Meeting Summary The 22nd annual symposium of the International Isotope Society's United Kingdom Group took place at the Møller Centre, Churchill College, Cambridge, UK, on Friday, 18 October 2013. The meeting was attended by 65 delegates from academia and industry; the life sciences; and chemical, radiochemical and scientific instrument suppliers. Delegates were welcomed by Dr Ken Lawrie (GlaxoSmithKline, UK, chair of the IIS UK group). The subsequent scientific programme consisted of oral and poster presentations on isotopic chemistry and applications of labelled compounds, or of chemistry with potential implications for isotopic synthesis. Both short-lived and long-lived isotopes were represented, as were stable isotopes. The symposium programme was divided into a morning session chaired by Dr Karl Cable (GlaxoSmithKline, UK) and afternoon sessions chaired by Mr Mike Chappelle (Quotient Biosciences, UK) and by Dr Nick Bushby (AstraZeneca, UK). The UK meeting concluded with remarks from Dr Ken Lawrie (GlaxoSmithKline, UK).

In support of a program to develop an alpha 7 agonist as a treatment for Alzheimer's disease, three drug candidates, 1, 2, and 3, were prepared in labeled forms. Compound 1 was prepared in C-14 labeled form by lithiation of [2,6-(14)C2]2-chloropyridine and subsequent coupling with spirooxirane-2,3'-quinuclidine. When this same coupling was attempted using [3,4,5,6-(2)H4]2-chloropyridine, alcohol [(2)H6]-6 was the major product indicating that the primary isotope effect for the lithiation step was significant enough to shift the reaction pathway. Therefore, an alternate site of labeling was used to prepare [(2)H4]-1. [(13)C5]-2 was prepared in five steps from [(13)C5 ]2-furoic acid, but the C-14 labeled compound used [(14)C2]-1 as the starting material instead. [(14)C2]-3 was prepared in two steps from [carbonyl-(14)C]nicotinic acid.

Introduction: The alpha-7 nicotinic acetylcholine receptor (alpha 7 nAChR) is key in brain communication and has been implicated in the pathophysiology of diseases of the central nervous system. A positron-emitting radioligand targeting the alpha 7 nAChR would enable better understanding of a variety of neuropsychiatric illnesses, including schizophrenia and Alzheimer's disease, and could enhance the development of new drugs for these and other conditions. We describe our attempt to synthesize an alpha 7 nAChR-selective radiotracer for positron emission tomography (PET).Methods: We prepared the high-affinity (K-d = 0.2 nM) alpha 7 nAChR agonist, 5'-(2-[F-18]fluorophenyl)spiro[1-azabicyclo-[2.2.2]octane]-3,2'-(3'H)furo[2,3-b]pyridine, [F-18]AZ11637326, in two steps, a nucleophilic fluorination followed by decarbonylation. We studied [F-18]AZ11637326 in rodents, including mice lacking alpha 7 nAChR, and in non-human primates.Results: [F-18]AZ11637326 was synthesized in a non-decay-corrected radiochemical yield of 3% from the end of synthesis (90 min) with a radiochemical purity >90% and average specific radioactivity of 140 GBq/mu mol (3,781 mCi/mu mol). Modest rodent brain uptake was observed (2-5% injected dose per gram of tissue, depending on specific activity), with studies comparing CD-1 and alpha 7 nAChR null mice indicating an element of target-specific binding. Blocking studies in non-human primates did not reveal specific binding within the brain.Conclusion: Despite the high affinity and target selectivity of AZ11637326 for alpha 7 nAChR in vitro and encouraging rodent studies, receptor-mediated binding could not be demonstrated in non-human primates. Further structural optimization of compounds of this class will be required for them to serve as suitable radiotracers for PET. (C) 2013 Elsevier Inc. All rights reserved.

Meeting Summary The 20th annual symposium of the International Isotope Society's United Kingdom Group took place at the Wellcome Genome Campus, Hinxton, Cambridge, UK on Tuesday 18 October 2011. The meeting was attended by around 70 delegates from academia and industry, the life sciences, chemical, radiochemical and scientific instrument suppliers. Delegates were welcomed by Dr Ken Lawrie (GlaxoSmithKline, UK, chair of the IIS UK group). The subsequent scientific programme consisted of oral and poster presentations on isotopic chemistry and applications of labelled compounds or of chemistry with potential implications for isotopic synthesis. Both short‐lived and long‐lived isotopes were represented, as were stable isotopes. The symposium programme was divided into a morning session chaired by Prof. Chris Willis (University of Bristol, UK) and afternoon sessions chaired by Mr Mike Chappelle (Quotient Biosciences, UK) and by Dr Nick Bushby (AstraZeneca, UK). The UK meeting concluded with remarks from Dr Ken Lawrie (GlaxoSmithKline, Stevenage, UK).

Metabolites of a G protein-coupled receptor modulator containing 1,2,4-oxadiazole and piperazine substructures were identified in vitro in human, rat, and dog hepatocyte incubates and in vivo in rat plasma, bile, urine, and feces by using 14C-radiolabeled parent compound. Exposure coverage for the major circulating metabolites in humans at steady state and in preclinical species used in drug safety assessments was determined by using pooled plasma samples collected from a human multiple ascending dose study and a 3-month rat toxicokinetic study. Metabolites M1 and M2, which were formed by opening of the 1,2,4-oxadiazole ring, were observed as major metabolites both in vitro and in vivo across species. The carboxylic acid metabolite M2 was presumably formed through reductive N-O bond cleavage of the oxadiazole ring and subsequent hydrolysis. However, the mechanism for the formation of the unusual N-cyanoamide metabolite M1 remains uncertain. Neither M1 nor M2 had any target activity, as did parent drug P. In rat bile, rearranged Cys-piperazine and Gly-Cys-piperazine adducts, involving the formation of a five-membered heteroaromatic imidazole derivative from a six-membered piperazine ring, were observed as minor metabolites. These findings support a previously reported mechanism regarding glutathione detoxification for piperazine bioactivation products.

In support of a program to develop an antipsychotic treatment for schizophrenia, three labeled forms of the NK3 receptor antagonist AZD2624 have been prepared. [3H2]AZD2624 was synthesized by tritiodehalogenation for use in receptor occupancy and autoradiographic studies. [13C6]AZD2624 was prepared for use as an internal standard through the intermediacy of [13C6]isatin, and two C-14 isotopomers of AZD2624 were prepared from [14C]benzoic acid and [14C]isatin for a variety of DMPK studies. Copyright © 2011 John Wiley & Sons, Ltd.

In support of a program to develop a treatment for depression, four labeled forms of a delta opioid agonist were prepared. The [2H4] labeled form was prepared using a relatively straightforward conversion of [2H4]bromoethanol to [2H4]N‐methyl‐2‐hydroxyethylamine. The key step in the synthesis of the [2H6] labeled form involved the Pd‐catalyzed exchange in D2O of 8‐quinolin‐8‐ol to give [2H6] 8‐quinolin‐8‐ol. The C‐14 labeled form was synthesized in one step using [14C]carbonylation, and the C‐11 labeled form was prepared in two steps from 11CH3I. Copyright © 2011 John Wiley & Sons, Ltd.

We previously reported the absence of high‐affinity binding of the group II metabotropic glutamate receptor agonists LY 354,740 and LY 379,268 to the D2L dopamine receptor. A rebuttal to our findings has since been reported (see Introduction section); this study represents our response. Analysis by LCMS of LY 354,740 and LY 379,268 used in this study revealed the correct molecular mass for these compounds. Both LY 354,740 and LY 379,268 exhibited potent agonist activity for mGluR 2 in the 35 S‐GTPγS assay. Functionally, neither compound displayed antagonist activity in the GTPγS assay with recombinant D 2 . At concentrations up to 10 μM, both compounds failed to displace [ 3 H]‐raclopride, [ 3 H]‐PHNO, or [ 3 H]‐domperidone in filter‐binding assays under isotonic (120 mM NaCl or N ‐methyl glucamine) or low‐ionic strength (no NaCl or N ‐methyl glucamine) conditions. Some displacement of [ 3 H]‐domperidone (20–40%) was observed at 30 μM of LY 354,740 under low‐ionic strength and under isotonic conditions in the absence of NaCl. No displacement of [ 3 H]‐domperidone was detected in a two site model at lower (<100 nM) concentrations of either compound. Moreover, no D 2 activity was observed for LY 354,740 or LY 379,268 in the CellKey™ (cellular dielectric spectroscopy) assay. In this communication, we discuss the possible reasons for differences in our study and the previously published work and implications of these studies for mechanisms of antipsychotic action. Synapse 65:64–68, 2011. © 2010 Wiley‐Liss, Inc.

Silylacetylenes are useful coupling partners for aromatic halides in the Sonogashira reaction and a C-14 labeled version of this useful synthon would allow ready access to a wide variety of arylalkynes. (CaC2)-C-14 was converted to triphenylsilyl[C-14(2)] acetylene using two related routes in 65% yield, and the resulting [C-14(2)] acetylene was coupled with an aryl halide to give the target triphenylsilylarylacetylene (2) in 40% yield.

Epidermal growth factor receptors (EGFR), upregulated in many tumor types, have been a target for therapeutic development and molecular imaging. The objective of this study was to evaluate the distribution and metabolic characteristics of fluorine-18 labeled anilinoquinazolines as potential imaging agents for EGFR tyrosine kinase expression. Fluorine-18 labeled fluoronitrobenzenes were prepared by reaction of potassium cryptand [18F]fluoride with 1,2- and 1,4-dinitrobenzenes, and 3-nitro-N,N,N-trimethylanilinium triflate in 5 min. Decay-corrected radiochemical yields of [18F]fluoride incorporation into the nitro-aromatic compounds were 81 ± 2%, 44 ± 4% and 77 ± 5% (n = 3–5) for the 2-, 3- and 4-fluoro isomers, respectively. Sodium borohydride reduction to the corresponding [18F]fluoroanilines was achieved with greater than 80% conversion in 5 min. Coupling of [18F]fluoroaniline-hydrochlorides to 6,7-dimethoxy-4-chloro-quinazoline gave the corresponding 6,7-dimethoxy-4-(2-, 3- and 4-[18F]fluoroanilino)quinazolines in 31 ± 5%, 17 ± 2% and 55 ± 2% radiochemical yield, respectively, while coupling to the 6,7-diethoxy-4-chloro-quinazoline produced 6,7-diethoxy-4-(2-, 3- and 4-[18F]fluoroanilino)quinazolines in 19 ± 6%, 9 ± 3% and 36 ± 6% radiochemical yield, respectively, in 90 min to end of synthesis from [18F]fluoride. Biodistribution of 2- and 4-[18F]fluoroanilinoquinazolines was conducted in tumor-bearing mice (MDA-MB-435 and MDA-MB-468 xenografts). Low tumor uptake (<1% injected dose per gram (ID/g) of tissue up to 3 h postinjection of the radiotracers) was observed. High bone uptake (5–15% ID/g) was noted with the 4-[18F]fluoroanilinoquinazolines. The metabolic stabilities of radiolabeled quinazolines were further evaluated by incubation with human female cryopreserved isolated hepatocytes. Rapid degeneration of the 4-fluoro-substituted compounds to baseline polar metabolites was observed by radio-TLC, whereas, the 2- and 3-[18F]fluoroaniline derivatives were significantly more stable, up to 2 h, corroborating the in vivo biodistribution studies. para-Substituted [18F]fluoroanilines, a common structural motif in radiopharmaceuticals, are highly susceptible to metabolic degradation.

The inventory of labeled compounds and methods for their preparation are constantly growing, but still more building blocks of biologically relevant compounds need to be developed. Furans are frequently encountered in bioactive molecules, and a good synthesis of labeled furan is found in the literature. We required a relatively uncommon labeled furan, 5-chloro-2-furoic acid, for investigative work labeled with C-13 and C-14. Carboxylation of the lithium anion of [C-13(4)] furan with (CO2)-C-13 followed by chlorination using benzyltrimethylammonium dichloroiodate provided the target compound in modest yield and high purity. The same procedure was then repeated with unlabeled furan and (CO2)-C-14 to give [carbonyl-C-14]-5-chlorofuran-2-carboxylic acid.

AZD2624 was pharmacologically characterized as a NK3 receptor antagonist intended for treatment of schizophrenia. The metabolic drug-drug interaction potential of AZD2624 was evaluated in in vitro studies. CYP3A4 and CYP3A5 appeared to be the primary enzymes mediating the formation of pharmacologically active ketone metabolite (M1), whereas CYP3A4, CYP3A5, and CYP2C9 appeared to be the enzymes responsible for the formation of the hydroxylated metabolite (M2). The apparent K(m) values were 1.5 and 6.3 µM for the formation of M1 and M2 in human liver microsomes, respectively. AZD2624 exhibited an inhibitory effect on microsomal CYP3A4/5 activities with apparent IC(50) values of 7.1 and 19.8 µM for midazolam and testosterone assays, respectively. No time-dependent inactivation of CYP3A4/5 activity (midazolam 1'-hydroxylation) by AZD2624 was observed. AZD2624 demonstrated weak to no inhibition of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, and CYP2D6. AZD2624 was not an inducer of CYP1A2 or CYP2B6. Although AZD2624-induced CYP3A4 activity in hepatocytes, the potential of AZD2624 to cause inductive drug interactions of this enzyme was low at relevant exposure concentration. Together with targeted low efficacious concentration, the results of this study demonstrated AZD2624 has a relatively low metabolic drug-drug interaction potential towards co-administered drugs. However, metabolism of AZD2624 might be inhibited when co-administrated with potent CYP3A4/5 inhibitors.

Positron emission tomography (PET) antagonist ligands such as [ 11 C]‐raclopride are commonly used to study dopamine D2 receptor (D2) binding of antipsychotics. It has been suggested that agonist radioligands bind preferentially to the high‐affinity state of D2 receptor and may provide a more relevant means of assessing D2 occupancy. The main objective of this study was to determine if D2 receptor occupancy (RO) could be differentiated with agonist and antagonist radioligands in vivo. Agonist radioligands [ 3 H]‐MNPA and [ 3 H]‐(+)‐PHNO were synthesized and compared to antagonist [ 3 H]‐raclopride in the in vitro binding and in vivo occupancy studies. In vivo, unanesthetized rats were pretreated with quinpirole (full agonist), aripiprazole (partial agonist), or haloperidol (antagonist) prior to administration of the agonist or antagonist radioligand. All three pretreatment compounds showed equivalent dose‐dependent D2 receptor occupancy in the rat striatum with each radioligand. The in vivo receptor occupancy results suggested that the binding of quinpirole, aripiprazole, and haloperidol to the high or low affinity state of the D2 receptor could not be differentiated using radiolabeled agonists or antagonists, presumably due to a predominance of high affinity states of the D2 receptor in vivo. This hypothesis was supported in part by the in vitro binding results. Our in vitro results show that [ 3 H]‐MNPA binds to D2S transfected CHO cell membranes at a single high affinity site. Displacement of [ 3 H]‐(+)‐PHNO binding by quinpirole and elimination of most [ 3 H]‐(+)‐PHNO binding by the guanine nucleotide GppNHp in striatal membranes suggest that the majority of D2 in striatal tissue is G‐protein coupled. Together, these findings suggest that D2 agonist radioligands produce in vivo receptor occupancy comparable to [ 3 H]‐raclopride. Synapse, 2010. © 2010 Wiley‐Liss, Inc.

Clozapine has been demonstrated to bind covalently to proteins as a result of metabolic activation that has been proposed to be a precursor to the serious side effects including death that occur in a small percentage of the population. The covalent modification of proteins by clozapine has been studied by several groups and is well documented; therefore, the department of drug metabolism desired to use [C-14]clozapine as a positive control for covalent binding assays. The preparation of [C-14]clozapine was first conducted using a previous reported route and then using a new route that utilized [C-14]carbonylation as the isotope incorporating step. While this route worked, it was not deemed superior to the previous route. However, this methodology proved quite effective in preparing C-14 labeled dibenzothiazepine and dibenzoxapine ring systems.

Journal of Labelled Compounds and RadiopharmaceuticalsVolume 50, Issue 5-6 p. 523-525 Short Research Article Investigation of isotopic exchange reactions using N-heterocyclic iridium (I) complexes† Mark E. Powell, Corresponding Author Mark E. Powell [email protected] CNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USACNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USASearch for more papers by this authorCharles S. Elmore, Charles S. Elmore CNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USASearch for more papers by this authorPeter N. Dorff, Peter N. Dorff CNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USASearch for more papers by this authorJ. Richard Heys, J. Richard Heys CNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USASearch for more papers by this author Mark E. Powell, Corresponding Author Mark E. Powell [email protected] CNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USACNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USASearch for more papers by this authorCharles S. Elmore, Charles S. Elmore CNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USASearch for more papers by this authorPeter N. Dorff, Peter N. Dorff CNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USASearch for more papers by this authorJ. Richard Heys, J. Richard Heys CNS Chemistry, AstraZeneca Pharmaceuticals LP, 1800 Concord Pike, Wilmington, DE 19850, USASearch for more papers by this author First published: 30 July 2007 https://doi.org/10.1002/jlcr.1239Citations: 18 † Proceedings of the Ninth International Symposium on the Synthesis and Applications of Isotopically Compounds, Edinburgh, 16-20 July 2006. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. REFERENCES 1 (a) Heys JR. Chem Commun 1992; 680; (b) Shu AYL, Saunders D, Levinson SH, Landvatter SW, Mahoney A, Senderoff SG, Mokhallalati MK, Heys JR. J Label Compd Radiopharm 1999; 42: 797; (c) Shu AYL, Heys JR. Tetrahedron Lett 2000; 41: 9015; (d) Hesk D, Gignan G, Lee F, Yang J, Voronin K, Magatti D, McNamara P, Koharski D, Hendershot S, Saluja S, Wang S. J Label Compd Radiopharm 2002; 45: 145; (e)Ellames GJ, Gibson JS, Herbert JM, Kerr WJ, McNeill AH. J Label Compd Radiopharm 2004; 47: 1; (f) HickeyMJ, JonesJR, Kingston LP, Lockley WJS, Mather AN, McAuley BM, Wilkinson DJ. Tetrahedron Lett 2003; 44: 3959. 2 (a) Vazquez-Serrano LD, Owens BT, Buriak JM. Chem Commun 2002; 2581; (b) Lee HM, Jian T, Stevens ED, Nolan SP. Organometallics 2001; 20: 1255; (c) Hillier AC, Lee HM, Stevens ED, Nolan SP. Organometallics 2001; 20: 4246; (d) Vazquez-Serrano LD, Owens BT, Buriak JM. Inorg Chim Acta 2006; 359: 2786. 3 (a) Crabtree RH, Felkin H, Morris GE. J Organomet Chem 1977; 141: 205; (b) Crabtree RH. Acc Chem Res 1979; 12: 331. Citing Literature Volume50, Issue5-6Special Issue: Proceedings of the Ninth International Symposium on the Synthesis and Applications of Isotopically Labelled Compounds, Edinburgh, 16–20 July 2006.April ‐ May 2007Pages 523-525 ReferencesRelatedInformation

Journal of Labelled Compounds and RadiopharmaceuticalsVolume 44, Issue S1 p. S936-S938 Article Polymer-supported radiopharmaceutical precursors: Rapid production of [125I]iodophenylpiperazinium ions Peter N. Dorff, Peter N. Dorff Department of Chemistry, McMaster University, Ontario, Canada, L8S 4M1 Department of Chemistry, The University of Western Ontario, London, Ontario, Canada, N6A 5B7Search for more papers by this authorDuncan H. Hunter, Duncan H. Hunter Department of Chemistry, The University of Western Ontario, London, Ontario, Canada, N6A 5B7Search for more papers by this authorStephen M. Hanrahan, Stephen M. Hanrahan Center for Functional Imaging, Lawrence Berkeley National Laboratory, Berkeley, California, 94720Search for more papers by this authorHenry F. Vanbrocklin, Henry F. Vanbrocklin Center for Functional Imaging, Lawrence Berkeley National Laboratory, Berkeley, California, 94720Search for more papers by this author Peter N. Dorff, Peter N. Dorff Department of Chemistry, McMaster University, Ontario, Canada, L8S 4M1 Department of Chemistry, The University of Western Ontario, London, Ontario, Canada, N6A 5B7Search for more papers by this authorDuncan H. Hunter, Duncan H. Hunter Department of Chemistry, The University of Western Ontario, London, Ontario, Canada, N6A 5B7Search for more papers by this authorStephen M. Hanrahan, Stephen M. Hanrahan Center for Functional Imaging, Lawrence Berkeley National Laboratory, Berkeley, California, 94720Search for more papers by this authorHenry F. Vanbrocklin, Henry F. Vanbrocklin Center for Functional Imaging, Lawrence Berkeley National Laboratory, Berkeley, California, 94720Search for more papers by this author First published: 23 April 2012 https://doi.org/10.1002/jlcr.25804401329AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume44, IssueS1Supplement: Journal of Labelled Compounds and RadiopharmaceuticalsMay 2001Pages S936-S938 RelatedInformation