Noninvasive imaging in living subjects with positron emission tomography (PET) provides early detection of diseases in humans. For this application, it is necessary to prepare specific molecular ...imaging probes labeled with positron-emitting radioisotopes such as fluorine-18 for obtaining high-quality PET imaging. In this review, we describe recent trends in the F-18 radiolabeling method for the introduction of no-carrier-added fluorine-18, which was obtained from an
18
O(p,n)
18
F reaction, into a specific molecular site, which in turn is intended to serve as an imaging agent for PET study. These labeling protocols are based on ionic liquid media
18
F radiofluorination in the presence of some water, enzymatic
18
F fluorination using fluorinase in water solution, non-polar protic alcohol media
18
F radiofluorination and its mechanism, and nucleophilic
18
F fluorination of an aromatic iodonium salt precursor.
Synthesis of 18F-labelled biotin analogues Blom, Elisabeth; Itsenko, Oleksiy; Långström, Bengt
Journal of labelled compounds & radiopharmaceuticals,
August 2011, Letnik:
54, Številka:
10
Journal Article
Recenzirano
Odprti dostop
A one‐step 18F‐labelling strategy was used to prepare three labelled analogues of the vitamin biotin, which can be useful as tracers because of biotin's high affinity for avidin. The labelled ...compounds were obtained in decay‐corrected yields of up to 35% and specific radioactivity of 320 GBq/µmol. When evaluated in situ, the analogues showed good affinity for avidin: 60–75% of the radiolabelled compounds were bound to avidin within 5 minutes. The binding was site‐specific, as shown by blocking experiments with native biotin.
A one‐step 18F‐labelling strategy was used to prepare three labelled analogues of biotin. The labelled compounds were obtained in decay‐corrected yields of up to 35%. The analogues showed good affinity for avidin in situ.
Fluoropyridyl derivatives of 3,2-cpyrazolo-corticosteroids have high affinity for the glucocorticoid receptor (GR) and are highly active glucocorticoids. They are thus considered to be excellent ...candidates for PET imaging of GR containing tissues when labeled with fluorine-18 (t1/2=110min). Previously reported syntheses of these fluorinated glucocorticoids were accomplished by conventional thermal nucleophilic halogen exchange reactions with chloropyridyl precursors. These reactions were found to proceed at rates too slow for feasible application to radiosynthesis using 18Ffluoride. We have applied microwave-heating methods to these reactions and found that significant rate enhancements can be realized. Kinetic experiments showed an average relative rate ratio of 3/1 for microwave versus conventional heating and preparative experiments showed an average relative conversion ratio of 4.5/1 during the initial 120min, a period approximating one half-life of the isotope. The microwave method described was used to prepare previously unreported 2′-(2-fluoro-4-pyridyl)-11β,17,21-trihydroxy-16α-methyl-20-oxo-pregn-4-eno-3,2-c-pyrazole, which was evaluated for biological activity.
Carbon-fluorine bond formation Furuya, Takeru; Kuttruff, Christian A; Ritter, Tobias
Current opinion in drug discovery & development
11, Številka:
6
Journal Article
A selection of carbon-fluorine bond-forming reactions that have been developed in the recent past are presented. An overview of the most common fluorination reagents is followed by descriptions of ...fluorination reactions that are organized by reactivity. The distinction between nucleophilic and electrophilic fluorinations is highlighted, as well as between aliphatic and aromatic fluorinations. Each section is divided into more specific reaction classes and examples for the synthesis of pharmaceuticals, 18Fradiolabeling and mechanistic investigations are provided.
Anhydrous tetrabutylammonium fluoride(TBAF_(anh).) has been found to be a highly efficient fluorinating reagent for nucleophilic aromatic fluorinations such as fluorodenitration or halogen ...exchange(Halex) reaction.The products were formed in high to excellent yields under surprisingly mild reaction conditions and no phenol or ether side-products were detected in these reactions.
Various fluorinated chiral compounds were synthesized by the reactions of amino alcohols and diols with bis(2−methoxyethyl)aminosulfur trifluoride (Deoxofluor).
Various fluorinated chiral compounds ...were synthesized using bis(2-methoxyethyl)aminosulfur trifluoride (Deoxofluor) as a nucleophilic fluorinating reagent. Reactions of Deoxofluor (
1) with amino alcohols (
2a–
d) and diols (
2e–
g) in methylene chloride at room temperature led to the formation of the corresponding fluoro derivatives (
3a–
g) in good yields.
In connection with our investigation of the competitive mesolytic cleavages 1 of radical anions we have prepared several symmetrically substituted 2,7-bis(halomethyl)naphthalene derivatives....
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