A direct cross-coupling reaction of electron-deficient alkenes using an oxidizing directing group

Article abstract of DOI:10.1039/c6cc07064g

An oxidant-free cross-coupling reaction of electron-deficient alkenes using an inexpensive ruthenium catalyst is reported. With the assistance of the oxidizing directing group CONH(OMe), this protocol provides a mild, straightforward and efficient method for the preparation of valuable 1,3-butadiene skeletons with excellent Z,E selectivities.

Full text of DOI:10.1039/c6cc07064g

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ARTICLE TYPE
Direct Cross-Coupling Reaction of Electron-Deficient Alkenes Using an
Oxidizing Directing Group†
Chunbing Yu, Feifei Li, Jian Zhang,* and Guofu Zhong*
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
5
DOI: 10.1039/b000000x
coupling of unactivated alkenes via a double C-H bond activation
pathway would undoubtedly be an extremely attractive process
for the preparation of 1,3-butadienes.8-10 Very recently, Loh
group reported a stereo- and chemo-selective cross-coupling
50 between simple acrylates, providing an efficient route to (Z,E)-
muconate derivatives, but the reaction should be performed at
135 oC and 2.0 equiv. Cu(OAc)2 was required as oxidant.10e
Meanwhile, a selective alkenylation of enol phosphates via direct
C-H functionalization was reported by the same group, also using
55 quantitative amount of metal oxidant (Scheme 1, eq 1).10f Herein,
we describe a novel redox-neutral (2Z,4E)-dienamide synthesis
employing oxidizing directing group under very simple and mild
reaction conditions (Scheme 1, eq 2).
An oxidant-free cross-coupling reaction of electron-deficient
alkenes using inexpensive ruthenium catalyst is reported.
With the assistance of the oxidizing directing group
CONH(OMe), this protocol provides a mild, straightforward
10 and efficient method for the preparation of valuable 1,3-
butadiene skeletons with excellent Z,E selectivities.
Over the past decades, transition-metal-catalyzed direct C-H
bond functionalizations have attracted significant interest,
because these transformations realize the activation of inert C-H
15 bonds, thus allowing the use of cheaper and readily available
starting materials with increased sustainability.1 One of the most
popular strategies to obtain a chemo- and regioselective C-H
activation is the introduction of a directing group (DG) that
directs functionalization to the desired position.2 However, such
20 C-H bond transformations generally require external metal or
non-metal oxidants to regenerate the active catalytic species and
complete the catalytic cycle, and most of which are usually
performed under rather harsh oxidative conditions and provide
stoichiometric amounts of the reduced oxidant as waste, reducing
25 the overall “greenness” of the process. Recently, Ackermann
group reported a ruthenium(II)-catalyzed oxidative alkenylation
reactions with ambient oxygen as the sole oxidant.3 Jeganmohan
and co-workers also disclosed a ruthenium-catalyzed alkenylation
of arenes at room temperature with hydrogen evolution.4 These
30 examples represent two strategies to overcome those drawbacks
by reducing waste formation from oxidant. Another emerging
strategy in the realm of C-H activation chemistry is the
application of an internal oxidizing directing group (DGOx) that
acts as both a directing group and an internal oxidant for redox-
35 neutral coupling reactions.5 Recently, several N-O containing
directing groups such as N-methoxy, N-oxide, N-acyloxy, nitroso
and even hydrazine groups are demonstrated to be popular and
useful oxidizing directing groups.6 These results have numerous
advantages: the reaction proceeds under mild conditions, is very
40 practical and completely regio- and mono-selective, and most
importantly, results in improved yields and substrate scope.
60
Scheme 1 Directed cross-coupling of alkenes.
The first step of the present work was the installation of
suitable directing group to an alkene. Concerning the subsequent
65 cross-coupling step, the initial optimization experiments were
performed with N-methoxy-2-methyl-2-propenamide (1a) derived
from methacrylic acid and n-butyl acrylate (2a), in the presence
of inexpensive [Ru(p-cymene)Cl2]211 (5.0 mol%) and NaOAc (30
mol%) in DCE at 60 oC as the catalytic conditions, but the
70 reaction afforded desired 1,3-dienamide 3a in only 19% yield
(Table 1, entry 1). After screening a series of representative
solvents, we were pleased to find that the yield was increased to
49% when the reaction was performed in N,N-dimethyl
formamide (DMF) (Table 1, entry 2). In contrast, it is worthy to
75 note that other polar solvents such as DMSO and THF even
afforded no desired product (Table 1, entries 4 and 5).
Considering that basicity may influence the reaction, then
acetates with different alkali metals were tested, but all of them
could not greatly improve the reaction (Table 1, entries 7-9). It is
80 worth noting that addition of AgSbF6 even totally retarded the
cross-coupling, indicating that acetate is crucial for the
Butadiene derivatives are valuable building blocks in synthetic
organic chemistry and represent key structural motifs in naturally
occurring products as well as in various bioactive molecules.7
45 From the viewpoint of atom and step economy, direct cross-
College of Materials, Chemistry and Chemical Engineering, Hangzhou
Normal University, Hangzhou 310036, China.
E-mail: zhangjian@hznu.edu.cn ; zgf@hznu.edu.cn
† Electronic Supplementary Information (ESI) available: Detailed
experimental procedures analytical data. See DOI: 10.1039/b000000x
This journal is © The Royal Society of Chemistry [year]
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ruthenium-based cyclometalation and the regeneration of the
The scope of the different alkenes as coupling partners was
catalyst (Table 1, entry10).6p,11 Subsequently, we turned to
examine sterically hindered carboxylate additives including
also investigated (Table 2). Various acrylates, such as methyl
View Article Online
acrylate, ethyl acrylate, tert-butyl acrylate, hexyl acrylate, and
KO2CMes and KOPiv.11d To our delight, both of the carboxylates 45 phenyl acrylate were all efficiently reacted with acrylamide 1a to
DOI: 10.1039/C6CC07064G
5
gave better yields. If KOPiv was employed, the product yield
increased to 82% with 99/1 Z/E ratio (Table 1, entries 11 and 12).
The Z-configuration of product 3a was determined by a NOESY
NMR spectrum experiment, indicating a directed vinylic C-H
produce the corresponding butadienes in good yields with
excellent stereo-selectivities (Table 2, 3o-t). Intriguingly,
acrylamide 1a also reacted with 2,2,2-trifluoroethyl acrylate to
give the cross-coupling product 3t in 45% yield without a
bond functionalization event.6,10 Changing the amount of additive 50 decrease in Z/E ratio selectivity. Although electron-rich alkenes
10 or reaction temperature led to decreased yields. Moreover, the
reaction provided no product in the absence of [Ru(p-
cymene)Cl2]2 (see the SI for details).
and styrene are inactive in such cross-coupling reactions,13 other
electron-deficient alkenes,14 such as α,β-unsaturated ketone,
2,3,4,5,6-penta-fluorostyrene and vinyl phosphonate, all reacted
well and gave the corresponding butadiene products in moderate
55 to good yields with excellent Z/E stereo-selectivity (Table 2, 3u-
w).
Table 1 Optimization of catalytic conditionsa
Table 2 Substrate scopea
O
R1
O
NH2
[Ru(p-cymene)Cl2]2
R1
R2
OMe
15
KOPiv
R2
N
H
+
CO2Bu
Yield (%)b
Z/Ec
99/1
99/1
93/7
-
DMF, 60 oC
Entry
Additive
NaOAc
NaOAc
NaOAc
NaOAc
NaOAc
NaOAc
CsOAc
LiOAc
Solvent
DCE
CO2Bu
2a
19
49
37
0
1
3
1
2
O
O
DMF
O
O
NH2
NH2
5
NH2
NH2
CH3CN
THF
3
4
CO2Bu
CO2Bu
CO2Bu
CO2Bu
3b, 59%
3c, 48%
3d, 67%
3a, 82%
DMSO
t-AmOH
DMF
0
-
5
Z/E = 99/1
Z/E > 99/1
Z/E > 99/1
Z/E = 99/1
20
32
58
55
0
99/1
99/1
94/6
99/1
-
6
O
3e, 38%, Z/E = 98/2b
R
R = H,
O
R = OMe, 3f, 49%, Z/E = 97/3b
7
NH2
, 26%, Z/E = 97/3b
NH2
3g
R = F,
R = Me, 3h, 49%, Z/E > 99/1b
R = CF3, 3i, 22%, Z/E = 92/8b
R = t-Bu, 3j, 48%, Z/E > 99/1b
DMF
8
CO2Bu
3k, 43%
KOAc
DMF
9
CO2Bu
Z/E = 96/4b
AgSbF6
KO2CMes
KOPiv
DMF
10
11
12
O
O
O
DMF
63
99/1
NH2
NH2
NH2
DMF
82
99/1
CO2Bu
CO2Bu
3n, 15%
a Unless otherwise noted, the reactions were carried out using acrylamide
(1a) (0.20 mmol), acrylate 2a (0.36 mmol), [Ru(p-cymene)Cl2]2 (5.0
mol%), additive (30 mol%) in a solvent (0.2 M, 1.0 mL) at 60 °C for 16 h
under an argon atmosphere (1 atm). b The yields indicated in the table are
CO2Bu
3m, 33%
Z/E > 99/1
3l, 20%
Z/E = 97/3
Z/E =98/2
O
O
3o, R = Me,
3p, R = Et,
3q, R = t-Bu,
3r, R = Hex,
3s, R = Ph,
66%, Z/E = 99/1
74%, Z/E = 99/1
57%, Z/E = 99/1
60%, Z/E = 98/2
70%, Z/E = 99/1
c
1
20 isolated yields. Z/E ratios were determined by H NMR. DCE = 1,2-
dichloroethane; DMSO = dimethyl sulphoxide; DMF = N,N-dimethyl
formamide.
NH2
NH2
OR
3t, R = CH2CF3, 45%, Z/E > 99/1
O
O
O
F
With the optimized reaction conditions in hand, we next
examined the scope and limitation of differently substituted N-
25 methoxyacrylamide (1) by employing butyl acrylate (2a) as
coupling partner (Table 2). Subjecting acrylamide (1) tethering a
hexyl, decyl or 2-phenylethyl substituent at the α-position of
acrylamide to acrylate 2a delivered the corresponding 1,3-
butadiene in moderate to good yields with excellent Z/E
30 stereoselectivity. However, introduction of aromatic rings to the
α-position of acrylamide (1) decreased the product yields
3u, 49%
Z/E > 99/1
O
NH2
NH2
F
F
OEt
P
F
O
EtO
F
3v, 41%
Z/E > 99/1
3w, 60%
Z/E = 97/3
60 a Unless otherwise noted, the reactions were carried out using amide 1
(0.2 mmol), acrylate 2a (0.36 mmol), [Ru(p-cymene)Cl2]2 (5.0 mol%),
KOPiv (30 mol%) in DMF (1.0 mL) at 60 °C for 16 h under an argon
atmosphere (1 atm). The yields indicated in the table are isolated yields;
Z/E ratios were determined by 1H NMR. b The reaction was performed at
65 80 °C.
o
remarkably even at elevated temperature (80 C) due to low
conversion, and obvious electronic effect was observed, showing
that electron-donating groups accelerated the reaction while
35 electron-withdrawing groups gave opposite results (Table 2, 3e-j).
Moreover, this catalytic protocol is not only limited to α-
monosubstituted acrylamide but also is applicable to α,β-
disubstituted acrylamide derivatives (3l and 3m), albeit with
decreased yields. Other β-substituted acrylamide, as exemplified
40 with N-methoxy-2-butenamide, was also investigated, but only
15% yield was obtained (3n).12
The versatility of the reaction is also exemplified by the
tolerance of varied O-substituents (Scheme 2). N-Ethoxy-2-
methyl-2-propenamide (1u) reacted well with acrylate. However,
70 installation of more bulky groups, such as Bn (1v) and
tetrahydropyrane (1w), to oxygen atom led to decreased yields.
Moreover, methacrylamide (1x) and N-methyl methacrylamide
2
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(1y) without N-methoxy group were also tested as precursors, but 35 by pivalic acid releases the desired product 3 while at the same
neither of them afforded desired butadiene product. Furthermore,
time regenerating the active ruthenium(II) biscarboxylate catalyst
View Article Online
Weinreb amide 1z did not show any reactivity, exhibiting a Ru-N
I to facilitate the next catalytic cycle (Scheme 4).
bond based five-membered ruthenacycle intermediate.6
DOI: 10.1039/C6CC07064G
O
O
NH2
R
Standard Cond.
N
2a
+
H
COOBu
1a, R = OMe, 82%, Z/E = 99/1
1u, R = OEt, 64%, Z/E = 99/1
1v, R = OBn, 37%, Z/E = 97/3
O
1w, R =
32%, Z/E = 98/2
O
1x, R = H, not detected
O
Me
Standard Cond.
Standard Cond.
N
Not detected
2a
+
+
H
1y
O
OMe
N
No reaction
2a
Me
1z
5
40
Scheme 4 Proposed mechanism.
Scheme 2 Variation of the differently N- and/or O-substituted
acrylamides.
Conclusions
Moreover, if diphenyl acetylene 4 was subjected to acrylamide
In conclusion, we have developed an inexpensive ruthenium-
catalyzed direct cross-coupling reaction of electron-deficient
alkenes. With the assistance of the oxidizing directing group, this
10 1a under the optimal conditions, a valuable pyridone 5 via
cyclization was obtained in 21% yield without the formation of
desired 1,3-butadiene (eq 3).6d,p,q
45 protocol provides a mild, oxidant-free, straightforward method
for the preparation of valuable 1,3-dienamide with excellent Z,E
selectivities.
Acknowledgement
We gratefully acknowledge National Natural Science
50 Foundation of China (NSFC) (21502037 and 21373073), Natural
Science Foundation of Zhejiang Province (ZJNSF)
(LY15B020008), the PCSIRT (IRT 1231) and Hangzhou Normal
University for financial support. G. Z. acknowledges a Qianjiang
Scholar award from Zhejiang Province, China.
15 Finally, we pursued some mechanistic studies of the catalytic
process. Exposure of acrylamide 1e to optimal conditions without
acrylate in the presence of deuterated water led to an exclusively
Z-selective vinyl H/D exchange, suggesting
a reversible
cyclometalation event (Scheme 3, eq 4).6,10 Moreover, a KIE
20 value of 7.3 reveals that the vinylic C-H bond cleavage might be
involved in the rate-determining step (Scheme 3, eq 5).6r,10e-f
55 Notes and references
1
For reviews on C-H bond functionalizations, see: (a) K. M. Engle,
T.-S. Mei, M. Wasa and J.-Q. Yu, Acc. Chem. Res., 2012, 45, 788;
(b) S. R. Neufeldt and M. S. Sanford, Acc. Chem. Res., 2012, 45,
936; (c) G. Song, F. Wang and X. Li, Chem. Soc. Rev., 2012, 41,
3651; (d) J. Wencel-Delord, T. Dröge, F. Liu and F. Glorius, Chem.
Soc. Rev., 2011, 40, 4740; (e) C. S. Yeung and V. M. Dong, Chem.
Rev., 2011, 111, 1215; (f) J. F. Hartwig, Chem. Soc. Rev., 2011, 40,
1992; (g) L. Ackermann, Chem. Rev., 2011, 111, 1314; (h) D. A.
Colby, R. G. Bergman and J. A. Ellman, Chem. Rev., 2010, 110,
624; (i) T. W. Lyons and M. S. Sanford, Chem. Rev., 2010, 110,
1147; (j) M. C. Willis, Chem. Rev., 2010, 110, 725.
60
65
Scheme 3 Isotopic labeling experiments.
2
(a) M. Zhang, Y. Zhang, X. Jie, H. Zhao, G. Li and W. Su, Org.
Chem. Front., 2014, 1, 843; (b) Z. Chen, B. Wang, J. Zhang, W. Yu,
Z. Liu and Y. Zhang, Org. Chem. Front., 2015, 2, 1107.
A. Bechtoldt, C. Tirler, K. Raghuvanshi, S. Warratz, C. Kornhaaß
and L. Ackermann, Angew. Chem. Int. Ed., 2016, 55, 264.
R. Manikandan, P. Madasamy and M. Jeganmohan, ACS Catal.,
2016, 6, 230.
(a) F. W. Patureau and F. Glorius, Angew. Chem. Int. Ed., 2011, 50,
1977; (b) Y. Chen, D. Wang, P. Duan, R. Ben, L. Dai, X. Shao, M.
Hong, J. Zhao and Y. Huang, Nat. Commun., 2014, 5, 4610; (c) H.
Zhang, K. Wang, B. Wang, H. Yi, F. Hu, C. Li, Y. Zhang and J.
25
On the basis of the above results and previous reports,6 we
propose that the reaction proceeds via reversible C-H bond
activation process, yielding a five-membered ruthenacycle II,
with concomitant liberation of pivalic acid. Then, the alkene 2
30 inserts into the Ru-C bond to form seven-membered ruthenacycle
intermediate III. Subsequently, β-H elimination followed by
reductive elimination furnishes ruthenium(0) intermediate. Next,
insertion of ruthenium(0) to N-O bond takes place to afford
ruthenium(II) amide intermediate IV. Finally, protonation of IV
70 3
4
5
75
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Wang, Angew. Chem. Int. Ed., 2014, 53, 13234; (d) S. Yu, S. Liu, Y.
and 3n. Moreover, N-O bond cleavage also occurred in the
Lan, B. Wan and X. Li, J. Am. Chem. Soc., 2015, 137, 1623.
(a) J. Wu, X. Cui, L. Chen, G. Jiang and Y. Wu, J. Am. Chem. Soc.,
2009, 131, 13888; (b) Y. Tan and J. F. Hartwig, J. Am. Chem.Soc.,
2010, 132, 3676; (c) K.-H. Ng, A. S. C. Chan and W.-Y. Yu, J. Am.
Chem. Soc., 2010, 132, 12862; (d) N. Guimond, C. Gouliaras and K.
Fagnou, J. Am. Chem. Soc., 2010, 132, 6908; (e) N. Guimond, S. I.
Gorelsky and K. Fagnou, J. Am. Chem. Soc., 2011, 133, 6449; (f) S.
Rakshit, C. Grohmann, T. Besset and F. Glorius, J. Am. Chem. Soc.,
2011, 133, 2350; (g) J. R. Huckins, E. A. Bercot, O. R. Thiel, T.-L.
Hwang and M. M. Bio, J. Am. Chem. Soc., 2013, 135, 14492; (h) D.
Zhao, Z. Shi and F. Glorius, Angew. Chem. Int. Ed., 2013, 52,
12426; (i) C. Wang and Y. Huang, Org. Lett., 2013, 15, 5294; (j) B.
Liu, C. Song, C. Sun, S. Zhou and J. Zhu, J. Am. Chem. Soc., 2013,
135, 16625; (k) X. Huang, J. Huang, C. Du, X. Zhang, F. Song and J.
You, Angew. Chem., Int. Ed., 2013, 52, 12970; (l) Y. Fukui, P. Liu,
Q. Liu, Z.-T. He, N.-Y. Wu, P. Tian and G.-Q. Lin, J. Am. Chem.
Soc., 2014, 136, 15607; (m) U. Sharma, Y. Park and S. Chang, J.
Org. Chem., 2014, 79, 9899; (n) W.-J. Chen and Z. Lin,
Organometallics, 2015, 34, 309; (o) G. Liu, Y. Shen, Z. Zhou and X.
Lu, Angew. Chem., Int. Ed., 2013, 52, 6033; (p) B. Li, H. Feng, S.
Xu and B. Wang, Chem.-Eur. J., 2011, 17, 12573; (q) L.
Ackermann and S. Fenner, Org. Lett., 2011, 13, 6548; (r) B. Li, J.
Ma, N. Wang, H. Feng, S. Xu and B. Wang, Org. Lett., 2012, 14,
736; (s) J. Mo, L. Wang, Y. Liu and X. Cui, Synthesis, 2015, 47,
439; (t) H. Huang, X. Ji, W. Wu and H. Jiang, Chem. Soc. Rev.,
2015, 44, 1155; (u) F. Yang and L. Ackermann, J. Org. Chem.,
2014, 79, 12070.
(a) F. Fringuelli and A. Taticchi, Dienes in the Diels-Alder Reaction,
Wiley-Interscience, New York, 1990; (b) T. Y. Luh and K. T. Wong,
Synthesis, 1993, 349; (c) G. Mehta and H. S. P. Rao, The Chemistry
of Dienes and Polyenes, ed. Z. Rappoport, Wiley, New York, 1997,
vol. 1, pp. 359-480.
Pd-catalyzed oxidative cross-coupling of linear alkenes with
terminal alkenes: (a) Y. H. Xu, J. Lu and T. P. Loh, J. Am. Chem.
Soc., 2009, 131, 1372; (b) Z. K. Wen, Y. H. Xu and T. P. Loh,
Chem.-Eur. J., 2012, 18, 13284; (c) Z.-K. Wen, Y.-H. Xu and T.-P.
Loh, Chem. Sci., 2013, 4, 4520; (d) H. Yu, W. Jin, C. Sun, J. Chen,
W. Du, S. He and Z. Yu, Angew. Chem., Int. Ed., 2010, 49, 5792; (e)
Y. X. Zhang, Z. J. Cui, Z. J. Li and Z. Q. Liu, Org. Lett., 2012, 14,
1838; (f) X. Shang and Z.-Q. Liu, Chem. Soc. Rev., 2013, 42, 3253;
(g) Y. Hatamoto, S. Sakaguchi and Y. Ishii, Org. Lett., 2004, 6,
4623.
examples of 1f, 1g, 1h, 1i,1j and 1k, leading to primary acrylamides
6
as side products which could not react as cross-coupling precursors.
View Article Online
DOI: 10.1039/C6CC07064G
Increased catalyst concentration (10 mol%) still did not improve the
reaction yield.
75
5
10
15
20
25
30
35
40
45
50
55
60
13 Styrene derivatives and electron-rich alkenes were proved to be
inactive and no diene or dihydropyridone product was formed (ref.
6f, 6p-q).
80 14 Branched and linear acrylates, such as methyl methacrylate and
methyl crotonate, led to trace amount of product.
85
7
8
9
Pd-catalyzed oxidative cross-coupling of cyclic alkenes with
terminal alkenes: (a) K. Hirota, Y. Isobe, Y. Kitade and Y. Maki,
Synthesis, 1987, 495. (b) D. Cheng and T. Gallagher, Org. Lett.,
2009, 11, 2639; (c) Y. Bai, J. Zeng, S. Cai and X.-W. Liu, Org. Lett.,
2011, 13, 4394; (d) D. Kim and S. Hong, Org. Lett., 2011, 13, 4466.
(e) Y. Y. Yu, M. J. Niphakis and G. I. Georg, Org. Lett., 2011, 13,
5932; (f) N. Gigant and I. Gillaizeau, Org. Lett., 2012, 14, 3304; (g)
Y. Chen, F. Wang, A. Jia and X. Li, Chem. Sci., 2012, 3, 3231; (h)
Y. Moon, D. Kwon and S. Hong, Angew. Chem., Int. Ed., 2012, 51,
11333; (i) M. Min, Y. Kim and S. Hong, Chem. Commun., 2013, 49,
196; (j) M. Z. Li, L. X. Li and H. B. Ge, Adv. Synth. Catal., 2010,
352, 2445.
10 (a) T. Besset, N. Kuhl, F. W. Patureau and F. Glorius, Chem.-Eur. J.,
2011, 17, 7167; (b) M. Boultadakis-Arapinis, M. N. Hopkinson and
F. Glorius, Org. Lett., 2014, 16, 1630; (c) R. Feng, W. Yu, K. Wang,
Z. Liu and Y. Zhang, Adv. Synth. Catal., 2014, 356, 1501; (d) J.
Zhang and T. P. Loh, Chem. Commun., 2012, 48, 11232; (e) X.-H.
Hu, J. Zhang, X.-F. Yang, Y.-H. Xu and T.-P. Loh, J. Am. Chem.
Soc., 2015, 137, 3169; (f) X.-H. Hu, X.-F. Yang and T.-P. Loh,
Angew. Chem. Int. Ed., 2015, 54, 15535; (g) Y. H. Xu, Y. K. Chok
and T. P. Loh, Chem. Sci., 2011, 2, 1822.
65 11 (a) L. Ackermann, Chem. Rev., 2011, 111, 1315; (b) J. Li, S. Warratz,
D. Zell, S. D. Sarkar, E. E. Ishikawa and L. Ackermann, J. Am.
Chem. Soc., 2015, 137, 13894; (c) P. B. Arockiam, C. Bruneau and
P. H. Dixneuf, Chem. Rev., 2012, 112, 5879; (d) L. Ackermann and
S. Fenner, Org. Lett., 2011, 13, 6548.
70 12 Generally, the poor or moderate yields are caused by decreased
conversions comparing to 3a, especially in the examples of 3e, 3l
4
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