Efficient and convenient oxidation of urazoles to their corresponding triazolinediones under solvent-free conditions

Article abstract of DOI:10.1081/SCC-120014774

Urazoles are oxidized to their corresponding triazolinediones in excellent yields with potassium dichromate in the presence of aluminium chloride under solvent-free conditions.

Full text of DOI:10.1081/SCC-120014774

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EFFICIENT AND CONVENIENT OXIDATION OF URAZOLES
TO THEIR CORRESPONDING TRIAZOLINEDIONES UNDER
SOLVENT-FREE CONDITIONS
a
a
b
Iraj Mohammadpoor-Baltork , Majid M. Sadeghi , Shadpour E. Mallakpour , Abdol Reza
b
a
Hajipour & Abol-Hassan Adibi
a
Department of Chemistry , Isfahan University , Isfahan, 81744, Iran
b
College of Chemistry , Isfahan University of Technology , Isfahan, 84156, Iran
Published online: 22 May 2009.
To cite this article: Iraj Mohammadpoor-Baltork , Majid M. Sadeghi , Shadpour E. Mallakpour , Abdol Reza Hajipour & Abol-
Hassan Adibi (2002) EFFICIENT AND CONVENIENT OXIDATION OF URAZOLES TO THEIR CORRESPONDING TRIAZOLINEDIONES
UNDER SOLVENT-FREE CONDITIONS, Synthetic Communications: An International Journal for Rapid Communication of Synthetic
Organic Chemistry, 32:22, 3445-3448, DOI: 10.1081/SCC-120014774
To link to this article: http://dx.doi.org/10.1081/SCC-120014774
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SYNTHETIC COMMUNICATIONS
Vol. 32, No. 22, pp. 3445–3448, 2002
EFFICIENT AND CONVENIENT
OXIDATION OF URAZOLES TO THEIR
CORRESPONDING TRIAZOLINEDIONES
UNDER SOLVENT-FREE CONDITIONS
1
,
1
Iraj Mohammadpoor-Baltork, * Majid M. Sadeghi,
2
Shadpour E. Mallakpour, Abdol Reza Hajipour,
2
1
and Abol-Hassan Adibi
1
Department of Chemistry, Isfahan University,
Isfahan 81744, Iran
College of Chemistry, Isfahan University of
Technology, Isfahan 84156, Iran
2
ABSTRACT
Urazoles are oxidized to their corresponding triazolinediones
in excellent yields with potassium dichromate in the presence
of aluminium chloride under solvent-free conditions.
4
-Substituted-1,2,4-triazole-3,5-diones are valuable starting materials
[
1–5]
[6–8]
in different organic reactions such as [4 þ 2]
and [2 þ 2]
cyclo-
[11–13]
and electrophilic aromatic substitution.
[
9,10]
additions, ene reactions
[
14]
These compounds can also be used in dehydrogenation reactions
oxidation of alcohols to their corresponding carbonyl compounds.
and
15–17]
[
*
Corresponding author. E-mail: haji@cc.iut.ac.ir
445
3
DOI: 10.1081/SCC-120014774
Copyright & 2002 by Marcel Dekker, Inc.
0039-7911 (Print); 1532-2432 (Online)
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3
446
MOHAMMADPOOR-BALTORK ET AL.
Unusual reactivity of triazolinediones makes them hard to prepare and
purify.
Oxidation of urazoles is a common way for the preparation of tri-
azolinediones and a wide variety of methods and reagents have been
[
18–24]
reported in the literature for this purpose.
However, in some of these
methods by-products are produced or the products decompose under the
reaction conditions, and/or the workup is difficult. Therefore, the prepara-
tion of these compounds under mild and solid phase conditions is of
practical importance for synthetic organic chemists and is still in demand.
Heterogeneous reactions that are facilitated by supported reagents on
various solid inorganic surfaces have received attention in recent years. The
advantages of these methods over conventional homogeneous reactions are
higher selectivity, enhanced reaction rates, cleaner products, and mani-
pulative simplicity. In continuation of our ongoing work on development
[
25–27]
of environmentally beingn methods using solid support,
we now report
a very convenient method for the oxidation of urazoles with potassium
dichromate in the presence of aluminium chloride under solid phase
conditions (Sch. 1).
As shown in Table 1, different kinds of urazoles are rapidly oxidized
with potassium dichromate in the presence of aluminium chloride under
solvent-free conditions to afford the corresponding triazolinediones in
excellent yields.
In conclusion, in this study we have introduced a simple, rapid, and
mild procedure for the oxidation of urazoles. In addition, the commercial
availability and low cost of the reagent, high yields of the products, short
reaction times, and easy workup are noteworthy advantages of the present
method.
1
R
2
R
1
a
b
c
d
e
f
H
H
H
H
Ph
4-ClC
6 4
H
4-NO
Et
n-Pr
2 6 4
C H
Na
H
Cyclohexyl
Scheme 1.

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OXIDATION OF URAZOLES TO TRIAZOLINEDIONES
3447
Table 1. Oxidation of Urazoles to Triazolinediones with
Under Solvent-Free Conditions
K
2
Cr
2
O
7
/AlCl
3
b
Time
(min)
Yield
(%)
a
Substrate
Product
c
1a
1b
1c
1d
1e
1f
2a
3
15
20
5
5
3
95
90
90
93
95
98
2b
2c
2d
2e
2f
a
All products were identified by comparison of their physical and
spectral data with those of authentic samples.
b
Isolated yields.
In the absence of AlCl , 4-phenyl urazole remained intact after
c
3
3
2 2 7
0 min in the presence of K Cr O .
EXPERIMENTAL
Oxidation of Urazoles: General Procedure
A mortar was charged with urazole (2 mmol), potassium dichromate
4 mmol) and aluminium chloride (2 mmol). The mixture was ground with a
(
pestle until TLC showed complete disappearance of the starting material.
The reaction mixture was sublimed directly to afford the pure triazolinedione
in 90–98% yields (Table 1).
ACKNOWLEDGMENT
We are thankful to the Isfahan University Research Council for
partial support of this work.
REFERENCES
1. Mallakpour, S.E.; Zolfigol, M.A. Indian J. Chem. 1995, 34B, 183.
2. Mallakpour, S.E.; Zolfigol, M.A. Indian J. Chem. 1995, 34B, 302.
3. Mallakpour, S.E.; Zolfigol, M.A. Indian J. Chem. 1998, 37B, 1001.
4. Mallakpour, S.E.; Zolfigol, M.A. Indian J. Chem. 1999, 38B, 777.

MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016
©
2002 Marcel Dekker, Inc. All rights reserved. This material may not be used or reproduced in any form without the express written permission of Marcel Dekker, Inc.
3
448
MOHAMMADPOOR-BALTORK ET AL.
5. Desimoni, G.; Faita, G.; Righetti, P.P.; Sulcini, A.; Tsyganov, D.
Tetrahedron 1994, 50, 1821.
6. Hall, J.H.; Krishnan, G. J. Org. Chem. 1984, 49, 2498.
7. Hall, J.H.; Jones, M.L. J. Org. Chem. 1983, 48, 822.
8. Seymour, G.A.; Green, F.D. J. Am. Chem. Soc. 1980, 102, 6384.
9. Mallakpour, S.E.; Butler, G.B.; Aghabozorg, H.; Palanik, G.
J. Macromolecules 1985, 18, 342.
1
1
1
1
0. Lai, Y.C.; Mallakpour, S.E.; Butler, G.B.; Palanik, G. J. Org. Chem.
985, 50, 4378.
1. Mallakpour, S.E.; Butler, G.B. J. Polym. Sci. Part A: Polym. Chem.
Ed. 1989, 27, 217.
2. Mallakpour, S.E.; Butler, G.B. J. Polym. Sci. Part A: Polym. Chem.
Ed. 1989, 27, 215.
3. Mallakpour, S. E.; Butler, G.B. J. Polym. Sci. Part A: Polym. Chem.
Ed. 1987, 25, 2781.
1
1
1
4. Klindert, T.; Seitz, G. Synth. Commun. 1996, 26, 2587.
5. Cookson, R.C.; Stevens, I.D.R.; Watts, C.T. Chem. Commun.
1966, 744.
16. Borhani, D.W.; Green, F.D. J. Org. Chem. 1986, 51, 1563.
17. Akasaka, T.; Sonobe, H.; Sato, R.; Ando, W. Tetrahedron Lett. 1984,
25, 4757.
1
1
2
2
2
8. Stickler, J.C.; Pirkle, W.H. J. Org. Chem. 1966, 31, 3444.
9. Read, G.; Rechardson, N.R. J. Chem. Soc. Perkin Trans. 1 1996, 167.
0. Mallakpour, S.E. J. Chem. Ed. 1992, 69, 238.
1. Mallakpour, S.E.; Zolfigol, M.A. J. Sci. I. R. Iran 1993, 4, 199.
2. Zolfigol, M.A.; Mallakpour, S.E.; Madrakian, E.; Ghaemi, E. Indian
J. Chem. 2000, 39B, 308.
2
2
3. Zolfigol, M.A.; Mallakpour, S.E. Synth. Commun. 1999, 29, 4061.
4. Zolfigol, M.A.; Kiany Borazjani, M.; Mallakpour, S.E.; Nasr-Isfahani,
H. Synth. Commun. 2000, 30, 2573.
2
2
2
5. Hajipour, A.R.; Mohammadpoor-Baltork, I.; Nikbaghat, K.;
Imanzadeh, G. Synth. Commun. 1999, 29, 1697.
6. Hajipour, A.R.; Mallakpour, S.E.; Mohammadpoor-Baltork, I.;
Khoee, S. Chem. Lett. 2000, 120.
7. Hajipour, A.R.; Mohammadpoor-Baltork, I. Phosphorus, Sulfur and
Silicon. 2000, 164, 145.
Received in Japan August 8, 2001