4-Acylamino-and 4-ureidobenzamides as melanin-concentrating hormone (MCH) receptor 1 antagonists

Article abstract of DOI:10.1016/j.bmcl.2004.07.077

Synthesis, in vitro biological evaluation and structure-activity relationships of novel hMCH1R-antagonists are disclosed. The nature of the amine side chains could be varied considerably in contrast to the central benzamide scaffold and aromatic substituents.

Full text of DOI:10.1016/j.bmcl.2004.07.077

Bioorganic & Medicinal Chemistry Letters 14 (2004) 5075–5080
4-Acylamino- and 4-ureidobenzamides as
melanin-concentrating hormone (MCH) receptor 1 antagonists
Jean-Marie Receveur, Emelie Bjurling, Trond Ulven, Paul Brian Little,
Pia K. Nørregaard and ThomasHo¨gberg*
7TM Pharma A/S, Fremtidsvej 3, DK-2970 Hørsholm, Denmark
Received 23 June 2004; revised 28 July 2004; accepted 29 July 2004
Available online 20 August 2004
Abstract—Synthesis, in vitro biological evaluation and structure–activity relationships of 4-acylamino-and 4-ureidobenzamides as
novel hMCH1R-antagonists are disclosed. The nature of the amine side chains could be varied considerably in contrast to the cen-
tral benzamide scaffold and aromatic substituents.
Ó 2004 Elsevier Ltd. All rights reserved.
Melanin-concentrating hormone (MCH) isa nonadeca-
O
N
peptide found in rat1 and human brain.2 Expressed in
particular in the lateral hypothalamus, evidence for
involvement of MCH in feeding and body weight regu-
lation isabundant, 3 and includesthe observation of up-
regulated MCH mRNA in fasting rats and in obese
ob/ob rats, and increased food consumption upon
i.c.v.-injection of MCH in rats.4 Also, deletion of the
MCH-gene in mice results in a lean phenotype,5 whereas
overexpression of the MCH-gene in the lateral hypo-
thalamus gives an obese and insulin resistant pheno-
type.6 Furthermore, the hormone isreported to be
involved in memory functions,7 anxiety,8 and depres-
sion.9 Two seven transmembrane (7TM) G-protein cou-
pled receptors, MCH1R (SLC-1) and MCH2R (SLT),
have been identified for MCH,3,10,11 and MCH1R-defi-
cient mice are reported to be lean, hyperactive and
hyperphagic.12 Aminotetraline T-226296 (Fig. 1) was
the first reported small molecule MCH1R antagonist.13
T-226296 and SNAP-79419 (Fig. 1) were reported to
suppress food intake induced by i.c.v.-injected MCH
in rats. Thus, MCH1R antagonists are potentially inter-
esting agents for treatment of metabolic or obesity-re-
lated disorders, as well as of disorders related to
depression and anxiety.
N
H
T-226296
F
F
F
O
O
MeO
N
N
H
N
H
N
N
H
O
OMe
O
SNAP-7941
Figure 1. MCH antagonists.
A comparison of the physicochemical environment of
the binding site (physicogenetic analysis14) of the
MCH1 receptor with other 7TM receptorsrevealed a
high similarity to several monoaminergic receptors, in
particular dopamine D2 and D3. The combination of
the plethora of small molecule ligand information on
these receptors, especially the dopamine ligands exem-
plified in Figure 2,15 with the aminotetraline T-226296,
which wasthe only known MCH1R ligand at the time, 13
led to the design of novel benzamide ligands with a
hydrophobic western appendage. Especially appealing
wasthe preusmption that an intramolecular hydrogen
bond could lock the eastern amide side chain,15 forming
a coplanar arrangement similar to that in the aminotetra-
line. Furthermore, the 2-methoxybenzamide system may
Keywords: Melanin-concentrating hormone receptor 1; MCH1; MCH1
receptor; MCH1 receptor antagonists; Structure–activity relationships;
Benzamides.
*
Corresponding author. Tel.: +45 3925 7777; fax: +45 3925 7776;
e-mail: th@7tm.com
0960-894X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2004.07.077

5076
J.-M. Receveur et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5075–5080
O
O
Ph
O
N
N
Cl
Cl
N
H
OMe
N
H
R5
H2N
OMe
N
H
R3
H2N
OMe
R5 = H
metoclopramide
clebopride
(a)
F
R5 = Me
OH
O
(c)
(e)
H
O
H
Et
N
N
H
N
Br
O
O
N
H
OMe
eticlopride
Figure 2. Benzamide dopamine D2 ligands.
OMe
O
OMe
O
OMe
Cl
R2
OMe
N
R5
R3
NCQ 115
N
H
N
R5
R3
R2
R2
(b), (d)
(b), (d)
O
O
serve a dual purpose in promoting aqueous solubility by
introducing potential hydrogen donor/acceptor sites
available for interaction with water, while the intramo-
lecular hydrogen-bond may promote transport over
the blood–brain barrier by minimization of hydrogen
bond interaction sites. Modeling of putative ligands in
an MCH1 receptor homology model also corroborated
the need of a hydrophobic western side.16 Thus, the
benzamides I and II (Schemes1 and 2 ) appeared as
potentially interesting structures in the search for novel
MCH1R ligands.
R1
R1
N
H
R3
O
N
O
N
R2
H
R3
N
N
R5
H
R5
Ia: R3 = H,
R5 = H
IIa: R3 = H,
R5 = H
IIb: R3 = OMe, R5 = H
IIc: R3 = OMe, R5 = Me
Ib: R3 = OMe, R5 = H
Ic: R3 = OMe, R5 = Me
Id: R3 = H,
R5 = Me
Scheme 2. Reagentsand conditions: (a) paraformaldehyde, MeONa,
MeOH, 40°C, 12h; then NaBH4, rt to 50°C 8h; (b) LiOH, THF/
MeOH/water, rt 12h; (c) acid chloride (R2C6H4COCl), DCM, rt 12h;
(d) PS-DCC, HOBt, DCM, rt 30min; then amine (R1NH2) rt 12h; (e)
isocyanate (R2C6H4NCO), DCM, 12h; PS-trisamine, 12h.
The majority of the compoundswere synthesized by one
of the two equally efficient routesshown in Schemes1
and 2, depending on which part of the molecule that
wasin focusfor the exploration. Librarieswith diverse
western parts were constructed by coupling of 4-nitro-
benzoic acidswith an amine, hydrogenation of the nitro
group, and reaction in a parallel fashion with either acid
chloridesor isocyanatesto provide amides II or ureas I
(Scheme 1). Alternatively 4-aminobenzoic acidswere
reacted with acid chlorides or isocyanates, and the east-
ern amine part wasintroduced in the end to provide
libraries with diverse eastern parts (Scheme 2).
O
OH
O2N
R3
R3 = H
R3 = OMe
The N-methylated urea compoundswere synthesized by
similar routes incorporating reductive alkylation of the
anilinic nitrogen prior to coupling with isocyanates
(Schemes1 or 2 ). Compoundswith wetsern N-methyl-
ated ureas( 44, 45) aswell asthe cyclic urea 46 were syn-
thesized as outlined in Scheme 3.
(a), (b), (c)
O
R1
N
H
R5
N
R3
H
IIIa: R3 = H,
R5 = H
IIIb: R3 = OMe, R5 = H
IIIc: R3 = OMe, R5 = Me
Oxadiazoleswere ysntheiszed by the general route de-
picted in Scheme 4. Thus, the N-hydroxybenzamidine
wasformed by treatment of the nitrile with hydroxylam-
ine and sodium methoxide in the presence of the methyl
ester, and the oxadiazoles were obtained upon reaction
with the appropriate acyl chloride and dehydration,17
followed by hydrolysis of the methyl ester and coupling
with the appropriate amine.
(e)
(d)
O
O
O
R1
N
R1
N
H
O
R2
H
N
H
N
R5
R3
N
R5
R3
R2
Ia: R3 = H,
R5 = H
Ib: R3 = OMe, R5 = H
Ic: R3 = OMe, R5 = Me
IIa: R3 = H,
R5 = H
IIb: R3 = OMe, R5 = H
The initial 2-methoxybenzamideswere appended with a
biphenyl carboxamide western moiety analogous with
the aminotetraline T-226296 and in accordance with
the receptor modeling.16 Use of the metoclopramide
N,N-dimethylethylamine side chain (a) immediately led
to activity (1), albeit in the micromolar range (Table
1).18 Slightly increasing the bulk to N,N-diethyl resulted
in 10-fold improved affinity (2), asdid homologation of
Id: R3 = H,
R5 = Me
Scheme 1. Reagentsand condition:s (a) (i) (COCl) 2, DCM, DMF
(cat.), 0°C, 1h; (ii) amine (R1NH2), rt 12h; (b) H2, Pd/C, EtOH, rt 12h
or H2, Pt/C, EtOH, rt 12h; (c) (i) paraformaldehyde, MeONa, MeOH,
40°C, 12h; then NaBH4, rt to 50°C 8h; (ii) LiOH, THF/MeOH/water,
rt 12h; (d) acid chloride (R2C6H4COCl), DCM, rt,12h; (e) isocyanate
(R2C6H4NCO), DCM, 12h; PS-trisamine, 12h.

J.-M. Receveur et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5075–5080
5077
Replacement of the central amide linker with the bioiso-
stere oxadiazole (B series) led to compounds (9 and 10)
with activitiescomparable to the para-phenoxyphenyl
derivatives 7 and 8.
O
O
O
(c), (b)
NH2
O
OMe
OMe
N
N
H
OBn
Introduction of a urea moiety (C series) in the place of
the central amide linker resulted in a slight loss of affin-
ity for the biphenyl derivatives( 11 vs 3), but significantly
increased affinity and functional (IP3) activity for the
para-phenoxyphenyl series (12,13). The potency wasre-
tained by the removal of the methoxy group (14,15) or
by elongation to ethoxy (16). Extension of the eastern
amine side chain gained another order of magnitude in
potency (17). Notably, the corresponding meta-phen-
oxyphenyl compound 19 isequipotent with 17 and
shows improved functional response whereas the
ortho-analogue 18 isalmots devoid of affinity ( Table
1). The morpholine 20 was slightly less active than the
piperidine 19. In contrast to the amide series, the
enhancement in affinity of the 2-methoxy group (5 vs
6) isnot seen for the potent trifluorinated ureas( 21 vs
22 and 23 vs 24).
(d), (e), (f), (g)
O
(a), (b)
O
O
N
O
N
H
N
N
OMe
46
O
N
O
N
H
OMe
N
N
H
R4
44: R4 = Me, R5 = H
45: R4 = Me, R5 = Me
Scheme 3. Reagentsand conditions: (a) paraformaldehyde, MeONa,
MeOH, 40°C, 12h; then NaBH4, rt to 50°C 8h; (b) phosgene (20% in
PhMe), DIPEA, CH2Cl2, 0°C, 15min, followed by addition of aniline
IIIb–c; (c) benzyloxy acetaldehyde, MeOH, 0°C, 30min, then NaC-
NBH3, rt, 12h; (d) H2, Pd(OH)2/C, MeOH, 30°C, 5h; (e) methane-
sulfonyl chloride, DIPEA, 0°C, 2h and then rt, 12h, followed by Et3N,
CH3CN, 70°C, 2h; (f) LiOH, THF/MeOH/water, 30°C, 48h; (g) PS-
DCC, HOBt, DCM, rt, 30min; then amine, rt 12h.
The further influence of aromatic substituents was
investigated in this series (Table 2). Removal of the
phenoxy group resulted in complete loss of affinity
(27) and the introduction of a para-fluoro substituent
(28) only resulted in a weak affinity for the MCH1R.
Likewise, the 3,5-dimethoxy (30) displays a weak affinity
whereasthe 3,5-dichloro compound 32 givesa moderate
affinity, comparable to the 3-chloro-4-fluoro (31) and
3-trifluoromethoxy (34) derivatives. Introduction of a
larger halogen (Br) in the para-position (29) leadsto
an appreciable affinity. The favored para-halogen isalso
evidenced in the 3,4-dichloro compound 33. The
lower affinity of 36, 37, and 38 indicatesthat hydrophilic
propertiesin the para position are unfavorable. The
softer thiomethyl 39 and especially its trifluoro ana-
logue 41 have affinitiescomparable to the trifluorometh-
oxy derivative 21. The favorable featuresof the latter are
obviously optimal for the trifluoromethyl (23) deriva-
tive. The positive contribution by the para-positioned
trifluoromethoxy group can be counteracted by a
sterically demanding ortho-substituent like bromine
(35). The rigid para-phenyl moiety (11) provides
moderate affinity whereasthe more flexible para-phen-
oxy 12 is10-fold more active, which may be explained
by better fit into the hydrophobic binding pocket
(Tables1 and 2 ).
O
O
OMe
(a), (b)
OMe
N
R2
NC
N
O
(c), (d)
O
R1
N
H
N
R2
N
O
9 and 10
Scheme 4. Reagentsand conditions: (a) H 2NOH, MeONa, MeOH, rt,
48h; (b) (i) acid chloride (R2C6H4COCl), DIPEA, DCM, 0°C to rt,
12h; (ii) TBAF, THF, rt 48h; (c) LiOH, THF/MeOH/water (6:3:1), rt
12h; (d) H2N-R1, PS-DCC, HOBt, DCM, 48h; then PS-trisamine, rt,
2h.
the side chain (3). Further elongation of the eastern part
with N-benzylated side chains, well known from the
dopamine D2 ligands(cf. Fig. 2), wasgenerally well tol-
erated and in some cases resulted in improved affinity (4,
5). Accordingly, for this series, there is a considerable
freedom of operation around the eastern amine side
chain. However, removal of the 2-methoxy group from
The high binding affinity for the trifluoromethoxy or tri-
fluoromethyl derivatives 21–23 isconistsent with func-
tional inhibition in the IP3 assay (Table 1). However,
the high affinity for compound 24 (IC50 = 5nM) was
not reflected in the IP3 assay. Introduction of meta-phen-
ylamine in the western part (26) resulted in another
10-fold increase in affinity (IC50 = 8nM), aswell asappre-
ciable antagonistic functional activity (IC50 = 25nM). In
comparison with the phenoxy compounds, the corre-
sponding para-phenylamine derivative 25 is surprisingly
less active both in binding and functional assays (Table
1). Thismight indicate a pivotal interaction of the anil-
inic hydrogen in compound 26.
thisclassof biphenyl carboxamides(
1–5) resulted in
the complete loss of affinity (6). Furthermore, the biphe-
nyl western part seems to be somewhat superior to the
phenoxyphenyl for the amide linker (A series), since
insertion of an ether oxygen in 2 and 3 resulted in a
slight loss of activity (7 and 8, respectively).

5078
J.-M. Receveur et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5075–5080
Table 1.
O
O
O
R1
R1
Ph
R1
N
H
O
N
H
N
H
O
R2
R2
N
O
N
H
R3
R3
N
H
N
H
R3
R2
N
A
C
B
N
N
Ph
N
N
N
*
*
N
N
N
*
N
*
*
O
*
*
*
a
b
c
d
e
f
g
h
Compd
R1
R2
R3
hMCH1R
hMCH2R
Binding (lM)a
IP3 (lM)b
(lM)c
1
A
A
A
A
A
A
A
A
B
B
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
a
b
c
4-Ph
4-Ph
OMe
OMe
OMe
OMe
OMe
H
2.41 1.72 (3)
0.37
12
––
> 100a
––
> 100a
––
––
2
3
4-Ph
4-Ph
0.64
0.64
5.29
––
4
d
e
5
4-Ph
4-Ph
0.13
>100
––
––
6
a
b
c
––
––
7
4-PhO
4-PhO
4-PhO
4-PhO
4-Ph
OMe
OMe
H
1.97
1.92
6.81
––
8
––
––
9
b
f
2.45
1.90
––
––
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
H
––
––
c
OMe
OMe
OMe
H
1.48
0.14 0.10 (2)
0.53
––
b
f
4-PhO
4-PhO
4-PhO
4-PhO
4-PhO
4-PhO
2-PhO
3-PhO
3-PhO
0.88
3.45
––
––
f
0.25 0.16 (2)
0.14
0.24
1.30 0.17 (2)
5.82
6.31a
2.88a
––
d
b
g
g
g
h
b
b
b
b
g
g
H
OEt
OMe
OMe
OMe
OMe
OMe
H
1.95
0.24 0.19 (2)
––
0.059 0.021 (2)
>10
10a, >100b
0.028 0.002 (2)
0.074 0.008 (3)
0.059 0.0014 (2)
0.061 0.012 (2)
0.027 0.006 (2)
0.0053
0.032 0.022 (4)
0.112
>100a
>100a,b
>100a
>100a,b
>100a
––
4-CF3O
4-CF3O
4-CF3
0.26 0.085 (2)
0.25 0.049 (2)
0.17 0.060
0.17 0.07 (2)
1.44
OMe
H
4-CF3
4-PhNH
3-PhNH
OMe
OMe
0.85
0.0081 0.0025 (2)
0.025 0.011 (4)
10a
a Binding (IC50 CHO-whole cells).18
b Antagonism IP3 (IC50 CHO-whole cells).18
c Binding or antagonism IP3 (IC50 CHO-whole cells).18
To further investigate the binding mode of the urea-ser-
ies, the hydrogen-bond donating groups were systemat-
ically modified. Hence, methylation of the easternmost
nitrogen (R5) of the central urea of 12 (Table 3) was
not affecting the affinity notably (43), whereasmethyl-
ation at the westernmost nitrogen (R4) resulted in a sig-
nificant drop in affinity (44). Di-methylation of the urea
(45) resulted in a further drop to produce a virtually
inactive compound. We reasoned that this could be
due to repulsion between the methyl groups and disrup-
tion of the presumed planar trans,trans-configuration of
the urea. To investigate this, the cyclic urea 46 wassyn-
thesized without achieving any enhancement in affinity.
One possible explanation of these observations, that also
would provide a partial rationale for the higher affinity
of the urea compoundscompared to amidesand oxadi-
azoles, could be the involvement of the urea in a hydro-
gen-bond interaction with the receptor, preferably at the
western nitrogen.
N-Methylation of the benzamide to form 48 only mar-
ginally reduced the receptor-binding compared to 47.
However, a corresponding N-methylation of the meth-
oxybenzamide 12 to produce 49 resulted in a 100-fold
loss of affinity. These observations are most likely ex-
plained by a disruption of the planar 2-methoxybenz-
amide system. Finally, introduction of a 5-chloro in
the benzamide also resulted in a comparably inactive
compound (50), indicating that a planar conformation
of the urea in relation to the central benzamide isalso
required for activity.
In summary, by combining MCH1 receptor modeling
and structural input from dopamine D2 receptor lig-
and,s which according to our analyissisone of the
receptors with a binding site similar to MCH1R, with
the known aminotetraline T-226296, we were able
to identify new series of MCH1R antagonists. All
compounds showed excellent selectivity over MCH2R

J.-M. Receveur et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5075–5080
5079
Table 2.
(26) exhibited a single digit nanomolar activity that war-
rantsfurther investigations.
O
O
N
N
H
O
X
N
H
N
H
Acknowledgements
CH3
The authorswould like to extend their gratitude to B.
Aastrup, R. Andersen, J. Bundgaard, A. Christensen,
and M. Grimstrup, for their useful discussions and tech-
nical assistance.
X
hMCH1R binding (lM)a
27
28
29
30
31
32
33
34
21
35
36
37
38
39
40
41
23
42
11b
12
H
>100
15.8
0.25
18
4-F
4-Br
3,5-(OMe)2
3-Cl, 4-F
3,5-Cl2
3.9
4.8
References and notes
3,4-Cl2
3-CF3O
4-CF3O
0.71
2.5
1. Vaughan, J. M.; Fischer, W. H.; Hoeger, C.; Rivier, J.;
Vale, W. Endocrinology 1989, 125, 1660.
2. Mouri, T.; Takahashi, K.; Kawauchi, H.; Sone, M.;
Totsune, K.; Murakami, O.; Itoi, K.; Ohneda, M.; Sasano,
H.; Sasano, N. Peptides 1993, 14, 643.
0.15
8.8
2-Br, 4-CF3O
4-CH3CO
4-CF3CO
4-CN
13
5.9
3.2
3. Reviewson the involvement of MCH in feeding: (a)
Forray, C. Curr. Opin. Pharmacol. 2003, 3, 85; (b)
Kawano, H.; Honma, S.; Honma, A.; Horie, M.; Kawano,
Y.; Hayashi, S. Anat. Sci. Int. 2002, 77, 149.
4. (a) Presse, F.; Sorokovsky, I.; Max, J.-P.; Nicolaidis, S.;
Nahon, J.-L. Neuroscience 1996, 71, 735; (b) Qu, D.;
Ludwig, D. S.; Gammeltoft, S.; Piper, M.; Pelleymounter,
M. A.; Cullen, M. J.; Mathes, W. F.; Przypek, J.;
Kanarek, R.; Maratos-Flier, E. Nature 1996, 380, 243;
(c) Rossi, M.; Choi, S. J.; OÕShea, D.; Miyoshi, T.; Ghatel,
M. A.; Bloom, S. R. Endocrinology 1997, 138, 351.
5. Shimada, M.; Tritos, N. A.; Lowell, B. B.; Flier, J. S.;
Maratos-Flier, E. Nature 1998, 396, 670.
4-SMe
3-SMe
0.96
4.7
4-CF3S
4-CF3
3-CF3
0.20
0.052
7.9
4-Ph
4-PhO
9.1
0.72
a SPA-binding (IC50 CHO-membranes),18 usually giving higher IC50
values than whole cell assay used in Table 1.
b Three carbon amine side chain c (Table 1).
6. Ludwig, D. S.; Tritos, N. A.; Mastaitis, J. W.; Kulkarni,
R.; Kokkotou, E.; Elmquist, J.; Lowell, B.; Flier, J. S.;
Maratos-Flier, E. J. Clin. Investig. 2001, 107, 379.
7. Monzon, M. E.; de Souza, M. M.; Izquierdo, L. A.;
Izquierdo, I.; Barros, D. M.; de Barioglio, S. R. Peptides
1999, 20, 1517.
8. (a) Monzon, M. E.; De Barioglio, S. R. Physiol. Behav.
1999, 67, 813; (b) Varas, M.; Perez, M.; Monzon, M. E.;
Rubialesde Barioglio, S. Peptides 2002, 23, 2213.
9. Borowsky, B.; Durkin, M. M.; Ogozalek, K.; Marzabadi,
M. R.; DeLeon, J.; Heurich, R.; Lichtblau, H.; Shaposh-
nik, Z.; Daniewska, I.; Blackburn, T. P.; Branchek, T. A.;
Gerald, C.; Vaysse, P. J.; Forray, C. Nat. Med. 2002, 8,
825.
10. Identification of MCH1: (a) Chambers, J.; Ames, R. S.;
Bergsma, D.; Muir, A.; Fitzgerald, L. R.; Hervieu, G.;
Dytko, G. M.; Foley, J. J.; Martins, J.; Liu, W.-S.; Park,
J.; Ellis, C.; Ganguly, S.; Konchar, S.; Cluderay, J.; Leslie,
R.; Wilson, S.; Sarau, H. M. Nature 1999, 400, 261; (b)
Saito, Y.; Nothacker, H.-P.; Wang, Z.; Lin, S. H. S.;
Leslie, F.; Civelli, O. Nature 1999, 400, 265.
Table 3.
O
N
O
R7
N
R6
O
R3
N
N
R4 R5
R3
R4,R5
R6
R7 hMCH1R binding (lM)a
12 OMe H,H
H
H
H
H
H
H
H
H
H
Cl
0.72
0.54
5.8
43 OMe H,Me
44 OMe Me,H
45 OMe Me,Me
46 OMe CH2CH2
H
H
H
>100
>100
3.5
H
47
48
H
H
H,H
H,H
H
Me
Me
H
11
>100
>100
49 OMe H,H
50 OMe H,H
a SPA-binding (IC50 CHO-membranes).18
11. Identification of MCH2: (a) Sailer, A. W.; Sano, H.; Zeng,
Z.; McDonald, T. P.; Pan, J.; Pong, S.-S.; Feighner, S. D.;
Tan, C. P.; Fukami, T.; Iwaasa, H. H. D. L.; Morin, N.
R.; Sadowski, S. J.; Ito, M.; Ito, M.; Bansal, A.; Ky, B.;
Figueroa, D. J.; Jiang, Q.; Austin, C. P.; MacNeil, D. J.;
Ishihara, A.; Ihara, M.; Kanatani, A.; Van der Ploeg, L.
H. T.; Howard, A. D.; Liu, Q. Proc. Natl. Acad. Sci.
U.S.A. 2001, 98, 7564; (b) An, S.; Cutler, G.; Zhao, J. J.;
Huang, S.-G.; Tian, H.; Li, W.; Liang, L.; Rich, M.;
Bakleh, A.; Du, J.; Chen, J.-L.; Dai, K. Proc. Natl. Acad.
Sci. U.S.A. 2001, 98, 7576.
(Table 1). Despite the structural input from the dopam-
ine D2 and D3 ligandsit wasthe serotonin 5-HT and
2A
5-HT2C, histamine H2 and the dopamine transporter
that posed the largest selectivity issues for this class of
compounds.19 The activity of the compound series in
general exhibited a considerable structural tolerance
around the amine in the eastern part, but was generally
quite sensitive to modifications in the western part. Sub-
stituents that disrupted the planarity of the system
around the central benzamide were not tolerated. A urea
derivative having a western meta-anilinic phenyl moiety
12. Marsh, D. J.; Weingarth, D. T.; Novi, D. E.; Chen, H. Y.;
Trumbauer, M. E.; Chen, A. S.; Guan, X.-M.; Jiang, M.
M.; Feng, Y.; Camacho, R. E.; Shen, Z.; Frazier, E. G.;

5080
J.-M. Receveur et al. / Bioorg. Med. Chem. Lett. 14 (2004) 5075–5080
Yu, K. D.; Metzger, J. M.; Kuca, S. J.; Shearman, L. P.;
and hydrophobic binding pocket formed by the residues
Ala124, Phe128, Ile175, Phe213, Phe217, Trp269, Tyr272
Tyr273
Gopal-Truter, S.; MacNeil, D. J.; Strack, A. M.; MacIn-
tyre, D. E.; Van der Ploeg, L. H. T.; Qian, S. Proc. Natl.
Acad. Sci. U.S.A. 2002, 99, 3240–3245.
,
.
17. Gangloff, A. R.; Litvak, J.; Shelton, E. J.; Sperandio, D.;
Wang, V. R.; Rice, K. D. TetrahedronLett. 2001, 42, 1441.
18. Radioligand binding assay was conducted with
stably transfected CHO cells, expressing human MCH1
receptor or MCH2 receptor, by competition binding using
13. Takekawa, S.; Asami, A.; Ishihara, Y.; Terauchi, J.; Kato,
K.; Shimomura, Y.; Mori, M.; Murakoshi, H.; Kato, K.;
Suzuki, N.; Nishimura, O.; Fujino, M. Eur. J. Pharmacol.
2002, 438, 129.
14. Frimurer, T.; Ulven, T.; Elling, C.; Gerlach, L.-O.;
Ho¨gberg, T. A Physicogenetic Method to Assign Lig-
and-binding Relationships between 7TM Receptors
Applied on CRTH2. Presentation at XVIIIth Int. Symp.
Med. Chem. 2004, Session 3D, Copenhagen.
15. (a) Ho¨gberg, T. Drug DesignDiscov. 1993, 9, 333; (b)
Ho¨gberg, T. Drugs. Fut. 1991, 6, 333; (c) Ho¨gberg, T.;
Norinder, U.; Ra¨msby, S.; Stensland, B. J. Pharm.
Pharmacol. 1987, 39, 787.
16. Frimurer, T. Unpublished results: Explicit atomic models
of the transmembrane domain of MCH1R were con-
structed by use of the comparative modeling program
MODELLER [Sali, A.; Blundell, T. L. Comparative
Protein Modeling by Satisfaction of Spatial Restraints.
J. Mol. Biol. 1993, 234, 779–815] and the structural
framework of rhodopsin (PDB Protein Database code
1F88). Since no current comparative modeling method can
recover from an incorrect sequence alignment, maximal
effort waspaid to obtain the mots accurate alignment
possible, between the rhodopsin template and the target
sequence of MCH1R. The sequence alignment program
ClustalW [Higgins, D. G.; Thompson, J. D.; Gibson, T. J.
Using CLUSTAL for Multiple Sequence Alignments.
Meth. Enzymol. 1996, 266, 383–402] wasuesd to obtain
an alignment which wasin agreement with generic
fingerprints, specific to the rhodopsin-like receptor family
of 7TM receptor proteins[Baldwin, J. M. The Probable
Arrangement of the Helicesin G Protein-Coupled Recep-
tors. The EMBO J. 1993, 12, 1693–1703]. Considerations
to a proposed common TM binding site and associated
binding modesof ligandsrecognized by monoamine
receptors, in particular dopamine D2, suggested a lower
[
125I]-MCH. Alternatively, binding wasconducted as
scintillation proximity assay (SPA) by incubating mem-
branesfrom Eurocsreen (ES-370-M) and PEI-treated
WGA-coupled PVT SPA beads, type B from Amersham
Pharmacia Biotech, with tracer in the presences of various
concentrations of test compounds. Nonspecific binding
wasdetermined asthe binding in the preesnce of 1
lM
MCH. In the phosphatidylinositol assay, the cells were
incubated with 5lCi of [3H]-myo-inositol in inositol-free
culture medium. Phosphatidylinositol turnover was stim-
ulated by submaximal concentrations of MCH in the
presence of increasing amounts of ligand and the gener-
ated [3H]-inositol phosphates were purified on Bio-Rad
AG 1-X8 anion-exchange resin. Data were analyzed and
IC50 values determined by nonlinear regression. For
details of binding and functional assays see: Ho¨gberg,
T.; Bjurling, A. E.; Receveur, J.-M.; Little, P. B.; Elling, C.
E.; Nørregaard, P. K.; Ulven, T. Int. Pat. Appl. 2003, WO
03/087045 A1.
19. Receptor profiling wasconducted on representative com-
pounds at CEREP on 75 receptors, transporters and ion
channelsat 10 lM. Typical results on the nearest receptors
(IC50-value or percentage inhibition at 10lM): Compound
20: adenosine A3 48%, dopamine D1 57%, histamine H2
1.8lM, muscarinic M1 64%, opiate mu 48%, serotonin 5-
HT2A 0.67lM, serotonin 5-HT2C 1.3lM, NE transporter
68%, DA transporter 1.5lM. Compound 21: adenosine A3
36%, dopamine D1 78%, dopamine D2 79%, histamine H2
2.2lM, muscarinic M1 72%, muscarinic M2 46%, opiate
mu 44%, serotonin 5-HT2A 1.3lM, serotonin 5-HT2C
0.31lM, Sigma 65%, Na+ channel (site 2) 76%, NE
transporter 67%, DA transporter 6.9lM.