bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ethyl chlorocarbonate‐14C and its application to the synthesis of N‐methyl‐14C‐amines
Authors: Marshall F. J. , McMahon R. E. 
Published: October 2006

AbstractA convenient method for the preparation of ethyl chlorocarbonate‐14C is described. This has led to a facile synthesis of N‐methyl‐14C secondary amines by lithium aluminum hydride reduction of an intermediate 14C‐carbamate. The reaction has also been employed in the preparation of N‐methyl‐2H3‐ and N‐methyl‐3 H‐amines by using lithium aluminum hydride‐2 H4and lithium aluminum hydride‐3H.
Peptidic hormone interactions at the molecular level‐preparation of highly labelled 3H oxytocin
Authors: Morgat J. L. , Hung Lam Thanh , Cardinaud R. , Fromageot P. , Bockaert J. , Imbert M. , Morel F. 
Published: October 2006

AbstractThe tritium labelling of oxytocin has been attained by a two step procedure. First, di‐iodo oxytocin is prepared. After a survey of various iodination reagents, ICI has been selected as it reacts much more rapidly with the tyrosyl ring than with the disulfide bridge, which under mild conditions remains unaffected. The di‐iodo derivative, nevertheless, has lost most or all of its biological activity. Catalytic substitution of the peptide bound iodine by tritium results in labelling the hormone and in restoration of the biological activity. The 3H oxytocin obtained retains 90 % of its hydrosmotic activity and about 65 % of its avian depressor activity. Its specific radioactivity reaches 36 Ci/mMole, a value allowing further studies of the hormone at a molecular level.
Preparation of some mercuri‐derivatives of fluorescein labelled with isotopes 197Hg or 203Hg. I. Study of preparation methods
Authors: Ratuský J. , Kronrád L. , Málek P. , Vavrejn B. , Kolc J. 
Published: October 2006

AbstractA method for preparation of mercuri‐derivatives of fluorescein labelled by 197Hg or 203Hg from mercuric acetate and fluorescein has been described. Individual products formed in the reaction mixture were isolated with both paper chromatography and chromatography on alumina column. Their identification was carried out by determining the amount of mercury contained in individual chromatographic fractions. Polarographic observation of the overall mercurization reaction has shown that proceeds rather fast. Similar situation is also valid for exchange reaction between mercuricacetate‐203Hg and individual derivatives of fluorescein.
Preparation of some mercuri‐derivatives of fluorescein labelled with isotopes 197Hg or 203Hg. II. Study of conditions for optimum yield of individual fractions
Authors: Kronrád L. , Ratuský J. , Málek P. , Vavrejn B. , Kolc J. 
Published: October 2006

AbstractThe work is a continuation of the preceding study of possibilities for preparation of labelled derivatives of fluorescein. The conditions under which it is possible to get maximum possible yield of individual products from reaction mixture of mercuric acetate‐203Hg and fluorescein has been studied in detail. It has been found that the yield of derivatives with different mercury content depends to a great extent on the molar ratio of both reaction components. In the first, rapid step of mercurization approximately the same amount of all products is formed regardless of the molar ratio of reaction components. By heating the equilibrium is shifted in favour of the product corresponding to the given molar composition of reaction mixture. The detailed procedures for preparation of difluoresceinyl mercury‐203Hg and hydroxymercurifluorescein‐203Hg have been given.
Preparation of some mercuri‐derivatives of fluorescein labelled with isotopes 197Hg and 203Hg. III. Recoil‐labelling of derivatives
Authors: Kronrád L. , Ratuský J. , Málek P. , Vavrejn B. , Kolc J. 
Published: October 2006

AbstractThe possibility of preparation of mercuriderivatives of fluorescein labelled with 197 Hg by irradiation of the respective compounds in a nuclear reactor has been studied. For all investigated compounds, specific activity high enough could be obtained without any significant radiation decomposition. In cases, when the target molecule contained more than one target atom‐bis (hydroxymercurifluoresceinyl) mercury and bis (hydroxymercurifluorescein)‐higher enrichment factor for some products could be obtained. The recommended procedure for preparation of difluoresceinylmercury‐197 Hg by this method has been given.
Syntheses of 1‐O‐methyl‐14C‐DL‐myo‐inositol (methyl‐14C‐bornesitol) and 5‐O‐methyl‐14C‐myo‐inositol (methyl‐14C‐sequoyitol)
Authors: Shah R. H. , Loewus F. 
Published: October 2006

Abstract1‐O‐ and 5‐O‐Methyl‐14C‐myo‐inositols (methyf‐14C‐bornesitol and ‐sequoyitol) were synthesized by methylation of appropriately blocked myo‐inositol derivatives with methyl = 14C iodide and potassium hydroxide. The benzyl blocking groups of 1‐O‐methyl‐14C‐3,4,5, 6‐tetra‐O‐benzyl‐DL‐myo‐inositol and 1,2,3,4, 6‐penta‐O‐benzyl‐5‐0‐methyl‐14C‐myo‐inositol were cleaved by hydrogenolysis catalyzed by palladium on carbon‐palladium chloride (5 : 1) to obtain the 1‐O‐ and 5‐O‐methyl‐14C‐myo‐inositols respectively.
Synthesis of L‐glutamine‐S‐14C, L‐glutamic acid‐5‐14C, and L‐ornithine‐5‐14C
Authors: Havránek Miloš , Kopecká‐Schadtová Hana , Vereš Karel 
Published: October 2006

AbstractOn alkylation of K14CN with the methyl ester of L‐α‐benzyl‐oxycarbonylamino‐γ‐bromobutyric acid, the methyl ester of L‐α‐benzyloxycarbonylamino‐γ‐cyano‐14C‐butyric acid (II) was obtained The latter was submitted to mild alkaline hydrolysis to yield the free nitrilo acid III which on treatment with hydrogen bromide solution in acetic acid gave L‐glutamine‐5‐14C in one reaction step. L‐Ornithine‐5‐14C was prepared by catalytic hydrogenation of the nitrilo ester II, and L‐glutamic‐5‐14C acid was obtained on acid hydrolysis of the same compound (II). The activated ester (2, 4, 5‐trichlorophenyl ester) of acid III may serve as a suitable intermediate for the preparation of glutamine or ornithine peptides. All prepared substances were optically active L‐forms.
Four syntheses incorporating carbon‐14 or tritium into trans‐1‐methyl‐1,4,5,6‐tetrahydro‐2‐[2‐(2‐thienyl)vinyl]pyrimidine (pyrantel, banminth®)
Authors: Figdor S. K. , Schach Wittenau M. Von , Faulkner J. K. , Monro A. M. 
Published: October 2006

AbstractLabelled pyrantel, an anthelmintic agent, was required for metabolism studies in several animal species. Four labelled syntheses are described incorporating carbon‐14 or tritium into selected sites of the pyrantel molecule. The ultimate location of the marker in each synthesis was chosen in order to yield information about the metabolic breakdown patterns of pyrantel.
Synthesis of cholesterol‐20‐14C
Authors: Porto Ana M. , Gros Eduardo G. 
Published: October 2006

AbstractCholesterol‐20‐14C was synthesized in four steps from pregnenolone‐20‐14C. The labelled intermediates were proven to be cholest‐5‐ene‐3β, 20α‐diol acetate‐3, cholesta‐5, 20 (22)‐diene‐3β‐ol acetate, and cholesterol acetate by 1H‐n.m.r. spectroscopical analysis. Cholesterol‐20‐14C was obtained with a radiochemical purity exceeding 99%.
The synthesis and purification of 4‐[14C]‐ and 7α[3H]‐androsta‐4,16‐dien‐3‐one
Authors: Wilkinson M. , Coombs M. M. , Gower D. B. 
Published: October 2006

AbstractThe synthesis of radioactive androsta‐4,16‐dien‐3‐one from both 4‐[14C]‐ and 7α‐[3 H]‐testosterone has been achieved using modifications of a method due to Henbest. Contrarily to this earlier report, yields of purified androstadienone were approximately 6%. Other compounds, which may be ring D isomers, have been separated by column chromatography on silicic acid impregnated with silver nitrate. Labelled 17‐epitestosterone acetate is also formed in this reaction, and may be readily isolated.
Preparation of ring labelled adamantane derivatives II. 2‐adamantanone‐2−14C, adamantane‐2−14C and 1‐methyladamantane‐2 or 4−14C
Authors: Liggero Samuel H. , Majerski Zdenko , von R. Schleyer Paul , Wolf A. P. , Redvanly C. S. , Wynberg Hans , Boerma J. A. , Strating J. 
Published: October 2006

AbstractA high‐yield, relatively simple synthetic route leading to incorporation of 14C into the secondary position of the adamantane nucleus is described. The synthesis was achieved by the sequence shown in Figure 2. The key steps involved the introduction of a 14C label by diazomethane‐14C ring expansion of adamantanone to give 4‐homoadamantanone‐4−14C (I). Benzylic acid rearrangement of the corresponding homoadamantane diketone (II) gave hydroxy acid (III) which was converted by a novel reaction (SOCl2/benzene) to 2‐adamantanone‐2−14C (IV). The overall yield of labelled 2‐adamantanone was 66%. Wolff‐Kishner reduction of (IV) gave adamantane‐2−14C (V). This was converted to the l‐methyl derivative (VII) by treatment of the corresponding bromide (VI) with methylmagnesium bromide.
Synthesis of 6‐n‐propyl‐2‐thiouracil‐6−14C
Authors: Thornhill D. P. , Sitar D. S. 
Published: October 2006

Abstract6‐n‐Propyl‐2‐thiouracil‐6−14C was prepared from sodium butyrate‐1−14C, with a radiochemical yield of 34%. Butyryl chloride‐1−14C was prepared from butyric acid‐1−14C and condensed with sodio ethylacetoacetate to yield ethyl β‐oxohexanoate‐β−14C. The β‐keto ester was condensed with thiourea in sodium ethoxide to yield the 2 substituted thiouracil.
The synthesis of 14C‐uniformly ring labeled 3,3′,5,5′‐tetra‐tert‐butyldiphenoquinone
Authors: Heeg J. F. , Born G. S. , White H. C. 
Published: October 2006

Abstract14C‐uniformly ring labeled 3,3′,5,5′‐tetra‐tert‐butyldiphenoquinone was synthesized from 2,6‐di‐tert‐butylphenol. Chemical purity was established by mixed melting point, thin‐layer and gas‐liquid chromatography. Radiochemical purity was determined using auto‐radiography in conjunction with thin‐layer chromatography and liquid scintillation techniques. Structure was confirmed by elemental analysis, ultraviolet‐visible and infrared spectroscopy and nuclear magnetic resonance.
Markierte verbindungen IX (1) mechanismus der reaktion von hexachlorpropen zu trichlororthoacrylsäureestern, 14C‐markierte chlor‐C3‐verbindungen
Authors: Boberg Friedrich , Khalaf Hosni , Kirchhoff Klaus 
Published: October 2006

AbstractThe SN2′‐mechanism is proved for the reaction of hexachloro‐propene to trichloroorthoacrylic acid methylester. Moreover 14C‐labelled chloro‐C2‐ and chloro‐C3‐compounds given in reaction schemes 1–3 are synthesized.
Small‐scale degradation of carbon‐14 labelled carboxylic acids. I. Modification of the hunsdiecker reaction
Authors: Susan A. B. , Nystrom R. F. 
Published: October 2006

AbstractA modified Hunsdiecker reaction is described for the degradation of the silver salts of acetic acid‐1−14C, acetic acid‐2−14C, propionic acid‐1−14C, propionic acid‐3−14C, n‐butyric acid‐1−14C and n‐butyric acid‐2−14C to carbon dioxide, silver bromide and an organic bromide containing one less carbon atom than the acid, on a 0.5 to 10 millimole scale. This reaction is performed by allowing the silver salt of a carbon‐14 labelled acid to react with bromine vapor in a sealed tube. Then the separation, purification and determination of the amount of each degradation product is accomplished by use of high vacuum techniques. Finally, the products which are obtained in a radiochemically pure form are analyzed for radioactivity by liquid scintillation counting.
Synthesis of 15α, 15β, 21, 21, 21−3H5‐pregn‐5‐en‐3β‐ol‐20‐one
Authors: Ranzi B. M. , Ronchetti F. , Russo G. 
Published: October 2006

AbstractThe readily accessible pregna‐5,16‐dien‐3 β‐ol‐20‐one (1) was transformed into 3β‐acetoxy‐pregna‐5,17‐dien‐20‐isopropoxy‐16‐one (9). This compound was labelled by base‐catalyzed isotopic exchange and then reconverted into labelled pregna‐5,16‐dien‐3β‐ol‐20‐one (13). Hydrogenation of this last one furnished the title compound (14). The labelling extent in the 15α,15β and 21 positions was determined by combined chemical and microbiological methods.
Zur tritiummarkierung von purinpolyribonucleotiden
Authors: Lauschke Udo , Lodemann Edgar , Wacker Adolf 
Published: October 2006

AbstractPurine polyribonucleotides were labeled with tritium in the 8‐position of the purine ring by heating in tritiated water. An increase in the time of reaction raises the specific activity of the products thus obtained. However under these conditions the degree of fragmentation of the polynucleotides also rises.
Synthesis of homovanillic acid‐2−14C, homoprotocatechuic acid‐2−14C, 3′, 4′‐dihydroxymandelic acid‐2−14C and 1‐(4 hydroxy‐3‐methoxyphenyl)‐ethylene glycol‐1−14C
Authors: Liebman A. A. , Malarek D. H. , Dorsky A. M. , Kaegi H. H. 
Published: October 2006

AbstractSpecifically labelled phenylacetic acid and mandelic acid derivatives, metabolites of L‐Dopa, have been synthesized via the intermediary labelled benzyl alcohols, which were prepared by reduction of the methyl esters of the appropriate benzoic acids. The benzyl alcohols have been converted to the corresponding phenylacetonitriles via the intermediate chlorides and to the cyanohydrins via the intermediate aldehydes in yields significantly higher than previously reported. Overall radiochemical yields of the title compounds were in the order of 25% from 14CO2 and specific activities ranged from 4–10 mC/mmole. The collated procedures have general applicability.
Labelled compounds of potential biological interest II, ‐ application of the yavorsky method for tritiation
Authors: Telc Andrija , Brunfelter Björn , Gosztonyi Tamas 
Published: October 2006

AbstractThe application of the Yavorsky method for tritiation of a number of aminoacetanilides, 2‐amino‐1‐phenylpropane derivatives and some other compounds is described and briefly discussed.
New possibilities of enzymic synthesis of radioactive nucleotides. IV. Application of in vivo tryptophan‐stabilized enzyme system from regenerating rat liver for the synthesis of radioactive thymidine 5′ ‐ phosphates in vitro
Authors: Filip Jiri , Hybs Karel , Nejedly Zdenek , Greger Januaz , Vesely Jiri , Cihak Alois 
Published: October 2006

AbstractThe enzymatic extract ptepared from 48h. regenerating rat liver stabilized with dietary L‐tryptophan possesses the enhanced thymidine and thymidylate kinase activity. The optimal conditions for the phosphorylation of thymidine in vitro were found and the possibility for the preparativer uses was considered. The amount of newly formed thymidine 5′‐monophosphate and 5′ ‐triphosphate depends on the level of adenosine 5′ ‐triphosphate in the reaction mixture, on the temperature of incubation and on the concentration of Mg2+ ‐ions.
Synthesis of 14C‐labelled thyrotropin releasing hormone [pyroglutamylhistidyl‐14C(U)‐prolineamide]
Authors: Flouret George , Alter Arthur , Gendrich Ronald 
Published: October 2006

AbstractA simplified synthesis of pyroglutamylhistidyl‐prolineamide (TRH) was developed for the purpose of making labelled TRH. Pentachlorophenyl pyroglutamate was reacted with histidine to make pyroglutamylhistidine, and the dipeptide was coupled in situ with prolineamide by means of dicyclohexylcarbodiimide to yield the desired hormone. Both the dipeptide and the hormone were purified by chromatography on silica gel. This method of synthesis was conveniently adapted to synthesize TRH‐14C starting with histidine‐14C (U). Purification of labelled TRH was accomplished by preparative TLC.
Radiochemical syntheses. Part III (1) ‐ the synthesis of tritiated α‐ecdysone and 25‐ deoxy‐α‐ecdysone of high specific activity(2)
Authors: Hafferl W. , Wren D. L. , Marshall J. P. , Calzada M. C. , Siddall J. B. 
Published: October 2006

Abstract23, 24‐3 H‐α‐ecdysone and 23, 24‐25‐3 H‐25‐deoxy‐α‐ecdysone were prepared by catalytic hydrogenation of 2ß, 3α, 14α, 22R, 25‐pentahydroxy‐5β‐cholest‐7‐en‐23‐yn‐6‐one with tritium gas and palladium on charcoal in ethanol. Radioactivity and purity measurements of the stored highly labelled compounds are described.
Synthesis of 3H‐ and 14C‐labelled 0‐(3‐morpholinoethoxy)‐diphenylether hydrochloride
Authors: Horie Tohru , Fujita Takeshi 
Published: October 2006

AbstractThe methods for preparation of 14C or 3H labelled compound of 0‐(β‐morpholinoethoxy)‐diphenylether hydrochloride (MPE‐HCI) have been investigated. (1)Starting from guaijacol and 14 C‐bromobenzene (U), the synthesis of MPE‐phenyl‐ 14C (U)‐HCI has been accomplished by a heterogeneous palladium‐catalyzed exchange reaction in a yield of 60%.
Synthesis of organic compounds labelled with hydrogen isotopes. I ‐ exchange of halogen atoms in halohydrins for hydrogen isotopes to prepare alcohols labelled with deuterium or tritium
Authors: Egyed J. , Neszmélyi A. , Beke I. , Baitz E. 
Published: October 2006

AbstractA method has been developed for the preparation of alcohols labelled with hydrogen isotopes, from halohydrins. The synthesis has been performed via Grignard reagents in one step, in the course of which the halogen substituent has exchanged for magnesium which then exchanges for the hydrogen isotope required
Use of L‐ [14C]glycerotetrulose for the enzymatic preparation of 14C‐ labelled intermediates of the pentose phosphate pathway
Authors: Clark M. G. , Blackmore P. F. , Williams J. F. 
Published: October 2006

AbstractL‐/14C/glycerotetrulose (L‐/14C/erythrulose) was prepared by a two step process. Step one involved the formation of L‐/14C/glycerotetrulose 1‐phosphate by condensation of specifically 14C‐labelled 1, 3‐dihydroxydimethyl ketone 1‐phosphate (dihydroxyacetone phosphate) with formaldehyde as catalysed by crystalline rabbit muscle aldolase. Step two involved the enzymatic dephosphroylation of L‐/14C/erythrulose 1‐phosphate. Based on the criteria of the constancy of the specific activity of L‐erythrulose and its derivatives, namely L‐erythrulose phenylosazone and L‐erythrulose o‐nitrophenylhydrazone, the compound was concluded to be pure.Using /1‐14C/‐ and /2‐14C/ dihydroxyacetone phosphate, L‐/1‐14C/‐ and L‐/2‐14C/ erythrulose were prepared and used for the enzymatic preparation of D‐/1‐14C/‐ and /2‐14C/xylulose 5‐phosphate, D‐/1‐14C/‐ and /2‐14C/ fructose 6‐phosphate, D‐/1‐14C/‐ and /2‐14C/ altroheptulose 7‐phosphate, D‐1‐14C/‐ and /2‐14C/ mannoheptulose 7‐phosphate and D‐/1‐14C/‐ and /2‐14C/ glycero D‐ido octulose 8‐phosphate. The authenticity of each of the prepared 14C‐labelled sugar phosphates was verified by chromatographic and specific degradative procedures.
Synthesis of 3H‐ and 14C‐labelled doisynolic and marrianolic acids, and stability of tritium label
Authors: Kundu Nakuleswar , Osawa Yoshio 
Published: October 2006

Abstract3H‐ and 14C‐Labelled doisynolic acid was prepared from 6,7‐3H‐, 2,4,6,7‐3H‐ and 4‐14C‐labelled oestradiol and oestrone by a regulated alkali fusion. Labelled marrianolic acid was similarly prepared from labelled oestriol. Unstability of regiospecific tritium labels in alkali was observed by use of double labelled compounds.
Ethyl esters of Ω‐carboxamidoaliphatic acids‐14CONH2
Authors: Tolman V. , Cabak J. , Benes J. 
Published: October 2006

AbstractEthyl esters of 2‐cyanoacetic, 3‐cyanopropionic and 4‐cyanobutyric acids ‐ 14CN were prepared by reaction of the appropriate halogenated esters with potassium cyanide‐14C. Conversion of these cyanoesters into iminoether hydrochlorides and subsequent thermal decomposition gave ethyl esters of malonamic, succinamic and glutaramic acids ‐14CONH2.
Chemical studies on tobacco smoke XXIII. Synthesis of carbon‐14 labelled myosmine, nornicotine and N′‐nitrosonornicotine
Authors: Hu M. W. , Bondinell W. E. , Hoffmann D. 
Published: October 2006

Abstractdl‐Nornicotine‐2′‐14C was synthesized in four steps. Nicotinic acid (carboxyl‐14C) was first esterified with diazomethane to yield methyl nicotinate (carboxyl‐14C). The ester was condensed with 3‐lithio‐N‐trimethylsilyl‐2‐pyrrolidone to give 3‐nicotinoyl‐N‐trimethyslsilyl‐2‐pyrrolidone (ketone carbonyl‐14C), which was hydrolyzed and decarboxylated in concentrated hydrochloric acid to give myosmine‐2′‐14C.Reduction of myosmine‐2′14C gave nornicotine‐2′‐14C. Reaction of nornicotine‐2′‐14C in hydrochloric acid with sodium nitrite gave N′‐nitrosonornicotine‐2′‐14C. Purification of labelled myosmine, nornicotine, and N′‐nitrosonornicotine was accomplished by preparative thin layer chromatography.
Carboxyl group ‐CO2 exchange in the thermal decomposition of aliphatic dicarboxylic acid salts
Authors: Szabolcs A. , Szammer J. 
Published: October 2006

AbstractThe exchange reaction of carboxyl groups with carbon dioxide has been studied in thermal decomposition of aliphatic dicarboxylic acid disodium salts. It has been found that exchange takes place under given experimental conditions. In some cases the process results in considerable exchange even in lower conversion ranges therefore it is of significance in the field of isotopes techniques.
Synthesis of 3‐methyl‐4‐phenyl‐3‐butenamide‐1‐14C and N,N‐dideutero‐3‐methyl‐4‐phenyl‐3‐butenamide
Authors: Valcavi U. 
Published: October 2006

AbstractThe syntheses of 3‐methyl‐4‐phenyl‐3‐butenamide, an hypolipemic compound, labelled 1‐14C (VIII) and N,N‐dideutero (XI) are described. The 2‐methyl‐3‐phenyl‐2‐propenyl chloride (VI), reacting with cuprous cyanide‐14C, gave the 3‐methyl‐4‐phenyl‐3‐butenonitrile‐1‐14C (VII) which, treated with hydrochloric acid‐water, gave the 3‐methyl‐4‐phenyl‐3‐ butenamide‐1‐14C (VIII). The 3‐methyl‐4‐phenyl‐3‐butenonitrile (X), treated with hydrochloric acid‐D2O, gave the N,N‐dideutero‐3‐methyl‐4‐phenyl‐3‐butenamide (XI).
Synthesis of 2,6‐dimethoxy [U‐14C] phenol
Authors: Miller J. J. , Olavesen A. H. , Curtis C. G. 
Published: October 2006

AbstractThe preparation of 2, 6‐dimethoxy [U‐14C]phenol was carried out in five steps from [U‐14C]phenol. [U‐14C]Phenol was converted to 2‐[U‐14C]phenoxy‐5‐nitrobenzophenone which was sequentially hydroxylated with hydrogen peroxide‐acetic acid to give the di‐ortho hydroxylated phenolic intermediate, 2‐(2′',6″‐dihydroxy [U‐14C]phenoxy)‐5‐nitrobenzophenone. Methylation of this intermediate and subsequent scission of the aryl ether link with piperidine gave the required di‐ortho substituted phenol. An alternative sequence was investigated for the conversion of 2‐(2″‐hydroxy‐phenoxy)‐5‐nitrobenzophenone to 2‐(2″,6″‐dimethoxyphenoxy)‐5‐nitrobenzophenone but it gave a poorer overall yield with an unstable intermediate. Characterization data are included.
Site‐specific labeling of indole derivatives; 3‐(dimethylaminomethyl) indole‐2‐2H (1)
Authors: Bosin T. R. , Rogers R. B. 
Published: October 2006

AbstractA procedure for the site‐specific labeling of indole derivatives has been developed. The procedure utilizes the blocking and activating properties of the p‐toluenesulfonyl group which allows for the facile metalation at the 2‐position of indole with n ‐butyllithium and incorporation of deuterium upon reaction with 2H2O. Removal of the p‐toluenesulfonyl group is achieved by treatment with sodium in liquid ammonia and occurs with retention of the label.
Micro‐scale preparation of 4‐thiouracil labelled with 14C or 14C + 35S
Authors: Seda J. , Votruba L. I. , Tykva R. 
Published: October 2006

AbstractA selective and quantitative method was developed for a microscale preparation of 4‐thiouracil‐2‐14C by the direct thiation of uracil‐2‐14C. From pyridine, dioxane, and tetralin as the thiation solvents, the best yield was obtained in dioxane (96.6% of 4‐thiouracil‐2‐14C). The simultaneous labelling with 14C + 35S was obtained by isotope exchange with elemental sulfur‐35S on refluxing in dimethylformamide. The present procedure may be used as a general method for the preparation of 14C or 14C + 35S labelled bases of nucleic acids of both the pyrimidine and purine type as well as the corresponding nucleosides and nucleotides.