Radiosynthesis of methyl and heptyl [11C]Isocyanates from [11C]phosgene, application to the synthesis of carbamates: [11C]physostygmine and [11C]heptylphysostigmine

[11C]methylisocyanate and [11C]heptylisocyanate were prepared within 10–11 min in amounts of 180–270 mCi (6.66–10 GBq) by action of [11C]COCl2 on N,N-bis(trimethylsilyl)methylamine and heptylamine respectively. The characterization of the isocyanates was done by their reaction on eseroline which gives [11C]physostigmine or [11C]heptylphysostigmine (two inhibitors of acetylcholinesterase). [11C]Isocyanates are obtained with a sp. act. of about 1.8 Ci/μmol (66.6 GBq/μmol), calculated for 10 min EOB which allows to synthesize 62–95 mCi (2.3–3.5 GBq) at 35 min EOB, of [11C]physostigmine or [11C]heptylphysostigmine, specific activity: 700–800 mCi/μmol (25.9–39.6 GBq/μmol). The interest in the use of amine or protected amine is discussed.