Synthesis of 2-oxoazetidine derivatives of 2-aminothiazole and their biological activity

Article abstract of DOI:10.2298/JSC110616002S

A new series of 3-chloro-4-(substituted phenyl)-1-{[2-(2-thiazolylamino) ethyl]amino}-2-azetidinone, compounds 4a-m, has been synthesized from 2-aminothiazole as the starting material. The structures of all the synthesized compounds were confirmed by chemical and spectral analyses, such as FTIR, 1H-NMR and 13C-NMR spectroscopy. All the final synthesized compounds 4a-m were screened for their antibacterial and antifungal activities against some selected bacteria and fungi and for their antitubercular activity against Mycobacterium tuberculosis, and their minimum inhibitory concentration (MIC) values were determined. The anti-inflammatory activities of the title compounds were screened using albino rats (either sex) and gave acceptable results. 2012 Copyright (CC) SCS.

Full text of DOI:10.2298/JSC110616002S

J. Serb. Chem. Soc. 77 (5) 599–605 (2012)
UDC 547.433–304.2+547.789.1+542.913:57–188
JSCS–4293
Original scientific paper
Synthesis of 2-oxoazetidine derivatives of 2-aminothiazole
and their biological activity
*
PUSHKAL SAMADHIYA , RITU SHARMA, SANTOSH K. SRIVASTAVA
and SAVITRI D. SRIVASTAVA
Synthesis Organic Chemistry Laboratory, Department of Chemistry, Dr. H.S. Gour
University, Sagar, Madhya Pradesh-470003, India
(Received 5 January, revised 16 June 2011)
Abstract: A new series of 3-chloro-4-(substituted phenyl)-1-{[2-(2-thiazolylami-
no)ethyl]amino}-2-azetidinone, compounds 4a–m, has been synthesized from
2-aminothiazole as the starting material. The structures of all the synthesized
compounds were confirmed by chemical and spectral analyses, such as FTIR,
1H-NMR and 13C-NMR spectroscopy. All the final synthesized compounds
4a–m were screened for their antibacterial and antifungal activities against
some selected bacteria and fungi and for their antitubercular activity against
Mycobacterium tuberculosis, and their minimum inhibitory concentration
(MIC) values were determined. The anti-inflammatory activities of the title
compounds were screened using albino rats (either sex) and gave acceptable re-
sults.
Keywords: synthesis; 2-aminothiazole; azetidinone; antimicrobial; antitubercu-
lar; anti-inflammatory.
INTRODUCTION
The azetidinone unit is a crucial structural feature of significant classes of
antibiotics and its chemistry is very important to their biological activities, for
instance, the penicillin and cephalosporin antibiotics possess cis-β-lactam units,
whereas the thienamycins and trinems have trans-β-lactam moieties. The
effective synthesis of β-lactam became a desirable goal based on the discovery of
penicillin and cephalosporin. Although most penicillin and cephalosporin related
compounds are obtained by biosynthesis, chemical modification of intermediates
for bioassay of the antibacterial activity of the resulting compounds has become
of utmost importance because of the growing resistance of bacteria against pe-
nicillin- and cephalosporin-like compounds and the need for medicines with
1,2
more specific antibacterial activity. The azetidinone derivatives have also been
*Corresponding author. E-mail: pushkalsamadhiya@rediffmail.com
doi: 10.2298/JSC110616002S
599
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recognized as tumor necrosis factor-alpha (TNF-alpha) converting enzyme (TACE)
3
4
inhibitors and agents with new biological activities, such as anticancer, anti-
5
6
7
8
coccidial, cardiovascular, antiviral, mutagenic, anticonvulsant and anti-in-
9,10
flammatory.
Condensed heterocyclic systems are of considerable interest not
only because of their potential biological activity, but also because of their ver-
satility as synthons in organic transformations.
The thiazole moiety is also an important component of the pharmacophores
of a large number of molecules of medicinal significance and the evaluation of
11
12
13,14
their biological activity, such as antiprotozoal, antibacterial, antifungal,
15
16
antitubercular and anthelmintic, with emphasis on their potential medicinal
applications, is desirable. Moreover, thiazole derivatives have attracted a great
deal of interest due to their wide applications in the field of pharmaceuticals.
In the present study, a series of N-[2-(2-aminothiazolyl)ethyl]-4-(substituted
phenyl)-3-chloro-2-oxo-1-iminoazetidines, compounds 4a–m, was synthesized as
shown in Scheme 1. The structure of all the synthesized compounds was elu-
cidated by FTIR, H-NMR, C-NMR, and chemical methods. All the final
compounds 4a–m were screened for their antibacterial, antifungal, antitubercular
and anti-inflammatory activities.
1
13
NH2NH2.H2O
BrCH2CH2Cl
N
S
N
S
S
N
S
NHCH2CH2Cl
1
NH2
NHCH2CH NHNH2
22
ArCHO
N
Et3N+ClCH2COCl
CHAr
Cl
NHCH2CH2NHN
N
S
4(a-m)
NHCH2CH2NHN=CHAr
O
3(a-m)
Ar= substituted phenyl ring
Compound
Ar
Compound
Ar
3a and 4a
3b and 4b
3c and 4c
3d and 4d
3e and 4e
3f and 4f
3g and 4g
C6H5
3h and 4h
3i and 4i
3j and 4j
3k and 4k
3l and 4l
3m and 4m
–
4-NO2C6H4
3-NO2C6H4
2-NO2C6H4
4-CH3OC6H4
4-CH3C6H4
4-HOC6H4
–
4-ClC6H4
3-ClC6H4
2-ClC6H4
4-BrC6H4
3-BrC6H4
2-BrC6H4
Scheme 1. Synthesis of compounds 1–4.
EXPERIMENTAL
Melting points were taken in open capillaries and are uncorrected. The progress of the re-
actions was monitored by silica gel-G coated TLC plates using MeOH:CHCl3 (2:8) system.
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SYNTHESIS AND BIOLOGICAL ACTIVITY OF 2-OXOAZETIDINE DERIVATIVES
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The spot was visualized by exposing the dry plate to iodine vapors. The IR spectra were re-
corded in KBr discs on a Shimadzu 8201 PC FTIR spectrophotometer (νmax in cm-1) and the
1H-NMR and 13C-NMR spectra were measured on a Bruker DRX-300 spectrometer in CDCl3 at
300 and 75 MHz, respectively, using TMS as an internal standard. All chemical shifts are
reported on δ scales. Elemental analyses were realized on a Carlo Erba-1108 analyzer. The
analytical data of all the compounds were satisfactory. For column chromatographic
purification of the products, Merck silica gel 60 (230–400 mesh) was used. The reagent grade
chemicals were purchased from commercial sources and further purified before use.
Procedure for the synthesis of 2-[(2-chloroethyl)amino]thiazole, compound 1
2-Aminothiazole and 1-bromo-2-chloroethane (1:1 mole) were dissolved in methanol.
The reaction mixture was continuously stirred on a magnetic stirrer at 30–35 °C for about 8 h.
The product was filtered and purified by column chromatography. The purified product was
dried in the oven at 45–50 °C for 8 h and recrystallized from ethanol to yield compound 1.
Procedure for the synthesis of N-(2-hydrazinylethyl)-thiazolamine, compound 2
Compound 1 and hydrazine hydrate (1:1 mole) were dissolved in methanol at room tem-
perature. The reaction mixture was continuously stirred on a magnetic stirrer at 30–35 °C for
about 5 h. The product was filtered off and purified by column chromatography. The purified
product was dried in an oven at 45–50 °C for 9 h and recrystallized from ethanol to yield
compound 2.
General procedure for the synthesis of substituted benzaldehyde, 2-[2-(thiazolylamino)ethyl]-
hydrazone, compounds 3a–m
Compound 2 and an appropriate substituted benzaldehyde (1:1 mole) were dissolved in
methanol and allowed to reaction. The reaction mixture was first continuously stirred on a
magnetic stirrer at 30–35 °C for about 3–5 h and then kept on a steam bath at 75–90 °C for
about 3–4 h. The products were filtered and cooled to room temperature. The filtered products
were purified by column chromatography. The purified products were dried in an oven at 55–
–60 °C for 6–10 h and recrystallized from ethanol to yield compounds 3a–m.
General procedure for the synthesis of 3-chloro-4-(substituted phenyl)-1-{[2-(2-thiazolylami-
no)ethyl]amino}-2-azetidinone, compounds 4a–m
An appropriate compound 3a–m and chloroacetyl chloride in the presence of Et3N (1:1:1
mole ratio) were dissolved in methanol (50 ml) and allowed to react. The reaction mixture was
first continuously stirred on a magnetic stirrer at 30–35 °C for about 3–4 h and then kept on a
steam bath at 70–85 °C for about 3–5 h. The products were filtered and cooled to room tempe-
rature. The filtered products were purified by column chromatography. The purified products
were dried in an oven at 60–65 °C for 4–8 h and recrystallized from ethanol to yield com-
pounds 4a–m, respectively.
Biological importance
The antibacterial, antifungal and antitubercular activities of compounds 4a–m were as-
sayed in vitro against selected bacteria: Bacillus subtilis, Escherichia coli, Staphylococcus au-
reus and Klebsiella pneumoniae, and fungi: Aspergillus niger, A. flavus, Candida albicans and
Fusarium oxysporum, and Mycobacterium tuberculosis (H37Rv) strain. The minimal inhibi-
tory concentration (MIC) values of compounds 4a–m were determined using the filter paper
disc diffusion method (antibacterial and antifungal activity) and the Lowenstein–Jensen (LJ)
medium (conventional) method (antitubercular activity) at 100 μg mL-1 and lower concentra-
tions. Streptomycin and griseofulvin, used as the standard for the antibacterial and antifungal
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activity, respectively, showed MIC values in the range 1.25–3.25 μg mL-1 for all the bacterial
strain and 6.25–12.5 μg mL-1 for all fungal strain. For the antitubercular activity, isoniazid and
rifampicin were taken as standards (MIC range 1.25–2.50 μg mL-1). All standards were also
screened under similar condition for comparison.
Anti-inflammatory activity
The carageenan-induced rat paw edema method was employed for evaluating the anti-
inflammatory activity of the compounds at a dose 50 mg kg–1 bw in albino rats (weighing 80–
110 g, each group contained 5 animal) using phenylbutazone as the standard drug for compa-
rison at a dose 30 mg kg-1 body weight. The rate paw edema was produced by the method of
Winter et al.17 The percentage inhibition of inflammation was calculated by applying the
Newbould formula.18
RESULTS AND DISCUSSION
3-Chloro-4-(substituted
phenyl)-1-{[2-(2-thiazolylamino)ethyl]amino}-2-
-azetidinone, compounds 4a–m, were synthesized in four different steps.
2-Aminothiazole on reaction with Cl(CH ) Br at room temperature afforded
2 2
2-[(2-chloroethyl)amino]thiazole, compound 1. The IR spectrum of compound 1
displayed absorptions at 1336 and 740 for (C–N) and (C–Cl), respectively, this
clearly indicated the synthesis of compound 1. Compound 1 on reaction with
hydrazine hydrate at room temperature yielded N-(2-hydrazinylethyl)-2-
-thiazolamine, compound 2. The IR spectrum of compound 2 showed absorptions
–1
for NH and NH at 3378 and 3429 cm , respectively, while the absorption for
2
1
(C–Cl) in the IR spectrum of compound 1 had disappeared. The H-NMR spec-
trum of 2 displayed signals at δ 7.63 and 5.56 ppm for NH and NH , respectively.
2
Compound 2 on further reaction with several selected substituted aromatic
aldehydes produced substituted benzaldehyde, 2-[2-(thiazolylamino)–ethyl]–
hydrazone, compounds 3a–m. The characteristic absorption for a Schiff base
–1
(N=CH) appeared in the range 1542–1579 cm in the IR spectra of compounds
1
13
3a–m and in the H- and C-NMR spectra signals appeared at δ 7.82–8.12 and δ
1
151.6–157.4 ppm, respectively. In the H-NMR, the broad signal of NH present
2
in the spectrum of compound 2 had disappeared. Compounds 3a–m on treatment
with ClCH COCl in the presence of Et N furnished the final products,
2
3
compounds 4a–m. In the IR spectra of compounds 4a–m, the carbonyl group of
the β-lactam ring showed a characteristic absorption in the range 1726–
–1
1
–1752 cm and the H-NMR spectra of compounds 4a–m showed two doublets
for (N–CH) and (CH–Cl) in the range δ 4.72–4.98 and 4.13–4.28 ppm, res-
13
pectively. In the C-NMR spectra of compounds 4a–m, three characteristic
signals appeared for (N–CH), (CH–Cl) and (CO cyclic) in the δ ranges 60.8–
–65.7, 49.7–54.8 and 169.8–176.4 ppm, respectively. The IR absorption and
1
13
H- and C-NMR signals of the N=CH group were absent. All these fact collect-
ively suggest the successful synthesis of all the above compounds.
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SYNTHESIS AND BIOLOGICAL ACTIVITY OF 2-OXOAZETIDINE DERIVATIVES
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The analytic and spectral data of all the synthesized compounds are given in
the supplementary material to this paper.
Biological testing
The results of all the described activities (antibacterial, antifungal, antitu-
bercular and anti-inflammatory) are summarized in Tables I and II. The results of
the antimicrobial screening data revealed that all the compounds 4a–m showed
considerable and varied activity against the selected microorganisms. The results
shown in Tables I and II revealed that all the synthesized compounds 4a–m have a
structure activity relationship (SAR) because the activity of the compounds
varied with substitution. The nitro group-containing compounds (4h, 4i and 4j)
showed higher activity than the chloro (4c and 4d), or bromo group containing
compounds (4e and 4f). The chloro and bromo derivatives also had a higher activity
than the other rested compounds. Based on the SAR, it can be concluded that the
activity of the compounds depends on electron withdrawing nature of the substituent
groups. The sequence of the activity is the following: NO > Cl > Br > OH >
2
> OCH > CH .
3
3
TABLE I. Antibacterial, antifungal and antitubercular activities of compounds 4a–m. The
MIC values of the standard streptomycin for all bacteria strains and griseofulvin for all fungi
strains were in the range of 1.25–3.25 and 6.25–12.5 μg ml-1, respectively. Isoniazid and ri-
fampicin were used as standards, MIC values in the range of 1.25–2.50 μg ml-1, for M.
tuberculosis
Antitubercular
Antibacterial activity
Antifungal activity
A. F. oxi-
activity
Compd.
B. sub- E. S. au- K. pneu-
A.
C. al-
M. tuber-
culosis
>12.5
>2.50
>2.50
2.50
>2.50
>2.50
6.25
2.50
2.50
>2.50
12.5
>12.5
6.25
tilis
coli reus moniae niger flavus sporum bicans
4a
4b
4c
4d
4e
4f
4g
4h
4i
12.5 >6.25 12.5
>3.25 6.25 3.25
6.25 >3.25 6.25
>3.25 6.25 3.25
6.25 >3.25 3.25
6.25 3.25 6.25
>3.25 6.25 >3.25
3.25 >3.25 3.25
3.25 3.25 >3.25
3.25 >3.25 3.25
>12.5 6.25 >12.5
6.25
>3.25
3.25
>25 >25
>25 >12.5
>12.5 25
>12.5 >25
>25
>25
>12.5
>12.5
25
>25
>25
>12.5
>12.5
>25
>12.5
25
>25
>12.5
>12.5
>25
>25
>12.5
6.25
>3.25 >12.5 25
>3.25 >12.5 >12.5 >12.5
6.25
3.25
3.25
3.25
6.25
25 >12.5 >12.5
25 >12.5 >12.5
>12.5 >12.5 >12.5
>12.5 >12.5 >12.5
4j
4k
4l
25
>25 >25
>25 25
25
>25
>25
>12.5
>12.5 >12.5 >12.5 >12.5
>3.25 >3.25 >6.25 >6.25
4m
The investigation of antimicrobial (antibacterial, antifungal and antitubercular)
data revealed that the compounds 4c, 4d, 4e, 4f, 4h, 4i and 4j displayed high activity,
the compounds 4b, 4g and 4m showed moderate activity and the other compounds
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SAMADHIYA et al.
showed low activity against all the strains compared with the standard drugs. In the
anti-inflammatory activity test, compounds 4c, 4d, 4e, 4f, 4h, 4i and 4j showed high
activity while the other compounds displayed moderate to low activity.
TABLE II. Anti-inflammatory activity of compounds 4a–m
Before carageenan administration Total increase in paw volume
Compound
Inhibition, %
(mean SEM)
after 5 h (mean SEM)
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
0.62 0.02
0.65±0.02
0.66±0.02
0.64±0.02
0.66±0.03
0.67±0.02
0.66±0.02
0.65±0.03
0.68±0.02
0.67±0.03
0.65±0.02
0.64±0.02
0.67±0.02
0.68±0.02
0.66±0.03
0.18±0.02
0.16±0.02
0.16±0.01
0.17±0.02
0.15±0.02
0.14±0.01
0.16±0.01
0.14±0.01
0.13±0.03
0.12±0.02
0.16±0.02
0.18±0.02
0.16±0.01
0.35±0.01
0.10±0.02
48.57
54.29
54.29
51.43
57.14
60.00
54.29
60.00
62.86
65.71
54.29
48.57
54.29
–
4m
Control
Standard; phe-
nylbutazone
71.43
CONCLUSIONS
The research study reports the successful synthesis of compounds 1–4. The
antimicrobial and antitubercular activity of the newly synthesized compounds
bearing a 2-azetidinone moiety revealed that all the tested compounds showed
moderate to good antibacterial, antifungal and antitubercular activities against the
selected microbial strains. The results of the anti-inflammatory activity testing
also showed positive results. Some of the compounds displayed promising ac-
tivities and are of interest for further transformations towards more potent deri-
vatives.
SUPPLEMENTARY MATERIAL
Аnalytical and spectral data of synthesized compounds are available elec-
tronically from http://www.shd.org.rs/JSCS/, or from the corresponding author
on request.
Acknowledgements. The authors are thankful to SAIF, Central Drugs Research Institute
Lucknow (India) for providing the spectral and analytical data of the compounds. We are
thankful to the Head, Department of Biotechnology, Dr. H. S. Gour, University, Sagar (India)
for the antimicrobial (antibacterial and antifungal) activity determinations and to the Micro-
care Laboratory and the Tuberculosis Research Center Surat, Gujarat (India) for the antituber-
culosis activity results. We are also thankful to the Head, Department of Chemistry Dr. H. S.
Gour, University, Sagar (India) for providing the facilities to carry out the work.
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SYNTHESIS AND BIOLOGICAL ACTIVITY OF 2-OXOAZETIDINE DERIVATIVES
605
И З В О Д
СИНТЕЗА И БИОЛОШКА АКТИВНОСТ 2-ОКСОАЗЕТИДИНСКИХ
ДЕРИВАТА 2-АМИНОТИАЗОЛА
PUSHKAL SAMADHIYA, RITU SHARMA, SANTOSH K. SRIVASTAVA и SAVITRI D. SRIVASTAVA
Synthesis Organic Chemistry Laboratory, Department of Chemistry, Dr. H.S. Gour University, Sagar,
Madhya Pradesh-470003, India
Синтетисана је серија нових деривата 3-хлоро-4-(супституисани фенил)-1-{[2-(тиазо-
лиламино)етил]амино}-2-азетидинона, једињења 4а–m, полазећи од 2-аминотиазола. Струк-
тура свих синтетисаних једињења потврђена је аналитичким и спектралним методамa, IC,
1H-NMR и 13C-NMR спектроскопијом. Испитана је антибактеријска, антифунгална актив-
ност према одабраним ћелијским линијама бактерија и гљива, као и антитуберкулозна
активност према Mycobacterium tuberculosis синтетисаних једињења 4а–m. Антиинфлама-
торна активност је испитана према албино пацовима. Резултати показују задовољавајућу
активност тестираних једињења.
(Примљено 5. јануара, ревидирано 16. јуна 2011)
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