Synthesis and initialin vitro characterization of 6-[18F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine, a high-affinity radioligand for central nicotinic acetylcholine receptors
作者:Andrei O. Koren、Andrew G. Horti、Alexey G. Mukhin、Daniela G�ndisch、Robert F. Dannals、Edythe D. London
DOI:10.1002/(sici)1099-1344(200004)43:5<413::aid-jlcr326>3.0.co;2-1
日期:2000.4
6-[F-18]Fluora-3-(2(S)-azetidinylmethoxy)pyridine ([F-18](1) under bar), a novel analogue of the high-affinity nicotinic acetylcholine receptor ligand, A-85380, was prepared by a two-step procedure from an appropriate nitro precursor. In the first step, a Kryptofix 222-assisted F-18 nucleophilic heteroaromatic substitution in 6-nitro-3-((1-tert-butoxycarbonyl-2(S)-azetidinyl)methoxy)pyridine provided a radio-fluorinated Boc-protected intermediate. Subsequent acidic deprotection of the intermediate gave [F-18](1) under bar with an overall radiochemical yield of 8 to 12% (non-decay-corrected). The typical synthesis time was ca. 110 min. Specific radioactivity of the final product ranged from 1000 to 4500 mCi/mu mol, as calculated at the end-of-synthesis. III vitro studies demonstrated that the novel radioligand bound to a single population of sites in rat brain membranes, presumably, to the alpha 4 beta 2 subtype of nicotinic acetylcholine receptor. This binding was characterized by a K-d value of 28 pM, consistent with the K-i value of 25 pM, derived previously for unlabeled (1) under bar in competition assays with (+/-)-[H-3]epibatidine.