Eine Reihe definierter Metathesekatalysatoren – Synthese von und Reaktionen mit [RuCl₂ (  CHR′)(PR₃)₂]

Abstract

Wesentlich bessere Initiatoren und demzufolge erheblich reaktiver als die Komplexe des Typs A sind die Metathesekatalysatoren B, die durch Umsetzung von [RuCl2 (PPh3)3] mit den entsprechenden Diazoalkanen und nachfolgenden Phosphanaustausch erhältlich sind. Während die PPh3‐Derivate ausgezeichnete Katalysatoren für die lebende ROMP von Norbornen sind, erweist sich der Komplex mit R  Cy, R′  Ph zusätzlich als sehr wirksamer Katalysator für die Metathese acyclischer Alkene.

The First Grubbs-Type Metathesis Catalyst withcis Stereochemistry: Synthesis of [(η2-dtbpm)Cl2Ru=CH−CH=CMe2] from a Novel, Coordinatively Unsaturated Dinuclear Ruthenium Dihydride

“…As shown by spectroscopy and X-ray diffraction, all known and catalytically active Grubbs-type Ru carbene complexes [(PR 3 ) 2 Cl 2 RuCR 1 R positions, consistent with the steric requirements of, for example, PPh 3 , PCy 3 , or P(iPr) 3 . The P-Ru-P angles range from around 160 to 1708, [1, 3, 6a, 12, 16] (2), the first ruthenium metathesis catalyst with cis stereochemistry due to a chelating bis(di-tert-butylphosphanyl)methane (dtbpm) ligand.…”

“…It remained unclear whether the isomers are in equilibrium (either by intramolecular rearrangement, as expected given the well-known nonrigidity of ML 5 complexes, [17] or by phosphane dissociation [13c] ) or exist as stable, noninterconverting species. Nevertheless, it was surprising that sterically demanding phosphanes with large cone angles such as PCy 3 and PiPr 3 would allow formation of cis complexes in observable quantities.…”

“…The presence of the base is essential, as in the absence of NEt 3 the same reaction conditions lead to the formation of the triply chlorobridged dinuclear mixed hydrido ± dihydrogen complex [(h 2 -dtbpm)Ru(H)](m 2 -Cl) 3 …”

“…[2] The accessibility of Grubbs- ] has been continuously improved, and the range of possible carbene ligand precursors extended from cyclopropenes [1] to diazoalkanes, [3] vinyl and propargyl chlorides, [4] 1,1-dihaloalkanes, [5] and finally to 1-alkynes. [6] Recently, ruthenium carbene complexes with bidentate Schiff base [7] and Wanzlick ± Arduengo-type carbene ligands, [8] as well as Ru vinylidene systems with Cp, hydridotris(pyrazolyl)borate, Cp*, [9] and h 6 -arene [10] ligands have extended the range of ruthenium-based metathesis catalysts.…”

Transition metal-based polymer chemistry: a critical micro-review

“…An alternative route to ruthenium alkylidenes that avoids the preparation of 2,2-diphenylcyclopropene was elaborated by Schwab et al [153,154]. The synthetic protocol entails the reaction of RuCl 2 .PPh 3 / 3 with a diazoalkane.…”