Synthesis and Antimicrobial Evaluation of Novel Pyrazole-Annulated Oxygen-Containing Macrocycles

Article abstract of DOI:10.1007/s10593-016-1939-y

[Figure not available: see fulltext.] An efficient approach to the synthesis of fused pyrazole-annulated macrocycles has been demonstrated. Vilsmeier–Haack reaction of substituted o-hydroxyacetophenones with phenyl hydrazine followed by reduction of the r

Full text of DOI:10.1007/s10593-016-1939-y

DOI 10.1007/s10593-016-1939-y
Chemistry of Heterocyclic Compounds 2016, 52(8), 609–614
Synthesis and antimicrobial evaluation
of novel pyrazole-annulated oxygen-containing macrocycles
Dongamanti Ashok1*, Mohan Gandhi Devulapally1, Srinivas Gundu1,
Vikas Kumar Aamate1, Shivakanth Chintalapally2
1 Department of Chemistry, Osmania University,
Hyderabad 500 007, India; e-mail: ashokdou@gmail.com
2 Department of Genetics, Osmania University,
Hyderabad 500 007, India; e-mail: cshivakanth@gmail.com
Published in Khimiya Geterotsiklicheskikh Soedinenii,
2016, 52(8), 609–614
Submitted May 10, 2016
Accepted after revision July 13, 2016
O
O
O
R
O
R
R
O
O
N
N
N
N
N
N
R = H, Me, Br
An efficient approach to the synthesis of fused pyrazole-annulated macrocycles has been demonstrated. Vilsmeier–Haack reaction of
substituted o-hydroxyacetophenones with phenyl hydrazine followed by reduction of the resulting pyrazolyl aldehydes yielded the corre-
sponding alcohols. These precursors upon alkylation with dibromoalkanes gave the target library. The structures of the synthesized pro-
ducts were established based on 1H, 13C NMR, IR, and mass spectral data. All the final macrocycles were screened for their antimicrobial
activity. Compounds bearing electron-donating groups show promising antimicrobial activity against the tested strains.
Keywords: macrocycles, pyrazole, Vilsmeier–Haack reagent, antimicrobial activity, dialkylation.
In recent years, macrocyclic compounds have found
a variety of applications in the field of chemistry, biology,
materials science, and nanotechnology.1 Due to their
conformational bias and flexible nature, these molecules
are considered to be efficient molecular ligands for
biological targets.2 Particularly, small macrocyclic rings
with heterocyclic motifs tend to be excellent molecular
ligands because they are known to interact with distinct
protein molecules. Hence, macrocyclic compounds have
potential applications in drug development and discovery.
In addition, some of them act as fluorescent sensors for
chiral molecules and form complexes with small molecules
in host–guest interactions.3,4 There are many macrocyclic
compounds known in the literature with potential bio-
logical activity.5,6
fipronil contain pyrazole framework (Fig. 1). Thus, in the
light of the above findings and in the context of our15
ongoing work regarding the synthesis of new heterocyclic
compounds, we found it an attractive idea to construct new
fused pyrazole-grafted macrocycles. Such compounds are
not only synthetically challenging but may also be vitally
important for pharmacological studies in the development
of new medicinal properties. Therefore, we herein report
the synthesis of a series of novel pyrazole-annulated
oxygen-containing macrocycles (Fig. 1). The synthesized
macrocycles were evaluated for their in vitro antimicrobial
activity. Most of the compounds showed promising
antimicrobial activity against the tested strains.
On the other hand, pyrazole and its derivatives represent
a class of well-known nitrogen-containing heterocyclic
compounds, which occupy an important position in
medicinal and pesticide chemistry with a wide range of
biological activity, such as antimicrobial,7 anticancer,8 anti-
inflammatory,9 antidepressant,10 anticonvulsant,10,11 anti-
hyperglycemic,12 antimetabolite,13 and selective enzyme
inhibitory effects.14 Among the numerous known bio-
logically active molecules of this class, pyraclostrobin and
Figure 1. The proposed macrocycles containing a pyrazole scaffold.
0009-3122/16/52(8)-0609©2016 Springer Science+Business Media New York
609

Chemistry of Heterocyclic Compounds 2016, 52(8), 609–614
Scheme 1
The synthetic route adopted for the preparation of fused
spectrum of compound 7a (in CDCl3) taken as an example,
showed a singlet for the pyrazole ring proton at 7.99 ppm,
and another singlet for the methylene protons at 4.38 ppm.
Two triplets for two methylene groups adjacent to oxygen
atoms appeared at 4.11 and 3.62 ppm, respectively. In
addition, two o-methylene protons gave multiplets in the
ranges of 1.86–1.90 and 1.78–1.82 ppm. The mass
spectrum of compound 7a revealed a peak at m/z 321
corresponding to its [M+H]+ ion.
The newly synthesized compounds 7a–i were screened
in vitro for their antibacterial activity against Staphylococ-
cus aureus (ATCC 9144), Escherichia coli (ATCC 25922),
Klebsiella pneumoniae (ATCC 13048), and Pseudomonas
aeruginosa (ATCC 19660) strains at 100 µg/ml concen-
tration. Ampicillin was employed as the standard antibacte-
rial drug. The results obtained as zone of inhibition in
millimeters are presented in Table 1. Investigation of the
antibacterial efficiency of the synthesized compounds
revealed that most of the tested compounds displayed some
inhibitory effects on the growth of the tested Gram-positive
pyrazole-grafted macrocycles is depicted in Scheme 1. The
synthetic strategy begins with the condensation of
substituted o-hydroxyacetophenones 1a–c with phenyl-
hydrazine (2) to efficiently provide the hydrazones 3a–c.
These derivatives 3a–c were purified and transformed into
the corresponding 3-(2-hydroxyaryl)-1-phenyl-1H-pyrazole-
4-carbaldehydes 4a–c by using the Vilsmeier–Haack
reagent.16 Pyrazole aldehydes were reduced to the cor-
responding alcohols 5a–c by the action of NaBH4 in
methanol at room temperature. The structures of com-
pounds 5a–c were confirmed on the basis of spectroscopic
data. The obtained substituted 2-[4-(hydroxymethyl)-
1-phenyl-1H-pyrazol-3-yl]phenols 5a–c were subjected to
dialkylation with dibromoalkanes 6a–c in the presence of
sodium hydride for 24 h in DMF to afford the required
fused macrocycles containing pyrazole framework 7a–i in
moderate to good yields.
All the synthesized macrocycles were characterized by
1
1H, 13C NMR, IR, and mass spectral data. The H NMR
Table 1. Antimicrobial activity of macrocycles 7a–i, expressed as zone of inhibition in mm*
Bacterial strains
Compound
Fungal strains
F. oxysporum
S. aureus
K. pneumoniae
E. coli
P. aeruginosa
A. flavus
4.0
8.0
4.5
6.0
4.5
3.0
12.5
8.0
4.5
15.5
8.0
17.0
–
6.0
12.0
8.5
5.0
10.0
7.5
<2.0
2.5
<2.0
3.5
2.0
3.5
5.0
2.0
2.5
6.0
<2.0
–
7a
7b
6.0
<2.0
4.0
7c
5.5
9.5
8.5
7d
15.0
10.5
8.0
22.5
15.0
8.0
16.5
11.5
11.0
21.0
15.5
25.0
–
4.5
7e
<2.0
<2.0
5.5
7f
7g
18.0
10.0
20.0
–
27.0
9.5
7h
7i
<2.0
–
Ampicillin
Amphotericin B
33.0
–
16.4
18.6
* 10 μl of ampicillin (0.1 mg/ml) was used as a positive control. DMSO (10 μl of 0.8% aqueous solution) was used as negative control.
610

Chemistry of Heterocyclic Compounds 2016, 52(8), 609–614
and Gram-negative bacterial strains. It is evident from
and then POCl3 (0.03 mol) was added dropwise at 0–5°C.
After the addition of POCl3 was finished, the reaction
mixture was stirred at room temperature for 24 h. After
completion of the reaction (monitored by TLC), the
reaction mixture was poured onto crushed ice and then
neutralized with 10% aqueous NaOH solution. The
precipitate was filtered off, thoroughly washed with water,
and recrystallized from ethanol.
Table 1 that compounds 7e,h having an electron-donating
group (methyl) at the fused benzene ring demonstrated a
good zone of inhibition against all the bacterial strains
compared to the standard. The remaining compounds were
characterized by a smaller zone of inhibition against all the
bacterial strains.
We have also tested the antifungal activity of these new
macrocyclic compounds against two fungal strains, Fusa-
rium oxysporum and Aspergillus flavus. The results of the
antifungal screening were compared to the standard anti-
fungal drug amphotericin B. All the macrocyclic com-
pounds 7a–i demonstrated low inhibitory activity against
the tested fungal strains at 200 µg/ml concentration.
3-(2-Hydroxyphenyl)-1-phenyl-1H-pyrazole-4-carb-
aldehyde (4a). Yield 0.90 g (65%), light-yellow solid, mp
98–100°C. IR spectrum, ν, cm–1: 3125 (OH), 2866, 1690
(CHO), 1529, 1500, 1249, 1210. 1H NMR spectrum,
δ, ppm (J, Hz): 7.01–7.05 (1H, m, H Ar); 7.12 (1H, d,
J = 1.0, H Ar); 7.35–7.39 (1H, m, H Ar); 7.42–7.46 (1H,
m, H Ar); 7.53–7.57 (2H, m, H Ar); 7.72–7.74 (2H, m,
H Ar); 7.93–7.95 (1H, m, H Ar); 8.59 (1H, s, H pyrazole);
10.08 (1H, s, CHO); 10.20 (1H, s, OH). 13C NMR spectrum,
δ, ppm: 114.8; 117.8; 119.1; 119.9; 124.1; 126.8; 129.5; 130.1;
130.3; 132.3; 139.8; 150.6; 155.1; 183.3 (CHO). Mass spectrum,
m/z: 265 [M+H]+. Found, %: C 72.68; H 4.56; N 10.54.
C16H12N2O2. Calculated, %: C 72.72; H 4.58; N 10.60.
3-(2-Hydroxy-5-methylphenyl)-1-phenyl-1H-pyrazole-
4-carbaldehyde (4b). Yield 0.69 g (50%), yellow solid,
mp 58–60°C. IR spectrum, ν, cm–1: 3120 (OH), 2856, 1686
Thus, we have developed an efficient protocol for the
synthesis of fused pyrazole macrocycles containing two
oxygen atoms with moderate to good yields. These macro-
cycles are relatively accessible for further studies because
they can be obtained through a facile, three-step synthesis
with commercially available and relatively inexpensive
chemicals. These pyrazole-fused macrocycles have been
evaluated for their antimicrobial activity. Among the
synthesized compounds, 14-methyl-2-phenyl-2,4,7,8,9,10-
hexahydro-2H-benzo[5,6][1,7]dioxacyclododecino[4,3-c]-
pyrazole and 15-methyl-2-phenyl-2,4,6,7,8,9,10,11-octahydro-
benzo[5,6][1,7]dioxacyclotridecino[4,3-c]pyrazole having
an electron-donating methyl substituent in the phenyl ring
demonstrated good zone of inhibition against all the bacte-
rial strains compared to ampicillin. The rest of the com-
pounds showed moderate antimicrobial activity against all
tested organisms. The experimental results of this study will
likely provide a new basis for the design of interesting macro-
cycles during further studies, including the design of new
analogs of these macrocycles with various biological activities.
1
(CHO), 1514, 1235, 1201. H NMR spectrum, δ, ppm
(J, Hz): 2.37 (3H, s, CH3); 7.02 (1H, d, J = 8.3, H Ar); 7.17–
7.19 (1H, m, H Ar); 7.35–7.36 (1H, m, H Ar); 7.41–7.45
(1H, m, H Ar); 7.52–7.56 (1H, m, H Ar); 7.72–7.74 (2H,
m, H Ar); 7.83–7.84 (1H, m, H Ar); 8.59 (1H, s,
H pyrazole); 9.78 (1H, s, OH); 10.11 (1H, s, CHO).
13C NMR spectrum, δ, ppm: 21.7 (CH3); 113.0; 117.4;
119.8; 120.5; 121.5; 128.5; 129.3; 131.4; 131.9; 132.8;
139.7; 151.6; 155.2; 184.5 (CHO). Mass spectrum, m/z:
279 [M+H]+. Found, %: C 73.30; H 4.99; N 10.00.
C17H14N2O2. Calculated, %: C 73.37; H 5.07; N 10.07.
3-(5-Bromo-2-hydroxyphenyl)-1-phenyl-1H-pyrazole-
4-carbaldehyde (4c). Yield 0.74 g (55%), yellow solid, mp
120–122°C. IR spectrum, ν, cm–1: 3133 (OH), 2878, 1696
(CHO), 1535, 1506, 1254, 1218. 1H NMR spectrum,
δ, ppm (J, Hz): 7.00 (1H, d, J = 8.8, H Ar); 7.43–7.48 (2H,
m, H Ar); 7.54–7.58 (2H, m, H Ar); 7.71–7.73 (2H, m,
H Ar); 8.23 (1H, d, J = 2.3, H Ar); 8.59 (1H, s, H pyrazole);
10.18 (1H, s, CHO); 10.20 (1H, s, OH). 13C NMR
spectrum, δ, ppm: 111.6; 117.1; 119.2; 119.7; 123.1; 128.7;
130.0; 132.0; 133.4; 133.8; 138.0; 151.2; 155.2; 183.6
(CHO). Mass spectrum, m/z: 343 [M+H]+. Found, %:
C 55.83; H 3.11; N 8.13. C16H11BrN2O2. Calculated, %:
C 56.00; H 3.23; N 8.16.
Experimental
IR spectra were recorded on a Shimadzu FTIR-8400S
1
spectrometer. H and 13C NMR spectra were acquired on a
Bruker Avance 400 spectrometer (400 and 100 MHz,
respectively) in CDCl3 using TMS as internal standard.
Mass spectra were recorded on a Shimadzu GCMS-
QP1000 spectrometer. Elemental analyses were performed
on a Carlo Erba EA1106 elemental analyzer. Melting
points were determined in open capillary tubes on a Stuart
SMP3 melting point apparatus and are uncorrected.
Analytical TLC was performed on precoated Merck 60
F254 silica gel plates, visualization by exposing to iodine
vapor and under UV light. All the reagents and solvents
were purchased from commercial sources.
Conversion of 4-formylpyrazoles 4a–c into respective
pyrazole-2-phenols 5a–c (General method). Sodium boro-
hydride (0.017 g, 0.94 mmol) was added slowly with
stirring to a solution of 4-formylpyrazole 4a–c (0.94 mmol)
in MeOH (5 ml) at 0°C. The reaction mixture was stirred
for 1 h at room temperature. The reaction progress was
monitored by TLC. After completion of the reaction, the
mixture was poured into the ice-cold water. After 15 min, it
was extracted with dichloromethane (3×10 ml) and dried
over Na2SO4, and the solvent was removed under reduced
pressure to give the corresponding alcohol 5a–c.
Synthesis of formylpyrazoles 4a–c as per modified
literature procedure.16 Step 1. Phenylhydrazine (2) (2.7 g,
1.7 ml, 24 mmol) was added to a solution of the appropriate
2-hydroxyacetophenone 1a–c (24 mmol) in methanol (20 ml).
The mixture was refluxed for 2 h in the presence of acetic
acid (1.5 ml). After cooling of the reaction mixture, the
phenylhydrazone intermediate crystallized and was filtered
off.
Step 2. The appropriate 2-hydroxyacetophenone phenyl-
hydrazone 3a–c (0.01 mol) was dissolved in DMF (15 ml)
611

Chemistry of Heterocyclic Compounds 2016, 52(8), 609–614
CH2); 1.86–1.90 (2H, m, CH2); 3.62 (2H, t, J = 5.5, OCH2);
2-[4-(Hydroxymethyl)-1-phenyl-1H-pyrazol-3-yl]phenol
(5a). Yield 0.49 g (98%), yellow solid, mp 108–110°C.
IR spectrum, ν, cm–1: 3433 (OH), 3327 (CH2–OH), 2924,
4.09–4.12 (2H, t, J = 4.5, OCH2); 4.38 (2H, s, ArCH2O);
6.93 (1H, d, J = 8.3, H Ar); 6.99–7.02 (1H, m, H Ar); 7.27–
7.28 (1H, m, H Ar); 7.34–7.38 (1H, m, H Ar); 7.41–7.45
(2H, m, H Ar); 7.52 (1H, dd, J = 1.5, J = 6.0, H Ar); 7.75–
7.75 (2H, m, H Ar); 7.99 (1H, s, H pyrazole). 13C NMR
spectrum, δ, ppm: 25.6; 27.6; 61.5; 67.8; 68.6; 111.0;
118.8; 119.4; 120.1; 122.3; 126.1; 128.0; 129.3; 129.8;
131.4; 140.0; 151.2; 157.1. Mass spectrum, m/z: 321
[M+H]+. Found, %: C 74.94; H 6.25; N 8.70. C20H20N2O2.
Calculated, %: C 74.98; H 6.29; N 8.74.
1
2853, 1597, 1503, 1391, 1359. H NMR spectrum, δ, ppm
(J, Hz): 4.87 (2H, s, CH2OH); 6.95–6.99 (1H, m, H Ar);
7.08 (1H, dd, J = 1.0, J = 7.3, H Ar); 7.27–7.34 (2H, m,
H Ar); 7.45–7.49 (2H, m, H Ar); 7.64–7.66 (2H, m, H Ar);
7.74 (1H, dd, J = 1.5, J = 6.3, H Ar); 8.02 (1H, s, H pyrazole).
13C NMR spectrum, δ, ppm: 55.2 (CH2OH); 117.2; 117.9;
119.3; 119.5; 120.5; 121.1; 124.2; 126.5; 129.5; 132.1;
140.1; 149.2; 155.1. Mass spectrum, m/z (Irel, %): 267
[M+H]+ (100). Found, %: C 72.11; H 5.25; N 10.48.
C16H14N2O2. Calculated, %: C 72.17; H 5.30; N 10.52.
2-[4-(Hydroxymethyl)-1-phenyl-1H-pyrazol-3-yl]-
4-methylphenol (5b). Yield 0.49 g (97%), light-yellow
solid, mp 110–112°C. IR spectrum, ν, cm–1: 3428 (OH),
13-Methyl-2-phenyl-2,4,6,7,8,9-hexahydro[1,6]benzo-
dioxacycloundecino[9,8-c]pyrazole (7b). Yield 0.25 g (72%),
light-yellow solid, mp 88–90°C. IR spectrum, ν, cm–1: 2923,
1
2866, 1665, 1545, 1396, 1377, 1238, 755, 689. H NMR
spectrum, δ, ppm (J, Hz): 1.81–1.86 (2H, m, CH2); 1.90–
1.94 (2H, m, CH2); 2.34 (3H, s, CH3); 3.65 (2H, t, J = 5.0,
OCH2); 4.14 (2H, t, J = 4.5, OCH2); 4.42 (2H, s, ArCH2O);
6.94 (1H, d, J = 8.3, H Ar); 7.03–7.05 (1H, m, H Ar); 7.28–
7.30 (1H, m, H Ar); 7.39–7.44 (1H, m, H Ar); 7.48–7.50
(1H, m, H Ar); 7.54 (1H, dd, J = 1.5, J = 6.0, H Ar); 7.75–
7.78 (2H, m, H Ar); 7.96 (1H, s, H pyrazole). 13C NMR
spectrum, δ, ppm: 21.5; 24.8; 27.2; 60.8; 66.8; 67.9; 110.6;
118.5; 119.1; 120.6; 122.0; 125.8; 128.2; 129.3; 130.6;
131.4; 139.7; 150.1; 156.1. Mass spectrum, m/z: 335
[M+H]+. Found, %: C 75.38; H 6.58; N 8.34. C21H22N2O2.
Calculated, %: C 75.42; H 6.63; N 8.38.
1
3315 (CH2–OH), 2918, 2849, 1588, 1389, 1249. H NMR
spectrum, δ, ppm (J, Hz): 2.32 (3H, s, CH3); 4.86 (2H, s,
CH2OH); 6.97 (1H, d, J = 8.3, H Ar); 7.06–7.08 (1H, m, H Ar);
7.29–7.33 (1H, m, H Ar); 7.44–7.48 (3H, m, H Ar); 7.61–
7.63 (2H, m, H Ar); 7.75 (1H, dd, J = 1.5, J = 6.3, H Ar); 7.99
(1H, s, H pyrazole); 10.65 (1H, s, OH). 13C NMR spectrum,
δ, ppm: 20.7 (CH3); 56.5 (CH2OH); 116.3; 116.8; 118.6;
121.1; 126.8; 127.7; 128.0; 128.5; 129.6; 130.3; 138.9;
149.8; 153.7. Mass spectrum, m/z: 281 [M+H]+. Found, %:
C 72.80; H 5.70; N 9.95. C17H16N2O2. Calculated, %:
C 72.84; H 5.75; N 9.99.
4-Bromo-2-[4-(hydroxymethyl)-1-phenyl-1H-pyrazol-
3-yl]phenol (5c). Yield 0.48 g (96%), yellow solid, mp 118–
120°C. IR spectrum, ν, cm–1: 3445 (OH), 3335 (CH2–OH),
13-Bromo-2-phenyl-2,4,6,7,8,9-hexahydro[1,6]benzodi-
oxacycloundecino[9,8-c]pyrazole (7c). Yield 0.20 g (71%),
yellow solid, mp 82–84°C. IR spectrum, ν, cm–1: 3344,
1
1
2933, 2868, 1601, 1515, 1397, 1364. H NMR spectrum,
2870, 1615, 1519, 1356, 1315, 1045, 765, 665. H NMR
δ, ppm (J, Hz): 4.87 (2H, d, J = 4.0, CH2OH); 6.97 (1H, d,
J = 8.8, H Ar); 7.33–7.37 (2H, m, H Ar); 7.48–7.52 (2H,
m, H Ar); 7.64–7.67 (2H, m, H Ar); 7.90 (1H, dd, J = 1.5,
J = 7.8, H Ar); 8.06 (1H, s, H pyrazole); 10.91 (1H, s, OH).
13C NMR spectrum, δ, ppm: 56.2 (CH2OH); 111.2; 118.4;
118.8; 119.1; 121.0; 127.2; 128.1; 129.7; 130.3; 132.2;
138.8; 148.8; 155.2. Mass spectrum, m/z: 344 [M+H]+.
Found, %: C 55.62; H 3.76; N 8.07. C16H13BrN2O2. Calcu-
lated, %: C 55.67; H 3.80; N 8.12.
Synthesis of macrocycles 7a–i (General method).
Catalytic amount of sodium hydride (60% suspension in
mineral oil, 20 mg, 1.1 mmol) was added to a well stirred
solution of compound 5a–c (0.375 mmol) in DMF (5 ml)
under nitrogen atmosphere upon cooling. Dibromoalkane
6a–c (0.375 mmol) was added, and the reaction mixture
was stirred under room temperature for 24 h. The reaction
progress was monitored by TLC (hexane–EtOAc, 7:3).
After completion of the reaction, the mixture was poured
into the ice-cold water and extracted with ethyl acetate. The
combined organic layers were dried over Na2SO4 and
concentrated in vacuum. The crude product was purified by
column chromatography using hexane–ethyl acetate, 8:2, as
an eluent to afford compound 7a–i.
spectrum, δ, ppm (J, Hz): 1.77–1.82 (2H, m, CH2); 1.87–
1.92 (2H, m, CH2); 3.60 (2H, t, J = 5.1, OCH2); 4.10 (2H, t,
J = 4.5, OCH2); 4.40 (2H, s, ArCH2O); 6.92 (1H, d, J = 8.3,
H Ar); 7.03–7.05 (1H, m, H Ar); 7.27–7.28 (1H, m, H Ar);
7.34–7.35 (1H, m, H Ar); 7.43–7.45 (1H, m, H Ar); 7.51
(1H, dd, J = 1.5, J = 6.0, H Ar); 7.74–7.78 (2H, m, H Ar);
8.00 (1H, s, H pyrazole). 13C NMR spectrum, δ, ppm: 25.8;
27.6; 61.7; 66.8; 68.8; 111.5; 118.8; 119.5; 120.4; 121.8;
124.8; 127.5; 129.4; 131.4; 132.5; 140.2; 151.6; 156.1.
Mass spectrum, m/z: 399 [M+H]+. Found, %: C 60.10;
H 4.75; N 6.97. C20H19BrN2O2. Calculated, %: C 60.16;
H 4.80; N 7.02.
2-Phenyl-2,4,7,8,9,10-hexahydro-6H-[1,7]benzodioxa-
cyclododecino[10,9-c]pyrazole (7d). Yield 0.19 g (68%),
light-yellow solid, mp 100–102°C. IR spectrum, ν, cm–1:
1
2919, 1600, 1503, 1459, 1242, 1066, 958, 751, 689. H
NMR spectrum, δ, ppm (J, Hz): 1.60–1.65 (2H, m,
CH2CH2CH2); 1.70–1.76 (2H, m, CH2CH2CH2); 1.81–1.86
(2H, m, CH2CH2CH2); 3.66 (2H, t, J = 7.0, OCH2); 4.05
(2H, t, J = 4.5, OCH2); 4.40 (2H, s, ArCH2O); 6.95–7.04
(2H, m, H Ar); 7.28–7.29 (2H, m, H Ar); 7.40–7.46 (3H,
m, H Ar); 7.75–7.77 (2H, m, H Ar); 8.09 (1H, s,
H pyrazole). 13C NMR spectrum, δ, ppm: 17.0; 28.0; 28.4;
66.1; 69.7; 70.6; 116.4; 117.2; 119.0; 119.9; 120.8; 123.0;
126.2; 129.1; 129.3; 130.7; 139.7; 149.9; 154.1. Mass
spectrum, m/z: 335 [M+H]+. Found, %: C 75.38; H 6.60;
N 8.32. C21H22N2O2. Calculated, %: C 75.42; H 6.63;
N 8.38.
2-Phenyl-2,4,6,7,8,9-hexahydro[1,6]benzodioxacyclo-
undecino[9,8-c]pyrazole (7a). Yield 0.20 g (70%), light-
yellow solid, mp 85–87°C. IR spectrum, ν, cm–1: 3345,
2939, 2876, 1616, 1535, 1376, 1356, 1012, 892, 699.
1H NMR spectrum, δ, ppm (J, Hz): 1.78–1.82 (2H, m,
612

Chemistry of Heterocyclic Compounds 2016, 52(8), 609–614
14-Methyl-2-phenyl-2,4,7,8,9,10-hexahydro-6H-[1,7]-
119.9; 123.4; 126.2; 129.3; 129.6; 130.5; 131.1; 139.7;
149.9; 151.1. Mass spectrum, m/z: 363 [M+H]+. Found, %:
C 76.15; H 7.20; N 7.70. C23H26N2O2. Calculated, %:
C 76.21; H 7.23; N 7.73.
benzodioxacyclododecino[10,9-c]pyrazole (7e). Yield
0.17 g (66%), white solid, mp 94–97°C. IR spectrum, ν, cm–1:
2944, 1611, 1515, 1465, 1254, 1069, 945, 739, 669. 1H NMR
spectrum, δ, ppm (J, Hz): 1.59–1.62 (2H, m, CH2CH2CH2);
1.67–1.74 (2H, m, CH2CH2CH2); 1.80–1.85 (2H, m,
CH2CH2CH2); 2.31 (3H, s, CH3); 3.64 (2H, t, J = 7.0,
OCH2); 4.03 (2H, t, J = 4.5, OCH2); 4.35 (2H, s, ArCH2O);
6.92–6.94 (1H, m, H Ar); 6.96–7.00 (2H, m, H Ar); 7.27–7.29
(1H, m, H Ar); 7.33–7.36 (1H, m, H Ar); 7.39–7.44 (2H, m,
H Ar); 7.72–7.74 (1H, m, H Ar); 8.00 (1H, s, H pyrazole).
13C NMR spectrum, δ, ppm: 15.2; 21.6; 28.4; 28.8; 66.0;
70.8; 71.6; 113.3; 117.2; 118.9; 119.0; 123.4; 126.2; 129.3;
129.6; 130.5; 131.1; 139.7; 150.1; 153.2. Mass spectrum,
m/z: 349 [M+H]+. Found, %: C 75.80; H 6.90; N 8.00.
C22H24N2O2. Calculated, %: C 75.83; H 6.94; N 8.04.
15-Bromo-2-phenyl-2,4,6,7,8,9,10,11-octahydrobenzo-
[1,7]dioxacyclotridecino[11,10-c]pyrazole (7i). Yield 0.23 g
(72%), brown solid, mp 92–95°C. IR spectrum, ν, cm–1: 3338,
2961, 2845, 1615, 1462, 1242, 1121, 1032, 744, 695.
1H NMR spectrum, δ, ppm (J, Hz): 1.28–1.43 (4H, m,
2CH2); 1.56–1.65 (2H, m, CH2); 1.68–1.72 (2H, m, CH2);
3.45 (2H, t, J = 7.0, OCH2); 4.02 (2H, t, J = 4.5, OCH2);
4.33 (2H, s, ArCH2O); 6.84 (1H, d, J = 8.7, H Ar); 7.27–
7.28 (1H, m, H Ar); 7.40–7.46 (4H, m, H Ar); 7.75 (2H, d,
J = 7.8, H Ar); 7.99 (1H, s, H pyrazole). 13C NMR
spectrum, δ, ppm: 21.6; 22.3; 27.0; 27.7; 29.7; 62.2; 66.1;
66.2; 112.0; 113.7; 119.0; 124.3; 126.3; 127.6; 129.3;
132.5; 134.1; 139.9; 149.7; 157.1. Mass spectrum, m/z: 427
[M+H]+. Found, %: C 61.78; H 5.40; N 6.06. C22H23BrN2O2.
Calculated, %: C 61.83; H 5.42; N 6.11.
Antimicrobial studies of the synthesized compounds 7a–i.
In vitro antimicrobial studies were carried out by agar well
diffusion method against test organisms.17,18 Nutrient broth
(NB) plates were swabbed with 24-h old broth culture (100 ml)
of test bacteria. Using a sterile cork borer, wells (6 mm)
were made in each Petri plate. Test samples in DMSO
(100 µg/ml) were added into the wells by using sterile
pipettes. Simultaneously, the standard antibiotics (ampi-
cillin for antibacterial activity, amphotericin B for anti-
fungal activity) were tested against the microorganisms.
The plates were incubated at 37°C for 24 h. After appro-
priate incubation, the diameter of inhibition zone around
each well was measured. Duplicates were maintained and
the average values were calculated for finding the
antibacterial as well as antifungal activity. The 24-h old
cultures of the test bacteria S. aureus (ATCC 9144), E. coli
(ATCC 25922), K. pneumoniae (ATCC 13048), and
P. aeruginosa (ATCC 19660) were diluted 100-fold in
nutrient broth (100 ml bacterial cultures in 10 l NB). All
the tubes were incubated at 37°C for 24 h for bacteria and
at 28°C for 48 h for fungi.
14-Bromo-2-phenyl-2,4,7,8,9,10-hexahydro-6H-[1,7]-
benzodioxacyclododecino[10,9-c]pyrazole (7f). Yield
0.20 g (70%), light-yellow solid, mp 98–100°C. IR spectrum,
ν, cm–1: 3015, 1632, 1520, 1489, 1233, 1071, 965, 746,
683. 1H NMR spectrum, δ, ppm (J, Hz): 1.60–1.65 (2H, m,
CH2CH2CH2); 1.70–1.76 (2H, m, CH2CH2CH2); 1.81–1.86
(2H, m, CH2CH2CH2); 3.66 (2H, t, J = 7.0, OCH2); 4.05
(2H, t, J = 4.5, OCH2), 4.40 (2H, s, ArCH2O); 6.96 (1H, d,
J = 8.3, H Ar); 7.27–7.28 (2H, m, H Ar); 7.35–7.40 (1H,
m, H Ar); 7.42–7.45 (2H, m, H Ar); 7.75–7.77 (2H, m, H Ar);
8.09 (1H, s, H pyrazole). 13C NMR spectrum, δ, ppm: 22.7;
28.4; 29.7; 59.8; 66.0; 68.8; 112.8; 117.2; 118.8; 119.9;
120.7; 124.2; 126.4; 129.4; 132.4; 134.6; 139.5; 149.5;
155.8. Mass spectrum, m/z: 413 [M+H]+. Found, %:
C 61.00; H 5.09; N 6.74. C21H21BrN2O2. Calculated, %:
C 61.03; H 5.12; N 6.78.
2-Phenyl-2,4,6,7,8,9,10,11-octahydrobenzo[1,8]dioxa-
cyclotridecino[11,10-c]pyrazole (7g). Yield 0.23 g (72%),
white solid, mp 85–87°C. IR spectrum, ν, cm–1: 3325,
2943, 2832, 1602, 1451, 1252, 1116, 1023, 758, 670.
1H NMR spectrum, δ, ppm (J, Hz): 1.37–1.40 (4H, m,
2CH2); 1.57–1.61 (2H, m, CH2); 1.71–1.75 (2H, m, CH2);
3.48 (2H, t, J = 5.5, OCH2); 4.07 (2H, t, J = 5.5, OCH2);
4.36 (2H, s, ArCH2O); 6.98–7.02 (2H, m, H Ar); 7.28–7.31
(2H, m, H Ar); 7.35–7.40 (1H, m, H Ar); 7.43–7.47 (2H, m,
H Ar); 7.79 (2H, d, J = 7.8, H Ar); 8.02 (1H, s, H pyrazole).
13C NMR spectrum, δ, ppm: 21.6; 22.3; 27.1; 27.7; 62.3;
65.7; 65.9; 112.1; 118.9; 119.0; 119.9; 122.2; 126.1; 127.5;
129.3; 129.8; 131.5; 140.0; 151.1; 157.8. Mass spectrum, m/z:
349 [M+H]+. Found, %: C 75.75; H 6.90; N 8.00.
C22H24N2O2. Calculated, %: C 75.83; H 6.94; N 8.04.
Supplementary information file containing 1H and 13C NMR
spectra is available at http://link.springer.com/journal/10593.
The authors are grateful to Department of Chemistry,
Osmania University for providing laboratory facilities and
the Central Facility for Research and Development, OU for
providing spectral analysis. One of the authors, Mohan
Gandhi Devulapally, is thankful to UGC-New Delhi for
granting Senior Research Fellowship.
15-Methyl-2-phenyl-2,4,6,7,8,9,10,11-octahydrobenzo-
[1,7]dioxacyclotridecino[11,10-c]pyrazole (7h). Yield
0.25 g (74%), white solid, mp 82–84°C. IR spectrum, ν, cm–1:
3315, 2932, 2816, 1594, 1423, 1225, 1153, 1034, 735, 663.
1H NMR spectrum, δ, ppm (J, Hz): 1.35–1.39 (4H, m,
2CH2); 1.57–1.61 (2H, m, CH2); 1.71–1.74 (2H, m, CH2);
2.34 (3H, s, CH3); 3.48 (2H, t, J = 5.5, OCH2); 4.07 (2H, t,
J = 5.5, OCH2); 4.36 (2H, s, ArCH2O); 7.00 (1H, t, J = 8.3,
H Ar); 7.28–7.30 (1H, m, H Ar); 7.35–7.40 (1H, m, H Ar);
7.43–7.47 (3H, m, H Ar); 7.78 (2H, d, J = 7.8, H Ar); 8.02
(1H, s, H pyrazole). 13C NMR spectrum, δ, ppm: 21.8; 25.0;
25.5; 27.8; 28.0; 66.2; 69.7; 71.6; 113.3; 117.2; 118.9;
References
1. Balzani, V.; Credi, A.; Raymo, F. M.; Stoddart, J. F. Angew.
Chem., Int. Ed. 2000, 39, 3348.
2. Schreiber, S. L. Science 2000, 287, 1964.
3. Lodeiro, C.; Capelo, J. L.; Mejuto, J. C.; Oliveira, E.;
Santos, H. M.; Pedras, B.; Núñez, C. Chem. Soc. Rev. 2010,
39, 2948.
4. Bazzicalupi, C.; Bencini, A.; Matera, I.; Puccioni, S.;
Valtancoli, B. Inorg. Chim. Acta. 2012, 381, 162.
613

Chemistry of Heterocyclic Compounds 2016, 52(8), 609–614
5. Andersen, O. A; Nathubhai, A.; Dixon, M. J.; Eggleston, I. M.;
12. Kees, K. L.; Fitzgerald, J. J., Jr.; Steiner, K. E.; Mattes, J. F.;
Mihan, B.; Tosi, T.; Mondoro, D.; McCaleb, M. L. J. Med.
Chem. 1996, 39, 3920.
van Aalten, D. M. F. Chem. Biol. 2008, 15, 295.
6. Rush, C. L; Schüttelkopf, A. W.; Hurtado-Guerrero, R.;
Blair, D. E.; Ibrahim, A. F. M.; Desvergnes, S.; Eggleston, I. M.;
van Aalten, D. M. F. Chem Biol. 2010, 17, 1275.
7. Sharshira, E. M.; Hamada N. M. M. Molecules 2012, 17,
4962.
13. Schmidt, P.; Eichenberger, K.; Wilhelm, M. Angew. Chem.
1961, 73, 15.
14. Wächter, G. A.; Hartmann, R. W.; Sergejew, T.; Grün, G. L.;
Ledergerber, D. J. Med. Chem. 1996, 39, 834.
15. Dongamanti, A.; Aamate, V. K.; Devulapally, M. G.; Gundu, S.;
Kotni, M. K.; Manga, V.; Balasubramanian, S.; Ernala, P.
Bioorg. Med. Chem. Lett. 2015, 25, 898.
16. Rathelot, P.; Azas, N.; El-Kashef, H.; Delmas, F.; Di Giorgio, C.;
Timon-David, P.; Maldonado, J.; Vanelle, P. Eur. J. Med.
Chem. 2002, 37, 671.
8. Magedov, I. V.; Manpadi, M.; Van slambrouck, S.;
Steelant, W. F. A.; Rozhkova, E.; Przheval'skii, N. M.;
Rogelj, S.; Kornienko, A. J. Med. Chem. 2007, 50, 5183.
9. Rovnyak, G. C.; Millonig, R. C.; Schwartz, J.; Shu, V.
J. Med. Chem. 1982, 25, 1482.
10. Palaska, E.; Aytemir, M.; Uzbay, I. T.; Erol, D. Eur. J. Med.
Chem. 2001, 36, 539.
11. Ozdemir, Z.; Kandilci, H. B.; Gumusel, B.; Calis, U.;
Bilgin, A. A. Eur. J. Med. Chem. 2007, 42, 373.
17. Chung, K. T.; Thomasson, W. R.; Wu-Yuan, C. D. J. Appl.
Bacteriol. 1990, 69, 498.
18. Azoro, C. World J. Biotechnol. 2002, 3, 347.
614