B2O3/Al2O3 as a new, highly efficient and reusable heterogeneous catalyst for the selective synthesis of β-enamino ketones and esters under solvent-free conditions

Article abstract of DOI:10.1590/S0103-50532010000800021

Boron oxide adsorbed on alumina (B₂O₃/Al ₂O₃) has been found to be a new and highly efficient heterogeneous catalyst for the synthesis of β-enamino ketones and esters by the enamination of various primary and secondary amines with β-dicarbonyl compounds under solvent-free conditions. The important features of this methodology are broad substrate scope, high yield, no requirement of metal catalysts, high regio-and chemoselectivity and environmental friendliness. In addition, the catalyst could be recovered easily after the reactions and reused without evident loss of reactivity.

Full text of DOI:10.1590/S0103-50532010000800021

J. Braz. Chem. Soc., Vol. 21, No. 8, 1552-1556, 2010.
Printed in Brazil - ©2010 Sociedade Brasileira de Química
0103 - 5053 $6.00+0.00
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst for the
Selective Synthesis of β-Enamino Ketones and Esters under Solvent-Free Conditions
Jiu-Xi Chen,a Chang-Fu Zhang,b Wen-Xia Gao,a Hui-Le Jin,a Jin-Chang Dinga,b and
Hua-Yue Wu*,a
aCollege of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, 325035, China
bWenzhou Vocational and Technical College, Wenzhou, 325035, China
Óxido de boro adsorvido sobre alumina (B2O3/Al2O3) foi usado como um novo e eficiente
catalisador na síntese de β-aminocetonas e ésteres pela enaminação de diferentes aminas primárias
e secundárias com compostos carbonílicos sob condições livre de solvente. A importância dessa
metodologia congrega grande variedade de substratos, alta eficiência, ausência de catalisador
metálico, alta régio- e quimioseletividade em condições amigáveis ao ambiente.Ainda, o catalisador
pode ser recuperado facilmente depois das reações e reusado sem perda de atividade.
Boron oxide adsorbed on alumina (B2O3/Al2O3) has been found to be a new and highly efficient
heterogeneous catalyst for the synthesis of β-enamino ketones and esters by the enamination of
various primary and secondary amines with β-dicarbonyl compounds under solvent-free conditions.
The important features of this methodology are broad substrate scope, high yield, no requirement
of metal catalysts, high regio- and chemoselectivity and environmental friendliness. In addition, the
catalyst could be recovered easily after the reactions and reused without evident loss of reactivity.
Keywords: β-enamino ketones, β-enamino esters, β-dicarbonyl compounds, amines,
B2O3/Al2O3, solvent-free
Introduction
of convenient, environmental friendliness, high yield and
clean approaches is highly desirable.
β-Enamino carbonylic compounds represent an
important class of functionalized building blocks, which
become increasingly important in medicinal chemistry
and organic synthesis.1 Consequently, various approaches
toward the construction of β-enamino carbonylic
compounds have been explored during the past years.
The direct enamination of 1,3-dicarbonyl compounds
with amines is one of the most straightforward methods
for the synthesis of β-enamino ketones and esters in the
presence of various promoting agents.2-19 Recent reports
have described the preparation of β-enamino ketones
and esters catalyzed by metal triflate.20 Although the
reported methodologies are suitable for certain synthetic
conditions, some of these procedures suffered from
disadvantages, such as long reaction time, low yield,
use of volatile organic solvents, requirement of excess
of reagents or costly catalysts, special apparatus and
harsh reaction conditions. Therefore, the development
Recently, heterogeneous organic reactions21 have
been recently performed with immobilized reagents on
solid supports. These procedures offer several intrinsic
advantages such as clean reactions, the easy separation of
products, the recover and reuse of catalyst conveniently, the
minimization of waste production, and eco-friendliness etc.
As a part of our great interest in developing novel
synthetic routes for the formations of carbon-carbon and
carbon-heteroatom bonds,22 we herein reported B2O3/Al2O3
as a new, efficient and reusable heterogeneous catalyst for
the enamination of β-dicarbonyl compounds with amines.
Results and Discussion
The model reaction of ethyl acetoacetate (1a) with
aniline (2a) was conducted to find the optimal reaction
conditions and the initial results are listed in Table 1.
First, the effect of solvents was tested. Among all the
solvents tested, ethanol afforded better yield than some
other solvents tested. As shown in Table 1, however,
*e-mail: huayuewu@wzu.edu.cn

Vol. 21, No. 8, 2010
Chen et al.
1553
Table 1. The condensation of ethyl acetoacetate with aniline under various different reaction conditionsa
Ph
O
O
NH
O
B2O3/Al2O3
r.t.
+
PhNH2
OEt
OEt
1a
2a
3a
Entry
Solvent
EtOH
CH3CN
CH2Cl2
H2O
time (h)
Yields (%)b
1
2
3
4
5
6
7
8
9
1
1
75
68
1
70
1
65
none
1
95
none
2.5
1
96
none
85c
none
1
95d (22)e
40f
none
5
aAll reactions were run with 1a (1 mmol), 2a (1.1 mmol) and B2O3/Al2O3 (0.03 g, 15% m/m) in 2 mL of solvent at room temperature. bIsolated yields.
d
e
cB2O3/Al2O3 (0.01 g, 15% m/m) was used as a catalyst. B2O3/Al2O3 (0.05 g, 15% m/m) was used as a catalyst. In the absence of catalyst.
fAl2O3 (0.03 g) was used as a catalyst.
the presence of additional solvents lowered the reaction
rate (Table 1, entries 1-4). So we chose to perform this
reaction under solvent-free conditions (Table 1, entry 5).
In contrast, the product 3a was obtained in 22% yield in
the absence of B2O3/Al2O3 (Table 1, entry 8). When only
Al2O3 was used as a catalyst, 3a was obtained in 40%
yield (Table 1, entry 9). On the other hand, it was found
that the yield was affected by adding different amount of
B2O3/Al2O3 (Table 1, entries 5, 7-8). Thus, subsequent
studies were carried out under the following optimized
conditions, that are, 0.03 g B2O3/Al2O3 at room temperature
in the absence of solvent.
equivalents of 1 were required in order to have a complete
conversion of diamines. When aliphatic diamine such as
1,3-propanediamine was examined, the corresponding bis-
enamine products 5a and 5b were obtained in 95 and 99%
yields, respectively. Moreover, when aromatic diamine such
as 1,4-benzenediamine was examined, the corresponding
bis-enamine products 5c and 5d were obtained in 88 and
97% yields, respectively.
However, when more sterically hindered aromatic
diamine such as 1,2-benzenediamine was examined, the
reaction only gave the mono-enamine products 6a and
6b using two equivalents and even three equivalents of
β-dicarbonyl compounds.
On the other hand, we have investigated the efficiency
of this catalyst for a few representative intermolecular
competition studies (Scheme 1). The different reactivity of
aromatic amines and aliphatic amines were demonstrated
during the reaction of β-dicarbonyl compounds such
as ethyl acetoacetate and acetylacetone with equimolar
mixtures of aniline and n-propylamine (selectivity in favour
of n-propylamine).Analysis of the mixture after 2 h showed
that only n-propylamine reacted with ethyl acetoacetate
and acetylacetone.
Finally, the reusability of B2O3/Al2O3 was further
investigated in subsequent reactions, taking the additions
of aniline to ethyl acetoacetate as an example (Scheme 2).
The catalyst was easily recovered by simple filtration
after diluting of the reaction mixture with ethyl acetate
and was reused after being dried under vacuum.
B2O3/Al2O3 was reused for four runs without evident loss
of activity.
With optimal conditions in hand, the reaction of
different β-dicarbonyl compounds 1 with a range of
primary, secondary, and aromatic amines 2 were examined
to explore the scope of the reaction.
As shown inTable 2, a series of aromatic amines bearing
either electron-donating or electron-withdrawing groups
on aromatic ring were investigated. The substituent groups
on the aromatic ring associated with amines did not show
obvious effects in terms of yields under optimal conditions.
It was observed that the corresponding β-enamino ketones
and esters 3 were obtained in good to excellent yields.
Aliphatic amines also reacted efficiently to give products
3m-3p in good yields, and the reaction time was shorter
than that of aromatic amines (Table 2, entries 13-16).
Moreover, secondary amines reacted to afford products 3q-
3s in good yields but with longer reaction times (Table 2,
entries 17-19).
Next, we investigated the reaction of β-dicarbonyl
compounds 1 with diamines 4 (Table 3). In this reaction, two

1554
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Table 2. Synthesis of β-enamino carbonylic compounds catalyzed by B2O3/Al2O3a
R2
R3
O
O
H
N
N
O
B2O3/Al2O3
r.t.
+
R2
R3
R1
R1
1
2
3
Entry
1
R1
R2
R3
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
time
1 h
Product
3a
3b
3c
Yield (%)b
OEt
Me
Ph
Ph
95
87
2
2 h
3
OEt
Me
α-naphtyl
α-naphtyl
4-CH3C6H4
4-CH3C6H4
2-CH3OC6H4
2-CH3OC6H4
3-ClC6H4
3 h
86
4
4 h
3d
3e
90
5
OEt
Me
1.5 h
1.5 h
2 h
88
6
3f
86
7
OEt
Me
3g
3h
3i
85
8
2 h
89
9
OEt
Me
2 h
83
10
11
12
13
14
15
16
17
18
19
3-ClC6H4
2 h
3j
71 (98)c
78 (91)c
73 (86)c
91
OEt
OEt
OEt
Me
4-ClC6H4
1.5 h
2 h
3k
3l
4-BrC6H4
CH3CH2CH2
CH3CH2CH2
PhCH2
20 min
20 min
50 min
50 min
5 h
3m
3n
3o
3p
3q
3r
88
OEt
Me
80
PhCH2
86
Me
CH3CH2
CH3CH2
83
Me
morpholine
morpholine
5 h
83
OEt
5 h
3s
82
a All reactions were run with 1 (1 mmol), 2 (1.1 mmol) and B2O3/Al2O3 (0.03 g, 15% m/m) in the absence of solvent at room temperature. b Isolated yields.
c 50 oC.
Ph
O
HN
R1 = OEt, 3a
R1 = Me, 3b
PhNH2
R1
O
O
0%
B2O3/Al2O3
r.t.
+
R1
nPr
R1 = OEt, 3m
R1 = Me, 3n
O
HN
R1
NH2
100%
Scheme 1. Chemoselective reaction.
Ph
O
HN
O
O
B2O3/Al2O3
r.t.
+
PhNH2
EtO
OEt
3a
Run 1: 95%; Run 2: 95%; Run 3: 92%; Run 4: 91%
Scheme 2. Reuse of the catalyst.

Vol. 21, No. 8, 2010
Chen et al.
1555
Table 3. Reaction of β-dicarbonyl compounds with diamines catalyzed by B2O3/Al2O3a
R2
R2
O
HN
NH2
O
O
R2
N
N
B2O3/Al2O3
r.t.
+
H
H
+
H2N
NH2
R1
R1
R1
O
O
R1
1
4
5
6
Entry
1
R1
Diamine 4
time
Product
Yield (%)b
O
HN
NH
O
OEt
Me
20 min
95
99
H2N
NH2
EtO
OEt
5a
O
HN
NH
O
2
3
5 min
1 h
H2N
NH2
5b
O
O
OEt
NH
HN
EtO
OEt
Me
88
97
H2N
NH2
5c
O
O
NH
HN
4
5
1 h
4 h
H2N
NH2
5d
H2N
HN
NH2
OEt
Me
86
81
O
NH2
EtO
6a
H2N
NH2
NH2
6
3.5 h
O
HN
6b
a All reactions were run with 1 (2 mmol), 4 (1 mmol) and B2O3/Al2O3 (0.03 g, 15% m/m) in the absence of solvent at room temperature. b Isolated yields.
Conclusions
and 13C NMR spectra were taken on a Bruker DPX300
spectrometer using CDCl3 as the solvent with
tetramethylsilane (TMS) as an internal standard at room
temperature. Chemical shifts were given in δ relative to
TMS, the coupling constants J are given in Hz.
In conclusion, we have reported B2O3/Al2O3 as a highly
efficient heterogeneous reusable catalyst for chemoselective
enamination of β-dicarbonyl compounds with aliphatic and
aromatic amines under solvent-free conditions. In addition,
the important features of this procedure are mild reaction
conditions, high yield, and operational simplicity which
make it a useful and attractive strategy for the preparation
of N-substituted β-enamino carbonylic compounds.
General procedure for the preparation of b-enamino
ketones and esters
To a magnetically stirred mixture of the β-dicarbonyl
compounds (1 mmol) and amines (1.1 mmol), B2O3/Al2O3
(0.03 g, 15% m/m) was added and the reaction mixture
was stirred at room temperature for the appropriate time.
The reaction was monitored by TLC. After completion of
the reaction, the reaction mixture was diluted with ethyl
Experimental
Melting points were recorded on Digital Melting
Point Apparatus WRS-1B and were uncorrected. 1H NMR

1556
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
acetate. The catalyst was separated by filtration, then the
solution was washed with ethyl acetate (5 mL) and dried
over anhydrous sodium sulfate, filtered and the solvent was
evaporated under vacuum. The residue was purified by flash
column chromatography to afford the desired product. The
spectral and analytical data of all compounds are given in
Supporting Information.
8. Ceric ammonium nitrate: Duan, Z.; Li, T.; Xuan, X. J.; Wu, Y.
J.; Chin. Chem. Lett. 2006, 17, 1566; Sridharan, V.; Avendano,
C.; Menendez, J. C.; Synlett 2007, 881; Mo, L. P.; Liu, S. F.;
Li, W. Z.; J. Chin. Chem. Soc. 2007, 54, 879.
9. 12-Tungstophosphoric acid: Chen, X.; She, J.; Shang, Z. C.;
Wu, J.; Wu, H. F.; Zhang, P. Z.; Synthesis 2008, 3478.
10. InBr3: Zhang, Z. H.; Yin, L.; Wang, Y. M.; Adv. Synth. Catal.
2006, 348, 184 and references cited therein.
Supplementary Information
11. ZrOCl2·8H2O: Zhang, Z. H.; Li, T. S.; Li, J. J.; Catal. Commun.
2007, 8, 1615.
Supplementary data are available free of charge at
http://jbcs.sbq.org.br, as PDF file.
12. CoCl2: Zhang, Z. H.; Hu, J. Y.; J. Braz. Chem. Soc. 2006, 17,
1447.
13. Silica-supported sulfuric acid: Chen, X.; She, J.; Shang, Z. C.;
Wu, J.; Zhang, P. Z.; Synth. Commun. 2009, 39, 947.
14. Silica-supported antimony(III) chloride: Zhang, L. F.;Yang, S.
T.; Russ. J. Org. Chem. 2009, 45, 18.
Acknowledgments
We are grateful to the National Key Technology R&D
Program (No. 2007BAI34B00) and the Natural Science
Foundation of Zhejiang Province (No. Y4080107) for
financial support.
15. Phosphotungstic acid: Li, G. C.; J. Chem. Res. 2007, 696.
16. Sulfated zirconia: Zhang, Z. H.; Song, L. M.; J. Chem. Res.
2005, 817.
17. SnCl4: Tin tetrachloride: Zhang, Z. H.; Ma, Z. C.; Mo, L. P.;
Indian J. Chem. 2007, 46B, 535.
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Received: December 1. 2009
Web Release Date: April 27, 2010

J. Braz. Chem. Soc., Vol. 21, No. 8, S1-S28, 2010.
Printed in Brazil - ©2010 Sociedade Brasileira de Química
0103 - 5053 $6.00+0.00
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst for the
Selective Synthesis of β-Enamino Ketones and Esters under Solvent-Free Conditions
Jiu-Xi Chen,a Chang-Fu Zhang,b Wen-Xia Gao,a Hui-Le Jin,a Jin-Chang Dinga,b and
Hua-Yue Wu*,a
aCollege of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, 325035, China
bWenzhou Vocational and Technical College, Wenzhou, 325035, China
Description of the products
134.2, 123.0, 128.2, 126.9, 126.9, 126.5, 125.5, 123.4,
122.8, 97.4, 29.2, 19.6.
(Z)-Ethyl 3-(phenylamino)but-2-enoate (3a)1
Oil, IR (KBr) nmax/cm-1: 3456, 3258, 2979, 1610, 1495,
(Z)-Ethyl 3-(p-toluidino)but-2-enoate (3e)1
1442, 1370, 1270, 1162, 1056 cm–1. H NMR (300 MHz,
Oil; IR (KBr) nmax/cm-1: 3257, 3189, 2979, 1615, 1509,
1441, 1271, 1161, 1059, 792; 1H NMR (300MHz, CDCl3):
d 10.28 (br s, 1H, NH), 7.10-7.13 (m, 2H), 6.96-6.99 (m,
2H), 4.66 (s, 1H), 4.14 (q, J 7.2Hz, 2H), 2.33 (s, 3H), 1.95
(s, 3H), 1.28 (t, J 7.2Hz, 3H); 13C MNR (75MHz, CDCl3):
d 170.5, 158.8, 136.7, 134.9, 129.6, 124.7, 85.3, 58.7,
20.9, 20.3, 14.6.
1
CDCl3): d 10.41 (br s, 1H, NH), 7.30-7.35 (m, 2H), 7.08-7.18
(m, 3H), 4.71 (s, 1H), 4.17 (q, J 7.2 Hz, 2H), 2.01 (s, 3H),
1.32 (t, J 7.2 Hz, 3H). 13C MNR (75 MHz, CDCl3): d 170.4,
158.9, 139.3, 129.0, 124.9, 124.4, 85.9, 58.7, 20.3, 14.6.
(Z)-4-(Phenylamino)pent-3-en-2-one (3b)
Solid, mp: 47-49 oC (Lit.1 48-49 oC); IR (KBr) nmax/cm-1:
3349, 2980, 1605, 1499, 1432, 1276, 1183, 1017, 746; 1H
NMR (300MHz, CDCl3): d 12.46 (br s, 1H, NH), 7.25-7.30
(m, 2H), 7.03-7.15 (m, 3H), 5.14 (s, 1H), 2.05 (s, 3H), 1.93
(s, 3H); 13C MNR (75MHz, CDCl3): d 196.0, 160.2, 138.6,
129.0, 125.5, 124.6, 97.6, 29.1, 19.8.
(Z)-4-(p-Toluidino)pent-3-en-2-one (3f)
Solid, mp: 66-67 oC (Lit.4 68-69 oC); IR (KBr) nmax/cm-1:
3448, 2922, 1607, 1508, 1434, 1276, 1178, 1013, 822,
753; 1H NMR (300MHz, CDCl3): d 12.40 (br s, 1H, NH),
7.14 (d, J 8.4Hz, 2H), 7.00 (d, J 8.4Hz, 2H), 5.16 (s, 1H),
2.34 (s, 3H), 2.09 (s, 3H), 1.96 (s, 3H); 13C MNR (75MHz,
CDCl3): d 195.9, 160.7, 136.1, 135.5, 129.6, 124.8, 97.2,
29.1, 20.9, 19.7.
(Z)-Ethyl 3-(naphthalen-1-ylamino)but-2-enoate (3c)2
Oil; IR (KBr) nmax/cm-1:: 3246, 3056, 2978, 1605, 1441,
1
1384, 1266, 1165, 785; H NMR (300MHz, CDCl3): d
10.61 (br s, 1H, NH), 8.06-8.09 (m, 1H), 7.86-7.89 (m,
1H), 7.75 (d, J 8.4 Hz, 1H), 7.26-7.57 (m, 4H), 4.83 (s,
1H), 4.23 (q, J 7.2Hz, 2H), 1.86 (s, 3H), 1.34 (q, J 7.2Hz,
(Z)-Ethyl 3-(2-methoxyphenylamino)but-2-enoate (3g)5
Oil; IR (KBr) nmax/cm-1: 3262, 2976, 1614, 1464, 1376,
1
1220, 1161, 1037, 746; H NMR (300MHz, CDCl3): d
13
3H); C MNR (75MHz, CDCl3): d 170.7, 160.5, 135.3,
10.28 (br s, 1H, NH), 7.08-7.14 (m, 2H), 6.88-6.92 (m,
2H), 4.71 (s, 1H), 4.16 (q, J 7.2Hz, 2H), 3.86 (s, 3H), 2.01
(s, 3H), 1.28 (t, J 7.2Hz, 3H); 13C MNR (75MHz, CDCl3):
d 170.2, 158.9, 152.6, 128.6, 125.3, 124.4, 120.3, 111.0,
86.3, 58.7, 55.7, 20.4, 14.6.
134.3, 130.4, 128.2, 126.7, 126.5, 126.4, 125.3, 123.6,
122.7, 85.7, 58.8, 20.04, 14.7.
(Z)-4-(Naphthalen-1-ylamino)pent-3-en-2-one (3d)
o
o
Solid, mp: 61-63 C (Lit.3 51-53 C); IR (KBr) nmax
/
cm-1: 3430, 2972, 1600, 1550, 1425, 1278, 1078, 1015,
774; 1H NMR (300MHz, CDCl3): d 12.76 (br s, 1H, NH),
8.02-8.05 (m, 1H), 7.87-7.90 (m, 1H), 7.77 (d, J 8.4Hz,
1H), 7.27-7.56 (m, 4H), 5.32 (s, 1H), 2.18 (s, 3H), 1.88 (s,
(Z)-4-(2-Methoxyphenylamino)pent-3-en-2-one (3h)5
Oil; IR (KBr) nmax/cm-1: 3456, 2949, 2841, 1607, 1481,
1344, 1274, 1180, 1025, 747; 1H NMR (300MHz, CDCl3):
d 12.32 (br s, 1H, NH), 7.01-7.18 (m, 2H), 6.87-6.93 (m,
2H), 5.20 (s, 1H), 3.86 (s, 3H), 2.10 (s, 3H), 1.99 (s, 3H);
13C MNR (75MHz, CDCl3): d 195.9, 160.4, 152.8, 128.0,
126.2, 125.0, 120.3, 111.2, 97.8, 55.7, 29.1, 20.0.
13
3H); C MNR (75MHz, CDCl3): d 196.6, 161.9, 134.8,
*e-mail: huayuewu@wzu.edu.cn

S2
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
(Z)-Ethyl 3-(3-chlorophenylamino)but-2-enoate (3i)6
Oil; IR (KBr) nmax/cm-1: 3190, 2979, 1637, 1476, 1370,
(Z)-Ethyl 3-(benzylamino)but-2-enoate (3o)5
Oil; IR (KBr) nmax/cm-1: 3289, 2977, 1605, 1499, 1445,
1280, 1169, 1113, 786, 697; 1H NMR (300MHz, CDCl3): d
8.96 (br s, 1H, NH), 7.24-7.37 (m, 5H), 4.54 (s, 1H), 4.43
(d, J 6.3Hz, 2H), 4.10 (q, J 7.2Hz, 2H), 1.92 (s, 3H), 1.26 (t,
J 7.2Hz, 3H); 13C MNR (75MHz, CDCl3): d 170.5, 161.7,
138.7, 128.7, 127.2, 126.6, 83.1, 58.3, 46.7, 19.3, 14.5.
1
1270, 1164, 1074, 784; H NMR (300MHz, CDCl3): d
10.42 (br s, 1H, NH), 7.10-7.22 (m, 3H), 6.94-6.96 (m,
1H), 4.72 (s, 1H), 4.15 (q, J 7.2Hz, 2H), 2.02 (s, 3H), 1.28
(t, J 7.2Hz, 3H); 13C MNR (75MHz, CDCl3): d 170.3,
158.0, 140.7, 134.6, 130.0, 124.7, 123.9, 122.1, 87.5,
59.0, 20.4, 14.6.
(Z)-4-(Benzylamino)pent-3-en-2-one (3p)5
(Z)-4-(3-Chlorophenylamino)pent-3-en-2-one (3j)
Solid, mp: 37-39 oC (Lit.1 39-40 oC); IR (KBr) nmax/cm-1:
3428, 2978, 1578, 1491, 1429, 1276, 1186, 1020, 937,
772; 1H NMR (300MHz, CDCl3): d 12.47 (br s, 1H, NH),
6.98-7.29 (m, 4H), 5.22 (s, 1H), 2.11 (s, 3H), 2.02 (s, 3H);
13C MNR (75MHz, CDCl3): d 196.4, 157.8, 140.2, 128.1,
127.5, 124.9, 118.3, 115.7, 97.0, 43.2, 19.3.
Oil; IR (KBr) nmax/cm-1: 3446, 2926, 1605, 1509, 1441,
1360, 1295, 1104, 1023, 739; 1H NMR (300MHz, CDCl3):
d 11.16 (br s, 1H, NH), 7.24-7.36 (m, 5H), 5.04 (s, 1H),
4.45 (d, J 6.3Hz, 2H), 2.03 (s, 3H) 1.91 (s, 3H); 13C MNR
(75MHz, CDCl3): d 195.3, 163.0, 138.0, 128.7, 127.3,
126.6, 95.8, 46.6, 28.8, 18.8.
4-(Diethylamino)pent-3-en-2-one (3q)9
(Z)-Ethyl 3-(4-chlorophenylamino)but-2-enoate (3k)
Solid, mp: 52-54 oC (Lit.1 54-55 oC); IR (KBr) nmax/cm-1:
3457, 2980, 1633, 1491, 1383, 1272, 1160, 787; 1H NMR
(300MHz, CDCl3): d 10.34 (br s, 1H, NH), 7.22-7.26 (m,
2H), 6.97-6.99 (m, 2H), 4.69 (s, 1H), 4.12 (q, J 7.2Hz,
2H), 1.95 (s, 3H), 1.26 (t, J 7.2Hz, 3H); 13C MNR (75MHz,
CDCl3): d 170.4, 158.3, 138.0, 130.2, 129.2, 125.5, 86.9,
58.9, 20.2, 14.6.
Oil; IR (KBr) nmax/cm-1: 2975, 1628, 1538, 1439, 1355,
1
1193; H NMR (300MHz, CDCl3): d 5.07 (s, 1H), 3.25-
3.32 (m, 4H), 2.51 (s, 3H), 2.05 (s, 3H), 1.13-1.18 (m,
6H); 13C MNR (75MHz, CDCl3): d 194.1, 160.0, 93.8,
43.7, 15.1, 12.4.
4-Morpholinopent-3-en-2-one (3r)1
Oil; IR (KBr) nmax/cm-1: 2964, 2854, 1640, 1544, 1431,
1257, 1184, 1119; 1H NMR (300MHz, CDCl3): d 5.21 (s,
1H), 3.64-3.71 (m, 4H), 3.26-3.30 (m, 4H), 2.43 (s, 3H),
1.97 (s, 3H); 13C MNR (75MHz, CDCl3): d 195.5, 160.6,
96.9, 66.5, 45.8, 30.7, 15.1.
(Z)-Ethyl 3-(4-bromophenylamino)but-2-enoate (3l)
Solid, mp: 53-55 oC (Lit.3 54-55 oC); IR (KBr) nmax/cm-1:
3451, 3273, 2924, 1622, 1482, 1358, 1269, 1163, 1059,
786; 1H NMR (300MHz, CDCl3): d 10.35 (br s, 1H, NH),
7.38-7.43 (m, 2H), 6.91-6.96 (m, 2H), 4.70 (s, 1H), 4.12
Ethyl 3-morpholinobut-2-enoate (3s)9
13
(q, J 7.2Hz, 2H), 1.97 (s, 3H), 1.26 (t, J 7.2Hz, 3H); C
Oil; IR (KBr) nmax/cm-1: 2970, 2854, 1688, 1584, 1435,
1259, 1144, 998, 805; 1H NMR (300MHz, CDCl3): d 4.78
(s, 1H), 4.06-4.12 (m, 2H), 3.69-3.73 (m, 4H), 3.19-3.23 (m,
4H), 2.40 (s, 3H), 1.22-1.27 (m, 3H); 13C MNR (75MHz,
CDCl3): d 168.6, 160.9, 88.1, 66.0, 58.4, 46.1, 15.0, 14.2.
MNR (75MHz, CDCl3): d 170.3, 158.2, 138.5, 132.1,
125.7, 117.9, 87.0, 58.9, 20.3, 14.6.
(Z)-Ethyl 3-(propylamino)but-2-enoate (3m)7
Oil; IR (KBr) nmax/cm-1: 3285, 2965, 1609, 1448, 1270,
1160, 1065, 784, 695; 1H NMR (300MHz, CDCl3): d 8.51
(br s, 1H, NH), 4.36 (s, 1H), 4.00-4.03 (m, 2H), 3.07-3.11
(m, 2H), 1.85 (s, 3H), 1.49-1.53 (m, 2H), 1.16-1.18 (m, 3H),
0.90-0.91 (m, 3H); C MNR (75MHz, CDCl3): d 170.5,
161.8, 81.6, 58.0, 44.5, 23.5, 19.2, 14.5, 11.2.
(2Z, 2’Z)-Diethyl 3, 3’-(propane-1, 3-diylbis(azanediyl))
dibut-2-enoate (5a)1
Oil; IR (KBr) nmax/cm-1: 3283, 3193, 2977, 2248, 1604,
1270, 913, 787, 726, 554; 1H NMR (300MHz, CDCl3): d
8.47 (br s, 2H, NH), 4.37 (s, 2H), 3.98 (q, J 7.2Hz, 4H), 3.22
(q, J 6.3Hz, 4H), 1.82 (s, 6H), 1.74-1.76 (m, 2H), 1.15 (t,
J 7.2Hz, 6H); 13C MNR (75MHz, CDCl3): d 170.5, 161.7,
82.6, 58.2, 39.7, 30.9, 19.2, 14.5.
13
(Z)-4-(Propylamino)pent-3-en-2-one (3n)8
Oil; IR (KBr) nmax/cm-1: 3451, 2960, 1603, 1443, 1359,
1295, 740, 647; 1H NMR (300MHz, CDCl3): d 10.85 (br
s, 1H, NH), 4.93 (s, 1H), 3.14-3.21 (m, 2H), 1.98 (s, 3H),
1.90 (s, 3H), 1.53-1.62 (m, 2H), 0.93-0.98 (m, 3H); 13C
MNR (75MHz, CDCl3): d 194.8, 163.1, 95.0, 44.8, 28.7,
23.3, 18.8, 11.3.
(3Z, 3’Z)-4, 4’-(Propane-1, 3-diylbis(azanediyl))dipent-
3-en-2-one (5b)
Solid, mp: 43-45 oC (Lit.10 50-52 oC); IR (KBr) nmax/cm-1:
3442, 2940, 1606, 1438, 1363, 1294, 1123, 1016, 742; 1H
NMR (300MHz, CDCl3): d 10.87 (br s, 1H, NH), 4.98 (s,

Vol. 21, No. 8, 2010
Chen et al.
S3
1H), 3.32-3.38 (m, 2H), 1.99 (s, 3H), 1.92 (s, 3H), 1.85-
1.89 (m, 1H); 13C MNR (75MHz, CDCl3): d 195.2, 163.2
95.6, 39.6, 30.2, 28.8, 18.8.
(Z)-4-(2-Aminophenylamino)pent-3-en-2-one (6b)
o
Solid, mp: 129-131 C (Lit.6 not reported); IR (KBr)
n
max/cm-1: 3759, 3445, 2931, 1624, 1426, 1256, 1255, 1114,
765; 1H NMR (300MHz, CDCl3): d 12.47 (br s, 1H, NH),
6.98-7.28 (m, 4H), 5.21 (s, 1H), 2.10 (s, 3H), 2.02 (s, 3H);
13C MNR (75MHz, CDCl3): d 196.7, 159.3, 140.1, 134.6,
130.1, 125.4, 124.5, 122.6, 98.4, 29.3, 19.9.
(2Z,2’Z)-Diethyl 3,3'-(1,4-phenylenebis(azanediyl))dibut-
2-enoate (5c)27
o
o
Solid, mp: 135-137 C (Lit.11 135 C); IR (KBr) nmax
/
cm-1: 2450, 2979, 2929, 1617, 1484, 1385, 1256, 1056, 780,
679; 1H NMR (300MHz, CDCl3): d 10.34 (br s, 2H, NH),
7.04 (s, 4H), 4.70 (s, 2H), 4.15 (q, J 7.2Hz, 4H), 2.00 (s,
6H), 1.29 (d, J 7.2Hz, 6H); 13C MNR (75MHz, CDCl3): d
170.3, 158.7, 136.2, 124.9, 86.2, 58.7, 20.2, 14.5.
References
1. Zhang, Z. H.; Yin, L.; Wang, Y. M.; Adv. Synth. Catal. 2006,
348, 184.
2. Khodaei, M. M.; Khosropour,A. R.; Kookhazadeh, M.; Synlett
2004, 1980.
(3Z,3’Z)-4,4’-(1,4-Phenylenebis(azanediyl))dipent-3-en-
2-one (5d)28
3. Xu, F.; Lv, H.-X.; Wang, J.-P.; Tian,Y.-P.; Wang, J.-J.; J. Chem.
Res. 2008, 707.
o
o
Solid, mp: 185-187 C (Lit.12 172 C); IR (KBr) nmax
/
cm-1: 3442, 2926, 1614, 1568, 1492, 1430, 1267, 1177,
1008, 865, 737; 1H NMR (300MHz, CDCl3): d 11.96 (br
s, 2H, NH), 7.07 (s, 4H), 5.19 (s, 2H), 2.10 (s, 6H), 2.00
(s, 6H); 13C MNR (75MHz, CDCl3): d 196.3, 159.8, 136.1,
125.1, 97.8, 29.1, 19.8.
4. Roberts, E.; Turnur, E. E.; J. Chem. Soc. 1927, 1832.
5. Chen, X.; She, J.; Shang, Z. C.; Wu, J.; Wu, H. F.; Zhang, P. Z.;
Synthesis 2008, 3478.
6. Song, Z. Y.; Bai, D. R.; Yu, H. T.; Xu, L. L.; Zhang, W. X.;
Meng, J. B.; Matsuura, T.; Chin. Chem. Lett. 2004, 15, 127.
7. Jacobs, J.; Kesteleyn, B.; De Kimpe, N.; Tetrahedron 2008, 64,
7545.
(Z)-Ethyl 3-(2-aminophenylamino)but-2-enoate (6a)29
Solid, mp: 77-79 oC (Lit.13 85 oC); IR (KBr) nmax/cm-1:
3408, 3285, 2965, 1609, 1448, 1270, 1159, 1065, 784,
695; 1H NMR (300MHz, CDCl3): d 9.70 (br s, 1H, NH),
7.04-7.10 (m, 2H), 6.68-6.76 (m, 2H), 4.72 (s, 1H), 4.15
(q, J 7.2Hz, 2H), 3.84 (br s, 2H, NH), 1.80 (s, 3H), 1.28 (t,
J 7.2Hz, 3H); 13C MNR (75MHz, CDCl3): d 170.6, 161.5,
143.5, 128.6, 128.0, 124.7, 118.3, 115.6, 85.1, 58.7, 19.7,
14.6.
8. Zhang, Y.; Raines, A. J.; Flowers, R. A.; J. Org. Chem. 2004,
69, 6267.
9. Vohra, R. K.; Renaud, J. L.; Bruneau, C.; Synthesis 2007, 731.
10. Zhang, Z. H.; Hu, J.-Y; J. Braz. Chem. Soc. 2006, 17, 1447.
11. Bangdiwala, B. P.; Desai, C. M.; J. Indian Chem. Soc. 1954,
31, 688.
12. Kudryavtsev, A. S.; Savich, I. A.; Khimiya 1962, 17, 57.
13. Sexton, W. A.; J. Chem. Soc. 1942, 303.

S4
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S1. 1H NMR of 3a (300 MHz, CDCl3) and 13C NMR of 3a (75 MHz, CDCl3).

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Figure S2. 1H NMR of 3b (300 MHz, CDCl3) and 13C NMR of 3b (75 MHz, CDCl3).

S6
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S3. 1H NMR of 3c (300 MHz, CDCl3) and 13C NMR of 3c (75 MHz, CDCl3).

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Chen et al.
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Figure S4. 1H NMR of 3d (300 MHz, CDCl3) and 13C NMR of 3d (75 MHz, CDCl3).

S8
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S5. 1H NMR of 3e (300 MHz, CDCl3) and 13C NMR of 3e (75 MHz, CDCl3).

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Figure S6. 1H NMR of 3f (300 MHz, CDCl3) and 13C NMR of 3f (75 MHz, CDCl3).

S10
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S7. 1H NMR of 3g (300 MHz, CDCl3) and 13C NMR of 3g (75 MHz, CDCl3).

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Figure S8. 1H NMR of 3h (300 MHz, CDCl3) and 13C NMR of 3h (75 MHz, CDCl3).

S12
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S9. 1H NMR of 3i (300 MHz, CDCl3) and 13C NMR of 3i (75 MHz, CDCl3).

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Figure S10. 1H NMR of 3j (300 MHz, CDCl3) and 13C NMR of 3j (75 MHz, CDCl3).

S14
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S11. 1H NMR of 3k (300 MHz, CDCl3) and 13C NMR of 3k (75 MHz, CDCl3).

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Figure S12. 1H NMR of 3l (300 MHz, CDCl3) and 13C NMR of 3l (75 MHz, CDCl3).

S16
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S13. 1H NMR of 3m (300 MHz, CDCl3) and 13C NMR of 3m (75 MHz, CDCl3).

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Chen et al.
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Figure S14. 1H NMR of 3n (300 MHz, CDCl3) and 13C NMR of 3n (75 MHz, CDCl3).

S18
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S15. 1H NMR of 3o (300 MHz, CDCl3) and 13C NMR of 3o (75 MHz, CDCl3).

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S19
Figure S16. 1H NMR of 3p (300 MHz, CDCl3) and 13C NMR of 3p (75 MHz, CDCl3).

S20
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S17. 1H NMR of 3q (300 MHz, CDCl3) and 13C NMR of 3q (75 MHz, CDCl3).

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Figure S18. 1H NMR of 3r (300 MHz, CDCl3) and 13C NMR of 3r (75 MHz, CDCl3).

S22
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S19. 1H NMR of 3s (300 MHz, CDCl3) and 13C NMR of 3s (75 MHz, CDCl3).

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Figure S20. 1H NMR of 5a (300 MHz, CDCl3) and 13C NMR of 5a (75 MHz, CDCl3).

S24
B2O3/Al2O3 as a New, Highly Efficient and Reusable Heterogeneous Catalyst
J. Braz. Chem. Soc.
Figure S21. 1H NMR of 5b (300 MHz, CDCl3) and 13C NMR of 5b (75 MHz, CDCl3).

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Figure S22. 1H NMR of 5c (300 MHz, CDCl3) and 13C NMR of 5c (75 MHz, CDCl3).