Melamine trisulfonic acid: An efficient, heterogeneous and reusable catalyst for the synthesis of 10-aryl-6,8-dimethyl-6, 10-dihydro-5-oxa-6,8- diazaanthra [2,3-d][1,3]dioxole-7,9-diones

Article abstract of DOI:10.1155/2011/853747

Melamine trisulfonic acid was used as an efficient and recyclable catalyst for the one-pot synthesis of 10-aryl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8- diazaanthra[2,3-d][1,3]dioxole-7,9-diones by condensation of 3,4-methylene dioxyphenol, aromatic aldehydes

Full text of DOI:10.1155/2011/853747

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
2011, 8(4), 1972-1978
http://www.e-journals.net
Melamine Trisulfonic Acid: An Efficient,
Heterogeneous and Reusable Catalyst for the
Synthesis of 10-Aryl-6,8-dimethyl- 6, 10-dihydro-5-
oxa-6,8-diazaanthra [2,3-d][1,3]dioxole- 7,9-diones
WEILIN LI* and QIUYAN LUO
*School of Pharmacy, Xinxiang Medical University
Xinxiang, Henan 453003, P. R. China
Department of Gynecological
The Third Affiliated Hospital to Xinxiang Medical University
Xinxiang 453003, P. R. China
linweilin1977@163.com
Received 17 January 2011; Accepted 1 March 2011
Abstract: Melamine trisulfonic acid was used as an efficient and recyclable
catalyst for the one-pot synthesis of 10-aryl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-
diazaanthra[2,3-d][1,3]dioxole-7,9-diones by condensation of 3,4-methylene
dioxyphenol, aromatic aldehydes and 1,3-dimethylbarbituric acid under solvent-
free conditions. Different types of aromatic. aldehydes were used in the reaction
and in all cases the products were obtained in good to excellent yields.
Keywords: Benzo[1,3]dioxoles, 3,4-Methylene dioxyphenol, Melamine trisulfonic acid, Solvent-free
Introduction
Multi-component, one-pot synthesis has received considerable attention because of their
wide range of applications in pharmaceutical chemistry for creation of structural diversity
and combinatorial libraries for drug discovery1. MCRs are extremely convergent, producing
a remarkably high increase of molecular complexity in just one step2. The ready availability,
potential biological activity and high reactivity of 3,4-methylenedioxyphenol makes it
attractive molecule in pharmaceutical chemistry3. Consequently, a large number of
3,4-methylenedioxyphenol derivatives have been prepared for biological evaluation4.
Recently, melamine trisulfonic acid (MTSA) has emerged as a promising solid acid
catalyst for acid catalyzed reactions, such as acetylation of alcohols, phenols and amines5,
oxathioacetalyzation of aldehydes6 and methoxymethylation of alcohols7. MTSA as a
solidacid catalyst is prepared from the reaction of melamine with neat chlorosulfonic acid at

1973
WEILIN LI et al.
room temperature (Scheme 1). Compared to conventional acids, MTSA in particular has
advantages of low catalyst loading, moisture stability and catalyst recycling. In the present
research, we wish to describe a simple and efficient protocol for the rapid preparation of
10-aryl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-diones
using a catalytic amount of recyclable MTSA under solvent-free conditions (Scheme 2). To
the best of our knowledge, there are no reports on three-component coupling of aldehyde,
3,4-methylenedioxyphenol and 1,3-dimethylbarbituric acid to produce a new class of
3,4-methylenedioxyphenol derivatives.
NHSO3H
NH2
neat
N
N
+ 3HCl
N
N
ClSO3H (3 eq.)
+
r.t.
HO3SHN
N
NHSO3H
R
H2N
N
NH2
Scheme 1
O
N
O
O
O
O
O
MTSA
neat, 110 °C
N
+
+ RCHO
O
N
O
OH
O
N
O
4
2
3
1
Scheme 2
Experimental
NMR spectra were determined on Bruker AV-400 instrument at room temperature using
TMS as internal standard, coupling constants (J) were measured in Hz; Elemental analysis
were performed by a Vario-III elemental analyzer; Mass spectra were taken on a Macro mass
spectrometer (Waters) by electro-spray method (ES); Melting points were determined on a
XT-4 binocular microscope and were uncorrected; Commercially available reagents were
used throughout without further purification unless otherwise stated.
Preparation of MTSA catalyst
A 250 mL suction flask charged with chlorosulfonic acid (5 mL, 75.2 mmol) was equipped
with a gas inlet tube for conducting HCl gas over an adsorbing solution. Melamine (3.16 g,
25.07 mmol) was added in small portions over a period of 30 min at room temperature. HCl
gas evolved from the reaction vessel immediately (Scheme 1). After completion of the
addition of melamine, the mixture was shaken for 30min; meanwhile, the residual HCl was
removed by suction. Melamine trisulfonic acid (7.7 g, 85%) was obtained as a white solid.
General procedure for the preparation of 4
A mixture of 3,4-methylene dioxyphenol, (1 mmol), aldehyde (1 mmol), 1,3-dimethylbarbituric
acid (1 mmol) and MTSA (0.05 mmol) was heated at 110 oC for an appropriate time (TLC). After
completion, the reaction mixture was washed with water (15 mL) and residue recrystallized from
EtOH to afford the pure product 4. Aqueous washings were collected and evaporated under
reduced pressure. After removal of the water, MTSAwas recovered.
10-Phenyl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-
7,9-dione (4a)
1
White powder, m.p. 245-246 oC; H NMR (CDCl3, 400 MHz) δ: 7.26-7.16 (m, 5H), 6.68
(s, 1H), 6.52 (s, 1H), 5.95 (d, 1H, J = 0.8 Hz), 5.91 (d, 1H, J = 0.8 Hz), 5.03 (s, 1H), 3.55 (s, 3H),

Melamine Trisulfonic Acid: An Efficient Catalyst
1974
3.28 (s, 3H); 13C NMR (CDCl3, 100 MHz) δ: 161.9, 152.6, 150.7, 147.2, 145.6, 145.1,
143.1, 128.6, 127.8, 127.7, 126.9, 116.8, 108.2, 101.8, 98.0, 90.0, 39.2, 29.0, 28.1; MS
(ESI): m/z 365 [M+H]+; Anal. calcd for C20H16N2O5: C 65.93, H 4.43, N 7.69; found: C
65.90, H 4.48, N 7.74.
10-(4-Chlorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]
dioxole-7,9-dione(4b)
1
White powder, m.p. 254-255 oC; H NMR (CDCl3, 400 MHz) δ: 7.22 (d, 2H, J = 6.4 Hz),
7.18 (d, 2H, J = 6.8 Hz), 6.67 (s, 1H), 6.47 (s, 1H), 5.97 (d, 1H, J = 0.8 Hz), 5.92 (d, 1H,
J = 0.8 Hz), 5.00 (s, 1H), 3.54 (s, 3H), 3.28 (s, 3H); 13C NMR (CDCl3, 100 MHz) δ: 161.8,
152.6, 150.6, 147.4, 145.7, 143.6, 143.0, 132.7, 129.3, 128.8, 128.7, 116.1, 108.0, 101.9,
98.1, 89.6, 38.6, 29.0, 28.1; MS (ESI): m/z 399 [M+H]+; Anal. calcd for C20H15ClN2O5: C
60.23, H 3.79, N 8.89; found: C 60.19, H 3.85, N 8.95..
10-(4-Fluorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]
dioxole-7,9-dione (4c)
1
White powder, m.p. 253-254 oC; H NMR (CDCl3, 400 MHz) δ: 7.22-7.19 (m, 2H), 6.95-
6.91 (m, 2H), 6.67 (s, 1H), 6.48 (s, 1H), 5.96 (d, 1H, J = 1.2 Hz), 5.92 (d, 1H, J = 1.2 Hz),
5.01 (s, 1H), 3.54 (s, 3H), 3.28 (s, 3H); 13C NMR (CDCl3, 100 MHz) δ: 161.9, 152.5, 150.6,
147.3, 145.6, 143.0, 140.9, 129.4, 116.5, 115.4, 115.2, 108.1, 101.9, 98.0, 89.8, 38.4, 29.0,
28.1; MS (ESI): m/z 383 [M+H]+; Anal. calcd for C20H15FN2O5: C 62.83, H 3.95, N 7.33;
found: C 62.90, H 3.89, N 7.40.
10-(4-Methylphenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]
dioxole-7,9-dione (4d)
1
White powder, m.p. 248-249 oC; H NMR (CDCl3, 400 MHz) δ: 7.14 (d, 2H, J = 8.0 Hz),
7.07 (d, 2H, J = 8.0 Hz), 6.67 (s, 1H), 6.52 (s, 1H), 5.95 (d, 1H, J = 0.8 Hz), 5.90 (d, 1H,
J = 0.8 Hz), 4.99 (s, 1H), 3.54 (s, 3H), 3.28 (s, 3H), 2.27 (s, 3H); 13C NMR (CDCl3, 100
MHz) δ: 161.9, 152.5, 150.7, 147.1, 145.5, 143.0, 142.3, 136.5, 129.3, 129.2, 127.7, 127.6,
117.0, 108.2, 101.8, 98.0, 90.1, 38.8, 29.0, 28.1, 21.0; MS (ESI): m/z 379 [M+H]+; Anal.
calcd for C21H18N2O5: C 66.66, H 4.79, N 7.40; found: C 66.70, H 4.69, N 7.49.
10-(4-Nitrophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]
dioxole-7,9-dione (4e)
1
White powder, m.p. 259-260 oC; H NMR (CDCl3, 400 MHz) δ: 8.12 (d, 2H, J = 8.8 Hz),
7.43 (d, 2H, J = 8.4 Hz), 6.71 (s, 1H), 6.44 (s, 1H), 5.98 (d, 1H, J = 0.8 Hz), 5.95 (d, 1H,
J = 0.8 Hz), 5.15 (s, 1H), 3.56 (s, 3H), 3.27 (s, 3H); 13C NMR (CDCl3, 100 MHz) δ: 161.8,
152.8, 152.1, 150.5, 147.8, 146.8, 145.9, 143.1, 128.9, 123.9, 114.9, 107.9, 102.1, 98.3, 88.8,
39.1, 29.1, 28.1; MS (ESI): m/z 410 [M+H]+; Anal. calcd for C20H15N3O7: C 58.68, H 3.69, N
10.27; found: C 58.60, H 3.72, N 10.20.
10-(3-Nitrophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]
dioxole-7,9-dione (4f)
o
1
White powder, m.p. 262-263 C; H NMR (CDCl3, 400 MHz) δ: 8.05-8.03 (m, 1H),
8.00-7.98 (m, 1H), 7.72 (d, 1H, J = 7.6 Hz), 6.71 (s, 1H), 6.44 (s, 1H), 5.98 (d, 1H, J = 0.8
Hz), 5.94 (d, 1H, J = 0.8 Hz), 5.15 (s, 1H), 3.57 (s, 3H), 3.27 (s, 3H); 13C NMR (CDCl3, 100
MHz) δ: 161.8, 152.8, 150.5, 148.5, 147.8, 147.1, 145.9, 143.0, 134.5, 129.3, 122.9, 115.0,
107.9, 102.1, 98.4, 88.8, 39.1, 29.1, 28.1; MS (ESI): m/z 410 [M+H]+; Anal. calcd for
C20H15N3O7: C 58.68, H 3.69, N 10.27; found: C 58.72, H 3.75, N 10.22.

1975
WEILIN LI et al.
10-(3,4-Dichlorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d]
[1,3]dioxole-7,9-dione(4g)
o
1
White powder, m.p. 247-248 C; H NMR (CDCl3, 400 MHz) δ: 7.33 (d, 1H, J = 8.0 Hz),
7.26-7.25 (m, 1H), 7.15 (dd, 1H, J = 2.0, 8.0 Hz), 6.68 (s, 1H), 6.45 (s, 1H), 5.98 (d, 1H,
J = 0.8 Hz), 5.94 (d, 1H, J = 0.8 Hz), 4.98 (s, 1H), 3.55 (s, 3H), 3.28 (s, 3H); 13C NMR
(CDCl3, 100 MHz) δ: 161.8, 152.7, 150.6, 147.6, 145.8, 145.3, 143.0, 132.6, 131.0, 130.4,
129.8, 127.5, 115.4, 107.9, 102.0, 98.2, 89.0, 38.5, 29.1, 28.1; MS (ESI): m/z 433 [M+H]+;
Anal. calcd for C20H14Cl2N3O7: C 55.45, H 3.26, N 6.47; found: C 55.50, H 3.20, N 6.50.
10-(2,4-Dichlorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d]
[1,3]dioxole-7,9-dione(4h)
o
1
White powder, m.p. 277-278 C; H NMR (CDCl3, 400 MHz) δ: 7.36 (d, 1H, J = 2.0 Hz),
7.14-7.12 (m, 2H), 6.63 (s, 1H), 6.55 (s, 1H), 5.96 (d, 1H, J = 1.6 Hz), 5.92 (d, 1H, J = 1.6
Hz), 5.52 (s, 1H), 3.57 (s, 3H), 3.27 (s, 3H); 13C NMR (CDCl3, 100 MHz) δ: 161.7, 153.1,
150.7, 147.4, 145.6, 142.7, 141.0, 133.5, 133.2, 131.2, 129.7, 127.6, 115.1, 107.5, 101.9,
98.0, 88.2, 38.6, 29.1, 28.1; MS (ESI): m/z 433 [M+H]+; Anal. calcd for C20H14Cl2N3O7: C
55.45, H 3.26, N 6.47; found: C 55.38, H 3.24, N 6.52.
10-(2-chlorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]
dioxole-7,9-dione(4i)
o
1
White powder, m.p. 233-234 C; H NMR (CDCl3, 400 MHz) δ: 7.34 (d, 1H, J = 7.6 Hz),
7.17-7.12 (m, 3H), 6.63 (s, 1H), 6.61 (s, 1H), 5.95 (d, 1H, J = 0.8 Hz), 5.90 (d, 1H, J = 0.8
Hz), 5.58 (s, 1H), 3.57 (s, 3H), 3.27 (s, 3H); 13C NMR (CDCl3, 100 MHz) δ:161.7, 153.1,
150.8, 147.3, 145.5, 142.7, 142.3, 132.8, 130.3, 130.0, 128.1, 127.2, 115.7, 107.7, 101.8,
97.9, 88.7, 38.2, 29.1, 28.1; MS (ESI): m/z 399 [M+H]+; Anal. calcd for C20H15ClN2O5: C
60.23, H 3.79, N 8.89; found: C 60.22, H 3.80, N 8.92.
Results and Discussion
To choose optimum conditions, first, the effect of temperature on the rate of the reaction was studied
for the preparation of 10-phenyl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d] [1,3]
dioxole-7,9-dione from the three-component condensation reaction of 3,4-methylenedioxyphenol,
benzaldehyde and 1,3- dimethylbarbituric acid in presence of 5 mol% melamine trisulfonic acid
under solvent-free conditions (Table 1). At 110 °C, the reaction proceeded smoothly and gave
short reaction time and high yield. Therefore, we kept the reaction temperature at 110 °C.
Table 1. Temperature optimization for the synthesis of synthesis of 7-phenyl-6H,7H-
naphtho[1',2': 5,6]pyrano[3,2-c]chromen-6-onea
Entry Temperature /oC
Time /h Yield/ %b
1
2
3
4
5
6
7
8
9
25
50
60
70
80
90
100
110
120
130
140
5
3
3
3
2
0
10
25
36
42
58
74
86
86
85
85
2
1.5
1.5
1.5
1
10
11
1
aReaction conditions: 3,4-methylenedioxyphenol (1 mmol); benzaldehyde (1 mmol); 1,3- dimethylbarbituric
acid (1 mmol); MTSA (0.05 mmol); neat, bIsolated yield

Melamine Trisulfonic Acid: An Efficient Catalyst
1976
Next, the study set out to determine optimal amount of MTSA, the reaction was carried
out by varying amount of the catalyst (Table 2). Maximum yield was obtained with 5 mol%
of the catalyst. Further increase in amount of MTSA in the mentioned reaction did not has
any significant effect on the product yield.
Table 2. The amounts of catalyst optimization for the synthesis of 7-phenyl-6H,7H-
naphtho[1',2': 5,6]pyrano[3,2-c]chromen-6-onea
Entry
MTSA /mol%
Time /h
5
Yield /%b
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
0
2
42
56
68
79
86
86
84
85
2
1.5
1.5
1.5
1.5
1.5
1.5
aReaction conditions: 3,4-methylenedioxyphenol (1 mmol); benzaldehyde (1 mmol); 1,3-
dimethylbarbituric acid (1 mmol); 110 °C; neat, bIsolated yield
In order to extend the above reaction (Scheme 2) to a library system, various kinds
of arylaldehydes 2 (Table 2) were subjected to react with 1 and 3 to give the
corresponding 10-aryl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra [2,3-d][1,3]-
dioxole- 7,9-diones and representative examples are shown in Table 2. All of 1 gave
expected products at high yields, either bearing electron-withdrawing groups (such as
halide, nitro) or electron-donating groups (such as alkyl group) under the same reaction
condition. To further demonstrate the scope and limitation of the substrates, aliphatic
aldehydes, such as phenylacetaldehyde, propionaldehyde, n-butyl aldehyde and
n-heptaldehyde, were used as reactants to react with3,4-methylenedioxyphenol and
1,3- dimethylbarbituric acid. However, the desired products were not found and
obtained successfully. All of the structures were characterized by 1H NMR, 13C NMR,
MS and elemental analysis
Table 3. Preparation of 10-aryl-6,8-dimethyl-6,10- dihydro-5-oxa-6,8-diazaanthra [2,3-d]
[1,3]dioxole-7,9-dionesa
Entry
R
C6H5
Time/ min
Product
4a
4b
Yield/ %b
1
2
3
4
5
6
7
8
9
1.5
1
86
89
85
80
95
88
85
83
79
4-Cl-C6H4
4-F-C6H4
1
4c
4d
4-Me-C6H4
4-NO2-C6H4
3-NO2-C6H4
2,4-Cl2-C6H3
3,4-Cl2-C6H3
2-Cl-C6H4
2
1
4e
1.5
2
2
1.5
4f
4g
4h
4i
a Reaction conditions: 3,4-methylenedioxyphenol (1 mmol); aldehyde (1 mmol); 1,3-dimethylbarbituric
acid (1 mmol);MTSA (0.05 mmol); 110 °C; neat. bIsolated yield

1977
WEILIN LI et al.
A tentative mechanism for this transformation is proposed in Scheme 3. The reaction
likely proceeds via initial formation of oxonium species 5, which then undergo dehydration
to give olefin 6. Subsequent Michael-type addition of 3,4-methylenedioxyphenol 1 to the
olefin followed by cyclization and dehydration to afford the corresponding products 4a-4i.
O
N
O
O
OH
Ar
OH
O
N
O
OH
N
O
Ar
N
-H2O, H
H
3
H
H
O
N
O
O
N
6
2
O
O
5
OH
H
1
Ar
Ar
O
O
Ar
O
O
N
O
O
O
O
O
O
N
N
N
-H2O
O
N
O
O
N
O
OH
HO
OH2
4
Scheme 3
Conclusion
In conclusion, an efficient protocol for the one-pot preparation of 10-aryl-6,8-dimethyl-
6,10- dihydro-5-oxa-6,8- diazaanthra[2,3-d][1,3]dioxole-7,9-diones from the three-
component condensation reaction of 3,4-methylene dioxyphenol, aromatic aldehydes and
1,3-dimethylbarbituric acid using a reusable MTSA as catalyst was described. The reactions
were carried out under thermal solvent-free conditions with short reaction time and produced
the corresponding products in good to excellent yields. Also the catalyst could be
successfully recovered and recycled at least for three runs without significant loss in activity.
Acknowledgment
We are pleased to acknowledge the financial support from Xinxiang Medical University.
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Melamine Trisulfonic Acid: An Efficient Catalyst
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Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
http://www.hindawi.com
Volume 2014
Volume 2014
Volume 2014
Volume 2014
Volume 2014