Phenylguanidines as selective nonpeptide melanocortin-5 receptor antagonists

Article abstract of DOI:10.1021/jm0400496

A series of phenylguanidine analogues represented by 10, 12, and 21 were synthesized and found to have high binding affinities for the human melanocortin-5 receptor. Their binding affinities for three other melanocortin receptor subtypes, MC1, MC3, and MC4, were low. Selected compounds were also tested for their functional activity and exhibited inhibition of α-MSH-stimulated cAMP production in cells expressing the human MC5 receptor. Compound 10 had a K_i value of 2.1 nM in the binding assay and an IC₅₀ of 72 nM in the functional assay. Some analogues such as 13 from this series possessed weak agonist activity at the human MC4 receptor.

Full text of DOI:10.1021/jm0400496

J . Med. Chem. 2004, 47, 4083-4088
4083
P h en ylgu a n id in es a s Selective Non p ep tid e Mela n ocor tin -5 Recep tor
An ta gon ists
Chen Chen,* J inghua Yu, Beth A. Fleck, Sam R. J . Hoare, J ohn Saunders, and Alan C. Foster
Departments of Medicinal Chemistry, Pharmacology, and Neuroscience, Neurocrine Biosciences, Inc.,
10555 Science Center Drive, San Diego, California 92121
Received February 26, 2004
A series of phenylguanidine analogues represented by 10, 12, and 21 were synthesized and
found to have high binding affinities for the human melanocortin-5 receptor. Their binding
affinities for three other melanocortin receptor subtypes, MC1, MC3, and MC4, were low.
Selected compounds were also tested for their functional activity and exhibited inhibition of
R-MSH-stimulated cAMP production in cells expressing the human MC5 receptor. Compound
10 had a Ki value of 2.1 nM in the binding assay and an IC50 of 72 nM in the functional assay.
Some analogues such as 13 from this series possessed weak agonist activity at the human
MC4 receptor.
In tr od u ction
Five receptors, MC1-5R, are known to mediate the
behavioral and physiological effects of melanocortin
peptides. Activation of these G-protein-coupled receptors
stimulates the production of cAMP in various tissues.1
The melanocortin-1 receptor (MC1R) is expressed in
epidermal and follicular melanocytes2 and regulates
skin pigmentation and the immune system.3 The MC2R
(ACTH receptor) controls steroid production in the
adrenal cortex.4 The MC3R,5 MC4R,6 and MC5R7 are
all found in the brain. While the MC3R may be involved
in the central regulation of body weight,8 the MC4R are
known to be important for body weight regulation and
influence of sexual behavior.9 A clear function for the
central melanocortin-5 receptor has not been deter-
mined. However, the MC5R is found in a wide range of
tissues and there is evidence that it may have a role in
regulating exocrine gland secretion.10 Peripherally, the
MC5R is expressed abundantly in pheromone-producing
exocrine glands, including sebaceous, lachrymal, Har-
derian, sex accessory, and preputial glands.11 Mice that
are genetically engineered to be MC5R-deficient
(MC5R-/-) have defective sebaceous and Harderian
glands.11a Studies on the behavioral activities in MC5R-
deficiet mice have been reported recently.12,13
The melanocortin peptides are the natural ligands for
the MCRs and consist of the melanotropins R-MSH,
â-MSH, and γ-MSH and the adrenocorticotropin ACTH.
Interestingly, agouti-protein and agouti-related protein
have been discovered as endogenous antagonists or
inverse agonists of the melanocortin receptors.1 Because
of the importance of the MC4R in feeding behavior,
metabolism, and energy homeostasis, recent research
efforts have been focused on the discovery of selective
MC4R agonists or antagonists for potential treatment
of human diseases such as obesity and cachexia.14
Highly potent and selective small molecule MC4R
agonists such as 1 have been reported (Figure 1).15
Moreover, MC1R-selective agonists, such as compound
F igu r e 1. Small molecule agonists for the melanocortin
receptors.
2, have been reported recently and demonstrated ef-
ficacy in an acute model of inflammation.16 By contrast,
MC5R-selective small molecule ligands, which could be
useful to further define the biological role of the mel-
anocortin-5 receptor, have not been described. Here we
report a series of N-alkyl-N′-phenylguanidines as potent
and selective antagonists at the human melanocortin-5
receptor.17
Ch em istr y
The synthesis of the targeted phenylguanidines is
showed in Scheme 1. The commercially available 4-azi-
dobenzoic acid was coupled with 2,4-dichlorophenethyl-
amine under standard peptide coupling conditions
(EDC/DIEA/THF) to give the corresponding amide 3 in
68% isolated yield. This amide 3 was then treated with
triphenylphosphine in THF at room temperature to form
an azo-Wittig intermediate, which was reacted with
cyclohexyl isocyanate at 70 °C to form an iminoimide
that was converted to the desired guanidines 4-25 by
reaction with various primary or secondary amines in
a one-pot synthesis.
Resu lts a n d Discu ssion
These compounds were then tested in a competitive
binding assay using HEK293 cells stably expressing the
human melanocortin-5 receptor and [125I]NDP-MSH as
the radiolabeled ligand, as previously described.18 The
structure-activity relationships of the phenylguanidines
at the human MC5 receptor are depicted in Table 1.
Selected compounds were then measured for their
* Corresponding author. Tel: 1-858-658-7600. Fax: 1-858-658-7602.
E-mail: cchen@neurocrine.com.
10.1021/jm0400496 CCC: $27.50 © 2004 American Chemical Society
Published on Web 06/23/2004

4084 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 16
Chen et al.
Sch em e 1a
a
Reagents and conditions: (a) 2,4-dichlorophenethylamine/EDC/THF; (b) Ph3P/THF; (c) cyclohexyl isocyanate, 70 °C; (d) R1R2NH,
70 °C.
Ta ble 1. Binding Affinities of Phenylguanidines at the Human MC5 Receptora
a
b
Receptors expressed in HEK293 cells. Ki values (n > 3) determined by radioligand binding assay using [125I]NDP-MSH.
binding affinities for the human MC1, MC3, and MC4
receptors to determine selectivity. They were further
tested for their abilities to stimulate cAMP production
at 10 µM concentration in cells expressing the human
MC4 and MC5 receptors for functional agonistic activity.
EC50 values were obtained from dose-dependent curves
for compounds stimulating cAMP release at >25% levels
of R-MSH. Compounds with high MC5R affinity from

Phenylguanidines as MC5 Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 16 4085
Ta ble 2. Binding, Selectivity, and Functional Activity of
Phenylguanidinesa
hMC4
EC50
compd Ki (µM)b Ki (µM) (µM) (µM) (IA)c
hMC5
hMC1
hMC3
Ki
Ki
IC50
(µM)
(µM)
9
10
11
12
13
21
22
23
0.40
(25%)
(29%)
0.36
(23%)
(27%)
1.9
2.2
3.5
2.8
2.8
3.9
2.4
2.5
2.3
0.65
0.84
0.58
1.9 (28%) 0.018
2.7 (37%) 0.0021 0.072
1.8 (65%) 0.021
0.46
0.38
0.84 NDd
0.59
0.0059 0.38
4.0 (76%) 0.011
0.089
1.3
1.5
1.4
2.9 (45%) 0.0053 0.53e
NDd
4.6 (36%) 0.036
0.026
0.53
0.63
F igu r e 2. Inhibition curves for compound 10 in radioligand
binding assays for human MC1, MC3, MC4, and MC5 recep-
tors expressed in HEK293 cells. Inhibition of [125I]NDP-MSH
binding to cell membranes bearing the receptors was measured
as described in ref 18.
(27%)
a
Data are average of at least three independent determinations.
b
Values in parentheses are percentage inhibition at 10 µM
concentration. c Intrinsic activity: percentage of maximal cAMP
production relative to R-MSH. Not determined. e Single deter-
d
mination.
Compound 13 bound to the MC4R with a Ki of 590 nM;
however, it stimulated cAMP production to 76% of the
maximal level for R-MSH, with an EC50 value of 4.0 µM.
None of these compounds significantly stimulated
cAMP production in MC5R-containing cells (<2% of
R-MSH, data not shown). We then tested their abilities
to inhibit R-MSH-stimulated cAMP production as pos-
sible functional antagonistic activity on the MC5R.
Several compounds displayed good potency in this assay
(Table 2). For example, the IC50 values for 10 and 13
were 72 and 89 nM, respectively. These results dem-
onstrated that these compounds were functional an-
tagonists at the human MC5 receptor.
All compounds listed in Table 2 had low binding
affinities at the MC1, MC3, and MC4 receptors, al-
though most of them exhibited weak agonistic activities
at the MC4 receptor. The Ki ratios of MC5R vs MC1R,
MC3R, or MC4R for many compounds were over 100,
making this series of compounds, especially 10, 12, and
21, MC5 receptor-selective antagonists (Figure 2). Al-
though the physiological function of the MC5 receptor
remains unclear at present, this series of compounds
certainly could serve as useful tools for defining and
delineating the roles of this receptor.
the binding experiments were also tested for their
abilities to inhibit R-MSH-stimulated cAMP production
as functional antagonist activity. These results are
summarized in Table 2.
In the competitive binding assay, the nonsubstituted
piperazine guanidine 9 bound to the MC5 receptor with
a Ki value of 18 nM, and the binding affinity of the
corresponding N-methylated analogue 8 was slightly
lower (Ki ) 50 nM). However, the 3-methylpiperazine
with an R-configuration increased the binding by almost
10-fold (10, Ki ) 2.1 nM), while the S-methyl group had
little effect (11, Ki ) 21 nM). The fact that the (3R)-
methylpiperazine 10 bound to the MC5 receptor better
than the corresponding (3S)-isomer 11 demonstrated a
strong stereospecific effect at the 3-position of pipera-
zine. The trans-2,5-dimethylpiperazine 12 (Ki ) 5.9 nM)
exhibited slightly higher Ki value than 10, which may
imply that the 2-methyl substituent of the piperazine
had minimal effect on the receptor binding.
While the size of the 4-substituent of piperazine
seemed to have a minimal impact (the N-benzyl ana-
logue 7, Ki ) 44 nM, had similar binding affinity to the
N-methyl analogue 8, Ki ) 50 nM), the basic 4-nitrogen
was important for high affinity. Thus, the 4-phenyl (5)
and 4-pyrimidinyl (6) compounds exhibited lower bind-
ing affinities (Ki values of 5 and 6 were 290 and 305
nM, respectively) than 7 or 8. This was also true when
the piperazine was replaced by piperidine, morpholine,
or piperazinone (compounds 14-17, Ki’s > 140 nM).
Although the piperazine moiety was important for high
affinity binding, it could be replaced by an aminoalkyl
group. For example, the 2-aminoisobutyl compound 21
had a Ki value of 5.3 nM, which was comparable to that
of the piperazine 10. Compounds 22 and 23 also
possessed good MC5 receptor binding affinities (Ki
values of 26 and 36 nM, respectively).
Con clu sion
In summary, we have synthesized a series of phen-
ylguanidines as melanocortin-5 antagonists via an aza-
Wittig reaction. These compounds possessed low nano-
molar binding affinities and full antagonistic function
at the human MC5 receptor. For example, 10 had Ki
value of 2.1 nM at the MC5 receptor and >840 nM at
the MC1, MC3, and MC4 receptor subtypes. The high
MC5 receptor selectivity of these compounds should
make them useful as potent MC5 antagonists for further
exploring the physiological role of the melanocortin-5
receptor.
None of these phenylguanidines had appreciable
affinity for the human MC1R except compounds 9 and
12, which had Ki values of 400 and 360 nM, respectively.
All compounds tested had weak binding affinities for
the human MC3R (Ki values of 2-3 µM, Table 2).
Interestingly, these compounds exhibited modest bind-
ing affinities for the human MC4 recptor and stimulated
cAMP production with various intrinsic activities. For
example, compound 9 had a Ki value of 650 nM and
stimulated cAMP production but only to the 28%
maximal level of R-MSH, with an EC50 value of 1.9 µM.
Exp er im en ta l Section
1
Gen er a l P r oced u r es. H NMR spectra were recorded on
Varian spectrometer (Mercury 300 Hz) using TMS as the
internal standard and CDCl3 as the solvent, except where
indicated. LC-MS analyses were performed on a Perkin-Elmer
Sciex API-100 mass spectrometer using the electron spray
ionization technique or a SpectraSystem P4000 HPLC system
coupled with a Finnigan LCD/Deca mass spectrometer using
the electrospray ionization technique. HRMS ESI was carried
out on a Bruker 4.7T BIOAPEX FTMS mass spectrometer. All
commercially available reagents were used without further
purification.

4086 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 16
Chen et al.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-a za d op h en ylca r box-
a m id e 3. To a mixture of 2-(2,4-dichlorophenyl)ethylamine
(19.9 mmol), 4-azidobenzoic acid (21.9 mmol), and EDC (21.9
mmol) in THF was added DIEA (43.8 mmol) at room temper-
ature. The mixture was stirred overnight and the solvent was
removed. The residue was diluted with ethyl acetate; washed
with 1 N HCl, brine, and saturated NaHCO3; dried over
MgSO4; and concentrated to give a solid, which was purified
on silica gel with ethyl acetate/hexane (1:4) to give the title
compound (68%): 1H NMR (300 MHz, CDCl3) δ 3.06 (t, J )
6.9 Hz, 2H), 3.71 (dt, J ) 7.2, 6.0 Hz, 2H), 6.17 (t, J ) 6.0 Hz,
1H), 7.07 (d, J ) 8.7 Hz, 2H), 7.20 (d, J ) 1.5 Hz, 2H), 7.41 (s,
1H), 7.72 (d, J ) 8.7 Hz, 2H) ppm; APCI MS m/z 335.2 [MH]+,
307.2 [MH+ - N2].
Gen er a l P r oced u r e for Syn th esis of 4-25. To a solution
of N-[2-(2,4-dichlorophenyl)ethyl]-4-azadophenylcarboxamide
(1 equiv) in THF was added triphenylphosphine (1.2 equiv) at
room temperature. After 10 min, cyclohexyl isocyanate (1.2
equiv) was added. The solution was heated at 70 °C overnight.
An appropriated amine (2 equiv) was then added and the
mixture was further heated at 70 °C for 2 h. THF was removed
in vacuo, and the residue was dissolved in 1 N HCl and water
and extracted with ether. The aqueous layer was treated with
saturated NaHCO3 and extracted with ethyl acetate. The
combined ethyl acetate layers were dried over MgSO4 and
concentrated, and the residue was purified on silica gel
(aqueous NH4OH:MeOH:DCM, 1:5:94) to give the desired
produce in 17-100% yield.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(4-(2,5-d im et h ylp h en yl)-1-p ip er a zin yl)m et h yl]a m in o}-
ben za m id e (4): white solid, 87 mg (90%); 1H NMR (300 MHz,
CDCl3) δ 0.90-1.34 (m, 4H), 1.52-1.75 (m, 4H), 1.91 (m, 2H),
2.26 (s, 3H), 2.31 (s. 3H), 2.92 (t, J ) 4.2 Hz, 4H), 3.05 (t, J )
6.6 Hz, 2H), 3.18 (brs, 1H), 3.38 (t, J ) 4.5 Hz, 4H), 3.79 (dt,
J ) 6.6, 6.3 Hz, 2H), 6.16 (t, J ) 5.7 Hz, 1H), 6.82 (d, J ) 7.2
Hz, 1H), 6.84 (s, 1H), 6.88 (d, J ) 8.4 Hz, 2H), 7.07 (d, J ) 7.2
Hz, 1H), 7.19 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz,
1H), 7.39 (d, J ) 1.2 Hz, 1H), 7.64 (d, J ) 8.4 Hz, 2H); LC-
MS m/z 606.4 [MH]+, tR 8.31 min. Anal. (C34H41Cl2N5O) C, H,
N.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(4-p h en yl-1-p ip er a zin yl)m et h yl]a m in o}b en za m id e (5):
white solid, 79 mg (85%); 1H NMR (300 MHz, CDCl3) δ 0.90-
1.30 (m, 4H), 1.52-1.76 (m, 4H), 1.90 (m, 2H), 3.05 (t, J ) 6.6
Hz, 2H), 3.15 (brs, 1H), 3.21 (t, J ) 5.4 Hz, 4H), 3.41 (t, J )
5.4 Hz, 4H), 3.69 (dt, J ) 7.2, 6.0 Hz, 2H), 6.15 (t, J ) 5.4 Hz,
1H), 6.86 (d, J ) 8.4 Hz, 2H), 6.89 (t, J ) 7.5 Hz, 1H), 6.95 (d,
J ) 8.4 Hz, 2H), 7.19 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J )
8.0 Hz, 1H), 7.28 (dd, J ) 8.4, 7.5 Hz, 2H), 7.39 (d, J ) 1.5 Hz,
1H), 7.64 (d, J ) 8.4 Hz, 2H); LC-MS m/z 578.5 [MH]+, tR
7.51 min. Anal. (C32H37Cl2N5O) C, H, N.
MHz, CDCl3) δ 0.90-1.30 (m, 4H), 1.50-1.95 (m, 6H), 2.30 (s,
3H), 2.42 (m, 4H), 3.10 (t, J ) 7.0 Hz, 2H), 3.20 (brs, 1H), 3.29
(m, 4H), 3.69 (dt, J ) 7.2, 6.0 Hz, 2H), 6.40 (brs, 1H), 6.91 (d,
J ) 8.7 Hz, 2H), 7.19 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J )
8.0 Hz, 1H), 7.39 (d, J ) 1.5 Hz, 1H), 7.67 (d, J ) 8.7 Hz, 2H);
LC-MS m/z 516.1 [MH]+, tR 5.18 min; HRMS (MALDI-FTMS)
calcd for C27H35Cl2N5O 516.2291, found 516.2287.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(1-p ip er a zin yl)m eth yl]a m in o}ben za m id e (9): white solid,
38 mg (47%); 1H NMR (300 MHz, CDCl3) δ 0.90-1.30 (m, 4H),
1.52-1.94 (m, 6H), 2.89 (t, J ) 5.4 Hz, 4H), 3.04 (t, J ) 7.2
Hz, 2H), 3.11 (brs, 1H), 3.20 (t, J ) 5.4 Hz, 4H), 3.68 (dt, J )
6.9, 6.3 Hz, 2H), 6.16 (t, J ) 6.0 Hz, 1H), 6.84 (d, J ) 9.0 Hz,
2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H), 7.20 (d, J ) 8.0 Hz, 1H),
7.39 (d, J ) 1.5 Hz, 1H), 7.63 (d, J ) 8.4 Hz, 2H); LC-MS m/z
502.3 [MH]+, tR 5.26 min. Anal. (C26H33Cl2N5O) C, H, N.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(3R-m eth yl-1-piper a zin yl)m eth yl]a m in o}ben za m id e (10):
white solid, 18 mg (22%); 1H NMR (300 MHz, CDCl3) δ 0.94-
1.30 (m, 4H), 1.05 (d, J ) 6.6 Hz, 3H), 1.50-1.94 (m, 6H), 2.47
(dd, J ) 10.2, 12.9 Hz, 1H), 2.72-3.01 (m, 5H), 3.05 (t, J )
7.5 Hz, 2H), 3.10 (brs, 1H), 3.53 (d, J ) 10.8 Hz, 2H), 3.68 (dt,
J ) 6.9, 6.3 Hz, 2H), 6.16 (t, J ) 5.7 Hz, 1H), 6.85 (d, J ) 8.4
Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H), 7.22 (d, J ) 8.0 Hz,
1H), 7.39 (d, J ) 1.2 Hz, 1H), 7.63 (d, J ) 8.4 Hz, 2H); LC-
MS m/z 516.4 [MH]+, tR 5.32 min; HRMS (MALDI-FTMS)
calcd for C27H35Cl2N5O: 516.2291, found 516.2287.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(3S-m eth yl-1-p ip er a zin yl)m eth yl]a m in o}ben za m id e (11):
white solid, 59 mg (72%); 1H NMR (300 MHz, CDCl3) δ 0.88-
1.30 (m, 4H), 1.05 (d, J ) 6.3 Hz, 3H), 1.50-1.92 (m, 6H), 2.47
(dd, J ) 10.2, 12.9 Hz, 1H), 2.70-3.00 (m, 5H), 3.05 (t, J )
6.9 Hz, 2H), 3.12 (brs, 1H), 3.53 (d, J ) 11.4 Hz, 2H), 3.68 (dt,
J ) 6.9, 6.3 Hz, 2H), 6.14 (t, J ) 6.3 Hz, 1H), 6.85 (d, J ) 8.4
Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz,
1H), 7.39 (d, J ) 1.8 Hz, 1H), 7.63 (d, J ) 8.4 Hz, 2H); LC-
MS m/z 516.3 [MH]+, tR 5.32 min. Anal. (C27H35Cl2N5O‚0.5H2O)
C, H, N.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(2,5-tr a n s-d im eth yl-1-p ip er a zin yl)m eth yl]a m in o}ben za -
m id e (12): white solid, 39 mg (46%); 1H NMR (300 MHz,
CDCl3) δ 0.90-1.34 (m, 4H), 1.08 (d, J ) 6.6 Hz, 3H), 1.18 (d,
J ) 6.0 Hz, 3H), 1.52-1.96 (m, 6H), 2.55 (m, 2H), 2.84-3.38
(m, 8H), 3.63-3.73 (dt, J ) 6.6, 6.6 Hz, 2H), 6.16 (t, J ) 5.7
Hz, 1H), 6.86 (d, J ) 8.4 Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz,
1H), 7.21 (d, J ) 8.0 Hz, 1H), 7.39 (d, J ) 1.8 Hz, 1H), 7.64 (d,
J ) 8.4 Hz, 2H); LC-MS m/z 530.3 [MH]+, tR 5.43 min. Anal.
(C28H37Cl2N5O‚0.5H2O) C, H, N.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(3,5-d im et h yl-1-p ip er a zin yl)m et h yl]a m in o}b en za m id e
1
(13): white solid, 82 mg (97%); H NMR (300 MHz, CDCl3) δ
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(4-(1-p yr im id in yl)-1-p ip er a zin yl)m et h yl]a m in o}b en za -
m id e 4-(1-p yr im id in e)p ip er a zin e (6): white solid, 90 mg
(97%); 1H NMR (300 MHz, CDCl3) δ 1.00-1.30 (m, 4H), 1.52-
1.98 (m, 6H), 3.05 (t, J ) 6.9 Hz, 2H), 3.27 (brs, 1H), 3.35 (t,
J ) 4.5 Hz, 4H), 3.69 (dt, J ) 7.2, 6.0 Hz, 2H), 3.86 (t, J ) 4.8
Hz, 4H), 6.34 (brs, 1H), 6.53 (t, J ) 5.1 Hz, 1H), 6.92 (d, J )
7.5 Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz,
1H), 7.39 (d, J ) 1.5 Hz, 1H), 7.67 (d, J ) 8.4 Hz, 2H), 8.31 (d,
J ) 4.8 Hz, 2H); LC-MS m/z 580.5 [MH]+, tR 6.66 min. Anal.
(C30H35Cl2N7O‚1/3H2O) C, H, N.
0.89-1.29 (m, 4H), 1.06 (d, J ) 6.0 Hz, 6H), 1.50-1.92 (m,
6H), 2.38 (dd, J ) 12.3, 10.5 Hz, 2H), 2.90 (m, 2H), 3.04 (t, J
) 7.2 Hz, 2H), 3.12 (brs, 1H), 3.42 (brs, 1H), 3.54 (d, J ) 12.9
Hz, 2H), 3.68 (dt, J ) 6.9, 6.3 Hz, 2H), 6.16 (t, J ) 6.0 Hz,
1H), 6.82 (d, J ) 8.4 Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H),
7.21 (d, J ) 8.0 Hz, 1H), 7.38 (d, J ) 1.2 Hz, 1H), 7.62 (d, J )
8.4 Hz, 2H); LC-MS m/z 530.5 [MH]+, tR 5.36 min. Anal.
(C28H37Cl2N5O) C, H, N.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(3,5-d im eth yl-1-m or p h olin yl)m eth yl]a m in o}ben za m id e
1
(14): white solid, 71 mg (89%); H NMR (300 MHz, CDCl3) δ
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(4-b en zyl-1-p ip er a zin yl)m et h yl]a m in o}b en za m id e (7):
white solid, 55 mg (58%); 1H NMR (300 MHz, CDCl3) δ 1.04-
1.34 (m, 4H), 1.50-1.94 (m, 6H), 2.45(brs, 4H), 3.06 (t, J )
6.9 Hz, 2H), 3.29 (brs, 5H), 3.51 (s, 2H), 3.69 (dt, J ) 6.9, 6.6
Hz, 2H), 6.46 (brs, 1H), 6.95 (d, J ) 6.3 Hz, 2H), 7.17 (dd, J )
8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz, 1H), 7.28 (m, 5H), 7.38
(d, J ) 1.5 Hz, 1H), 7.68 (d, J ) 8.4 Hz, 2H); LC-MS m/z
592.3 [MH]+, tR 5.75 min. Anal. (C33H39Cl2N5O‚H2O) C, H, N.
0.88-1.30 (m, 10H), 1.50-1.96 (m, 6H), 2.40-4.10 (m, 11H),
6.16 (brs. 1H), 6.82 (d, J ) 8.7 Hz, 2H), 7.18 (dd, J ) 8.0, 1.8
Hz, 1H), 7.21 (d, J ) 8.0 Hz, 1H),7.39 (d, J ) 1.8 Hz, 1H),
7.63 (d, J ) 7.5 Hz, 2H); LC-MS m/z 531.1 [MH]+, tR 6.77
min; HRMS (MALDI-FTMS) calcd for C28H36Cl2N4O2 531.2288,
found 531.2263.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(3,5-d im et h yl-1-p ip er a zin yl)m et h yl]a m in o}b en za m id e
1
(15): white solid, 27 mg (34%); H NMR (300 MHz, CDCl3) δ
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(4-m eth yl-1-p ip er a zin yl)m eth yl]a m in o}ben za m id e 4-m e-
th ylp ip er a zin e (8): white solid, 27 mg (35%); H NMR (300
0.61-1.60 (m, 12H), 1.50-1.96 (m, 6H), 2.20-3.80 (m, 11H),
6.13 (t, J ) 6.0 Hz, 1H), 6.84 (m, 2H), 7.18 (dd, J ) 8.0, 1.8
Hz, 1H), 7.21 (d, J ) 8.0 Hz, 1H), 7.39 (d, J ) 1.8 Hz, 1H),
1

Phenylguanidines as MC5 Receptor Antagonists
J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 16 4087
7.62 (d, J ) 8.4 Hz, 2H); LC-MS m/z 529.1 [MH]+, tR 7.56
min; HRMS (MALDI-FTMS) calcd for C29H38Cl2N4O 529.2495,
found 529.2479.
δ 0.96-1.30 (m, 4H), 1.50-1.80 (m, 4H), 1.90 (m, 2H), 2.05
(m, 1H), 2.41 (s, 3H), 3.04 (t, J ) 6.9 Hz, 2H), 3.08 (m, 1H),
3.18-3.54 (m, 5H), 3.67 (dt, J ) 6.9, 6.3 Hz, 2H), 3.91 (brs,
1H), 6.16 (t, J ) 5.7 Hz, 1H), 6.83 (d, J ) 8.7 Hz, 2H), 7.18
(dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz, 1H), 7.38 (d, J
) 1.8 Hz, 1H), 7.59 (d, J ) 8.4 Hz, 2H); LC-MS m/z 516.3
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(3-oxo-1-piper azin yl)m eth yl]am in o}ben zam ide (16): white
1
solid, 73 mg (88%); H NMR (300 MHz, CDCl3) δ 0.90-1.30
[MH]+, tR 5.33 min; HRMS (MALDI-FTMS) calcd for C27H35
-
(m, 4H), 1.50-1.90 (m, 6H), 3.00 (brs, 1H), 3.05 (t, J ) 6.9
Hz, 2H), 3.45-3.57 (m, 4H), 3.70 (dt, J ) 6.3, 4.8 Hz, 2H),
3.96 (s, 2H), 6.20 (m, 2H), 6.83 (d, J ) 8.4 Hz, 2H), 7.18 (dd,
J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz, 1H), 7.39 (d, J ) 0.9
Hz, 1H), 7.65 (d, J ) 8.4 Hz, 2H); LC-MS m/z 516.4 [MH]+,
tR 5.91 min. Anal. (C26H31Cl2N5O2‚1/3H2O) C, H, N.
Cl2N5O 516.2291, found 516.2305.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(4-a m in o-1-p ip er id in yl)m eth yl]a m in o}ben za m id e (24):
white solid, 21 mg (25%); 1H NMR (300 MHz, CDCl3) δ 0.92-
1.94 (m, 14H), 2.74-2.90 (m, 3H), 3.04 (t, J ) 7.2 Hz, 2H),
3.11 (brs, 1H), 3.59-3.73 (m, 4H), 6.18 (t, J ) 5.7 Hz, 1H),
6.84 (d, J ) 8.1 Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21
(d, J ) 8.0 Hz, 1H), 7.39 (d, J ) 1.8 Hz, 1H), 7.63 (d, J ) 8.4
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(2-m et h yl-3-oxo-1-p ip er a zin yl)m et h yl]a m in o}b en za m -
id e (17): white solid, 92 mg (100%); 1H NMR (300 MHz, CDCl3)
δ 0.84-1.26 (m, 4H), 1.52 (d, J ) 7.5 Hz, 3H), 1.50-1.92 (m,
6H), 3.00 (m, 1H), 3.05 (t, J ) 6.9 Hz, 2H), 3.23-3.36 (m, 3H),
3.68 (m, 2H), 3.78 (m, 1H), 4.34 (q, J ) 7.5 Hz, 1H), 6.20 (m,
2H), 6.81 (d, J ) 8.4 Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H),
7.21 (d, J ) 8.0 Hz, 1H), 7.39 (d, J ) 1.2 Hz, 1H), 7.64 (d, J )
8.4 Hz, 2H); LC-MS m/z 530.5 [MH]+, tR 5.97 min. Anal.
(C27H33Cl2N5O) C, H, N.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(N-cycloh exyl-N-m et h yla m in o)m et h yl]a m in o}b en za m -
id e (18): white solid, 78 mg (92%); 1H NMR (300 MHz, CDCl3)
δ 1.0-1.36 (m, 8H), 1.40-1.96 (m, 12H), 2.71 (s, 3H), 3.06 (t,
J ) 6.9 Hz, 2H), 3.29 (brs, 1H), 3.57 (brs, 1H), 3.69 (dt, J )
7.2, 6.0 Hz, 2H), 6.48 (brs, 1H), 6.92 (brs, 2H), 7.16 (dd, J )
8.0, 1.8 Hz, 1H), 7.22 (d, J ) 8.0 Hz, 1H), 7.37 (d, J ) 1.8 Hz,
1H), 7.68 (d, J ) 6.9 Hz, 2H); LC-MS m/z 529.3 [MH]+, tR
7.52 min. Anal. (C29H38Cl2N4O‚H2O) C, H, N.
Hz, 2H); LC-MS m/z 516.3 [MH]+, tR 5.36 min. Anal. (C27H35
-
Cl2N5O‚1/3H2O) C, H, N.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(4-(1-p yr r olid in yl)-1-p ip er id in yl)m eth yl]a m in o}ben za m -
id e (25): white solid, 85 mg (93%); 1H NMR (300 MHz, CDCl3)
δ 0.90-1.30 (m, 4H), 1.42-2.20 (m, 14H), 2.59 (brs, 4 H), 2.77
(t, J ) 12.3 Hz, 2H), 3.04 (t, J ) 7.2 Hz, 2H), 3.10 (brs, 1H),
3.46 (brs, 1H), 3.60-3.74 (m, 4H), 6.12 (t, J ) 5.7 Hz, 1H),
6.83 (d, J ) 8.1 Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21
(d, J ) 8.0 Hz, 1H), 7.39 (d, J ) 1.5 Hz, 1H), 7.62 (d, J ) 8.4
Hz, 2H); LC-MS m/z 570.5 [MH]+, tR 5.45 min. Anal. (C31H41
Cl2N5O‚1/3H2O) C, H, N.
-
Refer en ces
(1) The Melanocortin Receptors; Cone, R. D., Ed.; Humana Press
Inc.: Totwa, NJ , 2000.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(dipr opylam in o)m eth yl]am in o}ben zam ide (19): white solid,
62 mg (75%); 1H NMR (300 MHz, CDCl3) δ 0.90 (t, J ) 6.3 Hz,
6H), 0.93-1.26 (m, 4H), 1.50-1.68 (m, 8H) 1.84 (m, 2H), 3.05
(t, J ) 6.6 Hz, 2H), 3.13 (t, J ) 7.5 Hz, 4H), 3.52 (brs, 1H),
3.69 (dt, J ) 7.0, 6.3 Hz, 2H), 6.11 (t, J ) 5.7 Hz, 1H), 6.80 (d,
J ) 8.4 Hz, 2H), 7.18 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J )
8.0 Hz, 1H), 7.39 (d, J ) 1.5 Hz, 1H), 7.69 (d, J ) 8.4 Hz, 2H);
LC-MS m/z 517.3 [MH]+, tR 7.38 min. Anal. (C28H38Cl2N4O)
C, H, N.
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Munzert, G.; Watson, S. J .; DelValle, J .; Yamada, T. Molecular
cloning of a novel melanocortin receptor. J . Biol. Chem. 1993,
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N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(3,5-diflu or oben zylam in o)m eth yl]am in o}ben zam ide (20):
1
white solid, 18 mg (20%); H NMR (300 MHz, CDCl3) δ 1.0-
1.40 (m, 4H), 1.52-2.0 (m, 6H), 3.04 (t, J ) 7.2 Hz, 2H), 3.28
(brs, 1H), 3.68 (dt, J ) 6.9, 6.3 Hz, 2H), 3.74 (brs, 1H), 4.45 (s,
2H), 6.13 (t, J ) 6.0 Hz, 1H), 6.72 (m, 1H), 6.89 (m, 4H), 7.18
(dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz, 1H), 7.39 (d, J
) 1.2 Hz, 1H), 7.63 (d, J ) 8.5 Hz, 2H); LC-MS m/z 559.3
[MH]+, tR 7.55 min; HRMS (MALDI-FTMS) calcd for C29H30
Cl2F2N4O 559.1837, found 559.1822.
-
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(2-a m in o-2-m eth ylp r op yla m in o)m eth yl]a m in o}ben za m -
id e (21): white solid, 37 mg (46%); 1H NMR (300 MHz, CDCl3)
δ 1.06-1.42 (m, 10H), 1.54-1.74 (m, 4H), 1.92-2.03 (m, 2H),
3.0-3.09 (m, 4H), 3.43 (brs, 1H), 3.68 (dt, J ) 6.9, 6.3 Hz, 2H),
6.12 (t, J ) 5.7 Hz, 1H), 6.90 (d, J ) 8.4 Hz, 2H), 7.18 (dd, J
) 8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz, 1H),7.39 (d, J ) 1.8
Hz, 1H), 7.62 (d, J ) 8.4 Hz, 2H); LC-MS m/z 504.4 [MH]+,
tR 5.35 min. Anal. (C26H35Cl2N5O‚1/3H2O) C, H, N.
(6) Gantz, I.; Miwa, H.; Konda, Y.; Shimoto, Y.; Tashiro, T.; Watson,
S. J .; DelValle, J .; Yamada, T. Molecular cloning, expression,
and gene localization of a fourth melanocortin receptor. J . Biol.
Chem. 1993, 268, 15174-15179.
(7) Labbe, O.; Desarnaud, F.; Eggerickx, D.; Vassart, G.; Parmentier,
M. Molecular cloning of a mouse melanocortin 5 receptor gene
widely expressed in peripheral tissues. Biochemistry 1994, 33,
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Pelleymounter, M. A.; Dekoning, J .; Baetscher, M.; Cone, R. D.
A unique metabolic syndrome causes obesity in the melanocor-
tin-3 receptor-deficient mouse. Endocrinology 2000, 141, 3518-
3521. (b) Chen, A. S.; Marsh, D. J .; Trumbauer, M. E.; Frazier,
E. G.; Guan, X. M.; Yu, H.; Rosenblum, C. I.; Vongs, A.; Feng,
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obesity syndrome. Nature 1997, 385, 165-168. (b) Heisler, L.
K.; Cowley, M. A.; Tecott, L. H.; Fan, W.; Low, M. J .; Smart, J .
L.; Rubinstein, M.; Tatro, J . B.; Marcus, J . M.; Holstege, H.; Lee,
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(p yr r olid in -3-yla m in e)m et h yl]a m in o}b en za m id e (22):
white solid, 78 mg (97%); 1H NMR (300 MHz, CDCl3) δ 0.98-
1.30 (m, 4H), 1.50-1.72 (m, 4H), 1.90 (m, 2H), 2.06 (m, 1H),
3.00 (m, 1H), 3.04 (t, J ) 6.9 Hz, 2H), 3.29 (brs, 1H), 3.35 (m,
1H), 3.44-3.63 (m, 3H), 3.69 (dt, J ) 6.6, 6.3 Hz, 2H), 3.87
(brs, 1H), 6.14 (t, J ) 6.0 Hz, 1H), 6.82 (d, J ) 9.0 Hz, 2H),
7.18 (dd, J ) 8.0, 1.8 Hz, 1H), 7.21 (d, J ) 8.0 Hz, 1H), 7.39
(d, J ) 1.8 Hz, 1H), 7.58 (d, J ) 9.0 Hz, 2H); LC-MS m/z
502.3 [MH]+, tR 5.32 min. Anal. (C26H33Cl2N5O‚1/3H2O) C, H,
N.
N-[2-(2,4-Dich lor op h en yl)eth yl]-4-{[cycloh exylim in o-
(3-m eth yla m in o-1-p yr r olid in yl)m eth yl]a m in o}ben za m -
id e (23): white solid, 14 mg (17%); 1H NMR (300 MHz, CDCl3)

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J M0400496