Synthesis and antiviral activity of novel 1,3,4-thiadiazine derivatives

Article abstract of DOI:10.1248/cpb.59.1016

A series of novel 1,3,4-thiadiazine derivatives were synthesized via chemical optimization on phthiobuzone. Their anti-herpes simplex virus (HSV) activities in vitro were also tested. Several compounds exhibited more highly potent anti-HSV activity and much higher selectivity index (SI) values than those of phthiobuzone. The most potent anti-HSV compound was 4f, which showed marked inhibition against HSV-1 (IC₅₀=77.04μg/ml) and HSV-2 (IC₅₀=30.00μg/ml). Meanwhile it had low cytotoxicity (CC ₅₀=1000.00μg/ml), resulting in high (SI_HSV-1= 12.98, SI_HSV-2=33.33, respectively). Furthermore, a computational study for prediction of absorption, distribution, metabolism, excretion (ADME) properties of compound 4f was performed by determination of topological polar surface area, absorption and Lipinski parameters.

Full text of DOI:10.1248/cpb.59.1016

1016
Regular Article
Chem. Pharm. Bull. 59(8) 1016—1019 (2011)
Vol. 59, No. 8
Synthesis and Antiviral Activity of Novel 1,3,4-Thiadiazine Derivatives
a
a
a
Yajun YANG,a,b Ziming FENG, Jianshuang JIANG, Yanan YANG, Xiandao PAN, ,a,c and
*
,a
*
Peicheng ZHANG
a Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine (Ministry of Education),
Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing 100050,
People’s Republic of China: b Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Institute of
Laboratory Animal Science, Chinese Academy of Medical Sciences & Comparative Medical Center, Peking Union Medical
College; Beijing 100021, People’s Republic of China: and c Beijing Union Pharmaceutical Factory; Beijing 102600,
People’s Republic of China. Received April 2, 2011; accepted May 13, 2011; published online May 17, 2011
A series of novel 1,3,4-thiadiazine derivatives were synthesized via chemical optimization on phthiobuzone.
Their anti-herpes simplex virus (HSV) activities in vitro were also tested. Several compounds exhibited more
highly potent anti-HSV activity and much higher selectivity index (SI) values than those of phthiobuzone. The
most potent anti-HSV compound was 4f, which showed marked inhibition against HSV-1 (IC50ꢀ77.04 mg/ml) and
HSV-2 (IC50ꢀ30.00 mg/ml). Meanwhile it had low cytotoxicity (CC50ꢀ1000.00 mg/ml), resulting in high (SIHSV-1ꢀ
12.98, SIHSV-2ꢀ33.33, respectively). Furthermore, a computational study for prediction of absorption, distribu-
tion, metabolism, excretion (ADME) properties of compound 4f was performed by determination of topological
polar surface area, absorption and Lipinski parameters.
Key words 1,3,4-thiadiazine; phthiobuzone; antiviral activity; herpes simplex virus
Herpes viruses are responsible for a wide range of human ity. As part of our further research of TDA, chemical opti-
diseases. Conventional antiviral chemotherapy using nucleo- mization was performed on bisthiosemicarbazone, the core
side analogues such as acyclovir is effective in most cases, scaffold of TDA. In order to maintain degrees of similarity,
but is also prone to toxicity and drug resistance. These limi- we replaced bisthiosemicarbazone with different heterocy-
tations have fueled interest in developing novel antiviral cles containing sulfur and nitrogen atoms. This work resulted
agents.1—3)
in the synthesis of a series of 1,3,4-thiadiazine derivatives
Phthiobuzone (Ftibamzone, Tai Ding An, TDA, Fig. 1), 3- without losing biological action. Herein, we reported the syn-
phthalimido-2-oxo-n-butyraldehyde bisthiosemicarbazone, thesis and antiviral activity of those novel 1,3,4-thiadiazine
was used in clinic for treatment of herpes and trachoma dis- derivatives against HSV-1 and HSV-2.
eases in China and Egypt. In vitro anti-herpetic activity stud-
ies demonstrated that TDA possessed the effect of inhibiting Results and Discussion
virus plaque formation and reproduction against herpes sim-
The synthesis of 1,3,4-thiadiazine derivatives began with
plex virus 1 (HSV-1) and herpes simplex virus 2 (HSV-2). phthalandiones 1a—c (Chart 1). Condensation of compounds
Moreover, TDA has a unique mechanism of antiviral action, 1a—c with amino acids gave 2a—h,6) which were converted
which might be associated with ribonucleotide reductase, dif- into a-bromo ketones 3a—h according to the previous
ferent from those of the antiviral nucleotide analogues.4,5) method.5,7) Using NaHCO3 as base, cyclization of com-
But TDA has limited medicinal application due to its poor pounds 3a—h with 4-substituted thiosemicarbazides in re-
pharmaceutical profile, such as low activity and low solubil- fluxing EtOH gave compounds 4a—n, 4s, 4t and 5a—e in
moderate to good yields. The synthesis of compounds 4o—r
and 7 were illustrated in Chart 2. Acylation and alkylation of
4f afforded compounds 4o, 4p and 4q, 4r, respectively. Com-
pound 4f was reduced by NaBH4 to yield 6, which was fur-
ther methylated to give the corresponding compound 7.
The potential anti-HSV activity and cytotoxicity of the
Fig. 1. Structures of TDA and 1,3,4-Thiadiazine Derivatives
Chart 1. The Synthesis Route of Compounds 4a—n, 4s, 4t and 5a—e
∗ To whom correspondence should be addressed. e-mail: xdp@imm.ac.cn; pczhang@imm.ac.cn
© 2011 Pharmaceutical Society of Japan

August 2011
1017
Chart 2. The Synthesis Route of Compounds 4o—r and 7
Table 1. Anti-HSV-1 Activity (mg/ml), Cytotoxicity (mg/ml) and Selectivity Index of Compounds 4a—t, 5a—e and 7 in Vitro
a)
b)
Comp.
R1
R2
R3
R4
R5
n
CC50
IC50
SIc)
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
4s
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
NO2
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Br
H
H
H
H
H
H
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
H
Me
H
H
H
H
H
H
H
H
H
H
H
H
Me
c-Hexyl
4-Cl-Bn
Allyl
Bn
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
2
0
0
333.33
192.45
192.45
557.35
192.45
1000.00
192.45
192.45
192.45
21.38
ꢁ111.11
ꢁ111.11
ꢁ111.11
77.04
7.23
2.50
12.98
3.00
77.04
77.04
64.15
Ph
4-MeO-Ph
4-Me-Ph
4-NO2-Ph
2-F-Ph
4-F-Ph
4-Cl-Ph
3-Pyridyl
2-Pyridyl
Ph
ꢁ111.11
ꢁ111.11
ꢁ12.34
ꢁ37.03
ꢁ37.03
ꢁ333.33
333.33
111.11
ꢁ37.04
ꢁ111.11
47.72
ꢁ111.11
111.11
ꢁ111.11
ꢁ111.11
25.68
64.15
64.15
557.35
333.33
192.45
111.11
192.45
192.45
192.45
480.75
192.45
192.45
192.45
53.41
H
1.00
1.73
Bz
Ac
Me
Bn
H
H
H
H
H
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
4.03
4t
4.32
5a
5b
5c
5d
5e
7
H
H
Bn
i-Bu
7.49
4.32
H
H
Ph
Ph
12.34
ꢁ111.11
37.03
192.45
160.25
353.55
4.32
3.32
TDA
106.52
a) CC50: 50% cytotoxic concentration; b) IC50: 50% effective concentration; c) SI (selective index)ꢀCC50/IC50
.
synthesized 1,3,4-thiadiazine derivatives, together with those troduced, producing compounds 4f and 5a—e. Of these,
of the reference drug TDA, were evaluated in Vero cells. The compounds 5c and 5d were 4—6 folds more potent than
result was summarized in Table 1. The subclass of com- TDA. This result suggests that the alkyl linker was impor-
pounds 4a—r had a wide variety of substituents on the 2-po- tant for antiviral activity. The introduction of substituents on
sition of 1,3,4-thiadiazine ring. Compounds 4d—g and 4r the phthalimide (compounds 4s, 4t) generally led to loss of
showed potent activity against HSV-1 with IC50 values rang- activity. In addition, compound 7 exhibited similar antiviral
ing from 47.72 to 77.04 mg/ml. On the other hand, the intro- activity to compound 4r.
duction of other substituents in the same position decreased
Compounds that showed good activity against HSV-1 and
the inhibitory potency (compounds 4a—c, 4h, 4i, 4m—o, good separation between anti-HSV activity and toxicity were
4q) or led to an increase in toxicity (compounds 4j—l, 4p). tested for activity against HSV-2 (Table 2). However, com-
Therefore, it could be concluded that suitable electron-donat- pounds 4d and 5c lost suppressant property against HSV-2.
ing group was in favor of antiviral activity. Most importantly, The most potent anti-HSV compound was 4f, which showed
compound 4f had higher selectivity index (SI) than that of marked inhibition of HSV-1 (IC50ꢀ77.04 mg/ml) and HSV-2
TDA. To study the effect of the chain between the phthal- (IC50ꢀ30.00 mg/ml). Meanwhile it had low cytotoxicity
imide and 1,3,4-thiadiazine ring, different linkers were in- (CC50ꢀ1000.00 mg/ml), resulting in high selectivity index

1018
Vol. 59, No. 8
Table 2. Anti-HSV-2 Activity (mg/ml), Predicted ADME and Lipinski Parameters of Compounds 4d, 4f and 5c
HSV-2
Lipinski’s ruled)
Comp.
%ABS
TPSAd)
a)
b)
CC50
IC50
SIc)
n-ON
n-OHNH
log P
MW
4d
4f
5c
557.35
1000.00
192.45
353.55
ꢁ333.33
30.00
ꢁ111.11
73.05
82.8
82.8
82.8
60.7
75.831
75.831
75.831
139.904
6
6
6
9
1
1
1
6
2.562
3.579
5.007
0.843
328.40
364.43
440.53
377.46
33.33
4.84
TDA
a) CC50: 50% cytotoxic concentration; b) IC50: 50% effective concentration; c) SI (selective index)ꢀCC50/IC50; d) www.molinspiration.com/cgi-bin/properties.
(SIHSV-1ꢀ12.98, SIHSV-2ꢀ33.33, respectively). In addition, and then filtered. The filtrate was evaporated to give a residue, which was
subjected to silica gel column chromatography to afford target compounds.
compound 4f was evaluated for its solubility profile in vitro
in differet solutions (2 mg/2 ml), including CH2Cl2, EtOAc,
4a: Yellow oil, yield: 57.7%. 1H-NMR (CDCl3) d: 1.78 (3H, d, Jꢀ7.2 Hz),
2.15 (3H, s), 3.12—3.17 (5H, m), 5.28 (1H, q, Jꢀ7.2 Hz), 7.69—7.83 (4H,
acetone, and MeOH. Compound 4f showed improved solu-
bility (ꢁ1 mg/ml) when compared to TDA (only soluble in
dimethyl sulfoxide). A computational study of compound 4f
was performed by determination of Lipinski’s rule and topo-
logical polar surface area (TPSA).8) The percent absorption
(%ABS) was estimated using equation: %ABSꢀ109ꢂ
0.345ꢃTPSA, according to Zhao et al.9) Our results revealed
that the lipophilicity (LogP), molecular weight (MW), hydro-
gen bond acceptors (n-ON) and donors (n-OHNH) of com-
pound 4f fulfilled Lipinski’s rule. Furthermore, 4f demon-
strated low TPSA and high %ABS values, suggesting its
good oral bioavailability and absorption.
m). HR-ESI-MS (positive) m/z: 317.1077 [MꢄH]ꢄ (Calcd for C15H17N4O2S:
317.1072). IR (cmꢂ1): 3224, 1775, 1710, 1385, 879, 720, 531.
1
4b: Yellow solid, yield: 51.8%, mp: 175.1—176.2 °C. H-NMR (CDCl3)
d: 1.11—1.42 (6H, m), 1.59—1.73 (3H, m), 1.80 (3H, d, Jꢀ7.2 Hz), 2.04—
2.06 (2H, m), 3.15 (2H, dd, Jꢀ16.8 Hz), 5.29 (1H, q, Jꢀ7.2 Hz), 7.71—7.86
(4H, m). HR-ESI-MS (positive) m/z: 371.1523 [MꢄH]ꢄ (Calcd for
C19H23N4O2S: 371.1542). IR (cmꢂ1): 3160, 1778, 1710, 1606, 1384, 1348,
883, 718.
1
4c: Yellow solid, yield: 35.1%, mp: 165.4—166.8 °C. H-NMR (DMSO-
d6) d: 1.67 (3H, d, Jꢀ6.9 Hz), 3.28 (2H, s), 3.43 (2H, dd), 5.12 (1H, q,
Jꢀ6.9 Hz), 7.29—7.37 (4H, m), 7.82—7.86 (4H, m), 10.87 (1H, s). HR-
ESI-MS (positive) m/z: 413.0834 [MꢄH]ꢄ (Calcd for C20H18ClN4O2S:
413.0839). IR (cmꢂ1): 3184, 1775, 1711, 1605, 1382, 882, 848, 716, 535.
4d: Yellow solid, yield: 80.4%, mp: 99.9—102.2 °C. 1H-NMR (CDCl3) d:
1.76 (3H, d, Jꢀ6.9 Hz), 3.13 (2H, s), 4.04 (2H, m), 5.09—5.29 (3H, m),
5.85—5.94 (1H, m), 7.67—7.82 (4H, m). HR-ESI-MS (positive) m/z:
329.1067 [MꢄH]ꢄ (Calcd for C16H17N4O2S: 329.1072). IR (cmꢂ1): 3301,
1774, 1702, 1529, 1382, 1332, 1263, 1041, 879, 720, 529.
In summary, we synthesized a series of novel 1,3,4-thiadi-
azine derivatives via chemical optimization on TDA. Their
anti-HSV activities in vitro were also tested. It was worth
noting several derivatives exhibited more highly potent anti-
4e: Yellow oil, yield: 63.4%. 1H-NMR (DMSO-d6) d: 1.67 (3H, d,
HSV activity and much higher SI values than those of TDA. Jꢀ6.9 Hz), 3.27 (2H, s), 4.46 (2H, s), 5.12 (1H, q, Jꢀ6.9 Hz), 6.79—7.33
(5H, m), 7.82—7.89 (4H, m), 10.75 (1H, s). HR-ESI-MS (positive) m/z:
This founding refined our present understanding of the TDA
pharmacophore and established certain structure–activity
379.1229 [MꢄH]ꢄ (Calcd for C20H19N4O2S: 379.1229). IR (cmꢂ1): 3133,
1774, 1713, 1562, 1382, 881, 715.
relationships. To our knowledge, this is the first report on
the anti-HSV activity of 1,3,4-thiadiazine derivatives. A com-
putational study revealed the potential of compound 4f as a
new antiviral agent. Further studies are required to investigate
the antiviral mechanism of this compound.
4f: White solid, yield: 48.1%, mp: 178.9—180.7 °C. 1H-NMR (DMSO-d6)
d: 1.66 (3H, d, Jꢀ6.9 Hz), 3.43 (2H, s), 5.14 (1H, q, Jꢀ6.9 Hz), 6.96—7.01
(3H, m), 7.22—7.27 (2H, m), 7.83—7.90 (4H, m), 10.98 (1H, s); ESI-MS:
[MꢄH]ꢄ 365.1089, [MꢄNa]ꢄ 387.0906. HR-ESI-MS (positive) m/z:
365.1078 [MꢄH]ꢄ (Calcd for C19H17N4O2S: 365.1072). IR (cmꢂ1): 3083,
1777, 1708, 1385, 1125, 883, 721.
4g: Yellow solid, yield: 33.0%, mp: 171.7—173.1 °C. 1H-NMR
(CD3COCD3) d: 1.75 (3H, d, Jꢀ7.2 Hz), 3.48 (2H, dd, Jꢀ21 Hz), 3.74 (2H,
s), 5.23 (1H, q, Jꢀ7.2 Hz), 6.81—6.89 (4H, m), 7.83—7.86 (4H, m). HR-
ESI-MS (positive) m/z: 395.1172 [MꢄH]ꢄ (Calcd for C20H19N4O3S:
395.1178). IR (cmꢂ1): 3169, 1777, 1703, 1592, 1503, 1239, 1153, 1040,
Experimental
Biology. Antiviral Assay The antiviral activity of compounds 4a—t,
5a—e and 7 was determined using a cytopathic effect (CPE) reduction assay
against HSV-1 (VR733) and HSV-2 (SAV) in Vero cell cultures. Cells grown
to confluency in 96-well plates were infected with 100 CCID50 (the 50% cell 879, 721, 531.
culture infective dose) of virus. After an adsorption period of 2 h at 37 °C,
virus was removed and serial dilutions of the compounds were added. Virus-
infected wells without compounds were used as cytopathogenicity controls.
Viral cytopathogenicity was completed 1—2 d after viral infection. Antiviral
activity is expressed as the IC50 (50% inhibitory concentration).
Cytotoxic Assay Cytotoxicity of the compounds for the host cells was
evaluated in parallel with their antiviral effects, based on the inhibition of
cell growth.10)
4h: White solid, yield: 52.8%, mp: 179.6—180.9 °C. 1H-NMR
(CD3COCD3) d: 1.75 (3H, d, Jꢀ6.9 Hz), 2.25 (3H, s), 3.48 (2H, dd, Jꢀ
20.7 Hz), 5.23 (1H, q, Jꢀ6.9 Hz), 6.88 (2H, m), 7.05 (2H, m), 7.83—7.86
(4H, m). HR-ESI-MS (positive) m/z: 379.1223 [MꢄH]ꢄ (Calcd for
C20H19N4O2S: 379.1229). IR (cmꢂ1): 3179, 1776, 1703, 1592, 1384, 1162,
1044, 878, 722.
4i: White solid, yield: 58.6%, mp: 178.1—178.8 °C. 1H-NMR
(CD3COCD3) d: 1.77 (3H, d, Jꢀ7.2 Hz), 3.59 (2H, s), 5.27 (1H, q,
Jꢀ7.2 Hz), 7.09 (2H, s), 7.87 (4H, s), 8.17 (2H, m). HR-ESI-MS (positive)
m/z: 410.0918 [MꢄH]ꢄ (Calcd for C19H16N5O4S: 410.0923). IR (cmꢂ1):
3145, 1777, 1703, 1320, 1107, 839, 718.
Chemistry. General 1H-NMR spectra were recorded on a Varian MER-
CURY-300 (300 MHz) system. Chemical shift values (d) are given in ppm
relative to TMS as internal standard. HR-MS spectra were obtained on a
LC/MSD time-of-flight (TOF) spectrometer, using electrospray ionization
(ESI) as ionization mode. IR spectra were measured on a Nicolet 5700 spec-
trometer (microscope transmission). Flash column chromatography was per-
formed with 200—300 mesh silica gel.
4j: Yellow solid, yield: 62.8%, mp: 129.1—131.5 °C. 1H-NMR
(CD3COCD3) d: 1.74 (3H, d, Jꢀ7.2 Hz), 3.56 (2H, dd, Jꢀ18.6 Hz), 5.27
(1H, q, Jꢀ7.2 Hz), 6.95—6.7.11 (4H, m), 7.83—7.86 (4H, m). HR-ESI-MS
(positive) m/z: 383.0973 [MꢄH]ꢄ (Calcd for C19H16FN4O2S: 383.0978). IR
(cmꢂ1): 3248, 1777, 1710, 1607, 1385, 1218, 762, 719.
General Procedure for the Preparation of Compounds 4a—n, 4s, t
and 5a—e Compounds 3a—h (10 mmol), NaHCO3 (168 mg, 20 mmol)
1
4k: White solid, yield: 44.5%, mp: 155.2—156.8 °C. H-NMR (DMSO-
and 4-substituted-3-thiosemicarbazides (1.2 eq) were suspended in EtOH d6) d: 1.65 (3H, d, Jꢀ6.0 Hz), 3.45 (2H, s), 5.13 (1H, q, Jꢀ6.0 Hz), 6.79
(20 ml). The suspension was refluxed for 1 h and poured into water (20 ml).
(2H, s), 7.07—7.09 (2H, m), 7.83—7.90 (4H, m), 10.98 (1H, s). HR-ESI-
The mixture were extracted with EtOAc (30 mlꢃ3). The organic extracts MS (positive) m/z: 383.0961 [MꢄH]ꢄ (Calcd for C19H16FN4O2S: 383.0978).
were successively washed with water and brine, dried over absolute MgSO4, IR (cmꢂ1): 3248, 1779, 1709, 1612, 1503, 1384, 1199, 880, 717.

August 2011
1019
4l: White solid, yield: 65.3%, mp: 163.1—164.3 °C. 1H-NMR (DMSO-d6)
d: 1.66 (3H, d, Jꢀ6.9 Hz), 3.47 (2H, s), 5.14 (1H, q, Jꢀ6.9 Hz), 6.79 (2H,
s), 7.27—7.30 (2H, m), 7.83—7.90 (4H, m), 11.05 (1H, s). HR-ESI-MS
(positive) m/z: 399.0678 [MꢂH]ꢂ (Calcd for C19H16ClN4O2S: 399.0683). IR
(cmꢃ1): 3089, 1775, 1707, 1609, 1386, 879, 720.
d6) d: 1.68 (3H, d, Jꢀ7.2 Hz), 1.91 (3H, s), 3.15 (2H, dd, Jꢀ23.7 Hz), 5.19
(1H, q, Jꢀ7.2 Hz), 7.35—7.49 (5H, m), 7.85 (4H, s). HR-ESI-MS (positive)
m/z: 407.1165 [MꢂH]ꢂ (Calcd for C21H19N4O3S: 407.1178). IR (cmꢃ1):
1772, 1709, 1672, 1388, 1275, 730, 697.
General Procedure for the Preparation of Compounds 4q—r A solu-
tion of compound 4f (364 mg, 10 mmol), K2CO3 (276 mg, 20 mmol),
iodomethane or benzyl bromide (1.2 eq) in N,N-dimethylformamide (DMF)
(10 ml) were stirred at room temperature for 12 h. The reaction mixture was
poured into water (20 ml) and extracted with EtOAc (30 mlꢄ3). The organic
extracts were successively washed with water and brine, dried over absolute
MgSO4, and then filtered. The filtrate was evaporated to give a residue,
which was subjected to silica gel column chromatography to afford target
compounds.
4m: Yellow solid, yield: 49.3%, mp: 180.5—181.5 °C. 1H-NMR (DMSO-
d6) d: 1.65 (3H, d, Jꢀ7.2 Hz), 3.50 (2H, s), 5.13 (1H, q, Jꢀ7.2 Hz), 7.20
(1H, s), 7.26—7.30 (1H, m), 7.83—7.90 (4H, m), 8.07 (1H, s), 8.20 (1H, s),
11.19 (1H, s). HR-ESI-MS (positive) m/z: 366.0998 [MꢂH]ꢂ (Calcd for
C18H16N5O2S: 366.1025). IR (cmꢃ1): 3086, 1776, 1709, 1591, 1569, 1389,
882, 715.
1
4n: Yellow solid, yield: 41.1%, mp: 170.3—171.9 °C. H-NMR (DMSO-
d6) d: 1.67 (3H, d, Jꢀ6.9 Hz), 3.28 (2H, s), 5.16 (1H, q, Jꢀ6.9 Hz), 6.94—
6.98 (1H, m), 7.03—7.06 (1H, m), 7.63—7.69 (1H, m), 7.84—7.91 (4H, m),
8.29—8.30 (1H, m), 11.27 (1H, s). HR-ESI-MS (positive) m/z: 366.0998
[MꢂH]ꢂ (Calcd for C18H16N5O2S: 366.1025). IR (cmꢃ1): 3059, 1775, 1715,
1570, 1546, 1466, 1382, 1155, 795, 720.
4q: White oil, yield: 60.2%. 1H-NMR (CDCl3) d: 1.74 (3H, d, Jꢀ7.2 Hz),
3.29 (2H, s), 3.55 (3H, s), 5.21 (1H, q, Jꢀ7.2 Hz), 6.83—6.85 (2H, m),
7.03—7.08 (1H, m), 7.25—7.30 (2H, m), 7.73—7.77 (2H, m), 7.85—7.88
(2H, m). HR-ESI-MS (positive) m/z: 379.1230 [MꢂH]ꢂ (Calcd for
C20H19N4O2S: 379.1229). IR (cmꢃ1): 1777, 1749, 1710, 1581, 1385, 1197,
723.
4s: White solid, yield: 25.0%, mp: 189.2—190.8 °C. 1H-NMR (DMSO-
d6) d: 1.65 (3H, d, Jꢀ6.3 Hz), 3.42 (2H, s), 5.12 (1H, q, Jꢀ6.3 Hz), 6.79
(1H, s), 6.96—7.01 (1H, m), 7.22—7.27 (3H, m), 7.81 (1H, m), 8.04—8.09
(2H, m), 10.97 (1H, s). HR-ESI-MS (positive) m/z: 443.0154 [MꢂH]ꢂ
(Calcd for C19H16BrN4O2S: 443.0177). IR (cmꢃ1): 3083, 1773, 1708, 1605,
1377, 775, 743.
4r: White solid, yield: 82.5%, mp: 136.1—137.7 °C. 1H-NMR (CDCl3) d:
1.71 (3H, d, Jꢀ7.2 Hz), 3.25 (2H, s), 5.16 (1H, q, Jꢀ7.2 Hz), 5.22 (2H, s),
6.77—6.79 (2H, m), 7.01—7.06 (1H, m), 7.21—7.28 (4H, m), 7.33—7.37
(3H, m), 7.70—7.73 (2H, m), 7.81—7.84 (2H, m). HR-ESI-MS (positive)
m/z: 455.1549 [MꢂH]ꢂ (Calcd for C26H23N4O2S: 455.1542). IR (cmꢃ1):
1778, 1711, 1780, 1382, 736, 722.
Preparation of Compounds 7 A solution of compound 4f (364 mg,
10 mmol) and NaBH4 (76 mg, 20 ml) in tetrahydrofuran (THF) and MeOH
(10 ml, 1 : 1) were stirred at 0 °C for 2 h. The reaction mixture was poured
into water (20 ml) and filtered. The solid was dried to give compound 6,
which was added to MeOH (10 ml) containing p-toluenesulfonic acid
(10 eq). The solution were refluxed for 8 h, poured into water (20 ml) and ex-
tracted with EtOAc (30 mlꢄ3). The organic extracts were successively
washed with water and brine, dried over absolute MgSO4, and then filtered.
The filtrate was evaporated to give a residue, which was subjected to silica
gel column chromatography to afford compound 7.
4t: White solid, yield: 40.2%, mp: 94.7—96.1 °C. 1H-NMR (CDCl3) d:
1.76 (3H, d, Jꢀ6.9 Hz), 3.33 (2H, s), 5.24 (1H, q, Jꢀ6.9 Hz), 6.91—6.93
(1H, m), 6.99—7.08 (1H, m), 7.22—7.27 (2H, m), 7.89—7.94 (2H, m),
8.04—8.12 (2H, m). HR-ESI-MS (positive) m/z: 410.0910 [MꢂH]ꢂ (Calcd
for C19H16N5O4S: 410.0923). IR (cmꢃ1): 3086, 1783, 1719, 1583, 1543,
1382, 1358, 723, 699.
5a: White solid, yield: 65.7%, mp: 171.4—173.3 °C. 1H-NMR (DMSO-
d6) d: 3.46 (2H, s), 4.59 (2H, s), 6.79 (1H, s), 6.94—6.98 (2H, m), 7.21—
7.26 (2H, m), 7.85—7.94 (4H, m), 10.85 (1H, s). HR-ESI-MS (positive)
m/z: 351.0896 [MꢂH]ꢂ (Calcd for C18H15N4O2S: 351.0916). IR (cmꢃ1):
3092, 1777, 1734, 1608, 1585, 1420, 1391, 947, 700.
1
5b: White solid, yield: 41.9%, mp: 201.1—202.0 °C. H-NMR (DMSO-
7: White oil, yield: 53.9%. 1H-NMR (DMSO-d6) d: 1.67 (3H, d,
Jꢀ7.2 Hz), 3.26 (2H, s), 3.48 (3H, s), 5.11 (1H, q, Jꢀ7.2 Hz), 6.95—7.09
(3H, m), 7.24—7.30 (2H, m), 7.51—7.64 (3H,m), 7.82—7.84 (2H, m),
10.95 (1H, s). HR-ESI-MS (positive) m/z: 381.1387 [MꢂH]ꢂ (Calcd for
C20H21N4O2S: 381.1385). IR (cmꢃ1): 3031, 1778, 1710, 1580, 1383, 1070,
736, 722.
d6) d: 2.72 (2H, s), 3.41 (2H, s), 3.82 (2H, s), 6.74 (1H, s), 6.95—6.98 (2H,
m), 7.22—7.27 (2H, m), 7.82—7.89 (4H, m), 10.77 (1H, s). HR-ESI-MS
(positive) m/z: 365.1053 [MꢂH]ꢂ (Calcd for C19H17N4O2S: 365.1072). IR
(cmꢃ1): 3082, 1769, 1695, 1612, 1594, 993, 776, 716, 695.
5c: White solid, yield: 40.1%, mp: 150.6—151.8 °C. 1H-NMR (DMSO-
d6) d: 2.90—2.95 (2H, m), 2.49—2.54 (4H, m), 3.65 (2H, s), 6.74 (1H, s),
6.93—6.98 (2H, m), 7.22—7.31 (2H, m), 7.82—7.94 (4H, m), 10.75 (1H,
s). HR-ESI-MS (positive) m/z: 379.1212 [MꢂH]ꢂ (Calcd for C20H19N4O2S:
379.1229). IR (cmꢃ1): 3172, 1769, 1710, 1603, 1398, 1024, 773, 720, 701.
Acknowledgement Financial support of Beijing Municipal Commission
of Commerce is acknowledged. Technical assistance of professor Wang Lin
is greatly appreciated.
1
5d: Yellow solid, yield: 68.2%, mp: 136.2—137.0 °C. H-NMR (DMSO-
d6) d: 3.50—3.54 (4H, m), 5.33 (1H, m), 6.79 (1H, s), 6.95—7.32 (9H, m),
7.80 (4H, s), 10.05 (1H, s). HR-ESI-MS (positive) m/z: 441.1373 [MꢂH]ꢂ
(Calcd for C25H21N4O2S: 441.1385). IR (cmꢃ1): 3077, 1771, 1761, 1574,
1383, 769, 715.
References
1) Gudmundsson K. S., Johns B. A., Allen S. H., Bioorg. Med. Chem.
Lett., 18, 1157—1161 (2008).
5e: White solid, yield: 33.3%, mp: 161.1—162.3 °C. 1H-NMR (DMSO-
d6) d: 0.87—0.91 (6H, m), 1.48—1.52 (1H, m), 1.86—1.96 (1H, m), 2.24—
2.34 (1H, m), 3.47 (2H, s), 5.07—5.12 (1H, m), 6.96—7.01 (3H, m), 7.22—
7.27 (2H, m), 7.85—7.92 (4H, m), 10.66 (1H, s). HR-ESI-MS (positive)
m/z: 407.1532 [MꢂH]ꢂ (Calcd for C22H23N4O2S: 407.1542). IR (cmꢃ1):
3060, 1776, 1712, 1586, 1383, 719.
2) Gudmundsson K. S., Johns B. A., Bioorg. Med. Chem. Lett., 17,
2735—2739 (2007).
3) Tomé J. P. C., Neves M. G. P. M. S., Tomé A. C., Cavaleiro J. A. S.,
Mendonça A. F., Pegado I. N., Duarte R., Valdeira M. L., Bioorg. Med.
Chem., 13, 3878—3888 (2005).
4) Yin M. B., Cheng M., Ye Q. R., Yang H. M., Gao Y. J., Wang L., Liu
Y. Y., Acta Academiae Medicinae Sinicae, 9, 79—83 (1987).
5) Yang Y. J., Zhao J. H., Pan X. D., Zhang P. C., Chem. Pharm. Bull., 58,
208—211 (2010).
6) Medjahed W., Tabet Zatla A., Kajima Mulengi J., Baba Ahmed F. Z.,
Merzouk H., Tetrahedron Lett., 45, 1211—1213 (2004).
7) Wang G. X., Wang L., Zhao Z. Z., Tao P. Z., Wang S. Q., Acta Phar-
macol. Sin., 31, 831—836 (1996).
8) Nazari Formagio A. S., Santos P. R., Zanoli K., Ueda-Nakamura T.,
Düsman Tonin L. T., Nakamura C. V., Sarragiotto M. H., Eur. J. Med.
Chem., 44, 4695—4701 (2009).
9) Zhao Y. H., Abraham M. H., Le J., Hersey A., Luscombe C. N., Beck
G., Sherborne B., Cooper I., Pharm. Res., 19, 1446—1457 (2002).
10) Guo H. F., Li Y. H., Tao P. Z., Yi H., Wang S. Q., He W. Y., Jiang J. D.,
Li Z. R., Acta Pharmaceutica Sinica, 45, 268—273 (2010).
General Procedure for the Preparation of Compounds 4o—p A so-
lution of compound 4f (364 mg, 10 mmol), Et3N (202 mg, 20 mmol), acetic
anhydride or Benzoyl chloride (1.2 eq) in CH2Cl2 (10 ml) were stirred at
room temperature for 12 h. The reaction mixture was poured into water
(20 ml) and extracted with CH2Cl2 (30 mlꢄ3). The organic extracts were
successively washed with water and brine, dried over absolute MgSO4, and
then filtered. The filtrate was evaporated to give a residue, which was sub-
jected to silica gel column chromatography to afford target compounds.
4o: White oil, yield: 58.3%. 1H-NMR (CDCl3) d: 1.79 (3H, d, Jꢀ6.9 Hz),
2.88 (1H, d, Jꢀ14.1 Hz), 2.30 (1H, d, Jꢀ14.1 Hz), 5.31 (1H, q, Jꢀ6.9 Hz),
7.01—7.49 (10H, m), 7.71—7.87 (4H, m). HR-ESI-MS (positive) m/z:
469.1352 [MꢂH]ꢂ (Calcd for C26H21N4O3S: 469.1334). IR (cmꢃ1): 1776,
1710, 1384, 1334, 719, 696.
1
4p: White solid, yield: 66.3%, mp: 160.0—161.4 °C. H-NMR (DMSO-