title: Titania-catalyzed radiofluorination of tosylated precursors in highly aqueous medium.
abstract: Nucleophilic radiofluorination is an efficient synthetic route to many positron-emission tomography (PET) probes, but removal of water to activate the cyclotron-produced [(18)F]fluoride has to be performed prior to reaction, which significantly increases overall radiolabeling time and causes radioactivity loss. In this report, we demonstrate the possibility of (18)F-radiofluorination in highly aqueous medium. The method utilizes titania nanoparticles, 1:1 (v/v) acetonitrile-thexyl alcohol solvent mixture, and tetra-n-butylammonium bicarbonate as a phase-transfer agent. Efficient radiolabeling is directly performed with aqueous [(18)F]fluoride without the need for a drying/azeotroping step to significantly reduce radiosynthesis time. High radiochemical purity of the target compound is also achieved. The substrate scope of the synthetic strategy is demonstrated with a range of aromatic, aliphatic, and cycloaliphatic tosylated precursors.
authors: Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine at University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095, United States.
authors: Maxim E
authors: ME
authors: Sergeev
authors: Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine at University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095, United States.
authors: Federica
authors: F
authors: Morgia
authors: Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine at University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095, United States.
authors: Mark
authors: M
authors: Lazari
authors: Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine at University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095, United States.
authors: Christopher
authors: C
authors: Wang
authors: Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine at University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095, United States.
authors: R Michael
authors: RM
authors: van Dam
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000438:Alcohols / Q000737:chemistry; D002384:Catalysis; D005462:Fluorine Radioisotopes / Q000737:chemistry*; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry; D014025:Titanium / Q000737:chemistry*; D014105:Tosyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D000438:Alcohols; D005462:Fluorine Radioisotopes; D014105:Tosyl Compounds; D014867:Water; C009495:titanium dioxide; D014025:Titanium; C032159:acetonitrile