Remarkable enhancement of aerobic epoxidation reactivity for olefins catalyzed by μ-oxo-bisiron(III) porphyrins under ambient conditions

Article abstract of DOI:10.1016/j.tetlet.2009.09.061

With μ.-oxo dimeric iron(III) porphyrins [(FeIIITPP)2O] as catalyst, isobutylaldehyde as co-reductant, and dioxygen as oxidant, an efficient model system for epoxidation of olefins has been developed. Compared with mono-metalloporphyrins as catalyst, a remarkable enhancement of reactivity was obtained for the present olefin epoxidation system, in which the turnover number (TON) of the catalyst has doubled from about 700 million to 1400 million. Moreover, a plausible mechanism involving both binuclear and mononuclear intermediate has been proposed.

Full text of DOI:10.1016/j.tetlet.2009.09.061

Tetrahedron Letters 50 (2009) 6601–6605
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Remarkable enhancement of aerobic epoxidation reactivity for olefins
catalyzed by
l-oxo-bisiron(III) porphyrins under ambient conditions
Xian-Tai Zhou a, Qing-Hua Tang b, Hong-Bing Ji a,
*
a School of Chemistry and Chemical Engineering, Sun Yat-sen University, 510275 Guangzhou, PR China
b School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, PR China
a r t i c l e i n f o
a b s t r a c t
With l
-oxo dimeric iron(III) porphyrins [(FeIIITPP)2O] as catalyst, isobutylaldehyde as co-reductant, and
Article history:
Received 26 July 2009
Revised 6 September 2009
Accepted 11 September 2009
Available online 13 September 2009
dioxygen as oxidant, an efficient model system for epoxidation of olefins has been developed. Compared
with mono-metalloporphyrins as catalyst, a remarkable enhancement of reactivity was obtained for the
present olefin epoxidation system, in which the turnover number (TON) of the catalyst has doubled from
about 700 million to 1400 million. Moreover, a plausible mechanism involving both binuclear and mono-
nuclear intermediate has been proposed.
Keywords:
Ó 2009 Elsevier Ltd. All rights reserved.
l-Oxo dimeric iron(III) porphyrins
Olefins
Epoxidation
Dioxygen
1. Introduction
Bismetalloporphyrin dimers are composed of two covalently
bound mono-metalloporphyrin molecules. Investigations over the
Catalytic epoxidation of olefins has attracted much attention
both in industry and in organic synthesis, for epoxides are among
the most useful synthetic intermediates.1 Epoxidation of olefins
could be carried out with various catalytic systems, in which com-
plexes of ruthenium,2 manganese,3 polyoxometalates,4 and oxova-
nadium Schiff base5 could all be used as catalysts.
past decades indicated that
or have low activity for hydroxylation of alkanes. Recently, high
catalytic activities of -oxo dimeric metalloporphyrins for the
oxidation of cyclohexane, ethylbenzene, and toluene have been
reported.15 However, the catalysis of simple
-oxo dimeric metal-
l-oxo-bisiron porphyrins are inactive
l
l
loporphyrins for epoxidation of olefins by dioxygen has not been
As model catalysts of cytochrome P-450, metalloporphyrins
have been used in the highly efficient epoxidations of olefins in
combination with various oxidants for example, iodosylbenzene,6
hydrogen peroxide,7 and sodium periodate.8 To pursue the eco-
nomical and environmentally friendly processes for the production
of epoxides, selective epoxidation of olefins by molecular oxygen is
particularly desirable.9 Mukaiyama et al. reported an efficient ap-
proach for epoxidation of olefins using dioxygen as oxidant under
ambient conditions. The process involved the use of b-diketonate
complexes of Ni2+, Co2+, and Fe3+ as catalysts and an aldehyde as
oxygen acceptor.10 Subsequently, many metal catalysts for exam-
ple, manganese complex,11 cobalt-containing molecular sieves,12
and metalloporphyrins13 demonstrated highly catalytic perfor-
mance for the aerobic oxidation in the presence of aldehyde. We
have also developed a series of catalytic systems for the aerobic
oxidation of sulfide, alcohol, and ketone with metalloporphyrins
as catalysts.14
reported up to now.
In our previous works, simple structural mono-manganese por-
phyrin conferred high activity and selectivity for the epoxidation of
olefins, its turnover number could reach up to 700 million, which is
comparable to enzyme catalysis.16 Based on the high efficiency of
the metalloporphyrin-catalyzed epoxidation system, we have em-
ployed the simple l-oxo dimeric iron porphyrins for catalyzing the
epoxidation of olefins by dioxygen in the presence of isobutyralde-
hyde in the present Letter, as shown in Scheme 1.17 The catalytic
system has been proved to be efficient for the aerobic epoxidation
of olefins under ambient conditions. Compared with mono-metal-
loporphyrins, a remarkable enhancement of reactivity has been ob-
served. It is the first time that dimeric iron(III) porphyrins are used
for aerobic epoxidation, and the TON obtained is higher than other
catalysts reported.
2. (FeIIITPP)2O Catalytic epoxidation of cyclohexene
With cyclohexene as model compound, the effects of reaction
conditions on the epoxidation in the presence of (FeIIITPP)2O with
molecular oxygen as oxidant have been investigated.18 Table 1
* Corresponding author. Tel.: +862084113658; fax: +862084113654.
E-mail address: jihb@mail.sysu.edu.cn (H.-B. Ji).
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.09.061

6602
X.-T. Zhou et al. / Tetrahedron Letters 50 (2009) 6601–6605
(FeIIITPP)2O
R1
R3
O
R2
R4
R1
R3
R2
R4
isobutyraldehyde, CH3CN, O2, r.t.
O
N
N
N
N
N
N
N
N
Fe
Fe
Scheme 1. Aerobic epoxidation of olefins catalyzed by [FeIIITPP]2O in the presence of molecular oxygen and isobutyraldehyde.
Table 1
Compared with the aerobic epoxidation catalyzed by mono-
metalloporphyrin, (FeIIITPPCl, entry 10), it is clear that
-oxo di-
meric iron(III) porphyrin exhibited higher catalytic performance
for the aerobic epoxidation of cyclohexene, probably because
(FeIIITPP)2O has superior stability for epoxidation than FeIIITPPCl.
Aerobic epoxidation of cyclohexene catalyzed by (FeIIITPP)2O in the presence of
isobutyraldehydea
l
Entry
Amount of catalyst (ppm)
Conv. (%)
Yield (%)
1
2
3
4
5
6
0
21
96
>99
90
81
84
0
92
>99
85
21
93
96
88
80
81
0
90
96
82
0.01
0.05
0.1
3. Effects of solvent on the epoxidation of cyclohexene
1.0
Using
l-oxo-bisiron(III) porphyrin as the catalyst, the aerobic
10.0
0.05
0.05
0.05
0.1
7b
8c
9d
10e
epoxidation of cyclohexene with various solvents has been investi-
gated, and the results were summarized in Table 2.
It has been observed that the solvent played an important role
for the oxidation reaction. Polar solvents for example, acetonitrile
and benzotrifluoride seemed to be more favorable for the epoxida-
tion of cyclohexene. Dichloromethane was not suitable for this
catalytic epoxidation, although it was commonly used in metallo-
porphyrins-catalyzed epoxidation systems.20 It may be due to the
instability of (FeIIITPP)2O in dichloromethane, which could be
partly converted to mono-metalloporphyrins.21
a
Substrate (2 mmol), isobutylaldehyde (0.011 mol), acetonitrile (6 mL), O2 bub-
bling, 4 h, rt.
b
No isobutylaldehyde.
c
d
e
Substrate/isobutylaldehyde = 1:5.
Substrate/isobutylaldehyde = 1:6.
FeIIITPPCl as catalyst.
4. Epoxidation of various substrates catalyzed by (FeIIITPP)2O
summarizes the main results obtained under different reaction
conditions. It could be found from entry 1 of Table 1 that only
21% cyclohexene could be converted in the absence of catalyst,
indicating that the (FeIIITPP)2O catalyst is crucial for the epoxida-
tion. As depicted in Table 1, it was observed that the yield was con-
siderably enhanced when the catalyst was used. The conversion of
cyclohexene could reach up to 96% even when the amount of cat-
alyst was only 0.01 ppm (entry 2). The optimal amount of catalyst
for the epoxidation was 0.05 ppm (entry 3). On the contrary, at-
tempts for enhancing the yield by increasing the amount of cata-
lyst were unsuccessful. The yield decreased with the increase of
catalyst amount (entries 4–6). This is the typical characteristics
of metalloporphyrins-catalyzed oxidation, which was caused by
the shielding effect due to the increasing catalyst intermediates.19
The effects of isobutyraldehyde on the reaction were also inves-
tigated. As shown in Table 1, the reaction could not take place in
the absence of isobutyraldehyde (entry 7), strongly implying that
(FeIIITPP)2O could not activate molecular oxygen without aldehyde
as an oxygen acceptor under ambient conditions. The epoxidation
with various molar ratio of substrate to isobutyraldehyde were
examined. When the substrate/isobutyraldehyde molar ratio
reached 1:5, 92% cyclohexene could be converted (entry 8).
Increasing molar ratio gave higher conversion (entry 9). However,
no significant difference was observed when the substrate/isobu-
tyraldehyde molar ratio exceeds 1:5.5.
To evaluate the scope of the catalytic system, various alkenes
were subjected to the reaction system using only 0.05 ppm of cat-
alyst (Table 3). As shown in Table 3, most substrates could be
smoothly converted to corresponding epoxides with high conver-
sion rate and excellent selectivity.
It seems that the efficiency of the epoxidation in this catalytic
system is not closely related with the steric conformation of sub-
strates. For instance, slightly longer reaction time was required
for 1-methylcyclohexene than cyclohexene (entries 1 and 2). How-
ever, slow oxidation occurred and an unsatisfactory conversion
Table 2
Effect of the solvent on the aerobic epoxidation of cyclohexene catalyzed by
(FeIIITPP)2Oa
Entry
Solvent
Conv. (%)
Yield (%)
Selectivity (%)
1
2
3
4
5
Acetonitrile
Benzotrifluoride
Methanol
Dichloromethane
Toluene
>99
73
66
60
96
71
64
57
59
96
97
97
95
96
61
a
Substrate (2 mmol), substrate/isobutylaldehyde = 1:5.5 (molar ratio),
(FeIIITPP)2O (0.05 ppm), acetonitrile (6 mL), O2 bubbling, 4 h, rt.

X.-T. Zhou et al. / Tetrahedron Letters 50 (2009) 6601–6605
6603
Table 3
Aerobic epoxidation of various alkenes catalyzed by (FeIIITPP)2Oa
Entry
Substrate
Product
Reaction time (h)
4
Conv. (%)
>99
Yield (%)
1
96
98
O
O
2
5
>99
3
7
7
42
73
41
72
O
4b
5
7
7
36
76
34
73
O
O
O
6b
O
7
7
7
23
70
13
64
8b
9
4
8
>99
96
98
94
O
10
11
12
4
6
93
96
92
72
O
a
Substrate (2 mmol), isobutylaldehyde (0.011 mol), acetonitrile (6 mL), O2 bubbling, rt.
(FeIIITPP)2O (1.0 ppm).
b
could be obtained for the simple
a
-olefins or terminal alkenes such
When the amount of (FeIIITPP)2O catalyst used was
6.0 Â 10À9 mmol, cyclohexene oxide could be obtained with the
isolated yield of 87%. It should be mentioned that the turnover
as 1-octene, 1-hexene, and styrene (entries 3, 5, and 7). When the
amount of catalyst increased to 1.0 ppm, a remarkable enhance-
ment for conversion and yield was observed (entries 4, 6, and 8).
While for the non-terminal linear olefin for example, trans-2-oc-
tene, the catalytic system showed excellent catalytic performance,
in which trans-2-octene was converted to the corresponding epox-
ide in 4 hours (entry 9). The catalytic system also seems favorable
for the conversion of other cycloolefin for example, cyclooctene, in
which the reaction system exhibited highly catalytic performance
with 92% yield of cyclooctene epoxide (entry 11).
number of the
l-oxo dimeric porphyrin could reach
1,432,993,256, and its TOF was 2.4 Â 106 minÀ1 23
.
A remarkable
enhancement of reactivity for
l-oxo dimeric iron(III) porphyrins
was observed compared with mono-metalloporphyrins, in which
its TON was about 700 million.
6. A plausible mechanism for the aerobic epoxidation catalyzed
by (FeIIITPP)2O
Another salient feature of the present epoxidation is its high
regioselectivity. When (+)-limonene was subjected to the epoxida-
tion, the monoepoxide with the epoxide group on the ring was the
main product and its selectivity was 72% (entry 12).
As reported previously, the oxygenation of organic substrates
catalyzed by metalloporphyrin complexes plus aldehyde is usually
considered to involve a radical and high-valent metal intermediate
mechanism.24 2,6-Di-tert-butyl-4-methylphenol as a radical trap
has been used in the epoxidation of cyclohexene, and it was found
that the reaction was completely inhibited. Therefore, the aerobic
epoxidation should involve radical species.
5. Large scale epoxidation of cyclohexene
To further investigate the efficiency of the catalytic system, a
large scale experiment for the aerobic epoxidation of cyclohexene
was carried out as shown in Scheme 2.22
In order to obtain further information about the role of the
high-valent iron porphyrin on the epoxidation, in situ UV–vis spec-

6604
X.-T. Zhou et al. / Tetrahedron Letters 50 (2009) 6601–6605
[FeIIITPP]2O
O
CH3CN(60mL), isobutyraldehyge(0. 11mol), O2(1atm), 10h, r.t
isolated yield: 87%
20mmol
TON:1,432,993,256
TOF: 2388322 min-1
Scheme 2. Large scale epoxidation of cyclohexene catalyzed by (FeIIITPP)2O.
tra was used. The catalytic epoxidation in CH3CN was carried out in
a quartz colorimetric cell with dioxygen bubbling. UV–vis spectra
were recorded with 5 min intervals. Figure 1 exemplifies the UV–
416
a
b
vis results observed for
l-oxo dimeric iron(III) porphyrins during
the epoxidation process. The initial spectrum of (FeIIITPP)2O cata-
lyst with a characteristic of Soret band at 408 nm was shown in
Figure 1a. When isobutyraldehyde was added into the mixture, a
shift from 408 to 417 nm with a loss in intensity was observed,
as shown in Figure 1b. Besides, the disappearance of the two Q-
band peaks at 570 and 610 nm was found with the addition of iso-
butyraldehyde. As the reaction continued, a decrease in the Soret
band at 417 nm was recorded. The changes of UV–vis spectra are
indicative of the existence of an active species expected as the
high-valent iron porphyrin.25
400
500
600
700
Figure 2. The UV–vis spectra of (FeIIITPP)2O with isobutyraldehyde and cyclohex-
ene after 20 min of reaction time (a), FeTPPCl (b).
It is usually considered that
l-oxo dimeric metalloporphyrins
could easily form mono-metalloporphyrins during the catalytic
process. In fact, whether the dinuclear intermediate or the mono-
nuclear intermediate is the active species remains controversial
mediates, that is, O@VFe–O–FeV@O and FeV@O were formed by
series of free radical processes. Formation of epoxide is assumed
by the reaction of oxo-iron intermediates with olefins.
for the oxygenation of hydrocarbons catalyzed by
l-oxo dimeric
metalloporphyrins. The possible mononuclear metalloporphyrins
existing in the catalytic system are FeTPPCl or FeTPPOH. Attempts
to obtain some useful information from UV–vis spectrum have
been made.
In conclusion, highly efficient epoxidation of olefins by the
molecular oxygen in the presence of 50 ppb (FeIIITPP)2O was re-
ported. The catalyst conferred high activity and selectivity for the
olefins epoxidation under ambient conditions. The turnover num-
ber of the catalyst could reach up to 1400 million, which is the
highest reported so far. The epoxidation was via a radical process
with the formation of high-valent iron intermediates, which were
confirmed by in situ UV–vis spectroscopy. The results also indicate
that both binuclear and mononuclear exist simultaneously in the
reaction system.
From the UV–vis spectra, FeTPPOH as the mononuclear inter-
mediate in the process is impossible. The active intermediate of
FeTPPOH would form a new peak at 461 nm, while no such peak
was found from the in situ UV–vis spectra as shown in Figure 1.
Figure 2a shows the UV–vis spectra of (FeIIITPP)2O with isobutyral-
dehyde and cyclohexene after reacting for 20 min. Similar UV–vis
spectra curves could be obtained for FeTPPCl catalyst as shown
in Figure 2b. If the high-valent intermediate was mononuclear iron
porphyrin (FeTPPCl), the Soret peak at 416 nm would disappear as
the reported previously.26 However, a certain degree loss of inten-
sity for the Soret peak at 416 nm could be observed for the present
system. As shown in Figure 1, the intensity of Soret peak at 416 re-
mains unchanged after 20 min. The above results indicate that
both the dinuclear and the mononuclear high-valent intermediates
exist in the catalytic system. Probably two kinds of oxo-iron inter-
Acknowledgments
The authors thank the Key Fundamental Research Foundation
(2008CB617511), the National Natural Science Foundation of
China
(20976203), China Postdoctoral Science Foundation
(20080440792), and the Program for New Century Excellent Tal-
ents in University (NCET-06-740) for providing financial support
for this project.
References and notes
a
b
408
2.1
1.4
0.7
0.0
1. (a) Lane, B. S.; Burgess, K. Chem. Rev. 2003, 103, 2457–2473; (b) Rubajlo, V. L.;
Maslov, S. A.; Zaikov, G. E. Liquid-Phase Oxidation of Unsaturated Compounds;
Nova Science Publishers Inc.: Hauppauge, 1993; (c) McGarrigle, E. M.; Gilheany,
D. G. Chem. Rev. 2005, 105, 1563–1602; (d) Xia, Q. H.; Ge, H. Q.; Ye, C. P.; Liu, Z.
M.; Su, K. X. Chem. Rev. 2005, 105, 1603–1662; (e) Grigoropoulou, G.; Clark, J.
H.; Elings, J. A. Green Chem. 2003, 5, 1–7.
2. (a) Tse, M. K.; Bhor, S.; Klawonn, M.; Anilkumar, G.; Jiao, H. J.; Spannenberg, A.;
Dobler, C.; Magerlein, W.; Hugl, H.; Beller, M. Chem.-Eur. J. 2006, 12, 1875–
1888; (b) Magerlein, W.; Dreisbach, C.; Hugl, H.; Tse, M. K.; Klawonn, M.; Bhor,
S.; Beller, M. Catal. Today 2007, 121, 140–150; (c) Qi, J. Y.; Qiu, L. Q.; Lam, K. H.;
Yip, C. W.; Zhou, Z. Y.; Chan, A. S. C. Chem. Commun. 2003, 1058–1059.
3. (a) Brinksma, J.; Schmieder, L.; van Vliet, G.; Boaron, R.; Hage, R.; De Vos, D. E.;
Alsters, P. L.; Feringa, B. L. Tetrahedron Lett. 2002, 43, 2619–2622; (b) Luts, T.;
Frank, R.; Suprun, W.; Fritzsche, S.; Hey-Hawkins, E.; Papp, H. J. Mol. Catal. A
2007, 273, 250–258; (c) Castaman, S. T.; Nakagaki, S.; Ribeiro, R. R.; Ciuffi, K. J.;
Drechsel, S. M. J. Mol. Catal. A 2009, 300, 89–97; (d) Krishnan, R.; Vancheesan, S.
J. Mol. Catal. A 2002, 185, 87–95; (e) Serafimidou, A.; Stamatis, A.; Louloudi, M.
Catal. Commun. 2008, 9, 35–39.
417
570
610
600
400
500
Wavelength/ nm
700
Figure 1. In situ UV–vis spectra of cyclohexene epoxidation catalyzed by
(FeIIITPP)2O in the presence of molecular oxygen and isobutyraldehyde.

X.-T. Zhou et al. / Tetrahedron Letters 50 (2009) 6601–6605
6605
4. Nishiyama, Y.; Nakagawa, Y.; Mizuno, N. Angew. Chem., Int. Ed. 2001, 40, 3639–
3641.
5. Rayati, S.; Koliaei, M.; Ashouri, F.; Mohebbi, S.; Wojtczak, A.; Kozakiewicz, A.
Appl. Catal., A 2008, 346, 65–71.
6. (a) Murakami, Y.; Konishi, K. J. Am. Chem. Soc. 2007, 129, 14401–14407; (b)
Vinhado, F. S.; Gandini, M. E. F.; Iamamoto, Y.; Silva, A. M. G.; Simoes, M. M. Q.;
Neves, M. G. P. M.; Tome, A. C.; Rebelo, S. L. H.; Pereira, A. M. V. M.; Cavaleiro, J.
A. S. J. Mol. Catal. A 2005, 239, 138–143; (c) de Sousa, A. N.; de Carvalho, M. E. M.
16. Zhou, X. T.; Ji, H. B.; Xu, H. C.; Pei, L. X.; Wang, L. F.; Yao, X. D. Tetrahedron Lett.
2007, 48, 2691–2695.
17. FeIIITPPCl and (FeIIITPP)2O were prepared according to the procedure reported
previously, see: Ref. 13. The spectral and analysis data of (FeIIITPP)2O. FAB: m/z
1353. Anal. Calcd for C88H56Fe2N8O: C, 78.11; H, 4.17; N, 8.28. Found: C, 77.97;
H, 4.29; N, 8.09. UV–vis(CH2Cl2) kmax
: 409 nm (Soret band), 548 nm and
592 nm (Q-band); IR: 889 cmÀ1
(m
Fe–O–Fe). The spectral and analysis data of
FeTPPCl are FAB: m/z 705. Anal. Calcd for C44H28N4FeCl: C, 74.98; H, 3.98; N,
7.95. Found: C, 75.12; H, 4.01; N, 7.89. UV–vis(CH2Cl2) kmax: 417 nm (Soret
D.; Idemori, Y. M. J. Mol. Catal.
A 2001, 169, 1–10; (d) Serwicka, E. M.;
Poltowicza, J.; Bahranowski, K. T.; Olejniczak, Z.; Jones, W. Appl. Catal., A 2004,
275, 9–14; (e) Li, Z.; Xia, C. G.; Ji, M. Appl. Catal., A 2003, 252, 17–21.
7. (a) Stephenson, N. A.; Bell, A. T. J. Mol. Catal. A 2007, 275, 54–62; (b) Chan, W. K.;
Wong, M. K.; Che, C. M. J. Org. Chem. 2005, 70, 4226–4232; (c) Stephenson, N.
A.; Bell, A. T. J. Am. Chem. Soc. 2005, 127, 8635–8643; (d) Campestrini, S.;
Tonellato, U. J. Mol. Catal. A 2001, 171, 37–42; (e) De Paula, R.; Simoes, M. M. Q.;
Neves, M. G. P. M.; Cavaleiro, J. A. S. Catal. Commun. 2008, 10, 57–60.
8. (a) Naik, R.; Joshi, P.; Umbarkar, S.; Deshpande, R. K. Catal. Commun. 2005, 6,
125–129; (b) Moghadam, M.; Tangestaninejad, S.; Mirkhani, V.; Kargar, H.;
Komeili-Isfahani, H. Catal. Commun. 2005, 6, 688–693; (c) Moghadam, M.;
Mirkhani, V.; Tangestaninejad, S.; Mohammdpoor-Baltork, I.; Kargar, H. J. Mol.
Catal. A 2008, 288, 116–124.
9. (a) Lignier, P.; Mangematin, S.; Morfin, F.; Rousset, J. L.; Caps, V. Catal. Today
2008, 138, 50–54; (b) Kantam, M. L.; Rao, B. P. C.; Reddy, R. S.; Sekhar, N. S.;
Sreedhar, B.; Choudary, B. M. J. Mol. Catal. A 2007, 272, 1–5; (c) Haber, J.;
Matachowski, L.; Pamin, K.; Poltowicz, J. J. Mol. Catal. A 2003, 198, 215–221; (d)
Kameyama, H.; Narumi, F.; Hattori, T.; Kameyama, H. J. Mol. Catal. A 2006, 258,
172–177.
10. (a) Mukaiyama, T.; Yamada, T.; Nagata, T.; Imagawa, K. Chem. Lett. 1993, 327–
330; (b) Yamada, T.; Takai, T.; Rhode, O.; Mukaiyama, T. Bull. Chem. Soc. Jpn.
1991, 64, 2109–2117; (c) Nagata, T.; Imagawa, K.; Yamada, T.; Mukaiyama, T.
Chem. Lett. 1994, 1259–1262.
11. (a) Qi, J. Y.; Li, Y. M.; Zhou, Z. Y.; Che, C. M.; Yeung, C. H.; Chan, A. S. C. Adv.
Synth. Catal. 2005, 347, 45–49; (b) Ravikumar, K. S.; Barbier, F.; Begue, J. P.;
Delpon, D. B. Tetrahedron 1998, 54, 7457–7464.
12. Raja, R.; Sankar, G.; Thomas, J. M. Chem. Commun. 2009, 9, 829–830.
13. (a) Haber, J.; Mlodnicka, T.; Poltowicz, J. J. Mol. Catal. 1989, 54, 451–461; (b)
Mandal, A. K.; Iqbal, J. Tetrahedron 1997, 53, 7641–7648; (c) Ellis, S.;
Kozhevnikov, I. V. J. Mol. Catal. A 2002, 187, 227–235.
14. (a) Zhou, X. T.; Ji, H. B.; Yuan, Q. L. J. Porphyrins Phthalocyanines 2008, 12, 94–
100; (b) Ji, H. B.; Yuan, Q. L.; Zhou, X. T.; Pei, L. X.; Wang, L. F. Bioorg. Med. Chem.
Lett. 2007, 17, 6364–6368; (c) Zhou, X. T.; Ji, H. B.; Cheng, Z.; Xu, J. C.; Pei, L. X.;
Wang, L. F. Bioorg. Med. Chem. Lett. 2007, 17, 4650–4653; (d) Wang, L. Z.; She, Y.
B.; Zhong, R. G.; Ji, H. B.; Zhang, Y. H.; Song, X. F. Org. Process Res. Dev. 2006, 10,
757–761.
band), 527 nm (Q-band). IR: 1006 cmÀ1 and 325 cmÀ1
.
18. General procedure for the catalytic epoxidation of olefins to epoxides. Dioxygen
was bubbled to solution of acetonitrile (6 mL), cyclohexene (2 mmol),
isobutylaldehyde (11 mmol),
a
l
-oxo-bisiron(III) porphyrin catalyst (0.05 ppm,
6.0 Â 10À9 mmol) and naphthalene (0.8 mmol, inert internal standard) at room
temperature. The consumption of the starting olefins and formation of
oxidized products were monitored by GC (Shimadzu GC-14C) and GC–MS
(Shimadzu GCMS-QP2010 plus).
19. (a) Guo, C. C.; Liu, Q.; Wang, X. T.; Hu, H. Y. Appl. Catal., A 2005, 282, 55–59; (b)
Zhou, X. T.; Ji, H. B.; Yuan, Q. L.; Xu, J. C.; Pei, L. X.; Wang, L. F. Chin. J. Chem.
2008, 26, 1114–1118.
20. (a) Reginato, G.; Di Bari, L.; Salvadori, P.; Guilard, R. Eur. J. Org. Chem. 2000,
1165–1171; (b) Zhao, Y. C.; Xiang, Y. Z.; Pu, L.; Yang, M.; Yu, X. Q. Appl. Catal., A
2006, 301, 176–181; (c) Elemans, J. A. A. W.; Bijsterveld, E. J. A.; Rowan, A. E.;
Nolte, R. J. M. Eur. J. Org. Chem. 2007, 751–757.
21. Zhu, S. J.; Gui, M. D.; Guo, C. C. Chem. J. Chinese U. 1989, 10, 1100–1104.
22. General procedure for the large scale catalytic epoxidation of cyclohexene.
Cyclohexene (20 mmol), isobutylaldehyde (0.11 mol), and (FeIIITPP)2O
(6.0 Â 10À9 mmol) were added to 60 mL dichloromethane in the presence of
molecular oxygen at room temperature while stirring. The crude products
were purified via column chromatography (silica geland cyclohexane as
eluting agents). After removing the solvent under reduced pressure, the pure
cyclohexene oxide was obtained with the yield of 87%.
23. TOF is commonly used to express the catalytic efficiency of the
catalyst with the definition as converted substrate (mol) per catalyst (mol)
per minute.
24. (a) Nam, W.; Kim, H. J.; Kim, S. H.; Ho, R. Y. N.; Valentine, J. S. Inorg. Chem. 1996,
35, 1045–1049; (b) Wentzel, B. B.; Alsters, P. L.; Feiters, M. C.; Nolte, R. J. M. J.
Org. Chem. 2004, 69, 3453–3464; (c) Wentzel, B. B.; Gosling, P. A.; Feiters, M. C.;
Nolte, R. J. M. J. Chem. Soc., Dalton Trans. 1998, 2241–2246.
25. (a) Song, W. J.; Seo, M. S.; George, S. D.; Ohta, T.; Song, R.; Kang, M. J.; Kitagawa,
T.; Solomon, E. I.; Nam, W. J. Am. Chem. Soc. 2007, 129, 1268–1277; (b) Nam,
W.; Lim, M. H.; Moon, S. K.; Kim, C. J. Am. Chem. Soc. 2000, 122, 10805–10809;
(c) Shimazaki, Y.; Nagano, T.; Takesue, H.; Ye, B. H.; Tani, F.; Naruta, Y. Angew.
Chem., Int. Ed. 2004, 129, 98–100.
15. (a) Guo, C. C.; Liu, X. Q.; Li, Z. P.; Guo, D. C. Appl. Catal., A 2002, 230, 53–60; (b)
Guo, C. C.; Liu, X. Q.; Liu, Y.; Liu, Q.; Chu, M. F.; Zhang, X. B. J. Mol. Catal. A 2003,
192, 289–294; (c) Guo, C. C.; Peng, Q. J.; Liu, Q.; Jiang, G. F. J. Mol. Catal. A 2003,
192, 295–302.
26. Chen, H. Y.; Ji, H. B.; Zhou, X. T.; Xu, J. C.; Wang, L. F. Catal. Commun. 2009, 10,
828–832.