bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of 6‐substituted benzo[a]pyrene‐α‐14C derivatives
Authors: Hicks James L. , Heys J. Richard 
Published: October 2006

Abstract6‐Lithiobenzo[a]pyrene was carbonated to produce benzo[a]pyrene‐6‐carboxylic‐14C acid, which was in turn used in the preparation of several derivatives. Methylation to the ester was followed by LiAlH4 reduction to 6‐hydroxymethyl‐14C‐benzo[a]pyrene. An efficient oxidation using DDQ produced the corresponding aldehyde. Direct reduction of the ester using LiAlH4 and AlCl3 produced 6‐methyl‐14C‐benzo[a]‐pyrene.
Synthesis of [16,16,17α‐2H3] estradiol and [14α,15,15–2H3] estrone of high isotopic purity
Authors: Massey Ian J. , Tökés Laszlo 
Published: October 2006

AbstractThe title compounds, each of high isotopic purity, were synthesized as internal standards for the mass spectral quantitation of estradiol and estrone. The [2H3] estradiol 3 was obtained from estrone (1) by alkaline H/2H exchange of the C‐16 protons and LiAl2LH4 reduction of the C‐17 keto function. The [2H3] estrone 16 was synthesized by a multistep sequence using deuterioboration of a C‐14 double bond and a three step reductive deuteration of a C‐15 keto function as the key steps for deuterium incorporation.
Synthesis of radioactive 11C molecules for medical research on a microscale : A theoretical and practical approach
Authors: Berger Gérard , Mazière Mariannick , Godot Jean‐Marie 
Published: October 2006

AbstractIt is often necessary to obtain certain 11C radiopharmaceuticals with a high specific activity (> 1000 Ci/mmole), especially when these are intended for medical purposes and are either toxic or used for “in vivo” specific receptor binding studies. The amounts of labelling agent must be very small (concentrations often below to 10−3 M) and some synthesis are difficult or impossible under these conditions.

This article shows how the specific activitry of the labelling agent A affects the synthesis yield of the radiopharmaceutical A′ in the reaction:

A specific activity increase can improve, reduce or have no effect on the yield according to the respective valuse of V1, V2, V′1, V′2.
Different ways to shift an epuilibrium unfavourabel to labelling are also given : reaction temperature, concentrations, addition of starting products, removal of final products.
The reaction kinetics are important since the half‐life of carbon 11 is 20 mn, but this parameter is a complex function of concentrations which can only be detemined by experiment. It seems however that in special cases the percentage of radioactivity incorporated in a given times is imdependent of specific activity.
The effect of impurities, which can be present in concentration of the same order of magnitude as those of the labelling agent is also discussed.
Each thereticl development is illustrated by concrete examples studied in the laboratory.
The conclusion is that theoretically it should not be impossible to synthesize strictly carrier‐free 11C radiopharmaceuticals in certain favourable cases (if it were known how to prepare such carrier‐free labelling agents).
O‐deuterio‐butanoic acid
Authors: Maskill H 
Published: October 2006

AbstractA literature procedure for the preparation of O‐deuterioacetic acid from the anhydride gives substantial deuterium incorporation at C‐2 when used to prepare deuteriobutanoic acid. The enol form of butanoic anhydride is implicated as the intermediate which causes the isotopic scrambling. The required title compound was obtained by the reaction of butanoyl chloride and deuterium oxide.
An efficient synthesis of 5‐(phenyl‐13C6)‐5‐phenylhydantoin
Authors: Poupaert Jacques H. , Winand Martial , Dumont P. 
Published: October 2006

AbstractA procedure is described to convert benzene‐ 13C6 into 5‐(phenyl‐ 13C6)‐5‐phenylhydantoin in 80% overall yield.
Enzymatic synthesis of 11C‐labelled S‐adenosylmethionine
Authors: Gueguen Paul , Morgat Jean‐Louis , Maziere Mariannick , Berger Gérard , Comar Dominique , Maman Michel 
Published: October 2006

AbstractThis article describes the radiosynthesis of 11C‐labelled S‐adenosylmethionine by an enzymatic process. This methyl donor was prepared by condensation of L‐(methyl‐11C) methionine with ATP. The synthesis and purification could be carried out in 20 minutes with a final yield of 80 %. The specific radioactivity obtained was close to 200 Ci/mmole. 6 mCi of 11C‐labelled S‐adenosylmethionine was injected in a rabbit, and its repartition followed by an opticamera.
The synthesis of disodium‐3‐amino‐1‐hydroxypropane‐1, 1‐diphosphonate‐1‐14C. (APD· 2Na)
Authors: Magnien Ernest , Shaikh Mujahid , Suh John T. , Jones Howard 
Published: October 2006

AbstractDisodium‐3‐amino‐1‐hydroxy‐1, 1‐diphosphonate‐1‐14C (APD 2Na), a powerful calcium binding agent and potential drug for the treatment of Paget's Disease was synthesized. The reaction was carried out by reacting β‐alanine (1‐14C) with phosphorus acid and phosphorus trichloride in chlorobenzene. Treatment of the resultant APD with two equivalents of sodium hydroxide gave the title compound.
Synthesis and characterization of 14C polyvinylphosphonic acid
Authors: Stringer Orum D. , Charig Andrew 
Published: October 2006

AbstractTen mCi of 14C ethylene was converted to 1.16 mCi of 14C PVPA by oxidative phosphonation with phosphorus trichloride and molecular oxygen, dehydrohalogenation with triethylamine in ether, polymerization, and hydrolysis. The polymer had a specific activity of 12 uCi/mg and a radiochemical purity over 99%.
A new and efficient synthesis of monotritiomethyl iodide
Authors: Saljoughian Manouchehr , Morimoto Hiromi , Dorsky Albert M. , Rapoport Henry , Andres Hendrik 
Published: October 2006

AbstractA new and efficient synthesis of high specific activity TCH2I containing one atom of tritium per molecule is reported. The precursors for this reagent, chloromethyl p‐phenylbenzoate or bis‐chloromethyl terephthalate, were prepared by the condensation of the corresponding acid chlorides with paraformaldehyde in the presence of zinc chloride. Tritiodehalogenation of the precursors with tritium gas and Pd‐C (10%) in dimethylformamide afforded the desired tritioesters. Cleavage of the esters by lithium iodide at 180°C (SN2 type reaction), or by HI at 140°C gave mono tritium labeled methyl iodide in more than 95% yield. The reaction of the latter with a number of amines yielded tritium labeled N‐methylated products readily as was shown by Radio‐HPLC. The specificity of the labeling in the final products was confirmed by tritium nmr spectroscopy.
The synthesis of 2‐14C‐N‐nitrosothiazolidine
Authors: Cragin David W. , Shibamoto Takayuki 
Published: October 2006

Abstract2‐14C‐N‐Nitrosothiazolidine was synthesized with a chemical purity of 99.6%, a radio chemical purity of 99.4%, and an overall yield of 30.7%. Unlabelled N‐nitroso‐thiazolidine, synthesized using the same method, resulted in a purity of 99.85% by capillary GC and 99.7% by HPLC. Analysis of N‐nitrosothiazolidine by GC was found to require a low injection port temperature of 160°C to prevent denitrosation in the injection port. During the nitrosation of thiazolidine, if the pH was reduced below 4 with hydrochloric acid, ring hydrolysis occurred, and chlorinated disulfide compounds formed.
Synthesis of 1‐benzyl‐4‐[(5,6‐dimethoxy[2‐14C]‐1‐indanon)‐2‐yl]‐methylpiperidine hydrochloride (E2020‐14C)
Authors: Iimura Youichi , Mishima Mannen , Sugimoto Hachiro 
Published: October 2006

Abstract1‐Benzyl‐4‐[(5,6‐dimethoxy[2‐14C]‐1‐indanon)‐2‐yl]‐methylpiperidine hydrochloride (1) (E2020‐14C), an acetylcholinesterase inhibitor for studying the pharmacokinetic profiles of E2020, was synthesized from 5,6‐dimethoxy[2‐14C]‐1‐indanone (2) as the labelled starting material.
Preparation of sodium 2‐mercapto‐[14C]ethanesulfonate
Authors: Jarý J. , Grossmann V. , Doležal S. , Labsk´ J. 
Published: October 2006

AbstractStarting from [1‐14C]ethanol 1,2‐dibrom‐[14C]‐ethane was prepared by an usual method through [14C]‐ethylene. Sodium sulfite was alkylated by 1,2‐dibrom–[14C]ethane and the formed sodium 2‐brom‐[14C]ethane sulfonate was transferred without isolation to a labelled 2‐[(aminoiminomethyl)thio]‐[14C]ethanesulfonic acid. After purification by crystallization of the acid 2‐mercapto‐[14C]ethanesulfonic acid was prepared through guanidinium salt. After the neutralization of 2‐mercapto‐[14C]ethanesulfonic acid by sodium hydroxide the corresponding sodium salt with specific activity 0.083 μCi/mmol (0.31 MBq/mmol) was prepared.
Catalytic tritiation of splenopentine and diacetylsplenopentine via the di‐iodo‐tyrosine derivatives
Authors: Oehlke J. , Mittag E. , Klebsch H.‐J. , Niedrich H. 
Published: October 2006

AbstractTritium labelled splenopentine (Arg‐Lys‐Glu‐Val‐Tyr‐OH) and diacetylsplenopentine (Nα‐ac‐Arg‐Nα‐ac‐Arg‐Nε‐ac‐Lys‐Glu‐Val‐Tyr‐OH) were prepared by the catalytic dehalotritiation of the corresponding diiodopeptides obtained by ICl‐iodination. Under conditious which proved to be optimal in foregoing model deuterations, a specific radioactivity of about 90% of the theoretical one was achieved. The labelling result was influenced noticeably by a transfer of solvent hydrogen directly to the substrate analogously as found in the dehalodeuterations of simple amino acid derivatives.
Positron labeled phorbol ester: Synthesis method for “non‐carrier added” phorbol 13‐[1‐11C] butyrate using ketene reaction
Authors: Imahori Yoshio , Fujii Ryou , Ido Tatsuo , Hirakawa Kimiyoshi , Nakahashi Hisamitsu 
Published: October 2006

AbstractA new method was developed to synthesize positron labeled phorbol esters for second messenger imaging based on a receptor binding to protein kinase C. [1‐11C]propyl ketene was produced by the pyrolytic decomposition of [1‐11C]butyric acid. This new method was made possible by the reaction of [1‐11C]propyl ketene to the hydroxyl group of phorbol under the non‐carrier added conditions. The precursor protected in the 20‐hydroxyl group of phorbol was acylated by [1‐11C]propyl ketene to the 13‐hydroxyl group producing phorbol 13‐[11C]butyrate ([11C]P13Bu). Total synthesis time was about 60 minutes and the specific activity was greater than 67 GBq/μmol (1800 mCi/μmol). [11C] P13Bu will prove to be useful ligand for PET studies due to the simple procedures required for synthesis.
Preparation of 2H‐ and 3H‐labelled carvone
Authors: Banthorpe Derek V. , Brown Geoffrey D. 
Published: October 2006

Abstract(‐)‐Carvone labelled with 2H or 3H at C‐10 was prepared by two methods. The first, involving a reversible ene reaction yielded 10‐deuteriocarvone with some substitution at other reactive centres. An improvement to this route involved the decomposition of an organozinc reagent of 10‐chloro‐carvone which gave a better yield of product substituted only at C‐10. As a preliminary to a possible radioimmunoassay with the above material, four derivatives of carvone linked to bovine serum albumin were prepared.
Synthesis of 15N labelled nylon 6
Authors: Glans J. H. , Hatfield G. R. 
Published: October 2006

AbstractThe synthesis of 15N labelled nylon 6 by anionic polymerization of ϵ‐caprolactam is described. Labelling of this commercially important polymer should greatly enhance investigations of its morphology by techniques such as NMR, IR, and Raman spectroscopies.
High specific activity tritiated prostaglandin analogs I: Synthesis of enprostil‐[13, 14‐3H]
Authors: Parnes Howard 
Published: October 2006

AbstractPartial reduction of the acetylenic precursor 1 with carrier‐free tritium gas in the presence of Lindlar catalyst gave the highly labelled cis‐allylic alcohol 2. Tritium was thus contained in the metabolically stable 13,14‐position of the lower side chain. Elaboration of 2 via a fourteen step, microscale sequence gave enprostil‐[13,14‐3H] 19 having a specific activity of 41 Ci/mmol.
Synthesis of methyl arachidonate‐17, 17, 18, 18‐d4
Authors: Adlof Richard 
Published: October 2006

AbstractMethyl arachidonate (5c, 8c, 11c, 14c‐20: 4) 17, 17, 18, 18‐d4 was prepared for use in both in vivo and in vitro metabolism studies. The deuterium atoms were incorporated by deuterium gas and Wilkinson's catalyst. The tetraacetylenic acid precursor (5a, 8a, 11a, 14a‐20: 4) 17, 17, 18, 18‐d4 was synthesized by a series of Grignard coupling reactions and reduced by Lindlar catalyst and hydrogen gas to arachidonic acid‐d4. The methyl ester was prepared by diazomethane and purified by a combination of reverse phase and silver resin chromatography. The deuterated methyl arachidonate was prepared in an overall yield of ca. 11% and with an isotopic purity of ≥91%. The deuterium‐labelled tetracetylenic acid precursor and the methyl arachidonate‐d4 were characterized by 13C‐NMR.
Labelled compounds of interest as antitumour agents. Part III (1). Synthesis of 2H and 3H isotopomers of etanidazole (SR 2508)
Authors: Webb Paul , Threadgill Michael D. 
Published: October 2006

AbstractChemically and radiochemically efficient syntheses of N‐(2‐hydroxy‐2‐[2H]ethyl)‐2‐(2‐nitroimidazol‐l‐yl)acetamide and N‐(2‐hydroxy‐2‐[3H]ethyl)‐2‐(2‐nitroimidazol‐1‐yl)acetamide, isotopomers of the hypoxic cell radiosensitiser etanidazole (SR 2508), have been achieved by reduction of the corresponding aldehyde with isotopically labelled sodium borohydride. The primary kinetic deuterium isotope effect for the process is 1.5.
C‐29 tritiated β‐amyrin: Chemical synthesis aiming at the study of aromatization processes in sediments
Authors: Lohmann Françoise , Trendel Jean‐michel , Hetru Charles , Albrecht Pierre 
Published: October 2006

AbstractTritiated β‐amyrin (olean‐12‐en‐3β‐ol, 2) was synthesized in six steps, from epikatonic acid (3), with a specific activity of 550 GBq/mmole. The protracted incubation of this triterpene in a pond mud led by biodegradation to labelled aromatic tetracyclic hydrocarbons, identical with known sedimentary biomarkers.
Effects of catalyst pretreatment and additives on the hydrogen incorporation during the catalytic deuteration of N‐acetyl‐di‐iodotyrosineamide
Authors: Oehlke J. , Niedrich H. , Zöpfl H.‐J. , Franke P. 
Published: October 2006

AbstractThe influence of the mode of presaturating the catalyst and of different inhibiting agents on the catalytic deuteration of N‐acetyl‐3,5‐di‐iodo‐L‐tyrosineamide was investigated in order to derive conclusions for optimizing peptide tritiations. Reactions of the activated catalyst with solvent and substrate can be inhibited independently. The exchange of the catalyst‐bound deuterium against hydrogen from solvent is inhibited by the substrate itself and by addition of 1,3‐di‐chlorobenzene. The dehalogenation reaction and the unspecific exchange of carbon‐bound hydrogen of the substrate are inhibited preferably by thioglycolic acid, iodide and by the triethyl‐ammonium ion.
A convenient preparation of 2‐[15N]‐amino‐4,6‐dimethoxypyrimidine
Authors: Spencer Thomas K. , Georg Gunda I. , Aubé Jeffrey 
Published: October 2006

AbstractA convenient preparation of 2‐[15N]‐amino‐4,6‐dimethoxypyrimidine using 15N‐ammonium chloride as the source of 15N is described.
Synthesis of racemic, S(+)‐ and R(‐)‐N‐[methyl‐3H]3,4‐methylenedioxymethamphetamine
Authors: Hashimoto Kenji , Hirai Katsumi , Goromaru Tsuyoshi 
Published: October 2006

AbstractThe synthesis of 3,4‐methylenedioxymethamphetamine(MDMA), a serotonergic neurotoxin, labeled with tritium is described. Labeling was accomplished by N‐alkylation of the free base of the corresponding desmethyl compound using [3H]methyl iodide. The compound was purified by preparative HPLC. The radiochemical yield was about 60% based on [3H]methyl iodide. The radiochemical purity was more than 95% from HPLC and TLC. Furthermore, S(+)‐ and R(‐)‐[3H]MDMA were completely separated by analytical HPLC with chiral column.
Complexes of technetium III and IV with pyrophosphate: Preparation, analysis and metabolic breakdown studies
Authors: Shafiq Y. F. , Al‐Janabi M. A. A. , Abdel‐Azeez M. A. M. 
Published: October 2006

AbstractThe oxidation state of technetium‐pyrophosphate (99m‐Tc PYP) reduced by SnCl2.2H2 O was determined by radiochromatography. Two different complexes were formed (complex I and complex II). The oxidation states of Tc to be III or IV or both in complex II or hydrated technetium dioxide in complex I were investigated. Formation of Tc (III)/Tc(IV)‐PYP and hydrated technetium dioxide‐PYP complexes were studied by radiochromatography and by biodistribution in mice. Experiments in animals helped to clarify the behaviour of these complexes. Thus urine obtained from one group of mice injected with 99m‐Tc‐PYP complexes wase reinjected to another group of mice. It was found that complex II excreted in the urine was not broken down while cleavage and deposition of 99m‐Tc‐species were found with complex I excreted in urine.
Facile and economical preparation of [14C]‐labelled shikimic acid
Authors: Krüper Annette , Gehrke Peter , Amrhein Nikolaus 
Published: October 2006

AbstractA convenient and inexpensive method for the preparation of [14C]‐labelled shikimic acid based on the photoassimilation of 14CO2 by henbane (Hyoscyamus niger L.) leaves in the presence of the herbicide glyphosate is described.Methanolic extracts were purified by successive anion exchange, paper and thin‐layer chromatography to yield [14C]‐labelled shikimic acid of 99.5% radiochemical purity, as shown by analytical HPLC. Under the conditions employed, the rate of incorporation of 14CO2 into shikimic acid (0.7 – 17.6%) showed a positive correlation with the size of the leaf used in the incubation (3.6 ‐ 146 mg fresh weight), while the specific activity of the acid (6 ‐ 12.7 GBq/mmol) was an inverse function of the leaf size.
Regio‐ and stereo‐selective deuterium labelling of β‐cyclodextrin
Authors: Djedaïni Florence , Desalos Jacques , Perly Bruno 
Published: October 2006

AbstractReliable methods for the selective deuteration of β‐cyclodextrin are described. Kinetic studies of the proton‐deuterium exchange catalysed by Raney nickel in deuterium oxide show dramatically different behaviours of positions 2, 6 and 3 and allow selective labelling. Deuteration of protons at position 2 can be achieved by performing the exchange procedure at room temperature or preferably at 310 K. Under these conditions, no other positions are affected. At refluxing temperature, protons of the methylene group rapidly exchange and, at longer reaction times, deuteration at C3 takes place. A combination of direct and back exchange cycles affords cyclodextrins labelled on any of the sensitive positions. “Organic shift reagents” are used to assist the NMR analysis of labelled samples and have shown some stereoselectivity for deuteration of the C6 methylene group protons.
Synthesis of sodium 3‐ethyl‐7‐isopropyl‐[2‐14C]‐azulene‐1‐sulfonate
Authors: Suzaka Hiroaki , Tomiyama Tsuyoshi , Ikegami Shiro 
Published: October 2006

AbstractSodium 3‐ethyl‐7‐isopropylazulene‐1‐sulfonate1, which has been found to be a potent and chemically stable agent having anti‐inflammatory and anti‐ulcerous activity, was synthesized in14C‐labelled form by using potassium [14C]‐cyanide.14C‐Labelled1with a specific activity of 9.02 mCi/mmol was prepared in eight steps in 21.9% overall chemical yield from 3‐(t‐butyldiphenylsilyloxy)propyl tosylate10.
Synthesis of [2′‐13C]biotin
Authors: Etzel W. A. , Berger S. 
Published: October 2006

Abstract[2′‐13C]Biotin was synthesized in 51% yield by reaction of the hydrolysis product of biotin, 3,4‐diaminotetrahydro‐2‐thiophenvalerianic acid, with [13C]phosgene.
Synthesis of mitomycin C labeled with mono‐tritium at the C6 ‐ methyl position
Authors: Kanda Yutaka , Akinaga Shiro , Kasai Masaji 
Published: October 2006

AbstractA first preparation of mitomycin C specifically labeled with mono‐tritium at the C6‐methyl position is described. The key intermediate in the synthesis, 7,7‐ethylenedioxy‐6‐methylenemitosane (5) was made by treating 7,7‐ethylenedioxy‐6‐phenylselenomitosane (4) with meta‐chloroperbenzoic acid. Subsequent 1,4‐addition of [3H]hydride gave 7,7‐ethylenedioxymitosane labeled with tritium (6). Amination at C7 position and deacetylation of 1a‐aziridine nitrogen of 6 gave [C6‐CH3‐3H1] mitomycin C (2) with an overall yield of 15%. The specific activity of the final compound was 16.2 mCi/mmol with 13% tritium incorporation.
Preparation of 15N labeled tetranitromethane C(15NO2)4
Authors: Skawinski William , Flisak Joseph , Chung Alex C. , Jordan Frank , Mendelsohn Richard 
Published: October 2006

Abstract15N labeled tetranitromethane, C(15NO2)4, was prepared from anhydrous nitric acid and acetic anhydride. A procedure for the preparation of the nitric acid from Na15NO3 is described. Tyrosine was nitrated with H15NO3 and its 15N NMR spectrum compared well with that of tyrosine nitrated with C(15NO2)4.
Synthesis of 3‐[D7]isopropylbenzo‐2‐thia‐1,3‐diazinon‐(4)‐2,2‐dioxide ([D7]‐bentazone)
Authors: Jacquemijns Marjorie , Stavenuiter Johannes F. C. , Zomer Gijsbert 
Published: October 2006

Abstract[D7]bentazone (95 atom% D) was synthesized from methyl antranilate and [D7]isopropylsulfamoyl chloride. [D7]isopropylsulfamoyl chloride was prepared by treatment of [D7]isopropyl amine with chlorosulfonic acid and phosphorous pentachloride. The overall yield from [D7]isopropyl amine was 7%.
Synthese radioactive de sels d'ammonium quaternaires d'hydroxy imino methyl‐2 OU ‐4 pyridinyle par l'intermediaire de la N‐methyl formanilide‐14C. II. Marquage par 14C de l'iodure d'[hydroxyimino methyl‐2 methyl‐1 pyridinyle ou 2‐PAM Iodure et du diodure de trimethylène dioxy‐3,3′ bis [hydroxy imino methyl‐2 methyl‐1, pyridinyle] ou R‐665
Authors: Madelmont J. C. , Nicolas C. , Maurizis J. C. , Dupuy J. M. , Garrigue H. , Meyniel J. M. , Demerseman P. , Sentenac‐Roumanou H. , Veyre Et A. 
Published: October 2006

The two compounds were labelled by 14C on the hydroxyimino methyl group substituted on the 2 positions of the pyridinium ring.The convenient pyridinium lithiated intermediates were formylated with N‐methyl 14C‐formanilide. The hydroxyimino methyl groups were synthezised by reaction of the 14C‐formyl compound with hydroxylamine. For the two species alkylation of pyridine was performed with methyliodide. Radiochemical yields were 50% and 20%.
Synthesis of [119mSn]‐mesoporphyrin IX dichloride
Authors: Denissen Jon F. 
Published: October 2006

AbstractTin mesoporphyrin IX dichloride (Sn‐MPCl2) is a heme oxygenase inhibitor of current clinical interest for the treatment of neonatal hyperbilirubinemia. The synthesis of [119mSn]‐MPCl2 for drug metabolism and disposition studies is reported. [119mSn]‐MPCl2 was prepared in 60% radiochemical yield by metalation of the porphyrin nucleus of mesoporphyrin IX dihydrochloride with tin(II)‐119m acetate. The product had a specific activity of 43.4 mCi/mmol and a radiochemical purity of 99%, as determined by radio‐HPLC analysis.
Facile [14C]methane preparation using the reduction of [14C]methyl iodide by sodium borohydride
Authors: Elbert Thomas , Matucha Miroslav 
Published: October 2006

Abstract[14C]Methane (440 mCi) was prepared using the reduction of [14C]methyl iodide by sodium borohydride in diglyme in quantitative yield. The diborane formed was trapped as nonvolatile 9‐BBN. [14C]Methane free of any accompanying gases was conveniently distributed into calibrated glass ampules by the aid of capillary vacuum manifold and freezing out by liquid nitrogen.
Syntheses of 14C‐labelled monoacidic metabolites of dithiopyr
Authors: Mehrsheikh Mohammad E. , Clizbe Lane A. , Singh Harbhajan , Purdum Wr 
Published: October 2006

AbstractConvenient methods for the selective hydrolysis of the thioester groups of dithiopyr to the corresponding carboxylic acid are described. 2‐(Difluoromethyl)‐4‐(2‐methylpropyl)‐5‐[(methylthio)carbonyl]‐6‐(trifluoromethyl)‐3‐pyridine‐4‐14C‐carboxylic acid (2) was obtained by simple potassium hydroxide hydrolysis of 14C‐labelled dithiopyr. A more involve strategy was necessary for the preparation of the isomeric carboxylic acid 6‐(difluoromethyl)‐4‐(2‐methylpropyl)‐5‐[(methylthio) carbonyl]‐2‐(trifluoromethyl)‐3‐pyridine‐4‐14C‐carboxylic acid (3)