Pd-catalyzed oxidative olefination of arenes with olefins via C-H activation: Retention of the leaving group

Article abstract of DOI:10.1134/S1070427215012023X

Pd-catalyzed direct oxidative olefination of arenes with olefins via C-H activation is described in the absence of any chelating directing groups. For Pd-catalyzed oxidative coupling between arenes and allyl acetate, it was observed the retention of the leaving group.

Full text of DOI:10.1134/S1070427215012023X

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 12, pp. 2050−2055. © Pleiades Publishing, Ltd., 2015.
VARIOUS TECHNOLOGICAL
PROCESSES
Pd-Catalyzed Oxidative Olefination of Arenes
with Olefins via C–H Activation: Retention
of the Leaving Group1
Jincheng Mao*, Xiaojiang Yang, Dingli Wang, and Yang Zhang
State Key Laboratory of Oil and Gas Reservoir, Geology, and Exploitation, Southwest Petroleum University,
Chengdu, 610500, P. R. China
*e-mail: jcmao@swpu.edu.cn
Received November 26, 2015
Abstract—Pd-catalyzed direct oxidative olefination of arenes with olefins via C–H activation is described in the
absence of any chelating directing groups. For Pd-catalyzed oxidative coupling between arenes and allyl acetate,
it was observed the retention of the leaving group.
DOI: 10.1134/S1070427215012023X
INTRODUCTION
Only a few non-chelate assisted cases have been reported
[9–12], and these are limited to activiated C–H positions
of some specific heterocylic structures. Although the
direct oxidative coupling reaction between benzene and
alkenes catalyzed by Pd complexes has been reported, this
catalytic system was limited to a few election-rich arenes
(Scheme 1b) [13–15]. Recently, Feng and Loh have
reported an example of oxidant-free Rh(III)-catalyzed
direct C–H olefination of arenes with allyl acetates
using N,N-disubstituted aminocarbonyl as DG [16]. As
expected, this transformation involves β-elimination,
which was observed in many Pd-catalyzed Heck reactions
[17]. Considering that the resulting substituted allylic
esters could be amenable to further functional-group
transformations, herein we demonstrate a highly efficient
Pd-catalyzed DHR of arenes with allyl actetate by
avoiding β-acetate or β-carbonate elimination under non-
chelate-assisted conditions [18–22]. Furthermore, this
catalytic protocol could be applied for DHR of acrylates
and styrenes as shown in Scheme 1.
Heck–Mizoroki arylation of olefins with aryl halides
and triflates is one of the most popular and most distinct
methods for the construction of vinylarene derivatives
[1, 2]. Although great progress has been made since the
Heck reaction was first discovered, it still suffers from
one major drawback: the production of salt waste [3].
Thus, it could not meet the demands of atom
economical, efficient, environmentally benign synthetic
methods. However, the dehydrogenative Heck reaction
(DHR) could solve this problem, since the arylation of
an olefin proceeds through direct C–H/C–H coupling [4].
Since DHR was first introduced in 1969 by Fujiwara and
Moritani, direct C–H activation and functionalization
have gained much attention by chemists. Mostly, Pd, Ru,
and Rh are found to be efficient catalysts in these C–H
activation processes. However, the use of ortho-directing
groups (DG) is almost always required to improve the
regioselectivity and efficiency of DHR, including imino,
carbonyl, amido, hydroxyl, and 2-subsituted pyridyl
group (Scheme 1a) [5–8]. This restriction has greatly
limited the structural diversity of the products and
subsequent application to complex molecule synthesis,
since the directing group will become part of the product.
In the course of our study on the oxidative coupling
of arenes with alkenes, we found an effective catalytic
system for the direct oxidative coupling of arenes that
contained no directing groups with acrylates. In this
system, PdCl2(PCy3)2 and Cu(OAc)2·H2O were used as
the catalysts, Ag2O was used as oxidant, and LiCl was
used as an additive.
1 The text was submitted by the authors in English.
2050

Pd-CATALYZED OXIDATIVE OLEFINATION
2051
Scheme 1. Transition metal catalyzed oxidative olefination.
DG
DG
Transition metal
Transition metal
+
R
(a)
(a)
R
R
(R = Ph, acylates)
+
R
(b)
(b)
(R = Ph, acylates)
DG
DG
Transition metal
OAc
+
(c)
(c)
R'
R'
This work
OAc
OAc
R
Transition metal
+
R
(R = Ph, acylates)
EXPERIMENTAL
RESULTS AND DISCUSSION
Firstly, the reaction of p-xylene (1a) with allyl acetate
(2a) was employed to optimize the reaction conditions.
Table 1 shows representative results for the reaction of
1a with 2a. It was found that the reaction of 1a with
All manipulations were carried out under air atmos-
phere. Terminal olefins and alkenes were purchased from
Acros Organics and used without further purification.
Palladium and copper catalysts were purchased from
Adamas corporation. Column chromatography was
generally performed on silica gel (300–400 mesh) and
reactions were monitored by thin layer chromatography
(TLC) using UV light to visualize the course of the reac-
tions. The 1H (400 MHz) and 13C NMR (100 MHz) data
were recorded on Varian 400 M spectrometers using
CDCl3 as solvent. The chemical shifts (δ) are reported in
ppm and coupling constants (J) in Hz. 1H NMR spectra
was recorded with tetramethylsilane (δ = 0.00 ppm) as
internal reference; 13C NMR spectra was recorded with
CDCl3 (δ = 77.00 ppm) as internal reference. MS were
performed by the State-authorized Analytical Center in
Soochow University.
.
2a catalyzed by PdCl2(PCy3)2 and Cu(OAc)2 H2O in the
presence of air and a stoichiomeric amount of Ag2O to
give the desired product in 66% yield (Table 1, entry 1).
It was found that the reaction almost did not take place
without PdCl2(PCy3)2 (Table 1, entry 2). And the small
amount of Cu(OAc)2·H2O is necessary to carry out the
coupling in higher conversion, which indicated that
Cu(OAc)2·H2O is apparently suitable as a co-catalyst in
this system (Table 1, entry 3). An oxidant such as Ag2O
is also indispensable (Table 1, entry 4). Other Pd cata-
lysts, such as PdCl2(PPh3)2, PdCl2(dppf)2, PdCl2 with
phosphine ligands, could be employed as catalysts with
lower efficiency (Table 1, entries 5–8). The results in
Table 1 still indicated that Ag2O is the most powerful
among the tested oxidants including Ag2CO3, AgOAc,
and AgNO3 (Table 1, entries 9–11). The amount of
PdCl2(PCy3)2 could be reduced in this catalytic system
(Table 1, entry 12), and higher yield was also obtained.
Addition of LiCl to this system enhanced the reaction
in a certain extent, and the yield was increased to 72%.
General Procedure for Pd-catalyzed oxidative cou-
pling between arene and olefin. A mixture of olefin
(0.3 mmol), arene (2 mL), PdCl2(PCy3)2 (2.5 mol %),
Ag2O (0.3 mmol), Cu(OAc)2·H2O (0.3 mmol), LiCl
(0.6 mmol) in a sealed tube was stirred under an air at-
mosphere at 130°C for 24 h. Then the excessive arene
was removed by reduced distillation and the residue was
directly purified by flash column chromatography (pe-
troleum ether or petroleum ether/ethyl acetate) to afford
the corresponding coupling products.
To extend the present reaction, 2a was allowed to
react with various aryl compounds under the system of
PdCl2(PCy3)2/Cu(OAc)2·H2O/Ag2O/LiCl. The results
are shown in Table 2, and the yields of the products
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 88 No. 12 2015

2052
JINCHENG MAO et al.
Table 1. Optimization of reaction conditions for the coupling of p-xylene with allyl acetatea
Entry
Catalyst
Additive
Oxidant
Ag2O
Yield, %b
66
1
2
PdCl2(PCy3)2/Cu(OAc)2·H2O
Cu(OAc)2·H2O
–
–
Ag2O
Traces
3
4
5
PdCl2(PCy3)2
–
–
–
Ag2O
–
12
Traces
40
PdCl2(PCy3)2/Cu(OAc)2·H2O
PdCl2(PPh3)2/Cu(OAc)2·H2O
Ag2O
6
7c
PdCl2(dppf)2/Cu(OAc)2·H2O
PdCl2/Cu(OAc)2·H2O
–
PCy3
PCy3
–
Ag2O
Ag2O
25
33
17
51
40
19
69
72
8c
Pd (dba)2/Cu(OAc)2·H2O
Ag2O
9
PdCl2(PCy3)2/Cu(OAc)2·H2O
PdCl2(PCy3)2/Cu(OAc)2·H2O
PdCl2(PCy3)2/Cu(OAc)2·H2O
PdCl2(PCy3)2/Cu(OAc)2·H2O
PdCl2(PCy3)2/Cu(OAc)2·H2O
Ag2CO3
AgOAc
AgNO3
Ag2O
10
11
12d
13d,e
–
–
–
LiCl
Ag2O
a Catalytic conditions: Allyl acetate (0.3 mmol), PdCl2(PCy3)2 (5 mol %), Cu(OAc)2·H2O (0.3 mmol), Ag2O (0.3 mmol), p-xylene (2 mL),
130°C, 24 h, air. b Isolated yield based on allyl acetate. c 10 mol% PCy3. d PdCl2(PCy3)2 (2.5 mol %). e 2 equiv. of LiCl.
ranged from 51 to 76%. m-Xylene (1b) with 2a afforded
the isomeric mixture of coupling products 3ba (71%
yield) and the ratio is 3 : 1 (Table 2, entry 2). o-Xylene
coupled with 2a to give a mixture of coupling products
3ca (3.7 : 1) in 63% yield (Table 2, entry 3). The reaction
of toluene (1d), ethylbenzene (1e), propyl benzene (1f),
isopropyl benzene (1g) and tert-butyl benzene (1h)
with 2a afforded the corresponding oxidative coupling
products (3da, 3ea, 3fa, 3ga, and 3ha) in 76, 68, 60,
51, and 52% yields, respectively (Table 2, entries 4–8).
Bulky substituents on the benzene ring led to decreased
yield of the reaction (Table 2, entries 9, 10). However,
the ortho-substituted product gradually was reduced in
ratio, and for the coupling of tert-butyl benzene, the para-
substituted product was exclusively obtained (52% yield,
Table 2, entry 8). It is interesting to find that the reaction
of chlorobenzene (1i), para-chlorobromobenzene (1j) and
di-chlorobenzene (1k) with 2a gave the corresponding
products (3ia, 3ja, 3ka) in good yields. However, when
the substituent group on the benzene ring containing a
carbonyl was employed, the reaction almost does not
occur at all.
For the present reaction, the high regioselectivities
could be explained by the possibility of chelation
between the carbonyl O atom and the Pd atom, which
was described previously [23, 24].
Table 3 summarizes the oxidative coupling of
1a with various alkenes under the same conditions.
1a reacted smoothly with several acrylates to give
the corresponding cinnamates (58–61%) (Table 3,
entries 1, 2). To our surprise, the arylation of acrolein
under these reaction conditions give the double arylated
product 3ad in 34% yield (Table 3, entry 3).
These results inspired us to preform oxidative cou-
pling with some active olefins, such as allyl bromides. As
shown in Scheme 2, the reaction of 1a with allyl bromide
was preformed. It was pleasing to find that only the olefi-
nation product was acquired (28% yield), which is differ-
ent from the traditional C–H arylation reaction [25].
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 88 No. 12 2015

Pd-CATALYZED OXIDATIVE OLEFINATION
2053
Table 2. Screening different additives and nickel sources for nickel-catalyzed Sonogashira reactiona
R1
R1
PdCl (PCy ) ,
LiCl
2
3 2
OAc
OAc
R2
R2
.
Ag2O, Cu(OAc)2 H2O
130°C, 24 h
1
2a
3
a
Reaction conditions: allyl acetate (0.3 mmol), PdCl2(PCy3)2 (2.5 mol %), Ag2O (0.3 mmol), Cu(OAc)2·H2O (0.3mmol), LiCl (0.6 mmol),
arene (2 mL), 130°C, 24 h. All products were trans-isomers. Isolated yield based on allyl acetate.
Scheme 2. Pd-catalyzed oxidative coupling of p-xylene and allyl bromide.
PdCl2(PCy3)2, LiCl
Br
+
Br
Ag2O, Cu(OAc)2.H2O
130°C, 24 h
28%
CONCLUSIONS
reaction was smoothly promoted under air to give the
corresponding coupling products in moderate to good
yields. The reaction works well for both election-
rich and election-deficient arenes in the presence of
relatively low loading Pd catalyst, and readily available
In summary, an efficient catalytic system for the
oxidative coupling of arenes with alkenes through the
aromatic C–H bond activation was developed. The
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 88 No. 12 2015

2054
JINCHENG MAO et al.
Table 3. Optimization of reaction conditions for the coupling of p-xylene with allyl acetatea
Entry
1
Alkenes 2
Product 3
Compd.
Yield, %b
61
O
O
O
O
3ab
O
O
O
O
2
3
3ac
3ad
58
34
O
H
O
H
a
Catalytic conditions: olefin (0.3 mmol), PdCl2(PCy3)2 (2.5 mol %), Ag2O (0.3 mmol), Cu(OAc)2·H2O (0.3 mmol), LiCl (0.6 mmol), p-xylene
(2 mL), 130°C, 24 h. All products were trans-isomers.
b Isolated yield based on allyl acetate.
3. Stephan, M.S.A., Teunissen, J.J.M., Verzijl, G.K.M., and
De Vries, J.G., Angew. Chem., Int. Ed. Engl., 1998, vol. 37,
p. 662.
Cu(OAc)2·H2O as co-catalyst. It is noteworthy that
for the oxidative olefination between arenes and allyl
acetate, the leaving group could be retained in the
products, which could serve as a useful supplement to
the traditional DHR. In the future, we hope to find some
applications in organic synthesis.
4. Le Bras, J. and Muzart, J., Chem. Rev., 2011, vol. 111,
p. 1170.
5. Patureau, F.W. and Glorius, F., J. Am. Chem. Soc., 2010,
vol. 132, p. 9982.
6. Martinez, R., Chevalier, R., Darses, S., and Genet, J.-P.,
ACKNOWLEDGMENTS
Angew. Chem. Int. Ed., 2006, vol. 45, p. 8232.
7. Wang, F., Song, G.-Y., and Li, X.-W., Org. Lett., 2010,
We gratefully acknowledge the grants from Open
Fund (PLN1409) of State Key Laboratory of Oil and
Gas Reservoir Geology and Exploitation (Southwest
Petroleum University) and the Research Grant under the
SA/China Agreement on Cooperation in Science and
Technology.
vol. 12, p. 5430.
8. Ye, M.-C., Gao, G.-L., and Yu, J.-Q., J. Am. Chem. Soc.,
2011, vol. 133, p. 6964.
9. Kubota, A., Emmert, M.H., and Sanford, M.S., Org. Lett.,
2012, vol. 14, p. 1760.
10. Pan, D., Yu, M., Chen, W., and Jiao, N., Chem. Asian J.,
2010, vol. 5, p. 1090.
REFERENCES
11. Pankajakshan, S., Xu, Y.-H., Cheng, J.K., Low, M.T., and
Loh, T.-P., Angew. Chem. Int. Ed., 2012, vol. 51, p. 5701.
1. Beletskaya, I.P. and Cheprakov, A.V., Chem. Rev., 2000,
vol. 100, p. 3009.
12. Harada, S., Yano, H., and Obora, Y., Chem. Cat. Chem,
2013, vol. 5, p. 121.
2. Meijere, A.D. and Meyer, F.E., Angew. Chem. Int. Ed.,
1994, vol. 33, p. 2379.
13. Yokota, T., Tani, M., Sakaguchi, S., and Ishii, Y., J. Am.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 88 No. 12 2015

Pd-CATALYZED OXIDATIVE OLEFINATION
Chem. Soc., 2005, vol. 125, p. 1476. 2005, vol. 127, p. 72.
2055
14. Tani, M., Sakaguchi, S., and Ishii, Y., J. Org. Chem., 2004,
20. Shang, X., Xiong, Y., Zhang, Y., Zhang, L., and Liu, Z.,
vol. 69, p. 1221.
Synlett., 2012, vol. 259.
15. Zheng, L. and Wang, J., Chem. Eur. J., 2012, vol. 18,
21. Li., Z., Zhang, Y., and Liu, Z.-Q., Org. Lett., 2012, vol. 14,
p. 9699.
p. 74.
16. Feng, C., Feng, D., and Loh, T.-P., Org. Lett., 2013, vol. 15,
22. Zhang, Y., Li, Z., and Liu, Z.-Q., Org. Lett., 2012, vol. 14,
p. 3670.
p. 226.
17. Mariamplillai, B., Herse, C., and Lautens, M., Org. Lett.,
23. Kang, S.-K., Lee, H.-W., Jang, S.-B., Kim, T.H., and
2005, vol. 7, p. 4745.
Pyun, S.-J., J. Org. Chem., 1996, vol. 61, p. 2604.
18. Zhang, Q. and Lu, X., J. Am. Chem. Soc., 2000, vol. 122,
24. Beronocchi, E., Cacchi, S., Ciattini, P.G., and Morera
p. 7604.
Ortar, E.G., Tetrahedron Lett., 1992, vol. 33, p. 3073.
19. Lautens, M., Tayama, E., and Herse, C., J. Am. Chem. Soc.,
25. Ichihara, J., Chem. Commun., 1997, p. 1921.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 88 No. 12 2015