Synthesis and antibacterial activity of oxazolidinones containing triazolyl group

Article abstract of DOI:10.1016/j.ejmech.2007.01.012

A new series of oxazolidinones containing triazolyl group has been synthesized and tested for in vitro antibacterial activity by MIC determination against a panel of resistant and susceptible Gram-positive organisms. Most of the analogs in this series dis

Full text of DOI:10.1016/j.ejmech.2007.01.012

European Journal of Medicinal Chemistry 42 (2007) 1137e1143
http://www.elsevier.com/locate/ejmech
Short communication
Synthesis and antibacterial activity of oxazolidinones
containing triazolyl group
Houxing Fan a, Gang Xu a, Yilang Chen a, Zhiteng Jiang a, Shuhua Zhang b,
a
Yushe Yang a, , Ruyun Ji
*
a State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institute for Biological Sciences,
Chinese Academy of Sciences, Shanghai 201203, China
b Sichuan Industrial Institute of Antibiotics, Chengdu 610051, China
Received 1 November 2006; received in revised form 3 January 2007; accepted 8 January 2007
Available online 25 January 2007
Abstract
A new series of oxazolidinones containing triazolyl group has been synthesized and tested for in vitro antibacterial activity by MIC deter-
mination against a panel of resistant and susceptible Gram-positive organisms. Most of the analogs in this series displayed activity superior to
linezolid and vancomycin in vitro. Further, in vivo efficacies of the selected oxazolidinones were also disclosed herein.
Ó 2007 Elsevier Masson SAS. All rights reserved.
Keywords: Oxazolidinone; Linezolid; Antibacterial agents; Gram-positive organisms
1. Introduction
further exploration of features of oxazolidinone series to over-
come these issues.
Infections due to Gram-positive bacteria such as methicillin-
resistant Staphylococcus aureus (MRSA), vancomycin-re-
sistant Enterococcus faecium (VREF), and penicillin-resistant
Streptococcus pneumoniae (PRSP) are the leading cause of
morbidity and mortality in hospital settings and community
today [1e5]. Oxazolidinones, typified by linezolid (ZyvoxÔ,
Pharmacia/Pfizer, Fig. 1), represent a new class of synthetic
antibacterial agents with potent activity against clinically im-
portant susceptible and resistant Gram-positive pathogens [6].
Oxazolidinones inhibit the bacterial protein synthesis prior to
the chain initiation step by binding to the 23S rRNA of 50S
ribosomal subunit, and interfering with the initiator fMET-
tRNA binding to the P-site of the ribosomal peptidyltransferase
center [7,8]. Resistance to antibiotics may be unavoidable
and, recently, some linezolid-resistant clinical isolates of
VREF and S. aureus have been reported [9,10]. This unexpected
early development of resistance emphasizes the need for
We have found that the introduction of sulfonyl group to
oxazolidinones, such as YC-20 (Fig. 1) [11], could enhance
their antibacterial activities. In addition, recent studies have
shown that the conversion of the acetamide group of linezolid
to the triazolyl group to get PH-027 (Fig. 1) could restore its
antibacterial activities and reduce its activity against mono-
amine oxidase [12,13]. In order to find more potent oxazolidi-
none antibacterial agents with reduced side effects, we
combined the structural properties of YC-20 and PH-027
into one molecule. In this paper, we report our efforts towards
the synthesis and in vitro antibacterial activities of a new series
of oxazolidinone derivatives bearing a triazolyl side chain at
the C-5 position and a sulfonyl group as well as being linked
to piperazine ring. Furthermore, the in vivo activity of the se-
lected compounds 7, 16 and 20 was tested in mice mode.
2. Chemistry
Synthesis of these novel compounds was carried out in
a straightforward manner. The intermediate azide derivative
* Corresponding author. Tel./fax: þ86 21 50806786.
E-mail address: ysyang@mail.shcnc.ac.cn (Y. Yang).
0223-5234/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2007.01.012

1138
H. Fan et al. / European Journal of Medicinal Chemistry 42 (2007) 1137e1143
Fig. 1. Structures of linezolid, PH-027 and YC-20.
1 was synthesized from the readily available starting materials
piperazine and 3,4-difluoronitrobenzene according to the
known method [14,15] in several steps. Treatment of com-
pound 1 with acetylene in a steel bomb and dimethoxyethane
(DME) as solvent at 90 ꢀC for 16 h afforded compound 2. An-
other improved method is treatment of compound 1 with vinyl
They were less potent by several-fold than linezolid despite
comparable in vitro activity against the organism. This differ-
ence in in vivo potency may be due to their poor water solubil-
ity or suboptimal pharmacokinetic properties.
4. Conclusion
˚
acetate, sodium carbonate and 4 A molecular sieves at reflux-
ing temperature for 84 h to get compound 2 with a yield of
82%. This improved method has several advantages over the
former such as no use of inflammable gas acetylene or high-
pressure proof equipments. Removal of the Cbz protection
group of compound 2 under an atmosphere of hydrogen by
hydrogenation at room temperature afforded compound 3.
The key intermediate amine compound 3 was condensed
with various sulfonyl chloride analogs to afford the desired
compounds (Scheme 1). Further chemical transformation in-
volving treatment of compound 16 with 10% palladium on
carbon in dichloromethane and methanol under hydrogen
afforded compound 20 with good yield. The structure of the
In conclusion, a series of new 5-triazole substituted oxazo-
lidinones was synthesized and evaluated for microbiological
activity against a panel of resistant and susceptible Gram-pos-
itive organisms in vitro comparable to linezolid and vancomy-
cin. Most of them were more potent than linezolid and
vancomycin. Several analogs from this series also exhibited
in vivo activity in a lethal murine infection model when ad-
ministered orally, but were less effective than linezolid. Fur-
ther optimization of this new class of oxazolidinone analogs
is ongoing in our laboratories.
5. Experimental protocols
1
target compounds was confirmed by H NMR, MS and ele-
mental analysis.
5.1. General procedures
All solvents used were of analytical grade (Sinopharm
Chemical Reagent Co., Ltd.). Melting points (uncorrected)
were determined in open capillaries on a MEL-TEMP appara-
3. Results and discussion
The result of in vitro antibacterial activity against a spec-
trum of resistant and susceptible Gram-positive organisms is
summarized in Table 1. It clearly shows that all compounds
bearing sulfonyl group have good antibacterial activity.
Compounds 5, 7, 13, 16 and 20 showed more potent antibac-
terial activity than linezolid and vancomycin. Obviously, the
introduction of strong electron-withdrawing groups (e.g. eCF3,
eF and eNO2) into the oxazolidinones can confer excellent
antibacterial activity especially at the 3-position of the phenyl-
sulfonyl group, in addition, electron-donating groups (e.g. eCl
and eNH2), as shown in compounds 5 and 20, can increase ac-
tivity too, but eBr and eCH3 lead to a slight decrease in
activity. The replacement of the phenyl of compound 4 with
2-thiophenyl (compound 19) led to an increase in activity, it
suggested that the introduction of heteroaryl ring system into
the molecule may increase its antibacterial activity.
1
tus. H NMR spectral data were recorded on a Varian Mer-
cury-400 spectrometer, chemical shifts are given in parts per
million (d) values and coupling constants (J ) in Hz. EI-MS
spectra were obtained on a Finnigan MAT 95 mass spectrom-
eter. Elemental analyses were obtained using a vario EL spec-
trometer. Column chromatography was performed on silica gel
H (200e300 mesh, Qingdao Marine Chemical Ltd.), and the
solvent proportions were expressed on a volume:volume basis.
5.2. Procedure for preparation of compound 2
A solution of the 5-azidomethyl 1 (4.34 g, 9.56 mmol) in
dimethoxyethane (40 mL) was placed in a steel bomb and
cooled to ꢁ78 ꢀC in a dry iceeacetone bath. A stream of ex-
cess acetylene gas was passed into the bomb to condense over
a period of 3 min, the steel bomb was tightly closed and the
mixture was heated at 90 ꢀC for 16 h. The bomb was cooled
The in vivo activity of compounds 7, 16 and 20 was tested
in mice mode, see Table 2, but the result was not desirable.

H. Fan et al. / European Journal of Medicinal Chemistry 42 (2007) 1137e1143
1139
ꢀ
˚
Scheme 1. (a) C2H2, DME, 90 C, 16 h; or vinyl acetate, 4 A molecular sieves, Na2CO3, refluxing, 84 h; (b) 10% Pd/C, H2, CH3OH overnight; (c) RSO2Cl, Et3N,
CH2Cl2, 0.5 h; (d) 10% Pd/C, H2, CH3OH/CH2Cl2, overnight.
to 0 ꢀC and excess acetylene was released carefully and the
mixture was concentrated to give a yellow solid, which was re-
crystallized from ethyl acetate and petroleum ether (1:10) mix-
ture to afford compound 2 (3.37 g, 81%) as a white solid.
Another improved method to get compound 2. A mixture of
compound 1 (17.82 g, 39.25 mmol), anhydrous sodium car-
˚
bonate (4.16 g, 39.25 mmol) and a small amount of 4 A mo-
lecular sieves in vinyl acetate (350 mL) was stirred under
Table 1
MIC (mg/ml) values of new oxazolidinones in various Gram-positive bacteria
F
O
F
O
O
S
O
O
N
N
N
N
R
N
N
R
N
N
N
N
N
N
O
2, 3
4-20
No
R
MSSAa
MRSAb
MSSEc
MRSEd
EFe
PRSPf
0.5e1
2
Cbz
H
0.25e1
1e2
1e2
0.5
1
0.5e2
1e2
2e4
0.5e1
4e8
1e2
1
0.5
2
3
1e2
1e2
1e4
0.5e2
0.5e2
8
1e2
1e4
4
Ph
( p)-ClPh
2e4
0.25e0.5
2e8
0.004e0.015
1e2
2e8
5
0.125e0.5
4e8
0.001e0.008
0.5e1
2e4
0.5e2
8
0.125e0.5
2e4
0.002e0.5
0.5e1
2e4
6
( p)-BrPh
(m)-FPh
7
0.25e0.5
1e2
2e8
0.25e1
0.5e1
1e2
0.5e2
2e4
2e4
8
( p)-FPh
9
2,4-di-FPh
( p)-CH3Ph
( p)-CH3OPh
(o)-CF3Ph
(m)-CF3Ph
( p)-CF3Ph
(o)-NO2Ph
(m)-NO2Ph
( p)-NO2Ph
( p)-CNPh
2-Thiophenyl
(m)-NH2Ph
1e4
2e4
2e4
2e4
0.5e1
1
10
11
12
13
14
15
16
17
18
19
20
Van
LZ
1e2
1e2
1e2
2e4
2e4
1e4
0.5e2
0.5e2
0.5e2
0.5e2
0.06e1
1
1e2
2e4
0.06e0.125
0.5e1
0.5e1
0.06e0.125
0.5e1
0.5e1
0.06e0.5
1e2
0.03e0.06
0.5e2
0.5e2
0.03e0.06
1e4
0.015e0.06
0.5e2
0.5e2
1
1
0.06e0.125
1e2
2e4
0.06e1
1e4
0.5e4
1
0.5e1
1e2
2e4
1
0.015e0.06
0.5e2
4e8
2e4
4e8
1e2
1e2
1
1e2
0.5e1
0.125e0.5
0.25e0.5
0.125e1
0.25e1
0.5e1
1e2
0.5e1
0.5e1
1e2
1e2
0.25e1
0.5e2
0.25e0.5
0.25e1
0.25e1
0.25e0.5
0.25e0.5
Van ¼ Vancomycin; LZ ¼ linezolid.
a
MSSA ¼ Methicillin-susceptible S. aureus. n ¼ 5 strains.
MRSA ¼ Methicillin-resistant S. aureus. n ¼ 5 strains.
b
c
d
e
f
MSSE ¼ Methicillin-susceptible Streptococcus epidermidis. n ¼ 5 strains.
MRSE ¼ Methicillin-resistant S. epidermidis. n ¼ 5 strains.
EF ¼ Enterococcus faecalis. n ¼ 5 strains.
PRSP ¼ Penicillin-resistant S. pneumoniae. n ¼ 10 strains.

1140
H. Fan et al. / European Journal of Medicinal Chemistry 42 (2007) 1137e1143
Table 2
In vivo efficacies (ED50, mg/kg) of selected compounds (route ¼ p.o.)
5.6. Structural data
Compounds
MRSA BAA-42
MSSA 04-5
MRSE 03427
5.6.1. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(benzyloxycarbonyl)piperazin-1-yl)phenyl)oxazolidin-2-
one (2)
7
16
>100
>100
>100
17.88
55.14
55.14
>100
84.30
>100
84.77
Mp: 184e186 ꢀC. 1H NMR (CDCl3): d 7.78 (s, 1H), 7.74 (s,
1H), 7.28e7.38 (m, 6H), 6.96 (dd, J1 ¼ 2.57 Hz, J2 ¼ 8.91 Hz,
1H), 6.88 (t, J ¼ 9.04 Hz, 1H), 5.15 (s, 2H), 5.04 (m, 1H),
4.78 (d, J ¼ 4.39 Hz, 2H), 4.12 (t, J ¼ 9.16 Hz, 1H), 3.90 (dd,
J1 ¼ 6.10 Hz, J2 ¼ 9.28 Hz, 1H), 3.66 (m, 4H), 3.00 (br s, 4H).
MS (EI) m/z (%): 480 (Mþ, 93), 91 (100). Anal. Calcd for
C24H25FN6O4: C, 59.99; H, 5.24; N, 17.49. Found: C, 60.06;
H, 5.25; N, 17.51.
20
Linezolid
>100
23.96
nitrogen at refluxing temperature for 84 h. The mixture was
concentrated and the residue was diluted with dichlorome-
thane, the mixture was then filtered through diatomaceous
earth, the filter cake was washed with dichloromethane, and
the combined filtrates were concentrated to give a slight yel-
low solid. The solid was triturated with methanol (30 mL)
twice to afford compound 2 (15.4 g, 82%) as a white solid.
5.6.2. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(piperazin-1-yl)phenyl)oxazolidin-2-one (3)
1
Mp: 202e204 ꢀC. H NMR (CDCl3): d 7.79 (s, 1H), 7.75
5.3. Procedure for preparation of compound 3
(s, 1H), 7.28 (dd, J1 ¼ 2.48 Hz, J2 ¼ 13.75 Hz, 1H), 6.97
(dd, J1 ¼ 2.20 Hz, J2 ¼ 8.94 Hz, 1H), 6.89 (t, J ¼ 8.87 Hz,
1H), 5.04 (m, 1H), 4.78 (d, J ¼ 3.90 Hz, 2H), 4.12 (t,
J ¼ 9.14 Hz, 1H), 3.89 (dd, J1 ¼ 6.12 Hz, J2 ¼ 9.28 Hz, 1H),
3.02 (m, 8H). MS (EI) m/z (%): 346 (Mþ, 54), 304 (100).
A mixture of compound 2 (4.80 g, 10 mmol) and 10%
palladium on carbon (0.1 g) in ethyl acetate (50 mL) and
methanol (50 mL) was stirred under hydrogen (balloon) over-
night. The mixture was then filtered through diatomaceous
earth, the filter cake was washed with methanol, and the com-
bined filtrates were concentrated to give a slight yellow solid.
Purification by silica gel column chromatography eluting with
dichloromethane and methanol (5:1) gave a slight yellow
solid. Recrystallization from ethyl acetate and petroleum ether
(1:2) afforded compound 3 (1.84 g, 53%) as a white solid.
5.6.3. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(phenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-2-one
(4)
Mp: 182e184 ꢀC. 1H NMR (CDCl3): d 7.71e7.76 (m, 3H),
7.67 (d, J ¼ 0.98 Hz, 1H), 7.56e7.62 (m, 1H), 7.49e7.54 (m,
2H), 7.25 (dd, J1 ¼ 2.54 Hz, J2 ¼ 14.08 Hz, 1H), 6.89 (dd,
J1 ¼ 2.35 Hz, J2 ¼ 8.81 Hz, 1H), 6.82 (t, J ¼ 9.00 Hz, 1H),
5.01 (m, 1H), 4.74 (m, 2H), 4.07 (t, J ¼ 9.09 Hz, 1H), 3.84
(dd, J1 ¼ 6.06 Hz, J2 ¼ 9.39 Hz, 1H), 3.03e3.14 (m, 8H).
MS (EI) m/z (%): 486 (Mþ, 7), 91 (100). Anal. Calcd for:
C22H23FN6O4S: C, 54.31; H, 4.76; N, 17.27. Found: C,
54.38; H, 4.88; N, 16.99.
5.4. General procedure for preparation
of compounds 4e19
To a solution of compound 3 (100 mg, 0.29 mmol) and pyri-
dine (0.2 mL) in anhydrous dichloromethane (15 mL) was
added phenylsulfonyl chloride (67 mg, 0.30 mmol) under
iceesalt bath. The mixture was stirred at room temperature
for 0.5 h, then washed with water and extracted with dichloro-
methane. The combined organic extract was dried over Na2SO4,
and then concentrated in vacuo. The residue was purified by sil-
ica gel column chromatography eluting with dichloromethane
and methanol (50:1) to afford compound 4 (48 mg, 34%) as
a white solid.
5.6.4. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(4-chlorophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (5)
Mp: 232e234 ꢀC. 1H NMR (CDCl3): d 7.78e7.83 (m, 2H),
7.77 (d, J ¼ 1.01 Hz, 1H), 7.74 (d, J ¼ 1.01 Hz, 1H), 7.28 (dd,
J1 ¼ 2.69 Hz, J2 ¼ 13.93 Hz, 1H), 7.21e7.26 (m, 2H), 6.94
(dd, J1 ¼ 2.68 Hz, J2 ¼ 9.40 Hz, 1H), 6.86 (t, J ¼ 8.98 Hz,
1H), 5.05 (m, 1H), 4.79 (d, J ¼ 4.19 Hz, 2H), 4.12 (t,
J ¼ 9.15 Hz, 1H), 3.88 (dd, J1 ¼ 6.05 Hz, J2 ¼ 9.40 Hz, 1H),
3.18 (t, J ¼ 4.70 Hz, 4H), 3.10 (t, J ¼ 4.70 Hz, 4H). MS (EI)
m/z (%): 520 (Mþ, 3), 460 (100). Anal. Calcd for
C22H22FN6O4SCl.1/2CH3OH: C, 50.37; H, 4.47; N, 15.67.
Found: C, 50.58; H, 4.30; N, 15.55.
5.5. Procedure for preparation of compound 20
A mixture of compound 16 (100 mg, 0.19 mmol) and 10%
palladium on carbon (20 mg) in dichloromethane (10 mL) and
methanol (10 mL) was stirred under hydrogen (balloon) over-
night. The mixture was then filtered through diatomaceous
earth, the filter cake was washed with methanol, and the com-
bined filtrates were concentrated to give a slight yellow solid.
The solid was purified by silica gel column chromatography
eluting with dichloromethane and methanol (50:1) to get
a slight yellow solid, followed by recrystallization from a mix-
ture of ethyl acetate and petroleum ether (1:5) to afford com-
pound 20 (58 mg, 62%) as a white solid.
5.6.5. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(4-bromophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (6)
Mp: 197e200 ꢀC. 1H NMR (CDCl3):
d 7.78 (d,
J ¼ 1.07 Hz, 1H), 7.74 (d, J ¼ 0.92 Hz, 1H), 7.62e7.72 (m,
4H), 7.28 (dd, J1 ¼ 2.44 Hz, J2 ¼ 13.88 Hz, 1H), 6.93 (dd,
J1 ¼ 2.30 Hz, J2 ¼ 9.30 Hz, 1H), 6.86 (t, J ¼ 8.93 Hz, 1H),

H. Fan et al. / European Journal of Medicinal Chemistry 42 (2007) 1137e1143
1141
5.04 (m, 1H), 4.78 (d, J ¼ 4.71 Hz, 2H), 4.11 (t, J ¼ 9.16 Hz,
1H), 3.89 (dd, J1 ¼ 6.11 Hz, J2 ¼ 9.46 Hz, 1H), 3.08e3.20 (m,
8H). MS (EI) m/z (%): 564 (Mþ, 12), 566 (12), 56 (100). Anal.
Calcd for C22H23FBrN6O4S.1/2CH3OH: C, 46.48; H, 4.16; N,
14.45. Found: C, 46.21; H, 4.08; N, 14.14.
3.05e3.16 (m, 8H), 2.42 (s, 3H). MS (EI) m/z (%): 500
(Mþ, 52), 345(100). Anal. Calcd for C23H25FN6O4S: C,
55.19; H, 5.03; N, 16.78. Found: C, 54.92; H, 5.00; N, 16.38.
5.6.10. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(4-methoxphenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (11)
5.6.6. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(3-fluorophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (7)
Mp: 203e205 ꢀC. 1H NMR (CDCl3): d 7.70e7.79 (m, 4H),
7.28 (dd, J1 ¼ 2.44 Hz, J2 ¼ 13.89 Hz, 1H), 7.02 (m, 2H), 6.94
(dd, J1 ¼ 2.64 Hz, J2 ¼ 9.29 Hz, 1H), 6.86 (t, J ¼ 8.90 Hz,
1H), 5.05 (m, 1H), 4.78 (dd, J1 ¼ 0.88 Hz, J2 ¼ 3.92 Hz,
2H), 4.10 (t, J ¼ 9.15 Hz, 1H), 3.88 (m, 4H), 3.06e3.16 (m,
8H). MS (EI) m/z (%): 516 (Mþ, 28), 56 (100). Anal. Calcd
for C23H25FN6O5S: C, 53.48; H, 4.88; N, 16.27. Found: C,
16.38; H, 4.83; N, 53.64.
Mp: 232e234 ꢀC. 1H NMR (CDCl3): d 7.85 (d, J ¼ 2.06 Hz,
1H), 7.82 (d, J ¼ 2.02 Hz, 1H), 7.77 (d, J ¼ 1.10 Hz, 1H), 7.74
(d, J ¼ 0.96 Hz, 1H), 7.38 (d, J ¼ 8.11 Hz, 2H), 7.28 (dd,
J1 ¼ 2.47 Hz, J2 ¼ 13.89 Hz, 1H), 6.94 (dd, J1 ¼ 2.48 Hz,
J2 ¼ 9.15 Hz, 1H), 6.88 (t, J ¼ 9.06 Hz, 1H), 5.05 (m, 1H),
4.79 (d, J ¼ 4.40 Hz, 2H), 4.12 (t, J ¼ 9.21 Hz, 1H), 3.90 (dd,
J1 ¼ 6.05 Hz, J2 ¼ 9.35 Hz, 1H), 3.20 (t, J ¼ 4.74 Hz, 4H),
3.08 (t, J ¼ 4.74 Hz, 4H). MS (EI) m/z (%): 504 (Mþ, 52), 345
(100). Anal. Calcd for C22H22F2N6O4S: C, 52.38; H, 4.40; N,
16.66. Found: C, 52.65; H, 4.73; N, 16.57.
5.6.11. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(2-trifluoromethylphenylsulfonyl)piperazin-1-yl)phenyl)-
oxazolidin-2-one (12)
1
5.6.7. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(4-fluorophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (8)
Mp: 144e146 ꢀC. H NMR (CDCl3): d 8.14 (m, 1H), 7.92
(m, 2H), 7.70e7.80 (m, 3H), 7.30 (dd, J1 ¼ 2.47 Hz,
J2 ¼ 13.88 Hz, 1H), 6.95 (dd, J1 ¼ 2.88 Hz, J2 ¼ 8.80 Hz,
1H), 6.87 (t, J ¼ 8.93 Hz, 1H), 5.05 (m, 1H), 4.79 (m, 2H),
4.12 (t, J ¼ 9.21 Hz, 1H), 3.90 (dd, J1 ¼ 6.19 Hz,
J2 ¼ 9.49 Hz, 1H), 3.40 (t, J ¼ 4.82 Hz, 4H), 3.09 (t,
J ¼ 4.95 Hz, 4H). MS (EI) m/z (%): 554 (Mþ, 1), 256 (100).
Anal. Calcd for C23H22F4N6O4S: C, 49.82; H, 4.00; N,
15.16. Found: C, 49.92; H, 3.96; N, 15.06.
Mp: 220e222 ꢀC. 1H NMR (CDCl3): d 7.78e7.83 (m, 2H),
7.77 (d, J ¼ 0.96 Hz, 1H), 7.74 (d, J ¼ 1.10 Hz, 1H), 7.30 (dd,
J1 ¼ 2.26 Hz, J2 ¼ 13.91 Hz, 1H), 7.22e7.27 (m, 2H), 6.95
(dd, J1 ¼ 2.34 Hz, J2 ¼ 8.94 Hz, 1H), 6.90 (t, J ¼ 8.74 Hz,
1H), 5.05 (m, 1H), 4.78 (d, J ¼ 4.13 Hz, 2H), 4.12 (t,
J ¼ 9.14 Hz, 1H), 3.88 (dd, J1 ¼ 6.05 Hz, J2 ¼ 9.35 Hz, 1H),
3.20 (t, J ¼ 4.40 Hz, 4H), 3.12 (t, J ¼ 4.68 Hz, 4H). MS (EI)
m/z (%): 504 (Mþ, 51), 56 (100). Anal. Calcd for
C22H22F2N6O4S: C, 52.38; H, 4.40; N, 16.66. Found: C,
52.57; H, 4.59; N, 16.34.
5.6.12. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(3-trifluoromethylphenylsulfonyl)piperazin-1-yl)phenyl)-
oxazolidin-2-one (13)
1
Mp: 202e204 ꢀC. H NMR (CDCl3): d 8.03 (s, 1H), 7.98
5.6.8. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(2,4-difluorophenylsulfonyl)piperazin-1-yl)phenyl)-
oxazolidin-2-one (9)
(d, J ¼ 8.06 Hz, 1H), 7.90 (d, J ¼ 8.06 Hz, 1H), 7.70e7.80
(m, 4H), 6.94 (dd, J1 ¼ 2.36 Hz, J2 ¼ 8.97 Hz, 1H), 6.86 (t,
J ¼ 8.94 Hz, 1H), 5.05 (m, 1H), 4.79 (d, J ¼ 4.20 Hz, 2H),
4.10 (t, J ¼ 9.21 Hz, 1H), 3.89 (dd, J1 ¼ 6.21 Hz,
J2 ¼ 9.57 Hz, 1H), 3.10e3.22 (m, 8H). MS (EI) m/z (%):
554 (Mþ, 49), 345 (100). Anal. Calcd for C23H22F4N6O4S:
C, 49.82; H, 4.00; N, 15.16. Found: C, 49.86; H, 4.20; N,
14.92.
1
Mp: 224e226 ꢀC. H NMR (CDCl3): d 7.88 (m, 1H), 7.78
(d, J ¼ 0.96 Hz, 1H), 7.74 (d, J ¼ 0.96 Hz, 1H), 7.30 (dd,
J1 ¼ 2.47 Hz, J2 ¼ 13.75 Hz, 1H), 7.96e7.06 (m, 2H), 6.94
(dd, J1 ¼ 2.06 Hz, J2 ¼ 8.80 Hz, 1H), 6.87 (t, J ¼ 8.94 Hz,
1H), 5.05 (m, 1H), 4.78 (m, 2H), 4.12 (t, J ¼ 9.07 Hz, 1H),
3.85 (dd, J1 ¼ 6.05 Hz, J2 ¼ 9.34 Hz, 1H), 3.34 (t,
J ¼ 4.88 Hz, 4H), 3.10 (t, J ¼ 4.88 Hz, 4H). MS (EI) m/z
(%): 522 (Mþ, 55), 345 (100). Anal. Calcd for C22H22F2N6O4-
S.CH3OH: C, 49.82; H, 4.54; N, 15.15. Found: C, 49.72; H,
4.22; N, 15.39.
5.6.13. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(4-trifluoromethylphenylsulfonyl)piperazin-1-yl)phenyl)-
oxazolidin-2-one (14)
Mp: 245e247 ꢀC. 1H NMR (CDCl3):
d 7.92 (d,
5.6.9. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(4-tolylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-2-one
(10)
J ¼ 8.25 Hz, 2H), 7.83 (d, J ¼ 8.39 Hz, 2H), 7.77 (d,
J ¼ 1.10 Hz, 1H), 7.74 (d, J ¼ 1.10 Hz, 1H), 7.28 (dd,
J1 ¼ 2.34 Hz, J2 ¼ 13.88 Hz, 1H), 6.94 (dd, J1 ¼ 2.20 Hz,
J2 ¼ 9.90 Hz, 1H), 6.86 (t, J ¼ 8.95 Hz, 1H), 5.05 (m, 1H),
4.80 (d, J ¼ 4.13 Hz, 2H), 4.10 (t, J ¼ 9.21 Hz, 1H), 3.89
(dd, J1 ¼ 6.19 Hz, J2 ¼ 9.49 Hz, 1H), 3.20 (t, J ¼ 4.75 Hz,
4H), 3.10 (t, J ¼ 4.75 Hz, 4H). MS (EI) m/z (%): 554 (Mþ,
40), 56 (100). Anal. Calcd for C23H22F4N6O4S: C, 49.82; H,
4.00; N, 15.16. Found: C, 49.90; H, 3.99; N, 15.02.
Mp: 195e198 ꢀC. 1H NMR (CDCl3):
d 7.77 (d,
J ¼ 0.92 Hz, 1H), 7.76 (d, J ¼ 1.06 Hz, 1H), 7.64 (m, 2H),
7.33 (m, 3H), 7.27 (dd, J1 ¼ 2.52 Hz, J2 ¼ 13.96 Hz, 1H),
6.92 (dd, J1 ¼ 2.37 Hz, J2 ¼ 8.85 Hz, 1H), 6.86 (t,
J ¼ 8.85 Hz, 1H), 5.04 (m, 1H), 4.76 (m, 2H), 4.10 (t,
J ¼ 9.16 Hz, 1H), 3.86 (dd, J1 ¼ 6.03 Hz, J2 ¼ 9.38 Hz, 1H),

1142
H. Fan et al. / European Journal of Medicinal Chemistry 42 (2007) 1137e1143
5.6.14. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(2-nitrophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (15)
J1 ¼ 1.34 Hz, J2 ¼ 3,69 Hz, 1H), 7.30 (dd, J1 ¼ 2.52 Hz,
J2 ¼ 13.93 Hz, 1H), 7.17 (dd, J1 ¼ 3.86 Hz, J2 ¼ 5.03 Hz,
1H), 6.95 (dd, J1 ¼ 2.43 Hz, J2 ¼ 9.32 Hz, 1H), 6.88 (t,
J ¼ 8.90 Hz, 1H), 5.05 (m, 1H), 4.78 (d, J ¼ 3.86 Hz, 2H),
4.12 (t, J ¼ 9.15 Hz, 1H), 3.90 (dd, J1 ¼ 6.21 Hz,
J2 ¼ 9.40 Hz, 1H), 3.24 (t, J ¼ 4.87 Hz, 4H), 3.14 (t,
J ¼ 4.87 Hz, 4H). MS (EI) m/z (%): 492 (Mþ, 1), 345 (100).
Anal. Calcd for C22H21FN6O4S2: C, 48.77; H, 4.30; N,
17.06. Found: C, 48.72; H, 4.42; N, 17.39.
Mp: 197e199 ꢀC. 1H NMR (CDCl3):
d 8.63 (t,
J ¼ 2.33 Hz, 1H), 8.45 (m, 1H), 8.12 (m, 1H), 7.74e7.82
(m, 3H), 7.28 (dd, J1 ¼ 2.48 Hz, J2 ¼ 13.98 Hz, 1H), 6.94
(dd, J1 ¼ 2.36 Hz, J2 ¼ 8.97 Hz, 1H), 6.86 (t, J ¼ 8.94 Hz,
1H), 5.05 (m, 1H), 4.78 (d, J ¼ 4.12 Hz, 2H), 4.12 (t,
J ¼ 9.08 Hz, 1H), 3.89 (dd, J1 ¼ 6.05 Hz, J2 ¼ 9.48 Hz, 1H),
3.25 (m, 4H), 3.13 (m, 4H). MS (EI) m/z (%): 531 (Mþ, 6),
57 (100). Anal. Calcd for C22H22FN7O6S: C, 49.71; H, 4.17;
N, 18.45. Found: C, 49.43; H, 4.46; N, 18.26.
5.6.19. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(3-aminophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (20)
5.6.15. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(3-nitrophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (16)
Mp: 165e167 ꢀC. 1H NMR (DMSO-d6): d 8.15 (d,
J ¼ 0.96 Hz, 1H), 7.75 (d, J ¼ 0.96 Hz, 1H), 7.37 (dd,
J1 ¼ 2.41 Hz, J2 ¼ 14.64 Hz, 1H), 7.28 (t, J ¼ 7.91 Hz, 1H),
7.10 (dd, J1 ¼ 2.52 Hz, J2 ¼ 8.93 Hz, 1H), 7.04 (t,
J ¼ 9.26 Hz, 1H), 6.93 (t, J ¼ 2.01 Hz, 1H), 6.84 (m, 2H),
5.10 (m, 1H), 4.81 (d, J ¼ 5.08 Hz, 2H), 4.19 (t,
J ¼ 9.21 Hz, 1H), 3.81 (dd, J1 ¼ 5.77 Hz, J2 ¼ 9.42 Hz, 1H),
3.02 (m, 8H). MS (EI) m/z (%): 501 (Mþ, 4), 56 (100).
Anal. Calcd for C22H24FN7O4S.1/2H2O: C, 51.71; H, 4.90;
N, 19.19. Found: C, 51.95; H, 4.92; N, 18.87.
Mp: 197e199 ꢀC. 1H NMR (CDCl3): d 8.63 (t, J ¼ 1.81 Hz,
1H), 8.49 (m, 1H), 8.11 (m, 1H), 7.80 (t, J ¼ 7.97 Hz, 1H), 7.77
(d, J ¼ 0.88 Hz, 1H), 7.73 (d, J ¼ 0.88 Hz, 1H), 7.30 (m, 1H),
6.94 (dd, J1 ¼ 2.47 Hz, J2 ¼ 8.85 Hz, 1H), 6.87 (t, J ¼ 8.91 Hz,
1H), 5.04 (m, 1H), 4.79 (d, J ¼ 4.02 Hz, 2H), 4.10
(t, J ¼ 9.15 Hz, 1H), 3.90 (dd, J1 ¼ 6.06 Hz, J2 ¼ 9.29 Hz, 1H),
3.26 (t, J ¼ 4.45 Hz, 4H), 3.12 (t, J ¼ 4.80 Hz, 4H). MS (EI)
m/z (%): 531 (Mþ, 22), 345 (100). Anal. Calcd for
C22H22FN7O6S: C, 49.71; H, 4.17; N, 18.45. Found: C, 49.87;
H, 4.16; N, 18.12.
5.7. Pharmacology
5.6.16. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(4-nitrophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (17)
5.7.1. In vitro
The in vitro antibacterial activity (MIC) of the compounds
2e20 against Gram-positive bacteria was tested as growth in-
hibition with the use of the microdilution broth method ac-
cording to NCCLS [16]. The compounds were dissolved in
20% water in DMSO to prepare a stock solution in which
the concentration of the compounds is 1920 mg/mL. Serial
twofold dilutions were prepared from the stock solution in
sterile water or Mueller-Hinton (MH) agar medium to provide
the concentration of 8, 4, 2, 1, 0.5, 0.25, 0.125, 0.06, 0.03,
0.015, 0.008, 0.004, 0.002, 0.001 and 0.0005 mg/mL.
1
Mp: 222e224 ꢀC. H NMR (CDCl3): d 8.40 (m, 2H), 7.98
(m, 2H), 7.74 (s, 1H), 7.77(s, 1H), 7.28 (dd, J1 ¼ 2.55 Hz,
J2 ¼ 14.19 Hz, 1H), 6.94 (dd, J1 ¼ 3.03 Hz, J2 ¼ 9.68 Hz,
1H), 6.86 (t, J ¼ 9.00 Hz, 1H), 5.05 (m, 1H), 4.79 (d,
J ¼ 4.21 Hz, 2H), 4.10 (t, J ¼ 9.10 Hz, 1H), 3.90 (dd,
J1 ¼ 6.16 Hz, J2 ¼ 9.11 Hz, 1H), 3.24 (t, J ¼ 4.40 Hz, 4H),
3.12 (t, J ¼ 4.75 Hz, 4H). MS (EI) m/z (%): 531 (Mþ, 11),
56 (100). Anal. Calcd for C22H22FN7O6S: C, 49.71; H, 4.17;
N, 18.45. Found: C, 49.70; H, 4.23; N, 18.16.
5.6.17. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(4-cyanophenylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (18)
5.7.2. In vivo
KunMing mice weighing 18e20 g were used in the study
with five mice in each group. Lethal systemic infection was
caused in the mice by injecting intraperitoneally MLD inocu-
lum of MRSA BAA-42, MSSA 04-5 and MRSE 03427, the
compounds were administered orally immediately and 4 h
post-infection. The ED50 was calculated by the Bliss method
[17,18] on day 7 post-infection.
1
Mp: 237e239 ꢀC. H NMR (CDCl3): d 7.90 (m, 4H), 7.78
(s, 1H), 7.74 (s, 1H), 7.28 (dd, J1 ¼ 2.34 Hz, J2 ¼ 14.15 Hz,
1H), 6.94 (m, 1H), 6.86 (t, J ¼ 8.80 Hz, 1H), 5.04 (m, 1H),
4.78 (d, J ¼ 3.85 Hz, 2H), 4.10 (t, J ¼ 8.93 Hz, 1H), 3.90
(dd, J1 ¼ 5.77 Hz, J2 ¼ 8.93 Hz, 1H), 3.20 (m, 4H), 3.10 (m,
4H). MS (EI) m/z (%): 511 (Mþ, 46), 345 (100). Anal. Calcd
for C23H22FN7O6S: C, 54.00; H, 4.33; N, 19.17. Found: C,
54.06; H, 4.30; N, 19.05.
Acknowledgements
5.6.18. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(thiophen-2-ylsulfonyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (19)
The authors are thankful for the financial support from the
National Natural Science Foundation of China (Project
20272067). We would also like to thank Chinese Academy
of Sciences for funding (KSCX2-SW-220).
1
Mp: 202e204 ꢀC. H NMR (CDCl3): d 7.77 (s, 1H), 7.74
(s, 1H), 7.65 (dd, J1 ¼ 1.34 Hz, J2 ¼ 5.04 Hz, 1H), 7.57 (dd,

H. Fan et al. / European Journal of Medicinal Chemistry 42 (2007) 1137e1143
1143
[11] C. Yingjie, Y. Yushe, J. Ruyun, Z.H. Shuhua, Bioorg. Med. Chem. Lett.
13 (14) (2003) 2311e2313.
References
[12] O.A. Phillips, E.E. Udo, A.A.M. Ali, N. Al-Hassawi, Bioorg. Med.
Chem. 11 (1) (2003) 35e41.
[1] M.A. Pfaller, R.N. Jones, G.V. Doern, H.S. Sader, K.C. Kugler,
M.L. Beach, Diagn. Microbiol. Infect. Dis. 33 (4) (1999) 283e297.
[2] P. Abi-Hanna, A.L. Frank, J.P. Quinn, S. Kelkar, P.C. Schreckenberger,
M.K. Hayden, J.F. Marcinak, Clin. Infect. Dis. 30 (3) (2000) 630e631.
[3] P. Collignon, J. Infect. Dis. 179 (6) (1999) 1592.
[13] R.R. Ramsay, M.B. Gravestock, Mini Rev. Med. Chem. 3 (2) (2003)
129e136.
[14] S.J. Brickner, D.K. Hutchinson, M.R. Barbachyn, P.R. Manninen,
D.A. Ulanowicz, S.A. Garmon, K.C. Grega, S.K. Hendges, D.S. Toops,
C.W. Ford, G.E. Zurenko, J. Med. Chem. 39 (3) (1996) 673e679.
[15] M.J. Genin, D.A. Allwine, D.J. Anderson, M.R. Barbachyn,
D.E. Emmert, S.A. Garmon, D.R. Graber, K.C. Grega, J.B. Hester,
D.K. Hutchinson, J. Morris, R.J. Reischer, C.W. Ford, G.E. Zurenko,
J.C. Hamel, R.D. Schaadt, D. Stapert, B.H. Yagi, J. Med. Chem. 43 (5)
(2000) 953e970.
[4] J. Merlino, M. Leroi, R. Bradbury, D. Veal, C. Harbour, J. Clin. Micro-
biol. 38 (2000) 2378e2380.
[5] B.D. Cookson, Infect. Control Hosp. Epidemiol. 21 (6) (2000) 398e403.
[6] D. Clemett, A. Markham, Drugs 59 (4) (2000) 815e827.
[7] S.M. Swaney, H. Aoki, M.C. Ganoza, D.L. Shinabarger, Antimicrob.
Agents Chemother. 42 (1998) 3251e3255 and references cited therein.
[8] H. Aoki, L. Ke, S.M. Poppe, T.J. Poel, E.A. Weaver, R.C. Gadwood,
R.C. Thomas, D.L. Shinabarger, M.C. Ganoza, Antimicrob. Agents Che-
mother. 46 (2002) 1080e1085 and references cited therein.
[9] S. Tsirodas, H.S. Gold, G. Sakoulas, G.M. Eliopoulas, C. Wennerstein,
L. Venkataraman, R.C. Moellering Jr., M.J. Ferro, Lancet 358 (2001) 207e208.
[10] A.P. Johnson, L. Tysall, M.W. Stockdale, N. Woodford, M.E. Kaufmann,
M. Warner, D.M. Livermoore, F. Asboth, F.J. Alleberger, Eur. J. Clin. Mi-
crobiol. Infect. Dis. 21 (2002) 751e754.
[16] National Committee for Clinical Laboratory Standards, Methods for Di-
lution Antimicrobial Susceptibility Tests for Bacteria that Grows Aerobi-
cally, fourth ed. National Committee for Clinical Laboratory Standards,
Villanova, PA, USA, 1997 Approved standards: NCCLS Document
M7-A4.
[17] C.I. Bliss, Science 79 (1934) 38e39.
[18] C.I. Bliss, Ann. Appl. Biol. 22 (1935) 134e167.