129841-08-3Relevant academic research and scientific papers
Fast and reliable method for the preparation of ortho- and para-[ 18F]fluorobenzyl halide derivatives: Key intermediates for the preparation of no-carrier-added PET aromatic radiopharmaceuticals
Lemaire, Christian,Libert, Lionel,Plenevaux, Alain,Aerts, Jo?l,Franci, Xavier,Luxen, André
experimental part, p. 48 - 55 (2012/06/18)
A fast and reliable method suitable for the automated preparation of (substituted) [18F]fluorobenzyl halides from several [ 18F]fluorobenzaldehydes was developed. Aromatic nucleophilic substitution of trimethylammonium benzaldehyde t
Nucleophilic [18F]Fluorination and subsequent decarbonylation of methoxy-substituted nitro- and halogen-benzenes activated by one or two formyl groups
Shen, Bin,Loeffler, Dirk,Reischl, Gerald,Machulla, Hans-Juergen,Zeller, Klaus-Peter
experimental part, p. 113 - 119 (2011/08/03)
As model reactions for the introduction of 18F into protected aromatic amino acids, the replacement of NO2, Cl, Br and F by [ 18F]fluoride in 2-isophthalaldehyde and 2-terephthalaldehyde derivatives which model 18/su
Nucleophilic substitution of nitro groups by [18F]fluoride in methoxy-substituted ortho-nitrobenzaldehydes-A systematic study
Shen, Bin,L?ffler, Dirk,Reischl, Gerald,Machulla, Hans-Jürgen,Zeller, Klaus-Peter
experimental part, p. 216 - 224 (2009/07/25)
As model reactions for the introduction of [18F]fluorine into aromatic amino acids, the replacement of NO2 by [18F]fluoride ion in mono- to tetra-methoxy-substituted ortho-nitrobenzaldehydes was systematically investigated. Unexpectedly, the highly methoxylated precursors 2,3,4-trimethoxy-6-nitrobenzaldehyde and 2,3,4,5-tetramethoxy-6-nitrobenzaldehyde showed high maximum radiochemical yields (82% and 48% respectively). When the electrophilicity of the leaving group substituted carbon atom is expressed by its 13C NMR chemical shift a good correlation with the reaction rate at the beginning of the reaction (first min) was found (R2 = 0.89), whereas the maximum radiochemical yields correlated much poorer with this electrophilicity parameter. This may be caused by side reactions becoming influencial in the further reaction course. As possible side reactions the demethylation of methoxy groups and intramolecular redox reactions could be detected by HPLC/MS.
Effect of aldehyde and methoxy substituents on nucleophilic aromatic substitution by [18F]fluoride
Shen, Bin,L?ffler, Dirk,Zeller, Klaus-Peter,übele, Michael,Reischl, Gerald,Machulla, Hans-Jürgen
, p. 1461 - 1468 (2008/09/18)
For a series of benzaldehydes only with a leaving group or with both a leaving group and a single methoxy substituent 18F-fluorination via nucleophilic aromatic substitution (SNAr) was studied in DMF and Me2SO. In general, the radiochemical yields were clearly higher in DMF than in Me2SO. In the fluorodehalogenation reaction (leaving group: halogen = Br, Cl), extremely low radiochemical yields were observed in Me2SO (2SO (within 3 min reaction time, 90% of the precursor was consumed; radiochemical yield = 1.0 ± 0.5%); however, in DMF oxidation was always kept at a low level during the entire reaction (13C-NMR ppm values of the aromatic carbon atom bearing the leaving group.
NO-CARRIER ADDED (NCA) ARYL FLUORIDES VIA THE NUCLEOPHILIC AROMATIC SUBSTITUTION OF ELECTRON-RICH AROMATIC RINGS
Ding, Y.-S.,Shiue, C.-Y.,Fowler, J. S.,Wolf, A. P.,Plenevaux, A.
, p. 189 - 205 (2007/10/02)
Nucleophilic aromatic substitution by fluoride ion has been demonstrated on rings containing electron donating groups in addition to the necessary electron withdrawing and leaving groups.The reaction of (18)F- with a series of aromatic nitro aldehydes having protected hydroxyl substituents on the ring was studied.The reactivity of the aromatic ring towards nucleophilic substitution to give (18)F-labeled aromatic fluoroaldehyde derivatives is correlated with electron density at the reaction center.The effect of a number of protected hydroxyl substituents is reported. 13C-NMR was used as a sensitive probe for the changes in electron distribution at the ring carbon atoms.Radiochemical yield correlated with ppm values at the reaction center.This methodology has been applied to the synthesis of no-carrier-added(NCA) 6-fluoro-L-DOPA.The extension of this strategy to the syntheses of other labeled pharmaceuticals appears promising.
