The false adrenergic neurotransmitter [11C]meta-hydroxyephedrine ([11C]HED) is currently the PET tracer of choice for assessment of myocardial sympathetic innervation. The molecule is metabolised in the 4-position of the aromatic ring. The resulting radiolabelled metabolites need to be measured in order to obtain an arterial input function. Our aim was the development of a PET tracer with an increased metabolic stability relative to [11C]HED. We selected 4-methylmetaraminol as a candidate molecule for radiolabelling with 11C (t1/2 20.4 min). Our radiosynthetic approach towards 4-[11C]methylmetaraminol involved a palladium-catalyzed cross-coupling reaction of a protected 4-trimethylstannyl derivative of metaraminol with [11C]methyl iodide followed by removal of the protective groups. 4-[11C]methylmetaraminol was obtained in a final decay-corrected radiochemical yield of 20–25% within a synthesis time of 60–80 min. The specific radioactivity at the end of the synthesis ranged from 18–37 to GBq/μmol. The unlabelled reference molecule, 4-methylmetaraminol, was prepared in a 5-step synthesis starting from metaraminol. A biological evaluation of 4-[11C]methylmetaraminol is in progress and the results will be reported elsewhere. Copyright © 2002 John Wiley & Sons, Ltd.
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肾上腺素能神经递质[11C]甲羟
麻黄碱([11C]HED)是目前评估心肌交感神经支配的首选 PET 示踪剂。该分子在芳香环的 4 位发生代谢。所产生的放射性标记代谢物需要进行测量,以获得动脉输入功能。我们的目标是开发一种相对于 [11C]HED 代谢稳定性更高的 PET 示踪剂。我们选择了 4-甲基
甲胺醇作为 11C 放射性标记的候选分子(t1/2 20.4 分钟)。我们对 4-[11C]甲基
甲胺醇的放射合成方法包括在
钯催化下,使受保护的
甲胺醇 4-
三甲基锡衍
生物与[11C]甲基
碘发生交叉偶联反应,然后去除保护基团。在 60-80 分钟的合成时间内,4-[11C]甲基
甲胺醇的最终衰变校正放射
化学收率为 20-25%。合成结束时的比放射性介于 18-37 GBq/μmol 之间。未标记的参照分子--4-甲基
对氨基苯酚是从
对氨基苯酚开始,通过 5 步合成法制备的。4-[11C]methylmetaraminol 的
生物学评估正在进行中,结果将在其他地方报告。Copyright © 2002 John Wiley & Sons, Ltd. All Rights Reserved.