Synthesis of (R,S)-[4-11C]baclofen via Michael addition of nitromethane labeled with short-lived 11C.
The synthesis of (R,S)-[4-11C]baclofen, the first 11C-labeled GABAB agonist, was demonstrated via Michael addition of nitro[11C]methane as a key step. A tetrabutylammonium fluoride promoted Michael addition of nitro[11C]methane to methyl p-chlorocinnamate, followed by the nitro-group reduction in the presence of NiCl2 and NaBH4 in aqueous MeOH and alkaline hydrolysis yielded (R,S)-[4-11C]baclofen in 36.4+/-1.8% radiochemical conversion in three steps within 20 min.
Kato
Koichi
K
Department of Molecular Probes, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan. katok@nirs.go.jp
Zhang
Ming-Rong
MR
Suzuki
Kazutoshi
K
D001418:Baclofen / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D002250:Carbon Radioisotopes; D018755:GABA Agonists; D058786:GABA-B Receptor Agonists; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D009595:Nitroparaffins / Q000737:chemistry*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000138:chemical synthesis* / Q000737:chemistry; D018080:Receptors, GABA-B / Q000378:metabolism
D002250:Carbon Radioisotopes; D018755:GABA Agonists; D058786:GABA-B Receptor Agonists; D009595:Nitroparaffins; D019275:Radiopharmaceuticals; D018080:Receptors, GABA-B; D001418:Baclofen; D008697:Methane; C008640:nitromethane