A New Method for Radiosynthesis of 11C-Labeled Carbamate Groups and its Application for a Highly Efficient Synthesis of the Kappa-Opioid Receptor Tracer [11C]GR103545

Table 2: Radiochemical Yield^a of [¹¹C]GR103454^b,^c


T (°C)	Reaction Time (min)	RCY^a
25	5	64 ± 5
35	5	72 ± 6
40	2	84 ± 4
40	5	91 ± 5

^a Determined by analytical radio-HPLC

^b Results represent the mean ± std, n = 5.

^c To a solution of des-carbamate-GR103545 (3 mg, 8.4 µmol) in anhydrous DMF (500 µl) was added 3 molar equivalents of the TBA-reagent and 3 molar equivalents of Cs₂CO₃. CO₂ gas (20 ml/min) was bubbled through the suspension for 1 h at room temperature. Subsequently, the ¹¹C-alkylating agent was swept trapped in the reaction vial and allowed to react for the desired period of time.