Synthesis and antimicrobial evaluation of new pyrano[4,3-b]pyran and pyrano[3,2-c]chromene derivatives bearing a 2-thiophenoxyquinoline nucleus

Article abstract of DOI:10.1002/ardp.201100203

A new series of pyrano[4,3-b]pyran 4a-i and pyrano[3,2-c]chromene 6a-r derivatives bearing a 2-thiophenoxyquinoline nucleus were synthesized by reaction of 2-(4-(un)-substituted thiophenoxy)quinoline-3-carbaldehydes 2a-i with 6-methyl-4-hydroxypyran-2-one

Full text of DOI:10.1002/ardp.201100203

314
Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
Full Paper
Synthesis and Antimicrobial Evaluation of New
Pyrano[4,3-b]pyran and Pyrano[3,2-c]chromene Derivatives
Bearing a 2-Thiophenoxyquinoline Nucleus
Jigar A. Makawana, Manish P. Patel, and Ranjan G. Patel
Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, Gujarat, India
A new series of pyrano[4,3-b]pyran 4a–i and pyrano[3,2-c]chromene 6a–r derivatives bearing a 2-
thiophenoxyquinoline nucleus were synthesized by reaction of 2-(4-(un)-substituted thiophenoxy)-
quinoline-3-carbaldehydes 2a–i with 6-methyl-4-hydroxypyran-2-one
3 and 4-hydroxy-6-(un)-
substituted-2H-chromen-2-one 5a–b respectively and malononitrile at room temperature in the
presence of KOH as a basic catalyst. All the compounds were screened against three Gram-positive
bacteria (Streptococcus pneumoniae, Bacillus subtilis, Clostridium tetani), three Gram-negative bacteria
(Salmonella typhi, Escherichia coli, Vibrio cholerae) and two fungi (Candida albicans, Aspergillus fumigatus)
using the broth microdilution MIC (minimum inhibitory concentration) method. Upon antimicrobial
screening, it was observed that the majority of the compounds were found to be active against Bacillus
subtilis, Clostridium tetani and Candida albicans as compared to standard drugs.
Keywords: Chromene / In vitro antimicrobial activity / Pyran / 2-Thiophenoxyquinoline
Received: June 9, 2011; Revised: October 6, 2011; Accepted: October 14, 2011
DOI 10.1002/ardp.201100203
Introduction
tuberculosis, anti-inflammatory and anti-fungal agents [5].
Naturally occurring chromenes were found in plants [6]
and have been used as valuable leads for the design and
synthesis of new pharmacophores for medicinal chemistry
and drug development. On the other hand, the quinoline
moiety is of great importance to chemists as well as biologists
as it is found in a large variety of naturally occurring com-
pounds and also chemically useful molecules having diverse
biological activities. A large variety of quinoline derivatives
have been used as antimicrobial [7], antileishmanial [8], anti-
tuberculosis [9], antimalerial [10], anticancer agents [11], etc.
Encouraged by their potential clinical applications and in
continuation of our previous investigations on biopotent
heterocycles we have recently published the pyrano[3,2-
c]chromene derivatives bearing 2-phenoxyquinoline nucleus
[12] and we observed that these compounds showed excellent
antimicrobial activity. In continuation, our efforts are
focused to design and synthesize biologically potent hetero-
cyclic systems via combination of both the therapeutically
active moieties 2-thiophenoxyquinoline and pyran or
chromene together in a single scaffold.
The exploration of heterocycles as privileged structures in
drug discovery is, beyond doubt, one of the major areas in
medicinal chemistry. These privileged structures represent a
class of molecules that act as ligands for various biological
receptors with a high degree of binding affinity. Problems
with multi-drug resistant microorganisms have reached an
alarming level in many countries around the world.
Infections caused by those microorganisms pose a serious
challenge to the medical community and the need for an
effective therapy has led to a search for novel antimicrobial
agents.
The pyran nucleus is a fertile source of biologically import-
ant molecules possessing a wide spectrum of biological
and pharmacological activities, such as antimicrobial [1],
antiviral [2] antiproliferative [3], antitumor activities [4],
etc. Further, chromene derivatives have attracted consider-
able interest due to their diverse biological properties
and therapeutical applications, namely as anti-HIV, anti-
Moreover, the most suitable protocol for the synthesis of
functionalized organic compounds would be a multicom-
ponent reaction due to the fact that the synthesis can be
Correspondence: Dr. Ranjan G. Patel, Department of Chemistry, Sardar
Patel University, Vallabh Vidyanagar, 388120, Gujarat, India.
E-mail: patelranjanben@yahoo.com
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Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
Pyrano[4,3-b]pyran and Pyrano[3,2-c]chromene Derivatives
315
performed without the isolation of the intermediates, with-
out discharging any functional groups and within short
reaction time [13].
peak of CH proton was observed at around 4.78–4.99 ppm.
Peaks at around 36.12–36.44 ppm for CH carbon and 56.18–
56.78 ppm for C–CN carbon were observed in the 13C-NMR
spectra of compounds 4a–i. In FT-IR spectra, compounds 4a–i
The constitution of all the compounds was characterized
using elemental analysis, FT-IR, 1H-NMR, 13C-NMR and the
molecular weight of some selected compounds was confirmed
by mass spectroscopy. All the compounds were screened for
in vitro antimicrobial activity against eight human pathogens,
of which three were Gram-positive bacteria (Streptococcus
pneumoniae, Bacillus subtilis, Clostridium tetani), three were
Gram-negative bacteria (Salmonella typhi, Escherichia coli, Vibrio
cholerae) and two were fungal pathogens (Candida albicans,
Aspergillus fumigatus), using the broth microdilution MIC
(minimum inhibitory concentration) method [14].
exhibited an absorption band at around 2194–2205 cmꢀ1 for
1
–C N str. and 1670–1725 cmꢀ1 for –C O str. Further, in H-
–
–
NMR spectra of compounds 6a–r, a singlet peak of CH proton
was observed at around 5.09–5.23 ppm. Peaks at around
35.57–37.45 ppm for CH carbon and 57.03–57.39 ppm for
C–CN carbon were observed in the 13C-NMR spectra of com-
pounds 6a–r. In FT-IR spectra, compounds 6a–r exhibited
absorption bands at around 2194–2210 cmꢀ1 for –C N str.
and 1670–1725 cmꢀ1 for–C O str. The change in the carbon-
–
–
ylic absorption of the lactones in compounds 4a–i and 6a–r
may be attributed to the spatial arrangement and positional
changes of R1. The obtained elemental analysis values are in
good agreement with theoretical data. Further, the molecu-
lar weight of selected compounds such as 4a, 6a, 6i and 6n
were confirmed by their mass spectral studies. Mass
spectroscopy of the above mentioned compounds showed
molecular ion peak [Mþ1]þ corresponding to exact mass.
Mass spectra of compound 4a gave molecular ion peak at
m/z ¼ 440 [Mþ1]þ corresponding to molecular formula
Results and discussion
Chemistry
The key intermediates, 2-(4-(un)-substituted thiophenoxy)qui-
noline-3-carbaldehydes 2a–i, were prepared by refluxing 2-
chloroquinoline-3-carbaldehydes 1a–c and various 4-(un)-sub-
stituted thiophenols in the presence of anhydrous potassium
carbonate in dry DMF for 2.5 h. Required 2-chloroquinoline-
3-carbaldehydes 1a–c were prepared by Vilsmeier-Haack reac-
tion according to literature procedure [15].
C
25H17N3O3S, compound 6a gave molecular ion peak at
m/z ¼ 476 [Mþ1]þ corresponding to molecular formula
In the present study, pyrano[4,3-b]pyran 4a–i and pyr-
ano[3,2-c]chromene 6a–r derivatives were synthesized in
moderate to good yield i.e. 64–94% by reaction of 2-(4-(un)-
substituted thiophenoxyquinoline)-3-carbaldehydes 2a–i
with 6-methyl-4-hydroxypyran-2-one 3 and 4-hydroxy-6-(un)-
substituted-2H-chromen-2-one 5a–b respectively and malono-
nitrile at room temperature in the presence of KOH as a basic
catalyst (Scheme 1).
C28H17N3O3S, compound 6i gave molecular ion peak at
m/z ¼ 520 [Mþ1]þ corresponding to molecular formula
C
30H21N3O4S and compound 6n gave molecular ion peak
at MS m/z ¼ 539 [Mþ1]þ corresponding to molecular formula
C
30H20ClN3O3S. All physical, analytical data as well as spec-
troscopic characterization data of the synthesized com-
pounds 4a–i and 6a–r are given in the experimental section.
Many pyran and chromene derivatives have been synthes-
ized using organic basic catalysts like piperidine, triethyl-
amine and using convenient electrochemical processes [16].
In the present study, we have used KOH as an inorganic basic
catalyst to avoid the use of hazardous organic bases. The
reaction provides advantage as it is carried out without
applying heat (or at room temperature) with a short reaction
time. In accordance with the mechanism suggested in
the literature [17], the first step of this process may involve
Knoevenagel condensation of aldehyde 2a and malononitrile
giving heterylidenenitrile derivatives, followed by Michael
addition of 3 to heterylidenenitrile to afford the title com-
pound 4a (Scheme 2). The mechanism remains the same for
the other mentioned compounds.
Antimicrobial screening
The examination of the antimicrobial activity data (Table 1)
reveals that most of the compounds showed effective anti-
bacterial and antifungal activity against the employed
strains when compared with the standard drugs ampicillin,
norfloxacin and griseofulvin.
Against the Gram-positive bacterium B. subtilis compound
6e has shown excellent activity (MIC ¼ 62.5 mg/mL) as com-
pared to ampicillin (MIC ¼ 250 mg/mL) while compound 6p
against the Gram-positive bacterium S. pneumoniae and com-
pound 6o against the Gram-negative bacterium E. coli showed
excellent activity (MIC ¼ 62.5 mg/mL) as compared to ampi-
cillin (MIC ¼ 100 mg/mL). Compound 4b is found to have
better activity (MIC ¼ 100 mg/mL) as compared to ampicillin
(MIC ¼ 250 mg/mL) against B. subtilis. Compound 4i against
B. subtilis and C. tetani as well as compound 6f against
B. subtilis were found to have better activity (MIC ¼ 125 mg/mL)
as compared to ampicillin (MIC ¼ 250 mg/mL). Compounds
4a, 4f, 6a, 6c and 6g against B. subtilis as well as compounds
The structures of all the synthesized compounds were
established by 1H-NMR, 13C-NMR, FT-IR spectrometry and
elemental analysis and the molecular weight of some
selected compounds was confirmed by using mass spec-
troscopy. In 1H-NMR spectra of compounds 4a–i, a singlet
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316
J. A. Makawana et al.
Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
Scheme 1. Synthetic pathway for the compounds 2a–i, 4a–i and 6a–r.
Scheme 2. Plausible mechanistic pathway
for the synthesis of compound 4a.
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Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
Pyrano[4,3-b]pyran and Pyrano[3,2-c]chromene Derivatives
317
Table 1. Antimicrobial activity (MIC, mg/mL) of compounds 4a–i and 6a–r.
Gram positive bacteria
Gram negative bacteria
Fungi
Compd
Streptococcus
pneumoniae
MTCC 1936
Bacillus
subtilis
MTCC 441
Clostridium
tetani
MTCC 449
Salmonella
typhi
MTCC 98
Escherichia
coli
MTCC 443
Vibrio
cholerae
MTCC 3906
Candida
albicans
MTCC 227
Aspergillus
fumigatus
MTCC 3008
4a
4b
4c
4d
4e
4f
4g
4h
4i
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
6q
200
200
100
500
500
250
250
250
200
200
250
200
250
250
250
200
200
250
500
500
250
500
250
100
62.5
200
250
100
10
200
100
250
500
500
200
250
250
125
200
250
200
200
62.5
125
200
250
500
250
500
250
500
500
500
500
250
250
250
100
–
250
250
200
250
500
200
250
250
125
200
200
200
200
200
250
200
250
200
250
200
250
500
500
500
250
250
500
250
50
250
200
250
200
125
200
250
200
200
250
100
250
250
500
500
100
250
250
200
500
250
200
200
250
200
200
200
100
10
200
200
250
200
100
250
200
125
250
250
100
250
250
500
500
100
250
250
200
500
250
125
100
62.5
250
100
200
100
10
200
200
200
250
100
250
250
250
200
250
125
200
250
500
500
250
250
200
250
200
250
200
200
200
200
250
200
100
10
250
1000
1000
1000
200
1000
200
200
>1000
1000
>1000
200
250
1000
500
500
250
250
1000
>1000
>1000
500
500
500
1000
1000
500
1000
1000
500
250
1000
1000
100
>1000
>1000
>1000
1000
100
500
1000
1000
500
1000
>1000
1000
500
>1000
>1000
1000
–
–
100
500
1000
>1000
>1000
–
–
500
6r
Ampicillin
Norfloxacin
Griseofulvin
–
–
–
–
–
4c, 4f, 6a–6e, 6g, 6i and 6k against C. tetani have shown
good activity (MIC ¼ 200 mg/mL) as compared to ampicillin
(MIC ¼ 250 mg/mL). Against the fungal pathogen C. albicans,
compounds 4e (MIC ¼ 200 mg/mL), 4a, 4f, 6a and 6b
(MIC ¼ 250 mg/mL) were found to have better activity as
compared to griseofulvin (MIC ¼ 500 mg/mL).
Compounds 4c and 6o against the Gram-positive bacterium S.
pneumoniae as well as compounds 6n and 6q against the Gram-
negative bacterium E. coli showed comparable activity
(MIC ¼ 100 mg/mL)
to
ampicillin
(MIC ¼ 100 mg/mL).
Moreover, compounds 4h, 4i, 6f, 6g, 6h, 6k, 6n and 6o
against C. albicans as well as compounds 6b and 6g against
A. fumigatus showed equal activity (MIC ¼ 500 mg/mL) to
griseofulvin (MIC ¼ 500 mg/mL).
Compound 4b against B. subtilis was found to be equally
active (MIC ¼ 100 mg/mL) as compared to norfloxacin
(MIC ¼ 100 mg/mL) while compounds 4g, 4h, 6h, 6j, 6l and
6q were found to be equally active (MIC ¼ 250 mg/mL) as com- Conclusion
pared to ampicillin (MIC ¼ 250 mg/mL) against B. subtilis and
C. tetani. Further, the compounds 4c, 6b and 6r against B. subtilis
as well as compounds 4a, 4b, 4d, 6f, and 6p against C. tetani
showed comparable activity (MIC ¼ 250 mg/mL) to ampicillin
(MIC ¼ 250 mg/mL). Further, compound 4e was found to be
equally active (MIC ¼ 100 mg/mL) against the Gram-negative
bacteria V. cholerae and E. coli as compared to ampicillin
(MIC ¼ 100 mg/mL) while compounds 6b and 6g were found
to have equal activity (MIC ¼ 100 mg/mL) against S. typhi and
E. coli as compared to ampicillin (MIC ¼ 100 mg/mL).
New pyrano[4,3-b]pyran and pyrano[3,2-c]chromene deriva-
tives bearing a 2-thiophenoxyquinoline nucleus were syn-
thesized by using an ecofriendly base at room temperature
through the one-pot MCRs approach. The engaged synthetic
strategy allows the construction of relatively complicated
nitrogen and oxygen carrying heterocyclic systems through
an easy and efficient reaction. Of the compounds studied, 6e
against B. subtilis, 6o against E. coli and 6p against S. pneumoniae
proved to be most efficient antimicrobial members. Majority
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J. A. Makawana et al.
Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 19.90 (CH3), 36.44 (CH),
56.78 (C–CN), 98.53, 119.49, 126.70, 126.89, 127.88, 128.23,
128.73, 129.50, 130.40, 130.40, 132.19, 132.19, 134.47,
137.27, 147.02, 157.60, 158.85, 159.50, 160.43, 161.44, 161.81
of the compounds were found to be active against B. subtilis, C.
tetani and C. albicans and compounds 6b and 6g (i.e. methyl
group either at the 6th position of the quinoline ring or at the
4th position of the thiophenol ring) were found to have better
activity against most of the species employed. According to
this conclusion, it is worth to mention that the synthesized
new compounds emerged as a spot of antimicrobial medicine
research.
(Ar–C), 163.87 (C O); MS m/z: 440 [Mþ1]þ. Anal. calcd.
–
–
for C25H17N3O3S (439.49 g/mol): C, 68.32; H, 3.90; N, 9.56.
Found: C, 68.04; H, 4.16; N, 9.87.
2-Amino-4-(2-(phenylthio)-6-methylquinolin-3-yl)-5-oxo-7-
methyl-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4b)
Yield: 93%; m.p.: 254–2568C; IR (KBr, n, cmꢀ1): 3387 and 3315
(asym. and sym. str. of –NH2), 3020 (Ar–CH str.), 2200 (–C N str.),
Experimental
1710 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.22
–
–
General procedures
(s, 3H, CH3), 2.41 (s, 3H, CH3), 4.78 (s, 1H, CH), 6.31–8.24
(m, 12H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm):
19.47 (CH3), 21.17 (CH3), 36.21 (CH), 56.41 (C–CN), 99.10,
118.32, 126.13, 127.05, 127.93, 128.20, 128.69, 129.89, 131.10,
131.10, 132.27, 132.27, 134.21, 137.76, 146.87, 157.46, 158.32,
Required acetic anhydride, substituted anilines, acetic acid,
malononitrile, phosphorous oxychloride, potassium hydroxide,
were obtained from S. D. Fine Chem Ltd., Vadodara, Gujarat,
India. 6-Methyl-4-hydroxypyran-2-one was obtained from Sigma-
Aldrich and 4-hydroxy-6-(un)-substituted-2H-chromen-2-ones
were synthesized by solid phase reaction of malonic acid and
4-(un)-substituted phenols in phosphorous oxychloride in the
presence of zinc chloride. Solvents were purified and dried
before being used. All melting points were taken in open capil-
–
159.74, 160.11, 161.57, 161.90 (Ar–C), 163.29 (C O). Anal. cald.
–
for C26H19N3O3S (453.51 g/mol): C, 68.86; H, 4.22; N, 9.27. Found:
C, 68.57; H, 4.53; N, 8.91.
2-Amino-4-(2-(phenylthio)-6-methoxyquinolin-3-yl)-5-oxo-
7-methyl-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile
(4c)
laries and are uncorrected. Thin-layer chromatography (TLC, on
60
aluminium plates precoated with silica gel,
F
254
, 0.25 mm
thickness) (Merck, Darmstadt, Germany) was used for monitor-
ing the progress of all reactions, purity and homogeneity of the
synthesized compounds. UV radiation and/or iodine were used as
the visualizing agents. Elemental analysis (% C, H, N) was carried
out on a Perkin-Elmer 2400 series-II elemental analyzer (Perkin-
Elmer, USA) and all compounds are within ꢁ0.4% of theory
specified. The IR spectra were recorded in KBr on a Perkin-
Elmer Spectrum GX FT-IR spectrophotometer (Perkin-Elmer,
Yield: 88%; m.p.: 278–2808C; IR (KBr, n, cmꢀ1): 3398 and 3325
(asym. and sym. str. of –NH2), 3041 (Ar–CH str.), 2196 (–C N str.),
1705 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.25
–
–
(s, 3H, CH3), 3.80 (s, 3H, OCH3), 4.89 (s, 1H, CH), 6.34–8.27
(m, 12H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm):
19.59 (CH3), 36.34 (CH), 56.67 (C–CN), 57.18 (OCH3), 98.17,
118.94, 126.37, 127.35, 127.67, 128.04, 128.53, 129.70, 130.19,
130.19, 132.24, 132.24, 134.59, 137.15, 146.90, 157.12, 158.49,
USA) and only the characteristic peaks are reported in cmꢀ1
.
1H-NMR and 13C-NMR spectra were recorded in DMSO-d6 on a
Bruker Avance 400F (MHz) spectrometer (Bruker Scientific
Corporation Ltd., Switzerland) using the solvent peak as internal
standard at 400 MHz and 100 MHz respectively. Chemical shifts
are reported in parts per million (ppm). Mass spectra were
scanned on a Shimadzu LCMS 2010 spectrometer.
–
159.83, 160.42, 161.07, 161.74 (Ar–C), 163.72 (C O). Anal. cald.
–
for C26H19N3O4S (469.51 g/mol): C, 66.51; H, 4.08; N, 8.95. Found:
C, 66.72; H, 3.78; N, 8.63.
2-Amino-4-(2-(p-chlorophenylthio)quinolin-3-yl)-5-oxo-7-
methyl-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4d)
Yield: 78%; m.p.: 268–2708C; IR (KBr, n, cmꢀ1): 3405 and 3320
(asym. and sym. str. of –NH2), 3056 (Ar–CH str.), 2205 (–C N str.),
General procedure for the synthesis of compounds 4a–i/
6a–r
1670 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.24
–
–
(s, 3H, CH3), 4.93 (s, 1H, CH), 6.32–8.23 (m, 12H, Ar–HþNH2);
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 19.81 (CH3), 36.39 (CH),
56.73 (C–CN), 98.36, 119.81, 126.07, 126.69, 127.22, 128.30,
128.89, 129.51, 130.17, 130.17, 132.15, 132.15, 134.29, 137.33,
147.03, 157.65, 158.84, 159.27, 160.49, 161.38, 161.32 (Ar–C),
2-(4-(un)-Substituted thiophenoxy)quinoline-3-carbaldehydes 2a–
i (10 mmol), malononitrile (10 mmol) and 6-methyl-4-hydroxy-
pyran-2-one 3/4-hydroxy-6-(un)-substituted-2H-chromene-2-one
5a–b (10 mmol) were thoroughly mixed in ethanolic KOH
(3 mmol, 10 mL) and stirred at room temperature for 0.5–1 h.
After completion of the reaction (checked by TLC), the solid
separated was filtered, washed well with ethanol (10 mL), dried
and recrystallized from chloroform to get the pure solid sample
4a–i/6a–r. Physical, analytical and spectroscopic characteriz-
ation data of the compounds 4a–i and 6a–r are given hereafter.
–
163.83 (C O). Anal. cald. for C25H16ClN3O3S (473.93 g/mol): C,
–
63.36; H, 3.40; N, 8.87. Found: C, 63.59; H, 3.12; N, 9.13.
2-Amino-4-(2-(p-chlorophenylthio)-6-methylquinolin-3-yl)-
5-oxo-7-methyl-4,5-dihydropyrano[4,3-b]pyran-3-
carbonitrile (4e)
Yield: 94%; m.p.: 244–2468C; IR (KBr, n, cmꢀ1): 3420 and 3315
(asym. and sym. str. of –NH2), 3020 (Ar–CH str.), 2205 (–C N str.),
2-Amino-4-(2-(phenylthio)quinolin-3-yl)-5-oxo-7-methyl-
4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4a)
Yield: 83%; m.p.: 232–2348C; IR (KBr, n, cmꢀ1): 3389 and 3326
(asym. and sym. str. of –NH2), 3058 (Ar–CH str.), 2194 (–C N str.),
1725 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.23
–
–
(s, 3H, CH3), 2.43 (s, 3H, CH3), 4.81 (s, 1H, CH), 6.33–8.25
(m, 11H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm):
19.31 (CH3), 21.48 (CH3), 36.19 (CH), 56.52 (C–CN), 99.42,
1690 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.24
–
–
(s, 3H, CH3), 4.99 (s, 1H, CH), 6.33–8.21 (m, 13H, Ar–HþNH2);
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Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
Pyrano[4,3-b]pyran and Pyrano[3,2-c]chromene Derivatives
319
118.07, 126.20, 127.29, 127.87, 128.37, 128.73, 129.81, 131.03,
131.03, 132.22, 132.22, 134.32, 137.89, 146.74, 157.59, 158.12,
57.19 (OCH3), 98.95, 118.78, 126.32, 127.10, 127.87, 128.20,
128.81, 129.22, 130.31, 130.31, 132.22, 132.22, 134.29, 137.08,
146.75, 157.43, 158.52, 159.67, 160.49, 161.05, 161.72 (Ar–C),
–
159.72, 160.21, 161.53, 161.55 (Ar–C), 163.67 (C O). Anal. cald.
–
for C26H18ClN3O3S (487.96 g/mol): C, 64.00; H, 3.72; N, 8.61.
–
163.55 (C O). Anal. cald. for C27H21N3O4S (483.54 g/mol): C,
–
67.07; H, 4.38; N, 8.69. Found: C, 67.39; H, 4.17; N, 8.92.
Found: C, 64.23; H, 4.08; N, 8.93.
2-Amino-4-(2-(phenylthio)quinolin-3-yl)-5-oxo-4,5-
dihydropyrano[3,2-c]chromene-3-carbonitrile (6a)
2-Amino-4-(2-(p-chlorophenylthio)-6-methoxyquinolin-3-
yl)-5-oxo-7-methyl-4,5-dihydropyrano[4,3-b]pyran-3-
carbonitrile (4f)
Yield: 69%; m.p.: 230–2328C; IR (KBr, n, cmꢀ1): 3389 and 3326
(asym. and sym. str. of –NH2), 3058 (Ar–CH str.), 2200 (–C N str.),
Yield: 81%; m.p.: 272–2748C; IR (KBr, n, cmꢀ1): 3396 and 3320
(asym. and sym. str. of –NH2), 3040 (Ar–CH str.), 2200 (–C N str.),
1690 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 5.19
–
–
(s, 1H, CH), 7.34–8.31 (m, 16H, Ar–HþNH2); 13C-NMR (100 MHz,
DMSO-d6) dC (ppm): 36.02 (CH), 57.11 (C–CN), 102.97, 113.44,
117.12, 119.44, 123.08, 125.20, 126.70, 127.88, 128.22, 128.73,
129.45, 130.40, 130.40, 132.16, 132.16, 133.53, 134.43,
137.17, 147.07, 148.23, 152.80, 154.47, 154.74, 157.70, 158.64
1720 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.24
–
–
(s, 3H, CH3), 3.81 (s, 3H, OCH3), 4.93 (s, 1H, CH), 6.35–8.29
(m, 11H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm):
19.53 (CH3), 36.30 (CH), 56.65 (C–CN), 57.42 (OCH3), 98.31,
118.92, 126.39, 127.52, 127.91, 128.11, 128.68, 129.71, 130.08,
130.08, 132.25, 132.25, 134.17, 137.02, 146.78, 157.19, 158.32,
(Ar–C), 160.10 (C O); MS m/z: 476 [Mþ1]þ. Anal. cald.
–
–
for C28H17N3O3S (475.52 g/mol): C, 70.72; H, 3.60; N, 8.84.
Found: C, 70.95; H, 3.89; N, 8.52.
–
159.79, 160.90, 161.18, 161.87 (Ar–C), 163.86 (C O). Anal. cald.
–
for C26H18ClN3O4S (503.96 g/mol): C, 61.97; H, 3.60; N, 8.34.
Found: C, 61.73; H, 3.82; N, 8.59.
2-Amino-4-(2-(phenylthio)-6-methylquinolin-3-yl)-5-oxo-
4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (6b)
Yield: 73%; m.p.: 262–2648C; IR (KBr, n, cmꢀ1): 3396 and 3320
(asym. and sym. str. of –NH2), 3041 (Ar–CH str.), 2210 (–C N str.),
2-Amino-4-(2-(p-methylphenylthio)quinolin-3-yl)-5-oxo-7-
methyl-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4g)
Yield: 84%; m.p.: 250–2528C; IR (KBr, n, cmꢀ1): 3398 and 3315
(asym. and sym. str. of –NH2), 3034 (Ar–CH str.), 2196 (–C N str.),
1705 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.41
–
–
(s, 3H, CH3), 5.21 (s, 1H, CH), 7.26–8.29 (m, 15H, Ar–HþNH2);
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.27 (CH3), 36.21 (CH),
57.03 (C–CN), 105.20, 113.17, 116.28, 118.72, 123.14, 125.62,
126.34, 127.74, 128.03, 128.43, 129.49, 130.87, 130.87, 132.25,
132.25, 132.96, 134.17, 137.56, 147.98, 148.12, 152.77,
1685 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.23
–
–
(s, 3H, CH3), 2.44 (s, 3H, CH3), 4.97 (s, 1H, CH), 6.37–8.22
(m, 12H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm):
19.39 (CH3), 21.31 (CH3), 36.12 (CH), 56.65 (C–CN), 98.31,
119.32, 126.28, 126.72, 127.62, 128.04, 128.98, 129.86, 130.24,
130.24, 132.19, 132.19, 134.11, 137.32, 147.09, 157.79, 158.21,
–
154.08, 155.10, 157.52, 158.89 (Ar–C), 160.38 (C O). Anal. cald.
–
for C29H19N3O3S (489.54 g/mol): C, 71.15; H, 3.91; N, 8.58. Found:
–
159.43, 160.18, 161.23, 161.15 (Ar–C), 163.79 (C O). Anal. cald.
–
for C26H19N3O3S (453.51 g/mol): C, 68.86; H, 4.22; N, 9.27. Found:
C, 70.86; H, 4.28; N, 8.72.
C, 68.53; H, 3.96; N, 9.05.
2-Amino-4-(2-(phenylthio)-6-methoxyquinolin-3-yl)-5-oxo-
4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (6c)
Yield: 79%; m.p.: 290–2928C; IR (KBr, n, cmꢀ1): 3405 and 3310
(asym. and sym. str. of –NH2), 3022 (Ar–CH str.), 2198 (–C N str.),
2-Amino-4-(2-(p-methylphenylthio)-6-methylquinolin-3-yl)-
5-oxo-7-methyl-4,5-dihydropyrano[4,3-b]pyran-3-
carbonitrile (4h)
1695 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 3.83
–
–
Yield: 91%; m.p.: 258–2608C; IR (KBr, n, cmꢀ1): 3410 and 3320
(asym. and sym. str. of –NH2), 3029 (Ar–CH str.), 2205 (–C N str.),
(s, 3H, OCH3), 5.09 (s, 1H, CH), 7.31–8.24 (m, 15H, Ar–HþNH2);
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 36.16 (CH), 55.81 (OCH3),
57.39 (C–CN), 105.45, 113.12, 116.67, 118.23, 123.04, 125.29,
126.73, 127.06, 128.19, 128.94, 129.18, 130.20, 130.20, 132.11,
132.11, 133.03, 134.27, 137.18, 147.89, 148.03, 152.62,
1710 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.22
–
–
(s, 3H, CH3), 2.42 (s, 3H, CH3), 2.45 (s, 3H, CH3), 4.85 (s, 1H,
CH), 6.34–8.26 (m, 11H, Ar–HþNH2); 13C-NMR (100 MHz,
DMSO-d6) dC (ppm): 19.23 (CH3), 21.29 (CH3), 21.42 (CH3), 36.37
(CH), 56.51 (C–CN), 99.88, 118.32, 126.87, 127.21, 127.69, 128.32,
128.93, 129.24, 131.10, 131.10, 132.20, 132.20, 134.12, 137.74,
146.14, 157.63, 158.07, 159.22, 160.19, 161.09, 161.31 (Ar–C),
–
154.13, 155.75, 157.80, 158.25 (Ar–C), 160.23 (C O). Anal. cald.
–
for C29H19N3O4S (505.54 g/mol): C, 68.90; H, 3.79; N, 8.31. Found:
C, 69.21; H, 3.98; N, 8.59.
–
163.52 (C O). Anal. cald. for C27H21N3O3S (467.54 g/mol): C,
–
69.36; H, 4.53; N, 8.99. Found: C, 69.62; H, 4.21; N, 8.84.
2-Amino-4-(2-(p-chlorophenylthio)quinolin-3-yl)-5-oxo-
4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (6d)
Yield: 64%; m.p.: 274–2768C; IR (KBr, n, cmꢀ1): 3398 and 3325
(asym. and sym. str. of –NH2), 3054 (Ar–CH str.), 2200 (–C N str.),
2-Amino-4-(2-(p-methylphenylthio)-6-methoxyquinolin-3-
yl)-5-oxo-7-methyl-4,5-dihydropyrano[4,3-b]pyran-3-
carbonitrile (4i)
1720 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 5.14
–
–
(s, 1H, CH), 7.23–8.18 (m, 15H, Ar–HþNH2); 13C-NMR (100 MHz,
DMSO-d6) dC (ppm): 36.24 (CH), 57.28 (C–CN), 102.18, 113.20,
116.24, 118.92, 123.57, 125.20, 126.78, 127.12, 128.04, 128.69,
129.22, 130.36, 130.26, 132.04, 132.04, 133.19, 134.57, 137.55,
147.41, 148.29, 152.12, 154.15, 155.39, 157.02, 158.65 (Ar–C),
Yield: 77%; m.p.: 246–2488C; IR (KBr, n, cmꢀ1): 3420 and 3326
(asym. and sym. str. of –NH2), 3056 (Ar–CH str.), 2194 (–C N str.),
1715 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.24
–
–
(s, 3H, CH3), 2.44 (s, 3H, CH3), 3.79 (s, 3H, OCH3), 4.88 (s, 1H,
CH), 6.33–8.24 (m, 11H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-
d6) dC (ppm): 19.34 (CH3), 21.37 (CH3), 36.32 (CH), 56.18 (C–CN),
–
160.16 (C O). Anal. cald. for C28H16ClN3O3S (509.96 g/mol): C,
–
65.95; H, 3.16; N, 8.24. Found: C, 66.18; H, 3.49; N, 7.96.
ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

320
J. A. Makawana et al.
Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
2-Amino-4-(2-(p-chlorophenylthio)-6-methylquinolin-3-yl)-
5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile
(6e)
2-Amino-4-(2-(p-methylphenylthio)-6-methoxyquinolin-3-
yl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-
carbonitrile (6i)
Yield: 83%; m.p.: 286–2888C; IR (KBr, n, cmꢀ1): 3410 and 3315
(asym. and sym. str. of –NH2), 3040 (Ar–CH str.), 2205 (–C N str.),
Yield: 77%; m.p.: 266–2688C; IR (KBr, n, cmꢀ1): 3405 and 3310
(asym. and sym. str. of –NH2), 3058 (Ar–CH str.), 2198 (–C N str.),
–
1680 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.42
1
1710 (–C O str.); H-NMR (400 MHz, DMSO-d ) dH (ppm): 2.31 (s, 3H,
–
–
–
6
(s, 3H, CH3), 5.20 (s, 1H, CH), 7.27–8.21 (m, 14H, Ar–HþNH2);
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.23 (CH3), 36.35 (CH),
57.21 (C–CN), 105.18, 113.27, 116.12, 118.90, 123.02, 125.53,
126.28, 127.10, 128.23, 128.40, 129.12, 130.76, 130.76, 132.23,
132.23, 132.59, 134.22, 137.09, 147.84, 148.19, 152.81, 154.19,
CH3), 3.82 (s, 3H, OCH3), 5.17 (s, 1H, CH), 7.17–8.18 (m, 14H,
Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.20 (CH3),
35.57 (CH), 55.89 (OCH3), 57.42 (C–CN), 106.01, 113.44, 117.11,
118.75, 119.41, 122.29, 122.80, 123.03, 125.18, 128.20, 128.80,
129.45, 130.05, 130.05, 133.33, 133.33, 133.97, 135.18, 136.79,
–
–
155.28, 157.13, 158.27 (Ar–C), 160.56 (C O). Anal. cald. for
–
C29H18ClN3O3S (523.99 g/mol): C, 66.47; H, 3.46; N, 8.02.
Found: C, 66.14; 3.12; N, 8.31.
137.96, 143.36, 152.74, 154.62, 157.55, 158.57 (Ar–C), 160.05 (C O);
–
MS m/z: 520 [Mþ1]þ. Anal. cald. for C30H21N3O4S (519.57 g/mol): C,
69.35; H, 4.07; N, 8.09. Found: C, 69.52; H, 3.85; N, 8.23.
2-Amino-4-(2-(p-chlorophenylthio)-6-methoxyquinolin-3-
yl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-
carbonitrile (6f)
2-Amino-4-(2-(phenylthio)quinolin-3-yl)-5-oxo-9-methyl-
4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (6j)
Yield: 89%; m.p.: 276–2788C; IR (KBr, n, cmꢀ1): 3410 and 3325
(asym. and sym. str. of –NH2), 3024 (Ar–CH str.), 2200 (–C N str.),
Yield: 76%; m.p.: 252–2548C; IR (KBr, n, cmꢀ1): 3387 and 3326
(asym. and sym. str. of –NH2), 3029 (Ar–CH str.), 2196 (–C N str.),
1670 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.45
–
–
1695 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 3.81
(s, 3H, CH3), 5.23 (s, 1H, CH), 7.21–8.15 (m, 15H, Ar–HþNH2);
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.09 (CH3), 37.34 (CH),
57.21 (C–CN), 113.17, 116.08, 119.32, 120.09, 123.71, 125.20,
126.22, 128.06, 128.35, 129.16, 129.97, 130.44, 130.44, 132.18,
132.18, 133.57, 134.01, 137.21, 147.30, 148.00, 152.32, 154.07,
–
–
(s, 3H, OCH3), 5.22 (s, 1H, CH), 7.21–8.15 (m, 14H, Ar–HþNH2);
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 36.29 (CH), 55.78 (OCH3),
57.24 (C–CN), 105.05, 113.35, 116.54, 118.28, 123.35, 125.65,
126.78, 127.22, 128.09, 128.67, 129.20, 130.24, 130.24, 132.45,
132.45, 133.09, 134.56, 137.33, 147.29, 148.56, 152.77, 154.64,
–
154.71, 157.89, 158.56 (Ar–C), 160.49 (C O). Anal. cald.
–
for C29H19N3O3S (489.54 g/mol): C, 71.15; H, 3.91; N, 8.58.
–
155.32, 157.10, 158.56 (Ar–C), 160.45 (C O). Anal. cald.
–
for C29H18ClN3O4S (539.99 g/mol): C, 64.50; H, 3.36; N, 7.78.
Found: C, 71.36; H, 4.19; N, 8.26.
Found: C, 64.29; H, 3.72; N, 7.51.
2-Amino-4-(2-(phenylthio)-6-methylquinolin-3-yl)-5-oxo-9-
methyl-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile
(6k)
2-Amino-4-(2-(p-methylphenylthio)quinolin-3-yl)-5-oxo-
4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (6g)
Yield: 92%; m.p.: 282–2848C; IR (KBr, n, cmꢀ1): 3389 and 3315
(asym. and sym. str. of –NH2), 3034 (Ar–CH str.), 2205 (–C N str.),
Yield: 68%; m.p.: 256–2588C; IR (KBr, n, cmꢀ1): 3398 and 3326
(asym. and sym. str. of –NH2), 3035 (Ar–CH str.), 2196 (–C N str.),
1725 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.29
1690 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.39
–
–
–
–
(s, 3H, CH3), 5.16 (s, 1H, CH), 7.28–8.32 (m, 15H, Ar–HþNH2);
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.34 (CH3), 36.26 (CH),
57.34 (C–CN), 105.17, 113.20, 116.32, 118.06, 123.47, 125.09,
126.34, 127.35, 128.03, 128.78, 129.12, 130.29, 130.29, 132.40,
132.40, 133.19, 134.24, 137.57, 147.14, 148.37, 152.58,
(s, 3H, CH3), 2.44 (s, 3H, CH3), 5.17 (s, 1H, CH), 7.31–8.17
(m, 14H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm):
21.03 (CH3), 21.44 (CH3), 37.15 (CH), 57.17 (C–CN), 113.13, 116.38,
119.12, 119.89, 121.54, 122.20, 126.76, 127.10, 128.13, 129.47,
131.40, 131.40, 132.21, 132.21, 133.09, 134.15, 134.93, 135.24,
136.43, 137.74, 145.12, 150.89, 154.47, 155.20, 158.56 (Ar–C),
–
154.39, 155.93, 157.29, 158.48 (Ar–C), 160.53 (C O). Anal. cald.
–
for C29H19N3O3S (489.54 g/mol): C, 71.15; H, 3.91; N, 8.58. Found:
–
160.35 (C O). Anal. cald. for C30H21N3O3S (503.57 g/mol): C,
–
71.55; H, 4.20; N, 8.34. Found: C, 71.24; H, 4.35; N, 8.06.
C, 71.41; H, 4.26; N, 8.76.
2-Amino-4-(2-(p-methylphenylthio)-6-methylquinolin-3-yl)-
5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile
(6h)
2-Amino-4-(2-(phenylthio)-6-methoxyquinolin-3-yl)-5-oxo-
9-methyl-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile
(6l)
Yield: 85%; m.p.: 248–2508C; IR (KBr, n, cmꢀ1): 3420 and 3325
(asym. and sym. str. of –NH2), 3041 (Ar–CH str.), 2194 (–C N str.),
Yield: 74%; m.p.: 284–2868C; IR (KBr, n, cmꢀ1): 3387 and 3315
(asym. and sym. str. of –NH2), 3038 (Ar–CH str.), 2210 (–C N str.),
1690 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.33
1715 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 3.80
–
–
–
–
(s, 3H, CH3), 2.41 (s, 3H, CH3), 5.13 (s, 1H, CH), 7.15–8.28
(m, 14H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm):
21.26 (CH3), 21.37 (CH3), 36.31 (CH), 57.24 (C–CN), 105.13,
113.09, 116.30, 119.12, 123.78, 125.69, 126.02, 127.78, 128.11,
128.90, 129.04, 130.55, 130.55, 132.00, 132.00, 132.42,
134.09, 137.61, 147.11, 148.80, 152.33, 154.19, 155.24, 157.17,
(s, 3H, OCH3), 2.46 (s, 3H, CH3), 5.19 (s, 1H, CH), 7.25–8.20
(m, 14H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm):
21.47 (CH3), 37.45 (CH), 55.81 (OCH3), 57.26 (C–CN), 113.08,
116.20, 119.41, 119.69, 121.23, 122.43, 126.57, 127.19, 128.43,
129.02, 131.00, 131.00, 132.24, 132.24, 133.39, 134.05, 134.67,
135.72, 136.10, 137.45, 145.17, 150.27, 154.44, 155.03,
–
–
158.51 (Ar–C), 160.72 (C O). Anal. cald. for C30H21N3O3S
–
(503.57 g/mol): C, 71.55; H, 4.20; N, 8.34. Found: C, 71.19;
158.70 (Ar–C), 160.57 (C O). Anal. cald. for C30H21N3O4S
–
(519.57 g/mol): C, 69.35; H, 4.07; N, 8.09. Found: C, 69.18;
H, 3.86; N, 8.01.
H, 3.75; N, 7.89.
ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
Pyrano[4,3-b]pyran and Pyrano[3,2-c]chromene Derivatives
321
2-Amino-4-(2-(p-chlorophenylthio)quinolin-3-yl)-5-oxo-9-
methyl-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile
(6m)
2-Amino-4-(2-(p-methylphenylthio)-6-methylquinolin-3-yl)-
5-oxo-9-methyl-4,5-dihydropyrano[3,2-c]chromene-3-
carbonitrile (6q)
Yield: 80%; m.p.: 264–2668C; IR (KBr, n, cmꢀ1): 3420 and 3310
(asym. and sym. str. of –NH2), 3020 (Ar–CH str.), 2194 (–C N str.),
Yield: 70%; m.p.: 260–2628C; IR (KBr, n, cmꢀ1): 3387 and 3315
(asym. and sym. str. of –NH2), 3058 (Ar–CH str.), 2194 (–C N str.),
1680 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.45
1670 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.40
–
–
–
–
(s, 3H, CH3), 5.12 (s, 1H, CH), 7.22–8.29 (m, 14H, Ar–HþNH2);
13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.01 (CH3), 37.42 (CH),
57.10 (C–CN), 113.09, 116.75, 119.14, 119.59, 121.65, 122.83,
126.47, 127.21, 127.87, 129.09, 131.28, 131.28, 132.30, 132.30,
133.14, 134.27, 134.69, 135.03, 135.91, 136.29, 145.39, 150.86,
(s, 3H, CH3), 2.42 (s, 3H, CH3), 2.45 (s, 3H, CH3), 5.21 (s, 1H,
CH), 7.30–8.12 (m, 13H, Ar–HþNH2); 13C-NMR (100 MHz,
DMSO-d6) dC (ppm): 21.13 (CH3), 21.31 (CH3), 21.43 (CH3), 36.39
(CH), 57.38 (C–CN), 113.18, 116.88, 119.15, 123.20, 125.38, 126.07,
127.29, 128.14, 128.58, 129.10, 130.39, 130.39, 132.20, 132.20,
132.44, 134.19, 137.23, 139.45, 147.01, 148.47, 152.79, 154.63,
–
154.18, 155.29, 158.38 (Ar–C), 160.40 (C O). Anal. cald. for
–
C29H18ClN3O3S (523.99 g/mol): C, 66.47; H, 3.46; N, 8.02.
–
155.40, 157.78, 158.16 (Ar–C), 160.49 (C O). Anal. cald. for
–
C31H23N3O3S (517.60 g/mol): C, 71.93; H, 4.48; N, 8.12. Found:
Found: C, 66.15; H, 3.69; N, 7.69.
C, 71.59; H, 4.16; N, 8.36.
2-Amino-4-(2-(p-chlorophenylthio)-6-methylquinolin-3-yl)-
5-oxo-9-methyl-4,5-dihydropyrano[3,2-c]chromene-3-
carbonitrile (6n)
2-Amino-4-(2-(p-methylphenylthio)-6-methoxyquinolin-3-
yl)-5-oxo-9-methyl-4,5-dihydropyrano[3,2-c]chromene-3-
carbonitrile (6r)
Yield: 93%; m.p.: 248–2508C; IR (KBr, n, cmꢀ1): 3389 and 3325
(asym. and sym. str. of –NH2), 3044 (Ar–CH str.), 2205 (–C N str.),
Yield: 65%; m.p.: 274–2768C; IR (KBr, n, cmꢀ1): 3410 and 3325
(asym. and sym. str. of –NH2), 3041 (Ar–CH str.), 2210 (–C N str.),
1670 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.41
–
–
1725 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.41
–
–
(s, 3H, CH3), 2.44 (s, 3H, CH3), 5.11 (s, 1H, CH), 7.33–8.19 (m, 13H,
Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.01 (CH3),
21.48 (CH3), 37.36 (CH), 57.05 (C–CN), 113.04, 116.86, 119.36, 119.67,
121.76, 122.65, 126.93, 127.08, 127.74, 129.42, 131.58, 131.58,
132.60, 132.60, 133.47, 134.33, 134.59, 135.45, 135.74, 136.43,
(s, 3H, CH3), 2.46 (s, 3H, CH3), 3.79 (s, 3H, OCH3), 5.17 (s, 1H,
CH), 7.27–8.25 (m, 13H, Ar–HþNH2); 13C-NMR (100 MHz, DMSO-
d6) dC (ppm): 21.25 (CH3), 21.47 (CH3), 35.79 (CH), 55.81 (OCH3),
57.19 (C–CN), 113.23, 117.10, 118.89, 119.27, 122.68, 123.09,
123.48, 125.33, 128.90, 129.12, 129.78, 130.17, 130.17, 133.43,
133.43, 133.58, 135.10, 136.22, 137.10, 139.28, 143.57, 152.23,
–
145.77, 150.95, 154.63, 155.75, 158.61 (Ar–C), 160.14 (C O); MS
–
m/z: 539 [Mþ1]þ. Anal. cald. for C30H20ClN3O3S (538.02 g/mol): C,
–
66.97; H, 3.75; N, 7.81. Found: 67.09; H, 3.96; N, 7.56.
154.05, 157.67, 158.59 (Ar–C), 160.36 (C O). Anal. cald.
–
for C31H23N3O4S (533.60 g/mol): C, 69.78; H, 4.34; N, 7.87.
Found: C, 69.91; H, 4.02; N, 8.01.
2-Amino-4-(2-(p-chlorophenylthio)-6-methoxyquinolin-3-
yl)-5-oxo-9-methyl-4,5-dihydropyrano[3,2-c]chromene-3-
carbonitrile (6o)
Methodology for in vitro antimicrobial screening or
MIC measurement
Yield: 75%; m.p.: 288–2908C; IR (KBr, n, cmꢀ1): 3396 and 3320
The in vitro antimicrobial activities of all the compounds and
standard drugs were assessed against three representatives of
Gram-positive bacteria viz. Streptococcus pneumoniae (MTCC 1936),
Bacillus subtilis (MTCC 441), Clostridium tetani (MTCC 449), three
Gram-negative bacteria viz. Salmonella typhi (MTCC 98), Escherichia
coli (MTCC 443), Vibrio cholerae (MTCC 3906) and two fungi viz.
Candida albicans (MTCC 227) and Aspergillus fumigatus (MTCC 3008)
by the broth microdilution MIC method according to the
National Committee for Clinical Laboratory Standards [14].
The strains employed for the activity were procured from,
MTCC–Micro Type Culture Collection, Institute of Microbial
Technology, Chandigarh. Mueller Hinton Broth was used as
nutrient medium to grow and dilute the compound suspension
for the test bacteria and Sabouraud Dextrose Broth was used for
fungal nutrition. Ampicillin, chloramphenicol, ciprofloxacin
and norfloxacin were used as standard antibacterial drugs,
whereas griseofulvin and nystatin were used as standard anti-
fungal drugs.
(asym. and sym. str. of –NH2), 3022 (Ar–CH str.), 2205 (–C N str.),
–
1
1705 (–C O str.); H-NMR (400 MHz, DMSO-d ) d (ppm): 3.84 (s, 3H,
–
6
H
OCH3), 2.46 (s, 3H, CH3), 5.18 (s, 1H, CH), 7.29–8.18 (m, 13H,
Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.45 (CH3),
37.42 (CH), 55.87 (OCH3), 57.12 (C–CN), 113.18, 116.20, 119.45,
120.07, 121.15, 122.87, 126.80, 127.23, 127.90, 129.11, 131.09,
131.09, 132.34, 132.34, 133.41, 134.67, 134.56, 135.42, 135.08,
136.00, 145.10, 150.94, 154.30, 155.55, 158.17 (Ar-C), 160.29
–
(C O). Anal. cald. for C30H20ClN3O4S (554.02 g/mol): C, 65.04;
–
H, 3.64; N, 7.58. Found: C, 65.28; H, 3.51; N, 7.36.
2-Amino-4-(2-(p-methylphenylthio)quinolin-3-yl)-5-oxo-9-
methyl-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile
(6p)
Yield: 86%; m.p.: 280–2828C; IR (KBr, n, cmꢀ1): 3405 and 3310
(asym. and sym. str. of –NH2), 3035 (Ar–CH str.), 2200 (–C N str.),
1720 (–C O str.); 1H-NMR (400 MHz, DMSO-d6) dH (ppm): 2.40
–
–
(s, 3H, CH3), 2.44 (s, 3H, CH3), 5.15 (s, 1H, CH), 7.21–8.15 (m, 14H,
Ar–HþNH2); 13C-NMR (100 MHz, DMSO-d6) dC (ppm): 21.38 (CH3),
21.42 (CH3), 36.30 (CH), 57.34 (C–CN), 113.30, 116.18, 118.78, 123.39,
125.10, 126.87, 127.55, 128.29, 128.09, 129.15, 130.25, 130.25,
132.41, 132.41, 133.12, 134.35, 137.19, 139.12, 147.02, 148.64,
Bacterial strains were primarily inoculated into Mueller–
Hinton agar and, after overnight growth, a number of colonies
were directly suspended in saline solution until the
turbidity matched the turbidity of the McFarland standard
(approximately 108 CFU/mL), i.e. the inoculum size for the test
strain was adjusted to 108 CFU/mL by comparing the turbidity
(turbidimetric method). Similarly, fungi were inoculated in
Sabouraud Dextrose Broth, the procedures of inoculum
–
152.22, 154.04, 155.20, 157.33, 158.43 (Ar–C), 160.37 (C O). Anal.
–
cald. for C30H21N3O3S (503.57 g/mol): C, 71.55; H, 4.20; N, 8.34.
Found: C, 71.72; H, 4.39; N, 8.63.
ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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322
J. A. Makawana et al.
Arch. Pharm. Chem. Life Sci. 2012, 345, 314–322
standardization were also similar. DMSO was used as diluent/
vehicle to get the desired concentration of synthesized com-
pounds and standard drugs to test the standard microbial
strains, i.e. the compounds were dissolved in DMSO and the
solutions were diluted with culture medium. Each compound
and the standard drugs were diluted obtaining 2000 mg/mL
concentration, as a stock solution. By further progressive
dilutions with the test medium, the required concentrations
were obtained for primary and secondary screening. In primary
screening 1000, 500, and 250 mg/mL concentrations of the
synthesized compounds were taken. The active compounds
found in this primary screening were further diluted to
obtain 200, 125, 100, 62.5 and 50 mg/mL concentrations
for secondary screening to test in a second set of dilution
against all microorganisms. Briefly, the control tube containing
no antibiotic is immediately subcultured [before inoculation] by
spreading a loopful evenly over a quarter of a plate of medium
suitable for the growth of the test organism. The tubes are then
put for incubation at 378C for 24 h for bacteria and 48 h for
fungi. Growth or lack of growth in the tubes containing the
antimicrobial agent was determined by comparison with the
growth control, indicated by turbidity. The lowest concentration
that completely inhibited visible growth of the organism was
recorded as the minimal inhibitory concentration (MIC, mg/mL),
i.e. the amount of growth from the control tube before
incubation (which represents the original inoculum) is com-
pared. A set of tubes containing only seeded broth and the
solvent controls were maintained under identical conditions
so as to make sure that the solvent had no influence on strain
growth. The test mixture should contain 108 CFU/mL organisms.
The interpretation of the results was based on griseofulvin and
nystatin breakpoints for the fungi and based on ampicillin,
chloramphenicol, ciprofloxacin and norfloxacin for bacterial
pathogens.
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The authors are thankful to the Department of Chemistry, Sardar Patel
University for providing research facilities. We are also thankful to
Vaibhav Analytical Laboratory, Ahmedabad for the FT-IR and
Sophisticated Instrumentation Centre for Applied Research and
Training (SICART), Vallabh Vidyanagar for elemental analysis. As well
as Oxygen Healthcare Research Pvt. Ltd., Ahmadabad for providing mass
spectrometry facilities and Dhanji P. Rajani, Microcare Laboratory, Surat
for antimicrobial screening of the compounds reported herein. One of the
authors is grateful to UGC, New Delhi for a Research Fellowship in Sciences
for Meritorious Students.
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The authors have declared no conflict of interest.
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