Ruthenium‐katalysierte Reaktionen – eine Schatzkiste für atomökonomische Umwandlungen

Abstract

Der stetige Bedarf an neuen Chemikalien bei gleichzeitiger Forderung nach umweltfreundlichen Herstellungsmethoden stellt an Synthesechemiker große Anforderungen. Die Maximierung der Syntheseeffizienz durch die Umwandlung einfacher Bausteine in komplexe Zielmoleküle bleibt daher eine grundlegende Aufgabe. In diesem Zusammenhang ist die Verwendung von Ruthenium‐Komplexen als Katalysatoren für mehrere nichtmetathetische Umwandlungen ein vielversprechender Ansatz, denn diese Komplexe ermöglichen den schnellen Aufbau komplexer Moleküle mit hoher Selektivität und Atomökonomie. Zudem zeigen sie häufig ungewöhnliche Reaktivität, und durch das sorgfältige Studium der zugrundeliegenden Mechanismen können neue Reaktionen entwickelt und neue Reaktivitäten entdeckt werden.

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

“…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].…”

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

“…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.…”

“…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.…”

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

“…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).…”