Synthesis of γ-amino[4-11C]butyric acid (GABA)

A one-pot synthesis of no-carrier added γ-amino[4-11C]butyric acid (GABA) starting with hydrogen [11C]cyanide prepared from [11C]carbon dioxide, is presented. Hydrogen [11C]cyanide was trapped in tetrahydrofuran/potassium hydroxide in the presence of the amino polyether Krytofix 2.2.2. A Michael addition with ethyl acrylate followed by a selective reduction and hydrolysis of the resulting amino ester gave [4-11C]GABA. The radiochemical purity of GABA was higher than 99% and the decay corrected radiochemical yield was 60-65% based on the amount of H[11C]CN used. The total synthesis time including purification was around 40 min, counted from the start of the Michael addition reaction. (Author)