Synthesis and myorelaxant activity of fused 1,4-dihydropyridines on isolated rabbit gastric fundus

Article abstract of DOI:10.1002/ddr.21024

Strategy, Management and Health Policy Preclinical Research In the present study, 25 novel condensed 1,4-dihydropyridine (DHP) derivatives bearing cyclopentane, cyclohexane, or tetrahydrothiopene ring with a bulky and lipophilic moiety (3-pyridylmethyl) in the ester group were synthesized via a modified Hantzsch reaction, and their calcium channel modulator activities were assayed on isolated rabbit gastric fundus smooth muscle strips. To evaluate the myorelaxant effects of the compounds, the maximum relaxant response (Emax) and pD ₂ values were calculated. The results indicated that all compounds produced concentration-dependent relaxation and the introduction of five- or six-membered rings to the DHP nucleus and 3-pyridiylmethyl moiety to the ester group led to potent calcium antagonists.

Full text of DOI:10.1002/ddr.21024

DRUG DEVELOPMENT RESEARCH •• : ••–•• (2012)
Research Article
Synthesis and Myorelaxant Activity of Fused
1,4-Dihydropyridines on Isolated Rabbit Gastric Fundus
1
1
2
1
2
˙
˙
Cihat S¸afak, * Miyase Gözde Gündüz, Sevil Özger Ilhan, Rahime S¸ims¸ek, Fatma Is¸li,
S¸eniz Yıldırım,2 Gökçe Sevim Öztürk Fincan,2 Yusuf Sarıog˘lu,2 and Anthony Linden3
1Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hacettepe University,
Ankara 06100, Turkey
2Department of Pharmacology, Faculty of Medicine, Gazi University, Ankara 06500, Turkey
3Institute of Organic Chemistry, University of Zurich, CH-8057, Zurich, Switzerland
Strategy, Management and Health Policy
Enabling
Preclinical Development Clinical Development
Technology,
Genomics,
Proteomics
Preclinical
Research
Toxicology, Formulation
Drug Delivery,
Pharmacokinetics
Phases I-III
Regulatory, Quality,
Manufacturing
Postmarketing
Phase IV
ABSTRACT
In the present study, 25 novel condensed 1,4-dihydropyridine (DHP) derivatives bearing
cyclopentane, cyclohexane, or tetrahydrothiopene ring with a bulky and lipophilic moiety (3-pyridylmethyl)
in the ester group were synthesized via a modified Hantzsch reaction, and their calcium channel modulator
activities were assayed on isolated rabbit gastric fundus smooth muscle strips. To evaluate the myorelaxant
effects of the compounds, the maximum relaxant response (Emax) and pD2 values were calculated. The
results indicated that all compounds produced concentration-dependent relaxation and the introduction of
five- or six-membered rings to the DHP nucleus and 3-pyridiylmethyl moiety to the ester group led to potent
calcium antagonists. Drug Dev Res •• : ••–••, 2012.
© 2012 Wiley Periodicals, Inc.
Key words: condensed 1,4-dihydropyridine; calcium channel modulator; myorelaxant activity
INTRODUCTION
modifications have been carried out on the structure of
nifedipine, the prototype of DHPs (Fig. 1), in order
to enhance calcium modulating effects and lead new
active compounds [Gordeev et al., 1998].
Some studies indicated that racemic hexahydro-
quinolines, indenopyridines, acridines, and furoquino-
lines, which are the condensed ring systems bearing
DHP structure, exhibited calcium antagonist effects
[Rose, 1990; S¸ims¸ek et al., 2003, 2008; Tu et al., 2004].
At the C-4 phenyl group, with one or more electron-
withdrawing substituents at the ortho or meta position
Calcium channels play a critical role both in the
normal biological functions and also in various patho-
logical processes that occur in neuronal, muscle, and
neurosecretory cells [Dolphin, 2006].Although there
are different types of calcium channel with distinct
physiological roles, L-type channels are typically con-
fined to cell bodies and regulate contractility in muscle
cells [Zamponi, 1997].Calcium channel blockers inhibit
selectively the calcium influx through cell membranes
[Edraki et al., 2009]. 1,4-Dihydropyridines (DHPs),
e.g., nifedipine, nicardipine, amlodipine, represent a
well-known class of calcium antagonists and are com-
*Correspondence to: Cihat S¸afak, Department of Pharma-
mercially employed for the treatment of cardiovascular ceutical Chemistry, Faculty of Pharmacy, Hacettepe University,
Ankara 06100, Turkey.
E-mail: csafak@hacettepe.edu.tr
diseases, particularly hypertension and angina [Vaghy
et al., 1987; Triggle, 2003; S¸afak and S¸ims¸ek, 2006].
Received 22 May 2012; Accepted 29 June 2012
DHPs have attracted interest since their introduc-
tion into clinical medicine because of their high potency
Published online in Wiley Online Library (wileyonlinelibrary.
and selectivity of action [Zhou et al., 2011]. Many com). DOI: 10.1002/ddr.21024
© 2012 Wiley Periodicals, Inc.

2
S¸AFAK ET AL.
are preferable rather than the other groups such as alkyls recorded on a Perkin Elmer FT-IR Spectrum BX (Bea-
or phenyl groups carrying a substituent at the paraposi- consfield, UK). Proton Nuclear Magnetic Resonance
tion [Coburn et al., 1988]. The substituents at the C-3 (1H NMR) and Carbon-13 Nuclear Magnetic Resonance
and C-5 positions modulate tissue selectivity and asym- (13C NMR) spectra were obtained in dimethylsulfoxide
metrical substituents in these positions alter the activity (DMSO) solutions on a Varian Mercury 400, 400 MHz
[Miri et al., 2006]. Among the performed modifications High Performance Digital FT-NMR Spectrometer
at C-3 and C-5, the introduction of bulky and lipophilic (Palo Alto, CA, USA). Chemical shifts are reported in
substituents as one of the esterifying groups led to parts per million (ppm) relative to tetramethylsilane.
novel, potent calcium antagonists [Leonardi et al., 1998] The X-ray crystallographic analysis was carried out
including nicardipine, barnidipine, and benidipine on a Nonius Kappa CCD area-detector diffractometer
[Tamazawa et al., 1986; Sohda et al., 1990]. In addi- (Philadelphia, PA USA). Mass spectra were obtained on
tion, the compounds possessing a 2-pyridylmethyl, an Agilent 5973 Network Mass Selective Detector by
3-pyridylmethyl, 4-pyridylmethyl, or 2-pyridylethyl moi- electron ionization (Philadelphia, PA USA). Elemental
eties at the C-3 and C-5 positions were determined to analyses were performed on a Leco CHNS-932 Elemen-
show strong calcium channel blocking effect [Mehdi- tal Analyzer (Philadelphia, PA USA). Purification by
pour et al., 2007]. It was estimated that the pyridinyl column chromatography was carried out on Merck silica
nitrogen free electron pair or charge distribution on the gel 60 (0.040–0.063 mm) (Steinheim, Germany).
pyridinyl ring could be the important determinants for
calcium channel modulatory effects [Vo et al., 1992].
CHEMISTRY
The aim of the present study is to examine the
influence of cyclopentane, cyclohexane, or tetrahy-
drothiophene rings fused to the DHP ring having a
bulky moiety (3-pyridylmethyl) in the ester group and
two electron-withdrawing substituents attached to the
phenyl ring and to investigate the calcium modulator
activities of the compounds on isolated rabbit gastric
fundus smooth muscle strips.
Synthesis
The synthesis of tetrahydrothiophene-3-one-1,1-
dioxide and pyridine-3-ylmethyl 3-oxo-butanoate are
shown in Figures 2 and 3, respectively.
Tetrahydrothiophen-3-one (0.1 mol), triethylortho-
formate (0.1 mol), p-toluensulfonic acid (0.26 mmol),
and 2 ml ethanol was stirred for 20 h. The mixture
was treated with anhydrous sodium acetate (4 mmol),
sodium tungstate dihydrate (0.00085 mmol), and 28 ml
water. Twenty-eight milliliters of a 35% solution of
MATERIALS AND METHODS
All chemicals used in this study were purchased hydrogen peroxide in water was added dropwise while
from Sigma-Aldrich and Fluka (Steinheim, Germany). keeping the reaction cooled to 30°C. After stirring
Melting points were determined on a Thomas Hoover overnight at room temperature, the resulting product
Capillary Melting Point Apparatus (Philadelphia, PA was filtered and washed with water to achieve 3,3-
USA) and were uncorrected. Infrared spectra were diethoxytetrahydro-thiephene-1,1-dione. The product
was stirred in a mixture of HCl and water at 60°C for
2 h. The mixture was extracted with dichloromethane
(60 ml). The dichloromethane layer was isolated and
dried with magnesium sulfate, filtered, and concen-
NO2
trated. The residue was crystallized from ethanol
H3COOC
H3C
COOCH3
to provide tetrahydrothiophene-3-one-1,1-dioxide
[Altenbach et al., 2004].
3-Pyridylcarbinol (0.02 mol), 2,2,6-trimethyl-4H-
1,3-dioxin-4-one (0.02 mol), and 10 ml xylene were
stirred in an oil bath at 150°C. After an hour, xylene was
removed under diminished pressure, and the residue
N
H
CH3
Fig. 1. Nifedipine.
C2H5O
C2H5O
C2H5O
C2H5O
O
O
HC(OC2H5)3
TsOH
H2O2
Na2WO4, NaOAc
HCl
S
S
S
S
O
O
O
O
Fig. 2. Synthesis of tetrahydrothiophene-3-one-1,1-dioxide.
Drug Dev. Res.

SYNTHESIS AND MYORELAXANT ACTIVITY
3
was then dissolved in water, extracted with ethyl 3-Pyridylmethyl 5-methyl-7-(2,3-disubstituted
acetate. The ethyl acetate layer was isolated and dried phenyl)-2,3,4,7-tetrahydrothieno[3,2-b]pyridine-6-
with magnesium sulfate. Ethyl acetate was removed via carboxylate-1,1-dioxide (compounds six to 10)
a rotary evaporator in order to achieve 3-pyridylmethyl
3-oxobutanoate.
Tetrahydrothiophene-3-on-1,1-dioxide (0.001 mol),
2,3-disubstituted benzaldehyde (0.001 mol), 3-
Compounds one to 25 were prepared (Fig. 4) pyridylmethyl 3-oxobutanoate (0.001 mol), and ammo-
by heating appropriate 1,3-cyclodicarbonyl or nium acetate (0.005 mol) were refluxed for 8 h in 15 ml
tetrahydrothiophene-3-one-1,1-dioxide, the aromatic methanol. The precipitate, which was obtained after
aldehyde, 3-pyridylmethyl 3-oxo-butanoate and ammo- cooling the reaction mixture, was crystallized from
nium acetate in methanol, according to the Hantzsch methanol.
reaction.
3-Pyridylmethyl (2-methyl/2,6,6-trimethyl/2,7,7-
trimethyl)-5-oxo-4-(2,3-disubstituted phenyl)-1,
4,5,6,7,8-hexahydroquinoline-3-carboxylate
(compounds 11–25)
3-Pyridylmethyl 2-methyl-4-(2,3-disubstituted
phenyl)-5-oxo-4,5,6,7-tetrahydro-1H-cyclopenta
[b]pyridine-3-carboxylate (compounds one to five)
0.001 mol appropriate 1,3-cyclohexanedione (1,3-
cyclohexanedione, 4,4-dimethyl-1,3-cyclohexane dione,
5,5-dimethyl1,3-cyclohexanedione), 2,3-disubstituted
1,3-Cyclopentanedione
disubstituted benzaldehyde
(0.001 mol),
(0.001 mol),
2,3-
3-
pyridylmethyl 3-oxobutanoate (0.001 mol), and
ammonium acetate (0.005 mol) were refluxed for 8 h in
15 ml methanol. After the reaction was completed, the
reaction mixture was poured into ice water. The
obtained precipitate was filtered and crystallized from
appropriate solvents. Some compounds were purified
by column chromatography using silica gel as the solid
phase and a 7:3 mixture of ethyl acetate: methanol as
mobile phase.
benzaldehyde
(0.001 mol),
3-pyridylmethyl
3-
oxobutanoate (0.001 mol), and ammonium acetate
(0.005 mol) were refluxed for 8 h in 15 ml methanol.
The precipitate, which was obtained after cooling the
reaction mixture, was filtered and crystallized from
appropriate solvents to achieve the target compound.
3-Pyridylmethyl 2-methyl-4-(2,3-dichlorophenyl)-
35-oxo-4,5,6,7-tetrahydro-1H-cyclopenta[b]pyridine-
3-carboxylate (1)
O
O
O
Crystallized from ethyl acetate/n-hexane. 1HNMR
(d, DMSO-d6): 2.10–2.23 (2H, m, H-6), 2.32 (3H, s,
2-CH3), 2.50–2.56 (2H, m, H-7), 4.88 and 5.06 (2H, AB
system, JAB: 12.8 Hz, COOCH2), 5.18 (1H, s, H-4),
7.15–7.40 (5H, m, aromatic), 8.30 (1H, s, pyridine H-2),
8.45 (1H, d, J: 3.6 Hz, pyridine H-6), 9.90 (1H, s, NH).
CH2OH
CH3CCH2COCH2
O
+
N
N
O
F
Fig. 3. Synthesis of 3-pyridylmethyl 3-oxo-butanoate.
R2
R1
O
O
R2
R1
COOCH2
CH3CCH2COCH2
CH3COONH4
A
+
+
CHO
A
N
N
N
H
CH3
O
O
O
O
O
O
S
A:
O
O
O
O
O
R1, R2: 2,3-Cl2; 2-F, 3-Cl; 2,3-F2; 2-Cl, 3-CF3; 2-F, 3-CF3
Fig. 4. Synthesis of compounds 1 to 25.
Drug Dev. Res.

4
S¸AFAK ET AL.
13CNMR (d, DMSO-d6): 18.8, 23.7, 33.2, 35.9, 62.4, 126.1, 127.2, 129.3, 131.9, 134.8, 135.3, 146.9, 148.2,
102.5, 115.8, 123.2, 127.7, 128.0, 129.2, 130.1, 131.3, 148.9, 164.0, 166.0, 200.4. MS (m/z): 462 [M]+. Anal.
131.9, 135.4, 146.9, 147.7, 148.8, 149.0, 163.8, 166.0, calcd. for C23H18ClF3N2O3: C, 59.68; H, 3.92; N, 6.05.
200.4. MS (m/z): 429 [M]+. Anal. calcd. (analysis calcu- Found: C, 59.71; H, 4.00; N, 6.11.
lated) for C22H18Cl2N2O3: C: 61.55, H: 4.23, N: 6.53.
Found: C: 61.42, H: 4.19, N: 6.49.
3-Pyridylmethyl 2-methyl-4-(2-fluoro-3-
trifluoromethylphenyl)-5-oxo-4,5,6,7-tetra-hydro-
3-Pyridylmethyl 2-methyl-4-(2-fluoro-3-
chlorophenyl)-5-oxo-4,5,6,7-tetrahydro-1H-
cyclopenta[b]pyridine-3-carboxylate (2)
1H-cyclopenta[b]pyridine-3-carboxylate (5)
Crystallized from ethyl acetate/n-hexane. 1HNMR
(d, DMSO-d6): 2.16–2.25 (2H, m, H-7), 2.34 (3H, s,
Purified via column chromatography. 1HNMR (d, 2-CH3), 2.49–2.57 (2H, m, H-6),5.02 (1H, s, H-4), 4.94
DMSO-d6): 2.10–2.20 (2H, m, H-6), 2.30 (3H, s, and 5.03 (2H, AB system, JAB: 12.8 Hz, COOCH2),
2-CH3), 2.50–2.56 (2H, m, H-7), 4.90 and 5.08 (2H, AB 7.20–7.50 (5H, m, aromatic), 8.3 (1H, d, J: 1.6 Hz, pyri-
system, JAB: 12.8 Hz, COOCH2), 5.18 (1H, s, H-4), dine H-6), 8.45 (1H, dd, J: 4.8/1.6 Hz, pyridine H-2),
7.15–7.40 (5H, m, aromatic), 8.32 (1H, s, pyridine H-2), 9.93 (1H, s, NH). 13CNMR (d, DMSO-d6): 18.9, 30.6,
8.46 (1H, d, pyridine H-6), 9.95 (1H, s, NH). 13CNMR 33.3, 39.0, 62.5, 101.4, 115.0, 121.4, 123.2, 124.1, 124.5,
(d, DMSO-d6): 18.8, 23.8, 33.2, 36.0, 62.4, 102.5, 115.8, 124.7, 124.9, 131.8, 135.0, 135.3, 135.4, 135.6, 148.3,
123.1, 127.7, 128.0, 129.2, 130.1, 131.4, 131.9, 135.4, 148.9, 164.2, 165.9, 200.5. MS (m/z): 445 [M-1]+. Anal.
146.8, 147.7, 148.8, 149.0, 163.8, 166.0, 200.3. MS calcd. forC23H18F4N2O3: C, 61.88; H, 4.06; N, 6.28.
(m/z): 412 [M]+. Anal. calcd. for C22H18ClFN2O3: C, Found: C, 62.01; H, 4.17; N, 6.22.
64.00; H, 4.39; N, 6.79. Found: C 64.12; H, 4.41; N,
6.88.
3-Pyridylmethyl 7-(2,3-dichlorophenyl)-5-methyl-
2,3,4,7-tetrahydrothieno[3,2-b] pyridine-6-
3-Pyridylmethyl 2-methyl-4-(2,3-difluorophenyl)-
5-oxo-4,5,6,7-tetrahydro-1H-cyclopenta[b]pyridine-
3-carboxylate (3)
carboxylate-1,1-dioxide (6)
Crystallized from methanol. 1HNMR (d,
DMSO-d6): 2.12 (1H, doublet of doublet of doublets
Crystallized from ethyl acetate. 1HNMR (d, [ddd], H-3A), 2.35 (3H, s, 5-CH3), 2.45 (1H, ddd,
DMSO-d6): 2.12–2.24 (2H, m, H-7), 2.30 (3H, s, H-3B), 3.04 (1H, ddd, H-2A), 3.39 (1H, ddd, H-2B),
2-CH3), 2.46–2.54 (2H, m, H-6), 4.93 (1H, s, H-4), 4.90 4.73 (1H, s, H-7), 4.78 and 4.9 (2H, AB system, JAB:
and 5.03 (2H, AB system, JAB: 12.4 Hz, COOCH2), 13.2 Hz, COOCH2), 6.01 (1H, s, NH), 7.05–7.47 (5H,
6.85–7.40 (5H, m, aromatic), 8.4 (1H, d, J: 1.6 Hz, pyri- m, aromatic), 8.16 (1H, d, J: 1.6 Hz, pyridine H-2),
dine H-6), 8.45 [1H, doublet of doublets (dd), J: 4.8/ 8.42 (1H, dd, J: Hz, 4.8/1.6, pyridine H-6). 13CNMR
1.6 Hz, pyridine H-2], 9.87 (1H, s, NH). 13CNMR (d, (d, DMSO-d6): 20.7, 34.1, 34.7, 51.0, 62.1, 65.5, 81.3,
DMSO-d6): 18.8, 30.7, 33.3, 38.8, 62.5, 101.6, 114.5, 90.8, 123.5, 127.6, 128.8, 129.4, 130.5, 131.8, 132.9,
123.2, 124.1, 131.8, 135.4, 136.3, 145.5, 147.9, 148.0, 135.0, 143.3, 148.8, 149.1, 155.0, 166.4. MS (m/z): 464
148.9, 149.2, 150.4, 150.6, 164.0, 166.0, 200.5. MS [M]+. Anal. calcd. for C21H18Cl2N2O4S: C, 54.20; H,
(m/z): 395 [M-1]+. Anal. Calcd. forC22H18F2N2O3: C, 3.90; N, 6.02; S, 6.89. Found: C, 54.13; H, 4.01; N,
66.66; H, 4.58; N, 7.07. Found: C, 66.78; H, 4.63; N, 6.11; S, 6.93.
7.12.
3-Pyridylmethyl 7-(2-fluoro-3-chlorophenyl)-5-
methyl-2,3,4,7-tetrahydrothieno[3,2-b]pyridine-6-
3-Pyridylmethyl 2-methyl-4-(2-chloro-3-
trifluoromethylphenyl)-5-oxo-4,5,6,7-tetra-hydro-1H- carboxylate-1,1-dioxide (7)
cyclopenta[b]pyridine-3-carboxylate (4)
Crystallized from isopropanol. 1HNMR (d,
Crystallized from ethyl acetate/n-hexane. 1HNMR DMSO-d6): 2.13 (1H, ddd, H-3A), 2.33 (3H, s, 5-CH3),
(d, DMSO-d6): 2.12–2.25 (2H, m, H-7), 2.33 (3H, s, 2.45 (1H, ddd, H-3B), 3.04 (1H, ddd, H-2A), 3.42 (1H,
2-CH3), 2.49–2.57 (2H, m, H-6), 5.28 (1H, s, H-4), 4.89 ddd, H-2B), 4.61 (1H, s, H-7), 4.81 and 5.01 (2H, AB
and 5.04 (2H, AB system, JAB: 12.4 Hz, COOCH2), system, JAB: 13.6 Hz, COOCH2), 5.94 (1H, s, NH),
7.18–7.58 (5H, m, aromatic), 8.23 (1H, d, J: 2 Hz, pyri- 7.05–7.40 (5H, m, aromatic), 8.18 (1H, d, J: 1.6 Hz,
dine H-2), 8.43 (1H, dd, J: 4.8/2 Hz, pyridine H-6), 9.93 pyridine H-2), 8.42 (1H, dd, J: 4.8/1.6 Hz, pyridine
(1H, s, NH). 13CNMR (d, DMSO-d6): 18.9, 33.2 34.8, H-6). 13CNMR (d, DMSO-d6): 20.3, 28.4, 30.6, 34.2,
38.8, 62.4, 102.2, 115.6, 121.7, 123.1, 124.5, 125.8, 50.5, 61.6, 65.7, 80.7, 89.3, 119.1, 123.1, 124.4, 128.9,
Drug Dev. Res.

SYNTHESIS AND MYORELAXANT ACTIVITY
5
132.2, 132.4, 134.6, 148.6, 153.5, 154.6, 155.9, 165.9. 121.4, 123.0. 123.9, 124.1, 125.1, 132.1, 132.2, 132.4,
MS (m/z): 447 [M-1]+. Anal. calcd. for 134.5, 135.0, 148.4, 148.6, 154.9, 165.8. MS (m/z): 481
C21H18ClFN2O4S: C, 56.19; H, 4.04; N, 6.24; S, 7.14. [M-1]+. Anal. calcd. for C22H18F4N2O4S: C, 54.77; H,
Found: C, 56.33; H, 4.14; N, 6.33; S, 7.08.
3.76; N, 5.81; S, 6.65. Found: C, 54.91; H, 3.65; N, 5.94;
S, 6.71.
3-Pyridylmethyl 7-(2,3-difluorophenyl)-5-methyl-
2,3,4,7-tetrahydrothieno[3,2-b] pyridine-6-
carboxylate-1,1-dioxide (8)
3-Pyridylmethyl 2-methyl-4-(2,3-dichlorophenyl)-5-
oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate
Crystallized from methanol. 1HNMR (d, (11)
DMSO-d6): 2.14 (1H, ddd, H-3A), 2.33 (3H, s, 5-CH3),
1
Crystallized from ethanol. HNMR (d, DMSO-
2.46 (1H, ddd, H-3B), 3.04 (1H, ddd, H-2A), 3.42 (1H, d6): 1.70-2.50 (6H, m, H-6,7,8), 2.26 (3H, s, 2-CH3),
ddd, H-2B), 4.63 (1H, s, H-7), 4.81 and 5.02 (2H, AB 4.98 and 5.06 (2H, AB system, JAB: 12.8 Hz, COOCH2),
system, JAB: 13.2 Hz, COOCH2), 5.97 (1H, s, NH), 5.25 (1H, s, H-4), 7.13–7.47 (5H, m, aromatic), 8.36
6.99–7.25, (5H, m, aromatic), 8.16 (1H, s, pyridine (1H, d, J: 2.4 Hz, pyridine H-2), 8.47 (1H, dd, J: 4.0/
H-2), 8.41 (1H, dd, J: 4.8/1.6 Hz, pyridine H-6). 1.6 Hz, pyridine H-6), 9.32 (1H, s, NH). 13CNMR (d,
13CNMR (d, DMSO-d6): 20.8, 28.6, 34.7, 50.9, 62.1, DMSO-d6): 18.8, 22.2, 26.6, 36.3, 37.1, 62.8, 102.8,
66.3, 81.2, 89.8, 115.4, 115.6, 123.6, 124.1, 125.7, 133.0, 111.4, 112.5, 123.7, 127.6, 128.3, 130.3, 131.9, 132.6,
133.4, 133.5, 135.1, 148.9, 149.1, 155.0, 166.4. MS 136.0, 146.9, 148.5, 149.6, 152.1, 166.8, 172.7, 194.9.
(m/z): 432 [M]+. Anal. calcd. forC21H18F2N2O4S: C, MS (m/z): 442 [M]+. Anal. calcd. for C23H20Cl2N2O3: C,
58.33; H, 4.20; N, 6.48; S, 7.41. Found: C, 58.55; H, 62.31; H, 4.55; N, 6.32. Found: C, 62.55; H, 4.66; N,
4.29; N, 6.41; S, 7.45.
6.21.
3-Pyridylmethyl 7-(2-chloro-3-
trifluoromethylphenyl)-5-methyl-2,3,4,7-
tetrahydro-thieno[3,2-b]pyridine-6-carboxylate-1,
1-dioxide (9)
3-Pyridylmethyl 2-methyl-4-(2-fluoro-3-
chlorophenyl)-5-oxo-1,4,5,6,7,8-hexahydroqui-
noline-3-carboxylate (12)
Crystallized from ethyl acetate/n-hexane. 1HNMR
Crystallized from methanol. 1HNMR (d, DMSO- (d, DMSO-d6): 1.75-2.50 (6H, m, H-6,7,8), 2.27 (3H, s,
d6): 2.14 (1H, ddd, H-3A), 2.37 (3H, s, 5-CH3), 2.45 (1H, 2-CH3), 5.08 (1H, s, H-4), 4.98 and 5.08 (2H, AB
ddd, H-3B), 3.06 (1H, ddd, H-2A), 3.44 (1H, ddd, H-2B), system, JAB: 12.4 Hz, COOCH2), 6.98–7.53 (5H, m, aro-
4.81 (1H, s, H-7), 4.76 and 4.99 (2H, AB system, JAB: matic), 8.40 (1H, d, J: 2.0 Hz, pyridine H-2), 8.49 (1H,
13.2 Hz, COOCH2), 5.95 (1H, s, NH), 7.06–7.68 (5H, dd, J: 4.0/ 2.0 Hz, pyridine H-6), 9.31 (1H, s, NH).
m, aromatic), 8.14 (1H, d, J: 2 Hz, pyridine H-2), 8.39 13CNMR (d, DMSO-d6): 18.8, 21.2, 26.5, 31.7, 37.0,
(1H, dd, J: Hz, 4.8/2.0, pyridine H-6). 13CNMR (d, 63.0, 102.0, 110.6, 119.7, 123.8, 125.1, 128.3, 129.9,
DMSO-d6): 20.2, 32.6, 34.1, 50.6, 61.6, 64.9, 80.8, 89.9, 132.4, 136.1, 137.1, 147.2, 149.4, 152.1, 153.4, 155.9,
121.6, 123.0, 124.4, 125.9, 126.3, 126.7, 127.0, 129.4, 166.6, 194.9.MS (m/z): 425 [M-1]+. Anal. calcd. for
132.2, 134.6, 142.9, 148.6, 154.9. 165.8. MS (m/z): 498 C23H20ClFN2O3: C, 64.72; H, 4.72; N, 6.56. Found: C,
[M]+. Anal. calcd. for C22H18ClF3N2O4S: C, 52.96; H, 65.03; H, 4.91; N, 6.69.
3.64; N, 5.61; S, 6.43. Found: C, 53.17; H, 3.77; N, 5.72;
S, 6.50.
3-Pyridylmethyl 2-methyl-4-(2,3-difluorophenyl)-5-
oxo-1,4,5,6,7,8-hexahydroquinoline-3-
carboxylate (13)
Crystallized from carbon tetrachloride. HNMR
3-Pyridylmethyl 7-(2-fluoro-3-
trifluoromethylphenyl)-5-methyl-2,3,4,7-tetrahydro-
1
thieno[3,2-b]pyridin-6-carboxylate-1,1-dioxide (10) (d, DMSO-d6): 1.71–2.51 (6H, m, H-6,7,8), 2.28 (3H, s,
1
Crystallized from ethanol. HNMR (d, DMSO- 2-CH3), 4.99 and 5.08 (2H, AB system, JAB: 12.4 Hz,
d6): 2.16 (1H, ddd, H-3A), 2.35 (3H, s, 5-CH3), 2.46 (1H, COOCH2), 5.09 (1H, s, H-4), 6.92–7.54 (5H, m, aro-
ddd, H-3B), 3.06 (1H, ddd, H-2A), 3.43 (1H, ddd, H-2B), matic), 8.40 (1H, d, J: 2.4 Hz, pyridine H-2), 8.49 (1H,
4.65 (1H, s, H-7), 4.79 and 5.02 (2H, AB system, JAB: dd, J: 5.2/ 2.4 Hz, pyridine H-6), 9.30 (1H, s, NH).
13.6 Hz, COOCH2), 6.00 (1H, s, NH), 7.11–7.60 13CNMR (d, DMSO-d6): 18.3, 20.7, 26.0, 30.6, 36.5,
(5H, m, aromatic), 8.15 (1H, s, pyridine H-2), 8.41 62.5, 101.5, 110.2, 114.5, 123.3, 123.9, 125.4, 132.0,
(1H, dd, J: 4.4/2.0 Hz, pyridine H-6). 13CNMR (d, 135.6, 137.5, 146.6, 148.2, 148.9, 149.1, 150.6, 151.6,
DMSO-d6): 20.3, 27.9, 34.1, 50.5, 61.6, 65.6, 80.7, 88.9, 166.1, 194.3. MS (m/z): 410 [M]+. Anal. calcd. for
Drug Dev. Res.

6
S¸AFAK ET AL.
C23H20F2N2O3: C, 67.31; H, 4.91; N, 6.83. Found: C, 3-Pyridylmethyl 2,6,6-trimethyl-4-(2-fluoro-3-
67.52; H, 5.11; N, 6.67.
chlorophenyl)-5-oxo-1,4,5,6,7,8-hexahydro-
quinoline-3-carboxylate (17)
Crystallized from benzene–petroleum benzene
1
3-Pyridylmethyl 2-methyl-4-(2-chloro-3-
(40:60). HNMR (d, DMSO-d6): 0.81 (3H, s, 6-CH3),
trifluoromethylphenyl)-5-oxo-1,4,5,6,7,8-hexahydro 0.95 (3H, s, 6-CH3), 1.65–1.76 (2H, m, H-7), 2.27 (3H,
quinoline-3-carboxylate (14)
s, 2-CH3), 2.40–2.52 (2H, m, H-8), 4.98 and 5.07 (2H,
Crystallized from methanol. 1HNMR (d, DMSO- AB system, JAB: 12.4 Hz, COOCH2), 5.04 (1H, s, H-4),
d6): 1.781–2.51 (6H, m, H-6,7,8), 2.27 (3H, s, 2-CH3), 6.97–7.55 (5H, m, aromatic), 8.42 (1H, d, J: 1.6 Hz,
4.98 and 5.06 (2H, AB system, JAB: 13.2 Hz, COOCH2), pyridine H-2), 8.49 (1H, dd, J: 4.8/ 1.6 Hz, pyridine
5.34 (1H, s, H-4), 7.23–7.57 (5H, m, aromatic), 8.33 H-6), 9.25 (1H, s, NH). 13CNMR (d, DMSO-d6): 18.4,
(1H, d, J: 2.0 Hz, pyridine H-2), 8.45 (1H, dd, J: 4.8/ 22.8, 24.1, 24.7 31.5, 33.9, 62.5, 101.1, 108.4, 119.2,
2.0 Hz, pyridine H-6), 9.35 (1H, s, NH). 13CNMR (d, 123.3, 124.6, 127.8, 129.2, 132.0, 135.7, 136.7, 136.9,
DMSO-d6): 18.3, 20.6, 26.3, 32.9, 36.6, 62.3, 102.1, 146.7, 149.0, 149.8, 152.8, 155.2, 166.2, 199.1. MS
110.8, 111.8, 121.8, 123.2, 124.5, 125.4, 126.1, 126.9, (m/z): 453 [M-1]+. Anal. calcd. for C25H24Cl2N2O3: C,
129.4, 132.1, 135.4, 146.8, 148.0, 149.0, 151.8, 166.2, 66.00; H, 5.32; N, 6.16. Found: C, 65.73; H, 5.21; N,
194.4. MS (m/z): 475 [M-1]+. Anal. calcd. for 6.05.
C24H20ClF3N2O3: C, 60.45; H, 4.23; N, 5.87. Found: C,
60.61; H, 4.40; N, 6.00.
3-Pyridylmethyl 2,6,6-trimethyl-4-(2,3-
difluorophenyl)-5-oxo-1,4,5,6,7,8-
3-Pyridylmethyl 2-methyl-4-(2-fluoro-3-
trifluoromethylphenyl)-5-oxo-1,4,5,6,7,8-hexahydro
hexahydroquinoline-3-carboxylate (18)
1
Crystallized from benzene. HNMR (d, DMSO-
quinoline-3-carboxylate (15)
d6): 0.81 (3H, s, 6-CH3), 0.95 (3H, s, 6-CH3), 1.65–1.74
Crystallized from cyclohexane. 1HNMR (d,
(2H, m, H-7), 2.27 (3H, s, 2-CH3), 2.40–2.52 (2H, m,
DMSO-d6): 1.69–2.50 (6H, m, H-6,7,8), 2.20 (3H, s,
H-8), 4.99 and 5.07 (2H, AB system, JAB: 12.8 Hz,
2-CH3), 4.99 and 5.04 (2H, AB system, JAB: 12.4 Hz,
COOCH2), 5.05 (1H, s, H-4), 6.91–7.56 (5H, m, aro-
COOCH2), 5.14 (1H, s, H-4), 7.18–7.52 (5H, m, aro-
matic), 8.41 (1H, d, J: 1.6 Hz, pyridine H-2), 8.49 (1H,
matic), 8.38 (1H, d, J: 2.0 Hz, pyridine H-2), 8.48 (1H,
dd, J: 4.8/ 1.6 Hz, pyridine H-6), 9.25 (1H, s, NH).
dd, J: 4.4/ 2.0 Hz, pyridine H-6), 9.34 (1H, s, NH).
13CNMR (d, DMSO-d6): 18.3, 22.8, 24.1, 24.7, 30.9,
13CNMR (d, DMSO-d6): 18.9, 21.2, 26.7, 31.1, 36.9,
33.9, 39.0, 62.4, 101.2, 108.4, 114.2, 114.4, 123.3, 123.8,
63.0, 101.8, 110.6, 111.8, 116.3, 123.7, 124.7, 125.2,
123.9, 125.3, 132.0, 133.1, 135.6, 146.6, 148.9, 149.1,
132.5, 135.8, 136.0, 137.2, 147.5, 149.5, 152.3, 154.9,
149.8, 166.2, 199.1. MS (m/z): 438 [M]+. Anal. calcd. for
157.4, 166.6, 194.9. MS (m/z): 460 [M]+. Anal. calcd. for
C25H24F2N2O3: C, 68.48; H, 5.52; N, 6.39. Found: C,
C24H20F4N2O3: C, 62.61; H, 4.38; N, 6.08. Found: C,
68.63; H, 5.40; N, 6.56.
62.77; H, 4.44; N, 5.87.
3-Pyridylmethyl 2,6,6-trimethyl-4-(2,3-
dichlorophenyl)-5-oxo-1,4,5,6,7,8-
hexahydroquinoline-3-carboxylate (16)
3-Pyridylmethyl 2,6,6-trimethyl-4-(2-chloro-3-
trifluoromethylphenyl)-5-oxo-1,4,5,6,7,8-hexa-
hydroquinoline-3-carboxylate (19)
1
Crystallized from ethanol. HNMR (d, DMSO-
Crystallized from methanol. 1HNMR (d, DMSO-
d6): 0.79 (3H, s, 6-CH3), 0.95 (3H, s, 6-CH3), 1.64–1.76 d6): 0.79 (3H, s, 6-CH3), 0.95 (3H, s, 6-CH3), 1.63–1.74
(2H, m, H-7), 2.24 (3H, s, 2-CH3), 2.40–2.50 (2H, m, (2H, m, H-7), 2.25 (3H, s, 2-CH3), 2.40–2.53 (2H, m,
H-8), 4.99 and 5.06 (2H, AB system, JAB: 13.2 Hz, H-8), 4.98 and 5.04 (2H, AB system, JAB: 12.4 Hz,
COOCH2), 5.20 (1H, s, H-4), 7.12–7.48 (5H, m, aro- COOCH2), 5.29 (1H, s, H-4), 7.25–7.55 (5H, m, aro-
matic), 8.37 (1H, d, J: 1.6 Hz, pyridine H-2), 8.47 (1H, matic), 8.34 (1H, d, J: 2.0 Hz, pyridine H-2), 8.46 (1H,
dd, J: 4.4/ 1.6 Hz, pyridine H-6), 9.24 (1H, s, NH). dd, J: 5.2/ 2.0 Hz, pyridine H-6), 9.30 (1H, s, NH).
13CNMR (d, DMSO-d6): 18.3, 22.9, 24.1, 24.6, 33.9, 13CNMR (d, DMSO-d6): 18.4, 21.6, 22.9, 24.1, 24.6,
36.1, 62.3, 101.9, 109.2, 123.2, 127.5, 127.7, 129.6, 33.8, 35.3, 62.3, 101.6, 109.0, 121.8, 123.2, 124.5, 125.3,
130.1, 131.3, 132.1, 133.4, 135.6, 146.3, 148.2, 148.9, 126.0, 126.8, 129.4, 132.1, 135.5, 146.8, 148.0, 148.8,
149.1, 149.7, 166.3, 199.1. MS (m/z): 470 [M]+. Anal. 149.1, 150.0, 166.3, 199.1. MS (m/z): 503 [M-1]+. Anal.
calcd. for C25H24Cl2N2O3: C, 63.70; H, 5.13; N, 5.94. calcd. for C26H24ClF3N2O3: C, 61.85; H, 4.79; N, 5.55.
Found: C, 63.88; H, 5.22; N, 6.13.
Found: C, 61.61; H, 4.83; N, 5.53.
Drug Dev. Res.

SYNTHESIS AND MYORELAXANT ACTIVITY
7
3-Pyridylmethyl 2,6,6-trimethyl-4-(2-fluoro-3-
trifluoromethylphenyl)-5-oxo-1,4,5,6,7,8-hexa-
hydroquinoline-3-carboxylate (20)
3-Pyridylmethyl 2,7,7-trimethyl-4-(2,3-
difluorophenyl)-5-oxo-1,4,5,6,7,8-hexahydroquinoli-
ne-3-carboxylate (23)
Crystallized from ethyl acetate/benzene. 1HNMR
Crystallized from ethyl acetate/n-hexane. 1HNMR
(d, DMSO-d6): 0.80 (3H, s, 6-CH3), 0.95 (3H, s, 6-CH3), (d, DMSO-d6): 0.81 (3H, s, 7-CH3), 0.99 (3H, s, 7-CH3),
1.62–1.75 (2H, m, H-7), 2.27 (3H, s, 2-CH3), 2.38–2.52 1.92 and 2.15 (2H, AB system, JAB: 16.0 Hz, H-8), 2.28
(2H, m, H-8), 5.02 (2H, s, COOCH2), 5.09 (1H, s, H-4), (3H, s, 2-CH3), 2.26 and 2.42 (2H, AB system, JAB:
7.16–7.54 (5H, m, aromatic), 8.39 (1H, d, J: 2.0 Hz, 16.8 Hz, H-6), 4.99 and 5.08 (2H, AB system, JAB:
pyridine H-2), 8.49 (1H, dd, J: 4.8/ 2.0 Hz, pyridine 12.4 Hz, COOCH2), 5.06 (1H, s, H-4), 6.92–7.54 (5H,
H-6), 9.29 (1H, s, NH). 13CNMR (d, DMSO-d6): 18.4, m, aromatic), 8.0 (1H, d, J: 1.6 Hz, pyridine H-2), 8.49
22.8, 24.1, 24.6, 31.2, 33.9, 40.1, 62.5, 100.9, 108.2, (1H, dd, J: 4.0/ 1.6 Hz, pyridine H-6), 9.25 (1H, s, NH).
115.6, 121.5, 123.2, 124.1, 124.3, 124.6, 132.0, 135.5, 13CNMR (d, DMSO-d6): 18.4, 26.2, 28.9, 31.8, 35.8,
136.6, 147.0, 149.1, 150.0, 154.4, 157.0, 166.1, 199.1. 38.9, 50.2, 62.3, 101.5, 108.9, 114.5, 123.3, 125.4, 132.0,
MS (m/z): 488 [M]+. Anal. calcd. for C26H24F4N2O3: C, 135.6, 137.2, 145.4, 146.8, 147.8, 148.1, 148.9, 149.7,
63.93; H, 4.95; N, 5.73. Found: C, 63.76; H, 4.86; N, 150.0, 166.3, 194.1. MS (m/z): 437 [M-1]+. Anal. calcd.
5.86.
for C25H24F2N2O3: C, 68.48; H, 5.52; N, 6.39. Found: C,
68.22; H, 5.69; N, 6.59.
3-Pyridylmethyl 2,7,7-trimethyl-4-(2,3-
dichlorophenyl)-5-oxo-1,4,5,6,7,8-
hexahydroquinoline-3-carboxylate (21)
3-Pyridylmethyl 2,7,7-trimethyl-4-(2-chloro-3-
trifluoromethylphenyl)-5-oxo-1,4,5,6,7,8-hexa-
hydroquinoline-3-carboxylate (24)
Crystallized from ethyl acetate/n-hexane. 1HNMR
(d, DMSO-d6): 0.81 (3H, s, 7-CH3), 0.99 (3H, s, 7-CH3),
1.91 and 2.14 (2H, AB system, JAB: 16.0 Hz, H-8), 2.26
(3H, s, 2-CH3), 2.26 and 2.42 (2H, AB system, JAB:
16.8 Hz, H-6), 4.98 and 5.07 (2H, AB system, JAB:
12.4 Hz, COOCH2), 5.23 (1H, s, H-4), 7.13–7.47 (5H,
m, aromatic), 8.36 (1H, d, J: 2.0 Hz, pyridine H-2), 8.47
(1H, dd, J: 4.4/ 2.0 Hz, pyridine H-6), 9.24 (1H, s, NH).
13CNMR (d, DMSO-d6): 18.4, 26.3, 28.9, 31.9, 35.8,
38.8, 50.1, 62.3, 102.2, 109.7, 123.2, 127.4, 127.8, 129.7,
130.1, 131.4, 132.1, 135.5, 146.6, 147.8, 148.9, 149.1,
149.6, 166.4, 194.0. MS (m/z): 470 [M]+. Anal. calcd. for
C25H24Cl2N2O3: C, 63.70; H, 5.13; N, 5.94. Found: C,
63.46; H, 5.25; N, 5.88.
Crystallized from ethyl acetate/n-hexane. 1HNMR
(d, DMSO-d6): 0.82 (3H, s, 7-CH3), 1.00 (3H, s, 7-CH3),
1.92 and 2.14 (2H, AB system, JAB: 16.0 Hz, H-8), 2.27
(3H, s, 2-CH3), 2.27 and 2.43 (2H, AB system, JAB:
17.2 Hz, H-6), 4.98 and 5.06 (2H, AB system, JAB:
13.2 Hz, COOCH2), 5.32 (1H, s, H-4), 7.23–7.56 (5H,
m, aromatic), 8.33 (1H, d, J: 1.6 Hz, pyridine H-2), 8.45
(1H, dd, J: 5.2/ 1.6 Hz, pyridine H-6), 9.28 (1H, s, NH).
13CNMR (d, DMSO-d6): 18.4, 26.3, 28.9, 31.9, 34.9,
38.8, 50.00, 62.3, 101.9, 109.5, 123.2, 125.5, 126.1,
126.8, 129.4, 132.1, 135.4, 135.5, 136.6, 147.0, 147.7,
148.8, 149.0, 149.9, 166.2, 194.0. MS (m/z): 504 [M]+.
Anal. calcd. for C26H24ClF3N2O3: C, 61.85; H, 4.79; N,
5.55. Found: C, 62.07; H, 4.66; N, 5.32.
3-Pyridylmethyl 2,7,7-trimethyl-4-(2-fluoro-3-
chlorophenyl)-5-oxo-1,4,5,6,7,8-hexahydro-
quinoline-3-carboxylate (22)
3-Pyridylmethyl 2,7,7-trimethyl-4-(2-fluoro-3-
trifluoromethylphenyl)-5-oxo-1,4,5,6,7,8-
hexahydroquinoline-3-carboxylate (25)
Crystallized from methanol. 1HNMR (d, DMSO-
Crystallized from ethyl acetate. 1HNMR (d,
d6): 0.81 (3H, s, 7-CH3), 0.99 (3H, s, 7-CH3), 1.92 and DMSO-d6): 0.82 (3H, s, 7-CH3), 1.00 (3H, s, 7-CH3),
2.14 (2H, AB system, JAB: 16.0 Hz, H-8), 2.28 (3H, s, 1.92 and 2.15 (2H, AB system, JAB: 16.0 Hz, H-8), 2.29
2-CH3), 2.27 and 2.42 (2H, AB system, JAB: 17.2 Hz, (3H, s, 2-CH3), 2.26 and 2.44 (2H, AB system, JAB:
H-6), 4.98 and 5.07 (2H, AB system, JAB: 12.4 Hz, 16.8 Hz, H-6), 4.99 and 5.04 (2H, AB system, JAB:
COOCH2), 5.05 (1H, s, H-4), 6.98–7.54 (5H, m, aro- 12.4 Hz, COOCH2), 5.10 (1H, s, H-4), 7.17–7.54 (5H,
matic), 8.41 (1H, d, J: 2.0 Hz, pyridine H-2), 8.49 (1H, m, aromatic), 8.39 (1H, d, J: 2.0 Hz, pyridine H-2), 8.49
dd, J: 4.0/ 1.4 Hz, pyridine H-6), 9.25 (1H, s, NH). (1H, dd, J: 4.8/ 1.6 Hz, pyridine H-6), 9.29 (1H, s,
13CNMR (d, DMSO-d6): 18.4, 26.2, 28.9, 31.2, 32.0, NH).13CNMR (d, DMSO-d6): 18.4, 22.4, 25.9, 28.4,
48.5, 50.0, 62.5, 101.5, 108.9, 119.3, 123.3, 124.5, 127.9, 31.1, 32.0, 49.9, 62.6, 101.1, 108.7, 116.1, 121.5, 123.3,
129.3, 131.9, 135.7, 136.5, 146.8, 149.0, 149.8, 152.8, 124.0, 124.7, 126.9, 131.9., 135.6, 136.2, 147.2, 149.0,
155.3, 166.1, 194.0. MS (m/z): 454 [M]+. Anal. calcd. for 150.0, 154.6, 157.2, 166.1, 194.0. MS (m/z): 487 [M-1]+.
C25H24Cl2N2O3: C, 66.00; H, 5.32; N, 6.16. Found: C, Anal. calcd. for C26H24F4N2O3: C, 63.93; H, 4.95; N,
66.22; H, 5.47; N, 6.22.
5.73. Found: C, 64.11; H, 5.10; N, 5.88.
Drug Dev. Res.

8
S¸AFAK ET AL.
nolol (beta adrenergic receptor blocker, 10-6 M), and
Nw-nitro-L-arginine methyl ester (L-NAME) hydro-
PHARMACOLOGY
New Zealand white rabbits weighing 2.5–3 kg chloride (the nitric oxide synthase inhibitor, 10-4 M).
(Laboratory Animal Production Center, Gazi Univer- L-NAME, propranolol hydrochloride, and nifedipine
sity, Ankara, Turkey) were used in pharmacological were dissolved in distilled water, whereas the com-
studies. After the rabbits were sacrificed with injection pounds and indomethacin were dissolved in DMSO.
of sodium pentobarbital (30–40 mg/kg, i.v.), the
The calcium antagonist activities of the com-
stomach was removed through an abdominal incision. pounds were determined by tests performed on isolated
The fundal part of the stomach was then dissected par- rabbit gastric fundus smooth muscle strips. Prepara-
allel to the longitudinal muscle wall. The obtained tions were placed in high K+ containing (80 mM) solu-
approximately 15–20 mm long and 2 mm wide muscle tion. When Ca+2 (2.5 mM) was added to the organ bath,
strip was allowed to equilibrate for a period of 60 min in a contraction occurred. At the plateau level of contrac-
20-ml organ baths filled with Ca2+ free Krebs–Henseleit tion, the test compounds (10-8 – 3 ¥ 10-4 M) and nife-
solution (KHS) of the following composition (mmol/l): dipine (10-9 – 10-5 M) were applied. Concentration
NaCl, 118; KCl, 4.7; NaHCO3, 25; MgCl2, 0.54; relaxation for compounds and nifedipine were obtained
NaHPO4, 0.9; and glucose, 10.04.The pH of the satu- by adding into the bath in a cumulative manner.
rated solution was 7.4. During the studies, the solution Responses of test compounds and nifedipine were
was aerated with 95% O2 and 5% CO2 and temperature expressed as the percentage of the precontraction using
was maintained at 37°C by a thermoregulated water Ca2+ (2.5 mM). DMSO was also tested in Ca2+ (2.5 mM)
circuit. Each strip was connected to a force transducer precontracted rings.
˙
(FDT 10-A, May IOBS 99, COMMAT Iletis¸im Co.,
For evaluating the effects of an antagonist, the
Ankara, Turkey) for the measurement of isometric maximum relaxant response (Emax) and pD2 (–log
force, which was continuously displaced and recorded EC50) values were computed by using GraphPad Prism
on an online computer via four-channel transducer data 5.0 package program. All data were expressed as
acquisition system (MP30B-CE, BIOPAC Systems Inc., mean Ϯ standard error of mean. Statistical comparison
Santa Barbara, CA, USA) using software (BSL PRO v between the groups was performed by Mann–Whitney
3.6.7, BIOPAC Systems Inc.) that also had the capacity U-test and P-values less than 0.05 were considered to be
of analyzing the data. After mounting, each strip was statistically significant.
allowed to equilibrate with a basal tension of 1 g for
60 min. Ca2+ free KHS was replaced with fresh solution of Gazi University, Faculty of Medicine, Ankara,
every 15 min during this period of time. Turkey (GÜET-10.031). All procedures involving
This study was approved by the Ethics Committee
In order to eliminate whether the relaxation animals and their care were conducted in conformity
induced by the test compounds was due to an interac- with international laws and policies.
tion with cyclooxygenase, adrenergic, or nitric oxide
The maximum relaxant effects (Emax) and the
pathways, all experiments were carried out in the pres- negative logarithm of the concentration for the half-
ence of indomethacin (COX inhibitor, 10-5 M), propra- maximal response (pD2) values of the compounds and
TABLE 1. Maximum Relaxant Responses (Emax) and pD2 Values of the Compounds and Nifedipine on Isolated Strips of Rabbit Gastric
Fundus Smooth Muscle
Compound
Emax
pD2
Compound
Emax
pD2
1*
2
3
4
5
6*
7*
8
90.59 Ϯ 3.70
100.00 Ϯ 0.00
99.62 Ϯ 0.38
96.70 Ϯ 2.13
99.68 Ϯ 0.32
91.76 Ϯ 2.68
77.48 Ϯ 11.97
98.14 Ϯ 1.17
90.04 Ϯ 5.20
71.73 Ϯ 8.64
98.40 Ϯ 1.60
100.00 Ϯ 0.00
100.00 Ϯ 0.00
5.19 Ϯ 0.14
5.31 Ϯ 0.18
5.08 Ϯ 0.12
4.88 Ϯ 0.11
4.62 Ϯ 0.12
4.27 Ϯ 0.07
3.81 Ϯ 0.05
4.78 Ϯ 0.10
4.87 Ϯ 0.12
4.46 Ϯ 0.17
6.05 Ϯ 0.09
5.81 Ϯ 0.08
5.88 Ϯ 0.18
14
15
16
17
18
19
20
21
22
96.92 Ϯ 3.08
100.00 Ϯ 0.00
99.09 Ϯ 0.91
97.49 Ϯ 2.50
96.13 Ϯ 3.87
100.00 Ϯ 0.00
90.64 Ϯ 5.42
96.54 Ϯ 2.90
100.00 Ϯ 0.00
100.00 Ϯ 0.00
85.77 Ϯ 5.29
99.44 Ϯ 0.46
100.00 Ϯ 0.00
5.63 Ϯ 0.16
5.43 Ϯ 0.08
5.78 Ϯ 0.13
5.45 Ϯ 0.10
5.44 Ϯ 0.11
5.52 Ϯ 0.09
5.17 Ϯ 0.11
4.89 Ϯ 0.12
5.11 Ϯ 0.07
5.35 Ϯ 0.15
4.72 Ϯ 0.10
4.89 Ϯ 0.25
8.10 Ϯ 0.03
9
10*
11
12
13
23
24*
25
Nifedipine
*P < 0.05 different from nifedipine.
Drug Dev. Res.

SYNTHESIS AND MYORELAXANT ACTIVITY
9
nifedipine on isolated strips of rabbit gastric fundus
smooth muscle are given in Table 1. DMSO, the solvent
used to dissolve the test compounds, had no significant
relaxant effect.
TABLE 2. Structural Data of Synthesized Compounds
Melting
Empirical
formula
Compound
R1
R2
point (oC)
M. W.
R2
R1
RESULTS AND DISCUSSION
O
COOCH2
Structure and properties of the prepared com-
pounds are given in Table 2. Maximum relaxant
responses (Emax) and pD2 values of the compounds
and nifedipine on isolated strips of rabbit gastric fundus
smooth muscle are given in Table 1. This series of novel
condensed 1,4-DHPs were prepared via a modified
Hantzsch reaction and the structures elucidated by IR
(infrared), 1HNMR, 13CNMR, and mass spectra.
Elemental analysis results were within Ϯ 0.4% of theo-
retical values for all compounds.
N
N
H
CH3
1
2
3
4
5
Cl
F
F
Cl
F
Cl
Cl
F
CF3
CF3
177
194
216
209
210
C22H18Cl2N2O3
C22H18ClFN2O3
C22H18F2N2O3
C23H18ClF3N2O3
C23H18F4N2O3
429
412
396
462
446
R2
R1
O
O
S
COOCH2
In the IR spectra, characteristic N-H, C=O
N
(ester), C=O (ketone), and S=O stretching bonds were
N
H
CH3
1
observed. In the HNMR spectra, each proton of the
6
7
8
9
10
Cl
F
F
Cl
F
Cl
Cl
F
CF3
CF3
203
184
233
201
211
C21H18Cl2N2O4S
C21H18ClFN2O4S
C21H18F2N2O4S
C22H18ClF3N2O4S
C22H18F4N2O4S
464
448
432
498
482
tetrahydrothiophene ring was observed at 2.12–
3.44 ppm separately and as ddd. The methyl and
methine protons on the DHP ring were seen as singlets
at 2.20–2.37 ppm and 4.65–5.34 ppm, respectively. The
protons, which are on phenyl and pyridine rings, were
seen at 6.85–8.49 ppm. The N-H signals were observed
at either 5.94–6.01 ppm or 9.24–9.95 ppm as singlets.
In the 13CNMR spectra, the number of the signals fit
exactly the number of carbon atoms. The mass spectra
of the compounds were recorded via the electron ion-
ization technique. The molecular ion peak (M+) or the
M-1 peak due to the aromatization of the DHP ring to
the pyridine analog were seen in the spectra of all com-
pounds. Cleavage of the ester group and phenyl ring
from the parent molecule was the next most observed
fragmentations.
R2
O
R1
COOCH2
N
N
H
CH3
11
12
13
14
15
Cl
F
F
Cl
F
Cl
Cl
F
CF3
CF3
205
200
204
196
202
C23H20Cl2N2O3
C23H20ClFN2O3
C23H20F2N2O3
C24H20ClF3N2O3
C24H20F4N2O3
R2
442
426
410
476
460
O
R1
The structure of compound 20 was also confirmed
by an X-ray crystal structure analysis (Fig. 5). The 1,4-
DHP ring has a shallow boat conformation, while the
oxocyclohexene ring has a half-chair conformation and
the amine group forms an intermolecular N-H. . . . . ..N
hydrogen bond with the pyridine ring N atom of a
neighboring molecule. The halogen-substituted phenyl
ring has a weak intramolecular p–p interaction with the
pyridine ring. A detailed description of the structure is
presented in Figure 2 [Linden et al., 2011].
COOCH2
N
N
CH3
H
16
17
18
19
20
Cl
F
F
Cl
F
Cl
Cl
F
CF3
CF3
221
204
211
192
185
C25H24Cl2N2O3
C25H24Cl2N2O3
C25H24F2N2O3
C26H24ClF3N2O3
C26H24F4N2O3
R2
470
454
438
504
488
O
R1
The results of the tests performed on with Ca2+
(2.5 mM) precontracted isolated rabbit gastric fundus
smooth muscle strips indicated that all of compounds
and nifedipine had concentration-dependent relaxation
responses with the efficacy order: Nifedipine = 2 =
12 = 13 = 15 = 19 = 22 = 23 Ն 5 = 3 = 25 = 16 Ն 11 = 8
Ն 17 Ն 14 = 4 = 21 = 18 > 6 Ն 20 = 1 = 9 > 24 > 7 > 10.
While compounds 2, 12, 13, 15, 19, 22, and 23 had the
COOCH2
N
N
H
CH3
21
22
23
24
25
Cl
F
F
Cl
F
Cl
Cl
F
CF3
CF3
230
167
200
191
162
C25H24Cl2N2O3
C25H24Cl2N2O3
C25H24F2N2O3
C26H24ClF3N2O3
C26H24F4N2O3
470
454
438
504
488
Drug Dev. Res.

10
S¸AFAK ET AL.
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