Synthesis and calming activity of 2-amino-4-(4-β-d-allopyranoside- phenyl)-6-3(4)-substituted phenylpyrimidines

Article abstract of DOI:10.1007/s10600-010-9739-6

Using helicid as starting material, E-4-β-D-allopyranoside-cinnamic-4- substituted phenylketones (1a-1h) containing the structure of chalcones were synthesized; then these chalcones were reacted with guanidine hydrochloride through a 1, 4-Michael reaction

Full text of DOI:10.1007/s10600-010-9739-6

Chemistry of Natural Compounds, Vol. 46, No. 5, 2010
SYNTHESIS AND CALMING ACTIVITY OF 2-AMINO-4-(4-ꢀ-D-ALLO-
PYRANOSIDE-PHENYL)-6-3(4)-SUBSTITUTED PHENYLPYRIMIDINES
XiuJuan Yin, Lei Zheng, Ying Li, and ShuFan Yin*
UDC 547.495.9
Using helicid as starting material, E-4-ꢀ-D-allopyranoside-cinnamic-4-substituted phenylketones (1a–1h)
containing the structure of chalcones were synthesized; then these chalcones were reacted with guanidine
hydrochloride through a 1,4-Michael reaction, giving 2-amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-3(4)-
1
substituted phenylpyrimidines (2a–2h), which were characterized by IR, H NMR, and HR-MS. The target
compounds were evaluated by the spontaneous locomotor activity test, showing that all of them had good
calming activity; compound 2f was found to have the greatest.
Keywords: helicid, guanidine hydrochloride, pyrimidine, calming activity.
Helicid (4-formylphenyl-ꢀ-D-allopyranoside, C H O ) is a pure natural compound extracted from the fruit of
13 16
7
Helicia nilagirica Beed, which has been successfully used in the treatment of patients with insomnia in China. It has good
biological activities, such as calming and sleep-inducing activity for the treatment of neurasthenia and neurasthenia syndrome
caused by headache, poisoning, or rheumatism [1–3]. However, it also has some disadvantages, such as slow action and low
biological utilization. Therefore, in order to obtain helicid analogues with better therapeutic effect and low side effect, we try
our best to search for a ‘‘superhelicid’’.
Our attention was focused on the restructuring of the formyl group of aromatic ring of 4-formylphenyl-ꢀ-D-
allopyranoside. 1-Substituted N-methyl-series derivatives [4, 5], benzimidazole derivatives [6, 7], and oxadiazoline and isoxazole
derivatives [8, 9] were obtained by the Mannich reaction, condensation reaction, and 1,3-dipolar cycloaddition reaction,
respectively. Because pyrimidines have the basic nucleus in nucleic acids and have been associated with a number of biological
activities [10–12], the pyrimidine ring was introduced into the structure of helicid in order to further improve the biological
activities of helicid.
Styryl-acetophenone, guanidine hydrochloride, and KOH can be directly generate the pyrimidine ring [13, 14]. In
this paper, the extension of the formyl conjugate carbon chain was performed by the Shmidt-Claisen reaction to get
ꢁ,ꢀ-unsaturated carbonyl derivatives 1a–1h. Because helicid is similar to the acetal structure, which is more stable in the base
solution than in the acid solution [15], guanidine hydrochloride was neutrallized with KOH solution, and then pyrimidine
derivatives 2a–2h were obtained through 1,4-Michael reaction.
R
1
R
2
NH
HOH C
2
.
HCl
2
HOH C
2
O
O
HO
H N
N
NH
2
O
O
R
1
HO
N
OH
OH
O
KOH, EtOH/H O
2
OH
NH
R
2
OH
2
1a - h
2a - 2h
a: R = R = H; b: R = CH , R = H; c: R = CH CH , R = H; d: R = OCH , R = H
1
2
1
3
2
1
2
3
2
1
3
2
e: R = F, R = H; f: R = Cl, R = H; g: R = Br, R = H; h: R = H, R = Cl
1
2
1
2
1
2
1
2
College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China, fax: 86 028 85503392, e-mail:
chuandayouji217@163.com. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 657–659, September–October, 2010.
Original article submitted April 23, 2009.
0009-3130/10/4605-0779 02010 Springer Science+Business Media, Inc.
779

TABLE 1. Sedative-hypnotic Activities for Target Compounds Evaluated Using the Spontaneous Locomotor Activity Test
Number of movements per minute
Compound
initial
after 15 min
after 30 min
after 60 min
after 90 min
after 120 min
Saline
Diazepam
Helicid
2a
217.67ꢂ8.24
209.00ꢂ9.72
214.14ꢂ92.87
181.83ꢂ36.20
3.17ꢂ2.79***
168.27ꢂ31.00
170.33ꢂ32.05
3.17ꢂ1.90***
136.01ꢂ66.92
163.67ꢂ29.18
0.67ꢂ0.49**
149.35ꢂ42.75
165.33ꢂ31.83
0.00ꢂ0.00**
139.61ꢂ52.14
160.67ꢂ29.43
4.00ꢂ2.02**
146.26ꢂ30.63
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
218.1 17.71
171.00 25.85
112.50 18.14
136.17 35.75
92.67 33.44*
99.00 34.19*
2b
222.50ꢂ15.58
214.67ꢂ14.91
213.00ꢂ10.49
213.33ꢂ24.78
207.50ꢂ6.30
208.83ꢂ13.04
88.33ꢂ24.08**
95.50ꢂ21.15**
122.50ꢂ27.98
202.50ꢂ17.21
111.00ꢂ8.03*
141.17ꢂ29.44
119.00ꢂ34.12
135.83ꢂ13.88
69.33ꢂ18.05**
146.00ꢂ34.73
43.83ꢂ15.83**
50.00ꢂ28.24*
107.33ꢂ26.92
119.83ꢂ18.61
161.67ꢂ24.40
68.17ꢂ29.55**
72.00ꢂ28.53
77.50ꢂ36.04
168.67ꢂ26.94
148.50ꢂ20.99
110.00ꢂ28.48
138.83ꢂ34.65
90.33ꢂ21.63
90.83ꢂ24.41
112.83ꢂ37.86
110.17ꢂ27.92
107.83ꢂ36.20
52.67ꢂ20.74**
14.17ꢂ7.88***
59.50ꢂ28.76**
2c
2d
2e
2f
2g
2h
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
ꢂ
59.67 23.54**
215.00 15.61
154.50 13.95
76.00 25.49*
84.33 19.89
109.67 33.68
______
Values are means ꢂ S. *P < 0.05, **P < 0.01, ***P < 0.001 compared with saline.
–1
–1
Dose of compound: 200 mg·kg ; diazepam, 20 mg·kg .
The results of spontaneous locomotor activity test are shown in Table 1. Compared with saline helicid, all the compounds
tested showed good calming activities. Moreover, compounds 2e, 2f, 2g, and 2h significantly altered the spontaneous locomotor
activity. After 30 min the motor activity of derivatives 2e, 2f, 2g, and 2h decreased from 213.33 ꢂ 24.78, 207.50 ꢂ 6.30,
208.83 ꢂ 13.04, and 215.00 ꢂ 15.61 movements/min to 146.00 ꢂ 34.73, 43.83 ꢂ 15.83, 50.00 ꢂ 28.24, and 76.00 ꢂ 25.49
movements/min, respectively. After 120 min the motor activity of derivatives 2e, 2f, 2g, and 2h decreased from 146.00 ꢂ 34.73,
43.83 ꢂ 15.83, 50.00 ꢂ 28.24, and 76.00 ꢂ 25.49 movements/min to 52.67 ꢂ 20.74, 14.17 ꢂ 7.88, 59.50 ꢂ 28.76, and 59.67 ꢂ 23.54
movements/min, respectively. In particular, compound 2f was found to be the best. In general, the order of calming activities
of the 2-amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-3(4)-substituted-aryl-pyrimidines at the -6-[3(4)-substituted] phenyl position
was electron-drawing groups > electron-donating groups. Comparison of substituents at the 3 and 4 positions showed that
4-substituents were better. Compounds 2a–2h were characterized and evaluated for their calming activities in mice. So further
modification of helicid should be worthwhile.
EXPERIMENTAL
Materials see [16].
Mice (Kunming strain) weighting 17–22 g were obtained from the West China School of Pharmacy at Sichuan
University (Chengdu China). All samples were dissolved in 0.9% NaCl solution to form different concentrations of solutions
for later use.
Compounds 1a, 1b, 1d, 1f, and 1g were prepared according to [17], while compounds 1c and 1e were prepared
according to [18].
E-4-ꢀ-D-Allopyranoside-cinnamic-3-chlorophenyl Ketone (1h). To a solution of helicid (1.420 g, 5 mmol) in
30 mL of anhydrous ethanol, 10% NaOH aqueous solution were added in a period of about 30 min under an ice bath, and then
3-substituted hypnone (2.310 g, 5.5 mmol) was added. This reaction was maintained at 0ꢃC for 10 h, monitored by TLC. The
solution was neutralized with diluted hydrochloric acid after the reaction ended, then concentrated to half of the original
volume; then water (30 mL) was added. The solid was filtered and recrystallized from ethanol–H O (5:1) to give a pale yellow
2
solid.
[ꢁ]2D5
–1
Yield 80%, mp 90–94ꢃC,
–28.10ꢃ (c 0.017 mol/L, C H OH). IR (KBr, cm ): 3380, 3068, 2892, 1653, 1596,
1508, 1423, 1215, 1172, 1078, 1033, 975, 809, 693, 788, 614. H NMR (400 MHz, DMSO-d , ꢄ, J/Hz): 4.50–5.20 (6H, m),
2
5
1
6
3.35–3.85 (4H, br, 4OH), 5.22–5.23 (1H, m, OCHO), 7.81 (1H, d, J = 16.0, CH=CHCO), 7.30–7.70 (4H, m, Ar-H), 7.60–8.00
+
(4H, m, m-Cl-Ar-H). HR-MS-ESI calcd for C H O Na [M + Na] : 443.0866, found: 443.0867.
21 21
7
General Procedure for 2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-3(4)-substituted-phenyl-pyrimidines (2a–2h).
Guanidine hydrochloride (1.43 g, 15 mmol) was dissolved in 10 mL of water, then neutralized with 20% KOH aqueous
solution, which was then heated to 50–60ꢃC for 0.5 h. Then an ethanol solution of 1a (5 mmol) was added, and the mixture
780

stirred at reflux temperature for 7–8 h. The reaction was monitored by TLC, concentrated under reduce pressure in a rotary
evaporator, and the crude product was purified by flash chromatography on silica gel (MeOH–CHCl , 1:6, v/v) to afford the
3
pure compound 2a.
2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-phenylpyrimidine (2a). This compound was prepared from compound
25
–1
1a. Yellow solid, yield 64%, mp 150–152ꢃC,
ꢅ–27.61ꢃ (c 0.016 mol/L, C H OH). IR (KBr, cm ): 3361, 2920, 1609,
[ꢁ]D
2 5
1
1570, 1539, 1511, 1452, 1365, 1231, 1179, 1079, 1036, 916, 830, 771, 695. H NMR (400 MHz, DMSO-d , ꢄ): 3.95 (2H, s,
6
NH ), 4.55–5.30 (6H, m), 3.30–3.80 (4H, br, 4OH), 5.21–5.24 (1H, m, OCHO), 6.80 (1H, s, 5-H), 7.10–7.80 (4H, m, Ar-H),
2
+
8.10–8.30 (5H, m, Ar-H). HR-MS-ESI calcd for C H N O [M + H] : 426.1660, found: 426.1642.
22 24
3 6
2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl-6-(4-methylphenyl)pyrimidine (2b). This compound was prepared from
[ꢁ]2D5
–1
compound 1b. Yellow solid, yield 62%, mp 150–153ꢃC,
–28.35ꢃ (c 0.021 mol/L, C H OH). IR (KBr, cm ): 3381,
2
5
1
2920, 1609, 1579, 1538, 1509, 1445, 1366, 1233, 1132, 1080, 1036, 916, 815, 754, 653. H NMR (400 MHz, DMSO-d , ꢄ):
6
2.31 (3H, s, CH ), 3.96 (2H, s, NH ), 4.55–5.25 (6H, m), 3.35–4.00 (4H, br, 4OH), 5.24–5.26 (1H, m, OCHO), 6.7 (1H, s, 5-H),
3
2
+
7.10–7.60 (4H, m, Ar-H), 8.20–8.30 (4H, m, p-CH -Ar-H). HR-MS-ESI calcd for C H N O [M + H] : 440.1816, found:
3
23 26 3 6
440.1802.
2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-(4-ethylphenyl)pyrimidine (2c). This compound was prepared from
25
–1
compound 1c. Yellow solid, yield 61%, mp 152–154ꢃC,
–27.41ꢃ (c 0.025 mol/L, C H OH). IR (KBr, cm ): 3401, 2920,
2 5
[ꢁ]D
1
1641, 1571, 1536, 1512, 1453, 1367, 1232, 1180, 1081, 1037, 915, 831, 771, 574. H NMR (400 MHz, DMSO-d , ꢄ): 1.25
6
(3H, t, CH ), 2.35 (2H, q, CH ), 3.98 (2H, s, NH ), 4.60–5.30 (6H, m), 3.40–3.80 (4H, br, 4OH), 5.24–5.26 (1H, m, OCHO),
3
2
2
+
6.50 (1H, s, 5-H), 7.10–7.40 (4H, m, Ar-H), 8.10–8.30 (4H, m, p-CH CH -Ar-H). HR-MS-ESI calcd for C H N O [M + H]
2
3
24 28 3 6
454.1973, found: 454.1992.
2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-(4-methoxyphenyl)pyrimidine (2d). This compound was prepared
25
–1
from compound 1d. Yellow solid, yield 63%, mp 149–151ꢃC,
–28.13ꢃ (c 0.026 mol/L, C H OH). IR (KBr, cm ): 3353,
[ꢁ]D
2
5
1
2925, 1622, 1569, 1538, 1511, 1461, 1365, 1232, 1153, 1078, 1034, 916, 828, 787, 695. H NMR (400 MHz, DMSO-d , ꢄ):
6
3.20 (3H, s, OCH ), 3.90 (2H, s, NH ), 4.55–5.25 (6H, m), 3.35–4.00 (4H, br, 4OH), 5.22–5.24 (1H, m, OCHO), 6.70 (1H, s,
3
2
+
5-H), 7.10–7.60 (4H, m, Ar-H), 8.15–8.35 (4H, m, p-OCH -Ar-H). HR-MS-ESI calcd for C H N O [M + H] : 456.1765,
3
23 26 3 7
found: 456.1767.
2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-(4-fluorophenyl)pyrimidine (2e). This compound was prepared from
[ꢁ]25
–1
compound 1e. Yellow solid, yield 65%, mp 152–153ꢃC,
–27.55ꢃ (c 0.022 mol/L, C H OH). IR (KBr, cm ): 3365, 2923,
D
2
5
1
1604, 1575, 1540, 1508, 1446, 1366, 1229, 1180, 1080, 1037, 911, 823, 755, 639. H NMR (400 MHz, DMSO-d , ꢄ): 3.95
6
(2H, s, NH ), 4.40–5.10 (6H, m), 3.25–3.80 (4H, br, 4OH), 5.25–5.27 (1H, m, OCHO), 6.75 (1H, s, 5-H), 7.10–7.40 (4H, m,
2
+
Ar-H), 8.15–8.35 (4H, m, p-F-Ar-H). HR-MS-ESI calcd for C H FN O [M + H] : 444.1565, found: 444.1556.
22 23
3 6
2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-(4-chlorophenyl)pyrimidine (2f). This compound was prepared from
25
–1
compound 1f. Yellow solid, yield 66%, mp 152–154ꢃC,
–26.34ꢃ (c 0.020 mol/L, C H OH). IR (KBr, cm ): 3377, 2922,
[ꢁ]D
2 5
1
1613, 1584, 1536, 1511, 1445, 1364, 1231, 1179, 1084, 1038, 910, 819, 775, 637. H NMR (400 MHz, DMSO-d , ꢄ): 3.90
6
(2H, s, NH ), 4.55–5.25 (6H, m), 3.35–4.0 (4H, br, 4OH), 5.22–5.24 (1H, m, OCHO), 6.70 (1H, s, 5-H), 7.10–7.60 (4H, m, Ar-
2
+
H), 8.15–8.35 (4H, m, p-Cl-Ar-H). HR-MS-ESI calcd for C H ClN O [M + H] : 460.1270, found: 460.1248.
22 23
3 6
2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-(4-bromophenyl)pyrimidine (2g). This compound was prepared from
[ꢁ]25
–1
compound 1g. Yellow solid, yield 65%, mp 153–155ꢃC,
–28.00ꢃ (c 0.017 mol/L, C H OH). IR (KBr, cm ): 3369, 2921,
D
2
5
1
1610, 1586, 1538, 1511, 1445, 1363, 1231, 1178, 1080, 1036, 912, 817, 754, 619. H NMR (400 MHz, DMSO-d , ꢄ): 3.95
6
(2H, s, NH ), 4.50–5.20 (6H, m), 3.35–3.85 (4H, br, 4OH), 5.22–5.24 (1H, m, OCHO), 6.80 (1H, s, 5-H), 7.10–7.80 (4H, m,
2
+
Ar-H), 8.15–8.35 (4H, m, p-Br-Ar-H); HR-MS-ESI calcd for C H BrN O [M + H] : 504.0765, found: 504.0754.
22 23
3 6
2-Amino-4-(4-ꢀ-D-allopyranoside-phenyl)-6-(3-chlorophenyl)pyrimidine (2h). This compound was prepared from
[ꢁ]2D5
–1
compound 1h. Yellow solid, yield 61%, mp 152–153ꢃC,
–26.62ꢃ (c 0.019 mol/L, C H OH). IR (KBr, cm ): 3380,
2
5
1
2921, 1570, 1571, 1538, 1512, 1444, 1361, 1231, 1179, 1079, 1036, 907, 827, 788, 614. H NMR (400 MHz, DMSO-d , ꢄ):
6
3.95 (2H, s, NH ), 4.50–5.20 (6H, m), 3.35–3.85 (4H, br, 4OH), 5.24–5.26 (1H, m, OCHO), 6.80 (1H, s, 5-H), 7.10–7.60 (4H,
2
+
m, Ar-H), 8.15–8.35 (4H, m, m-Cl-Ar-H). HR-MS-ESI calcd for C H ClN O [M + H] : 460.1270, found: 460.1275.
22 23
3 6
Biological Activity Tests. All the target compounds were tested for sedative-hypnotic activities by the spontaneous
locomotor activity method. All samples were dissolved in saline (200 mg/kg). Diazepam was dissolved in saline (20 mg/kg)
for use later. Sixty-six mice were randomized into 11 groups of 6 mice each (3 male and 3 female). In order to maintain suitable
environmental conditions throughout the experiments, all mice were placed in a recorder for 5 min before the experiments.
Group A received saline by injection, group B received diazepam (20 mg/kg, i.p.), group C received 4-formylphenyl-ꢀ-D-
781

allopyranoside (20 mg/kg, i.p.), and groups 2a–2h received the synthesized compounds (200 mg/kg, i.p.). 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 the
spontaneous activity was recorded for 5 min after 0, 15, 30, 60, 90, and 120 min. The data were recorded as number of
movements per minute.
ACKNOWLEDGMENT
We are grateful to the Analytical & Testing Center of Sichuan University, P. R. China for providing analytical data,
and Mr. Bao (College of Pharmacy, Sichuan University) for completing the sedative-hypnotic test.
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