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

Article abstract of DOI:10.1002/anie.202103222

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.

Full text of DOI:10.1002/anie.202103222

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
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International Edition
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Accepted Article
Title: Iron-Catalyzed Wacker-type Oxidation of Olefins at Room
Temperature with 1,3-Diketones or Neocuproine as Ligands
Authors: Florian Puls, Philipp Linke, Olga Kataeva, and Hans-Joachim
Knölker
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10.1002/anie.202103222
Angewandte Chemie International Edition
RESEARCH ARTICLE
Iron-Catalyzed Wacker-type Oxidation of Olefins at Room
Temperature with 1,3-Diketones or Neocuproine as Ligands**
Florian Puls, Philipp Linke, Olga Kataeva, and Hans-Joachim Knölker*
[*]
Dr. F. Puls, P. Linke, Prof. Dr. H.-J. Knölker
Fakultät Chemie und Lebensmittelchemie, Technische Universität Dresden
Bergstraße 66, 01069 Dresden (Germany)
E-mail: hans-joachim.knoelker@tu-dresden.de
Dr. O. Kataeva
A. E. Arbuzov Institute of Organic and Physical Chemistry
FRC Kazan Scientific Center, Russian Academy of Sciences
Arbuzov Str. 8, Kazan 420088 (Russia)
[**]
Part 148 of “Transition Metals in Organic Synthesis”; for part 147, see: V. Lösle, O. Kataeva, H.-J. Knölker, Synthesis 2021, 53, 359–364.
Supporting information for this article is given via a link at the end of the document.
Dedicated to Professor K. Peter C. Vollhardt on the occasion of his 75th birthday.
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 for
ketone formation, 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.
Figure 1. Selected biologically active and natural compounds with ketone
moieties.
A common method for the synthesis of ketones is the
palladium-catalyzed oxidation of alkene substrates, well known
as the Wacker oxidation.[8] Since its discovery in the late 1950’s,
this transformation found a wide range of applications in natural
product synthesis and in industry for the preparation of
pharmaceuticals as well as commodity chemicals. Moreover,
detailed mechanistic studies were reported.[8] However, the
Wacker process requires catalytic amounts of palladium and
copper salts are used as reoxidant. Moreover, this catalytic
system is generally less efficient for the oxidation of internal
alkenes and electron-deficient olefins. Despite recent progress
to overcome these limitations,[9] the search for inexpensive
alternatives has led to the development of earth-abundant first-
row transition-metal catalysis for this transformation with
application of iron,[10] cobalt,[11] or nickel[12] compounds as
catalysts. Han et al. described a Wacker-type oxidation of
alkenes to ketones in ethanol at 80 °C using iron(II) chloride as
catalyst, polymethylhydrosiloxane (PMHS) as additive, and air
as sole oxidant.[10a] We described the conversion of olefins into
ketones proceeding in ethanol at room temperature using
iron(II)–hexadecafluorophthalocyanine as catalyst, triethylsilane
as additive, and oxygen as sole oxidant.[10b] In the course of our
project directed towards the application of iron compounds as
catalysts for operationally simple and convenient synthetic
transformations,[13] we have been searching to expand the
toolkit for the iron-catalyzed Wacker-type oxidation. Herein, we
Introduction
A wide variety of transition metals are known and well
established in catalyzing a broad range of transformations for
the synthesis of organic substrates.[1] In the past, mostly noble
metals like platinum, rhodium, or palladium have been
employed for this purpose. However, over the past few years,
the development of sustainable methodologies based on earth-
abundant first-row transition metals has gained much attention
because of the increasing demand for efficient and
environmentally benign synthetic methods.[2] In this context, iron
occupies the center stage.[3] Iron compounds offer several
advantages as catalysts, including high abundance in the
Earth’s crust, sustainability, low price, and high reactivity.
Another driving force for the move from precious to abundant
metal catalysis is the high toxicity of the noble metals.[4,5] Iron
exhibits a low toxicity and was involved in biological systems
since early on in evolution.[6]
Ketone moieties are found in
a large number of
biologically active compounds including drugs and natural
products (Figure 1). Furthermore, ketones represent versatile
intermediates in synthesis and crucial industrial components.[7]
1
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10.1002/anie.202103222
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RESEARCH ARTICLE
describe the development of an efficient iron-catalyzed
oxidation of alkenes to ketones at room temperature under air
With the more bulky diisobutyro- (dibm) or
dipivaloylmethanato (dpm) ligands we obtained only slightly
improved yields of 2a along with the by-products resulting from
radical dimerization (entries 2 and 3). Alteration of the ligand
atmosphere
using
either
readily
available
tris(dibenzoylmethanato)iron(III), or a combination of iron(II)
chloride and neocuproine as catalysts and phenylsilane as
reductive additive.
electronics
by
using
the
electron-deficient
trifluoroacetylacetonato (tfaa), hexafluoroacetylacetonato (hfaa),
or 4,4,4-trifluoro-1-phenyl-1,3-butanedionato (tfba) ligands led
to a sharp decrease of the yield for 2a (entries 4‒6),
presumably due to the increased Lewis acidity of the iron
complexes and their lower potential to capture oxygen.[16]
Finally, iron(III) complexes containing ligands with one or two
Results and Discussion
We used 2-vinylnaphthalene (1a) as model substrate and
performed the oxidations under air in ethanol as solvent and
with phenylsilane as additive. Because of their easy availability,
we explored the application of 1,3-diketonato iron(III) complexes
as catalysts (10 mol%) (Table 1).[14] The acetylacetonate
complex Fe(acac)3 provided only low yields of 2-
acetylnaphthalene (2a) (entry 1). Competing side reactions
were radical dimerizations to either 1,3-di(naphth-2-yl)butane
and 2,3-di(naphth-2-yl)butane,[10b] or reduction of the olefin to 2-
ethylnaphthalene.[15] Then, we explored the effect of the ligand
structure by testing a range of different 1,3-diketones as ligands
at iron(III) (Table 1).
phenyl
substituents
like
benzoylacetone
(ba)
or
dibenzoylmethane (dbm) were employed for this reaction. With
Fe(ba)3 as catalyst, the yield of 2a increased to 72% (entry 7)
and application of tris(dibenzoylmethanato)iron(III) [Fe(dbm)3]
gave 79% of 2a along with 8% of the corresponding alcohol 3a
(entry 8). A reduction of the catalyst load from 10 to 3 mol% led
to similar yields of 2a (entry 9). A pure oxygen atmosphere is
not required as it led to no significant increase in product
formation (entry 10). We demonstrated that the catalyst
Fe(dbm)3 could be applied to a gram-scale synthesis. Thus,
reaction of 6.5 mmol of 1a afforded within 5 h 80% of 2-
acetylnaphthalene (2a) along with 11% of the alcohol 3a (entry
11). Variation of the solvent, employment of hydrosilane
additives other than PhSiH3, or the addition of bases to the
reaction gave either lower yields or no product (see Supporting
Information, Tables S1–S3). Control experiments in the
absence of either Fe(dbm)3, or PhSiH3, or air (by performing the
reaction under an argon atmosphere) provided no product, thus
emphasizing a crucial role for each of these components.
Next, we investigated the steric and electronic influence of
substituents at the aryl moieties on the catalytic activity of the
corresponding iron complex by introduction of methyl-, tert-
butyl-, and methoxy groups (Scheme 1 and SI). Twofold
Friedel‒Crafts acylation of mesitylene or durene with malonyl
dichloride led to the β-diketones dimesitylenecarbonylmethane
(dmmH) or to didurenecarbonylmethane (ddmH).[17] 4-(tert-
Butyl)benzenecarbonyl]-[(4-methoxy)benzenecarbonyl]methane
(avobenzone, abH) and di(4-methoxy)benzenecarbonylmethane
(damH) are commercially available. The corresponding iron
complexes were prepared by mixing the appropriate 1,3-
diketone ligand with FeCl3 ∙ 6 H2O in aqueous ethanol at 60 °C
for 1 h (see SI for details). The structures for the complexes
Fe(ba)3, Fe(dbm)3,[18] Fe(dmm)3,[19] Fe(ab)3,[20] and Fe(ddm)3
were confirmed by X-ray analysis (Figures 2‒4, Figure S1, and
Figure S6).
Table 1. Ligand optimization for the iron-catalyzed Wacker-type oxidation
using 1,3-diketonato iron(III) complexes.[a]
Entry
R1
R2
Time [h]
Yield
Yield
2a [%]
3a [%]
1
2
Me
iPr
Me
iPr
tBu
Me
CF3
Ph
Ph
Ph
Ph
Ph
Ph
2
24
26
44
1
2
2
7
3
tBu
CF3
CF3
CF3
Me
Ph
6
8
4[b]
5[c]
6[d]
7
24
24
24
3.5
4.5
5.5
4.5
5
0
6
0
5
0
72
79
78
80
80
12
8
8
9[e]
10[e,f]
11[g]
Ph
14
8
Ph
Ph
11
[a] Reaction conditions: 1a (0.65 mmol), catalyst (10 mol%), PhSiH3 (2
equiv), EtOH (3 mL), room temperature, air; full conversion of starting
material was indicated by TLC analysis; all yields given refer to isolated
products. [b] 91% of starting material was recovered. [c] 84% of starting
material was recovered. [d] 75% of starting material was recovered. [e] With
3 mol% Fe(dbm)3. [f] The reaction was carried out under O2 (1 atm). [g]
Reaction conditions: 1a (6.5 mmol), Fe(dbm)3 (3 mol%), PhSiH3 (2 equiv),
Scheme 1. Synthesis of aryl substituted 1,3-diketonato iron(III) complexes.
For experimental details of the syntheses of Fe(dmm)3, Fe(ddm)3, Fe(ab)3,
and Fe(dam)3, see SI. dmm
didurenecarbonylmethanato,
methoxy)benzenecarbonyl]methanato
=
ab
dimesitylenecarbonylmethanato, ddm
4-(tert-Butyl)benzenecarbonyl]-[(4-
(avobenzonato); dam di(4-
methoxy)benzenecarbonylmethanato (dianisolecarbonylmethanato).
=
EtOH
(30 mL),
room
temperature,
air.
Fe(dbm)3
=
=
tris(dibenzoylmethanato)iron(III).
=
2
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10.1002/anie.202103222
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Application of the substituted aryl 1,3-diketone iron(III)
complexes as catalysts (5 mol%) in the Wacker-type oxidation
of 2-vinylnaphthalene (1a) revealed significant differences of
their catalytic activity (Table 2). Using Fe(dmm)3 and Fe(ddm)3,
degradation of the catalyst during the reaction occurred (entries
1 and 2). The avobenzone-derived iron(III) complex Fe(ab)3
showed a good performance as catalyst for the oxidation to 2a
and led to complete conversion of 1a after only 3.5 h at slightly
lower yields than obtained with Fe(dbm)3 (entry 3). However,
application of the more electron-rich complex Fe(dam)3 led to a
decrease in the yield of 2a as compared to the reaction using
Fe(ab)3 (entry 4).
Table 2. Efficiency of substituted 1,3-diaryl-1,3-diketonato iron(III) complexes
as catalysts for the Wacker-type oxidation.[a]
Figure 2. Molecular structure of tris(dibenzoylmethanato)iron(III) [Fe(dbm)3]
in the crystal (thermal ellipsoids are shown at the 50% probability level;
hydrogen atoms are omitted for clarity).
Entry
Iron(III) complex
Time
[h]
Reisolated
1a [%]
Yield
2a [%]
Yield
3a [%]
1
2
Fe(dmm)3
Fe(ddm)3
Fe(ab)3
5.5
5.5
3.5
5.5
39
30
-
26
49
70
55
9
7
3[b]
4
10
2
Fe(dam)3
25
[a] Reaction conditions: 1a (0.65 mmol), iron(III) catalyst (5 mol%), PhSiH3 (2
equiv), EtOH (3 mL), room temperature, air; all yields given refer to isolated
products. [b] Full conversion of starting material was verified by TLC analysis.
In our previous report, we have shown that highly pure
FeCl2 (99.99%) in combination with Et3SiH was not able to
convert the alkene 1a to the ketone 2a at room temperature.[10b]
Figure 3. Molecular structure of tris(dimesitylenecarbonylmethanato)iron(III)
[Fe(dmm)3] in the crystal (thermal ellipsoids are shown at the 50% probability
level; hydrogen atoms are omitted for clarity).
However in preliminary experiments, we achieved
a full
conversion of 1a even at room temperature after 4.5 h when
PhSiH3 was applied as additive. Therefore, we investigated the
catalytic activity of a range of simple iron compounds in the
Wacker-type oxidation of 1a to 2a at room temperature using
PhSiH3 as additive. 2-Vinylnaphthalene (1a) was treated with
5 mol% of an iron compound and 2 equiv of PhSiH3 in ethanol
under air (Table 3). Iron(II) or iron(III) chloride salts (entries 1‒3)
and the readily available ionic liquid [bmim][FeCl4][21] (entry 10)
gave moderate yields of 2a in the range of 59‒69%, whereas
other iron compounds were less efficient (entries 4‒9). In order
to avoid the observed decomposition of substrate 1a, we have
studied a broad range of supporting ligands using FeCl2 as
catalyst and identified neocuproine (2,9-dimethyl-1,10-
phenathroline) as the best ligand to improve the catalytic
performance (see SI, Table S4). A detailed optimization by
variation of iron compounds, solvents, and hydrosilanes, and
testing the presence of base additives (see SI, Tables S5–S8)
led to the combination of FeCl2/neocuproine (3 mol% each) with
phenylsilane (2 equiv) as additive in ethanol at room
temperature as optimized reaction conditions which provided 2a
in 76% yield (entry 11). This set of conditions appears to work
Figure 4. Molecular structure of tris{[4-(tert-butyl)benzenecarbonyl]-[(4-
methoxy)benzenecarbonyl]methanato}iron(III) [Fe(ab)3] in the crystal (thermal
ellipsoids are shown at the 50% probability level; hydrogen atoms are omitted
for clarity).
3
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RESEARCH ARTICLE
even better on a larger scale, starting with 1.0 g (6.5 mmol) of
2-vinylnaphthalene (1a) provided 2-acetylnaphthalene (2a) in
83% yield (entry 12).
(1k and 1l) afforded regioselectively the corresponding benzylic
ketones 2g‒2l in yields ranging from 74–87%. The conversion
of the naturally occurring phenylpropanoid α-asarone (1h) into
the
ketone
2h
proceeded
faster
with
tris(benzoylacetonato)iron(III) [Fe(ba)3] as catalyst. Surprisingly,
reaction of cinnamyl chloride (1j) even after prolonged reaction
times (48 h) and with a higher load of the catalyst Fe(dbm)3
(10 mol%) gave a poor turnover of the starting material (35% of
Table 3. Optimization for the iron-catalyzed Wacker-type oxidation using
different iron compounds as catalysts with PhSiH3 as additive.[a]
2j,
49 %
re-isolated
1j).
However,
using
tris(benzoylacetonato)iron(III) (3 mol%) as catalyst provided the
product 2j in 81% yield after 6.5 h with no alcohol 3j as by-
product. Aliphatic terminal or internal olefins (1m–1o) proved to
be useful starting materials for the iron-catalyzed Wacker-type
oxidation. Thus, using either method A or B afforded the
corresponding ketones 2m–2o in moderate yields (35–62%)
with an increased proportion of the alcohol by-products 3m–3o
(14–47%). Octadecan-2-one (2n) is a natural product which
has been isolated from various sources.[23] Oxidation of the
iminostilbene 1p to the corresponding ketone 2p proceeded
very slowly with Fe(dbm)3 as catalyst. With Fe(ba)3 as catalyst
(3 mol%), 2p was obtained in 70% yield. Compound 2p is a
direct synthetic precursor for the antiepileptic drug
oxcarbazepine.[24] Finally, we demonstrated the applicability of
the present method for the synthesis of natural products.
Oxidation of the pyrano[3,2-a]carbazole alkaloid girinimbine
(1q)[25] using Fe(dbm)3 as catalyst (method A) provided the
naturally occurring euchrestifoline (2q)[26] in 54% yield along
with 43% of the corresponding alcohol 3q, whereas methods B
and C failed in this case.
Entry
Iron source
Time
[h]
Reisolated
1a [%]
Yield
2a [%]
Yield
3a [%]
1
2
FeCl2
4.5
4.5
3.5
4.5
4.5
4.5
4.5
4.5
24
-
69
59
60
46
traces
7
13
5
FeCl2 ∙ 4 H2O
FeCl3
20
-
3
14
8
4
FeBr2
34
87
76
55
66
22
12
-
5
Fe(C2O4) ∙ 2 H2O
FeF3
0
6
0
7
Fe(OAc)2
FeSO4 ∙ 7 H2O
[CpFe(CO)2]2
[bmim][FeCl4]
FeCl2
19
2
3
8
0
9
47
65
76
83
3
10
11[b]
12[c]
24
9
We have performed a series of mechanistic experiments
in order to gain more information on the mechanism of the iron-
catalyzed Wacker-type oxidation (see Supporting Information
for details). All the mechanistic experiments described below
have been accomplished with both sets of optimized reaction
conditions, method A and method B. Using per-deuterated
ethanol (EtOD-[D5]) as solvent for the oxidation of 1a, no
deuterium was incorporated into the product. However, using
PhSiD3[27] as reductive additive led to a deuterium incorporation
of 97% in the methyl groups of the ketone 2a and in the alcohol
3a (Scheme 3). No product was formed when the reaction was
performed under argon. In order to support our assumption that
the oxygen incorporated in the products 2a and 3a derives from
the atmosphere, we have executed 18O-labeling experiments. In
fact, running the experiments under an atmosphere of 18O2, we
detected an 18O-incorporation of 92% into both products with
method A and of 95% with method B (see SI). This outcome
unequivocally confirmed that the oxygen atoms incorporated
into the ketone and into the alcohol both derive from the
atmosphere. Using 2-vinylnaphthalene with a deuterium atom at
the α-position (1a-[α-D1], D-content 92%) led exclusively to
unlabeled ketone 2a and labeled alcohol 1-deutero-1-
(naphthalen-2-yl)ethanol (3a-[α-D1]) with the same deuterium
content (92%) at the benzylic position. Thus, we conclude that
the alcohol 3a is not formed via a subsequent iron-catalyzed
reduction of the ketone 2a. In line with this conclusion, reaction
of the ketone 2a with PhSiH3 in the presence of either Fe(dbm)3
or FeCl2/neocuproine as catalysts provided no alcohol 3a. In
contrast, our previous findings have shown that the iron-
catalyzed Wacker-type oxidation of 1a with iron(II)–
hexadecafluorophthalocyanine as catalyst provided the alcohol
3.5
3
14
15
FeCl2
-
[a] Reaction conditions: 1a (0.65 mmol), catalyst (5 mol%), PhSiH3 (2 equiv),
EtOH (3 mL), room temperature, air; all yields given refer to isolated products.
[b] With FeCl2 (3 mol%), and neocuproine (2,9-dimethyl-1,10-phenanthroline,
mol%). [c] Reaction conditions: 1a (6.5 mmol), FeCl2 (3 mol%),
neocuproine (3 mol%), PhSiH3 (2 equiv), EtOH (30 mL), room temperature,
air. bmim = 1-butyl-3-methylimidazolium, Cp = cyclopentadienyl.
3
The substrate scope of the iron-catalyzed Wacker-type
oxidation was investigated using the two sets of optimized
reaction conditions described above with either 3 mol% of
Fe(dbm)3 (method A) or 3 mol% each of FeCl2/neocuproine
(method B) as catalyst systems in the presence of phenylsilane
(2 equiv) in ethanol at room temperature under air (Table 4). In
order to show the effect of the neocuproine ligand on the iron
catalysis, some substrates have been converted using only 3
mol% of FeCl2 as catalyst (method C). A range of terminal
styrene derivatives (1a‒1f) was efficiently transformed into the
corresponding aryl methyl ketones 2a‒2f in yields of up to 97%
and with the alcohols 3a–3f as the only by-products. The
neocuproine ligand in method B generally leads to shorter
reaction times and less decomposition of the substrate
compared to method C using only FeCl2 as catalyst. Thus, the
influence of neocuproine is ascribed to a ligand-accelerated
catalysis.[22] This assumption derives support from the fact that
in contrast to the FeCl2/neocuproine system, the preformed
complex
dichloro(2,9-dimethyl-1,10-phenanthrolin-
κN1,κN10)iron(II), which has been characterized by X-ray
analysis (Figure S8), does not catalyze the oxidation of 1a (see
SI). Non-terminal styrene derivatives (1g‒1j) and chromenes
3a at least to some extent via subsequent reduction of 2a.[10b]
A
4
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10.1002/anie.202103222
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radical mechanism is assumed for the iron-catalyzed Wacker-
type oxidation based on the fact that no product was formed
when the reaction was executed in the presence of TEMPO (2
equiv). Treatment of either 1-(naphthalen-2-yl)ethanol (3a) or
the epoxide 2-(naphthalen-2-yl)oxirane under reaction
conditions of either method A or method B did not afford the
ketone 2a. These results confirmed that neither a mechanism
via hydration and subsequent dehydrogenation[28] nor via
epoxidation and subsequent Meinwald rearrangement[29] is
involved in the formation of ketone 2a.
Table 4. Substrate scope for the iron-catalyzed Wacker-type oxidation.[a]
[a] For complete conversion of 1 (0.65 mmol), the progress of the reaction was monitored by TLC and GC-MS analysis of the reaction mixture. Yields given refer
to isolated products (ketones 2a–2q, alcohols 3a–3q). [b] Tris(benzoylacetonato)iron(III) Fe(ba)3 (3 mol%) was used instead of Fe(dbm)3. [c] NaOAc (6 mol%)
was additionally to accelerate the reaction (Table S8). [d] No conversion, starting material [girinimbine (1q)] was quantitatively recovered. TIPS = triisopropylsilyl.
Based on the results of our mechanistic experiments and
previous reports,[10b,30] we propose the following catalytic cycle
for the iron-catalyzed Wacker-type oxidation of olefins to
ketones using the conditions described above (methods A–C)
(Scheme 4). Ligand exchange by ethanol and loss of a proton
generate an iron(III) ethoxide complex FeX2OEt (A). Subsequent
reaction with PhSiH3 leads to an iron(III) hydride complex along
with PhSiH2(OEt) (B).[30a] Hydrogen atom transfer (HAT)[31] with
an olefin generates a carbon-centered radical and an iron(II)
species which are in equilibrium with an iron(III)‒alkyl complex
(C). The latter can also be formed by insertion of the olefin into
the iron(III) hydride complex (hydrometalation). Capturing of
oxygen affords an iron(III)‒peroxoalkyl complex (D). Finally,
breaking of the O‒O and C‒H bonds provides the ketone (E)[32]
and an iron(III) hydroxide which either reacts with ethanol to
Scheme 3. Labeling experiments for the iron-catalyzed Wacker-type oxidation.
regenerate the iron(III) ethoxide (F), or transmetalation with
5
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10.1002/anie.202103222
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phenylsilane provides directly the iron(III) hydride species along
with phenylsilanol as by-product (G). A hydroxyl radical transfer
to the alkyl radical can form the alcohol as a by-product of this
process (H).[33]
clearly identified the hydrosilane additive as the origin of the
additional hydrogen atom at the terminal carbon atom and
oxygen from the atmosphere as source for the oxo group. The
method was shown to be useful for the synthesis of bioactive
compounds and natural products.
Supporting Information Summary
See the Supporting Information for the synthesis of the iron
complexes, complete characterization of all compounds, details
of the optimization studies, copies of the NMR spectra (1H, 13C +
DEPT, 19F), Mössbauer spectroscopy of Fe(dbm)3, and the
mechanistic experiments.
Acknowledgements
We are grateful to the Deutsche Forschungsgemeinschaft
(DFG) for the financial support of our project „Green and
Sustainable Catalysts for Synthesis of Organic Building
Blocks“ (DFG grant KN 240/19-2). We thank the Deutscher
Akademischer Austauschdienst (DAAD) for support (57507438).
We are indebted to Felix Seewald, Institute of Solide State and
Materials Physics, TU Dresden, for the measurement of the
Mössbauer spectrum of Fe(dbm)3.
Scheme 4. Proposed mechanism for the iron-catalyzed Wacker-type oxidation
of olefins to ketones using iron(III) compounds (method A–C).
Conflict of interest
Alternatively, a Mukaiyama hydration by metal exchange of
the intermediate iron(III)–peroxoalkyl complex with hydrosilane
could generate an iron(III) hydride and a silyl peroxoalkyl
compound (Scheme 5).[34] Rearrangement of the latter and
reaction with ethanol would also lead to the alcohol.
The authors declare no conflict of interest.
Keywords: homogeneous catalysis • iron • olefins • ketones •
1,3-diketones • hydrosilanes
[1]
a) Transition Metals for Organic Synthesis: Building Blocks and Fine
Chemicals, Second Revised and Enlarged Edition (Eds.: M. Beller, C.
Bolm), Wiley-VCH, Weinheim, 2004; b) Organic Synthesis Using
Transition Metals, 2nd Edition (Ed.: R. Bates), Wiley-VCH, Weinheim,
2012.
[2]
a) Catalysis without Precious Metals (Ed.: R. M. Bullock), Wiley-VCH,
Weinheim, 2010; b) N. V. Tzouras, I. K. Stamatopoulos, A. T.
Papastavrou, A. A. Liori, G. C. Vougioukalakis, Coord. Chem.
Rev. 2017, 343, 25–138; c) Non-Noble Metal Catalysis: Molecular
Approaches and Reactions (Eds.: R. J. M. Klein Gebbink, M.-E. Moret),
Wiley-VCH, Weinheim, 2019.
Scheme 5. Proposed formation of the alcohol by-product via Mukaiyama
hydration.
[3]
a) C. Bolm, J. Legros, J. Le Paih, L. Zani, Chem. Rev. 2004, 104,
6217–6254; b) Iron Catalysis in Organic Chemistry: Reactions and
Applications (Ed.: B. Plietker), Wiley-VCH, Weinheim, 2008; c) Top.
Organomet. Chem. 2015, 50, 1–356 (Ed.: E. Bauer); d) I. Bauer, H.-J.
Knölker, Chem. Rev. 2015, 115, 3170–3387; e) A. Fürstner, ACS Cent.
Sci. 2016, 2, 778–789; f) R. Shang, L. Ilies, E. Nakamura, Chem. Rev.
2017, 117, 9086–9139; g) A. Guðmundsson, J.-E. Bäckvall, Molecules
2020, 25, 1349.
Conclusion
In summary, we have developed two protocols for the mild
iron-catalyzed oxidation of olefins to ketones using phenylsilane
(PhSiH3) as reductive additive and either the readily available
1,3-diketonato iron(III) complex tris(dibenzoylmethanato)iron(III)
[Fe(dbm)3] (or alternatively tris(benzoylacetonato)iron(III)
[Fe(ba)3]) or a combination of FeCl2 and neocuproine as
catalysts. Both protocols work at room temperature in ethanol as
solvent and need only air as sole oxidant. Cyclic as well as
acyclic styrenes and aliphatic alkenes are transformed into the
corresponding ketones with good functional group tolerance
using one of the two optimized protocols. Labeling studies
[4]
[5]
For a critical review on toxicity of transition metals, see: K. S. Egorova,
V. P. Ananikov, Angew. Chem. Int. Ed. 2016, 55, 12150‒12162; Angew.
Chem. 2016, 128, 12334‒12347.
a) In the preparation of pharmaceuticals, the contamination by
palladium must be less than 10 ppm. The ICH Q3D (R1) guideline on
elemental impurities can be found under www.ema.europa.eu/en/ich-
q3d-elemental-impurities; b) Handbook on the Toxicology of Metals, 4th
Edition (Eds.: G. Nordberg, B. Fowler, M. Nordberg), Academic Press,
London, 2014.
6
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10.1002/anie.202103222
Angewandte Chemie International Edition
RESEARCH ARTICLE
[6]
a) M. Sono, M. P. Roach, E. D. Coulter, J. H. Dawson, Chem. Rev.
1996, 96, 2841–2888; b) B. Meunier, S. P. de Visser, S. Shaik, Chem.
Rev. 2004, 104, 3947–3980; c) I. G. Denisov, T. M. Makris, S. G. Sligar,
I. Schlichting, Chem. Rev. 2005, 105, 2253–2277; d) J. Müller, M.
Bröring in Iron Catalysis in Organic Chemistry: Reactions and
Applications (Ed.: B. Plietker), Wiley-VCH, Weinheim, 2008, chap. 2, pp.
29–72; e) S. Shaik, S. Cohen, Y. Wang, H. Chen, D. Kumar, W. Thiel,
Chem. Rev. 2010, 110, 949–1017; f) L. Podust, D. H. Sherman, Nat.
Prod. Rep. 2012, 29, 1251–1266; g) T. L. Poulos, Chem. Rev. 2014,
114, 3919–3962.
der Wissenschaften zu Leipzig – Math.-naturwiss. Klasse, S. Hirzel,
Stuttgart/Leipzig, 2021, Vol. 133, no. 4, pp. 1–30.
[14] Selected examples for applications of iron(III) 1,3-diketonato complexes,
see: a) S. M. Neumann, J. K. Kochi, J. Org. Chem. 1975, 40, 599‒606;
b) T. Takai, E. Hata, T. Yamada, T. Mukaiyama, Bull. Chem. Soc. Jpn.
1991, 64, 2513‒2518; c) P. A. Vigato, V. Peruzzo, S. Tamburini, Coord.
Chem. Rev. 2009, 253, 1099‒1201; d) S.-S. Weng, C.-S. Ke, F.-K.
Chen, Y.-F. Lyu, G.-Y. Lin, Tetrahedron 2011, 67, 1640‒1648; e) D.
Lübken, M. Saxarra, M. Kalesse, Synthesis 2019, 51, 161‒177; f) J. Lv,
J.-J. Zhu, Y. Liu, H. Dong, J. Org. Chem. 2020, 85, 3307‒3319.
[15] P. V. Kattamuri, J. G. West, J. Am. Chem. Soc. 2020, 142, 19316–
19326.
[7]
[8]
H. Siegel, M. Eggersdorfer, Ullmann’s Encyclopedia of Industrial
Chemistry, Vol. 20, 7th Edition (Ed.: M. Bohnet), Wiley-VCH, Weinheim,
2012, pp. 187‒208.
[16] a) C. Tsiamis, C. Michael, A. D. Jannakoudakis, P. D. Jannakoudakis,
Inorg. Chim. Acta 1986, 120, 1‒9; b) M. M. Conradie, J. Conradie,
Electrochim. Acta, 2015, 152, 512‒519; c) A. A. Adeniyi, J. Conradie,
Int. J. Quantum Chem. 2019, 119, e26036.
a) J. Smidt, W. Hafner, R. Jira, R. Sedlmeier, R. Sieber, R. Rüttinger, H.
Kojer, Angew. Chem. 1959, 71, 176–182; b) J. Smidt, W. Hafner, R.
Jira, R. Sieber, J. Sedlmeier, A. Sabel, Angew. Chem. 1962, 74, 93–
102; c) J. E. Bäckvall, B. Åkermark, S. O. Ljunggren, J. Am. Chem. Soc.
1979, 101, 2411–2416; d) J. Tsuji, Synthesis 1984, 369‒384; e) P. M.
Henry in Handbook of Organopalladium Chemistry for Organic
[17] C. Zhang, P. Yang, Y. Yang, X. Huang, X.-J. Yang, B. Wu, Synth.
Commun. 2008, 38, 2349‒2356.
[18] Crystallographic data for Fe(dbm)3: C45H33FeO6, M = 725.56 g mol‒1
,
Synthesis, Vol.
2
(Ed.: E. Negishi), Wiley, New York, 2002, pp.
crystal size: 0.100  0.209  0.342 mm3, triclinic, space group P1¯, a =
9.7947(7), b = 10.4344(7), c = 18.2360(14) Å, α = 93.258(3), β =
93.333(3), γ = 106.151(3)°, V = 1782.0(2) Å3, Z = 2, ρcalcd = 1.352 g/cm3,
μ = 0.474 mm‒1, λ = 0.71073 Å, T = 150(2) K, θ range: 2.25‒30.63°,
reflections collected: 119766, independent: 10900 (Rint = 0.0389), 469
parameters. The structure was solved by direct methods and refined by
full-matrix least-squares on F2; final R indices [I > 2σ(I)]: R1 = 0.0356,
wR2 = 0.1067; maximal residual electron density: 0.647 e Å–3. CCDC-
2064663 contains the supplementary crystallographic data for this
structure. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre.
2119‒2139; f) J. Takacs, X.-t. Jiang, Curr. Org. Chem. 2003, 7, 369–
396; g) J. Tsuji, Palladium Reagents and Catalysts: New Perspectives
for the 21st Century, 2nd Edition, Wiley, Hoboken, 2004, pp. 27‒35; h)
M. G. Clerici, M. Ricci, G. Strukul in Metal-catalysis in Industrial Organic
Processes (Eds.: G. P. Chiusoli, P. M. Maitlis), Royal Society of
Chemistry RSC Publishing, Cambridge, 2006, pp. 65–73; i) R. Jira,
Angew. Chem. Int. Ed. 2009, 48, 9034‒9037; Angew. Chem. 2009, 121,
9196‒9199; j) G. Kovács, A. Stirling, A. Lledós, G. Ujaque, Chem. Eur.
J. 2012, 18, 5612–5619; k) P. Kočovský, J.-E. Bäckvall, Chem. Eur. J.
2015, 21, 36–56; l) R. Jira in Applied Homogeneous Catalysis with
Organometallic Compounds,
A
Comprehensive Handbook in Four
For comparison see: E. G. Zaitseva, I. A. Baidina, P. A. Stabnikov, S. V.
Volumes, 3rd Edition (Eds.: B. Cornils, W. A. Herrmann, M. Beller, R.
Paciello), Wiley-VCH, Weinheim, 2018, pp. 488‒508; m) O. N. Temkin,
Kinet. Catal. 2020, 61, 663‒720; n) R. A. Fernandes, A. K. Jha, P.
Kumar, Catal. Sci. Technol. 2020, 10, 7448–7470.
Borisov, I. K. Igumenov, J. Struct. Chem. 1990, 31, 349‒354.
[19] Crystallographic data for Fe(dmm)3: C63H69FeO6, M = 978.03 g mol‒1
,
crystal size: 0.069  0.122  0.311 mm3, monoclinic, space group P21/n,
a = 15.910(2), b = 17.615(2), c = 19.133(2) Å, β = 92.430(5)°, V =
5357.3(12) Å3, Z = 4, ρcalcd = 1.213 g cm‒3, μ = 0.332 mm‒1, λ = 0.71073
Å, T = 150(2) K, θ range: 1.57‒27.55°, reflections collected: 102448,
independent: 12322 (Rint = 0.0833), 649 parameters. The structure was
solved by direct methods and refined by full-matrix least-squares on F2;
final R indices [I > 2σ(I)]: R1 = 0.0456, wR2 = 0.0981; maximal residual
[9]
For representative examples, see: a) T. Mitsudome, K. Mizumoto, T.
Mizugaki, K. Jitsukawa, K. Kaneda, Angew. Chem. Int. Ed. 2010, 49,
1238‒1240; Angew. Chem. 2010, 122, 1260‒1262; b) B. W. Michel, L.
D. Steffens, M. S. Sigman, J. Am. Chem. Soc. 2011, 133, 8317–8325;
c) P. Teo, Z. K. Wickens, G. Dong, R. H. Grubbs, Org. Lett. 2012, 14,
3237–3239; d) B. Morandi, Z. K. Wickens, R. H. Grubbs, Angew. Chem.
Int. Ed. 2013, 52, 2944‒2948; Angew. Chem. 2013, 125, 3016‒3020; e)
T. Mitsudome, S. Yoshida, T. Mizugaki, K. Jitsukawa, K. Kaneda,
Angew. Chem. Int. Ed. 2013, 52, 5961‒5964; Angew. Chem. 2013, 125,
6077‒6080; f) R. A. Fernandes, D. A. Chaudhari, J. Org. Chem. 2014,
79, 5787–5793; g) Q. Cao, D. S. Bailie, R. Fu, M. J. Muldoon, Green
Chem. 2015, 17, 2750–2757; h) D. A. Chaudhari, R. A. Fernandes, J.
Org. Chem. 2016, 81, 2113–2121; i) K.-F. Hu, X.-S. Ning, J.-P. Qu, Y.-
B. Kang, J. Org. Chem. 2018, 83, 11327‒11332; j) Y. A. Ho, E.
Paffenholz, H. J. Kim, B. Orgis, M. Rueping, D. C. Fabry,
ChemCatChem 2019, 11, 1889‒1892; k) Q. Huang, Y.-W. Li, X.-S.
Ning, G.-Q. Jiang, X.-W. Zhang, J.-P. Qu, Y.-B. Kang, Org. Lett. 2020,
22, 965‒969.
electron density: 0.327
e
Å–3
.
CCDC-2064664 contains the
supplementary crystallographic data for this structure. These data can
be obtained free of charge from The Cambridge Crystallographic Data
Centre.
[20] Crystallographic data for Fe(ab)3: C63H63FeO9 · CH2Cl2, M = 1068.88 g
mol‒1, crystal size: 0.251  0.215  0.136 mm3, monoclinic, space group
C2/c, a = 35.6827(12) b = 12.8286(4), c = 30.7195(11) Å, β =
110.2530(12)°, V = 13192.7(8) Å3, Z = 8, ρcalcd = 1.076 g cm3, μ = 0.357
mm‒1, λ = 0.71073 Å, T = 150(2) K, θ range: 2.34‒26.82°, reflections
collected: 100690, independent: 16346 (Rint = 0.0730), 668 parameters.
The structure was solved by direct methods and refined by full-matrix
least-squares on F2; final R indices [I > 2σ(I)]: R1 = 0.0692, wR2
=
0.2056; maximal residual electron density: 0.597 e Å–3. CCDC-2067942
contains the supplementary crystallographic data for this structure.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre.
[10] a) B. Liu, F. Jin, T. Wang, X. Yuan, W. Han, Angew. Chem. Int. Ed.
2017, 56, 12712–12717; Angew. Chem. 2017, 129, 12886–12891; b) F.
Puls, H.-J. Knölker, Angew. Chem. Int. Ed. 2018, 57, 1222‒1226;
Angew. Chem. 2018, 130, 1236‒1240.
[21] S. Hayashi, H. Hamaguchi, Chem. Lett. 2004, 33, 1590‒1591.
[22] D. J. Berrisford, C. Bolm, K. B. Sharpless, Angew. Chem. Int. Ed. Engl.
1995, 34, 1059‒1070; Angew. Chem. 1995, 107, 1159‒1171.
[23] a) A. Ulubelen, T. Baytop, Phytochemistry 1973, 12, 1824; b) J. O.
Grimalt, L. Angulo, A. López-Galindo, M. C. Comas, J. Albaigés, Chem.
Geol. 1990, 82, 341–363; c) M. P. Rahelivao, T. Lübken, M. Gruner, O.
Kataeva, R. Ralambondrahety, H. Andriamanantoanina, M. P.
Checinski, I. Bauer, H.-J. Knölker, Org. Biomol. Chem. 2017, 15, 2593–
2608.
[11] a) Y. Matsushita, T. Matsui, K. Sugamoto, Chem. Lett. 1992, 1381–
1384; b) G. Huang, L. Wang, H. Luo, S. Shang, B. Chen, S. Chen, S.
Gao, Y. An, Catal. Sci. Technol. 2020, 10, 2769‒2773.
[12] B. Liu, P. Hu, F. Xu, L. Cheng, M. Tan, W. Han, Commun. Chem. 2019,
2, 5.
[13] a) R. F. Fritsche, G. Theumer, O. Kataeva, H.-J. Knölker, Angew.
Chem. Int. Ed. 2017, 56, 549‒553; Angew. Chem. 2017, 129, 564‒568;
b) C. Brütting, R. F. Fritsche, S. K. Kutz, C. Börger, A. W. Schmidt, O.
Kataeva, H.-J. Knölker, Chem. Eur. J. 2018, 24, 458‒470; c) A. Purtsas,
O. Kataeva, H.-J. Knölker, Chem. Eur. J. 2020, 26, 2499‒2508; d) A.
Purtsas, S. Stipurin, O. Kataeva, H.-J. Knölker, Molecules 2020, 25,
1608; e) H.-J. Knölker, Sitzungsberichte der Sächsischen Akademie
[24] a) A. Citterlo, G. Breviglieri, G. Bruno, G. Blanchetti, European Patent
Application, EP 1127877A2 (2001); b) T. A. Glauser, Pharmacotherapy
2001, 21, 904–919; c) G. Flesch, Clin. Drug Invest. 2004, 24, 185–203;
d) P. C. Fuenfschilling, W. Zaugg, U. Beutler, D. Kaufmann, O. Lohse,
7
This article is protected by copyright. All rights reserved.

10.1002/anie.202103222
Angewandte Chemie International Edition
RESEARCH ARTICLE
J.-P. Mutz, U. Onken, J.-L. Reber, D. Shenton, Org. Process Res. Dev.
2005, 9, 272–277; e) J. M. Gomez-Arguelles, R. Dorado, J. M.
Sepulveda, A. Herrera, F. Gilo Arrojo, E. Aragón, C. Ruiz Huete, C.
Terrón, B. Anciones, J. Clin. Neurosci. 2008, 15, 516–519; f) H. Singh,
N. Gupta, P. Kumar, S. K. Dubey, P. K. Sharma, Org. Process Res.
Dev. 2009, 13, 870–874.
[25] Isolation: a) N. L. Dutta, C. Quasim, Indian J. Chem. 1969, 7, 307–308;
b) B. S. Joshi, V. N. Kamat, D. H. Gawad, T. R. Govindachari,
Phytochemistry 1972, 11, 2065–2071; syntheses: c) D. P. Chakraborty,
A. Islam, J. Indian Chem. Soc. 1971, 48, 91‒92; d) K. K. Gruner, T.
Hopfmann, K. Matsumoto, A. Jäger, T. Katsuki, H.-J. Knölker, Org.
Biomol. Chem. 2011, 9, 2057–2061; e) R. Hesse, K. K. Gruner, O.
Kataeva, A. W. Schmidt, H.-J. Knölker, Chem. Eur. J. 2013, 19, 14098–
14111.
[26] a) Isolation: T.-S. Wu, M.-L. Wang, P.-L. Wu, Phytochemistry 1996, 43,
785–789; syntheses: b) K. K. Gruner, H.-J. Knölker, Org. Biomol. Chem.
2008, 6, 3902‒3904; c) F. Puls, O. Kataeva, H.-J. Knölker, Eur. J. Org.
Chem. 2018, 4272‒4276; c) G. Chakraborti, S. Paladhi, T. Mandal, J.
Dash, J. Org. Chem. 2018, 83, 7347‒7359.
[27] K. Aoyagi, Y. Ohmori, K. Inomata, K. Matsumoto, S. Shimada, K. Sato,
Y. Nakajima, Chem. Commun. 2019, 55, 5859‒5862.
[28] a) H. Song, B. Kang, S. H. Hong, ACS Catal. 2014, 4, 2889‒2895; b) S.
Chakraborty, P. O. Lagaditis, M. Förster, E. A. Bielinski, N. Hazari, M. C.
Holthausen, W. D. Jones, S. Schneider, ACS Catal. 2014, 4,
3994‒4003.
[29] J. Meinwald, S. S. Labana, M. S. Chadha, J. Am. Chem. Soc. 1963, 85,
582‒585.
[30] a) J. C. Lo, D. Kim, C.-M. Pan, J. T. Edwards, Y. Yabe, J. H. Gui, T. Qin,
S. Gutiérrez, J. Giacoboni, M. W. Smith, P. L. Holland, P. S. Baran, J.
Am. Chem. Soc. 2017, 139, 2484‒2503; b) D. Kim, S. M. Wahidur
Rahaman, B. Q. Mercado, R. Poli, P. L. Holland, J. Am. Chem. Soc.
2019, 141, 7473‒7485; c) H. Jiang, W. Lai, H. Chen, ACS Catal. 2019,
9, 6080‒6086.
[31] a) M. Tilset, V. D. Parker, J. Am. Chem. Soc. 1989, 111, 6711‒6717; b)
R. Morris Bullock, E. G. Samsel, J. Am. Chem. Soc. 1990, 112,
6886‒6898; c) D. C. Eisenberg, J. R. Norton, Isr. J. Chem. 1991, 31,
55‒66; d) D. C. Eisenberg, C. J. C. Lawrie, A. E. Moody, J. R. Norton, J.
Am. Chem. Soc. 1991, 113, 4888‒4895; e) S. A. Green, S. W. M.
Crossley, J. L. M. Matos, S. Vásquez-Céspedes, S. L. Shevick, R. A.
Shenvi, Acc. Chem. Res. 2018, 51, 2628–2640; f) S. L. Shevick, C. V.
Wilson, S. Kotesova, D. Kim, P. L. Holland, R. A. Shenvi, Chem. Sci.
2020, 11, 12401–12422; g) S. Sarkar, K. P. S. Cheung, V. Gevorgyan,
Chem. Sci. 2020, 11, 12974–12993.
[32] R. D. Arasasingham, A. L. Balch, C. R. Cornman, L. Latos-Grazynski, J.
Am. Chem. Soc. 1989, 111, 4357‒4363.
[33] a) J. P. T. Zaragoza, T. H. Yosca, M. A. Siegler, P. Moënne-Loccoz, M.
T. Green, D. P. Goldberg, J. Am. Chem. Soc. 2017, 139, 13640‒13643;
b) X. Huang, J. T. Groves, Chem. Rev. 2018, 118, 2491‒2553; c) M. J.
Drummond, C. L. Ford, D. L. Gray, C. V. Popescu, A. R. Fout, J. Am.
Chem. Soc. 2019, 141, 6639‒6650; d) V. Yadav, R. J. Rodriguez, M. A.
Siegler, D. P. Goldberg, J. Am. Chem. Soc. 2020, 142, 7259‒7264.
[34] a) S. Isayama, T. Mukaiyama, Chem. Lett. 1989, 18, 1071‒1074; b) T.
Tokuyasu, S. Kunikawa, M. Shigeki, A. Masuyama, M. Nojima, Org.
Lett. 2002, 4, 3595‒3598; c) H. Gandhi, K. O’Reilly, M. K. Gupta, C.
Horgan, E. M. O’Leary, T. P. O’Sullivan, RSC Adv. 2017, 7,
19506‒19556; d) A. Bhunia, K. Bergander, C. D. Daniliuc, A. Studer,
Angew. Chem. Int. Ed. 2021, 60, 8313–8320; Angew. Chem. 2021, 133,
8394–8401.
8
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Entry for the Table of Contents
Iron enters the stage: Various iron catalyst systems featuring a range of different ligands have been evaluated for the Wacker-type
oxidation of olefins to ketones in the presence of phenylsilane at room temperature and ambient air. The transformation is
operationally simple, sustainable, exhibits a high functional group tolerance, and is applicable to natural product synthesis.
9
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