Asymmetric Epoxidation of Olefins with H2O2 Catalyzed by a Bioinspired Aminopyridine N4 Iron Complex

Article abstract of DOI:10.1002/cctc.201601293

An iron complex with a chiral aminopyridine N4 ligand bearing strong electron-donating and bulky morpholine groups on the ligand is synthesized and characterized. The iron complex serves to efficiently catalyze the asymmetric epoxidation of various olefins by employing aqueous hydrogen peroxide as the green oxidant, providing the corresponding epoxides in good to excellent yields and enantioselectivities (up to 93 % yield and 99.9 % ee). Owing to the introduction of morpholine functional groups on the ligand, the Fe-catalyzed reaction can proceed with a catalytic amount of the carboxylic acid partner (3 mol %).

Full text of DOI:10.1002/cctc.201601293

Accepted Article
Title: Asymmetric Epoxidation of Olefins with H2O2 Catalyzed by a
Bioinspired Aminopyridine N4 Iron Complex
Authors: Wei Sun, Wenfang Wang, Qiangsheng Sun, Daqian Xu, and
Chungu Xia
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10.1002/cctc.201601293
ChemCatChem
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Asymmetric Epoxidation of Olefins with H2O2 Catalyzed by a
Bioinspired Aminopyridine N4 Iron Complex
Wenfang Wang,[a][b] Qiangsheng Sun,[a] Daqian Xu,[a] Chungu Xia,[a] and Wei Sun*[a]
Abstract: An iron complex with chiral aminopyridine N4 ligand
bearing strong electron-donating and bulky morpholine groups on
the ligand is synthesized and characterized. The iron complex
serves to efficiently catalyze the asymmetric epoxidation of various
olefins by employing aqueous hydrogen peroxide as the green
oxidant, providing the corresponding epoxides in good to excellent
yields and enantioselectivities (up to 93% yield, and 99.9% ee). Due
to the introduction of morpholine functional groups on the ligand, the
Fe-catalyzed reaction can proceed in the catalytic amount of the
carboxylic acid partner (3 mol%).
(N,N′-dimethyl-N,N′-bis(phenyl-2-pyridinylmethyl)-cyclohexane-
1,2-di-amine) or (S)-PEB ((S)-1-(1-ethyl-1H-benzo[d]imidazol-2-
yl)-N-((1-((1-ethyl-1H-benzo[d]imidazole-2-yl)methyl)pyrrolidin-2-
yl)methyl)-N-methylmethanamine) as catalyst.[26,27] Later, Talsi,
Bryliakov and co-workers not only described the catalyst system
[((S,S)-PDP)Fe(OTf)2]/H2O2/carboxylic acid (PDP = N,N′-bis(2-
pyridylmethyl)-2,2’-bipyrrolidine) for the asymmetric epoxidation
of alkenes, but also indicated that the steric hindrance of the
carboxylic acid could tune the reaction enantioselectivity.[28]
Introduction
Catalytic asymmetric epoxidation of olefins has been widely
recognized as a powerful tool in synthetic chemistry due to the
generating of chiral epoxides, which are versatile synthons for
the construction of natural products and pharmaceutical
molecules.[1-5] Thus, numerous efforts have been devoted to
achieving efficient catalysts, and a number of chiral metal
complexes and organocatalysts have been developed
successfully for the enantioselective epoxidation of a variety of
alkenes.[6-9] Despite enormous progress in the field, it is of great
importance to explore practical asymmetric epoxidation using
environmentally friendly catalysts and oxidants from the
viewpoint of green chemistry. In this context, the development of
iron catalysts with considerable activity is highly desirable, since
iron is nontoxic, cheap and abundant on the earth.[10] In 1983,
Groves reported the first asymmetric epoxidation using iron
porphyrin complex.[11] Encouraged by this result, a growing
number of iron-based complexes were applied to asymmetric
epoxidation of olefins.[12-17] Especially, Fe complexes with
polydentate N-donor ligands (e.g., aminopyridine-based N4
ligand) were used as the models of natural nonheme
oxygenases, capable of catalyzing various selective oxygenation
reactions with environmentally friendly H2O2.[18-24] In 2001,
Jacobsen and co-workers reported that iron(II)-MEP complex
Scheme 1. Asymmetric epoxidation catalyzed by aminopyridine N4 iron
complexes.
Although considerable advancements have been achieved in
the iron-catalyzed asymmetric epoxidation via tuning of the
corresponding chiral polydentate N-donor ligands, still the
development of efficient catalysts with broad substrate scope
and high activity represents an important challenge. After above
approaches, Costas and co-workers reported an elegant
example that involves a derived iron(II)-PDP complex bearing
strongly electon donating NMe2 groups at pyridine rings of the
ligand, demonstrating improved substrate scope including
simple alkenes (e.g., cis-β-methylstyrene, α-methyl styrenes)
and stereocontrol (Scheme 1).[29,30] In a recent report, the same
group presented that iron catalyst containing an electron-
donating pyridine substituted by bulky triisopropyl silane and a
benzimidazole ring could convert cyclic aliphatic enones into the
(MEP
=
N,N’-dimethyl-N,N’-bis(2-pyridylmethyl)ethylene-1,2-
diamine) could efficiently catalyze epoxidation of a variety of
aliphatic olefins.[25] Inspired by this poineering work, we firstly
reported the enantioselective epoxidation of α,β-enones with up
to 99% ee, using nonheme iron complex with (R,R)-P-MCP
[a]
W. Wang, Dr. Q. Sun, D. Xu, Prof. Dr. C. Xia, and Prof. Dr. W. Sun
State Key Laboratory for Oxo Synthesis and Selective Oxidation,
and Suzhou Research Institute of LICP, Lanzhou Institute of
Chemical Physics (LICP)
corresponding epoxides with
enantioselectivities (Scheme
excellent yields and
1).[31]
Several important
Chinese Academy of Sciences
Lanzhou 730000, China
E-mail: wsun@licp.cas.cn.
University of Chinese Academy of Sciences
Beijing 100049, China
implications can be drawn from these studies: (1) the carboxylic
moiety is directly involved in the active iron species; (2) the
reactivity and enantioselectivity of the iron catalyst can be
manipulated by electronic and steric properties of the chiral
ligands. Taken together, the development of iron complex
[b]
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10.1002/cctc.201601293
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bearing chiral aminopyridine N4 ligand that possessed strong
donating and bulky groups at pyridine rings was reasonable and
feasible. Continuing our interest in the development of non-
heme metal complexes for the oxidations,[26,32-36] herein we
describe the preparation, reactivity of an iron complex supported
by a new aminopyridine ligand where the electronic and steric
properties can be tuned by the introduction of morpholine group
on the ligand.
enantioselectivity of epoxidation.[28,40] Thus, we used EHA as the
additive firstly and 81% yield and 90% ee were obtained (Table
1, entry 1). Bulky 1-adamantane carboxylic acid (ACA) was also
tried in the reaction and no better results were observed (Table
1, entry 6).[41] On the other hand, Costas and co-workers
demonstrated that chiral acid (e. g. amino acids) has the ability
to efficiently promote the iron-catalyzed epoxidation reactions by
H2O2.[29,30] Therefore, we also investigated a serial of chiral acids
to identify the best additive for this epoxidation catalyzed by C1
(Table 1, entries 7-9). As shown in Table 1, 3 mol% D-(+)-
camphoric acid (D-CPA) was the best additive to produce the
desired product with excellent yield (93%) and enantioselectivity
(90%).[34] Very recently, we have found that catalytic amount of
H2SO4 can promote the Mn-catalyzed epoxidation of olefins.[42]
In this case, however, H2SO4 cannot effectively facilitate the
asymmetric epoxidation catalyzed by iron catalyst C1 (Table 1,
entry 10).
Results and Discussion
As shown in the Scheme 2, the chiral N4 ligand, (R,R)-MPMCP
could be synthesized by the direct alkylation of (R,R)-N,N’-
dimethylcyclohexane-1,2-diamine
(chloromethyl)pyridin-4-yl)-morpholine
with
(2),
4-(2-
was
which
synthesized from easily available compound (4-chloropyridin-2-
yl)methanol. [29,37] Iron complex, (R,R)-MPMCP-Fe(OTf)2 (C1) was
synthesized by treating N4 ligands with Fe(OTf)2 in CH3CN.
Table 1. Screening the reaction conditions.[a]
Entry
Oxidant
Acid
Yield [%] [b]
ee [%][c]
90
1
2
3
4
5
6
7
8
H2O2 (50%)
H2O2 (30%)
m-CPBA
EHA
EHA
EHA
EHA
EHA
ACA
D-CPA
S-IBP
81
72
81
40
-
87
26
TBHP
80
Scheme 2. Synthetic route of the ligand MPMCP(L1) and iron complex
MPMCP-Fe(C1).
Oxone
-
H2O2 (50%)
H2O2 (50%)
H2O2 (50%)
41
93
55
30
77
To examine the reactivity of (R,R)-MPMCP-Fe(OTf)2 (C1), we
initially screened the reaction conditions with chalcone as a
model substrate in the presence of 2-ethylhexanoic acid (EHA)
as the additive. It was found that the use of 2 mol% of C1
realized the reaction with 81% yield and 90% ee, using aqueous
H2O2 as the oxidant at -30 oC in CH3CN (Table 1, entry 1).
Notably, the loading of EHA could be reduced to 3 mol% by
using of iron catalyst C1 bearing morpholine functional groups.
The using of 30% aqueous H2O2 led to a slightly decrease both
in reactivity and enantioselectivity (Table 1, entry 2). In addition,
several oxidants, such as m-chloroperoxybenzoic acid (m-
CPBA), tert-butyl hydroperoxide (TBHP) were investigated to
identify the choice of oxidant, both the product yields and the ee
values were lower than that of H2O2 (Table 1, entries 3 and 4).
No epoxidation occurred when oxone was used as oxidant
(Table 1, entry 5).
90
74
Boc-L-(-)-
Proline
57
9
H2O2 (50%)
H2O2 (50%)
10
H2SO4
20
77
[a] Reaction conditions: H2O2 (1.6 equiv, diluted with 0.5 mL of MeCN) was
added over a period of 30 min to a stirred solution of iron catalyst C1 (2
mol%), acid (3 mol%), and substrate (0.4 mmol) in CH3CN (1.0 mL) at -30
oC, then the mixture was further stirred for additional 30 min (The structure
of examined acids was listed in Figure 1). [b] Isolated product yield. [c]
Determined by HPLC with a Daicel chiral OD-H column.
It has been demonstrated that acids play an important role in
asymmetric epoxidation catalyzed by nonheme metal complexes
with H2O2 and using of coligand carboxylic acid lead to an
efficient heterolytic O−O bond cleavage of MIII(OOH) (M = Fe,
Mn) species to form high-valent metal-oxo species.[38,39]
Bryliakov, Talsi and co-workers found that the branched
carboxylic acid EHA could dramatically improve the yield and
Figure 1. The examined carboxylic acids in this study.
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42
74
90
84
Table 2. Substrate scope of asymmetric epoxidation of olefins by bioinspired
iron catalyst.[a]
13
83
14
53[e]
15[d]
Substrate
Yield[%][b]
ee[%][c]
90
Entry
1
[a] Reaction conditions: H2O2 ( 1.6 equiv, diluted with 0.5 mL of MeCN) was
added over a period of 30 min to a stirred solution of iron catalyst C1 (2
mol%), D-CPA (3 mol%) and substrate (0.4 mmol) in CH3CN (1.0 mL) at -30
oC, then the mixture was further stirred for additional 30 min. [b] Isolated
product yield. [c] Determined by HPLC analysis on chiral stationary phase. [d]
3 mol % of EHA was used in place of D-CPA. [e] The yield and ee were
determined by GC with a chiral column.
93
2
3
90
80
94
91
With the optimized reaction conditions in hand, we first
examined the substrate scope of the chalcones, and the results
were summarized in Table 2. The chalcone derivatives with
various electronic properties on the phenyl ring of the olefin side
were smoothly converted into the corresponding epoxyketones
in excellent yields and enantioselectivities (Table 2, entries 2-4).
Then, chalcones with different functional groups on phenyl at
ketone side were explored. Obviously, substitutes on the phenyl
ring of the ketone side were proven to reduce the reaction
outcome. It was found that chalcone bearing methyl group gave
48% yield and 92% ee (Table 2, entry 5). And, lower yields and
enantioselectivities were obtained when either electron-donating
or electron-withdrawing groups were introduced to the phenyl
ring (Table 2, entries 6-8). Disubstituted chalcone in both phenyl
rings was also tolerated albeit with low yield and moderate
enantioselectivity (Table 2, entry 9). To further demonstrate the
utility of this iron-catalyzed epoxidation, several less examined
electron-deficient alkenyl amides were also involved. To our
delight, the corresponding epoxy amides were obtained in
excellent yields and with up to 99.9% ee (Table 2, entry 11),
albeit the substrate bearing a bromo substituent provided a
moderate yield (Table 2. entry 12). Additionally, we screened
other olefins that were structurally different to expand the scope
of the reaction. Firstly, chromenes were tested and moderate
yields and good enantioselectivities were observed (Table 2,
entries 13, 14). In the case of asymmetric epoxidation of cis-β-
methylstyrene reaction, the reaction proceeded smoothly to
deliver the epoxide in 90 % yield and 53% ee with 3 mol % of
EHA as acid partner (Table 2, entry 15). Overall, the dosage of
carboxylic acid could be reduced to catalytic amount by
introducing strong donating group at pyridine rings while
maintaining the activities and enantioselectivities, which was
consistent with the previous reports.[29,30] Carboxylic acid would
coordinate with metal-hydroperoxo intermediates and facilitate
the O-O bond cleavage, thereby generating high-valent metal-
oxo species as reactive intermediates in epoxidation
systems.[29,30,38-40]
4
5
6
87
48
51
92
92
74
7
8
41
62
83
72
9
34
91
54
91
10
11
12
90
51
99.9
85
Conclusions
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6.62 – 6.51 (m, 1H), 4.55 (s, 2H), 3.81 (m, 4H), 3.29 (m, 4H). 13C NMR
(101 MHz, CDCl3) δ 156.7, 156.2, 149.3, 107.4, 106.9, 66.3, 46.8, 46.2.
In summary, we have prepared and characterized an
aminopyridine ligand and its iron complex, bearing a strong
electrondonating and bulky morpholine group on the ligand. As
expected, the iron complex exhibited excellent stereoselectivities
in the asymmetric epoxidation of various olefins (e.g., chalcones,
up to 94% ee; alkenyl amides, up to 99.9% ee), with
environmentally friendly H2O2 as the oxidant in the presence of
catalytic amount of the carboxylic acid partner (e. g., D-(+)-
camphoric acid, 2-ethylhexanoic acid). Further elucidation of the
reaction mechanism and development of more robust catalytic
systems are underway. It is believed that the practical and
environmentally friendly asymmetric epoxidation achieved by
nonheme iron catalysts would be explored widely and applied in
synthetic chemistry.
(R,R)-MPMCP (L1)
4-(2-(Chloromethyl)pyridin-4-yl)morpholine (2) (869 mg, 4.1 mmol) and
(R,R)-N,N’-dimethyl-cyclohexane-1,2-diamine (289 mg, 2.0 mmol) were
dissolved in 35 mL of dry CH3CN, and dry Na2CO3 (1.20 g), tetra-(n-
octyl)ammonium bromide (154 mg) were added. The mixture was stirred
under Ar atmosphere at 80 oC for 20 h. After cooling to rt, the mixture
was filtered, and the precipitate was washed with CH2Cl2. The combined
filtrates were evaporated under vacuo. To the residue, 2 N solution of
NaOH aq. was added to reach pH > 10, then the mixture was extracted
with 3x20 mL of CH2Cl2, The organic fractions were combined, dried over
Na2SO4 and the solvent was eliminated under vacuum. The obtained
brown oil that was purified by silica column and the collected fractions
were removed under reduced pressure to provide the ligand as yellow
20
solid (410 mg, 0.83 mmol, yield 41%). [α]D = +28.7 (c = 1.07 in
CHCl3),1H NMR (400 MHz, CDCl3) δ 8.16 (d, J = 6.0 Hz, 2H), 7.11 (d, J =
2.4 Hz, 2H), 6.51 (dd, J = 6.0, 2.4 Hz, 2H), 3.90 – 3.52 (m, 12H), 3.21 –
3.01 (m, 8H), 2.64 (d, J = 8.0 Hz, 2H), 2.29 (s, 6H), 2.09 – 1.91 (m, 2H),
1.75 (d, J = 8.0 Hz, 2H), 1.11-1.35 (m, 4H). 13C NMR (101 MHz, CDCl3) δ
162.1, 155.9, 149.0, 107.1, 106.8, 66.4, 64.7, 60.4, 46.2, 37.0, 25.8, 25.5.
HRMS (ESI-MS) calcd. for C28H43N6O2 [M+H]+: 495.3447, found:
495.3427.
Experimental Section
General remark
The chemicals were purchased from commercial suppliers and used
without further purification. 1H NMR and 13C NMR spectra were recorded
on a Bruker Avance III 400 MHz spectrometer using CDCl3 as the solvent
with TMS as an internal reference. HRMS (ESI) were determined on an
Agilent 6530 Accurate-Mass Q-TOF mass spectrometer. Elemental
analyses were performed on a Vario EL cube elementar analyzer. GC–
MS spectra were recorded on an Agilent Technologies 7890A GC-
system/ Agilent 5975 MS (EI) with a HP-5MS column. HPLC analysis
was performed on Waters-Breeze (2487 Dual λ Absorbance Detector
and 1525 Binary HPLC Pump). Chiralpak OD-H, AD-H, OJ, AS, OB, IC
columns were purchased from Daicel Chemical Industries, LTD. GC
analysis was performed on a Agilent 7890 GC with a CP-Chirasil-Dex CB
column. Column chromatography was generally performed on silica gel
(200-300 mesh) and TLC inspections were performed on silica gel GF254
plates. All reactions were carried out under argon in dried glassware.
(R,R)-MPMCP iron complex (C1)
Under an argon atmosphere, Fe(CF3SO3)2 (0.25 mmol, 1 equiv) was
added to a stirred solution of chiral ligand L1 (0.25 mmol, 1 equiv) in
acetonitrile (3 mL) at room temperature, then the reaction mixture was
stirred for 24 h. After the solvent was removed under vacuum, the
resulting solid was washed thoroughly with ether for three times and
dried under vacuum to yield iron complex C1 (yield > 90 %). HRMS (ESI-
MS) calcd. for C28H42FeN6O2 [M-2OTf]2+: 275.1360, found: 275.1356;
elemental analysis Calcd (%) for C30H42F6FeN6O8S2•1.5H2O: C 41.15, H
5.18, N 9.60; found C 41.09, H 4.84, N 9.12.
Synthesis of the N4-based ligand and iron complex[28,36]
(4-morpholinopyridin-2-yl)methanol (1)
General procedures for asymmetric epoxidation
(4-Chloropyridin-2-yl)methanol (1.00 g, 7.0 mmol) and morpholine (3.05 g,
35.0 mmol) were added to a 25 mL Schlenk tube and stirred at 155 oC
for 24 h. After cooling to room temperature, the mixture was diluted with
methylene chloride and washed with H2O, brine and dried over Na2SO4.
Then the solvent was eliminated under vacuum to provide the product (1)
as yellow solid (1.1 g, yield 73%).1H NMR (400 MHz, CDCl3) δ 8.12 (d, J
= 6.0 Hz, 1H), 6.71 (d, J = 2.4 Hz, 1H), 6.49 (m, 1H), 5.16 (s, 1H), 4.60 (s,
2H), 3.79 – 3.68 (m, 4H), 3.28 – 3.18 (m, 4H). 13C NMR (101 MHz,
CDCl3) δ 160.9, 156.0, 149.0, 106.9, 104.7, 66.3, 64.6, 46.1.
Under an argon atmosphere, a 10 mL Schlenk tube was charged with
substrate (0.4 mmol), catalyst C1 (2 mol%), acid (3 mol%), MeCN (1.0
mL) and a magnetic stir bar, and cooled at -30 oC. Then a H2O2 solution
(1.6 equiv, diluted from a 50% aqueous solution in 0.5 mL MeCN) was
added via a syringe pump over a period of 30 min. The solution was
further stirred at -30 oC for 30 min. Then the reaction was treated with
CH2Cl2, and washed with saturated Na2S2O3 aqueous solution, saturated
NaHCO3 aqueous solution. The solvent was removed under reduced
pressure and the resulting residue was purified by flash column
chromatography on silica gel to get pure products.
4-(2-(chloromethyl)pyridin-4-yl)morpholine (2)
To a stirred solution of (4-morpholinopyridin-2-yl)methanol (1.10 g, 5.8
mmol) in CH2Cl2 (50 mL) was added thionyl chloride (1.00 g, 9.0 mmol)
slowly. After addition, the resulting mixture was stirred at rt overnight.
The reaction was quenched with Na2CO3 aqueous solution, and the
organic layer was collected. The aqueous layer was extracted with
CH2Cl2, and the combined organic phase was dried over Na2SO4.
Removal of volatile components gave an orange solid (869 mg, 70%
yield). 1H NMR (400 MHz, CDCl3) δ 8.22 (d, J = 6.0 Hz, 1H), 6.81 (s, 1H),
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (21473226 and 21133011).
Keywords: Asymmetric epoxidation • Iron • Hydrogen peroxide •
Olefin• Bioinspired catalysis
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[1]
[2]
a) Q. H. Xia, H. Q. Ge, C. P. Ye, Z. M. Liu, K. X. Su, Chem. Rev. 2005,
[23] M. S. Chen, M. C. White, Science 2007, 318, 783-787.
105, 1603-1662; b) A. J. McCue, R. P. K. Wells, J. A. Anderson,
ChemCatChem 2011, 3, 699-703.
[24] M. S. Chen, M. C. White, Science 2010, 327, 566-571.
[25] M. C. White, A. G. Doyle, E. N. Jacobsen, J. Am. Chem. Soc. 2001,
123, 7194-7195.
a) O. A. Wong, Y. Shi, Chem. Rev. 2008, 108, 3958-3987; b) Y. Zhu, Q.
Wang, R. G. Cornwall, Y. Shi, Chem. Rev. 2014, 114, 8199-8256; c) T.
T. Liu, Z. J. Lin, P. C. Shi, T. Ma, Y. B. Huang, R. Cao, ChemCatChem
2015, 7, 2340-2345.
[26] M. Wu, C. X. Miao, S. F. Wang, X. X. Hu, C. G. Xia, F. E. Kühn, W. Sun,
Adv. Synth. Catal. 2011, 353, 3014-3022.
[27] B. Wang, S. F. Wang, C. G. Xia, W. Sun, Chem. Eur. J. 2012, 18,
7332-7335.
[3]
[4]
[5]
G. De Faveri, G. Ilyashenko, M. Watkinson, Chem. Soc. Rev. 2011, 40,
1722-1760.
[28] O. Y. Lyakin, R. V. Ottenbacher, K. P. Bryliakov, E. P. Talsi, ACS Catal.
2012, 2, 1196-1202.
E. P. Talsi, T. V. Rybalova, K. P. Bryliakov, J. Mol. Catal. A: Chem.
2016, 421, 131-137.
[29] O. Cusso, I. Garcia-Bosch, X. Ribas, J. Lloret-Fillol, M. Costas, J. Am.
Chem. Soc. 2013, 135, 14871-14878.
T. Bogaerts, S. Wouters, P. Van der Voort, V. Van Speybroeck,
ChemCatChem 2015, 7, 2711-2719.
[30] O. Cusso, X. Ribas, J. Lloret-Fillol, M. Costas, Angew. Chem., Int. Ed.
2015, 54, 2729-2733.
[6]
[7]
T. Katsuki, K. B. Sharpless, J. Am. Chem. Soc. 1980, 102, 5974-5976.
W. Zhang, J. L. Loebach, S. R. Wilson, E. N. Jacobsen, J. Am. Chem.
Soc. 1990, 112, 2801-2803.
[31] O. Cusso, M. Cianfanelli, X. Ribas, R. J. M. K. Gebbink, M. Costas, J.
Am. Chem. Soc. 2016, 138, 2732-2738.
[8]
[9]
R. Irie, K. Noda, Y. Ito, N. Matsumoto, T. Katsuki, Tetrahedron Lett.
1990, 31, 7345-7348.
[32] M. Wu, B. Wang, S. F. Wang, C. X. Xia, W. Sun, Org. Lett. 2009, 11,
3622-3625.
Y. Tu, Z. X. Wang, Y. Shi, J. Am. Chem. Soc. 1996, 118, 9806-9807.
[33] a) B. Wang, C. X. Miao, S. F. Wang, C. G. Xia, W. Sun, Chem. Eur. J.
2012, 18, 6750-6753; b) X. E. Wang, C. X. Miao, S. F. Wang, C. G. Xia,
W. Sun, ChemCatChem 2013, 5, 2489-2494.
[10] K. Gopalaiah, Chem. Rev. 2013, 113, 3248-3296.
[11] J. T. Groves, R. S. Myers, J. Am. Chem. Soc. 1983, 105, 5791-5796.
[12] a) B. F. Perandones, E. D. Nieto, C. Godard, S. Castillon, P. De Frutos,
C. Claver, ChemCatChem 2013, 5, 1092-1095; b) O. Cusso, X. Ribas,
M. Costas, Chem. Commun. 2015, 51, 14285-14298.
[34] D. Y. Shen, B. Qiu, D. Q. Xu, C. X. Miao, C. G. Xia, W. Sun, Org. Lett.
2016, 18, 372-375.
[35] D. Y. Shen, C. X. Miao, S. F. Wang, C. G. Xia, W. Sun, Org. Lett. 2014,
16, 1108-1111.
[13] C. Wang, H. Yamamoto, Chem. Asian J. 2015, 10, 2056-2068.
[14] a) J. W. Kuck, A. Raba, I. I. E. Markovits, M. Cokoja, F. E. Kuhn,
ChemCatChem 2014, 6, 1882-1886; b) A. Fingerhut, O. V. Serdyuk, S.
B. Tsogoeva, Green Chem. 2015, 17, 2042-2058.
[36] D. Y. Shen, C. X. Miao, D. Q. Xu, C. G. Xia, W. Sun, Org. Lett. 2015,
17, 54-57.
[37] C. X. Zhang, S. Kaderli, M. Costas, E. Kim, Y. M. Neuhold, K. D. Karlin,
A. D. Zuberbuhler, Inorg. Chem. 2003, 42. 1087-1024.
[38] R. Mas-Balleste, L. Que, J. Am. Chem. Soc. 2007, 129, 15964-15972.
[39] Y. Wang, D. Janardanan, D. Usharani, K. Han, L. Que, S. Shaik, ACS
Catal. 2013, 3, 1334-1341.
[15] J. P. Collman, Z. Wang, A. Straumanis, M. Quelquejeu, E. Rose, J. Am.
Chem. Soc. 1999, 121, 460-461.
[16] F. G. Gelalcha, B. Bitterlich, G. Anilkumar, M. K. Tse, M. Beller, Angew.
Chem., Int. Ed. 2007, 46, 7293-7296.
[17] Y. Nishikawa, H. Yamamoto, J. Am. Chem. Soc. 2011, 133, 8432-8435.
[18] M. Costas, M. P. Mehn, M. P. Jensen, L. Que, Jr., Chem. Rev. 2004,
104, 939-986.
[40] A. M. Zima, O. Y. Lyakin, R. V. Ottenbacher, K. P. Bryliakov, E. P. Talsi,
ACS Catal. 2016, 6, 5399-5404.
[41] W. Dai, S. S. Shang, B. Chen, G. S. Li, L. Y. Wang, L. H. Ren, S. Gao,
J. Org. Chem. 2014, 79, 6688-6694.
[19] W. Nam, Acc. Chem. Res. 2007, 40, 522-531.
[20] E. P. Talsi, K. P. Bryliakov, Coord. Chem. Rev. 2012, 256, 1418-1434.
[21] W. N. Oloo, L. Que, Acc. Chem. Res. 2015, 48, 2612-2621.
[22] K. P. Bryliakov, E. P. Talsi, Coord. Chem. Rev. 2014, 276, 73-96.
[42] C. X. Miao, B. Wang, Y. Wang, C. G. Xia, Y.-M. Lee, W. Nam, W. Sun,
J. Am. Chem. Soc. 2016, 138, 936-943.
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10.1002/cctc.201601293
ChemCatChem
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The aminopyridine N4 iron complex
serves to efficiently catalyze the
asymmetric epoxidation of various
olefins by H2O2, providing the
epoxides in good to excellent yields
and enantioselectivities (up to 99.9%
ee). Due to the introduction of
morpholine functional groups on the
ligand, the Fe-catalyzed reaction can
proceed in the catalytic amount of the
carboxylic acid partner (3 mol%).
W. Wang, Q. Sun, D. Xu, C. Xia, W.
Sun*
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Asymmetric Epoxidation of Olefins
with H2O2 Catalyzed by a Bioinspired
Aminopyridine N4 Iron Complex
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