Synthesis and structure-activity relationships of N-{1-[(6-fluoro-2-naphthyl)methyl]piperidin-4-yl}benzamide derivatives as novel CCR3 antagonists

Article abstract of DOI:10.1016/j.bmc.2007.10.003

A novel class of potent CCR3 receptor antagonists were designed and synthesized starting from N-{1-[(6-fluoro-2-naphthyl)methyl]piperidin-4-yl}benzamide (1),which was found by subjecting our chemical library to high throughput screening (HTS). The CCR3 in

Full text of DOI:10.1016/j.bmc.2007.10.003

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry 16 (2008) 144–156
Synthesis and structure–activity relationships of N-{1-[(6-fluoro-
2-naphthyl)methyl]piperidin-4-yl}benzamide derivatives
as novel CCR3 antagonists
Ippei Sato,a,* Koichiro Morihira,a Hiroshi Inami,a Hirokazu Kubota,a
Tatsuaki Morokata,a Keiko Suzuki,a Noritaka Hamada,a Yosuke Iura,b Aiko Nitta,b
Takayuki Imaoka,b Toshiya Takahashi,b Makoto Takeuchi,a
Mitsuaki Ohtaa and Shin-ichi Tsukamotoa
aDrug Discovery Research, Astellas Pharma Inc., 21 Miyukigaoka, Tsukuba-shi, Ibaraki 305-8585, Japan
bPharmaceutical Research Laboratories, Toray Industries Inc., 6-10-1 Tebiro, Kamakura, Kanagawa 248-8555, Japan
Received 6 September 2007; revised 26 September 2007; accepted 2 October 2007
Available online 5 October 2007
Abstract—A novel class of potent CCR3 receptor antagonists were designed and synthesized starting from N-{1-[(6-fluoro-2-naph-
thyl)methyl]piperidin-4-yl}benzamide (1),which was found by subjecting our chemical library to high throughput screening (HTS).
The CCR3 inhibitory activity of the synthesized compounds against eotaxin-induced Ca2+ influx was evaluated using CCR3-
expressing preB cells. Systematic chemical modifications of 1 revealed that the 6-fluoro-2-naphthylmethyl moiety was essential
for CCR3 inhibitory activity in this new series of CCR3 antagonists. Further structural modifications of the benzamide and piper-
idine moieties of 1 led to the identification of N-{8-[(6-fluoro-2-naphthyl)methyl]-8-azabicyclo[3.2.1]oct-3- yl}biphenyl-2-carboxam-
ide (31) as a potent CCR3 antagonist with an IC50 value of 0.020 lM.
ꢀ 2007 Elsevier Ltd. All rights reserved.
1. Introduction
mokines, CXC chemokines, C chemokines, and CX3C
chemokines, based on their structure. Their biological
activity is mediated through seven-transmembrane G-
protein coupled receptors (GPCRs) on the surface of im-
mune and inflammatory cells. These receptors (CCR1-
11, CXC1-6, XCR1, CX3C1) have been cloned and
characterized. Among them, CCR3, a CC chemokine
receptor subtype, is thought to play an important role
in the migration, activation, and degranulation of
inflammatory cells, such as eosinophils, mast cells, baso-
phils, and Th-2 cells.2a–e
One of the pathological features of various inflamma-
tory diseases, such as allergic asthma and atopic derma-
titis, is infiltration of eosinophils to the sites of
inflammation. In particular, asthma is a reversible
inflammatory disease that repeatedly caused airway
obstruction and enhances airway hyper-responsiveness
caused by an injury to the airway epithelium, which is
induced by injurious proteins, chemical mediators, and
inflammatory mediator released from activated
eosinophils.1a,b
Studies on CCR3 gene KO mice as animal models of
allergic asthma and atopic dermatitis demonstrated that
the infiltration of eosinophils into lung and dermal tis-
sues and the enhancement of airway hyper-responsive-
ness are less than those of wild type mice.3
Furthermore, the antibody against eotaxin, a selective
CCR3 ligand, in vivo reduces the accumulation of eosin-
ophils in the lung that occurs in response to ovalbumin.4
‘Chemokine’ is a generic term for small (8–12 kDa), hep-
arin-binding, basic proteins that induce the migration
and activation of leukocytes and macrophages, respec-
tively. They are classified into four sub-families, CC che-
Keywords: Allergic diseases; CCR3 antagonists; 6-fluoro-2-naphthyl-
methyl moiety; Nortropane derivatives.
These factors suggest that CCR3 antagonists, which
selectively suppress the activation of inflammatory cells,
*
Corresponding author. Tel.: +81 29 863 6732; fax: +81 29 852
5387; e-mail: ippei.sato@jp.astellas.com
0968-0896/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2007.10.003

I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
145
may have therapeutic potentials for treating diseases,
such as allergic asthma and atopic dermatitis.
O
N
1
N
H
F
To develop a new therapeutic drug for the treatment of
the inflammatory diseases described above, a research
program was started in an attempt to discover a novel
type of CCR3 antagonist. First, our chemical library
was subjected to HTS, which resulted in the discovery
Cl
Cl
O
N
S
N
N
H
of a lead compound with moderate activity (IC50
=
S
2
1.3 lM), N-{1-[(6-fluoro-2-naphthyl)methyl]piperidin-
4-yl}benzamide (1). (Fig. 1). The results of the work
on synthesis, the structure–activity relationship (SAR),
and the biological activity of each of the N-{1-[(6-flu-
oro-2-naphthyl)methyl]piperidin-4-yl}benzamide deriv-
atives are described herein.
H2N
Cl
OMe
H
OH
MeO
MeO
O
N
N
N
H
H
3
2. Chemistry
Me
HN
O
O
The syntheses of the compounds are summarized in
Schemes 1–7.
N
NH
NH
The N-(1-alkylpiperidin-4-yl)benzamide derivatives
(6b–e) were prepared from the amine (5) by reductive
alkylation with appropriate aldehydes. In the case of
6f and 6g, compound 5 was alkylated with 2-(bromo-
methyl)-6-fluoroquinoline5 and 3-chloro-40-fluoropro-
piophenone, respectively (Scheme 1).
F
O
Me
4
Alkylation of the amine (7) with the bromide (8)6 in the
presence of K2CO3, followed by removal of the Boc
group, yielded the intermediate amine (9). The benzyl
amine (10) was obtained by reductive alkylation of 9
with the benzaldehyde. Condensation of 9 with the ben-
zenesulfonyl chloride and the (2E)-3-phenylacryloyl
chloride yielded compounds 11 and 12, respectively
(Scheme 2).
Figure 1. Structure of compound 1 and previously reported CCR3
antagonists (2,8a,b 3,8c and 48d).
O
NH
O
Ar
a or b
N
N
H
N
H
HCl
5
6b-g
The synthesis of compound 15 is shown in Scheme 3.
Alkylation of the amine (13) with 8, followed by hydro-
lysis with NaOH in EtOH, yielded the carboxylic acid
Scheme 1. Synthesis of compounds 6b–g. Reagents and conditions: (a)
aldehyde, NaBH(OAc)3, AcOH, THF/CH2Cl2, rt; (b) in the case of 6f
and 6g: alkyl halide, K2CO3, EtOH, reflux.
a, b
c, d
N
2HCl
N
NH
Br
+
Boc
H2N
F
N
F
N
F
2HCl
H
H
9
10
7
8
f
e
N
O
N
O
O
S
N
F
N
F
H
H
11
12
Scheme 2. Synthesis of compounds 10–12. Reagents and conditions: (a) K2CO3, MeCN, rt, 20 h, 76%; (b) 4 M HCl/EtOAc, EtOAc, rt, 90%; (c)
PhCHO, NaBH(OAc)3, CH2Cl2, rt, 8 h; (d) 4 M HCl/EtOAc, 57% for two steps; (e) PhSO2Cl, DIPEA, CH2Cl2, rt, overnight, 41% (f) cinnamoyl
chloride, Et3N, CH2Cl2, rt, overnight, 56%.
a, b
c
N
NH
N
H
N
O
HO
F
F
O
O
O
13
14
15
Scheme 3. Synthesis of compounds 15. Reagents and conditions: (a) 8, K2CO3, EtOH, rt, overnight, 72%; (b) 1 N NaOH, EtOH, rt, 4h, 50%; (c)
aniline, WSCÆHCl, HOBt, Et3N, CH2Cl2, rt, overnight, 68%.

146
I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
b, c
a
O
N
NH
N
N
X
F
HO
HO
F
F
(HCl)
H
16
17
d
18: X = O
19: X = NH
N
H2N
2HCl
9
Scheme 4. Synthesis of compounds 18 and 19. Reagents and conditions: (a) 8, Et3N, CHCl3, rt, 4 h, 84%; (b) PhNCO, toluene, reflux, 11 h; (c) 4 M
HCl/EtOAc, 40% for two steps; (d) PhNCO, DIPEA, CH2Cl2, rt, overnight, 68%.
a or b
c
R
O
N
R
O
N
N
N
F
N
Me
F
H2N
F
H
4
2
2HCl
3
9
1, 20a-l
21: R = H
Scheme 5. Synthesis of compounds 20a–l and 21. Reagents and conditions: (a) ArCOCl, base; (b) ArCOOH, WSCÆHCl, HOBt, CH2Cl2; (c) NaH,
DMF, rt, 1.5 h, then MeI, rt, 5 h, 47%.
HCl
a
b, c, d
N
NH
HO
HO
O
F
22
23
O
H
N
e
N
N
NH
H2N
F
=
O
Me
F
Me
N
Me
hemifumalate
F
24
25
Scheme 6. Synthesis of compounds 25. Reagents and conditions: (a) 8, K2CO3, DMF, rt, 78%; (b) MeLi, Et2O, ꢀ70 ꢁC, 90%; (c) MeCN, H2SO4, rt,
93%; (d) 3 M HCl, 100 ꢁC, quant; (e) biphenyl-2-carboxylic acid, WSCÆHCl, HOBt, 1,2-dichloroethane, rt; (f) fumaric, acid, 31% for two steps.
O
O
a, b
HCl
NH
c
NH2
NH
NH
N
N
F
F
26:exo isomer
28:exo isomer
30:exo isomer
a, b
c, d
oxalate
O
H2N
O
N
N
N
N
NH
H
H
HCl
27:endo isomer
29:endo isomer
31:endo isomer
Scheme 7. Synthesis of compounds 30 and 31. Reagents and conditions: (a) biphenyl-2-carboxylic acid, WSCÆHCl, HOBt, DMF; (b) H2, 10 wt%
Pd(OH)2/C, 4 M HCl/EtOAc, rt; (c) 8, K2CO3, rt; (d) oxalate, MeOH.
(14). Compound 14 was transformed into the target
compound (15) by condensation with aniline.
(19) was synthesized with 18 from 9 in the same
manner.
Scheme 4 illustrates the synthesis of the carbamate
(18) and the urea (19). Compound 16 was alkylated
with 8 and the subsequent reaction with the pheny-
lisocyanate afforded the carbamate (18). The urea
The condensation of 9 with acids or acid chlorides
yielded the 6-fluoro-2-naphthylmethyl derivatives (20a–
l). Compound 21 was prepared by methylating 1 using
MeI (Scheme 5).

I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
147
Compound 25 was prepared from 22 in five steps, as fol-
lows: alkylation with 8, methylation by MeLi, the Ritter
reaction with MeCN and H2SO4, condensation with
biphenyl-2-carboxylic acid, and then crystallization as
a hemifumarate.
protons at the bridge of the 8-azabicyclo[3.2.1]octane
ring (Hi).
The crystal of 31 suitable for X-ray analysis was pre-
pared by recrystallization as an oxalate from i-PrOH.
In addition, it was confirmed that the structure of 31
corresponded to the desired endo-isomer (Fig. 3).
Amines 267 and 277 were reacted with the biphenyl-2-
carboxylic acid followed by deprotection of the benzyl
group to yield the amines 28 and 29, respectively. Com-
pounds 28 and 29 were converted into the exo-derivative
(30) and the endo-derivative (31), respectively, by alkyl-
ation with 8 (Scheme 7).
The conformation analyses of 20j, 25, 30, and 31 using
NMR were performed as described below (Fig. 2). Since
the methylene protons of the piperidine ring (Ha and
Hb) of 20j had a vicinal coupling constant (Jab) of more
than 12 Hz, the piperidine ring seemed to adopt the
chair form as the most stable conformation. As for 25,
nuclear Overhauser effects (NOEs) between the methyl
group of the piperidine ring and the methylene protons
at the 3-position of the piperidine ring (Hc) were ob-
served; however, no NOEs were observed between the
methyl group and the methylene protons at the 2-posi-
tion of the piperidine ring (Hd). And for the same rea-
son as 20j, the piperidine ring seemed to adopt the
chair form as the most stable conformation. These indi-
cated that the methyl group of 25 should occupy the
equatorial position at the 4-position of the piperidine
ring, and its benzamide group should occupy the axial
position. With respect to the conformation of 30, the
NOEs were observed between the amide proton at 30
and the methylene protons at the bridge of the 8-azabi-
cyclo[3.2.1]octane ring (He). Furthermore, the methine
proton at the 3-position of the 8-azabicyclo[3.2.1]octane
ring (Hf) did not adopt the axial conformation, since the
coupling constant of this methine proton (Jf) was less
than 6 Hz. As a result of these NMR analyses, the most
stable conformation of 30 was thought to be as shown in
Figure 2. The most stable conformation of 31 is believed
to be as shown in Figure 2, since NOEs were observed
between the methine proton at the 3-position of the 8-
azabicyclo[3.2.1]octane ring (Hg) and the methylene
Figure 3. Displacement ellipsoid plot of 31 drawn at the 30%
probability level.
Jab > 12 Hz
Jf < 6 Hz
Hb
O
O
He
NH
N
N
H
Ha
Hf
F
N
F
20j
30
O
Jcd > 12 Hz
F
Hi
Hd
NH
O
Hg
Me
N
N
N
H
Hc
F
25
31
NOE relationship
Figure 2. Conformation of 20j, 25, 30, and 31.

148
I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
3. Results and discussion
therefore a strategy for structural optimization was
planned as follows: (1) replace the 6-fluoro-2-naphthyl-
methyl moiety at the terminal of 1 with the other aryl
ring, (2) structural modification of the linker moieties
at the center of 1, (3) introduction of substituents onto
the benzamide moiety at another terminal.
The synthesized compounds were evaluated for their
inhibitory activity (IC50) on eotaxin-induced Ca2+ influx
by using CCR3-expressing preB cells. The lead com-
pound (1) displayed moderate CCR3 inhibitory activity
with an IC50 value of 1.3 lM.
First, the effects of replacing the 6-fluoro-2-naphthyl-
methyl moiety of 1 with another aryl ring were explored
(Table 1). The naphthalene (6a),9 which removed a fluo-
rine atom from 1, had no inhibitory effect at the concen-
tration of 10 lM. The 2-MeO-naphthalene (6b) and the
4-fluorobenzyl derivative (6c) also had no inhibitory ef-
fect at that concentration. Furthermore, introduction of
the cinnamoyl (6d), the fluoroquinoline (6f), and the ke-
tone (6g) caused severe losses of activity. In Table 1,
only compound 6e, which introduced a fluorine atom
into the cinnamoyl moiety of 6d, showed moderate
activity (IC50 value = 3.4 lM). These results suggest that
the existence of a heteroatom between the nitrogen atom
in the piperidine ring and the terminal fluorine atom
would not be tolerated (6f and 6g), and that the terminal
fluorine atom would play an important and significant
role in CCR3 inhibitory activity (6a vs. 1 and 6d vs.
6e). The 6-fluoro-2-naphthylmethyl group shows the
strongest CCR3 inhibitory activity in this table.
Many of the CCR3 antagonists that have been reported
recently have one of two structural features in common
with the lead compound (1). One is having a basic nitro-
gen atom in the center of the molecule, and the other is
having aryl rings at each terminal of the molecule
(Fig. 1).8a–d This common structural feature seems to
be the key pharmacophore for CCR3 inhibitory activity,
Table 1. CCR3 inhibitory activities of benzamide derivatives (1, 6a–g)
O
N
Ar
N
H
Compound
Ar
IC50a (lM)
1
6-F-2-Naphthyl
2-Naphthyl
6-MeO-2-naphthyl
1.3 0.034
N.Eb
N.Eb
6a
6b
Next, the influence of the linker between the basic nitro-
gen atom in the piperidine and the phenyl ring of 1 was
investigated (Table 2). All compounds with linker
lengths of two atoms, such as benzylamine (10), sulfon-
amide (11), reverse amide (15), and N-methyl amide
(21), inhibited the CCR3 receptor to a degree compara-
ble to 1. In contrast, all derivatives with linkages of three
atoms or more (12, 18, and 19) were weak inhibitors.
These observations indicate that the distance between
the terminal phenyl ring and the basic nitrogen atom
6c
6d
N.Eb
N.Eb
F
6e
6f
3.4 0.30
N.Eb
F
N
F
O
6g
N.Eb
Table 3. CCR3 inhibitory activities of substituted benzamide deriva-
tives (20a–l)
F
a IC50 values are shown with SE (number of determinations) when
more than three determinations were made.
b No effect at 10 lM.
O
N
R
F
N
H
2
4
3
Compound
R
IC50a (lM)
Table 2. CCR3 inhibitory activities of 6-fluoro-2-naphthylmethyl
derivatives (10–12, 15, 18, 19, 21)
1
H
1.3 0.034
2.9 0.67
0.67 0.20
0.64 0.27
0.72 0.34
3.5 1.0
20a
20b
20c
20d
20e
20f
20g
20h
20i
20j
20k
20l
2-F
3-F
4-F
N
X
F
2-MeO
3-MeO
4-MeO
2-PhO
3-PhO
4-PhO
2-Ph
Compound
X
IC50a (lM)
1
–CONH–
–CH2NH–
1.3 0.034
0.60 0.11
0.83 0.071
1.7 0.088
0.81 0.19
9.7 3.7
2.4 0.63
0.095 0.026
1.1 0.37
40%b
10
11
15
21
12
18
19
–SO2NH–
–NHCO–
–CONMe–
0.038 0.0054
N.E.c
27%b
–(E)–CH@CH–CONH–
–NHCOO–
–NHCONH–
3-Ph
4-Ph
4.8 1.1
31%b
a IC50 values are shown with SE (number of determinations) when
more than three determinations were made.
b % inhibition at 10 lM.
a IC50 values are shown with SE (number of determinations) when
more than three determinations were made.
b % inhibition at 10 lM.
c No effect at 10 lM.

I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
149
Table 4. CCR3 inhibitory activities of 6-fluoronaphthalene derivatives
(25, 30, and 31)
prove if the conformation was constrained like that of
20j. To that end, nortropane derivatives 30 and 31 were
designed and synthesized. As expected, the endo-isomer
(30), which should have had the same conformation as
25 and been the most stable, had an inhibitory activity
equal to that of 25, and the exo-isomer (31), which
should have the same inhibitory activity as 20j, was
the most potent against the CCR3 receptor among this
series, with an IC50 value of 0.020 lM. Since it was eas-
ier for 31 to adopt the active conformation, the CCR3
inhibitory activity of 31 was approximately two times
more potent than that of 20j (Fig. 3).
Compound Structure
IC50a (lM)
O
20j
0.038 0.0054
N
N
H
F
O
25
2.8 0.97
NH
Me
N
Inhibitory activity against other CC chemokines,
CCR1, CCR2, and CCR5, of 31 was also evaluated.
The results showed that compound 31 had a 40% inhi-
bition rate against CCR1 at the concentration of
10 lM, but had no effect on CCR2 or CCR5 at that
concentration. Thus, 31 proved to be a selective and
potent CCR3 antagonist.
F
O
H
30
31
NH
H
2.7 1.4
N
F
Further biological, pharmacokinetic and pharmacotoxic
evaluation for 31 are now being carried out.
O
0.020 0.0039
N
H
N
F
a IC50 values are shown with SE (number of determinations) when
more than three determinations were made.
4. Conclusions
In an attempt to discover new potent CCR3 antagonists, a
series of N-{1-[(6-fluoro-2-naphthyl)methyl]piperidin-4-
yl}benzamide derivatives were synthesized and evaluated.
The results of the SAR studies in this series indicated that
6-fluoronaphthalene-2-ylmethyl moiety was essential for
potent CCR3 inhibitory activity. Furthermore, hydro-
phobicandbulkygroupsprovedtobeappropriatesubstit-
uents at the 2-position of the benzamide moiety, and the
nortropane ring was shown to be more suitable for the
cyclic amine moiety than the flexible piperidine ring.
Consequently, exo-N-{8-[(6-fluoro-2-naphthyl)methyl]-
8-azabicyclo[3.2.1]oct-3-yl} biphenyl-2-carboxamide (31)
was determined to be a novel lead compound in search
for more potent CCR3 antagonists to be used as therapeu-
tic agents for allergic diseases.
is the important factor determining the inhibitory po-
tency, not which atoms are present in the linker moiety.
In Table 3, the effects of various substituents around the
phenyl moiety of 1 were examined. The introduction of
a fluorine atom at the 3- or 4-position on the phenyl ring
of 1 (20b and 20c) slightly enhanced the inhibitory activ-
ity, whereas the introduction of a fluorine atom at the
2-position (20a) slightly reduced it. In contrast to these
results, the incorporation of the methoxy group at the
3- or 4-position on the phenyl ring of 1 (20e and 20f)
slightly reduced inhibitory activity, while at the 2-posi-
tion (20d) inhibitory activity was slightly enhanced.
The phenoxy and phenyl groups around the phenyl ring
of 1 displayed the same tendency as the methoxy group.
The 2-phenoxy and the 2-phenyl derivatives (20g and
20j) led to about 14-fold and 34-fold increases in
activity, respectively, compared to 1. These results indi-
cated that the hydrophobic and bulky groups would be
suitable substituents at the 2-position, but there might
be steric limitations around the 3- and 4-position.
5. Experimental
5.1. Chemistry
In general, reagents and solvents were used as pur-
chased without further purification. Melting points
were determined with a Yanaco MP-500D melting
1
Finally, we focused on the conformation of 20j (shown
in Fig. 2). Compound 25 was designed and synthesized
to have a conformation different from that of 20j, specif-
ically, the most stable conformation. The piperidine ring
should have adopted to the chair form, and the benzam-
ide moiety should have occupied the axial position of
the piperidine ring. However, compound 25, which is a
two-atom-linkage derivative, was a weaker CCR3 recep-
tor inhibitor than 20j (IC50 value = 2.8 lM) (Table 4).
These observations indicated that the most stable con-
formation of 20j is actually the active conformation.
Therefore, the expectation was that activity would im-
point apparatus and left uncorrected. H NMR spec-
tra were recorded on a JEOL JNM-LA300 or a JEOL
JNM-EX400 spectrometer. Chemical shifts were ex-
pressed in d (ppm) values with tetramethylsilane as
an internal standard (NMR descriptions; s, singlet;
d, doublet; t, triplet; dt, double triplet; m, multiplet,
and br, broad peak). Mass spectra were recorded on
a JEOL JMS-LX2000 spectrometer. The elemental
analyses were performed with a Yanaco MT-5 micro-
analyzer (C, H, N) and Yokogawa IC-7000S ion chro-
matographic analyzer (halogens) and were within
0.4% of theoretical values.

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I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
5.1.1. N-{1-[(6-Methoxy-2-naphthyl)methyl]piperidin-4-
yl}benzamide (6b). To solution of (300 mg,
for C21H23FN2O: C, 74.53; H, 6.85; N, 8.28; F, 5.61.
Found: C, 74.70; H, 6.91; N, 8.31; F 5.58.
a
5
1.25 mmol) in CH2Cl2 (3 mL), and THF (1 mL) were
added 6-methoxy-2-naphthaldehyde (255 mg 1.37
mmol), sodiumtriacetoxyborohydride (362 mg, 1.62
mmol) and AcOH (1 drop), and the mixture was stirred
at room temperature for 16 h. The mixture was parti-
tioned between CHCl3 and satd NaHCO3 aq and then
the organic layer was dried over MgSO4, filtered, and
concentrated in vacuo. The crude solid was recrystal-
lized from MeCN–CHCl3 to yield 6b (308 mg, 66%) as
a colorless powder: mp: 197–199 ꢁC (MeCN–CHCl3);
1H NMR (400 MHz, CDCl3) d: 1.53–1.63 (m, 2H),
1.99–2.07 (m, 2H), 2.18–2.27 (m, 2H), 2.86–2.93 (m,
2H), 2.80–2.88 (m, 2H), 3.63 (s, 2H), 3.92 (s, 3H),
3.99–4.09 (m, 1H), 5.94–6.02 (m, 1H), 7.10–7.16 (m,
2H), 7.39–7.52 (m, 4H), 7.65–7.78 (m, 5H); MS (FAB)
m/z = 375 [M+H]+. Anal. Calcd for C24H26N2O2: C,
76.98; H, 7.00; N, 7.48. Found: C, 77.02; H, 7.12; N,
7.54.
5.1.5.
N-{1-[(6-Fluoroquinolin-2-yl)methyl]piperidin-4-
yl}benzamide (6f). To a solution of 5 (300 mg, 1.25 mmol)
in EtOH (10 mL) were added 2-(bromomethyl)-6-fluoro-
quinoline5 (300 mg 1.25 mmol) and K2CO3 (517 mg,
3.74 mmol), and the mixture was stirred at reflux for
3 h. The mixture was cooled to rt and partitioned between
EtOAc and brine, and then the organic layer was dried
over MgSO4, filtered, and concentrated in vacuo. The
crude solid was recrystallized from MeCN to yield 6f
(288 mg, 63%) as a colorless powder. mp: 198–201 ꢁC;
1H NMR (400 MHz, DMSO-d6 d: 1.55–1.70 (m, 2H),
1.75–1.84 (m, 2H), 2.13–2.23 (m, 2H), 2.82–2.90 (m,
2H), 3.74–3.86 (m, 3H), 7.45 (dd, J = 7.8, 7.4 Hz, 2H),
7.48–7.54 (m, 1H), 7.63 (dd, J = 9.2, 2.4 Hz, 1H), 7.68
(d, J = 7.6 Hz, 2H), 7.77 (dd, J = 9.2, 2.4 Hz, 1H), 7.83
(d, J = 7.8 Hz, 2H ), 8.04 (dd, J = 6.0, 7.2 Hz, 1H), 8.25
(d, J = 7.6 Hz, 1H), 8.34 (d, J = 8.8 Hz, 1H); MS (FAB)
m/z = 364 [M+H]+. Anal. Calcd for C22H22FN3O: C,
72.71; H, 6.10; N, 11.56; F, 5.23. Found: C, 72.45; H,
6.12; N, 11.56; F, 5.25.
5.1.2. N-[1-(4-Fluorobenzyl)piperidin-4-yl]benzamide
(6c). Compound 6c was prepared from 5 and 4-fluoro-
benzaldehyde in a manner similar to that described for
compound 6b, with a yield of 40% as a colorless powder.
5.1.6.
N-{1-[3-(4-Fluorophenyl)-3-oxopropyl]piperidin-
1
mp: 145–147 ꢁC (EtOH–MeCN); H NMR (300 MHz,
4-yl}benzamide (6g). Compound 6g was prepared from
5 and 3-chloro-40-fluoropropiophenone in a manner
similar to that described for compound 6f, with a yield
of 11% as a colorless solid. mp: 150–156 ꢁC (MeCN);
1H NMR (300 MHz, CDCl3) d: 1.62–1.77 (m, 2H),
2.04–2.14 (m, 2H), 2.33–2.44 (m, 2H), 2.95 (t,
J = 7.2 Hz, 2H), 2.98–3.07 (m, 2H), 3.26 (t, J = 7.2 Hz,
2H), 4.00–4.14 (m, 1H), 6.06 (d, J = 7.2 Hz, 1H), 7.10–
7.17 (m, 2H), 7.39–7.54 (m, 3H), 7.72–7.78 (m, 2H),
7.96–8.04 (m, 2H); MS (FAB) m/z = 355 [M+H]+. Anal.
Calcd for C21H23FN2O2Æ0.5H2O: C, 69.40; H, 6.66; N,
7.71; F, 5.23. Found: C, 69.08; H, 6.47; N, 7.60; F 5.22.
CDCl3) d: 1.51 (dd, J = 11.4, 3.9 Hz, 1H), 1.59 (dd,
J = 11.1, 3.6 Hz, 1H), 1.98–2.08 (m, 2H), 2.17 (dt,
J = 11.7, 2.4 Hz, 2H), 2.78–2.88 (m, 2H), 3.48 (s, 2H),
3.95–4.08 (m, 1H), 5.93–6.03 (m, 1H), 6.96–7.05 (m,
2H), 7.24–7.32 (m, 1H), 7.39–7.53 (m, 3H), 7.72–7.77
(m, 2H); MS (FAB) m/z = 313 [M+H]+. Anal. Calcd
for C19H21FN2O: C, 73.05; H, 6.78; N, 8.97; F, 6.08.
Found: C, 72.95; H, 6.94; N, 9.02, F, 6.08.
5.1.3.
N-{1-[(2E)-3-Phenylprop-2-en-1-yl]piperidin-4-
yl}benzamide (6d). Compound 6d was prepared from 5
and (2E)-3-phenylacrylaldehyde in a manner similar to
that described for compound 6b, with a yield of 67% as
a colorless powder. mp: 165–168 ꢁC (MeCN–CHCl3);
1H NMR (400 MHz, CDCl3) d: 1.54 (ddd, J = 13.9,
11.2, 3.4 Hz, 2H), 2.04–2.11 (m, 2H), 2.15–2.24 (m,
2H), 2.92–3.00 (m, 2H), 3.17 (dd, J = 6.9, 1.0 Hz, 2H),
3.97–4.09 (m, 1H), 5.99 (d, J = 7.4 Hz, 1H), 6.28 (dt,
J = 15.6, 6.9 Hz, 1H), 6.53 (d, J = 15.6 Hz, 1H), 7.21–
7.25 (m, 1H), 7.28–7.35 (m, 2H), 7.36–7.46 (m, 4H),
7.47–7.53 (m, 1H), 7.73–7.78 (m, 2H); MS (FAB)
m/z = 321 [M+H]+. Anal. Calcd for C21H20N2O: C,
78.71; H, 7.55; N, 8.74. Found: C, 78.75; H, 7.67; N, 8.74.
5.1.7. 1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-amine
dihydrochloride (9). To a solution of tert-butyl piperi-
din-4-ylcarbamateÆHCl (14.2 g, 59.3 mmol) in MeCN
(200 mL) were added
8 (14.2 g 59.3 mmol) and
K2CO3 (24.6 g, 178 mmol), and the mixture was stirred
at room temperature for 20 h. This mixture was con-
centrated in vacuo. The residue was then partitioned
between EtOAc and H2O, and the organic layer was
washed with brine, dried over Na2SO4, filtered, and
concentrated in vacuo. The residue was purified by sil-
ica gel column chromatography (CHCl3–MeOH = 100/
0–95/5) to yield tert-butyl {1-[(6-fluoro-2-naph-
thyl)methyl]piperidin-4-yl} carbamate (16.2 g, 76%)
as a colorless solid. To a solution of compound
obtained above in EtOAc (200 mL) were added 4 M
HCl (g)/EtOAc (200 mL), and the mixture was stirred
at room temperature for 17.5 h. The precipitate was
collected by filtration, washed with EtOAc and Et2O,
and dried in vacuo to yield 9 (13.5 g, 90%) as a
colorless solid. 1H NMR (400 MHz, DMSO-d6) d:
1.94–2.19 (m, 4H), 2.50–3.50 (m, 5H), 4.40, 4.50
(each d, J = 5.2 Hz, 2H), 7.45–7.54. (m, 1H), 7.76–
7.89 (m, 2H), 7.98–8.06 (m, 2H), 8.16, 8.18 (each s,
1H), 8.35–8.64 (m, 3H), 11.20–11.46 (m, 1H); MS
(FAB) m/z = 259 [M+H]+.
5.1.4. N-{1-[(2E)-3-(4-Fluorophenyl)prop-2-en-1-yl]pip-
eridin-4-yl}benzamide (6e). Compound 6e was prepared
from 5 and (2E)-3-(4-fluorophenyl) acrylaldehyde10 in
a manner similar to that described for compound 6b,
with a yield of 71% as a colorless solid. mp: 181–
1
183 ꢁC (MeCN–CHCl3); H NMR (400 MHz, CDCl3)
d: 1.58 (ddd, J = 13.7, 11.2, 3.7 Hz, 2H), 2.03–2.11 (m,
2H), 2.15–2.24 (m, 2H), 2.95–3.00 (m, 2H), 3.16 (dd,
J = 6.8, 1.0 Hz, 2H), 3.97–4.09 (m, 1H), 5.99 (d,
J = 7.3 Hz, 1H), 6.20 (dt, J = 15.6, 6.8 Hz, 1H), 6.54
(d, J = 15.6 Hz, 1H), 6.97–7.03 (m, 2H), 7.31–7.38 (m,
2H), 7.40–7.47 (m, 2H), 7.48–7.53 (m, 1H), 7.73–7.78
(m, 2H); MS (FAB) m/z = 339 [M+H]+. Anal. Calcd

I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
151
5.1.8. N-Benzyl-1-[(6-fluoro-2-naphthyl)methyl]piperidin-
4-amine (10). A solution of 9 (600 mg, 1.81 mmol) in
EtOAc (50 mL) were washed with satd NaHCO3 aq
and brine. The organic layer was dried over MgSO4, fil-
tered, and concentrated in vacuo. To a solution of the
crude product in CH2Cl2 (18 mL) were added benzalde-
hyde (1.81 mL 1.81 mmol) and sodiumtriacetoxyboro-
hydride (422 mg, 1.99 mmol), and the mixture was
stirred at room temperature for 8 h. This mixture was
partitioned between EtOAc and satd NaHCO3 aq and
the organic layer was washed with brine. The organic
layer was then dried over MgSO4, filtered, and concen-
trated in vacuo. To a solution of compound obtained
above in EtOAc (15 mL) were added 4 M HCl (g)/
EtOAc (1.5 mL), and the mixture was stirred at room
temperature. The precipitate was collected by filtration,
washed with EtOAc, and dried in vacuo to yield 10
(435 mg, 57%) as a colorless crystal. mp: 316–318 ꢁC
ture. This mixture was then partitioned between EtOAc
and H2O, and the organic layer was washed with brine,
dried over MgSO4, filtered, and concentrated in vacuo.
The residue was purified by silica gel column chroma-
tography (CHCl3–MeOH = 100/0–95/5) to yield Ethyl
1-[(6-fluoro-2-naphthyl)methyl]piperidine-4-carboxylate
(569 mg, 72%) as a colorless oil. To a solution of the
compound obtained above in EtOH (6 mL) were added
1 M NaOH aq (2.0 mL), and the mixture was stirred at
room temperature for 4 h. This mixture was acidified
with 1 M HCl aq and the precipitate was collected by fil-
tration, washed with H2O, and dried in vacuo to yield 14
(259 mg, 50%) as a pale brown solid. 1H NMR
(400 MHz, DMSO-d6) d: 1.52–1.63 (m, 2H), 1.73–1.83
(m, 2H), 1.97–2.08 (m, 2H), 2.16–2.25. (m, 1H), 2.74–
2.82 (m, 2H), 3.59 (s, 2H), 7.40 (ddd, J = 8.8, 7.2,
2.4 Hz, 1H), 7.51 (d, J = 8.4 Hz, 1H), 7.67 (dd,
J = 10.4, 2.4 Hz, 1H), 7.82 (s, 1H), 7.86 (d, J = 8.4 Hz
1H), 7.98 (dd, J = 7.2, 6.0 Hz 1H), 11.90–12.29 (m,
1H); MS (FAB) m/z = 288 [M+H]+.
1
(EtOAc); H NMR (400 MHz, DMSO-d6) d: 2.03–2.16
(m, 2H), 2.26–2.36 (m, 2H), 2.96–3.04 (m, 2H), 3.42–
3.52 (m, 2H), 4.22 (d, J = 4.4 Hz, 1H), 4.41 (d,
J = 4.4 Hz, 1H), 7.39–7.60 (m, 6H), 7.75–7.86 (m, 2H),
7.96–8.07 (m, 2H), 8.14 (s, 1H), 9.57 (s, 1H), 11.02 (s,
1H); MS (FAB) m/z = 349 [M+H]+. Anal. Calcd for
C23H24FN2Æ2HCl: C, 65.56; H, 6.46; N, 6.65; F, 4.51.
Found: C, 64.47; H, 6.58; N, 6.66; F, 4.45.
5.1.12. 1-[(6-Fluoro-2-naphthyl)methyl]-N-phenylpiperi-
dine-4-carboxamide (15). Compound 15 was prepared
from 14 and aniline in a manner similar to that de-
scribed for compound 20g, with a yield of 68% as a col-
1
orless solid. mp: 209–211 ꢁC (MeCN–EtOH); H NMR
(400 MHz, CDCl3) d: 1.84–1.96 (m, 4H), 2.05–2.13 (m,
2H), 2.20–2.31 (m, 1H), 2.94–3.04 (m, 2H), 3.66 (s,
2H), 7.06–7.16 (m, 2H), 7.22–7.34 (m, 5H), 7.43 (dd,
J = 9.8, 2.5 Hz, 1H), 7.49–7.54 (m, 3H ), 7.73–7.82 (m,
3H); MS (FAB) m/z = 363 [M+H]+. Anal. Calcd for
C23H23FN2O: C, 76.22; H, 6.40; N, 7.73; F, 5.24.
Found: C, 76.16; H, 6.42; N,7.74; F, 5.36.
5.1.9.
N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-
yl}benzenesulfonamide (11). Compound 11 was prepared
from 9 and benzenesulfonyl chloride in a manner similar
to that described for compound 20c, with a yield of 41%
as a colorless solid. mp: 118–119 ꢁC (MeCN);1H NMR
(400 MHz, CDCl3) d: 1.42–1.53 (m, 2H), 1.70–1.79 (m,
2H), 2.03–2.12 (m, 2H), 2.69–2.78 (m, 2H), 3.16–3.27
(m, 1H), 3.58 (s, 2H), 4.58 (d, J = 7.3 Hz, 1H),
7.21–7.28 (m, 1H), 7.39–7.58 (m, 5H), 7.66 (s, 1H), 7.71
(d, J = 8.3 Hz, 1H), 7.76 (dd, J = 9.0, 5.6 Hz, 1H ),
7.86–7.91 (m, 2H); MS (FAB) m/z = 399 [M+H]+. Anal.
Calcd for C22H23FN2O2S: C, 66.31; H, 5.82; N, 7.03; S,
8.05; F, 4.77. Found: C, 66.12; H, 5.82; N, 6.98; S,
8.10; F, 4.74.
5.1.13. 1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-ol (17).
To a solution of 4-hydroxypiperidine (16) (346 mg,
8.37 mmol) in CHCl3 (15 mL) were added 8 (1.00 g
4.18 mmol) and Et3N (0.58 mL, 4.18 mmol), and the
mixture was stirred at room temperature for 4 h. This
mixture was partitioned between CHCl3 and satd NaH-
CO3 aq and the organic layer was then washed with
brine, dried over MgSO4, filtered, and concentrated in
vacuo. The residue was purified by silica gel column
chromatography (CHCl3–MeOH = 95/5) to yield 17
5.1.10. (2E)-N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-
4-yl}-3-phenylacrylamide (12). Compound 12 was pre-
pared from 9 and cinnamoyl chloride in a manner simi-
lar to that described for compound 20c, with a yield of
56% as a colorless solid. mp: 184–186 ꢁC (MeCN–
CHCl3);1H NMR (400 MHz, CDCl3) d: 1.48–1.59 (m,
2H), 1.95–2.02 (m, 2H), 2.16–2.26 (m, 2H), 2.83–2.92
(m, 2H), 3.64 (s, 2H), 3.91–4.03 (m, 1H), 5.52 (d,
J = 7.8 Hz, 1H), 6.37 (d, J = 15.7 Hz, 1H) 7.23–7.28
(m, 1H), 7.33–7.39 (m, 3H), 7.43 (dd, J = 10.0, 2.8 Hz,
1H), 7.47–7.54 (m, 3H), 7.61 (d, J = 15.7 Hz, 1H ),
7.72–7.77 (m, 2H), 7.79 (dd, J = 9.0, 5.6 Hz, 1H); MS
(FAB) m/z = 389 [M+H]+. Anal. Calcd for
C25H25FN2O: C, 77.29; H, 6.49; N, 7.21; F, 4.89.
Found: C, 77.43; H, 6.53; N, 7.21; F, 4.73.
(910 mg, 84%) as
a
colorless solid. 1H NMR
(400 MHz, DMSO-d6) d: 1.34–1.47 (m, 2H), 1.66–1.76
(m, 2H), 2.00–2.14 (t, J = 10.0 Hz, 2H), 2.65–2.74 (m,
2H), 3.42–3.52 (m,1H), 3.57 (s, 2H),4.52 (d,
J = 3.9 Hz, 1H), 7.35–7.44 (m, 1H), 7.52 (d,
J = 8.8 Hz, 1H), 7.66 (d, J = 9.3 Hz, 1H), 7.81 (s,1H),
7.86 (d, J = 8.3 Hz, 1H), 7.97 (dd, J = 8.8, 5.9 Hz, 1H);
MS (FAB) m/z = 260 [M+H]+.
5.1.14. 1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-yl phe-
nylcarbamate hydrochloride (18). To a solution of 17
(490 mg, 1.89 mmol) in toluene (15 mL) were added
phenylisocyanate (225 mg, 1.89 mmol), and the mixture
was stirred at reflux for 11 h. The mixture was cooled to
rt and concentrated in vacuo. To a solution of the crude
product in EtOAc(10 mL) were added 4 M HCl (g)/
EtOAc (0.5 mL), and this mixture was then stirred at
room temperature for 0.5 h. The precipitate was
collected by filtration, washed with EtOAc, and dried
5.1.11. 1-[(6-Fluoro-2-naphthyl)methyl]piperidine-4-car-
boxylic acid (14). To a solution of Ethyl isonipecotate
(406 mg, 2.50 mmol) in EtOH (6 mL) was added 8
(598 mg 2.50 mmol), and K2CO3 (433 mg, 3.13 mmol)
and the mixture was stirred overnight at room tempera-

152
I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
in vacuo to yield 18 (308 mg, 40%) as a colorless solid.
mp: 202–204 ꢁC (EtOAc); 1H NMR (400 MHz,
DMSO-d6) d: 1.97–2.12 (m, 2H), 2.13–2.28 (m, 2H),
3.07–3.22 (m, 2H), 3.30–3.45 (m, 2H), 4.40–4.54 (m,
2H), 4.78–4.99 (m, 1H), 6.99 (t, J = 7.3 Hz, 1H), 7.27
(t, J = 7.5 Hz, 2H), 7.40–7.56 (m, 3H), 7.79 (d,
J = 9.7 Hz, 1H), 7.87 (d, J = 8.3 Hz, 1H), 7.97–8.09
(m, 2H), 8.15–8.23 (m, 1H), 9.70 (bars, 1H), 11.08–
11.32 (m, 1H); MS (FAB) m/z = 379 [M+H]+. Anal.
Calcd for C23H23FN2O2ÆHCl: C, 66.58; H, 5.83; N,
6.75; F, 4.58; Cl, 8.54. Found: C, 66.32; H, 5.74; N,
6.78; F, 4.37; Cl, 8.42.
(104 mg, 0.64 mmol) in CH2Cl2 (2 mL), and the mixture
was stirred overnight at room temperature. This mixture
was partitioned between CH2Cl2 and H2O, and the or-
ganic layer was dried over MgSO4, filtered, and concen-
trated in vacuo. The residue was purified by silica gel
column chromatography (CHCl3–MeOH = 100/0–98/
2). The crude solid was recrystallized from MeCN–
CHCl3 to yield 20b (166 mg, 72%) as a colorless crystal.
1
mp: 183–185 ꢁC; H NMR (400 MHz, CDCl3) d: 1.52–
1.64 (m, 2H), 1.98–2.07 (m, 2H), 2.18–2.27 (m, 2H),
2.85–2.94 (m, 2H), 3.65 (s, 2H), 3.96–4.08 (m, 1H),
5.97 (d, J = 7.3 Hz, 1H), 7.15–7.23 (m, 1H), 7.22–7.29
(m, 1H), 7.36–7.55 (m, 5H), 7.66–7.77 (m, 2H), 7.79
(dd, J = 8.8, 5.5 Hz, 1H); MS (FAB) m/z = 381
[M+H]+. Anal. Calcd for C23H22FN2O: C, 72.61; H,
5.83; N, 7.36; F, 9.99; Found: C, 72.77; H, 5.86; N,
7.37; F, 9.89.
5.1.15. N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-yl}-
N0-phenylurea (19). To a solution of 9 (200 mg,
0.60 mmol) in CH2Cl2 (6 mL) were added N,N-diisopro-
pylethylamine (0.43 mL, 2.42 mmol) and phenylisocya-
nate (77 mg, 0.64 mmol), and the mixture was stirred
at room temperature for over night. This mixture was
then partitioned between CHCl3 and H2O, and the or-
ganic layer was dried over MgSO4, filtered, and concen-
trated in vacuo. The residue was purified by silica gel
column chromatography (CHCl3–MeOH = 100/0–98/
2). The crude solid was recrystallized from MeCN–
EtOH to yield 19 (155 mg, 68%) as a colorless crystal.
5.1.18. 4-Fluoro-N-{1-[(6-fluoro-2-naphthyl)methyl]pip-
eridin-4-yl}benzamide (20c). To an ice-cold solution of
9 (250 mg, 0.76 mmol) in CH2Cl2 (2 mL) and THF
(1 mL) were added Et3N (0.38 mL, 2.72 mmol) and 2-
fluorobenzoylchloride (130 mg, 0.79 mmol), and this
mixture was stirred overnight at room temperature.
The mixture was poured into H2O, and the precipitate
was collected by filtration, washed with H2O, and dried
in vacuo. The crude solid was recrystallized from
MeCN–EtOH–CHCl3 to yield 20c (176 mg, 61%) as a
1
mp: 214–216 ꢁC (MeCN–EtOH); H NMR (400 MHz,
CDCl3) d: 1.40–1.52 (m, 2H), 1.93–2.01 (m, 2H), 2.13–
2.24 (m, 2H), 2.78–2.87 (m, 2H), 3.62 (s, 2H), 3.69–
3.79 (m, 1H), 4.56 (d, J = 7.8 Hz, 1H), 6.16 (s, 1H),
7.07–7.13 (m, 1H), 7.21–7.34 (m, 5H), 7.43 (dd,
J = 9.8, 2.5 Hz, 1H), 7.49 (d, J = 7.8 Hz, 1H), 7.70 (s,
1H), 7.73 (d, J = 9.8 Hz, 1H), 7.78 (dd, J = 9.1, 5.7 Hz,
1H); MS (FAB) m/z = 378 [M+H]+. Anal. Calcd for
C23H24FN3O: C, 73.19; H, 6.41; N, 11.13; F, 5.03.
Found: C, 72.99; H, 6.39; N, 11.10; F, 4.77.
1
colorless crystal. mp: 203–206 ꢁC; H NMR (400 MHz,
CDCl3) d: 1.52–1.64 (m, 2H), 1.98–2.07 (m, 2H), 2.18–
2.28 (m, 2H), 2.86–2.94 (m, 2H), 3.65 (s, 2H), 3.96–
4.08 (m, 1H), 5.91 (d, J = 7.4 Hz, 1H), 7.07–7.13 (m,
2H), 7.22–7.28 (m, 2H), 7.43 (dd, J = 9.8, 2.5 Hz,
1H), 7.56 (d, J = 8.3 Hz, 1H), 7.72–7.78 (m, 4H), 7.79
(dd, J = 8.8, 5.4 Hz, 1H); MS (FAB) m/z = 381
[M+H]+. Anal. Calcd for C23H22FN2O: C, 72.61; H,
5.83; N, 7.36; F, 9.99; Found: C, 72.54; H, 5.68; N,
7.34; F, 10.06.
5.1.16. 2-Fluoro-N-{1-[(6-fluoro-2-naphthyl)methyl]pip-
eridin-4-yl}benzamide (20a). To an ice-cold solution of 9
(200 mg, 0.60 mmol) in pyridine (2 mL) were added 2-flu-
orobenzoylchloride (130 mg, 0.79 mmol) in THF (2 mL),
and the mixture was stirred overnight at room tempera-
ture. This mixture was concentrated in vacuo, and the res-
idue was partitioned between CHCl3 and H2O. The
organic layer was then dried over MgSO4, filtered, and
concentrated in vacuo. The residue was purified by silica
gel column chromatography (CHCl3–MeOH = 100/0–
98/2). The crude solid was recrystallized from MeCN–
CHCl3 to yield 20a (170 mg, 74%) as a colorless crystal.
5.1.19. N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-yl}-
2-methoxybenzamide (20d). Compound 20d 1.5fumarate
was prepared from 9 and 2-methoxybenzoylchloride in a
manner similar to that described for compound 20c,
with a yield of 45% as a pale pink crystal. mp: 210–
213 ꢁC (MeOH); 1H NMR (400 MHz, DMSO-d6) d:
1.54–1.66 (m, 2H), 1.81–1.89 (m, 2H), 2.28 (t,
J = 10.2 Hz, 2H), 2.80–2.88 (m, 2H), 3.73 (s, 2H),
3.80–3.89 (m, 4H), 6.64 (s, 3H), 7.23 (t, J = 7.4 Hz,
1H), 7.14 (d, J = 8.3 Hz, 1H), 7.39–7.48 (m, 2H), 7.56
(d, J = 8.8 Hz, 1H), 7.65–7.72 (m, 2H), 7.86–7.91 (m,
2H), 7.97-8.05 (m, 2H); MS (FAB) m/z = 393 [M+H]+.
Anal. Calcd for C24H29FN2O2Æ1.5C4H4O4: C, 63.60;
H, 5.51; N, 4.94; F, 3.35. Found: C, 63.55; H, 5.49; N,
4.92; F, 3.14.
1
mp: 171–173 ꢁC;- H NMR (400 MHz, CDCl3) d: 1.56–
1.67 (m, 2H), 2.01–2.09 (m, 2H), 2.20–2.30 (m, 2H),
2.84–2.93 (m, 2H), 3.65 (s, 2H), 4.02–4.14 (m, 1H), 6.64
(dd, J = 12.2, 7.8 Hz, 1H), 7.10 (ddd, J = 12.2, 8.3,
1.0 Hz, 1H), 7.22–7.29 (m, 2H), 7.41–7.49 (m, 2H), 7.53
(d, J = 8.8 Hz, 1H), 7.72–7.77 (m, 2H), 7.79 (dd,
J = 9.0, 5.7 Hz, 1H), 8.08 (dt, J = 8.3, 1.9 Hz, 1H); MS
(FAB) m/z = 381 [M+H]+. Anal. Calcd for C23H22FN2O:
C, 72.61; H, 5.83; N, 7.36; F, 9.99; Found: C, 72.86; H,
5.78; N, 7.40; F, 9.80.
5.1.20. N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-yl}-
3-methoxybenzamide (20e). Compound 20d was pre-
pared from 9 and 3-methoxybenzoylchloride in a man-
ner similar to that described for compound 20c, with a
yield of 62% as a colorless crystal. mp: 186–188 ꢁC
(MeCN); 1H NMR (400 MHz, CDCl3) d: 1.52–1.63
(m, 2H), 1.99–2.08 (m, 2H), 2.18–2.28 (m, 2H), 2.84–
2.93 (m, 2H), 3.65 (s, 2H), 3.84 (s, 3H), 3.96–4.08 (m,
5.1.17. 3-Fluoro-N-{1-[(6-fluoro-2-naphthyl)methyl]pip-
eridin-4-yl}benzamide (20b). To an ice-cold solution of
9 (200 mg, 0.60 mmol) in CH2Cl2 (2 mL) and 1 M NaH-
CO3 aq (2.2mL) were added 3-fluorobenzoylchloride

I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
153
1H), 5.97 (d, J = 7.8 Hz, 1H), 7.03 (ddd, J = 8.3, 2.7,
1.0 Hz, 1H), 7.22–7.28 (m, 3H), 7.30–7.35 (m, 2H),
7.43 (dd, J = 9.8, 2.4 Hz, 1H), 7.52 (d, J = 8.3 Hz, 1H),
7.72–7.76 (m, 2H), 7.79 (dd, J = 9.0, 5.7 Hz, 1H); MS
(FAB) m/z = 393 [M+H]+. Anal. Calcd for
C24H25FN2O2: C, 73.45; H, 6.42; N, 7.14; F, 4.84;
Found: C, 73.67; H, 6.39; N, 7.16; F, 4.61.
from 9 and 3-phenoxybenzoic acid in a manner similar
to that described for compound 20g, with a yield of
67% as a colorless crystal. mp: 173–175 ꢁC (MeCN);
1H NMR (400 MHz, CDCl3) d: 1.52–1.64 (m, 2H),
1.99–2.09 (m, 2H), 2.18–2.27 (m, 2H), 2.85–2.94 (m,
2H), 3.65 (s, 2H), 3.97–4.08 (m, 1H), 5.90 (d,
J = 7.3 Hz, 1H), 6.98–7.06 (m, 4H), 7.14–7.19 (m, 1H),
7.22–7.28 (m, 1H), 7.35–7.40 (m, 2H), 7.43 (dd,
J = 9.8, 2.4 Hz, 1H), 7.52 (d, J = 8.3 Hz, 1H), 7.70–
7.77 (m, 4H), 7.79 (dd, J = 9.1, 5.7 Hz, 1H); MS
(FAB) m/z = 455 [M+H]+. Anal. Calcd for
C29H27FN2O2: C, 76.63; H, 5.99; N, 6.16; F, 4.18.
Found: C, 76.75; H, 5.94; N, 6.24; F, 3.97.
5.1.21. N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-yl}-
2-methoxybenzamide (20f). Compound 20f was prepared
from 9 and 4-methoxybenzoylchloride in a manner sim-
ilar to that described for compound 20c, with a yield of
62% as a colorless crystal. mp: 216–218 ꢁC (EtOH–
1
CHCl3); H NMR (400 MHz, CDCl3) d: 1.52–1.63 (m,
2H), 1.98–2.07 (m, 2H), 2.18–2.28 (m, 2H), 2.84–2.93
(m, 2H), 3.65 (s, 2H), 3.84 (s, 3H), 3.96–4.07 (m, 1H),
5.89 (d, J = 7.8 Hz, 1H), 6.89–6.94 (m, 2H), 7.24 (dt,
J = 8.7, 2.4 Hz, 1H), 7.43 (dd, J = 9.8, 2.4 Hz, 1H),
7.69–7.81 (m, 5H), 7.79 (dd, J = 8.7, 5.7 Hz, 1H); MS
(FAB) m/z = 393 [M+H]+. Anal. Calcd for
C24H25FN2O2: C, 73.45; H, 6.42; N, 7.14; F, 4.84;
Found: C, 73.45; H, 6.45; N, 7.14; F, 4.86.
5.1.25.
N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-
yl}biphenyl-2-carboxamide (20j). Compound 20j was
prepared from 9 and biphenyl-2-carboxylic acid in a
manner similar to that described for compound 20g,
with a yield of 62% as a colorless solid. mp: 205–
207 ꢁC (MeCN); 1H NMR (400 MHz, DMSO-d6 d:
1.20–1.38 (m, J > 12 Hz, 2H), 1.50–1.64 (m, 2H),
1.90–2.06 (m, J > 12 Hz, 2H), 2.63–2.77 (m, 2H),
3.54 (br, 2H), 7.28–7.45 (m, 9H), 7.46–7.53 (m, 2H),
7.68 (d, J = 9.3 Hz, 1H), 7.7.76–7.90 (m, 2H), 7.94–
8.03 (m, 2H); MS (FAB) m/z = 439 [M+H]+. Anal.
Calcd for C29H27FN2OÆ0.2H2O: C, 78.78; H, 6.25;
N, 6.34; F, 4.30. Found: C, 78.76; H, 6.27; N, 6.48;
F, 4.46.
5.1.22. N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-yl}-
2-phenoxybenzamide (20g). To a solution of 9 (200 mg,
0.60 mmol) in CH2Cl2 (3 mL) were added 2-phenoxy-
benzoic acid (129 mg, 0.60 mmol), HOBt (98 mg,
0.73 mmol), WSCÆHCl (140 mg, 0.725 mmol) and Et3N
(0.20 mL), and this mixture was stirred at room temper-
ature for 3 days. The mixture was then partitioned be-
tween CH2Cl2 and satd NaHCO3 aq and the organic
layer was dried over MgSO4, filtered, and concentrated
in vacuo. The crude solid was recrystallized from EtOAc
to yield 20g (106 mg, 39%) as a colorless solid. mp: 142–
144 ꢁC (EtOAc); 1H NMR (400 MHz, DMSO-d6) d:
1.38–1.52 (m, 2H), 1.61–1.72 (m, 2H), 2.00–2.12 (m,
2H), 2.65–2.75 (m, 2H), 3.54 (s, 2H), 3.64–3.76 (m,
1H), 6.93–7.02 (m, 3H), 7.11 (t, J = 7.6 Hz, 1H), 7.23
(t, J = 7.2 Hz, 1H), 7.33–7.54 (m, 5H), 7.60 (d,
J = 6.8 Hz, 1H), 7.67 (d, J = 10.0 Hz, 1H), 7.79 (br,
1H), 7.86 (d, J = 8.4 Hz, 1H), 7.98 (dd, J = 8.4, 5.6 Hz,
1H), 8.05 (d, J = 7.2 Hz, 1H); MS (FAB) m/z = 455
[M+H]+. Anal. Calcd for C29H27FN2O2: C, 76.63; H,
5.99; N, 6.16; F, 4.18. Found: C, 76.26; H, 6.15; N,
6.02; F, 4.00.
5.1.26.
N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-
yl}biphenyl-3-carboxamide (20k). Compound 20k hydro-
chloride was prepared from 9 and biphenyl-3-carboxylic
acid in a manner similar to that described for compound
20g, with a yield of 41% as a colorless solid. mp: 246–
248 ꢁC (MeOH); 1H NMR (400 MHz, DMSO-d6) d:
1.98–2.17 (m, 4H), 3.08–3.21 (m, 2H), 3.21–3.43 (m,
2H), 3.98–4.24 (m, 1H), 4.40–4.54 (m, 2H), 7.38–7.46
(m, 1H), 7.48–7.61 (m, 4H), 7.70–7.95 (m, 6H), 7.99–
8.18 (m, 2H), 8.12–8.24 (m, 2H), 8.52–8.76 (m, 1H),
10.88–11.28 (m, 1H); MS (FAB) m/z = 439 [M+H]+.
Anal. Calcd for C29H27FN2OÆHClÆ0.2H2O: C, 72.78; H,
5.98; N, 5.85; F, 3.97; Cl, 7.41. Found: C, 72.65; H,
5.83; N, 5.87; F, 4.14; Cl, 7.35.
5.1.27.
N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-
yl}biphenyl-4-carboxamide (20l). Compound 20l was
prepared from 9 and biphenyl-4-carboxylic acid in a
manner similar to that described for compound 20g,
with a yield of 27% as a colorless solid. mp: 214–
5.1.23. N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-yl}-
3-phenoxybenzamide (20h). Compound 20h was pre-
pared from 9 and 3-phenoxybenzoic acid in a manner
similar to that described for compound 20g, with a yield
of 55% as a colorless crystal. mp: 165–168 ꢁC (i-Pr2O–
1
218 ꢁC (MeCN); H NMR (400 MHz, CDCl3) d: 1.54–
1.66 (m, 2H), 2.02–2.10 (m, 2H), 2.19–2.29 (m, 2H),
2.86–2.94 (m, 2H), 3.66 (s, 2H), 4.00–4.12 (m, 1H),
6.03 (d, J = 7.8 Hz, 1H), 7.23–7.28 (m, 1H), 7.36–7.50
(m, 4H), 7.53 (d, J = 8.7 Hz, 1H), 7.58–7.68 (m, 4H),
7.72–7.85 (m, 5H); MS (FAB) m/z = 439 [M+H]+. Anal.
Calcd for C29H27FN2O: C, 79.43; H, 6.21; N, 6.39; F,
4.33. Found: C, 79.65; H, 6.37; N, 6.47; F, 4.45.
1
MeOH); H NMR (400 MHz, CDCl3) d: 1.51–1.62 (m,
2H), 1.9–2.06 (m, 2H), 2.17–2.28 (m, 2H), 2.84–2.96
(m, 2H), 3.65 (s, 2H), 3.95–4.06 (m, 1H), 5.93 (d,
J = 7.8 Hz, 1H), 6.98–7.05 (m, 2H), 7.08–7.18 (m, 2H),
7.22–7.28 (m, 1H), 7.33–7.48 (m, 6H), 7.51 (d,
J = 8.3 Hz, 1H), 7.70–7.76 (m, 2H), 7.99 (dd,
J = 8.85.8 Hz, 1H); MS (FAB) m/z = 455 [M+H]+. Anal.
calcd for C29H27FN2O2: C, 76.63; H, 5.99; N, 6.16; F,
4.18. Found: C, 76.71; H, 5.93; N, 6.17; F, 4.34.
5.1.28.
N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-
yl}-N-methylbenzamide (21). To a solution of 1 (300 mg,
0.83 mmol) in DMF (5 mL) were added NaH (60% oil
dispersion, 43 mg 1.08 mmol), and the mixture was stir-
red at room temperature for 1.5 h. The mixture was
5.1.24. N-{1-[(6-Fluoro-2-naphthyl)methyl]piperidin-4-yl}-
4-phenoxybenzamide (20i). Compound 20i was prepared

154
I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
added MeI (58 ll 0.91 mmol), which was then stirred at
room temperature for 5 h. This mixture was then parti-
tioned between EtOAc and satd NaHCO3 aq and the or-
ganic layer was washed with brine, dried over Na2SO4,
filtered, and concentrated in vacuo. The crude solid was
recrystallized from MeCN–i-Pr2O to yield 21 (145 mg,
2.8 Hz, 1H), 7.43 (dd, J = 9.8, 2.5 Hz, 1H), 7.51 (d,
J = 8.8 Hz, 1H), 7.72–7.75 (m, 3H), 7.78 (dd, J = 9.0,
5.6 Hz, 1H); MS (FAB) m/z = 273 [M+H]+.
5.1.31. N-{1-[(6-Fluoro-2-naphthyl)methyl]-4-methylpi-
peridin-4-yl}biphenyl-2-carboxamide hemifumarate (25).
Compound 25 was prepared from 24 and biphenyl-2-car-
boxylic acid in a manner similar to that described for
compound 20g with a yield of 31% as a colorless crystal.
mp: 168–171 ꢁC (MeOH); 1H NMR (500 MHz, DMSO-
d6) d: 1.21 (s, 3H), 1.38–1.45 (m, J > 12 Hz, 2H), 2.05–
2.16 (m, J > 12 Hz, 4H), 2.43–2.49 (m, 2H), 3.60 (s,
2H), 6.60 (s, 1H), 7.30–7.48 (m, 10H), 7.51–7.54 (m,
2H), 7.68 (dd, J = 10.3, 2.6 Hz, 1H), 7.83–7.88 (m, 2H),
8.00 (dd, J = 9.2, 5.8 Hz, 1H); MS (FAB) m/z = 453
[M+H]+. Anal. Calcd for C30H29FN2OÆ 0.5C4H4O4Æ0.75-
H2O: C, 73.33; H, 6.25; N, 5.34; F, 3.62. Found: C, 73.23;
H, 6.35; N, 5.30; F, 3.66.
1
47%) as a colorless crystal. mp: 124–126 ꢁC; H NMR
(400 MHz, DMSO-d6) d: 1.50–1.93 (m, 5H), 2.00–2.22
(m, 1H), 2.69–3.00 (m, 5H), 3.49–3.70 (m, 3H), 7.30–
7.56 (m, 7H), 7.67 (d, J = 10.3 Hz, 1H), 7.73–7.91 (m,
2H), 7.97 (br, 1H); MS (FAB) m/z = 377 [M+H]+. Anal.
Calcd for C24H25FN2O: C, 76.57; H, 6.69; N, 7.44; F,
5.05. Found: C, 76.19; H, 6.80; N, 7.31, F, 4.69.
5.1.29. 1-[(6-Fluoro-2-naphthyl)methyl]-piperidin-4-one
(23). To a solution of 4-piperidone monohydrate mono-
hydrochloride (4.11 g, 26.2 mmol) in DMF (80 ml) were
added 8 (5.05 g, 21.1 mmol) and K2CO3 (7.30 g,
52.4 mmol), and the mixture was stirred at room tem-
perature for 1 week. The mixture was concentrated in
vacuo. The residue was partitioned between CHCl3
and H2O, and the organic layer was washed with brine,
dried over Na2SO4, filtered and concentrated in vacuo.
The residue was purified by silica gel column chroma-
tography (Hexane–EtOAc = 2/1–1/2) to give 23 (4.22 g,
78%) as yellow oil. 1H NMR (400 MHz, CDCl3) d:
2.47 (dd, J = 6.3, 5.9 Hz, 4H), 2.79 (dd, J = 6.3,
5.9 Hz, 4H), 3.76 (s,2H), 7.23–7.39 (m, 1H), 7.44 (dd,
J = 10.0, 2.7 Hz, 1H), 7.56 (d, J = 8.3 Hz, 1H), 7.74–
7.83 (m, 3H); MS (GC) m/z = 257 (M)+.
5.1.32. endo-N-8-Azabicyclo[3.2.1]oct-3-ylbiphenyl-2-car-
boxamide hydrochloride (28). To a solution of endo-8-
benzyl-8-azabicyclo[3.2.1]octan-3-amine (26)7 (573 mg,
2.65 mmol) in DMF (10 mL) were added biphenyl-2-
carboxylic acid (525 mg, 2.65 mmol), HOBt (430 mg,
3.18 mmol) and WSCÆHCl (613 mg, 3.18 mmol), and
the mixture was stirred at room temperature for 40 h.
This mixture was partitioned between EtOAc and satd
NaHCO3 aq and the organic layer was washed with
brine, dried over MgSO4, filtered, and concentrated in
vacuo. The residue was purified by silica gel column
chromatography (CHCl3–MeOH = 97.5/2.5) to yield
endo-N-(8-benzyl-8-azabicyclo[3.2.1]oct-3-yl)biphenyl-2-
carboxamide (850 mg, 81%) as a colorless oil. To a solu-
tion of the compound obtained above in EtOH (15 mL)
and MeOH (5mL) were added 4 M HCl (g)/EtOAc
(1 mL), and Pd(OH)2 (10 wt%, 300 mg), and the mixture
was stirred in a hydrogen atmosphere at room tempera-
ture for 23 h. The catalyst was removed by filtration on
celite and the filtrate was concentrated in vacuo to yield
5.1.30. 1-[(6-Fluoro-2-naphthyl)methyl]-4-methylpiperidin-
4-amine (24). To a cooled (ꢀ78 ꢁC) solution of 23
(1.54 g, 6.00 mmol) in Et2O (80 ml) were added 1.14 M
solution of MeLi (14.8 ml, 16.8 mmol, ) in Et2O, and
the mixture was stirred at ꢀ78 ꢁC for 2 h. The mixture
was partitioned between EtOAc and H2O, and the or-
ganic layer was washed with brine, dried over Mg2SO4,
filtered, and concentrated in vacuo. The residue was
purified by silica gel column chromatography (CHCl3–
MeOH = 100/0–98/2) to give 1-[(6-fluoro-2-naphthyl)
methyl]-4-methylpiperidin-4-ol (1.48 g, 90%) as pale
yellow solid. To a solution of residual compound ob-
tained above (684 mg, 2.50 mmol) in MeCN (308 mg,
7.5 mmol) were added CH2SO4 (1.12 mL, 20.0 mmol),
and the mixture was stirred at room temperature for
overnight. The mixture was poured onto ice and neutral-
ized with satd NaHCO3 aq and extracted with EtOAc.
The organic layer was washed with brine, dried over
Mg2SO4, filtered and concentrated in vacuo. The residue
was purified by silica gel column chromatography
(CHCl3–MeOH = 100/0–98/2) to give N-{1-[(6-fluoro-
2-naphthyl)methyl]-4-methylpiperidin-4-yl}acetamide
(734 mg, 93%) as pale brown solid. A solution of resid-
ual compound obtained above (350 mg, 1.11 mmol) in
3 M HCl (4.5 ml) were stirred at 100 ꢁC for overnight.
The mixture was cooled on ice-bath and neutralized
with 3 M NaOH, and extracted with CHCl3. The organ-
ic layer was washed with brine, dried over Na2SO4, fil-
tered and concentrated in vacuo to give 25 (315 mg,
1
28 (570 mg, quant.) as a colorless amorphous solid.; H
NMR (400 MHz, DMSO-d6) d: 1.55–1.69 (m, 4H), 1.75–
1.83 (m, 2H), 2.16 (ddd, J = 15.6, 6.4, 3.5 Hz, 2H), 3.33
(br, 2H), 3.39–3.48 (m, 1H), 7.33–7.46 (m, 8H), 7.52
(dt,J = 7.5, 1.6 Hz, 1H), 8.16 (d, J = 3.6 Hz, 1H), 8.64–
9.20 (m, 1H); MS (FAB) m/z = 307 [M+H]+.
5.1.33. endo-N-8-Azabicyclo[3.2.1]oct-3-ylbiphenyl-2-car-
boxamide hydrochloride (29). Compound 29 was pre-
pared from 277 in a manner similar to that described
for compound 28, with a quantitative yield over two
steps as a colorless amorphous solid; 1H NMR
(400 MHz, DMSO-d6) d: 1.55–1.65 (m, 2H), 1.68–1.78
(m, 2H),1.79–1.83 (m, 2H), 1.92–2.03 (m, 2H), 3.85–
3.95 (m, 2H), 3.96–4.08 (m, 1H), 7.31–7.50 (m, 8H),
7.48–7.53 (m, 1H), 8.30 (d, J = 7.3 Hz, 1H), 8.74–8.95
(m, 1H), 9.14–9.38 (m, 1H); MS (FAB) m/z = 307
[M+H]+.
5.1.34. endo-N-{8-[(6-Fluoro-2-naphthyl)methyl]-8-azabi-
cyclo[3.2.1]oct-3-yl}biphenyl-2-carboxamide (30). Com-
pound 30 was prepared from 28 and 8 in a manner
similar to that described for compound 6f, with a yield
of 21% as a colorless crystal. mp: 90–92 ꢁC (MeOH);
1
quant.) as brown oil. H NMR (400 MHz, CDCl3) d:
1.12 (s, 3H), 1.40–1.52 (m, 4H), 1.58–1.67 (m, 2H),
2.40–2.55 (m, 4H), 3.65 (s, 2H), 7.23 (dd, J = 8.8,

I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
155
1H NMR (400 MHz,DMSO-d6) d: 1.47–1.54 (m, 4H),
1.72–1.83 (m, 2H), 1.92–2.02 (m, 2H), 2.93–2.99 (m,
2H), 3.55 (s, 2H), 3.82–3.91 (m, J < 6.0 Hz, 1H), 7.30–
7.45 (m, 8H), 7.49 (dt, J = 7.3, 2.0 Hz, 1H), 7.56 (d,
J = 8.8 Hz, 1H), 7.66 (dd, J = 10.3, 2.5 Hz, 1H), 7.78
(d, J = 5.4 Hz, 1H), 7.82–7.86 (m, 2H), 7.96 (dd,
J = 5.8, 8.8 Hz, 1H); MS (FAB) m/z = 465 [M+H]+.
Anal. Calcd for C31H29FN2OÆ0.7H2O: C, 78.03; H,
6.42; N, 5.87; F, 3.98. Found: C, 77.90; H, 6.62; N,
5.71; F, 3.83.
least-squares method with anisotropic thermal parame-
ters and the SIR92 programs. Hydrogen atoms were
calculated assuming idealized geometries but were not
refined. The discrepancy indices R and wR were 0.115
and 0.183 for 5515 [I > 0.00r(I)] reflections. All calcula-
tions were performed using the teXan crystallographic
software package from Molecular Structure Corpora-
tion.14 Lists of the atomic coordinates, anisotropic
thermal parameters, and bond lengths and angles are
stored at the Cambridge Crystal Crystallographic Data
Centre, UK, CCDC-630758.
5.1.35. exo-N-{8-[(6-Fluoro-2-naphthyl)methyl]-8-azabi-
cyclo[3.2.1]oct-3-yl}biphenyl-2-carboxamide oxalate
(31). Compound 31 was prepared from 29 and 8 in a man-
ner similar to that described for compound 6f, with a yield
of 53% as a colorless crystal. mp: 159–161 ꢁC (MeOH); 1H
NMR (400 MHz, DMSO-d6) d: 1.64–1.76 (m, 4H), 1.84–
1.97 (m, 2H), 2.20–2.24 (m, 2H), 3.60–3.73 (m, 2H), 4.02–
4.24 (m, 3H), 7.28–7.45 (m, 8H), 7.46–7.53 (m, 2H), 7.68
(d, J = 8.8 Hz, 1H), 7.76 (dd, J = 10.3, 2.5 Hz, 1H), 7.97
(d, J = 8.3 Hz, 1H), 8.02 (dd, J = 9.3, 5.8 Hz, 1H), 8.08
(s, 1H), 8.13 (d, J = 7.9 Hz, 1H); MS (FAB) m/z = 465
[M+H]+. Anal. Calcd for C31H29FN2OÆC2H2O4ÆH2O: C,
69.22; H, 5.81; N, 4.89; F, 3.32. Found: C, 69.41; H,
5.94; N, 4.82; F, 3.28.
Acknowledgments
The authors wish to offer their deep thanks to Mr. M.
Yokota for his helpful support in preparing the manu-
script, and are also grateful to the staff of the Division
of Analytical Science Laboratories for their help with
the elemental analysis and spectral measurements.
References and notes
1. (a) Barnes, P. J.; Chung, K. F.; Page, C. P. Pharmacol.
Rev. 1998, 50, 515–596; (b) Busse, W. W.; Banks-schlegel,
S.; Wenzel, S. E. J. Allergy Clin. Immunol. 2000, 106,
1033–1042.
5.2. Biology
5.2.1. Measurement of intracellular Ca2+ concentrations.
CCR3-transfected B300-19 cells11 were loaded with
5 lM Fura-2 acetoxymethyl ester in RPMI 1640 media
containing 1% fetal bovine serum for 30 min at 37 ꢁC.
After two washes, the cells were resuspended at a density
of 2 · 106 cells/mL in 20 mM HEPES buffer containing
0.1% BSA, 130 mM NaCl, 5.4 mM KCl, 1 mM, MgCl2
2.5 mM, CaCl2, and 5.5 mM glucose. The cell suspen-
sion (490 ll) was transferred into cuvettes and placed
under constant agitation. Changes in fluorescence were
monitored at 25 ꢁC using a spectrophotometer at excita-
tion wavelength of 340 nm and 380 nm and an emission
wavelengths of 510 nm. Calculation of Ca2+ concentra-
tion was performed using the Kd for the Ca2+ binding
of 224 nm. The antagonist was dissolved in 100%
DMSO solution (1 ll) and added to the cuvette 1 min
prior to the addition of eotaxin (final concentration of
50 ng/mL). Linear regression analysis using EXSAS-
STAT was used to calculate the IC50 values. Values
are reported as means SEM of triplicate experiments.
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C31H29FN2OÆC2H2O4ÆC3H8O, Mw = 614.69, mono-
˚
clinic, space group: P21/c, a = 16.060(4) A, b =
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˚
˚
13.621(3) A, c = 14.652(3) A, b = 95.65(2)ꢁ,V = 3189(1)
3
3
˚
A , Dx = 1.28 g/cm , and Z = 4. A single crystal was
used for X-ray diffraction data collection on a Rigaku
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and polarization factors. The structure was solved using
the direct method and the SIR92 program.13 The
non-hydrogen atoms were refined using a full-matrix

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I. Sato et al. / Bioorg. Med. Chem. 16 (2008) 144–156
9. Compound 6a was acquired from an outside supplier.
12. Copies of the data can be obtained, free of charge, on
application to CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK [fax: +44(0)1223 336033 or e-mail:
deposit@ccdc.cam.ac.uk].
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