Synthesis and sedative activity of 5-(4'-β-D-allopyranosyloxyphenyl)- 3-aryl- 4,5-dihydropyrazole-1-carbothioamides

Article abstract of DOI:10.1007/s10600-010-9631-4

5-(4'-β-D-Allopyranosyloxyphenyl)-3-aryl-4,5-dihydropyrazole-1- carbothioamides (2a-2h) were synthesized by the reaction of (1a-1h) with thiosemicarbazide and KOH in ethanol. The structures of all new compounds were characterized by ¹HNMR, IR, and MS (HR-MS) spectra. A preliminary bioassay test of 1f-1h and 2a-2h suggested that most of these helicid analogues showed mild to strong activity. Compounds 1g, 2a, 2c, and 2f at a dose of 200 mg?kg^-1 were better than that of the parent helicid.

Full text of DOI:10.1007/s10600-010-9631-4

Chemistry of Natural Compounds, Vol. 46, No. 3, 2010
SYNTHESIS AND SEDATIVE ACTIVITY OF
5-(4ꢀ-ꢁ-D-ALLOPYRANOSYLOXYPHENYL)-3-ARYL-
4,5-DIHYDROPYRAZOLE-1-CARBOTHIOAMIDES
Li Fu, Ding Ye, Guo Peng Chen, Ying Li,
and Shu Fan Yin*
UDC 547.772
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-aryl-4,5-dihydropyrazole-1-carbothioamides (2a–2h) were synthesized
by the reaction of (1a–1h) with thiosemicarbazide and KOH in ethanol. The structures of all new compounds
1
were characterized by HNMR, IR, and MS (HR-MS) spectra. A preliminary bioassay test of 1f–1h and
2a–2h suggested that most of these helicid analogues showed mild to strong activity. Compounds 1g, 2a, 2c,
–1
and 2f at a dose of 200 mg·kg were better than that of the parent helicid.
Keywords: helicid, Claisen-Schmidt reaction, pyrazoline, carbothioamide.
Natural helicid (4-formylphenyl-ꢁ-D-allopyranoside, C H O ), a major active ingredient in Chinese herbal medicine,
13 16
7
is a pure compound extracted from the fruit of Helicia nilagirica Beed [1], which is distributed widely in Yunnan Province of
China. It has been reported that helicid possesses a variety of biological activities, including sedative, hypnotic, analgesic,
anticonvulsant, and so on [2]. But helicid also has side effects, such as the large dose required, slow action, and low biological
utilization. Therefore, multiple approaches are being sought to overcome these limitations. Our laboratoryꢀs attention was
focused on modification at the aldehyde group of helicid [3–6], which gave good results. In recent years, increasing evidence
suggests that pyrazoline derivatives possess a broad spectrum of biological activities [7–13], such as antibacterial, antifungal,
antimicrobial, antidepressant, and anticonvulsant. Herein, in order to obtain helicid analogues with excellent therapeutic effect
and low side effect, we successfully used pyrazoline in the structure modification of helicid. In this paper, we synthesized
eleven helicid derivatives through Schmidt-Claisen condensation and addition reaction. The structures of all new compounds
1
were characterized by H NMR, IR, and MS spectra, and the sedative-hypnotic activity produced by the target derivatives was
–1
investigated by the spontaneous activity test. Compounds 1g, 2a, 2c, and 2f at a dose of 200 mg·kg was better than that of the
parent helicid.
R
H
OH
O
a
H
b
OH
O
3
4
O
CH CH
C
R
O
4'
5
N
HO
HO
NH C(S)NHNH
2 2
O
HO
HO
N
EtOH/KOH, reflux
HO
H
x
HO
H N
S
2
1a - h
2a - h
1a,2a: R = H; 1b,2b: R = CH ; 1c,2c: R = OCH ; 1d,2d: R = Cl
3
3
1e,2e: R = Br; 1f,2f: R = F; 1g,2g: R = C H ; 1h,2h: R = NO
2
5
2
Department of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China, fax: 86 028 85503392, e-mail:
chuandayouji217@163.com. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 353–355, May–June, 2010. Original
article submitted December 26, 2008.
0009-3130/10/4603-0417 02010 Springer Science+Business Media, Inc.
417

TABLE 1. Spontaneous Motion Results of Target Compounds in Mice
Post-administration, x ꢆ s
Compounda
Pre-administration, x ꢆ s
30 min
60 min
90 min
103.33 56.10
0.05% CMC
161.00 21.72
141.00 20.55
121.33 77.81
ꢆ
ꢆ
ꢆ
ꢆ
Diazepamb
163.17 40.91
34.83 23.27**
18.00 26.65*
8.00 19.60**
ꢆ
ꢆ
ꢆ
ꢆ
Helicid
1f
1g
163.83 76.08
162.5 50.23**
130.67 69.04
70.67 44.27**
ꢆ
ꢆ
ꢆ
ꢆ
151.33 36.01
144.00 102.73
112.83 35.75
91.17 92.29
ꢆ
ꢆ
ꢆ
ꢆ
162.17ꢆ49.47
116.17ꢆ77.22
114.50ꢆ40.89
60.17ꢆ34.65**
1h
2a
2b
2c
2d
2e
169.47 59.67
159.51 64.12
168.27 68.34
115.85 45.46*
ꢆ
ꢆ
ꢆ
ꢆ
161.00 47.62
92.17 49.79
71.50 16.90
42.00 53.35**
ꢆ
ꢆ
ꢆ
ꢆ
181.67ꢆ28.76
115.83ꢆ68.05
90.33ꢆ54.13
96.00ꢆ65.78
34.33 24.38**
ꢆ
167.67 51.84
86.67 43.36*
103.00 51.79
ꢆ
ꢆ
ꢆ
163.50 58.75
107.60 74.39
78.67 73.05
73.50 49.29
ꢆ
83.17 61.69
ꢆ
ꢆ
ꢆ
ꢆ
166.83 55.64
182.83 123.71
119.50 37.77
ꢆ
ꢆ
ꢆ
2f
2g
171.83 55.87
105.33 53.40
99.00 48.15
39.83 35.27**
ꢆ
ꢆ
ꢆ
ꢆ
162.00ꢆ38.62
157.67ꢆ53.40
122.17ꢆ28.29
91.17ꢆ49.96
152.33 42.53
119.50 54.12
88.17 78.94
99.00 72.96
ꢆ
______ 2h
ꢆ
ꢆ
ꢆ
a
b
*P<0.05; **P<0.01 compared with 0.05% CMC. Dose: 200 mg/kg. Diazepam: 20 mg/kg. Number of animals: 6.
In the present study, the title compounds were synthesized by a two-step reaction as shown in Scheme 1. All of the
1
new compounds were identified using IR, H NMR, and MS (HR-MS). The IR spectra of compounds 2a–2h showed NH
2
–1
–1
–1
stretching bands at 3435–3427 cm and 3376–3343 cm and C=N stretching bands at 1595–1577 cm due to ring closure,
and C=S stretching bands at 1407–1344 cm . In H NMR spectra, protons CH -CH of the pyrazoline fragment of the
–1
1
2
synthesized compounds 2a–2h show characteristic patterns of an ABX system. The chemical shifts of H , H , and H have
A
B
X
been assigned to about ꢂ 3.00–3.22, ꢂ 3.35–3.45, and ꢂ 5.76–5.93, respectively, with corresponding coupling constants of
= 17.8–18.4 Hz, J = 7–11.4 Hz, and J = 4.2–7.4 Hz. According to the currently accepted mechanism, formation of the
J
AB
BX
AX
cyclized pyrazoline analogues proceeds via the thiosemicarbazone, which undergoes cyclization under basic conditions to
form the desired pyrazoline ring in all the compounds [14].
To summarize, a concise and effective procedure has been successfully developed for the synthesis of helicid derivatives
containing pyrazoline. The results of the present investigation should be of value in the synthesis of structural analogs.
EXPERIMENTAL
Helicid was purchased from Yunnan Chemical Company of China. Mice (Kunming strain) weighing 18–22 g were
obtained from West China School of Pharmacy, Sichuan University (Chengdu China). Flash column chromatography was
performed on silica gel (300–400 mesh, Qingdao, China). Thin-layer chromatography (TLC) was performed on percolated
Merck silica gel 60F plates. Diazepam injects was purchased from Tianjin Jiaozuo Pharmaceutical Co. Ltd. (China) (Batch
254
number 030708-1). All the other reagents and solvent were commercially available and used without further purification.
Compounds 1a–1e were prepared according to the method in the literature [5].
1
Melting points were determined on a Thomas-Hoover melting point apparatus and are uncorrected. H NMR spectra
were taken on a BrukerAV-400 MHz spectrometer with TMS as an internal standard. IR spectra were recorded on a Perkin–Elmer
FT-IR spectrometer (KBr disk). Mass spectra were obtained on a Finnigan-LCQDECA mass spectrometer (ESI-LR-MS) and
a Bruker Daltoics Bio TOF-Q mass spectrometer (ESI-HR-MS). An electronic balance (Sartorius BS210S) and multi-function
mice locomotor activity recorder (YLS-1A) were used.
Procedure for the Preparation of Compounds 1f–1h ꢃ15ꢄ.
E-(4-ꢁ-D-Allopyranosyloxyphenyl)-1-(4-nitrophenyl)-propenone (1h). This compound was prepared from
4-nitroacetophenone. Yield: 310 mg, 72%, pale yellow solid, mp 85–87ꢅC.
–1
1
IR (KBr, cm ): 3391, 2918, 1662, 1574, 1519, 1452, 1343, 1247, 1108, 1083, 1030, 986, 830. H NMR (400 MHz,
DMSO-d , ꢂ, ppm, J/Hz): 3.40–3.95 (6H, m), 5.20 (1H, d, J = 8.0, H-1), 7.82 (1H, d, J = 16.0, CH=CH), 7.09–8.39 (8H, m,
6
418

–
PhH), 8.34 (1H, d, J = 16.0, CH=CHCO), 4.51–5.11 (4H, br, 4-OH). ESI-LR-MS m/z: 466.0887 [M + Cl] ; calcd for
C H Cl O N , 466.0899.
21 21
1 9 1
General Procedure for the Preparation of Compounds 2a–2h. In a round bottomed flask, a mixture of 1a–1h
(1 mmol), thiosemicarbazide (1.2 mmol), and potassium hydroxide (0.11 g) in ethanol (15 mL) was introduced. The mixture
was heated to reflux, and the progress of the reaction was monitored by TLC. After the reaction ended, the mixture was
acidified with diluted hydrochloric acid (1 mol/L) to give a yellow solid, which was filtered. The solution was concentrated
under reduced pressure, and the residue was subjected to column chromatography. It was first eluted with ethyl acetate to
remove impurities, and then with chloroform, hexane, and methanol (7:5:2, volume ratio) as solvents to give products 2a–2h.
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-phenyl-4,5-dihydropyrazole-1-carbothioamide (2a). This compound was
prepared from 1a. Yield: 266 mg, 58%, yellow solid, mp 156–158ꢅC.
–1
IR (KBr, cm ): 3434, 3376, 2920, 1606, 1587, 1509, 1478, 1344, 1079, 1033, 976, 837, 692.
1
H NMR (400 MHz, DMSO-d , ꢂ, ppm, J/Hz): 3.13 (1H, dd, J = 6.4, J = 18.0, Ha-4), 3.44 (1H, dd, J = 11.2,
6
ax
ab
bx
J
= 18.0, Hb-4), 3.37–3.90 (6H, m), 5.08 (1H, d, J = 8.0, 1-H), 5.87 (1H, dd, J = 11.2, J = 6.4, Hx-5), 6.93–7.88 (9H, m,
ab
bx ax
PhH), 4.46–4.93 (4H, br, 4OH), 7.89–8.02 (2H, br, NH ).
2
+
ESI-LR-MS m/z: 482.1363 [M + Na] ; calcd for C H O N SNa, 482.1367.
22 25
6 3
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-(4-methylphenyl)-4,5-dihydropyrazole-1-carbothioamide (2b). This
compound was prepared from 1b. Yield: 255 mg, 54%, yellow solid, mp 143–145ꢅC.
–1
1
IR (KBr, cm ): 3431, 3376, 2921, 1602, 1588, 1509, 1478, 1446, 1361, 1346, 1233, 1080, 1033, 917, 692. H NMR
(400 MHz, DMSO-d , ꢂ, ppm, J/Hz): 2.35 (3H, s, CH ) 3.10 (1H, dd, J = 4.2, J = 18.0, Ha-4), 3.44 (1H, dd, J = 11.2,
6
3
ax
ab
bx
J
= 18.0, Hb-4), 3.35–3.90 (6H, m), 5.08 (1H, d, J = 8.0, H-1), 5.85 (1H, dd, J = 11.2, J = 4.2, Hx-5), 6.93–7.84 (8H, m,
PhH), 4.49–5.05 (4H, br, 4OH), 7.98–8.58 (2H, br, NH ). ESI-LR-MS m/z: 496.1524 [M + Na] ; calcd for C H O N SNa,
ab
bx ax
+
2
23 27 6 3
496.1524.
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-(4-methoxyphenyl)-4,5-dihydropyrazole-1-carbothioamide (2c). This
compound was prepared from 1c. Yield: 254 mg, 52%, yellow solid, mp 141–143ꢅC.
–1
1
IR (KBr, cm ): 3427, 3351, 2921, 1607, 1580, 1509, 1360, 1252, 1081, 1036, 973, 793, 699. H NMR (400 MHz,
DMSO-d , ꢂ, ppm, J/Hz): 3.10 (1H, dd, J = 4.4, J = 17.8, Ha-4), 3.44 (1H, dd, J = 7.6, J = 17.8, Hb-4), 3.36–3.91 (9H,
6
ax
ab
bx
ab
m), 5.08 (1H, d, J = 8.0, H-1), 5.84 (1H, dd, J = 7.6, J = 4.4, Hx-5), 6.93–7.83 (8H, m, PhH), 4.42–5.00 (4H, br, 4OH),
bx
ax
+
7.75–7.88 (2H, br, NH ). ESI-LR-MS m/z: 512.1464 [M + Na] ; calcd for C H O N SNa, 512.1473.
2
23 27 7 3
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-(4-chlorophenyl)-4,5-dihydropyrazole-1-carbothioamide (2d). This
compound was prepared from 1d. Yield: 306 mg, 62%, yellow solid, mp 170–172ꢅC.
–1
1
IR (KBr, cm ): 3435, 3369, 2913, 1595, 1509, 1471, 1360, 1233, 1082, 1035, 977, 828, 695. H NMR (400 MHz,
DMSO-d , ꢂ, ppm, J/Hz): 3.13 (1H, dd, J = 6.0, J = 18.0, Ha-4), 3.44 (1H, dd, J = 11.4, J = 18.0, Hb-4), 3.37–3.90 (6H, m),
6
ax
ab
bx
ab
5.08 (1H, d, J = 8.0, H-1), 5.87 (1H, dd, J = 11.4, J = 6.0, Hx-5), 6.93–7.92 (8H, m, PhH), 4.49–5.05 (4H, br, 4OH), 7.95–8.05
bx
ax
+
(2H, br, NH ). ESI-LR-MS m/z: 516.0953 [M + Na] ; calcd for C H Cl O N SNa, 516.0967.
2
22 24
1 6 3
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-(4-bromophenyl)-4,5-dihydropyrazole-1-carbothioamide (2e). This
compound was prepared from 1e. Yield: 301 mg, 56%, yellow solid, mp 157–159ꢅC.
–1
1
IR (KBr, cm ): 3434, 3369, 2920, 1606, 1589, 1509, 1359, 1233, 1072, 1008, 912, 825, 713. H NMR (400 MHz,
DMSO-d , ꢂ, ppm, J/Hz): 3.13 (1H, dd, J = 4.2, J = 17.8, Ha-4), 3.44 (1H, dd, J = 9.2, J = 17.8, Hb-4), 3.37–3.90 (6H,
6
ax
ab
bx
ab
m), 5.08 (1H, d, J = 8.0, H-1), 5.87 (1H, dd, J = 9.2, J = 4.2, Hx-5), 6.93–7.84 (8H, m, PhH), 4.49–5.05 (4H, br, 4OH),
bx
ax
+
7.95–8.05 (2H, br, NH ). ESI-LR-MS m/z: 560.0450 [M + Na] ; calcd for C H BrO N SNa, 560.0461.
2
22 24
6 3
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-(4-fluorophenyl)-4,5-dihydropyrazole-1-carbothioamide (2f). This
compound was prepared from 1f. Yield: 253 mg, 53%, yellow solid, mp 148–150ꢅC.
–1
1
IR (KBr, cm ): 3427, 3353, 2913, 1601, 1505, 1479, 1411, 1361, 1231, 1036, 977, 838, 713. H NMR (400 MHz,
DMSO-d , ꢂ, ppm, J/Hz): 3.13 (1H, dd, J = 7.4, J = 18.0, Ha-4), 3.44 (1H, dd, J = 11.2, J = 18.0, Hb-4), 3.33–3.90 (6H,
6
ax
ab
bx
ab
m), 5.08 (1H, d, J = 8.0, H-1), 5.86 (1H, dd, J = 11.2, J = 7.4, Hx-5), 6.93–7.88 (8H, m, PhH), 4.47–5.05 (4H, br, 4OH),
bx
ax
+
7.96–8.02 (2H, br, NH ). ESI-LR-MS m/z: 500.1245 [M + Na] ; calcd for C H FO N SNa, 500.1262.
2
22 24
6 3
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-(4-ethylphenyl)-4,5-dihydropyrazole-1-carbothioamide (2g). This
compound was prepared from 1g. Yield: 297 mg, 61%, yellow solid, mp 144–146ꢅC.
–1
1
IR (KBr, cm ): 3435, 3376, 2920, 1608, 1577, 1467, 1407, 1338, 1234, 1083, 977, 850, 691. H NMR (400 MHz,
DMSO-d , ꢂ, ppm, J/Hz): 1.15–1.19 (3H, t, CH ), 2.62 (2H, q, J = 15.2, CH ), 3.02 (1H, dd, J = 6.8, J = 18.0, Ha-4), 3.36
6
3
2
ax
ab
(1H, dd, J = 11.0, J = 18.4, Hb-4), 3.30–3.83 (6H, m), 5.01 (1H, d, J = 8.0, H-1), 5.78 (1H, dd, J = 11.0, J = 6.8, Hx-5),
bx
ab
bx
ax
419

+
6.84–7.22 (8H, m, PhH), 4.40–4.98 (4H, br, 4OH), 7.70–7.72 (2H, br, NH ). ESI-LR-MS m/z: 510.1669 [M + Na] ; calcd for
2
C H O N SNa, 510.1669.
22 29
6 3
5-(4ꢀ-ꢁ-D-Allopyranosyloxyphenyl)-3-(4-nitrophenyl)-4,5-dihydropyrazole-1-carbothioamide (2h). This
compound was prepared from 1h. Yield: 217 mg, 43%, yellow solid, mp 160–162ꢅC.
–1
1
IR (KBr, cm ): 3505, 3376, 2920, 1608, 1577, 1511, 1407, 1338, 1234, 1180, 1083, 1036, 977, 850, 691. H NMR
(400 MHz, DMSO-d , ꢂ, ppm, J/Hz): 3.20 (1H, dd, J = 6.0, J = 18.0, Ha-4), 3.43 (1H, dd, J = 11.4, J = 18.0, Hb-4),
6
ax
ab
bx
ab
3.34–3.94 (6H, m), 5.08 (1H, d, J = 8.0, H-1), 5.91 (1H, dd, J = 11.4, J = 6.0, Hx-5), 6.93–8.30 (8H, m, PhH), 4.49–5.06
bx
ax
+
(4H, br, 4OH), 8.21–8.27 (2H, br, NH ). ESI-LR-MS m/z: 527.1189 [M + Na] ; calcd for C H O N SNa, 527.1207.
2
22 24 8 4
The sedative-hypnotic activity of all the compounds was investigated by recording the number of spontaneous activities
in mice using a recorder; all samples were dissolved in 0.05%CMC (carboxymethyl cellulose) to form a solution (200 mg/kg)
for use later. Diazepam injects were dissolved in saline to a form solution (20 mg/kg) for use later. Eighty-four mice were
randomized in the experiment and divided into 14 groups of 6 mice each (3 male and 3 female). The mice were placed in the
recorder for 5 min before the experiments and maintained in suitable environmental conditions throughout the experiments.
–1
When testing, the prepared solutions were injected into the mouse stomach with a syringe in a volume of 0.2 mL·10 g body
weight, and then the number of spontaneous activities was recorded every 5 min at 30 min intervals. The data were recorded
–1
as number of movements per minute and are listed in Table 1. Compounds 1g, 2a, 2c, and 2f at a dose of 200 mg·kg were
better than that of the parent compound helicid. Thus, further modification of helicid should be worthwhile.
ACKNOWLEDGMENT
We thank the Analytical & Testing Center of Sichuan University, P. R. China for assistance in obtaining analytical
data.
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