Iron‐Catalyzed Wacker‐type Oxidation of Olefins at Room Temperature with 1,3‐Diketones or Neocuproine as Ligands**

Abstract

Herein, we describe a convenient and general method for the oxidation of olefins to ketones using either tris(dibenzoylmethanato)iron(III) [Fe(dbm)3] or a combination of iron(II) chloride and neocuproine (2,9‐dimethyl‐1,10‐phenanthroline) as catalysts and phenylsilane (PhSiH3) as additive. All reactions proceed efficiently at room temperature using air as sole oxidant. This transformation has been applied to a variety of substrates, is operationally simple, proceeds under mild reaction conditions, and shows a high functional‐group tolerance. The ketones are formed smoothly in up to 97 % yield and with 100 % regioselectivity, while the corresponding alcohols were observed as by‐products. Labeling experiments showed that an incorporated hydrogen atom originates from the phenylsilane. The oxygen atom of the ketone as well as of the alcohol derives from the ambient atmosphere.

2,2′‐Bis(arylamino)‐1,1′‐biaryls as Building Blocks for the Synthesis of Dibenzo[d,f][1,3]diazepines, Dibenzo[d,f][1,3]diazepinones, and Dibenzo[c,e][1,2,7]thiadiazepine 6‐Oxides

“…We have an ongoing project directed towards the application of iron compounds as catalysts for convenient oxidative transformations, since iron compounds represent environmentally benign catalysts [30,31] . In this context, we found that the hexadecafluorophthalocyanine–iron(II) complex FePcF 16 , [32,33] which under air is immediately oxidized to μ‐oxo‐bis[(hexadecafluorophthalocyanine)iron(III)] (O[FePcF 16 ] 2 ) (Figure 2), [33f] shows exceptional reactivity as catalyst for the oxidative C−C homocoupling reaction of diarylamines 3 to 2,2′‐bis(arylamino)‐1,1′‐biaryl compounds 4 [34a,b] .…”

New Paradigms in Catalysis Inspired by Cytochromes P450

“…Furthermore, the same group developed more effective iron catalytic systems based on a hexacoordinated iron III complex comprising three O , O -chelating dibenzoylmethanato(dbm) [Fe(dbm) 3 ] ligands or an in situ combination of FeCl 2 and the N , N -chelating neocuproine ligand, thereby pushing the boundaries of the sustainable Wacker-type oxidation (Scheme 6 ). 25 In the presence of PhSiH 3 , these iron catalytic systems did not work for aromatic olefins and aliphatic olefins, even internal examples.…”

Sustainable Wacker‐Type Oxidations

“…Pushing the boundaries of sustainable Wacker‐type oxidations, the Knölker group reported in 2021 the first examples of iron catalysts operating in an air atmosphere and at room temperature with Markovnikov selectivity [29] . The precatalysts are based on a hexacoordinated iron(III) complex comprising three O , O ‐chelating dibenzoylmethanato (dbm) ligands or an in situ combination of FeCl 2 and the N , N ‐chelating neocuproine ligand (Scheme 11).…”