Montmorillonite-palladium-copper catalyzed cross-coupling of methyl acrylate with aryl amines

Article abstract of DOI:10.1016/S0040-4039(99)02082-1

Heck vinylation reactions of different anilines were performed with vinylacetate by using palladium chloride and copper nitrate intercalated montmorillonite K10 clay as catalyst. The substituted methylcinnamates were obtained in good yields without simultaneous side reaction to stilbenes.

Full text of DOI:10.1016/S0040-4039(99)02082-1

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 41 (2000) 317–319
Montmorillonite–palladium–copper catalyzed cross-coupling of
methyl acrylate with aryl amines
Christophe Waterlot,a Daniel Couturier a and Benoît Rigo b,∗
aLaboratoire d’Ingéniérie Moléculaire, Université de Lille, 59655 Villeneuve d’Ascq, France
bLaboratoire d’Ingéniérie Moléculaire, Ecole des Hautes Etudes Industrielles, 13 rue de Toul, 59046 Lille, France
Received 27 September 1999; accepted 29 October 1999
Abstract
Heck vinylation reactions of different anilines were performed with vinylacetate by using palladium chloride and
copper nitrate intercalated montmorillonite K10 clay as catalyst. The substituted methylcinnamates were obtained
in good yields without simultaneous side reaction to stilbenes. © 2000 Elsevier Science Ltd. All rights reserved.
Keywords: arylation; heck reactions; aryl amines; montmorillonite; palladium; copper.
Heck vinylation of substituted aromatics is one of the most frequently studied reactions in organic syn-
thesis. The reaction is generally performed with aryl halides using homogeneous catalysts.1–7 Recently,
several publications have appeared on the development of heterogeneous catalysts8–10 such as modified
montmorillonite K10 clay11,12 in order to perform Heck vinylation in a simple and inexpensive way. By
comparison with palladium diacetate and triphenylphosphine, palladium intercalated montmorillonite
K10 is less expensive for the synthesis of methyl substituted cinnamates from aryl halides (X=r, I).13,14
From an industrial point of view, aryl halides have no considerable commercial interest because of
further reactions leading to stilbenes3,7,11,12 and the expensive cost of catalysts or halides used (X=Br, I).
For these reasons, many studies on the amination of aryl halides15–17 and on the vinylation of substituted
anilines with inexpensive simple salts were realized.18–21 In this framework, two different mechanisms
have been suggested: the first one is a C–N bond cleavage of aryl amines when treated with palladium
salts and acetic acid to give Ar–Pd–N species.18 When the vinylation is performed in the presence of
nitrites,19,21 oxidative addition of aryldiazoniums to palladium occurred, yielding Ar–Pd species.22
To the best of our knowledge, no direct synthesis of methyl cinnamates from anilines by using
Pd–Cu exchanged montmorillonite K10 clay23–25 (Pd–Cu–Mont.K10) as heterogeneous catalyst has been
described. We thus investigate the use of this catalyst for the arylation of methyl acrylate with aryl amines
(Scheme 1) and the influence of tert-butyl nitrite on this reaction. Our results are summarized in Table 1.
By using the modified K10 clay as catalyst, good yields in methyl cinnamates were obtained from
aromatic amines and no stilbenes by-products were formed.27 This vinylation is selective and no side
∗
Corresponding author. E-mail: rigo@hei.fupl.asso.fr (B. Rigo)
0040-4039/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(99)02082-1
tetl 16010

318
Scheme 1.
Table 1
Pd–Cu–Mont.K10 catalyzed synthesis of methyl cinnamates from substituted anilines26
reaction from a halogen (entries 3 and 4) was observed. Interestingly, the addition of an equimolar
amount of tert-butyl nitrite to the heterogeneous catalyst hindered the reaction. Thus, this arylation can
be favorably compared to other modified Heck reactions performed with aromatic amines and simple
palladium catalysts.18
This work allowed us to synthesize a monomer (Table 1, entry 6) in an inexpensive way.28,29
Polymerization of this compound yields electron transfer polymer14 which can be used as a cheap reagent
to remove dissolved oxygen from organic solvents.30
Conclusively, we have described a new variation of Heck reactions giving good yields of cinnamates
starting from anilines, without the formation of by-products.
References
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3. Plevyak, J. E.; Dickerson, J. E.; Heck, R. F. J. Org. Chem. 1979, 44, 4078–4080.

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14. Waterlot, C. PhD Thesis, Université de Lille, France, 1999.
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16. Guari, Y.; Van Es, D. S.; Reck, J. N. H.; Kamer, P. C. J.; Van Leeuwen, P. W. N. M. Tetrahedron Lett. 1999, 40, 3789–3790.
17. Larock, R. C. In Comprehensive Organic Transformations; VCH Publishers: New York, 1989; pp. 399–400.
18. Akiyama, F.; Miyazaki, H.; Kaneda, K.; Teranishi, S. J. Org. Chem. 1980, 45, 2359–2361.
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23. Choudhary, B. M.; Sarma, R. H.; Rao, K. K. Tetrahedron 1992, 48, 719–726.
24. Pd–Cu–Mont.K10 is a palladium and copper exchanged montmorillonite K10 clay. This catalyst was prepared by
exchanging the clay with dilute aqueous palladium chloride (Pd=0.29 wt% of Mont.K10 clay) and copper nitrate (Cu=0.36
wt% of Mont.K10 clay).25
25. Ramchandani, R. K.; Uphade, R. K.; Vinod, M. P.; Wakharkar, R. D.; Choudhary, V. R.; Sudalai, A. Chem. Comm. 1997,
2071–2072.
26. General procedure for the arylation of methyl acrylate (Table 1, entry 6): A solution of methyl acrylate (8.0 g, 93.5 mmol)
in dichloromethane (10 mL) was slowly added to a mixture of 2,5-dimethoxy-1-(40-aminobenzyl)benzene (11.3 g, 46.7
mmol), Pd–Cu–Mont.K10 clay (1.1 g) in acetic acid (50 mL) and dichloromethane (15 mL). The suspension was refluxed
with stirring until the starting material was completely consumed as judged by HPLC analysis. The catalyst was collected29
and the cooled reaction mixture was stirred with 100 mL of water. The aqueous layer was extracted with dichloromethane
(50 mL), and the organic phases were dried over CaCl2 and concentrated under vacuum. The brown solid was recrystallized
from petroleum ether/diethyl ether giving the monomer 2 (10.2 g, 70%) as a white solid, mp 83°C; IR (KBr): 2995, 2835,
1710, 1600, 1500, 1430, 1320, 1230, 1170, 1020 cm−1; 1H NMR (CDCl3): δ 3.72 (s, 3H), 3.76 (s, 3H), 3.79 (s, 3H), 3.95
(s, 2H), 6.38 (d, J=16.1 Hz, 1H), 6.66 (d, J=3.0 Hz, 1H), 6.72 (dd, J=8.8 Hz, J=3.0 Hz, 1H), 6.79 (d, J=8.8 Hz, 1H), 7.22 (d,
J=8.1 Hz, 2H), 7.42 (d, J=8.1 Hz, 2H), 7.66 (d, J=16.1 Hz, 1H); 13C NMR (CDCl3): δ 36.1, 51.7, 55.7, 56.0, 111.5, 116.9,
128.2, 128.4, 130.2, 132.1, 143.7, 144.9, 151.7, 153.6, 167.7; m/z 312 (M+, 100). Anal. calcd for C19H20O4: C, 73.06; H,
6.45. Found: C, 72.92; H, 6.29.
27. At the end of the reaction, only final product and a small amount of polymers are observed in the reaction mixture.
28. Accordingly, the preparation of the catalyst,23,25 only 0.0029 g of Pd were necessary to synthesize methyl cinnamates
starting from 100 g of substituted aryl amines.
29. The catalyst from the reaction mixture was recovered by simple filtration and was successfully reused once without losing its
activity in the vinylation of 2,5-dimethoxy-1-(40-aminobenzyl)benzene (Table 1, entry 6). Ramchandani reused this catalyst
three times in vinylation of aryl iodides.25
30. Waterlot, C.; Couturier, D.; Hasiak, B. J. Polym. Sci. 1999, submitted for publication.