Acid promoted radical-chain difunctionalization of styrenes with stabilized radicals and (N,O)-nucleophiles

Article abstract of DOI:10.1039/c9cc09369a

A difunctionalization of alkenes through sequential addition of a radical and a nucleophile has been developed, which is suggested to proceed by a radical chain mechanism not requiring a catalyst. An electron transfer step to the oxidant benzoyl peroxide is facilitated by protonation with a strong acid.

Full text of DOI:10.1039/c9cc09369a

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DOI: 10.1039/C9CC09369A
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Acid Promoted Radical-Chain Difunctionalization of Styrenes with
Stabilized Radicals and (N,O)-Nucleophiles
Received 00th January 20xx,
Accepted 00th January 20xx
Sensheng Liu, and Martin Klussmann*
DOI: 10.1039/x0xx00000x
A difunctionalization of alkenes through sequential addition of a raised our interest for its combination of a peroxide and acid
radical and a nucleophile has been developed, which is suggested and its potential to add radicals and nucleophiles to olefins.
to proceed by a radical chain mechanism not requiring a catalyst.
An electron transfer step to the oxidant benzoyl peroxide is
a) Typical procedure of radical-nucleophile difunctionalization of olefins:
facilitated by protonation with a strong acid.
Nu
R
R
Oxidant
ET
R
Nu
R
The difunctionalization of alkenes is a powerful transformation
in synthetic organic chemistry. Besides transition-metal
catalysed methods that proceed via organometallic
b) This work:
Nu
1
R1
R1
intermediates, such reactions can be efficiently conducted by
C/S
Nu = O, N
BPO, HPF6
0 °C, 2-6 h
2
+
S/C
H
+
Nu
addition of free radicals. An interesting strategy amongst
5
these is the consecutive addition of a radical and a
nucleophile, which requires an electron transfer (ET) step after
the radical addition, in order to generate a carbocation that
Scheme 1 Radical-nucleophile addition of olefins. BPO = Benzoyl peroxide.
2
a,3
could be trapped by a nucleophile (Scheme 1a).
Such
Here, we report mechanistic details of the effect of acid on
benzoyl peroxide and a method for difunctionalization of
styrene derivatives with stabilized C- and S-radicals and N- and
O-nucleophiles. The reactions do not require a catalyst but the
presence of a strong Brønsted acid, and they operate at only
slightly elevated temperature (Scheme 1b).
We found that the combination of BPO with HPF
the addition of thioxanthene (2a) and acetonitrile to styrene
1a) without any additional catalyst within two hours at 50°C
Table 1, entry 1). The product’s structure (3a) suggested that
a thioxanthenyl radical was added to styrene and subsequently
reactions would enable functionalizing olefins with a wide
variety of reagents in a regioselective manner, given that
radical precursors and nucleophiles mostly react
complementarily. Although many synthetically interesting
methods have been developed towards this goal, there is as of
yet no method with a truly broad substrate scope of both
6
allowed for
4
,5,6
radicals and nucleophiles.
Most of these methods require
the presence of a transition metal catalyst or reagent to
achieve the desired ET forming the carbocation intermediate,
(
(
7
notable exceptions utilize an organic photocatalyst, iodide as
8
9
catalyst or electrochemistry.
1
2
acetonitrile attacked as a nucleophile in a Ritter reaction. The
C-radical of thioxanthene had apparently formed by H-atom
We had previously worked on the activation of tert-butyl
hydroperoxide by Brønsted acids, most notably in the
1
3
transfer (HAT),
generated from BPO.
presumably to a benzoyloxyl radical
1
0
presence of ketones. We noticed the work by Zhang, Bao and
co-workers, who reported copper-catalysed
difunctionalization of alkenes using benzoyl peroxide (BPO) in
a
The acid plays a crucial role for the reaction: with lower
amounts, the yield drops significantly (entry 2) and without
acid, no reaction occurs (entry 3; for further results under
changed reaction conditions, see the Supporting Information).
In the presence of other acids, the product was also formed,
but apparently the yield is correlated with the acid strength.
For example, trifluoroacetic acid gave only 11% of 3a, while
and HClO gave 39% and 51% (entries
4 4
-6). In the absence of BPO and with other peroxide oxidants,
the product was not formed. Ambient temperature is
sufficient for the reaction, but the rate is significantly reduced.
1
1
6
the presence of HPF . Acetonitrile was both radical precursor
and nucleophile and the role of the acid was not clear, thus it
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim
an der Ruhr, Germany.
E-mail: klusi@mpi-muelheim.mpg.de
the stronger acids HBF
4
Electronic Supplementary Information (ESI) available, including experimental
details, NMR spectra, X-ray crystallographic data and
DOI: 10.1039/x0xx00000x
a CIF file. See
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Performing the reaction under strict exclusion of oxygen amount used under reaction conditions. OtheVriewaAcritdicsle Oanllsinoe
increased the yield, and the reaction could also be performed induced such a shift, but less strong, DaOsI:is10.s1h03o9w/Cn9ChCe0r9e36f9oAr
on a larger scale, giving 1.5 g of 3a with an isolated yield of trifluoroacetic acid (for other acids, see the Supporting
8
3% (entry 7).
Information). The reduction was thus significantly eased by the
strong acid HPF , possibly by protonation that turns the now
6
cationic peroxide into a better electron acceptor.
Table 1 Optimization of the reaction conditionsa
O
BPO (1.5 equiv.)
Me
NH
S
Acid
CH3CN (2 ml)
S
50 °C, 2 h
1a
2a
3a
Entry
Acid
Acid equiv.
Yield (%)b
1
2
3
4
5
6
HPF
HPF
6
(aq., 55%)
1.0
0.1
-
1.0
1.0
1.0
1.0
88
20
0
11
39
51
c
6
(aq., 55%)
-
CF
HBF
HClO
HPF
3
CO
2
Hc
4
(aq., 48%)
(aq., 70%)
(aq., 55%)
4
d
e
7
6
91 (88, 83 )
a
1
a (0.2 mmol), 2a (0.4 mmol, 2.0 equiv.), BPO (0.3 mmol, 1.5 equiv.), Acid (0.2
b
1
mmol, 1.0 equiv.) in CH
3
CN (2 ml). Yields determined by H NMR spectroscopic
Figure 1 Cyclic voltammograms showing the effect of acid addition on the reduction
potential of BPO. Two platinized Pt wires as a counter and working electrode with a
Ag/AgCl electrode as a reference were used. The cyclic voltammetry (CV) was
conducted from -1.0 V to 2.0 V with a scan rate of 100 mV/s. BPO (0.3 mmol), acid (0.2
analysis of the crude reaction mixture relative to internal standard CH
3
NO
2
, yield
c
d
of isolated product in parentheses. With addition of 1.0 equiv. of water.
e
Degassed, under argon. Performed on a larger scale, isolating 1.5 g of 3a.
3
mmol), tetrabutylammonium hexafluorophosphate (0.1 M) in CH CN under Ar.
The reaction is very likely proceeding via a radical mechanism, These results indicate a reaction mechanism that relies on
as the addition of radical inhibitors reduced the yield electron transfer (ET) steps (Scheme 3). Initiating benzoyloxyl
significantly (see the Supporting Information for details). The radicals (4) are formed from BPO in the presence of
acid apparently does not affect the decomposition of BPO, thioxanthene, possibly by ET to BPO that is facilitated by
1
4
which has a reported 10 hour half-life temperature of 73 °C.
protonation. These induce HAT from thioxanthene, generating
As an NMR experiment revealed, BPO with or without acid did a new radical (5), which then adds to styrene, forming the
not change when heated in acetonitrile at 50 °C for two hours benzylic radical 6. This is oxidized by BPO in the presence of
(
Scheme 2a). However, in the presence of thioxanthene, HPF , most likely by ET to the protonated peroxide (7), giving
6
benzoic acid was formed in significant amounts under these the intermediate carbocation 8, benzoate and a new
conditions, indicating that it accelerates the peroxide benzoyloxyl radical. The cation 8 can react as an electrophile
decomposition (Scheme 2b).
with acetonitrile, generating the product 3a in the fashion of a
Ritter reaction. Thus, the reaction appears to run by a radical
chain mechanism and can be seen as a case of “electron-
a)
CH3CN (2 ml)
0 °C, 2 h, Ar
O
5
No change
No change
O
O
15
catalysis”.
HPF6 (1.0 equiv.)
CH CN (2 ml)
O
BPO
3
BPO (0.3 mmol)
50 °C, 2 h, Ar
initiation
2a
BzOH
b)
O
H
O
S
H
H
O
2a
CH CN (2 ml)
H
3
BPO
O
Ph
Ph
O
50 °C, 2 h, Ar
OH
Ph
O
BzOH
4
BPO (0.3 mmol)
+
7
O
S
2a (0.4 mmol)
0.17 mmol
e
5
S
Scheme 2 Experiments pointing to the reaction mechanism.
H3C CN
While the acid does not accelerate the homolytic cleavage of
BPO, it does change its redox potential. We studied this effect
by cyclic voltammetry (Figure 1). The reduction of BPO alone
was found to occur at −345 mV, which underwent a shift by
S
Ph
S
1a
3a
Ph
Ph
8
6
6
+470 mV in the presence of 0.66 equiv. of HPF , the relative
Scheme 3 Potential reaction mechanism, shown exemplary for 1a and 2a.
2
| J. Name., 2012, 00, 1-3
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Based on this working model of the reaction’s mechanism, Next, the scope with respect to nucleophiles was explored.
View Article Online
DOI: 10.1039/C9CC09369A
other substrates that can initiate such a radical chain by Although we tried many substrates (see the Supporting
interaction with BPO1 and that easily form radicals by HAT to Information for further details), only alcohols were successful,
6
a benzoyloxyl radical should also be employable, as well as and only with thioxanthene but not with xanthene (Scheme 5).
other olefins and alternative nucleophiles.
Reactions of styrene with various alcohols produced the
As shown in Scheme 4, styrenes with both weakly electron- expected products in good yields, with primary alcohols in
t
donating (Me, Bu) and withdrawing (F, Cl, Br) substituents on generally higher yields (9a-9e, 73-93%) than secondary (9f-9g)
the aromatic ring, regardless of their positions, afforded the and tertiary alcohols (9h).
desired products in good yields 62-96% (3b-3f, 3j-3k and 3m-
BPO (1.5 equiv.)
HPF6 55%
(1 equiv.)
3
n), as did 4-vinylbiphenyl and vinylnaphthalene (3i, 3p).
R
However, styrene bearing the strongly electron-donating
methoxy substituent did not give the desired product, and the
strongly electron-withdrawing NO and CF substituents led to
2 3
O
S
+
CH3CN (1 ml)
R-OH (1 ml)
50 °C, 2 h
S
1a
2a
9
low yields of 3g, 3h and 3l in 10%, 30% and 33%. Using indene
as olefin gave the product 3q in 30% yield, but it is remarkable
for its high trans-selectivity. A diastereomeric ratio of >21:1
was determined in the crude reaction mixture, but after
purification, we received the pure trans-product 3q. Similarly,
only the trans-product 3r was isolated from the reaction with
E-β-methylstyrene. Strangely, other nitriles besides
acetonitrile did not lead to the expected products with
thioxanthene. However, when we used xanthene as HAT-
R
R
iPrO
O
S
S
O
S
Ph
Ph
Ph
9
a: R = Me, 91%
b: R = Et, 73%
9f: 69%
9
9g: R = Cy, 28%
9c: R = nPr, 93%
t
9h: R = Bu, 40%
9
9
d: R = nBu, 92%
e: R = nPent, 84%
donor, we could isolate different amide products by Scheme 5 Substrate scope for the reaction of alcohol nucleophiles: 1a (0.2 mmol), 2a
(
(
0.4 mmol, 2.0 equiv.), BPO (0.3 mmol, 1.5 equiv.), HPF
1 ml) and CH CN (1 ml), Ar, isolated yield.
6
(0.2 mmol, 1.0 equiv.), alcohols
performing the reaction in different nitriles as solvent.
Aliphatic and aromatic nitriles as well gave the products 3s-3x
with good yields after an extended reaction time of 6 hours.
The general structure of these products was confirmed by X-
ray crystallography of product 3e.
3
Thiophenols (10) as HAT-donors with acetonitrile as
nucleophile could also be employed successfully in this
reaction with styrene (Scheme 6). While alkyl thiols did not
react under those conditions, products 11 with various
differently substituted thiophenols could be employed.
Products of a thiol-ene reaction were not observed Similar
products like 11 had recently been reported, being synthesized
O
BPO (1.5 equiv.)
HPF6 55%
Me
NH
X
(
1 equiv.)
Nitriles (2 ml)
0 °C, 2 h
R1
+
X
5
R1
1
2
3
8
by an iodide-catalysed radical reaction or by ionic reactions
also utilizing stoichiometric amounts of oxidants.
O
O
O
1
7
Me
NH
S
Me
NH
S
Me
NH
R
S
O
Me
NH
R
BPO (1.5 equiv.)
HPF6 55%
(1 equiv.)
3
3
3
3
3
3
3
3
b, R = Me, 83%
c, R = Bu, 62%
3j, R = Me, 63%
3k, R = Br, 77%
3l, R = NO2, 33%
HS
S
t
R
3m, R = Me, 77%
3n, R = Br, 71%
R
R
d, R = F, 96%
e, R = Cl, 84%
f, R = Br, 81%
g, R = NO2, 10%
h, R = CF3, 30%
i, R = Ph, 80%
+
CH3CN (2 ml)
50 °C, 6 h
1a
10
11
O
O
O
Me
NH
S
Me
NH
S
O
11a, R = H, 61%
R
11g, 53%
1
1
1
1
1b, R = Me, 45%
Me
NH
Me
NH
t
1c, R = Bu, 54%
S
S
O
Ph
1d, R = OMe, 50%
1e, R = Cl, 42%
3o, R = 2,4,6-Me, 75%
3p, 73%
Ph
Me
NH
Me
R
11f, R = Br, 49%
O
O
S
Me
Ph
rac-3e
Me
NH
S
Me
NH
S
11h, 39%
O
Me
trans-3r, 49%a
Scheme 6 Substrate scope for thiylation: 1a (0.2 mmol), 10 (0.4 mmol, 2.0 equiv.), BPO
trans-3q, 30%a
(0.3 mmol, 1.5 equiv.), HPF (0.2 mmol, 1.0 equiv.) and CH CN (2 ml), Ar, isolated yield.
6
3
R
NH
O
s, R = Me, 92%a
3v, R = Pr, 41%
i
a
3
3
3
t, R = Et, 72%a
3w, R = Bu, 51%a
3x, R = Ph, 40%a
t
n
a
Substrates not capable of initiating BPO decomposition
obviously fail in this reaction. However, addition of extra
initiators may overcome this limitation. We found that
addition of N,N-dimethylanilines, well-known initiators for
u
,
R
=
P
r
,
8
1
%
Scheme 4 Substrate scope for the reaction of styrenes and nitriles: 1 (0.2 mmol), 2 (0.4
mmol, 2.0 equiv.), BPO (0.3 mmol, 1.5 equiv.), HPF (0.2 mmol, 1.0 equiv.) and nitriles
2 ml), Ar, isolated yield. a Reaction time: 6 hours. ORTEP diagram is drawn with
displacement ellipsoids at the 50% probability level.
6
(
1
8
BPO, enable the addition of two molecules of acetonitrile to
styrene, furnishing 13 (Scheme 7). Although the yields are not
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J. Name., 2013, 00, 1-3 | 3
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5 For C-radicals, see: (a) P. G. Janson, I. Ghoneim, N. O.
as high as with Cu-catalysts,11 48% is reached with the use of
View Article Online
Ilchenko and K. J. Szabó, Org. Lett., 2012, 14, 2882; (b) H.
DOI: 10.1039/C9CC09369A
Egami, R. Shimizu and M. Sodeoka, Tetrahedron Lett., 2012,
1
0 mol% of the p-bromo aniline. The product yield is obviously
linked to the initiation rate and electronic properties of the
anilines, as the comparison with more and less electron rich
derivatives shows.
5
1
3, 5503; (c) Y. Yasu, T. Koike and M. Akita, Org. Lett., 2013,
5, 2136; (d) A. Carboni, G. Dagousset, E. Magnier and G.
Masson, Org. Lett., 2014, 16, 1240; (e) H. Yi, X. Zhang, C. Qin,
Z. Liao, J. Liu and A. Lei, Adv. Synth. Catal., 2014, 356, 2873;
O
(f) C. Chatalova-Sazepin, Q. Wang, G. M. Sammis and J. Zhu,
BPO (1.5 equiv.)
HPF6 55% (1.3 equiv.)
Angew. Chem. Int. Ed., 2015, 54, 5443; (g) Y.-Y. Liu, X.-H.
Yang, R.-J. Song, S. Luo and J.-H. Li, Nat. Commun., 2017, 8,
14720; (h) B. Qian, S. Chen, T. Wang, X. Zhang and H. Bao, J.
Am. Chem. Soc., 2017, 139, 13076; (i) S. N. Gockel, T. L.
Buchanan and K. L. Hull, J. Am. Chem. Soc., 2018, 140, 58; (j)
W. Deng, W. Feng, Y. Li and H. Bao, Org. Lett., 2018, 20,
NH
Ph
+
N
Ar
CH3CN (30 ml)
70 °C, 18 h
Ph
CN
1a
12
13
(1.0 equiv.)
(10 mol%)
N
N
N
N
N
4
245; (k) R. Su, Y. Li, M.-Y. Min, X.-H. Ouyang, R.-J. Song and
J.-H. Li, Chem. Commun., 2018, 54, 13511; (l) Y.-X. Dong, Y. Li,
C.-C. Gu, S.-S. Jiang, R.-J. Song and J.-H. Li, Org. Lett., 2018,
CH3
Br
CN
NO2
1
0% 13
25% 13
48% 13
21% 13
11% 13
2
0, 7594; (m) X.-H. Ouyang, Y. Li, R.-J. Song, M. Hu, S. Luo
Scheme 7 Investigating dimethylaniline initiators: 1a (0.5 mmol), BPO (0.75 mmol, 1.5
equiv.), HPF (0.66 mmol, 1.3 equiv.), 12 (0.05 mmol) and CH CN (30 ml), isolated yield.
and J.-H. Li, Sci. Adv., 2019, 5, eaav9839.
6
3
6
For heteroatom-radicals, see: (a) Y. Gao, X. Li, W. Chen, G.
Tang and Y. Zhao, J. Org. Chem., 2015, 80, 11398; (b) Y. Yang,
R.-J. Song, X.-H. Ouyang, C.-Y. Wang, J.-H. Li and S. Luo,
Angew. Chem. Int. Ed., 2017, 56, 7916; (c) B. Du, Y. Wang, H.
Mei, J. Han and Y. Pan, Adv. Synth. Catal., 2017, 359, 1684;
(d) Y. Wang, W. Wang, R. Tang, Z. Liu, W. Tao and Z. Fang,
Org. Biomol. Chem., 2018, 16, 7782.
In conclusion, a method for the difunctionalization of styrenes
with radicals derived from thioxanthene, xanthene and
thiophenols together with nitrile and alcohol nucleophiles was
6
developed. The combination of benzoyl peroxide with HPF , a
7
8
N. Noto, T. Koike and M. Akita, Chem. Sci., 2017, 8, 6375.
Y. Zheng, Y. He, G. Rong, X. Zhang, Y. Weng, K. Dong, X. Xu
and J. Mao, Org. Lett., 2015, 17, 5444.
Y. Yuan, Y. Cao, Y. Lin, Y. Li, Z. Huang and A. Lei, ACS Catal.,
2018, 8, 10871.
strong Brønsted acid, is a key element of the reaction that
does not require transition-metal catalysts, high temperatures
or prolonged reaction times. Mechanistic studies suggest that
the acid can promote the electron transfer to the peroxide,
9
and that the reaction proceeds by a radical chain that is 10 (a) B. Schweitzer-Chaput, A. Sud, Á. Pinter, S. Dehn, P.
Schulze and M. Klussmann, Angew. Chem. Int. Ed., 2013, 52,
initiated by interaction of the radical precursor with the
1
3228; (b) B. Schweitzer-Chaput, J. Demaerel, H. Engler and
peroxide. Addition of an extra radical initiator can overcome
this limitation, which suggests a way to extend this synthetic
strategy.
M.K. thanks the DFG (KL 2221/4-2, Heisenberg scholarship)
and S. L. thanks the China Scholarship Council (CSC, doctoral
scholarship No. 201808420290). We are grateful for the help
of the analytical departments of the MPI für Kohlenforschung
and for help in cyclic voltammetry measurements by Dr.
Yuxiao Ding (MPI for Chemical Energy Conversion).
M. Klussmann, Angew. Chem. Int. Ed., 2014, 53, 8737; (c) B.
Schweitzer-Chaput, T. Kurtén and M. Klussmann, Angew.
Chem. Int. Ed., 2015, 54, 11848; (d) H.-L. Yue and M.
Klussmann, Synlett, 2016, 27, 2505; (e) B. Schweitzer-
Chaput, E. Boess and M. Klussmann, Org. Lett., 2016, 18,
4
944; (f) W. Shao, M. Lux, M. Breugst and M. Klussmann,
Org. Chem. Front., 2019, 6, 1796.
1 N. Zhu, T. Wang, L. Ge, Y. Li, X. Zhang and H. Bao, Org. Lett.,
2017, 19, 4718.
1
12 (a) B. H. Hoff, Synthesis, 2018, 50, 2824; (b) D. Jiang, T. He, L.
Ma and Z. Wang, RSC Adv., 2014, 4, 64936.
3 (a) M. Milan, M. Salamone, M. Costas and M. Bietti, Acc.
Chem. Res., 2018, 51, 1984; (b) T. V. RajanBabu and F.
Gagosz, in Encyclopedia of Reagents for Organic Synthesis,
2005, DOI: 10.1002/047084289X.rd022.pub2.
4 C. S. Sheppard, in Encyclopedia of polymer science and
engineering, John Wiley & Sons, Inc., 1985, vol. 11, pp. 1.
5 A. Studer and D. P. Curran, Nat Chem, 2014, 6, 765.
6 The induced decomposition of BPO could also be shown for
the other radical precursors used in this study, see the
Supporting Information for details.
1
Conflicts of interest
There are no conflicts to declare.
1
1
1
Notes and references
1
For a review, see: (a) J.-S. Zhang, L. Liu, T. Chen and L.-B. Han,
Chem. Asian J., 2018, 13, 2277; (b) F. Wang, X. Qi, Z. Liang, P.
Chen and G. Liu, Angew. Chem. Int. Ed., 2014, 53, 1881; (c) A.
Bunescu, Q. Wang and J. Zhu, Angew. Chem. Int. Ed., 2015,
4, 3132.
(a) X.-W. Lan, N.-X. Wang and Y. Xing, Eur. J. Org. Chem.,
017, 2017, 5821; (b) H. Yi, G. Zhang, H. Wang, Z. Huang, J.
1
7 (a) A. Bewick, J. M. Mellor and W. M. Owton, J. Chem. Soc.,
Perkin Trans. 1, 1985, 1039; (b) L. Benati, P. C. Montevecchi
and P. Spagnolo, J. Chem. Soc., Perkin Trans. 1, 1987, 2815;
5
(c) H. Cui, X. Liu, W. Wei, D. Yang, C. He, T. Zhang and H.
2
Wang, J. Org. Chem., 2016, 81, 2252; (d) D. Wang, Z. Yan, Q.
Xie, R. Zhang, S. Lin and Y. Wang, Org. Biomol. Chem., 2017,
2
Wang, A. K. Singh and A. Lei, Chem. Rev., 2017, 117, 9016; (c)
H. Egami and M. Sodeoka, Angew. Chem. Int. Ed., 2014, 53,
1
5, 1998.
1
8 (a) L. Horner and E. Schwenk, Liebigs Ann. Chem., 1950, 566,
8
2
294; (d) H. Fischer and L. Radom, Angew. Chem. Int. Ed.,
001, 40, 1340.
6
1
9; (b) A. Székely and M. Klussmann, Chem. Asian J., 2019,
4, 105.
3
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F. Minisci, Acc. Chem. Res., 1975, 8, 165.
For an overview of early methods using stoichiometric
3
Mn(OAc) , see: G. G. Melikyan, Synthesis, 1993, 1993, 833.
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| J. Name., 2012, 00, 1-3
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