- Aromatic chlorination of ω-phenylalkylamines and ω- phenylalkylamides in carbon tetrachloride and α,α,α- trifluorotoluene
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The aromatic halogenation of simple alkylbenzenes with chlorine proceeds smoothly in acetic acid but is much less efficient in less polar solvents. By contrast chlorination of ω-phenylalkylamines, such as 3-phenylpropylamine, occurs readily in either acetic acid, carbon tetrachloride or α,α,α-trifluorotoluene, and in the latter solvents gives high proportions of ortho-chlorinated products. These effects are attributable to the involvement of N-chloroamines as reaction intermediates, with intramolecular delivery of the chlorine electrophile. ω-Phenylalkylamides, such as 3-phenylpropionamide, also easily undergo aromatic chlorination in carbon tetrachloride and α,α,α-trifluorotoluene. These reactions generally show a first-order dependence on the substrate concentration, but not on the amount of chlorine. With carbon tetrachloride, very similar reaction rates are observed with chlorine concentrations ranging from 0.1-1.5 M. In α,α,α-trifluorotoluene, the rates reach a plateau at a chlorine concentration of approximately 0.2 M. These features indicate that the reactions proceed via the formation of intermediates which evidence suggests may be the corresponding O-chloroimidates. Irrespective of the mechanistic details, the reactions are remarkably rapid, being faster than analogous reactions in acetic acid and three to four orders of magnitude more rapid than reactions of simple alkylbenzenes in carbon tetrachloride. Therefore, chlorination of the amines and amides may be accomplished without the need for highly polar solvents, added catalysts or large excesses of chlorine, which are often employed for electrophilic aromatic substitutions. Although the use of carbon tetrachloride is becoming increasingly impractical due to environmental concerns, the trifluorotoluene is a suitable alternative. The Royal Society of Chemistry 2006.
- O'Connell, Jenny L.,Simpson, Jamie S.,Dumanski, Paul G.,Simpson, Gregory W.,Easton, Christopher J.
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p. 2716 - 2723
(2008/02/08)
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- Pyrimidine derivatives and processes for the preparation thereof
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The present invention relates to novel pyrimidine derivatives and pharmaceutically acceptable non-toxic salts thereof which possess an excellent inhibitory activity against gastric acid secretion, a pharmaceutical composition containing the same as an active ingredient, and a process for the preparation thereof.
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- The influence of substitution at aromatic part of 1,2,3,4-tetrahydroisoquinoline on in vitro and in vivo 5-HT1A/5-HT2A receptor activities of its 1-adamantoyloaminoalkyl derivatives
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Further structure-activity relationship (SAR) studies with the 1,2,3,4-tetrahydroisoquinoline (THIQ) class of 5-HT1A ligands led to the synthesis of new 1-adamantoyloaminoalkyl derivatives. The impact of substituent variations in the aromatic part of THIQ moiety on 5-HT1A and 5-HT2A receptor affinities, as well as in vivo functional properties of the investigated compounds were discussed. It was found that modification reduced the binding affinity for 5-HT1A receptors (in comparison with unsubstituted THIQ derivatives); however, the majority of new compounds still remained potent 5-HT1A ligands (Ki = 4.9-46 nM) and most of them showed features of partial agonists of postsynaptic 5-HT1A receptors. At the same time, their 5-HT2A receptor affinity was slightly increased (Ki = 40-1475 nM), which resulted in a loss of 5-HT2A/5-HT1A selectivity. 5-Br,8-OCH3 derivative - the most potent, mixed 5-HT1A/5-HT2A ligand - produced activation of presynaptic 5-HT1A receptors and showed properties of a 5-HT2A receptor antagonist. Copyright
- Bojarski, Andrzej J,Mokrosz, Maria J,Minol, Sijka Charakchieva,Koziol, Aneta,Wesolowska, Anna,Tatarczynska, Ewa,Klodzinska, Aleksandra,Chojnacka-Wojcik, Ewa
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- Design and Synthesis of New Naphthalenic Derivatives as Ligands for 2-Iodomelatonin Binding Sites
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New melatonin-like agents were designed from the frameworks of 2,5-dimethoxyphenethylamine, an important structural moiety for the 5-HT receptor, and (2-methoxynaphthyl)ethylamine.The compounds were synthesized by classical methods and evaluated in binding assays with chicken brain membranes using 2-(125I>iodomelatonin as the radioligand.Preliminary studies on the series of N-acyl-disubstituted phenethylamines showed the favorable role of the methoxy group in the ortho position of the side chain on the affinity for the receptor ( Ki = 8 +/- 0.2 nM ) for N-propionamide (3o).This effect was confirmed in a series of the naphthalene derivatives, a bioisosteric moiety of the indole ring, and several potent ligands for melatonin binding sites were prepared such as N-propionamide (4b) ( Ki = 0.67 +/- 0.05 nM ) and N-cyclopropylformamide (Ki = 0.05 +/- 0.004 nM ( (4k).Structure-activity relationships are discussed with regard to melatonin and bioisosteric naphthalenic compound 2.The Ki value for 4b was affected to a similar extent to that of melatonin by GTP-γ-S or Mn2+ in competition experiments, suggesting an agonist profile for this compound.
- Langlois, Michel,Bremont, Beatrice,Shen, Shuren,Poncet, Annie,Andrieux, Jean,et al.
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p. 2050 - 2060
(2007/10/02)
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