Synthesis and antiproliferative activities of chloropyridazine derivatives retain alkylsulfonyl moiety

Full text of DOI:10.1002/bkcs.10967

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DOI: 10.1002/bkcs.10967
BULLETIN OF THE
C. Kim and M.-S. Park
KOREAN CHEMICAL SOCIETY
Synthesis and Antiproliferative Activities of Chloropyridazine
Derivatives Retain Alkylsulfonyl Moiety
*
Chaewon Kim and Myung-Sook Park
College of Pharmacy, Duksung Women’s University, Seoul 132-714, Korea.
*E-mail: mspark@duksung.ac.kr
Received July 15, 2016, Accepted August 25, 2016, Published online October 3, 2016
Keywords: Chloropyridazines, 3-Alkylsulfonyl, Antiproliferative, MCF-7, Hep3B
Some chloropyridazine derivatives have shown interesting
intermediate dichloropyridazinyl diselenide 2 was obtain-
able from the corresponding 3,6-dichloropyridazine 1 by
pharmacodynamics properties in terms of antioxidant1 and
anti-human rotavirus (HRV) activities (Figure 1).2,3 To date,
however, no study has evaluated the antiproliferative effects
of chloropyridazines in other types of human cancer cells.
Therefore, the replacement of the heterocycle of chloro-
pyridazines by heteroatoms (or moieties) such as oxygen
(O), sulfur (S), selenium (Se), sulfinyl (SO), and sulfonyl
(SO2) yields the target compounds (Figure 1). We designed
substituted 3-chloropyridazine derivatives as possible anti-
tumor candidates. These derivatives have three basic struc-
tures, namely chloropyridazine region, heteroatoms, and
alkyl chain. We made an examination of antiproliferative
activities for target chloropyridazines of five groups against
breast cancer (MCF-7) and hepatocellular carcinoma
(Hep3B) cells in Cell Counting Kit-8 (CCK-8) assays. As a
result, we describe herein the preparation of some chloro-
pyridazine derivatives and the refinement of potential
proliferative inhibitors on human cancer cell lines.
reaction with sodium diselenide.7 A synthetic pathway
7,8
for dipyridyl diselenide has been developed
and the
synthesis of substituted dipyridazinyl diselenide has been
reported.9 We applied a general method of preparing dia-
ryl (or dialkyl) diselenide from diaryl (or dialkyl) halides
and sodium diselenide.10–12 A series of alkylselenylpyri-
dazines 5b–5f was prepared by Se–Se bond cleavage and
Se-alkylation.
Treatment of alkylthiopyridazines 4a–4e with 35%
hydrogen peroxide afforded corresponding alkylsulfinyl-
chloropyridazine 6a–6e and alkylsulfonylchloropyridazine
7a–7e. Target 6a–6e and 7a–7e were synthesized as
illustrated in Scheme 1.
The chloropyridazines were obtained mostly through
the substitution reaction. Scheme 1 depicts the prepara-
tion of desired substituted chloropyridazine derivatives.
We previously reported the synthesis of 3-allylthio-6-
chloropyridazine in 95% yield through allylthiolation.4
All 3-alkoxy-6-chloropyridazines 3b–3d and 3-alkylthio-
6-chloropyridazines 4b–4e were prepared following
the synthetic methods of existing literature.5,6 The
Figure 1. Bioactive chloropyridazines and target chloropyridazines.
Scheme 1. Synthetic routes for target chloropyridazine analogues.
Bull. Korean Chem. Soc. 2016, Vol. 37, 1858–1861
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We applied a common method for the CCK-8 assays17
of synthetic compounds. In Table 1, we summarize the
antiproliferative activities for targets. Among 22, four com-
pounds (4e, 6a, 7c and 7d) that had IC50 values below
200 μM inhibited the growth of MCF-7 at standard concen-
trations (6.25, 25, 100, and 400 μg/mL). Two compounds
(7c, 7d) that had IC50 values below 200 μM inhibited the
growth of Hep3B. The antiproliferative activities of deriva-
tives were not good as shown in Figures 2 and 3.
Compound 4e inhibited MCF-7 cell growth and 7c
resisted Hep3B cell growth at IC50 in a dose-dependent
manner at a low concentration (6.25 μg/mL). Both com-
pounds 7c (3-n-butylsulfonyl-6-chloropyridazine) and 7d
(3-n-pentylsulfonyl-6-chloropyridazine) had potentially
antiproliferative activity against MCF-7 and Hep3B cell
lines. CCK-8 assays indicated that compounds 7c, 7d
inhibited cancer cells proliferation by triggering cell death.
In conclusion, we designed and synthesized a total of five
groups of alkoxy-(or alkylthio-, alkylselenyl-, alkylsufinyl-,
alkylsulfonyl-)chloropyridazines, and their antiproliferative
activity was evaluated in the human cancer cell lines. IC50
values showed that the alkylsulfonylchloropyridazine com-
pounds exhibited more active than the other four groups
having alkoxy, alkylthio, alkylselenyl, alkylsulfinyl moieties
against MCF-7 and Hep2B Cells.
Table 1. Inhibitory results for five groups of synthesized
chloropyridazines against MCF-7, Hep3B.
N
N
Cl
X
R
IC50 (μM)
Comp. No.
R
X
MCF-7
Hep3B
3ba
3ca
3da
4bb
4cb
4db
4e
5bc
5cc
5dc
5e
n-propyl
n-butyl
n-pentyl
n-propyl
n-butyl
n-pentyl
n-hexyl
n-propyl
n-butyl
n-pentyl
n-hexyl
iso-propyl
ethyl
n-propyl
n-butyl
n-pentyl
n-hexyl
ethyl
n-propyl
n-butyl
n-pentyl
n-hexyl
O
O
O
S
S
S
1756.3
>4000
2491.7
>4000
1404.6
>4000
39.9
2436.6
>4000
2552.4
>4000
>4000
106.7
1890.2
1737.5
2185.3
2830.6
550.3
419.0
125.7
130.5
250.3
1517.6
2143.2
1397.1
3812.1
1321.4
>5000
695.8
>5000
>5000
1223.8
1896.2
1805.0
389.8
4601.0
1768.6
912.2
915.3
418.5
316.9
115.0
127.4
268.3
S
Se
Se
Se
Se
Se
SO
SO
SO
5f
6ad
6bd
6cd
6d
SO
SO
6e
7a
7b
7c
7d
7e
SO2
SO2
SO2
SO2
SO2
Experimental
Materials and Methods for Bioassays: Cell Line Culture
Conditions. MCF-7 and Hep3B cancer cells were pur-
chased from the American Type Culture Collection
(ATCC; Manassas, VA, USA).
a
3b–3d were reported.5
4b–4d were reported.6
5b–5d were reported.10
6a–6c were reported.16
b
c
d
Antiproliferative CCK-8 Assays. The cytotoxic activity
of compounds was determined in vitro using the CCK-8
assay kit (Dojindo, Kumamoto, Japan).
A series of compound 4a–4e was prepared from 1 using
General Synthetic Procedure for Alkoxypyridazines
3b–3d and Alkylthiopyridazines 4b–4e. The alkoxypyri-
dazines 3b–3d and alkylthiopyridazines 4b–4d were synthe-
sized from 1 through alkoxylation (or alkylthiolation) using
a modification on previously reported methods.4–6,18
alkylthiolation with alkylmercaptan. Sulfides 4a–4e were oxi-
dized to 6a–6e using 1–2 equiv of 35% hydrogen peroxide as
an oxidant.13–16 Sulfones 7a–7e were synthesized using 3.5–5
equiv of oxidants. The oxidation of 4a–4e to 7a–7e was also
accomplished with aqueous hydrogen peroxide at room temper-
ature in acetic acid for 18–72 h.
3-(n-Hexylthio)-6-chloropyridazine (4e). Yield: 54%.
1
m.p. 62–64ꢀC. H NMR (CDCl3) δ 8.15 (d, J = 8.8 Hz,
Figure 2. Antiproliferative activity of chloropyridazines in MCF-7 cancer cells.
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Figure 3. Antiproliferative activity of chloropyridazines in Hep3B cancer cells.
1H, CH, pyridazine), 7.80 (d, J = 8.8 Hz, 1H, CH, pyrida-
zine), 3.59 (t, J = 8.0 Hz, 2H, SCH2, hexyl), 1.85–1.74
(m, 2H, CH2, hexyl), 1.48–1.39 (m, 2H, CH2, hexyl),
1.30–1.27 (m, 1H, CH2, hexyl), 0.86 (t, J = 6.7 Hz, 3H,
CH3, hexyl). 13C NMR (CDCl3) δ 161.11, 159.73, 130.00,
126.63 (pyridazine), 52.39, 31.02, 27.91, 22.19, 21.99,
13.81 (hexyl).
757 (C Se), 697 (C Cl); GC-MS m/z (%) 236 (M+),
194.0 (100.0), 192.0 (54.11), 196.0 (50.52), 236 (45.16),
155.10 (41.53).
General Synthetic Procedure for Alkylsulfinylpyri-
dazines 6a–6e. The compound 6a–6e was prepared from
3-chloroalkylthiopyridazine 4a–4e as a white solid using
a modification of a previously reported method. To a
solution of 4a–4e (7 mmol) in 15 mL acetic acid, 35%
hydrogen peroxide (100–200 mol%) was added at
RT. The resulting mixture was stirred for 22–72 h at
RT. After completion of the reaction, the mixture was
diluted with 30 mL ether and 15 mL water, and it was
partitioned between ether and water layers in a separating
funnel. The ether layer was extracted with 15 mL sodium
hydroxide (1 N-NaOH) solution three times. The com-
bined water layer was reextracted several times with
50 mL dichloromethane. The combined organic layers
were washed with water, dried over anhydrous Na2SO4,
and concentrated. The crude product was further purified
by silica gel column chromatography (Hexanes/EtOAc
1:1) to provide the target compound as a white solid.
The compound 6a–6c was prepared using the reported
synthetic procedure, and these spectra data were identi-
fied with the literature.16
General Synthetic Procedure for Alkylselenylpyrida-
zines 5b–5f. To a stirred mixture of dipyridazyinyl disele-
nide
2
(5.2 mmol), powdered sodium hydroxide
(26 mmol), and tetrabutylammonium bromide (1.04 mmol)
in absolute tetrahydrofuran (THF) (60 mL), a solution of
hydrazine monohydrate (1.73 mmol) was added at room
temperature (RT). After 1 h of stirring, the color of the
reaction mixture turned to orange red from pale yellow.
The reaction mixture was then cooled to 0ꢀC, alkyl halide
(10.4 mmol) with the same amount of THF was added
slowly dropwise, and stirring continued for 1 h at 0ꢀC.
After the reaction was complete, the solvent THF was eva-
porated under reduced pressure. The residue was dissolved
in ethyl acetate (50 mL). The organic layer was washed
with water (50 mL × 3) and subsequently dried over anhy-
drous sodium sulfate (Na2SO4). After solvent evaporation,
the residue was purified by column chromatography (hex-
anes/EtOAc 3:1, 2:1) on silica gel to afford 5b–5f.
3-(n-Pentylsulfinyl)-6-chloropyridazine (6d). Yield:
54%. m.p. 57–59ꢀC. 1H NMR (CDCl3)
δ
8.13
3-(n-Hexylselenyl)-6-chloropyridazine (5e). Yield:
38%. m.p. 45–48ꢀC. 1H NMR (CDCl3)
δ
7.49
(d, J = 8.8 Hz, 1H, CH, pyridazine), 7.78 (d, J = 8.8 Hz,
1H, CH, pyridazine), 3.30–3.20 (m, 1H, SCH2, pentyl),
3.08–2.99 (m, 1H, SCH2, pentyl), 1.95–1.69 (m, 1H, CH2,
pentyl), 1.60–1.54 (m, 1H, CH2, pentyl), 1.49–1.31 (m, 4H,
CH2, pentyl), 0.90 (t, J = 7.2 Hz, 3H, CH3, pentyl). 13C
NMR (CDCl3) δ 168.63, 157.89, 129.82, 125.70 (pyrida-
zine), 55.30, 30.60, 22.15, 21.31, 13.69 (pentyl). FT-IR
(KBr) cm−1 3025 (aromatic), 1543 (N N), 1492, 1451
(CH2), 1028 (SO), 540 (CCl). GC-MS m/z (%) 232.73
(M+) 145.90 (base peak).
(d, J = 8.8 Hz, 1H, CH, pyridazine), 7.30 (d, J = 8.8 Hz,
1H, CH, pyridazine), 3.33 (t, J = 7.4 Hz, 2H, SeCH2,
hexyl), 1.87–1.77 (m, 2H, CH2, hexyl), 1.32–1.327 (m, 6H,
CH2, hexyl), 0.87 (t, J = 6.9 Hz, 3H, CH3, hexyl). 13C
NMR (CDCl3) δ 159.04, 155.25, 129.95, 129.16 (pyrida-
zine), 31.26, 29.66, 29.57, 26.57, 22.49, 13.95 (hexyl).
3-(iso-Propylselenyl)-6-chloropyridazine (5f ). Yield:
59%. m.p. 53–54ꢀC. 1H NMR (CDCl3)
δ
7.18
(d, J = 9.0 Hz, 1H, CH, pyridazine), 6.80 (d, J = 9.0 Hz,
1H, CH, pyridazine), 3.83 (m, 1H, CH, isopropyl), 1.58 (d,
J = 7.6 Hz, 6H, CH3, isopropyl). 13C NMR (CDCl3) δ
159.74, 154.17, 131.42, 127.33 (pyridazine), 34.80 (isopro-
pyl CH), 24.36 (isopropyl CH3). FT-IR (KBr) cm−1 3059
(aromatic), 1542(N N), 1492 (CH2), 1451 (CH3),
3-(n-Hexylsulfinyl)-6-chloropyridazine (6e). Yield:
48%. m.p. 62–65ꢀC. 1H NMR (CDCl3)
δ
8.12
(d, J = 8.7 Hz, 1H, CH, pyridazine), 7.76 (d, J = 8.7 Hz,
1H, CH, pyridazine), 3.28–3.19 (m, 1H, SCH2, hexyl),
3.08–2.97 (m, 1H, SCH2, hexyl), 1.91–1.86 (m, 1H, CH2,
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hexyl), 1.60–1.54 (m, 1H, CH2, hexyl), 1.53–1.30 (m, 2H,
CH2, hexyl), 1.28–1.24 (m, 4H, CH2, hexyl), 0.86
(t, J = 6.9 Hz, 3H, CH3, hexyl). 13C NMR (CDCl3) δ 168.62,
157.89, 129.82, 125.70 (pyridazine), 55.32, 31.21, 28.17,
22.30, 21.57, 13.85 (hexyl). FT-IR (KBr) cm−1 3025 (aro-
matic), 1543 (N N), 1492, 1452 (CH2), 1028 (SO),
540 (CCl). GC-MS m/z (%) 246.76 (M+) 123.00 (base peak).
General Synthetic Procedure for Alkylsulfonylpyrida-
zines 7a–7e. The compound 7a–7e was prepared from 3-
chloroalkylthiopyridazine 4a–4e as a white solid using a
modification of a previously reported oxidation method.16
3-(Ethylsulfonyl)-6-chloropyridazine (7a). Yield: 51%.
(CCl). GC-MS m/z (%) 248.69 (M+) 78.90 (100.0), 113.90
(97.3), 140.90 (76.3), 115.90 (31.9), 155.90 (29.5).
3-(n-Hexylsulfonyl)-6-chloropyridazine (7e). Yield:
78%. m.p. 88–90ꢀC. 1H NMR (CDCl3) δ 8.15 (d, J = 8.8 Hz,
1H, CH, pyridazine), 7.80 (d, J = 8.8 Hz, 1H, CH, pyrida-
zine), 3.59 (t, J = 8.0 Hz, 2H, SCH2, hexyl), 1.85–1.75 (m,
2H, CH2, hexyl), 1.48–1.39 (m, 2H, CH2, hexyl), 1.30–1.27
(m, 4H, CH2, hexyl), 0.86 (t, J = 6.7 Hz, 3H, CH3, hexyl).
13C NMR (CDCl3) δ 161.11, 159.74, 130.00, 126.63 (pyrida-
zine), 52.39, 31.02, 27.92, 22.19, 21.99, 13.81 (hexyl). FT-IR
(KBr) cm−1 3025 (aromatic), 1545 (N N), 1491, 1452 (CH2),
1320 (SO2), 1028 (SO), 702, 540 (CCl). GC-MS m/z (%)
262.69 (M+) 140.90 (100.0), 113.90 (93.6), 78.90 (82.3),
142.90 (32.3), 115.90 (31.1).
1
m.p. 68–70ꢀC. H NMR (CDCl3) δ 8.16 (d, J = 8.9 Hz,
1H, CH, pyridazine), 7.81 (d, J = 8.9 Hz, 1H, CH, pyrida-
zine), 3.67 (q, J = 14.9 Hz, 2H, SCH2, ethyl), 1.40
(t, J = 7.4 Hz, 3H, CH3, ethyl). 13C NMR (CDCl3) δ
160.68, 159.79, 130.03, 126.79 (pyridazine), 47.00, 6.78
(ethyl). FT-IR (KBr) cm−1 3025 (aromatic), 1545 (N N),
1491, 1452 (CH2), 1325, 1154 (SO2), 1028 (SO),
540 (CCl). GC-MS m/z (%) 206.69 (M+) 78.90 (100.0),
113.90 (62.9), 115.90 (20.0), 51.90 (15.9), 140.90 (13.6).
3-(n-Propylsulfonyl)-6-chloropyridazine (7b). Yield:
Acknowledgments. This research was supported by the
Duksung Women’s University Research Grants 2014.
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71%. m.p. 66–67ꢀC. 1H NMR (CDCl3)
δ
8.15
(d, J = 8.9 Hz, 1H, CH, pyridazine), 7.80 (d, J = 8.8 Hz,
1H, CH, pyridazine), 3.59 (m, 2H, SCH2, propyl), 1.86
(m, 2H, CH2, propyl), 1.08 (t, J = 7.2 Hz, 3H, CH3, pro-
pyl). 13C NMR (CDCl3) δ 161.25, 159.77, 129.99, 126.59
(pyridazine), 54.07, 16.03, 12.95 (propyl). FT-IR (KBr)
cm−1 3025 (aromatic), 1545 (N N), 1491, 1452 (CH2),
1320 (SO2), 1028 (SO), 540 (CCl). GC-MS m/z (%) 220.69
(M+) 78.90 (100.0), 113.90 (68.4), 127.90 (26.1), 115.90
(21.7), 51.90 (12.3).
3-(n-Butylsulfonyl)-6-chloropyridazine (7c). Yield:
64 %. m.p. 65–70ꢀC. 1H NMR (CDCl3)
δ 8.15
(d, J = 8.9 Hz, 1H, CH, pyridazine), 7.80 (d, J = 8.9 Hz,
1H, CH, pyridazine), 3.60 (t, J = 1.7 Hz, 2H, SCH2, butyl),
1.84–1.73 (m, 2H, CH2, butyl), 1.53–1.41 (m, 2H, CH2,
butyl), 0.95 (t, J = 4.5 Hz, 3H, CH3, butyl). 13C NMR
(CDCl3) δ 161.25, 159.77, 129.93, 126.54 (pyridazine),
52.14, 23.09, 21.53, 13.32 (butyl). FT-IR (KBr) cm−1 3025
(aromatic), 1545 (N N), 1491, 1452 (CH2), 1319, 1181,
1154 (SO2), 1028 (SO), 702, 540 (CCl). GC-MS m/z (%)
234.69 (M+) 78.90 (100.0), 113.90 (68.5), 127.90 (26.2),
115.90 (22.0), 51.90 (12.3).
3-(n-Pentylsulfonyl)-6-chloropyridazine (7d). Yield:
79%. m.p. 77–82ꢀC. 1H NMR (CDCl3)
δ
8.14
(d, J = 8.8 Hz, 1H, CH, pyridazine), 7.79 (d, J = 8.8 Hz,
1H, CH, pyridazine), 3.61 (t, J = 2.9 Hz, 2H, SCH2, pen-
tyl), 1.86–1.78 (m, 2H, CH2, pentyl), 1.47–1.27 (m, 4H,
CH2, pentyl), 0.89 (t, J = 4.6 Hz, 3H, CH3, pentyl). 13C
NMR (CDCl3) δ 161.12, 159.73, 130.00, 126.62 (pyrida-
zine), 52.35, 30.33, 21.72, 21.68, 13.59 (pentyl). FT-IR
(KBr) cm−1 3025 (aromatic), 1545 (N N), 1491, 1452
(CH2), 1319, 1180, 1153 (SO2), 1028 (SO), 702, 540
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