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

2‐(4‐Methylaminostyryl)‐6‐(2‐[ 18 F]fluoroethoxy)benzoxazole ([ 18 F]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 [ 18 F]KF and Kryptofix 222 in acetonitrile, and the crude product purified by semi‐preparative HPLC to give [ 18 F]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‐ 11 C]methylaminostyryl)‐5‐fluorobenzoxazole ([ 11 C]BF‐145) was also prepared from 2‐(4‐aminostyryl)‐5‐fluorobenzoxazole, [ 11 C]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.