- Phase transfer Wittig reaction with 1,3-dioxolan-2-yl-methyltriphenyl phosphonium salts: An efficient method for vinylogation of aromatic aldehydes
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Aldehydes were efficiently transformed into allylic dioxolanes by a Wittig-type reaction, using 1,3-dioxolan-2-yl-methyltriphenylphosphonium bromide under phase transfer conditions. The substituent kinetic effects were studied, and related to Hammett values and electrochemical potentials.
- Daubresse, Nicolas,Francesch, Charlette,Rolando, Christian
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- Synthesis, pharmacological activity and structure affinity relationships of spirocyclic σ1 receptor ligands with a (2-fluoroethyl) residue in 3-position
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In order to develop a fluorinated radiotracer for imaging of σ1 receptors in the central nervous system a series of (2-fluoroethyl) substituted spirocyclic piperidines 3 has been prepared. In the key step of the synthesis 2-bromocinnamaldehyde
- Maestrup, Eva Gro?e,Wiese, Christian,Schepmann, Dirk,Brust, Peter,Wünsch, Bernhard
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experimental part
p. 393 - 405
(2011/02/27)
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- Synthesis and SAR studies of 3-substituted 1′-benzylspiro[[2]benzoxepine1,4′-piperidines]
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The preparation of the hitherto unknown spiro[[2]benzoxepine-1,4′-piperidine] ring system is described. The synthesis consists of a Wittig reaction of 2-bromobenzaldehyde (4) and (1,3-dioxolan-2-ylmethyl)triphenylphosphonium bromide (5) to yield an α,β-unsaturated acetal. The double bond of 6 was subsequently hydrogenated. The resulting brominated acetal 7 was treated with n-butyllithium and then with 1-benzylpiperidin-4-one (9) to yield the hydroxy acetal 10. Acid-catalyzed cyclization of 10 with p-toluenesulfonic acid or aqueous HCl resulted in the formation of the 1′-benzylspiro[[2]benzoxepine-1,4′-piperidines] 11 and 12, respectively. The substituents in the 3-position of the spiro compounds 11 and 12 were further modified by reaction with trimethylsilyl cyanide or (cyanomethylene)triphenylphosphorane in order to introduce residues with one or two carbon atoms, respectively. The synthesized compounds were evaluated for σ1- and σ2-receptor affinity in vitro. The most potent σ1-ligand was the methoxy derivative 11 (Ki = 2.56 nM), whereas the cyanomethyl derivative 20 turned out to be the most σ1-selective compound (σ1/σ2 selectivity 768). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Maier, Christoph A.,Wuensch, Bernhard
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p. 714 - 720
(2007/10/03)
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