Synthesis of 8-[¹⁸F]fluoroguanine derivatives: In vivo probes for imaging gene expression with positron emission tomography

A new method for the preparation of 8-[¹⁸F]fluoroguanine derivatives based on a direct radiofluorination reaction has been developed. The radiofluorination of ganciclovir (1a) with [¹⁸F]F₂ was carried out in absolute ethanol in the presence of tetraethylammonium hydroxide at room temperature to give 8-[¹⁸F]fluoroganciclovir (3a) in an approximately 1% radiochemical yield. Similarly, 8-[¹⁸F]fluoropenciclovir (3b), 8-[¹⁸F]fluoroacyclovir (3c), and 8-[¹⁸F]fluoroguanosine (3d) were synthesized from penciclovir (1b), acyclovir (1c), and guanosine (1d), respectively, using [¹⁸F]F₂. The structural analyses of the final products (3a, 3b, 3c, and 3d) were carried out after ¹⁸F decay by ¹H, ¹³C, and ¹⁹F nuclear magnetic resonance and high resolution mass spectroscopy. Copyright (C) 2000 Elsevier Science Inc.