bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Efficient Syntheses of Hyaluronic Acid Oligosaccharides
Authors: Huang Lijun , Huang Xuefei 
Published: October 2006

AbstractHighly efficient syntheses of hyaluronic acid oligosaccharides have been accomplished through the pre‐activation based iterative one‐pot strategy. A series of oligosaccharides ranging from di‐ to hexasaccharides were rapidly assembled using only near stoichiometric amounts of the building blocks without aglycon adjustment or purifications of intermediate oligosaccharides. Deprotection and oxidation protocols were developed for protective group removal and oxidation‐state adjustment. The availability of such structurally well defined synthetic hyaluronic acid oligosaccharides will greatly facilitate the establishment of detailed structure–function relationships.
The new administrative computing
Authors: Green Kenneth C. 
Published: October 2006

AbstractThe new administrative computing is quite different from its predecessors. It involves different people, who are often engaged in qualitatively different tasks. And it recognizes that one type of computer does not offer a complete solution to the administrative and academic computing needs on college campuses. The changes in administrative computing–those of the past decade and those coming in the next ten years–represent challenging, dynamic, and exciting opportunities for campus administrators interested in harnessing the new technologies for institutional advancement and their own professional development.
Convenient syntheses of some α‐deuterated alkyl mesityl ketones by exchange reactions
Authors: Pinkus A. G. , Sabesan A. , Subramanyam Ravi 
Published: October 2006

AbstractThree alkyl mesityl ketones (methyl, ethyl, and isopropyl) deuterated in the α‐positions were prepared in good yields (82‐89%) by exchange with deuterium oxide using dioxane solvent and various catalysts. Little or no exchange was obtained when reactions were attempted under conditions used in published procedures for other ketones. Infrared and 1H nmr spectral evidence in support of structural assignments of deuterated ketones is given.
Syntheses with stable isotopes: Oleic‐1‐13C acid and triolein‐1′,1″, 1″′‐13C3
Authors: Whaley T. W. , Daub G. H. , Walker R. D. , Williams D. L. 
Published: October 2006

AbstractA synthesis of oleic‐1‐13C acid and its conversion to triolein‐1′,1″,1″′‐13C3 are described. 9‐Octadecynenitrile‐1‐13C was prepared from 1‐bromo‐8‐heptadecyne and sodium cyanide‐13C. Hydrolysis afforded stearolic‐1‐13C acid, which was reduced to oleic‐1‐13C acid by the action of disiamylborane on methyl stearolate‐1‐13C. Hydrogenation of stearolic acid in the presence of Lindlar's catalyst was also investigated. Condensation of glycerol and oleic‐1‐13C acid to give triolein‐1′,1″,1″′‐13C3 was effected with dicyclohexylcarbodiimide and 4‐dimethylaminopyridine. The overall yield of triolein‐13C3 from sodium cyanide‐13C was 40%.
Synthesis of deuterium labelled trifluoperazine
Authors: Shetty H. U. , Hawes E. M. , Midha K. K. 
Published: October 2006

AbstractProcedures for the preparation of trifluoperazine with two, four and six deuterium atoms are described. Deuterium was introduced in the propylpiperazine side chain by treatment of the appropriate amide with lithium aluminium deuteride. The isotopic purity of the products was greater than 96.2%.
Stability and storage of compounds labelled with radioisotopes
Authors: Bayly R. J. , Evans E. A. 
Published: October 2006

AbstractThis review summarises the present knowledge concerning the decomposition by self‐irradiation of compounds labelled with the radioisotopes, carbon‐14, hydrogen‐3 (tritium), sulphur‐35, selenium‐75, chlorine‐36, phosphorus‐32, iodine‐125, iodine‐131, cobalt‐57 and cobalt‐58. A discussion of the methods which can be used for the control of this decomposition is also included.
Synthese von 14C‐ringmarkierten phenolischen Ligninspaltstücken und Ligninalkoholen aus Ba14CO3
Authors: Haider K. 
Published: October 2006

AbstractIn früheren Versuchen wurde der mikrobielle Abbau von Substituenten des aromatischen Ringes von phenolischen Ligninspaltstücken und von Lignin selbst untersucht; hierzu wurden die Substituenten durch 14C markiert. Um den Abbau dieser Substituenten mit dem des aromatischen Rings vergleichen zu können, war es notwendig, den Benzolring durch 14C zu markieren. Die synthetisierten phenolischen Verbindungen sind in Abbildung 1 zusammengestellt. Die Synthesen hierfür gingen von Ba14CO3 aus, das über Acetylen in Benzol überführt wurde. Die Substituenten wurden nach und nach mit verschiedenen Methoden in das Benzol eingeführt. Die Ausbeuten, bezogen auf Ba14CO3, lagen für die synthetisierten Ligninalkolhole für p‐Cumaralkohol bei 18%, für Coniferylalkohol bei 6% und für Sinapinalkohol bei 2%. Die spezifische Aktivität dieser Ligninalkohole betrug 0,1‐0,06 mC/mMol. Die spezifische Aktivität der anderen, in Abbildung 1 gezeigten Verbindungen betrug 0,3‐0,1 mC/mMol.
Synthesis of specifically tritium‐labelled oxytocin and lysine‐vasopressin with high specific activity
Authors: Sjöholm Ingvar , Carlsson Lars 
Published: October 2006

AbstractHighly tritium‐labelled oxytocin and lysine‐vasopressin have been synthesized. L‐tyrosine‐3‐3H was prepared from L‐3‐iodotyrosine and tritium gas in methanolic potassium hydroxide with palladium on active carbon as a catalyst. The tritiated oxytocin and lysine‐vasopressin were obtained from the tritiated tyrosine and the heptapeptides of oxytocin and lysine‐vasopressin, respectively, by the p‐nitrophenyl ester method. The peptides had a high degree of purity and the specific radioactivity was 2.9 C/mmole or 5.9 μC/IU for oxytocin and 1.9 C/mmole or 6.5 μC/IU for lysine‐vasopressin. The high radioactivity of the peptides permits extensive studies of their properties in vivo. The stability of the tritium label is discussed.
Preparation of equilin 3H and determination of tritium distribution
Authors: Rakhit S. , Deghenghi R. 
Published: October 2006

AbstractTritiated equilin of specific activity 6.85 × 108 dpm/mg has been prepared by catalytic exchange with tritium oxide. It was found after a series of chemical reactions, that at least 90 % of the radioactivity remained in the B‐ring of the molecule. Of this, 75 % was found to be present at C‐6.
Liquid scintillation counting techniques for the radioassay of [14C] melanin
Authors: Bull Alan T. 
Published: October 2006

AbstractThe radioactive melanin used in this study was extracted from the cell walls of the fungus Aspergillus nidulans after growth in the presence of 14C‐labelled precursors. The counting systems investigated comprised solid samples suspended in a liquid scintillator with or without silica gel, solubilized samples blended in a liquid scintillator and solubilized samples adsorbed on to glass‐fibre discs wich were suspended in a liquid scintillator. Results obtained by counting solid samples with an end window detector are compared with the liquid scintillation data. High counting efficiencies were realized with the glass‐fibre disc method which is recommended for the assay of soluble samples. Liquid scintillation counting of silica gel suspensions was vastly superior to end window counting for the assay of solid samples. The data suggest that 14C‐labelled materials of a particulate or highly pigmented nature can be counted with high efficiency in a liquid scintillation system.
Deuteration of a substrate to high isotopic purity with low grade heavy water
Authors: Rosatzin H. 
Published: October 2006

AbstractDeuterium chemistry is still quite costly, mainly because of the high prices of deuterated compounds needed for syntheses. Furthermore, the risk of diluting isotopically the compounds prepared is considerable. These disadvantages can be alleviated, if i) the deuterium of the D‐donator is exchanged efficiently, ii) highly deuterated solvents and reactants can is be prepared conveniently on a laboratory scale, and iii) compounds, which have been isotopically diluted can be reconcentrated conveniently. Fulfillments of these requirements allows for research in deuterium chemistry on a close to pilot plant scale at tolerable costs.With this aim in mind, basic principles of batch deuterations on pilot plant scale with low grade heavy water discussed. By up‐grading D2O wastes, close to 98 % of the deuterium employed for reaction can be incorporated into the substrate.
14C‐ und 3H‐Markierung von 1‐ Phenyl‐4‐amino‐5‐chlor‐6‐pyridazon im Phenyl‐ bzw. Pyridazonring
Authors: Burger T. F. 
Published: October 2006

AbstractDie 14C‐ und 3H‐Markierung von 1‐Phenyl‐4‐amino‐5‐chlor‐6‐pyridazon im Phenylring wurde durch Umsetzung von Mucochlorsäure mit 14C‐bzw. 3H‐markiertem Phenylhydrazin‐hydrochlorid und Erhitzen des markierten Zwischenproduktes 1‐Phenyl‐4,5‐dichlor‐6‐pyridazon mit konzentriertem Ammoniak erzielt. Die Synthese mit 14C‐markierter Mucochlorsäure als Ausgangs‐material ergab Markierung im Pyridazonring. 14C‐ und 3H‐markiertes Phenylhydrazin‐hydrochlorid wurde aus markiertem Anilin‐hydrochlorid synthetisiert und 14C‐markierte Mucochlorsäure wurde aus Acetylen‐14C oder Formaldehyd‐14C mit 14C‐markiertem 2‐Butin‐1,4‐diol als Zwischenprodukt hergestellt.
Synthesis of 1,4‐dihydro‐1‐methyl‐4‐oxonicotinonitrile‐8‐14C
Authors: Johnson H. E. , Waller G. R. 
Published: October 2006

AbstractThe possibility that 1,4‐dihydro‐1‐methyl‐4‐oxonicotinonitrile (V) is an intermediate in the biosynthesis of the alkaloid ricinine from nicotinic or quinolinic acid in Ricinus communis L. led to our interest in preparing the carbon‐14 labeled compound. The 4‐oxonicotinonitrile (V) and the corresponding 6‐oxonicotinonitrile were shown to be oxidation products of nicotinonitrile methiodide by a crude enzyme preparation from castor seedlings (1, 2). The 6‐oxonicotinonitrile was shown to be identical to the alkaloid nudiflorine isolated from Trewia nudiflora (3).
14C‐labelled 4‐hydroxycoumarin derivatives. I. Synthesis of 3‐substituted derivatives
Authors: Susan A. B. , Dinescu M. , Gavat L. 
Published: October 2006

AbstractThe synthesis and characterization of 3‐R‐substituted derivatives of 4‐hydroxycoumarin‐3‐14C is described, where R is (α‐acetonylbenzyl), (α‐acetonyl‐p‐nitrobenzyl), or (α‐acetonyl‐p‐chlorobenzyl). The compounds were prepared by the quinoline‐catalysed condensation of 4‐hydroxycoumarin‐3‐14C with the following unsaturated ketones : benzylideneacetone, p‐chlorobenzylideneacetone and p‐nitrobenzylideneacetone.
Synthèse de Stéroïdes Tritiés en C16
Authors: Weinman S. , Livet J. 
Published: October 2006

AbstractUne méthode générale de préparation de stéroïdes de type 17α‐hydroxy et 17α,21dihydroxy prégnanestéroïdes tritiés en 16 est présentée dans ce travail.Elle consiste en la formation d'un dérivé 16β bromé, suivie d'une hydrogènolyse so us l'action du tritium gaz donnant lieu au dérivé 16‐3H.La purification est réalisée au moyen d'une saponification non dénaturante suivie de chromatographie sur couche mince de gel de silice et de chromatographie sur colonne de celite.La cristallisation en présence d'un entraǐneur non radioactif rend compte de la pureté et de la radiohomogénéité du produit.
Zur Synthese carbonylmarkierter Hydroxybenzaldehyde
Authors: Billek G. , Kindl H. , Schimpl A. , Schmook F. P. 
Published: October 2006

AbstractHydroxybenzaldehyde, die in der Carbonylgruppe mit 14C markiert sind, lassen sich einfach in einer dreistufigen Reaktionsfolge darstellen. Cu14CN — erhalten aus K14CN — und Bromphenole geben Hydroxyarylnitrile‐(nitril‐14C), die mit Raney‐Nickel und Natrium‐hypophosphit zu den entsprechenden Hydroxybenzaldehyden‐(carbonyl‐14C) reduziert werden können.
Synthesis of the hepatocarcinogen N‐methyl‐4‐aminoazobenzene with tritium in the prime ring
Authors: Lin Jen‐Kun , Miller James A. 
Published: October 2006

AbstractThe new compound N‐methyl‐4‐nitrosoacetanilide was coupled with aniline‐3H (ring‐G) in ethanol‐acetic acid and the resulting azoamide was hydrolyzed in alkali to give a high yield of N‐methyl‐4‐aminoazobenzene labelled in the prime ring.
Synthesis and resolution of o‐hydroxy‐DL‐phenylalanine‐2‐14C
Authors: Petitclerc C. , D'Iorio A. , Benoiton N. Leo 
Published: October 2006

Abstracto‐Hydroxy‐DL‐phenylalanine‐2‐14C was prepared by the condensation of o‐methoxybenzyl chloride and ethyl acetamidocyanoacetate‐2‐14C and subsequent hydrolysis. The racemate was resolved by the stereospecific action of chymotrypsin on the amino acid ethyl ester at p H 5.0 to give the two isomers in 26‐30% yield.
Synthesis of 3‐(o‐Chlorophenyl)‐2‐methyl‐4 (3H)‐quinazolinone‐2 and 4‐14C
Authors: Merrill E. J. 
Published: October 2006

AbstractThe synthesis of 3‐(o‐chlorophenyl)‐2‐methyl‐4[3H]‐quinazolinone labeled with 14C in both the 2 and 4 positions of the quinazolinone ring is described.
Preparation of 14C‐ and 3H‐methoxyl‐labelled forms of ubiquinone by photochemical O‐demethylation and subsequent remethylation
Authors: Cheng Hong‐Ming , Casida John E. 
Published: October 2006

AbstractUbiquinone [ubiquinone (50), coenzyme Q10, CoQ10] undergoes O‐demethylation to the 2‐ and 3‐hydroxyubiquinones, reduction to the hydroubiquinone, and cyclization to the ubichromenol derivative when irradiated, in alcohol solution, with a sunlamp. It is likely that the ubichromenol and hydroubiquinone derivatives form via a common intermediate which is different from that involved in the formation of the hydroxyubiquinone derivatives. The mixture of hydroxyubiquinones, on methylation with 14C‐ and 3H‐labelled methyl iodide or diazomethane, yields methoxyl‐labelled ubiquinone, a material useful in the study of ubiquinone photodecomposition, metabolism, and biochemistry.
The preparation of polyvinyl acetate phthalate‐14C1
Authors: Stiver J. F. , Data J. B. , Christian J. E. 
Published: October 2006

AbstractPolyvinyl acetate phthalate‐14C1 (PV AP) was prepared by condensing radioactive phthalic anhydride with polyvinyl alcohol*. The radioactive anhydride was prepared from ethyl anthranilate The chemical purity and the authenticity of the PV AP so prepared was ascertained by a comparison of its acid number and thin layer chromatography to an authentic sample. The specific activity was determined using liquid scintillation counting.
Synthesis of 17α ‐ethynylestradiol‐6, 7‐3H and 17α‐ethynylestradiol‐6,7‐3H, 3‐cyclopentyl‐1‐14C ether
Authors: Merrill E. J. , Vernice G. G. 
Published: October 2006

AbstractSeveral authors have reported on the physiological differences between 17α‐ethynylestradiol and its 3‐cyclopentyl ether. The radiolabeled steroids were required to compare their relative absorptions, excretions, and metabolic products. Tritium was introduced into the steroid nucleus by catalytic tritiation of 6‐dehydroestrone. Etherification with either cyclopentyl bromide or cyclopentyl‐14C p‐bromobenzenesulfonate gave the cyclopentyl ether of estrone. Ethynylation of either estrone‐6, 7‐3 H or its cyclopentyl‐14C ether gave 17α‐ethynylestradiol‐6, 7‐3 H and 17α‐ethynylestradiol‐6, 7‐3H, 3‐cyclopentyl‐14C ether. It was also possible to etherify 17α‐ethynylestradiol directly although in poorer yields.
Synthesis and identification of 2‐dimethylamino‐5‐(phenyl‐2′‐3H)‐2‐oxazolin‐4‐one
Authors: Howell Charles F. , Van Lear George , Hardy Robert A. 
Published: October 2006

AbstractThe title compound 1b was prepared by tritiolysis of 5‐(O‐bromophenyl)‐2‐dimethylamino‐2‐oxazolin‐4‐one, 2, with 10 Ci of tritium and diluted with unlabelled 1a. The mass spectrum of the 2′ ‐deutero derivative 1c, prepared similarly, showed that 92.9 % of labelled compound was Dl with only 3.1 % D2 and that > 95 % of the isotope was in the aromatic ring.
The synthesis of 11,11‐dideuterolinoleic acid
Authors: Tucker W. P. , Tove S. B. , Kepler C. R. 
Published: October 2006

AbstractThe synthesis of 11,11‐dideuterolinoleic acid is described. The procedure employed resulted in a product of high isotopic purity. The NMR and mass spectral analyses of the product and intermediates confirm the position and extent of deuterium incorporation.
Pregnenolone‐17 α−3H. Synthesis and study of label distribution
Authors: Milewich Leon , Axelrod Leonard R. 
Published: October 2006

AbstractPregnenolone‐17α −3H was synthesized by reaction of 17α‐bromo‐pregnenolone with tritiated acetic acid (CH3CO2 3H) and zinc metal dust. The distribution of the label in the product was studied; about 98% was at the 17‐position and the remainder was randomly distributed on the steroids nucleus. It was also found that when pregnenolone was stirred with deuterated acetic acid (CH3CO2 2H) and zinc metal dust for a longer period of time (22 hr) and in relatively high concentration, the protons of the C21‐methyl group (˜57%) were exchanged for deuterium.
The synthesis of 11,11‐dideuterooleic acid
Authors: Tucker W. P. , Tove S. B. , Kepler C. R. 
Published: October 2006

AbstractThe synthesis of 11,11‐dideuterooleic acid is described. The Wittig reaction is used to introduce the carbon‐carbon double bond, giving a mixture of which better than 90% is the desired cis‐isomer. Two alternative routes gave deuterium incorporation of 95 and >98%d2.
Die markierung von aminoxiden mit isotopem sauerstoff
Authors: Schmidt H.‐L. , Weber N. , Halmann M. 
Published: October 2006

AbstractFrom 18O2 as starting material H218O2 cannot be obtained in a concentration which is sufficient for the synthesis of many amine oxides. Ba18O2 synthesized from 18O2 by a method of Anbar is suitable for the direct oxidation of many amines in glacial acetic acid. The method is demonstrated by the syntheses of the amine oxides of several amines of different basicities with non‐labelled BaO2 in the mMol scale. The synthesis of 18O‐N,N‐dimethylaniline oxide—yield 40% from 0,65 mMol Ba18O2—is described in detail.
Nuclear deuterium exchange in methoxybenzenes and methylated flavonoids
Authors: Kolar G. F. 
Published: October 2006

AbstractThe isolation of 6,8‐d2‐catechin/epicatechin 5,7,3′,4′‐tetramethyl ether from the cleavage of a methylated condensed procyanidin with D2O/dioxan resulted in an investigation of deuterium exchange in some related compounds under identical experimental conditions. In the absence of any acidic catalyst, a partial exchange was established in the majority of di‐ and trimethoxybenzenes when heated with D2O/dioxan (3:1) at 95° for 16 hr in Pyrex glass ampules; 1,3,5‐trimethoxybenzene was found to undergo a complete exchange of nuclear hydrogens under these mild conditions. Methylated flavonoids containing a reactive phloroglucinol system also exchanged both nuclear hydrogens at C6 and C8 with deuterium, but 5,7,3′,4′‐tetramethoxy‐2,3‐trans‐flavan‐3,4‐cis‐diol (2R: 3R‐trans‐R3: 4S‐cis) failed to react.
Preparation of tritium‐labelled D,L‐2,6‐diaminopimelic acid
Authors: Hanuš J. , Vereš K. 
Published: October 2006

AbstractOn hydrogenation of the 2,6‐bis(phenylhydrazone) of 2,6‐diketopimelic acid with carrier‐free tritium a very low specific activity was achieved, due to the labile C‐T‐bonds in the α‐positions. 2,6‐Diaminopimelic‐4−3H acid of spec. activity 790 mCi/mmole was obtained by catalytic dehydrohalogenation of 4‐chloro‐2,6‐diaminopimelic acid in 1N ammonia. A new, simple apparatus for catalytic tritiation is also described.
Preparation of [2‐D], [2,2′‐D2], [1−15N], and [2−13C] enriched ethylenimines
Authors: Bak Bøge , Skaarup Steen 
Published: October 2006

AbstractThree isotopically enriched samples of ethylenimine [aziridine] have been prepared, namely, mixtures containing ca. 50% [2‐D]ethylenimine, 25% [2,2′‐D2]ethylenimine, and 25% parent molecule; 97% [15N]ethylenimine and 3% parent molecule; 64% [13C]ethylenimine and 36% parent molecule. Infrared gas spectra showed the samples (ca. 90 mg) to be of high chemical purity (>98 %). The preparations have been used successfully for high‐resolution microwave studies.
Radiochemical preparation of 3, 4, 3′, 4,‐tetrachloroazobenzene−14C
Authors: Tanaka F. S. , Wien R. G. 
Published: October 2006

AbstractInterest for the preparation of 14C‐labeled 3,4,3′,4′‐tetrachloroazobenzene for metabolism studies was developed after recent reports indicated that soil micro‐organisms could transform some chlorinated aniline based herbicides into azobenzene compounds. The preparation of tetrachloroazobenzene was carried out in a three‐step synthesis starting with ring−14C‐3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (Diuron) which was previously prepared in the laboratory. The overall product yield for the synthesis was estimated to be 33.6%, and the specific activity of the labeled material was 252 μCi/mM.
Preparation de la diceto‐2, 5 piperazine 14C‐2, 5 et sa reduction en piperazine 14C‐2, 5
Authors: Herbert M. , Jimeno De Osso F. , Pichat L. 
Published: October 2006

Abstract2‐5 diketo piperazine 2, 5‐14C was obtained by cyclisation of glycine 1‐14C methyl ester in ether‐water solution, yield of 34%. The reduction of 2, 5 diketo piperazine 2, 5‐14C with Li Al H4 in tetrahydrofuran led to piperazine 2, 5‐14C, yield of 25% based on glycine 1‐14C, specific activity : 33, 4 mCi/mM.
Tritium labelling of the lymphocyte ‐ stimulating leucoagglutinin from kidney beans (phaseolus vulgaris)
Authors: Weber Theodor H. 
Published: October 2006

AbstractLymphocyte‐stimulating leucoagglutinin isolated from extract of kidney beans (Phaseolus vulgaris) was labelled with tritium by treatment with acetic anhydride‐3H in aqueous solution. The labelling procedure used, which introduced 1.7 acetyl groups per leucoagglutinin molecule (molecular weight: 140 000) had no detectable effect upon the lymphocyte‐stimulating or agglutinating activity of the leucoagglutinin. The label was found to be stable after 2 months' storage at 4°C or °20°C.
N‐ acylamino acids and peptides III. The synthesis of N‐ (feruloyl‐2‐14C)‐glycine‐2‐3H
Authors: De Pooter H. , Pé I. , Van Sumere C. F. 
Published: October 2006

AbstractN‐(Feruloyl‐2‐14C)‐glycine‐2‐3H (IX) was obtained with an acceptable yield (43%) starting from O‐methoxycarbonyl‐ferulic acid‐2‐14C (IV) and glycine‐2‐3H ethyl ester (VI). The latter two compounds were first condensed into N‐(O‐methoxycarbonyl‐feruloyl‐2‐14C)‐glycine ‐2‐3H ethyl ester (VII) using anisoyl chloride (X) and the mixed anhydride method (?). Subsequently VII was transformed into N‐(feruloyl‐2‐14C)‐glycine‐2‐3H (IX) by alkaline hydrolysis. The specific activities of the compound were respectively 12.64 μCi (3H)/μmole and 1.71 μCi (14C)/μmole.
A convenient preparation of 18O‐dimethylformamide
Authors: Rao Koganty R. , Digenis George A. 
Published: October 2006

AbstractA method is described by which 18O‐DMF can be prepared conveniently and in very high yields (∼ 90%) by reacting at room temperature an equimolar quantity of benzoyl chloride, DMF and 18O‐labelled water.
Thermal transcarboxylation reactions, II. The study of carboxyl group exchange in the course of ketone formation
Authors: Szammer J. , Szabolcs A. , Noszko L. 
Published: October 2006

AbstractThe course of carboxyl group exchange in the thermal decomposition of a mixture of disodium adipate and pimelate has been studied using 14C‐labelled compounds. The exchange data obtained from the residual acide and ketone formed point to two different incorporation processes. This phenomenon can be well interpreted by presuming the presence of a malonta type intermediate formed in the decomposition process.
Enzymic synthesis of L‐glutamic acid‐15N and 4‐aminobutyric acid‐15N and the preparation of L‐pyroglutamic acio‐15N
Authors: Greenaway W. , Whatley F. R. 
Published: October 2006

AbstractThe production of L‐glutamic acid‐15N in good yield by direct enzymic synthesis from 2‐oxoglutaric acid, ammonium chloride‐15N (95 atom % 15N) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) is described. The NADPH is continuously regenerated by coupling the first reaction to the oxidation of glucose‐6‐phosphate, which serves to drive the synthesis of L‐glutamic acid to completion.4‐Aminobutyric acid‐15N is produced by incubation of L‐glutamic acid‐15N with glutamic acid decarboxylase. CO2 is lost from the reaction mixture and the conversion of glutamic acid to 4‐aminobutyric acid proceeds to completion.L‐Pyroglutamic acid‐15N is produced by heating aqueous solutions of L‐glutamic acid‐15N at 135° for 3 hours.