- Synthesis of 3-substituted indazoles and benzoisoxazoles via Pd-catalyzed cyclization reactions: application to the synthesis of nigellicine
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Syntheses of 3-substituted indazoles and benzoisoxazoles were efficiently accomplished with the aid of Pd-catalyzed intramolecular carbon-nitrogen and carbon-oxygen bond formations. The catalyst system described herein allows the cyclization to proceed under very mild conditions and thus could be applied to a wide range of substrates with acid- or base-sensitive functional groups. A total synthesis for the indazole ring-containing natural product nigellicine is also described.
- Inamoto, Kiyofumi,Katsuno, Mika,Yoshino, Takashi,Arai, Yukari,Hiroya, Kou,Sakamoto, Takao
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p. 2695 - 2711
(2007/10/03)
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- Synthesis of 4H-benzo[e]-1,2-selanazin-4-one derivatives: a new heterocyclic ring system
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The synthesis of novel 1,2-benzoselenazin-4-ones which are six-membered homologues of ebselen, is described in order to evaluate their glutathione peroxidase-like activity.
- Messali, Mouslim,Christiaens, Léon E.,Alshahateet, Solhe F.,Kooli, Fethi
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p. 7448 - 7451
(2008/03/13)
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- Cyclic enolates of Ni and Pd: Equilibrium between C- and O-bound tautomers and reactivity studies
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2-Acylaryl complexes of Ni and Pd containing chelating diphosphines react with KtBuO to give metallacyclic enolate complexes. While coordination through the carbon atom is preferred in the case of Pd, the nickel O-enolate compounds are formed as the corresponding O-tautomers. Slow equilibration between O- and C-enolate tautomers is observed for the nickel complex with an unsubstituted enolate function (M-O-C=CH2). Theoretical DFT calculations suggest that the barrier for the tautomer exchange has its origin in the rigidity of the metallacycle. Whilst the C-enolate tautomer is unreactive towards aldehydes, the corresponding O-enolate adds to MeCHO and PhCHO, giving rise to products that retain the enolate functionality. The carbonylation of these products cleanly leads to the formation of enol lactones in a highly selective manner.
- Campora, Juan,Maya, Celia M.,Palma, Pilar,Carmona, Ernesto,Gutierrez, Enrique,Ruiz, Caridad,Graiff, Claudia,Tiripicchio, Antonio
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p. 6889 - 6904
(2007/10/03)
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- Diminished reactivity of ortho-substituted phenacyl bromides toward nucleophilic displacement
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A systematic increase of substitution rates by tert-butylamine on α-bromopropiophenones is observed with meta or para substituents with increasing electron-withdrawing ability (k x 103 L M-1 min-1 = 12.7 (p-CH3), 15.7 (o-F), 20.5 (H), 20.0 (p-Cl), 23.6 (m-Cl), 27.3 (p-CF3)). Within an ortho-substituted series, the reactivities decrease (k x 103 L M-1 min-1 = 7.64 (o-OCH3), 5.31 (o-CH3), 2.85 (o-Cl), 2.40 (o-CF3)). Ortho-substitution results occur from rotational barrier effects and an Aδσ + Bδσ + repulsion. The major bonding contribution between reaction and α-substituent centers (A-B) is only the σ bond. When π bonding is allowed between A and B (meta/para-substitution), delocalization and stabilization of the reacting center occurs.
- Kalendra, Diane M.,Sickles, Barry R.
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p. 1594 - 1596
(2007/10/03)
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- Synthesis and activity of 2-methyl-3-aminopropiophenones as centrally acting muscle relaxants
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Some novel 2-methyl-3-aminopropiophenones were synthesized and their centrally acting muscle relaxant activities were,evaluated for an inhibitory effect on the flexor reflex in rats. The structure-activity relationships are discussed. In this series 2-methyl-3-pyrrolidino-1-(4-trifluoromethylphenyl)-propan-1-one (28) showed significant centrally acting muscle relaxant activity. In addition, the activities of each enantiomer (28-(S) and (R)) were studied along with their acute toxicities. Compound 28-(R) was found to exhibit more potent activity and weaker acute toxicity than 28-(S). Accordingly, compound 28-(R) (NK433) is under development as a novel centrally acting muscle relaxant.
- Shiozawa,Narita,Izumi,Kurashige,Sakitama,Ishikawa
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- Therapeutically useful 1-phenyl-2-piperidinoalkanol derivatives
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Compounds of the formula: STR1 wherein R1 is hydrogen, halogen, trifluoromethyl, alkyl, hydroxyl, alkyoxy, benzyloxy, alkanoyloxy, or benzoyloxy, or when R2 is hydroxyl or methoxy in the 4-position and R3 is hydrogen, R1 may also represent hydroxymethyl carbamoyl or alkoxycarbonyl, R2 is hydrogen, halogen, alkyl, hydroxyl, or alkoxy, R3 is hydrogen or alkyl, R4 is alkyl (in which case the compounds are (±)-erythro) or when R3 represents hydrogen, R4 may also be hydrogen, and R5 is hydrogen, halogen, alkyl, alkoxy, or three methoxy groups in the 3-, 4- and 5-positions and pharmaceutically acceptable acid addition salts thereof, with the exclusion of compounds wherein: (a) one of R1 and R2 is in the 4-position and is hydroxyl, alkoxy or benzyloxy, the other is in the 3-position and is hydrogen, hydroxyl, alkoxy or benzyloxy, and R3 and R5 are hydrogen and wherein: (b) R1 is in the 4-position and is halogen, R4 is methyl and R2, R3 and R5 are hydrogen, are useful as medicaments.
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- Process for the manufacture of ketones
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Ketones are prepared by reacting carboxylic acid halides, in particular carboxylic acid chlorides, with aluminum-alkyl compounds, optionally in the presence of an aluminum trihalide, in methylene chloride as the solvent, at a temperature between about 20° and about 100° C., preferably between about 30° and about 60° C., more preferably of about 40° C. which is the reflux temperature of the methylene chloride. When operating at a temperature above approximately 40° C., pressure higher than atmospheric is applied. The reaction mixture is worked up in usual manner, suitably by decomposition with water followed by distillation.
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