Radiosynthesis of a 2‐substituted 4,5‐dihydro‐1H‐[2‐11C] imidazole: the I2 imidazoline receptor ligand [11C] benazoline |
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Abstract: | Benazoline (2‐naphthalen‐2‐yl‐4,5‐dihydro‐1H‐imidazole) is a selective high‐affinity ligand for the imidazoline I2 receptor. This compound was labelled with carbon‐11 (T1/2=20.4 min) at the number two carbon atom of its 2‐imidazoline ring. Cyclotron‐produced [11C]carbon dioxide reacted with 2‐naphthylmagnesium bromide to give 2‐[carboxyl‐11C]naphthoic acid in 60% radiochemical yield. The latter was heated with a mixture of ethylenediamine and its dihydrochloride at 300°C to give [11C]benazoline in 16% overall yield, relative to [11C]carbon dioxide and with a specific radioactivity of 54 GBq/μmol, decay corrected for end of irradiation. The procedure requires about 45 min from end of cyclotron irradiation. This method should be extendable to other imidazolines. Copyright © 2003 John Wiley & Sons, Ltd. |
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Keywords: | [2‐11C]imidazolines [11C]benazoline imidazoline receptor |
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