Intramolecular 1,5-H transfer reaction of aryl iodides through visible-light photoredox catalysis: A concise method for the synthesis of natural product scaffolds

Article abstract of DOI:10.1039/c6cc02007k

The intramolecular 1,5-H transfer reaction of the aryl radicals generated from unactivated aryl iodides by photocatalysis is described. The features of this transformation are operational simplicity, excellent yields, mild reaction conditions, and good fu

Full text of DOI:10.1039/c6cc02007k

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COMMUNICATION
Intramolecular 1,5-H transfer reaction of aryl iodides through
visible-light photoredox catalysis: a concise method for the
synthesis of the natural product scaffolds
Received 00th January 20xx,
Accepted 00th January 20xx
Jian-Qiang Chen, Yun-Long Wei, Guo-Qiang Xu, Yong-Min Liang and Peng-Fei Xu*
DOI: 10.1039/x0xx00000x
www.rsc.org/
The intramolecular 1,5-H transfer reaction of the aryl radicals aryl iodides, could be employed in the reduction and reductive
generated from unactivited aryl iodides by photocatalysis is cyclization reactions under mild conditions, respectively. We
described. The features of this transformation are operational envisioned that intramolecular 1,5-H transfer reaction of aryl
simplicity, excellent yields, mild reaction conditions, and good iodides might also be realized through visible-light photoredox
functional group tolerance. With this approach, a more concise catalysis under mild conditions without using toxic reagents.
formal synthesis of (±)-coerulescine and (±)-physovenine is One of the difficult problems to address is to avoid the process
accomplished.
of reductive dehalogenation, as shown in Figure 1.
From our initial test results, we were delighted to find that
visible light photoredox catalysis could truly catalyze the
intramolecular 1,5-HAT reaction of o-anilide aryl radicals. The
proposed mechanism of this reaction is illustrated in Scheme
Hydrogen-atom transfer is a reliable and widely used process
in radical-mediated reactions and therefore a powerful tool to
perform chemical transformations. In particular, intramolec-
ular 1,5-H atom transfer (HAT) reactions have been extensively
investigated and numerous applications have been described
in organic synthesis.1-3 For these reactions, highly reactive aryl
and alkenyl free radicals are often involved to achieve the
useful radical translocations.3 Despite the importance of this
type of reactions, one of the several limitations of the
traditional methods is the requirement of superstoichiometric
quantities of hazardous reagents such as tributyltin hydride,
azobisisobutyronitrile (AIBN), etc. to generate and/or
terminate the free radicals.3a-3c Another limitation is that high
temperature is often required to initiate these reactions and
significant amounts of waste byproducts will be produced. All
these drawbacks restrict the broad applications of the
traditional methods in modern synthetic chemistry. In this
context, we are interested in exploring new approaches to
overcome these limitations.
1. Irradiation of photocatalyst fac-Ir(ppy)3 (6) [ppy = 2-
phenylpyridine] with visible light generates a long-lived (τ = 1.9
red
µs)4a photoexcited state, fac-*Ir(ppy)3
(
7
)
(E1/2
[fac-
Ir(ppy)3 /fac-*Ir(ppy)3] = − 1.73 V vs SCE),5 which is a strong
electron donor to reduce the substrate. The unactivated aryl
iodide (E1/2red = − 1.59 V vs SCE for iodobenzene)7 can accept a
+
single electron from fac-*Ir(ppy)3 (7) and then produce the
highly activated aryl radical, which undergoes an intramole-
cular 1,5-HAT reaction and provides the stabilized tertiary
carbon radical (
4
).3d,e Species
4
is then converted to the
cyclohexadienyl radical
(5)
through cyclization.8 In the
meantime, single electron transfer (SET) from excited state of
During the past several years, visible light photocatalysis
has attracted a great deal of attention from researchers in
organic synthesis.4 Harnessing of energy from visible light as
an inexpensive and abundant means to construct complex
organic molecules has emerged as a promising method in
organic chemistry. Stephenson5 and Lee6 have showed that
aryl radicals, generated by photoredox reaction of unactivated
Fig. 1. Different reactions for the aryl halides.
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Table 1 Initial studies and reaction optimization.a
H
H
1.5-HAT
O
N
O
N
N
O
I
5
4
3
fac-Ir(ppy)3
R3N
10
8
H
N
*
fac-Ir(ppy)3
O
O
7
I
1a
N
2a
hv
R3NH
11
R3N
9
fac-Ir(ppy)3
6
Scheme 1 Proposed mechanism for the 1,5-HAT reaction.
Yield
Entry
Catalyst
Base
Solvent (v/v)
Time
(%)b
+
fac-*Ir(ppy)3
(
7
) to 1a provides the oxidized fac-Ir(ppy)3
+
(
8
),
which is a powerful oxidant (E1/2red [fac-Ir(ppy)3 /fac-Ir(ppy)3] =
+ 0.77 V vs SCE).4a In the presence of the tertiary amine as the
1
Ru(bpy)3Cl2
fac-Ir(ppy)3
[Ir(ppy)2(dtbbpy)]PF6
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
fac-Ir(ppy)3
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
Et3N
MeCN
24h
24h
24h
24h
7d
0
2
MeCN
37
10
57
78
46
44
67
46
51
82
87
75
77
+
stoichiometric reductant, fac-Ir(ppy)3
(
8
) can be converted to
3
MeCN
the corresponding ground state photocatalyst and complete
the photoredox cycle. Finally, the generated cation radical (10
undergoes hydrogen atom abstraction from the cyclohexad-
ienyl radical (
) to give the final product.9
4
CH2Cl2
)
5
THF
5
6
EA
5d
Based on the initial test reaction, we began our
investigation by screening conditions for the intramolecular
1,5-HAT reaction of o-anilide aryl iodide (1a). To our delight,
the only desired 1,5-HAT product (in a modest 37% yield) was
observed at 20oC by irradiation with a 25W blue LED strip
when fac-Ir(ppy)3 was used as the photocatalyst and N,N-
diisopropylethylamine (DIPEA) as the organic base (entry 2).5
But the reaction did not occur under Ru(bpy)3Cl2 catalysis
(entry 1). Meanwhile, when [Ir(ppy)2(dtbbpy)]PF6 was used
instead of fac-Ir(ppy)3, the yield of the product, accompanied
with the appearance of undesired reduction product (60%
yield), was decreased to 10% (Scheme 2).6 The examination of
the solvents revealed that THF produced better yield, but the
reaction took much longer time to complete (entry 5).
Compared with THF, when a 1:1 THF/acetone or 7:1 THF/H2O
solvent system was used, slight improvement of yield but
dramatical diminution of the reaction time could be observed
(entries 11 and 12). The role of acetone or water was likely to
increase the solubility of the byproduct, solid N,N-
diisopropylethylaminehydriodate (iPr2NEt.HI), which could
hinder the photocatalyst from absorbing visible light. Next, the
organic base as another crucial reaction parameter was also
explored, and the optimal one was found to be DIPEA with
87% yield (entry 12). Interestingly, when 2,6-lutidine or K2HPO4
was used as the base instead of DIPEA, the reaction did not
occur. This phenomenon indicated that DIPEA not only acted
as the acid acceptor, but also joined the photocatalyst cycle.
Lastly, control experiments demonstrated that an organic
base, a photocatalyst, and a light source are all necessary in
this intramolecular 1,5-HAT protocol (see ESI).10
7
DMSO
12h
36h
36h
12h
60h
60h
60h
60h
8
Acetone
MeOH
9
10
11
12
13
14
DMF
THF/H2O(7:1)
THF/Acetone(1:1)
THF/Acetone(1:1)
THF/Acetone(1:1)
Bu3N
2,6-
lutidine
15
16
fac-Ir(ppy)3
fac-Ir(ppy)3
THF/Acetone(1:1)
THF/Acetone(1:1)
60h
60h
0
0
K2HPO4
a Unless otherwise noted, the reaction of 1a (0.2 mmol) was carried out in the presence
of the photocatalyst (0.002 mmol) in the indicated solvent (4.0 mL) with a 25W blue
LED strip at 20oC. b Isolated yield.
Scheme 2 [Ir(ppy)2(dtbbpy)]PF6 was used as the photocatalyst
amide proceeded smoothly to give the corresponding 3,3-
dialkyloxindole (2b-2h) in good to high yields. Substrates with
a double bond or a hetero atom in the alkyl group at the α-
position of the amide could readily convert into target
compounds
(
2i-2j
)
without any undesired reduction
byproducts. On the other hand, the same observation was
made for 4-bromo-2-iodophenylamides (2m and 2s, with the
yield of 80% and 86%, respectively) which are not tolerant in
the traditional conditions. We believe that this result can be
With the optimized conditions in hand, we next focused
our attention on the scope of the substrate. As shown in Table
2, a variety of substituted o-anilide aryl iodides (1) were
investigated by using fac-Ir(ppy)3 as the photocatalyt. The
reaction of substrates bearing dialkyl group at α-position of the
red
rationalized by their more negative reduction potentials (E1/2
2 | J. Name., 2012, 00, 1-3
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= − 2.07 V vs SCE for bromobenzene)7 than the activated
COMMUNICATION
Boc
I
N
Ir(ppy)3(1 mol%)
O
iPr2NEt (5 equiv), THF/acetone (1:1)
red
+
20oC,N2, blue LED strip, 60h
O
N
photocatalyst fac-*Ir(ppy)3
*Ir(ppy)3] = − 1.73 V vs SCE). The results in table
that o-anilide aryl iodides with electron-withdrawing
(
7)
(E1/2
[fac-Ir(ppy)3 /fac-
N
Boc
N
2
also show
1ad
2ad 65% yield
(1)
Boc
N
N
substituents gave better yields than those with electron-
donating substituents (2k–2p vs 2w–2x). However, electron-
rich o-anilide aryl iodides required longer reaction times for
full convertion into the products. In contrast, the unprotected
o-anilide aryl iodide was entirely transformed into the product
of reductive dehalogenation (2ab).
i). BPO, CH2Cl2, 80oC, 18h
ii). NaOH, MeOH, rt, 18h
ref. 13
O
O
iii). NH3, MeOH, rt, 4h
N
N
H
H
(±)-coerulescine
3ad 43% yield
OH
OH
Ir(ppy)3 (1 mol%)
iPr2NEt (5 equiv), THF/acetone (1:1)
O
N
N
O
Since the oxindole moiety is widely found in the core
structure of natural alkaloids and bioactive compounds, our
group have focused much attention on the synthesis of the
oxindole derivatives.11 This convenient method mentioned
above will be potentially useful for the synthesis of natural
products containing the oxindole moiety. With this in mind, we
decided to apply this powerful approach to the synthesis of
the bioactive alkaloid coerulescine, which was isolated from
20oC,N2, blue LED strip, 96h
I
2ae 88% yield
1ae
Me
HN
O
ref. 16
O
LiAlH4
O
O
N
THF, rt
N
(±)-physovenine
Scheme 3 Formal synthesis of coerulescine and physovenine
3ae 80% yield
the blue canary grass phalaris coerulescens in 1998 by stereocenter in the spirocyclic oxindole moiety. Now, this
Colegate’s group.12 In the past, one of the main challenges to challenge can be easily overcome with this new method
address was how to construct the all-carbon quaternary
(Scheme 3). Spirooxindole 2ad was deprotected uneventfully
to compound 3ad, which can be smoothly transformed into
coerulescine, as demonstrated by Suárez-Castillo et al.13 In
order to further widen the application of this intramolecular
1,5-H atom transformation method, we applied it to the
formal synthesis of another natural alkaloid, physovenine,
which has been synthesized by many groups.14-16 Treatment of
Table 2 Intramolecular 1,5-HAT reaction: scope of the substrate.a,b
4-hydroxy-N-(2-iodophenyl)-N,2-dimethylbut-anamide
(
1ae
)
with the general condition afforded the desired product (2ae
)
O
O
O
O
O
O
in 88% yield after 96h, which was subsequently subjected to
the reduction with LAH providing the cyclization product
N
N
N
N
2e 87%
2c 93%
2d 90%
2b 67%
(
3ae).15 Additional modification of 3ae afforded (±)-
physovenine.16 Based on this procedure, we created a concise
synthetic route to form physovenine by using this visible light
photoredox catalysis as the critical step.
O
O
N
N
N
N
2g 83%
2h 67%
2f 89%
2i 65%
O
Under the similar reaction conditions, reactant 1af was
also converted into the corresponding desired product 2af
(scheme 4).17 In this transformation, we realized the functi-
onalization of the unreactive tertiary aliphatic C−H bond
through visible light photocatalysis.
2k, R1 F (87%)
2l, R1 Cl (82%)
NC
R1
2m, R1 Br (80%)
O
O
O
1
N
N
N
2n
, R
CN (89%)
2o, R1 CF3 (92%)
2p, R1 CO2Me (90%)
2q 88%
2k-2p
2j
70%
The proposed mechanism of the visible light catalyzed
F3C
Cl
Br
F
intramolecular 1,5-HAT reaction is illustrated in Scheme 1. It
O
O
O
O
O
N
can also support the transformation of m-substituent of
reactant (1ag) to a mixture of 2ag and 2ag’ with a ratio of 2:1
after 96h (scheme 5).18
N
N
N
2u 92%
2r 82%
2s 86%
2t 80%
OTBS
O
NC
O
N
O
O
N
N
N
d
2w 70%c
2x
77%
H
2y 64%
2v 86%
I
H
O
O
O
O
N
H
N
N
Scheme 4 Functionalization of the unreactive C−H bond
N
N
Ph
1ac
n.r.
2ab 95%
2aa 20%
2z 65%
different reactions for other types of substrates
a
Reaction conditions: photocatalyst (0.002 mmol), DIPEA (1.0 mmol), reactant (0.2
mmol) in THF/Acetone (1:1) (4 mL), at 20oC，under N2 atmosphere, with a 25W blue
d
LED strip, with reaction time of 60h. b Isolated yields. c Reaction time 96h. Reaction
Scheme 5 Transformation of the m-substituted reactant
time 108h. n.r. = no reaction.
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Nechab and M. P. Bertrand, J. Org. Chem., 2012, 77, 2773; (j)
G. Lejeune, J. Font, T. Parella, R. Alibés, M. Figueredo, J. Org.
Chem., 2015, 80, 9437; (k) F. -Q. Huang, X. Dong, L. -W. Qi, B.
Zhang, Tetrahedron Lett., 2016, 57, 1600.
In conclusion, we have developed
a
visible-light
photoredox catalysis approach to achieve the intramolecular
1,5-H transfer reaction of o-anilide aryl iodides. In contrast to
conventional methods, this approach does not require
superstoichiometric quantities of toxic reagents. Furthermore,
this reaction features operational simplicity, mild reaction
conditions, exceptional functional group tolerance and good to
excellent yields. Therefore, the method described herein
makes a significant complementation to the research fields of
HAT reactions and photoredox catalysis. The practicability of
this transformation has also been demonstrated in the more
concise formal synthesis of (±)-coerulescine and (±)-
physovenine in comparison with previous work.
4
For selected review, see: (a) C. K. Prier, D. A. Rankic, D. W. C.
5322; (b) M.
MacMillan, Chem. Rev., 2013, 113,
Reckenthaler, A. G. Griesbeck, Adv. Synth. Catal., 2013, 355
,
2727; (c) M. N. Hopkinson, B. Sahoo, J. L. Li and F. Glorius,
Chem. Eur. J., 2014, 20, 3874; (d) J. W. Beatty and C. R. J.
Stephenson, Acc. Chem. Res., 2015, 48, 1474; (e) C. Wang
and Z. Lu, Org. Chem. Front., 2015, 2, 179; (f) E. Meggers,
Chem. Commum., 2015, 51, 3290; (g) J. Xuan and W. -J. Xiao,
Angew. Chem. Int. Ed., 2012, 51, 6828; (h) J. -R. Chen, X. -Q.
Hu, L. -Q. Lu and W. -J. Xiao, Chem. Soc. Rev., 2016, 45, DOI:
10.1039/C5CS00655D.
J. D. Nguyen, E. M. D’Amato, J. M. R. Narayanam and C. R. J.
Stephenson, Nature. Chem., 2012, 4, 854.
E. Kim, C. Lee, Angew. Chem. Int. Ed., 2012, 51, 12303.
(a) A. J. Fry and R. L. Krieger, J. Org. Chem., 1976, 41, 54; (b)
L. Pause, M. Robert and J. M. Savéant, J. Am. Chem. Soc.,
1999, 121, 7158.
5
We are grateful to the NSFC (21172097, 21202070,
21302075 and 21372105), the International S&T Cooperation
Program of China (2013DFR70580), and the “111” program
from MOE of P. R. China.
6
7
8
9
Selected examples: (a) F. Gao, C. Yang, G. -L. Gao, L. Zheng,
W. Xia, Org. Lett., 2015. 17. 3478; (b) J. Xie, P. Xu, H. Li, Q.
Xue, H. Jin, Y. Cheng, C. Zhu, Chem. Commun., 2013, 49, 5672;
(c) G. -Q. Xu, C. -G. Li, M. -Q. Liu, J. Cao, Y. -C. Luo and P. -F.
Xu, Chem. Commun., 2015, 51, 1190.
Notes and references
1
For selected examples of 1,5 H-abstraction initiated by an
oxygen radical, see: (a) D. H. R. Barton, J. M. Beaton, L. E.
Geller and M. M. Pechet, J. Am. Chem. Soc., 1960, 82, 2640;
(b) D. H. R. Barton, J. M. Beaton, L. E. Geller and M.
M.Pechet, J. Am. Chem. Soc., 1961, 83, 4076; (c) M. L.
Mihailović and M. Miloradović, Tetrahedron, 1966, 22, 723;
(d) J. I. Concepción, C. G. Francisco, R. Hernández, J. A.
Salazar and E. Suárez, Tetrahedron Lett., 1984, 25, 1953; (e)
M. J. Robins, Z. Guo, M. C. Samano and S. F. Wnuk, J. Am.
Chem. Soc., 1996, 118, 11317; (f) D. Crich, X. Huang and M.
J. L. Jeffrey, F. R. Petronijević and D. W. C. MacMillan, J. Am.
Chem. Soc., 2015, 137, 8404.
10 See the Supporting Information for details on the
optimization studies and control experiments (table 1).
11 (a) T. -P. Gao, J. -B. Lin, X. -Q. Hu and P. -F. Xu, Chem.
Commun., 2014, 50, 8934; (b) S. Zhao, J. -B. Lin, Y. -Y. Zhao, Y.
-M. Liang and P. -F. Xu, Org. Lett., 2014, 16,1802; (c) L. Tian,
X. -Q. Hu, Y. -H. Li and P. -F. Xu, Chem. Commun., 2013, 49
7213.
,
Newcomb, Org. Lett., 1999, 1, 225; (g) C. G. Francisco, A. J.
12 N. Anderton, P. A. Cockrum, S. M. Colegate, J. A. Edgar, K.
Flower, I. Vit and R. I. Willing, Phytochemistry, 1998, 48, 437.
13 O. R. Suárez-Castillo, M. Meléndez-Rodríguez, Y. M.
Contreras-Martínez, A. Alvarez-Hernández, M. S. Morales-
Herrera and E. Suárez, J. Org. Chem., 2002, 67, 7439; (h) H.
Zhu, J. G. Wickenden, N. E. Campbell, J. C. T. Leung, K. M.
Johnson and G. M. Sammis, Org. Lett., 2009, 11, 2019; (i) R.
Kundu, Z. T. Ball, Org. Lett., 2010, 12, 2460; (j) J. Zhang, Y. Li,
F. Zhang, C. Hu, and Y. Chen, Angew. Chem. Int. Ed., 2016,
55, 1872.
Ríos and P. Joseph-Nathan, Nat. Prod. Commun., 2009, 4,
797.
14 (a) T. Sunazuka, K. Yoshida, N. Kojima, T. Shirahata, T Hirose,
M. Handa, D. Yamamoto, Y. Harigaya, I. Kuwajima and S.
Omura, Tetrahedron Lett., 2005, 46, 1459; (b) W. -H. Chiou, C.
-L. Kao, J. -C. Tsai and Y. -M. Chang, Chem. Commun., 2013,
49, 8232; (c) T. Matsuura, L. E. Overman and D. J. Poon, J. Am.
Chem. Soc., 1998, 120, 6500; (d) K. Shishido, E. Shitara, H.
Komatsu, K. Hiroya, K. Fukumoto and T. Kametani, J. Org.
Chem., 1986, 51,3007; (e) S. Takano, M. Moriya and K.
Ogasawara, J. Org. Chem. 1991, 56, 5982; (f) B. Zhou, W.
Hou, Y. Yang, H. Feng and Y. Li, Org. Lett., 2014, 16, 1322; (g)
2
For selected examples of 1,5 H-abstraction initiated by a
nitrogen radical, see: (a) E. J. Corey and W. R. Hertler, J. Am.
Chem. Soc., 1960, 82, 1657; (b) C. G. Francisco, A. J. Herrera
and E. Suárez, J. Org. Chem., 2003, 68, 1012; (c) A. Martin, I.
Perez-Martin and E. Suarez, Org. Lett., 2005,
Reddy, B. V. S. Reddy and E. J. Corey, Org. Lett., 2006,
7, 2027; (d) L. R.
8,
2819; (e) C. G. Francisco, A. J. Herrera, A. Martin, I.Perez-
Martin and E. Suarez, Tetrahedron Lett., 2007, 48, 6384; (f)
R. Fan, D. Pu, F. Wen and J. Wu, J. Org. Chem., 2007, 72
,
8994; (g) T. Liu, T. -S. Mei and J. -Q. Yu, J. Am. Chem. Soc.,
2015, 137, 5871.
For selected examples of 1,5 H-abstraction initiated by a
carbon (sp2) radical, see: (a) D. P. Curran, D. Kim, H. T. Liu
and W. Shen, J. Am. Chem. Soc.,1988, 110, 5900; (b) D. P.
S. De, M. K. Das, S. Bhunia and A. Bisai, Org. Lett. 2015, 17
5922.
,
3
15 (a) T. Y. Zhang and H. Zhang, Tetrahedron Lett., 2002. 43
1363; (b) A. J. Clark and K, Jones, Tetrahedron, 1992, 48
6875.
.
,
Curran, A. C. Abraham and H. Liu, J. Org. Chem., 1991, 56
4337; (c) D. P. Curran and J. Xu, J. Am. Chem. Soc., 1996, 118
,
,
16 M. G. Kulkarni, A. P. Dhondge, A. S. Borhade, D. D. Gaikwad,
S. W. Chavhan, Y. B. Shaikh, V. B. Nigdale, M. P. Desai, D. R.
Birhade and M.P. Shinde, Eur. J. Org. Chem., 2009, 3875.
17 B. S. Bhakuni, A. Yadav, S. Kumar, S. Patel, S. Sharma, and S.
Kumar, J. Org. Chem., 2014, 79, 2944.
18 (a) B. S. Bhakuni, A. Yadav, S. Kumar, S. Patel, S. Sharma and
S. Kumar, J. Org. Chem., 2014, 79, 2944; (b) Q. Dai, J. Yu, Y.
Jiang, S. Guo, H. Yang and J. Cheng, Chem. Commun., 2014,
50, 3865.
3142; (d) T. A. Khan, R Tripoli, J. J. Crawford, C. G. Martin and
J. A. Murphy, Org. Lett., 2003. . 2971; (e) A. L. J. Beckwith,
5
V. W. Bowry, W. R. Bowman, E. Mann, J. Parr and J. M. D.
Storey, Angew. Chem. Int. Ed., 2004, 43, 95; (f) V. Rey, A. B.
Pierini and A. B. Penenory, J. Org. Chem., 2009, 74, 1223; (g)
M. E. Wood, S. Bissiriou, C. Lowe, A. M. Norrish, K. Sénéchal,
K. M. Windeatt, S. J. Coles and M. B. Hursthouse, Org.
Biomol. Chem., 2010, 8, 4653; (h) M. Nechab, D. Campolo, J.
Maury, P. Perfetti, N. Vanthuyne, D. Siri and M. P. Bertrand,
J. Am. Chem. Soc., 2010, 132, 14742; (i) D. Campolo, A.
Gaudel-Siri, S. Mondal, D. Siri, E. Besson, N. Vanthuyne, M.
4 | J. Name., 2012, 00, 1-3
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