Synthesis of N-(2-chloro-5-methylthiophenyl)-N′-(3-methyl-thiophenyl)-N′-[3H3]methylguanidine, {[3H3]CNS-5161}

The preparation of the title compound, [H-3(3)]CNS-5161, was accomplished in three steps starting with the production of [H-3(3)]iodomethane (CT3I). The intermediate N-[H-3(3)]methyl-3-(thiomethylphenyl)cyanamide was prepared in 77% yield by the addition of CT3I to 3-(thiomethylphenyl)cyanamide, previously treated with sodium hydride. Reaction of this tritiated intermediate with 2-chloro-5-thiomethylaniline hydrochloride formed the guanidine compound [H-3(3)]CNS-5161. Purification by HPLC gave the desired labeled product in an overall yield of 9% with > 96% radiochemical purity and a final specific activity of 66 Ci mmol(-1). Copyright (C) 2002 John Wiley Sons, Ltd.