Fluorine-18: positron emission

However, a body of evidence is being accumulated that if a halogen, such as a bromine or an iodine atom, is replaced by a beta-fluoroethyl group, the electronic and polar properties of the drug can be pretty much the same. So, what psychedelics have a bromo or an iodo group Obviously, DOB and DOI. Thus, DOEF is a natural candidate for fluorine-18 positron emission tomography, and also a natural candidate for clinical trials. And, voila, it is an active material. 

Fluorine-18 Positron emission 1.83 hours PET studies of heart, brain... 

Positron emission tomography (PET) makes use of a short-lived positron emitter such as fluorine-18 to image human tissue with a degree of detail not possible with x-rays. It has been used extensively to study brain function (see illustration) and in medical diagnosis. For example, when the hormone estrogen is labelled with fluorine-18 and injected into a cancer patient, the fluorine-bearing compound is preferentially absorbed by the tumor. The positrons given off by the fluorine atoms are quickly annihilated when they meet... 

Considerable interest has been focused on the efficient and rapid synthesis of 2-deoxy-2-[ F]fluoro-D-gIucose, a popular imaging agent for positron-emission tomography (see Section III, 1). However, introduction of a fluorine atom at C-2 by nucleophilic displacement is generally not easy on account of the weak nucleophilic character of the fluoride ion. One possible... 

Yatham, L.N., Liddle, P. F. Dennie, J. (1999). Decrease in brain serotonin 2 receptor binding in patients with major depression following desipramine treatment a positron emission tomography study with fluorine-18-labeled setoperone. Arch. Gen. Psychiatry, 56, 705-11. 

Ding Y-S, Eowler JS (1996) 18F-Labeled tracers for positron emission tomography studies in the neurosciences. In Ojima 1, McCarthy J, Welch JT (eds) Biomedical frontiers of fluorine chemistry. ACS Symp Series 639. The American Chemical Society, Washington DC, chap 23, p 328... 

The next two chapters are dedicated to radiopharmaceutical contrast agents starting with a detailed description of the chemistry of p -emitting compounds based on fluorine-18. Particular emphasis is laid on the different radiolabeled precursors and their suitability for the rapid synthesis of compounds useful for positron emission tomography. 

Tamaki N, Yonekura Y, Yamashita K, Saji H, Magata Y, Senda M et al. Positron emission tomography using fluorine-18 deoxyglucose in evaluation of coronary artery bypass grafting. Am J Cardiol 1989 64 860-865... 

Gropler RJ, Geltman EM, Sampathkumaran K, Perez JE, Schechtman KB, Conversano A et al. Comparison of carbon-11-acetate with fluorine-18-fluorodeoxyglucose for delineating viable myocardium by positron emission tomography. J Am Coll Cardiol 1993 22 1587-1597... 

Fluorine-18 Chemistry for Molecular Imaging with Positron Emission Tomography... 

Fluorine-18 is an artificial radionuclide, discovered in 1937. It decays with a half-life of 109.8 min for 97% by positron emission and for 3% by electron capture to the stable isotope oxygen-18. The maximum jS+-particle energy is 0.635 MeV [4],... 

C. Halldin, T. Hogberg, L. Farde, Fluorine-18-labeled NCQ 115, a selective dopamine D-2 receptor ligand. Preparation and positron emission tomography, Nucl. Med. Biol. 21 (1994) 627-631. 

Most of the fluoro derivatives of proline described in the literature are fluorinated in the 4 position. 4-Fluoroprolines are able to mimic 4-hydroxyproline, present in some proteins and polypeptides. On the other hand, 4-fluorination could suppress oxidative metabolism or modified ring conformation of ligands.The labeled analogues may be used as probes in PET (positron emission tomography) for localization of tumors... 

Ernst, M., Zametkin, A.J., Matochik, J.A., Jons, P.H., and Cohen, R.M. (1998) DOPA decarboxylase activity in attention deficit disorder adults. A [fluorine-18]fluorodopa positron emission tomographic study. / Neurosci 18 5901-5907. 

Bhn J, Baron JC, Dubois B, et al Loss of brain 5-HT2 receptors in Alzheimer s disease in vivo assessment with positron emission tomography and fluorine-18 setoperone. Brain 116 497-510, 1993... 

Aryltriazenes can also be decomposed by hydrogen fluoride in organic solution after extraction from their aqueous mother phase. In this case, hydrogen fluoride can be used in small excess but the nature of the solvent is crucial for example, tetrahydrofuran gives complex mixtures, dichloromethane promotes radical reactions (dimerizations, reductions) and acetic acid favors triazene decomposition before fluorination. Aromatic and haloaromatic compounds seem to be the best solvents.283 Such a technique, especially suited for the rapid introduction of an 18F atom, has been employed to produce [ 8F]haloperidol (3), the specific receptors of which have been localized in the brain by positron emission transaxial tomography.298... 

Many fluorinations by electropositive fluorine reagents produce a-fluoro carbonyl compounds as the final result An extensive review exists on the preparation of a-fluorocarbonyl compounds [10]. Also, electropositive reagents are used, widely in the preparation ofISF-labeled radioactive materials required in positron emission tomography for biomedical research Excellent reviews are available on fluonne-18 labeling [11, 12]. 

Renewed interest in the fluorination of quaternary ammonium salts is prompted by the need for rapid fluorination techniques to incorporate 18F (t /f 110 mm) in positron emission tomography (PET) studies One promising approach is displacement of trimethylammomum ion, bound directly to an aromatic ring, by fluoride ion This technique was initially developed with substituted phenyltnmeth-ylammomum perchlorates and unlabeled cesium fluoride in dimethyl sulfoxide or acetonitrile [73] (equation 14)... 

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