title: Efficient radiosynthesis of carbon-11 labelled uncharged Thioflavin T derivatives using [11C]methyl triflate for beta-amyloid imaging in Alzheimer's Disease with PET.
abstract: The synthesis of carbon-11 amino function labelled uncharged Thioflavin T derivatives is known to be performed by reaction of the demethyl-precursors with [11C]methyl iodide but the labelling yields are only mediocre. The use of [11C]methyl triflate improved the radiochemical yield of three potential beta-amyloid imaging PET-radiotracers significantly. Performance of the labelling reaction by reacting the corresponding precursor molecules with [11C]methyl triflate for 1 min at 80 degrees C led to radiochemical yields of 44+/-10% (n=5) for [11C]6-Me-BTA-1, 68+/-4% (n=10) for [11C]BTA-1 and 58+/-2% (n=5) for [11C]6-OH-BTA-1 with respect to [11C]methyl triflate. In production runs (60 min, 50 microA) up to 6500 MBq (mean: 4000+/-1900 MBq) of [11C]6-Me-BTA-1, 7900 MBq (mean: 6000+/-1000 MBq) of [11C]BTA-1 and 7100 MBq (mean: 6300+/-600 MBq) of [11C]6-OH-BTA-1 could be obtained ready for intravenous injection. The radiochemical purity was >95% with specific activities in the range of 80-120 GBq/micromol (EOS) within a total synthesis time of less than 40 min after EOB.
authors.affiliation: Radiopharmacy, PET-Center, University Hospital Tübingen, Roentgenweg 15, D-72076 Tübingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Solbach
authors.forename: M
authors.initials: M
authors.lastname: Uebele
authors.forename: G
authors.initials: G
authors.lastname: Reischl
authors.forename: H-J
authors.initials: HJ
authors.lastname: Machulla
mesh_terms: D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D016229:Amyloid beta-Peptides / Q000032:analysis; D000814:Aniline Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D052160:Benzothiazoles; D002250:Carbon Radioisotopes / Q000737:chemistry*; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D008698:Mesylates / Q000138:chemical synthesis / Q000737:chemistry*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*; D013844:Thiazoles / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: C473078:2-(4'-methylaminophenyl)benzothiazole; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D052160:Benzothiazoles; D002250:Carbon Radioisotopes; D008698:Mesylates; D019275:Radiopharmaceuticals; D013844:Thiazoles; C009462:thioflavin T; C012077:trifluoromethanesulfonic acid