title: Successful application of a neutral organic base, 1,8-bis(tetramethylguanidino)naphthalene (TMGN), for the radiosynthesis of [11C]raclopride.
abstract: [11C]Raclopride is one of the most popular PET tracers used in Parkinson's disease studies. We previously prepared [11C]raclopride with reasonable yields using NaOH as an inorganic base, but the reaction patterns fluctuated. In this study, we describe the successful application of a commercially available 'super basic' proton sponge, TMGN, as a base for the [11C]methylation step using [11C]CH3OTf. This novel TMGN method produced better radiochemical yields, as well as enhanced reproducibility and a reduction in side products. Under optimal conditions (1.2 equiv. of TMGN), the radiochemical yield was 14.4±0.2% (ndc, EOS, n=5) and the specific activity was 66.6±13.3 GBq/mmol (n=5).
authors.affiliation: Neuroscience Research Institute, Gachon University, 24, Namdong-daero 774 beon-gil, Namdong-gu, Incheon, Korea.
authors.forename: Jihye
authors.initials: J
authors.lastname: Lee
authors.affiliation: Gachon Advanced Institute for Health Science and Technology, Graduate School, Gachon University, 155, Gaetbeol-ro, Yeonsu-gu, Incheon, Korea.
authors.forename: Il-Koo
authors.initials: IK
authors.lastname: Cheong
authors.affiliation: Neuroscience Research Institute, Gachon University, 24, Namdong-daero 774 beon-gil, Namdong-gu, Incheon, Korea; Department of Neuroscience, College of Medicine, Gachon University, 191, Hambangmoe-ro, Yeonsu-gu, Incheon, Korea. Electronic address: rchemist@gachon.ac.kr.
authors.forename: Sang-Yoon
authors.initials: SY
authors.lastname: Lee
keywords: PET imaging; Parkinson's disease; Proton sponge; TMGN; [(11)C]Raclopride