Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy 241 Exploring Palladium-Mediated 11C/12C-Carbonylation Reactions PET Tracer Development Targeting the Vesicular Acetylcholine Transporter SARA ROSLIN ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6192 ISBN 978-91-513-0136-5 UPPSALA urn:nbn:se:uu:diva-332359 2017 Dissertation presented at Uppsala University to be publicly examined in Hall B:21, BMC, Husargatan 3, Uppsala, Friday, 15 December 2017 at 09:15 for the degree of Doctor of Philosophy (Faculty of Pharmacy). The examination will be conducted in English. Faculty examiner: Ph.D. Victor Pike (National Institute of Mental Health, Molecular Imaging Branch). Abstract Roslin, S. 2017. Exploring Palladium-Mediated 11C/12C-Carbonylation Reactions. PET Tracer Development Targeting the Vesicular Acetylcholine Transporter. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy 241. 99 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-513-0136-5. The work presented herein describes the utilization and exploration of palladium-mediated incorporations of carbon monoxide and/or [11C]carbon monoxide into compounds and structural motifs with biological relevance. The first part of the thesis describes the design, synthesis and 11C-labeling of prospective PET tracers for the vesicular acetylcholine transporter (VAChT), a target affected in several neurodegenerative diseases. Different parts of the benzovesamicol scaffold were modified in papers I and II to probe the binding to VAChT. The key motif was an amide functional group, which enabled the use of palladium-mediated 11C/12C-carbonylations to synthesize and evaluate two different sets of structurally related ligands. The second part of the thesis describes the exploration of different aspects of palladium- mediated 11C/12C-carbonylation reactions. The utilization of unactivated alkyl iodides and bromides as coupling partners in a carbonylative Suzuki-Miyaura reaction was described in paper III. The combination of palladium-catalysis together with visible light irradiation enabled their functionalization via an alkyl radical. The mild conditions, namely the ambient temperature and pressure of carbon monoxide, and the accessible reaction set-up further added to the utility of the method. A palladium(II)-mediated oxidative 11C-carbonylation for synthesis of 11C-labeled ureas was described in paper IV. Utilizing only amines in addition to a palladium-source and [11C]carbon monoxide, the method proved to be facile and robust, thus representing a simplification in relation to methods using other 11C-synthons for synthesis of 11C-labeled ureas. Finally, a palladium(0)-catalyzed carbonylation reaction for synthesis of acylamidines was presented in paper V. The versatility of the method was demonstrated by one-pot cyclizations to form oxadiazoles and triazoles together with the corresponding 11C-carbonylation reaction to produce 11C-labeled acylamidines and an oxadiazole. The work described herein has thus contributed structural information in the search for a PET tracer for VAChT and identified a viable lead structure for future investigations. Furthermore, investigation of reaction conditions that would allow use of either elusive or accessible substrates led to the development of methods for synthesis and/or 11C-labeling of various carbonylated compounds. Keywords: Carbonylation, palladium, carbon-11, radiochemistry, positron emission tomography, vesicular acetylcholine transporter, vesamicol, alkyl halide, oxidative carbonylation, acylamidine, oxadiazole, heterocycle Sara Roslin, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry, Box 574, Uppsala University, SE-75123 Uppsala, Sweden. © Sara Roslin 2017 ISSN 1651-6192 ISBN 978-91-513-0136-5 urn:nbn:se:uu:diva-332359 (http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-332359) Till min växande familj List of Papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. I Bergman, S., Estrada, S., Hall, H., Rahman, R., Blomgren, A., Larhed, M., Svedberg, M., Thibblin, A., Wångsell, F., Antoni, G. (2014) Synthesis and Labelling of a Piperazine-Based Library of 11C-Labeled Ligands for Imaging of the Vesicular Acetylcholine Transporter. Journal of Labelled Compounds and Radiopharma- ceuticals, 57(8):525–532. II Roslin, S., De Rosa, M., Deuther-Conrad, W., Eriksson, J., Odell, L.R., Antoni, G., Brust, P., Larhed, M. (2017) Synthesis and In Vitro Evaluation of 5-Substituted Benzovesamicol Ana- logs containing N-Substituted Amides as Potential Positron Emission Tomography Tracers for the Vesicular Acetylcholine Transporter. Bioorganic & Medicinal Chemistry, 25(19):5095– 5106. Part of special issue “Design and Synthesis of Bioactive Compounds”. III Roslin, S., Odell, L.R. (2017) Palladium and Visible-Light Me- diated Carbonylative Suzuki-Miyaura Coupling of Unactivated Alkyl Halides and Aryl Boronic Acids. Chemical Communica- tions, 53:6895–6898. IV Roslin, S., Brandt, P., Nordeman, P., Larhed, M., Odell, L.R., Eriksson, J. (2017) Synthesis of 11C-Labelled Ureas by Palla- dium(II)-Mediated Oxidative Carbonylation. Molecules, 22(10):1688. Part of special issue “Current Aspects of Radio- pharmaceutical Chemistry”. V Rydfjord, J., Roslin, S., Roy, T., Abbas, A., Stevens, M., Larhed, M., Odell, L.R. Acylamidines by Pd-Catalyzed Aminocarbonyl- ation: One-Pot Cyclizations and 11C-Labeling. Manuscript. Reprints were made with permission from the respective publishers. Author Contribution Statement The following contributions were made by the author of this thesis to each paper: I Synthesized reference compounds and starting material for 11C- labeling experiments, prepared 11C-labeled compounds, col- lated experimental data and drafted the manuscript. II Designed and synthesized compounds for affinity determina- tions and synthesized starting material for 11C-labeling experi- ments, performed 11C-labeling experiments, collated experi- mental data and drafted the manuscript. III Designed and carried out method development, designed and synthesized starting materials and final compounds, collated ex- perimental data and drafted the manuscript. IV Designed and carried out method development, designed and synthesized starting material and reference compounds, per- formed 11C-labeling experiments, collated data and drafted the manuscript. V Performed 11C-labeling experiments, assisted in collating ex- perimental data and manuscript preparation. Papers Not Included in This Thesis Lampa, A.K., Bergman, S.M., Gustafsson, S.S., Alogheli, H., Åkerblom, E.B., Lindeberg, G.G., Svensson, R.M., Artursson, P., Danielson, U.H., Kar- lén, A., Sandström, A. (2014) Novel Peptidomimetic Hepatitis C Virus NS3/4A Protease Inhibitors Spanning the P2-P1’-region. ACS Medicinal Chemistry Letters, 5(3): 249–254. Chow, S.Y., Stevens, M.Y., Åkerbladh, L., Bergman, S., Odell, L.R. (2016) Mild and Low-Pressure fac-Ir(ppy)3-Mediated Radical Aminocarbonylation of Unactivated Alkyl Iodides through Visible-Light Photoredox Catalysis. Chemistry – A European Journal, 22(27):9155–9161. Hot Paper. Featured on the cover of the July 2016 issue. Roslin, S., Odell, L.R. (2017) Visible-Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp3)-Substrates. European Journal of Organic Chemistry, 2017(15):1993–2007. Part of Special issue: Photoredox Catalysis. Contents Thesis Overview ........................................................................................... 15 Introduction ................................................................................................... 17 Palladium Catalysis .................................................................................. 17 The Palladium Mediated Carbonylation Reaction ................................... 18 Positron Emission Tomography and Tracer Development ...................... 21 Positron Emission Tomography .......................................................... 21 Considerations in Tracer Development ............................................... 23 11C-Carbonylative Radiochemistry ...................................................... 26 Targeting the Cholinergic System ............................................................ 29 The Cholinergic System ...................................................................... 29 The Cholinergic System in Neurodegenerative Diseases .................... 30 The Vesicular Acetylcholine Transporter ............................................ 32 Development of Ligands for the Vesicular Acetylcholine Transporter ........................................................................................... 32 Design, Synthesis and 11C-Labeling of Ligands for the Development of a PET Tracer for VAChT ................................................................................ 36 Synthesis and Labelling of a Piperazine-Based Library of 11C-Labeled Ligands for Imaging of the Vesicular Acetylcholine Transporter (Paper I) .................................................................................................. 37 Aim ...................................................................................................... 37 Design, Synthesis and 11C-Labeling .................................................... 3 7 Preclinical evaluation........................................................................... 39 Synthesis and In Vitro Evaluation of 5-Substituted Benzovesamicol Analogs containing N-Substituted