Reductive N‐alkylation of secondary amines with [2‐11C]acetone

The development of a labeling method for secondary amines with [2‐11C]acetone is described since the R2N‐isopropyl moiety is present in many biologically active compounds. The influence of a variety of parameters (e.g. reagents, solvents, temperature, and time) on the reaction outcome is discussed. Under the optimal reaction conditions, [11C]1‐isopropyl‐4‐phenylpiperazine ([11C]iPPP) was synthesized from [2‐11C]acetone and 1‐phenylpiperazine in a decay‐corrected radiochemical yield of 72%. The overall synthesis time, from EOB to HPLC analysis of [11C]iPPP, was 20 min. Specific activity was 142–208 GBq/μmol at the end of synthesis.