- [a] Experiments were performed using approximately 18.5 GBq of [11C]CO2 as a starting activity from the cyclotron; [b] Radiochemical yield (%, dc) was estimated as the actual final activity of [11C]2 or [11C]3 in relation to trapped [11C]CO2 (AT) (decay corrected); [c] TBAF (0.05 mmol) [d] without TBAF [e] blank experiments in DMSO