Novel piperidinyloxy oxazolidinone antibacterial agents. Diversification of the N-substituent

Article abstract of DOI:10.1016/S0968-0896(02)00065-2

Oxazolidinone antibacterial agents, where the morpholino group of linezolid was replaced with an N-substituted piperidinyloxy moiety, were synthesized and shown to be active against a variety of resistant and susceptible Gram-positive organisms. The funct

Full text of DOI:10.1016/S0968-0896(02)00065-2

Bioorganic & Medicinal Chemistry 10 (2002) 2345–2351
Novel Piperidinyloxy Oxazolidinone Antibacterial Agents.
Diversification of the N-Substituent
Michele A. Weidner-Wells,* Christine M. Boggs, Barbara D. Foleno, John Melton,
Karen Bush, Raul M. Goldschmidt and Dennis J. Hlasta
Antimicrobial Agents Research Team, Johnson and Johnson Pharmaceutical Research and Development, LLC,
1000 Route 202, Raritan, NJ 08869, USA
Received 8 November 2001; accepted 2 January 2002
Abstract—Oxazolidinone antibacterial agents, where the morpholino group of linezolid was replaced with an N-substituted piper-
idinyloxy moiety, were synthesized and shown to be active against a variety of resistant and susceptible Gram-positive organisms.
The functionality attached to the piperidine nitrogen was varied extensively to determine the SAR for this series. One of the most
potent compounds, 11, showed in vivo efficacy upon subcutaneous administration in a Staphylococcus aureus Smith murine sys-
temic infection. # 2002 Elsevier Science Ltd. All rights reserved.
Introduction
New classes of antibacterial agents with novel mechan-
isms of action are urgently needed to combat the
increase in multidrug resistant infections. Recent reports
indicate that in 1998, at least 21% of all nosocomial
enterococcal infections in US hospitals were due to
vancomycin-resistant enterococci (VRE).1 The oxazoli-
dinones, a new class of totally synthetic antibacterial
agents, are active against a variety of clinically impor-
tant susceptible and resistant Gram-positive organisms
such as methicillin-resistant Staphylococcus aureus
(MRSA), VRE, and penicillin-resistant Streptococcus
pneumoniae (PRSP). Scientists at DuPont originally
discovered this class of agents in the late 1980’s.2
However, development of DuP-721, the drug candidate
that emerged from these initial studies, was dis-
continued following Phase I clinical trials. Subse-
quently, researchers at Pharmacia and Upjohn
identified two clinical candidates, eperezolid (1) and
linezolid (2).3 Linezolid is currently marketed for the
treatment of multidrug resistant Gram-positive infec-
tions such as nosocomial and community-acquired
pneumonia and skin infections.
The oxazolidinone class of antibacterial agents selec-
tively binds to the 23S RNA component of the 50S
ribosomal subunit, inhibiting protein synthesis at an
early phase of translation.4 Due to its unique mechan-
ism of action, it is believed that there will be a lack of
cross-resistance with other classes of protein synthesis
inhibitors.5
Several SAR studies of the oxazolidinones have
demonstrated a high tolerance for structural variation
at the 4-position of the phenyl ring, while the oxazoli-
dinone ring is essential for activity.6 Based on these
reports, we have developed a series of oxazolidinone
antibacterial agents 3 where the morpholine moiety of
linezolid was replaced with a 4-piperidinyloxy group
with various functionalities appended to the nitrogen.
Previous studies from these laboratories have examined
the effect of ring size and fluorine substitution on in
*Corresponding author. Tel.: +1-908-704-5933; fax: +1-908-203-
8109; e-mail: mwells@prdus.jnj.com
0968-0896/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S0968-0896(02)00065-2

2346
M. A. Weidner-Wells et al. / Bioorg. Med. Chem. 10 (2002) 2345–2351
Scheme 3. Reagents: (a) (i) TEA, CH2Cl2; (ii) ArC(O)Cl; (b) (i) TEA,
CH2Cl2; (ii) ClCH2C(O)Cl; (c) pyridylmethanol, NaH, THF.
smoothly to afford amides 10 and 12–14. a-Hydroxy-
acetamide 11 was obtained by deprotection of a-benzyl-
oxyacetamide 10. Sulfonamide 17 was prepared via
glycinamide 16. Acetamide 18 was synthesized directly
by coupling of 9 with acetylglycine (Scheme 2).
Scheme 1. Reagents: (a) KOtBu, THF, 89%; (b) HCO2NH4, Pd/C,
MeOH, 99%; (c) Cbz–Cl, NaHCO3, acetone, water, 89%; (d) (i) nBuLi,
THF, À78ꢀC; (ii) (R)-glycidyl butyrate, 72%; (e) Ms–Cl, TEA, CH2Cl2,
0 ꢀC; (f) NaN3, DMF, 75 ꢀC, 92%; (g) (i) PPh3, THF; (ii) water, reflux;
(h) Ac2O, pyridine, EtOAc, 85%; (i) TFA, CH2Cl2, 98%.
Reaction of 9 with heteroaryl acid chlorides afforded
amides 19–22 in good yield. Pyridino analogues 23–25
of a-benzyloxy acetamide 10 were synthesized in two
steps. Amine 9 was converted to the a-chloroacetamide
followed by reaction with the sodium alkoxide of the
appropriate pyridinylmethanol regioisomer (Scheme 3).
Results and Discussion
The oxazolidinone analogues synthesized were tested
for in vitro antibacterial activity against a panel of sus-
ceptible and resistant Gram-positive and Gram-negative
organisms. None of these compounds exhibited any
activity against Gram-negative organisms such as
Escherichia coli K-12 wild type strain or an E. coli strain
OC 2530 that is hypersensitive to antimicrobial agents
due to a defective outer membrane when tested at con-
centrations as high as 32 mg/mL. Data for select Gram-
positive organisms are reported as a minimum inhibitory
concentration (MIC) expressed in mg/mL (Table 1).
Compounds were tested in broth as well as in the pre-
sence of 50% mouse serum against Staphylococcus aureus
Smith (OC4172) to give an indication of serum protein
binding. If the MIC is increased at least 4-fold in the
presence of serum the compound may be binding to
serum proteins or is inactivated by components of the
serum. As a result, there may no longer be a sufficient
concentration of free drug in the serum to inhibit the
growth of bacteria effectively in vivo.
Scheme 2. Reagents: (a) (i) TEA, CH2Cl2; (ii) R1CH2C(O)Cl;
(b) HCO2NH4, Pd/C, MeOH; (c) (i) TEA, CH2Cl2; (ii)
CbzNHCH2C(O)F; (d) H2, Pd/C, MeOH, 50 psi; (e) CH3SO2Cl, TEA,
CH2Cl2; (f) (i) TEA, CH2Cl2; (ii) acetylglycine, EDCI.
vitro activity.7 It was reported that fluorine substitution
increases potency and the six-membered 4-piperi-
dinyloxy ring was optimal. This paper describes efforts
to increase the in vitro activity by diversification of the
nitrogen substituent. In addition, several of the more
potent compounds were studied in vivo.
Chemistry
The synthesis of key intermediate 9 is outlined in
Scheme 1. A nucleophilic aromatic substitution reaction
between Boc-protected 4-hydroxypiperidine (4) and
3,4-difluoronitrobenzene afforded the nitroaromatic
derivative 5. Reduction of the nitro group followed by
protection of the resulting aniline gave Cbz derivative 6.
The oxazolidinone ring was assembled in one step by
reaction of the anion of 6 with (R)-glycidyl butyrate to
afford alcohol 7.3 Standard functional group manipu-
lations yielded Boc-protected acetamide 8 in several
steps. The Boc group was removed by treatment with
trifluoroacetic acid in methylene chloride to provide
intermediate 9 as the TFA salt in excellent overall yield.
The initial compounds screened were the a-benzyloxy-
acetamide 10 and the a-hydroxyacetamide 11, the direct
analogues of eperezolid (1). These compounds showed
measurable in vitro antibacterial activity against a range
of susceptible as well as resistant Gram-positive organ-
isms, such as MRSA and VRE. Since these compounds
were 2- to 4-fold less potent than linezolid (2), mod-
ification of the hydroxyl group was investigated as a
possible means to increase potency. Examination of the
MIC values for compounds 10–14 relative to linezolid,
indicate that the hydroxyl may be functioning as a
hydrogen bond donor since des-hydroxyl analogue 12,
methylated analogue 13, and the acetylated derivative
14 are 2-fold less potent than 11. In addition, the phenyl
group of 10 is important since this compound is 2- to
Amine 9 was derivatized as shown in Schemes 2 and 3.
Acylation with a variety of acid chlorides proceeded

M. A. Weidner-Wells et al. / Bioorg. Med. Chem. 10 (2002) 2345–2351
Table 1. In vitro antibacterial activity (MIC, mg/mL)
2347
Compd
R
S. aureus
OC 4172
S. aureus
with seruma
MRSA
OC 2878
E. faecium
(VRE) OC 3312
E. faecalis
ATCC 29212
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
2
CH2OCH2Ph
CH2OH4
CH3
CH2OCH3
CH2OAc
CH2NHCbz
CH2NH2
CH2NHSO2CH3
CH2NHAc
2-Thienyl
4
4
8
8
8
8
32
8
8
8
16
8
8
32
16
8
16
4
2
8
8
8
8
4
8
16
16
16
8
32
16
64
8
8
8
16
32
8
4
16
16
16
32
32
16
16
16
32
16
16
16
16
16
2
16
16
16
8
32
16
32
8
8
32
16
16
4
8
4
2-Furyl
5-Isoxazolyl
2-Pyridyl
16
8
8
16
32
16
16
2
CH2OCH2-(2-pyridyl)
CH2OCH2-(3-pyridyl)
CH2OCH2-(4-pyridyl)
—
16
16
8
8
2
2
2
aIn the presence of 50% mouse serum.
4-fold more potent than the methylated analogue 13.
However, benzyloxy analogue 10 exhibits an increase in
MIC in the presence of mouse serum indicating either
binding to or inactivation by serum proteins, whereas
hydroxy acetamide 11 does not exhibit this behavior.
This is most likely due to the increased lipophilicity of
the benzyloxy moiety relative to the hydroxyl.
compounds were less potent than the parent compound
10.
Compounds 10 and 11 were screened against an
expanded panel of Gram-positive organisms as well as
Haemophilus influenzae, a Gram-negative respiratory
pathogen. Benzyloxyacetamide 10 exhibited a MIC
range of 1–8 mg/mL against a panel of 26 isolates of
penicillin-susceptible and penicillin-resistant S. pneumoniae,
while hydroxyacetamide 11 had a MIC range of 0.5–4
mg/mL against the same organisms. Linezolid had a
range of 0.12–1 mg/mL. Neither of the piperidinyloxy
compounds 10 nor 11 was active against H. influenzae at
concentrations as high as 32 mg/mL, whereas linezolid was
active against some strains (MIC range 4–32 mg/mL).
Hydroxyl mimics 15–18 were investigated next. As is
evident from the data, a basic functionality is detri-
mental to activity since amine 16 exhibits a significant
loss in potency. The sulfonamide 17 and acetamide 18
also are several-fold less potent than hydroxy acetamide
11. The highly lipophilic Cbz derivative 15 displays a
4-fold increase in MIC in the presence of serum, thus
indicating possible protein binding.
Compounds 10 and 11, administered subcutaneously in
a S. aureus Smith murine systemic infection model, had
ED50 values of 48 and 13 mg/kg/day, respectively. The
ED50 for linezolid was 2.7 mg/kg/day. The poor in vivo
activity of 10 compared to 11 is most likely due to a
combination of serum protein binding and poor solubility
in the vehicle (40% hydroxypropyl-b-cyclodextrin) uti-
lized for the study.
A 5-isoxazolyl amide has been reported to be a rigid
bioisostere for the hydroxyacetamide functionality of
eperezolid (1).8 To this end, heteroaryl amides 19–22
were synthesized. In general, replacement of the benzyl-
oxy acetamide with heteroaryl amides led to less potent
compounds. 2-Thienyl amide 19 and 5-isoxazolyl amide
21 were the most potent analogues in this series. Not
unexpectedly, the 2-pyridyl substitution was better than
the regiosiomeric pyridine analogues (data not shown)
since this placement of the nitrogen more closely mimics
the a-hydroxyacetyl moiety.
In conclusion, a series of piperidinyloxy oxazolidinone
antibacterial agents was discovered with in vitro activity
against a variety of clinically relevant susceptible as well
as resistant (MRSA, VRE, and PRSP) Gram-positive
organisms. Diverse functional groups are tolerated on
the piperidinyloxy nitrogen; however, bulky substituents
resulted in a loss of activity. Two of the most potent
compounds, 10 and 11, were active against a larger
panel of bacterial pathogens, but had MIC values >32
mg/mL against H. influenzae. a-Hydroxyacetamide 11
Since benzyloxyacetamide 10 had a favorable suscept-
ibility profile except for the increased MIC in the pres-
ence of serum, attention was focused on the
preparation of analogues that would minimize this
interaction. The regioisomeric pyridyl analogues 23–25
exhibited reduced serum protein binding, however, these

2348
M. A. Weidner-Wells et al. / Bioorg. Med. Chem. 10 (2002) 2345–2351
showed in vivo efficacy upon subcutaneous administra-
tion in a S. aureus Smith murine systemic infection model.
mL) at À78 ꢀC, was added 2.5M n-BuLi (2.0 mL; 5.0
mmol) and the reaction stirred for 1 h. (R)-Glycidyl
butyrate (0.71 mL; 5.01 mmol) was added via syringe
and the reaction warmed to room temperature and stir-
red overnight. The reaction was carefully poured into
satd NH4Cl (150 mL) and extracted with EtOAc (3Â100
mL). The combined organic layers were washed with
H2O, dried and the solvent evaporated. Chromato-
graphy (60% EtOAc/hexanes) gave 1.ꢀ15 g (72%) of
Experimental
General
Proton (1HNMR) magnetic resonance spectra were
recorded on a Bruker Avance 300 instrument in deuter-
iochloroform unless noted otherwise. Mass spectra were
recorded on a HP1100 LC/MSD with an ESI source
and single quad analyzer. Column chromatography was
performed with EM Silica Gel 60. Melting points were
determined on a Thomas Hoover Mel-Temp apparatus
and are uncorrected. The term ‘dried’ refers to the use
of anhydrous magnesium sulfate.
1
alcohol 7 as a white solid; mp 110–111 C. HNMR d
7.47 (dd, J=12.8, 3.0 Hz, 1H), 7.15 (dt, J=8.8, 1.4 Hz,
1H), 7.00 (t, J=8.8 Hz, 1H), 4.73–4.83 (m, 1H), 4.38–
4.46 (m, 1H), 3.90–4.01 (m, 3H), 3.68–3.80 (m, 3H),
3.25–3.46 (m, 2H), 2.37 (br s, 1H), 1.84–2.01 (m, 2H),
1.71–1.80 (m, 2H), 1.48 (s, 9H). MS [M+Na]+ 433.5.
Anal. calcd for C20H27FN2O6: C, 58.53; H, 6.63; N,
6.83. Found: C, 58.27; H, 6.59; N, 6.61.
1-[N-(t-Butoxycarbonyl)piperidinyl-4-oxy]-2-fluoro-4-nitro-
benzene (5). To
(S)-N-[3-[3-Fluoro-4-{N-(t-butoxycarbonyl)piperidinyl-4-
oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (8).
To alcohol 7 (2.13 g; 5.20 mmol) in CH2Cl2 (100 mL)
at 0 ꢀC was added triethylamine (1.5 mL; 5.27 mmol)
and methanesulfonyl chloride (0.78 mL; 10.0 mmol).
After stirring for 3 h at 0 ꢀC, the reaction was poured
into H2O (75 mL) and extracted with CH2Cl2 (100 mL).
The combined organic layers were washed with H2O,
dried and the solvent evaporated to yield 2.54 g (99%)
of mesylate as a cream solid; mp 127–129 ꢀC, MS
[M+HÀBoc]+ 389.2. To a solution of mesylate (5.20
mmol) in DMF (70 mL) was added sodium azide (1.22
g; 18.8 mmol) and the reaction heated at 75 ꢀC over-
night. The reaction was poured into H2O (300 mL) and
extracted with EtOAc (3Â200 mL). The combined
organic layers were washed with H2O (3Â200 mL),
dried and the solvent evaporated to yield 2.07 g (92%)
a solution N-(t-butoxycarbonyl)-
4-piperidinol (740 mg; 3.7 mmol) in dry THF (10 mL) at
0 ꢀC was added dropwise KOtBu (1 M in THF; 4.0 mL;
4.0 mmol). After stirring at 0 ꢀC for 0.5 h, 3,4-difluoro-
nitrobenzene (0.40 mL; 3.6 mmol) was added and the
reaction warmed to room temperature and stirred over-
night. The reaction was poured into H2O (100 mL) and
extracted with CH2Cl2 (3Â100 mL). The combined
organic layers were washed with H2O, dried and the
solvent evaporated. The solid was triturated with cold
hexanes to afford 1.1 g (89%) of 5 as a pale yellow solid;
mp 88–90 ꢀC. HNMR d 7.98–8.06 (m, 2H), 7.05 (t,
1
J=8.5 Hz, 1H), 4.67 (septet, J=3.5 Hz, 1H), 3.66–3.75
(m, 2H), 3.37–3.45 (m, 2H), 1.94–2.05 (m, 2H), 1.80–
1.89 (m, 2H), 1.61 (s, 9H). MS [M+Na]+ 364. Anal.
calcd for C16H21FN2O5: C, 56.46; H, 6.22; N, 8.23.
Found: C, 56.48; H, 6.22; N, 8.02.
1
of azide as a beige solid. HNMR d 7.46 (dd, J=12.9,
2.7 Hz, 1H), 7.14 (dt, J=8.9, 1.4 Hz, 1H), 7.01 (t,
J=8.9 Hz, 1H), 4.71–4.83 (m, 1H), 4.34–4.43 (m, 1H),
4.05 (t, J=8.9 Hz, 1H), 3.83 (dd, J=8.9, 6.2 Hz, 1H),
3.77–3.88 (m, 2H), 3.71 (dd, J=13.2, 4.6 Hz, 1H), 3.59
(dd, J=13.2, 4.3 Hz, 1H), 3.23–3.38 (m, 2H), 1.85–2.00
(m, 2H), 1.71–1.81 (m, 2H), 1.47 (s, 9H).
2-Fluoro-1-{N-(t-butoxycarbonyl)piperidinyl-4-oxy}-
4-(phenylmethoxycarbonylamino)benzene (6). To nitro-
benzene 5 (1.78 g, 5.23 mmol) in MeOH(100 mL) was
added ammonium formate (1.05 g; 16.6 mmol) and 10%
Pd/C (70 mg) and the reaction heated at reflux under N2
for 2 h. The reaction was filtered through a pad of Celite
and the filtrate evaporated to afford the aniline as a gold
oil. To crude aniline (5.23 mmol) in 2:1 acetone/H2O
(150 mL) at 0 ꢀC was added NaHCO3 (1.03 g; 12.3
mmol) and benzylchloroformate (0.90 mL; 6.30 mmol).
After stirring at room temperature for 6 h, the volatiles
were evaporated, the residue diluted with H2O (300 mL)
and extracted with Et2O (3Â150 mL). The combined
organic layers were washed with H2O, dried and the
solvent evaporated. Chromatography (20% EtOAc/
hexanes) afforded 2.06 g (89%) of 6 as a yellow, waxy
To a solution of azide (4.78 mmol) in dry THF (9 mL)
was added triphenylphosphine (1.51 g, 5.75 mmol) and
the reaction stirred for 3 h at room temperature. H2O
(4.5 mL) was added and the reaction heated at 60 ꢀC for
4 h. The volatiles were evaporated and the residue
azeotroped with benzene (2Â20 mL) to yield the crude
amine. To a solution of this crude amine in EtOAc (100
mL) was added acetic anhydride (0.58 mL; 6.15 mmol)
and pyridine (1.2 mL; 14.8 mmol), and the reaction
stirred at room temperature overnight. The reaction
mixture was poured into H2O (250 mL) and extracted
with EtOAc (3Â150 mL). The combined organic layers
were dried and the solvent removed. Chromatography
(100% EtOAc to 5% MeOH/EtOAc) yielded 1.85 g
(85%) of acetamide 8 as a white solid; mp 179–180 ꢀC.
1HNMR d 7.47 (dd J=12.8, 2.4 Hz, 1H), 7.09 (dt,
J=8.9 Hz, 1.4 Hz, 1H), 7.01 (t, J=8.9 Hz, 1H), 6.05 (br
t, J=6.0 Hz, 1H), 4.71–4.85 (m, 1H), 4.33–4.46 (m, 1H),
4.00 (t, J=9.0 Hz, 1H), 3.51–3.85 (m, 5H), 3.23–3.39
(m, 2H), 2.08 (s, 3H), 1.62–1.98 (m, 4H), 1.50 (s, 9H).
solid, mp 101–103 ꢀC. HNMR d 7.31–7.44 (m, 6H),
1
6.93–7.06 (m, 2H), 6.60 (br s, 1H), 5.19 (s, 2H), 4.35–
4.49 (m, 1H), 3.74–3.87 (m, 2H), 3.22–3.39 (m, 2H),
1.81–2.07 (m, 2H), 1.62–1.79 (m, 2H), 1.48 (s, 9H).
MS[M+Na]+ 467. Anal. calcd for C24H29FN2O5: C,
64.85; H, 6.56; N, 6.30. Found: C, 64.62; H, 6.57; N, 6.19.
(R)-[3-[3-Fluoro-4-{N-(t-butoxycarbonyl)piperidinyl-4-
oxy}phenyl]-2-oxo-5-oxazolidinyl]-methanol (7). To
Cbz derivative 6 (1.73 g; 3.89 mmol) in dry THF (25

M. A. Weidner-Wells et al. / Bioorg. Med. Chem. 10 (2002) 2345–2351
2349
MS [M+Na]+ 474. Anal. calcd for C22H30FN3O6: C,
58.53; H, 6.70; N, 9.31. Found: C, 58.56; H, 6.84; N,
9.02.
3H), 1.80–1.90 (m, 4H). MS [M+H]+ 394. Anal. calcd
C19H24FN3O5/1.5H2O: C, 54.28; H, 6.47; N, 9.99.
Found: C, 54.36; H, 6.16; N, 10.17.
(S)-N-[3-[3-Fluoro-4-{piperidinyl-4-oxy}phenyl]-2-oxo-
5-oxazolidinyl]methyl]acetamide trifluoroacetate (9). To
a solution of protected acetamide 8 (1.94 g; 4.30 mmol)
in CH2Cl2 (225 mL) was added trifluoroacetic acid (2.5
mL; 32.50 mmol) and the reaction stirred at room tem-
perature for 6 h. The volatiles were evaporated to yield
(S)-N-[3-[3-Fluoro-4-{N-(methoxyacetyl)piperidinyl-4-
oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl] acetamide (13).
This was prepared according to the procedure for 10
utilizing methoxyacetyl chloride instead of benzyloxy-
acetyl chloride. Chromatography (2.5–10% MeOH/
CH2Cl2) afforded 101 mg (32%) of 13 as a beige foam.
1HNMR d 7.48 (dd, J=12.9, 2.5 Hz, 1H), 7.09–7.12
(m, 1H), 7.00 (t, J=8.8 Hz, 1H), 6.00 (br t, 1H), 4.67–
4.72 (m, 1H), 4.40–4.43 (m, 1H), 4.13 (s, 2H), 4.03 (t,
J=8.9 Hz, 1H), 3.52–3.86 (m, 6H), 3.44 (s, 3H), 3.40–
3.43 (m, 1H), 2.03 (s, 3H), 1.72–1.96 (m, 4H). MS
[M+Na]+ 446. Anal. calcd for C20H26FN3O6: C, 56.73;
H, 6.19; N, 9.92. Found: C, 57.05; H, 6.21; N, 9.55.
1
a viscous oil (98%). HNMR (DMSO- d6) d 9.50 (br s,
1H), 9.27 (br s, 1H), 8.21 (t, J=5.8 Hz, 1H), 7.54 (dd,
J=12.0, 2.3 Hz, 1H), 7.06–7.11 (m, 2H), 4.74–4.79 (m,
1H), 4.49–4.58 (m, 1H), 4.05 (t, J=8.9 Hz, 1H), 3.80
(dd, J=8.9, 6.5 Hz, 1H), 3.51–3.62 (m, 2H), 3.27–3.33
(m, 2H), 3.18–3.23 (m, 2H), 2.04–2.15 (m, 4H), 1.95 (s,
3H). MS [M+Na]+ 374.
(S)-N-[3-[3-Fluoro-4-{N-(benzyloxyacetyl)piperidinyl-
4-oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (10).
To a suspension of 9 (1.50 mmol) in CH2Cl2 (50 mL)
was added NEt3 (0.60 mL, 4.3 mmol) and benzyloxy-
acetyl chloride (0.25 mL, 1.58 mmol). After stirring for
18 h, the reaction was poured into H2O (75 mL) and
extracted with CH2Cl2 (4Â50 mL). The combined
organic layers were dried and evaporated. Chromato-
graphy (5% MeOH/EtOAc) afforded 10 as a white glass
(86%). 1HNMR d 7.47 (dd, J=12.9, 2.5 Hz, 1H), 7.21–
7.45 (m, 6H), 6.98 (t, J=8.8 Hz, 1H), 6.24 (br t, J=6.1
Hz, 1H), 4.74–4.87 (m, 1H), 4.61 (s, 2H), 4.48–4.53 (m,
1H), 4.20 (s, 2H), 4.02 (t, J=9.0 Hz, 1H), 3.62–3.87 (m,
6H), 3.47–3.52 (m, 1H), 2.02 (s, 3H), 1.81–1.98 (m, 4H).
MS [M+Na]+ 522. Anal. calcd for C26H30FN3O6: C,
62.52; H, 6.05; N, 8.41. Found: C, 62.38; H, 6.08; N,
8.42.
(S)-N-[3-[3-Fluoro-4-{N-(acetoxyacetyl)piperidinyl-4-
oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (14).
This was prepared according to the procedure for 10
utilizing acetoxyacetyl chloride instead of benzyloxy-
acetyl chloride. Chromatography using 10% MeOH/
CH2Cl2 afforded 14 as a pale beige solid (53%); mp
146–147.5 ꢀC. 1HNMR d 7.48 (dd, J=12.9, 2.4 Hz,
1H), 7.06–7.12 (m, 1H), 7.00 (t, J=8.9 Hz, 1H), 6.08 (br
t, J=5.8 Hz, 1H), 4.68–4.81 (m, 3H), 4.46–4.51 (m, 1H),
4.03 (t, J=9.0 Hz, 1H), 3.61–3.78 (m, 6H), 3.30–3.35
(m, 1H), 2.19 (s, 3H), 2.02 (s, 3H), 1.80–1.91 (m, 4H).
MS [M+H]+ 452. Anal. calcd for C21H26FN3O7: C,
55.81; H, 5.81; N, 9.31. Found: C, 55.55; H, 5.71; N,
9.28.
(S)-N-[3-[3-Fluoro-4-{N-(ꢀ-phenylmethoxycarbonylamino-
acetyl)piperidinyl-4-oxy}phenyl]-2-oxo-5-oxazolidinyl]-
methyl]acetamide (15). To a solution of 9 (266 mg, 0.76
mmol) in CH2Cl2 (15 mL) was added NEt3 (0.2 mL)
and N-phenylmethoxycarbonylglycine acid fluoride (188
mg, 0.89 mmol) and the reaction was stirred at room
temperature for 1.5 h. Then the reaction was poured
into sat. NaHCO3 (50 mL) and extracted with CH2Cl2.
The combined organic layers were dried and the solvent
evaporated to afford 375 mg (91%) of crude 15. 1H
NMR d 7.48 (dd, J=12.9, 2.4 Hz, 1H), 7.37–7.44 (m,
5H), 7.09–7.12 (m, 1H), 7.00 (t, J=8.9 Hz, 1H), 6.21–
6.25 (m, 1H), 5.87 (br t, J=5.9 Hz, 1H), 5.15 (s, 2H),
4.70–4.75 (m, 1H), 4.48–4.52 (m, 1H), 3.97–4.11 (m,
3H), 3.62–3.86 (m, 6H), 3.27–3.33 (m, 1H), 2.10 (s, 3H),
1.80–1.89 (m, 4H). MS [M+Na]+ 465. Anal. calcd for
C27H31FN4O7/0.25CH2Cl2: C, 58.05; H, 5.63; N, 9.94.
Found: C, 58.35; H, 5.75; N, 9.59.
(S)-N-[3-[3-Fluoro-4-{N-(ꢀ-hydroxyacetyl)piperidinyl-
4-oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (11).
To a solution of 10 (540 mg, 1.08 mmol) in MeOH(50
mL) was added ammonium formate (503 mg) and a
catalytic amount of 10% Pd/C, and the reaction was
heated at reflux overnight. Then the reaction was fil-
tered through a pad of Celite and the solvent removed
under reduced pressure. Chromatography (2–10%
MeOH/CH2Cl2) afforded 11 as a hygroscopic white
glass (93%), mp 71–75 ꢀC. 1HNMR d 7.49 (dd,
J=12.9, 2.6 Hz, 1H), 7.09 (dd, J=8.9, 1.6 Hz, 1H), 7.00
(t, J=8.9 Hz, 1H), 6.18 (br t, J=6.1 Hz, 1H), 4.75–4.83
(m, 1H), 4.51 (q, J=4.6 Hz, 1H), 4.19 (s, 2H), 4.02 (t,
J=9.0 Hz, 1H), 3.51–3.86 (m, 7H), 3.20 (dt, J=13.7, 5.2
Hz, 1H), 2.03 (s, 3H), 1.80–1.95 (m, 4H). MS [M+Na]+
432. Anal. calcd for C19H24FN3O6: C, 55.74; H, 5.91; N,
10.26. Found: C, 55.85; H, 5.86; N, 10.13.
(S)-N-[3-[3-Fluoro-4-{N-(ꢀ-aminoacetyl)piperidinyl-4-
oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (16).
A solution of 15 (340 mg, 0.62 mmol) in EtOH(30
mL) was treated with 10% Pd/C (36 mg), followed by
hydrogenation at 50 psi overnight. The suspension was
filtered through Celite and the filtrate evaporated to
afford crude amine. Trituration of the crude solid with
CHCl3 yielded 16 as a beige glass (73%); mp 142–
(S)-N-[3-[3-Fluoro-4-{N-(acetyl)piperidinyl-4-oxy}phenyl]-
2-oxo-5-oxazolidinyl]methyl]acetamide (12). This was
prepared according to the procedure for 10 utilizing
acetyl chloride instead of benzyloxyacetyl chloride. The
title compound was isolated as a hygroscopic glass
(46%). 1HNMR d 7.47 (dd, J=12.9, 2.2 Hz, 1H), 7.02–
7.09 (m, 2H), 6.97 (br t, J=8.8 Hz, 1H), 4.75–4.79 (m,
1H), 4.44–4.48 (m, 1H), 4.03 (t, J=9.0 Hz, 1H), 3.61–
3.87 (m, 6H), 3.38–3.49 (m, 1H), 2.12 (s, 3H), 2.02 (s,
146 ꢀC. HNMR (DMSO- d6) d 8.29 (br t, J=5.8 Hz,
1
1H), 7.53 (dd, J=13.0, 2.5 Hz, 1H), 7.17–7.32 (m, 2H),
4.68–4.80 (m, 1H), 4.52–4.73 (m, 1H), 4.10 (t, J=9.1

2350
M. A. Weidner-Wells et al. / Bioorg. Med. Chem. 10 (2002) 2345–2351
1
Hz, 1H), 3.92 (s, 2H), 3.71–3.75 (m, 1H), 3.38–3.62 (m,
6H), 1.88 (s, 3H), 1.75–1.87 (m, 4H). MS [M+H]+ 409.
Anal. calcd for C19H25FN4O5/0.65CHCl3: C, 48.56; H,
5.32; N, 11.53. Found: C, 48.68; H, 5.42; N, 11.21.
(81%); mp 134–136 ꢀC. HNMR d 7.45–7.51 (m, 2H),
6.98–7.09 (m, 3H), 6.48 (dd, J=3.5, 1.8 Hz, 1H), 6.20 (t,
J=6.1 Hz, 1H), 4.74–4.82 (m, 1H), 4.50–4.55 (m, 1H),
4.03 (t, J=8.9 Hz, 1H), 3.57–3.94 (m, 7H), 2.03 (s, 3H),
1.82–1.93 (m, 4H). MS [M+H]+ 446. Anal. calcd for
C22H24FN3O6: C, 59.32; H, 5.43; N, 9.42. Found: C,
59.17; H, 5.29; N, 9.35.
(S)-N-[3-[3-Fluoro-4-{N-(ꢀ-methylsulfonylaminoacetyl)-
piperidinyl-4-oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]-
acetamide (17). To a solution of 16 (340 mg, 0.62
mmol) in CH2Cl2 (30 mL) was added NEt3 (0.23 mL)
and methanesulfonyl chloride (0.07 mL, 0.90 mmol) and
the reaction stirred at room temperature for 18 h. The
reaction was poured into sat. NaHCO3 (50 mL), extracted
with CH2Cl2, washed with H2O, dried and the solvent
removed. Chromatography (5% MeOH/CH2Cl2) yielded
(S)-N-[3-[3-Fluoro-4-{N-(5-isoxazolylcarbonyl)piperdinyl-
4 - oxy}phenyl] - 2 - oxo - 5 - oxazolidinyl]methyl]acetamide
(21). This was prepared according to the procedure for
10 utilizing isoxazole-5-carbonyl chloride instead of
benzyloxyacetyl chloride. Chromatography with 5%
1
MeOH/CH2Cl2 afforded 21 as a white foam (65%). H
109 mg (32%) of 17 as a white foam; mp 78–82 ꢀC. H
NMR d 8.31 (d, J=1.8 Hz, 1H), 7.49 (dd, J=12.9, 2.6
Hz, 1H), 7.08–7.12 (m, 1H), 7.01 (t, J=8.8 Hz, 1H),
6.77 (d, J=1.8 Hz, 1H), 6.04 (t, J=6.0 Hz, 1H), 4.73–
4.81 (m, 1H), 4.52–4.57 (m, 1H), 4.03 (t, J=9.0 Hz, 1H),
3.56–3.95 (m, 7H), 2.03 (s, 3H), 1.75–2.00 (m, 4H). MS
[M+H]+ 447. Anal. calcd for C21H23FN4O6: C, 56.50;
H, 5.19; N, 12.55. Found: C, 56.13; H, 5.05; N, 12.61.
1
NMR d 7.49 (dd, J=13.0, 2.6 Hz, 1H), 7.07–7.10 (m, 1H),
7.00 (t, J=8.8 Hz, 1H), 5.94 (br s, 1H), 5.34 (br s, 1H),
4.75–4.82 (m, 1H), 4.43–4.52 (m, 1H), 3.99–4.06 (m, 3H),
3.61–3.78 (m, 6H), 3.38–3.41 (m, 1H), 2.98 (s, 3H), 2.03
(s, 3H), 1.85–1.93 (m, 4H). MS [M+H]+ 487. Anal. calcd
for C20H27FN4O7S/0.1H2O: C, 49.19; H, 5.61; N, 11.47.
Found: C, 48.98; H, 5.39; N, 11.09.
(S)-N-[3-[3-Fluoro-4-{N-(2-pyridoyl)piperidinyl-4-oxy}-
phenyl]-2-oxo-5-oxazolidinyl]methyl] acetamide (22). This
was prepared according to the procedure for 10 utilizing
picolinoyl chloride instead of benzyloxyacetyl chloride.
Isolated as an off-white solid, 190 mg (69%); mp 55–
58 ꢀC. 1HNMR d 8.59 (d, J=4.8 Hz, 1H), 7.81 (t,
J=7.5 Hz, 1H), 7.64 (d, J=7.5 Hz, 1H), 7.48 (dd,
J=12.9, 2.5 Hz, 1H), 7.35 (dd, J=7.1, 5.5 Hz, 1H),
7.06–7.11 (m, 1H), 7.01 (t, J=8.8 Hz, 1H), 6.02 (br t,
1H), 4.72–4.77 (m, 1H), 4.50–4.55 (m, 1H), 4.03 (t,
J=8.8 Hz, 1H), 3.50–3.99 (m, 7H), 2.03 (s, 3H), 1.80–
1.98 (m, 4H). MS [M+H]+ 457. Anal. calcd for
C23H25FN4O5/0.2CH2Cl2: C, 58.86; H, 5.41; N, 11.83.
Found: C, 59.03; H, 5.59; N, 11.47.
(S)-N-[3-[3-Fluoro-4-{N-(ꢀ-N-acetylaminoacetyl)piperidi-
nyl-4-oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide
(18). To a solution of N-acetylglycine (74 mg, 0.63
mmol) in CH2Cl2 (10 mL) was added EDCI (125 mg,
0.65 mmol) and the reaction stirred at room tempera-
ture for 2 h. Then a solution of 9 (304 mg, 0.65 mmol)
and NEt3 (0.15 mL, 1.07 mmol) in CH2Cl2 (10 mL) was
added and the reaction stirred at room temperature for
3 h. The reaction was poured into H2O (10 mL) and
extracted with CH2Cl2. The combined organic layers
were dried and the solvent evaporated to yield the crude
product. Chromatography (5% MeOH/CH2Cl2) yielded
161 mg (57%) of 18 as a white foam; mp 66–68 C. H
NMR d 7.47 (dd, J=13.0, 2.6 Hz, 1H), 7.08–7.10 (m,
1H), 6.99 (t, J=8.8 Hz, 1H), 6.61 (br s, 1H), 5.98 (br t,
J=6.0 Hz, 1H), 4.71–4.79 (m, 1H), 4.49–4.52 (m, 1H),
4.06–4.15 (m, 2H), 4.03 (t, J=9.0 Hz, 1H), 3.58–3.78
(m, 6H), 3.36–3.45 (m, 1H), 2.06 (s, 3H), 2.03 (s, 3H),
1.84–1.90 (m, 4H). MS [M+H]+ 451. Anal. calcd for
C21H27FN4O6/0.3CH2Cl2: C, 53.75; H, 5.85; N, 11.77.
Found: C, 53.85; H, 5.96; N, 11.62.
ꢀ
1
(S)-N-[3-Fluoro-[4-{N-(pyridin-2-ylmethoxyacetyl)piperi-
dinyl-4-oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]aceta-
mide (23). This was prepared via the a-chloroacetamide.
(S)-N-[3-[4-{N-(Chloroacetyl)piperidinyl-4-oxy}phenyl]-
2-oxo-5-oxazolidinyl]methylacetamide, prepared accord-
ing to the procedure of 10, was isolated as a viscous oil.
To NaH(60% in oil; 117 mg; 2.93 mmol) in anhydrous
THF (5 mL) at 0 ꢀC, was added dropwise pyridine-
2-methanol (0.24 mL, 2.47 mmol) in THF (5 mL). After
stirring for 15 min, chloroacetamide (523 mg, 1.22
mmol) in anh THF (5 mL) was added in one portion.
The reaction was warmed to room temperature and
stirred for 72 h. The reaction was poured into water (50
mL) and extracted CH2Cl2 (3Â75 mL). The combined
organic layers were dried and evaporated. Purification
by chromatography (5% MeOH/CH2Cl2) yielded 403
(S)-N-[3-[3-Fluoro-4-{N-(2-thienylcarbonyl)piperidinyl-
4-oxy}phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide (19).
This was prepared according to the procedure for 10
utilizing thiophene-2-carbonyl chloride instead of ben-
zyloxyacetyl chloride. Pure 19 was isolated as a beige
foam (63%); mp 48–51 ꢀC. HNMR d 7.44–7.51 (m,
1
2H), 7.28–7.31 (m, 1H), 6.98–7.07 (m, 3H), 6.11 (br t,
J=6.0 Hz, 1H), 4.74–4.79 (m, 1H), 4.49–4.53 (m, 1H),
4.03 (t, J=9.0 Hz, 1H), 3.56–3.95 (m, 6H), 2.88–3.09
(m, 1H), 2.03 (s, 3H), 1.86–1.97 (m, 4H). MS [M+H]+
462. Anal. calcd for C22H24FN3O5S: C, 57.26; H, 5.24;
N, 9.10. Found: C, 57.23; H, 5.24; N, 8.78.
1
mg (59%) of 23 as a yellow semi-solid. HNMR d 8.54
(d, J=4.2 Hz, 1H), 7.72 (t, J=7.7 Hz, 1H), 7.45–7.49
(m, 2H), 7.21 (t, J=6.1 Hz, 1H), 7.07–7.10 (m, 1H), 7.00
(t, J=8.8 Hz, 1H), 6.01 (br t, J=5.8 Hz, 1H), 4.75–4.78
(m, 1H), 4.73 (s, 2H), 4.44–4.48 (m, 1H), 4.31 (s, 2H),
4.02 (t, J=8.9 Hz, 1H), 3.58–3.79 (m, 6H), 3.42–3.45
(m, 1H), 2.03 (s, 3H), 1.85–1.90 (m, 4H). MS [M+H]+
501. Anal. calcd for C25H29FN4O6/0.7CH2Cl2: C,
55.12; H, 5.47; N, 10.01. Found: C, 55.17; H, 5.67; N,
10.21.
(S)-N-[3-[3-Fluoro-4-{N-(2-furoyl)piperdinyl-4-oxy}phenyl]-
2-oxo-5-oxazolidinyl]methyl]acetamide (20). This was
prepared according to the procedure for 10 utilizing
2-furoyl chloride instead of benzyloxyacetyl chloride.
Trituration with warm ether afforded 20 as a white solid

M. A. Weidner-Wells et al. / Bioorg. Med. Chem. 10 (2002) 2345–2351
2351
(S)-N-[3-Fluoro-[4-{N-(pyridin-3-ylmethoxyacetyl)piperi-
dinyl-4-oxy}phenyl]-2-oxo-5-oxazolidinyl]methylaceta-
mide (24). This was prepared according to the
procedure for 23 utilizing pyridine-3-methanol instead
of pyridine-2-methanol. Chromatography with 3%
were performed according to National Committee for
Clinical Laboratory Standards methods.9
Mouse protection assay
1
MeOH/CH2Cl2 afforded 24 as a clear glass (43%). H
In vivo efficacy was assessed in a murine septicemia
model of infection caused by S. aureus Smith. Female
Swiss–Webster mice were infected ip with approxi-
mately 6Â105 CFU/mL of the challenging strain. Pro-
tecting compounds were administered subcutaneously in
40% hydroxypropyl-b-cyclodextrin at 1 and 3 h after
infection. The dose allowing survival of 50% of the
animals (ED50) was calculated using the Logistic routine
of the SAS suite of statistical programs.
NMR d 8.56–8.60 (m, 2H), 7.73 (d, J=7.8 Hz, 1H), 7.47
(dd, J=13.0, 2.6 Hz, 1H), 7.30 (dd, J=7.8, 5.1 Hz, 1H),
7.08 (dd, J=8.9, 1.6 Hz, 1H), 6.99 (t, J=8.9 Hz, 1H),
6.02 (t, J=6.2 Hz, 1H), 4.70–4.78 (m, 1H), 4.64 (s, 2H),
4.43–4.47 (m, 1H), 4.24 (s, 2H), 4.02 (t, J=8.9 Hz, 1H),
3.57–3.78 (m, 6H), 3.35–3.45 (m, 1H), 2.02 (s, 3H),
1.80–1.96 (m, 4H). MS [M+H]+ 501. Anal. calcd for
C25H29FN4O6/0.25CH2Cl2: C, 58.13; H, 5.70; N, 10.74.
Found: C, 58.24; H, 5.73; N, 11.04.
(S)-N-[3-Fluoro[4-{N-(pyridin-4-ylmethoxyacetyl)piperi-
dinyl-4-oxy}phenyl]-2-oxo-5-oxazolidinyl]methylacetamide
(25). This was prepared according to the procedure for
23 utilizing pyridine-4-methanol instead of pyridine-
2-methanol. Chromatography using 5% MeOH/
Acknowledgements
The authors wish to thank Ellyn Wira and Jeffrey Fer-
nandez for in vitro and in vivo technical assistance,
respectively. In addition, we wish to thank Dr. Mark J.
Macielag for suggestions and his critical reading of the
manuscript.
1
CH2Cl2, afforded 25 as a white foam (63%). HNMR
(CDCl3) d 8.59 (d, J=5.9 Hz, 2H), 7.47 (dd, J=12.9,
2.6 Hz, 1H), 7.28 (d, J=5.9 Hz, 2H), 7.07–7.11 (m, 1H),
6.99 (t, J=8.8 Hz, 1H), 5.91–5.94 (m, 1H), 4.72–4.79
(m, 1H), 4.65 (s, 2H), 4.45–4.49 (m, 1H), 4.26 (s, 2H),
4.02 (t, J=8.9 Hz, 1H), 3.40–3.78 (m, 7H), 2.02 (s, 3H),
1.85–1.95 (m, 4H). MS [M+H]+ 501. Anal. calcd for
C25H29FN4O6/0.25CH2Cl2: C, 58.13; H, 5.70; N, 10.74.
Found: C, 57.92; H, 5.61; N, 10.96.
References and Notes
1. Centers for Disease Control and Prevention. MMWR
Morb Mortal Wkly. Rpt. 1999, 47, 1.
2. Gregory, W.; Brittelli, D.; Wang, C.-L.; Wuonola, M.;
McRipley, R.; Eustice, D.; Eberly, V.; Bartholomew, P.; Slee,
A.; Forbes, M. J. Med. Chem. 1989, 32, 1673.
Bacterial strains
3. Brickner, S.; Hutchinson, D.; Barbachyn, M.; Manninen, P.;
Ulanowicz, D.; Garmon, S.; Grega, K.; Hendges, S.; Toops,
D.; Ford, C.; Zurenko, G. J. Med. Chem. 1996, 39, 673.
4. Shinabarger, D.; Marotti, K.; Murray, R.; Lin, A.; Mel-
chior, E.; Swaney, S.; Dunyak, D.; Demyan, W.; Buysse, J.
Antimicrob. Agents Chemother. 1997, 41, 2132.
5. Clemett, D.; Markham, A. Drugs 2000, 59, 815.
6. Genin, M. Exp. Opin. Ther. Pat. 2000, 10, 1405.
7. Weidner-Wells, M.; Boggs, C.; Foleno, B.; Wira, E.; Bush,
K.; Goldschmidt, R.; Hlasta, D. Bioorg. Med. Chem. Lett.
2001, 11, 1829.
A set of nine strains was used as the primary screening
panel: S. aureus OC 4172 (Smith strain) and ATCC
29213, are methicillin susceptible; OC 2878 and OC
3726 (COL strain) are methicillin resistant (MRSA);
E. faecalis ATCC 29212 and E. faecium OC 3312 are
susceptible and resistant to vancomycin, respectively;
E. coli OC 2605 (strain KL16) and OC 2530 (LPS-
defective); Pseudomonas aeruginosa ATCC 27853. Other
strains used herein were clinical isolates from the
Johnson and Johnson Pharmaceutical Research and
Development, LLC culture collection.
8. Pae, A. N.; Kim, H. Y.; Joo, H. J.; Kim, B. H.; Cho, Y. S.;
Choi, K. I.; Choi, J. H.; Koh, H. Y. Bioorg. Med. Chem. Lett.
1999, 9, 2679.
9. National Committee for Clinical Laboratory Standards.
Methods for Dilution Antimicrobial Susceptibility Tests for
Bacteria that Grow Aerobically, 4th ed.; Approved standard:
NCCLS Document M7-A4; National Committee for Clinical
Laboratory Standards: Villanova, PA, USA, 1997.
Microbiological methods
Broth microdilution MIC (lowest concentration of
compound inhibiting visible growth) determinations