Catalytic epoxidations with pyridinebis(oxazoline)-methyltrioxorhenium complexes and nitrogen-containing catalyst systems

Article abstract of DOI:10.1002/ejic.201200736

The epoxidation of olefins with methyltrioxorhenium (MTO) in the presence of various chiral oxazolines and pyridinebis(oxazoline) ligands as well as achiral N-ligands has been investigated. By applying 1-octene as a model system, reaction conditions were optimized, and high yields and good chemoselectivity (>90 %) were achieved. By applying other aromatic and aliphatic olefins, similar chemoselectivities and up to 19 % enantioselectivity were obtained. The epoxidation of 1-octene using methyltrioxorhenium (MTO) in the presence of pyridinebis(oxazoline) and related ligands is reported. Although excellent chemoselectivity (>90 %) and good yields were obtained, low enantioselectivity was observed. Copyright

Full text of DOI:10.1002/ejic.201200736

FULL PAPER
DOI: 10.1002/ejic.201200736
Catalytic Epoxidations with Pyridinebis(oxazoline)–Methyltrioxorhenium
Complexes and Nitrogen-Containing Catalyst Systems
[a]
[a]
[a]
[b]
[b]
Konstanze Kiersch, Yuehui Li, Kathrin Junge, Normen Szesni, Richard Fischer,
[c]
[a]
Fritz E. Kühn, and Matthias Beller*
Keywords: Rhenium / Epoxidation / Alkenes / Homogeneous catalysis / N ligands
The epoxidation of olefins with methyltrioxorhenium (MTO)
in the presence of various chiral oxazolines and pyridinebis-
conditions were optimized, and high yields and good chemo-
selectivity (Ͼ90%) were achieved. By applying other aro-
matic and aliphatic olefins, similar chemoselectivities and up
to 19% enantioselectivity were obtained.
(oxazoline) ligands as well as achiral N-ligands has been in-
vestigated. By applying 1-octene as a model system, reaction
ation.[11] Although high catalytic activity of MTO has been
reported in various epoxidations, there still exists a strong
interest for further improving catalyst efficiency and sta-
bility, especially for terminal olefins.
Introduction
The epoxidation of olefins represents an important trans-
formation for organic synthesis as well as for the chemical
industry. State-of-the-art epoxidations should proceed un-
der environmentally benign reaction conditions with inex-
pensive catalysts by using sustainable terminal oxidants and
simple operation protocols.[1] In this respect, the choice of
the oxidant is a key issue. Next to air, hydrogen peroxide is
the most “green” and waste-avoiding oxidant, which can
oxidize organic compounds with an atom efficiency of
Among the different epoxides, ethylene oxide (EO) and
propylene oxide are the industrially most important prod-
ucts with respect to scale. Both are key feedstocks for a
[
12]
wide variety of bulk intermediates such as glycols
glycol ethers.
and
[
13,14]
More specifically, ethylene oxide was
produced on a 19 million ton scale in 2008 by direct oxi-
dation of ethylene with air or oxygen using a heterogeneous
[
1d,2]
4
7%.
With regard to the catalysts, the use of ruthe-
manganese-,
[
15]
silver-based catalyst. Notably, the EO process is also one
[
3]
[4]
[5]
[6,7]
nium-,
iron-,
and rhenium-based
of the largest chemical-process emitters of CO , which is
2
complexes is attractive. In this respect, methyltrioxorhen-
ium (MTO) is one of the most general homogeneous oxi-
dation catalysts that has been intensively developed by the
formed as the main byproduct. In contrast, the direct oxi-
dation of propylene with oxygen is unselective owing to the
competitive allylic oxidation reaction. However, the de-
mand for propylene oxide (1,2-propylene oxide) is steadily
growing with more than 6.7 million tons produced in
[
6]
group of Herrmann and later by Espenson and co-
[
8]
workers. MTO shows a high thermal stability and is solu-
ble in most organic solvents and water.[6a,9] Notably, MTO
activates hydrogen peroxide without significantly decom-
[
16]
2004.
Hence, significant research interest exists to find
more efficient and less problematic processes for the cata-
[
10b]
posing the oxidant.
Over the last decade, the mechanism
[
17]
lytic synthesis of lower aliphatic epoxides.
In fact, re-
of MTO-catalyzed epoxidations has been studied in detail,
both from a kinetic and theoretical point of view in homo-
geneous and heterogeneous variations.[ A significant im-
provement in MTO-catalyzed epoxidations has been
achieved by the addition of nitrogen-containing ligands
such as substituted pyridines, pyrazoles, or imidazoles to
suppress the ring opening and accelerate alkene epoxid-
cently the first industrial plants for epoxidation of propyl-
ene with hydrogen peroxide by Evonik and BASF using ti-
tanium-based catalysts went on stream.
10]
Since MTO is known to be a highly active catalyst for
[
18]
alkene epoxidation with H O ,
in a joint cooperation
2
2
with former Süd-Chemie AG a research program on the
MTO-catalyzed epoxidation of terminal aliphatic olefins
was started. In this study, we present a full account of our
results for the epoxidation of 1-octene using MTO in the
presence of several chiral and achiral ligands. 1-Octene was
used as the model substrate for terminal lower aliphatic ole-
fins owing to its easier handling. Furthermore, experiments
[
a] Leibniz-Institut für Katalyse an der Universität Rostock e.V.
Albert-Einstein-Straße 29a, 18059 Rostock, Germany
Fax: +49-381-1281-51113
E-mail: Matthias.Beller@catalysis.de
Homepage: www.catalysis.de
[
[
b] Süd-Chemie AG, R&D Catalytic Technologies,
Waldheimer Straße 13, 83052 Bruckmühl, Germany
c] Molecular Catalysis, Catalysis Research Center, TU München,
Lichtenbergstraße 4, 85747 Garching bei München, Germany
for the chiral epoxidation of different olefins with H O as
2
2
oxidant were performed and are presented here.
5972
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 5972–5978

Catalytic Epoxidations
Results and Discussion
Oxidation of 1-Octene
Table 1. Testing different ligands in the catalytic epoxidation of 1-
octene with MTO/H O .
2 2
[a]
Although MTO can oxidize olefins without any addi-
tives, it is known that the addition of specific ligands im-
proves conversion and selectivity.[ For example, 1-octene
is smoothly oxidized in dichloromethane in the presence of
MTO (3 mol-%) using H O (2 equiv.; 30% in water) at
19]
2
2
room temperature (Table 1, Entry 10). However, vigorous
stirring or shaking of the biphasic reaction mixture is essen-
tial to obtain high yields of the corresponding epoxide and
reproducible conversions. Following our previous study of
oxidation reactions, a selection of different N-ligands sum-
[
20]
marized in Table 1 was added to the model reaction.
In
all cases, high chemoselectivity (Ͼ90% of epoxide) was ob-
tained regardless of the ligand chosen. Regarding the reac-
tivity, some of the ligands showed no influence on the reac-
tion (Table 1, Entries 5–9), some slowed down the reaction
(Table 1, Entries 11–13), and a few of the tested additives
increased the activity (Table 1, Entries 1–4). Among the dif-
ferent tested ligands, (R,R)-1,3-benzenebis(4-phenyl-4,5-di-
hydro-2-oxazole) (1a) showed the highest chemoselectivity
(Ͼ99%) and conversions after 2 and 4 h (62 and 76%,
respectively; Table 1, Entry 1). Therefore, other oxazoline
derivatives were tested and the reactivity was determined.
A popular class of oxazoline compounds are the so-called
pyridinebis(oxazoline) (pybox) ligands, which are commer-
cially available and have been intensively investigated by our
[
21,22] 1
group.
H NMR spectroscopy measurements of the in
situ formed MTO complexes of selected different oxazoline
and pybox ligands 1a–4a (Figure 1) were realized to esti-
mate their reactivity towards 1-octene (Table 2). Interest-
ingly, the magnitude of the shift of the Re–CH proton sig-
3
nal is directly related to the electron character of the li-
[
23]
gand. The proton signal from the Re–CH group of non-
3
coordinated MTO is observed at δ = 2.64 ppm. After com-
plexation of ligands 1a–4a, signals close to the initial methyl
shift of free MTO were measured to reveal only a weak
coordination of ligands to the rhenium center. Nevertheless,
slight differences have been detected that indicate a grada-
tion of activity and selectivity for the MTO adducts. In the
case of complex 1b bearing a phenyl ring instead of pyr-
idine, the weakest shift was observed of all the studied ad-
ducts followed by the pybox adduct 2b.
[
%
a] Reaction conditions: 1 mmol olefin, 3 mol-% of MTO, 12 mol-
of ligand, 2 mL of CH Cl , 100 μL of dodecane (GC internal
standard), and 2 equiv. of H (30%) were added at room tem-
perature in air. [b] Conversion was determined by GC analysis by
2
2
Of the four selected compounds presented in Table 2,
complexes 1b and 2b display the weakest shift of the Re–
2
O
2
CH proton signal, which implies that both are the least comparison with authentic samples. [c] Selectivity refers to the
3
chemoselectivity of epoxide from olefin. No different selectivity was
determined after 2 and 4 h.
stable and catalytically most active complexes. Both as-
sumptions turned out to be correct. As expected, these
MTO complexes 1b and 2b showed the best catalytic per-
formance affording Ͼ96 and 82% yields, respectively,
within 19 h for the epoxidation of 1-octene with hydrogen
peroxide (Figure 2). Compounds 3b and 4b showed lower
catalytic efficiency with yields of up to 62% after 19 h for by a reduced catalytic activity. So, the expected behavior of
the epoxidation of 1-octene. Complex 4b displayed the compounds 3b and 4b (most stable and catalytically least
strongest chemical shift of the proton signal of the Re–CH3 active) was confirmed, as reflected by the NMR spectro-
group, which is associated with a higher stability followed scopic data.
Eur. J. Inorg. Chem. 2012, 5972–5978
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5973

M. Beller et al.
FULL PAPER
selectivity (41% ee) for any MTO-catalyzed epoxidation
was reported by Herrmann et al. using chiral diols derived
[
25a]
from (+)-tartaric acid.
workers reported an enantiomeric excess of 36% using an
In addition, Corma and co-
[
23a]
MTO/(R)-1-phenylethylamine catalyst system.
Unfortu-
nately, in both cases the conversion was rather poor, which
was mainly due to the low temperature that had to be used.
Hence, the further development of enantioselective MTO
catalysts is desirable.
While no asymmetric induction could be observed in the
epoxidation of 1-octene, we also performed catalytic investi-
gations using trans-stilbene, which is considered to be a
Figure 1. Tested ligands 1a–4a.
good model substrate for asymmetric epoxidations.[
20d]
By
applying combinations of MTO/1a and MTO/4a good reac-
tivity but only racemic products were obtained (Table 3, En-
tries 1, 2). However, the combination of MTO/2a and
MTO/3a showed some chiral induction (Table 3, Entries 3,
1
Table 2. Selected H NMR spectroscopic data of MTO complexes
in CDCl .
3
4). In the case of 2a, excellent catalytic performance was
observed at room temperature giving a conversion of 88%
and Ͼ99% chemoselectivity, and the ee of the product was
18%. Variation of the reaction parameters led to optimized
reaction conditions (3 mol-% of MTO catalyst, 12 mol-%
of ligand, 2 equiv. of H O (30%), 2 mL of CH Cl , room
Entry
Compound
3
δ(Re–CH ) [ppm]
2
2
2
2
1
2
3
4
5
MTO
1b
2.64
2.62
2.59
2.51
2.49
temp.) as summarized in Table 3. Running the reaction at
lower temperature did not increase the ee but resulted in a
strong reduction of the yield (Table 3, Entry 10). Thus, all
catalytic experiments were carried out at room temperature.
Interestingly, the order of addition of the reaction compo-
nents had an influence on the enantioselectivity. Under op-
2b
3b
4b
Table 3. Oxidation of trans-stilbene to stilbene oxide.[a]
Entry Ligand
H
2
O
2
T
Conversion Yield Selectivity ee
[b]
[b]
[c]
[d]
[
equiv.] [°C]
[%]
[%]
[%]
[%]
1
2
3
4
1a
4a
2a
3a
2a
2a
2a
2a
2a
2a
2a
2a
2a
2
2
2
2
2
1
3
8
2
2
2
2
2
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
0
Ͼ99
81
88
13
39
55
86
96
60
2
Ͼ99
73
88
13
29
50
83
93
60
2
Ͼ99
89
Ͼ99
Ͼ99
75
92
96
96
Ͼ99
Ͼ99
Ͼ99
94
rac
rac
18
10
12
11
9
7
6
19
15
7
[
e]
5
6
7
8
9
Figure 2. Yield of the catalytic epoxidation of 1-octene after 2, 4,
and 19 h using different complexes 1b–4b.
[
f]
1
0
Oxidation of trans-Stilbene with Chiral Oxazoline and
Pybox Ligands
1
1
10
30
r.t.
36
95
98
36
89
95
1
13
2
[
g]
Ͼ99
8
Owing to the increased reactivity and improved chemose-
lectivity of some of the ligands in the epoxidation of 1-
octene, we were interested in the chiral induction of ligands
[
1
(
a] Reaction conditions: 1 mmol of olefin, 3 mol-% of MTO,
2 mol-% of ligand, CH
GC internal standard), and 2 equiv. of H
2
Cl
2
, 2 mL of CH
2
Cl
2
, 100 μL of dodecane
2
O
2
(30% in water) were
1
a–4a, too. Clearly, asymmetric epoxidation of olefins is of added at room temperature in air, and the mixture was stirred for
interest for the synthesis of chiral intermediates in the phar- 19 h. [b] Conversion and yield were determined by GC analysis
maceutical and agrochemical industries.[
24]
by comparison with authentic samples. [c] Selectivity refers to the
chemoselectivity of epoxide from olefin. [d] Ligands 2a and 3a give
(
To date, only
few publications describe the enantioselective MTO-cata-
2R,3R) enantiomers. [e] Reaction was run in toluene (2 mL). [f]
equiv. of urea/hydrogen peroxide (UHP). [g] Opposite order of
lyzed epoxidation of olefins, and no general applicable syn-
2
thetic protocol exists.[
23a,25]
2 2
So far, the highest enantio- addition: olefin was added after H O .
5974
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 5972–5978

Catalytic Epoxidations
Table 4. Influence of different ligands on the epoxidation of trans-
stilbene.
Table 4. (continued).
[
a]
[
1
a] Reaction conditions: 1 mmol of olefin, 3 mol-% of MTO,
2 mol-% of ligand, 2 mL of CH
2
Cl
O
2
, 100 μL of dodecane (GC
(30%) were added at room
internal standard), and 2 equiv. of H
2
2
temperature in air, and the mixture was stirred for 19 h. [b] Conver-
sion and yield were determined by GC analysis by comparison with
authentic samples. [c] Selectivity refers to the chemoselectivity of
epoxide from olefin.
timized conditions, the olefin, MTO, and ligand were added
first, and then the reaction was started by the addition of
hydrogen peroxide; this led to high yields and moderate
enantioselectivity. In the reaction protocols reported by
[
23a]
[25b]
[25c]
Corma,
Kühn,
and Burke,
MTO, chiral ligand,
and hydrogen peroxide were mixed, which caused a change
of color, followed by the addition of olefin. By applying this
second procedure to our catalyst systems, high conversion
was achieved (98%), while the ee was lower (Table 3, En-
try 13).
By using the above-described procedure, different pybox
ligands were tested next. Additionally, (–)-(S)-1-phenyleth-
ylamine was applied, which has been used previously in the
[
23a]
literature.
Although the latter ligand gave 17% ee of the
product, the conversion and chemoselectivity decreased sig-
nificantly (Table 4, Entry 1). In the case of ligand 2 both
[(R) and (S)] enantiomers were tested and gave the opposite
enantiomeric excess with similar ee values (Table 4, En-
tries 2, 3). Furthermore, other pybox ligands with different
substituents in the 4- or 5-position of the oxazoline moiety
were screened. Although a number of these ligands gave
good conversions and selectivity, no further improvement
of enantioselectivity was achieved (Table 4, Entries 4–7). In
the case of ligands 3a, 9a, and 10a (Table 4, Entries 8–10)
the conversion was also low. Nevertheless, the influence of
substituents on the pyridine ring was investigated, too
(Table 4, Entry 11). However, only a racemic mixture of the
corresponding epoxide was obtained. Ligand 11a was syn-
[
21]
thesized starting from 12a, which was also tested for this
Eur. J. Inorg. Chem. 2012, 5972–5978
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5975

M. Beller et al.
FULL PAPER
Table 5. Epoxidation of different aromatic olefins with MTO and ligands 2a or 12a.[a]
[a] Reaction conditions: 1 mmol of olefin, 3 mol-% of MTO, 12 mol-% of ligand, 2 mL of CH
2
Cl
2
, 100 μL of dodecane (GC internal
standard), and 2 equiv. of H O (30%) were added at room temperature in air, and the mixture was stirred for 19 h. [b] Conversion and
2
2
yield were determined by GC analysis by comparison with authentic samples. [c] Selectivity refers to the chemoselectivity of epoxide from
olefin. [d] Absolute configuration not determined.
reaction. Surprisingly, ligand 12a showed very good conver- as shown in Table 5, they gave only low but reproducible
sion and selectivity (both as 95%) as well as 19% ee enantioselectivities. For example, 1-phenylcyclohexene and
(Table 4, Entry 12). Therefore, precursor 13a of the efficient β-methylstyrene gave 11% ee (Table 5, Entries 3, 4, and 11).
ligand 2a was used too, but this ligand showed no chiral
effect (Table 4, Entry 13).
Finally, we tested ligands 2a and 12a in the epoxidation
of terminal and di- and trisubstituted aromatic olefins. By
using styrene in the presence of 2a, an excellent yield and
Conclusion
We studied the influence of different pyridinebis(oxa-
chemoselectivity was observed considering the sensitivity of zoline) and related N-ligands in the MTO-catalyzed epoxid-
the product. Unfortunately, both ligands produced only a ation of 1-octene and stilbene. By applying optimized con-
racemic mixture of styrene epoxide (Table 5, Entries 2 and ditions a variety of aromatic olefins were oxidized in good
10). Most of the other substrates also led to high yields and yields and chemoselectivities. However, the obtained
chemoselectivity of the corresponding epoxides. However, enantioselectivities (up to 19%) remained too low to be of
5976
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 5972–5978

Catalytic Epoxidations
synthetic interest. NMR spectroscopic investigations of the F. E. K. thanks the Bavarian State Ministry for Economy, Infra-
structure, Traffic and Technology (project no. IBF-3665g/899/2-
NW-0806-0002) for project funding.
MTO–oxazoline complexes showed a correlation between
the shift of the Re–CH signal and the catalyst perform-
3
ance.
[
1] For reviews on metal-catalyzed epoxidation and commentaries,
see: a) K. A. Jørgensen, Chem. Rev. 1989, 89, 431–458; b) G.
Grigoropoulou, J. H. Clark, J. A. Elings, Green Chem. 2003, 5,
Experimental Section
1
–7; c) B. S. Lane, K. Burgess, Chem. Rev. 2003, 103, 2457–
473; d) M. Beller, Adv. Synth. Catal. 2004, 346, 107–108.
2
General Remarks: All solvents and chemicals were obtained com-
[
2] F. Shi, M. K. Tse, H. M. Kaiser, M. Beller, Adv. Synth. Catal.
007, 349, 2425–2430.
mercially and were used as received. “30%” aqueous H
urea/hydrogen peroxide (UHP) from Merck were used as received.
The peroxide content of H varied from 30 to 40% as deter-
mined by titration. NMR spectra were measured using a Bruker
ARX 300 spectrometer at 400 MHz ( H). All spectra were recorded
in CDCl , and chemical shifts (δ) are reported in ppm relative to
3
tetramethylsilane referenced to the residual solvent peaks. Spectra
were measured at room temperature unless stated otherwise.
2 2
O and
2
[
3] For recent work on Ru-based epoxidations, see: a) I. W. C. E.
Arends, T. Kodama, R. A. Sheldon, in Topics in Organometallic
Chemistry (Eds.: C. Bruneau, P. H. Dixneuf), Springer-Verlag,
Berlin, Heidelberg, 2004, pp. 277–320; b) M. K. Tse, C. Döbler,
S. Bhor, M. Klawonn, W. Mägerlein, H. Hugl, M. Beller, An-
gew. Chem. 2004, 116, 5367–5372; Angew. Chem. Int. Ed. 2004,
2
O
2
1
4
3, 5255–5260; c) M. K. Tse, M. Klawonn, S. Bhor, C. Döbler,
G. Anilkumar, H. Hugl, W. Mägerlein, M. Beller, Org. Lett.
005, 7, 987–990; d) S. Bhor, G. Anilkumar, M. K. Tse, M.
1
Ligand 1b: H NMR (400.1 MHz, CDCl
3
): δ = 2.62 (s, 3 H, Re–
2
CH
3
), 4.2 (dd, 2 H), 4.43 (dd, 2 H), 5.35 (dd, 2 H), 7.27–7.4 (m,
Klawonn, C. Döbler, B. Bitterlich, A. Grotevendt, M. Beller,
Org. Lett. 2005, 7, 3393–3396; e) D. Chatterjee, Coord. Chem.
Rev. 2008, 176–198.
10 H), 7.45 (t, 1 H), 8.06 (dd, 2 H), 8.49 (t, 1 H) ppm.
1
Ligand 2b: H NMR (400.1 MHz, CDCl
3
): δ = 2.59 (s, 3 H, Re–
[
4] a) A. Murphy, G. Dubois, T. D. P. Stack, J. Am. Chem. Soc.
CH
3
), 4.42 (dd, 2 H), 4.93 (dd, 2 H), 5.46 (dd, 2 H), 7.26–7.36 (m,
2
003, 125, 5250–5251; b) K. Muniz-Fernandez, C. Bolm, in
10 H), 7.91 (t, 1 H), 8.34 (dd, 2 H) ppm.
Transition Metals for Organic Synthesis 2nd ed. (Eds.: M.
Beller, C. Bolm), Wiley-VCH, Weinheim, 2004, pp. 344–356; c)
A. Murphy, A. Pace, T. D. P. Stack, Org. Lett. 2004, 6, 3119–
1
Ligand 3b: H NMR (400.1 MHz, CDCl
CH ), 4.35 (dd, 2 H), 4.83 (dd, 2 H), 5.55 (dd, 2 H), 7.05–7.15 (m,
3
3
): δ = 2.51 (s, 3 H, Re–
3
122; d) E. M. McGarrigle, D. G. Gilheany, Chem. Rev. 2005,
4
H), 7.25–7.4 (m, 4 H), 7.9 (t, 1 H), 8.3 (dd, 2 H) ppm.
105, 1563–1602; e) B. Kang, M. Kim, J. Lee, Y. Do, S. Chang,
1
Ligand 4b: H NMR (400.1 MHz, CDCl
3
): δ = 2.49 (s, 3 H, Re–
J. Org. Chem. 2006, 71, 6721–6727; f) I. Garcia-Bosch, A.
Company, X. Fontrodona, X. Ribas, M. Costas, Org. Lett.
3
CH ), 4.15 (dd, 2 H), 4.5 (dd, 2 H), 5. 6 (dd, 2 H), 7.36–7.42 (m,
2008, 10, 2095–2098.
10 H), 7.93 (t, 1 H), 8.3 (dd, 2 H) ppm.
[
5] For reviews on iron-based catalysts, see: a) B. S. Lane, K. Bur-
gess, Chem. Rev. 2003, 103, 2457–2473; b) C. Bolm, J. Legros,
J. Le Paih, L. Zani, Chem. Rev. 2004, 104, 6217–6254; c) M.
Costas, M. P. Mehn, M. P. Jensen, L. Que, Jr., Chem. Rev.
2004, 104, 939–986; d) E. B. Bauer, Curr. Org. Chem. 2008, 12,
General Procedure for the Epoxidation of Olefins with H
3 mol-%), ligand (12 mol-%), olefin (1 mmol), and CH
2
O
2
: MTO
(
2
Cl
2
(2 mL)
were added to a 50 mL round-bottomed flask at room temperature.
The mixture was stirred for a few minutes, and than dodecane (GC
internal standard, 100 μL) was added. The reaction was directly
1
341–1369; e) K. Schröder, K. Junge, B. Bitterlich, M. Beller,
Top. Organomet. Chem. 2011, 33, 83–109; f) K. Junge, K.
Schröder, M. Beller, Chem. Commun. 2011, 47, 4849–4859; for
recent iron-catalyzed oxidations, see: g) M. R. Bukowski, P.
Comba, A. Lienke, C. Limberg, C. L. de Laorden, R. Mas-
Ballesté, M. Merz, L. Que, Jr., Angew. Chem. 2006, 118, 3524–
2 2
started by adding 30% H O (2 equiv.), and the mixture was stirred
vigorously in air for 19 h. The conversion and yield were deter-
mined by GC analysis without further manipulations and were
compared with authentic samples. The yield was determined by GC
(30 m HP 5 Agilent Technologies 50–300 °C) based on the internal
3528; Angew. Chem. Int. Ed. 2006, 45, 3446–3449; h) S. Taktak,
standard (calibration curve) and the enantioselectivity (ee values)
was determined by chiral HPLC: trans-stilbene: Reposil 100; elu-
ent: n-hexane/ethanol (99:1); flow: 1.0 mLmin ; styrene: Chi-
ralPAK AD-H; eluent: n-hexane/2-propanol (99.95:0.05); flow:
W. Ye, A. M. Herrera, E. V. Rybak-Akimova, Inorg. Chem.
2007, 46, 2929–2942; i) A. Company, L. Gmez, M. Gell, X.
Ribas, J. M. Luis, L. Que, Jr., M. Costas, J. Am. Chem. Soc.
–
1
2
007, 129, 15766–15767; j) M. S. Chen, M. C. White, Science
2007, 318, 783–787; k) M. S. Chen, M. C. White, Science 2010,
27, 566–571; l) M. Wu, C. Miao, S. Wong, H. Xue, C. Xia,
–1
1.0 mLmin ; 1-phenylcyclohexene: ChiralPAK AD-H; eluent: n-
3
–
1
hexane/2-propanol (99.95:0.05); flow: 1.0 mLmin ; β-methylstyr-
ene: Chiralcel OD-H; eluent: n-hexane/ethanol (99.95:0.05); flow:
F. E. Kühn, W. Son, Adv. Synth. Catal. 2011, 353, 3014–3022;
m) B. Join, K. Möller, C. Ziebart, K. Schröder, D. Gördes, K.
Thurow, A. Spannenberg, K. Junge, M. Beller, Adv. Synth. Ca-
tal. 2011, 353, 3023–3030.
–1
1.0 mLmin ; p-chlorostyrene: ChiralPAK AD-H; eluent: n-hept-
–1
ane/ethanol (98:2); flow: 0.5 mLmin ; p-bromostyrene: Chi-
ralPAK AD-H; eluent: n-heptane/ethanol (98:2); flow:
[6] a) W. A. Herrmann, W. Wagner, U. N. Flessner, U. Volkhardt,
H. Komber, Angew. Chem. 1991, 103, 1704–1706; Angew.
Chem. Int. Ed. Engl. 1991, 30, 1636–1638; b) W. A. Herrmann,
R. W. Fischer, D. W. Marz, Angew. Chem. 1991, 103, 1706–
1709; Angew. Chem. Int. Ed. Engl. 1991, 30, 1638–1641; c)
W. A. Herrmann, M. Wang, Angew. Chem. 1991, 103, 1709–
–1
0.5 mLmin ; (E)-2-(4-butylstyryl)naphthalene: Reposil 100; elu-
–1
ent: n-heptane/ethanol (98:2); flow: 1.0 mLmin ; (E)-1,2-bis(4-bu-
tylphenyl)ethene: Reposil 100; eluent: n-heptane/ethanol (98:2);
flow: 1.0 mLmin ).
–1
1711; Angew. Chem. Int. Ed. Engl. 1991, 30, 1641–1643; d) F. E.
Kühn, A. M. Santos, P. W. Roesky, E. Herdtweck, W. Scherer,
P. Gisdakis, I. V. Yudanov, C. Di Valentin, N. Rösch, Chem.
Eur. J. 1999, 5, 3603–3615; e) F. E. Kühn, A. Scherbaum, W. A.
Herrmann, J. Organomet. Chem. 2004, 689, 4149–4164; f) G.
Soldaini, Synlett 2004, 1849–1850; g) F. E. Kühn, A. M. San-
tos, W. A. Herrmann, Dalton Trans. 2005, 2483–2491; h) F. E.
Kühn, J. Zhao, W. A. Herrmann, Tetrahedron: Asymmetry
2005, 16, 3469; i) M. Zhou, J. Zhao, J. Li, S. Yue, C. Bao, J.
Acknowledgments
K. K. thanks Dr. D. Michalik for the NMR spectroscopy measure-
ments and is grateful to Dr. B. Join and Dr. K. Schröder for helpful
discussions. The authors thank Dr. C. Fischer, S. Buchholz, S.
Schareina, A. Koch, and K. Fiedler (all at the Leibniz-Institut für
Katalyse e.V.) for excellent analytical and technical support.
Eur. J. Inorg. Chem. 2012, 5972–5978
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5977

M. Beller et al.
FULL PAPER
Mink, S. Zang, F. E. Kühn, Chem. Eur. J. 2007, 13, 158–166;
j) A. Schreckeneder, P. Traar, G. Raber, J. Baumgartner, F. Be-
laj, N. C. Mösch-Zanetti, Inorg. Chem. 2009, 48, 11608–11614.
[15] D. Steinborn (Ed.), Grundlagen der metallorganische Kom-
plexkatalyse, Teubner, Wiesbaden, 2007.
[16] H.-J. Arpe (Ed.), Industrielle Organische Chemie, 6th ed.,
Wiley-VCH, Weinheim, 2007.
[
7] For reviews on rhenium-based catalysts, see: a) C. C. Romão,
F. E. Kühn, W. A. Herrmann, Chem. Rev. 1997, 97, 3197–3246;
b) W. A. Herrmann, F. E. Kühn, Acc. Chem. Res. 1997, 30,
[
17] a) A. K. Yudin (Ed.), Aziridines and Epoxides in Organic Syn-
thesis Wiley-VCH, Weinheim, 2006; b) H. Adolfsson in Modern
Oxidation Methods (Ed.: J. E. Bäckvall), Wiley-VCH,
Weinheim, 2011, pp. 37–84.
1
69–180; c) D. Betz, P. Altmann, M. Cokoja, W. A. Herrmann,
F. E. Kühn, Coord. Chem. Rev. 2011, 255, 1518–1540.
[
8] A. M. Al-Ajlouni, J. H. Espenson, J. Am. Chem. Soc. 1995,
[
18] For recent publications on MTO epoxidation, see: a) S. Yama-
zaki, Org. Biomol. Chem. 2010, 8, 2377–2385; b) S. A. Hauser,
V. Korinth, E. Herdtweck, M. Cokoja, W. A. Herrmann, F. E.
Kühn, Eur. J. Inorg. Chem. 2010, 4083–4090; c) A. Di Giu-
seppe, M. Crucianelli, M. Passacantando, S. Nisi, R. Saladino,
J. Catal. 2010, 276, 412–422; d) Y. Gao, Y. Zhang, C. Qiu, J.
Zhao, Appl. Organomet. Chem. 2011, 25, 54–60; e) R. Yang, Y.
Zhang, J. Zhao, Catal. Commun. 2011, 12, 923–926; f) P.
Altmann, M. Cokoja, F. E. Kühn, J. Organomet. Chem. 2012,
1
17, 9243–9250.
[
9] a) W. A. Herrmann, A. M. J. Rost, J. K. M. Mitterpleininger,
N. Szesni, W. Sturm, R. W. Fischer, F. E. Kühn, Angew. Chem.
2
007, 119, 7440–7442; Angew. Chem. Int. Ed. 2007, 46, 7301–
7
303; b) E. Tosh, H. K. M. Mitterpleininger, A. M. J. Rost, D.
Veljanovski, W. A. Herrmann, F. E. Kühn, Green Chem. 2007,
9
, 1296–12981; c) A. Capapé, M.-D. Zhou, S.-L. Zang, F. E.
Kühn, J. Organomet. Chem. 2008, 693, 3240–3244.
[
10] For examples of heterogeneous MTO-catalyzed epoxidations,
see: a) M. C. A. van Vliet, I. W. C. E. Arends, R. A. Sheldon,
Chem. Commun. 1999, 821–822; b) J. Iskara, D. Bonnet-
Delpon, J. P. Begue, Tetrahedron Lett. 2002, 43, 1001–1003; c)
R. Buffon, U. Schuchardt, J. Braz, Chem. Soc. 2003, 14, 347;
d) R. Saladino, A. A. Andrechi, V. Neri, C. Crestini, Tetrahe-
dron 2005, 61, 1069–1075; e) E. Da Palma Carreiro, G. Yong-
En, A. J. Burke, J. Mol. Catal. A 2005, 235, 285–292; f) L. M.
Gonzalez, A. L. Vila, C. Montes, G. Gelbard, React. Funct.
Polym. 2005, 65, 169–181; g) D. Ogrin, A. R. Barron, J. Mol.
Catal. A 2006, 244, 267–270; h) S. Gago, J. A. Fernandes, M.
Abrantes, F. E. Kühn, P. Ribeiro-Claro, M. Pillinger, T. M.
Santos, I. S. Goncalves, Microporous Mesoporous Mater. 2006,
701, 51–55; g) T. Michelle, M. Cokoja, V. Sieber, F. E. Kühn,
J. Mol. Catal. A 2012, 358, 159–165; h) M. Carril, P. Altmann,
W. Bonrath, T. Netscher, J. Schütz, F. E. Kühn, Catal. Sci.
Technol. 2012, 2, 722–724; i) P. Altmann, M. Cokoja, F. E.
Kühn, Eur. J. Inorg. Chem. 2012, 3235–3239.
[19] W. A. Herrmann, H. Ding, R. M. Kratzer, F. E. Kühn, J. J.
Haider, R. W. Fischer, J. Organomet. Chem. 1997, 549, 319–
322.
[20]
a) K. Möller, G. Wienhöfer, K. Schröder, B. Join, K. Junge, M.
Beller, Chem. Eur. J. 2010, 16, 10300–10303; b) K. Schröder, S.
Enthaler, B. Join, K. Junge, M. Beller, Adv. Synth. Catal. 2010,
352, 1771–1778; c) K. Schröder, K. Junge, A. Spannenberg, M.
8
9, 284–290; i) K. R. Jain, F. E. Kühn, J. Organomet. Chem.
Beller, Catal. Today 2010, 157, 364–370; d) K. Schröder, B.
Join, A. J. Amali, K. Junge, X. Ribas, M. Costas, M. Beller,
Angew. Chem. 2011, 123, 1461–1465; Angew. Chem. Int. Ed.
2
007, 692, 5532–5540; j) K. R. Jain, W. A. Herrmann, F. E.
Kühn, Coord. Chem. Rev. 2008, 252, 556–568.
[
11] a) J. Rudolph, K. L. Reddy, J. P. Chiang, K. B. Sharpless, J.
Am. Chem. Soc. 1997, 119, 6189–6190; b) C. Coperet, H. Ad-
olfsson, B. K. Sharpless, Chem. Commun. 1997, 1565–1566; c)
W. A. Herrmann, R. M. Kratzer, H. Ding, R. W. Thiel, H.
Glas, J. Organomet. Chem. 1998, 555, 293–295; d) H. Adolfs-
son, A. Converso, B. K. Sharpless, Tetrahedron Lett. 1999, 40,
2
011, 50, 1425–1429.
[
21] M. K. Tse, S. Bhor, M. Klawonn, G. Anilkumar, H. Jiao, C.
Döbler, A. Spannenberg, W. Mägerlein, H. Hugl, M. Beller,
Chem. Eur. J. 2006, 12, 1855–1874.
[
[
22] M. K. Tse, S. Bhor, M. Klawonn, C. Döbler, M. Beller, Tetrahe-
dron Lett. 2003, 44, 7479–7483.
3991–3994; e) H. Adolfsson, C. Coperent, J. P. Chiang, A. K.
23] a) M. J. Sabater, M. E. Domine, A. Corma, J. Catal. 2002, 210,
Yudin, J. Org. Chem. 2000, 65, 8651–8658; f) S. Yamazaki, Org.
Biomol. Chem. 2007, 5, 2109–2113; g) S. Yamazaki, Tetrahe-
dron 2008, 64, 9253–9257; h) M. D. Zhou, Y. Yu, A. Capapé,
K. R. Jain, E. Herdtweck, X. R. Li, J. Li, S. L. Zhang, F. E.
Kühn, Chem. Asian J. 2009, 4, 411–418; i) P. Altmann, F. E.
Kühn, J. Organomet. Chem. 2009, 694, 4032–4035; j) M. D.
Zhou, K. R. Jain, A. Günyar, P. N. W. Baxter, E. Herdtweck,
F. E. Kühn, Eur. J. Inorg. Chem. 2009, 2907–2914.
192–197; b) C.-J. Qiu, Y.-C. Zhang, Y. Gao, J.-Q. Zhao, J. Or-
ganomet. Chem. 2009, 694, 3418–3424.
24] R. A. Sheldon, in Applied Homogenous Catalysis with Organo-
metallic Compounds (Eds.: B. Cornils, W. A. Herrmann), vol.
[
[
1, Wiley-VCH, 2002, pp. 412–426.
25] a) C. E. Tucker, K. G. Davenport, US 5618958 1997; b) J. J.
Haider, R. M. Kratzer, W. A. Hermann, J. Zhao, F. E. Kühn,
J. Organomet. Chem. 2004, 689, 3735–3740; c) E.
Da Palma Carreiro, G. Yong-En, A. J. Burke, J. Mol. Catal. A
[
[
[
12] G. Strukul, Catalytic Oxidations with Hydrogen Peroxide as
Oxidant, Kluwer Academic Publishers, Dordrecht, 1992.
13] M. Inoue, E. Nakayama, Y. Nakamura, Bull. Chem. Soc. Jpn.
2
005, 235, 285–292; d) F. W. Y. Zhang, W. Ran, J. Zhao, J. Mol.
Catal. (China) 2010, 24, 240–246.
1991, 64, 3442.
Received: July 3, 2012
14] S. T. Oyama (Ed.), Mechanisms in Homogeneous and Hetero-
geneous Epoxidation Catalysis, Elsevier, Amsterdam, 2008.
Published Online: November 6, 2012
5978
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 5972–5978