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

The development of a labeling method for secondary amines with [2-C-11]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, [C-11]1-isopropyl-4-phenylpiperazine ([C-11]iPPP) was synthesized from [2-C-11]acetone and 1-phenylpiperazine in a decay-corrected radiochemical yield of 72%. The overall synthesis time, from EOB to HPLC analysis of [C-11]iPPP, was 20 min. Specific activity was 142-208 GBq/mumol at the end of synthesis. Copyright (C) 2003 John Wiley Sons, Ltd.