Structure and asymmetric epoxidation reactivity of chiral Mn(III) salen catalysts modified by different axial anions

Article abstract of DOI:10.1039/c5ra13178b

A series of chiral Mn(iii) catalysts [salen-Mn(iii)][X] (X^- = Cl^-, OAc^-, NO₃^-, BF₄^-, CF₃SO₃^-, OCH₂CH₃^-) were synthesized by ion exchange. The influence of the axial anion on both the electronic structure and steric configuration of [salen-Mn(iii)][X] were carefully investigated. Besides, the reactivity and enantioselectivity of these catalysts were explored in the asymmetric epoxidation of olefins. The obtained results indicate that the axial anions have influences on both electronic structure and steric configuration of the chiral Mn(iii) salen complexes. Controlling the reactivity and enantioselectivity of these chiral Mn(iii) salen complexes can be achieved by changing the axial anions.

Full text of DOI:10.1039/c5ra13178b

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Graphical abstract：
The axial anions influence the electronic structure, steric configuration, and
enantioselectivity of the chiral Mn(III) salen complexes.

Please Rd So Cn oA tda vd aj un sc te ms argins
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Journal Name
ARTICLE
Structure and asymmetric epoxidation reactivity of chiral Mn(III)
salen catalysts modified by different axial anions
Received 00th January 20xx,
Accepted 00th January 20xx
Xiuxing Xi, Jing Shao, Xingbang Hu*, and Youting Wu*
-
-
-
-
-
-
-
DOI: 10.1039/x0xx00000x
3 4 3 3 2 3
A series of chiral Mn(III) catalysts [salen-Mn(III)][X] (X =Cl , OAc , NO , BF , CF SO , OCH CH ) were synthesized by ion
exchange. The influence of the axial anion on both the electronic structure and steric configuration of [salen-Mn(III)][X]
were carefully investigated. Besides, the reactivity and enantioselectivity of these catalysts were explored in the
asymmetric epoxidation of olefins. The obtained results indicate that the axial anions have influences on both electronic
structure and steric configuration of the chiral Mn(III) salen complexes. Controlling the reactivity and enantioselectivity of
these chiral Mn(III) salen complexes can be achieved by changing the axial anions.
www.rsc.org/
29-37
conformations
. These findings suggest the strong ability of
Introduction
The asymmetric epoxidation of olefins is an extremely
important and powerful reaction for the synthesis of chiral
counterion with big bulk to influence the asymmetric catalysis.
Most of the chiral metal (Cr, Mn, Co, or Cu) salen complexes,
including the well-known Jacobsen catalyst, have quite small
-
-
-
-
-
1
-7 counterion (such as Cl , OAc , NO
3
, BF
. The influence of these small counterions
on the electronic structure has received much research
4 3 3
, CF SO , and
intermediates in the pharmaceutical and agrochemical fields .
-
8-14,18,38-41
CH CH O )
3
2
Jacobsen et al. had reported that the chiral Mn(III) salen
complexes with chloride ion connecting to the mental center
could efficiently catalyze the asymmetric epoxidation of
8
-14,18,38-42
attention
. What is the influence of these axial anions
8-14
on the reactivity and enantioselectivity of chiral salen catalysts?
Recently, Kurahashi et al. found that the small axial anions
could obviously change the steric configuration of chiral salen-
olefins . As a kind of homogeneous catalysts, the chiral
Mn(III) salen complexes show quite good catalytic activity and
enantioselectivity.
43,44
Mn(IV) compound
. However, it still remained unclear
In order to further improve their activity and enantioselecti-
vity, intense efforts have been made to modify the chiral metal
about the influence of these small counterions on the
V
structure of Mn =O active intermediate and the
(Cr, Mn, Co, or Cu) salen complexes. Among the various
19-21,44-46
enantioselectivity of the chiral salen catalysts
.
methods that have been reported, modifying the salicylidene
rings of the metal-salen catalysts with functional group is
considered as an effective method to produce compounds
with high enantioselectivity
introducing different substituents at the 3,3’- and 5,5’-
positions of the salen unit, such as bulked triethylaminomethyl,
methylimidazolium , triphenyl phosphine . Moreover, an
increasing number of studies have been focusing on the
substituent of the cyclohexyl on the structure of the
Herein, the influence of the axial anions on the electronic
structure and steric configuration of [salen-Mn(III)][X] and its
V
1
5-20
Mn =O active intermediate were investigated. Besides, the
. The most established one is
reactivity and enantioselectivity of these catalysts were
explored in the asymmetric epoxidation of olefins.
1
5
18
Results and discussion
2
1-25
Influence of axial anions on the structure of chiral Mn(III) salen
catalysts
metalsalen complexes
. Besides, macrocyclic chiral metal
salen complexes possessing achiral and chiral linkers were
introduced for enantioselective reactions to obtain higher
catalytic activity and enantioselectivity relative to the
The chiral Mn(III) salen compounds were synthesized
8
-14
4
,26-28
according to the well-known procedures
and catalysts with
monomeric counterparts
.
different anions were obtained by ion exchange (Scheme 1).
These compounds were characterized by FT-IR, MS, elemental
analysis and UV-vis spectroscopy.
As we know, the IR frequency and UV-vis absorption band
can be used as an indicator for the slight change of electronic
structure. The C=N groups in different [salen-Mn(III)][X], which
participate in coordination with manganese, have different IR
An exciting new progress is that asymmetric counterion-
directed catalysis (ACDC) is used as a general strategy for
asymmetric synthesis and it has been revealed that a chiral
counterion could induce a preference for enantiomorphic
School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093,
P. R. China. E-mail: huxb@nju.edu.cn; ytwu@nju.edu.cn. Tel: +86 2583 596665
This journal is © The Royal Society of Chemistry 20xx
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DOI: 10.1039/C5RA13178B
CHO
N
N
OH
2
H N
NH
2
V
Table 2. Structural parameters for complexes [Mn =O(salen)][X]
t-Bu
OH HO
t-Bu t-Bu
t-Bu
-
-
-
-
-
-
- a
(H
3
C)
3
C
3 3
C(CH )
(
X =Cl , OAc , NO , BF , CF SO and CH CH O ) .
3
4
3
3
3
2
salen-1
X=Cl
X=AcO
X=NO3
X=BF4
X=CH CH O
3 2
N
O
N
O
AgX or
Mn
Cl
Mn(OAC)
2
4H O
CH
3
CH
2
ONa
b
2
t-Bu
t-Bu
[salen-Mn][X]
SDMn
3.099
2.622
2.647
2.597
3.125
LiCl O/EtOH
H
2
0
o
C, CH Cl
2
2
(
2.757) (2.772)
-0.870 0.632
0.870) (0.892)
(2.643) (2.621) (2.982)
0.596 0.587 -0.852
(0.824) (0.751) (1.024)
-0.584 -0.506 -0.150
t-Bu
t-Bu
b
SDO
[salen-Mn][Cl]
-
-
-
-
(
Scheme 1. Synthetic of [salen-Mn(III)][X]( X =OAc , NO , BF ,
3
4
-
-
c
CF SO and CH CH O )
Q
O
-0.099
-0.589
3
3
3
2
(
-0.216) (-0.313) (-0.331) (-0.370) (-0.038)
1.751 1.649 1.645 1.637 1.776
(1.723) (1.715) (1.685) (1.664) (1.828)
2.361 2.106 2.225 2.227 1.869
2.405) (2.023) (2.114) (2.167) (1.872)
d
R
Mn=O
Table 1. Some of the typical spectroscopy parameters
RMn-Xd
-
-
b
20 c
Axial
V
)
(cm
V
)
C-O(cm
λmax (nm)
[α]D
C=N
a
1
1 a
(
anions
-
∠
MnN
32.9
(17.6)
13.6
(9.7)
35.3
(11.5)
17.7
(11.8)
-27.2
(-35.1)
-6.7
(-1.9)
17.8
44.4
(14.7)
14.9
(13.3)
-11.3
(-31.6)
-6.2
(0.1)
9.2
37.5
(18.7)
23.1
(17.2)
-23.0
(-28.5)
-1.3
38.1
(36.8)
14.6
(10.7)
-36.1
(-39.1)
-16.5
(-17.3)
-11.4
1
1
Cl
1608
1609
1612
1613
1620
1608
1611
1251
1251
1252
1252
1252
1251
1251
435.6 496.8 -1038
431.8 492.6 -1268
437.6 491.2 -954
431.5 489.8 -536
438.6 486.6 -456
434.4 491.6 -890
421.6 481.4 -640
e
-
O1C1
∠MnN
O1C4
∠
OAc
NO
BF4
-
3
e
-
-
MneO2 -33.0
CF SO3
3
-
N2C2
∠MnO
(-28.5)
-11.9
(-3.6)
1.4
CH CH O
3
2
d
2
None
e
a
b
N
2
C
3
(4.8)
5.7
The typical vibration frequency measured as KBr pellets.
f
c
△
a
E
The main absorbed peak of UV-vis in CH Cl . The specific
rotation of 0.0005 g/ml [salen-Mn][X]( X =Cl , OAc , NO , BF ,
2
2
b
-
-
-
-
-
Structural parameters of triplet (quintuplet). The absolute
3
4
c
-
-
d
value of spin density carried by Mn and O. The charge carried
by Mn and O. The Mn=O and Mn-X bond lengths in
Å. Dihedral angle. The energy difference between triplet and
quintuplet (Etriplet - Equintuplet).
CF SO3 and CH CH O ) in CH Cl . Compound without axial
3
3
2
2
2
d
anion was synthesized according to the method reported in ref.
e
f
4
6.
−
1
vibration frequencies (ranging from 1607.9 to 1619.8 cm )
Table 1). Similarly, the C-O vibration frequencies also differ
V
Influence of axial anions on the Mn =O active intermediate
(
V
It has been widely accepted that Mn =O(salen) complex is the
active intermediate in the asymmetric epoxidation using Mn(III)
. Though steric configuration of [salen-
Mn(IV)][X] (X =Cl , NO , N and CF CH O ) have been well
established basing on crystal research , it is still quite difficult
to explore the steric structure of these active Mn =O(salen)
intermediates by experimental methods. Herein, theoretical
calculations based on density functional theory were used to
investigate the influence of axial anions on Mn =O active
from each other. Moreover, the UV-vis absorption band for
4
the d-d transition of Mn salen complex , ranges from 486.6 to
4
5-49
salen as catalyst
4
96.8nm for different catalysts. Comparing with compound
-
-
-
-
-
2
3
3
3
2
without axial anion, the coordinated anion obviously increase
the λmax values. These FT-IR and UV-vis differences suggest
that the axial anions directly influence the electronic
distribution of the active site Mn.
4
3
V
Besides the influence on the electronic structure of the
active center, axial anion also brings remarkable steric
configuration variation of [salen-Mn(III)][X]. It is well-known
that specific rotatory power is an inherent property to rotate
the plane of incident polarized light, which is related to the
steric configuration of the chiral compound. The specific
rotator power of different [salen-Mn(III)][X] was measured on
the same conditions. It was found that these values ranged
from -456 to -1268. Comparing with compound without axial
V
intermediate. It is worth noting that this theoretical method is
accurate enough to reproduce the crystal structures or
43
50-52
predict experimental results
.
It has been found that the spin density (SD) and charge (Q)
carried by the active metal and oxygen are good indicators for
the reactivity of catalysts and there exists a linear relationship
51,53
between SD/Q values and reaction barrier
. For the
V
-
-
[Mn =O(salen)][X] system, it is not surprising that the axial
anion has an obvious influence on the SD/Q values of Mn and
O atoms (Table 2). Hence, these catalysts should have quite
different catalytic abilities.
The steric configuration of Mn salen complex plays a
significant role in determining the enantioselectivity of the
anion, week coordinated anion BF4 and CF SO3 decrease the
3
values of specific rotation whereas the other stronger
coordinated anion increase this value. It indicated the axial
anion had an obvious influence on the steric configuration of
the chiral Mn(III) salen, which agreeswith the crystal results of
4
3
double axial anion [salen-Mn(IV)][X]2
.
2
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. It is interesting to find that, though the counterion, we still can not find out the relationship between
1-7,45
catalytic process
View Article Online
DOI: 10.1039/C5RA13178B
-
-
-
-
-
volumes of these anions (Cl , AcO , NO , BF , and CH CH O ) the specific rotation and the degree of configuration distortion
3
4
3
2
Table 3. Asymmetric epoxidation of different olefins catalyzed
-
-
-
-
-
-
by [salen-Mn][X] ( X =Cl , OAc , NO , BF , CF SO and
3
4
3
3
-
a
CH CH O
)
3
2
c
d
Entry
Axial
anion
Substrate
Styrene
Con.(%)
ee(%)
TOF
(h )
b
-1
e
-
1
2
3
4
5
6
7
8
9
Cl
99.1
99.5
98.6
93.0
93.8
90.2
96.1
93.2
89.7
96.4
93.0
99.8
34.7
40.7
37.1
45.8
28.6
33.5
78.7
90.6
93.1
57.7
64.9
48.9
94.2
97.7
91.1
94.4
97.2
95.1
198.2
199.0
197.2
186.0
184.0
199.6
192.2
186.4
179.4
192.8
186.0
199.6
59.4
-
AcO
-
NO3
-
BF4
-
CF SO
3
3
-
-
-
CH CH O
3
2
-
Cl
Indene
-
-
AcO
NO3
-
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
BF4
-
CF SO
3
3
CH CH O
3
2
-
Cl
Acenapht- 29.7
hylene
34.2
-
-
AcO
NO3
68.4
36.5
49.2
30.7
28.5
73.0
-
BF4
CF SO
98.4
-
61.4
3
3
8
CH CH O
57.0
3
2
V
-
-
a
Fig. 1. The optimized structures of [Mn =O(salen)][X], (a) X =Cl ,
(
Reaction conditions: substrate (1mmol), m-CPBA (2mmol),
-
-
-
-
-
-
-
-
b
b) X =OAc , (c) X =NO , (d) X =BF , (e) X = CH CH O
3 4 3 2
NMO (5mmol) in CH Cl , T=0
substrate. Conversion % of substrate determined by GC. Ee
is the enantiomeric excess, which determined by GC with
RESTEK RT-BetaDEXse chiral column. Turnover Frequency
(TOF) is calculated by expression of [product]/[ catalyst]×time
℃
.
Catalyst was 1 mol% of
2
2
c
d
2
9-37
are quite small compared with those used in ACDC
have an undeniable effect on the steric configuration of Mn
, they
e
43,44
salen complex. Being similar to [salen Mn(IV)][X]2
, these
V
-1
active Mn =O(salen) intermediates also adopt a stepped
conformation with one of two salicylidene rings pointing
upward and the other downward (Fig. 1). The values of
(h ).
of these complexes. Based on the results presented in Table 1
and Fig. 1, what we can safely state is that the degree of
configuration distortion diversifies with different axial anion
obviously. Controlling the enantioselectivity by changing the
axial anions should be possible.
dihedral angle
and MnO N C were used to describe steric configuration
distortion of these catalysts (Table 2). For the quintuplet
structure, the values of MnO N C and MnO N C range
from 4.8 to -17.3 and -28.5 to -39.1 respectively.
∠MnN O C , ∠MnN O C , ∠MnO N C ,
1 1 1 1 1 4 2 2 2
∠
2
2 3
∠
∠
2
2
3
2
2
2
Though it is found that the catalysts with different structure
characteristics can be obtained by introducing different
Reactivity of chiral Mn(III) salen with different axial anions
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Though above spectral and theoretic results have a careful experimental research on the catalytic pVroiewceAsrtsiclsehOonwlines
demonstrated that the axial anions have an undeniable effect that the influence of axial anion is depenDdOeIn: 1t0o.1n03t9h/Ce5rReAa13c1t7io8nB
on the electronic and steric configuration of Mn salen complex, substrate and solvent.
Table 4. The effect of solvent on the epoxidation of indene
catalyzed by different catalysts .
The asymmetric epoxidation of olefins with different steric
hindrance (styrene, indene, and acenaphthylene) were
investigated (Table 3). No matter what axial anion is used, the
epoxidation of styrene can be finished within 0.5 hour. But,
the enantioselectivities are all poor and the corresponding ee
values only vary in a narrow range (28.6~45.8). Though axial
anions have brought an obvious difference in the steric
configuration distortion of these catalysts, the steric hindrance
of styrene is too small to clearly distinguish the variation
induced by the axial anions.
a
b
c
Time Cond. ee
TOF
(h )
Entry Catalyst
Solvent
DCM
e
-1
f
(h)
(%)
(%)
-
1
2
3
4
X=Cl
0.5
0.5
0.5
0.5
96.1 78.7 192.2
98.6 71.1 197.2
23.6 55.7 47.2
89.7 93.1 179.4
CH CN
3
DMF
DCM
-
X=NO3
5
CH CN
0.5
93.8 80.7 187.6
3
Increasing the steric hindrance of the reactant makes the
diversity induced by axial anions more clear. In the asymmetric
epoxidation of indene, the ee values range from 48.9 to 93.1
6
7
DMF
DCM
0.5
0.5
8.6
59.5 17.2
X=BF4-
96.4 57.7 192.8
-
8
9
CH CN
0.5
0.5
97.3 86.8 194.6
(Entries 7~12, Table 3). The catalyst with NO3 as axial anion
3
-
gives the highest ee value whereas the one with CH CH O
3
2
DMF
6.8
41.0 13.6
a
gives the lowest ee value. At the same time, high conversion
can be achieved in 0.5 h for all catalysts. Compared with the
Reaction conditions: indene (1mmol), m-CPBA (2mmol), NMO
5mmol) in different solvent, T=0
indene. DCM: dichloromethane; CH CN: acetonitrile; DMF:
N,N-dimethylformamide. Conversion % of indene determined
by GC. Ee is the enantiomeric excess, which determined by
GC with RESTEK RT-BetaDEXse chiral column.
b
(
℃
.
Catalyst was 1 mol% of
c
methods which introduce functional groups on salicylidene
3
15-20
d
rings of the metal-salen catalysts
, changing the axial anion
e
provides a much easier, but also effective, method to control
the reactivity of the traditional Jacobsen catalysts [salen-
Mn(III)][Cl].
Further increasing the steric hindrance of the substrate
results in lower discrimination in the influence of the axial
anion. In the asymmetric epoxidation of acenaphthylene
f
Turnover
Frequency (TOF) is calculated by expression of [product]/[ cat-
-1
alyst]×time (h ).
(Entries 13~18, Table 3), though good enantioselectivities are
obtained for all catalysts, the corresponding ee values vary in
an extremely narrow range (91.1~97.7).
It should be noticed that even though the steric
configuration of Mn salen complex plays a significant role in
determining the enantioselectivity of the asymmetric
epoxidation of olefins, many other factors also have noticeable
influences on the enantioselectivity values. Jacobsen et al.
discovered and studied the influence of electronic effects of
substituents on the asymmetric epoxidation in detail. They
found that the enantioselectivity could be improved when the
electron-donating group at the 5,5’- positions of the salen
9
unit . Jacobsen also found that the structure of substrates had
1
,1-4,9
great influences on the enantioselectivity of the reaction
,
and cis-di-substituted olefins had high enantioselectivity
1
4,5
9,6
values . Besides that, oxidant , additives , and reaction
9
temperature also affect the enantioselectivity values.
Herein we found that the solvent can cooperate with the
axial anion to influence the reaction. The asymmetric
-
-
epoxidation of indene catalyzed by [salen-Mn(III)][X] (X =Cl ,
-
-
NO , and BF ) were further investigated in solvents with
3
4
Fig. 2. (a) UV-vis spectra of [salen-Mn(III)][Cl], [salen-
Mn(III)][Cl]+m-CPBA in CH Cl (0.1mM) in dependence of time
different polarity (DCM, CH CN and DMF). For all catalysts,
3
2
2
reactions performed in DMF gave poor conversion and
enantioselectivity (Table 4). As we known, even though there
(
every 20mins from the top down n1-n6, n7, 6h, n8, 8h). (b-d)
V
The changing curves of Mn =O absorbance of [salen-
Mn(III)][Cl], [salen-Mn(III)][ NO ] and [salen-Mn(III)][BF ] with
V
is no olefin in the reaction system, the Mn =O active
54
3
4
intermediate can also decompose in solution (Fig. 2a) . For
time in A: DCM, B: CH CN, C: DMF.
3
[
salen-Mn(III)][Cl], full decomposition takes 8 hours in DCM.
However, this decomposition becomes quite fast in DMF for all
catalysts investigated here. It is probably because that there
4
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exists a competition between the active oxygen of Mn=O and column (RESTEK RT-BetaDEXse, 30m×0.25mm×0V.i2ew5μArmticl)e.OTnlhinee
the oxygen of DMF. This competition will accelerate the reagents and solvents were pure analyDtiOcaI:l10g.1r0a3d9e/Cm5RaAt1e3r1i7a8lBs
release of active oxygen and enhance the possibility of olefin
purchased from commercial sources and used without further
oxidation by the released oxygen rather than by the active purification unless otherwise indicated.
oxygen of Mn=O. Thus, the steric configuration of Mn salen Synthesis of salen-1: (1R,2R)-(-)-1,2-Diaminocyclohexane
complex has a poor influence on the reaction and a poor (3.42g, 30mol) was mixed with potassium carbonate (3.78g,
enantioselectivity was obtained in DMF. When the axial anions 27mol) in 20ml distilled water at 80
℃ for 0.5h. When the
-
-
were Cl or NO , reactions performed in DCM gave better solid was completely dissolved, 50ml ethanol was added to the
3
enantioselectivity, whereas the enantioselectivity was better solution at reflux for 1h. Then 3,5-di-tert-Butyl salicylaldehyde
-
in CH CN when the axial anion was BF . Correspondingly, we (5.86g, 25mol) was added dropwise to the mixture within 1h
3
4
V
can find that the decomposition of the Mn =O active which was dissolved in ethanol (100ml). The reaction mixture
intermediate is slower in DCM than that in CH CN for [salen- was heated at 80 for an additional 3h and then cooled at
Mn(III)][X] (X =Cl and NO ). However, this decomposition is the ice-water bath. The yellow solid which was precipitated
℃
3
-
-
-
3
slower in CH CN than that in DCM for [salen-Mn(III)][BF ].
out was separated by filtration. The preliminary product was
dissolved in dichloromethane (80ml) and then washed
sequentially with distilled water (2×40ml) and saturated brine
3
4
(
2×30ml). The organgic layer was dried over anhydrous MgSO4
Conclusions
overnight and the solvent was evaporated under reduced
pressure to get bright yellow product. Yield: 74.8%; [α] = -
3
5
7
1
20
The structure and reactivity of a series of chiral Mn(III)
D
o
1
-
-
-
-
-
-
47.75 (c=0.02, CH Cl ); m.p. 207.6~208.6 C; H NMR (CDCl ,
catalysts [salen-Mn(III)][X] (X = Cl , OAc , NO , BF , CF SO ,
2
2
3
3
4
3
3
-
00 MHz) δ, ppm: 13.67 (s, 2H; Ar-OH), 8.33 (s, 2H; CH=N),
and CH CH O ) were investigated. The obtained results
3
2
.31 (d , 2H; Ar-H), 6.98 (d, 2H; Ar-H), 3.36 (s, 2H; N-CH), 2.0-
indicate that a simply changing on the axial anions can result in
obvious variation in not only the electronic structure, but also
the steric configuration of [salen-Mn(III)][X] and its MnV=O
active intermediate. It can further lead to different reactivity
and enantioselectivity in the asymmetric epoxidation of olefins.
Besides, the axial anions can also change the decomposition
13
.4(m, 8H; CH ), 1.43(s, 18H; CH ), 1.26 (s, 18H; CH ). C NMR
2
3
3
(CDCl , 500MHz) δ, ppm: 165.87, 158.04, 139.91, 136.39,
3
1
3
1
1
26.76, 126.07, 117.91, 72.46, 34.99, 34.06, 33.30, 32.22,
-
1
1.46, 29.49, 24.40; FT-IR (KBr, v/cm ): 3418.6, 2961.9, 2871.8,
630.6, 1594.4, 1467.3, 1361.3, 1269.7, 1173.6, 1134.9, 1084.9,
V
037.2, 878.8, 827.8, 772.4, 711.0, 644.0; UV-vis (CH Cl2
，
rate of the Mn =O active intermediate. However, the influence
2
λmax /nm): 232, 262, 331; MS(m/z): Calcd for C H N O :
5
C H N O : C, 79.07; H, 9.95; N, 5.12; Found: C, 78.77; H,
9
Synthesis of [salen-Mn][Cl]: The ligand Salen-1 (4.92g, 9mmol)
dissolved in toluene (60ml) was added dropwise to 3
equivalent of Mn(OAc) ·4H O (6.62g, 27mmol) in ethanol (75
ml). The reaction mixture was stirred at reflux for 3h. Then the
LiCl (27mol, 1.63g) was added and the resulted mixture was
of axial anion is dependent on the substrate and the solvent.
Previous research has revealed that, based on the two-state-
reactivity model, the singlet, triplet, and quintet spin states of
Mn-salen complexs are all accessible during the reaction
36 55
2
2
+
47.43 [M+H] ; found: 547.25; Elemental analysis Calcd (%) for
36 54
2
2
.93; N, 5.03.
55
processes . Hence, to fully understand the effect of these
counterions on the enantioselectivity, a theoretic investigation
on the whole reaction process is necessary. Our theoretic on
this topic is on progress, including reaction catalyzed by singlet,
triplet, and quintet spin states of Mn-salen complexs with
different counterions.
2
2
further heated to reflux at 80
solution was washed with distilled water (2×40ml), and the
℃ for 2h. After 1.5h, the cold
orangic layer was dried over anhydrous MgSO . The solvent
was removed by rotary evaporation under reduced pressure.
Experimental
4
The residue was purified by recrystallizing from CH Cl (20ml)
Synthesis of catalysts and characterizations
2
2
and pentane (80ml). After filtered and dried in vacuum, brown
2
0
powdery [salen-Mn][Cl] was obtained. Yield: 79.7%; [α] = -
The NMR spectra were detected by Bruker ARX 500MHz
D
o
-1
1
2
1
4
038.0 (c=0.0005, CH Cl ); m.p.>300 C; FT-IR (KBr, v/cm ):
2 2
instrument, using CDCl as solvents and TMS as the internal
3
948.7, 2865.8, 1607.9, 1535.7, 1461.1, 1432.5, 1388.5, 1312.2,
251.2, 1175.5, 1031.4, 837.0, 780.8, 749.2, 566.8, 543.4,
standard. Elemental analysis was taken on an Elementar vario
EL II. Optical rotations of chiral complexes were recorded on a
WZZ-2A automatic polarimeter instrument. FT-IR spectra were
obtained from KBr pellets on a Bruker APEX-III spectrometer in
+
·
83.7; LC-MS(m/e): Calcd for [C H ClMnN O ] : 634.31;
36 52
2
2
+
found: 634.25; MS(ESI, m/z): calcd for [salen-Mn] : 599.34;
found: 599.83 ;Elemental analysis Calcd (%) for
-1
4
2
00-4000cm region and UV-vis spectra on a UV-vis SPECORD
00 spectrophotometer. No any data treatment were adopted
C H ClMnN O : C, 68.07; H, 8.25; N, 4.41; Found: C, 68.25; H,
36 52
2
2
8
.40; N, 4.08.
on the spectra measurements. Mass spectra were performed
on an LCMS-2020 mass spectrometer. The products of
epoxidation reaction were monitored by GC5890C gas
chromatograph equipped with a flame ionization detector
using high-purity nitrogen as the carrier gas. Conversions and
ee values were determined by GC with a chiral capillary
Synthesis of [salen-Mn][X] (X= OAc, NO , BF , CF SO ): 5
3
4
3
3
-
-
-
-
-
equivalent of AgX (X =OAc , NO , BF , CF SO ) (1mmol) was
3
4
3
3
respectively added to the [Salen-Mn][Cl] (0.127g, 0.2 mmol) in
CH Cl (5ml) at 40 below. The mixture was stirred for 5h.
℃
2
2
Then the cold solution was filtered to remove silver salts.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
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Please Rd So Cn oA tda vd aj un sc te ms argins
ARTICLE
Journal Name
Anhydrous pentane (50ml) was added to the filtration to give a A typical asymmetric epoxidation reaction was pVeierwfoArrtimcleeOdnlianes
light brown precipate. Collected by filtration and washed with follows. The catalysts [salen-Mn][X] (0.01DmOmI: 1o0l.,1013m9/oCl5%RAb13a1s7e8dB
pentane, the residue was dried in vacuum. Then on Mn element) and N-methylmorpholine-N-oxide (NMMO)
recrystallization from CH Cl (2ml) and pentane (20ml) at 20
℃
(5mmol as an axial additive) were dissolved in CH Cl2
2
2
2
below, the pure solid [salen-Mn][X] was obtained.
containing olefins (styrene, indene, diphenylethene,
2
0
[
salen-Mn][OAc]: Yield: 52.3%; [α] = -1268.0 (c=0.0005, acenaphthylene as substrates, 1mmol) at 0 °C. The mixed
D
-
1
CH Cl ); FT-IR (KBr, v/cm ): 3405.5
，2946.5, 2865.6, 1609.3, solution was stirred for 10minutes. Then 3-chloroperoxybenzo-
2
2
1
7
536.9, 1434.4, 1388.0, 1308.1, 1250.7, 1175.9, 1031.6, 836.0, ic acid (m-CPBA) (2mmol) as an oxidant was added in 4 equal
80.9, 748.8, 567.5, 543.2, 483.7; LC-MS(m/e): calcd for portions in 2 minutes. Gas chromatograph was employed to
+
·
[
C H MnN O ] : 658.35; found: 658.30; MS(ESI, m/z): calcd determine the conversions and ee values of the reaction. Each
38 55 2 4
+
for [salen-Mn] : 599.34; found: 599.83; Elemental analysis ee value was measured three times. Hence, these data should
Calcd (%) for C H MnN O ·0.5H O: C, 68.34; H, 8.45; N, 4.19; be statistically reliable. Except dichloromethane, acetonitrile
3
8
55
2
4
2
Found: C, 68.22; H, 8.46; N, 4.06.
and N,N-dimethylformamide (DMF) were used as reactive
20
[
salen-Mn][NO ]: Yield: 46.8%; [α] = -954.0 (c=0.0005, solvent in the epoxidation of indene catalyzed by [salen-
3
D
-1
CH Cl ); FT-IR (KBr, v/cm ): 3419.3, 2952.1, 2866.6, 1612.4, Mn][Cl], [salen-Mn][NO ] and [salen-Mn][BF ].
2
2
3
4
1
1
535.6, 1463.0, 1432.6, 1390.1, 1310.9, 1251.8, 1175.2, 1115.5,
028.4, 836.9, 780.2, 748.8, 567.6, 543.3, 484.0; LC-MS(m/e): Computational Methods
+
·
calcd for [C H MnN O ] : 661.33; found: 661.25; MS(ESI,
m/z): calcd for [salen-Mn] : 599.34; found: 599.92; Elemental The B3LYP method has been widely used in the calculation of
analysis calcd (%) for C H MnN O ·0.5H O: C, 64.46; H, 7.96; metallorganic complexes. For this reason, we optimized all the
3
6
52
3
5
+
36
52
3
5
2
N, 6.26. Found: C, 64.35; H, 8.05; N, 6.07.
structures by the B3LYP method. 6-31+G* basis set was
20
[
salen-Mn][BF ]: Yield: 47.5%; [α] = -536.0 (c=0.0005, generally used for these atoms except for transition metal.
4
D
-1
CH Cl ); FT-IR (KBr, v/cm ): 2954.0, 2867.3, 1613.1, 1536.6, LANL2DZ was used for Mn. Geometric configuration
2
2
1
8
463.5, 1433.7, 1392.0, 1311.6, 1251.9, 1175.8, 1059.5, 1029.4, optimization, energy calculation, frequency calculation, and
37.2, 780.7, 749.4, 572.4, 544.0, 485.9; LC-MS(m/e): calcd for zero-point energy correction were performed by using the
+
·
[
C H BF MnN O ] : 686.34; found: 686.30; MS(ESI, m/z): same basis set. All calculations were performed with the
36 52 4 2 2
+
calcd for [salen-Mn] : 599.34; found: 599.83; Elemental Gaussian 03 suite of programs.
analysis Calcd (%) for C H BF MnN O : C, 62.98; H, 7.63; N,
36
52
4
2
2
4
.08; Found: C, 62.87; H, 7.63; N, 4.13.
2
0
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (No.21176110 and 21376115) and Jiangsu
Province Natural Science Foundation (BK20141311).
[salen-Mn][CF SO ]: Yield: 66.2%; [α] = -456.0 (c=0.0005,
3
3
D
-1
CH Cl ); FT-IR (KBr, v/cm ): 3471.0, 2955.6, 2868.4, 1619.8,
1
7
2
2
536.2, 1434.1, 1389.9, 1313.1, 1252.4, 1174.4, 1031.9, 837.7,
80.9, 750.2, 635.1, 574.9, 544.8, 487.9; LC-MS(m/e): calcd for
+
·
[
C H F MnN O S] : 748.29; found: 748.25; MS(ESI, m/z):
37 52 3 2 5
+
calcd for [salen-Mn] : 599.34; found: 599.83; Elemental
analysis Calcd (%) for C H F MnN O S·H O: C, 57.95; H, Notes and references
37
52
3
2
5
2
7
.10; N, 3.65; Found: C, 58.19; H, 7.00; N, 3.68.
[
1] P. Besse and H. Veschambre, Tetrahedron, 1994, 50, 8885-
927.
Synthesis of [salen-Mn][OCH CH ]:
CH CH O-Na (0.4mmol, 0.0272g) was added to the [Salen-
Mn][Cl] (0.127g, 0.2 mmol) in CH Cl (10ml) at 40
2
equivalents of
2
3
8
3
2
[2] Q. Xia, H. Ge, C. Ye, Z. Liu and K. Su, Chem. Rev., 2005, 105,
℃
below.
1603-1662.
2
2
After the mixture was stirred for 2h, the solvent was removed [3] L. L. Lou, K. Yu, F. Ding, X. J. Peng, M. M. Dong, C. Zhang and S.
by rotary evaporation. The resulting solid was dissolved in
CH Cl (5ml) and the solution was filtered in vacua. The rest of
X. Liu, J. Catal., 2007, 249, 102-101.
4] N. C. Maity, G. V. S. Rao, K. J. Prathap, S. H. R. Abdi, R. I.
Kureshy, N. H. Khan and H. C. Bajaj, J. Mol. Catal. A:Chem.,
[
2
2
process was similar as above. Finally, the pure yellowish-brown
powder [salen-Mn][OCH CH ] was obtained.
2
013, 366, 380-389.
2
3
20
[5] T. Sugiishi, M. Matsugi, H. Hamamoto and H. Amii, RSC
Adv. ,2015, 5, 17269-17282.
6] Q. P. Shi, Z. H. Shi, N. G. Li, Y. P. Tang and W. Li, Curr. Org.
Chem., 2013, 17, 2936-2970.
7] J. Rich, E. Manrique, F. Molton, C. Duboc, M. N. Collomb, M.
Rodríguez and I. Romero, Eur. J. Inorg. Chem., 2014, 16, 2663-
2670.
[
salen-Mn][OCH CH ]: Yield: 37.8%; [α] = -890.0 (c=0.0005,
2 3 D
-1
CH Cl ); FT-IR (KBr, v/cm ): 3448,1, 2949.8, 2866.1, 1607.9,
2
2
[
1
7
534.8, 1432.2, 1388.6, 1312.7, 1251.4, 1175.1, 1031.7, 837.1,
80.7, 749.2, 566.6, 543.5, 483.6; LC-MS(m/e): calcd for
[
+
·
[
C H MnN O ] : 644.37; found: 644.35; MS(ESI, m/z): calcd
38 57 2 3
+
for [salen-Mn] : 599.34; found: 599.83; Elemental analysis
Calcd (%) for C H MnN O ·H O: C, 68.86; H, 8.97; N, 4.23; [8] W. Zhang, J. L. Loebach, S. R. Wilson and E. N. Jacobsen, J. Am.
3
8
57
2
3
2
Found: C, 68.56; H, 8.40; N, 4.37.
Chem. Soc., 1990, 112, 2801-2803.
9] M. Palucki, P. J. Pospisil, W. Zhang and E. N. Jacobsen, J. Am.
Chem. Soc., 1994, 116, 9333-9334.
[
[
General epoxidation reaction procedure
10] D. A. Annis and E. N. Jacobsen, J. Am. Chem. Soc., 1999, 121,
4
147-4154.
6
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please Rd So Cn oA tda vd aj un sc te ms argins
Page 8 of 8
Journal Name
ARTICLE
[
[
[
[
11] E. N. Jacobsen, Acs. Chem. Res., 2000, 33, 421-431.
12] T. Katsuki, J. Mol. Catal. A:chem., 1996, 113, 87-107.
13] T. Katsuki, Adv. Synth. Catal., 2002, 344, 131-147.
14] M. Peng, Y. J. Chen, R. Tan, W. G. Zheng and D. H. Yin, RSC
Adv., 2013, 3, 20684-20692.
[44] C. L. Wang, T. Kurahashi, K. Inomata, M. HadaVieawnAdrtiHcle. OFnulijniie,
Inorg. Chem., 2013, 52, 9557-9566.
[45] L. Kürti, M. M. Blewett and E. J. Corey, Org. Lett., 2009, 11,
4592-4595.
[46] M. K. Brown, M. M. Blewett, J. R. Colombe and E. J. Corey, J.
Am. Chem. Soc., 2010, 132, 11165-11170.
DOI: 10.1039/C5RA13178B
[
15] R. I. Kureshy, K. J. Prathap, T. Roy, N. C. Maity, N. H. Khan, S. H.
R. Abdi and H. C. Bajaj, Adv. Synth. Catal., 2010, 352, 3053- [47] W. Adam, C. Mock-Knoblauch, C. R. Saha-Möller and M.
060. Herderich, J. Am. Chem. Soc., 2000, 122, 9685-9691.
16] M. A. Nasseri, A. Allahresani and H. Raissi, RSC Adv., 2014, 4, [48] P. Fristrup , B. B. Dideriksen , D. Tanner and P-O. Norrby, J. Am.
6087-26093. Chem. Soc., 2005, 127, 13672-13679.
17] X. Yun, X. Hu, Z. Y. Jin, J. H. Hu, C. Yan, J. Yao and H. Li, J. Mol. [49] M. Rocha, S. L.H. Rebelo and C. Freire, Appl. Catal. A: Gen.,
Catal. A:chem., 2010, 327, 25-31. 2013, 460-461, 116-123.
18] T. Chang, L. L. Jin and H. W. Jing, ChemCatChem., 2009, 1, 379- [50] K. B. Petersen, P-O. Norrby, A. M. Daly and D. G. Gilheany,
83. Chem. Eur. J., 2002, 8, 4299-4307.
19] W. Adam, K. J. Roschmann, C. R Saha-Möller and D. Seebach, J. [51] X. Hu, Y. Sun, J. Mao and H. Li, J. Catal., 2010, 272, 320-332.
3
[
[
[
[
[
[
[
[
2
3
Am. Chem. Soc., 2002, 124, 5068-5073.
20] J. Teixeira, A. R. Silva, L. C. Branco, C. A. M. Afonso and C.
Freire, Inorg. Chim. Acta., 2010, 363, 3321-3329.
21] W. Sun, H. W. Wang, C. G. Xia, J. W. Li and P. Q. Zhao, Angew.
Chem. Int. Ed., 2003, 42, 1042-1044.
22] M. Sankaralingama and M. Palaniandavar, Dalton Trans., 2014,
[52] X. Hu, J. Mao, Y. Sun, H. Chen and H. Li, Catal. Commun., 2009,
10, 1908–1912.
[53] X. Hu, C. Liu, Y. Wu and Z. Zhang, J. Phys. Chem. C, 2011, 115,
23913-23921.
[54] M. P. Feth, C. Bolm, J. P. Hildebrand, M. Kohler, O. Beckmann,
M. Bauer, R. Ramamonjisoa and H. Bertagnolli, Chem. Eur. J.,
2003, 9, 1348-1359.
4
3, 538-550.
23] D. P. Wang, M. Wang, R. Zhang, X. N. Wang, A. Gao, J. Ma and [55] W. Adam, K. J. Roschmann, C. R. Saha-moller and D. Seebach,
L. C. Sun, Appl. Catal. A: Gen., 2006, 315, 120-127.
J. Am. Chem. Soc. 2002, 124, 5068-5073.
[
[
24] J. Dimroth and M. Weck, RSC Adv., 2015, 5, 29108-29113.
25] Z. Li, Z. H. Tang, X. X. Hu and C. G. Xia, Chem. Eur. J., 2005, 11,
1
210-1216.
[
[
[
[
[
26] N. C. Maity, S. H. R. Abdi, R. I. Kureshy, N. H. Khan, E. Suresh,
G. P. Dangi and H. C. Bajaj, J. Catal., 2011, 277, 123-127.
27] R. Tan, D. H. Yin, N. Y. Yu, H. H. Zhao and D. L. Yin, J. Catal.,
2
009, 263, 284-291.
28] X. J. Zhu, K. Venkatasubbaiah, M. Weck and C. W. Jones,
ChemCatChem., 2010, 2, 1252-1259.
29] N. J. A. Martin and B. List, J. Am. Chem. Soc., 2006, 128,
1
3368-13369.
30] G. L. Hamilton, E. J. Kang, M. Mba and F. D. Toste, Science.,
007, 317, 496-499.
2
[
[
[
31] B. Zhao, H. Du and Y. Shi, J. Org. Chem., 2009, 74, 8392-8395.
32] S. H. Liao and B. List, Angew. Chem. Int. Ed., 2010, 49, 628-631.
33] M. Mahlau and B. List, Angew. Chem. Int. Ed., 2013, 52, 518-
5
33.
34] J. L. Cai, J. Huang, C. M. Li, H. Feng and Z. G. Liu, RSC Adv.,
013, 3, 18661-18670.
35] R. J. Phipps, G. L. Hamilton and F. D. Toste, Nature Chem.,
012, 4, 603-614.
[
[
[
[
[
[
[
[
[
[
2
2
36] V. Rauniyar, A. D. Lackner, G. L. Hamilton and F. D. Toste,
Science, 2011, 334, 1681-1684.
37] S. Kemper, P. Hrobarik, M. Kaupp and N. E. Schlorer, J. Am.
Chem. Soc., 2009, 131, 4172-4173.
38] A. Westphal, A. Klinkebiel, H. M. Berends, H. Broda, P. Kurz
and F. Tuczek, Inorg. Chem., 2013, 52, 2372-2387.
39] W. Adam, K. J. Roschmann and C. R Saha-Möller, Eur. J. Org.
Chem., 2000, 3519-3521.
40] Y. L. Wei, W. S. Huang, Y. M. Cui, K. F. Yang, Z. Xu and L. W. Xu,
RSC Adv., 2015, 5, 3098-3103.
41] L. H. Yuan, Y. Xu, X. B. Hu, G. Yang and Y. Wu, J. Mol. Catal. A:
Chem., 2015, 396, 55-60.
42] X. Hu, D. Martin, M. Melaimi and G. Bertrand, J. Am. Chem.
Soc., 2014, 136, 13594-13597.
43] T. Kurahashi, M. Hada and H. Fujii, J. Am. Chem. Soc., 2009,
1
31, 12394-12405.
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