Cyclopentadienon‐Eisenkomplexe: Entdeckung, Eigenschaften und katalytische Reaktivität

Abstract

In jüngster Zeit haben Cyclopentadienon‐Eisenkomplexe ein großes Interesse in der organischen Chemie gefunden. Sie können aus einfachen und kostengünstigen Materialien synthetisiert werden, sind sehr stabil gegen Wasser und Luft und zeichnen sich durch einzigartige katalytische Eigenschaften aus, die auf den redoxaktiven Liganden zurückzuführen sind, der solchen Komplexen leistungsstarke Redoxeigenschaften verleiht. In diesem Kurzaufsatz erläutern wir die Synthese und mechanistischen Eigenschaften von Cyclopentadienon‐ Eisenkomplexen und fassen ihre Anwendung in redoxneutralen racemischen und enantioselektiven Reaktionen zusammen.

Phosphine‐NHC Manganese Hydrogenation Catalyst Exhibiting a Non‐Classical Metal‐Ligand Cooperative H2 Activation Mode

“…Cooperative activation of inert chemical bonds is at opical concern in modern chemistry and homogeneous catalysis. Since the discovery of Shvo-type catalysts, [1] awide variety of transition metal complexes bearing non-innocent ligands was exploited for E À Hb ond activation, [2] recently supplemented by related reactivity of frustrated Lewis pairs [3] and maingroup ambiphiles. [4] Among all these transformations,t he activation of H 2 is of utmost importance because of its essential role in catalytic [transfer] hydrogenation [5] and hydrogen borrowing [6] processes relevant in fine chemicals industry.W hile the seminal contribution of Noyori and coll.…”

Iron‐Catalyzed α‐Alkylation of Ketones with Alcohols

“…Interestingly,the nature of the phosphine is also important:w ith 2mol %o fP ( o-Tol) 3 or P(2-methylfuryl) 3 ,similar results were achieved, whereas in the presence of 2mol %o fP Cy 3 ,P PhMe 2 ,o rP (OPh) 3 ,l ess active and selective transformations were observed (Supporting Information, Table S4). Obviously,n oc oupling occurred in the absence of iron catalyst or Cs 2 CO 3 as the base,o rw hen the reaction was performed in neat conditions (Table 1, entries [11][12][13].…”

Phosphine‐NHC Manganese Hydrogenation Catalyst Exhibiting a Non‐Classical Metal‐Ligand Cooperative H2 Activation Mode

“…Since the discovery of Shvo-type catalysts, [1] awide variety of transition metal complexes bearing non-innocent ligands was exploited for E À Hb ond activation, [2] recently supplemented by related reactivity of frustrated Lewis pairs [3] and maingroup ambiphiles. Since the discovery of Shvo-type catalysts, [1] awide variety of transition metal complexes bearing non-innocent ligands was exploited for E À Hb ond activation, [2] recently supplemented by related reactivity of frustrated Lewis pairs [3] and maingroup ambiphiles.…”

“…Compassing our recent investigations on the application of Mn I complexes supported by bidentate ligands in hydrogenation-type catalysis, [10] we turned our attention to the use of ligand systems now associating phosphine and NHC donors.C omplex 2 was readily obtained in 86 %y ield from the corresponding phosphine-imidazolium salt [1]OTs [11] through the sequential addition of KHMDS and [Mn-(CO) 5 Br] (Scheme 2). According to IR and NMR spectroscopy,t he air stable complex 2 forms as as ingle isomer (d P 71.3 ppm (s), d C 197.7 ppm (d, 2 J PC = 17.5 Hz, C N 2 C )), presenting af acial arrangement of the three carbonyl ligands as confirmed by an XRD study (Figure 1a).…”