Radiosynthesis of [4‐O‐methyl‐11C]KF18446 as a potential ligand for the central adenosine a2Areceptor and comparison with [4‐O‐methyl‐11C]KW6002 in rats

The adenosine A2Aantagonist, KF18446 was labelled in the aromatic O‐methyl position using [11C]iodomethane. [4‐O‐methyl‐11C]KF18446 and [4‐O‐methyl‐11C]KW‐6002, an adenosine A2Aantagonist that we radiolabelled previously, were evaluated in rats. In brain, both [4‐O‐methyl‐11C]KW‐6002 and [4‐O‐methyl‐11C]KF18446 showed the highest uptake in striata and lowest in frontal cortex. For [4‐O‐methyl‐11C]KW‐6002 maximal striata: frontal cortex ratio was 1.7 from 60 to 120 min. For [4‐O‐methyl‐11C]KF18446 maximal striata: frontal cortex ratio was 2.4 from 30 to 90 min. The amount of unchanged [4‐O‐methyl‐11C]KW‐6002 was > 98 % in striata and cerebellum at 75 min post‐injection.