bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of radiocarbon labelled lidocaine (α‐diethylaminoacet‐[1‐14C] ‐2′, 6′ ‐dimethylanilide)
Authors: Mezö  , Teplán  
Published: October 2006

AbstractStarting from sodium acetate‐1‐14C, acetyl‐1‐14C bromide was prepared and from this bromacetyl‐1‐14C bromide. The latter was used to acylate 2, 6‐dimetyl‐aniline to α‐bromoacet‐(1‐14C) ‐2′, 6′ ‐xylidide, with an activity yield of 31%. The labelled lidocaine and its hydrochloride were prepared from this product by refluxing with diethylamine, with yields of 84.5% and 74.3%, respectively. The molar activity of the radiocarbon‐labelled Lidocaine was found to be 3.48 mCi/mmole; thin‐layer chromatography showed the product to be homogeneous.
Radiation ‐ induced decomposition of radioiodine ‐ labelled 3 ‐ iodo ‐ L ‐ tyrosine
Authors: Appleby A. , Umfrid R. P. 
Published: October 2006

AbstractIn investigating the radiolytic decomposition of 3‐iodo‐L‐tyrosine we find :

that, by studying the effects of dissolved argon, nitrous oxide and hydrogen, e−aq is the reactive intermediate of greatest interest in choosing a protector of the labelled compound. This technique should have general application.
that O2/ ethanol and N2O/ ethanol are both good combinations for the purpose of protecting the substrate.
that in dilute solutions of MIT, with adequate protector present, high specific activity compound should be no more prone to radiation‐induced self‐decomposition than is compound labelled at a lower specific activity.

Items (2) and (3) should be noted particularly, in view of the widespread belief that high specific activity and the presence of oxygen are always deleterious to the stability of labelled compounde.
Markierte verbindungen XII. Perchlor ‐ 4 ‐ methylen ‐ 1 ‐ cyclopenten ‐ (14C) und ‐ (36CL)
Authors: Boberg Friedrich , Khalaf Hosni 
Published: October 2006

AbstractThe reaction of hexachloropropene (2) with hexachloro‐ 1.3‐cyclopentadiene (1) to perchloro‐4‐methylene‐1‐cyclopentene (3) is studied with 14C‐ and 36Cl‐ labelled compounds. 3 contains C‐1 or C‐3 of 2. 36Cl is statistically distributed on the compounds of the system. At 220° 2 is isomerized.
A Method for routine preparation of very pure chlormerodrin labelled with 197 Hg or 203 Hg with high specific activity
Authors: Lisewska Iwona , Potocki Jan , Pasternak Antoni 
Published: October 2006

AbstractA method for routine production of 3‐chloromercuri‐2‐methoxy‐propylurea‐197 Hg or 203 Hg with a high specific activity and high radiochemical purity, has been elaborated. Important for the method are: good and standardized HgCl2, the maintenance of molar ratioe HgCl2 to sodium acetate and allylurea 1:1 and 1:5 respectively, and the time of heating of the reaction mixture in the autoclave with overpressure 0.2 ‐ 0.3 At, not less than 6 hrs. The use of anhydrous ethyl ether for washing the precipitate removes both organic and inorganic radiochemical impurities. The method enables one to work with quantities of HgCl2 lower than 1 mg.
Markierte verbindungen XIV. Chlorierende spaltung von naphthalin‐(1‐14C)
Authors: Zörkendörfer Eckhard , Boberg Friedrich 
Published: October 2006

AbstractThe chlorination of naphthalene‐(1‐14C) to octachloro‐naphthalene‐(1‐14C), decachloro‐1.4‐dihydronaphthalene‐(1.4, 5.8‐14C), octachloro‐indene‐(1.3.4.7‐14C) + CCI4, decachloro‐indane‐(1.3.4.7‐14C) shows, that a β‐carbon atom of naphthalene is eliminated by chlorolysis.
The preparation of carbon‐14 labeled tobacco constituents, I. the syntheses of benzyl, phenethyl, and undecyl acetate‐14C‐1, 2
Authors: Comes R. A. , Jenkins R. W. 
Published: October 2006

AbstractThe syntheses and purifications of benzyl, phenethyl, and undecyl acetate‐14C‐1, 2 are described. These compounds were prepared by reaction of the appropriate alkyl or aryl halide with 14C‐labeled sodium acetate in the presence of acetic acid. Isolation of the acetates was accomplished by trapping from a gas chromatograph. The technique of gas‐liquid radiochromatography in activity determinations is described.
Synthesis of 14C‐chloroethene (vinyl chloride) and 14C‐trichloroethene
Authors: Criddle W. J. , Park G. S. , Robertson D. , Thomas W. H. J. 
Published: October 2006

AbstractThe synthesis of 14C‐chloroethene and 14C‐trichloroethene is described, the former in a state of high chemical purity suitable for polymerisation studies.
Synthesis of 1, 3‐dihydro‐1‐methyl‐7‐nitro‐5‐phenyl‐2H‐1, 4‐benzodiazepin‐2‐one‐5‐14c (nimetazepam‐5‐14C)
Authors: Yoshitake A. , Makari Y. , Endo M. 
Published: October 2006

AbstractThe synthesis from carbon‐14C dioxide of 1, 3‐dihydro‐1‐methyl‐7‐nitro‐5‐phenyl‐2H‐1, 4‐benzodiazepin‐2‐one‐5‐14C (I) for use in metabolic studies has been described. The synthesis was achieved by the sequence shown in figure 1. The overall yield of labelled nimetazepam (I) was nearly 36%.
Preparation d'acroleine tritiee ou deuteriee sur le carbone 1
Authors: Golfier Michel , Prangé Thierry 
Published: October 2006

AbstractThe synthesis of C‐1 tritiated or deuterated acrolein is described. The oxidation of allylic alcohol with the silver carbonate on Celite reagent shows an important isotopic effect. One can take advantage of this effect for a simple preparation of tritiated aldehydes. The NMR spectrum of deuterated acrolein is analysed and calculated.
Synthesis of 3 or 5[14C] 4‐butyl‐1, 2‐diphenyl‐3, 5‐pyrazolidinedione (phenylbutazone)
Authors: Stavchansky S. , Kostenbauder H. B. 
Published: October 2006

AbstractThe condensation of 1 or 3 [14C] n‐butylmalonate diethyl ester (III) with hydrazobenzene (IV) yields up to 90 per cent of 3 or 5 [14C] 4‐butyl‐1, 2‐diphenyl‐3, 5‐pyrazolidinedione, if n‐butyl alcohol is used as a solvent and the corresponding sodium alcoholate as a condensing agent (1, 2).One or three [14C] n ‐ butylmalonate diethyl ester can be synthesized by condensation of n‐bromobutane (II) and 1 [14C] ethyl malonate (I) in the presence of sodium ethoxide (3).
Synthese DU N‐ [(ethyl ‐ 1 pyrrolidinyl ‐2) methyl] methoxy‐2 sulfamoyl ‐5 benzamide (sulpiride) marque AU 14C
Authors: Noël J. P. , Benakis A. , Herbert M. , Pichat L. , Thominet M. 
Published: October 2006

AbstractSulpiride: N‐[léthyl‐l pyrrolidinyl‐2) methyl] methoxy‐2 sulfamoyl‐5 benzamide, has been labelled with carbon 14 in the carbonyl group by a five step synthesis from barium carbonate 14C. The specific activity of the final product is 37.6 mCi/mM (110 μCi/mg), and the radiochemical purity 99.5%. UV‐ and mass spectrometry confirm the identity of the labelled compound with the reference material, as well as the position labelled with 14C.
Synthese de la DL‐Norephedrine (Méthyle 14C)
Authors: Nguyen‐Hoang‐Nam  , Lucas P. , Pichat L. 
Published: October 2006

AbstractLa synthèse de la dl‐noréphédrine (méthyle 14C) en deux stades, à partir de l'α‐N, N‐dibenzylaminoacétophénone et de I14CH3 est décrite. Après purification par chromatographie sur résine échangeuse d'ions AG 50 W‐X2 on obtient la dl‐noréphédrine (méthyle 14C) HCl avec un rendement radiochimique de 31% par rapport à 14CO3Ba, activité spécifique: 55 mCi/mM. L'analyse par électrophorèse sur papier associée à la chromatographie sur papier et en couche mince permet de contrǒler la pureté radiochimique de la dl‐noréphédrine 14C.
Preparation of deuterium labelled catecholamines, catecholamine precursors and metabolites for use as internal standards in mass fragmentographic determination and for turnover studies
Authors: Lindström B. , Sjöquist B. , Anggard E. 
Published: October 2006

AbstractL‐dihydroxyphenylalanine‐2H3, L‐tyrosine‐2H2, dopamine‐2H3, 3‐methoxytyramine‐2H3, homovanillic acid‐2H2, homovanillic acid‐2H5 and vanillylmandelic acid 2H2 were prepared by hydrogen‐deuterium exchange under acidic or basic conditions. 4‐hydroxy‐3‐methoxy phenylethyleneglycol‐2H3 was prepared from vanillylmandelic acid‐2H by reduction with LiA12H4. The isotopic yield for L‐dihydroxyphenylalanine was 90% and for the other compounds >99%. These labelled compounds could be used as internal standards in the mass fragmentographic analysis of the protium species in tissues and body fluids as well as in metabolic studies in vivo.
The synthesis of 13C‐enriched α‐methyldopa
Authors: Ames Matthew M. , Castagnoli Neal 
Published: October 2006

AbstractAlpha‐methyldopa hydrochloride, specifically labelled with 13C in the benzylic position, was prepared for use in biotransformation studies. Carbonation of the lithio derivative of 3,4‐dibenzyloxybenzene with 13CO2 (64 atom percent) was followed by LiA1H4 reduction of the resulting benzoic acid. Oxidation with CrO3 provided the benzaldehyde which was condensed with nitroethane to form the phenylnitropropene, Reduction of this phenylnitropropene with Fe/HOAc gave the corresponding phenyl‐2‐propanone which was converted to its hydantoin derivative. Base hydrolysis of the hydantoin followed by debenzylation in concentrated hydrochloric acid gave the desired alpha‐methyldopa hydrochloride in 16% overall yield.
A labelled hypocholesteremic agent, preparation OF 2‐(2‐pyridine)‐1‐(3‐chlorophenyl)‐2‐phenyl‐1‐methylethanol uniformly tritiated on the 2‐phenyl ring
Authors: Hansen D. W. , Van Eeckhout E. Den , Drach J. C. , Burckhalter J. H. , Sinsheiraer J. K. 
Published: October 2006

Abstract2‐(2‐Pyridine)‐1‐(3‐chlorophenyl)‐2‐phenyl‐1‐methylethanol (I), containing tritium uniformly distributed in the 2‐phenyl ring, was synthesized in two steps with tritiated benzene as the labelled starting material.An improved procedure was employed for the coupling of m‐chloroacetophenone and 2‐benzylpyridine. The higher melting of two enantiomeric pairs, known for its hypocholesteremic activity in rats, was isolated and found to have a chemical purity of >95% and a specific activity of 0.11 mCi/mmole.
Synthese de la DL‐Lysine Marquee Selectivement par L'AZOTE 15 EN α ou en ϵ et son Dedoublement
Authors: Mizon J. et Ch 
Published: October 2006

AbstractLes auteurs décrivent les améliorations qu'ils ont apportées aux proaédés déjà connus de synthèse de la DL‐lysine, marquée à 1′15N en α ou en ϵ La bis N α N ϵ‐chloracétyl lysine, nécessaire pour réaliser le dédoublement de la DL lysine sous l′action de l'acyclase est préparée avec un bon rendement à l'aide du chloracétate de paranitrophényle.
Syntheses with stable isotopes: Methanol‐13C, methanol‐13C‐D4 and methanol‐12C
Authors: Ott D. G. , Kerr V. N. , Whaley T. W. , Benziger T. , Rohwer R. K. 
Published: October 2006

AbstractHydrogenation of carbon dioxide at mild temperature and preasure utilizing a copper‐zinc‐chromium catlyst has been developed for small‐ and large‐scale preparations of methanol and is applicable to various isotope isomers.
Synthesis of tritium and carbon‐14 labeled 1,3‐dioxolanes. II. D‐2‐ethyl‐2‐phenyl‐4‐(2‐piperidyl)‐1,3‐dioxolane hydrochloride,
Authors: Hsi Richard S. P. 
Published: October 2006

AbstractThe synthesis of 3H and 14C labeled d‐2‐ethyl‐2‐phenyl‐4‐(2‐piperidyl)‐1, 3‐dioxolane hydrochloride (Va and Vb respectively) is described. The optically pure α(‐)‐2‐(2‐piperidyl)ethane‐1,2‐diol hydrochloride (II), obtained by hydrolyzing α (+)‐2,2‐diphenyl‐4‐(2‐piperidyl)‐1,3‐dioxolane hydrochloride(1) (I), is used as the starting material to minimize the need for separation of isomers in the products.
Synthesis of carboxy‐14C furosemide
Authors: Liebman A. A. , Dorsky A. M. , Malarek D. H. 
Published: October 2006

AbstractA modification of the Sandmeyer reaction which requires only a moderate excess of cyanide‐14C was utilized for the preparation of 4‐chloro‐2‐fluorobenzonitrile‐7‐14C (3). After hydrolysis, the resulting acid (4) was converted to carboxy labelled furosemide (6) by existing methods. This procedure is potentially useful for insertion of 14C in compounds that fail to undergo conventional carbonation reactions.
Synthesis of 6‐/N,N‐1′,6′‐hexyleneformamidine‐14C/‐penicillanic acid
Authors: Zupanska Janina , Szymoniak Krystina , Busko‐Oszczapowicz Irena , Cieslak Jerzy 
Published: October 2006

AbstractSynthesis of 6‐/N,N‐1′, 6′‐hexyleneformamidine‐14C/penicillanic acid /VII/ was carried out. N‐formyl‐14C‐hexamethyleneimine /II/ was obtained from formic‐14C acid and hexamethyleneimine /I/. The product was chlorinated with oxalyl chloride. The obtained N,N‐1, 6‐hexylenechloroformimino‐14C chloride /III/ was condensed with trimethylsilyl ester of N‐trimethylsilyl‐6‐amino penicillanic acid /V/. The final product /VII/ was separated with a radiochemical yield of 46.5%.
Synthesis, isolation and immunochemical characterization of N‐(carboxymethyl‐3H)‐D‐lysergamide
Authors: Winkelhake Jeffrey L. , Voss Edward W. 
Published: October 2006

AbstractCovalent amide linkage of glycine‐2‐3H to the non‐hallucinogenic derivative, d‐lysergic acid (LSA), by carbodiimide activation results in a lysergic acid analogue which has potential use in biochemical studies of the mode of action, metabolism and immunology of d‐lysergic acid diethylamide (LSD). Optimal conditions for the reaction and isolation of the product, N‐(carboxymethyl‐3H)‐d‐lysergamide, were determined. The product was analyzed by radioimmune assay and by equilibrium dialysis with highly specific antibody to the lysergyl moiety.
Steroids XLI. preparation of 9α, 11ζ‐tritiated estrone‐3‐methyl ether and following syntheses of 17α‐CH2X‐derivatives of estradiol
Authors: Ponsold K. , Römer J. , Wagner H. 
Published: October 2006

AbstractThe preparation of 9α, 11ζ‐tritiated estrone‐3‐methyl ether with high specific activity is described. The following syntheses gave 17α‐CH2X‐derivatives of estradiol (X = CN and SCN) with high specific activity and radiochemical purity higher than 98%. Radiolysis and storage conditions are examined.
The stability of thymidine, uridine and their related nucleotides, labelled with tritium
Authors: Sheppard G. , Sheppard H. C. , Stivala J. F. 
Published: October 2006

AbstractAccurate knowledge of the stability of (3H)‐uridine, (3H)‐thymidine, and their triphosphates is important for their use as tracers in biological systems. Data for the stability of these compounds at different storage temperatures and in the presence of a stabiliser, ethanol, are presented. The effects observed are discussed in terms of current theories on radiation self‐decomposition.
Synthese Amelioree de la Progesterone 14C‐4
Authors: Hoellinger H. , Nguyen‐Hoang‐Nam  , Pichat L. 
Published: October 2006

AbstractLa synthèse améliorée de la progestérone 14C‐4 est décrite. La purification de la progestérone 14C‐4 par chromatographie sur colonne de silicate de Mg et CCM préparative a permis l'isolement de deux sous‐produits: isoprogestérone 14C‐4 et trioxo‐3,5,20‐seco A‐4,5 pregnane 14C‐4, identifiés par spectrométrie RMN et de masse. Rendement radioactif global: 40% par rapport à 14CO3Ba, activité spécifique: 59 mCi/mM.
Labelling of a new analgetic agent, 5α 9α‐dimethyl‐2‐[4‐(4‐fluorophenyl)‐4‐oxobutyl]‐2′‐hydroxy‐6,7‐benzo‐morphan (id‐1229), with tritium
Authors: Nakatsuka I. , Kawahara K. , Yoshitake A. 
Published: October 2006

Abstract5α,9α‐Dimethyl‐2‐[4‐(4‐fluorophenyl)‐4‐oxobutyl]‐2′‐hydroxy‐6,7‐benzomorphan (X) (ID‐1229), a new analgetic agent, was labelled with tritium at C‐3, 4 or C‐3 position of the benzo‐morphan nucleus for the use of metabolic studies. The procedures used are illustrated in Fig. 2. Catalytic reduction of the enamine (VI) with tritium gas afforded the benzomorphan‐3,4‐3H (VIIa) in 24% radiochemical yield while reduction of VI with sodium borotritide gave the benzomorphan‐3‐3H (VIIb) in 40%. The tritiated benzomorphans (VIIa and VIIb) were easily converted to ID‐1229‐3,4‐3H (Xa) and ID‐1229‐3‐3H (Xb), respectively. The overall radiochemical yield of Xa was 7.5% based on tritium gas and that of Xb was 12.0% based on sodium borotritide.
Preparation D'Aldehydes α‐β Ethyleniques Deuteries sur la Double Liaison
Authors: Bessiere Yvonne , Ouar Faroudja 
Published: October 2006

AbstractPour préparer des aldéhydes α‐β éthyléniques portent un atome de deutérium sur la double liaison en β du carbonyle, on utilise la méthode de Ireland et Marshall: transformation des butylthiométhylène alcools deutériés en milieu acide.
Preferential tritium labelling of binding site residues in alpha chymotrypsin by exposure of the 1,3‐3H‐diisopropylphosphoryl derivative to tritiated hydrogen sulfide
Authors: White Frederick H. 
Published: October 2006

AbstractWhen alpha chymotrypsin, labelled with a heavily tritiated diisopropylphosphoryl (3HDIP) group on the serine residue at position 195, was exposed to tritiated hydrogen sulfide (3HSH) under dry conditions, an incorporation of 3H occurred that favored residues close to the binding site. The reaction mechanism remains unclear. A direct transfer of 3H from the ligand is ruled out, although 3H in this position as well as in 3HSH is essential for the labelling reaction. It is shown that the reaction does not involve self‐radiolysis. It is suggested that the reaction may instead be related to an observed instability of 3H within the ligand, possibly through a free radical mechanism.
Synthesis of 2,4‐dihydroxy‐6‐pentyl‐benzoic‐6‐14C acid, ethyl ester. (olivetolic‐6‐14C acid. ethyl ester)
Authors: Schmit J. P. , Van de Velde V. , Piraux M. 
Published: October 2006

AbstractIn a first step, Δ1‐trans‐octenoic‐3‐14C acid was prepared by a Grignard reaction with BaCO3‐14C and 1‐bromo‐pentane, followed by reduction of the obtained hexanoic‐1‐14C acid to hexanal‐1‐14C via the n‐hexanol‐1‐14C. The produced hexanal‐1‐14C, by condensing with malonic acid gives the request Δ1‐trans‐octenoic‐3‐14C acid. In a second step, olivetolic‐6‐14C acid, ethyl ester was prepared by condensing the Δ1‐trans‐octenoic‐3‐14C acid, methyl ester with ethyl acetoacetate followed by bromination and catalytic hydrogenation.
Synthesis of 14C‐labelled isotope‐isomeric alkanes. I n‐heptane‐1‐14C and ‐2‐14C
Authors: Bally Ioana , Gǎrd Eugenia , Ciornei Elieabeta , Biltz Maria , Balaban A. T. 
Published: October 2006

AbstractThe synthesis of n‐heptane‐1‐14C is described. starting from 14CH3I via (14CH3) 2Cd and caproyl chloride; for obtaining n‐heptane‐2‐14C, n‐pentyl bromide is converted into the Grignard reagent, carbonated with 14CO2, and the resulted coproic acid is converted into its chloride and treated with dimethyloadmium. In both cases the labelled n‐heptan‐2‐one is finally reduced to labelled n‐heptane by the Kishner‐Wolff method.
Preparation of tritium‐labeled compounds. V. A group of steroids by catalytic reduction of unsaturated precursors with tritium gas
Authors: Thomas Richard C. , Ikeda George J. , Campbell J. Allan , Harpootlian Harry 
Published: October 2006

AbstractA group of Δ4‐3‐keto steroids was prepared by catalytic reduction of suitable conjugated diene‐3‐keto precursors with tritium gas. Thus, 11α‐hydroxy‐4‐pregnene‐3,20‐dione‐7‐3H (I), 20α‐hydroxy‐4‐pregnen‐3‐one‐7‐3H (II), 6α‐methyl‐4‐pregnene‐3,11,20‐trione‐7‐3H (III), 17α‐hydroxy‐6α‐methyl‐4‐pregnene‐3,20‐dione‐7‐3H, acetate (IV), and 17α‐hydroxy‐6‐methyl‐3H3‐16‐methylenepregna‐4, 6‐diene‐3,20‐dione, acetate (V) were prepared from 11α‐hydroxypregna‐4,6‐diene‐3,20‐dione (VI), 20α‐hydroxypregna‐4,6‐dien‐3‐one (VII), 6‐methylpregna‐4,6‐diene‐3,11,20‐trione (VIII), 17α‐hydroxy‐6‐methylpregna‐4,6‐diene‐3,20‐dione, acetate (IX), and 17α‐hydroxy‐6‐dibromomethylene‐16‐methylene‐4‐pregnene‐3,20‐dione, acetate (X), respectively. In addition, 3α‐hydroxy‐5β‐pregnane‐11,20‐dione‐7‐3H, cyclic 20‐(trimethylene acetal) (XI) was prepared from I via 11α‐hydroxy‐5β‐pregnane‐3,20‐dione‐7‐3H (XII), 5β‐pregnane‐3,11,20‐trione‐7‐3H (XIII) and 3α‐pregnane‐11,20‐dione‐7‐3H (XIV).
Improved techniques for semi‐micro synthesis of radioisotope labelled thiophosphate pesticides
Authors: Smith B. R. , Dauterman W. C. , Hodgson E. 
Published: October 2006

AbstractRadiolabelled ethanol can be incorporated into the organophosphate molecule by heating PSCl3 with the labelled alcohol. Methanol can also be incorporated in this manner, but with lower yields. The O, O‐dialkyl, phosphorochloridothionates were produced by treating O‐alkyl phosphorodiahloridothionate with the appropriate sodium alkoxide. Coupling the O, O‐dialkyl phosphorochloridothionate to a substituted phenol to form the pesticidal compounds was facilitated by the catalytic effect of silver ions. The catalyzed coupling reaction was found to be compatible with hdroxyllated heterocyclic compounds, and with phenols containing nitro‐, mercapto‐, alkyl‐, and cyano‐substituents. The reaction was not successful, however, with chloro‐substituted phenols The coupling reaction was also found to be useful in synthesizing EPN, a phosphonothionate pesticide. The coupling reaction does not appear to be useful for the synthesis of oxons, the analogous phosphate compounds.
The preparation of 3‐acetamido‐6‐methyl‐8‐N‐propyl‐S‐[3‐14C] triazolo‐[4, 3‐a] pyrazine [I.C.I. 58,301]
Authors: White D. F. , Burns J. 
Published: October 2006

AbstractThe preparation of 3‐acetamido‐6‐methyl‐8‐n‐propyl‐s‐[3‐14C] triazolo‐[4, 3‐a] pyrazine [I.C.I. 58,301] from sodium [14C] cyanide in three stages is described. The overall radiochemical yield of product, at a specific activity of 3.6 μCi/mg, was 26.0%.
Labelling of steroios by exchange with isotopic water on heterogeneous platinum and palladium: Methods for overcoming competing oxidation
Authors: Garnett J. L. , O'Keefe J. H. 
Published: October 2006

AbstractA representative group of steroids have been labelled by exchange with isotopic water in the presence of heterogeneous Group VIII transition metals. Platinum and palladium are the best of the metals studied. Steroids examined included oestrogens, keto and hydroxy derivatives, hydrocarbons and two cardiac glycosides. The presence of an OH group in the steroid leads to oxidation simultaneously with isotope incorporation. Esterification of the OH group prior to exchange eliminates oxidation and yields labelled compounds of high chemical purity. The variables affecting optimum exchange have been determined and include solvent, temperature of reaction and method of catalyst activation. Isotope orientation in the labelled steroids supports a mechanism involving the role of π‐ and σ‐bonded intermediates in the exchange reaction.
Isotopic hydrogen labelling of steroids by homogeneous platinum catalysed exchange
Authors: Garnett J. L. , O'Keefe J. H. 
Published: October 2006

AbstractA number of new homogeneous metal catalysts have been studied for the deuteration and/or tritiation of a range of steroids. Sodium tetrachloropltinate (II) was the most satisfaatory of the catalysts examined. This aompound catalysed selective exchange of protons in ring A of aromatic type steroids such as 3‐desoxyestrone. oestrone and oestradiol. Conversion of the free steroids to their acetate or benzoate esters gave better labelling since the OH group in the free steroid reacts with the catalyst leading to precipitation of platinum from the homogeneous solution and a reduction in exchange rate. Steroids with hindered double bonds such as cholesterol, testosterone, pregnenolone, desoxycorticosterone acetate and progesterone do not exchange rapidly nor do the cardiac glycosides, digitoxin and digitoxigenin. Exchange with homogeneous platinum is more selective in isotope incorporation than with the corresponding heterogeneous platinum. A mechanism for the homogeneous exchange is proposed in terms of π‐bonded intermediates. The present data are a guide for predicting the isotopic hydrogen labelling behaviour of steroids with the recently discovered homogeneous platinum catalyst.
Microsynthesis of 3H‐sterculic acid with high specific activity
Authors: van Tilborg H. 
Published: October 2006

AbstractCopper‐catalysed addition of ethyl diazoacetate to methyl scearolate (20 mmol scale) and subsequent saponification gave 9, 10‐carboxymethylene, 9‐octadecenoic acid in 67% yield. The letter was decarbonylated by treatment with HClO4/Ac2O in the cold (76 μmol scale) to give cyclopropenium perchlorate, which was reduced with NaBH4. After removal of non‐acidic by‐products. sterculic acid labelled with 3H in the cyclopropene ring was obtained in 9% yield. Its specific activity was 140 mCi/mmol, the radiochemical purity was 90%.