Ruthenium-katalysierte Reaktionen - eine Schatzkiste für atomökonomische Umwandlungen

Trost, Barry M.; Frederiksen, Mathias; Rudd, Michael T.

doi:10.1002/ange.200500136

Cited by 137 publications

(35 citation statements)

References 303 publications

(212 reference statements)

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“…We describe herein reproducible syntheses, characterization and reactivity of ruthenium cyclopentadienyl complexes based on diphenyl-2-pyridylphosphine (PPh 2 Py). Also, we present herein molecular structures of the complexes 1, 1a, 1c, 1e and 1f and results of our studies on catalytic activity of 1 in the reduction of aldehyde to alcohol under aqueous and aerobic conditions [36,37].…”

Section: Introductionmentioning

confidence: 99%

Structures, preparation and catalytic activity of ruthenium cyclopentadienyl complexes based on pyridyl-phosphine ligand

Kumar

Singh

Sharma

et al. 2009

Journal of Organometallic Chemistry

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“…Although we cannot rule out this mechanism at this time, the oxidative coupling mechanism cannot readily explain both the deuterium labeling pattern and the stereoselective formation of the tetrasubstituted Zolefin products. [18] In summary, a novel catalytic method for the synthesis of tetrasubstituted olefins has been developed from the conjugate addition of unactivated olefins to a,b-unsaturated carbonyl compounds. The preliminary kinetic and spectroscopic studies provide supporting evidence for a mechanistic pathway that involves a rate-limiting olefin insertion to the a,b-unsaturated carbonyl substrate and rapid olefin isomerization steps.…”

Section: Methodsmentioning

confidence: 99%

“…In general, cinnamic esters with para electron-donating groups were found to promote the coupling reaction, but neither cyclic enones nor pyrrolinones gave the coupling products under similar reaction conditions. The coupling reactions of N-methyl cinnamide with 1-alkenes furnished the tetrasubstituted Z-olefin products 2 r-2 u selectively (Table 2, entries [18][19][20][21][22]. The fact that both 1-and 2-butenes gave the same product, 2 r, suggests that the rate of olefin isomerization is much faster than the rate of the coupling reaction [a] Reaction conditions: ethyl cinnamate (0.58 mmol), propene (2.9 mmol), catalyst (3 mol %), CH 2 Cl 2 (1-2 mL), 70 8C, 2-5 h.…”

mentioning

confidence: 99%

Tetrasubstituted Olefins through the Stereoselective Catalytic Intermolecular Conjugate Addition of Simple Alkenes to α,β-Unsaturated Carbonyl Compounds

Kwon¹,

Lee²,

Yi³

2011

Angew. Chem.

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“…Inspired by the wealth of ruthenium-based double-bondmigration catalysis in the literature, [18,19] including for the synthesis of ketene acetals, [20,21] we postulated that a1 ,3-dihydride shift of av inyl acetal with catalysts such as [RuHCOCl(PPh 3 ) 3 ]( 2) [20] and [RuHCl(PPh 3 ) 3 ] [18] (3)w ould enable in situ olefin isomerization catalysts in the presence of alcohols without the need to isolate the highly sensitive ketene acetal intermediate.Initially,model reactions focused on the in situ isomerization of the commercially available 5,5-dimethyl-2-vinyl-1,3-dioxane,t hus avoiding isolation of the highly reactive DETSOU monomer (Scheme 1). With excess 1,6-hexanediol it was found that, while 2 catalyzed the formation of the diorthoester to 99.7 %c onversion at 45 8 8C in 6.5 h, using an analogous catalyst loading of 3 only gave similar conversion at the same rate when carried out at 85 8 8C (Supporting Information).…”

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confidence: 99%

Unlocking the Potential of Poly(Ortho Ester)s: A General Catalytic Approach to the Synthesis of Surface-Erodible Materials

et al. 2017

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Poly(ortho ester)s (POEs) are well-known for their surface-eroding properties and hence present unique opportunities for controlled-release and tissue-engineering applications.T heir development and wide-spread investigation has, however,b een severely limited by challenging synthetic requirements that incorporate unstable intermediates and are therefore highly irreproducible.H erein, the first catalytic method for the synthesis of POEs using air-a nd moisturestable vinyl acetal precursors is presented. The synthesis of arange of POE structures is demonstrated, including those that are extremely difficult to achieve by other synthetic methods. Furthermore,a pplication of this chemistry permits efficient installation of functional groups through ortho ester linkages on an aliphatic polycarbonate.The use of biodegradable polymers for controlled drug release and tissue engineering represents one of the most important advances in biomedicine. [1][2][3] An ideal material would display as urface erosion profile in which hydrolysis occurs faster than water ingress into the materials and results in sequential erosion of the surface layers. [4,5] Such profiles enable idealized zero-order release profiles and predictable materials properties throughout degradation.[6] Despite these benchmark requirements,t he paucity of easily accessible surface eroding materials have led to extensive study of bulk eroding materials,s uch as poly(lactic acid) and poly(ecaprolactone), [7,8] in which water diffusion into the material occurs at acomparable or faster rate to hydrolysis.This results in anon-linear mass loss over time,amplified by autocatalysis from trapped degradation products,w hich in turn leads to non-linear release by encapsulants,s ignificant burst effects, and uncontrolled loss of mechanical stability.Despite the clear potential advantages of surface erodible polymers,examples are limited to only afew families,such as poly(anhydride)s [9,10] and poly(ortho ester)s (POEs). [11,12] Them ilder degradation products present POEs as ap otentially more attractive choice for in vivo applications and, indeed, POE types III and IV (Figure 1) have shown significant promise in ocular [11][12][13][14] as well as gene delivery. [11,12] However,their synthesis typically involves either step-growth polymerization of the highly air-a nd moisture-sensitive diketene acetal (3,9-bis(ethylidene-2,4,8,10-tetraoxaspiro-[5,5]undecane (DETSOU;S cheme 1) with ad iol, [15] or transesterification between at riorthoester and triol.[16] Both procedures present significant synthetic challenges when it comes to producing repeatable polymer characteristics,which likely results because the highly reactive ketene acetal monomers compromises the high levels of purity required for successful step-growth polymerization. More recently, some success was achieved by preparing ortho-ester-containing monomers by multistep syntheses to create poly(ortho ester amide)s and poly(ortho ester urethane)s.[17] Despite these advances,f urther development of gene...

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“…Diese PPh 3 -Abstraktion wurde auch für die Ruthenium-katalysierte Bildung von a,b-ungesättigten Ketonen festgestellt. [18] Eine Rçntgenstrukturanalyse von 2 bestätigt die Koordination der basalen As 3 -Einheit des h 1 -As 4 -Liganden an ein [CpRu(PPh 3 )]-Fragment und die Spaltung einer basalen AsAs-Bindung (Abbildung 4). (E = P, As) mit ihren relativen Energien (PCM-korrigierte Werte in Klammern) (PCM = polarisierbares Kontinuumsmodell) in kJ mol À1 .…”

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Ein end-on-koordiniertes As₄-Tetraeder

2013

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Professor Werner Uhl zum 60. Geburtstag gewidmet Vor fast 150 Jahren entdeckte Bettendorff das gelbe Arsen als ein Elementallotrop. Er konnte es aber nicht in reiner Form isolieren, da es extrem instabil ist und sich schnell in eine amorphe Form zersetzt.[1] Nach 35 Jahren intensiver Diskussion über seine Existenz oder Nichtexistenz waren Erdmann und Unruh die ersten, die über die Synthese von gelbem Arsen in grçßeren Mengen und seine physikalischen Eigenschaften berichteten.[2] Jedoch bedurfte es weiterer 75 Jahre, bis die Gruppen von Sacconi und Scherer dieses schwer fassbare Arsenallotrop [3] sowie P 4 für die Synthese von Polyelement-Ligandkomplexen nutzten (E n -Ligandkomplexe; E = P, As) und die Analogie zwischen den beiden Homologen der 15. Gruppe demonstrierten. Seitdem wurde besonders die Aktivierung von weißem Phosphor durch Über-gangsmetalle [4] und Hauptgruppenelemente [5] zu einem aktiven Arbeitsgebiet der anorganischen Chemie. Die Reaktivität von As 4 ist dagegen weitaus weniger untersucht, [3,6] was an seiner Instabilität, der schlechten Lçslichkeit, der zeitaufwändigen Synthese [3] und der schnellen Zersetzung zu grauem Arsen liegt, speziell wenn es Licht ausgesetzt wird.Die Koordination des E 4 -Tetraeders (E = P, As) an Übergangsmetallkomplexe ist von besonderem Interesse, da sie den Eingangsschritt seiner Aktivierung repräsentiert. In den späten 1970er Jahren berichteten Sacconi et al. über die Synthese von [(np 3 )Ni(h 1 -P 4 )] (I) als erstem Komplex, der ein intaktes, end-on-koordiniertes P 4 -Tetraeder als Liganden trägt (Abbildung 1).[ . Dies sind ersten Komplexe, in denen intakte As 4 -Tetraeder side-on an Lewis-saure Kationen der 11. Gruppe koordiniert sind. [12] Interessanterweise sind für diesen Verbindungstyp die Arsenderivate thermodynamisch stabiler als die analogen P 4 -Komplexe. Jedoch ist im Hinblick auf eine geplante Aktivierung von As 4 (vergleiche die Komplexe IV) die herausfordernde Ecken-Koordination von gelbem Arsen über seine freien Elektronenpaare von speziellem Interesse. Wir berichten hier über die Synthese von [Cp*Ru(dppe)(h 1 -As 4 )]-[pftb] mit einem beispiellosen intakten end-on-koordinierten As 4 -Liganden. Weiterhin zeigen wir, dass die Addition eines zweiten kationischen Ruthenium-Komplexfragmentes nicht zur erwarteten zweiten End-on-Koordination führt, sondern zu einer Insertion in eine As-As-Bindung.

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Ruthenium-katalysierte Reaktionen - eine Schatzkiste für atomökonomische Umwandlungen

Cited by 137 publications

References 303 publications

Structures, preparation and catalytic activity of ruthenium cyclopentadienyl complexes based on pyridyl-phosphine ligand

Tetrasubstituted Olefins through the Stereoselective Catalytic Intermolecular Conjugate Addition of Simple Alkenes to α,β-Unsaturated Carbonyl Compounds

Unlocking the Potential of Poly(Ortho Ester)s: A General Catalytic Approach to the Synthesis of Surface-Erodible Materials

Ein end-on-koordiniertes As₄-Tetraeder

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Ruthenium-katalysierte Reaktionen - eine Schatzkiste für atomökonomische Umwandlungen

Cited by 137 publications

References 303 publications

Structures, preparation and catalytic activity of ruthenium cyclopentadienyl complexes based on pyridyl-phosphine ligand

Tetrasubstituted Olefins through the Stereoselective Catalytic Intermolecular Conjugate Addition of Simple Alkenes to α,β-Unsaturated Carbonyl Compounds

Unlocking the Potential of Poly(Ortho Ester)s: A General Catalytic Approach to the Synthesis of Surface-Erodible Materials

Ein end-on-koordiniertes As4-Tetraeder

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Ein end-on-koordiniertes As₄-Tetraeder