Synthesis of [11C]cyanamide, a versatile synthon for the production of 11C-labelled radiopharmaceuticals

For the production of [11C]cyanamide, a simple and easy to automate method is described. After trapping [11C]CO2 on a BaO/Al2O3 column, the [11C]BaNCN under a continuous NH3 flow at 700°C. [11C]Cyanamide is then eluted from this column with an aqueous solution and purified by a cation exchange column. Including trapping of [11C]CO2, a run requires approx. 10 min to give a solution of [11C]cyanamide in water with a specific activity of >9 TBq/mmol in a radiochemical yield of 55–65% and a radiochemical purity of >97%. The versatility of [11C]cyanamide as a synthon is shown by its rapid conversion into [11C]urea (3 min) and by the total synthesis of [11C]benzylguanidine and [11C]4-methyloxazol-2-amine.