Pd(0)/C catalyzed efficient Wacker oxidation of functionalized terminal olefins

Article abstract of DOI:10.1016/j.tetlet.2009.03.173

Wacker oxidation of terminal olefins was carried out at room temperature and atmospheric pressure by using Pd(0)/C in THF/H₂O (9:1). Palladium(0)/C was proven to be highly efficient catalyst for the Wacker oxidation of terminal olefins to the corresponding methyl ketones. The catalyst was reusable while maintaining its activity and selectivity to a high degree.

Full text of DOI:10.1016/j.tetlet.2009.03.173

Tetrahedron Letters 50 (2009) 2893–2894
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Tetrahedron Letters
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Pd(0)/C catalyzed efficient Wacker oxidation of functionalized terminal olefins
*
Mukund G. Kulkarni , Sharanappa M. Bagale, Mahadev P. Shinde, Dnyaneshwar D. Gaikwad,
Ajit S. Borhade, Attrimuni P. Dhondge, Sanjay W. Chavhan, Yunnus B. Shaikh, Vijay B. Ningdale,
*
Mayur P. Desai, Deekshaputra R. Birhade
Department of Chemistry, University of Pune, Ganeshkhind, Pune 411 007, Maharashtra, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Wacker oxidation of terminal olefins was carried out at room temperature and atmospheric pressure by
using Pd(0)/C in THF/H2O (9:1). Palladium(0)/C was proven to be highly efficient catalyst for the Wacker
oxidation of terminal olefins to the corresponding methyl ketones. The catalyst was reusable while main-
taining its activity and selectivity to a high degree.
Received 3 January 2009
Revised 24 March 2009
Accepted 26 March 2009
Available online 29 March 2009
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
at room temperature, was found to give methyl ketone in good yield.
To test the generality of this method terminal olefins 1b–l were sub-
Palladium catalyzed reactions such as Wacker oxidation, Heck
reaction, Suzuki coupling reaction etc. have gained a lot of impor-
tance and popularity in the area of synthetic for organic chemistry
over a period of time for its simplicity of operations in the prepara-
tion of useful synthetic intermediates. This is evident from the volu-
minous literature present in connection with these reactions. In all
these reactions namely, Heck reaction1,2, Suzuki reaction3,4, and
Sonogashira coupling reaction5,6 palladium can be used as a catalyst
either in the form of Pd(0)7,10,11,3,13 or Pd(I/II) species.8–10,12 How-
ever, in case of all of the Wacker oxidations14,15 carried out so far,
Pd was used in the form of Pd(II) ion. Palladium has never been used
in the form of Pd(0) for any Wacker oxidation as there are no reports
in the literature16,17 to this effect.
Further, conventional Wacker oxidation using homogeneous
Pd(II) catalysts often leads to difficulties in isolation of the prod-
ucts, separation of the catalysts from the reaction mixture, and
the difficulty about recycling the catalysts. Therefore, much effort
has been devoted to the development of highly efficient Wacker
oxidation by heterogeneous catalysts.18,19 But these catalyst sys-
tems often have drawbacks such as low catalytic activity, low yield
of product and severe dependence of success of the reaction on the
substrate structure. We herein report the use of Pd(0) to effect
Wacker oxidation of the terminal olefins.
jected to Wacker oxidation under the above reaction conditions (Ta-
ble 1). The results show that a variety of terminal olefins can be
converted to methyl ketones quite efficiently in good yields.
2. General procedure for Wacker oxidation
To the solution of substituted, functionalized olefin (1 mmol), in
aqueous THF (1:9, 10 ml), 10%Pd/C (0.1 mmol) and CuCl2
(0.1 mmol) were added. This mixture was stirred and heated at
reflux temperature under oxygen atmosphere. After the comple-
tion of reaction (TLC check), the reaction mixture was diluted with
water and filtered through Whatman 40 filter paper. The greenish
filtrate was extracted with ether. The combined ether layer was
washed with water, dried over anhydrous sodium sulphate and
concentrated under reduced pressure. The crude product was
purified by column chromatography using appropriate solvent
system.
It was further noticed that the recovered catalyst, after drying in
the oven at 100 °C, could be reused as such, along with a fresh
amount of CuCl2, to carry out the Wacker oxidation of the new
batch of the olefin. It was found that the reaction proceeds
smoothly giving the same yield. So it is clear that the catalyst
can be recycled without any problem. This finding makes present
protocol of converting, terminal olefins into methyl ketone, a
Initially, the terminal olefin 1a was heated with Pd(0)/C–Cu(0)/C
catalyst20 under the oxygen atmosphere. Unfortunately, no forma-
tion of methyl ketone was observed under these conditions even at
elevated temperatures. To circumvent this problem, the olefin 1a
was treated with commercially available 10% Pd(0)/C and catalytic
amountof CuCl2 underoxygenatmosphere(Scheme1). Thereaction,
10% Pd(0)/C
R
CuCl2
R
O
1a - l
2a - l
* Corresponding authors. Tel./fax: +91 020 2569 1728 (M.G.K.).
E-mail address: mgkulkarni@chem.unipune.ernet.in (M.G. Kulkarni).
Scheme 1.
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.03.173

2894
M. G. Kulkarni et al. / Tetrahedron Letters 50 (2009) 2893–2894
Table 1
practical and cheap method with the potential application for
large-scale preparation of methyl ketones.
Carbonyl compounds obtained by oxidation of terminal olefins as depicted in Scheme
1
From the above successful results it is clear that this type of
Wacker oxidation carried out by using Pd(0) proved to be an effi-
cient method for the preparation of methyl ketone from terminal
olefin. Further, the yield of the products and the reusability of
the catalyst while maintaining high activity and selectivity could
facilitate the application of Wacker oxidation of terminal olefins,
mediated by 10% Pd(0)/C, to multi-gram scale reactions and possi-
bly in the industrial applications.
R
% Yield
O
a
b
c
d
e
f
78
MeO
OMe
H
O
O
Acknowledgments
80
74
72
65
68
71
57a
73
67
The author S.M.B. thanks the University of Pune for providing
financial support. M.P.S., D.D.G., A.S.B., A.P.D., S.W.C., Y.B.S.,
V.B.N., M.P.D., D.R.B. thank CSIR for fellowship.
Cl
H
Supplementary data
NO2
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tetlet.2009.03.173.
References and notes
MeO
OMe
1. Heck, R. F. J.Am. Chem. Soc. 1968, 90, 5518.
2. Kobetic, R.; Biliskov, N. Kem. Ind. 2007, 56, 391–402.
3. Miyaura, N.; Suzuki, A. Chem. Commun. 1979, 866.
4. Dembitsky, V. M.; Abu, A. H.; Srebnik, M. Studies Inorg. Chem. 2005, 22, 119–
297.
5. Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett. 1975, 16, 4467–4470.
6. Campbell, B. Organocopper Reagents 1994, 217–235.
7. Heck, R. F.; Nolley, J. P. J. Org. Chem. 1972, 37, 2320–2322.
8. Mizoroki, T.; Mori, K.; Ozaki, A. Bull. Chem. Soc. Jap. 1971, 44, 581.
9. Miyaura, N. Tetrahedron Lett. 1979, 3437.
10. Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457–2483.
11. Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett. 1975, 16.
12. Chinchilla, R.; Nájera, C. Chem. Rev. 2007, 107, 874–922.
13. Andrew, G. M.; Peter, S. D. Org. Synth. 1998, 9, 117.
14. Phillips, F. C. Z. Anorg. Chem. 1894, 6, 213–228.
15. Jack, L. J. J. Am. Chem. Soc. 2007, 309–326.
16. Addition of alcohols across the olefin of tetrafluoroethylene has been
reported.17 However this, strictly speaking, cannot be described as a Wacker-
process.
O
O
O
O2N
O
NO2
O
g
h
i
17. Matsukawa, Y.; Mizukado, J.; Quan, H.; Tamura, M.; Sekiya, A. Angew. Chem.,
Int. Ed. 2005, 44, 1128–1130.
18. Zweni, P. P.; Alper, H. Adv. Synth. Catal. 2004, 346, 849.
19. Ansari, I. A.; Joyasawal, S.; Gupta, M. K.; Yadav, J. S.; Gree, R. Tetrahedron Lett.
2005, 46, 7507.
OBn
O
20. Catalyst was prepared by co-reducing PdCl2 and CuCl2 with sodium
borohydride in presence of charcoal.
O
O
O
j
O
k
l
C6H13
C14H27CH(OH)CH2–
–
73
69
a
Corresponding aldehyde was also obtained in 28% yield.