- Asymmetric intramolecular hydroamination of alkenes in mild and wet conditions - Structure and reactivity of cationic binuclear gold(I) catalysts
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A selected diphosphine binuclear gold(I) chloride complex was combined with a silver salt to catalyze efficiently, for the first time, the asymmetric intramolecular hydroamination of alkenes with high conversions and enantioselectivities, in mild conditions and in presence of water. Both enantiomers of the products could be obtained by controlling the molecular ion-pairs through the solvent polarity. The gold(I) cationic active species was characterized unambiguously at the solid state by X-ray analysis and in solution by DOSY 1H NMR experiments. No contribution of silver chloride was observed on the bonding mode of the catalyst.
- Abadie, Marc-Antoine,Trivelli, Xavier,Medina, Florian,Capet, Frederic,Roussel, Pascal,Agbossou-Niedercorn, Francine,Michon, Christophe
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- Acylative kinetic resolution of racemic methyl-substituted cyclic alkylamines with 2,5-dioxopyrrolidin-1-yl (: R)-2-phenoxypropanoate
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The diastereoselective acylation of a number of racemic methyl-substituted cyclic alkylamines with active esters of 2-phenoxypropanoic acid was studied in detail. The ester of (R)-2-phenoxypropanoic acid and N-hydroxysuccinimide was found to be the most selective agent. The highest stereoselectivity was observed in the kinetic resolution of racemic 2-methylpiperidine in toluene at -40 °C (selectivity factor s = 73) with the predominant formation of (R,R)-amide (93.7% de). To explain the observed stereoselectivity, DFT modelling of the transition states in the reactions of the title acylating agent with 2-methylpiperidine and 2-methylpyrrolidine was performed. The calculated values were in good agreement with experimental data. It has been demonstrated that the acylation proceeds via a concerted mechanism, in which the addition of an amine occurs simultaneously with the elimination of the hydroxysuccinimide fragment. The high stereoselectivity of the (R,R)-amide formation is largely ensured by the lower steric hindrances in the transition states as compared to the formation of (R,S)-amide.
- Bartashevich, Ekaterina V.,Chulakov, Evgeny N.,Ezhikova, Marina A.,Gruzdev, Dmitry A.,Kodess, Mikhail I.,Korolyova, Marina A.,Krasnov, Victor P.,Levit, Galina L.,Tumashov, Andrey A.,Vakarov, Sergey A.
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supporting information
p. 862 - 869
(2022/02/03)
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- Catalytic Reduction of Alkyl and Aryl Bromides Using Propan-2-ol
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Milstein's complex, (PNN)RuHCl(CO), catalyzes the efficient reduction of aryl and alkyl halides under relatively mild conditions by using propan-2-ol and a base. Sterically hindered tertiary and neopentyl substrates are reduced efficiently, as well as more functionalized aryl and alkyl bromides. The reduction process is proposed to occur by radical abstraction/hydrodehalogenation steps at ruthenium. Our research represents a safer and more sustainable alternative to typical silane, lithium aluminium hydride, and tin-based conditions for these reductions.
- Haibach, Michael C.,Stoltz, Brian M.,Grubbs, Robert H.
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supporting information
p. 15123 - 15126
(2017/11/20)
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- A new class of potent non-imidazole H3 antagonists: 2-Aminoethylbenzofurans
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2-Aminoethylbenzofurans constitute a new class of H3 antagonists that are more rotationally constrained than most previously reported H3 antagonists. They retain high potency at human and rat receptors, with efficient CNS penetration observed in 35. The SAR of the basic amine moiety was compared in three different series of analogues. The greatest potency was found in analogues bearing a 2-methylpyrrolidine, a 2,5-dimethylpyrrolidine, or a 2,6-dimethylpiperidine.
- Cowart, Marlon,Pratt, John K.,Stewart, Andrew O.,Bennani, Youssef L.,Esbenshade, Timothy A.,Hancock, Arthur A.
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p. 689 - 693
(2007/10/03)
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