Synthesis and biological evaluation of new N-linked 5-triazolylmethyl oxazolidinones

Article abstract of DOI:10.1016/j.ejmech.2007.09.010

A new series of oxazolidinones bearing N-linked 5-triazolylmethyl group have been synthesized and their in vitro antibacterial activities (MIC) were evaluated against a spectrum of resistant and susceptible Gram-positive organisms. Some of the analogues in this series displayed activity superior to linezolid and vancomycin. Furthermore, in vivo efficacies and pharmacokinetic properties of the selected compounds were also disclosed herein; the selected compounds showed reasonable bioavailability as well as in vivo efficacy comparable to that of linezolid.

Full text of DOI:10.1016/j.ejmech.2007.09.010

Available online at www.sciencedirect.com
European Journal of Medicinal Chemistry 43 (2008) 1706e1714
http://www.elsevier.com/locate/ejmech
Original article
Synthesis and biological evaluation of new N-linked
5-triazolylmethyl oxazolidinones
Houxing Fan a, Yilang Chen a, Zhiteng Jiang a, Shuhua Zhang b,
Dafang Zhong a, Ruyun Ji a, Yushe Yang a,
*
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 19 May 2007; received in revised form 7 September 2007; accepted 13 September 2007
Available online 26 September 2007
Abstract
A new series of oxazolidinones bearing N-linked 5-triazolylmethyl group have been synthesized and their in vitro antibacterial activities
(MIC ) were evaluated against a spectrum of resistant and susceptible Gram-positive organisms. Some of the analogues in this series displayed
activity superior to linezolid and vancomycin. Furthermore, in vivo efficacies and pharmacokinetic properties of the selected compounds were
also disclosed herein; the selected compounds showed reasonable bioavailability as well as in vivo efficacy comparable to that of linezolid.
Ó 2007 Elsevier Masson SAS. All rights reserved.
Keywords: Oxazolidinone; Linezolid; Antibacterial agents; Gram-positive organisms
1. Introduction
isolates of VREF and S. aureus have been reported recently
[9,10]. This unexpected early development of resistance
emphasizes the need for further exploration of features of
oxazolidinone series to overcome these issues.
Infections due to Gram-positive bacteria such as methicillin-
resistant Staphylococcus aureus (MRSA), vancomycin-resistant
Enterococcus faecium (VREF ), and penicillin-resistant Strepto-
coccus 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 important suscep-
tible 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 an-
tibiotics may be unavoidable, some linezolid-resistant clinical
Phillips and co-workers recently reported that new 5-
triazolylmethyl oxazolidinones based on the replacement of
the 5-acetamidomethyl substituents with N-linked triazolyl,
exemplified by pH-027 (Fig. 2), demonstrated strong in vitro
activity [11]. Furthermore, we have found that the arylsulfonyl
oxazolidinones bearing N-linked 5-triazolylmethyl group such
as YX-10 (Fig. 2) demonstrated potent in vitro activities
(MIC ¼ 0.25e1 mg/mL against MSSA), but their in vivo activi-
ties (ED50 > 100 mg/kg) were not desirable, the inferior in
vivo potency may be due to their poor solubility in the vehicle
or suboptimal pharmacokinetic properties [12]. However, RBx
7644 (Fig. 2), 5-nitro-2-furyl attached to the ‘piperazinyl-
phenyl-oxazolidinone’ core structure of eperezolid (Fig. 1)
with a methylene linker, has successfully completed Phase I
clinical trial in UK [13]. It showed similar or superior activity
to linezolid against common Gram-positive pathogens, but
more potent antibacterial activity than linezolid against some
* Corresponding author. Tel.: þ86 21 50806600x3405; 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.2007.09.010

H. Fan et al. / European Journal of Medicinal Chemistry 43 (2008) 1706e1714
1707
Fig. 1. Structure of linezolid and eperezolid.
fastidious Gram-negative organisms (MIC90 ¼ 2 mg/mL) [14].
Based on these findings, we designed and synthesized a new se-
ries of oxazolidinones bearing N-linked 5-triazolylmethyl group
to find more potent oxazolidinone antibacterial agents with
greater water solubility and better pharmacokinetic profiles.
Here we report our efforts towards the synthesis and biological
evaluation (including in vitro, in vivo and pharmacokinetics) of
this series of compounds, resulting in the discovery of a promis-
ing drug candidate (compound 4e) with potent antibacterial
activity and reasonable bioavailability.
vancomycin, with MIC values of 0.125 mg/mL against S. au-
reus ATCC 25923, 0.06 mg/mL against S. aureus ATCC
29213, 0.06e0.25 mg/mL against MSSA, 0.06e4 mg/mL
against MRSA, 0.03e0.125 mg/mL against Streptococcus
pneumoniae, 0.25e0.5 mg/mL against Enterococcus faecalis.
It identified the N-linked-5-triazoylmethyl group as structural
alternative for strong antibacterial in the oxazolidinone class.
Compounds 2ae2h, substituted phenyl ring attached to the
‘piperazinyl-phenyl-oxazolidinone’ core structure with a meth-
ylene linker, displayed potent antibacterial activity. Substitu-
tion on the phenyl ring with eNO2 or eCHO also showed
good antibacterial activity, and the substituted position was
relevant to the activity, reducing eNO2 group to electron-
donating group eNH2 resulted in enhancement of activity.
The replacement of substituted phenyl ring with 2-pyridyl
3a and 3-pyridyl 3b resulted in superior activity to linezolid,
while 4-pryidyl derivative 3c led to inferior activity to line-
zolid. In vitro rank order being 2-pyridyl > 3-pyridyl > 4-
pyridyl, the activity decreased with the increment of distance
between the nitrogen atom of pyridyl ring and the methylene
linker. It may be explained that compound 3a has a stronger
binding affinity with the receptor than that of compounds 3b
and 3c.
2. Chemistry
Synthesis of these novel compounds was carried out in
a straightforward manner. Compound 1 was synthesized
from the readily available starting materials piperazine and
3,4-difluoronitro-benzene according to the known method
[12,15,16] in several steps. As shown in Scheme 1, compound
1 readily underwent LeuckarteWallach reaction with the cor-
responding substituted formaldehyde in DMF as solvent at
100 ꢀC afforded compounds 2ae2c, 2e, 2g, 3ae3c, 4ae4d
and 5ae5e in moderate to good yields. Treatment of com-
pound 1 with 2-chloromethyl-5-nitrofuran [17] and triethyl-
amine in CH3CN gave 4e in 71% yield. Further chemical
transformations involving treatment of 2c, 2e and 2g with
10% palladium on carbon in CH2Cl2 and CH3OH under hydro-
gen afforded 2d, 2f and 2h, respectively, in moderate to good
yields. All the newly synthesized compounds were character-
ized by spectroscopic data (1H NMR, IR, EI-MS or ESI-MS),
mp and elemental analysis.
The replacement of substituted phenyl ring with 2-furyl 4a
and 3-furyl 4b resulted in superior activity to linezolid. Inter-
estingly, compound 4b displayed more potent activity than 4a,
it suggested that the linked position was relevant to the activ-
ity. Replacing 2-furyl with electron-donating group eCH3 (4c)
or weak electron-withdrawing group eCl (4d) led to a slight
decrease in activity, while strong electron-withdrawing group
eNO2 (4e) led to a great increase in activity.
Substitution with 2-thienyl 5a and 3-thienyl 5b also gave
compounds with superior activity to the reference compounds,
however, similar trend for furyl series was not observed in the
thienyl series, 2-thienyl derivative 5a was more potent than
3-thienyl derivative 5b. Substitution of 2-thienyl ring with
electron-donating group eCH3 (5d and 5e) or weak electron-
withdrawing group eBr (5c) on the different position resulted
in activity inferior to unsubstituted-thienyl derivative 5a.
3. Result and discussion
The result of in vitro antibacterial activities against a spec-
trum of resistant and susceptible Gram-positive organisms is
summarized in Table 1. It clearly showed that most of the
compounds in this series displayed good antibacterial activi-
ties, especially compound 4e, the most potent one, exhibited
more potent antibacterial activity than linezolid and
Fig. 2. Structure of pH-027, YX-10 and RBx 7644.

1708
H. Fan et al. / European Journal of Medicinal Chemistry 43 (2008) 1706e1714
Scheme 1. (a) RCHO, HCO2H, DMF, 100 ꢀC, 2e24 h; (b) 10% Pd/C, H2, CH2Cl2/MeOH, rt, 2 h; (c) 2-chloromethyl-nitrofuran, Et3N, CH3CN, 50 ꢀC, 6 h.
The in vivo activities of compounds 2e, 2h, 4a and 4b were
tested in mice mode (see Table 2). Compounds 4b
(ED50 ¼ 7.47 mg/kg) and 2e (ED50 ¼ 7.87 mg/kg) displayed
oral efficacies slightly superior than that for linezolid
(ED50 ¼ 8.45 mg/kg), while compounds 4b(ED50 ¼ 6.99 mg/kg)
and 2h (ED50 ¼ 6.73 mg/kg) displayed intravenous efficacies
slightly superior than that for linezolid (ED50 ¼ 8.45 mg/kg),
whereas compound 4awas inferior to linezolidand vancomycin.
Table 1
MIC ranges (mg/mL) of new oxazolidinones against Gram-positive clinical isolates
O
F
O
N
N
N
R
N
N
N
Compounds
R
S.a.a
MSSAb n ¼ 5
0.5e1
1e2
0.125e2
0.125e0.5
0.06e1
MRSAc n ¼ 3
0.125e1
0.25e2
1e4
S.p.d [5]
E.f.e [5]
2a
2b
3-CHOePh
4-CHOePh
2-NO2ePh
0.25
0.008
0.125
0.125
0.03
0.25
0.5
1
1
1
2
2c
2d
1e2
0.5e1
0.5
2 to >8
1e2
2-NH2ePh
3-NO2ePh
0.5e4
0.5e4
0.5e4
>8
2e
0.5e1
0.5e2
8 to >8
0.25e1
0.5e1
1e4
2f
2g
3-NH2ePh
4-NO2ePh
0.25e1
0.5e1
4 to >8
0.5
0.5 to >8
0.06e0.5
0.125e0.5
0.125e1
0.5e1
2h
3a
4-NH2ePh
2-Pyridyl
0.125
0.125
0.125
0.5
0.5e4
0.5e4
1e4
0.5e1
1
3b
3c
3-Pyridyl
4-Pyridyl
1e8
1e2
0.5
2e8
4a
4b
2-Furyl
3-Furyl
0.06
0.008
0.125
0.125
0.06
0.06
0.06
0.06
1
0.06e0.5
0.008e0.06
0.125e1
0.125e1
0.06e0.25
0.06e0.5
0.06e0.5
0.06e0.5
1e4
0.5e4
0.03e4
1e8
0.5e1
0.5e4
2 to >8
2e4
0.03e2
2
4c
4d
5-Me-furan-2-yl
5-Cl-furan-2-yl
5-NO2-furan-2-yl
2-Thienyl
1e4
1
4e
5a
0.06e4
0.06e4
1 to >8
0.5e4
4 to >8
4e8
0.03e0.125
0.06e0. 25
0.5
0.25e0.5
2e4
1 to >8
1e8
5b
5c
3-Thienyl
5-Br-thiophen-2-yl
3-Me-thiophen-2-yl
5-Me-thiophen-2-yl
0.5e1
4
5d
5e
4 to >8
4 to >8
1e2
0.125
0.5
0.125
0.06e8
0.5e2
0.125e1
2e8
1e2
1e2
Linezolid
Vancomycin
a
1e4
1e4
1e2
S.a. ¼ Staphylococcus aureus ATCC 29213.
b
c
d
e
MSSA ¼ Methicillin-susceptible Staphylococcus aureus.
MRSA ¼ Methicillin-resistant Staphylococcus aureus.
S.p. ¼ Streptococcus pneumoniae.
E.f ¼ Enterococcus faecalis.

H. Fan et al. / European Journal of Medicinal Chemistry 43 (2008) 1706e1714
1709
Table 2
In vivo efficacies of the selected compounds
linezolid. The result suggested that this series of oxazolidi-
nones bearing N-linked 5-triazolylmethyl group have potent
antibacterial activity and perfect pharmacokinetic profiles.
Further development of compound 4e as a promising drug can-
didate is on going in preclinical investigations.
a
ED50 (mg/kg)
Organism
Compound
Route
MRSA 05-2
2e
p.o.
i.v.
7.87 (5.24e21.81)
11.21 (7.30e18.99)
14.53 (9.72e34.78)
6.73 (4.47e10.79)
12.28 (8.25e24.67)
12.00 (7.65e27.95)
7.47 (5.21e15.41)
6.99 (4.48e19.90)
8.45 (5.65e14.26)
8.45 (5.65e14.26)
6.00 (3.83e13.96)
6.54 (3.89e21.87)
2h
p.o.
i.v.
5. Experimental
4a
p.o.
i.v.
4b
p.o.
i.v.
5.1. General
Linezolid
Vancomycin
p.o.
i.v.
All solvents used were of analytical grade (Sinopharm
Chemical Reagent Co., Ltd.). Melting points (uncorrected)
were determined on an X-4 melting point apparatus. 1H
NMR spectral data were recorded on a Varian Mercury-400
spectrometer, chemical shifts are given in parts per million
(d) values and coupling constants (J ) in Hertz. Infrared (IR)
spectra were recorded on a Nicolet FTIR-750 spectrometer.
EI-MS spectra were obtained on a Finnigan MAT 95 mass
spectrometer and ESI-MS spectra were obtained on a Kratos
MS 80 mass spectrometer. Elemental analysis was obtained
using a vario EL spectrometer. 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.
s.c.
i.v.
a
The amount of drug required after oral administration (mg/kg/day) to cure
50% of infected mice subjected to a lethal systemic infection. Numbers in
parentheses are 95% confidence ranges.
Compounds 2e, 2h, 4b and 4e were subjected to pharmaco-
kinetic performance assessment (Table 3). All of the selected
compounds have reasonable oral bioavailability (F ¼ 43.8e
102.6%). In a p.o. dose escalation study, a linear increase in
drug exposure was observed as indicated by AUC.
4. Conclusion
In conclusion, a new series of N-linked 5-triazolyl-methyl
substituted oxazolidinones were synthesized and evaluated
for microbiological activity against resistant and susceptible
Gram-positive organisms in vitro comparable to linezolid
and vancomycin. Most of them showed more potent or equiv-
alent activity to that of linezolid and vancomycin. Several
compounds from this series exhibited reasonable oral bioavail-
ability as well as in vivo efficacies comparable to that of
5.2. Preparation of compounds 2ae2h, 3ae3c,
4ae4e and 5ae5e
5.2.1. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(3-formylbenzyl)piperazin-1-yl)phenyl)-oxazolidin-
2-one (2a)
Compound 1 (383 mg, 1.0 mmol), isophthalaldehyde
(201 mg, 1.5 mmol) and formic acid (92 mg, 2.0 mmol)
Table 3
Pharmacokinetic parameters of the selected compounds
Cpa
Rtb
Dose (mg/kg)
CLg (mL/min/kg)
Fh (%)
c
Cmax (mg/mL)
d
Tmax (h)
e
t1/2b (h)
f
AUC0eN (mg h/mL)
2e
p.o.
p.o.
i.v.
10
50
10
10
50
10
10
50
10
10
50
10
3.24 ꢁ 0.68
10.77 ꢁ 2.15
n.c.i
1.40 ꢁ 0.80
2.30 ꢁ 0.50
n.a.j
2.36 ꢁ 0.56
5.34 ꢁ 2.56
2.95 ꢁ 0.46
3.40 ꢁ 0.24
4.67 ꢁ 0.98
3.52 ꢁ 0.52
2.76 ꢁ 0.52
8.60 ꢁ 3.15
2.95 ꢁ 0.46
1.51 ꢁ 0.55
1.66 ꢁ 0.48
1.18 ꢁ 0.32
16.10 ꢁ 5.98
74.50 ꢁ 21.90
26.16 ꢁ 8.24
3.10 ꢁ 0.46
11.70 ꢁ 4.99
11.30 ꢁ 3.58
6.98 ꢁ 2.73
54.4 ꢁ 8.00
49.00 ꢁ 17.50
23.90 ꢁ 4.24
10.50 ꢁ 2.50
8.86 ꢁ 3.03
6.98 ꢁ 2.73
18.00 ꢁ 4.33
16.80 ꢁ 3.17
16.17 ꢁ 4.83
61.5
n.c.
n.a.
43.8
n.c.
n.a.
62.7
n.c.
n.a.
102.6
n.c.
n.a.
p.o.
p.o.
i.v.
1.20 ꢁ 0.47
2.32 ꢁ 0.77
n.c.
0.75 ꢁ 0.29
1.00 ꢁ 0.00
n.a.
2h
4b
4e
18.10 ꢁ 6.50
7.08 ꢁ 1.07
p.o.
p.o.
i.v.
3.04 ꢁ 0.12
10.70 ꢁ 3.00
n.c.
0.88 ꢁ 0.25
1.90 ꢁ 1.00
n.a.
16.40 ꢁ 3.50
85.80 ꢁ 20.00
26.20 ꢁ 8.20
19.40 ꢁ 10.40
139.00 ꢁ 48.00
18.9 ꢁ 9.20
p.o.
p.o.
i.v.
5.44 ꢁ 1.28
16.9 ꢁ 2.30
n.c.
0.25 ꢁ 0.00
0.50 ꢁ 0.27
n.a.
a
b
c
d
e
f
Compound.
Route.
Maximum plasma concentration.
Time at which Cmax achieved.
Elimination half-life.
Area under the concentrationetime curve.
Clearance.
g
h
i
Absolute oral bioavailability assuming linear pharmacokinetics.
n.c. ¼ not calculated.
j
n.a. ¼ not applicable.

1710
H. Fan et al. / European Journal of Medicinal Chemistry 43 (2008) 1706e1714
were placed in dry DMF (5 mL) and heated to 100 ꢀC under
N2 for 16 h. The reaction was cooled and partitioned between
CH2Cl2 (30 mL) and saturated NaHCO3 solution (200 mL).
The aqueous layer was extracted with CH2Cl2 (2 ꢂ 25 mL)
and the combined extracts washed with water (200 mL) and
brine (100 mL), and dried over Na2SO4. Removal of the sol-
vent gave a residue which was chromatographed with
CH2Cl2/MeOH (50:1) to afford 2a (270 mg, 58%) as a white
(Mþ, 25), 304 (100). Anal. Calcd for C23H24FN7O4: C,
57.37; H, 5.02; N, 20.36. Found: C, 57.05; H, 4.96; N, 20.11.
5.2.4. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(2-aminobenzyl)piperazin-1-yl)phenyl)-oxazolidin-
2-one (2d)
A mixture of compound 2c (200 mg, 0.41 mmol) and 10%
palladium on carbon (40 mg) in CH2Cl2 (15 mL) and MeOH
(15 mL) was stirred under hydrogen (balloon) for 2 h. The
mixture was then filtered through diatomaceous earth, the filter
cake was washed with CH2Cl2 (30 mL), and the combined fil-
trates were concentrated, the residue was purified by silica gel
column chromatography eluting with CH2Cl2/MeOH (25:1) to
afford compound 2d (146 mg, 78%) as a white solid, mp 201e
1
solid, mp 120e121 ꢀC. H NMR (CDCl3): d 10.03 (s, 1H),
7.87 (s, 1H), 7.76e7.82 (m, 2H), 7.74 (s, 1H), 7.64 (d,
J ¼ 7.50 Hz, 1H), 7.50 (t, J ¼ 7.59 Hz, 1H), 7.27 (dd,
J1 ¼ 2.47 Hz, J2 ¼ 14.18 Hz, 1H), 6.95 (dd, J1 ¼ 2.47 Hz,
J2 ¼ 8.88 Hz, 1H), 6.88 (t, J ¼ 8.78 Hz, 1H), 5.03 (m, 1H),
4.78 (m, 2H), 4.12 (t, J ¼ 9.15 Hz, 1H), 3.88 (dd,
J1 ¼ 6.13 Hz, J2 ¼ 9.42 Hz, 1H), 3.64 (s, 2H), 3.12 (t,
J ¼ 4.76 Hz, 4H), 2.64 (t, J ¼ 4.76 Hz, 4H). IR (KBr pellet,
cmꢃ1): 3429, 2947, 2837, 1751, 1703, 1518, 1412, 1225,
1113, 750. MS (EI) m/z (%): 464 (Mþ, 100). Anal. Calcd
for C24H25FN6O3$1/2CH3OH: C, 61.24; H, 5.66; N, 17.49.
Found: C, 61.35; H, 5.37; N, 17.79.
1
202 ꢀC. H NMR (DMSO-d6): d 8.16 (d, J ¼ 0.78 Hz, 1H),
7.74 (d, J ¼ 0.78 Hz, 1H), 7.36 (dd, J1 ¼ 2.40 Hz,
J2 ¼ 14.96 Hz, 1H), 7.08 (dd, J1 ¼ 2.25 Hz, J2 ¼ 9.10 Hz,
1H), 7.02 (t, J ¼ 9.29 Hz, 1H), 6.95 (t, J ¼ 7.34 Hz, 2H),
6.62 (d, J ¼ 8.02 Hz, 1H), 6.49 (t, J ¼ 6.85 Hz, 1H), 5.10
(m, 1H), 4.80 (d, J ¼ 5.09 Hz, 2H), 4.18 (t, J ¼ 9.19 Hz,
1H), 3.83 (dd, J1 ¼ 5.77 Hz, J2 ¼ 9.19 Hz, 1H), 3.44 (br s,
2H), 3.36 (s, 2H), 2.96 (br s, 4H), 2.48 (br s, 4H). IR (KBr pel-
let, cmꢃ1): 3369, 3288, 2951, 2823, 1743, 1618, 1514, 1423,
1336, 1219, 1070, 748. MS (EI) m/z (%): 451 (Mþ, 17), 106
(100). Anal. Calcd for C23H26FN7O2: C, 61.18; H, 5.80; N,
21.72. Found: C, 61.16; H, 5.72; N, 21.92.
5.2.2. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(4-formylbenzyl)piperazin-1-yl)phenyl)-oxazolidin-
2-one (2b)
The title compound was prepared according to the similar
procedure for 2a utilizing terephthalaldehyde instead of iso-
phthalaldehyde, chromatography using CH2Cl2/MeOH (50:1)
afforded 2b (348 mg, 75%) as a white solid, mp 161e
162 ꢀC. 1H NMR (CDCl3): d 10.00 (s, 1H), 7.85 (d,
J ¼ 8.05 Hz, 2H), 7.78 (s, 1H), 7.74 (s, 1H), 7.53 (d,
J ¼ 8.05 Hz, 2H), 7.27 (dd, J1 ¼ 2.57 Hz, J2 ¼ 14.09 Hz,
1H), 6.95 (dd, J1 ¼ 2.38 Hz, J2 ¼ 8.78 Hz, 1H), 6.88 (t,
J ¼ 8.78 Hz, 1H), 5.04 (m, 1H), 4.78 (m, 2H), 4.12 (t,
J ¼ 9.15 Hz, 1H), 3.88 (dd, J1 ¼ 6.22 Hz, J2 ¼ 9.33 Hz, 1H),
3.64 (s, 2H), 3.08 (t, J ¼ 4.76 Hz, 4H), 2.64 (t, J ¼ 4.76 Hz,
4H). IR (KBr pellet, cmꢃ1): 3469, 3109, 2933, 2821, 1741,
1691, 1606, 1514, 1417, 1223, 1009, 754. MS (EI) m/z (%):
464 (Mþ, 91), 420 (100). Anal. Calcd for C24H25FN6O3$1/
2CH3OH: C, 61.24; H, 5.66; N, 17.49. Found: C, 61.51; H,
5.43; N, 17.83.
5.2.5. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(3-nitrobenzyl)piperazin-1-yl)phenyl)-oxazolidin-
2-one (2e)
The title compound was prepared according to the similar
procedure for 2a utilizing 3-nitrobenzaldehyde instead of iso-
phthalaldehyde, chromatography using CH2Cl2/MeOH (50:1)
afforded 2e (390 mg, 81%) as a yellow foam, mp 127e
1
128 ꢀC. H NMR (CDCl3): d 8.23 (t, J ¼ 1.77 Hz, 1H), 8.12
(m, 1H), 7.80 (d, J ¼ 0.98 Hz, 1H), 7.74 (d, J ¼ 0.98 Hz,
1H), 7.70 (d, J ¼ 7.43 Hz, 1H), 7.48 (t, J ¼ 7.92 Hz, 1H),
7.27 (dd, J1 ¼ 2.54 Hz, J2 ¼ 14.09 Hz, 1H), 6.94 (dd,
J1 ¼ 2.54 Hz, J2 ¼ 9.19 Hz, 1H), 6.88 (t, J ¼ 8.90 Hz, 1H),
5.05 (m, 1H), 4.87 (m, 2H), 4.12 (t, J ¼ 9.10 Hz, 1H), 3.88
(dd, J1 ¼ 6.06 Hz, J2 ¼ 9.39 Hz, 1H), 3.66 (s, 2H), 3.06 (t,
J ¼ 4.70 Hz, 4H), 2.65 (t, J ¼ 4.30 Hz, 4H). IR (KBr pellet,
cmꢃ1): 3124, 2939, 2818, 1741, 1518, 1421, 1348, 1227,
1194, 1014, 798, 731. MS (EI) m/z (%): 481 (Mþ, 100).
Anal. Calcd for C23H24FN7O4: C, 57.37; H, 5.02; N, 20.36.
Found: C, 57.43; H, 4.98; N, 20.46.
5.2.3. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(2-nitrobenzyl)piperazin-1-yl)phenyl)-oxazolidin-
2-one (2c)
The title compound was prepared according to the similar
procedure for 2a utilizing 2-nitrobenzaldehyde instead of iso-
phthalaldehyde, chromatography using CH2Cl2/MeOH (50:1)
afforded 2c (240 mg, 50%) as a yellow foam, mp 136e
5.2.6. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(3-aminobenzyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (2f)
1
137 ꢀC. H NMR (CDCl3): d 7.82 (d, J ¼ 7.97 Hz, 1H), 7.78
(d, J ¼ 0.96 Hz, 1H), 7.74 (d, J ¼ 0.96 Hz, 1H), 7.56 (m,
2H), 7.42 (m, 1H), 7.27 (dd, J1 ¼ 2.33 Hz, J2 ¼ 14.15 Hz,
1H), 6.94 (dd, J1 ¼ 2.40 Hz, J2 ¼ 9.13 Hz, 1H), 6.87 (t,
J ¼ 8.92 Hz, 1H), 5.05 (m, 1H), 4.88 (m, 2H), 4.12
(t, J ¼ 9.13 Hz, 1H), 3.84e3.90 (m, 3H), 3.06 (br s, 4H),
2.60 (br s, 4H). IR (KBr pellet, cmꢃ1): 3124, 2827, 1736,
1518, 1452, 1336, 1240, 1134, 735. MS (EI) m/z (%): 481
The title compound was prepared according to the similar
procedure for 2d utilizing 2e instead of 2c, chromatography
using CH2Cl2/MeOH (25:1) afforded 2f (120 mg, 64%) as
a white solid, mp: 189e191 ꢀC. 1H NMR (DMSO-d6):
d 8.13 (d, J ¼ 0.78 Hz, 1H), 7.72 (d, J ¼ 0.78 Hz, 1H), 7.34
(dd, J1 ¼ 2.53 Hz, J2 ¼ 14.86 Hz, 1H), 7.07 (dd,
J1 ¼ 2.34 Hz, J2 ¼ 8.80 Hz, 1H), 6.99 (t, J ¼ 9.29 Hz, 1H),

H. Fan et al. / European Journal of Medicinal Chemistry 43 (2008) 1706e1714
1711
6.92 (t, J ¼ 7.63 Hz, 1H), 6.54 (d, J ¼ 1.77 Hz, 1H), 6.44 (m,
2H), 5.08 (m, 1H), 4.95 (br s, 2H), 4.80 (d, J ¼ 5.09 Hz, 2H),
4.17 (t, J ¼ 9.19 Hz, 1H), 3.83 (dd, J1 ¼ 5.77 Hz,
J2 ¼ 9.19 Hz, 1H), 3.36 (s, 2H), 2.96 (br s, 4H), 2.48 (br s,
4H). IR (KBr pellet, cmꢃ1): 3464, 3363, 2951, 2823, 1747,
1618, 1514, 1423, 1331, 1225, 1101, 775. MS (EI) m/z (%):
451 (Mþ, 33), 57 (100). Anal. Calcd for C23H26FN7O2: C,
61.18; H, 5.80; N, 21.72. Found: C, 61.10; H, 5.68; N, 21.72.
(dd, J1 ¼ 2.47 Hz, J2 ¼ 14.16 Hz, 1H), 7.18 (m, 1H), 6.94
(dd, J1 ¼ 2.75 Hz, J2 ¼ 8.94 Hz, 1H), 6.87 (t, J ¼ 8.94 Hz,
1H), 5.04 (m, 1H), 4.77 (m, 2H), 4.12 (t, J ¼ 9.14 Hz, 1H),
3.87 (dd, J1 ¼ 9.35 Hz, J2 ¼ 6.18 Hz, 1H), 3.75 (s, 2H), 3.08
(t, J ¼ 4.54 Hz, 4H), 2.72 (br s, 4H). IR (KBr pellet, cmꢃ1):
3433, 2953, 2808, 1743, 1518, 1452, 1242, 1134, 760. MS
(EI) m/z (%): 437 (Mþ, 6), 121 (100). Anal. Calcd for
C22H24FN7O2: C, 60.40; H, 5.53; N, 22.41. Found: C, 60.45;
H, 5.60; N, 22.28.
5.2.7. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(4-nitrobenzyl)piperazin-1-yl)phenyl)-oxazolidin-
2-one (2g)
5.2.10. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(pyridin-3-ylmethyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (3b)
The title compound was prepared according to the similar
procedure for 2a utilizing 4-nitrobenzaldehyde instead of iso-
phthalaldehyde, chromatography using CH2Cl2/MeOH (50:1)
afforded 2g (294 mg, 61%) as a yellow foam, mp 181e
The title compound was prepared according to the similar
procedure for 2a utilizing 3-pyridinecarboxaldehyde instead
of isophthalaldehyde, chromatography using CH2Cl2/MeOH
(50:1) afforded 3b (216 mg, 49%) as a white solid, mp
1
182 ꢀC. H NMR (CDCl3): d 8.18 (d, J ¼ 8.60 Hz, 2H), 7.80
1
(d, J ¼ 0.98 Hz, 1H), 7.75 (d, J ¼ 0.78 Hz, 1H), 7.54 (d,
J ¼ 8.61 Hz, 2H), 7.27 (dd, J1 ¼ 2.44 Hz, J2 ¼ 14.18 Hz,
1H), 6.95 (dd, J1 ¼ 2.64 Hz, J2 ¼ 8.90 Hz, 1H), 6.88 (t,
J ¼ 8.91 Hz, 1H), 5.05 (m, 1H), 4.78 (m, 2H), 4.13 (t,
J ¼ 9.19 Hz, 1H), 3.90 (dd, J1 ¼ 6.17 Hz, J2 ¼ 9.27 Hz, 1H),
3.66 (s, 2H), 3.08 (br s, 4H), 2.65 (br s, 4H). IR (KBr pellet,
cmꢃ1): 3444, 3111, 2935, 2823, 1741, 1599, 1516, 1483,
1419, 1346, 1222, 1200, 1009, 862, 739. MS (EI) m/z (%):
481 (Mþ, 99), 304 (100). Anal. Calcd for C23H24FN7O4: C,
57.37; H, 5.02; N, 20.36. Found: C, 57.52; H, 5.05; N, 20.54.
158e159 ꢀC. H NMR (CDCl3): d 8.57 (d, J ¼ 2.01 Hz, 1H),
8.52 (dd, J1 ¼ 1.64 Hz, J2 ¼ 4.75 Hz, 1H), 7.78 (d, J ¼
0.92 Hz, 1H), 7.74 (d, J ¼ 0.91 Hz, 1H), 7.71 (d,
J ¼ 8.68 Hz, 1H), 7.27 (m, 2H), 6.94 (dd, J1 ¼ 2.74 Hz,
J2 ¼ 8.96 Hz, 1H), 6.87 (t, J ¼ 9.06 Hz, 1H), 5.03 (m, 1H),
4.77 (m, 2H), 4.12 (t, J ¼ 9.06 Hz, 1H), 3.87 (dd,
J1 ¼ 6.22 Hz, J2 ¼ 9.33 Hz, 1H), 3.58 (s, 2H), 3.07 (t,
J ¼ 4.48 Hz, 4H), 2.64 (t, J ¼ 4.21 Hz, 4H). IR (KBr pellet,
cmꢃ1): 3441, 3116, 2816, 1741, 1518, 1404, 1323, 1223,
1122, 1009, 714. MS (EI) m/z (%): 437 (Mþ, 100). Anal.
Calcd for C22H24FN7O2: C, 60.40; H, 5.53; N, 22.41. Found:
C, 60.34; H, 5.53; N, 22.33.
5.2.8. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(4-aminobenzyl)piperazin-1-yl)phenyl)-oxazolidin-
2-one (2h)
5.2.11. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(pyridin-4-ylmethyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (3c)
The title compound was prepared according to the similar
procedure for 2d utilizing 2g instead of 2c, chromatography
using CH2Cl2/MeOH (25:1) afforded 2h (54 mg, 29%) as
The title compound was prepared according to the similar
procedure for 2a utilizing 4-pyridinecarboxaldehyde instead
of isophthalaldehyde, chromatography using CH2Cl2/MeOH
(50:1) afforded 3c (242 mg, 55%) as a white solid, mp 151e
1
a white solid, mp: 191e192 ꢀC. H NMR (CDCl3): d 7.78
(s, 1H), 7.74 (s, 1H), 7.27 (dd, J1 ¼ 2.34 Hz, J2 ¼ 14.08 Hz,
1H), 7.14 (d, J ¼ 8.05 Hz, 2H), 6.95 (dd, J1 ¼ 2.02 Hz,
J2 ¼ 8.96 Hz, 1H), 6.88 (t, J ¼ 8.79 Hz, 1H), 6.68
(d, J ¼ 8.06 Hz, 2H), 5.04 (m, 1H), 4.87 (m, 2H), 4.12
(t, J ¼ 9.03 Hz, 1H), 3.87 (dd, J1 ¼ 6.10 Hz, J2 ¼ 9.27 Hz,
1H), 3.64 (br s, 2H), 3.52 (s, 2H), 3.10 (br s, 4H), 2.66 (br
s, 4H). IR (KBr pellet, cmꢃ1): 3433, 3317, 3211, 2941,
2814, 1736, 1626, 1516, 1421, 1229, 1198, 1080, 793. MS
(EI) m/z (%): 451 (Mþ, 3), 304 (100). Anal. Calcd for
C23H26FN7O2: C, 61.18; H, 5.80; N, 21.72. Found: C, 61.05;
H, 5.72; N, 21.74.
1
152 ꢀC. H NMR (CDCl3): d 8.56 (d, J ¼ 5.50 Hz, 2H), 7.78
(d, J ¼ 0.79 Hz, 1H), 7.74 (d, J ¼ 0.79 Hz, 1H), 7.34 (d,
J ¼ 5.36 Hz, 2H), 7.27 (dd, J1 ¼ 2.34 Hz, J2 ¼ 14.16 Hz,
1H), 6.95 (dd, J1 ¼ 2.40 Hz, J2 ¼ 8.87 Hz, 1H), 6.88 (t,
J ¼ 8.87 Hz, 1H), 5.04 (m, 1H), 4.77 (m, 2H), 4.12 (t,
J ¼ 9.15 Hz, 1H), 3.87 (dd, J1 ¼ 6.12 Hz, J2 ¼ 9.35 Hz, 1H),
3.58 (s, 2H), 3.08 (br s, 4H), 2.75 (br s, 4H). IR (KBr pellet,
cmꢃ1): 3446, 2935, 2823, 1759, 1738, 1603, 1516, 1423,
1227, 1014, 789. MS (EI) m/z (%): 437 (Mþ, 43), 393
(100). Anal. Calcd for C22H24FN7O2: C, 60.40; H, 5.53; N,
22.41. Found: C, 60.20; H, 5.41; N, 22.13.
5.2.9. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-
4-(4-(pyridin-2-ylmethyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (3a)
5.2.12. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(furan-2-ylmethyl)piperazin-1-yl)phenyl)oxazolidin-
2-one (4a)
The title compound was prepared according to the similar
procedure for 2a utilizing 2-pyridinecarboxaldehyde instead
of isophthalaldehyde, chromatography using CH2Cl2/MeOH
(50:1) afforded 3a (258 mg, 59%) as a white solid, mp
140e142 ꢀC. 1H NMR (CDCl3): d 8.58 (m, J ¼ 1.08 Hz,
1H), 7.78 (d, J ¼ 0.95 Hz, 1H), 7.74 (d, J ¼ 1.10 Hz, 1H),
7.66 (t, J ¼ 7.63 Hz, 1H), 7.45 (d, J ¼ 7.70 Hz, 1H), 7.27
The title compound was prepared according to the similar
procedure for 2a utilizing 2-furaldehyde instead of isophtha-
laldehyde, chromatography using CH2Cl2/MeOH (50:1)
afforded 4a (346 mg, 81%) as a white solid, mp 148e
1
149 ꢀC. H NMR (CDCl3): d 7.78 (d, J ¼ 0.98 Hz, 1H), 7.73

1712
H. Fan et al. / European Journal of Medicinal Chemistry 43 (2008) 1706e1714
(d, J ¼ 0.98 Hz, 1H), 7.39 (dd, J1 ¼ 1.01 Hz, J2 ¼ 8.74 Hz,
1H), 7.27 (dd, J1 ¼ 2.54 Hz, J2 ¼ 14.09 Hz, 1H), 6.93 (dd,
J1 ¼ 2.40 Hz, J2 ¼ 8.86 Hz, 1H), 6.87 (t, J ¼ 8.86 Hz, 1H),
6.32 (dd, J1 ¼ 1.95 Hz, J2 ¼ 3.13 Hz, 1H), 6.24 (d,
J ¼ 2.93 Hz, 1H), 5.05 (m, 1H), 4.77 (m, 2H), 4.11 (t,
J ¼ 9.19 Hz, 1H), 3.88 (dd, J1 ¼ 6.16 Hz, J2 ¼ 9.29 Hz, 1H),
3.62 (s, 2H), 3.08 (t, J ¼ 4.79 Hz, 4H), 2.65 (t, J ¼ 4.69 Hz,
4H). IR (KBr pellet, cmꢃ1): 3105, 2953, 2816, 1736, 1518,
1421, 1227, 1202, 1115, 754. MS (EI) m/z (%): 426 (Mþ,
100). Anal. Calcd for C21H23FN6O3: C, 59.15; H, 5.44; N,
19.71. Found: C, 59.20; H, 5.52; N, 19.61.
5.2.15. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-((5-chlorofuran-2-yl)methyl)piperazin-1-yl)-
phenyl)oxazolidin-2-one (4d)
The title compound was prepared according to the similar
procedure for 2a utilizing 5-chloro-2-furaldehyde instead of
isophthalaldehyde, chromatography using CH2Cl2/MeOH
(50:1) afforded 4d (190 mg, 41%) as a white solid, mp
1
135e137 ꢀC. H NMR (CDCl3): d 7.78 (d, J ¼ 1.10 Hz, 1H),
7.74 (d, J ¼ 0.96 Hz, 1H), 7.27 (dd, J1 ¼ 2.32 Hz,
J2 ¼ 14.16 Hz, 1H), 6.94 (dd, J1 ¼ 2.47 Hz, J2 ¼ 8.93 Hz,
1H), 6.88 (t, J ¼ 8.72 Hz, 1H), 6.24 (d, J ¼ 3.16 Hz, 1H),
6.10 (d, J ¼ 3.16 Hz, 1H), 5.04 (m, 1H), 4.77 (m, 2H), 4.12
(t, J ¼ 9.14 Hz, 1H), 3.87 (dd, J1 ¼ 6.18 Hz, J2 ¼ 9.34 Hz,
1H), 3.58 (s, 2H), 3.08 (t, J ¼ 4.81 Hz, 4H), 2.66 (t,
J ¼ 4.74 Hz, 4H). IR (KBr pellet, cmꢃ1): 3460, 3115, 2945,
2821, 1740, 1518, 1421, 1335, 1225, 1198, 1011, 806, 752.
MS (EI) m/z (%): 460 (Mþ, 72), 290 (100). Anal. Calcd for
C21H22ClFN6O3: C, 54.73; H, 4.81; N, 18.23. Found: C,
54.63; H, 4.95; N, 17.96.
5.2.13. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(furan-3-ylmethyl)piperazin-1-yl)phenyl)-oxazolidin-
2-one (4b)
The title compound was prepared according to the similar
procedure for 2a utilizing 3-furancarboxaldehyde instead of
isophthalaldehyde, chromatography using CH2Cl2/MeOH
(50:1) afforded 4b (236 mg, 55%) as a white solid, mp
1
156e157 ꢀC. H NMR (CDCl3): d 7.78 (d, J ¼ 1.10 Hz, 1H),
5.2.16. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-((5-nitrofuran-2-yl)methyl)-piperazin-1-
yl)phenyl)oxazolidin-2-one (4e)
7.74 (d, J ¼ 1.10 Hz, 1H), 7.39 (t, J ¼ 1.65 Hz, 1H), 7.35 (t,
J ¼ 0.76 Hz, 1H), 7.27 (dd, J1 ¼ 2.33 Hz, J2 ¼ 14.16 Hz,
1H), 6.94 (dd, J ¼ 8.93 Hz, 2.47 Hz, 1H), 6.87 (t,
J ¼ 8.80 Hz, 1H), 6.41 (dd, J1 ¼ 0.82 Hz, J2 ¼ 1.78 Hz, 1H),
5.03 (m, 1H), 4.77 (m, 2H), 4.11 (t, J ¼ 9.08 Hz, 1H), 3.87
(dd, J1 ¼ 6.12 Hz, J2 ¼ 9.42 Hz, 1H), 3.45 (s, 2H), 3.06 (t,
J ¼ 4.82 Hz, 4H), 2.63 (t, J ¼ 4.82 Hz, 4H). 13C NMR
(CDCl3, 100 MHz): d 47.30, 50.32, 51.89, 52.70, 52.76,
70.34, 107.60 (d, JCeF ¼ 25.9 Hz), 111.31, 114.21 (d,
JCeF ¼ 2.7 Hz), 118.90 (d, JCeF ¼ 4.1 Hz), 121.06, 125.01,
To a solution of compound 1 (383 mg, 1 mmol) in CH3CN
was added Et3N (1 mL) followed by 2-(chloromethyl)-5-nitro-
furan (293 mg, 1.8 mmol). The mixture was stirred at 50 ꢀC
under N2 for 6 h, then washed with water (200 mL) and ex-
tracted with CH2Cl2 (3 ꢂ 30 mL). The combined organic ex-
tracts were dried over Na2SO4 and then concentrated in vacuo.
The residue was purified by silica gel column chromatography
eluting with CH2Cl2/MeOH (50:1) to afford compound 4e
131.85
(d,
JCeF ¼ 10.7 Hz),
134.29,
136.95
(d,
1
(333 mg, 71%) as a yellow solid, mp 128e130 ꢀC. H NMR
JCeF ¼ 9.1 Hz), 140.84, 142.93, 153.37, 155.18 (d,
JCeF ¼ 245 Hz). IR (KBr pellet, cmꢃ1): 3440, 3107, 2814,
1745, 1518, 1452, 1240, 1124, 1018, 808. MS (EI) m/z (%):
426 (Mþ, 100). Anal. Calcd for C21H23FN6O3: C, 59.15; H,
5.44; N, 19.71. Found: C, 59.03; H, 5.35; N, 19.84.
(CDCl3): d 7.79 (d, J ¼ 0.96 Hz, 1H), 7.73 (d, J ¼ 0.97 Hz,
1H), 7.27 (m, 2H), 6.95 (dd, J1 ¼ 2.55 Hz, J2 ¼ 8.94 Hz, 1H),
6.88 (t, J ¼ 8.87 Hz, 1H), 6.54 (d, J ¼ 3.58 Hz, 1H), 5.05 (m,
1H), 4.78 (m, 2H), 4.12 (t, J ¼ 9.15 Hz, 1H), 3.89 (dd,
J1 ¼ 6.19 Hz, J2 ¼ 9.35 Hz, 1H), 3.71 (s, 2H), 3.09 (t,
J ¼ 4.82 Hz, 4H), 2.71 (t, J ¼ 4.82 Hz, 4H). 13C NMR
(CDCl3, 100 MHz): d 47.28, 50.16, 51.90, 52.68, 54.45,
70.36, 107.61 (d, JCeF ¼ 26 Hz), 112.23, 112.47, 114.18
(d, JCeF ¼ 2.7 Hz), 119.00 (d, JCeF ¼ 4.1 Hz), 125.05, 132.16
(d, JCeF ¼ 10 Hz), 134.28, 136.54 (d, JCeF ¼ 9.1 Hz), 151.78,
153.37, 155.18 (d, JCeF ¼ 245 Hz), 155.61. IR (KBr pellet,
cmꢃ1): 3440, 3136, 2945, 2825, 1745, 1587, 1518, 1498,
1360, 1236, 1014, 812, 739. MS (ESI) m/z (%): 472
(M þ H)þ. Anal. Calcd for C21H22FN7O5$1/2CH3OH: C,
52.97; H, 4.96; N, 20.11. Found: C, 53.19; H, 4.86; N, 20.26.
5.2.14. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-((5-methylfuran-2-yl)methyl)-piperazin-1-
yl)phenyl)oxazolidin-2-one (4c)
The title compound was prepared according to the similar
procedure for 2a utilizing 5-methyl-2-furaldehyde instead of
isophthalaldehyde, chromatography using CH2Cl2/MeOH
(50:1) afforded 4c (100 mg, 23%) as a white solid, mp 139e
1
140 ꢀC. H NMR (CDCl3): d 7.78 (d, J ¼ 0.96 Hz, 1H), 7.74
(d, J ¼ 0.97 Hz, 1H), 7.27 (dd, J1 ¼ 2.42 Hz, J2 ¼ 8.98 Hz,
1H), 6.94 (dd, J1 ¼ 2.42 Hz, J2 ¼ 8.89 Hz, 1H), 6.87 (t,
J ¼ 8.87 Hz, 1H), 6.10 (d, J ¼ 2.89 Hz, 1H), 5.90 (dd,
J1 ¼ 1.00 Hz, J2 ¼ 3.01 Hz, 1H), 5.04 (m, 1H), 4.77 (m, 2H),
4.12 (t, J ¼ 9.15 Hz, 1H), 3.87 (dd, J1 ¼ 6.18 Hz,
J2 ¼ 9.34 Hz, 1H), 3.56 (s, 2H), 3.10 (t, J ¼ 4.82 Hz, 4H),
2.65 (t, J ¼ 4.61 Hz, 4H), 2.28 (s, 3H). IR (KBr pellet,
cmꢃ1): 3435, 3138, 2926, 2818, 1738, 1518, 1421, 1225,
1198, 1113, 806. MS (EI) m/z (%): 440 (Mþ, 18), 123
(100). Anal. Calcd for C22H25FN6O3: C, 59.99; H, 5.72; N,
19.08. Found: C, 58.82; H, 5.71; N, 18.98.
5.2.17. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(thiophen-2-ylmethyl)-piperazin-1-yl)phenyl)oxazolidin-
2-one (5a)
The title compound was prepared according to the similar
procedure for 2a utilizing 2-thiophenecarboxaldehyde instead
of isophthalaldehyde, chromatography using CH2Cl2/MeOH
(50:1) afforded 5a (330 mg, 75%) as a white solid, mp
1
156e157 ꢀC. H NMR (CDCl3): d 7.78 (d, J ¼ 1.10 Hz, 1H),
7.74 (d, J ¼ 0.96 Hz, 1H), 7.23e7.30 (m, 2H), 6.85e6.97

H. Fan et al. / European Journal of Medicinal Chemistry 43 (2008) 1706e1714
1713
(m, 4H), 5.05 (m, 1H), 4.77 (m, 2H), 4.11 (t, J ¼ 9.08 Hz, 1H),
3.87 (dd, J1 ¼ 6.19 Hz, J2 ¼ 9.35 Hz, 1H), 3.80 (s, 2H), 3.08
(t, J ¼ 4.82 Hz, 4H), 2.67 (t, J ¼ 4.75 Hz, 4H). IR (KBr pellet,
cmꢃ1): 3124, 2941, 2810, 1749, 1518, 1452, 1333, 1242, 1134,
717. MS (EI) m/z (%): 442 (Mþ, 66), 97 (100). Anal. Calcd for
C21H23FN6O2S: C, 57.00; H, 5.24; N, 18.99. Found: C, 57.06;
H, 5.15; N, 18.92.
4.77 (m, 2H), 4.11 (t, J ¼ 9.14 Hz, 1H), 3.87 (dd,
J1 ¼ 6.26 Hz, J2 ¼ 9.28 Hz, 1H), 3.78 (s, 2H), 3.08 (t,
J ¼ 4.54 Hz, 4H), 2.67 (t, J ¼ 4.60 Hz, 4H), 2.12 (s, 3H). IR
(KBr pellet, cmꢃ1): 3086, 2951, 2820, 1751, 1514, 1452,
1421, 1331, 1223, 1132, 1011, 785, 737. MS (EI) m/z (%):
456 (Mþ, 41), 111 (100). Anal. Calcd for C22H25FN6O2S: C,
57.88; H, 5.52; N, 18.41. Found: C, 58.00; H, 5.24; N, 18.29.
5.2.18. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-(thiophen-3-ylmethyl)piperazin-1-yl)-phenyl)oxazolidin-
2-one (5b)
5.2.21. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-((5-methylthiophen-2-yl)methyl)piperazin-1-yl)-
phenyl)oxazolidin-2-one (5e)
The title compound was prepared according to the similar
procedure for 2a utilizing 3-thiophenecarboxaldehyde instead
of isophthalaldehyde, chromatography using CH2Cl2/MeOH
(50:1) afforded 5b (310 mg, 70%) as a white solid, mp
The title compound was prepared according to the similar
procedure for 2a utilizing 5-methyl-2-thiophenecarboxalde-
hyde instead of isophthalaldehyde, chromatography using
CH2Cl2/MeOH (50:1) afforded 5e (302 mg, 66%) as a white
solid, mp 153e154 ꢀC. 1H NMR (CDCl3): d 7.78 (d,
J ¼ 1.10 Hz, 1H), 7.74 (d, J ¼ 1.10 Hz, 1H), 7.27 (dd,
J1 ¼ 2.34 Hz, J2 ¼ 14.16 Hz, 1H), 6.95 (dd, J1 ¼ 2.40 Hz,
J2 ¼ 8.86 Hz, 1H), 6.88 (t, J ¼ 8.71 Hz, 1H), 6.72 (d,
J ¼ 3.30 Hz, 1H), 6.59 (m, 1H), 5.05 (m, 1H), 4.77 (m, 2H),
4.11 (t, J ¼ 9.07 Hz, 1H), 3.87 (dd, J1 ¼ 6.16 Hz,
J2 ¼ 9.35 Hz, 1H), 3.71 (s, 2H), 3.08 (t, J ¼ 4.81 Hz, 4H),
2.65 (t, J ¼ 4.61 Hz, 4H), 2.45 (s, 3H). IR (KBr pellet,
cmꢃ1): 3120, 2935, 2812, 1751, 1516, 1452, 1240, 1134,
798. MS (EI) m/z (%): 456 (Mþ, 77), 139 (100). Anal. Calcd
for C22H25FN6O2S: C, 57.88; H, 5.52; N, 18.41. Found: C,
57.96; H, 5.44; N, 18.36.
1
149e151 ꢀC. H NMR (CDCl3): d 7.78 (d, J ¼ 0.96 Hz, 1H),
7.74 (d, J ¼ 1.10 Hz, 1H), 7.24e7.30 (m, 2H), 7.15 (dd,
J1 ¼ 1.10 Hz, J2 ¼ 3.02 Hz, 1H), 7.08 (dd, J1 ¼ 1.31 Hz,
J2 ¼ 4.88 Hz, 1H), 6.95 (dd, J1 ¼ 2.47 Hz, J2 ¼ 9.07 Hz, 1H),
6.88 (t, J ¼ 8.80 Hz, 1H), 5.05 (m, 1H), 4.77 (m, 2H), 4.11
(t, J ¼ 9.14 Hz, 1H), 3.88 (dd, J1 ¼ 6.19 Hz, J2 ¼ 9.35 Hz,
1H), 3.61 (s, 2H), 3.07 (t, J ¼ 4.82 Hz, 4H), 2.63 (t,
J ¼ 4.82 Hz, 4H). IR (KBr pellet, cmꢃ1): 3458, 3105, 2935,
2814, 1736, 1518, 1333, 1227, 1200, 797. MS (EI) m/z (%):
442 (Mþ, 90), 97 (100). Anal. Calcd for C21H23FN6O2S: C,
57.00; H, 5.24; N, 18.99. Found: C, 57.07; H, 5.22; N, 18.82.
5.2.19. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-((5-bromothiophen-2-yl)methyl)piperazin-1-yl)-
phenyl)oxazolidin-2-one (5c)
5.3. Pharmacology
The title compound was prepared according to the similar
procedure for 2a utilizing 5-bromo-2-thiophenecarboxalde-
hyde instead of isophthalaldehyde, chromatography using
CH2Cl2/MeOH (50:1) afforded 5c (260 mg, 50%) as a white
solid, mp 151e152 ꢀC. 1H NMR (CDCl3): d 7.78 (d,
J ¼ 0.97 Hz, 1H), 7.74 (d, J ¼ 1.10 Hz, 1H), 7.27 (dd,
J1 ¼ 2.41 Hz, J2 ¼ 14.10 Hz, 1H), 7.14 (d, J ¼ 1.37 Hz, 1H),
6.85e6.97 (m, 3H), 5.04 (m, 1H), 4.77 (m, 2H), 4.11 (t,
J ¼ 9.08 Hz, 1H), 3.88 (dd, J1 ¼ 6.19 Hz, J2 ¼ 9.35 Hz, 1H),
3.73 (s, 2H), 3.07 (t, J ¼ 4.82 Hz, 4H), 2.67 (t, J ¼ 4.75 Hz,
4H). IR (KBr pellet, cmꢃ1): 3118, 2945, 2812, 1743, 1520,
1452, 1240, 1136, 837, 746. MS (EI) m/z (%): 520 (Mþ,
41), 290 (100). Anal. Calcd for C21H22BrFN6O2S: C, 48.37;
H, 4.25; N, 16.12. Found: C, 48.49; H, 4.19; N, 16.01.
5.3.1. In vitro
The in vitro antibacterial activity of the compounds against
Gram-positive bacteria was tested with linezolid and vanco-
mycin as positive controls. Minimum inhibitory concentration
(MIC) values were determined using agar dilution method ac-
cording to NCCLS [18]. Compounds were dissolved in 20%
water in DMSO to prepare a stock solution in which the con-
centration of the compounds is 1920 mg/mL. Serial two-fold
dilutions were prepared from the stock solution in sterile water
or MuellereHinton (MH) agar medium to provide the concen-
tration ranges 8e0.0005 mg/mL. The tested organisms were
grown in MH broth medium at 35 ꢀC for 16e18 h, the broths
were adjusted to the turbidity of 0.5 McFarland standard and
then the bacterial suspensions were inoculated onto the
drug-supplemented MH agar plates at 35 ꢀC for 18e20 h.
5.2.20. (R)-5-((1H-1,2,3-Triazol-1-yl)methyl)-3-(3-fluoro-4-
(4-((3-methylthiophen-2-yl)methyl)piperazin-1-yl)-
phenyl)oxazolidin-2-one (5d)
The title compound was prepared according to the similar
procedure for 2a utilizing 3-methyl-2-thiophenecarboxalde-
hyde instead of isophthalaldehyde, chromatography using
CH2Cl2/MeOH (50:1) afforded 5d (300 mg, 66%) as a white
solid, mp 131e133 ꢀC. 1H NMR (CDCl3): d 7.78 (d,
J ¼ 0.96 Hz, 1H), 7.73 (d, J ¼ 0.82 Hz, 1H), 7.27 (dd,
J1 ¼ 2.27 Hz, J2 ¼ 14.10 Hz, 1H), 7.14 (d, J ¼ 5.09 Hz, 1H),
6.95 (dd, J1 ¼ 2.26 Hz, J2 ¼ 8.87 Hz, 1H), 6.88 (t,
J ¼ 8.80 Hz, 1H), 6.80 (d, J ¼ 5.09 Hz, 1H), 5.05 (m, 1H),
5.3.2. In vivo
KunMing SPF level mice weighing 20 ꢁ 2 g were used in
the study with five mice in each group. Lethal systemic infec-
tion was caused in the mice by the injection of the MLD inoc-
ulum of MRSA 05-2 intraperitoneally. Compounds were
administered orally or by intravenous injection (dissolved in
0.9% NaCl solution) immediately and 4 h post-infection.
The ED50 was calculated by the Bliss method [19,20] on
day 7 post-infection.

1714
H. Fan et al. / European Journal of Medicinal Chemistry 43 (2008) 1706e1714
[7] S.M. Swaney, H. Aoki, M.C. Ganoza, D.L. Shinabarger, Antimicrob.
5.3.3. Pharmacokinetics
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)
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[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.
Microbiol. Infect. Dis. 21 (2002) 751e754.
The selected compounds 2e, 2h, 4b and 4e were subjected
to pharmacokinetic studies on SpragueeDawley rats weighing
220e280 g with four mice in each group (two male and two
female). The tested compounds were administered orally at
the dose of 10 mg/kg and 50 mg/kg, while administered intra-
venously at the dose of 10 mg/kg. Serial specimens (300 mL)
were collected via the retrobulbar vein and quantitation was
performed by LCeMS, pharmacokinetic parameters were cal-
culated from the mean plasma concentration by non-compart-
mental analysis.
[11] O.A. Phillips, E.E. Udo, A.A.M. Ali, N. Al-Hassawi, Bioorg. Med.
Chem. 11 (1) (2003) 35e41.
[12] F. Houxing, X. Gang, C.H. Yilang, J. Zhiteng, Z.H. Shuhua, Y. Yushe,
J. Ruyun, Eur. J. Med. Chem. 42 (8) (2007) 1137e1143.
[13] A. Rattan, Drugs Future 28 (2003) 1070e1077.
Acknowledgements
[14] L.M. Ednie, A. Rattan, M.R. Jacobs, P.C. Appelbaum, Antimicrob.
Agents Chemother. 47 (3) (2003) 1143e1147.
The authors are thankful for the financial support from the
National Natural Science Foundation of China (20672125).
[15] S.J. Brickner, D.K. Hutchinson, M.R. Barbachyn, P.R. Manninen,
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