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COMMUNICATION
Journal Name
Conflicts of interest
There are no conflicts to declare.
DOI: 10.1039/D0CC04440G
+
N
N
N
N
Mn
N
N
648.16
O
OTf
Notes and references
[Mn(IV)(O)(S,S-BPMB)(OTf)]+, m/z = 648.15, I-2
1
(a) M. M. Abu-Omar, A. Loaiza and N. Hontzeas, Chem. Rev.,
2005, 105, 2227–2252; (b) L. Que, Jr. and W. B. Tolman,
Nature, 2008, 455, 333–340; (c) M. Guo, T. Corona, K. Ray
and W. Nam, ACS Cent. Sci., 2019, 5, 13–28; d) K. Ray, F. F.
Pfaff, B. Wang, W. Nam, J. Am. Chem. Soc. 2014, 136, 13942–
13958.; e) G. Yin, Acc. Chem. Res., 2013, 46, 483–492.
(a) T. Newhouse and P. S. Baran, Angew. Chem. Int. Ed.,
2011, 50, 3362–3374; b) C.-M. Che, V. K.-Y. Lo, C.-Y. Zhou
and J.-S. Huang, Chem. Soc. Rev., 2011, 40, 1950–1975.
(a) W. N. Oloo and L. Que, Jr., Acc. Chem. Res., 2015, 48,
2612-2621; (b) E. P. Talsi and K. P. Bryliakov, Coord. Chem.
Rev., 2012, 256, 1418–1434; (c) I. Gamba, Z. Codolà, J. Lloret-
Fillol and M. Costas, Coord. Chem. Rev., 2017, 334, 2–24.
(a) K. P. Bryliakov, Chem. Rev., 2017, 117, 11406–11459; (b)
O. Cussó, X. Ribas and M. Costas, Chem. Commun., 2015, 51,
14285–14298; c) W. Sun and Q. S. Sun, Acc. Chem. Res.,
2019, 52, 2370–2381.
600
620
640
660
680
700
m/z
Fig. 2 CSI-MS spectrum of the solution showing the signal of [MnIV(O)(S,S-
BPMB)(OTf)]+, I-2 at m/z 648.15.
2
3
increasing intensity of the 251.60 m/z and 650.16 peaks, thus
indicating that the generated MnIV-oxo contains one
oxygenatom which can be exchanged with H218O (see ESI, Fig.
S3). The manganese-catalyzed epoxidation of styrene was then
carried out and monitored by CSI-MS. Upon the addition of
styrene, the intensities of the peaks at m/z 249.60 and 648.16
corresponding to MnIV-oxo decreased markedly. Most
remarkably, the CSI-MS spectrum of catalytic epoxidation of
styrene exhibited a new peak at m/z 752.19 which could be
4
5
6
7
8
9
B. Wang, C. Miao, S. Wang, C. Xia and W. Sun, Chem. - Eur. J.,
2012, 18, 6750–6753.
O. Y. Lyakin, R. V. Ottenbacher, K. P. Bryliakov and E. P. Talsi,
ACS Catal., 2012, 2, 1196–1202.
O. Cussó, I. Garcia-Bosch, X. Ribas, J. Lloret-Fillol and M.
Costas, J. Am. Chem. Soc., 2013, 135, 14871–14878.
J. Du, C. Miao, C. Xia, Y.-M. Lee, W. Nam and W. Sun, ACS
Catal., 2018, 8, 4528–4538.
C. Miao, B. Wang, Y. Wang, C. Xia, Y.-M. Lee, W. Nam and W.
Sun, J. Am. Chem. Soc. 2016, 138, 936–943.
assigned
to
[MnII(S,S-BPMB)(OTf)-epoxide]+,
a
key
intermediate during the epoxidation process {[MnII(S,S-
BPMB)(OTf)-(styrene oxide)]+, I-3, calculated m/z 752.22}, on
the basis of m/z and isotopic distribution pattern (see ESI, Fig.
S4). The findings above provide solid evidence for the role of
MnIV-oxo as an active epoxidizing species under the reaction
conditions. In this case, the specific BPMB ligand enables the
reactivity of MnIV-oxo in the epoxidation reaction, where its
smaller ligand pocket probably plays a key role. Additionally,
we carried out an 18O-labeled water (5 eq. H218O with respect
to the substrate) experiment on the epoxidation of styrene by
C1 and TBHP under the standard conditions. A significant
amount (10%) of 18O-incorporation from H218O into the styrene
oxide was observed, further indicating that a high-valent Mn-
oxo species served as an epoxidizing intermediate (Fig. S5).22
In summary, we have realized the manganese-catalyzed
asymmetric epoxidation of olefins with TBHP as the terminal
oxidant. Compared to the previous acid-assisted manganese
catalytic systems, the present catalyst could promote the
epoxidation reaction effectively under acid-free conditions,
enabled by the specific BPMB N4 ligand. As a result, the
substrates that are well-matched with the ligand pocket with
respect to size can achieve high levels of enantiocontrol.
According to the epoxidation of more challenging substrates,
the catalyst has demonstrated improved enantioselectivity for
simple olefins due to the smaller ligand pocket. Remarkably,
CSI-MS experiments support the formation of MnIV=O as an
active epoxidizing species. Further studies in this area,
including ligand development and mechanistic study, are
ongoing in this laboratory.
10 R. V. Ottenbacher, D. G. Samsonenko, E. P. Talsi and K. P.
Bryliakov, ACS Catal., 2014, 4, 1599–1606.
11 (a) D. Shen, C. Miao, S. Wang, C. Xia and W. Sun, Org. Lett.,
2014, 16, 1108–1111; (b) D. Shen, C. Miao, S. Wang, C. Xia
and W. Sun, Eur. J. Inorg. Chem. 2014, 33, 5777–5782.
12 (a) X. H. Liu, L. Lin and X. M. Feng, Acc. Chem. Res., 2011, 44,
574–587; (b) X. H. Liu, H. F. Zheng, Y. Xia, L. Lin and X. M.
Feng, Acc. Chem. Res., 2017, 50, 2621–2631.
13 Y. H. Li, K. L. Ding and C. A. Sandoval, Org. Lett., 2009, 11,
907–910.
14 G. Balboni, R. Guerrini, S. Salvadori, C. Bianchi, D. Rizzi, S. D.
Bryant and L. H. Lazarus, J. Med. Chem., 2002, 45, 713–720.
15 D. Q. Xu, Q. S. Sun, W. F. Wang, C. G. Xia, W. Sun, CCDC
1491559: Experimental Crystal Structure Determination,
2016, DOI: 10.5517/ccdc.csd.cc1m22tl
16 X. N. Chen, B. Gao, Y. J. Su and H. M. Huang, Adv. Syn. Catal.,
2017, 359, 2535–2541.
17 W. Wang, Q. Sun, C. Xia and W. Sun, Chin. J. Catal., 2018, 39,
1463–1469.
18 D. Q. Xu, Q. S. Sun, W. F. Wang, C. G. Xia, W. Sun, CCDC
1491558: Experimental Crystal Structure Determination,
2016, DOI: 10.5517/ccdc.csd.cc1m22sk
19 D. Shen, B. Qiu, D. Xu, C. Miao, C. Xia and W. Sun, Org. Lett.,
2016, 18, 372–375.
20 I. Prat, J. S. Mathieson, M. Güell, X. Ribas, J. M. Luis, L. Cronin
and M. Costas, Nat. Chem., 2011, 3, 788–793.
21 J. Serrano-Plana, W. N. Oloo, L. Acosta-Rueda, K. K. Meier, B.
Verdejo, E. García-España, M. G. Basallote, E. Münck, L. Que,
Jr., A. Company and M. Costas, J. Am. Chem. Soc., 2015, 137,
15833–15842.
22 (a) W. Nam and J. S. Valentin, J. Am. Chem. Soc., 1993, 115,
1772–1778; (b) M. S. Seo, J.-H. In, S. O. Kim, N. Y. Oh, J.
Hong, J. Kim, L. Que, Jr. and W. Nam, Angew. Chem. Int. Ed.,
2004, 43, 2417–2420.
We acknowledge financial support of this work from the
National Natural Science Foundation of China (21773273 and
21802153), the Dalian National Laboratory for Clean Energy
(DNL) Cooperation Fund, CAS (Grant No. DNL201904) and
Natural Science Foundation of Jiangsu Province (BK20170420).
4 | J. Name., 2012, 00, 1-3
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