A novel and efficient synthesis of maleic anhydrides by palladium-catalyzed dicarbonylation of terminal acetylenes in H2O/dioxane

Article abstract of DOI:10.1016/S0040-4039(01)01438-1

Maleic anhydrides can be obtained in high yields by the PdCl₂-catalyzed dicarbonylation of terminal acetylenes in H₂O/dioxane. It is not necessary to add reoxidants to the reaction, but reoxidants can affect the yield and the rate. We also found that the rate decreased and only traces of maleic anhydrides were formed in the presence of KCl or LiCl.

Full text of DOI:10.1016/S0040-4039(01)01438-1

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 6923–6924
A novel and efficient synthesis of maleic anhydrides by
palladium-catalyzed dicarbonylation of terminal acetylenes in
H2O/dioxane
Jinheng Li, Guoping Li, Huanfeng Jiang* and Mingcai Chen*
LCLC, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, PO Box 1122, Guangzhou 510650, China
Received 25 April 2001; revised 24 July 2001; accepted 3 August 2001
Abstract—Maleic anhydrides can be obtained in high yields by the PdCl2-catalyzed dicarbonylation of terminal acetylenes in
H2O/dioxane. It is not necessary to add reoxidants to the reaction, but reoxidants can affect the yield and the rate. We also found
that the rate decreased and only traces of maleic anhydrides were formed in the presence of KCl or LiCl. © 2001 Elsevier Science
Ltd. All rights reserved.
In 1999, we showed that (Z)-3-chloroacrylate esters
could be synthesized in the corresponding alcohol/ben-
zene mixture at room temperature under CO (1 atm) in
the presence of PdCl2 and CuCl2 (Scheme 1).1 In this
reaction, the solvent plays an important role in influ-
encing the chemoselectivity and stereoselectivity. We
now report that different kinds of product could be
obtained from the palladium-catalyzed carbonylation
reaction by changing the solvent. This finding is
expected to have a broad impact on studies of Pd(II)-
catalyzed carbonylation reactions leading to new
methodology.
filtration, the dioxane was removed by rotary evapora-
tion to give the crude product that was then purified
using preparative TLC on silica gel (light petroleum–
diethyl ether). Our results are summarized in Tables 1
and 2.
Table 1 reports the results of the palladium-catalyzed
dicarbonylation of phenylacetylene under a variety of
conditions. In MeOH/dioxane, phenylmaleic anhydride
was primarily obtained (80%) in the presence of PdCl2
and CuCl2 (entry 1). This result suggested that the
water in the dioxane competes with the MeOH.2 To
verify these results, two other experiments were carried
out: one in dioxane (AR, containing 0.3% of H2O) and
the other in H2O/dioxane (1/5, 10 mL). Only phenyl-
maleic anhydride was isolated from both reactions
(entries 2 and 3). We also examined different solvents
(entries 1–7). The best solvent was found to be H2O/
dioxane since the excess H2O did not affect the reac-
tion. No maleic anhydride was produced when other
solvents such as H2O, THF, H2O/THF, or H2O/C6H6,
were used.
We report that another catalytic carbonylation reaction
takes place using PdCl2 and CuCl2 as the catalyst
system when dioxane is used as the solvent. Maleic
anhydrides can be obtained in high yields (Scheme 2).
A typical procedure is as follows: alkyne 1 (1 mmol),
PdCl2 (0.056 mmol), and CuCl2 (2 mmol) were added
to dioxane (10 mL containing 0.3% of H2O). The
mixture was stirred under an atmospheric pressure of
CO at room temperature for the required time. After
Scheme 1.
* Corresponding author.
Scheme 2.
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(01)01438-1

6924
J. Li et al. / Tetrahedron Letters 42 (2001) 6923–6924
Table 1. Synthesis of phenylmaleic anhydride by palla-
Less than 10% of maleic anhydride was obtained in the
presence of PdCl2 with 4 mmol of KCl or LiCl (entries
9 and 10).
dium-catalyzed dicarbonylation of phenylacetylenea
A range of terminal acetylenes was evaluated as sub-
strates for the dicarbonylation reaction (Table 2). The
reaction proceeded smoothly and high yields were
obtained when 5 mmol of phenylacetylene was added in
the presence of PdCl2 (0.056 mmol), CuCl2 (10 mmol),
CO (1 atm) and dioxane (AR containing 0.3% of H2O,
50 mL) at room temperature (entry 1 in Table 2). Other
terminal acetylenes were also converted into the corre-
sponding maleic anhydrides smoothly in excellent yields
using PdCl2 and CuCl2 as the catalyst (entries 2–5).
Entry
Catalyst
Solvent (10
mL)
Reaction
time (h)b
Yields (%)c
1d
2
PdCl2/CuCl2 Dioxane
PdCl2/CuCl2 Dioxane
PdCl2/CuCl2 H2O/dioxane
PdCl2/CuCl2 H2O
PdCl2/CuCl2 THF
PdCl2/CuCl2 H2O/THF
PdCl2/CuCl2 H2O/C6H6
PdCl2
PdCl2/KCl
PdCl2/LiCl
2
2
2
15
14
14
14
14
15
15
80
99
98
Trace
–
3e
4
5
6e
7e
8
–
–
It is important to note that the carbonylation reaction
can proceed smoothly in the absence of reoxidant, but
reoxidant (CuCl2) can enhance the yield and rate. Other
reagents such as LiCl and KCl decreased the reaction
rate.
Dioxane
Dioxane
Dioxane
76
Trace
10
9f
10g
a Reaction conditions: 1 (1 mmol), PdCl2 (0.056 mmol), CuCl2 (2
mmol) and dioxane (AR, 10 mL containing 0.3% of H2O).
b The rate of the reaction was determined by GC analysis using an
internal standard.
In summary, we have shown that a reoxidant is not
necessary in the PdCl2-catalyzed dicarbonylation of ter-
minal acetylenes in H2O/dioxane, but it can affect the
yield and the rate of the reaction. We have also devel-
oped a mild, general and efficient method for the
synthesis of maleic anhydrides using PdCl2 and CuCl2
as the catalyst. Further synthetic applications and stud-
ies of the mechanism of the dicarbonylation reaction
are underway.
c Isolated yield.
d Reaction in MeOH/dioxane (10 mL, 0.6/9.4), methyl (Z)-3-
chlorophenylacrylate esters/phenylmaleic anhydride: 15/85.
e The ratio of H2O/solvent=2/10.
f KCl (4 mmol).
g LiCl (4 mmol), conversion 35%.
Table 2. Palladium-catalyzed dicarbonylation of terminal
alkynesa
Acknowledgements
Entry Alkyne
Reaction time (h)b Yields of 2 (%)c
1d
2
3
4
5
PhCꢀCH
9
4
4
2
3
98
94
96
84
87
We thank the National Natural Science Foundation of
China for financial support (Nos. 29772036 and
29872039).
p-C5H11C6H4CꢀCH
p-FC6H4CꢀCH
C5H11CꢀCH
C8H17CꢀCH
References
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