1243694-61-2Relevant academic research and scientific papers
Targeting cyclic nucleotide phosphodiesterase 5 (PDE5) in brain: Toward the development of a PET radioligand labeled with fluorine-18
Wenzel, Barbara,Liu, Jianrong,Dukic-Stefanovic, Sladjana,Deuther-Conrad, Winnie,Teodoro, Rodrigo,Ludwig, Friedrich-Alexander,Chezal, Jean-Michel,Moreau, Emmanuel,Brust, Peter,Maisonial-Besset, Aurelie
supporting information, p. 346 - 362 (2019/02/14)
With the aim to develop a specific radioligand for imaging the cyclic nucleotide phosphodiesterase 5 (PDE5) in brain by positron emission tomography (PET), seven new fluorinated inhibitors (3–9) were synthesized on the basis of a quinoline core. The inhibitory activity for PDE5 together with a panel of other PDEs was determined in vitro and two derivatives were selected for IC50 value determination. The most promising compound 7 (IC50 = 5.92 nM for PDE5A), containing a 3-fluoroazetidine moiety, was further radiolabeled by aliphatic nucleophilic substitution of two different leaving groups (nosylate and tosylate) using [18F]fluoride. The use of the nosylate precursor and tetra-n-butyl ammonium [18F]fluoride ([18F]TBAF) in 3-methyl-3-pentanol combined with the addition of a small amount of water proved to be the best radiolabeling conditions achieving a RCY of 4.9 ± 1.5% in an automated procedure. Preliminary biological investigations in vitro and in vivo were performed to characterize this new PDE5 radioligand. Metabolism studies of [18F]7 in mice revealed a fast metabolic degradation with the formation of radiometabolites which have been detected in the brain.
Chelation-assisted, copper(II)-acetate-accelerated azide-alkyne cycloaddition
Kuang, Gui-Chao,Michaels, Heather A.,Simmons, J. Tyler,Clark, Ronald J.,Zhu, Lei
supporting information; experimental part, p. 6540 - 6548 (2010/12/19)
We described in a previous communication a variant of the popular Cu I-catalyzed azide-alkyne cycloaddition (AAC) process where 5 mol % of Cu(OAc)2 in the absence of any added reducing agent is sufficient to enable the reaction. 2-Picolylazide (1) and 2-azidomethylquinoline (2) were found to be by far the most reactive carbon azide substrates that convert to 1,2,3-triazoles in as short as a few minutes under the discovered conditions. We hypothesized that the abilities of 1 and 2 to chelate CuII contribute significantly to the observed high reaction rates. The current work examines the effect of auxiliary ligands near the azido group other than pyridyl for CuII on the efficiency of the Cu(OAc)2-accelerated AAC reaction. The carbon azides capable of binding to the catalytic copper center at the alkylated azido nitrogen in a chelatable fashion were indeed shown to be superior substrates under the reported conditions. The chelation between carbon azide 11 and CuII was demonstrated in an X-ray single-crystal structure. In a limited set of examples, the ligand tris(benzyltriazolylmethyl) amine (TBTA), developed by Fokin et al. for assisting the original Cu I-catalyzed AAC reactions, also dramatically enhances the Cu(OAc)2-accelerated AAC reactions involving nonchelating azides. This observation leads to the hypothesis of an additional effect of chelating azides on the efficiencies of Cu(OAc)2-accelerated AAC reactions, which is to facilitate the rapid reduction of CuII to highly catalytic CuI species. Mechanistic studies on the AAC reactions with particular emphasis on the role of carbon azide/copper interactions will be conducted based on the observations reported in this work. Finally, the immediate utility of the product 1,2,3-triazole molecules derived from chelating azides as multidentate metal coordination ligands is demonstrated. The resulting triazolyl-containing ligands are expected to bind with transition metal ions via the N(2) nitrogen of the 1,2,3-triazolyl group to form nonplanar coordination rings. The CuII complexes of bidentate T1 and tetradentate T6 and the ZnII complex of T6 were characterized by X-ray crystallography. The structure of [Cu(T1)2(H2O) 2](ClO4)2 reveals the interesting synergistic effect of hydrogen bonding, π-π stacking interactions, and metal coordination in forming a one-dimensional supramolecular construct in the solid state. The tetradentate coordination mode of T6 may be incorporated into designs of new molecule sensors and organometallic catalysts.
