Remarkable solvent, porphyrin ligand, and substrate effects on participation of multiple active oxidants in manganese(III) porphyrin catalyzed oxidation reactions

Article abstract of DOI:10.1002/chem.201202640

The participation of multiple active oxidants generated from the reactions of two manganese(III) porphyrin complexes containing electron-withdrawing and -donating substituents with peroxyphenylacetic acid (PPAA) as a mechanistic probe was studied by carrying out catalytic oxidations of cyclohexene, 1-octene, and ethylbenzene in various solvent systems, namely, toluene, CH ₂Cl₂, CH₃CN, and H₂O/CH ₃CN (1:4). With an increase in the concentration of the easy-to-oxidize substrate cyclohexene in the presence of [(TMP)MnCl] (1 a) with electron-donating substituents, the ratio of heterolysis to homolysis increased gradually in all solvent systems, suggesting that [(TMP)Mn-OOC(O)R] species 2 a is the major active species. When the substrate was changed from the easy-to-oxidize one (cyclohexene) to difficult-to-oxidize ones (1-octene and ethylbenzene), the ratio of heterolysis to homolysis increased a little or did not change. [(F₂₀TPP)Mn-OOC(O)R] species 2 b generated from the reaction of [(F₂₀TPP)MnCl] (1 b) with electron-withdrawing substituents and PPAA also gradually becomes involved in olefin epoxidation (although to a much lesser degree than with [(TMP)Mn-OOR] 2 a) depending on the concentration of the easy-to-oxidize substrate cyclohexene in all aprotic solvent systems except for CH₃CN, whereas Mn^V=O species is the major active oxidant in the protic solvent system. With difficult-to-oxidize substrates, the ratio of heterolysis to homolysis did not vary except for 1-octene in toluene, indicating that a Mn^V=O intermediate generated from the heterolytic cleavage of 2 b becomes a major reactive species. We also studied the competitive epoxidations of cis-2-octene and trans-2-octene with two manganese(III) porphyrin complexes by meta-chloroperbenzoic acid (MCPBA) in various solvents under catalytic reaction conditions. The ratios of cis- to trans-2-octene oxide formed in the reactions of MCPBA varied depending on the substrate concentration, further supporting the contention that the reactions of manganese porphyrin complexes with peracids generate multiple reactive oxidizing intermediates. Copyright

Full text of DOI:10.1002/chem.201202640

DOI: 10.1002/chem.201202640
Remarkable Solvent, Porphyrin Ligand, and Substrate Effects on
Participation of Multiple Active Oxidants in Manganese
Catalyzed Oxidation Reactions
ACHTUNGTREN(NGNU III) Porphyrin
Min Young Hyun,[a] Young Dan Jo,[a] Jun Ho Lee,[b] Hong Gyu Lee,[a] Hyun Min Park,[a]
In Hong Hwang,[a] Kyeong Beom Kim,[a] Suk Joong Lee,*[b] and Cheal Kim*[a]
Abstract: The participation of multiple
active oxidants generated from the re-
oxidize one (cyclohexene) to difficult-
to-oxidize ones (1-octene and ethylben-
zene), the ratio of heterolysis to ho-
molysis increased a little or did not
dant in the protic solvent system. With
difficult-to-oxidize substrates, the ratio
of heterolysis to homolysis did not vary
except for 1-octene in toluene, indicat-
ing that a MnV=O intermediate gener-
ated from the heterolytic cleavage of
2b becomes a major reactive species.
We also studied the competitive ep-
actions of two manganese
ACHUTGTNREN(NUG III) porACHTUNGTERNpNUGN hy-
ACHTUNGTRENNUNG
À
drawing and -donating substituents
with peroxyphenylacetic acid (PPAA)
as a mechanistic probe was studied by
carrying out catalytic oxidations of cy-
change. [(F20TPP)Mn OOC(O)R] spe-
cies 2b generated from the reaction of
[(F20TPP)MnCl] (1b) with electron-
withdrawing substituents and PPAA
also gradually becomes involved in
olefin epoxidation (although to a much
A
N
ACHTUNGTRENNUNG
in various solvent systems, namely, tol-
uene, CH2Cl2, CH3CN, and H2O/
CH3CN (1:4). With an increase in the
concentration of the easy-to-oxidize
substrate cyclohexene in the presence
of [(TMP)MnCl] (1a) with electron-do-
nating substituents, the ratio of heterol-
ysis to homolysis increased gradually in
all solvent systems, suggesting that
ACHTUNGTRENNUNG
À
lesser degree than with [(TMP)Mn
phyrin complexes by meta-chloroper-
benzoic acid (MCPBA) in various sol-
vents under catalytic reaction condi-
tions. The ratios of cis- to trans-2-
octene oxide formed in the reactions of
MCPBA varied depending on the sub-
strate concentration, further supporting
the contention that the reactions of
manganese porphyrin complexes with
peracids generate multiple reactive oxi-
dizing intermediates.
OOR] 2a) depending on the concen-
tration of the easy-to-oxidize substrate
cyclohexene in all aprotic solvent sys-
tems except for CH3CN, whereas
MnV=O species is the major active oxi-
Keywords: manganese · oxidation ·
oxido ligands · porphyrinoids · sol-
vent effects
À
[(TMP)Mn OOC(O)R] species 2a is
the major active species. When the sub-
strate was changed from the easy-to-
Introduction
bioACTHUNGETRNNUG
inorganic chemistry for the past three decades.[1] In par-
ticular, reactions of synthetic manganese porphyrin com-
plexes with various oxidants such as peracids, iodosylben-
zene (PhIO), and hydroperoxides have been extensively
studied to understand the details of the enzymatic oxidation
Understanding the structures of the reactive intermediates
responsible for oxygen atom transfer by heme and nonheme
monooxygenase enzymes and their model compounds under
catalytic oxygenation conditions has been a major goal of
reaction mechanisms.[2] Although a wide variety of bi
ACHTUNGTRENNUNGoACHTUNGTRENNUNG
AHCTUNGTRENNUNG
nese porphyrin complexes are mimicked, only recently have
the key manganese(V)–oxo porphyrin intermediates been
characterized in addition to manganese(IV)–oxo species.[3]
They were prepared at low temperature, characterized by a
variety of spectroscopic methods, and used directly in re-
[a] M. Y. Hyun, Y. D. Jo, H. G. Lee, H. M. Park, I. H. Hwang, K. B. Kim,
Prof. C. Kim
Department of Fine Chemistry
Seoul National University of Science & Technology
Seoul 139-743 (Korea)
Fax : (+82) 2-973-9149
E-mail: chealkim@snut.ac.kr
AHCTUNGTREGaNNNU ctivity studies of oxygen atom transfer reactions such as
olefin epoxidations and alkane hydroxylations.[4] In addition,
À
there is evidence that supports the involvement of Mn
[b] J. H. Lee, Prof. S. J. Lee
Department of Chemistry
Research Institute for Natural Sciences
Korea University
5 Anam-dong, Sungbuk-gu, Seoul 136-701 (Korea)
E-mail: slee1@korea.ac.kr
OOR intermediates as the reactive species in the catalytic
or stoichiometric oxygenation of hydrocarbons by heme-
containing enzymes and manganese-porphyrin complexes.[5]
However, it is not completely clear which reactive species
are responsible for oxygen atom transfer in the catalytic
oxygenation reactions and what factors influence the nature
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201202640.
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Chem. Eur. J. 2013, 19, 1810 – 1818

FULL PAPER
zoic acid (MCPBA) studied
with cis- and trans-2-octene in
manganeseACTHUNRTGNEUNG(III) porphyrin cat-
alyzed oxidations in various
solvents at room temperature.
We found from the studies that
the three active oxidants might
indeed operate simultaneously
in Mn(porphyrin) complex cat-
alyzed olefin epoxidations and
that the mechanism of oxida-
tion shares many common fea-
tures among Mn
(nonheme), and Mn(por
AHCTUNGTRENNUNG
rin) complexes.[6] Moreover,
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
the participation of multiple
active oxidants was remarkably
influenced by the solvent po-
Scheme 1. Possible reactive intermediates from the reaction of PPAA with the manganese complexes.
of the reactive intermediates in synthetic manganese por-
phyrin systems.
Quite recently, we presented strong evidence that the
multiple active oxidants, MnV=O, MnIV=O, and MnIII
OO(O)CR, operate simultaneously in olefin epoxidation via
À
manganese complexes such as Mn
ACHTUNGTRENNUNG
G
depending on the reaction conditions such as the type of re-
action solution and the concentration of the substrate
(Scheme 1).[6] In addition, it has been proposed that the
nature of solvent might significantly affect partitioning be-
À
tween heterolysis and homolysis of the O O bond of a Mn–
À
À
acylperoxo intermediate (Mn OOC(O)R), and that O O
À
bond cleavage of the Mn OOC(O)R complex might pro-
ceed predominantly by heterolytic cleavage in protic sol-
vents. Therefore, a discrete MnV=O intermediate appeared
to be the dominant reactive species in protic solvents. Fur-
thermore, we have observed close similarities between these
Scheme 2. Structures of manganeseACTHUGNETRNNU(G III) porphyrin complexes.
larity, the concentration and type of substrate, and por
ACHTUNGTRENNUNGphy-
nonheme MnIII complex systems and Mn
(saloph=salicylaldehide-o-phenylenediimne),
G
A
ACHTUNGTRENNUNG
high-valent manganese(V)–oxo intermediates unexpectedly
show a similar preference for trans-2-octene over cis-2-
octene in the competitive epoxidation of cis- and trans-2-
octene, and that the ratios of cis- to trans-oxide with two
that this simultaneous operation of the three active oxidants
might prevail in all of the manganese catalyzed olefin ep-
A
ACHUTNGTRENNUG(salen), MnACHUTNGTREN(NUGN nonheme), and even
manganese
ACHTUNGTREN(NUNG III) porphyrin complexes varied depending on
To gain insight into the proposal that the three active oxi-
dants might operate simultaneously in Mn(porphyrin) com-
plex catalyzed olefin epoxidations and to understand the ef-
the substrate concentration.
À
ficient O O bond activation in which the mechanism of oxi-
dation shares many common features among Mn(salen),
Mn(nonheme), and Mn(porphyrin) complexes, we systemat-
Results and Discussion
AHCTUNGTRENNUNG
G
In attempts to gain insight into the proposal that the simul-
taneous operation of the three active oxidants might prevail
in all manganese-catalyzed olefin epoxidations, including
ically studied the solvent, porphyrin ligand, and substrate ef-
fects on two MnIII porphyrin complexes containing electron-
withdrawing and -donating substituents, [(TMP)MnCl] (1a;
MnACTHNUTRGENNG(U salen), MnAHCTUNGTRNEN(UGN nonheme), and even Mn(porphyrin) com-
TMP=5,10,15,20-tetramesitylporphyrin)
[(F20TPP)MnCl] (1b; F20TPP=5,10,15,20-tetrakis(penta-
fluorophenyl)porphyrin) (Scheme 2), with peracids.
Herein, we report the results of product distributions of
peroxyphenylacetic acid (PPAA) used as a mechanistic
probe and competitive epoxidations by meta-chloroperben-
and
plexes,[6b] we used PPAA as a mechanistic probe along with
two MnIII porphyrin complexes containing electron-with-
drawing and -donating substituents on phenyl groups at the
meso position of the porphyrin ring, namely, [(TMP)MnCl]
(1a) and [(F20TPP)MnCl] (1b). As we showed in our previ-
ous studies,[7] heterolytic cleavage of the O O bond of
À
Chem. Eur. J. 2013, 19, 1810 – 1818
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1811

S. J. Lee, C. Kim et al.
PPAA affords phenylacetic acid (PAA, 5; pathway (a) of
tion of cyclohexene employed.[7,8] That is, direct epoxidation
À
À
Scheme 1). In contrast, when the O O bond of the coordi-
of olefin by Mn OOR species affords PAA, the heterolytic
À
nated anion of PPAA is cleaved homolytically, an acyloxyl
radical is generated (pathway (c) of Scheme 1). This acyloxyl
radical undergoes rapid b-scission (diffusion-controlled rate
ca. 109 sÀ1) to give benzaldehyde (6), benzyl alcohol (7), and
toluene (8) via the benzyl radical.[7,8] The direct reaction of
the acylperoxo intermediate and substrate affords PAA
cleavage product of the O O bond of PPAA, and would
result in an increase in the amount of heterolytic cleavage.
We increased the concentration of substrate cyclohexene
from 0 to 160 mm in the presence of catalyst 1a. The ratio of
heterolysis to homolysis increased gradually within possible
experimental error (from 69:31 for 0 mm to 73:27 for 40 mm
to 82:18 for 160 mm; Table 1, entries 1—3, fourth column,
and Table S1). Under anaerobic conditions, almost identical
yields of the products were obtained. These results suggest
À
(pathway (b) of Scheme 1), and apparently affects the O O
bond cleavage mode.
À
Substrate effect on participation of multiple active oxidants:
First, we examined the product distribution of PPAA with
[(TMP)MnCl] (1a) having electron-donating groups in the
absence of a substrate in the nonpolar solvent toluene at
room temperature. PAA was the dominant degradation
product of PPAA (65% based on PPAA; entry 1 in Table
S1),[9] with some amounts of benzaldehyde (24%) and
that [(TMP)Mn OOC(O)R] species 2a generated from the
reaction of manganese porphyrin complex 1a and peracid
also gradually becomes involved in olefin epoxidation de-
pending on the concentration of cyclohexene in the non-
A
ACHTUNGTREN(NGNU saloph) and Mn-
AHCTUNGTRENNUNG
À
benzyl alcohol (4.9%) generated from the homolytic O O
Solvent effect on participation of multiple active oxidants:
We studied the solvent effects, because it has been demon-
strated previously in MnACTHNGURTENNU(G saloph) and MnACHTUNGERTN(NUNG nonheme) com-
À
bond cleavage, demonstrating that [(TMP)Mn OOC(O)R]
species 2a generated from the reaction of 1a and PPAA un-
derwent partitioning of 69% heterolysis and 31% homolysis
(Table 1, entry 1, fourth column).[10] To further examine the
interaction between O O bond cleavage and substrate oxi-
dation, we investigated the concentration effect of an easy-
to-oxidize substrate, cyclohexene. If the Mn OOR species
(2) was involved in the epoxidation reaction, then the ratio
of heterolysis to homolysis would vary with the concentra-
plexes that the multiple oxidants, MnIII OOC(O)R (2),
MnV=O (3), and MnIV=O (4), operate simultaneously as the
key active intermediates in aprotic solvents and that
MnV=O species might become the common reactive inter-
mediate in protic solvents.[6] We used a variety of solvents
with different polarities for the detailed study, ranging from
toluene (dielectric constant: 2.4) to CH2Cl2 (dielectric con-
À
À
À
Table 1. Product distributions derived from PPAA and competitive epoxidations mediated by Mn porphyrin complexes in the absence and the presence
of substrate in various solvent systems at room temperature.[a]
Entry Solvent
(dielectric
Conc.
[(TMP)MnCl] (1a)
ACHTUNGTRENNUNG
[mm] cyclohexene 1-octene ethylbenzene cis-/trans-
constant)
octene oxide
octene oxide
1
toluene
0
2.3
(69:31)
2.8
(73:27)
4.5
(82:18)
2.4
(70:30)
3.7
(79:21)
6.3
(86:14)
2.7
(73:27)
5.9
(86:14)
11.3
(92:8)
4.8
(83:17)
8.7
(90:10)
9.7
(91:9)
23.4
(96:4)
2.3
(69:31)
2.4
(71:29)
2.6
(73:27)
2.4
(70:30)
2.6
(72:28)
3.0
(75:25)
2.7
(73:27)
3.2
(76:24)
4.3
(81:19)
4.8
(83:17)
5.6
(85:15)
5.9
(86:14)
7.1
(88:12)
2.3
(69:31)
2.5
(72:28)
2.6
(72:28)
2.4
(70:30)
2.6
(72:28)
2.4
(71:29)
2.7
(73:27)
3.2
(76:24)
3.3
(77:23)
4.8
(83:17)
5.0
(83:17)
6.7
(87:13)
6.6
(87:13)
2.7
(73:27)
4.0
(80:20)
5.3
(84:16)
2.7
(73:27)
3.1
(75:25)
5.8
(85:15)
2.6
(72:28)
2.6
(72:28)
3.1
(76:24)
45.9
(98:2)
41.1
(98:2)
35.4
(97:3)
29.7
(97:3)
2.7
(73:27)
2.8
(74:26)
3.8
(79:21)
2.7
(73:27)
2.5
(71:29)
3.0
(75:25)
2.6
(72:28)
2.2
(69:31)
2.2
(69:31)
46.1
(98:2)
32.1
(97:3)
26.4
(96:4)
26.5
(96:4)
2.7
(73:27)
2.8
(74:26)
3.1
(76:24)
2.7
(73:27)
2.5
(71:29)
2.8
(74:26)
2.6
(72:28)
2.1
(68:32)
2.6
(72:28)
46.1
(98:2)
50.0
(98:2)
34.2
(97:3)
40.0
(98:2)
A
E
N
G
N
N
ACHTUNGTRENNUNG
2
40
160
0
1.8
2.5
2.1
2.6
R
ACHTUNGTRENNUNG
3
E
ACHTUNGTRENNUNG
4
CH2Cl2
(3.1)
N
N
ACHTUNGTRENNUNG
5
40
160
0
2.3
4.4
1.9
2.2
N
ACHTUNGTRENNUNG
6
R
ACHTUNGTRENNUNG
7
CH3CN
(5.8)
T
N
ACHTUNGTRENNUNG
8
40
160
0
2.5
6.4
1.4
2.0
N
ACHTUNGTRENNUNG
9
E
ACHTUNGTRENNUNG
10
11
12
13
H2O/CH3CN (1:4)
N
ACHTUNGTRENNUNG
H2O (9.0), CH3CN (5.8) 20
40
1.9
1.0
1.1
1.7
G
ACHTUNGTRENNUNG
3.6
N
ACHTUNGTRENNUNG
160
13.0
G
ACHTUNGTRENNUNG
[a] See the Experimental Section for details; numbers in parentheses represent the hetero/homo product ratio.
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Chem. Eur. J. 2013, 19, 1810 – 1818

ManganeseACHTUNGTRENNUNG(III) Porphyrin Catalyzed Oxidation Reactions
FULL PAPER
stant: 3.1) to CH3CN (dielectric constant: 5.8) to a mixture
of H2O (dielectric constant: 9.0) and CH3CN (1:4). As
shown in Table 1, when a slightly more polar solvent
(CH2Cl2) was used instead of toluene, the partitioning of
column, and Tables S9–S12). These results demonstrate that
À
[(TMP)Mn OOC(O)R] (2a) might not be involved in the
oxidation reaction with the difficult-to-oxidize substrate eth-
ylbenzene and the major reactive species is the
[(TMP)MnV=O] intermediate 3a generated from the hetero-
lytic cleavage of 2a. Cook et al. reported a similar type of
result, namely that PhIO, PFIB (pentafluoroiodosylben-
zene), and MCPBA in a manganese porphyrin complex
yielded the same selectivity for a difficult oxidation reaction,
alkane hydroxylation, and proposed that metal-based oxida-
tion via a common intermediate, MnV=O, occurred.[13]
À
[(TMP)Mn OOC(O)R] species 2a in the absence of cyclo-
hexene was nearly identical (heterolysis vs. homolysis: 70 vs.
30; Table 1, entry 4, fourth column, and Table S2) to that in
toluene.[9] The increase in the concentration of cy
ACTHNUTRGENNUcG loHCATUNGTRENNhUGN exene
showed a similar pattern for the ratio of heterolysis to ho-
molysis as shown in toluene, but with slightly higher ratios
depending on the cyclohexene concentration (Table 1, en-
tries 4–6). In the more polar solvent CH3CN, the ratio of
heterolysis to homolyis in the absence of cyclohexene was
slightly higher (73:27 (2.7)) than in toluene and CH2Cl2 (Ta-
ble 1,entry 7).[9] Similarly, increasing the concentrations of
cyclohexene increased the ratios of heterolysis to homolysis
(Table 1, entries 7–9 and Table S3). In the most polar and
protic solvent system of the mixture H2O/CH3CN (1:4), the
Porphyrin ligand effect on participation of multiple active
oxidants: We explored the porphyrin ligand effect on the
participation of the multiple active oxidants in the presence
of a manganeseACTHNUTRGNEUNG(III) porphyrin complex ([(F20TPP)MnCl]
(1b)) containing electron-withdrawing substituents at the
meso position of the porphyrin ring. We first examined the
product distribution of PPAA with 1b in the absence of sub-
strate in the nonpolar solvent toluene at room temperature.
The ratio of heterolysis to homolysis was 2.7,[9] similar to
that obtained with [(TMP)MnCl] (1a) in toluene (Table 1,
entry 1, eighth column, and Table S13), demonstrating that
À
partitioning of [(TMP)Mn OOC(O)R] species 2a in the ab-
sence of cyclohexene gave the large value of 4.8 (Table 1,
entry 10, fourth column, and Table S4),[9] indicating 83%
heterolysis and 17% hemolysis. This result indicates that the
À
protic solvent induces the Mn OOC(O)R species to under-
À
go dominantly heterolytic cleavage. The increase in the con-
centration of cyclohexene in the mixture H2O/CH3CN (1:4)
also showed, very surprisingly, a gradual increase in the
ratios of heterolysis to homolysis with the highest value of
23.4 with 160 mm cyclohexene (Table 1, entries 10–13),
the [(F20TPP)Mn OOC(O)R] species (2b) generated from
the reaction of 1b and PPAA underwent partitioning of
73% heterolysis and 27% homolysis. Furthermore, we in-
vestigated the concentration effect for the easy-to-oxidize
substrate cyclohexene. With increasing concentration of sub-
strate cyclohexene, the ratio of heterolysis to homolysis in-
creased gradually within possible experimental error
(Table 1, entries 1–3, eighth column, and Table S13). These
À
whereas it would be expected that the heterolytic O O
À
bond cleavage of [(TMP)Mn OOR] species 2a occurs by
general-acid catalysis prior to the direct interaction between
2a and olefin in the protic solvent system.[11] Taken together,
the concentration dependence of heterolysis versus homoly-
sis in all solvent systems tested in this study suggests that
À
results suggest that [(F20TPP)Mn OOC(O)R] species 2b
generated from the reaction of peracid with [(F20TPP)MnCl]
(1b) also gradually becomes involved in olefin epoxidation
depending on the concentration of cyclohexene in the non-
polar solvent toluene. When toluene was replaced with a
slightly more polar solvent CH2Cl2, the partitioning of
À
[(TMP)Mn OOC(O)R] species 2a is a major active species
and gradually becomes involved in olefin epoxidation de-
pending on the concentration of cyclohexene.
À
In contrast, as we and others have proposed, when the
substrate is active or the concentration of the substrate is
[(F20TPP)Mn OOC(O)R] species 2b in the absence of cy-
clohexene was nearly identical (heterolysis vs. homolysis: 73
vs. 27; Table 1, entry 4, eighth column, and Table S14) to
that in toluene.[9] An increase in the concentration of cyclo-
hexene showed a very similar pattern of heterolysis to ho-
molysis to that shown in toluene (Table 1, entries 4–6). In
the more polar solvent CH3CN, the ratio of heterolysis to
homolysis in the absence of cyclohexene was also nearly
identical (72:28) to those shown in toluene and CH2Cl2.[9]
However, increasing the concentrations of cyclohexene pro-
duced little change in the ratios of heterolysis to homolysis
(Table 1, entries 7–9, and Table S15). These unexpected re-
sults seem to correlate with the previous report by Collman
et al. that the ratios of the competitive epoxidation products
of styrene and cis-cyclooctene catalyzed by [(F20TPP)MnCl]
(1b) in CH3CN are essentially identical, regardless of the
oxidants employed.[14] These observations demonstrate that
À
high, the species M OOC(O)R might gradually become in-
volved in the epoxidation reaction,[12] so we used a difficult-
to-oxidize substrate, terminal olefin 1-octene, to investigate
the cleavage mode of PPAA with catalyst 1a. Using the
same method as above, we increased the concentration of
substrate 1-octene from 0 to 160 mm in the presence of cata-
lyst 1a in toluene (see Table S5). The ratio of heterolysis to
homolysis varied a little within possible experimental error
(Table 1, entries 1–3, fifth column). These results indicate
À
that [(TMP)Mn OOC(O)R] species 2a might act a little as
an active oxidant toward the difficult-to-oxidize substrate
1-octene. Similar product ratios were observed in the other
solvent systems (Table 1, fifth column, and Tables S6–S8).
Furthermore, we changed the substrate to one that is
more difficult to oxidize, namely, ethylbenzene. The ratios
of heterolysis to homolysis varied little with an increase in
the concentration of ethylbenzene independent of the sol-
vent polarity, as shown in Table 1 (entries 1–13, sixth
À
[(F20TPP)Mn OOC(O)R] species 2b might have little in-
volvement in olefin epoxidation in the presence of a large
amount of substrate in CH3CN; at present, it is not clear
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1813

S. J. Lee, C. Kim et al.
why 2b does not act as an active oxidant toward easy-to-oxi-
dize olefins only in CH3CN. In the most polar and protic sol-
vent system, the mixture H2O/CH3CN (1:4), the partitioning
of 2b in the absence of cyclohexene gave the largest value
of 45.9,[9] indicating 98% heterolysis and 2% homolysis,
H2O/CH3CN (1:4), the highest ratio (13.0) was observed at a
concentration of 160 mm with a large increase in the ratios
(Table 1, entries 11–13). To our knowledge, the change in
the ratios of cis- and trans-oxide depending on a change in
the substrate concentration was first observed in metallopor-
phyrin-catalyzed olefin epoxidation. These results further
support the contention that the reactions of the manganese
porphyrin complexes with the peracids generate multiple re-
active epoxidizing intermediates. If the reactive intermediate
generated in the reactions of MCPBA is only one species,
then the ratios of the oxide products formed in the competi-
tive epoxidations would be the same independent of the
concentration of substrate. In addition, the increase in the
ratios of cis- and trans-2-octene oxide with increasing polari-
ty of the solvent indicates that a greater portion of
À
which means that the protic solvent pushes Mn OOC(O)R
species exclusively to undergo heterolytic cleavage to pro-
duce a discrete MnV=O intermediate as the dominant re-
ACHTUNGTRENNUNGactive species (Table 1, entry 10, eighth column, and Table
S16). In contrast, an increase in the concentration of cyclo-
hexene in the mixture H2O/CH3CN (1:4) slightly decreased
the ratio of heterolysis to homolysis (Table 1, entries 10–13),
indicating that the nonpolar substrate cyclohexene slightly
retards the heterolytic cleavage, sensitive to the polar envi-
ronment.[11]
À
To investigate the interaction between 2b and a difficult-
to-oxidize substrate, we used 1-octene. Using the same
method as above, we increased the concentration of 1-
octene in the presence of catalyst 1b in toluene. The per-
centage of heterolysis to homolysis varied a little within pos-
sible experimental error (Table 1, entries 1–3, ninth column,
and Table S17), while almost no change was observed in the
other solvent systems (Table 1 and Tables S18–S20). These
patterns indicate that there might be a small interaction be-
[(TMP)Mn OOR] species 2a among the multiple active ox-
idants, [(TMP)MnV=O] (3a), [(TMP)MnIV=O] (4a), and
[(TMP)MnIII OOR] (2a), is involved in the olefin ep-
À
oxidation with increasing polarity of the solvent. This pro-
posal also agrees well with the product distributions of
PPAA in the [(TMP)MnCl]-catalyzed epoxidation. On the
other hand, the high ratio of cis- to trans-2-octene oxide ob-
served in the [(TMP)MnCl] (1a) reaction might be attribut-
able to the steric effect of the bulky MCPBA ligand bound
to the manganese porphyrin, given that the approach of
À
tween O O bond cleavage and the 1-octene epoxidation re-
À
action in the presence of 1b only in toluene and no interac-
tion in the other solvent systems.
trans-olefin to [(TMP)Mn OOR] 2a is highly restricted by
the steric hindrance between trans-olefin and the bulky
As in the reaction of [(TMP)MnCl] (1a) with ethylben-
zene, we changed the substrate to ethylbenzene, which is
more difficult to oxidize. The ratios of heterolysis to homol-
ysis did not vary with an increase in the concentration of
ethylbenzene independent of the solvent polarity, as shown
in Table 1 (entries 1–13, tenth column, and Tables S21–S24),
MCPBA bound to manganese.[15]
When identical competitive epoxidations were carried out
with [(F20TPP)MnCl] (1b) in the same solvent systems, the
ratios of cis- to trans-2-octene oxide formed in the reactions
of MCPBA still varied with the change in the substrate con-
centration (Table 1, 11th column) but were smaller than
those of [(TMP)MnCl] (1a). These results again indicate
that the reactions of 1b with peracids generate multiple re-
active epoxidizing intermediates, at least to some extent.
The decrease in the ratios of cis- to trans-oxide depending
on the solvent polarity under the same concentration of sub-
strate (40 or 160 mm) suggests that a larger portion of
[(F20TPP)MnV=O] species (3b) among the multiple active
oxidants, [(F20TPP)MnV=O] (3b), [(F20TPP)MnIV=O] (4b),
À
suggesting that [(F20TPP)Mn OOC(O)R] 2b might not be
involved in the oxidation reaction with the difficult-to-oxi-
dize substrate ethylbenzene.
Competitive olefin epoxidation by manganese porphyrin
complexes: To examine the selectivity of cis- and trans-2-
octene by multiple oxidants,[15] we studied competitive ep-
ACHTUNGTRENNUNGoxidations with two manganeseACHTUNGTERN(NUGN III) porphyrin complexes
À
(1a and 1b) and MCPBA as an oxidant in various solvent
systems at room temperature under catalytic reaction condi-
tions. The product ratios are listed in the seventh and elev-
enth columns of Table 1 and the yields of the epoxide prod-
ucts are shown in Tables S25 and S26.
The competitive epoxidations of cis- and trans-2-octene,
which are considered to be easy-to-oxidize substrates, were
first carried out with 1a in toluene. Surprisingly, the ratios
of cis- to trans-2-octene oxide formed in the reactions of
MCPBA varied depending on the substrate concentration
(1.8 for 40 mm and 2.5 for 160 mm; Table 1, entries 2 and 3,
seventh column). When toluene was replaced with CH2Cl2,
higher ratios of cis- to trans-2-octene oxide were obtained
(Table 1, entries 5 and 6), relative to those in toluene. In
CH3CN, the ratios were even higher (Table 1, entries 8 and
9). In the most polar and protic solvent system, the mixture
and [(F20TPP)Mn OOR] (2b), is involved in the olefin ep-
A
This phenomenon is contrary to that observed with
[(TMP)MnCl] (1a). In particular, in the protic solvent of the
mixture H2O/CH3CN (1:4), the ratio of cis- to trans-2-octene
oxide is close to 1 for a low concentration of substrate
(20 mm; Table 1, entry 11, 11th column), suggesting that the
reactive intermediates formed in the protic solvent might be
predominantly the high-valent manganese(V) oxo inter-
mediates. Again, this proposal matches well with the prod-
uct distributions of PPAA in [(F20TPP)MnCl]-catalyzed ep-
oxidation in the mixture H2O/CH3CN (1:4). The slight in-
crease in the ratios of cis- to trans-2-octene oxide depending
on the substrate concentration in the mixture H2O/CH3CN
À
(1:4) indicates that [(F20TPP)Mn OOR] species 2b is also
involved in olefin epoxidation reactions in the protic solvent
1814
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ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 1810 – 1818

ManganeseACHTUNGTRENNUNG(III) Porphyrin Catalyzed Oxidation Reactions
FULL PAPER
À
system, at least to a small extent, although to a much lower
might have a shorter lifetime than [(TMP)Mn OOR] spe-
cies 2a generated from the more electron-rich Mn complex
([(TMP)MnCl]; 1a).
À
degree than with [(TMP)Mn OOR] 2a.
For comparison, we prepared dioxo-MnV
G
dioxo-MnV
(F20TPP)À, under the conditions reported recently
In an effort to prove this assumption, we measured the
pH values of 1a and 1b in the solvent system H2O/CH3CN
(1:4). The pH values of 1a and 1b were determined to be
8.4 and 6.5, respectively. These values led us to conclude
that the heterolytic O O bond cleavage of [(F20TPP)Mn
OOR] intermediate 2b gener-
by Groves and Nam and co-workers (Figure S1 and S2),[3c,d]
and carried out the competitive epoxidations of cis- and
trans-2-octene with them upon the addition of trifluoroacetic
acid (Scheme 3).[3d] Neutralization of the excess base with
À
À
ated from 1b containing the
fluorinated electron-deficient
porphyrin ligand is accelerated
by general-acid catalysis at low
pH to produce [(F20TPP)MnV=
Scheme 3. Competitive epoxidation of cis- and trans-2-octene by dioxo-MnV(TMP)À and dioxo-MnV(F20TPP)À
ACTHNUTRGENNUG CAHTUNGTRENNUGN
upon the addition of trifluoroacetic acid.
O] intermediate 3b (Scheme 4,
pathway (a-1)),[11] whereas the
À
O O
bond
cleavage
of
À
1 equivalent of trifluoroacetic acid caused an instantaneous
reaction with added cis- to trans-2-octene (1:1 mixture) at
room temperature. The ratios of cis- to trans-2-octene oxide
were found to be 1.2:1 for [(TMP)MnCl] and 1.2:1 for
[(F20TPP)MnCl] in CH2Cl2 (Tables S27 and S28).[16]
[(TMP)Mn OOR] intermediate 2a generated from 1a con-
taining a methylated electron-rich porphyrin ligand is rela-
tively retarded at high pH and 2a has a long lifetime, trans-
ferring its oxygen atom to the olefin prior to the formation
of [(TMP)MnV=O] (3a; Scheme 4, pathway (b)). This con-
clusion implies that the pH value of the active site in en-
zymes might be very important for determining the nature
of the reactive intermediates responsible for hydrocarbon
oxidations.[11,17]
It is worth noting that the intermediate of the high-valent
manganese porphyrin complexes show the same preference
for trans-olefin over cis-olefin, and, to the best of our knowl-
edge, this is the first observation of a similar preference for
trans-oxide over cis-oxide in manganese porphyrin catalyzed
competitive epoxidations of cis- and trans-2-octene, although
it has been reported in iron porphyrin catalyzed competitive
epoxidations.[15a]
Proposed mechanism for hydrocarbon oxidation by
manganese
the most plausible mechanism for the formation of the re-
active species responsible for hydrocarbon oxidation by
ACHTUNGTREN(NUNG III) porphyrin complexes: Based on our results,
Moreover, a striking observation was that the cis- to
trans-epoxide ratios and the patterns of the product distribu-
tions of PPAA obtained in the reactions of [(TMP)MnCl]
ACHTUNGTRENNUNG
manganese porphyrin complexes could be as shown in
Scheme 4. The peracid reacts with a manganese complex to
À
(1a) and [(F20TPP)MnCl] (1b) in the presence of cy
N
form an iniACTHNGUTERNNUG
tial Mn–acylperoxo intermediate ([MnIII
N
OOC(O)R] (2)), which then undergoes either a heterolytic
V
À
(Table 1). This difference could possibly be explained by the
or hemolytic O O bond cleavage to afford Mn =O (3) or
À
lifetime of Mn OOR intermediates 2 generated from the
MnIV=O (4) species, or which transfers its oxygen atom di-
two manganese porphyrin complexes 1a and 1b with differ-
rectly to the substrate. In the absence of a substrate,
À
À
ent electronic properties, assuming that [(F20TPP)Mn
OOR] species 2b generated from the more electron-defi-
cient manganese porphyrin complex ([(F20TPP)MnCl]; 1b)
[(TMP)Mn OOR] (2a) intermediate generated from the
manganese porphyrin complex 1a having electron-donating
groups in aprotic solvents is cleaved both heterolytically
Scheme 4. Plausible mechanism for the formation of the reactive intermediates responsible for the hydrocarbon oxidations from the reaction of peracids
with the manganese porphyrin complexes.
Chem. Eur. J. 2013, 19, 1810 – 1818
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
1815

S. J. Lee, C. Kim et al.
(ca. 70%) and homolytically (ca. 30%) to form high-valent
manganese(V)–oxo species 3a (pathway (a)) and high-
valent manganese(IV)–oxo species 4a (pathway (c)). The
dation reactions. More detailed mechanistic studies to eluci-
date the factors that influence the partitioning of heterolysis
À
versus homolysis and the lifetime of the (porphyrin)Mn
OOR intermediate are currently underway in this laborato-
ry.
À
O O bond cleavage of 2a was shifted more to heterolysis
(83%) in the protic solvent. In the presence of an easy-to-
À
oxidize substrate, [(TMP)Mn OOR] 2a with a relatively
long lifetime reacts directly with the easy-to-oxidize sub-
strate (pathway (b)) as a major pathway to give a high ratio
of cis- to trans-oxide, whereas the partitioning of heterolytic
Experimental Section
À
and homolytic O O bond cleavage prevails in the presence
of a difficult-to-oxidize substrate. When the manganese por-
General: Cyclohexene, 1-octene, ethylbenzene, cis-2-octene, trans-2-
octene, cyclohexene oxide, 1-octene oxide, cyclohexenol, cyclohexenone,
acetophenone, sec-phenethyl alcohol, absolute toluene, mesitylaldehyde,
2,3,4,5,6-pentafluorobenzaldehyde, propionic acid, pyrrole, potassium car-
phyrin complex 1b having electron-withdrawing groups is
used as a catalyst in the absence of substrate, [(F20TPP)Mn
OOR] (2b) intermediate generated from 1b with peracid in
aprotic solvents is also cleaved both heterolytically
(ca. 73%) and homolytically (ca. 27%), similar to the obser-
vation with [(TMP)MnCl] (1a), resulting in the formation of
high-valent manACHTUNGTRENNUNGgaACHTUNGTRENNUNGnese(V)–oxo species 3b (pathway (a-1))
and high-valent manganese(IV)–oxo species 4b (pathway
(c-1)). In addition, the O O bond cleavage of 2b was shift-
À
bonate,
hexane, absolute methylene chloride, absolute acetonitrile, DMF, chloro-
form, trifluoroacetic acid, Mn(OAc)2, MgSO4, Na2SO4, and MCPBA
2,3-dichloro-5,6-dicyano-1,4-benzoquinone,
triethylamine,
AHCTUNGTRENNUNG
(65%) were purchased from Aldrich Chemical Co. and were used with-
out further purification. Peroxyphenylacetic acid (PPAA) was synthe-
sized according to the literature method.[6,7] Manipulations of the por-
phyrins were carried out under N2 with the use of standard inert-at
ACHTUNGTRENNUNGmo-
AHCTUNGERTGsNNUN phere and Schlenk techniques unless otherwise noted. Solvents used in
À
inert-atmosphere reactions were dried and degassed using standard pro-
cedures. Flash column chromatography was carried out with 230–400
mesh silica gel from Sigma–Aldrich using the wet-packing method. All
deuterated solvents were purchased from Cambridge Isotope Laboratory.
ed much more to heterolysis (98%) by the general-acid cat-
alysis in the protic solvent. In the presence of an easy-to-oxi-
dize substrate, somewhat differently, a small portion of
À
Instruments: Product analyses for oxidation reactions and partition reac-
tions of PPAA were performed on either a Hewlett–Packard 5890 II Plus
gas chromatograph interfaced with Hewlett–Packard Model 5989B mass
spectrometer or a Donam Systems 6200 gas chromatograph equipped
with a FID detector using a 30 m capillary column (Hewlett–Packard,
DB-5 or HP-FFAP). NMR spectra were recorded on a Varian AS400
(399.937 MHz for 1H and 100.573 MHz for 13C) spectrometer. 1H chemi-
cal shifts are referenced to the proton resonance resulting from protic
residue in deuterated solvent and 13C chemical shift recorded downfield
in ppm relative to the carbon resonance of the deuterated solvents. Ab-
sorbance and emission spectra were obtained using an Agilent UV/Vis/
NIR spectrophotometer using quartz cells. Matrix-assisted laser-desorp-
tion-ionization time-of-flight mass spectra (MALDI-TOF) were obtained
on a Bruker Daltonics LRF20 MALDI-TOF mass spectrometer at the
Industry-Academic Cooperation Foundation.
[(F20TPP)Mn OOR] 2b with a relatively short lifetime
reacts directly with the easy-to-oxidize substrate (pathway
(b-1)) and a large portion of it undergoes partitioning of
À
heterolytic and homolytic O O bond cleavage in aprotic
solvents, whereas in a protic solvent, the heterolytic O O
bond cleavage of 2b occurs exclusively to produce high-
valent manganese(V)–oxo species 3b that show a ratio of
cis- to trans-oxide close to 1 (pathway (a-1)). With the diffi-
cult-to-oxidize substrate, the partitioning of heterolytic and
À
À
homolytic O O bond cleavage of 2b occurs in the aprotic
À
solvents and its heterolytic O O bond cleavage occurs ex-
clusively in the protic solvent system.
This proposed mechanism based on our experimental
data reminds us that “detection of a particular active oxi-
dant under selected conditions will not necessarily demon-
strate the identity of the active oxidant under catalytic turn-
over conditions”, as Newcomb and co-workers stated.[4a]
Synthesis of tetramesitylporphyrin (TMP): Tetramesitylporphyrin was
synthesized by modified literature procedures.[18] Under a nitrogen at-
mosphere, mesitylaldehyde (4 mL, 27.1 mmol) and freshly distilled pyr-
role (1.9 mL, 27.1 mmol) were dissolved in chloroform (500 mL) in a 1 L
round-bottomed flask equipped with a magnetic stirbar. The mixture was
degassed for 10 min followed by an injection of boron trifluoride diethyl
etherate (0.24 mL, 1.98 mmol) into the reaction solution by syringe. The
reaction mixture was stirred at room temperature for 3 h under N2. 2,3-
Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 1 g) was introduced to
the reaction mixture and the resulting mixture was heated at reflux for a
further 1 h. After cooling, triethylamine (0.33 mL) was injected by sy-
ringe and stirred for 10 min. The crude reaction mixture was evaporated
to dryness using a rotary evaporator and the residue was purified by
silica-gel column chromatography (methylene chloride/hexane 1:2 v/v) to
afford pure TMP as a purple solid (635 mg, 11.0%). 1H NMR (400 MHz,
CDCl3): d=8.62 (s, 8H), 7.3 (s, 8H), 2.61 (s, 12H), 1.85 (s, 24H),
À2.50 ppm (s, 2H). 13C NMR (100 MHz, CDCl3): d=140.8, 134.4, 134.1,
133.1, 131.9, 121.1, 32.0, 21.9 ppm. MS (MALDI-TOF): m/z=781.87 for
[M+]; calcd 783.05.
Conclusion
Our results demonstrate that the participation of the multi-
ple active oxidants MnV=O, MnIV=O, and MnIII OO(O)CR
À
in hydrocarbon oxidation reactions by manganese porphyrin
complexes is markedly affected by several factors, such as
the solvent polarity, the concentration and type of substrate,
and the porphyrin ligands. Moreover, the O O bond activa-
tion mechanism shares many common features among Mn-
À
ACHTUNGTRENNUNG(salen), MnACHTUNGTRENNUNG(nonheme), and Mn(porphyrin) complexes. The
Synthesis of tetrakis(pentafluorophenyl)porphyrin (F20TPP): Tetrakis-
AHCTUNGERTG(NNUN pentafluorophenyl)porphyrin was synthesized by modified literature
results presented in this study not only may provide some
useful information for understanding the mechanisms of the
procedures.[18] 2,3,4,5,6-Pentafluorobenzaldehyde (1 g, 5.1 mmol) and pyr-
role (0.342 g, 5.1 mmol) were dissolved in propionic acid (25 mL) in a
100 mL round-bottomed flask equipped with a magnetic stirbar and a
water-cooled reflux condenser. The mixture was then allowed to reflux
for 2.5 h under air. After cooling, the reaction mixture was evaporated to
À
O O bond activation of peracids and hydroperoxides by
manganese porphyrin complexes, but also further support
the hypothesis of multiple oxidants in enzyme-catalyzed oxi-
1816
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Chem. Eur. J. 2013, 19, 1810 – 1818

ManganeseACHTUNGTRENNUNG(III) Porphyrin Catalyzed Oxidation Reactions
FULL PAPER
dryness using a rotary evaporator to yield a dark residue, which was dis-
solved in methylene chloride. The resulting solution was washed with
aqueous potassium carbonate (0.1m) and water (50 mL). The organic
layer was dried over anhydrous magnesium sulfate and evaporated to
dryness using a rotary evaporator. The resulting residue was purified by
silica-gel column chromatography (methylene chloride/hexane 1:3 v/v) to
the Ministry of Education, Science and Technology (2012001725,
2011 K000675, and 2012008875), and the Korea Research Foundation
Program (20120002285 and 20120005860) is gratefully acknowledged. We
thank Prof. J. T. Groves (Princeton University) for helpful discussion.
afford pure F20TPP as
a
purple solid (200 mg, 16.0%). 1H NMR
(400 MHz, CDCl3): d=8.92 (s, 8H), À1.53 ppm (s, 2H). HRMS
[1] a) B. Meunier, Chem. Rev. 1992, 92, 1411–1456; b) I. G. Denisov,
T. M. Makris, S. G. Sligar, I. Schlichting, Chem. Rev. 2005, 105,
2253–2277; c) P. R. Ortiz de Montellano, Ed. Cytochrome P450
Structure, Mechanism, and Biochemistry 3rd ed.; Kluwer Academic/
Plenum: New York, 2005; d) P. R. Ortiz de Montellano, Chem. Rev.
2010, 110, 932–948; e) J. T. Groves, J. Inorg. Biochem. 2006, 100,
434–447; f) M. Costas, Coord. Chem. Rev. 2011, 255, 2912–2932;
g) W. Liu, J. T. Groves, J. Am. Chem. Soc. 2010, 132, 12847–12849;
h) S. H. Kim, H. Park, M. S. Seo, M. Kubo, T. Ogura, J. Klajn, D. T.
Gryko, J. S. Valentine, W. Nam, J. Am. Chem. Soc. 2010, 132,
14030–14032; i) J. Annaraj, J. Cho, Y.-M. Lee, S. Y. Kim, R. Latifi,
S. P. de Visser, W. Nam, Angew. Chem. 2009, 121, 4214–4217;
Angew. Chem. Int. Ed. 2009, 48, 4150–4153; j) T. P. Umile, J. T.
Groves, Angew. Chem. 2011, 123, 721–724; Angew. Chem. Int. Ed.
2011, 50, 695–698; k) M. Costas, M. P. Mehn, M. P. Jensen, L.
Que, Jr., Chem. Rev. 2004, 104, 939–986; l) E. Y. Tshuva, S. J. Lip-
pard, Chem. Rev. 2004, 104, 987–1012; m) S. V. Kryatov, E. V.
Rybak-Akimova, Chem. Rev. 2005, 105, 2175–2226; n) M. New-
comb, R. Zhang, R. E. P. Chandrasena, J. A. Halgrimson, J. H.
Horner, T. M. Makris, S. G. Sligar, J. Am. Chem. Soc. 2006, 128,
4580–4581; o) W. Nam, Acc. Chem. Res. 2007, 40, 522–531; p) D.
Dolphin, T. G. Traylor, L. Y. Xie, Acc. Chem. Res. 1997, 30, 251–
259; q) C. Kim, Y. Watanabe, in Encyclopedia of Catalysis 2002,
Wiley, New York, pp. 593–643; r) R. Zhang, M. Newcomb, Acc.
Chem. Res. 2008, 41, 468–477; s) P. H. Toy, M. Newcomb, M. J.
Coon, A. D. N. Vaz, J. Am. Chem. Soc. 1998, 120, 9178–9179; t) S.
Shaik, W. Lai, H. Chen, Y. Wang, Acc. Chem. Res. 2010, 43, 1154–
1165; u) A. S. Borovik, Chem. Soc. Rev. 2011, 40, 1870–1874.
[2] a) J. P. Collman, J. I. Brauman, B. Meunier, T. Hayashi, T. Kodadek,
S. A. Raybuck, J. Am. Chem. Soc. 1985, 107, 2000–2005; b) B. Meu-
nier, E. Guilmet, M.-E. De Carval, R. Poilblanc, J. Am. Chem. Soc.
1984, 106, 6668–6676; c) J. A. Smegal, B. C. Schardt, C. L. Hill, J.
Am. Chem. Soc. 1983, 105, 3510–3515; d) L.-C. Yuan, T. C. Bruice,
J. Am. Chem. Soc. 1986, 108, 1643–1650; e) E. Porhiel, A. Bondon,
J. Leroy, Eur. J. Inorg. Chem. 2000, 1097–1105; f) E. Baciocchi, T.
Boschi, L. Cassioli, C. Galli, L. Jaquinod, A. Lapi, R. Paolesse,
K. M. Smith, P. Tagliatesta, Eur. J. Org. Chem. 1999, 3281–3286;
g) J. P. Collman, T. Kodadek, J. I. Brauman, J. Am. Chem. Soc. 1986,
108, 2588–2594; h) P. Battioni, J. P. Renaud, J. F. Bartoli, M. Reina-
Artiles, M. Fort, D. Mansuy, J. Am. Chem. Soc. 1988, 110, 8462–
8470.
[3] a) J. T. Groves, J. Lee, S. S. Marla, J. Am. Chem. Soc. 1997, 119,
6269–6273; b) W. Nam, I. Kim, M. H. Lim, H. J. Choi, J. S. Lee,
H. G. Jang, Chem. Eur. J. 2002, 8, 2067–2071; c) W. J. Song, M. S.
Seo, S. D. George, T. Ohta, R. Song, M.-J. Kang, T. Tosha, T. Kitaga-
wa, E. I. Solomon, W. Nam, J. Am. Chem. Soc. 2007, 129, 1268–
1277; d) N. Jin, M. Ibrahim, T. G. Spiro, J. T. Groves, J. Am. Chem.
Soc. 2007, 129, 12416–12417; e) Z. Gross, Angew. Chem. 2008, 120,
2777–2779; Angew. Chem. Int. Ed. 2008, 47, 2737–2739; f) J. T.
Groves, M. K. Stern, J. Am. Chem. Soc. 1988, 110, 8628–8638;
g) M. E. Crestoni, S. Fornarini, F. Lanucara, Chem. Eur. J. 2009, 15,
7863–7866; h) J. Y. Lee, Y.-M. Lee, H. Kotani, W. Nam, S. Fukuzu-
mi, Chem. Commun. 2009, 704–706.
[4] a) R. Zhang, J. H. Horner, M. Newcomb, J. Am. Chem. Soc. 2005,
127, 6573–6582; b) C. Arunkumar, Y.-M. Lee, J. Y. Lee, S. Fukuzu-
mi, W. Nam, Chem. Eur. J. 2009, 15, 11482–11489; c) R. Latifi, L.
Tahsini, B. Karamzadeh, N. Safari, W. Nam, S. P. de Visser, Arch. Bi-
ochem. Biophys. 2011, 507, 4–13; d) J. Bernadou, A.-S. Eabiano, A.
Robert, B. Meunier, J. Am. Chem. Soc. 1994, 116, 9375–9376; e) R.
Zhang, M. Newcomb, J. Am. Chem. Soc. 2003, 125, 12418–12419.
[5] a) S.-E. Park, W. J. Song, Y. O. Ryu, M. H. Lim, R. Song, K. M.
Kim, W. Nam, J. Inorg. Biochem. 2005, 99, 424–431; b) J. T. Groves,
(MALDI-TOF): m/z calcd: 974.55 [M+]; found: 973.14.
Synthesis of (tetramesitylporphyrinato)manganeseACTHUNGTREN(NUNG III) chloride (1a): A
solution of TMP (235 mg, 0.3 mmol) and Mn(OAc)2 (1.47 g, 6 mmol) in
AHCTUNGTRENNUNG
DMF (120 mL) was heated to reflux for 6 h. The reaction mixture was
evaporated to dryness using a rotary evaporator. The resulting mixture
was dissolved in methylene chloride and treated with 10% aqueous HCl
at room temperature for 10 min. The organic layer was separated, dried
over Na2SO4, filtered and concentrated to dryness using a rotary evapora-
tor. The resulting solid was purified by alumina column chromatography
(methylene chloride/hexane 1:1 v/v) to afford pure 1a as a dark brown
solid (214 mg, 82.0%). HRMS (MALDI-TOF): m/z calcd: 1009.00
[MÀCl]+; found: 1009.31.
Synthesis of {tetrakis(pentafluorophenyl)porphyrinato}manganese
ACHTUNGTNER(NUNG III)
chloride (1b): A solution of F20TPP (300 mg, 0.308 mmol) and Mn(OAc)2
AHCTUNGTRENNUNG
(230 mg, 0.924 mmol) in DMF (120 mL) was heated to reflux for 4 h
under air. The reaction mixture was evaporated to dryness using a rotary
evaporator. The resulting mixture was dissolved in methylene chloride
and treated with 10% aqueous HCl at room temperature for 10 min. The
solution was washed with water and organic layer was collected. The sol-
ution was dried over MgSO4. After evaporation of solvent, the solid was
purified by silica-gel column chromatography (methylene chloride/
MeOH 9:1 v/v) to afford pure 1b as
a dark brown solid. HRMS
(MALDI-TOF): m/z calcd: 1024.47 [MÀCl]+; found: 1023.31.
À
Analysis of the O O bond cleavage products from the oxidation reac-
tions of substrates by MnIII porphyrin complexes with PPAA: To a mix-
ture of substrate (0–0.16 mmol), the MnIII porphyrin complex (1.0ꢁ
10À3 mmol), and solvent (1 mL) was added PPAA (0.04 mmol). The mix-
ture was stirred for 10 min at room temperature. Each reaction was
monitored by GC/MS analysis of 20 mL aliquots withdrawn from the re-
action mixture. All reactions were run at least in triplicate and the aver-
age product yields are presented. Product yields were based on substrate
or PPAA.
Competitive reactions of cis-2-octene and trans-2-octene by manganese-
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
(0.04 mmol). The mixture was stirred for 10 min at room temperature.
Each reaction was analyzed by GC/MS analysis of 20 mL aliquots with-
drawn from the reaction mixture. All reactions were run at least in tripli-
cate and the average product yields are pre
based on substrate or MCPBA.
ACHTUNGTNERsNUNG ented. Product yields were
Competitive reactions of cis-2-octene and trans-2-octene by dioxo-MnV-
A
ACHTUNGTRENNUNG
À
acid: A solution of (TMP)MnV(O)2 (3.0ꢁ10À3 mmol) was prepared by
reacting (TMP)MnIIICl (3.0ꢁ10À3 mmol) with 1 equiv MCPBA in the
presence of 20 equiv TBAH in CH2Cl2 (1 mL) at room temperature.
After cis-2-octene (0.3 mmol) and trans-2-octene (0.3 mmol) were added
to the reaction solution, it was stirred for 5 min at room temperature.
Then, trifluoroacetic acid (6.0ꢁ10À2 mmol) was added to the mixture.
The same method was used to make dioxo-MnV
were run at least in triplicate and the average product yields are present-
ed. Product yields were based on manganese(III) porphyrin.
(F20TPP)À. All reactions
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
Acknowledgements
Financial support from the Converging Research Center Program
through the National Research Foundation of Korea (NRF) funded by
Chem. Eur. J. 2013, 19, 1810 – 1818
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
1817

S. J. Lee, C. Kim et al.
Y. Watanabe, T. J. McMurry, J. Am. Chem. Soc. 1983, 105, 4489–
4490.
117, 6691–6697; d) Y. Watanabe, K. Yamaguchi, I. Morishima, K.
Takehiro, M. Shimizu, T. Hayakawa, H. Orita, Inorg. Chem. 1991,
30, 2581–2582; e) W. Adam, K. J. Roschmann, C. R. Saha-Moller,
D. Seebach, J. Am. Chem. Soc. 2002, 124, 5068–5073; f) J. P. Coll-
man, L. Zeng, J. I. Brauman, Inorg. Chem. 2004, 43, 2672–2679;
g) K. P. Bryliakov, D. E. Babushkin, E. P. Talsi, J. Mol. Catal. A J.
Mol. Catal. A: Chem. 2000, 158, 19–35; h) A. Mahammed, Z. Gross,
J. Am. Chem. Soc. 2005, 127, 2883–2887; i) R. V. Ottenbacher, K. P.
Bryliakov, E. P. Talsi, Inorg. Chem. 2010, 49, 8620–8628; j) A.
Kumar, I. Goldberg, M. Botoshansky, Y. Buchman, Z. Gross, J. Am.
Chem. Soc. 2010, 132, 15233–15245; k) I. Garcia-Bosch, A. Compa-
ny, X. Fontrodona, X. Ribas, M. Costas, Org. Lett. 2008, 10, 2095–
2098; l) M. Newcomb, P. H. Toy, Acc. Chem. Res. 2000, 33, 449–455;
m) T. Tano, M. Z. Ertem, S. Yamaguchi, A. Kunishita, H. Sugimoto,
N. Fujieda, T. Ogura, C. J. Cramer, S. Itoh, Dalton Trans. 2011, 40,
10326.
[6] a) S. H. Lee, L. Xu, B. K. Park, Y. V. Mironov, S. H. Kim, Y. J. Song,
C. Kim, Y. Kim, S. J. Kim, Chem. Eur. J. 2010, 16, 4678–4685;
b) Y. J. Song, S. H. Lee, H. M. Park, S. H. Kim, H. G. Goo, G. H.
Eom, J. H. Lee, M. S. Lah, Y. Kim, S.-J. Kim, J. E. Lee, H.-I. Lee, C.
Kim, Chem. Eur. J. 2011, 17, 7336–7344.
[7] a) S. H. Lee, J. H. Han, H. Kwak, S. J. Lee, E. Y. Lee, H. J. Kim,
J. H. Lee, C. Bae, S. N. Lee, Y. Kim, C. Kim, Chem. Eur. J. 2007, 13,
9393–9398; b) Y. J. Song, M. Y. Hyun, J. H. Lee, H. G. Lee, J. H.
Kim, S. P. Jang, J. Y. Noh, Y. Kim, S.-J. Kim, S. J. Lee, C. Kim,
Chem. Eur. J. 2012, 18, 6094–6101; c) M. Y. Hyun, S. H. Kim, Y. J.
Song, H. G. Lee, Y. D. Jo, J. H. Kim, I. H. Hwang, J. Y. Noh, J.
Kang, C. Kim, J. Org. Chem. 2012, 77, 7307–7312.
[8] N. Suzuki, T. Higuchi, T. Nagano, J. Am. Chem. Soc. 2002, 124,
9622–9628.
[9] As it was reported that manganese porphyrin periodate system cata-
lyzed oxidative decarboxylation of aryl-substituted carboxylic acids
(S. Tangestaninejad, V. J. Mirkhani, J. Chem. Res. (S) 1998, 820–
821), we examined the oxidative decarboxylations of aryl carboxylic
acid (PAA) generated from the heterolytic cleavage of PPAA under
our reaction conditions. The oxidative decarboxylations of PAA
(40 mm) with 1a and 1b (1 mm) by MCPBA (40 mm) produced only
trace amounts of benzyl alcohol (less than 1%) in the absence of
substrate in CH2Cl2, CH3CN, and the mixture H2O/CH3CN (1:4).
[10] A similar product distribution (heterolysis/homolysis=63:37) from
the reaction of [(TMP)MnOH] with PPAA in the presence of
1 equivalent of base in CH2Cl2 was reported by Groves and Wata-
nabe: J. T. Groves, Y. Watanabe, Inorg. Chem. 1986, 25, 4808–4810.
[11] a) W. Nam, H. J. Han, S.-Y. Oh, Y. J. Lee, M.-H. Choi, S.-Y. Han, C.
Kim, S. K. Woo, W. Shin, J. Am. Chem. Soc. 2000, 122, 8677–8684;
b) J. T. Groves, Y. Watanabe, J. Am. Chem. Soc. 1986, 108, 7834–
7836; c) J. T. Groves, Y. Watanabe, J. Am. Chem. Soc. 1986, 108,
7836–7837; d) I. V. Khavrutskii, D. G. Musaev, K. Morokuma, Inorg.
Chem. 2005, 44, 306–315; e) T. G. Traylor, S. Tsuchiya, Y. S. Byun,
C. Kim, J. Am. Chem. Soc. 1993, 115, 2775–2781; f) L. C. Yuan,
T. C. Bruice, Inorg. Chem. 1985, 24, 986–987; g) T. G. Traylor, J. P.
Ciccone, J. Am. Chem. Soc. 1989, 111, 8413–8420; h) N. Jin, D. E.
Lahaye, J. T. Groves, Inorg. Chem. 2010, 49, 11516–11524.
[13] B. R. Cook, T. J. Reinert, K. S. Suslick, J. Am. Chem. Soc. 1986, 108,
7281–7286.
[14] J. P. Collman, L. Zeng, R. A. Decrꢂau, Chem. Commun. 2003, 2974–
2975.
[15] a) W. Nam, M. H. Lim, H. J. Lee, C. Kim, J. Am. Chem. Soc. 2000,
122, 6641–6647; b) J. P. Collman, L. Zeng, H. J. H. Wang, A. Lei,
J. I. Brauman, Eur. J. Org. Chem. 2006, 2707–2714.
[16] Competitive epoxidations of cis-2-octene and trans-2-octene by
dioxo-MnV(TMP)À and dioxo-MnV(F20TPP)À upon the addition of
ACTHNUTRGENNUG CAHTUNGTRENNUGN
trifluoroacetic acid were not carried out in MeCN and a mixture of
H2O/CH3CN (1:4), because clear dioxo-MnV(porphyrin)À species
were not formed in these solvent systems.
[17] a) J. H. Dawson, Science 1988, 240, 433–439; b) M. Sono, M. P.
Roach, E. D. Coulter, J. H. Dawson, Chem. Rev. 1996, 96, 2841–
2887; c) I. Schlichting, J. Berendzen, K. Chu, A. M. Stock, S. A.
Maves, D. E. Benson, R. M. Sweet, D. Ringe, G. A. Petsko, S. G.
Sligar, Science 2000, 287, 1615–1622.
[18] a) J. S. Lindsey, R. W. Wagner, J. Org. Chem. 1989, 54, 828–836;
b) L. Kaustov, M. E. Tal, A. I. Shames, Z. Gross, Inorg. Chem. 1997,
36, 3503–3511; c) H. C. Sacco, Y. Iamamoto, J. R. Lindsay Smith, J.
Chem. Soc. Perkin Trans. 2 2001, 2, 181–190; d) H. Tamiaki, N. Mat-
sumoto, S. Unno, S. Shinoda, H. Tsukube, Inorg. Chim. Acta 2000,
302, 243–249.
[12] a) A. Franke, C. Fertinger, R. van Eldik, Angew. Chem. 2008, 120,
5316–5320; Angew. Chem. Int. Ed. 2008, 47, 5238–5242; b) W. Nam,
R. Ho, J. S. Valentine, J. Am. Chem. Soc. 1991, 113, 7052–7054;
c) K. Machii, Y. Watanabe, I. Morishima, J. Am. Chem. Soc. 1995,
Received: July 25, 2012
Revised: September 28, 2012
Published online: November 23, 2012
1818
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Chem. Eur. J. 2013, 19, 1810 – 1818