐4‐methyl‐pyrylium perchlorates and ‐pyridines.
The use of the acetonide derivative in the preparation of D‐threo‐chloramphenicol‐1‐3H and its nitroso derivative
Authors: Heys J. Richard 
Published: October 2006

AbstractAn efficient synthesis of millimolar quantities of high specific activity D‐threo‐chloramphenicol‐1‐3H is described. The key step is the chromatographic separation of the compound from its 1‐epimer, produced in the Ca(B3H4)2 reduction of chloramphenicol ketone (D‐α‐dichloroacetyl‐amino‐β‐hydroxy‐p‐nitropropiophenone), by use of the acetonide derivative. Stereochemical aspects of the N‐bromosuccinimide oxidation of chloramphenicol to chloramphenicol ketone have been investigated, and the previously reported [1] specific rotation of chloramphenicol ketone has been corrected. The synthesis of nitrosochloramphenicol‐1‐3H is described.
Synthesis of 14C‐labeled 4‐acetyl‐5,6‐bis(4‐chlorophenyl)‐2‐(2‐hydroxyethyl)‐2H‐pyridazin‐3‐one
Authors: Buchman Russell , Evans T. R. 
Published: October 2006

AbstractA simple and convenient synthesis of a radiolabeled antihypertensive pyridazinone was developed. The product was purified chromatographically, and the chemical and radiochemical purities of the sample were determined.
Synthesis of carbon‐14‐labelled antibacterial agent. Synthesis of 1‐ethyl‐ [1‐14C]‐6‐fluoro‐1, 4‐dihydro‐4‐oxo‐7‐ (1‐piperazinyl)‐3‐quinolinecarboxylic acid (14C‐AM‐715)
Authors: Nagatsu Y. , Irikura T. 
Published: October 2006

Abstract1‐Ethyl‐6‐fluoro‐1,4‐dihydro‐4‐oxo‐7‐(1‐piperazinyl)‐ 3‐quinolinecarboxylic acid (I, AM‐715), a new potent antibacterial agent, was labelled with carbon‐14 at the C‐1 position of the N‐ethyl group for metabolic studies. The synthesis was achieved according to two reaction routes. The overall radiochemical yields of 14C‐AM‐715 based on ethyl iodide‐1‐14C from route A and route B, were 29.4% and 9.4%, respectively.
Synthesis of methionines specifically labelled with 2H or 13C
Authors: Billington David C. , Golding Bernard T. , Kebbell Michael J. , Nassereddin Ishaq K. 
Published: October 2006

AbstractEfficient methods for synthesising L‐[methy‐ 13C]methionine from [13C]iodomethane and L‐methionine, and L‐[3,4‐13C2] methionine from [13C2]ethene, are described; the preparation of [3,3‐2H2]methionine and [2,3,3‐2H3]methionine from methionine by an exchange method is detailed.
A simple, one‐step synthesis of 1‐14C‐acetylhydrazine
Authors: Mathiaparanam P. , Wong L. T. , Thomas B. H. 
Published: October 2006

AbstractA synthesis of 1‐14C‐acetylhydrazine by acetylation of hydrazine using 1‐ 14C‐ethyl acetate and a catalytic amount of activated alumina is described.
A novel synthesis of ethanolamine‐2‐14C
Authors: Koltai E. , Horváth B. , Bánfi D. 
Published: October 2006

AbstractEthanolamine‐2‐14C was prepared by the reduction of benzyloxycarbonyl‐glycine‐1‐14C methyl ester. The reduction was carried out with calcium borohydride and the protecting group was removed by hydrogenolysis.
Decay synthesis of carrier‐free 3‐methyl‐ [3H] ‐furan and 2‐methyl‐[3H] ‐furan
Authors: Speranza Maurizio , Angelini Giancarlo , Sparapani Cinzia 
Published: October 2006

AbstractNuclear decay of C3H4 in the presence of gaseous furan represents a simple and convenient synthetic route to carrier‐free multitritiated 3‐methyl‐ and 2‐methyl‐furan. Their application for biological studies appears particularly promising, on account of the favourable characteristics of the followed synthetic approach.
Rapid catalytic synthesis of 11C‐labelled aromatics
Authors: Speranza Maurizio , Ferrieri Richard A. , Wolf Alfred P. , Cacace Fulvio 
Published: October 2006

Abstract11C‐Labelled benzene derivatives were prepared catalytically by trimerizing acetylene‐11C with acetylene and propyne carriers over 1.5 grams of silica‐alumina support activated by potassium chromate (0.2% by weight). Optimized yields of the 11C‐labelled aromatics were obtained when the reactants were exposed to the catalyst for 10 minutes at 24°C. A minimum addition of 50 μmole of alkyne carrier was necessary before the trimerization proceeded to give appreciable yields of 11C‐labelled aromatics. In the competitive trimerization of acetylene‐11C with acetylene and propyne carriers, three 11C‐labelled aromatic products were generated: benzene, toluene, and xylene. From these studies acetylene was observed to be 1.6 times more reactive than propyne. In addition, the observed distribution of 11C‐labelled xylenes (3.4% ortho, 10.6% meta, and 86% para) indicates an apparent regiospecificity in the trimerization of 11C‐acetylene with propyne.
Synthesis of [2‐13C, 2‐14C]2‐aminoethanol, [1‐13C, 1‐14C]2‐chloroethylamine, N,N′‐bis([1‐13C, 1‐14C]2‐chloroethyl)‐N‐nitrosourea(BCNU) and N‐([1‐13C, 1‐14C]2‐chloroethyl)‐N‐nitrosourea(CNU)
Authors: Narayan Ramani , Chang Ching‐Jer 
Published: October 2006

Abstract[2‐13C, 2‐14C]2‐Aminoethanol hydrochloride was prepared in good yield from Na*CN in a two step sequence by first converting the Na*CN to OHCH2*CN and then reducing the nitrile directly with a solution of borane‐tetrahydrofuran complex. The reaction procedure was simple and the pure product could be obtained readily. Using this specifically labelled precursor, the synthesis of [1‐13C, 1‐14C]2‐chloroethylamine hydrochloride, N‐([1‐13C, 1‐14C]2‐chloroethyl)‐N‐nitrosourea(CNU) and N,N′‐bis([1‐13C, 1‐14C]2‐chloroethyl)‐N‐nitrosourea(BCNU) in good yield without isotope scrambling was also reported.
Tritium labelling of psychopharmacologic agents
Authors: Buchman Ouri , Shimoni Michael 
Published: October 2006

AbstractAttempts to reach phenothiazine derivatives labelled with tritium at high specific activity, are described. All the syntheses are based on catalysed dehalogenation procedures. The most encouraging results are those obtained by halogenation of the desired compound followed by catalytic dehalogenation with Pd/C. The specific activities are in the range of 10,000‐40,000 mCi/mmol.
Synthese du dimethindene (indenyl‐14C‐1)
Authors: Mestre P. , Noel J. P. , Pichat L. , Benakis A. 
Published: October 2006

AbstractSynthesis of (1‐14C‐indenyl) dimethindene (7‐14C) benzyl chloride prepared from (14C) barium carbonate is condensed with diethyl sodio malonate to give diethyl (7‐14C) benzyl malonate : 4 in a yield of 78 %. 4 is then alkylated with 2‐dimethylamino 1‐chloroethane to give the diethyl dialkylmalonate : 12. 12 is saponified with sodium hydroxide, decarboxylited by treatment with hot hydrochloric acid and cyclised with polyposphoric acid into 2‐(2‐dimethyl aminoethyl) 3‐(1‐ C) indanone : 8. This indanone is condensed with 2‐(2‐lithioethyl) pyridine, the intermediate is dehydrated into (1‐ C indenyl) Dimethindene which is isolated and purified as its maleate salt. Specific activity is 54 mCi/mMole. Radiochemical purity checked by TLC is better than 99%. The overall yield is 15.8 % based on barium carbonate.
The preparation of carbon‐14 and tritium labelled 1‐[4‐(2‐dimethylaminoethoxy)phenyl]‐1, 2‐diphenyl‐1‐butene [ICI 46,474, tamoxifen (‘nolvadex’)] and the separation of cis‐trans isomers I. The synthesis of carbon‐14 labelled tamoxifen (‘nolvadex’)
Authors: Burns J , Rutter D 
Published: October 2006

AbstractThe preparation of [14C]tamoxifen from [U‐14C]bromobenzene is described. Several preparations of the compound have been made with overall radiochemical yields of 12% ‐ 14%, and specific activities 1.3 to 10.1 mCi/mmol have been obtained.The purification procedures used, including the separation of the cis‐trans isomers by preparative thin layer chromatoqraphy, are also described.
Synthesis of triamcinolone acetonide‐4‐14C
Authors: Rao Pemmaraju Narasimha , Cessac James W. , Hill Kenneth A. 
Published: October 2006

AbstractThe free hydroxyl groups in triamcinolone acetonide (1) were protected as silyl ethers to give the bis‐silyloxy derivative 4. Compound 4 was then hydrogenated over 5% palladium on carbon to give the Δ4‐3‐oxo steroid 5 which was then converted to the enol‐lactone 7 under selective reaction conditions. The enol‐lactone 7 was subjected to Grignard reaction with 14C‐methylmagnesium iodide to give an adduct 8a which on subsequent treatment with lithium 2,6‐di‐t‐butylphenoxide gave 4‐14C‐Δ4‐3‐oxo derivative 9. Compound 9. was heated with selenium dioxide in t‐butanol containing pyridine to give the Δ1,4‐3‐oxo derivative 10. Removal of the silyl protecting groups was readily accomplished by heating 10 with hydrochloric acid in methanol‐tetrahydrofuran solution to give the title compound 11.
Syntheses of some di‐, tetra‐, and hexadeuterio‐octadecenoates
Authors: Dejarlais W. J. , Emken E. A. , Miller W. R. 
Published: October 2006

Abstract(E&Z)‐10‐Octadecenoic‐13,14‐d2, −14,15‐d2, and −14,14,15,15‐d4 acids were prepared by Wittig synthesis. (E&Z)‐11‐Octadecenoic‐14,14,15,15,17,18‐d6 acids were prepared by Wittig synthesis and by synthesis and reduction of 11‐octadecynoic‐14,14,15,15,17,18‐d6 acid. Overall yield in 11‐octadecenoate‐d6 synthesis was better by the Wittig procedure (25% vs. 15%). The Wittig‐produced 11‐octadecenoates had higher hexadeuterio contents than the acetylenic sequence products (85% vs. 70%) but the average isotopic purity was similar (5.9 D/mole). The Wittig method appears better for deuterium‐labelled octadecenoate synthesis.
Synthesis of dexamethasone‐4‐14C
Authors: Rao Pemmaraju Narasimha , Cessac James W. , Hill Kenneth A. 
Published: October 2006

AbstractThe bismethylenedioxy (BMD) derivative of dexamethasone 2 was silylated with trimethylchlorosilane and imidazole in dimethylformamide to give the 11β‐trimethylsilyloxy BMD derivative 3. The Δ1 ‐double bond in 3 was hydrogenated over 5% palladium on carbon to give the Δ4‐3‐oxo steroid 4. Oxidation of 4 with potassium permanganate‐sodium metaperiodate gave the seco‐acid 5 which on subsequent treatment with acetic anhydride; sodium acetate and triethylamine gave the enol‐lactone 6. The enol‐lactone 6 was reacted with 14C‐methylmagnesium iodide to give an adduct 7a which on heating at reflux with lithium 2,6‐di‐t‐butylphenoxide in dioxane gave the Δ4‐3‐oxo derivative 8. Compound 8 was heated at reflux with m‐iodylbenzoic acid and diphenyl diselenide in toluene to give the Δ1,4‐3‐oxo steroid 9. The protecting BMD and silyl groups were removed in a single step by reaction with aqueous trifluoroacetic acid containing 2N hydrochloric acid at room temperature to give dexamethasone‐4‐14C 10.
Synthesis of [4a‐13C]‐6‐methyltetrahydropterin
Authors: Lazarus Robert A. , Sulewski Michael A. , Benkovic Stephen J. 
Published: October 2006

AbstractThe synthesis of [4a‐13C]‐6‐methyltetrahydropterin, a synthetic cofactor for phenylalanine hydroxylase, is described. [2‐13C]‐ethyl bromoacetate was converted in four steps to [5‐13C]‐2,4‐diamino‐6‐hydroxypyrimidine in 86% yield. The latter was nitrosated, reduced, condensed with pyruvic aldehyde, and reduced to afford pure [4a‐13C]‐6‐methyltetrahydropterin in a net overall yield of 16%.
Synthesis and evaluation of 82Br and 77Br labeled (17α, 20E)‐21‐bromo‐19‐norpregna‐1,3,5(10),20‐tetraene‐3,17β ‐diol
Authors: Hanson Robert N. , El‐Wakil Hoda , Murphy Francis , Scott Wilbur D. 
Published: October 2006

Abstract17α ‐E‐Bromovinylestradiol and its radiobrominated analogs were prepared by halodestannylation. The synthesis was achieved by bromination of the tri‐n‐butylstannylvinyl intermediate to give a 90% isolated yield. The reaction of the intermediate with ammonium [82Br] bromide or sodium [17Br] bromide in the presence of an oxidant give the corresponding radiolabeled bromovinylestradiol in 80–90% yields after isolation by HPLC. The radiochemical purity was greater than 98% and no other UV‐active compounds could be detected by HPLC. An in vivo comparison of this compound with the previously prepared 17α ‐E‐[125I]iodovinyl estradiol indicated that the two compounds had similar uterine uptake and specific receptor binding properties. The results suggest that radiobromodestannylation may be the method of choice for the preparation of this and other structurally similar compounds.
Synthesis of [14C] labelled N‐nitro methylamine and N‐nitro dimethylamine
Authors: Braun H. , Plesch W. , Frei E. , Hassel M. , Wiessler M. 
Published: October 2006

AbstractN‐nitro [14C]methylamine was synthesized by the alkaline cleavage of N‐nitro[methyl‐14C] methylurethane obtained by nitration of [N ‐ methyl‐14C] methylurethane. N‐nitro[N‐methyl‐14C]dimethylamine could be obtained by methylation of monomethylnitramine with [14C] diazomethane.
Synthesis of 13C warfarin labelled at the hemiketal carbon, and its resolution
Authors: Savell Van Henry , Valente Edward J. , Eggleston D. S. 
Published: October 2006

AbstractWarfarin (cyclic hemiketal form: 2‐hydroxy‐2‐methyl‐4‐phenyl‐3,4‐dihydro‐2H,5H‐pyrano[3,2‐c][1]benzopyran‐5‐one) is labeled with 98+% 13C at the anomeric carbon (C2) and resolved into its enantiomers. Acetone‐2‐13C(98.6%) condenses with benzaldehyde in aqueous base to produce 4‐phenyl‐3‐buten‐2‐one‐2‐13C(98+%). Michael‐type addition of this to 4‐hydroxycoumarin in methanol produces the labeled diastereomeric warfarin methyl ketals which on deprotection form racemic warfarin‐2‐13C(98+%). Classical resolution of labeled warfarin with quinidine produces partly resolved (S)‐(–)‐warfarin‐2‐13C(98+%). Labeled warfarin is a suitable probe for warfarin configuration for which three distinct isomeric forms are known.
Synthesis of Some 3H labeled 2′, 3′‐dideoxynucleosides of pharmacological interest
Authors: Taylor George F. , Kepler John A. 
Published: October 2006

Abstract[Pyrimidine‐5‐3H]2′, 3′‐dideoxycytidine and [ribose 2,3‐3H]2′, 3′‐dideoxyinosine are prepared by catalytic reduction with tritium gas. [Adenine‐8‐3H]2′3′‐dideoxyadenosine is prepared by catalytic exchange with tritium gas. [Hypoxanthine‐8‐3H]2′,3′‐dideoxyinosine is prepared by the action of adenosine deaminase on [adenine‐8‐3H]2′,3′‐dideoxy‐adenosine.