Asymmetric activation of tropos catalysts in the stereoselective catalytic conjugate additions of R2Zn to α,β-enones: an efficient synthesis of (−)-muscone

Scafato, Patrizia; Cunsolo, Giovanni; Labano, Stefania; Rosini, Carlo

doi:10.1016/j.tet.2004.07.034

Cited by 40 publications

(23 citation statements)

References 48 publications

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“…[36,46,[66][67][68][69][70][71][72][73][74][75] Die komplementären und effizienten Synthesewege zu Phosphoramiditen veranschaulichen das modulare Gerüst dieser Liganden, ein Merkmal, das in einer einfachen und automatisierten Herstellung großer Ligandbibliotheken Anwendung gefunden hat (Abbildungen 2 und 3). [76][77][78][79][80][81][82][83][84] Außerdem sind die Ausgangsverbindungen billig und enantiomerenrein erhältlich, [85] was die Phosphoramidite zu leicht zugänglichen und kostengünstigen chiralen Liganden macht. In Bezug auf ihre Anwendbarkeit muss betont werden, dass viele Liganden dieser Verbindungsklasse an der Luft stabil sind und keine langwierigen Verfahren oder strikt inerte Handhabung erfordern, wie es bei einigen Phosphanliganden der Fall ist.…”

Section: Phosphoramidite: Struktur Synthese Und Eigenschaftenunclassified

“…Synthese von BINOL-Phosphoramiditen. [76][77][78][79][80][81][82][83][84] Gemische aus chiralen und achiralen Liganden können bekanntlich mit Übergangsmetallen Heterokomplexe bilden und so günstige oder nachteilige Wirkungen auf die asymmetrische Katalyse haben. [89][90][91][92] Ausgehend von Untersuchungen an Gemischen verschiedener chiraler einzähniger Liganden wurde aber ein neues Prinzip in die asymmetrische Katalyse eingeführt.…”

Section: Phosphoramidite: Struktur Synthese Und Eigenschaftenunclassified

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Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

2010

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Die asymmetrische Katalyse mit Übergangsmetallkomplexen ist die Grundlage unzähliger stereoselektiver Umwandlungen und hat damit das Bild der modernen Synthesechemie gewandelt. Der Schlüssel zum Erfolg war die Entwicklung chiraler Liganden zur Kontrolle der Regio‐, Diastereo‐ und Enantioselektivität. Dabei haben sich Phosphoramidite als eine äußerst vielseitige und leicht zugängliche Klasse von chiralen Liganden erwiesen. Ihre modulare Struktur ermöglicht die Herstellung von Ligandenbibliotheken und erleichtert die Feinabstimmung für eine bestimmte katalytische Reaktion. Phosphoramidite bewirken oft außerordentlich hohe Stereoselektivitäten, und ihre einzähnige Natur ist in der kombinatorischen Katalyse, die gemischte Liganden verwendet, unverzichtbar. In diesem Aufsatz werden neue Entwicklungen in der asymmetrischen Katalyse mit Phosphoramiditen diskutiert, wobei der Schwerpunkt auf der Bildung von Kohlenstoff‐ Kohlenstoff‐ und Kohlenstoff‐Heteroatom‐Bindungen liegt.

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Section: Phosphoramidite: Struktur Synthese Und Eigenschaftenunclassified

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

2010

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“…Experimental data corresponds with the literature [41]. General procedure for the final compounds 10 mmol of the compounds core structure and 10 mmol sodium hydrid were dissolved in 25 mL DMSO and stirred for 1 h at RT under argon atmosphere.…”

Section: 7-dihydro-6h-dibenz[ce]azepin Rmentioning

confidence: 99%

Synthesis and Biochemical Characterization of New Phenothiazines and Related Drugs as MDR Reversal Agents

Schmidtkunz¹,

Teitge

Castillo

et al. 2008

Archiv der Pharmazie

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Chemotherapy is one of the most important methods in the treatment of cancer. However, development of drug resistance during chemotherapy is the leading cause of treatment failure and decreased survival in cancer patients. Multidrug resistance (MDR) is one of the extensively studied forms of drug resistance for more than 30 years. The members of ATP-binding cassette protein family are responsible for multidrug resistance with P-glycoprotein as most representative transporter. To overcome multidrug resistance, pharmacological modulation of the transporters by efflux pump inhibitors seem to be the first choice, but preclinical studies did not lead to clinical applications. Therefore, a systematical research for pharmacophor structures is a promising strategy to increase the efficacy of those drugs still influencing multidrug resistance. In this study a range of phenothiazine derivatives was synthesizied with systematical variation of three molecule domains. The biochemical determination of multidrug resistance reversal activity was achieved with the crystalviolet assay on LLC-PK1/MDR1 cells. The results will be discussed considering of hypotheses in the literature directed to new structure-acitivity relationships to overcome drug resistance in the future.

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“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) pseudo-C s symmetry, and the latter was later used as a component of phosphoramidite ligands. [10] However, other bridged o,oЈ-linked biphenyls have been the subject of extensive conformational studies. A three-atom bridged biphenyl, B, with X = C(CO 2 Et) 2 was early resolved and found to be configurationally stable in the crystalline state, but found to lose half of its activity within 80 min in solution.…”

Section: Introductionmentioning

confidence: 99%

“…It was found to be somewhat dependent on the structure of the alcohol part of the ligands, but did not exceed 1.43:1, as observed for 1d ( Table 1). The low diastereomeric ratios contrast those of (5R,7R)-5,7-dimethyl-6,7-dihydro-5H-dibenz [c,e]azepine [17] and a phosphoramidite composed of 6,6Ј-binaphthol and 6,7-dihydro-5H-dibenz [c,e]azepine, [10] which exist as single diastereomers, but which have the stereogenic centers situated closer to the biphenyl part of the molecules. In order to allow assignment of the absolute configuration of the two diastereomers of menthol containing ligands 1b, the rigid analogues (R a )--3 and (R a )--3 were prepared from 8-chloro-8,9-dihydro-7H-dinaphtho[2,1-c;1Ј,2Ј-e]phosphepine (4) in 36 and 39 % yields, respectively, by a route analogous to that used for compounds 1b-e (Scheme 3).…”

Section: Introductionmentioning

confidence: 99%

Stereochemical Control of Chirally Flexible Phosphepines

Žalubovskis¹,

Fjellander²,

Szabó³

et al. 2006

Eur J Org Chem

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The barriers to interconversion of the two enantiomeric atropisomers of 6‐methoxy‐6,7‐dihydro‐5H‐dibenzo[c,e]phosphepine and that of the diastereomeric forms of 6‐(–)‐menthoxy‐6,7‐dihydro‐3H‐dibenzo[c,e]phosphepine were determined by NMR spectroscopical methods to be 19.3 and 18.5 kcal mol–1, respectively, at 298 K. The ratio of the atropisomers was shown to depend on the group bound to phosphorus. Only complexes with two homochiral ligands bound to the each metal center were obtained upon reaction with [Rh(COD)2]+ BF4–. The Rh complexes catalyzed the hydrogenation of α‐acetamidocinnamate. The major isomer of6‐(–)‐menthoxy‐6,7‐dihydro‐5H‐dibenzo[c,e]phosphepinewas found to exhibit higher activity but to afford a product with lower ee than its diastereomer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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Asymmetric activation of tropos catalysts in the stereoselective catalytic conjugate additions of R2Zn to α,β-enones: an efficient synthesis of (−)-muscone

Cited by 40 publications

References 48 publications

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

Synthesis and Biochemical Characterization of New Phenothiazines and Related Drugs as MDR Reversal Agents

Stereochemical Control of Chirally Flexible Phosphepines

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