Synthesis of carbon-11-labeled isonicotinamides as new potential PET agents for imaging of GSK-3 enzyme in Alzheimer’s disease

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• 作者：Mingzhang Gao ; Min Wang ; Qi-Huang Zheng ; ^{qzheng@iupui.edu}
• 关键词：Carbon-11-labeled isonicotinamides ; Glycogen synthase kinase-3 (GSK-3) ; Radiosynthesis ; Positron emission tomography (PET) ; Alzheimer&rsquo ; s disease (AD)
• 刊名：Bioorganic & Medicinal Chemistry Letters
• 出版年：2017
• 出版时间：15 February 2017
• 年：2017
• 卷：27
• 期：4
• 页码：740-743
• 全文大小：573 K
• 卷排序：27

文摘

The authentic standards 2-(cyclopropanecarboxamido)-N-(4-methoxypyridin-3-yl)isonicotinamide (4a) and 2-(cyclopropanecarboxamido)-N-(4-(4-methoxyphenyl)pyridin-3-yl)isonicotinamide (7a), and their corresponding precursors 2-(cyclopropanecarboxamido)-N-(4-hydroxypyridin-3-yl)isonicotinamide (4b) and 2-(cyclopropanecarboxamido)-N-(4-(4-hydroxyphenyl)pyridin-3-yl)isonicotinamide (7b) were synthesized from methyl 2-aminoisonicotinate and cyclopropanecarbonyl chloride with overall chemical yield 47% in three steps, 22% in four steps, 40% in three steps, and 17% in four steps, respectively. The target tracers 2-(cyclopropanecarboxamido)-N-(4-[11C]methoxypyridin-3-yl)isonicotinamide ([11C]4a) and 2-(cyclopropanecarboxamido)-N-(4-(4-[11C]methoxyphenyl)pyridin-3-yl)isonicotinamide ([11C]7a) were prepared from the precursors (4b and 7b) with [11C]CH3OTf through O-[11C]methylation and isolated by HPLC combined with SPE in 40–50% radiochemical yield, based on [11C]CO2 and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the specific activity (SA) at EOB was 370–1110 GBq/μmol with a total synthesis time of ∼40-min from EOB.