Novel orally active NPY Y5 receptor antagonists: Synthesis and structure-activity relationship of spiroindoline class compounds

Article abstract of DOI:10.1016/j.bmc.2009.05.064

Spiroindoline urea derivatives, designed to act as NPY Y5 receptor antagonists, were synthesized and their structure-activity relationships were investigated. Of these derivatives, compound 3a showed good Y5 binding affinity with favorable pharmacokinetic

Full text of DOI:10.1016/j.bmc.2009.05.064

Bioorganic & Medicinal Chemistry 17 (2009) 5015–5026
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Novel orally active NPY Y5 receptor antagonists: Synthesis
and structure–activity relationship of spiroindoline class compounds
*
Toshihiro Sakamoto , Minoru Moriya, Hiroyasu Tsuge, Toshiyuki Takahashi, Yuji Haga,
Katsumasa Nonoshita, Osamu Okamoto, Hirobumi Takahashi, Aya Sakuraba, Tomoko Hirohashi,
Takunobu Shibata, Tetsuya Kanno, Junko Ito, Hisashi Iwaasa, Akira Gomori, Akane Ishihara,
Takahiro Fukuroda, Akio Kanatani, Takehiro Fukami
Tsukuba Research Institute, Merck Research Laboratories, Banyu Pharmaceutical Co., Ltd, Okubo-3, Tsukuba, Ibaraki 300-2611, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Spiroindoline urea derivatives, designed to act as NPY Y5 receptor antagonists, were synthesized and
their structure–activity relationships were investigated. Of these derivatives, compound 3a showed good
Y5 binding affinity with favorable pharmacokinetic properties. Compound 3a significantly inhibited bPP
Y5 agonist-induced food intake in rats, and suppressed body weight gain in DIO mice.
Ó 2009 Elsevier Ltd. All rights reserved.
Received 27 April 2009
Revised 25 May 2009
Accepted 27 May 2009
Available online 2 June 2009
Keywords:
NPY
Neuropeptide Y
Y5 receptor
Spiroindoline
Obesity
Phenyl imidazole
1. Introduction
treatment of obesity. To date, various structurally diverse NPY Y5
receptor antagonists have been reported by a number of research
Neuropeptide Y (NPY) is a highly conserved C-terminus amidat-
ed peptide consisting of 36 amino acid residues, and has been
shown to have potent, centrally-mediated orexigenic effects.1–4
NPY is abundant in the central nervous system throughout the
cerebral cortex, forebrain, hypothalamus, brain stem, and spinal
cord. In the periphery, NPY is present in most sympathetic nerve
fibers, especially around blood vessels.5 Reports of NPY activity
demonstrate a wide range of potential effects at both central and
peripheral targets, acting either alone or in combination with other
neurotransmitters such as norepinephrine and glutamate. The ef-
fects of the NPY family of peptides are mediated via a family of
G-protein coupled receptors (GPCRs), providing opportunities for
subtype selective therapeutics. At least six receptor subtypes of
the NPY family have been characterized based on cloning and their
pharmacological characterization.6 Various pharmacological stud-
ies employing receptor deficient mice and/or subtype-selective
agonists and antagonists have suggested that the Y5 receptors
are involved in body weight regulation.7–9 The antagonism of the
Y5 receptors may have considerable therapeutic benefits for the
groups, including ours.10–23
Previously, our group reported several types of Y5 antago-
nists.18–23 Our first lead compound, 1, was designed following sim-
ilarity searching of an MRL compound collection, and had very high
potency against Y5 receptor (IC50: 0.85 nM).23 However, its oral
bioavailability was too poor to show in vivo efficacy. In order to
improve bioavailability, the incorporation of one or several N
atoms into the biphenyl region was conducted. This led to the
identification of compound 2c, which was found to reduce bovine
pancreatic polypeptide (bPP)-induced food intake in rats.24 More-
over, phenyl imidazole 3a was found to be effective in a chronic
obesity model. In this paper, we report detailed SAR studies of this
spiroindoline class, as well as the identification of compound 3a
(Fig. 1).
2. Chemistry
The general strategy for the synthesis of the derivatives is de-
scribed in Scheme 1. Compounds 2a–aj were prepared by the urea
formation between spiroindoline amine 6, which was previously
synthesized and reported by our Process Research group,25 and
phenyl carbamates of the corresponding amines. The phenyl
* Corresponding author. Tel.: +81 29 877 2000; fax: +81 29 877 2029.
E-mail address: toshihiro_sakamoto@merck.com (T. Sakamoto).
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.05.064

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T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
Figure 1. Spiroindoline Y5 antagonists.
Scheme 1. Reagents and conditions: (a) chlorophenylformate, pyridine, rt, or chlorophenylformate, Et3N, THF, rt; (b) 10 M NaOHaq, DMSO, rt or Et3N, 1,2-dichloroethane,
reflux.
carbamates 5 were generally made from the reaction between bi-
aryl amines 4 and phenyl chloroformate. The aryl amines 4 were
either purchased from suppliers as commercially available re-
agents or prepared using standard synthesis protocols.26–40
compounds 2a, 2b, and 2c. While these modifications decreased Y5
binding affinities 2–5-fold, the bioavailability of these compounds
was improved. (12%, 47%, and 53%, respectively) Introduction of a
pyridine moiety in the inner phenyl ring produced 2d and 2e,
which retained Y5 affinities. Since incorporation of a nitrogen atom
into the inner phenyl ring looked more tolerable in terms of Y5
affinities, heteroaromatics bearing two nitrogen atoms, such as
pyridazine, pyrazine, and pyrimidine, were introduced at this posi-
tion. With the exception of 2f, all compounds with an inner hetero-
aromatic ring exhibited high Y5 affinities. The meta-substitution,
2j–l, was also investigated, but resulted in deceased potency com-
pared to the para-substitution. In terms of bioavailability, com-
pounds 2f and 2i were the only two compounds among the 6-
membered inner heteroaromatic ring analogs to have detectable
plasma concentrations after oral administration.
3. Results and discussion
Previously reported lead compound 1 had high Y5 binding affin-
ity, but unacceptable oral bioavailability (F = 0%). This can be ex-
plained by its poor solubility (<0.01 lg/mL at pH 1, 3, 5, and 7)
and high lipophilicity (log D at pH 7.4 >4). To address this, we first
incorporated one or two nitrogen atoms into the biaryl part of the
compound. The binding affinities and bioavailabilities of these
derivatives are shown in Figure 2. Introduction of a nitrogen atom
on the outer phenyl ring produced ortho-, meta-, and para-pyridyl
Figure 2. Y5 binding affinities and bioavailability of compounds 1, 2a–l. NT, not tested. a Values are the mean of two or more independent assays.41 b Bioavailability (F(%)) was
calculated from administration at 3 mpk iv and at 10 mpk po dosing in SD rats (n = 2).43

T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
5017
Table 1
Profile of compounds 2a–c
H
O
N
N
Ar
N
S
O
O
Me
a
c
c
c
Compound
Ar
IC50 (nM)
Fb (%)
CLtot (mL/min/kg)
Cmax
(
lM)
Tmax (h)
AUCc
1.8
(lM h)
B/Pd
0.22
bPPe MEDf (mg)
>100
2a
3
12
24.4
0.6
0.25
1
N
2b
2.1
4.1
47
53
13.3
17.8
4.7
5.5
12.7
10.8
0.13
0.12
100*
10**
N
2c
1
N
a
Values are the mean of two or more independent assays.41
Bioavailability (F(%)) was calculated from administration at 3 mpk iv and at 10 mpk po dosing in SD rats (n = 2).43
Other PK parameters were calculated by the trapezoidal method from the plasma concentration at 5 min, 1 h, and 4 h after 3 mpk iv dosing and 0.5 h, 1 h, and 2 h after
b
c
10 mpk po dosing.
d
B/P (brain/plasma) ratio was shown as brain penetration 10 min after 3 mpk iv dosing in rats (n = 2).
bPP inhibition was calculated from the cumulative food intake from 0 h to 2 h after po dosing in SD rats (n = 7 or more).
MED (minimum effective dose; mg) in the bPP assay was shown as statistically-significant (*P < 0.05, **P < 0.01).
e
f
Compounds 2a–c, which incorporate a nitrogen atom in the
outer phenyl ring, were evaluated for their brain penetration abil-
ity and subsequently for their inhibitory effect on food intake in-
duced by the Y5 agonist, bovine pancreatic polypeptide (bPP)
(Table 1). It has been reported that intracerebroventricular (ICV)
administration of bPP, which is a Y5 agonist peptide, in SD rats sig-
nificantly enhances appetite as a Y5 efficacy of bPP. Treatment with
Y5 antagonists, such as 2a–c, competitively suppressed feeding in-
duced by bPP, and 2b and 2c showed statistically significant effi-
cacy at doses of 100 mg/kg or lower in this bPP-induced food
intake study. Comparison of the pharmacokinetics of compound
2c and lead compound 1 showed that the oral bioavailability of
2c was improved dramatically (F = 53%), but its brain penetrability
was lower (B/P = 0.12). The pharmacokinetic profiles, including
brain penetration, were important for indicating their in vivo effi-
cacy, and their binding efficacies were sufficiently high to show
their bPP-induced food intake efficacy. We next evaluated com-
pound 2c for its suppression effect on body weight in a diet-in-
duced obesity (DIO) model study.44 DIO mice generally gain
weight after eating moderately high fat diets, but the continuous
blockade of Y5 receptor suppresses body weight gain. Y5 antago-
nist 2c at 100 mg/kg oral dosing did not suppress body weight gain
in the DIO model study (data not shown). We speculated that in or-
der to be effective in the DIO model study, the compound must
have both better intrinsic potency and a better PK profile, including
bioavailability. We therefore further optimized the bi-aryl parts of
the spiroindoline skeleton in order to adjust pharmacokinetic
properties while maintaining potency.
imidazolyl, 2x, had decreased potency. Other biaryl analogues,
2t–w and 2y–ac showed slightly decreased potency compared to
lead compound 1. Fused rings, 2ad–ah, had overall lower potency
than the bi-aryl series.
Compounds with acceptable potency were screened using rat
PK studies,43 as shown in Figure 4. Compounds with a 5-membered
ring inside tended to have better bioavailability compared to com-
pounds with a 5-membered ring outside. Compounds 2ab, 2ac, and
2af showed greater than 20% bioavailability.
Compounds 2y, 2ab, 2ac, and 2af were found to have acceptable
bioavailability, and so their brain penetration and effect on bPP
food intake was assayed (Table 2). The brain penetrability of 2y
and 2af was too low (B/P = 0.02 and 0.03, respectively) to show
efficacy in bPP food intake. Of these four compounds, the isoxazole,
2ab, had the best B/P ratio, but no efficacy was observed when
tested in the bPP food intake assay. Although we were surprised
that none of the selected compounds showed efficacy, we further
characterized the phenyl imidazole compound, 2ac. This com-
pound was expected to show some basicity, with the imidazole
ring changing the physicochemical properties of the entire com-
pound. Log D value at pH 7.4 of compound 2ac was lowest among
4 compounds; however, 2ac had moderate brain penetrability be-
cause of the basicity of phenyl imidazole. To our knowledge, basic
and lipophilic compounds tend to better penetrate into the brain.
The balance of basicity and lipophilicity could lead to a brain pen-
etrable orally active compound.
Adjustment of lipophilicity by modification of the phenyl ring
substitution or the spiroindoline moiety was examined. These
derivatives were prepared as shown in Schemes 2 and 3. The
substituted phenyl imidazoles were obtained using previously re-
ported methods for phenyl imidazole.40 Derivatives 3, with an eth-
anesulfonyl group instead of a methanesulfonyl group on the
spiroindoline, were prepared using the same synthetic approach26
as used for the synthesis of the methanesulfonyl group. Results are
summarized in Table 3.
Extensive exploration of the right biaryl site was conducted,
providing compounds such as substituted mono aryl rings 2n–r,
bi-aryl compounds containing a 5-membered ring 2s–ac, and fused
aromatic rings 2ad–ah. The Y5 affinities of these compounds are
summarized in Figure 3. Mono aryl ring compounds 2m–r demon-
strated that substituents at the para position are necessary for po-
tency, since the compound without a substituent, 2m, showed no
Y5 affinity. Benzophenone 2q was the most potent of these com-
pounds (IC50 = 0.68 nM). In the bi-aryl type compounds, various
5-membered heteroaromatics were introduced at either the inner
or outer bi-aryl part. The 1,3,4-triazolyl, 2s, and the 1-methyl-2-
The brain penetrability of compound 3a was moderately im-
proved (B/P ratio 0.22) compared to compound 2ac, and showed
efficacy in the in vivo bPP assay (MED = 3 mpk). The potential mod-
ifications around 3a led to identify ortho-fluoro derivative 3b,

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T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
a
Figure 3. Y5 binding affinities of compounds 2e–ah. Values are the mean of two or more independent assays.41
Figure 4. Y5 binding affinities and bioavailability of selected compounds. a Values are the mean of two or more independent assays.41 b Bioavailability (F(%)) was calculated
from administration at 3 mpk iv and at 10 mpk po dosing in SD rats (n = 2).43
Table 2
Results of brain penetrability and bPP food intake assays of compounds 2y, 2ab, 2ac, and 2af, and their physicochemical properties
Fb (%)
B/P ratioc
Log D (pH 7.4)d
pKa
MEDf bPPg (mg)
a
e
Compound
IC50 (nM)
2y
1.4
1.3
2.4
2.5
13
23
27
24
0.02
0.22
0.10
0.03
3.08
2.53
2.15
2.74
NC
NC
6.25
5.37
>30
>30
>30
>30
2ab
2ac
2af
NC, not calculated.
a
Values are the mean of two or more independent assays.41
Bioavailability (F(%)) was calculated from administration at 3 mpk iv and at 10 mpk po dosing in SD rats (n = 2).43
B/P (brain/plasma) ratio is shown as brain penetration 10 min after 3 mpk iv dosing in rats (n = 2).
Values of log D at pH 7.4 were calculated by ACD/log D software (ver. 11.01).
Values of pKa were calculated by ACD/pKa DB software (ver. 11.01).
bPP inhibition was calculated from the cumulative food intake from 0 h to 2 h after 30 po dosing (n = 7 or more).
MED (minimum effective dose; mg) of bPP assay was shown as being statistically significant. (*P < 0.05, **P < 0.01).
b
c
d
e
f
g
which was shown to have similar profiles as 3a, and was effective
at 3 mpk in the bPP food intake study. Methanesulfonyl 2ai, which
has ortho-fluoro phenyl ring, was also not effective compared to
ethanesulfonyl 3b. meta-Methoxy 3f was effective at 10 mpk in
the bPP food intake study. Overall, ethyl substitution on spiroind-
oline seemed to improve the profile more than phenyl substitution

T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
5019
Scheme 2. Reagents and conditions: (a) HNO3, H2SO4, Ac2O, rt, 1 h; (b) anilines, MeOH, H2O, rt, overnight; (c) Pd(OH)2, THF, MeOH, rt, 1 h then phenyl chlorocarbomate.
Scheme 3. Reagents and conditions: (a) ethanesulfonyl chloride, Et3N, rt, 30 min; b) H2, Pd(OH)2–C, MeOH, THF, rt, 1 h; (c) Et3N, CHCl3, reflux.
on the biaryl amine part. Therefore, further investigations focused
on compound 3a. The pharmacokinetics profiles of the representa-
tive compounds 2ac and 3a are shown in Table 4. Head to head
comparison revealed that compound 3a is superior to 2ac with re-
spect to PK parameters (F, CLtot, AUC) and brain penetrability.
After ICV administration of bPP, 3a significantly inhibited
bPP-induced food intake (Fig. 5). Oral administration of 3a (1,
3, and 10 mg/kg) showed moderate dose-dependent efficacy in
suppressing feeding induced by bPP. The brain concentration of
3a in SD rats 2 h after oral administration (10 mg/kg) was
0.64 nmol/g. The result from this artificial food intake study re-
quired confirmation with a DIO model study, which is more
applicable to the actual disease. Compound 3a was therefore
evaluated in a DIO model study.44,45 The control mice continu-
ously gained weight over 13 consecutive days, whereas mice
treated with 3a (30 mg/kg) had significantly suppressed weight
gain (Fig. 6). Moreover, their cumulative food intake was 8.8%
lower than the controls. We also evaluated the effect of 3a on
the body weight change in DIO of Y5 knock-out mice (data not
shown), and found that compound 3a did not suppress weight
gain. Taken together, these results indicate that compound 3a
suppresses body weight gain in DIO mice by a Y5 anti-obesity
mechanism.
the right bi-aryl part of the compound was shown to be impor-
tant for in vivo potency. Compound 3a had satisfactory pharma-
cokinetic profiles and brain penetrability in an in vivo animal
model. Oral administration of 3a showed moderate dose–depen-
dent efficacy in suppressing feeding induced by bPP. In a DIO
model, 3a resulted in continuous suppression of weight gain
and an 8.8% decrease in cumulative food intake versus the
controls.
5. Experimental
5.1. Materials and methods
All reagents were obtained from commercial suppliers and
used without further purification or drying. TLC was performed
with Merck Silica Gel 60 F254 pre-coated plates. Silica gel col-
umn chromatography was carried out on Wakogel C-300 (mesh
45–75
with Moritex NH 60
l
m) or an appropriately sized pre-packed silica cartridge
l
M (purchased from Moritex). 1H NMR
spectra were recorded on a JEOL JNM-AL 400 spectrometer at
400 MHz, a Varian Gemini 300 spectrometer at 300 MHz, or a
Varian Gemini 200 spectrometer at 200 MHz, and are referenced
to residual solvent peaks (DMSO-d6,
d 2.49 ppm; CD3OD, d
3.30 ppm) or to an internal standard of tetramethylsilane (TMS,
d 0.00 ppm). Mass spectra were recorded with electronspray ion-
ization (ESI) or atmospheric pressure chemical ionization (APCI)
on a Waters micromass ZQ, micromass Quattro II or micromass
Q-Tof-2 instrument.
4. Conclusion
A series of spiroindoline derivatives was synthesized and
evaluated as NPY Y5 receptor antagonists. Phenyl imidazole on

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T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
Table 3
Effect of substituents in the phenyl imidazole series
H
O
N
N
N
R2
N
N
S
O
O
R1
MEDb bPPc (mg)
>30
Fd (%)
B/P ratioe
0.10
a
Compound
R1
R2
IC50 (nM)
2ac
Me
2.4
27
3a
3b
3c
Et
3.4
3.3
3.0
4.1
3.9
1.8
4.9
3**
37
23
23
NT
NT
NT
NT
0.22
0.25
0.18
NT
F
Et
3**
F
Et
30**
>30
>30
>30
>30
3d
2ai
2aj
3e
Et
F
F
Me
Me
Et
NT
F
NT
MeO
NT
OMe
3f
Et
Et
2.0
3.2
10*
NT
50.1
NT
0.11
NT
3g
OMe
NT, not tested.
a
Values are the mean of two or more independent assays.41
bPP inhibition was calculated from the cumulative food intake from 0 h to 2 h after 30 po dosing (n P 7).
MED (minimum effective dose; mg) of the bPP assay was shown as being statistically significant. (*P < 0.05, **P < 0.01).
F(%) was calculated from administration at 3 mpk iv and at 10 mpk po dosing in SD rats.43
b
c
d
e
B/P (brain/plasma) ratio was shown as brain penetration 10 min after 3 mpk iv dosing in rats.
5.2. Chemistry
give crude phenyl carbamates 5a–ah, which were used in the next
reaction without further purification.
5.2.1. General procedure for the synthesis of phenyl carbamate
5a–ah
5.2.2. Synthesis procedure for compounds, 2a–aj
The general procedure for the synthesis of phenyl carbamates is
described in Ref. 19. To the solution of the corresponding amine
4a–ah (2.00 mmol) in pyridine (5.00 mL) was added phenyl chloro-
5.2.2.1. 1-(Methylsulfonyl)-N-[4-(pyridin-2-yl)phenyl]-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2a). To
the solution of 5a (130 mg, 0.450 mmol) and
0.490 mmol) in DMSO (2.00 mL) was added aqueous 10 M NaOH
(50.0 L, 0.500 mmol). After stirring vigorously for 2 h, H2O was
6 (136 mg,
formate (274 lL, 2.20 mmol) at room temperature. After stirring
overnight, AcOEt and 10% aqueous citric acid were added and the
mixture was extracted with AcOEt. The organic layer was washed
with saturated aqueous NaHCO3 and brine, dried over Na2SO4,
and filtered. The solvent was removed under reduced pressure to
l
added and the mixture was extracted with AcOEt. The organic
layer was washed with brine, dried over Na2SO4, and filtered. The
solvent was removed under reduced pressure and the residue

T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
5021
J = 13.6 Hz); HRMS (ESI+) m/z [M+H]+ 463.1806 (C25H27N4O3S re-
quires: 463.1804).
Table 4
Profiles of compounds 2ac and 3a
H
H
O
O
N
N
5.2.2.2. 1-(Methylsulfonyl)-N-[4-(pyridin-3-yl)phenyl]-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2b). To
the solution of 5b (2.94 g, 10.1 mmol) and 6 (3.37 g, 11.1 mmol)
in 1,2-dichloroethane (6.00 mL) was added Et3N (5.70 mL,
40.9 mmol). After reflux for 1.5 h, diluted aqueous NaOH was
added and the mixture was extracted with CHCl3. The organic layer
was washed with brine, dried over Na2SO4, and filtered. The sol-
vent was removed under reduced pressure, and the residue was
collected by filtration and washed with EtOH to give 2b (2.86 g,
61%) as a yellow solid. Compound 2b was treated with 4 N HCl
in AcOEt to afford 2b HCl salt: 1H NMR (300 MHz; DMSO-d6): d
8.86 (1H, d, J = 1.8 Hz), 8.51–8.49 (1H, m), 8.05–8.01 (1H, m),
7.64 (4H, s), 7.44 (1H, dd, J = 7.9, 4.4 Hz), 7.37–7.21 (3H, m), 7.05
(1H, td, J = 7.3, 1.4 Hz), 4.18 (2H, br d, J = 13.6 Hz), 3.93 (2H, s),
3.06 (3H, s), 3.06–2.97 (2H, m), 1.85–1.68 (4H, m); HRMS (ESI+)
m/z [M+H]+ 463.1795 (C25H27N4O3S requires: 463.1804).
N
N
N
N
N
N
N
N
O
O
S
Me
S
O
O
Et
3a
2ac
2ac
3a
a
IC50
2.4
27
3.9
25.3
0.10
>30
3.4
37
2.5
58.9
0.22
3**
Fb (%)
b
CLtot (mL/min/kg)
AUCb
(l
M h)
B/P ratioc
MED in bPPd,e (mg)
a
Values are the mean of two or more independent assays.41
b
PK data (F, CLtot, AUC) are from administration at 3 mpk iv and at 10 mpk po
5.2.2.3. 1-(Methylsulfonyl)-N-[4-(pyridin-4-yl)phenyl]-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2c); 1.65
g (97%). Compound 2c was treated with 4 N HCl in AcOEt to afford
2c HCl salt: 1H NMR (300 MHz; DMSO-d6): d 8.78 (1H, s), 8.57 (2H,
d, J = 5.3 Hz), 7.76–7.66 (6H, m), 7.35–7.02 (4H, m), 4.19 (2H, d,
J = 13.5 Hz), 3.94 (2H, s), 3.07 (3H, s), 3.07–2.99 (2H, m), 1.89–
1.73 (4H, m); HRMS (ESI+) m/z [M+H]+ 463.1802 (C25H27N4O3S re-
quires: 463.1804).
dosing in SD rats (n = 2).43
c
B/P (brain/plasma) ratio is shown as brain penetration 10 min after 3 mpk iv
dosing in rats.
bPP inhibition was calculated from the cumulative food intake from 0 h to 2 h
after po dosing (n = 6 for 2ac; n P 10 for 3a).
MED (minimum effective dose; mg) of the bPP assay was shown as being sta-
tistically significant. (* P < 0.05, P < 0.01).
d
e
**
5.2.2.4. 1-(Methylsulfonyl)-N-(5-phenylpyridin-2-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2d); 200
mg (84%). 1H NMR (300 MHz; CDCl3): d 8.45 (1H, d, J = 1.8 Hz),
8.13 (1H, d, J = 8.2 Hz), 7.91 (1H, dd, J = 8.7, 2.5 Hz), 7.57 (2H, d,
J = 8.6 Hz), 7.49–7.37 (4H, m), 7.30–7.23 (1H, m), 7.17 (1H, dd,
J = 7.6, 1.0 Hz), 7.09 (1H, dd, J = 7.4, 1.0 Hz), 4.21 (2H, br d,
J = 13.4 Hz), 3.90 (2H, s), 3.20–3.05 (2H, m), 2.94 (3H, s), 2.05–
1.93 (2H, m), 1.82 (2H, br d, J = 13.8 Hz); HRMS (ESI+) m/z [M+H]+
463.1794 (C25H27N4O3S requires: 463.1804).
5.2.2.5. 1-(Methylsulfonyl)-N-(6-phenylpyridin-3-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2e); 180
mg (87%). 1H NMR (300 MHz; CDCl3): d 8.52 (1H, d, J = 2.6 Hz),
8.15–8.10 (1H, m), 7.95 (2H, dd, J = 7.6 Hz), 7.71 (1H, d,
J = 8.6 Hz), 7.50–7.38 (4H, m), 7.30–7.23 (1H, m), 7.18–7.17 (1H,
m), 7.09 (1H, t, J = 7.5 Hz), 6.58 (1H, s), 4.20–4.10 (2H, br d), 3.90
(2H, s), 3.20–3.05 (2H, m), 2.95 (3H, s), 2.05–1.93 (2H, m), 1.90–
1.80 (2H, m); HRMS (ESI+) m/z [M+H]+ 463.1813 (C25H27N4O3S re-
quires: 463.1804).
5.2.2.6. 1-(Methylsulfonyl)-N-(6-phenylpyridazin-3-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2f); 177
mg (76%). 1H NMR (400 MHz; CDCl3): d 8.37 (1H, br s), 8.00 (2H,
d, J = 7.3 Hz), 7.85 (1H, d, J = 9.3 Hz), 7.54–7.45 (4H, m), 7.42 (1H, d,
J = 7.8 Hz), 7.16 (1H, d, J = 7.3 Hz), 7.08 (1H, t, J = 7.6 Hz), 4.29 (2H,
br s), 3.91 (2H, s), 3.17–3.07 (2H, m), 2.94 (3H, s), 1.99 (2H, td,
J = 13.2, 4.4 Hz), 1.84 (2H, d, J = 13.2 Hz); HRMS (ESI+) m/z [M+H]+
464.1764 (C24H26N5O3S requires: 464.1756).
Figure 5. bPP-induced food intake study of compound 3a (po dosing) in SD rats.
Compound 3a was orally administered 1 h before bPP icv injection. The graphs
show the cumulative food intake in SD rats for 2 h after icv injection of bPP.
Significant differences with respect to the vechicle treated group are indicated by an
asterisk (*P < 0.05, **P < 0.01). The data shown are expressed as the mean SE.
n = 10–12 rats/group (represented in the bar graph).
was purified by flash chromatography on silica gel (Hexane/EtOAc:
1/2) to give 2a (123 mg, 70%) as a white solid. 2a was treated with
4 N HCl in AcOEt to afford 2a HCl salt: 1H NMR (300 MHz; CD3OD):
d 8.75 (1H, d, J = 5.4 Hz), 8.62 (1H, t, J = 7.7 Hz), 8.38 (1H, d,
J = 8.1 Hz), 7.98–7.93 (1H, m), 7.92 (2H, d, J = 9.0 Hz), 7.78 (2H, d,
J = 9.0 Hz), 7.39 (1H, d, J = 8.3 Hz), 7.22–7.29 (2H, m), 7.09 (1H, t,
J = 7.7 Hz), 4.26 (2H, d, J = 13.2 Hz), 3.99 (2H, s), 3.18 (2H, t,
J = 13.0 Hz), 2.99 (3H, s), 2.05–1.94 (2H, m), 1.83 (2H, d,
5.2.2.7. 1-(Methylsulfonyl)-N-(5-phenylpyrazin-2-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2g); 202
mg (67%). 1H NMR (300 MHz; DMSO-d6): d 9.67 (1H, br s), 9.13 (1H,
d, J = 1.4 Hz), 8.90 (1H, d, J = 1.5 Hz), 8.08 (2H, dd, J = 8.3, 1.4 Hz),
7.53–7.39 (6H, m), 7.34 (1H, d, J = 7.3 Hz), 7.30–7.19 (2H, m), 7.05
(1H, td, J = 7.5, 1.5 Hz), 4.23 (2H, br d, J = 14.8 Hz), 3.93 (2H, s),
3.09–3.00 (2H, m), 3.05 (3H, s), 1.84–1.67 (4H, m); HRMS (ESI+)
m/z [M+H]+ 464.1750 (C24H26N5O3S requires: 464.1756).

5022
T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
Figure 6. DIO-model study of compound 3a at 30 mpk po in C57BL/6J mice. Significant differences with respect to vehicle-administered controls are indicated by an asterisk
after day 6 (*P < 0.05). The DIO model study used C57BL mice, whose weights were between 25.5–31.1 g (vehicle) and 26.0–31.9 g (compound 3a). n = 10 mice/group.
5.2.2.8. 1-(Methylsulfonyl)-N-(2-phenylpyrimidin-5-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2h); 161
mg (54%). 1H NMR (300 MHz; DMSO-d6): d 9.02 (2H, s), 8.34–8.30
(2H, m), 7.53–7.45 (3H, m), 7.36 (1H, d, J = 7.2 Hz), 7.30–7.20
(2H, m), 7.05 (1H, td, J = 7.1, 1.4 Hz), 4.19 (2H, br d, J = 14.8 Hz),
3.94 (2H, s), 3.12–3.01 (2H, m), 3.06 (3H, s), 1.98–1.70 (4H, m);
HRMS (ESI+) m/z [M+H]+ 464.1754 (C24H26N5O3S requires:
464.1756).
1.88–1.70 (4H, m); HRMS (ESI+) m/z [M+H]+ 463.1811
(C25H27N4O3S requires: 463.1804).
5.2.2.13. 1-(Methylsulfonyl)-N-(pyridin-3-yl)-1,2-dihydro-10H-
spiro[indole-3,40-piperidine]-10-carboxamide (2m); 103 mg
(81%). 1H NMR (300 MHz; CDCl3): d 9.2–8.5 (1H, br s), 8.30 (1H,
dd, J = 9.1, 1.1 Hz), 8.14 (1H, dd, J = 4.4, 0.9 Hz), 7.87–7.81 (1H,
m), 7.42 (1H, d, J = 8.2 Hz), 7.29–7.05 (3H, m), 4.37–4.30 (2H, m),
3.89 (2H, s), 3.16–3.06 (2H, m), 2.94 (3H, s), 2.02–1.91 (2H, m),
1.85–1.80 (2H, m); HRMS (ESI+) m/z [M+H]+ 387.1491
(C19H23N4O3S requires: 387.1491).
5.2.2.9. 1-(Methylsulfonyl)-N-(5-phenylpyrimidin-2-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2i); 165
mg (80%). 1H NMR (300 MHz; DMSO-d6): d 9.68 (1H, br s), 8.88
(2H,s), 7.73 (2H, d, J = 8.1 Hz), 7.49 (2H, d, J = 7.4 Hz), 7.43–7.40
(6H, m), 7.38–7.20 (3H, m), 7.06(1H, td, J = 7.5, 1.5 Hz), 4.11 (2H,
br d, J = 13.8 Hz), 3.92 (2H, s), 3.09–2.98 (2H, m), 3.05 (3H, s),
1.87–1.66 (4H, m); HRMS (ESI+) m/z [M+H]+ 464.1745
(C24H26N5O3S requires: 464.1756).
5.2.2.14. N-(6-Chloropyridin-3-yl)-1-(methylsulfonyl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2n); 279
mg (77%). 1H NMR (300 MHz; CDCl3): d 8.32 (1H, d, J = 1.9 Hz),
8.05 (1H, dd, J = 8.7, 2.9 Hz), 7.41 (1H, d, J = 8.2 Hz), 7.31–7.23
(2H, m), 7.17 (1H, dd, J = 7.7, 1.2 Hz), 7.09 (1H, ddd, J = 7.4, 7.4,
1.0 Hz), 6.73 (1H, s), 4.18–4.11 (2H, m), 3.88 (2H, s), 3.15–3.04
(2H, m), 2.94 (3H, s), 2.02–1.91 (2H, m), 1.84–1.78 (2H, m); HRMS
(ESI+) m/z [M+H]+ 421.1110 (C19H22N4O3S requires: 421.1101).
5.2.2.10.
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2j);
134 mg (78%). 1H NMR (300 MHz, CDCl3):
8.66 (1H, d,
1-(Methylsulfonyl)-N-(2-phenylpyrimidin-4-yl)-1,2-
d
5.2.2.15. N-(5-Chloropyridin-2-yl)-1-(methylsulfonyl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2o); 71.8
mg (21%). 1H NMR (300 MHz; CDCl3): d 8.16 (1H, d, J = 2.6 Hz),
8.04 (1H, d, J = 9.0 Hz), 7.64 (1H, dd, J = 9.0, 2.6 Hz), 7.42 (1H, m),
7.31–7.03 (4H, m), 4.20–4.10 (2H, m), 3.89 (2H, s), 3.17–3.01 (2H,
m), 2.94 (3H, s), 2.04–1.77 (2H, m), 1.67–1.59 (2H, m); HRMS
(ESI+) m/z [M+H]+ 421.1110 (C19H22N4O3S requires: 421.1101).
J = 5.9 Hz), 8.36 (2H, td, J = 5.2, 2.6 Hz), 7.92 (1H, d, J = 5.9 Hz),
7.50–7.41 (5H, m), 7.30–7.25 (1H, m), 7.18 (1H, dd, J = 7.8,
1.0 Hz), 7.09 (1H, td, J = 7.6, 1.0 Hz), 4.22 (2H, d, J = 13.7 Hz), 3.91
(2H, s), 3.14 (2H, td, J = 13.3, 2.3 Hz), 2.95 (3H, s), 1.98 (2H, td,
J = 13.2, 4.2 Hz), 1.85 (2H, d, J = 13.7 Hz); HRMS (ESI+) m/z [M+H]+
464.1750 (C24H26N5O3S requires: 464.1756).
5.2.2.16. N-(4-Acetylphenyl)-1-(methylsulfonyl)-1,2-dihydro-10H-
spiro[indole-3,40-piperidine]-10-carboxamide (2p); 175 mg (91%)
as a white solid. 1H NMR (300 MHz; CDCl3): d 7.92 (2H, d, J =
8.7 Hz), 7.51 (2H, d, J = 8.7 Hz), 7.40 (1H, dd, J = 7.8 Hz), 7.29–7.22
(1H, m), 4.20–4.05 (2H, m), 6.87 (1H, s), 4.23–4.10 (2H, m), 3.87
(2H, s), 3.15–3.03 (2H, m), 2.94 (3H, s), 2.56 (3H, s), 2.05–1.90 (2H,
m), 1.86–1.74 (2H, m); HRMS (ESI+) m/z [M+H]+ 428.1648
(C22H26N3O4S requires: 428.1644).
5.2.2.11. 1-(Methylsulfonyl)-N-(4-phenylpyrimidin-2-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2k); 167 mg
(75%). 1H NMR (300 MHz; DMSO-d6): d 9.53 (1H, s), 8.61 (1H, d,
J = 5.2 Hz), 8.18–8.14 (2H, m), 7.59–7.52 (4H, m), 7.29–7.19 (3H, m),
7.07–7.01 (1H, m), 4.12 (1H, br d, J = 13.9 Hz), 3.92 (2H, s), 3.09–
3.00 (2H, m), 3.04 (3H, s), 1.88–1.77 (2H, m), 1.71–1.66 (2H, m); HRMS
(ESI+) m/z [M+H]+ 464.1764 (C24H26N5O3S requires: 464.1756).
5.2.2.12.
1-(Methylsulfonyl)-N-[3-(pyridin-4-yl)phenyl]-1,2-
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2l);
315 mg (99%). Compound 2l was treated with 4 N HCl in AcOEt
to afford 2l HCl salt (240 mg, 75%): 1H NMR (300 MHz; DMSO-
d6): d 8.97–8.92 (3H, m), 8.26–8.19 (3H, m), 7.76–7.72 (1H, m),
7.58–7.47 (2H, m), 7.34–7.21 (3H, m), 7.06 (1H, t, J = 7.2 Hz),
4.28–4.20 (2H, m), 3.95 (2H, s), 3.07 (3H, s), 3.10–2.99 (2H, m),
5.2.2.17. 1-(Methylsulfonyl)-N-[4-(phenylcarbonyl)phenyl]-1,2-
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2q);
163 mg (67%). 1H NMR (400 MHz; CDCl3):
d 7.82 (2H, d,
J = 8.8 Hz), 7.78 (2H, dd, J = 8.2, 1.3 Hz), 7.58 (1H, tt, J = 7.4,
1.5 Hz), 7.51 (2H, d, J = 8.5 Hz), 7.48 (2H, t, J = 7.1 Hz), 7.42 (1H,
d, J = 8.3 Hz), 7.27 (1H, td, J = 7.6, 1.5 Hz), 7.18 (1H, dd, J = 7.7,

T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
5023
1.1 Hz), 7.09 (1H, td, J = 7.4, 1.1 Hz), 6.65 (1H, s), 4.16 (2H, d,
J = 13.9 Hz), 3.90 (2H, s), 3.11 (2H, td, J = 13.2, 2.2 Hz), 2.95 (3H,
s), 1.99 (2H, dt, J = 18.9, 6.8 Hz), 1.83 (2H, d, J = 13.9 Hz); HRMS
(ESI+) m/z [M+H]+ 490.1809 (C27H28N3O4S requires: 490.1801).
5.2.2.25. 1-(Methylsulfonyl)-N-(3-phenyl-1H-pyrazol-5-yl)-1,2-
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2y);
140 mg (79%). 1H NMR (300 MHz; CDCl3):
d 7.63 (2H, d,
J = 7.8 Hz), 7.50–7.40 (3H, m), 7.40–7.08 (6H, m), 6.72 (1H, s),
4.15–4.10 (2H, m), 3.89 (2H, s), 3.15–3.02 (2H, m), 2.94 (3H, s),
2.00–1.70 (4H, m); HRMS (ESI+) m/z [M+H]+ 452.1758
(C23H26N5O3S requires: 452.1756).
5.2.2.18. 1-(Methylsulfonyl)-N-(4-phenoxyphenyl)-1,2-dihydro-
10H-spiro[indole-3,40-piperidine]-10-carboxamide (2r); 375 mg
(79%). 1H NMR (300 MHz; CDCl3): d 7.48–7.25 (6H, m), 7.25–
6.95 (7H, m), 6.38 (1H, s), 4.20–4.05 (2H, m), 3.89 (2H, s), 3.17–
3.00 (2H, m), 2.94 (3H, s), 2.08–1.88 (2H, m), 1.88–1.72 (2H, m);
HRMS (ESI+) m/z [M+H]+ 178.1809 (C26H28N3O4S requires:
478.1801).
5.2.2.26. 1-(Methylsulfonyl)-N-(5-phenyl-1,3-thiazol-2-yl)-1,2-
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2z);
232 mg (72%). 1H NMR (200 MHz; CDCl3): d 11.80–11.10 (1H, br
s), 7.50–7.30 (6H, m), 7.30–7.00 (4H, m), 4.90–4.38 (2H, br m),
3.90 (2H, s), 3.16–2.80 (2H, m), 2.90 (3H, s), 2.00–1.70 (4H, m);
HRMS (ESI+) m/z [M+H]+ 469.1368 (C23H25N4O3S2 requires:
469.1368).
5.2.2.19. 1-(Methylsulfonyl)-N-[4-(2H-1,2,3-triazol-2-yl)phenyl]-
1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide
(2s); 160 mg (59%). 1H NMR (300 MHz; DMSO-d6): d 8.43(2H, s),
7.60 (1H, d, J = 9.0 Hz), 7.42 (1H, d, J = 8.3 Hz), 7.34–7.25 (3H, m),
7.19 (1H, d, J = 8.1 Hz), 7.10 (1H, t, J = 7.7 Hz), 6.80 (1H, s), 4.20–
4.12 (2H, m), 3.90 (2H, s), 3.18–3.08 (2H, m), 2.96 (3H, s), 2.00–
1.92 (2H, m), 1.89–1.80 (2H, m); MS(ESI+) 453 [M+H]+.
5.2.2.27. 1-(Methylsulfonyl)-N-(5-phenyl-1,3,4-thiadiazol-2-yl)-
1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide
(2aa); 387 mg (83%). 1H NMR (300 MHz; CDCl3): d 7.85 (2H, d,
J = 7.3 Hz), 7.45–7.42 (4H, m), 7.30–7.21 (3H, m), 7.10 (1H, t,
J = 6.8 Hz), 4.46 (2H, d, J = 14.6 Hz), 3.93 (2H, s), 3.19 (2H, t,
J = 12.2 Hz), 2.93 (3H, s), 2.09 (2H, td, J = 13.7, 4.7 Hz), 1.87 (2H,
d, J = 13.7 Hz); HRMS (ESI+) m/z [M+H]+ 470.1312 (C22H24N5O3S2
requires: 470.1321).
5.2.2.20. 1-(Methylsulfonyl)-N-[4-(1H-pyrazol-1-yl)phenyl]-1,2-
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2t);
185 mg (82%). 1H NMR (300 MHz; CDCl3):
d 7.88 (1H, d,
J = 2.4 Hz), 7.70 (1H, d, J = 1.5 Hz), 7.62 (2H, d, J = 8.8 Hz), 7.49
(2H, d, J = 9.3 Hz), 7.41 (1H, d, J = 7.8 Hz), 7.18 (1H, d, J = 6.8 Hz),
7.09 (1H, t, J = 7.3 Hz), 6.65 (1H, s), 6.46 (1H, t, J = 2.0 Hz), 4.16
(2H, d, J = 13.7 Hz), 3.89 (2H, s), 3.08–3.04 (2H, m), 2.94 (3H, s),
1.97 (2H, td, J = 13.2, 4.2 Hz), 1.81 (2H, d, J = 13.2 Hz); HRMS
(ESI+) m/z [M+H]+ 452.1748 (C23H26N5O3S requires: 452.1756).
5.2.2.28. 1-(Methylsulfonyl)-N-(3-phenylisoxazol-5-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2ab); 215
mg (84%) as a white solid. 1H NMR (300 MHz; CDCl3): d 7.83–7.77
(3H, m), 7.48–7.39 (4H, m), 7.26 (1H, t, J = 7.5 Hz), 7.15 (1H, d,
J = 7.5 Hz), 7.06 (1H, t, J = 7.5 Hz), 6.57 (1H, s), 4.20–4.10 (2H, br
m), 3.88 (2H, s), 3.19–3.06 (2H, m), 2.95 (3H, s), 2.01–1.90 (2H,
m), 1.87–1.78 (2H, m); HRMS (ESI+) m/z [M+H]+ 453.1586
(C23H25N4O4S requires: 453.1597).
5.2.2.21. 1-(Methylsulfonyl)-N-[4-(1,3-thiazol-2-yl)phenyl]-1,2-
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2u);
352 mg (89%). 1H NMR (300 MHz; CDCl3):
d 7.92 (2H, d,
J = 8.7 Hz), 7.83 (1H, d, J = 3.3 Hz), 7.49 (2H, d, J = 8.7 Hz),
7.46–7.30 (1H, m), 7.27 (1H, d, J = 3.3 Hz), 7.30–7.23 (1H, m),
7.23–7.01 (2H, m), 6.53 (1H, s), 4.23–4.07 (2H, m), 3.90 (2H, s),
3.20–3.01 (2H, m), 2.94 (3H, s), 2.10–1.75 (4H, m); HRMS (ESI+)
m/z [M+H]+ 469.1368 (C23H25N4O3S2 requires: 469.1368).
5.2.2.29. 1-(Methylsulfonyl)-N-(1-phenyl-1H-imidazol-4-yl)-1,2-
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2ac);
244 mg (72%) as a white solid. 1H NMR (300 MHz; CDCl3): d 7.61
(1H, s), 7.58 (1H, s), 7.49–7.31 (6H, m), 7.29–7.21 (1H, m), 7.16
(1H, d, J = 7.2 Hz), 7.07 (1H, t, J = 7.2 Hz), 4.21–4.12 (2H, br d), 3.89
(2H, s), 3.15–3.00 (2H, m), 2.93 (3H, s), 2.02–1.90 (2H, m), 1.84–
1.70 (2H, m); HRMS (ESI+) m/z [M+H]+ 452.1752 (C23H26N5O3S
requires: 452.1756).
5.2.2.22. N-[4-(Furan-2-yl)phenyl]-1-(methylsulfonyl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2v); 49.5
mg (84%). 1H NMR (300 MHz; acetone-d6): d 8.11(1H, s), 7.75–
7.50 (5H, m), 7.45–7.30 (2H, m), 7.13–7.02 (1H, m), 6.73–6.67
(1H, m), 6.54–6.48 (1H, m), 4.35–4.20 (2H, m), 3.99 (2H, s), 3.22–
3.05 (2H, m), 3.00 (3H, s), 2.06–1.70 (4H, m); HRMS (ESI+) m/z
[M+H]+ 452.1648 (C24H26N3O4S requires: 452.1644).
5.2.2.30. 1-(Methylsulfonyl)-N-(quinolin-2-yl)-1,2-dihydro-10H-
spiro[indole-3,40-piperidine]-10-carboxamide (2ad); 288 mg
(97%) as a colorless amorphous. 1H NMR (300 MHz; DMSO-d6):
d 9.63 (1H, s), 8.22 (1H, d, J = 9.0 Hz), 7.99 (1H, d, J = 9.0 Hz), 7.85
(1H, d, J = 7.5 Hz), 7.75 (1H, d, J = 8.6 Hz), 7.64 (1H, m), 7.46–7.18
(4H, m), 7.04 (1H, m), 4.30–4.16 (2H, m), 3.93 (2H, s), 3.14–2.93
(2H, m), 3.05 (3H, s), 1.92–1.60 (4H, m); HRMS (ESI+) m/z [M+H]+
437.1656 (C23H25N4O3S requires: 437.1647).
5.2.2.23. N-[4-(1-Methyl-1H-imidazol-2-yl)phenyl]-1-(methyl-
sulfonyl)-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-car-
boxamide (2w); 143 mg (93%). Compound 2w was treated with
4 N HCl in AcOEt to afford 2w HCl salt: 1H NMR (300 MHz;
DMSO-d6): d 9.07 (1H, s), 7.82–7.67 (6H, m), 7.33–7.20 (3H, m),
7.08–7.03 (1H, m), 4.25–4.18 (2H, m), 3.95 (2H, s), 3.87 (3H, s),
3.07 (1H, s), 3.10–2.99 (2H, m), 1.88–1.70 (4H, m); HRMS (ESI+)
m/z [M+H]+ 466.1901 (C24H28N5O3S requires: 466.1913).
5.2.2.31. 1-(Methylsulfonyl)-N-(quinolin-3-yl)-1,2-dihydro-10H-
spiro[indole-3,40-piperidine]-10-carboxamide (2ae); 130 mg
(49%) as a colorless solid. 1H NMR (300 MHz; DMSO-d6): d 9.02
(1H, s), 8.97 (1H, d, J = 2.3 Hz), 8.44 (2H, d, J = 2.3 Hz), 7.90 (1H,
m), 7.84 (1H, m), 7.61–7.48 (2H, m), 7.38–7.19 (3H, m), 7.05 (1H,
m), 4.30–4.18 (2H, m), 3.95 (2H, s), 3.13–3.00 (2H, m), 3.06 (3H,
s), 1.90–1.68 (4H, m); HRMS (ESI+) m/z [M+H]+ 437.1647
(C23H25N4O3S requires: 437.1647).
5.2.2.24. 1-(Methylsulfonyl)-N-[4-(1,3-thiazol-4-yl)phenyl]-1,2-
dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (2x);
120 mg (58%). 1H NMR (300 MHz; CDCl3):
d 8.86 (1H, d,
J = 2.0 Hz), 7.88 (1H, d, J = 8.6 Hz), 7.47 (2H, d, J = 8.6 Hz), 7.47
(1H, s), 7.41 (1H, d, J = 7.7 Hz), 7.27–7.23 (1H, m), 7.20–7.15 (1H,
m), 7.08 (1H, t, J = 7.4 Hz), 6.60 (1H, br s), 4.12 (2H, d, J = 7.0 Hz),
3.88 (2H, s), 3.13–3.02 (2H, m), 3.07 (3H, s), 2.04–1.90 (2H, m),
1.82–1.75 (2H, m); HRMS (ESI+) m/z [M+H]+ 469.1371
(C23H25N4O3S2 requires: 469.1368).
5.2.2.32. 1-(Methylsulfonyl)-N-(quinolin-6-yl)-1,2-dihydro-10H-
spiro[indole-3,40-piperidine]-10-carboxamide (2af); 60 mg (21%)
as a pale yellow solid. 1H NMR (300 MHz; CDCl3): d 8.89 (1H, d,
J = 4.0 Hz), 8.13–8.00 (3H, m), 7.54 (2H, dd, J = 9.5, 2.4 Hz), 7.40–
7.05 (5H, m), 6.74 (1H, s), 4.18 (2H, br d, J = 11.0 Hz), 3.88 (2H,

5024
T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
s), 3.11 (2H, t, J = 11.0 Hz), 2.94 (3H, s), 1.98 (2H, td, J = 12.0,
5.0 Hz), 1.85–1.80 (2H, m); HRMS (ESI+) m/z [M+H]+ 437.1655
(C23H25N4O3S requires: 437.1647).
5.2.2.41. Phenyl [1-(3-fluorophenyl)-1H-imidazol-4-yl]carba-
mate (5aj); same as 5ai; 1.13 g (66%). 1H NMR (300 MHz; CDCl3):
d 9.60–9.42 (1H, br s), 8.40–8.32 (1H, br s), 7.59 (1H, s), 7.56–7.50
(1H, m), 7.45–7.35 (2H, m), 7.31–7.18 (6H, m).
5.2.2.33. N-(4-Methoxy-1,3-benzothiazol-2-yl)-1-(methylsulfo-
nyl)-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxam-
ide (2ag); 152 mg (48%). 1H NMR (300 MHz, CDCl3): d 8.64 (1H, br
s), 7.41 (1H, d, J = 7.8 Hz), 7.33 (1H, d, J = 7.8 Hz), 7.28–7.15 (4H, m),
7.08 (1H, td, J = 7.3, 1.0 Hz), 6.87 (1H, d, J = 8.3 Hz), 4.28 (2H, d,
J = 10.7 Hz), 3.99 (3H, s), 3.89 (2H, s), 3.10 (2H, t, J = 12.0 Hz),
2.94 (3H, s), 1.94 (2H, td, J = 13.2, 4.4 Hz), 1.81 (2H, d,
J = 14.1 Hz); HRMS (ESI+) m/z [M+H]+ 473.1324 (C22H25N4O4S2
requires: 473.1317).
5.2.2.42. Phenyl [1-(4-fluorophenyl)-1H-imidazol-4-yl]carba-
mate (5ak); same as 5ai; 915 mg (61%). 1H NMR (300 MHz;
CDCl3): d 9.82–9.70 (1H, br s), 7.89 (1H, s), 7.70–7.64 (2H, m),
7.47–7.37 (3H, m), 7.35–7.20 (5H, m).
5.2.2.43. Phenyl [1-(2-methoxyphenyl)-1H-imidazol-4-yl]carba-
mate (5al); same as 5ai; 599 mg (64%). 1H NMR (300 MHz;
CDCl3): d 9.8–9.3 (1H, br s), 7.64 (1H, s), 7.42–7.25 (8H, m), 7.06–
6.96 (2H, m), 3.83 (3H, s).
5.2.2.34. N-(5-Chloro-1,3-benzoxazol-2-yl)-1-(methylsulfonyl)-
1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxamide
(2ah); 167 mg (43%). 1H NMR (300 MHz; CDCl3): d 7.42–7.40 (1H,
m), 7.27–7.20 (2H, m), 7.17–7.13 (3H, m), 7.09–7.06 (1H, m), 4.81–
4.46 (2H, m), 3.90 (2H, s), 2.93 (3H, s) 3.16–2.85 (2H, m) 1.96–1.84
(2H, m), 1.82–1.70 (2H, m); HRMS (ESI+) m/z [M+H]+ 461.1056
(C21H22ClN4O4S requires: 461.1050); Analytical HPLC 99.6% pure.
5.2.2.44. Phenyl [1-(3-methoxyphenyl)-1H-imidazol-4-yl]carba-
mate (5am); same as 5ai; 869 mg (68%). 1H NMR (300 MHz;
CDCl3): d 7.70 (1H, s), 7.50 (1H, s), 7.43–7.31 (4H, m), 7.28–7.20
(4H, m), 7.01–6.95 (3H, m), 3.84 (3H, s).
5.2.2.45. Phenyl [1-(4-methoxyphenyl)-1H-imidazol-4-yl]carba-
mate (5an); same as 5ai; 631 mg (37%). 1H NMR (300 MHz;
CDCl3): d 9.88–9.77(1H, br s), 7.60 (1H, d, J = 1.7 Hz), 7.45–7.20
(8H, s), 6.97 (2H, d, J = 9.0 Hz), 3.84 (3H, s).
5.2.2.35. 1,4-Dinitro-1H-imidazole (8). To a suspension of 1,4-di-
nitro-1H-imidazole 7 (20.0 g, 177 mmol) in acetic acid (360 mL)
was slowly added nitric acid (d 1.5, 86 mL) and acetic anhydride
(240 mL) while cooling in an ice bath (temperature not to exceed
30 °C). The mixture was stirred at room temperature for 1 h, and
then poured onto crushed ice (2 L). AcOEt was added, the organic
layer was washed with aqueous K2CO3 and brine, then dried with
Na2SO4. The solvent was evaporated to give 8 (24.5 g, 88%) as a pale
yellow solid.
5.2.2.46. N-[1-(2-Fluorophenyl)-1H-imidazol-4-yl]-1-(methylsul-
fonyl)-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carbox-
amide (2ai); 181 mg (77%) as a colorless solid. 1H NMR (300 MHz;
CDCl3): d 8.66 (1H, br s), 7.91 (1H, d, J = 1.9 Hz), 7.59 (1H, d,
J = 1.9 Hz), 7.49–7.22 (6H, m), 7.17–7.07 (2H, m), 4.28–4.22 (2H,
m), 3.89 (2H, s), 3.15–3.04 (2H, m), 2.93 (3H, s), 1.97–1.92 (2H,
m), 1.84–1.78 (2H, m); HRMS (ESI+) m/z [M+H]+ 470.1669
(C23H25FN5O3S requires: 470.1662).
5.2.2.36. 1-(2-Fluorophenyl)-4-nitro-1H-imidazole (9ai). To a
suspension of 8 (1.58 g, 10 mmol) in water (30 mL) and methanol
(30 mL) was added 2-fluoroaniline (1.01 mL, 10.5 mmol) and the
mixture was stirred at room temperature for 16 h. The precipitate
was collected by filtration and dried in vacuo to give 9ai (1.91 g,
92%) as a pale yellow solid: 1H NMR (300 MHz; CDCl3): d 8.09
(1H, s), 7.75 (1H, s), 7.58–7.31 (4H, m).
5.2.2.47. N-[1-(3-Fluorophenyl)-1H-imidazol-4-yl]-1-(methyl-
sulfonyl)-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-car-
boxamide (2aj); 199 mg (84%). 1H NMR (300 MHz; CDCl3): d 9.75
(1H, br s), 8.20 (1H, d, J = 1.9 Hz), 7.66 (1H, d, J = 1.9 Hz), 7.51–7.40
(3H, m), 7.31–7.22 (3H, m), 7.17–7.06 (2H, m), 4.35–4.29 (2H, m),
3.89 (2H, s), 3.16–3.05 (2H, m), 2.93 (3H, s), 1.97–1.90 (2H, m),
1.85–1.79 (2H, m); HRMS (ESI+) m/z [M+H]+ 470.1670
(C23H25FN5O3S requires: 470.1662).
5.2.2.37. Phenyl [1-(2-fluorophenyl)-1H-imidazol-4-yl]carba-
mate (5ai). A mixture of 9ai (1.91 g, 9.22 mmol) and palladium
hydroxide (20 wt %, 1.0 g) in tetrahydrofuran (70 mL) and meth-
anol (30 mL) was stirred at rt for 2 h under H2, filtered through
hyflosupercell, then phenyl chlorocarbonate (1.4 mL) was added
to the filtrate. The mixture was stirred at room temperature
for 10 min, and then saturated aqueous NaHCO3 was added.
The mixture was extracted with AcOEt and the organic layer
was washed with brine, dried over Na2SO4, and filtered. The sol-
vent was removed under reduced pressure to give 5ai (1.95 g,
71%) as a white solid: 1H NMR (300 MHz; CDCl3): d 9.45–9.20
(1H, br s), 8.00–7.85 (1H, br s), 7.50–7.35 (5H, m), 7.34–7.18
(5H, m).
5.2.3. Procedure for the synthesis of compound 3a–g
5.2.3.1. Benzyl 1-(ethylsulfonyl)-1,2-dihydro-10H-spiro[indole-
3,40-piperidine]-10-carboxylate (11). To a solution of 10 (40.0 g,
124 mmol) in CHCl3 (400 mL) was added Et3N (34.6 mL, 248 mmol)
and ethanesulfonyl chloride (23.9 g, 186 mmol) at 0 °C. The mix-
ture was stirred at room temperature for 30 min, poured into
water, and extracted with CHCl3. The organic layer was washed
with 1 N HCl aq, saturated aqueous NaHCO3, then brine, and dried
over Na2SO4 Activated carbon was added, then the solution was fil-
tered and concentrated. The crude product was purified by column
chromatography (Wakogel C-200, 700 g, Hexane/EtOAc = 3:1–2:1–
3:2) to give 11 (47.2 g, 92%) as a yellow foam.
5.2.2.38. 1-(3-Fluorophenyl)-4-nitro-1H-imidazole (9aj); same
as 9ai; 1.23 g (94%). 1H NMR (300 MHz; CDCl3): d 8.10 (1H, s), 7.80
(1H, s), 7.62–7.51 (1H, m), 7.30–7.17 (3H, m).
5.2.3.2. 1-(Ethylsulfonyl)-1,2-dihydrospiro[indole-3,40-piperi-
dine] (12). A mixture of 11 (47.2 g, 114 mmol) and palladium
hydroxide (20 wt %, 20.0 g) in THF (75.0 mL) and MeOH
(75.0 mL) was stirred at rt for 17 h under H2, filtered through Cel-
ite, and concentrated. The residue was dissolved in THF (50.0 mL)
and MeOH (100 mL), and palladium hydroxide (20.0 g) was added.
The mixture was stirred at rt for 17 h under H2, filtered through
Celite, and concentrated. To the suspension of the residue in AcOEt
(200 mL) and MeOH (20.0 mL) was added 4 N HCl in AcOEt
(55.0 mL, 220 mmol). The mixture was stirred at room tempera-
5.2.2.39. 1-(4-Fluorophenyl)-4-nitro-1H-imidazole (9ak); same
as 9ai; 1.28 g (98%). 1H NMR (300 MHz; CDCl3): d 8.60 (1H, s), 8.18
(1H, s), 7.88–7.81 (2H, m), 7.47–7.37 (2H, m).
5.2.2.40.
1-(4-Methoxyphenyl)-4-nitro-1H-imidazole
(9al);
same as 9ai; 1.22 g (88%). 1H NMR (300 MHz; CDCl3): d 8.02
(1H, d, J = 1.6 Hz), 7.70 (1H, d, J = 1.6 Hz), 7.36 (2H, d, J = 9.1 Hz),
7.05 (2H, d, J = 9.1 Hz), 3.89 (3H, s).

T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
5025
ture for 1 h. The precipitate was collected and washed with ether
5.2.3.9. 1-(Ethylsulfonyl)-N-[1-(4-methoxyphenyl)-1H-imidazol-
4-yl]-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxam-
ide (3g); 177 mg (68%) as a pale yellow solid. 1H NMR (300 MHz,
DMSO-d6): d 9.56 (1H, s), 9.05 (1H, s), 7.69–7.02 (9H, m), 4.14–4.10
(2H, m), 3.97 (2H, s), 3.82 (3H, s), 3.29 (2H, q, J = 7.5 Hz), 3.12–3.05
(2H, m), 1.79–1.73 (4H, m), 1.24 (3H, t, J = 7.5 Hz); HRMS (ESI+) m/z
[M+H]+ 496.2014 (C25H30N5O4S requires: 496.2019).
to give 12 (35.0 g, 96%) as a pale pink solid: 1H NMR (300 MHz,
DMSO-d6):
d 8.90 (2H, s), 7.29–7.21 (2H, m), 7.17 (1H, d,
J = 7.3 Hz), 7.07 (1H, td, J = 7.3, 1.5 Hz), 3.97 (2H, s), 3.28 (2H, q,
J = 7.3 Hz), 3.05 (2H, t, J = 12.0 Hz), 2.07 (2H, td, J = 13.8, 4.1 Hz),
1.80 (2H, d, J = 14.6 Hz), 1.22 (3H, t, J = 7.6 Hz); MS (ESI+) 281
[M+H]+.
5.2.3.3. 1-(Ethylsulfonyl)-N-(1-phenyl-1H-imidazol-4-yl)-1,2-dihy-
dro-10H-spiro[indole-3,40-piperidine]-10-carboxamide (3a); 18.6 g
(86%) as a white solid. 1H NMR (300 MHz, CDCl3): d 7.61 (1H, t,
J = 1.6 Hz), 7.58 (3H, t, J = 1.6 Hz) 7.47–7.34 (6H, m), 7.27–7.19 (1H,
m), 7.49–7.12 (1H, m), 7.07–7.03 (1H, m), 4.16 (2H, d, J = 14.1 Hz),
3.96 (2H, s), 3.16 (2H, q, J = 7.5 Hz), 3.12–3.01 (2H, m), 1.96–1.89
(2H, m), 1.76–1.70 (2H, m), 1.42 (3H, t, J = 7.5 Hz); HRMS (ESI+) m/z
[M+H]+ 466.1905 (C24H28N5O3S requires: 466.1913); Analytical HPLC
99.3% pure.
Acknowledgment
We thank Mr. Hirokazu Ohsawa for analytical support in
obtaining key analytical data, and Mr. Hidekazu Takahashi for his
helpful suggestions. We are also grateful to the Banyu document
management service for editing the manuscript.
References and notes
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yl]-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxam-
ide (3b); 166 mg (68%). 1H NMR (300 MHz, acetone-d6): d 8.16
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5.2.3.5. 1-(Ethylsulfonyl)-N-[1-(3-fluorophenyl)-1H-imidazol-4-
yl]-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxam-
ide (3c); 162 mg (67%). 1H NMR (300 MHz, DMSO-d6): d 9.08 (1H,
s), 8.14 (1H, d, J = 1.7 Hz), 7.62–7.45 (4H, m), 7.29–7.15 (4H, m),
7.00 (1H, t, J = 7.0 Hz), 4.21–4.16 (2H, m), 3.94 (2H, s), 3.28 (2H,
q, J = 7.4 Hz), 2.98–2.89 (2H, m), 1.98–1.62 (4H, m), 1.23 (3H, t,
J = 7.4 Hz); HRMS (ESI+) m/z [M+H]+ 484.1822 (C24H27FN5O3S re-
quires: 484.1819).
5.2.3.6. 1-(Ethylsulfonyl)-N-[1-(4-fluorophenyl)-1H-imidazol-4-
yl]-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxam-
ide (3d); 216 mg (89%). 1H NMR (300 MHz, CDCl3): d 9.05 (1H, br
s), 8.03 (1H, s), 7.62 (1H, d, J = 1.8 Hz), 7.49–7.43 (2H, m), 7.37 (1H,
dd, J = 7.7, 0.7 Hz), 7.28–7.19 (3H, m), 7.14–7.11 (1H, m), 7.07–7.00
(1H, m), 4.30–4.23 (2H, m), 3.96 (2H, s), 3.16 (2H, q, J = 7.4 Hz),
3.17–3.02 (2H, m), 1.96–1.89 (2H, m), 1.84–1.78 (2H, m), 1.43
(3H, t, J = 7.4 Hz); HRMS (ESI+) m/z [M+H]+ 484.1814
(C24H27FN5O3S requires: 484.1819).
12. Norman, M. H.; Chen, N.; Chen, Z.; Fotsch, C.; Hale, C.; Han, N.; Hurt, R.; Jenkins,
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18. Sato, N.; Takahashi, T.; Shibata, T.; Haga, Y.; Sakuraba, A.; Hirose, M.; Sato, M.;
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19. Takahashi, T.; Sakuraba, A.; Hirohashi, T.; Shibata, T.; Hirose, M.; Haga, Y.;
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Bioorg. Med. Chem. 2006, 14, 7501.
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Kanatani, A.; Fukami, T. J. Med. Chem. 2008, 51, 4765.
5.2.3.7. 1-(Ethylsulfonyl)-N-[1-(2-methoxyphenyl)-1H-imidazol-
4-yl]-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxam-
ide (3e); as 3e HCl salt (258 mg, 81%) as a white solid. 1H NMR
(300 MHz, CDCl3): d 10.40 (1H, s), 8.25 (1H, d, J = 1.8 Hz), 7.58
(1H, d, J = 1.8 Hz), 7.52 (1H, t, J = 7.5 Hz), 7.42–7.35 (2H, m), 7.21
(1H, d, J = 7.5 Hz), 7.17–7.11 (3H, m), 7.03 (1H, t, J = 7.5 Hz),
4.42–4.34 (2H, m), 3.96 (2H, s), 3.91 (3H, s), 3.20–3.03 (4H, m),
2.01–1.89 (2H, m), 1.88–1.79 (2H, m), 1.42 (3H, t, J = 7.5 Hz);
HRMS (ESI+) m/z [M+H]+ 496.2017 (C25H30N5O4S requires:
496.2019).
21. Ogino, Y.; Ohtake, N.; Nagae, Y.; Matsuda, K.; Ishikawa, M.; Moriya, M.;
Kanesaka, M.; Mitobe, Y.; Ito, J.; Kanno, T.; Ishihara, A.; Iwaasa, H.; Ohe, T.;
Kanatani, A.; Fukami, T. Bioorg. Med. Chem. Lett. 2008, 18, 4997.
22. Ogino, Y.; Ohtake, N.; Nagae, Y.; Matsuda, K.; Moriya, M.; Suga, T.; Ishikawa,
M.; Kanesaka, M.; Mitobe, Y.; Ito, J.; Kanno, T.; Ishihara, A.; Iwaasa, H.; Ohe, T.;
Kanatani, A.; Fukami, T. Bioorg. Med. Chem. Lett. 2008, 18, 5010.
23. Sakamoto, T.; Moriya, M.; Haga, Y.; Takahashi, T.; Shibata, T.; Okamoto, O.;
Nonoshita, K.; Kitazawa, H.; Hidaka, M.; Gomori, A.; Iwaasa, H.; Ishihara, A.;
Kanatani, A.; Fukami, T.; Gao, Y.-D.; MacNeil, D. J.; Yang, L. Bioorg. Med. Chem.
Lett. 2009, 19, 1564.
5.2.3.8. 1-(Ethylsulfonyl)-N-[1-(3-methoxyphenyl)-1H-imidazol-
4-yl]-1,2-dihydro-10H-spiro[indole-3,40-piperidine]-10-carboxam-
ide (3f); 248 mg (83%) as a pale yellow solid. 1H NMR (300 MHz,
CDCl3): d 7.60 (1H, s), 7.56 (1H, s), 7.41–7.33 (3H, m), 7.22 (1H, t,
J = 7.5 Hz), 7.14 (1H, d, J = 7.5 Hz), 7.07–6.98 (2H, m), 6.95–6.93
(1H, m), 6.90–6.86 (1H, m), 4.20–4.10 (2H, m), 3.96 (2H, s), 3.85
(3H, s), 3.16 (2H, q, J = 7.5 Hz), 3.13–3.01 (2H, m), 2.00–1.89 (2H,
m), 1.82–1.75 (2H, m), 1.43 (3H, t, J = 7.5 Hz); HRMS (ESI+) m/z
[M+H]+ 496.2012 (C25H30N5O4S requires: 496.2019).
24. See Ref. 8 for the protocol used for the in vivo feeding experiments described
herein. Compounds were evaluated in groups of 13–16 animals which received

5026
injections of 5
T. Sakamoto et al. / Bioorg. Med. Chem. 17 (2009) 5015–5026
g of bPP (10 lL ICV, solved in 10 mM phosphate buffered saline
35. For 4u and 4x: Erlenmeyer, H.; Becker, C.; Sorkin, E.; Bloeh, H.; Suter, E. Helv.
l
containing 0.05% bovine serum albumin), and their food intake was monitored
for 2 h. Oral dosing of compounds (5 mL/kg, suspended in 0.5% methylcellulose
in distilled water) was done 1 h before ICV-agonist dosing.
25. Maligres, P. E.; Houpis, I.; Rossen, K.; Molina, A.; Sager, J.; Upadhyay, V.; Wells,
K. M.; Reamer, R. A.; Lynch, J. E.; Askin’, D.; Volante, R. P.; Reider, P. J.
Tetrahedron 1997, 53, 10983.
26. For 4a: Sato, M.; Aramaki, Y.; Imoto, H.; Aikawa, K.; Oda, T.; Kanzaki, N.; Iizawa,
Y.; Baba, M.; Shiraishi, M. Chem. Pharm. Bull. 2004, 52, 818.
27. For 4b: Miura, Y.; Kurokawa, S.; Nakatsuji, M.; Ando, K.; Teki, Y. J. Org. Chem.
1998, 63, 8295.
Chim. Acta 1947, 30, 2058.
36. For 4v: King, F. D.; Walton, D. R. M. Synthesis 1976, 40.
37. For 4w: Juergen, R. G.; Armin, H.; Rainer, W.; Jacobus, V. M.; Norbert, R.;
Walter, S.; Frank, H. U.S. Patent 6,762,180.
38. For 4y: see Ref 19.
39. For 4z: Pavlik, J. W.; Tongcharoensirikul, P.; Bird, N. P.; Colin Day, A.; Barltrop, J.
A. J. Am. Chem. Soc 1994, 116, 2292.
40. For 4ac: Ewa, S.; Jerzy, S. Pol. J. Chem. 1990, 64, 813.
41. A selective Y5 antagonist in Ref. 42 was used as an internal control across all
assay plates for data validation. The IC50 of this compound is 1.8 0.2 nM.
42. Fukami, T.; Kanatani, A.; Ishihara, A.; Ishii, Y.; Takahashi, T.; Haga, Y.;
Sakamoto, T.; Itoh, T. PCT Int. Appl. WO2001014376.
28. For 4c: Lamothe, M.; Pauwels, P. J.; Belliard, K.; Schambel, P.; Halazy, S. J. Med.
Chem. 1997, 40, 3542.
29. For 4e: Itoh, T.; Mase, T. Tetrahedron Lett. 2005, 46, 3573.
30. For 4f: Maes, B. U. W.; Lemiere, G. L. F.; Dommisse, R.; Augustyns, K.; Haemers,
A. Tetrahedron 2000, 56, 1777.
31. For 4h: Fanta, P. E.; Hedman, E. A. J. Am. Chem. Soc. 1956, 78, 1434.
32. For 4i: Yamamoto, H.; Matsuura, M.; Ikeda, H.; Kubota, M.; Kawamura, M.
EP1582516.
33. For 4s: Sternfeld, F.; Baker, F.; Broughton, H. B.; Guiblin, A. R.; Jelley, R. A.;
Matassa, V. G.; Reeve, A. J.; Beer, M. S.; Stanton, J. A.; Hargreaves, R. J.;
Shepheard, S. L.; Longmore, J.; Razzaque, Z.; Graham, M. I.; Sohal, B.; Street, L. J.
Bioorg. Med. Chem. Lett. 1996, 15, 1825.
34. For 4t: Kitazaki, T.; Ichikawa, T.; Tasaka, A.; Hosono, H.; Matsushita, Y.;
Hayashi, R.; Okonogi, K.; Itoh, K. Chem. Pharm. Bull. 2000, 48, 1935.
43. Rat PKs were determined from administration at 3 mpk iv and at 10 mpk po
dosing in SD rats (n = 2), and PK parameters (F, CLtot, AUC) were calculated by
the trapezoidal method at the following time points; iv: 5 min, 1.0 h, 4.0 h, po:
0.5 h, 1.0 h, 2.0 h.
44. Ishihara, A.; Kanatani, A.; Mashiko, S.; Tanaka, T.; Hidaka, M.; Gomori, A.;
Iwaasa, H.; Murai, N.; Egashira, S.; Murai, T.; Mitobe, Y.; Matsushita, H.;
Okamoto, O.; Sato, N.; Jitsuoka, M.; Fukuroda, T.; Ohe, T.; Guan, X.; MacNeil, D.
J.; Van der Ploeg, L. H.; Nishikibe, M.; Ishii, Y.; Ihara, M.; Fukami, T. Proc. Natl.
Acad. Sci. U.S.A. 2006, 103, 7154.
45. Mashiko, S.; Ishihara, A.; Iwaasa, H.; Sano, H.; Ito, J.; Gomori, A.; Oda, Z.;
Moriya, R.; Matsushita, H.; Jitsuoka, M.; Okamoto, O.; MacNeil, D. J.; Van der
Ploeg, L. H.; Fukami, T.; Kanatani, A. Mol. Pharmacol. 2007, 71, 602.