Silica-supported antimony(III) chloride as an efficient heterogeneous catalyst for the synthesis of aminopropenones and 3-aminopropenoates under solvent-free conditions

Article abstract of DOI:10.1134/S1070428009010023

A convenient and efficient procedure has been developed for the synthesis of 3-aminoprop-2-en-1-ones and 3-aminoprop-2-enoates catalyzed by silica-supported antimony(III) chloride at room temperature under solvent-free conditions. The reaction takes a sho

Full text of DOI:10.1134/S1070428009010023

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 1, pp. 18–21. © Pleiades Publishing, Ltd., 2009.
Published in Russian in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 1, pp. 25–28.
Silica-Supported Antimony(III) Chloride as an Efficient
Heterogeneous Catalyst for the Synthesis of Aminopropenones
and 3-Aminopropenoates under Solvent-Free Conditions*
Li-Feng Zhanga,b and Shu-Tao Yanga
a The College of Chemistry & Material Science, Hebei Normal University, Shijiazhuang, 050016 China
e-mail: organicchemistry@126.com
b Department of Chemical and Environmental Engineering, Hebei Chemical & Pharmaceutical Vocational Technology
College, Shijiazhuang, 050026 China
Received December 25, 2007
Abstract—A convenient and efficient procedure has been developed for the synthesis of 3-aminoprop-2-en-
1-ones and 3-aminoprop-2-enoates catalyzed by silica-supported antimony(III) chloride at room temperature
under solvent-free conditions. The reaction takes a short time and ensures good to excellent yields of the
products. Both aromatic and aliphatic amines and various 1,3-dicarbonyl compounds, including β-ketoesters
and β-diketones, can be involved.
DOI: 10.1134/S1070428009010023
3-Aminoprop-2-en-1-one derivatives which are also
known as β-enaminones are very useful components of
natural products and versatile precursors for the pre-
paration of pharmaceuticals [1–3]. Because of this
significant position of these compounds, numerous
methods have been reported for the preparation of
β-enaminone derivatives [4–6]. Among these, the reac-
tion of 1,3-dicarbonyl compounds with amines is one
of the simplest and most straightforward approaches.
This method usually requires removal of water as
azeotrope with an aromatic solvent using a Dean–Stark
trap [7]. Recently, some synthetic methods have been
reported, including the use of Lewis acids such as
Zn(ClO4)2 · 6 H2O [8], CeCl3 · 7 H2O [9], NaAuCl4
[10], Bi(OTf)3 [11], CoCl2·6H2O [12], CAN [13, 14],
Yb(OTf)3 [15, 16], SnCl4 ·5 H2O [17], ZrCl4 [18],
ZrOCl2 ·8 H2O [19], CuBr2 [20], Sc(OTf)3 [21], I2
[22], and InBr3 [23], solid acids such as montmorillo-
nite K10 [24], silica chloride [25], silica gel [26],
natural clays [27], HClO4/SiO2 [28], and sulfated
zirconia [29], to improve and modify this reaction.
Occasionally, the reaction can be performed in the ab-
sence of catalysts using ionic liquid [30] or water [31]
as reaction medium or under ultrasound irradiation
[32]. However, some of the reported methods are not
free from such drawbacks as long reaction time, un-
satisfactory yield, harsh reaction conditions, and the
necessity of using excess reagents or catalyst. There-
Scheme 1.
R1
O
O
NH
O
SbCl3/SiO2
R1NH2
+
Me
Me
R2
Me
R2
Ia–Iq
IIa–IIe
IIIa–IIIz
O
Me
Me
O
N
H
N
Me
H
IIIs
For R1 and R2, see table.
* The text was submitted by the authors in English.
18

SILICA-SUPPORTED ANTIMONY(III) CHLORIDE
19
Synthesis of 3-aminoprop-2-en-1-ones and 3-aminoprop-2-
enoates IIIa–IIIz in the presence of SbCl3/SiO2
fore, it is important to develop more convenient meth-
ods for the synthesis of β-enaminone derivatives.
Antimony trichloride has recently attracted atten-
tion due to its accessibility as inexpensive commercial
reagent and easier handling as compared to other metal
halides, e.g., InCl3, GdCl3, and TiCl4 [33]. It was
reported to catalyze various organic transformations,
including conversion of epoxides into β-hydroperoxy
alcohols [34], selective cleavage of trityl [35] and silyl
ethers [36], Knoevenagel condensation [37], synthesis
of 9-aryl-3,4,5,6,7,9-hexahydroxanthene-1,8-diones
[38], pyrano- and furanoquinoline derivatives [33, 39],
dihydropyrimidinones [40], and bis(indolyl)methanes
[41], Michael addition of indoles to α,β-unsaturated
ketones [42], ring opening of epoxides [43], and
Biginelli reaction [44]. The use of silica-supported re-
agents as recoverable and reusable catalysts in organic
synthesis has received considerable attention [45]. In
continuation of our studies on the applications of
Lewis acids as catalysts in the development of new
synthetic methodologies [46, 47], in the present com-
munication we report a novel and efficient solvent-free
procedure for the preparation of 3-aminoprop-2-en-1-
ones and 3-aminoprop-2-enoates using silica-supported
SbCl3 as heterogeneous catalyst (Scheme 1).
Comp.
no.
R1
R2
Time, min Yield, %
IIIa
IIIb
IIIc
IIId
IIIe
IIIf
Bu
Bu
Ph
OEt
OBzl
OEt
OEt
OEt
OEt
OBzl
OEt
OBzl
OMe
OEt
OEt
OEt
OEt
OEt
OEt
Me
20
22
93
92
94
93
90
95
92
95
92
95
93
92
85
72
73
90
93
95
93
91
80
92
93
81
75
80
20
H2C=CHCH2
(R)-PhCH(Me)
PhCH2
18
20
22
IIIg
IIIh
IIIi
PhCH2
25
Ph
60
Ph
60
IIIj
4-MeC6H4
4-EtOC6H4
4-(i-Pr)C6H4
2,4-F2C6H3
2,6-(i-Pr)2C6H3
4-Br-C6H4
2-Furyl
50
IIIk
IIIl
50
55
IIIm
IIIn
IIIo
IIIp
IIIq
IIIr
IIIs
IIIt
1200
3600
3600
60
Bu
15
H2C=CHCH2
Me
15
H2NCH2CH2CH2 Me
15
Initially, a systematic study was carried out to
evaluate the efficiency of this catalyst in a model
reaction of ethyl acetoacetate (10 mmol) with aniline
(10 mmol). The reaction was complete within 1 h in
the presence of 0.5 mmol (5 mol %) of SbCl3/SiO2
under solvent-free condition at room temperature.
Increase in the amount of the catalyst did not enhance
the yield, but the use of smaller amount of the catalyst
led to lower yield and longer reaction time. Only 30%
of the product was obtained even after stirring for 24 h
in the absence of catalyst. The solvent-free procedure
is more advantageous than the use of solvents such as
acetonitrile, ethanol, methylene chloride, ethyl acetate,
or dimethylformamide in terms of the reaction time
and yield. We also found that silica-supported SbCl3
ensured higher yield than did SbCl3 alone.
PhCH2CH2
PhCH(Me)
Ph
Me
Me
Me
Me
Me
Ph
15
IIIu
IIIv
IIIw
IIIx
IIIy
IIIz
18
20
4-MeC6H4
2-EtOC6H4
Ph
20
50
1200
1200
4-EtOC6H4
Ph
prop-2-en-1-ones and 3-aminoprop-2-enoates in high
yields and in short time. Furthermore, the reaction was
highly regioselective, and no by-products were de-
tected. The reactions with 4-bromoaniline (Io) having
an electron-withdrawing group was slower, and the
yield was lower. Prolonged reaction time was neces-
sary to obtain the corresponding product from sterical-
ly hindered 2,6-diisopropylphenylamine (In) in 72%
yield. Optically active (R)-(+)-α-methylbenzylamine
(Ie) was converted into the corresponding β-enamino-
ester (IIIe) without racemization or inversion, which
was confirmed by measuring the optical rotation. Two
equivalents of acetylacetone were used in the reaction
with propane-1,3-diamine (Is), and the product was
bis-enaminone (IIIs). It should be emphasized that
unsymmetrical 1,3-diketones, such as 1-phenylbutane-
Following the developed procedure, a number of
3-aminoprop-2-en-1-ones and 3-aminoprop-2-enoates
were prepared in good to excellent yields (see table).
The results indicated general character of the proposed
method which was efficient for the synthesis of not
only β-diketones but also β-ketoesters. As a rule,
primary aliphatic amines and benzylamines reacted
with a broad range of structurally diverse 1,3-dicarbon-
yl compounds to afford the corresponding 3-amino-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 1 2009

LI-FENG ZHANG, SHU-TAO YANG
20
1,3-dione, reacted with amines to give exclusively the
product in which the double bond was adjacent to the
methyl group (IIIy and IIIz).
pure ethyl 3-phenylaminobut-2-enoate. The catalyst
was repeatedly washed with diethyl ether and reused.
Compounds IIIa [29], IIIc–IIIf [23], IIIh [23], IIIi
[20], IIIj–IIIl [23], IIIn [23], IIIo [13], and IIIq–IIIz
[23] were reported previously; they were identified by
comparing their spectral data with those reported in
the literature. The spectral and analytical data for the
newly synthesized compounds are given below.
We also examined the possibility for recycling the
catalyst in the above model reaction. When the reac-
tion was complete, ethyl acetate was added to the
reaction mixture, the mixture was stirred, and the
catalyst was filtered off, washed with ethyl acetate, and
activated by heating for 2 h at 110°C. The recovered
catalyst was used in another reaction with the same
substrates without significant loss of activity after two
cycles.
Benzyl 3-butylaminobut-2-enoate (IIIb). IR spec-
trum, ν, cm–1: 3238, 3056, 1618, 1581, 1509, 1323,
1
1265, 1135, 1082, 965. H NMR spectrum, δ, ppm:
0.96 t (3H, J = 7.2 Hz), 1.36–1.46 m (2H), 1.50–
1.62 m (2H), 1.90 s (3H), 3.18 q (2H, J = 7.2 Hz),
3.40 s (1H), 5.03 s (2H), 7.23–7.32 m (5H), 8.55 br.s
(1H, NH). Found, %: C 72.62; H 8.75; N 5.88.
C15H21NO2. Calculated, %: C 72.84; H 8.56; N 5.66.
We can conclude that the proposed procedure for
the synthesis of 3-aminoprop-2-en-1-ones and 3-amino-
prop-2-enoates by condensation of 1,3-dicarbonyl
compounds with amines in the presence of silica-sup-
ported antimony(III) chloride under solvent-free condi-
tions is very promising due to its general character,
experimental simplicity, clean reaction, convenient
workup, and the possibility for reusing the catalyst.
Benzyl 3-benzylaminobut-2-enoate (IIIg). IR
spectrum, ν, cm–1: 3275, 3066, 1635, 1608, 1506,
1
1380, 1250, 1170, 1055, 968. H NMR spectrum, δ,
ppm: 1.92 s (3H), 4.40 d (2H, J= 5.2 Hz), 5.06 s (1H),
5.18 s (2H), 7.22–7.42 m (10H), 8.95 br.s (1H). Found,
%: C 76.60; H 7.02; N 5.18. C18H19NO2. Calculated,
%: C 76.84; H 6.81; N 4.98.
EXPERIMENTAL
The IR spectra were recorded on a a Bio-Rad FTS
1
Ethyl 3-(2,4-difluorophenylamino)but-2-enoate
(IIIm). IR spectrum, ν, cm–1: 3258, 3084, 1658, 1622,
1516, 1481, 1261, 1142, 1097, 1058, 1020, 939.
1H NMR spectrum, δ, ppm: 1.28 t (3H, J = 7.2 Hz),
1.88 s (3H), 4.16 q (2H, J = 7.2 Hz), 4.77 s (1H), 6.68–
6.92 m (2H), 7.10–7.18 m (1H), 10.01 br.s (1H, NH).
Found, %: C 56.95; H 5.72; N 6.06. C12H13F2NO2. Cal-
culated, %: C 59.75; H 5.43; N 5.81.
135 spectrometer. The H NMR spectra were recorded
on a Bruker AV 300 spectrometer from solutions in
CDCl3 using TMS as internal standard. The elemental
compositions were determined on a Vario EL III
CHNOS Analyzer.
Silica-supported antimony(III) chloride. Anti-
mony(III) chloride, 2.28 g (10 mmol), was dissolved
in 100 ml of distilled ethanol, 60 g of silica (300–
400 mesh) was added, and the mixture was stirred for
1 h at room temperature. The solvent was removed on
a rotary evaporator, and the residue was heated for 5 h
at 110°C under reduced pressure to obtain SbCl3/SiO2
as a free-flowing powder.
Ethyl 3-(furan-2-ylamino)but-2-enoate (IIIp). IR
spectrum, ν, cm–1: 3382, 2931, 1651, 1614, 1514,
1
1485, 1384, 1263, 1163, 1024, 948. H NMR spec-
trum, δ, ppm: 1.23 t (3H, J = 7.2 Hz), 1.99 s (3H),
4.08 q (2H, J = 7.2 Hz), 4.52 s (1H), 6.19 d.d (1H, J =
3.3, 0.6 Hz), 6.31 d.d (1H, J = 3.3, 1.8 Hz), 7.35 d.d
(1H, J = 1.8, 0.6 Hz), 8.80 br.s (1H, NH). Found, %:
C 61.35; H 6.98; N 6.95. C10H13NO3. Calculated, %:
C 61.53; H 6.71; N 7.18.
Typical procedure for the synthesis of 3-amino-
prop-2-en-1-ones and 3-aminoprop-2-enoates. A mix-
ture of 1.30 g (10 mmol) of ethyl acetoacetate, 0.93 g
(10 mmol) of aniline, and 3.1 g (0.5 mmol) of
SbCl3/SiO2 was stirred at room temperature, the prog-
ress of the reaction being monitored by TLC. When the
reaction was complete, the mixture was treated with
three 10-ml portions of ethyl acetate and stirred, and
the catalyst was filtered off. The combined organic
extracts were washed twice with water, dried over
anhydrous Na2SO4, and concentrated under reduced
pressure, and the residue was purified by column chro-
matography on silica gel using a 20% solution of ethyl
acetate in n-hexane as eluent to isolate 1.95 g (95%) of
Financial support from Hebei Normal University
(L2005Y05) is gratefully acknowledged.
REFERENCES
1. Dannhardt, G., Bauer A., and Nowe, U., J. Prakt. Chem.,
1998, vol. 340, p. 256.
2. Michael, J.P., de Koning, C.B., Gravestock, D., Hos-
ken, G.D., Howard, A.S., Jungmann, C.M., Krause,
R.W.M., Parsons, A.S., Felly S.C., and Stanbury, T.V.,
Pure Appl. Chem., 1999, vol. 71, p. 979.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 1 2009

SILICA-SUPPORTED ANTIMONY(III) CHLORIDE
21
26. Gao, Y.-H., Zhang, Q.-H., and Xu, J.-X., Synth. Com-
mun., 2004, vol. 34, p. 909.
3. Palmieri, G. and Cimarelli, C., Arkivoc, 2006, part (vi),
p. 104.
27. Silva, F.C., De Souza, M.C.B.V., Ferreira, V.F., Sabi-
no, S.J., and Antunes, O.A.C., Catal. Commun., 2004,
vol. 5, p. 151.
4. Ferraz, H.M.C. and Gonçalo, E.R.S., Quim. Nova, 2007,
vol. 30, p. 957.
5. Al-Zaydi, K.M. and Nhari, L.M., Orient. J. Chem.,
28. Das, B., Venkateswarlu, K., Majhi, A., Reddy, M.R.,
Reddy, K.N., Rao, Y.K., Ravikumar, K., and
Sridhar, B., J. Mol. Catal. A: Chem., 2006, vol. 246,
p. 276.
2006, vol. 22, p. 1.
6. Al-Shiekh, M.A., Org. Prep. Proced. Int., 2005, vol. 37,
p. 223.
7. Cone, E.J., Garner, R.H. and Hayes, A.W., J. Org.
Chem., 1972, vol. 37, p. 4436.
29. Zhang, Z.-H., and Song, L.-M., J. Chem. Res., 2005,
p. 817.
8. Bartoli, G., Bosco, M., Locatelli, M., Marcantoni, E.,
30. Bhosale, R.S., Suryawanshi, P.A., Ingle, S.A., Lokhan-
de, M.N., More, S.P., Mane, S.B., Bhosale, S.V., and
Pawar, R.P., Synlett, 2006, p. 933.
Melchiorre, P., and Sambri, L., Synlett, 2004, p. 239.
9. Khodaei, M.M., Khosropour, A.R., and Kookhaza-
deh, M., Synlett, 2004, p. 1980.
31. Stefani, H.A., Costa, I.M., and de O Silva, D., Synthesis,
10. Arcadi, A., Bianchi, G., Di Giuseppe, S., and Marinel-
2000, p. 1526.
li, F., Green Chem., 2003, vol. 5, p. 64.
32. Brandt, C.A., da Silva, A.C.M.P., Pancote, C.G.,
Brito, C.L., and da Silveira, M.A.B., Synthesis, 2004,
p. 1557.
33. Maiti, G. and Kundu, P., Tetrahedron Lett., 2006,
vol. 47, p. 5733.
34. Liu, Y.-H., Zhang, Z.-H., and Li, T.-S., Synthesis, 2008,
11. Khosropour, A.R., Khodaei, M.M., and Kookhaza-
deh, M., Tetrahedron Lett., 2004, vol. 45, p. 1725.
12. Zhang, Z.-H. and Hu, J.-Y, J. Braz. Chem. Soc., 2006,
vol. 17, p. 1447.
13. Mo, L.-P., Liu, S.-F., and Li, W.-Z., J. Chin. Chem.
Soc., 2007, vol. 54, p. 879.
p. 3314.
14. Sridharan, V., Avendaño, C., and Menéndez, J.C.,
35. Wu, Q.-P., Wang, Y., Chen, W., and Liu, H., Synth.
Commun., 2006, vol. 36, p. 1361.
Synlett, 2007, p. 881.
15. Epifano, F., Genovese, S., and Curini, M., Tetrahedron
Lett., 2007, vol. 48, p. 2717.
36. Wu, Q.-P, Wang, Y., Chen, W., Wang, H., and Liu, H.,
Lett. Org. Chem., 2006, vol. 3, p. 13.
16. Varala, R., Nuvula, S., and Adapa, S.R., Aust. J. Chem.,
37. Mitra, A.K., Karchaudhuri, N., and De, A., J. Indian
Chem. Soc., 2005, vol. 82, p. 177.
2006, vol. 59, p. 921.
17. Zhang, Z.-H., Ma, Z.-C., and Mo, L.-P., Indian J.
Chem., Sect. B, 2007, vol. 46, p. 535.
38. Zhang, Z.-H. and Liu, Y.-H., Catal. Commun., 2008,
vol. 9, p. 1715.
18. Lin, J. and Zhang, L.-F, Monatsh. Chem., 2007,
39. Mahajan, D., Ganai, B.A., Sharma, R.L., and Ka-
vol. 138, p. 77.
poor, K.K., Tetrahedron Lett., 2006, vol. 47, p. 7919.
19. Zhang, Z.-H., Li, T.-S., and Li, J.J., Catal. Commun.,
40. Kapoor, K.K., Ganai, B.A., Kumar, S., and An-
2007, vol. 8, p. 1615.
dotra, C.S., Can. J. Chem., 2006, vol. 84, p. 433.
20. Li, G.-C., Monatsh. Chem., 2008, vol. 139, p. 789.
41. Srinivasa, A., Nandeshwarappa, B.P., Kiran, B.M., and
Mahadevan, K.M., Phosphorus, Sulfur, Silicon Relat.
Elem., 2007, vol. 182, p. 2243.
21. Yadav, J.S., Kumar, V.N., Rao, R.S. Priyadarshi-
ni, A.D., Rao, P.P., Reddy, B.V.S., and Nagaiah, K.,
J. Mol. Catal. A: Chem., 2006, vol. 256, p. 234.
42. Maiti, G. and Kundu, P., Synth. Commun., 2007,
vol. 37, p. 2309.
43. Singh, M.C., and Peddinti, R.K., Tetrahedron Lett.,
22. Gogoi, S., Bhuyan, R., and Barua, N.C., Synth. Com-
mun., 2005, vol. 35, p. 2811.
2007, vol. 48, p. 7354.
44. Cepanec, I., Litvić, M., Filipan-Litvić, M., and Grün-
gold, I., Tetrahedron, 2007, vol. 63, p. 11822.
23. Zhang, Z.-H., Yin, L., and Wang, Y.-M., Adv. Synth.
Catal., 2006, vol. 348, p. 184.
24. Braibante, M.E.F., Braibante, H.T.S., Morel, A.F.,
Costa, C.C., and Lima, M.G., J. Braz. Chem. Soc., 2006,
vol. 17, p. 184.
45. Corma, A. and Garcia, H., Adv. Synth. Catal., 2006,
vol. 348, p. 1391.
46. Yang, S.-T., J. Chem. Res., 2006, no. 3, p. 199.
47. Zhang, Z.-H., Yang, S.-T., and Lin, J., Synth. Commun.,
25. Gholap, A.R., Chakor, N.S., Daniel, T., Lahoti, R.J.,
and Srinivasan, K.V., J. Mol. Catal. A: Chem., 2006,
vol. 245, p. 37.
2006, vol. 36, p. 1645.
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