Melanin-concentrating hormone receptor 1 antagonists: Synthesis, structure-activity relationship, docking studies, and biological evaluation of 2,3,4,5-tetrahydro-1H-3-benzazepine derivatives

Article abstract of DOI:10.1016/j.bmc.2011.09.007

Melanin-concentrating hormone receptor 1 (MCHR1) antagonists have been studied as potential agents for the treatment of obesity. Initial structure-activity relationship studies of in-house hit compound 1a and subsequent optimization studies resulted in th

Full text of DOI:10.1016/j.bmc.2011.09.007

Bioorganic & Medicinal Chemistry 19 (2011) 6261–6273
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Melanin-concentrating hormone receptor 1 antagonists: Synthesis,
structure–activity relationship, docking studies, and biological evaluation
of 2,3,4,5-tetrahydro-1H-3-benzazepine derivatives
⇑
Shizuo Kasai , Masahiro Kamaura, Makoto Kamata, Kazuyoshi Aso, Hitomi Ogino, Yoshihide Nakano,
Kaoru Watanabe, Tomoko Kaisho, Michiko Tawada, Yasutaka Nagisa, Shiro Takekawa, Koki Kato,
Nobuhiro Suzuki, Yuji Ishihara
Pharmaceutical Research Division, Takeda Pharmaceutical Co., Ltd, 26-1 Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 30 July 2011
Revised 5 September 2011
Accepted 6 September 2011
Available online 10 September 2011
Melanin-concentrating hormone receptor 1 (MCHR1) antagonists have been studied as potential agents
for the treatment of obesity. Initial structure–activity relationship studies of in-house hit compound 1a
and subsequent optimization studies resulted in the identification of tetrahydroisoquinoline derivative
23, 1-(2-acetyl-1,2,3,4-tetrahydroisoquinolin-7-yl)-4-[4-(4-chlorophenyl)piperidin-1-yl]butan-1-one, as
a potent hMCHR1 antagonist. A homology model of hMCHR1 suggests that these compounds interact
with Asn294 and Asp123 in the binding site of hMCHR1 to enhance binding affinity. Oral administration
of compound 23 dose-dependently reduced food intake in diet-induced obesity (DIO)-F344 rats.
Ó 2011 Elsevier Ltd. All rights reserved.
Keywords:
MCH
MCHR1 antagonist
Obesity
Homology model
1. Introduction
and MCH receptor 2 (MCHR2, aka SLT).12a–f Interestingly, MCHR2 is
not present in rodents.13
Melanin-concentrating hormone (MCH) is a cyclic peptide hor-
mone first isolated from the chum salmon pituitary and was shown
to regulate melanin pigment aggregation in melanocytes.1 MCH
was subsequently found to be present in mammals,2 and its amino
acid sequence is highly conserved in fish, rats, and humans.3 In the
mammalian brain, MCH is predominantly expressed in the peri-
karya of the lateral hypothalamus and zona incerta, with projec-
tions toward various regions of the brain.4 Recent studies on
MCH have focused on its role in the regulation of feeding behavior
and energy balance, which was confirmed by the following biolog-
ical evidences. (i) Intracerebroventricular (icv) injection of MCH
acutely stimulates feeding behavior in rats.5 (ii) Fasting in geneti-
cally obese ob/ob mice6 and Ay/a (agouti) mice results in the upreg-
ulation of MCH mRNA levels.7 (iii) MCH reverses the action of
MCHR1 is widely expressed in the CNS,14 and its expression, as
well as that of its ligand MCH, was found to be upregulated in
ob/ob mice and by fasting.15 MCHR1 deficient (Mch1rꢀ/ꢀ) mice
are hyperphagic; however, Mch1rꢀ/ꢀ mice are less susceptible to
diet-induced obesity due to their hyperactivity and increased en-
ergy expenditure.16a,b
An MCHR1 peptide antagonist suppressed MCH-induced food
intake in satiated Sprague–Dawley rats. Furthermore, chronic infu-
sion of the peptide antagonist in diet-induced obese (DIO)-mice re-
duced food intake, prevented body weight gain, and reduced body
weight in obese mice.17a,b These findings have made MCHR1 an
attractive pharmaceutical target; small-molecule MCHR1 antago-
nists have been heavily investigated by many pharmaceutical
and biotech companies in an attempt to identify an effective
anti-obesity agent.18a–c
alpha-melanocyte-stimulating hormone (a-MSH), an anorexigenic
melanocortin peptide.8a–c (iv) MCH-knockout mice exhibit reduced
body weight due to hypophagia and an increase in metabolic rate.9
(v) Overexpression of MCH mRNA in mice results in hyperphagia,
mild obesity, and insulin resistance.10
Me
Me
O
N
N
H
MCH was identified as the endogeneous ligand for the orphan
G-protein-coupled receptor (GPCR), MCHR1 (aka SLC-1, GPR24),11a–e
T-226296
hMCHR1 IC50 = 5.5 nM
F
⇑
Corresponding author. Tel.: +81 466 32 1052; fax: +81 466 29 4468.
E-mail address: Kasai_Shizuo@takeda.co.jp (S. Kasai).
Figure 1. Structure of T-226296.
0968-0896/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2011.09.007

6262
S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
We previously reported the tetrahydronaphthalene-based com-
O
Me
c
O
a
N
N
pound T-226296 (Fig. 1) as the first small molecule MCHR1 antag-
onist.19 Further effort has been devoted toward identifying a novel
class of non-peptidic MCHR1 antagonists. High-throughput screen-
ing of our in-house compound library against hMCHR1 resulted in
the identification of benzazepine derivative 1a (Fig. 2) as a new
lead compound with moderate affinity (IC50 = 20 nM) in a recep-
tor-binding assay. To explore the initial SAR of 1a, we designed 4
types of molecules (Types I–IV, Fig. 2), especially to identify the ba-
sic nitrogen that is essential for in vitro activity. Next, the replace-
ment of the phenylpiperidine and 3-benzazepine moieties was
investigated. Herein, we describe the SAR investigation of this ser-
ies of compounds, which led us to identify the potent, orally active
hMCHR1 antagonist 23 with favorable pharmacokinetic properties.
Me
Cl
58%
O
b
5
6
O
O
N
N
R
Me
Me
N
N
O
R'
O
R
4
7a-n
yield
R
2
3
2a 4-Cl
2b 4-F
60%
20%
26%
26%
26%
2c 4-Me
3-Me
2-Me
2d
2e
Scheme 1. Synthesis of benzazepine derivatives 2a–e and 7a–n. Reagents and
conditions: (a) 4-chlorobutyryl chloride, AlCl3, nitroethane; (b) phenylpiperidines,
N,N0-diisopropylethylamine, K2CO3, KI, DMF, 60 °C; (c) HNRR0, N,N0-diisopropyleth-
ylamine, DMF, 60 °C.
2. Chemistry
Benzazepine derivatives 2a–e and 7a–n were synthesized as
shown in Scheme 1. N-Acetylbenzazepine 5 was subjected to the
Friedel–Crafts reaction with 4-chlorobutyryl chloride to generate
a key intermediate, 4-chloro-1-(2,3,4,5-tetrahydro-1H-3-benzaze-
pin-7-yl)butan-1-one 6; subsequent displacement of the chlorine
with phenylpiperidines afforded 2a–e. Compounds 7a–n were syn-
thesized from 6 through parallel synthesis reaction with a variety of
amines under similar conditions to those used for 2a–e. Replace-
ment of the nitrogen substituent on the benzazepine ring is shown
in Scheme 2. The acetyl group of compound 2a was hydrolyzed
using concentrated HCl to yield the amine compound 1b. Reductive
amination of 1b with formaldehyde afforded the N-methyl deriva-
tive 1c. Coupling of 1b with acid chloride, sulfonyl chloride, methyl
chlorocarbamte, and ethyl isocyanate provided amides 2f–j, sulfon-
amides 2k and 2l, carbamate 2m, and urea 2n, respectively.
Replacements of the 3-benzazepine moiety of 2a consisting of
other bicyclic (22–27) or monocyclic (28) templates are depicted
in Scheme 3. The syntheses of these compounds were conducted
according to the reactions shown in Scheme 1. For bicyclic ana-
logues 8, 9, 11, and 12, the Friedel–Crafts reaction was used to
regioselectively furnish desired intermediates 15, 16, 18, and 19,
respectively.
yield
77%
R
Me-
b
c
1c
2f
2g
2h
2i
EtCO-
76%
54%
57%
59%
94%
nPrCO-
cPrCO-
nBuCO-
PhCO-
N R
a
N
2a
O
91%
Cl
2j
1b R=H
d
2k MeSO2-
2l EtSO2-
90%
58%
e
f
MeOCO- 73%
2m
2n
EtNHCO-
94%
Scheme 2. Synthesis of benzazepine derivatives 1c and 2f–n. Reagents and
conditions: (a) concd. HCl, reflux; (b) formaldehyde, formic acid, 100 °C; (c) acid
chloride, Et3N, THF; (d) sulfonyl chloride, Et3N, THF; (e) methyl chlorocarbamate,
Et3N, THF; (f) ethyl isocyanate, Et3N, THF.
The syntheses of benzazepine derivatives 3a, 3b, and 4 are illus-
trated in Scheme 4. N-Trifluoroacetylbenzazepine 29 was subjected
to the Friedel–Crafts reaction with succinic anhydride to afford car-
boxylic acid 30. Compound 30 was coupled with 4-chlorophenylpi-
peridine to yield amide 31, which was treated with aqueous K2CO3
to generate amine 3a. Compound 3a was subjected to reductive ami-
nation withformaldehydeor a reaction with acetyl chloride to afford
N-methyl analogue 3b or N-acetyl analogue 4, respectively.
The alkoxy derivative 37 was synthesized as shown in Scheme
5. Removal of the methyl group from 7-methoxy-2,3,4,5-tetrahy-
dro-1H-3-benzazepine 32 using aqueous HBr followed by Boc-pro-
tection of the nitrogen atom provided the 7-hydroxybenzazepine
derivative 33. Alkylation of the hydroxy group using 1-bromo-3-
chloropropane in the presence of K2CO3 generated the ether 34,
which was sequentially reacted with 4-chlorophenylpiperidine to
afford 35. Deprotection of the Boc group followed by a reaction
with acetyl chloride yielded the desired ether analogue 37.
3. Results and discussion
Compounds synthesized in this study were tested for their
binding affinities to the human MCH receptor 1 (hMCHR1) and
rat MCH receptor 1 (rMCHR1) expressed in Chinese hamster ovary
(CHO) cells using [125I]-MCH(4–19) as a ligand.19 Compounds with
high hMCHR1 affinities were evaluated further for antagonistic
activity in an in vitro functional assay to examine the inhibition
of MCH-stimulated arachidonic acid release from CHO cells
expressing hMCHR1.19
N R2
X
NH
N
N
O
O
R1
X = CH2, R2 = H, Me
X = CH2, R2 = COR, SO2R
X = CO, R2 = H, Me
Type I (1):
Type II (2):
Type III (3):
R1 = H, F, Cl, Me
1a MCHR1 IC50 = 20 nM
Type IV (4): X = CO, R2 = Ac
Figure 2. Structure of HTS hit compound 1a and analogues designed; Types I–IV.

S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
6263
n
n
n
a
N
Me
b
N
Me
N
Me
Cl
N
O
O
O
O
O
8 n=2
9 n=1
15 n=2 62%
16 n=1 68%
22 n=2
36%
36%
Cl
n=1
23
a
b
NH
O
NH
O
NH
O
Me
N
Me
Me
38%
59% Cl
O
O
10
17
Cl
24
m
N
Me
O
m
N
Me
O
m
n
a
b
n
S
N
N
n
Me
S
S
Cl
O
O
O
25 m=0, n=2
26 m=1, n=1
35%
45%
Cl
18
50%
64%
11 m=0, n=2
12 m=1, n=1
m=0, n=2
19 m=1, n=1
a
b
N
Cl
O
80%
51%
O
Cl
13
20
27
H
N
H
N
Me
Me
H
N
a
b
Me
O
O
Cl
N
O
69%
69%
O
O
14
21
28
Cl
Scheme 3. Synthesis of compound 22–28. Reagents and conditions: (a) 4-chlorobutyryl chloride, AlCl3, 1,2-dichloroethane; (b) 4-chlorophenylpiperidine, Et3N, K2CO3, KI,
DMF, 60 °C.
b
O
O
a
O
N
N
CF3
CF3
71%
HO
N
71%
O
29
30
O
c
O
O
N R
CF3
N
e
N
95%
O
O
31
3a
R = H
Cl
Cl
d
3b
4
R = Me
R = Ac
60%
64%
Scheme 4. Syhtnesis of compound 3a, 3b and 4. Reagents and conditions: (a) succinic anhydride, AlCl3, 1,2-dichloroethane; (b) 4-chlorophenylpiperidine hydrochloride,
diethyl phosphorocyanidate, Et3N, DMF; (c) K2CO3, MeOH-H2O; (d) HCHO, HCOOH, 100 °C; (e) acetyl chloride, K2CO3, MeCN.
in vitro activities of the compounds, grouped as Types I–IV and
the ether analogue 37. Addition of a chlorine atom at the 4-position
of the terminal benzene ring in compound 1a resulted in a 20-fold
increase in potency (1b, IC50 = 1.2 nM). Introduction of a methyl
group onto the nitrogen in the benzazepine ring afforded 1c
(IC50 = 0.96 nM), which showed comparable in vitro activity to
1b. Acetylation of the nitrogen atom in the benzazepine ring of
1b resulted in a modest loss of binding affinity (2a, IC50 = 6.6 nM).
Interestingly, 2a showed the most potent antagonistic activity
against hMCHR1 (arachidonic acid release, IC50 = 11 nM). However,
1b and 1c exhibited substantial loss in antagonistic activity
(IC50 = 22 and 34 nM, respectively), although these compounds dis-
played potent binding affinities. Type III compounds 3a and 3b
showed moderate binding affinities (IC50 = 20 and 30 nM, respec-
tively), and a neutral compound 4 (Type IV) resulted in a 10-fold
decrease in potency (IC50 = 190 nM). These results suggest that it
is essential to have at least one basic nitrogen atom to obtain po-
tent binding affinity, and that compounds with a basic nitrogen
a,b
c
NH
N Boc
MeO
Cl
HO
88%
29%
32
33
N R
d
N
O
N Boc
O
41%
35
R = Boc
e
f
Cl
34
36 R = H quant.
93%
37 R = Ac
Scheme 5. Synthesis of compound 37. Reagents and conditions: (a) 48% HBr, 80 °C,
16 h; (b) Boc2O, N,N0-diisopropylethylamine, THF–DMF (2:1), rt to 50 °C; (c) 1-
bromo-3-chloropropane, K2CO3, DMF, 80 °C; (d) 4-chlorophenylpiperidine hydro-
chloride, K2CO3, KI, DMF, 80 °C, 3 h; (e) TFA, rt, 16 h; (f) acetyl chloride, Et3N, THF, rt.
The results of the initial SAR study of lead compound 1a
(IC50 = 20 nM) are shown in Tables 1 and 2. Table 1 depicts the

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S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
Table 1
After establishing 4-chlorophenylpiperidine as a suitable sub-
In vitro activities of 3-benzazepine derivatives
stituent, we replaced the nitrogen substituent on the benzazepine
ring. Table 4 depicts the in vitro activities of amides 2f–j, sulfona-
mides 2k and 2l, carbamate 2m, and urea 2n. All compounds
displayed high hMCHR1 and rMCHR1 binding affinities, except
for the benzoyl-substituted 2j (IC50 = 70 nM). Among these, the
small alkyl amides 2f–h and the small alkyl sulfonamides 2k and
O
N R2
N
X
N
Me
N
O
O
I - IV
37
R1
Compd
Cl
2l exhibited considerably potent antagonistic activities (IC50
=
2.8–9.2 nM), and their IC50 values were comparable to those of
hMCHR1 binding.
Type
R1
R2
X
IC50 (nM)
hMCHR1a
AA releaseb
We replaced the 3-benzazepine core of 2a with other tem-
plates; the corresponding in vitro data are summarized in Table
5. The 2-benzazepine derivative 22 showed a 7-fold decrease in
binding affinity (IC50 = 46 nM) compared with 2a. On the other
hand, the tetrahydroisoquinoline derivative 23 displayed equipo-
tent hMCHR1 affinity (IC50 = 5.6 nM) and antagonistic activity
(IC50 = 6.2 nM) to 2a. Replacement of the 3-benzazepine scaffold
with other 6,5- or 5,6-membered rings (24–26) markedly de-
creased the hMCHR1 affinity (IC50 = 19–280 nM). Replacement of
the N-Ac group with a CH2 group in the benzazepine ring of 2a
yielded 27, which exhibited in decreased binding affinity
(IC50 = 61 nM). Ring-opening of the azepane part in the benzaze-
pine core, phenethylamide 28, also showed attenuated binding
affinity (IC50 = 450 nM). These results suggest that the benzene-
fused 6- or 7-membered ring systems possessing a nitrogen atom
confer high binding affinities. In addition, arranging the amide
moiety on the ring system in an optimal position is required to
obtain an effective interaction with the receptor.
1a
1b
1c
2a
3a
3b
4
I
I
I
II
III
III
IV
–
H
H
H
CH2
CH2
CH2
CH2
CO
CO
CO
–
20
NTc
22
34
Cl
Cl
Cl
Cl
Cl
Cl
–
1.2
0.96
6.6
20
30
190
100
Me
Ac
H
Me
Ac
–
11
NTc
NTc
NTc
NTc
37
a
Binding affinity for hMCHR1.
Antagonistic activity against hMCHR1, inhibition of MCH-stimulated arachi-
donic acid release from CHO cells expressing hMCHR1.
Not tested. IC50 values are calculated with one experiment performed in
duplicate.
b
c
Table 2
Binding affinities of 3-benzazepine derivatives 2b–e
4. Homology model of hMCHR1 and automated docking
O
N
Me
N
Further analysis of the SAR results will be discussed in terms of
a homology docking model we constructed. A homology model of
hMCHR1 was constructed based on the crystal structure of bovine
rhodopsin (PDB code 1F88) as a structural template using MOE
2005.06,20 after truncating a portion of the extracellular region
(residues 179–200). A primary sequence alignment of hMCHR1
and bovine rhodopsin was performed using MOE. Several models
were prepared by probing the possible rotamer states of residues
in the TM ligand binding region, which included Asp123, Tyr272,
Tyr273, and Asn294. hMCHR1 antagonists were docked into
hMCHR1 models using the automated docking program
GOLD.21–23 Reasonable binding modes were selected considering
both the GoldScore and the consistency of the observed SAR. To ac-
count for side chain flexibility, the resulting binding modes were
refined using energy minimization in MOE. Automatic docking
with distance constraints between the ligand atom and the oxygen
atom of the Asp123 carboxyl group was also performed. For this
case, however, reasonable binding modes could not be obtained.
Figure 3 depicts an overall model of the receptor transmem-
brane helical region docked with compound 2a, which is embed-
ded in the region between TM3, 5, 6, and 7. In this mode,
compound 2a sits in a binding pocket located in the upper half of
the helices, inserting its terminal chlorophenyl moiety into the
bottom of the cavity formed by TM5 and 6. Figure 4 shows a
close-up view of the interactions between the compound and
hMCHR1. Asp123 on TM3, which plays a critical role in the binding
of MCH, is located near the center of compound 2a and interacts
with the protonated nitrogen atom. This orientation varies from
that observed in the binding mode of T-226296 analogue: the
amide carbonyl group of T-226296 analogue interacts with
Gln127 instead of Asp123.24 Figure 5 shows the binding interac-
tions of the 3-benzazepine moiety of 2a. This mode shows a de-
O
R1
Compd
R1
IC50 (nM)
hMCHR1a
2b
2c
2d
2e
4-F
86
19
1200
900
4-Me
3-Me
2-Me
a
Refers to Table 1.
atom in the center of the molecule (1b,c = Type I, 2a = Type II) are
favored over those with terminal amines (3a,b = Type III). In addi-
tion, the ether analogue 37 showed a 15-fold loss in binding affin-
ity (IC50 = 100 nM) compared with 2a. These results suggest that
the carbonyl group of 2a may interact with the binding site of
the receptor. On the basis of these results, we selected the acety-
lbenzazepine analogue 2a (Type II) for further optimization
studies.
Table 2 shows the effects of varying substituents on the termi-
nal benzene ring of 2a. Replacement of chlorine at the 4-position
with fluorine (2b, IC50 = 86 nM) or
a methyl group (2c,
IC50 = 19 nM) resulted in 13- and 3-fold decreases in binding affin-
ity, respectively. Furthermore, binding affinities dramatically de-
creased when the methyl group position in 2c was changed from
the benzene 4-position to the 3- or 2-position (2d, IC50 = 1200 nM;
2e, IC50 = 900 nM).
Replacement of the 4-chlorophenylpiperidine group of 2a was
investigated (Table 3). Compounds possessing various amino
groups 7a–n showed lower affinity than the original compound
2a. Only one compound, 4-(4-chlorophenyl)piperidine-4-ol deriva-
tive 7l, showed moderate binding affinity (IC50 = 62 nM), whereas
the other amine analogues exhibited a significant loss in activity.
tailed view of where the amide carbonyl group makes
a
hydrogen bond interaction with the side chain carbamoyl nitrogen
of Asn294 on TM7. The SAR study of replacements for the

S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
6265
Table 3
Binding affinities of 3-benzazepine derivatives 7a–n
O
N
R
Me
N
R'
O
Compd
–NRR0
IC50 (nM)
hMCHR1a
Compd
–NRR0
IC50 (nM)
hMCHR1a
Et
Et
N
N
N
N
7a
7b
>1000
>1000
7h
7i
>1000
Cl
480
N
N
Cl
N
N
O
7c
>1000
7j
>1000
N
N
N
N
N
7d
7e
N Et
>1000
>1000
7k
7l
Cl
Cl
>1000
62
Me
N
OH
N
N
N
7f
>1000
>1000
7m
7n
>1000
>1000
N
N
7g
Me
a
Refers to Table 1.
Table 4
Table 5
In vitro activities of 3-benzazepine derivatives 2f–n
In vitro activities of compounds 22–28
R
N
N R
O
N
O
Cl
Cl
Compd
R
IC50 (nM)
Compd
R
IC50 (nM)
rMCHR1b
hMCHR1a
46
rMCHR1b
AA releasec
NTd
hMCHR1a
AA releasec
2f
EtCO
5.2
4.7
3.9
7.2
70
6.7
4.5
12
8.4
7.5
7.3
11
2.8
7.4
5.4
11
22
86
N
2g
2h
2i
2j
2k
2l
nPrCO
cPrCO
Ac
nBuCO
PhCO
23
24
25
5.6
77
19
11
6.2
N
79
NTd
9.2
5.3
NTd
NTd
Ac
MeSO2
EtSO2
MeOCO
EtNHCO
8.5
6.4
17
NTd
NTd
NTd
NTd
NHAc
Ac
2m
2n
8.1
11
N
N
a
b
c
S
S
Binding affinity for hMCHR1.
Binding affinity for rMCHR1.
Antagonistic activity against hMCHR1, inhibition of MCH-stimulated arachi-
26
27
280
61
NTd
80
NTd
NTd
Ac
donic acid release from CHO cells expressing hMCHR1.
Not tested. IC50 values are calculated with one experiment performed in
duplicate.
d
NHAc
28
450
NTd
NTd
benzazepine moiety (Table 5) supports this model. Replacement of
the 3-benzazepine ring with other bicyclic rings (22, 24–26), dele-
tion of the amide group (27), and ring-opening (28) decreased the
potency because these modifications cannot place the amide car-
bonyl group in the appropriate position to interact with Asn294.
Furthermore, Asn294 can form a hydrogen bond with the proton-
ated basic nitrogen atom in compounds 1b, 1c, 3a, and 3b (Table
1) that possess moderate to potent binding affinities for hMCHR1.
This model also suggests that there is a sufficient space for a
a,b,c,d
Refers to Table 4.
substituent around the nitrogen atom of the 3-benzazepine ring
of compound 2a. This space accommodates relatively large, polar
groups, such as n-butylcarbonyl (2i), methoxycarbonyl (2m), and
ethylaminocarbonyl (2n) groups, but not a bulky benzoyl group
(2j), as shown in Table 4. The 3-benzazepine core interacts with

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S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
lipophilic amino acid residues, i.e., Ile100, Leu103, Met104, and
Ile119, in the binding pocket. The carbonyl group at the 7-position
of the benzazepine ring makes a hydrogen bond with the side
chain oxygen atom of Tyr272 on TM6, which can explain the de-
creased potency of the ether analogue 37 (Table 1). Figure 6 shows
a detailed view of the binding mode for the 4-chlorophenylpiperi-
dine moiety; the chlorophenyl group is situated in a lipophilic
binding pocket comprised of Phe213, Ala216, and Phe217 on
TM5 and Tyr273 on TM6. This model provides a small lipophilic
space around the 4-position of the terminal benzene ring, while
the 2- and 3-positions appear too crowded to allow substituents.
The narrow SAR observed for compounds 2b–e (Table 2) and 7a–
n (Table 3) exemplifies the situation described in this model. The
protonated nitrogen atom of the piperidine group in 2a forms an
ionic interaction and a hydrogen bond with the carboxy group of
Asp123 on TM3; this is consistent with the decreased binding
affinities of the carbonylpiperidine analogue 4 (Table 1) that can-
not interact with Asp123.
5. Pharmacokinetic analysis and pharmacology
The metabolic stabilities of compounds 2a, 2f, 2h, 2l, and 23
were evaluated in hepatic microsomes (Table 6). Tetrahydroiso-
quinoline 23 showed good metabolic stability in human and rat he-
Figure 3. Binding mode of compound 2a (red). The overall view shows that 2a is
positioned between TM3 (green), TM5 (yellow), TM6 (orange), and TM7 (red).
patic microsomes (29 and 18 lL/min/kg at 10 lM, respectively). In
contrast, the benzazepines 2a, 2f, and 2l displayed relatively poor
metabolic stability, and the cyclopropyl amide compound 2h was
considerably unstable metabolically in vitro. Compounds 2a, 2l,
and 23 were orally administered to F344 rats at a dose of 10 mg/
kg, and the concentration of these compounds in the plasma and
brain were measured. The concentrations of 23 in both plasma
and brain were found to be higher than those of 2a. The Cmax value
for 23 in the rat brain was 0.90 0.15
for 2a. Furthermore, the AUC0–24h value for 23 in rat brain was
5.07 g h/g, which was 5-fold higher than that for 2a. The favorable
lg/g, 3-fold higher than that
l
pharmacokinetic profile may be ascribed to the excellent metabolic
stability and BBB permeability of compound 23. On the other hand,
sulfonamide 2l showed poor pharmacokinetic properties and, in
particular, the Cmax and AUC0–24h values for brain were extremely
low (0.06 0.02 lg/g and 0.06 lg h/g, respectively). On the basis
of these results, the tetrahydroisoquinoline derivative 23 was se-
Figure 4. Interactions between compound 2a (carbon atoms in yellow, nitrogen
atoms in blue, oxygen atoms in red, and chlorine atoms in light green) and MCHR1
(carbon atoms in green).
Figure 5. Binding mode of 3-benzazepine of 2a. The acetyl carbonyl group makes a
hydrogen bond with Asn294 on TM7. Asn294 can also interact with the benzaze-
pine nitrogen atom even when the nitrogen is protonated as a basic amine. The
carbonyl group at the 7-position of the benzazepine ring makes a hydrogen bond
with Try272 on TM6.
Figure 6. Binding interaction of 4-chlorophenylpiperidine of 2a. The protonated
nitrogen atom of the piperidine makes an ionic interaction and a hydrogen bond
with Asp123 on TM3. The chlorophenyl moiety is packed tightly within the
lipophilic pocket composed of Phe213 (TM5), Ala216 (TM5), Phe217 (TM5), and
Tyr273 (TM6).

S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
6267
Table 6
Profiles of 2a, 2f, 2h, 2l, and 23
N
N
n
R
O
Cl
Compd
R
n
CL(int.)a
Human
(l
L/min/kg)
Plasmab
Brainb
Tmax (h)
Rat
Cmax
(
lg/mL)
Tmax (h)
AUC0–24h
(l
g h/mL)
Cmax
(
lg/g)
AUC0–24h (lg h/g)
2a
2f
2h
2l
Ac
2
2
2
2
1
66
78
0.26 0.01
NTc
2
1.35
NTc
0.32 0.08
NTc
1
0.97
NTc
EtCO
cPrCO
EtSO2
Ac
121
209
105
29
109
238
107
18
NTc
NTc
1
NTc
NTc
1
NTc
NTc
NTc
NTc
0.11 0.03
0.48 0.06
0.18
3.40
0.06 0.02
0.90 0.15
0.06
5.07
23
2
2
a
b
c
Internal Clearance: In vitro metabolic stability in hepatic microsome at a concentration of 10 lM.
Concentrations were measured using HPLC 1, 2, 4, 8, and 24 h after oral administration of compounds (10 mg/kg, po) in F344 rats. n = 3.
Not tested.
dose-dependently attenuated food intake in DIO-F344 rats after
oral administration (1, 3, 10 mg/kg). These results suggest that
23 represents a new class of orally active non-peptidic hMCHR1
antagonists; however, further optimization is necessary to avoid
hERG-associated liability.
7. Experimental section
Melting points (mp) were determined with a Yanagimoto micro
melting point apparatus or BÜCHI Melting Point B545 and are uncor-
rected. Proton nuclear magnetic resonance (1H NMR) spectra were
recorded on a Varian Gemini 200 or Varian Mercury 300 NMR spec-
trometer. Chemical shifts were reported in d value (ppm) with tetra-
methylsilane as an internal standard. Splitting patterns are designed
as follows: s, singlet; d, doublet; t, triplet; dd, double doublet; q,
qualtet; quint, quintet; sext, sextet; m, multiplet; br, broad. Cou-
pling constants (J) are reported in hertz (Hz). LC/MS (ESI positive)
spectra were recorded on a Waters Micromass ZQ 2000. We carried
out Elemental analysis (C, H, N) to determine purity of test com-
pounds by the Analytical Department of Takeda Pharmaceutical
Co., and the results were within 0.4% of theoretical values. Purity
of compounds (>95%) was established by elemental analysis. The
data of Elemental analysis was attached Supplementary data.
Thin-layer chromatography (TLC) analyses were performed with sil-
ica gel 60F254 plate (Merck Art. 5715) or alumina 60F254 plate
(TypeE). Chromatographic separations were performed with Merck
Silica gel 60 (Merck Art.7734), ICN Alumina B, Akt. I (Activity grade
III) or basic silica gel (ChromatorexNH, 100–200 mesh, Fuji Sylysia
Chemical Ltd) using the indicated eluents. Yields are unoptimized.
Chemical intermediates were characterized by 1H NMR.
Figure 7. Effects of 23 (1, 3, and 10 mg/kg, po) on food intake in DIO-F344 rats.
Cumulative food intake after 5 and 16 h was measured. #: P <0.025 versus 0.5% MC
(Williams test). n = 6.
lected for further evaluation. Oral administration of 23 (1, 3, and
10 mg/kg) dose-dependently and significantly suppressed food in-
take (1.5%, 19.9% and 28.1%, respectively) in DIO-F344 rats (Fig. 7).
Although 23 showed promising anti-obesity profiles, further
development was suspended because 23 (and the related com-
pounds) displayed potent hERG channel inhibitory activity (64.2%
at 1
substantially inhibit the hERG channel at pharmacologically effec-
tive doses in DIO-F344 rats (10 mg/kg, Cmax = 0.48 0.06 g/mL;
1.08 M). Further optimization study addressing hERG activity is
lM, 100.0% at 10 lM) in a patch clamp study. Thus, 23 may
l
l
necessary for development of this analogue.
7.1. 1-(3-Acetyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-
chlorobutan-1-one (6)
6. Conclusion
To a mixture of 5 (20.0 g, 105.7 mmol) and 4-chlorobutyryl
chloride (16.4 g, 116.2 mmol) in nitroethane (200 mL) was added
AlCl3 (31.0 g, 232.5 mmol) and the mixture was stirred at room
temperature for 2 h. The reaction mixture was poured onto crashed
ice and the mixture was partitioned between AcOEt and water. The
AcOEt layer was washed with brine, dried over anhydrous MgSO4,
filtered and concentrated under reduced pressure. The resulting
residue was triturated with diisopropylether to give 6 (17.9 g, 58
%) as a colorless solid. 1H NMR (300 MHz, CDCl3) d: 2.19 (3H, s),
2.20–2.28 (2H, m), 2.93–3.05 (4H, m), 3.16 (2H, t, J = 7.0 Hz),
3.57–3.64 (2H, m), 3.68 (2H, t, J = 6.2 Hz), 3.71–3.79 (2H, m),
7.19–7.25 (1H, m), 7.69–7.81 (2H, m).
We developed a benzazepine derivative 1a as a hit compound,
representing a new class of hMCHR1 antagonists. SAR studies
and subsequent optimization studies led to the identification of a
potent, orally active, non-peptidic hMCHR1 antagonist, tetrahydro-
isoquinoline derivative 23. Homology modeling of these analogues
suggested that some key interactions, particularly those with
Asn294 and Asp123, enhance the binding affinity. Compound 23
exhibited nanomolar hMCHR1 affinity (IC50 = 5.6 nM) and potent
antagonistic activity (IC50 = 6.2 nM). Pharmacokinetic studies re-
vealed that 23 exhibited good pharmacokinetic properties with
high BBB permeability in rats. This compound effectively and

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S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
7.2. 1-(3-Acetyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-[4-
(4-chlorophenyl)piperidin-1-yl]-butan-1-one (2a)
95), 5.50 min (A/B = 5/95), 8.00 min (A/B = 90/10); UV 220 nm)
was performed on a Shimadzu LC-10Av System. The mass spec-
trometer used was Micromass Platform II (Atmospheric Pressure
Chemical ionization: APCI or Electronspray ionization: ESI). Pre-
A mixture of 6 (1.18 g, 4.00 mmol), 4-chlorophenylpiperidine
hydrochloride (1.11 g, 4.80 mmol), diisopropylethylamine (0.62 g,
4.80 mmol), K2CO3 (0.66 g, 4.80 mmol) and KI (0.80 g, 4.80 mmol)
in DMF (15 mL) was stirred at 60 °C for 16 h. The reaction mixture
was partitioned between AcOEt and water. The AcOEt layer was
washed with water, brine, dried over anhydrous MgSO4, filtered
and concentrated under reduced pressure. The resulting residue
was purified by silica gel column chromatography (AcOEt, AcOEt/
MeOH = 20/1) to give 2a (1.08 g, 60%) as a white solid: mp
131–132 °C. 1H NMR (200 MHz, CDCl3) d: 1.54–2.25 (11H, m),
2.37–2.56 (3H, m), 2.90–3.12 (8H, m), 3.53–3.64 (2H, m), 3.66–
3.79 (2H, m), 7.07–7.31 (5H, m), 7.72–7.82 (2H, m). Anal.
(C27H33ClN2O2ꢁ0.2H2O) C, H, N.
parative HPLC purification (YMC Combiprep ODS-A, S-5 lm,
50 mm id ꢂ 20 mm, 25 mL/min; solvent A: 0.1% TFA, solvent B:
0.1% MeCN; gradient cycle: 0.00 min (A/B = 90/10), 1.00 min (A/
B = 90/10), 4.20 min (A/B = 10/90), 5.40 min (A/B = 10/90),
5.50 min (A/B = 90/10), 5.60 min (A/B = 90/10); UV 220 nm) was
performed on a Gilson high-throughput purification System.
7.8. General procedure for the amine derivatives 7a–n
A mixture of 6 (0.05 g, 0.148 mmol), amine (0.150 mmol),
N,N-diisopropylethylamine (30.4 mg, 0.30 mmol) and DMF
(1.0 mL) charged in a test tube was shaken at 60 °C for 12 h. After
this time, the reaction mixture was transferred to a 96-well plate
and the solvent was removed. The resulting residue was parti-
tioned between AcOEt (1.5 mL) and water (1.5 mL). The AcOEt
layer was separated and concentrated. The resulting residue was
dissolved in DMSO (0.5 mL) and the mixture was purified by
preparative HPLC to give the desired compound. Yield (mg) and
LC–MS data of 7a–n were described in Supplementary data.
7.3. 1-(3-Acetyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-[4-
(4-fluorophenyl)piperidin-1-yl]-butan-1-one (2b)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 2b (20%) as a white solid: mp 111–
112 °C. 1H NMR (200 MHz, CDCl3) d: 1.65–1.82 (4H, m), 1.95–2.15
(4H, m), 2.19 (3H, s), 2.48 (3H, t, J = 7.0 Hz), 2.95–3.09 (8H, m), 3.60
(2H, m), 3.73 (2H, m), 6.92–7.01 (2H, m), 7.13–7.28 (3H, m), 7.77
(2H, m). Anal. (C27H33FN2O2) C, H, N.
7.9. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-(2,3,4,5-tetrahydro-
1H-3-benzazepin-7-yl)-butan-1-one dihydrochloride (1b)
7.4. 1-(3-Acetyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-[4-
(4-methylphenyl)piperidin-1-yl]-butan-1-one (2c)
A solution of 2a (9.80 g, 21.6 mmol) in concentrated hydrochlo-
ric acid (150 mL) was refluxed at 120 °C for 24 h. The reaction mix-
ture was basified with 8 M NaOH solution under ice-cooling and
the resulting mixture was partitioned between AcOEt and water.
The extract was washed with water, brine, dried over anhydrous
MgSO4, and filtered. To this filtrate was added 4 M HCl/AcOEt
(13 mL) under ice-cooling. After removal of the solvent under re-
duced pressure, the resulting solid was triturated with isopropa-
nol–diisopropyl ether to give 1b (9.49 g, 91%) as a white powder:
mp 243–247 °C (decomp.). 1H NMR (300 MHz, DMSO-d6) d: 1.99–
2.20 (6H, m), 2.80–3.39 (15H, m), 3.56 (2H, br d), 7.26–7.43 (5H,
m), 7.81–7.85 (2H, m), 9.48 (1H, br s). Anal. (C25H31ClN2Oꢁ2HCl)
C, H, N.
The title compound was prepared by a procedure similar to the
one described for 2a to provide 2c (26%) as a white solid: mp
103–104 °C. 1H NMR (200 MHz, CDCl3) d: 1.77–1.82 (4H, m), 2.01
(2H, m), 2.06 (2H, m), 2.19 (3H, s), 2.32 (3H, s), 2.51 (3H, t,
J = 6.9 Hz), 2.95–3.13 (8H, m), 3.59 (2H, m), 3.73 (2H, m), 7.10–
7.27 (5H, m), 7.78 (2H, m). Anal. (C28H36N2O2) C, H, N.
7.5. 1-(3-Acetyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-[4-
(3-methylphenyl)piperidin-1-yl]-butan-1-one (2d)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 2d (26%) as a solid: mp 82–83 °C.
1H NMR (200 MHz, CDCl3) d: 1.67–1.81 (4H, m), 1.96–2.09 (3H,
m), 2.19 (3H, s), 2.32 (3H, s), 2.45 (3H, t, J = 7.2 Hz), 2.88–3.00
(9H, m), 3.58–3.74 (4H, m), 7.00 (3H, m), 7.16–7.27 (2H, m), 7.78
(2H, m). Anal. (C28H36N2O2) C, H, N.
7.10. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-(3-methyl-2,3,4,5-
tetrahydro-1H-3-benzazepin-7-yl)-butan-1-one (1c)
A mixture of 1b (0.30 g, 0.73 mmol), formaldehyde (0.09 mL,
1.09 mmol) and formic acid (0.9 mL) was stirred at 100 °C for 4 h.
The reaction mixture was poured into water (20 mL) and the mix-
ture was basified with 8 M NaOH solution. The mixture was ex-
tracted with AcOEt (20 mL ꢂ 2) and the extract was washed with
water and brine, dried over MgSO4. After removal of the solvent
under reduced pressure, the resulting residue was chromato-
graphed on NH-silica gel (hexane/AcOEt = 1/1) to give 1c (free
amine, 0.24 g, 77%) as a colorless solid. This was treated with
4 M HCl (AcOEt solution) to give a white solid: mp 248–252 °C (de-
comp.). 1H NMR (200 MHz, CDCl3, free amine) d: 1.62–2.20 (8H, m),
2.36–2.67 (10H, m), 2.93–3.15 (8H, m), 7.07–7.30 (5H, m), 7.70–
7.80 (2H, m). Anal. (C26H33ClN2Oꢁ2HClꢁ0.5H2O) C, H, N.
7.6. 1-(3-Acetyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-[4-
(2-methylphenyl)piperidin-1-yl]-butan-1-one (2e)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 2e (26%) as a solid: mp 82–83 °C.
1H NMR (200 MHz, CDCl3) d: 1.73–1.75 (4H, m), 1.97–2.15 (3H,
m), 2.20 (3H, s), 2.33 (3H, s), 2.51 (3H, t, J = 7.2 Hz), 2.70–2.73
(2H, m), 2.95–3.10 (7H, m), 3.61 (2H, m), 3.74 (2H, m), 7.09–7.27
(5H, m), 7.79 (2H, m). Anal. (C28H36N2O2) C, H, N.
7.7. Combinatorial chemistry
7.11. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-(3-propionyl-
Parallel reactions were carried out in disposal polypropylene
test tube with cap (SARSTEDT AG&Co., 101 ꢂ 16.5 mm) using a
shaker. Liquid handling platform (Genesis, TECAN AG) was used
for sampling of the reaction mixture. Liquid Analytical HPLC anal-
2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-butan-1-one (2f)
To a mixture of 1b (0.30 g, 0.62 mmol) and triethylamine
(0.28 mL, 2.05 mmol) in THF (8 mL) was added a solution of propi-
onyl chloride (0.060 g, 0.68 mmol) in THF (2.0 mL) under ice-cool-
ing. After being stirred at room temperature for 1 h, the reaction
mixture was poured into 5% NaHCO3 (40 mL) and the mixture
ysis (CAPCELL PAK UG120 C18 Column; 2.0 mm id ꢂ 50 mm, 3
lm
particle size, 0.5 mL/min; solvent A: 0.1% TFA, solvent B: 0.1%
MeCN; gradient cycle: 0.00 min (A/B = 90/10), 4.00 min (A/B = 5/

S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
6269
was extracted with AcOEt (20 mL ꢂ 2). The extract was washed
with water (20 mL) and brine (20 mL), dried over MgSO4. After re-
moval of the solvent under reduced pressure, the resulting pale
yellow solid was triturated with Et2O/diisopropyl ether solution
to yield 2f (0.22 g, 76%) as a colorless powder: mp 110–112 °C.
1H NMR (300 MHz, CDCl3) d: 1.19 (3H, t, J = 7.5 Hz), 1.62–1.80
(4H, m), 1.95–2.08 (4H, m), 2.41–2.48 (5H, m), 2.97–3.04 (8H,
m), 3.59–3.61 (2H, m), 3.73–3.76 (2H, m), 7.12 (2H, d, J = 8.1 Hz),
7.20–7.26 (3H, m), 7.56–7.78 (2H, m). Anal. (C28H35Cl N2O2) C, H, N.
m), 3.43––3.47 (4H, m), 7.12 (2H, d, J = 8.4 Hz), 7.22–7.26 (3H, m),
7.77–7.81 (2H, m). Anal. (C26H33ClN2O3Sꢁ0.5H2O) C, H, N.
7.17. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-[3-(ethylsulfonyl)-
2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl]butan-1-one (2l)
The title compound was prepared by a procedure similar to
the one described for 2k to provide 2l (58%) as a colorless solid:
mp 138–139 °C. 1H NMR (300 MHz, CDCl3) d: 1.33 (3H, t,
J = 7.4 Hz), 1.59–1.74 (4H, m), 1.94–2.09 (4H, m), 2.44 (3H, t like),
2.92–3.11 (10H, m), 3.46–3.50 (4H, m), 7.11 (2H, d, J = 8.8 Hz),
7.21–7.27 (3H, m), 7.76–7.80 (2H, m). Anal. (C27H35ClN2O3S) C,
H, N.
7.12. 1-(3-Butyryl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-
[4-(4-chlorophenyl)piperidin-1-yl]-butan-1-one (2g)
The title compound was prepared by a procedure similar to
the one described for 2f to provide 2g (54%) as a colorless pow-
der: mp 93–94 °C. 1H NMR (300 MHz, CDCl3) d: 0.99 (3H, t,
J = 7.5 Hz), 1.62–1.80 (6H, m), 1.95–2.07 (4H, m), 2.37–2.46 (5H,
m), 2.95–3.04 (8H, m), 3.60–3.61 (2H, m), 3.73–3.75 (2H, m),
7.12 (2H, d, J = 8.1 Hz), 7.20–7.26 (3H, m), 7.76–7.78 (2H, m).
Anal. (C29H37Cl N2O2) C, H, N.
7.18. Methyl-7-{4-[4-(4-chlorophenyl)piperidin-1-yl]butanoyl}-
1,2,4,5-tetrahydro-3H-3-benzazepine-3-carboxylate (2m)
A mixture of 1b (0.20 g, 0.41 mmol) in AcOEt (20 mL) was
washed with 2 M NaOH (20 mL) and brine (20 mL), dried over
anhydrous MgSO4. After removal of the solvent under reduced
pressure, the resulting residue was dissolved in THF (10 mL). To
this solution was added triethylamine (0.070 mL, 0.50 mmol) and
methyl chlorocarbonate (0.050 g, 0.50 mmol) successively. After
being stirred at room temperature for 16 h, the reaction mixture
was poured into water (40 mL) and the mixture was extracted with
AcOEt (20 mL ꢂ 2). The extract was washed with brine and dried
over anhydrous MgSO4. After removal of the solvent under reduced
pressure, the resulting residue was purified by alumina column
chromatography (hexane/AcOEt = 1/1) to give 2m (0.14 g, 73%) as
a colorless oil. This oil was treated with 4 M HCl (AcOEt solution)
to give a colorless solid: mp 61 °C. 1H NMR (300 MHz, CDCl3, free
amine) d: 1.66–1.80 (4H, m), 1.95–2.07 (6H, m), 2.34 (2H, t,
J = 7.2 Hz), 2.96–3.04 (7H, m), 3.61 (4H, br s), 3.75 (3H, s), 7.11
(2H, d, J = 8.7 Hz), 7.20–7.27 (3H, m), 7.75–7.77 (2H, m). Anal.
(C27H33Cl N2O3ꢁHCl) C, H, N.
7.13. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-[3-(cyclopropylcar
bonyl)-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl]butan-1-one
(2h)
The title compound was prepared by a procedure similar to the
one described for 2f to provide 2h (57%) as a white solid: mp 122–
124 °C. 1H NMR (300 MHz, CDCl3) d: 0.77–0.84 (2H, m), 1.00–1.04
(2H, m), 1.62–1.86 (4H, m), 1.93–2.07 (6H, m), 2.42–2.47 (1H, m),
2.44 (2H, t, J = 7.2 Hz), 2.97–3.04 (7H, m), 3.75–3.81 (4H, m), 7.12
(2H, d, J = 8.4 Hz), 7.23–7.26 (3H, m), 7.76–7.78 (2H, m). Anal.
(C29H35Cl N2O2) C, H, N.
7.14. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-(3-pentanoyl-
2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-butan-1-one (2i)
The title compound was prepared by a procedure similar to the
one described for 2f to provide 2i (59%) as a pale red solid: mp
88 °C (decomp.). 1H NMR (300 MHz, CDCl3) d: 0.94 (3H, t,
J = 7.5 Hz), 1.39 (2H, sext, J = 7.5 Hz), 1.60–1.80 (6H, m), 1.95–
2.08 (4H, m), 2.39–2.46 (5H, m), 2.95–3.04 (8H, m), 3.60–3.61
(2H, m), 3.72–3.75 (2H, m), 7.12 (2H, d, J = 8.1 Hz), 7.20–7.26
(3H, m), 7.76–7.79 (2H, m). Anal. (C30H39Cl N2O2) C, H, N.
7.19. 7-{4-[4-(4-Chlorophenyl)piperidin-1-yl]butanoyl}-N-eth
yl-1,2,4,5-tetrahydro-3H-3-benzazepine-3-carboxamide (2n)
The title compound was prepared by a procedure similar to the
one described for 2f to provide 2n (94%) as a colorless solid. This
solid was triturated with diisopropyl ether to give a colorless pow-
der: mp 146–148 °C. 1H NMR (200 MHz, CDCl3) d: 1.17 (3H, t,
J = 7.4 Hz), 1.76 (4H, br m), 1.99–2.02 (4H, br m), 2.44–2.47 (2H,
m), 3.00–3.03 (9H, m), 3.32 (2H, m), 3.55 (4H, m), 4.47 (1H, m),
7.12 (2H, d, J = 8.4 Hz), 7.19–7.26 (3H, m), 7.74–7.77 (2H, m). Anal.
(C28H36 Cl N3O2ꢁ0.3H2O) C, H, N.
7.15. 1-(3-Benzoyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-
[4-(4-chlorophenyl)piperidin-1-yl]-butan-1-one (2j)
The title compound was prepared by a procedure similar to the
one described for 2f to provide 2j (94%) as a colorless powder: mp
103–105 °C. 1H NMR (200 MHz, CDCl3) d: 1.65–1.80 (6H, m), 1.93–
2.08 (6H, m), 2.44 (2H, t like), 2.95–3.11 (5H, m), 3.52 (2H, br m),
3.89 (2H, br s), 7.09–7.46 (10H, m), 7.77–7.80 (2H, m). Anal.
(C30H35Cl N2O2) C, H, N.
7.20. 1-(2-Acetyl-2,3,4,5-tetrahydro-1H-2-benzazepin-8-yl)-4-
chlorobutan-1-one (15)
The title compound was prepared by a procedure similar to the
one described for 6 to provide 15 (62%) as a colorless solid. 1H NMR
(200 MHz, CDCl3) d: 1.76–1.90 (2H, m), 2.05 and 2.12 (3H, s), 2.14–
2.27 (2H, m), 2.94–3.06 (2H, m), 3.00–3.17 (2H, m), 3.63–3.77 (2H,
m), 3.70–3.86 (2H, br m), 4.56 and 4.61 (2H, s), 7.13–7.39 (2H, m),
7.77–7.97 (1H, m).
7.16. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-[3-(methylsulfo
nyl)-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl]butan-1-one (2k)
A mixture of 1b (0.15 g, 0.34 mmol), methanesulfonyl chloride
(0.05 g, 0.41 mmol) and triethylamine (0.16 mL, 1.12 mmol) in
THF (10 mL) was stirred at room temperature for 2 h. The reaction
mixture was poured into 5% NaHCO3 (50 mL) and the mixture was
extracted with AcOEt (30 mL ꢂ 2). The extract was washed with
water and brine, dried over MgSO4. After removal of the solvent un-
der reduced pressure, 2k (0.15 g, 90%) was obtained as a pale yellow
solid: mp 156–158 °C. 1H NMR (200 MHz, CDCl3) d: 1.64–1.75 (4H,
m), 1.95–2.14 (4H, m), 2.47 (2H, t like), 2.79 (3H, s), 2.97–3.13 (9H,
7.21. 1-(2-Acetyl-1,2,3,4-tetrahydroisoquinolin-7-yl)-4-
chlorobutan-1-one (16)
The title compound was prepared by a procedure similar to the
one described for 6 to provide 16 (68%) as colorless crystals. 1H
NMR (300 MHz, CDCl3) d: 2.19 (3H, s), 2.25 (2H, m), 2.95 (2H, m),
3.17 (2H, quint, J = 6.9 Hz), 3.68 (3H, m), 3.85 (1H, t, J = 6.3 Hz),
4.71 (2H, s), 7.25 (1H, m), 7.78 (2H, m).

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S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
7.22. 1-(2-Acetyl-2,3,4,5-tetrahydro-1H-2-benzazepin-8-yl)-4-
[4-(4-chlorophenyl)piperidin-1-yl]butan-1-one hydrochloride
(22)
7.28. 1-(5-Acetyl-4,5,6,7-tetrahydrothieno[3,2-c]pyridin-2-yl)-
4-[4-(4-chlorophenyl)piperidin-1-yl]-butan-1-one (25)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 25 (35%) as a pale brown solid: mp
116–118 °C. 1H NMR (200 MHz, CDCl3) d: 1.61–1.73 (4H, m), 1.92–
2.09 (4H, m), 2.17 and 2.20 (3H, s), 2.39–2.46 (1H, m), 2.42 (2H, t,
J = 7.0 Hz), 2.88 (2H, t, J = 7.0 Hz), 2.88–3.03 (4H, m), 3.75 and
3.91 (2H, t, J = 5.8 Hz), 4.54 and 4.67 (2H, s), 7.12 (2H, d,
J = 8.4 Hz), 7.25 (2H, d, J = 8.4 Hz), 7.43 and 7.44 (1H, s). Anal.
(C24H29ClN2O2S) C, H, N.
The title compound was prepared by a procedure similar to the
one described for 2a to provide 22 (free amine, 36%) as a light
brown oil. This oil was treated with 4 M HCl (AcOEt solution)
and the resulting precipitate was triturated with Et2O/AcOEt solu-
tion to give 22 as a colorless powder: mp 153–155 °C (decomp.). 1H
NMR (300 MHz, DMSO-d6) d: 1.50–1.83 (2H, m), 1.87–2.23 (9H, m),
2.78–3.26 (9H, m), 3.58 (2H, d, J = 12.1 Hz), 3.66–3.86 (2H, m),
4.47–4.74 (2H, m), 7.17–7.51 (5H, m), 7.67–8.03 (2H, m), 10.6–
10.7 (1H, br m). Anal. (C27H33Cl N2O2ꢁHClꢁ1.0H2O) C, H, N.
7.29. 1-(6-Acetyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridin-2-yl)-
4-[4-(4-chlorophenyl)piperidin-1-yl]-butan-1-one (26)
7.23. 1-(2-Acetyl-1,2,3,4-tetrahydroisoquinolin-7-yl)-4-[4-(4-
chlorophenyl)piperidin-1-yl]butan-1-one hydrochloride (23)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 26 (45%) as a pale yellow solid: mp
137–138 °C. 1H NMR (300 MHz, CDCl3) d: 1.62–1.80 (4H, m), 1.89–
2.09 (4H, m), 2.17 and 2.20 (3H, s), 2.38–2.45 (3H, m), 2.74–3.02
(6H, m), 3.71 and 3.87 (2H, t, J = 5.4 Hz), 4.68 and 4.83 (2H, s),
7.12 (2H, d, J = 8.6 Hz), 7.25 (2H, d, J = 8.6 Hz), 7.45 (1H, s). Anal.
(C24H29ClN2O2S) C, H, N.
The title compound was prepared by a procedure similar to the
one described for 2a to provide 23 (free amine, 36%) as a colorless
crystalline solid. This solid was treated with hydrochloric acid
(EtOH solution) to afford 23 as a colorless powder: mp 204–
206 °C. 1H NMR (300 MHz, DMSO-d6) d: 1.78–2.28 (9H, m), 2.71–
3.28 (9H, m), 3.49–3.62 (2H, m), 3.62–3.75 (2H, m), 4.53–4.84
(2H, m), 7.13–7.51 (5H, m), 7.63–7.96 (2H, m), 10.7 (1H, br s). Anal.
(C26H31ClN2O2ꢁHClꢁ0.3H2O) C, H, N.
7.30. 4-Chloro-1-(6,7,8,9-tetrahydro-5H-benzo[7]annulen-2-
yl)butan-1-one (20)
7.24. N-[5-(4-Chlorobutanoyl)-2,3-dihydro-1H-inden-2-yl]aceta
mide (17)
The title compound was prepared by a procedure similar to the
one described for 6 to provide 20 (80%) as a brown oil. 1H NMR
(200 MHz, CDCl3) d: 1.58–1.70 (4H, m), 1.80–1.86 (2H, m), 2.22
(2H, m), 2.82–2.89 (4H, m), 3.15 (2H, t, J = 7.0 Hz), 3.67 (2H, t,
J = 6.2 Hz), 7.18 (1H, d like), 7.68–7.72 (2H, m).
The title compound was prepared by a procedure similar to the
one described for 6 to provide 17 (59%) as colorless crystals. 1H
NMR (200 MHz, CDCl3) d: 1.97 (3H, s), 2.22 (2H, quint., J = 6.0 Hz),
2.86 (2H, dd, J = 16.2 Hz, 4.2 Hz), 3.16 (2H, t, J = 6.9 Hz), 3.34 (2H,
dd, J = 16.5 Hz, 7.2 Hz), 3.68 (2H, t, J = 6.0 Hz), 4.78 (1H, m), 5.81
(1H, m), 7.32 (1H, d, J = 7.8 Hz), 7.84 (2H, m).
7.31. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-(6,7,8,9-tetrahyd
ro-5H-benzo[7]annulen-2-yl)-butan-1-one hydrochloride (27)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 27(free amine, 51%) as a pale yel-
low oil. This was treated with 4 M hydrochloric acid (AcOEt solu-
tion) and the resulting precipitate was triturated with
diisopropyl ether to give 27 as a colorless powder: mp 256–
257 °C. 1H NMR (200 MHz, CDCl3, free amine) d: 1.61–2.10 (10H,
m), 2.39–2.47 (4H, m), 2.81–3.11 (11H, m), 7.09–7.28 (5H, m),
7.69–7.73 (2H, m). Anal. (C26H32ClNOꢁHCl) C, H, N.
7.25. N-(5-{4-[4-(4-Chlorophenyl)piperidin-1-yl]butanoyl}-2,3-
dihydro-1H-inden-2-yl)-acetamide (24)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 24 (38%) as colorless crystals: mp
133–134 °C. 1H NMR (200 MHz, CDCl3) d: 1.61–1.82 (4H, m), 1.94
(3H, s), 1.98–2.14 (3H, m), 2.51 (4H, m), 2.90 (2H, dd, J = 16.4,
4.8 Hz), 2.99 (4H, m), 3.34 (2H, dd, J = 16.8, 7.4 Hz), 4.78 (1H, m),
5.87 (1H, m), 7.10–7.32 (5H, m), 7.84 (2H, m). Anal. (C26H31ClN2O2)
C, H, N.
7.32. N-{2-[4-(4-Chlorobutanoyl)phenyl]ethyl}acetamide (21)
The title compound was prepared by a procedure similar to the
one described for 6 to provide 21 (69%) as a pale yellow powder. 1H
NMR (300 MHz, CDCl3) d: 1.95 (3H, s), 2.23 (2H, quint. J = 6.5 Hz),
2.89 (2H, t, J = 6.5 Hz), 3.16 (2H, t, J = 6.9 Hz), 3.53 (2H, q,
J = 6.9 Hz), 3.68 (2H, t, J = 6.5 Hz), 5.44 (1H, br s), 7.29 (2H, d,
J = 8.1 Hz), 7.92 (2H, d, J = 8.1 Hz).
7.26. 1-(5-Acetyl-4,5,6,7-tetrahydrothieno[3,2-c]pyridin-2-yl)-
4-chlorobutan-1-one (18)
The title compound was prepared by a procedure similar to the
one described for 6 to provide 18 (50%) as a pale brown powder. 1H
NMR (200 MHz, CDCl3) d: 2.14–2.28 (5H, m), 2.88–2.99 (2H, m),
3.06 (2H, t, J = 7.0 Hz), 3.67 (2H, t, J = 6.2 Hz), 3.76 (1H, t,
J = 5.7 Hz), 3.92 (1H, t, J = 5.7 Hz), 4.56 and 4.68 (2H, s), 7.46 (1H, s).
7.33. N-[2-(4-{4-[4-(4-Chlorophenyl)piperidin-1-yl]butanoyl}
phenyl)ethyl]acetamide (28)
7.27. 1-(6-Acetyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridin-2-yl)-
4-chlorobutan-1-one (19)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 28 (69%) as a colorless powder: mp
158 –160 °C. 1H NMR (200 MHz, CDCl3) d: 1.60–1.75 (4H, m), 1.94
(3H, s), 1.94–2.04 (4H, m), 2.40–2.48 (3H, m), 2.85–3.03 (6H, m),
3.54 (2H, q like), 5.43 (1H, br s), 7.11 (2H, d, J = 13.2 Hz), 7.23–
7.31 (4H, m), 7.94 (2H, d, J = 12.0 Hz). Anal. (C25H31ClN2O2ꢁ1.5
H2O) C, H, N.
The title compound was prepared by a procedure similar to the
one described for 6 to provide 19 (64%) as a pale yellow solid. 1H
NMR (300 MHz, CDCl3) d: 2.15–2.31 (2H, m), 2.19 and 2.21 (3H,
s), 2.75–2.83 (2H, m), 3.02–3.11 (2H, m), 3.65 (2H, t, J = 6.2 Hz),
3.72 and 3.88 (2H, t, J = 6.2 Hz), 4.70 and 4.84 (2H, s), 7.46 (1H, s).

S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
6271
7.34. 4-Oxo-4-[3-(trifluoroacetyl)-2,3,4,5-tetrahydro-1H-3-
benzazepin-7-yl]butanoic acid (30)
(37 mg, 0.47 mmol) and the mixture was stirred at room tempera-
ture for 16 h. The reaction mixture was partitioned between AcOEt
and water, and the AcOEt layer was washed with brine, dried over
anhydrous MgSO4, filtered and concentrated under reduced pres-
sure to afford 4 (0.14 g, 64%) as a colorless solid: mp 109–112 °C.
1H NMR (200 MHz, CDCl3) d: 1.64 (2H, m), 1.89 (2H, m), 2.58
(4H, m), 2.66 (3H, s), 2.87 (2H, t, J = 6.6 Hz), 3.11 (4H, m), 3.17
(1H, m), 3.34 (2H, t, J = 6.6 Hz), 3.58–3.76 (4H, m), 4.13 (1H, d,
J = 15.6 Hz), 4.73 (1H, d, J = 12 Hz), 7.11–7.31 (5H, m), 7.81 (2H,
m). Anal. (C27H31ClN2O3) C, H, N.
To a mixture of 29 (10.0 g, 41.0 mmol) and succinic anhydride
(4.1 g, 41.0 mmol) in 1,2-dichloroethane (40 mL) was added AlCl3
(27.0 g, 205 mmol) at room temperature. After being stirred at
45 °C for 1 h, the reaction mixture was poured onto ice and the
resulting mixture was partitioned between AcOEt and water. The
AcOEt layer was washed with brine, dried over anhydrous MgSO4,
filtered and concentrated under reduced pressure. The resulting
residue was purified by silica gel column chromatography (hex-
ane/AcOEt = 1/1) to give 30 (10.0 g, 71%) as a yellow solid. 1H
NMR (200 MHz, CDCl3) d: 2.81 (2H, t, J = 6.4 Hz), 2.90–3.15 (4H,
m), 3.29 (2H, t, J = 6.4 Hz), 3.65–3.85 (4H, m), 7.20–7.33 (1H, m),
7.75–7.85 (2H, m), 10.0 (1H, br s).
7.39. tert-Butyl 7-hydroxy-1,2,4,5-tetrahydro-3H-3-benzazepine
-3-carboxylate (33)
A mixture of 32 (1.76 g, 9.92 mmol) and HBr (48% solution,
20 mL) was stirred at 80 °C for 16 h. After this time, the reaction
mixture was cooled to room temperature and concentrated under
reduced pressure. The resulting residue was dissolved in THF/DMF
(2/1, 300 mL). To this solution was added N,N-diisopropylethyl-
amine (2.82 g, 21.82 mmol) and di-tert-butyl dicarbonate (2.17 g,
9.92 mmol). The mixture was stirred at room temperature for
16 h, and then heated at 50 °C for 2 h. The reaction mixture was
concentrated under reduced pressure and the resulting residue
was purified by alumina column chromatography (hexane/
AcOEt = 1/1) to give 33 (0.75 g, 29%) as a light brown amorphous
powder. 1H NMR (300 MHz, CDCl3) d: 1.48 (9H, s), 2.80–2.84 (4H,
m), 3.53 (4H, dd like), 4.77 (1H, s), 6.56–6.61 (2H, m), 6.97 (1H,
d, J = 7.8 Hz).
7.35. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-4-oxo-1-[3-(trifluoro
acetyl)-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl]butan-1-one
(31)
A mixture of 30 (7.50 g, 21.8 mmol), 4-chlorophenylpiperidine
hydrochloride (5.00 g, 21.8 mmol), and triethylamine (4.41 g,
43.6 mmol) in DMF (30 mL) was stirred at room temperature for
30 min, then cooled to 0 °C. To this mixture was added diethyl
phosphorocyanidate (3.56 g, 21.8 mmol) and the mixture was stir-
red at 0 °C for 1 h. The reaction mixture was partitioned between
AcOEt and water, and the AcOEt layer was washed with water,
brine, dried over anhydrous MgSO4, filtered, and concentrated un-
der reduced pressure. The resulting residue was purified by silica
gel column chromatography (hexane/AcOEt = 1/1) to give 31
(8.10 g, 71%) as a colorless solid. 1H NMR (200 MHz, CDCl3) d:
1.45–2.00 (4H, m), 2.55–2.90 (4H, m), 2.97–3.28 (5H, m), 3.34
(2H, t, J = 6.4 Hz), 3.64–3.84 (4H, m), 4.04–4.21 (1H, m), 4.68–
4.84 (1H, m), 7.14 (2H, d, J = 8.4 Hz), 7.20–7.34 (3H, m), 7.80–
7.90 (2H, m).
7.40. tert-Butyl 7-(3-chloropropoxy)-1,2,4,5-tetrahydro-3H-3-
benzazepine-3-carboxylate (34)
A mixture of 33 (0.70 g, 2.66 mmol), 1-bromo-3-chloropropane
(0.50 g, 3.19 mmol), and K2CO3 (1.10 g, 7.98 mmol) in DMF (20 mL)
was stirred at 80 °C for 3 h. After this time, the reaction mixture
was cooled to room temperature and partitioned between AcOEt
and water. The AcOEt layer was washed with water, brine, dried
over anhydrous MgSO4, filtered and concentrated under reduced
pressure. The resulting residue was purified by alumina column
chromatography (hexane/AcOEt = 3/2) to give 34 (0.80 g, 88%) as
a light yellow oil. 1H NMR (300 MHz, CDCl3) d: 1.49 (9H, s), 2.16–
2.33 (2H, m), 2.83–2.85 (4H, m), 3.52–3.71 (4H, m), 4.05–4.18
(4H, m), 6.63–6.69 (2H, m), 7.00–7.26 (1H, m).
7.36. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-4-oxo-1-(2,3,4,5-
tetrahydro-1H-3-benzazepin-7-yl)butan-1-one (3a)
A
mixture of 31 (8.00 g, 15.4 mmol) and K2CO3 (6.40 g,
46.0 mmol) in MeOH/H2O (4/1, 250 mL) was stirred at room tem-
perature for 2 h. The reaction mixture was concentrated under re-
duced pressure and the resulting residue was partitioned between
AcOEt and water. The AcOEt layer was washed with brine, dried
over anhydrous MgSO4, filtered, and concentrated under reduced
pressure to afford 3a (6.20 g, 95%) as a white solid: mp 148–
149 °C. 1H NMR (200 MHz, CDCl3) d: 1.47–2.00 (4H, m), 2.57–
2.88 (5H, m), 2.98 (8H, br m), 3.07–3.27 (1H, m), 3.50 (2H, t,
J = 6.6 Hz), 4.05–4.21 (1H, m), 4.72–4.84 (1H, m), 7.10–7.34 (5H,
m), 7.74–7.83 (2H, m). Anal. (C25H29ClN2O2) C, H, N.
7.41. tert-Butyl 7-{3-[4-(4-chlorophenyl)piperidin-1-yl]propo
xy}-1,2,4,5-tetrahydro-3H-3-benzazepine-3-carboxylate (35)
The title compound was prepared by a procedure similar to the
one described for 2a to provide 35 (41%) as a light yellow solid. 1H
NMR (300 MHz, CDCl3) d: 1.49 (9H, s), 1.69–1.84 (4H, m), 1.95–
2.11 (4H, m), 2.44–2.57 (3H, m), 2.84–2.85 (4H, m), 3.04–3.08
(2H, m), 3.53 (4H, br m), 4.00 (2H, t, J = 6.3 Hz), 6.64–6.69 (2H,
m), 7.01 (1H, d, J = 8.4 Hz), 7.14––7.18 (2H, m), 7.24–7.28 (2H, m).
7.37. 4-[4-(4-Chlorophenyl)piperidin-1-yl]-1-(3-methyl-2,3,4,5-
tetrahydro-1H-3-benzazepin-7-yl)-4-oxobutan-1-one (3b)
The title compound was prepared by a procedure similar to the
one described for 1c to provide 3b (60%) as a colorless solid: mp
143–145 °C. 1H NMR (200 MHz, CDCl3) d: 1.47–2.00 (4H, m), 2.38
(3H, s), 2.47–2.88 (8H, m), 2.95–3.06 (4H, m), 3.08–3.28 (1H, m),
3.35 (2H, t, J = 6.8 Hz), 4.07–4.21 (1H, m), 4.71–4.86 (1H, m),
7.08–7.34 (5H, m), 7.75–7.85 (2H, m). Anal. (C26H31ClN2O2) C, H, N.
7.42. 7-{3-[4-(4-Chlorophenyl)piperidin-1-yl]propoxy}-2,3,4,5-
tetrahydro-1H-3-benzazepine (36)
A mixture of 35 (0.48 g, 0.96 mmol) and TFA (5 mL) was stirred
at room temperature for 16 h. The reaction mixture was concen-
trated under reduced pressure and the resulting residue was parti-
tioned between AcOEt and 1 M NaOH solution. The AcOEt layer
was washed with brine, dried over anhydrous MgSO4, filtered
and concentrated under reduced pressure to give 36 (0.38 g,
quant.) as a yellow oil. 1H NMR (300 MHz, CDCl3) d: 1.79–1.81
(4H, m), 1.99–2.06 (4H, m), 2.48–2.59 (6H, m), 2.88–3.10 (7H,
m), 4.00 (2H, t, J = 6.2 Hz), 6.63–6.68 (2H, m), 6.98–7.02 (1H, m),
7.38. 1-(3-Acetyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-4-
[4-(4-chlorophenyl)piperidin-1-yl]-4-oxobutan-1-one (4)
To a mixture of 3a (0.20 g, 0.47 mmol) and K2CO3 (0.14 g,
1.00 mmol) in acetonitrie (5 mL) was added acetyl chloride

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S. Kasai et al. / Bioorg. Med. Chem. 19 (2011) 6261–6273
7.15 (2H, d, J = 8.6 Hz), 7.27 (2H, d, J = 8.6 Hz). This oil was treated
with 4 M HCl/AcOEt solution to give the dihydrochloride of 36.
At 1, 2, 4, 8 and 24 h after oral administration, blood samples were
collected from tail vein. The rats were then sacrificed, and the brain
tissues were collected and immediately stored at ꢀ80 °C. The blood
samples were centrifuged to obtain the plasma fraction. The brain
samples were homogenized in saline to obtain 20% (w/v) homoge-
7.43. 3-Acetyl-7-{3-[4-(4-chlorophenyl)piperidin-1-
yl]propoxy}-2,3,4,5-tetrahydro-1H-3-benzazepine (37)
nates. The 100
lL of plasma or brain homogenate was deproteinized
To a solution of 36 (0.10 g, 0.21 mmol) and triethylamine
(0.070 g, 0.69 mmol) in THF (10 mL) was added a solution of acetyl
chloride (0.018 g, 0.23 mmol). After being stirred at room temper-
ature for 2 h, the reaction mixture was partitioned between AcOEt
and water. The AcOEt layer was separated and washed with 5%
NaHCO3, brine, dried over anhydrous MgSO4. After removal of
the solvent under reduced pressure, the resulting residue was puri-
fied by alumina column chromatography (hexane/AcOEt = 3/2 to
AcOEt) to give 37 (0.080 g, 93%) as a white solid: mp 109 °C. 1H
NMR (300 MHz, CDCl3) d: 1.72–1.83 (4H, m), 1.96–2.11 (4H, m),
2.18 (3H, s), 2.50 (1H, m), 2.55 (2H, t like), 2.87–2.89 (4H, m),
3.04–3.09 (2H, m), 3.53–3.58 (2H, m), 3.67–3.74 (2H, m), 4.01
(2H, t, J = 6.3 Hz), 6.66–6.70 (2H, m), 7.00–7.07 (1H, m), 7.15 (2H,
d, J = 8.4 Hz), 7.27 (2H, d, J = 8.4 Hz). Anal. (C26H33ClN2O2) C, H, N.
with 100 L acetonitrile. After centrifugation, the supernatant ob-
l
tained was diluted 2-fold with 0.01 mol/L HCO2NH4 (adjusted to
pH 3.0 with HCO2H) and centrifuged again. The compound concen-
tration in the supernatant was measured by LC system with a UV
detector or LC/MS/MS system with an API3000 triple quadrupole
mass spectrometer (Perkin–Elmer Sciex). The mass spectrometer
was equipped with a turbo ionspray source and operated in positive
ion mode. The LC conditions were as follows: column, an L-column
ODS (4.6 ꢂ 250 mm, Chemicals evaluation and research institute,
Japan); mobile phase, mixture solution of 0.01 mol/L HCOONH4 (ad-
justed to pH 3.0 with HCO2H) and acetonitrile; flow rate (isocratic)
1.0 mL/min; column temperature, 25 °C.
7.46.2. Rat food intake inhibition study
Male F344 rats (10-week-old: CLEA Japan) were housed individ-
ually and given chow diet (CE-2: CLEA Japan). Two weeks later, the
rats were grouped based on the food intake and the body weight as
indices. At 3:00PM, the rats were weighed and their food bins were
removed from their cages. Simultaneously, 0.5% methylcellulose
solution was administered orally to the control group, and 0.5%
methylcellulose suspension (1, 3 and 10 mg/kg) of the compound
was administered orally to the compound administration group
at 2 mL/kg (6 per group). Food bin for each rat was inserted 1 h
after administration. Five-hour and 16-hour after presentation of
food bin), food intake of each rat was measured.
7.44. Homology modeling and ligand docking
The homology model of hMCHR1 was constructed using the
crystal structure of bovine rhodopsin (PDB code 1F88), which ob-
tained from the RCSB Protein Data Bank, as a structural template.25
The primary alignment of the amino acid sequences between
hMCHR1 and rhodopsin using MOE 2005.06. Construction of
hMCHR1 homology models and side chain rotamer search were
performed with MOE. Antagonists were docked into the obtained
receptor models using the program GOLD. Resulting docking
modes with receptor models were subjected energy minimization
with MOE. In the energy minimization process, the MMFF94s
forcefield was used.
Acknowledgments
The authors thank Hiroyuki Watanabe and Kazuyuki Irie for
parallel synthesis and Koji Oonishi and Masashi Yamaguchi for
their assistance in the pharmacokinetic studies.
7.45. Metabolic stability in hepatic microsomes
Human hepatic microsomes were purchased from Xenotech,
LLC (Lenexa, KS). An incubation mixture with a final volume of
0.1 mL consisted of microsomal protein in 50 mmol/L KH2PO4–
Supplementary data
Supplementary data (synthesis of starting materials (5, 9, 19,
11, 12, 13, and 29), parallel synthesis of compound 7a–n, and ele-
mental analysis data) associated with this article can be found, in
the online version, at doi:10.1016/j.bmc.2011.09.007.
K2HPO4 phosphate buffer (pH 7.4) and 1 lmol/L test compound.
The concentration of hepatic microsomal protein was 0.2 mg/mL.
An NADPH-generating system containing 50 mmol/L MgCl2,
50 mmol/L glucose-6-phosphate, 5 mmol/L beta-NADP+ and 15
unit/mL glucose-6-phosphate dehydrogenase was prepared and
added to the incubation mixture with a 10% volume of the reaction
mixture. After the addition of the NADPH-generating system, the
mixture was incubated at 37 °C for 0 and 20 min. The reaction
was terminated by the addition of acetonitrile equivalent to the
volume of the reaction mixture. All incubations were made in
duplicate. Test compound in the reaction mixture was measured
by LC system equipped with a UV detector. For metabolic stability
determinations, chromatograms were analyzed for parent com-
pound disappearance from the reaction mixtures.
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