Novel probes for imaging amyloid-β: F-18 and C-11 labeling of 2-(4-aminostyryl)benzoxazole derivatives

2‐(4‐Methylaminostyryl)‐6‐(2‐[18F]fluoroethoxy)benzoxazole ([18F]BF‐168) was prepared and found to be a potential probe for imaging amyloid‐β. The precursor, a 6‐(2‐tosyloxyethoxy)benzoxazole derivative, was fluorinated with [18F]KF and Kryptofix 222 in acetonitrile, and the crude product purified by semi‐preparative HPLC to give [18F]BF‐168. The radiochemical purity was >95% and the maximum specific activity was 106 TBq/mmol at the end of synthesis. The synthesis time was 110 min from the end of bombardment. 2‐(4‐[N‐methyl‐11C]methylaminostyryl)‐5‐fluorobenzoxazole ([11C]BF‐145) was also prepared from 2‐(4‐aminostyryl)‐5‐fluorobenzoxazole, [11C]MeI and 5 N NaOH in DMSO, and purified by semi‐preparative HPLC. The radiochemical purity was >95% and the specific activity was 40–70 TBq/mmol at the end of synthesis. The synthesis time was 45 min from the end of bombardment. Copyright © 2004 John Wiley & Sons, Ltd.