Microwave-induced nucleophilic [18F]fluorination on aromatic rings: synthesis and effect of halogen on [18F]fluoride substitution of meta-halo (F, Cl, Br, I)-benzonitrile derivatives.
The meta-halo-3-methylbenzonitrile derivatives (-F, -Cl, -Br, -I) were synthesized as model compounds to study reactivity towards aromatic nucleophilic substitution. A single-mode microwave system was incorporated into a commercial radiochemical synthetic module for (18)F labeling. Labeling yields of 64% for fluoro-, 13% for bromo- and 9% for chloro-precursors were achieved in DMSO in <3 min. The observed order of reactivity of the leaving groups toward aromatic nucleophilic substitution was F>>Br>Cl>>>I.
Guo
Ning
N
Department of Radiology & Radiological Sciences, Vanderbilt University School of Medicine, 1161 21st Avenue South, Nashville, TN 37232, USA. ning.guo@vanderbilt.edu
Alagille
David
D
Tamagnan
Gilles
G
Price
Ronald R
RR
Baldwin
Ronald M
RM
D005462:Fluorine Radioisotopes / Q000737:chemistry* / Q000528:radiation effects*; D006219:Halogens / Q000737:chemistry* / Q000528:radiation effects*; D007553:Isotope Labeling / Q000379:methods*; D008872:Microwaves; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry* / Q000528:radiation effects*
D005462:Fluorine Radioisotopes; D006219:Halogens; D011084:Polycyclic Aromatic Hydrocarbons