Chalcone ditosylates as potent precursor for synthesis of some 4,5-disubstituted isoxazoles with antioxidant and anti-inflammatory activities

Article abstract of DOI:10.14233/ajchem.2019.22077

The present work emphasizes on the synthesis of a series of 4,5-disubstituted isoxazole derivatives of α,β-chalcone ditosylates which were synthesized by the reaction of α,β-chalcone ditosylates with hydroxylamine hydrochloride. Various α,β-chalcone ditos

Full text of DOI:10.14233/ajchem.2019.22077

Asian Journal of Chemistry; Vol. 31, No. 8 (2019), 1847-1850
A
SIAN
J
OURNAL OF HEMISTRY
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https://doi.org/10.14233/ajchem.2019.22077
Chalcone Ditosylates as Potent Precursor for Synthesis of Some 4,5-Disubstituted
Isoxazoles with Antioxidant and Anti-inflammatory Activities
1,*
2
3
PRAGI , JAGDEEP SINGH DUA and JITENDER SINGH
1Department of Pharmaceutical Sciences, Indra Kumar Gujral Punjab Technical University, Kapurthala-144603, India
2Shivalik College of Pharmacy, Nangal-140124, India
3Lord Shiva College of Pharmacy, Sirsa-125055, India
*Corresponding author: E-mail: arorapragi@gmail.com
Received: 14 March 2019;
Accepted: 26 April 2019;
Published online: 28 June 2019;
AJC-19464
The present work emphasizes on the synthesis of a series of 4,5-disubstituted isoxazole derivatives of α,β-chalcone ditosylates which
were synthesized by the reaction of α,β-chalcone ditosylates with hydroxylamine hydrochloride. Various α,β-chalcone ditosylates were
prepared by the reaction of respective chalcones with hydroxyl (tosyloxy)iodobenzene.The synthesized compounds were characterized
and subsequently evaluated for anti-inflammatory and antioxidant properties.
Keywords: α,β-Chalcone ditosylates, 4,5-Disubstituted isoxazoles, hydroxyl(tosyloxy)iodobenzene, Microbial activity.
amine hydrochloride to produce 1,2-aryl shift and thus give a
novel method for the synthesis of 4,5-disubstituted isoxazoles.
Different chalcone ditosylates were prepared by the reaction
of chalcones with Koser's reagent (hydroxyl(tosyloxy)iodo-
benzene, HTIB) as described by Rebrovic and Koser [23],
where they reported a stereo-specific syn-1,2-ditosyloxylation
of carbon-carbon double bond using HTIB.
INTRODUCTION
Isoxazoles are an important class of heterocyclic comp-
ounds and their chemical properties have been studied over
the years. Isoxazole derivatives have been useful as a versatile
building block for the synthesis of organic compounds. Isoxazoles
can be converted into various important synthetic units like β-
hydroxy ketones [1-7], γ-amino alcohols [8,9], α,β-unsaturated
oxime [10,11] and β-hydroxy nitriles [12,13]. Along with
these, isoxazole derivatives have been used in synthetic investi-
gation as of their known biological activities and pharmaco-
logical properties like hypoglycemic effect [14], analgesic [15],
anti-inflammatory [16], antibacterial activities [17] and
anticancer activity [18]. 4,5-Diarylisoxazole derivatives also
act as potent therapeutic agents for the treatment of cancer
[19] inhibition of cyclooxygenase-2 and have analgesic and
anti-inflammatory activities [20]. These compounds are also
helpful for the treatment of angiogenesis-related diseases
including cancers, rheumatoid arthritis and psoriasis [21].
In view of the above, the present study focuses on the
synthesis of 4,5-disubstituted isoxazole derivatives from α,β-
chalcone ditosylates. A new and convenient route to synthesis
of 4,5-diarylisoxazoles from chalcone ditosylates had also been
reported [22]. α,β-Chalcone ditosylates reacts with hydroxyl-
EXPERIMENTAL
Melting points of the synthesized compounds were deter-
mined by using open capillary method and are uncorrected.
TLC was performed to check the purity and to monitor the reac-
tion. The IR spectra were recorded on Shimadzu FTIR 8400
spectrophotometer using KBr pallets. 1H NMR spectra were
obtained in CDCl3 on a Bruker Spectrometer at 400 Hz. The
chemical shifts are reported in ppm (δ) in relation to tetramethyl-
silane (TMS) as an internal standard. Coupling constants (J)
are expressed in Hertz (Hz). All the chemicals and reagents
used were purchased from Merck and Sigma Aldrich.
Ethics statements: The protocol was approved by the
Institutional Animals Ethics Committee of the M.M. College
of Pharmacy (MMCP-IAEC-6 dated: 04/08/2018). All the
pharmacological activities were carried out as per CPCSEA
This is an open access journal, and articles are distributed under the terms of the Attribution 4.0 International (CC BY 4.0) License. This
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1848 Pragi et al.
Asian J. Chem.
(Committee for the purpose of control and supervision of
experiments on animals) norms.
7.02 (d, 2H, ArH, J = 8.1 Hz); 7.13 (d, 2H, ArH, J = 8.1 Hz);
6.54-6.87 (m, 7H, ArH); 8.28 (s, 1H, C3-isoxazole proton);
2.35 (s, 1H, OH). Elementalanalysis:calcd. (found)for C19H13NO2;
C 79.43 (79.42), H 4.56 (4.55).
General procedure for the synthesis of 4,5-disubstituted
isoxazoles from α,β-chalcone ditosylates: A mixture of
chalcone ditosylate (1a; 0.550 g,0.001 mol), hydroxylamine
hydrochloride (0.138 g, 0.002 mol) and sodium acetate (0.164 g,
0.002 mol) in ethanol (25 mL) was refluxed for approximately
3 h. The reaction mixture was poured on the ice-cold water.
The resulting mixture was then extracted with dichloromethane
(3 × 50 mL) and the organic extract obtained was dried over
anhydrous sodium sulphate and filtered. Evaporation of dichl-
oromethane in vacuo and the crude product obtained was purified
by column chromatography on silica gel (100-200 mesh) using
petroleum ether-ethylacetate as eluent to give pure isoxazole.
5-(Naphthalene-3-yl)-4-phenylisoxazole (V1D1I1):Yield:
65 %, m.p.: 134-136 ºC. IR (νmax, KBr, cm-1): Peak absent in CO
region; 1H NMR (CDCl3, 300 MHz) δ ppm: 7.32 (m, 5H,ArH);
8.29 (s, 1H, C3-isoxazole proton); 6.60-6.98 (m, 7H, ArH).
Elemental analysis: calcd. (found) for C19H13NO: C 84.11
(84.10), H 4.83 (4.84).
5-(Naphthalene-3-yl)-4-(4-chlorophenyl)isoxazole
(V2D2I2):Yield: 69 %, m.p.: 117-119 ºC. IR (νmax, KBr, cm-1):
Peak absent in CO region; 1H NMR (CDCl3, 300 MHz) δ ppm:
7.03 (d, 2H, ArH, J = 8.1 Hz); 7.23 (d, 2H, ArH, J = 8.1 Hz);
7.81 (s, 1H, C3-pyrazole proton); 6.60-6.98 (m, 7H, ArH).
Elemental analysis: calcd. (found) for C19H12NOCl: C 74.64
(74.62), H 3.96 (H 3.97).
5-(Naphthalene-3-yl)-4-(4-nitrophenyl)isoxazole
(V3D3I3):Yield: 78 %, m.p.: 100-102 ºC. IR (νmax, KBr, cm-1):
Peak absent in CO region; 1H NMR (CDCl3, 300 MHz) δ ppm:
6.89 (d, 2H, ArH, J = 8.1 Hz); 7.21 (d, 2H, ArH, J = 8.1 Hz);
6.58-6.81 (m, 7H, ArH); 8.25 (s, 1H, C3-isoxazole proton).
Elementalanalysis:calcd. (found) for C19H12N2O3: C 72.15 (72.13),
H 3.82 (3.83).
5-(Naphthalene-3-yl)-4-(4-methoxyphenyl)isoxazole
(V4D4I4): Yield: 70%, m.p.: 97-99 ºC. IR (νmax, KBr, cm-1):
Peak absent in CO region; 1H NMR (CDCl3, 300 MHz) δ ppm:
6.91 (d, 2H, ArH, J = 8.1 Hz); 7.26 (d, 2H, ArH, J = 8.1 Hz);
6.60-6.98 (m, 7H, ArH); 8.27 (s, 1H, C3-isoxazole proton);
3.81 (s, 3H, OCH3). Elemental analysis: calcd. (found) for
C20H15NO2: C 79.72 (79.71), H 5.02 (5.02).
5-(Naphthalene-3-yl)-4-(4-fluorophenyl)isoxazole
(V5D5I5):Yield: 69 %, m.p.: 108-110 ºC. IR (νmax, KBr, cm-1):
Peak absent in CO region; 1H NMR (CDCl3, 300 MHz) δ ppm:
7.02 (d, 2H, ArH, J = 8.1 Hz); 7.21 (d, 2H, ArH, J = 8.1 Hz);
6.58-6.89 (m, 7H, ArH); 8.27 (s, 1H, C3-isoxazole proton).
Elementalanalysis:calcd. (found)for C19H12NOF: C 78.88 (78.87),
H 4.18 (4.18).
5-(Naphthalene-3-yl)-4-p-tolylisoxazole (V6D6I6):
Yield: 73 %, m.p.: 127-128 ºC. IR (νmax, KBr, cm-1): Peak absent
in CO region; 1H NMR (CDCl3, 300 MHz) δ ppm: 7.14 (d, 2H,
ArH, J = 8.1 Hz); 7.26 (d, 2H,ArH, J = 8.1 Hz); 6.60-6.98 (m,
7H,ArH); 2.33 (s, 3H, CH3); 8.27 (s, 1H, C3-isoxazole proton).
Elemental analysis: calcd. (found) for C20H15NO: C 84.19 (84.18),
H 5.30 (5.30).
5-(Naphthalene-3-yl)-4-(4-hydroxyphenyl)isoxazole
(V7D7I7):Yield: 71 %, m.p.: 122-124 ºC. IR (νmax, KBr, cm-1):
Peak absent in CO region; 1H NMR (CDCl3, 300 MHz) δ ppm:
in vitroAntioxidant activity: The antioxidant activity of
the compounds were determined by using DPPH (1,1-
diphenyl-2-picrylhydrazyl) free radical scavenging method.
The given test compound was mixed with 95 % methanol to
make a final stock solution of concentration 100 µg/mL. From
the stock solution different solutions of concentration 10, 20,
40, 60 and 100 µg/mL were prepared. Ascorbic acid was used
as a standard and various concentrations of ascorbic acid were
prepared as of the test compound. Final mixture consisting of
1 mL of 0.3 mmol DPPH methanol solution was added to 2.5
mL of sample solution of different concentrations and allowed
to react at room temperature.After 15 min of incubation period
at 37 ºC, absorbance was calculated at 517 nm. Control reading
was also observed without the test compound.
Acontrol − Atest compound
Scavenging (%) =
×100
Acontrol
in vivoAnti-inflammatory activity: Carrageenan-induced
paw edema method was used for the determination of anti-
inflammatory activities of the compounds. Adult male rats (~
250 g) were used to evaluate anti-inflammatory activity.Animals
were divided into ten groups. Each group consists of six animals.
The different groups of rats were pre-treated with their respec-
tive doses. After 1 h, oedema was induced by administration
of 0.1 mL of 1 % carrageenan suspension into sub-plantar
region of left hind paw of each rat and then paw volume was
measured by using Plethysmometer (Laboratory enterprises,
Nasik) at 0, 1, 2, 3, 4 h. Mean SEM for treated and control
animals was calculated and compared for each time interval
and statistically analyzed. The details of the groups are as
follows:
Group I:
Group II:
Normal control
Inflammation control group which received
vehicle (0.25 % carboxymethylcellulose)
Group III: Standard group treated with (standard)
diclofenac sodium (100 mg/kg p.o.)
Group IV: Inflammation + V1D1I1 (100 mg/kg p.o.)
Group V:
Inflammation + V2D2I2 (100 mg/kg p.o.)
Group VI: Inflammation + V3D3I3 (100 mg/kg p.o.)
Group VII: Inflammation + V4D4I4 (100 mg/kg p.o.)
Group VIII: Inflammation + V5D5I5 (100 mg/kg p.o.)
Group IX: Inflammation + V6D6I6 (100 mg/kg p.o.)
Group X:
Inflammation + V7D7I7 (100 mg/kg p.o.)
Diclofenac sodium (20 mg/kg) was used as a standard
drug. The adult male rats were fasted overnight with access to
water. The synthesized compounds were given at the dose of
150 mg/kg and were administered through oral route. A 1 %
saline suspension of carrageenan was prepared. A 0.05 mL of
this suspension was injected into the planter tissue of left hind
paw of rat to induce edema. For control, the animals were injected
with equal volume of saline. In order to measure the paw volume
of rats Plethysmograph was used.

Vol. 31, No. 8 (2019)
Chalcone Ditosylates as Potent Precursor for Synthesis of Some 4,5-Disubstituted Isoxazoles 1849
activity results are given in Table-2. The compoundsV4D4I4
and V7D7I7 showed remarkable anti-inflammatory activity.
RESULTS AND DISCUSSION
Various derivatives of α,β-chalcone ditosylates were synth-
esized by the reaction of chalcone with (hydroxyl(tosyloxy)-
iodo-benzene, HTIB) by using Koser′s method. These chalcone
ditosylates were treated with hydroxylamine hydrochloride
to give different 4,5-disubstituted isoxazoles (Scheme-I). The
mechanism of conversion of ditosylates to 4,5-disubstituted
isoxazoles involves 1,2-aryl migrations.All the substrates reacted
in the same manner and gave good yield in the range 65-78 %.
The compounds were purified by recrystallization from ethanol
and dried under vacuum. The synthesized compounds were
characterized by IR, 1H NMR and elemental analysis.
The antioxidant activity results are given in Table-1. All
the synthesized compounds were found to be less potent than
the standard (ascorbic acid). However, the compounds V5D5I5
and V7D7I7 exhibited moderate antioxidant activity in
comparison to the standard. Similarly, the anti-inflammatory
Conclusion
Various 4,5-disubstituted isoxazoles were prepared from
the reaction of chalcone ditosylates and hydroxylamine
hydrochloride. All the compounds were characterized by IR,
NMR and elemental analysis. The IR spectrum of the product
showed the absence of a peak at 1680 cm-1 arising from the
carbonyl group of chalcone ditosylate. The 1H NMR spectrum
showed a sharp singlet at δ = 8.2 ppm, corresponding to a
single proton corresponding to that of C(3)-H of the isoxazole
ring. Antioxidant property was evaluated by using DPPH free
radical scavenging activity. The compounds V5D5I5 and
V7D7I7 exhibited moderate antioxidant activity as compared
with the standard. Synthesized isoxazoles were tested for in
vivo anti-inflammatory activity and the compounds V4D4I4 and
V7D7I7 showed good activity when compared to the standard.
N
O
O
OTs
O
HTIB
NH2.NH2.HCl
Ar
Ar'
Ar
Ar
Ar'
Ar'
Chalcone
OTs
4,5-disubstituted isoxazole
Chalcone ditosylate
Compound No. V1D1I1 V2D2I2
V3D3I3
V4D4I4
C10H7
V5D5I5
V6D6I6
C10H7
V7D7I7
Ar
C10H7
C10H7
C10H7
C10H7
C10H7
Ar'
C6H5
4-ClC6H4 4-NO2C6H4 4-MeOC6H4 4-FC6H4
4-MeC6H4 4-OHC6H4
Scheme-I: Synthetic sequence of 4,5-disubstituted isoxazoles
TABLE-1
ANTIOXIDANT ACTIVITY OF THE 4,5 DISUBSTITUTED ISOXAZOLES BY USING DPPH FREE RADICAL SCAVENGING METHOD
Inhibition (%)
Antioxidant
IC50 value
Compound
10 µg/mL
2.48
1.45
1.76
23.6
25.7
8.73
21.05
48.51
20 µg/mL
6.89
7.97
40 µg/mL
13.88
12.55
16.80
39.63
44.77
21.57
44.80
69.70
60 µg/mL
18.34
16.98
18.65
42.66
52.98
31.09
51.93
80.44
100 µg/mL
22.78
20.39
21.09
51.75
63.32
36.98
60.20
92.46
V1D1I1
V2D2I2
V3D3I3
V4D4I4
V5D5I5
214.14
240.57
211.03
83.43
59.30
131.70
65.46
1.94
2.09
31.92
37.32
12.12
31.73
60.90
V6D6I6
V7D7I7
Ascorbic acid (Standard)
TABLE-2
ANTI-INFLAMMATORY ACTIVITY OF 4,5-DISUBSTITUTED ISOXAZOLE DERIVATIVES
Paw volume (mm) after time (h)
Treatment group
0 h
1 h
2 h
3 h
4 h
V1D1I1
V2D2I2
V3D3I3
V4D4I4
V5D5I5
0.80 0.059
0.85 0.085
0.99 0.038
0.76 0.045
0.91 0.074
0.86 0.022
0.91 0.067
0.81 0.026
0.97 0.028
0.88 0.013
1.04 0.082
1.13 0.071
1.17 0.077
0.80 0.034
1.10 0.055
1.02 0.037
1.08 0.036
0.81 0.025
1.15 0.066
0.96 0.012
1.15 0.057
1.22 0.041
1.24 0.037
0.82 0.031
1.20 0.055
1.11 0.050
1.13 0.081
0.82 0.017
1.25 0.043
0.83 0.011
1.24 0.043
1.30 0.035
1.31 0.015
0.83 0.021
1.29 0.099
1.21 0.066
1.14 0.062
0.82 0.019
1.30 0.042
0.82 0.014
1.29 0.014
1.36 0.058
1.39 0.039
0.86 0.045
1.31 0.044
1.25 0.030
1.12 0.083
0.81 0.023
1.32 0.054
0.78 0.015
V6D6I6
V7D7I7
Control
Infalmmatory control
Diclofenac
Values are expressed as mean SEM (standard error mean).
Values are calculated as compared to control using one way ANOVA followed by Dunnet’s test.

1850 Pragi et al.
CONFLICT OF INTEREST
Asian J. Chem.
13. A.Yashiro,Y. Nishida, K. Kobayashi and M. Ohno, Synlett, 361 (2000);
https://doi.org/10.1055/s-2000-6548.
14. P. Conti, C. Dallanoce, M. De Amici, C. De Micheli and K.-N. Klotz,
Bioorg. Med. Chem., 6, 401 (1998);
The authors declare that there is no conflict of interests
regarding the publication of this article.
https://doi.org/10.1016/S0968-0896(97)10051-7.
15. A. Mishra, S.K. Jain and J.G.Asthana, Orient. J. Chem., 14, 151 (1998).
16. D.H. Ko, M.F. Maponya, M.A. Khalil, E.T. Oriaku and Z. You Lee, J.
Med. Chem. Res., 8, 313 (1998).
17. Y.Y. Kang, K.J. Shin, K.H. Yoo, K.J. Seo, C.Y. Hong, C.S. Lee, S.Y.
Park, D.J. Kim and S.W. Park, Bioorg. Med. Chem. Lett., 10, 95 (2000);
https://doi.org/10.1016/S0960-894X(99)00646-0.
18. S. Srivastava, L.K. Bajpai, S. Batra, A.P. Bhaduri, J.P. Maikhuri, G.
Gupta and J.D. Dhar,, Bioorg. Med. Chem., 7, 2607 (1999);
https://doi.org/10.1016/S0968-0896(99)00188-1.
19. P.A. Brough,W.Aherne, X. Barril, J. Borgognoni, K. Boxall, J.E. Cansfield,
K.-M.J. Cheung, I. Collins, N.G.M. Davies, M.J. Drysdale, B. Dymock,
S.A. Eccles, H. Finch, A. Fink, A. Hayes, R. Howes, R.E. Hubbard, K.
James, A.M. Jordan, A. Lockie, V. Martins, A. Massey, T.P. Matthews,
E. McDonald, C.J. Northfield, L.H. Pearl, C. Prodromou, S. Ray, F.I.
Raynaud, S.D. Roughley, S.Y. Sharp, A. Surgenor, D.L. Walmsley, P.
Webb, M. Wood, P. Workman and L. Wright, J. Med. Chem., 51, 196
(2008);
https://doi.org/10.1021/jm701018h.
20. A.G. Habeeb, P.N. Praveen Rao and E.E. Knaus, J. Med. Chem., 44,
2921 (2001);
https://doi.org/10.1021/jm0101287.
21. B.M. Kwon, K.H. Son, D.C. Han, S.K. Lee, K.D. Shin, S.B. Jeon and
J.H. Oh, US Patent 0131036 (2005).
22. R. Kamal, D. Sharma, D. Wadhwa and O. Prakash, Synlett., 93 (2012);
https://doi.org/10.1055/s-0031-1290109.
23. L. Rebrovic and G.F. Koser, J. Org. Chem., 49, 2462 (1984);
https://doi.org/10.1021/jo00187a032.
REFERENCES
1. A.P. Kozikowski and P.D. Stein, J. Am. Chem. Soc., 104, 4023 (1982);
https://doi.org/10.1021/ja00378a049.
2. D.P. Curran, J. Am. Chem. Soc., 105, 5826 (1983);
https://doi.org/10.1021/ja00356a021.
3. B.H. Kim,Y.J. Chung and E.J. Ryu, Tetrahedron Lett., 34, 8465 (1993);
https://doi.org/10.1016/S0040-4039(00)61360-6.
4. S.H. Andersen, K.K. Sharma and K.B.G. Torssell, Tetrahedron, 39,
2241 (1983);
https://doi.org/10.1016/S0040-4020(01)91946-5.
5. P.G. Baraldi, A. Barco, S. Benetti, S. Manfredini and D. Simoni,
Synthesis, 276 (1987);
https://doi.org/10.1055/s-1987-27915.
6. J.W. Bode and E.M. Carreira, Org. Lett., 3, 1587 (2001);
https://doi.org/10.1021/ol015885d.
7. A.P. Kozikowski and M.Adamczyk, Tetrahedron Lett., 23, 3123 (1982);
https://doi.org/10.1016/S0040-4039(00)88575-5.
8. A.P. Kozikowski and Y.Y. Chen, J. Org. Chem., 46, 5248 (1981);
https://doi.org/10.1021/jo00338a049.
9. J.W. Bode and E.M. Carreira, Tetrahedron Lett., 23, 4777 (1982);
https://doi.org/10.1016/S0040-4039(00)85711-1.
10. V. Jager and H. Grund, Angew. Chem. Int. Ed. Engl., 15, 50 (1976);
https://doi.org/10.1002/anie.197600501.
11. S.Y. Lee, B.S. Lee, C.W. Lee and D.Y. Oh, J. Org. Chem., 65, 256
(2000);
https://doi.org/10.1021/jo991261y.
12. G.W. Moersch, E.L. Wittle and W.A. Neuklis, J. Org. Chem., 32, 1387
(1967);
https://doi.org/10.1021/jo01280a023.