Design and synthesis of cinanserin analogs as severe acute respiratory syndrome coronavirus 3CL protease inhibitors

Article abstract of DOI:10.1248/cpb.56.1400

The severe acute respiratory syndrome (SARS) coronavirus 3CL protease is an attractive target for the development of anti-SARS drugs. In this paper, cinanserin (1) analogs were synthesized and tested for the inhibitory activities against SARS-coronavirus (CoV) 3CL protease by fluorescence resonance energy transfer (FRET) assay. Four analogs show significant activities, especially compound 26 with an IC₅₀ of 1.06 μM.

Full text of DOI:10.1248/cpb.56.1400

1400
Chem. Pharm. Bull. 56(10) 1400—1405 (2008)
Vol. 56, No. 10
Design and Synthesis of Cinanserin Analogs as Severe Acute Respiratory
Syndrome Coronavirus 3CL Protease Inhibitors
a
a
a
b
a
,a
*
Qingang YANG, Lili CHEN, Xuchang HE, Zhenting GAO, Xu SHEN, and Donglu BAI
a Shanghai Institute of Materia Medica, Chinese Academy of Sciences; 555 Zuchongzhi Road, Shanghai 201203, China:
and b School of Pharmacy, East China University of Science and Technology; Shanghai 200237, China.
Received February 26, 2008; accepted July 17, 2008; published online July 28, 2008
The severe acute respiratory syndrome (SARS) coronavirus 3CL protease is an attractive target for the de-
velopment of anti-SARS drugs. In this paper, cinanserin (1) analogs were synthesized and tested for the in-
hibitory activities against SARS-coronavirus (CoV) 3CL protease by fluorescence resonance energy transfer
(FRET) assay. Four analogs show significant activities, especially compound 26 with an IC50 of 1.06 mM.
Key words SARS coronavirus 3CL protease; cinanserin analog; inhibitor; fluorescence resonance energy transfer-based assay
Severe acute respiratory syndrome (SARS) is a life-threat- larly, compounds 23 and 24 were obtained from 2-aminophe-
ening form of atypical pneumonia caused by infection with a nol (43) and 2-amino-4-nitrophenol (44) via the same ap-
novel human coronavirus (SARS-CoV). It rapidly spreaded proach respectively (Chart 2).
from southern China to several other countries during late
Sulfoxide 25 was prepared by oxidation of cinanserin (1)
2002 and early 2003.1) By July 31, 2003, a total of 8098 with sodium periodate in acetonitrile. The synthesis of com-
SARS cases and 774 SARS-related deaths were reported pounds 26 and 27 also started from 2-aminothiophenol (28),
around the world.2,3) Although regional preventive measures which was reacted with an excess of cinnamoyl chloride (47,
are being implemented, vaccine and therapeutic drugs are RꢀH) or 2-cyanocinnamoyl chloride (48, RꢀCN) in the
being sought, no effective small molecule antiviral agent has presence of triethylamine at reflux in dichloromethane to
been reported for treating SARS so far.
give the desired products 29 and 30 respectively (Chart 3).
SARS-CoV is a positive-strand RNA virus that consists Among the target compounds, 2, 4, 5, 11, 21, 23 and 24 are
of about 29700 nucleotides. It encodes two overlapping known, but their 1H-NMR data have not been reported yet.
polyproteins, ppla (486 kDa) and pplab (790 kDa).4—7) The
Biological Results and SAR Discussion The bioactivi-
functional polypeptides are released from each polyprotein ties of compounds 2—27 were measured by a fluorescence
through extensive proteolytic processing primarily by 3CL resonance energy transfer (FRET)-based assay using 5-(2-
protease.8) Because of this functional importance of SARS- aminoethylamino)naphthelenesulfonic acid (Edans) and 4-(4-
CoV 3CL protease in the viral life cycle, it has been recog- dimethylaminophenylazo)benzoic acid (Dabcyl) as the en-
nized as a key target for drugs designing against SARS.9—11)
ergy transfer pair. The peptide substrate is Dabcyl-KN-
In our preceding paper, we have reported that cinanserin STLQSGLRKE-Edans labeled with Edans and Dabcyl. The
(1), a well-characterized serotonin antagonist, is a good po- inhibition of SARS-CoV 3CL protease slowly increased in
tential lead compound for designing more active inhibitors of the concentration range from 0 to 500 mM of the correspon-
3CL protease.12) Herein we report the design and synthesis of ding compounds. The IC50 value of the compounds in in-
two series of cinanserin derivatives as novel inhibitors of hibiting the catalytic activity of SARS-CoV 3CL protease
SARS-CoV 3CL protease.
was calculated by fitting the dose–response curve using a lo-
According to the 3D model of the cinanserin-3CL protease gistic derivative equation.12) The results are summarized in
complex,12) three series of cinanserin analogs have been de- Table 1.
signed and synthesized respectively (Table 1). In order to
Of the synthetic derivatives tested, compounds 7, 10, 13,
modify the cinnamide moiety of cinanserin, compounds 2— 26 and 27 displayed remarkable inhibitory activity of SARS-
9 were synthesized in which cinnamoyl group is replaced CoV 3CL protease, indicating that the cinnamoyl group is
with other phenyl-containing groups. Compounds 10—22 crucial for good inhibition of SARS-CoV 3CL protease.
and 26, 27 were designed and prepared to diversify the sub- Compound 7 is about 2-fold more potent than cinanserin,
stitute groups and chains on sulfur atom of cinanserin. Com- suggesting that introduction of a cyano substituent on a-po-
pounds 23—25 were prepared to vary the thioether group of sition of cinnamoyl group increased the inhibitory activity.
cinanserin into ether and sulfoxide respectively.
Replacement of the dimethylamino group of cinanserin with
Chemical Synthesis Compounds 2—22 were synthe- electron-withdrawing group such as an ester group (13) or
sized via a three-step route (Chart 1).13,14) The starting mate- elimination of the dimethylamino group (allylthioether 10)
rial 2-aminothiophenol (28) was first treated with excessive enhanced remarkably the inhibitory activity, and the chain
sodium isopropoxide at room temperature to form sodium length of the thioether is not critical of the inhibitory activity
salt, which was then reacted with a variety of alkyl halides or (compound 11 vs. 12; 15 vs. 16). When the phenylthioether
aminoalkyl halides, yielding intermediates 29—42. Most of moiety in cinanserin was changed to phenylether group (23)
the intermediates are known except 35, 36, 37 and 42. Acyla- or oxidized to sulfoxide (25), no inhibitory activity was ob-
tion of the intermediates with the corresponding acyl chlo- served. Unexpectedly, replacement of the 3-dimethylamino-
ride produced the target compounds 2—22 (Chart 1). Simi- propyl group in cinanserin with an additional cinnamoyl
∗ To whom correspondence should be addressed. e-mail: dlbai@mail.shcnc.ac.cn
© 2008 Pharmaceutical Society of Japan

October 2008
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Table 1. The Chemical Structures and Inhibitory Activities of Cinanserin 1 and Analogs 2—27 against SARS 3CL Proteasea)
Compd.
Structure
IC50 (mM)
Compd.
Structure
IC50 (mM)
ꢁ500
ꢁ500
ꢁ500
ꢁ500
293
1
323
15
Cinanserin
2
3
4
5
6
7
ꢁ500
ꢁ500
ꢁ500
ꢁ500
ꢁ500
125
16
17
18
19
20
349
21
ꢁ500
8
9
ꢁ500
ꢁ500
22
23
ꢁ500
ꢁ500
10
11
12
19.7
206
24
25
26
ꢁ500
ꢁ500
ꢁ500
1.06
13
13.5
27
43.7
14
ꢁ500
a) The flurogenic peptide substrate is Dabcyl-KNSTLQSGLRKE-Edans instead of Edans-VNSTLQSGLRK(Dabcyl)M as used in ref. 12.
group, giving compound 26 which showed very potent inhi- scripps.edu/resources/adt) were used to add polar hydrogen
bition against 3CL protease, and is 300-fold more potent than and assign partial charges to both protein and ligand.
cinanserin itself. These observations are in good coincidence AutoDock 3.015) was employed for the docking of compound
with the molecular docking study of the complex of 3Cl pro- 26 to SARS-3CL protease. All the molecular modeling and
tease with the ligand.
docking simulations were performed on a Silicon Graphics
Docking Study The 3D structure of compound 26 was Origin 3800 (with 128 CPUs).
constructed by the Corina online service (http://www.mol-
To address the SARS-CoV 3CL protease inhibitory activ-
net.com/online_demos/corina_demo.html). The 3D model of ity of compound 26, we applied molecular docking to iden-
SARS-CoV 3CL protease was retrieved from the Brookhaven tify the possible binding mode between the compound and
Protein Data Bank (PDB) (http://www.rcsb.org/pdb/) (PDB the enzyme. The top pose, ranked by the “estimated free en-
ID: 1UJ1, Chain A).12) AutoDock Tools (http://autodock. ergy of binding”, was chosen as the predicted binding mode.

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Vol. 56, No. 10
For the top pose, as shown in Fig. 1, compound 26 locates PLOT.16) In the light of this binding mode, compound 26 oc-
deep inside the S1 pocket12) with appropriate steric comple- cupies the substrate binding subsite, indicating that it is a
ment. Fourty hydrophobic interaction atom pairs between the competitive ligand for the enzyme’s substrate, and the pre-
compound and the enzyme were detected by using the LIG- dicted dissociation constant KD is 0.35 M. Compared with the
binding mode of cinanserin and SARS-CoV 3CL protease,12)
compound 26 binds tighter with the protease than cinanserin.
This might lead to the stronger inhibitory activity against the
protease.
Conclusion
Three series of cinanserin analogs derived from the modi-
fication of cinnamenyl, phenylthioether group and sulfur-
containing chain of cinanserin have been designed and syn-
thesized as potential inhibitors of SARS-CoV 3CL protease.
The inhibitory activities of these compounds were assessed
by FRET assay. Some analogs showed improved inhibitory
activities against SARS-CoV 3CL protease compared with
cinanserin itself. The IC50 values of compounds 10, 13, 26
and 27 are lower than 100 mM. Among them compound 26 is
the most potent one . It is much more potent than cinanserin
by two orders of magnitude in the inhibition of SARS 3CL
protease.
Chart 1 Synthesis of Compounds 1—22
Experimental
General All starting materials were commercially available and used
without further purification. All water-sensitive reactions were carried out in
oven-dried glassware with a stirring bar under a nitrogen atmosphere.
Toluene was dried over sodium, chloroform and dichloromethane were dried
over CaH2. Melting points were measured in capillary tube on a Buchi 510
melting point apparatus without correction. IR spectra were recorded on a
Nicolet Magna IR750 spectrometer with KBr disks or film. NMR spectra
were recorded on Brucker AMX-400 (400 MHz). Chemical shifts were re-
ported in parts per million (ppm, d units) downfield from chloroform where
solvent peak was used as internal standard. Proton coupling patterns were
described as singlet (s), doublet (d), triplet (t), quartet (q), multiplet (m), and
broad (br). Low- and high-resolution mass spectra (LR-MS and HR-MS)
were given with electric ionization (EI) produced by Varian MAT-711 and
Finnigan MAT-95 instrument.
Chart 2 Synthesis of Compounds 23 and 24
2-(3-Methoxypropylthio)benzenamine (35) To a solution of sodium
isopropoxide prepared from sodium (0.35 g, 15.2 mmol) in isopropanol
(20 ml) was added 28 (1.7 ml, 15 mmol), and the mixture was stirred at room
temperature for 30 min. 1-Chloro-3-methoxypropane (1.63 g, 15 mmol) was
then added to. The reaction mixture was stirred at reflux for 4 h, and con-
Chart 3 Synthesis of Compounds 26 and 27
Fig. 1. Modeled Interaction of Compound 26 with SARS-CoV 3CL Protease
(A) SARS-CoV 3CL protease is shown as a surface model, in grey; compound 26 is shown as deep grey stick and surface; (B) amino acid residues involved in the compound
26 binding: H-bond is represented as dashed line, and hydrophobic contacts with the ligand as spiked residue. (A) was generated with PyMOL17) and (B) was generated with
LIGPLOT.

October 2008
1403
densed in vaccum. The residue was treated with water and extracted with
N-[2-(3-Dimethylaminopropylthio)phenyl]-2-cyanocinnamide (7) In
ether twice. The combined organic layer was washed with water and dried the same manner as described for 2, it was prepared from 29 and 2-
over anhydrous MgSO4. After removal of the solvent, the residue was puri- cyanocinnamoyl chloride in a yield of 64% as an orange solid recrystallized
fied by flash column chromatography on silica gel eluting with petroether from ethyl acetate–n-hexane, mp 85—86 °C. IR (KBr) cmꢂ1: 3315, 2947,
1
(80) : chloroform (13) : ethyl acetate (7) to afford 35 (0.63 g, 21%) as a
2785, 2206, 1686, 1593, 1525, 1442, 1306, 1188, 1038; H-NMR (CDCl3)
brownish oil. 1H-NMR (CDCl3) d: 1.78—1.85 (2H, m), 2.82 (2H, t, d: 1.73—1.80 (2H, m), 2.18 (6H, s), 2.36 (2H, t, Jꢀ7.0Hz), 2.84 (2H, t,
Jꢀ7.1 Hz), 3.31 (3H, s), 3.45 (2H, t, Jꢀ6.4 Hz), 4.33 (2H, s, br), 6.66—6.73 Jꢀ7.2 Hz), 7.11 (1H, td, Jꢀ7.6, 1.3 Hz), 7.35—7.40 (1H, m), 7.49—7.60
(2H, m), 7.08—7.12 (1H, m), 7.37 (1H, dd, Jꢀ7.7, 1.5 Hz).
(4H, m), 7.98—8.00 (2H, m), 8.41(1H, s), 8.49 (1H, dd, Jꢀ8.2, 1.2 Hz),
2-(4-Methoxybutylthio)benzenamine (36) In the same manner as de- 9.70 (1H, s, br). MS m/z: 365 (Mꢃ), 261, 156, 128, 58 (100%); Anal. Calcd
scribed for 35, it was prepared from 28 and 1-chloro-4-methoxybutane in a for C21H23N3OS: C, 69.01; H, 6.34; N, 11.50. Found: C, 69.12; H, 6.24; N,
1
yield of 52% as a brownish oil. H-NMR (CDCl3) d: 1.62—1.70 (4H, m), 11.43.
2.76 (2H, t, Jꢀ7.2 Hz), 3.31 (3H, s), 3.36 (2H, t, Jꢀ6.0 Hz), 4.34 (2H, s, br),
6.66—6.73 (2H, m), 7.08—7.12 (1H, m), 7.36 (1H, dd, Jꢀ7.7, 1.5 Hz).
N-[2-(3-Dimethylaminopropylthio)phenyl]-2-phenylcinnamide (8) In
the same manner as described for 2, it was prepared from 29 and 2-phenyl-
2-[2-(2-N-Methylpyrrolidyl)ethylthio]benzenamine (37) In the same cinnamoyl chloride in a yield of 45% as a brown oil. IR (Film) cmꢂ1: 3332,
1
manner as described for 35, it was prepared from 28 and 2-(2-chloroethyl)- 2931, 2785, 1682, 1624, 1558, 1522, 1437, 1306, 1200; H-NMR (CDCl3)
1-methyl-pyrrolidine hydrochloride in a yield of 63% as a brownish oil. 1H- d: 1.42—1.50 (2H, m), 2.18 (6H, s), 2.24 (2H, t, Jꢀ7.0 Hz), 2.36 (2H, t,
NMR (CDCl3) d: 1.35—1.55 (2H, m), 1.63—1.75 (2H, m), 1.86—1.95 (2H, Jꢀ7.3 Hz), 7.00 (1H, td, Jꢀ7.4, 1.4 Hz), 7.05—7.55 (12H, m), 7.99 (1H, s),
m), 2.08—2.16 (2H, m), 2.25 (3H, s), 2.63—2.70 (1H, m), 2.78—2.85 (1H, 8.63 (1H, dd, Jꢀ8.2, 1.4 Hz), 8.77 (1H, s, br). MS m/z: 416 (Mꢃ), 224, 179,
m), 3.00—3.05 (1H, m), 4.34 (2H, s, br), 6.65—6.72 (2H, m), 7.08—7.12 118, 58 (100%); HR-MS (EI) m/z: Calcd for C26H28N2OS (Mꢃ) 416.1922.
(1H, m), 7.38—7.56 (1H, m).
Found 416.1923.
2-(2-Phenoxyethylthio)benzenamine (42) In the same manner as de-
N-[2-(3-Dimethylaminopropylthio)phenyl]-4-phenylbenzamide (9) In
scribed for 35, it was prepared from 28 and 2-phenoxyethyl bromide in a the same manner as described for 2, it was prepared from 29 and 4-phenyl-
1
yield of 94% as a brownish oil. H-NMR (CDCl3) d: 3.10 (2H, td, Jꢀ6.5, benzoyl chloride in a yield of 22% as a yellow oil. IR (Film) cmꢂ1: 3342,
0.7 Hz), 4.07 (2H, td, Jꢀ6.5, 0.7 Hz), 4.41 (2H, s, br), 6.67—6.74 (2H, m), 3057, 2941, 2767, 1678, 1608, 1579, 1508, 1433, 1306, 1250, 1101, 1038,
1
6.83—6.87 (2H, m), 6.93—6.97 (1H, m), 7.12—7.17 (1H, m), 7.24—7.30 1007; H-NMR (CDCl3) d: 1.70—1.77 (2H, m), 2.14 (6H, s), 2.33 (2H, t,
(2H, m), 7.42—7.45 (1H, m).
Jꢀ7.0 Hz), 2.84 (2H, t, Jꢀ7.2 Hz), 7.10 (1H, td, Jꢀ7.6, 1.4 Hz), 7.39—7.44
N-[2-(3-Dimethylaminopropylthio)phenyl]-3-phenylpropanamide (2H, m), 7.47—7.51 (2H, m), 7.58—7.60 (1H, m), 7.64—7.66 (2H, m), 7.75
(2)13) To a solution of 29 (210 mg, 1.0 mmol) in CHCl3 (2 ml) was added 3- (2H, dt, Jꢀ8.6, 2.0Hz), 8.05 (2H, dt, Jꢀ8.6, 2.0 Hz), 8.63 (1H, dd, Jꢀ8.2,
phenylpropionyl chloride (168 mg, 1.0 mmol) in CHCl3 (3 ml) dropwise.
After refluxing for 1 h, the reaction mixture was alkalized with ammonia so-
lution (25%). The organic layer was dried over anhydrous MgSO4 and con-
1.4 Hz), 9.53 (1H, s, br). MS m/z: 390 (Mꢃ), 181, 152, 58 (100%); HR-MS
(EI) m/z: Calcd for C24H26N2OS (Mꢃ) 390.1766. Found 390.1760.
N-(2-Allylthiophenyl)cinnamide (10) In the same manner as described
centrated in vacuum. The residue was purified by flash column chromatogra- for 2, it was prepared from 3018) and cinnamoyl chloride in a yield of 92% as
phy on silica gel eluting with a mixture of chloroform (9) : methanol (1) to
a white crystal recrystallized from ethyl acetate–n-hexane, mp 99—100 °C.
afford 2 (305 mg, 89%) as a brownish oil. IR (KBr) cmꢂ1: 3338, 3026, 2941, IR (KBr) cmꢂ1: 3433, 3255, 3082, 1768, 1771, 1678, 1655, 1618, 1579,
1
1
2769, 1691, 1578, 1510, 1433, 1294, 1159, 1076, 1038; H-NMR (CDCl3) 1537, 1436, 1338, 1286, 1240, 1184, 1072; H-NMR (CDCl3) d: 3.38 (2H,
d: 1.63—1.70 (2H, m), 2.19 (6H, s), 2.33 (2H, t, Jꢀ7.1 Hz), 2.67 (2H, t,
Jꢀ7.3 Hz), 2.74 (2H, t, Jꢀ7.4 Hz), 3.08 (2H, t, Jꢀ7.4 Hz), 7.03 (1H, td,
d, t, Jꢀ7.3, 1.1 Hz), 4.93 (1H, dq, Jꢀ16.9, 1.2 Hz), 5.01 (1H, dt, Jꢀ10.0,
0.7 Hz), 5.77—5.87 (1H, m), 6.61 (1H, d, Jꢀ15.5 Hz), 7.07 (1H, td, Jꢀ7.6,
Jꢀ7.6, 1.1 Hz), 7.18—7.22 (1H, m), 7.25—7.34 (5H, m), 7.48 (1H, dd, 1.4 Hz), 7.36—7.46 (4H, m), 7.53 (1H, dd, Jꢀ7.8, 1.6 Hz), 7.58—7.60 (2H,
Jꢀ7.7, 1.5 Hz), 8.39 (1H, d, Jꢀ8.1 Hz), 8.45 (1H, s, br). MS m/z: 342 (Mꢃ),
281, 58 (100%).
m), 7.77 (1H, d, Jꢀ15.5 Hz), 8.56 (1H, d, Jꢀ8.1 Hz), 8.72 (1H, s, br). MS
m/z: 295 (Mꢃ), 222, 131 (100%), 103, 77; Anal. Calcd for C18H17NOS: C,
73.19; H, 5.80; N, 4.74. Found: C, 73.20; H, 5.76; N, 4.66.
Benzyl N-2-(3-Dimethylaminopropylthio)phenylcarbamate (3) In the
same manner as described for 2, it was prepared from 29 and benzyl chloro-
N-(2-Benzylthiophenyl)cinnamide (11)19) In the same manner as de-
formate in a yield of 12% as a brown oil. IR (Film) cmꢂ1: 3350, 2856, 2941, scribed for 2, it was prepared from 3120) and cinnamoyl chloride in a yield of
1
2767, 1738, 1581, 1514, 1437, 1304, 1202, 1072, 1041; H-NMR (CDCl3) 63% as a white crystal recrystallized from ethyl acetate–n-hexane, mp
d: 1.65—1.72 (2H, m), 2.17 (6H, s), 2.34 (2H, t, Jꢀ7.1 Hz), 2.75 (2H, t,
Jꢀ7.1 Hz), 5.22 (2H, s), 6.99 (1H, td, Jꢀ7.5, 1.2 Hz), 7.30—7.45 (6H, m),
7.49 (1H, dd, Jꢀ7.8, 1.5 Hz), 8.09 (1H, s, br), 8.17 (1H, d, Jꢀ8.2 Hz). MS
m/z: 344 (Mꢃ), 91, 58 (100%); HR-MS (EI) m/z: Calcd for C19H24N2O2S
(Mꢃ) 344.1558. Found 344.1577.
138—139.5 °C. IR (KBr) cmꢂ1: 3222, 3026, 1660, 1626, 1576, 1537, 1441,
1344, 1284, 1188; 1H-NMR (CDCl3) d: 3.90 (2H, s), 6.26 (1H, d,
Jꢀ15.5 Hz), 7.02—7.08 (3H, m), 7.16—7.24 (3H, m), 7.35—7.45 (4H, m),
7.48 (1H, dd, Jꢀ7.7, 1.2 Hz), 7.54—7.56 (2H, m), 7.62 (1H, d, Jꢀ15.5 Hz),
8.37 (1H, s, br), 8.51 (1H, d, Jꢀ8.0 Hz). MS m/z: 345 (Mꢃ), 254, 222, 214,
N-[2-(3-Dimethylaminopropylthio)phenyl]phenylacetamide (4)13) In 131 (100%), 103, 91; Anal. Calcd for C22H19NOS: C, 76.49; H, 5.54; N,
the same manner as described for 2, it was prepared from 29 and phenyl- 4.05. Found: C, 76.46; H, 5.57; N, 3.95.
acetyl chloride in a yield of 49% as a brown oil. IR (Film) cmꢂ1: 3315,
N-[2-(Phenethylthio)phenyl]cinnamide (12) In the same manner as
1
2939, 2767, 1687, 1579, 1514, 1433, 1302, 1159, 1036; H-NMR (CDCl3) described for 2, it was prepared from 3221) and cinnamoyl chloride in a yield
d: 1.43—1.50 (2H, m), 2.15 (6H, s), 2.19 (2H, t, Jꢀ7.0 Hz), 2.40 (2H, t,
Jꢀ7.3 Hz), 3.79 (2H, s), 6.99 (1H, td, Jꢀ7.6, 1.4 Hz), 7.27—7.43 (7H, m),
8.42 (1H, d, Jꢀ8.2 Hz), 8.53 (1H, s, br).
of 70% as a white crystal recrystallized from ethyl acetate–n-hexane, mp
98—99.5 °C. IR (KBr) cmꢂ1: 3433, 3242, 3026, 1660, 1626, 1576, 1531,
1442, 1340, 1275, 1178, 1068; 1H-NMR (CDCl3) d: 2.86 (2H, t, Jꢀ7.3 Hz),
N-[2-(3-Dimethylaminopropylthio)phenyl]benzamide (5)13) In the 3.10 (2H, t, Jꢀ7.3 Hz), 6.38 (1H, d, Jꢀ15.5 Hz), 7.09 (1H, td, Jꢀ7.6,
same manner as described for 2, it was prepared from 29 and benzoyl chlo- 1.4 Hz), 7.15—7.30 (5H, m), 7.37—7.44 (4H, m), 7.54—7.59 (3H, m), 7.73
ride in a yield of 95% as a brown gel. IR (KBr) cmꢂ1: 3342, 2941, 2771,
1680, 1579, 1516, 1431, 1306, 1277, 1250, 1028; 1H-NMR (CDCl3) d:
1.69—1.76 (2H, m), 2.15 (6H, s), 2.34 (2H, t, Jꢀ7.0 Hz), 2.82 (2H, t,
Jꢀ7.2 Hz), 7.09 (1H, td, Jꢀ7.6, 1.3 Hz), 7.37—7.41 (1H, m), 7.50—7.60
(4H, m), 7.95—7.98 (2H, m), 8.59 (1H, dd, Jꢀ8.2, 1.3 Hz), 9.46 (1H, s, br).
MS m/z: 314 (Mꢃ), 253, 105, 77, 58 (100%).
(1H, d, Jꢀ15.5 Hz), 8.57 (1H, s, br), 8.58 (1H, d, Jꢀ8.0 Hz). MS m/z: 359
(Mꢃ), 255, 222, 131 (100%), 103; Anal. Calcd for C23H21NOS: C, 76.85; H,
5.89; N, 3.90. Found: C, 76.70; H, 5.93; N, 3.88.
N-(2-Carbomethoxyethylthiophenyl)cinnamide (13) In the same man-
ner as described for 2, it was prepared from 3322) and cinnamoyl chloride in
a yield of 84% as a yellow solid recrystallized from ethyl acetate–n-hexane,
N-[2-(3-Dimethylaminopropylthio)phenyl]-4-methylbenzenesulfon- mp 106—107 °C. IR (Film) cmꢂ1: 3319, 2947, 1724, 1672, 1624, 1578,
amide (6) In the same manner as described for 2, it was prepared from 29
1512, 1437, 1336, 1284, 1203, 1225, 1171, 1007; 1H-NMR (CDCl3) d: 2.57
and p-toluenesulfonyl chloride in a yield of 54% as a yellow solid. IR (KBr) (2H, t, Jꢀ6.6 Hz), 3.02 (2H, t, Jꢀ6.6 Hz), 3.71 (3H, s), 6.80 (1H, d,
cmꢂ1: 3425, 3103, 2922, 2474, 1599, 1572, 1473, 1433, 1334, 1240, 1167, Jꢀ15.6 Hz), 7.07 (1H, td, Jꢀ7.6, 1.4 Hz), 7.37—7.43 (4H, m), 7.56 (1H, dd,
1092, 1068; 1H-NMR (CDCl3) d: 1.78—1.85 (2H, m), 2.36 (3H, s), 2.63 Jꢀ6.4, 1.3 Hz), 7.59—7.63 (2H, m), 7.78 (1H, d, Jꢀ15.6 Hz), 8.62 (1H, d,
(6H, s), 2.70 (2H, t, Jꢀ6.7 Hz), 2.95 (2H, s, br), 7.04 (1H, td, Jꢀ7.6,
Jꢀ8.1 Hz), 8.91 (1H, s, br). MS m/z: 341 (Mꢃ), 222, 211, 131 (100%), 103,
1.2 Hz), 7.20—7.23 (3H, m), 7.35 (1H, dd, Jꢀ8.2, 0.9 Hz), 7.45 (1H, dd, 77; HR-MS (EI) m/z: Calcd for C19H19NO3S (Mꢃ) 341.1086, Found
Jꢀ7.9, 1.5 Hz), 7.69 (2H, dt, Jꢀ8.5, 1.8 Hz). MS m/z: 364 (Mꢃ), 209, 91, 341.1100.
84, 58 (100%); HR-MS (EI) m/z: Calcd for C18H24N2O2S2 (Mꢃ) 364.1279.
Found 364.1268.
N-[2-(4-Nitrobenzylthio)phenyl]cinnamide (14) In the same manner
as described for 2, it was prepared from 3423) and cinnamoyl chloride in a

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Vol. 56, No. 10
Jꢀ7.8 Hz), 9.11 (1H, s, br). MS m/z: 368 (Mꢃ), 131, 113, 100 (100%).
yield of 53% as a yellowish crystal recrystallized from ethyl acetate–n-
hexane, mp 160—162 °C. IR (KBr) cmꢂ1: 3292, 3076, 1660, 1620, 1572,
1522, 1433, 1340, 1172; 1H-NMR (CDCl3) d: 3.93 (2H, s), 6.37 (1H, d,
Jꢀ15.5 Hz), 7.01 (1H, td, Jꢀ7.6 Hz), 7.15—7.19 (2H, m), 7.31—7.34 (1H,
m), 7.38—7.44 (4H, m), 7.54—7.57 (2H, m), 7.67 (1H, d, Jꢀ15.5 Hz),
8.04—8.07 (2H, m), 8.38 (1H, s, br), 8.47 (1H, d, Jꢀ8.2 Hz), MS m/z: 390
(Mꢃ), 242, 131 (100%), 103, 77; 125, 91; Anal. Calcd for C22H18N2O3S: C,
67.67; H, 4.65; N, 7.17. Found: C, 67.39; H, 4.69; N, 6.93.
N-[2-(3-Methoxypropylthio)phenyl]cinnamide (15) In the same man-
ner as described for 2, it was prepared from 35 and cinnamoyl chloride in a
yield of 61% as a yellowish oil. IR (KBr) cmꢂ1: 3425, 3278, 2902, 2868,
1658, 1624, 1578, 1537, 1446, 1344, 1284, 1238, 1182, 1120; 1H-NMR
(CDCl3) d: 1.80—1.86 (2H, m), 2.87 (2H, t, Jꢀ7.2 Hz), 3.30 (3H, s), 3.45
(2H, t, Jꢀ6.0 Hz), 6.62 (1H, d, Jꢀ15.4 Hz), 7.06 (1H, td, Jꢀ7.5, 1.3 Hz),
7.34—7.43 (4H, m), 7.54 (1H, dd, Jꢀ7.7 Hz), 7.56—7.60 (2H, m), 7.77
(1H, d, Jꢀ15.4 Hz), 8.55 (1H, d, Jꢀ8.1 Hz), 8.74 (1H, s, br). MS m/z: 327
(Mꢃ), 222, 131 (100%), 103; HR-MS (EI) m/z: Calcd for C19H21NO2S (Mꢃ)
327.1293. Found 327.1290.
N-[2-(4-Methoxybutylthio)phenyl]cinnamide (16) In the same manner
as described for 2, it was prepared from 36 and cinnamoyl chloride in a yield
of 87% as a white crystal, mp 61—62.5 °C; IR (KBr) cmꢂ1: 3433, 3228,
3026, 2868, 1660, 1628, 1570, 1529, 1444, 1342, 1273, 1236, 1182, 1117;
1H-NMR (CDCl3) d: 1.63—1.71 (4H, m), 2.80 (2H, t, Jꢀ7.1 Hz), 3.28 (3H,
s), 3.35 (2H, t, Jꢀ6.0 Hz), 6.61 (1H, d, Jꢀ15.4 Hz), 7.07 (1H, td, Jꢀ7.5,
1.3 Hz), 7.34—7.43 (4H, m), 7.54 (1H, dd, Jꢀ7.7, 1.3 Hz), 7.58—7.60 (2H,
m), 7.77 (1H, d, Jꢀ15.4 Hz), 8.55 (1H, d, Jꢀ7.9 Hz), 8.73 (1H, s, br). MS
m/z: 341 (Mꢃ), 222, 131 (100%), 103, 87, 77; Anal. Calcd for C20H23NO2S:
C, 70.35; H, 6.79; N, 4.10. Found: C, 70.37; H, 6.70; N, 4.09.
N-[2-(2-Phenoxyethylthio)phenyl]cinnamide (22) In the same manner
as described for 2, it was prepared from 42 and cinnamoyl chloride in a yield
of 69% as a white crystal recrystallized from ethyl acetate–n-hexane, mp
111.5—113 °C. IR (KBr) cmꢂ1: 3433, 3294, 3053, 1660, 1630, 1603, 1578,
1527, 1496, 1466, 1439, 1288, 1242, 1176, 1036; 1H-NMR (CDCl3) d: 3.14
(2H, t, Jꢀ5.9 Hz), 4.04 (2H, t, Jꢀ5.9 Hz), 6.44 (1H, d, Jꢀ15.6 Hz), 6.85—
6.90 (3H, m), 7.09 (1H, td, Jꢀ7.4, 1.2 Hz), 7.17—7.22 (2H, m), 7.36—7.46
(6H, m), 7.63 (1H, dd, Jꢀ7.7, 1.7 Hz), 7.67 (1H, d, Jꢀ15.6 Hz), 8.60 (1H, d,
Jꢀ8.4 Hz), 8.90 (1H, s, br). MS m/z: 375 (Mꢃ), 281, 254, 222, 131 (100%),
103, 77; Anal. Calcd for C23H21NO2S: C, 73.57; H, 5.64; N, 3.73. Found: C,
73.83; H, 5.73; N, 3.98.
N-[2-(3-Dimethylaminopropoxy)phenyl]cinnamide (23)13) In the same
manner as described for 2, it was prepared from 4513) and cinnamoyl chlo-
ride in a yield of 58% as a brownish oil. IR (KBr) cmꢂ1: 3251, 3060, 2945,
2812, 2764, 1662, 1626, 1545, 1491, 1450, 1350, 1286, 1259, 1221, 1186,
1117, 1055; 1H-NMR (CDCl3) d: 2.00—2.09 (2H, m), 2.28 (6H, s), 2.48
(2H, t, Jꢀ6.9 Hz), 4.13 (2H, t, Jꢀ6.5 Hz), 6.59 (1H, d, Jꢀ15.5 Hz), 6.90—
6.93 (1H, m), 6.97—7.06 (2H, m), 7.35—7.42 (3H, m), 7.55—7.58 (2H, m),
7.75 (1H, d, Jꢀ15.5 Hz), 8.13 (1H, s, br), 8.52 (1H, d, Jꢀ6.5Hz).
N-[2-(3-Dimethylaminopropoxy)-5-nitrophenyl]cinnamide (24)26) In
the same manner as described for 2, it was prepared from 4626) and cin-
namoyl chloride in a yield of 58% as a brownish oil, mp 124.5—126 °C; 1H-
NMR (CDCl3) d: 2.05—2.12 (2H, m), 2.29 (6H, s), 2.50 (2H, t, Jꢀ6.8 Hz),
4.26 (2H, t, Jꢀ6.4 Hz), 6.58 (1H, d, Jꢀ15.4 Hz), 6.96 (1H, d, Jꢀ8.9 Hz),
7.37—7.44 (3H, m), 7.55—7.59 (2H, m), 7.80 (1H, d, Jꢀ15.5 Hz), 7.98
(1H, dd, Jꢀ8.9, 2.7 Hz), 8.17 (1H, s, br), 9.45 (1H, d, Jꢀ2.7 Hz).
N-[2-(3-Dimethylaminopropylsulfinyl)phenyl]cinnamide (25) To
a
N-[2-(2-N-Methylpyrrolidylethylthio)phenyl]cinnamide (17) In the
same manner as described for 2, it was prepared from 37 and cinnamoyl
chloride in a yield of 84% as a yellowish oil. IR (KBr) cmꢂ1: 3440, 3228,
2937, 3030, 2779, 1660, 1628, 1576, 1533, 1439, 1348, 1288, 1188; 1H-
NMR (CDCl3) d: 1.36—1.61 (2H, m), 1.64—1.76 (2H, m), 1.85—1.96 (2H,
m), 2.09—2.17 (2H, m), 2.25 (3H, s), 2.69—2.88 (2H, m), 3.00—3.05 (1H,
m), 6.60 (1H, d, Jꢀ15.6 Hz), 7.06 (1H, td, Jꢀ7.5, 1.3 Hz), 7.34—7.43 (4H,
m), 7.53—7.59 (3H, m), 7.76 (1H, d, Jꢀ15.6 Hz), 8.54 (1H, d, Jꢀ7.9 Hz),
8.72 (1H, s, br). MS m/z: 366 (Mꢃ), 236, 147, 131, 103, 84 (100%); HR-MS
(EI) m/z: Calcd for C22H26N2OS (Mꢃ) 366.1766. Found 366.1773.
solution of 1 (340 mg, 1.0 mmol) in CH3CN (2.5 ml) was added aqueous
NaIO4 (0.5 M, 2.5 ml) dropwise at ꢂ10 °C. After stirring at 0 °C for 12 h, an
additional aqueous NaIO4 (0.5 M, 2.5 ml) was added to the mixture, the stir-
ring was continued for 20 h. The mixture was filtered, and extracted with
CHCl3. The combined organic layer was washed, and dried over anhydrous
MgSO4. The filtrate was concentrated in vacuum. The residue was purified
by flash column chromatography on silica gel eluting with CHCl3 (9) :
CH3OH (1) to afford 25 (131 mg, 37%) as a yellow gel. IR (Film) cmꢂ1
:
3452, 3234, 2943, 1682, 1630, 1587, 1525, 1471, 1338, 1286, 1172, 1066,
1007; 1H-NMR (CDCl3) d: 1.87—1.97 (2H, m), 2.25 (6H, s), 2.41—2.54
(2H, m), 3.03—3.11 (1H, m), 3.24—3.31 (1H, m), 6.58 (1H, d, Jꢀ15.7 Hz),
7.15 (1H, td, Jꢀ7.4, 1.1 Hz), 7.29 (1H, dd, Jꢀ7.7, 1.4 Hz), 7.37—7.42 (3H,
m), 7.50—7.54 (1H, m), 7.57—5.59 (2H, m), 7.75 (1H, d, Jꢀ15.7 Hz), 8.61
(1H, d, Jꢀ8.5 Hz), 10.90 (1H, s, br). MS m/z: 356 (Mꢃ), 339, 149, 131, 111,
97, 84 (100%), 71, 58; HR-MS (EI) m/z: Calcd for C20H24N2O2S (Mꢃ)
356.1559. Found 356.1544.
N-[2-(4-Pyridylmethylthio)phenyl]cinnamide (18) In the same man-
ner as described for 2, it was prepared from 3824) and cinnamoyl chloride in
a yield of 96% as a brownish oil. IR (KBr) cmꢂ1: 3448, 3221, 3026, 1655,
1
1622, 1576, 1529, 1433, 1414, 1342, 1286, 1178, 1068; H-NMR (CDCl3)
d: 3.83 (2H, s), 6.42 (1H, d, Jꢀ15.4 Hz), 6.97—7.02 (2H, m), 7.32 (1H, dd,
Jꢀ7.7, 1.5 Hz), 7.36—7.44 (5H, m), 7.54—7.57 (2H, m), 7.69 (1H, d,
Jꢀ15.5 Hz), 8.43—8.46 (3H, m), 8.49 (1H, d, Jꢀ8.3 Hz). MS m/z: 346
(Mꢃ), 255, 216, 131 (100%), 103, 77; HR-MS (EI) m/z: Calcd for
C21H18N2OS (Mꢃ) 346.1140. Found 346.1141.
N-[2-(2-Pyridylmethylthio)phenyl]cinnamide (19) In the same man-
ner as described for 2, it was prepared from 3925) and cinnamoyl chloride in
a yield of 87% as a brownish crystal recrystallized from ethyl acetate–n-
hexane, mp 102—103.5 °C; IR (KBr) cmꢂ1: 3224, 3028, 1660, 1626, 1589,
1574, 1533, 1441, 1344, 1284, 1184; 1H-NMR (CDCl3) d: 4.04 (2H, s), 6.53
(1H, d, Jꢀ15.5 Hz), 6.80 (1H, d, Jꢀ7.7 Hz), 7.02—7.10 (2H, m), 7.34—
7.49 (5H, m), 7.55—7.60 (3H, m), 7.67 (1H, d, Jꢀ15.6 Hz), 8.49 (1H, d,
Jꢀ8.2 Hz), 8.55 (1H, dt, Jꢀ4.8, 0.8 Hz), 8.91 (1H, s, br). MS m/z: 346
(Mꢃ), 255, 222, 131, 103 (100%); Anal. Calcd for C21H18N2OS: C, 72.80; H,
5.24; N, 8.09. Found: C, 72.84; H, 5.27; N, 7.92.
N-(2-Cinnamoylthiophenyl)cinnamide (26) To a solution of 28 (125
mg, 1.0 mmol) and Et3N (0.6 ml) in CH2Cl2 (5 ml) was added at room tem-
perature a solution of cinnamoyl chloride (340 mg, 2.0 mmol) in CH2Cl2
(10 ml). After refluxing for 1 h, the reaction mixture was washed with water
and the organic layer was dried over anhydrous MgSO4. The solvent was re-
moved in vacuum and the residue was purified by flash column chromatog-
raphy on silica gel eluting with a mixture of petroleum ether (85) : chloro-
form (10) : ethyl acetate (5) to afford 26 (78 mg, 20%) as a white crystal re-
crystallized from ethyl acetate–n-hexane, mp 163—164 °C. IR (KBr) cmꢂ1
:
3317, 3055, 1674, 1614, 1578, 1516, 1439, 1333, 1280, 1174, 1032; 1H-
NMR (CDCl3) d: 6.51 (1H, d, Jꢀ15.5 Hz), 6.86 (1H, d, Jꢀ15.8 Hz), 7.20
(1H, td, Jꢀ7.7, 1.1 Hz), 7.34—7.61 (12H, m), 7.74 (1H, d, Jꢀ15.5 Hz), 7.75
(1H, d, Jꢀ15.8 Hz), 7.99 (1H, s, br), 8.48 (1H, d, Jꢀ7.6 Hz). MS m/z: 385
(Mꢃ), 357, 236, 131 (100%), 103, 77; Anal. Calcd for C24H19NO2S: C,
74.78; H, 4.97; N, 3.63. Found: C, 74.63; H, 4.94; N, 3.61.
N-[2-(3-Pyridylmethylthio)phenyl]cinnamide (20) In the same man-
ner as described for 2, it was prepared from 4024) and cinnamoyl chloride in
a yield of 60% as a brownish crystal, mp 106—107 °C; IR (KBr) cmꢂ1
:
N-[2-(2-Cyanocinnamoylthio)phenyl]-2-cyanocinnamide (27) In the
same manner as described for 26, it was prepared from 28 and 2-cyanocin-
namoyl chloride in a yield of 8.4% as a yellow crystal recrystallized from
ethyl acetate–n-haxane, mp 174—175 °C. IR (KBr) cmꢂ1: 3358, 3020, 2216,
1693, 1668, 1585, 1574, 1533, 1441, 1373, 1300, 1242, 1196, 1144, 1032;
1H-NMR (CDCl3) d: 7.29 (1H, td, Jꢀ7.8, 1.3 Hz), 7.47—7.63 (8H, m),
7.95—7.96 (2H, m), 8.04—8.06 (2H, m), 8.28 (1H, s), 8.40 (1H, s), 8.46
(1H, dd, Jꢀ8.3, 1.2 Hz), 8.77(1H, s, br). Anal. Calcd for C24H19NO2S: C,
71.71; H, 3.93; N, 9.65. Found: C, 71.46; H, 3.85; N, 9.55.
3184, 3026, 1658, 1626, 1574, 1537, 1439, 1344, 1284, 1238, 1184; 1H-
NMR (CDCl3) d: 3.88 (2H, s), 6.37 (1H, d, Jꢀ15.5 Hz), 7.00—7.04 (1H,
m), 7.10—7.13 (1H, m), 7.25—7.27 (1H, m), 7.36—7.43 (5H, m), 7.56—
7.58 (2H, m), 7.67 (1H, d, Jꢀ15.5 Hz), 8.38—8.42 (3H, m), 8.51 (1H, d,
Jꢀ8.0 Hz). MS m/z: 346 (Mꢃ), 313, 255, 222, 131 (100%), 103; Anal. Calcd
for C21H18N2OS: C, 72.80; H, 5.24; N, 8.09. Found: C, 73.05; H, 5.27; N,
7.92.
N-[2-(2-Morpholinoethylthio)phenyl]cinnamide (21)26) In the same
manner as described for 2, it was prepared from 4126) and cinnamoyl chlo-
ride in a yield of 81% as a yellowish oil. IR (KBr) cmꢂ1: 3440, 3257, 2800,
1664, 1632, 1576, 1529, 1442, 1344, 1178, 1115; 1H-NMR (CDCl3) d: 2.39
(4H, t, Jꢀ4.7 Hz), 2.46 (2H, t, Jꢀ6.7 Hz), 2.92 (2H, t, Jꢀ6.7 Hz), 3.68 (4H,
t, Jꢀ4.7 Hz), 6.67 (1H, d, Jꢀ15.6 Hz), 7.08 (1H, td, Jꢀ7.5, 1.4 Hz), 7.26—
7.44 (4H, m), 7.57—7.60 (3H, m), 7.78 (1H, d, Jꢀ15.6 Hz), 8.51 (1H, d,
References
1) Ksiazek T. G., Erdman D., Goldsmith C. S., Zaki S. R., Peret T.,
Emery S., Tong S., Urbani C., Comer J. A., Lim W., Rollin P. E., Dow-
ell S. F., Ling A.-E., Humphrey C. D., Shieh W.-J., Guarner J., Paddock
C. D., Rota P., Fields B., DeRisi J., Yang J.-Y., Cox N., Hughes J. M.,

October 2008
LeDuc J. W., Bellini W. J., Anderson L. J., the SARS Working Group,
1405
7) Thiel V., Herold J., Schelle B., Siddell S. G., J. Virol., 75, 6676—6681
N. Engl. J. Med., 348, 1953—1966 (2003).
(2001).
2) He J. F., Peng G. W., Min J., Yu D. W., Liang W. J., Zhang S. Y., Xu R.
H., Zheng H. Y., Wu X. W., Xu J., Fang L., Zhang X., Li H., Yan X.
G., Lu J. H., Hu Z. H., Huang J. C., Wan Z. Y., Lin J. Y., Song H. D.,
Wang S. Y., Zhou X. J., Zhang G. W., Guo B. W., Zheng H. J., Zhang
8) Murphy R. L., J. Acquired Immune Defic. Syndr., 33, S43—S52
(2003).
9) Anand K., Ziebuhr J., Wadhwani P., Masters J. R., Hilgenfeld R., Sci-
ence, 300, 1763—1767 (2003).
X. L., Zheng K., Wang B. F., Fu G., Hou J. L., Wang X. N., Chen S. J., 10) Thiel V., Ivanov K. A., Putics A., Hertzig T., Schelle B., J. Gen. Virol.,
Hao P., Tang H., Ren S. X., Zhong Y., Guo Z. M., Liu Q., Miao Y. G., 84, 2305—2315 (2003).
Kong X. Y., He W. Z., Li Y. X., Chen Z., Wu C.-I., Zhao G. P., Chiu R. 11) Fan K., Wei P., Feng Q., Chen S., Huang C.-K., Ma L., Lai B., Pei J.-F.,
W. K., Chim S. S. C., Tong Y. K., Chan P. K. S., Tan J. S., Lo Y. M. D.,
Science, 303, 1666—1669 (2004).
3) Wu C. Y., Jan J. T., Ma S. H., Kuo C. J., Juan H. F., Cheng Y. S. E.,
Hsu H. H., Huang H. C., Wu D., Ashraf B., Liang F. S., Liu R. S., Fang
J. M., Chen S. T., Liang P. H., Wong C. H., PNAS, 101, 10012—10017
(2004).
Liu Y., Chen J.-G., Lai L.-H., J. Biol. Chem., 279, 1637—1642 (2003).
12) Chen L. L., Gui C. S., Luo X. M., Yang Q. G., Gunther S., Scandella
E., Drosten C., Bai D. L., He X. C., Ludewig B., Chen J., Luo H. B.,
Yang Y. M., Yang Y. F., Zuo J. P., Thiel V., Chen K. X., Shen J. H.,
Shen X., Jiang H. L., J. Virol., 79, 7095—7103 (2005).
13) Krapcho J., Spitzmiller E. R., Turk C. F., Fried J., J. Med. Chem., 7,
376—377 (1964).
4) Marra M. A., Jones S. J. M., Astell C. R., Holt R. A., Brooks-Wilson
A., Butterfield Y. S. N., Khattra J., Asano J. K., Barber S. A., Chan S. 14) Krapcho J., US Patent, 3201401 (1965).
Y., Cloutier A., Coughlin S. M., Freeman G., Gim N., Griffith O. L., 15) Morris G. M., Goodsell D. S., Halliday R. S., Huey R., Hart W. E.,
Leach S. R., Mayo M., McDonald H., Montgomery S. B., Pandoh P.
K., Petrescu A. S., Robertson A. G., Schein J. E., Siddiqui A., Smailus
D. E., Stoot J. M., Yang G. S., Plummer F., Andonov A., Artsob H.,
Belew R. K., Olson A. J., J. Comput. Chem., 19, 1639—1662 (1998).
16) Wallace A. C., Laskowski R. A., Thornton J. M., Protein Eng., 8,
127—134 (1995).
Bastien N., Bernard K., Booth T. F., Bowness D., Czub M., Drebot 17) Delano W. L., “The PyMOL Molecular Graphics System,” DeLano
M., Fernando L., Flick R., Garbutt M., Gray M., Grolla A., Jones S., Scientific, Palo Alto, 2002.
Feldmann H., Meyers A., Kabain A., Li Y., Normand S., Stroher U., 18) Van Otterlo W. A. L., Morgans G. L., Khanye S. D., Aderibigbe B. A.
Tipples G. A., Tyler S., Vogrig R., Ward D., Watson B., Brunham R.
C., Krajden M., Petric M., Skowronski D. M., Upton C., Roper R. L.,
Science, 300, 1399—1404 (2003).
A., Michael J. P., Billing D. G., Tetrahedron Lett., 45, 9171—9175
(2004).
19) Krapcho J., Turk C. F., Piala J. J., J. Med. Chem., 11, 361—364 (1968).
20) Hucher N., Decroix B., Daïch A., J. Org. Chem., 66, 4695—4703
(2001).
5) Rota P. A., Oberste M. S., Monroe S. S., Nix W. A., Campagnoli R.,
Icenogle J. P., Penaranda S., Bankamp B., Maher K., Chen M.-H.,
Tong S., Tamin A., Lowe L., France M., DeRisi J. L., Chen Q., Wang 21) Raj Nandan P., Karin T., Can. J. Chem., 44, 1247—1258 (1966).
D., Erdman D. D., Peret T. C. T., Burns C., Ksiazek T. G., Rolin P. E., 22) Lévai A., Puzicha G., Syn. Comm., 15, 623—632 (1985).
Sanchez A., Liffick S., Holloway B., Limor J., McCaustland K., Olsen- 23) Harada T., Morimoto M., Nagasawa M., Takamura N., Inoue H., Oh-
Rasmussen M., Fouchier R., Gunther S., Osterhaus A. D. M. E.,
Drosten C., Pallansch M. A., Anderson L. J., Bellini W. J., Science, 24) Nacci V., Fiorini I., Corti P., Taddei I., Bernabei F., Fratiglioni P., Far-
300, 1394—1399 (2003). maco Ed. Sci., 35, 279—297 (1980).
6) Ruan Y., Wei C. L., Ling A. E., Vega V. B., Thoreau H., SeThoe S. Y., 25) Dhara P. K., Pramanik S., Lu T. H., Drew M. G. B., Chattopadhyay P.,
Chia J.-M., Ng P., Chiu K. P., Lim L., Zhang T., Chan K. P., Lin E. L. Polyhedron, 23, 2457—2464 (2004).
O., Ng M. L., Leo S. Y., Ng L. F. P., Ren E. C., Stanton L. W., Long P. 26) Krapcho J., Millonig R. C., Turk C. F., Amrein B. J., J. Med. Chem.,
M., Liu E. T., Lancet, 361, 1779—1785 (2003). 12, 164—166 (1969).
Ishi T., Takeda M., Chem. Pharm. Bull., 40, 1986—1989 (1992).