[11C]Cyclopropyl-FLB 457: A PET radioligand for low densities of dopamine D2 receptors
摘要:
(S)-5-Bromo- N-[(1-cyclopropylmethyl-2-pyrrolidinyl)methyl]-2,3-dimethoxybenzamide (4) has pico-molarin vitro binding affinity to D-2 receptor (K-i (D-2) = 0.003 nM) with lower affinity to D-3 receptor (K-i (D-3) = 0.22 nM). In this study, we describe radiosynthesis of [C-11]4 and evaluation of its binding characteristics in post-mortem human brain autoradiography and with PET in cynomolgus monkeys. The 11C labelled 4 was synthesized by using [C-11] methyltriflate in a methylation reaction with its phenolic precursor with good incorporation yield (64 +/- 11%, DCY) and high specific radioactivity > 370 GBq/mu mol (> 10 000 Ci/mmol). In post-mortem human brain autoradiography [C-11]4 exhibited high specific binding in brain regions enriched with dopamine D-2/D-3 receptors and low level of non-specific binding. In cynomolgus monkeys [C-11]4 exhibited high brain uptake reaching 4.4% ID at 7.5 min. The binding in the extrastriatal low density D-2-receptor regions; thalamus and frontal, parietal, temporal, and occipital cortex, was clearly visible. Pre-treatment with raclopride (1 mg/kg as tartrate) caused high reduction of binding in extrastriatal regions, including cerebellum. [C-11]4 is a promising radioligand for imaging D2 receptors in low density regions in brain. (c) 2008 Elsevier Ltd. All rights reserved.
Efficient stereoconservative synthesis of 1-substituted (S)- and
申请人:Astra Lakemedel Aktiebolag
公开号:US05300660A1
公开(公告)日:1994-04-05
Stereoconservative method for preparation of an (R)- or (S)-isomer of the compound of the formula I with at least 95% optical purity ##STR1## wherein R.sup.1 is a hydrogen atom, a saturated or unsaturated lower alkyl group, a cycloalkyl group, or a group (CH.sub.2).sub.m Ph wherein m is 0-3 and Ph is a substituted or unsubstituted phenyl group including 1) O,N-dialkylation, directly or stepwise of (R)- or (S)-proline 2) aminolysis 3) reduction to formation of the (R)- or (S)-isomer of the compound of the formula I, and new intermediates II and III in optical active form obtained by the reaction steps above and wherein R.sup.2 is defined as R.sup.1 above. ##STR2##