title: Syntheses of high-valent fac-[99mTcO3]+ complexes and [3+2] cycloadditions with alkenes in water as a direct labelling strategy.
abstract: Reported herein is a new concept for the labelling of biomolecules with small [(99m)TcO(3)](+) complexes through a [3+2] cycloaddition with alkenes for radiopharmaceutical applications. We developed convenient reactions for the synthesis of small, water stable fac-[TcO(3)(tacn-R)](+) complexes ((99)Tc and (99m)Tc, tacn = 1,4,7-triazacyclononane, R = H, -CH(2)-C(6)H(5), -CH(2)-C(6)H(4)COOH). With alkenes, these high valent [(99m)TcO(3)](+) complexes undergo [3+2] cycloaddition with formation of the corresponding Tc(V)-glycolato complexes. The (99m)Tc(V) and (99m)Tc(VII) complexes are stable at 37 degrees C in water and in the presence of serum proteins. Therefore, new opportunities in technetium chemistry are enabled with a high potential for medicinal and biological applications. In contrast to classical labelling, the presented strategy is ligand and not metal-centred.
authors.affiliation: Institute of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: Henrik
authors.initials: H
authors.lastname: Braband
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tooyama
authors.forename: Thomas
authors.initials: T
authors.lastname: Fox
authors.forename: Roger
authors.initials: R
authors.lastname: Alberto
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003500:Cyclization; D015609:Organotechnetium Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D011506:Proteins / Q000138:chemical synthesis / Q000737:chemistry; D019275:Radiopharmaceuticals / Q000138:chemical synthesis* / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D000475:Alkenes; D015609:Organotechnetium Compounds; D011506:Proteins; D019275:Radiopharmaceuticals; C535016:fac-(99mTcO3)+ complex; D014867:Water