[2′‐ 18 F]‐2‐oxoquazepam: Synthesis of a 5‐(2‐[ 18 F]fluorophenyl)‐1,4‐benzodiazepine‐2‐one

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A method for synthesizing the alkylating agent 2,2,2-trifluoroethyl triflate labelled with [ 18FIfluoride in the two position is presented. Ethyl [2-l~F]-mfluoroacetate was synthesized by the nucleophilic reaction of [ 18FIF-with ethyl bromodifluoroacetate in DMSO (4560%. 5 min, 80 OC) and subsequently converted to [2-18F]-2,2,2-trifluoroethanol using alane in THF (85-95%, 2 min, 40 OC). Reaction with triflic anhydride in 2,6-lutidine produced [2-18F]-2,2,2-trifluoroethyl triflate (70-80%, 1 min, 0 OC). In all three cases the product was removed from the reaction vessel by heating to distil under a stream of nitrogen. [2-18F]-2,2,2-Trifluoroethyl triflate was used to label 2-oxoquazepam by N-alkylation in a to1uene:DMF mixture (80-85%, 20 min, 120 OC). Although no-carrier-added [18F]F-was used, considerable unlabelled ethyl trifluoroacetate was produced in the first reaction. Varying the conditions for the fluoro-debromination reaction did not appreciably improve the relative ratio of labelled to unlabelled ester. The specific activity of the labelled 1.4-benzodiazepine-2-one obtained from 1850 MBq [18F]F-was found to be =37 MBq/pmol (1 mCi/pinol).

The ¹⁸F‐labelled alkylating agent 2,2,2‐trifluoroethyl triflate: Synthesis and specific activity

Johnström

Stone‐Elander

1995

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PET radioligands targeting the brain GABA_A/benzodiazepine receptor complex

Andersson

Halldin

2013

The development of positron emission tomography radioligands for the GABAA /benzodiazepine receptor complex (GABAA receptor) labeled with (11) C and (18) F is examined. The review covers labeling strategies as well as brief biological evaluations of radioligands. In addition, we assess the special considerations that must be taken during a development program for radioligands targeting the GABAA receptor and explore some of the challenges that lie ahead.

Labeling of human C‐peptide by conjugation with N‐succinimidyl‐4‐[¹⁸F]fluorobenzoate

Fredriksson¹,

Johnström²,

Stone‐Elander³

et al. 2001

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We have labeled proinsulin connecting peptide (C‐peptide) with fluorine‐18 (t½=109.7 min) in order to perform in vivo biodistribution and pharmacokinetic studies with position emission tomography (PET). This study reports the optimization of the conjugation labeling in the N‐terminal with N‐succinimidyl‐4‐[18F]fluorobenzoate ([18F]SFB). In preparative runs N‐4‐[18F]fluorobenzoyl‐C‐peptide ([18F]FB‐C‐peptide) was produced in 8–12% decay‐corrected yields, counted from resolubilized [18F]F−, in less than 5 h. The specific radioactivity of [18F]FB‐C‐peptide, determined using ELISA for one of the preparations, was around 70 GBq/μmol at end of synthesis. Copyright © 2001 John Wiley & Sons, Ltd.