Nucleophilic aromatic substitution by [18F]fluorideion has been demonstrated on rings containing electron donating groups in addition to the necessary electron withdrawing and leaving groups. The reaction of 18F− with a series of aromatic nitro aldehydes having protected hydroxyl substituents on the ring was studied. The reactivity of the aromatic ring towardsnucleophilic substitution to give 18F-labeled
Seyferth-Gilbert Homologation as a Route to<sup>18</sup>F-Labeled Building Blocks: Preparation of Radiofluorinated Phenylacetylenes and Their Application in PET Chemistry
作者:Philipp Krapf、Raphael Richarz、Elizaveta A. Urusova、Bernd Neumaier、Boris D. Zlatopolskiy
DOI:10.1002/ejoc.201501377
日期:2016.1
A convenient method for the preparation of hitherto unknown ([18F]fluorophenyl)acetylenes ([18F]FPAs) using the Seyferth–Gilberthomologation is reported. The novel buildingblocks were efficiently prepared from easily accessible [18F]fluorobenzaldehydes by using the Bestmann–Ohira reagent. High radiochemical yields and excellent radiochemical purities were achieved within only 20 min of reaction time;
2-Amino-2′-[18F]fluorobenzhydrols, intermediates for the synthesis of [2′-18F]-1,4-benzodiazepine-2-ones
作者:Peter Johnström、Sharon Stone-Elander
DOI:10.1002/jlcr.2580340206
日期:1994.2
A method for synthesizing 18F-labelled 2-amino-2′-fluorobenzhydrols under nocarrier-added conditions for use as radiolabelled intermediates in the synthesis of[2′-18F]-1,4-benzodiazepine-2-ones is presented. Anilinodichloroborane reagents were formed by the reaction of boron trichloride with 4-chloro-N-methylaniline, 6a, 4-nitro-N-methylaniline, 6b, 4-nitro-N-ethylaniline, 6c, and 4-chloro-N-(2,2,2-trifluoroethyl)aniline, 6d. 2-[18F]Fluorobenzaldehyde, 5, synthesized in 55–70% yields by the nucleophilic aromatic substitution of 2-nitrobenzaldehyde with the Kryptofix/K+ complex of [18F]F−, was subsequently reacted with the anilinodichloroborane coupling reagents with aromatic substitution occurring ortho to the amino group. The resulting 2-amino-2′-[18F]fluorobenzhydrols, 7a - 7d, were produced in conversions of 60–95% with reaction time ⩽ 10 min at room temperature or 60°C, depending on the aniline used. The total synthesis time, including evaporation of the target water, was 60–65 min. The total radiochemical conversions were of the order of 50–65% for 7a - 7c and 35–45% for 7d, decay-corrected and based on [18F]F−.
Neither azeotropic drying, nor base nor other additives: a minimalist approach to <sup>18</sup>F-labeling
作者:R. Richarz、P. Krapf、F. Zarrad、E. A. Urusova、B. Neumaier、B. D. Zlatopolskiy
DOI:10.1039/c4ob01336k
日期:——
A novel, efficient, time-saving and reliable radiolabeling procedure via nucleophilic substitution with [18F]fluoride is described. Different radiolabeled aliphatic and aromatic compounds were prepared in high radiochemical yields simply by heating of quaternary anilinium, diaryliodonium and triarylsulfonium [18F]fluorides in suitable solvents. The latter were obtained via direct elution of 18F− from
respectively). When the electrophilicity of the leaving group substituted carbon atom is expressed by its 13C NMR chemical shift a good correlation with the reactionrate 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