Synthesis and antimicrobial activities of some isoxazolyl thiazolyl pyrazoles

Article abstract of DOI:10.1007/s00044-011-9859-y

A series of isoxazolyl thiazolyl pyrazoles 5a-d was synthesized by multi-step process, starting from 3-Acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (dehydroacetic acid, DHAA) 1. DHAA 1 was easily converted to thiosemicarbazone 2 which on reaction with a-βromo

Full text of DOI:10.1007/s00044-011-9859-y

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2012) 21:3541–3548
DOI 10.1007/s00044-011-9859-y
ORIGINAL RESEARCH
Synthesis and antimicrobial activities of some isoxazolyl thiazolyl
pyrazoles
•
•
•
Satbir Mor Rajni Mohil Devinder Kumar
Munish Ahuja
Received: 30 April 2011 / Accepted: 31 October 2011 / Published online: 19 November 2011
Ó Springer Science+Business Media, LLC 2011
Abstract A series of isoxazolyl thiazolyl pyrazoles 5a–d
was synthesized by multi-step process, starting from
3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (dehydroacetic
acid, DHAA) 1. DHAA 1 was easily converted to thio-
semicarbazone 2 which on reaction with a-bromoketones
yielded thiazolyl hydrazones 3. Refluxing 3 in ethanol-
acetic acid furnished 1-(5-hydroxy-3-methyl-1-substituted
pyrazol-4-yl)-1,3-butanediones 4. Finally, the title com-
pounds 5a–d were synthesized from 4 on treatment with
hydroxylamine. The in vitro antimicrobial activity of
compounds 3a–d, 4a–d and 5a–d were tested. Most of the
synthesized compounds exhibited significant antibacterial
and antifungal activities.
properties such as antipyretic, analgesic and anti-inflam-
matory (Menozzi et al., 2000; Turan-Zitouni et al., 2001;
Palomer et al., 2002; Bekhit et al., 2008), antiparasitic
(Rathelot et al., 2002; Kumar et al., 2006), antitubercular
(Kaymakci oglu and Rollas 2002; Dixit et al., 2006),
anticonvulsant (Kucukguzel et al., 2000), antimicrobial
(El-Gaby et al., 2000; Baraldi et al., 2002; Akbas et al.,
2005), antiviral (Larsen et al.,1999), anticancer (Poreba
et al., 2001; Ishida et al., 2002; Witherington et al., 2003;
Rostom et al., 2003; Park et al., 2005), herbicidal (Liu
et al., 2007), etc. Likewise, thiazole nucleus present in a
number of different types of compounds has been found to
be associated with different types of pharmacological
properties like anti-inflammatory (Holla et al., 2003;
Venugopala and Jayashree, 2003; Pattan et al., 2007; Rostom
et al., 2009), antitumor (El-Subbagh et al., 1999; Ramla
et al., 2006), antifungal (Chimenti et al., 2011), antihy-
pertensive (William et al., 1992), anti-HIV (Frank et al.,
1995), etc. Antimicrobial activities of some substituted
thiazoles are well established because it possess (S–C=N)
toxophoric unit in the ring. Further, isoxazoles possess
analgesic, anti-inflammatory, antimicrobial and other
pharmacological activities (Habeeb et al., 2001; Velikor-
odov and Sukhenkol, 2003; Panda et al., 2009; Madhavi
et al., 2010), etc. Numerous biological properties are pos-
sessed by the molecules in which both pyrazole and thia-
zole moieties are present together (Bekhit et al., 2003;
Rostom, 2006). Similarly, the compounds containing pyr-
azole and isoxazole moieties have been shown to exhibit
antihyperglycemic, analgesic, anti-inflammatory, antipy-
retic antibacterial, antiviral, antitumor, antifungal and
antidepressant activities (Sugiura et al., 1977; Jungheim,
1989; Xue et al., 1998; Kang et al., 2000). Furthermore,
various types of pharmacological properties are exhibited
by the molecules containing isoxazole and thiazole
Keywords Isoxazole ꢀ Thiazole ꢀ Pyrazole ꢀ
Antibacterial ꢀ Antifungal
Introduction
The designing of new types of polyheterocyclic compounds
along with the refining of procedures for synthesis is an
urgent target of the modern heterocyclic chemistry.
Amongst the five-membered heterocyclic compounds,
much interest has been focused on the pyrazole nucleus
which is known to possess a broad spectrum of biological
S. Mor (&) ꢀ R. Mohil ꢀ D. Kumar
Department of Chemistry, Guru Jambheshwar University
of Science and Technology, Hisar 125001, Haryana, India
e-mail: satbir_mor@yahoo.co.in
M. Ahuja
Department of Pharmaceutical Sciences, Guru Jambheshwar
University of Science and Technology, Hisar 125001,
Haryana, India
123

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Med Chem Res (2012) 21:3541–3548
OH NNHCSNH2
OH
O
O
pharmacores existing in the same molecule (Rajanarendar
et al., 2010). It was, therefore, thought worthwhile to
undertake the synthesis of some pyrazole derivatives pos-
sessing a thiazole moiety at postion-1 and isoxazole moiety
at position-4 to frame potential biological molecules.
Keeping in view of growing interest in the reactions of
significance available in literature and numerous biological
properties possessed by them, we herein report a detailed
account of results of our investigations on the multistep
synthesis, characterization and antimicrobial activities of
3a–d, 4a–d and the title compounds, 3-methyl-4-(3-meth-
ylisoxazol-5-yl)-1-(4-substituted phenylthiazol-2-yl)-1H-
pyrazol-5-ol derivatives 5a–d.
NH2CSNHNH2 / EtOH
CH3
CH3
Reflux
H3C
O
O
H3C
O
1
2
R
RCOCH2Br
Reflux
NaOAc / EtOH
N
S
R
N
N
N
NH
S
EtOH / AcOH
Reflux
OH
N
O
CH3
HO
HO
CH3
H3C
O
O
CH3
3
4
NH2OH.HCl
EtOH / AcOH
Reflux
Results and discussion
3,4,5
R
H3C
Chemistry
a
b
c
d
Ph
N
(p)-CH3-Ph
(p)-OCH3-Ph
(p)-Cl-Ph
O
N
N
N
R
The title compounds 1-(4-(phenyl/4-substituted phenyl)
thiazol-2-yl)-3-methyl-4-(3-methylisoxazol-5-yl)-1H-pyra-
zol-5-ol 5a–d were synthesized as illustrated in Scheme 1.
The thiosemicarbazones 2 were prepared in high yields
upon treatment of 2-acetyl-4-hydroxy-6-methyl-2H-pyran-
2-one (dehydroacetic acid, DHAA) 1 with thiosemicarba-
zide in equimolar quantities which were smoothly con-
verted into the corresponding hydrazones 3 upon reaction
with different 4-substituted phenacyl bromides in the
presence of sodium acetate/ethanol. The hydrazones 3 thus
obtained underwent rearrangement in ethanol-acetic acid
mixture to afford the key intermediate 1-(5-hydroxy-3-
H3C
HO
S
5
Scheme 1 Synthesis of 1-(4-(4-substituted-phenyl)thiazol-2-yl)-3-
methyl-4-(3-methylisoxazol-5-yl)-1H-pyrazol-5-ols 5
2.20–2.29 and d 2.50–2.62, respectively, and one signal in
each case due to CH2 and oleifinic-H in the region at d
4.04–4.06 and 6.67–6.69 (exchangeable with D2O),
respectively. The singlet observed in the region at d
7.29–7.62 was assigned to thiazole ring-H. The ratio of
aromatic to aliphatic protons was found satisfactory. In 13
C
methyl-1-substituted pyrazol-4-yl)-1,3-butanediones
4
NMR spectra of 4 displayed peaks in the regions at d
188.48–188.87, 186.94–187.44 and 183.02–183.24 due to
carbonyl carbons. All these characteristic features corrob-
orate existence of keto-enol tautomerism in 4 (Fig. 1).
Further, the % ratio of keto/enol forms of 4 (4A:4B) were
which on subsequent treatment with hydroxylamine
hydrochloride furnished 1-(4-(phenyl/4-substitutedphenyl)
thiazol-2-yl)-3-methyl-4-(3-methylisoxazol-5-yl)-1H-pyra-
zol-5-ol 5a–d.
1
The structures of all the products were established on the
basis of elemental analyses, IR, NMR (1H and 13C) and
mass spectral data. The hydrazones 3 exhibited medium
intensity NH, OH broad stretching bands in the region
3,600–3,100 cm-1 and strong C=O stretching bands in the
region 1,699–1,684 cm-1 in their IR spectra. The 1H NMR
(400 MHz) spectra of these hydrazones displayed singlet in
the region at d 5.89–6.05 due to pyrone ring-H and singlet
in the region at d 6.62–6.85 due to thiazole ring-H which
are in agreement with the results as reported in the litera-
ture [Singh et al., 1993]. The IR spectra of 4 exhibited
absorption bands in the regions 3,600–3,100 and
1,718–1,706 and 1,646–1,633 cm-1 assigned to OH and
calculated from H NMR (400 MHz) spectral data, and
were found as 4a (35:65), 4b (25:75), 4c (50:50) and 4d
R
R
N
N
S
S
N
N
N
N
CH3
CH3
HO
HO
HO
O
O
O
CH3
CH3
1
4A
4B
CO functionalities, respectively. The H NMR (400 MHz)
spectra of 4 displayed four signals due to each of the CH3
groups present in pyrazolyl moiety in enol and keto forms,
in the regions at d 2.04–2.07 and 2.54–2.66 and d
Fig. 1 Keto-enol tautomeric forms of 1-(1-(4-(4-substituted-
phenyl)thiazol-2-yl)-5-hydroxy-3-methyl-1H-pyrazol-4-yl)butane-1,
3-diones 4
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Med Chem Res (2012) 21:3541–3548
3543
(37:63). A careful analysis of spectral data shows an
interesting trend that 4a, 4b and 4d exist predominantly in
enolic form but in 4c keto-enol forms are in equal amounts.
The title compounds 1-(4-(phenyl/4-substituted phenyl)
thiazol-2-yl)-3-methyl-4-(3-methylisoxazol-5-yl)-1H-pyra-
zol-5-ol 5a–d exhibited the characteristics broad absorp-
tion bands of medium intensity in the region 3,432–
3,204 cm-1 due to OH of pyrazole moiety in their IR
easily available. B. subtilis may contaminate food and
produces the proteolytic enzyme subtilisin and is respon-
sible for causing ropiness. S. aureus is a common cause of
boils, sties and skin infections and may cause serious
infections in debilitated persons. E. coli can cause gastro-
enteritis, urinary tract infections, and neonatal meningitis.
The fungus C. albicans is often a benign member of the
mucosal flora; however, it commonly causes mucosal dis-
ease with substantial morbidity and in vulnerable patients it
causes life-threatening bloodstream infections. A. niger is
not only a xerophilic fungi, but is also a thermo-tolerant
organism. Double strength nutrient broth and Sabouraud
dextrose broth were employed for bacterial and fungal
growth, respectively. The pMICs (negative logarithm of
minimum inhibitory concentrations) were recorded as the
minimum concentration of a compound that inhibits the
growth of tested microorganisms. pMICs were determined
by means of standard serial dilution method. The pMIC
values are presented in Table 2. Most of the synthesized
compounds showed good antibacterial activity with pMICs
ranging from 1.435 to 1.778. The new title compounds
isoxazolyl thiazolyl pyrazoles 5a–d and their precursors
3a–d and 4a–d were successfully synthesized. The syn-
thesized compounds were found to exhibit moderate
1
spectra. The H NMR (400 MHz) spectra of 5a–d showed
a singlet in the region d 6.51–6.55 due to isoxazole-H and
another singlet in the region d 7.25–7.71 assigned to thia-
zole-H. The mass spectral studies and elemental analysis
results were found satisfactory. Physical and chemical data
of the compounds 3a–d, 4a–d and 5a–d are detailed in
Table 1.
Antimicrobial activity
All the newly synthesized compounds has been assayed for
their in vitro antibacterial activity against Gram-positive
Bacillus subtilis, Staphylococcus aureus and Gram-nega-
tive Escherichia coli and in vitro antifungal activity against
Candida albicans and Aspergillus niger. The bacterial and
fungal strains selected for this study are most common and
Table 1 Physical and analytical data of compounds 3a–d, 4a–d and 5a–d
Compds
R
H
Reaction time (min) Yield % Melting point °C
Molecular formula Found % (Calculated) C H N
3a
30
76
71
73
67
57
59
64
61
68
63
74
69
188–190 Lit. mp 190–191 C17H15N3O3S
60.20
4.22
12.69
(59.81)
60.34
(4.43)
4.71
(12.31)
12.08
3b
3c
3d
4a
4b
4c
4d
5a
5b
5c
5d
CH3
25
204–206
C18H17N3O3S
C18H17N3O4S
(60.83)
57.94
(4.82)
4.96
(11.82)
11.59
OCH3 30
189–190
(58.21)
54.72
(4.61)
3.83
(11.31)
11.26
Cl
35
178–180
C
C
17H14ClN3O3S
17H15N3O3S
(54.33)
60.15
(3.75)
4.27
(11.18)
12.43
H
120
120
142–144 Lit. mp 145
110–112
(59.81)
61.14
(4.43)
5.08
(12.31)
12.23
CH3
C18H17N3O3S
C18H17N3O4S
(60.83)
58.53
(4.82)
4.93
(11.82)
10.96
OCH3 125
158–160
(58.21)
54.56
(4.61)
3.61
(11.31)
11.47
Cl
125
115
125
120–122
C
C
17H14ClN3O3S
17H14N4O2S
(54.33)
60.28
(3.75)
4.37
(11.18)
16.58
H
208–210
(60.34)
61.72
(4.17)
4.81
(16.56)
15.59
CH3
220–222
C18H16N4O2S
C18H16N4O3S
(61.35)
59.01
(4.58)
4.10
(15.90)
15.07
OCH3 110
232–234
(58.68)
55.13
(4.38)
3.16
(15.21)
15.16
Cl
125
258–260
C17H13ClN4O2S
(54.77)
(3.51)
(15.03)
123

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Med Chem Res (2012) 21:3541–3548
The graphical data of antimicrobial activities of all the
synthesized compounds is depicted in Fig. 2.
Table 2 In vitro antimicrobial activity (pMIC) of compounds 3a–d,
4a–d and 5a–d
Compounds Antibacterial activity
Antifungal activity
B. subtilis S. aureus E. coli C. albicans A. niger
Conclusion
3a
3b
3c
3d
4a
4b
4c
4d
5a
5b
5c
5d
1.435
1.453
1.171
1.478
1.435
1.453
1.472
1.477
1.733
1.750
1.771
1.775
1.737
1.453
1.472
1.478
1.435
1.754
1.472
1.778
1.733
1.750
1.771
2.077
2.698
–
1.435 1.435
1.453 1.152
1.472 1.171
1.478 1.478
1.435 1.435
1.754 1.453
1.472 1.472
1.477 1.477
1.733 1.432
1.750 1.449
1.470 1.470
1.775 1.477
1.435
1.435
1.472
1.478
1.435
1.453
1.472
1.477
1.432
1.750
1.771
1.474
–
The synthesized compounds were found to exhibit mod-
erate antibacterial activity, e.g. 5a–d against B. subtilis; 3a,
4b, 4d, 5a–c against S. aureus and 4b, 5a, 5b, 5d against E.
coli, whereas the compounds 5b, 5c were found to be
active fungicidal agent against A. niger. However, amongst
the newly synthesized title compounds, 1-(4-(4-chloro-
phenyl)thiazol-2-yl)-3-methyl-4-(3-methylisoxazol-5-yl)-
1H-pyrazol-5-ol 5d was found to exhibit the promising
antibacterial activity against S. aureus.
Experimental
Norfloxacin 2.698
Fluconazole
2.698
–
–
–
3.000
3.000
Melting points were determined in open capillaries and are
uncorrected. The IR absorption spectra were scanned on
Perkin Elmer Spectrum, BX II FTIR spectrometer using
potassium bromide (KBr) pellets and the wave numbers
antibacterial activity, e.g. 5a–d against B. subtilis; 3a, 4b,
4d, 5a–c against S. aureus and 4b, 5a, 5b, 5d against
E. coli, whereas the compounds 5b, 5c were found to be
active fungicidal agent against A. niger. However, amongst
the newly synthesized title compounds, 1-(4-(4-chloro-
phenyl)thiazol-2-yl)-3-methyl-4-(3-methylisoxazol-5-yl)-1H-
pyrazol-5-ol 5d was found to exhibit the promising anti-
bacterial activity against S. aureus (pMIC = 2.077, in
comparison to the standard reference norfloxacin, pMIC =
2.698). Almost all the compounds showed moderate level
of antifungal activity with pMICs ranging from 1.435 to
1.478 in comparison to the standard reference fluconazole
(pMIC = 3.000). However, 5b (pMIC = 1.750) and 5c
(pMIC = 1.771) exhibited good fungicidal activity. The
results of antimicrobial activity illustrate that the presence
of electron donating groups, CH3 and OCH3 on the phenyl
ring, in compounds 3–5 increases the antibacterial as well
as antifungal activities. Further, the presence of electron
withdrawing group, Cl on the phenyl ring, in compounds
5d enhances the antibacterial activity to a greater extent.
1
were given in cm-1. The H NMR and 13C NMR spectra
were recorded on Bruker Avance II 400 spectrometer at
400 and 100 MHz, respectively, in deuteriochloroform or
deuteriochloroform ? dimethyl sulfoxide-d6 or dimethyl
sulfoxide-d6. The chemical shifts are reported in parts per
million (d ppm) using tetramethylsilane (TMS) as an
internal standard. Coupling constants J are valued in Hertz
(Hz). Mass spectra were recorded on Waters Micromass
Q-Tof Micro (ESI) spectrometer. Elemental analysis was
carried out using Vario Micro Cube Elementar CHNS
analyser. Analytical results for C, H and N were within
0.4% of the theoretical values. The purities of the com-
pounds were checked by thin layer chromatography (TLC)
using readymade silica gel (SIL G/UV254, ALUGRAM)
plates. The spots were visualized under ultraviolet (UV)
lamp. Solvents were dried using standard literature proce-
dures. The thiosemicarbazones 2 were prepared by the
condensation of equimolar quantities of 2-acetyl-4-
Fig. 2 In vitro antimicrobial
activity (pMIC) of compounds
3a–d, 4a–d and 5a–d
B. subtilis
S. aureus
E. coli
3
2.5
2
1.5
1
0.5
0
C. albicans
A. niger
Compounds
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Med Chem Res (2012) 21:3541–3548
3545
hydroxy-6-methyl-2H-pyran-2-one and thiosemicarbazide
in absolute alcohol (Singh et al., 1993).
MS ES?) m/z 376.2 [M ? H]?; C17H14ClN3O3S; Calc. C
54.33, H 3.75, N 11.18; Found C 54.72, H 3.83, N 11.26.
General procedure for the synthesis of 4-hydroxy-6-
methyl-3-(1-(2-(4-substituted-phenylthiazol-2-
yl)hydrazono)ethyl)-2H-pyran-2-ones (3a–3d)
General procedure for the synthesis of 1-(1-(4-(4-
substituted-phenyl)thiazol-2-yl)-5-hydroxy -3-methyl-
1H-pyrazol-4-yl)butane-1,3-diones (4a–4d)
To a solution of 2 (2.41 g, 0.01 mol) and anhydrous
sodium acetate (0.82 g, 0.01 mol) in absolute ethanol, the
appropriate p-substituted phenacyl bromide (0.01 mol) was
added slowly with stirring. The reaction mixture was
refluxed gently for 25–35 min. The yellowish crystalline
solid thus obtained was filtered, washed with cold ethanol,
and recrystallized from dimethyl formamide and water.
Physical and analytical data are recorded in Table 1.
The hydrazone 3 (0.01 mol) was added in one lot to a hot
solution of acetic acid and refluxed for approximately 2 h.
The solid thus obtained, on cooling the reaction mixture
overnight, was filtered, washed with little cold ethanol and
crystallised from acetonitrile. Physical and analytical data
are recorded in Table 1.
1-(5-Hydroxy-3-methyl-1-(4-phenylthiazol-2-yl)-1H-
pyrazol-4-yl)butane-1,3-dione (4a)
4-Hydroxy-6-methyl-3-(1-(2-(4-phenylthiazol-2-
yl)hydrazono)ethyl)-2H-pyran-2-one (3a)
Yield 57%; mp 142–144°C (Lit. mp 145°C; Singh et al.,
1993); IR (KBr) 3,550–3,200 (OH), 1,706, 1,633 cm-1
(CO); 1H NMR (DMSO-d6) d 2.04, 2.27 (two s, 3H, CH3),
2.59, 2.62 (two s, 3H, CH3), 4.04 (s, 2H, CH2), 6.68 (s, 1H,
olefinic-H), 7.29–7.84 (m, 6H, ArH and thiazole-H); 13C
NMR (DMSO-d6) (enol ? keto forms) d 13.49, 13.71,
24.17, 30.97, 56.01, 97.76, 100.22, 103.84, 108.77, 126.41,
128.31, 128.68, 133.96, 134.05, 149.80, 149.84, 152.19,
152.70, 153.52, 159.05, 160.08, 183.13, 187.28, 188.5;
MS: (TOF MS ES?) m/z 342.2 [M ? H]?.
Yield 76%; mp 188–190°C (Lit. mp 190–191°C; Singh
et al., 1993); IR (KBr): 3,400–3,100 (NH, OH),
1,698 cm-1(CO); MS: (TOF MS ES?) m/z 342.2 [M ? H]?.
4-Hydroxy-6-methyl-3-(1-(2-(4-tolylthiazol-2-
yl)hydrazono)ethyl)-2H-pyran-2-one (3b)
Yield 71%; mp 204–206°C; IR (KBr) 3,550–3,200 (NH,
OH), 1,699 cm-1(CO); 1H NMR (DMSO-d6) d 2.16 (s, 3H,
CH3), 2.33 (s, 3H, CH3), 2.70 (s, 3H, CH3), 5.89 (s, 1H,
pyrone-H), 6.62 (s, 1H, thiazole-H), 7.23 (d, 2H, J = 8.0 Hz,
H-300,500), 7.61 (d, 2H, J = 8.08 Hz, H-200,600); MS: (TOF MS
ES?) m/z 356.1 [M ? H]?; C18H17N3O3S; Calc. C 60.83, H
4.82, N 11.82; Found C 60.34, H 4.71, N 12.08.
Hydroxy-3-methyl-1-(4-tolylthiazol-2-yl)-1H-pyrazol-4-
yl)butane-1,3-dione (4b)
Yield 59%; mp 110–112°C; IR (KBr) 3,600–3,200 (OH),
1,707, 1,646 cm-1(CO); 1H NMR (DMSO-d6) d 2.06, 2.27
(two s, 3H, CH3), 2.37, (s, 3H, CH3), 2.60, 2.64 (two s, 3H,
CH3), 4.04 (s, 2H, CH2), 6.69 (s, 1H, olefinic-H), 7.21 (d,
2H, J = 7.9 Hz, H-300, 500), 7.39 (s, 1H, thiazole-H), 7.84
(d, 2H, J = 7.9 Hz, H-200,600); 13C NMR (DMSO-d6)
(enol ? keto forms) d 13.49, 13.79, 21.34, 24.15, 30.95,
56.00, 97.73, 100.19, 103.81, 108.01, 126.33, 129.22,
129.36, 131.60, 137.49, 149.84, 149.88, 152.12, 152.71,
153.52, 159.08, 160.12, 183.24, 187.17, 188.48; MS: (TOF
MS ES?) m/z 356.1 [M ? H] ?; C18H17N3O3S; Calc. C
60.83, H 4.82, N 11.82; Found C 61.14, H 5.08, N 12.23.
4-Hydroxy-3-(1-(2-(4-(4-methoxyphenyl)thiazol-2-
yl)hydrazono)ethyl-6-methyl-2H-pyran-2-one (3c)
Yield 73%; mp 189–190°C; IR (KBr): 3,600–3,220 (NH,
1
OH), 1,687 cm-1 (CO); H NMR (DMSO-d6): d 2.08 (s,
3H, CH3), 2.69 (s, 3H, CH3), 3.84 (s, 3H, OCH3), 6.05 (s,
1H, pyrone-H), 6.69 (s, 1H, thiazole-H), 6.94 (d, 2H,
J = 8.72 Hz, H-300,500), 7.88 (d, 2H, J = 8.72 Hz,
H-200,600); MS: (TOF MS ES?) m/z 372.2 [M ? H]?;
C18H17N3O4S; Calc. C 58.21, H 4.61, N 11.31; Found C
57.94, H 4.96, N 11.59.
1-(5-Hydroxy -1-(4-(4-methoxyphenyl)thiazol-2-yl) -3-
methyl -1H-pyrazol-4-yl)butane-1,3-dione (4c)
3-(1-(2-(4-(4-Chlorophenyl)thiazol-2-yl)hydrazono)ethy)-
4-hydroxy-6-methyl-2H-pyran-2-one (3d)
Yield 64%; mp 158–160°C; IR (KBr) 3,600–3,300 (OH),
1,718, 1,646 cm-1(CO); 1H NMR (DMSO-d6) d 2.05, 2.20
(two s, 3H, CH3), 2.50, 2.54 (two s, 3H, CH3), 3.81 (s, 3H,
OCH3), 4.04 (s, 2H, CH2), 6.67 (s, 1H, olefinic-H), 7.02 (d,
J = 8.7 Hz, H-200, 600), 7.62 (s, 1H, thiazole-H), 7.93 (d,
J = 8.7 Hz, H-300,500); 13C NMR (DMSO-d6) (enol ? keto
Yield 67%; mp 178–180°C; IR (cm-1): 3,500–3,200 (NH,
1
OH), 1,684 cm-1 (CO); H NMR (DMSO-d6) d 2.20 (s,
3H, CH3), 2.63 (s, 3H, CH3), 5.89 (s, 1H, pyrone-H), 6.85
(s, 1H, thiazole-H), 7.38–7.76 (m, 4H, Ar–H) MS: (TOF
123

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Med Chem Res (2012) 21:3541–3548
forms) d 13.39, 13.76, 24.14, 30.91, 55.40, 56.41, 98.61,
100.10, 103.78, 108.88, 114.28, 123.90, 126.89, 136.71,
149.81, 149.93, 152.17, 152.87, 153.18, 159.47, 159.70,
161.51, 183.22, 186.94, 188.87; MS: (TOF MS ES?) m/
z 372.04 [M ? H] ?; C18H17N3O4S; Calc. C 58.21, H 4.61,
N 11.31; Found C 58.53, H 4.93, N 10.96.
CH3), 2.62 (s, 3H, CH3), 6.52 (s, 1H, isoxazole-H),
6.91–7.84 (m, 5H, Ar–H, thiazole-H); 13C NMR (DMSO-
d6) d 12.84, 11.41, 12.84, 21.36, 94.26, 99.31, 108.79,
126.30, 129.25, 129.39, 137.90, 147.72, 150.0, 151.37,
158.11, 159.41, 163.49; MS (TOF MS ES?) m/z 353.4
[M ? H]?; C18H16N4O2S; Calc. C 61.35, H 4.58, N 15.90;
Found C 61.72, H 4.81, N 15.59.
1-(1-(4-(4-Chlorophenyl)thiazol-2-yl)-5-hydroxy-3-methyl-
1H-pyrazol-4-yl)butane-1,3-dione (4d)
1-(4-(4-Methoxyphenyl)thiazol-2-yl)-3-methyl-4-(3-
methylisoxazol-5-yl)-1H-pyrazol-5ol (5c)
Yield 61%; mp 120–122°C; IR (KBr) 3,550–3,100 (OH),
1,717, 1,636 cm-1(CO); 1H NMR (DMSO-d6) d 2.07, 2.29
(two s, 3H, CH3), 2.62, 2.66 (two s, 3H, CH3), 4.06 (s, 2H,
CH2), 6.68 (s, 1H, olefinic-H), 7.40 (d, 2H, J = 8.4 Hz,
H-200,600), 7.45 (s, 1H, thiazole-H), 7.933 (d, J = 8.4 Hz,
H-300,500); 13C NMR (DMSO-d6) (enol ? keto forms) d
13.49, 13.69, 24.17, 30.94, 55.94, 97.75, 100.25, 103.86,
109.28, 127.80, 128.76, 132.64, 132.70, 133.58, 148.66,
Yield 74%; mp 232–234°C; IR (cm-1) 3,432 cm-1 (OH);
1H NMR (DMSO-d6) d 2.30 (s, 3H, CH3), 2.64 (s, 3H,
CH3), 3.84 (s, 3H, CH3), 6.54 (s, 1H, isoxazole-H), 6.93 (d,
2H, J = 2.84 Hz, H-300,500), 7.25 (s, 1H, thiazole-H), 7.86
(d, 2H, J = 2.84 Hz, H-200,600); 13C NMR (DMSO-d6) d
11.39, 12.83, 55.35, 94.37, 99.32, 106.71, 114.04, 126.94,
127.22, 127.62, 127.70, 147.69, 149.87, 159.46, 159.63,
163.44; MS (TOF MS ES?) m/z 369.2 [M ? H]?;
C18H16N4O3S; Calc.C 58.68, H 4.38, N 15.21; Found C
59.01, H 4.10, N 15.07.
152.32, 152.79, 153.64, 159.13, 160.15, 183.02, 187.44,
188.51; MS: (TOF MS ES?) m/z 376 [M ? H]
?
;
C17H14ClN3O3S; Calc. C 54.33, H 3.75, N 11.18; Found C
54.56, H 3.61, N 11.47.
1-(4-(4-Chlorophenyl)thiazol-2-yl)-3-methyl-4-(3-
methylisoxazol-5-yl)-1H-pyrazol-5-ol (5d)
General procedure for the synthesis of 1-(4-(4-
substituted-phenyl)thiazol-2-yl)-3-methyl-4-(3-
methylisoxazol-5-yl)-1H-pyrazol-5-ols (5a–d)
Yield 69%; mp 258–260°C; IR (KBr) 3,431 cm-1 (OH);
1H NMR (DMSO-d6) d 2.31 (s, 3H, CH3), 2.66 (s, 3H,
CH3), 6.55 (s, 1H, isoxazole-H), 7.41 (d, 2H, J = 8.4 Hz,
H-200,600)), 7.44 (s, 1H, thiazole-H), 7.94 (d, 2H,
J = 8.4 Hz, H-300, 500); 13C NMR (DMSO-d6) d 11.38,
12.84, 94.43, 99.40, 109.1, 127.76, 128.76, 132.75, 133.63,
138.9, 147.92, 148.81, 155.4, 159.51, 163.34; MS (TOF
MS ES?) m/z 373.3 [M ? H]?; C17H13ClN4O2S; Calc. C
54.77, H 3.51, N 15.03; Found C 55.13, H 3.16, N 15.16.
The solution of 4 (0.01 mol) and hydroxylamine hydro-
chloride (0.69 g, 0.01 mol) in 50 ml of ethanol and 50 ml
of acetic acid was heated at reflux for approximately 2 h.
The reaction mixture was cooled and then allowed to stand
overnight. The solid thus obtained, was collected and
recrystallised from acetonitrile. Physical and analytical
data are recorded in Table 1.
3-Methyl-4-(3-methylisoxazol-5-yl)-1-(4-phenylthiazol-2-
yl)-1H-pyrazol-5-ol (5a)
Antimicrobial activity
All the twelve newly synthesized compounds 3a–d, 4a–d
and 5a–d were screened for their in vitro antimicrobial
activity against five microorganisms, two Gram-positive
bacteria B. subtilis (MTCC 441) and S. aureus (MTCC
7443) and one Gram-negative bacteria E. coli (MTCC 42)
and two fungi C. albicans (MTCC 183) and A. niger
(MTCC 282) by serial tube dilution technique using two
solid media Double strength nutrient broth and Sabouraud
dextrose broth for bacterial and fungal growth, respec-
tively. The stock solutions (100 lg/ml) of all the test
compounds were prepared by dissolving 1 mg of the test
compound in 10 ml of dimethylsulphoxide. Norfloxacin
and fluconazole were used as reference against bacteria and
fungi, respectively. The fresh cultures were obtained by
inoculation of respective microorganism in suitable med-
ium (Double strength nutrient broth in case of bacteria and
Yield 68%; mp 208–210°C; IR (KBr) 3,204 cm-1 (OH);
1H NMR (DMSO-d6) d 2.27 (s, 3H, CH3), 2.61 (s, 3H,
CH3), 6.51 (s, 1H, isoxazole-H), 7.33–7.46 (m, 3H, Ar–H)),
7.71 (s, 1H, thiazole-H), 8.01 (d, 2H, J = 7.36 Hz,
H-200,600); 13C NMR (DMSO-d6) d 11.37, 12.92, 93.91,
99.32, 109.4, 126.45, 128.44, 128.96, 134.18, 148.09,
149.63, 152.51, 158.07, 159.42, 163.49; MS: (TOF MS
ES?) m/z 339.3 [M ? H]?; C17H14N4O2S; Calc. C 60.34,
H 4.17, N 16.56; Found C 60.28, H 4.37, N 16.58.
3-Methyl-4-(3-methylisoxazol-5-yl)-1-(4-p-tolylthiazol-2-
yl)-1H-pyrazol-5-ol (5b)
Yield 63%; mp 220–222°C; IR (KBr) 3,431 cm-1 (OH);
1H NMR (DMSO-d6) d 2.23 (s, 3H, CH3), 2.36 (s, 3H,
123

Med Chem Res (2012) 21:3541–3548
3547
Frank WB, Amanda SC, Marita HS, Richard J, Nils GJ, Christopher
LJ, Michael DK, Peter L, John MM, Noreen R, Oberg B,
Palkowitz JA, Parrish CA, Pranc J, Zhang H, Zhou XX (1995)
Phenethylthiazolethiourea (PETT) compounds, a new class of
HIV-1 reverse transcriptase inhibitors. 1. Synthesis and basic
structure-activity relationship studies of PETT analogs. J Med
Chem 38:4929–4936
Habeeb GA, Rao PNP, Kanus EE (2001) Design and synthesis of 4,5-
diphenyl-4isoxazolines: novel inhibitors of cyclooxygenase-2
with analgesic and antiinflammatory activity. J Med Chem 44:
2921–2927
Holla BS, Malini KV, Rao BS, Sarojini BK, Kumari NS (2003)
Synthesis of some new 2,4-disubstituted thiazoles as possible
antibacterial and anti-inflammatory agents. Eur J Med Chem 38:
313–318
Ishida J, Ohtsu H, Tachibana Y, Nakanishi Y, Bastow KF, Nagai M,
Wang H-K, Itokawa H, Lee KH (2002) Antitumor agents.
Part 214: synthesis and evaluation of curcumin analogues as
cytotoxic agents. Bioorg Med Chem 10:3481–3487
Sabouraud dextrose broth in case of fungi) followed by
incubation at 37 1°C. The stock solutions of the test
compounds were serially diluted in test tubes containing
1 ml of sterile medium to get the concentration of
50–3.12 lg/ml and then inoculated with 100 ll of sus-
pension of respective microorganism in sterile saline. The
inoculated test tubes were incubated at 37 1°C for 24 h
in case of B. subtilis, S. aureus and E. coli, at 37 1°C for
48 h in case of Candida albicans and at 37 1°C for
120 h in case of A. niger and their pMICs(-log of Minimum
inhibitory concentrations) were determined. Minimum
inhibitory concentration (MIC), in microbiology, is the
lowest concentration of an antimicrobial agent that will
inhibit the visible growth of a microorganism after
incubation.
The reference compounds Norfloxacin and fluconazole
were also tested under similar conditions to compare the
results of tested compounds. The data for the antibacterial
and antifungal studies are listed in Table 2 and expressed
in Fig. 2.
Jungheim L (1989) Bicyclic pyrazolidinone antibacterial agents.
Synthesis of side chain analogues of carbapenems. PS-5 and
thienamycin. Tetrahedron Lett 30:1889–1892
Kang YK, Shin KJ, Yoo KH, Seo KJ (2000) Synthesis and
antibacterial activity of new carbapenems containing isoxazole
moiety. Bioorg Med Chem Lett 10:95–99
Kaymakci oglu BK, Rollas S (2002) Synthesis, characterization and
evaluation of antituberculosis activity of some hydrazones. Il
Farmaco 57:595–599
Kucukguzel SG, Rollas S, Erdeniz H, Kiraz M, Ekinci AC, Vidin A
(2000) Synthesis, characterization and pharmacological proper-
ties of some 4-arylhydrazono-2-pyrazolin-5-one derivatives
obtained from heterocyclic amines. Eur J Med Chem 35:
761–771
Acknowledgments We gratefully acknowledge the financial sup-
port from CSIR New Delhi. Thanks to SAIF, Panjab University,
Chandigarh for providing NMR spectra of the compounds.
References
Kumar S, Kumar G, Kapoor M, Surolia A, Surolia N (2006) Synthesis
and evaluation of substituted pyrazoles: potential antimalarials
targeting the enoyl-ACP reductase of Plasmodium falciparum.
Syn Commun 36:215–226
Larsen JS, Zahran MA, Pedersen EB, Nielsen C (1999) Synthesis of
triazinopyrazole derivatives as potential inhibitors of HIV-1.
Monatsh Chem 18:203–216
Liu H, Wang HQ, Liu ZJ (2007) Synthesis and herbicidal activity of
novel pyrazolo[3,4-d]pyrimidin-4-one derivatives containing
aryloxyphenoxypropionate moieties. Bioorg Med Chem Lett 17:
2203–2209
Madhavi K, Bharathi K, Prasad KVSRG (2010) Synthesis and
evaluation of 3-methyl-4-nitro-5-(substituted styryl) isoxazoles
for antioxidant and anti-inflammatory activities. Res J Pharm Bio
Chem Sci 1(4):1073–1082
Menozzi G, Mosti L, Merello L, Piana A, Armani U, Ghia M, Angiola
M, Mattioli F (2000) 4-Dialkylamino-1-(5-substituted or unsub-
stituted 1-phenyl-1H-pyrazol-4-yl)-butan-1-ols: synthesis and
evaluation of analgesic, anti-inflammatory and platelet anti-
aggregating activities. Il Farmaco 55:219–226
Palomer A, Cabre F, Pascual J, Campos J, Trujillo MA, Entrena A,
Callo MA, Garcia L, Mauleon D, Espinosa A (2002) Identifi-
cation of Novel Cyclooxygenase-2 Selective inhibitors using
pharmacophore models. J Med Chem 45:1402–1411
Panda SS, Chowdary PVR, Jayashree BS (2009) Synthesis, antiin-
flammatory and antibacterial activity of novel indolyl-isoxaz-
oles. Ind J Pharm Sci 71(6):684–687
Park HJ, Lee K, Park SJ, Ahn B, Lee JC, Cho HY, Lee KI (2005)
Identification of antitumor activity of pyrazole oxime ethers.
Bioorg Med Chem Lett 15:3307–3312
Pattan SR, Reddy VV, Pawar PD, Khade AB, Desai NS, Bhat AR,
Taranalli AD (2007) Synthesis and anti-inflammatory evaluation
Akbas E, Berber I, Sener A, Hasanov B (2005) Synthesis and
antibacterial activity of 4-benzoyl-1-methyl-5-phenyl-1H-pyra-
zole-3-carboxylic acid and derivatives. Il Farmaco 60:23–26
Baraldi PG, Pavani MG, Nunez MDC, Brigidi P, Vitali B, Gambari R,
Romagnoli R (2002) Antimicrobial and antitumor activity of
N-heteroimmine-1,2,3-dithiazoles and their transformation in
triazolo-, imidazo-, and pyrazolopirimidines. Bioorg Med Chem
10:449–456
Bekhit AA, Fahmy HT, Rostom SAF, Baraka AM (2003) Design and
Synthesis of some substituted 1H-pyrazolyl-thiazolo[4,5-
d]pyrimidines as anti-inflammatory-antimicrobial agents. Eur J
Med Chem 38:27–36
Bekhit AA, Ashour HMA, Ghany YSA, Bekhit AEA, Baraka A
(2008) Synthesis and biological evaluation of some thiazolyl and
thiadiazolyl derivatives of 1H-pyrazole as anti-inflammatory
antimicrobial agents. Eur J Med Chem 43:456–463
Chimenti F, Bizzarri B, Bolasco A, Secci D, Chimenti P, Granese A,
Carradori S, Ascenzio MD, Lilli D, Rivanera D (2011) Synthesis
and biological evaluation of novel 2,4-disubstituted-1,3-thiazoles
as anti-Candida spp agents. Eur J Med Chem 46:378–382
Dixit PP, Patil VJ, Nair PS, Jain S, Sinha N, Arora SK (2006)
Synthesis of 1-[3-(4-benzotriazol-1/2-yl-3-fluorophenyl)-2-oxo-
oxazolidin-5-ylmethyl]-3-substituted-thiourea derivatives as
antituberculosis agents. Eur J Med Chem 41:423–428
El-Gaby MSA, Atalla AA, Gaber AM, Abd Al-Wahab KA (2000)
Studies on amino-pyrazoles: antibacterial activity of some novel
pyrazolo[1,5a]pyrimidines containing sulfonamido moieties. Il
Farmaco 55:596–602
El-Subbagh HI, Abadi AH, Lehmann J (1999) Synthesis and
antitumor activity of ethyl 2-substitutedaminothiazole-4-carbox-
ylate analogs. Arch Pharm Pharm Med Chem 332:137–142
123

3548
Med Chem Res (2012) 21:3541–3548
of 4-phenylamino benzylidene(thiazolidine-2,4-dione) deriva-
tives. Indian Drugs 44(4):253
Singh SP, Tarar LS, Kumar D (1993) A facile route for the synthesis
of 1-[5-hydroxy-3-methyl-(2-thiazolyl)-4-pyrazolyl]-1.3-butan-
ediones from dehydroacetic acid. Syn Commun 23(13):1855–
1861
Sugiura S, Ohno S, Ohtani O, Izumi K (1977) Synthesis and
antinflammatory and hypnotic activity of 5-alkoxy-3-(N-substi-
tuted carbamoyl)-1-phenylpyrazoles. J Med Chem 20:80–85
Turan-Zitouni G, Sivaci M, Kilic FS, Erol K (2001) Synthesis of
some triazolyl-antipyrine derivatives and investigation of anal-
gesic activity. Eur J Med Chem 36:685–689
Velikorodov AV, Sukhenkol LT (2003) Synthesis and antimicrobial
activity of 3,5-disubstituted isoxazolines and isoxazoles with
carbamate groups. Pharm Chem J 37:22–24
Venugopala KN, Jayashree BS (2003) Synthesis and characterization
of carboxamides of 20-amino-40-(6-bromo-3-coumarinyl) thia-
zole for their analgesic and anti-inflammatory activity. Ind J Het
Chem 12:307–310
William CP, Harriet WH, Michael DT, Michael JR, David GTJ, Cleo
JCC, Annette MD, Sylvester RK, Ila S, Steinbaugh BA, Batly
BL, Painchaud CA, Rapundalo ST, Michniewicz BM, Olson SCJ
(1992) Structure-activity relationships of a series of 2-amino-4-
thiazole-containing renin inhibitors. J Med Chem 35:2562–2572
Witherington J, Bordas V, Garland SL, Hickey DMB, Ife RJ, Liddle J,
Saunders M, Smith DG, Ward RW (2003) 5-Arylpyrazolo[3,4-
b]pyridines: potent inhibitors of glycogen synthase kinase-3
(GSK-3). Bioorg Med Chem Lett 13:1577–1580
Xue C, Roderick J, Mousa S, Olson RE, DeGrado WF (1998)
Synthesis and antiplatelet effects of an isoxazole series of
glycoprotein IIb/IIIa antagonists. Bioorg Med Chem Lett 8:
3499–3504
Poreba K, Opolski A, Wietrzyk J, Kowalska M (2001) Synthesis and
antiproliferative activity in vitro of new derivatives of 3-amin-
opyrazolo[3,4-b]pyridine. Part 1: reaction of 3-aminopyrazol-
o[3,4-b]pyridine with 1,3-,1,4- and a,b-unsaturated ketones.
Arch Pharm Pharm Med Chem 334:219–223
Rajanarendar E, Rao EK, Shaik FP, Reddy MN, Srinivas M (2010)
Design, synthesis, antibacterial and antifungal activity of novel
spiroisoxazolyl-bis-[5,50]thiazolidin-4-ones and spiro-isoxazolyl
thiazolidin-4-one-[5,50]-1,2–4 oxdiazolines. J Sulfur Chem 31
(4):263–274
Ramla MM, Omar MA, El-Khamry AMM, El-Diwan HI (2006)
Synthesis and antitumor activity of 1-substituted-2-methyl-5-
nitrobenzimidazoles. Bioorg Med Chem 14:7324–7332
Rathelot P, Azas N, El-Kashef H, Delmas F, Di Giorgio C, Timon-
David P, Maldonado J, Vanelle P (2002) 1,3-Diphenylpyrazoles:
synthesis and antiparasitic activities of azomethine derivatives.
Eur J Med Chem 37:671–679
Rostom SAF (2006) Synthesis and in vitro antitumor evaluation of
some indeno[1,2-c]pyrazol(in)es substituted with sulfonamide,
sulfonylurea (thiourea) pharmacophores and some derived
thiazole ring systems. Bioorg Med Chem 14:6475–6485
Rostom SAF, Shalaby MA, El-Demellawy MA (2003) Polysubstitut-
ed pyrazoles, part 5. Synthesis of new 1-(4-Chlorophenyl)-4-
hydroxy-1H-pyrazole-3-carboxylic acid hydrazide analogs and
some derived ring systems. A novel class of potential antitumor
and anti-HCV agents. Eur J Med Chem 38:959–974
Rostom SAF, El-Ashmawy IM, El Razik HR, Badr MH, Ashour
HMA (2009) Design and synthesis of some thiazolyl and
thiadiazolyl derivatives of antipyrine as potential non-acidic
anti-inflammatory, analgesic and antimicrobial agents. Bioorg
Med Chem 17:882–895
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