Design and synthesis of 3-phenyltetrahydronaphthalenic derivatives as new selective MT2 melatoninergic ligands. Part II

Article abstract of DOI:10.1016/j.bmc.2009.03.023

Following our studies of the melatoninergic receptors, we have developed new tetrahydronaphthalenic derivatives of melatonin that have been tested as selective melatonin receptors ligands. Regarding the role of the phenyl substituent to obtain selective l

Full text of DOI:10.1016/j.bmc.2009.03.023

Bioorganic & Medicinal Chemistry 17 (2009) 2963–2974
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Design and synthesis of 3-phenyltetrahydronaphthalenic derivatives as new
selective MT2 melatoninergic ligands. Part II
Sophie Durieux a, Angéline Chanu a, Christophe Bochu b, Valérie Audinot c, Sophie Coumailleau c,
Jean A. Boutin c, Philippe Delagrange d, Daniel H. Caignard d, Caroline Bennejean d, Pierre Renard d,
Daniel Lesieur a, Pascal Berthelot a, Saïd Yous a,
*
a Laboratoire de Chimie Thérapeutique (EA 1043), Université Lille Nord de France, Faculté des Sciences Pharmaceutiques et Biologiques, BP 83, 59006 Lille Cedex, France
b Laboratoire d’Application de Résonance Magnétique Nucléaire, Université Lille Nord de France, Faculté des Sciences Pharmaceutiques et Biologiques, BP 83, 59006 Lille Cedex, France
c Division de Pharmacologie Moléculaire et Cellulaire, Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, France
d Département des Sciences Expérimentales, Institut de Recherches Servier, 11 rue des Moulineaux, 92150 Suresnes, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Following our studies of the melatoninergic receptors, we have developed new tetrahydronaphthalenic
derivatives of melatonin that have been tested as selective melatonin receptors ligands. Regarding the
role of the phenyl substituent to obtain selective ligands, modulation of selectivity and activity have been
achieved by modifications of the acyl group and substitutions on the phenyl ring. Ten of the seventeen
evaluated derivatives have MT2 receptor affinity similar to that of melatonin. Moreover, we have
achieved remarkable MT2 selectivity over MT1 (selectivity >100) and have been able to further extend
the RSA of the tetrahydrophthalenic series. However, the compounds presented here display partial ago-
nist or antagonist behavior instead of full agonist.
Received 23 January 2009
Revised 5 March 2009
Accepted 11 March 2009
Available online 18 March 2009
Keywords:
Melatonin
Selective antagonists
MT2 receptors
Tetralins
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
and with MT2/MT1 selectivity ratios higher than one hundred.
The most interesting compounds belong to the N-(substituted-ani-
Melatonin 1 (N-acetyl-5-methoxytryptamine) is a tryptophan-
derived hormone characterized by a circadian rhythm of secre-
tion1,2 with peak levels occurring during the period of darkness.
Its activity is mediated through two high-affinity G-protein cou-
pled receptors named MT1 and MT2.3,4 Whereas it is known that
MT1 and MT2 receptors are expressed both centrally (suprachias-
matic nucleus, cortex, pars tuberalis, etc.) and peripherally (kidney,
adipocytes, retina, blood vessels, etc.),5 the physiological roles of
these receptors are not yet fully defined. There is evidence that
MT1 receptors might be implicated in the sleep promoting effects
of melatonin6,7 and in mediating vasoconstriction in rat caudal ar-
tery,8 whereas MT2 receptors appear to play a major role in the
resynchronizing activity of melatonin6,9 and in mediating vasodila-
tation in rat caudal artery.
These last years, several series of melatonin MT2 receptor li-
gands have been described (Chart 1) like indole 2,10 tetralin 310
and benzofuran 4.11 Recently, 512 has been reported having a bind-
ing affinity similar to melatonin at the MT2 receptor and a good
MT2 over MT1 selectivity (S = 763). The (E)-propenyl derivative
613 was a potent MT2 ligand, with affinities as high as melatonin,
linoethyl)amide series 7,14 which are highly selective antagonists,
with MT2 binding affinities greater than melatonin 1. Even if in this
previous series of molecules, we reached one of our aims, that is, to
obtain selective ligands, we did not obtain selective agonist for MT2
receptor subtype. Indeed, most of the ligands were partial agonists
and only two of them were full antagonists. This kind of selective
MT2 antagonist are already available and the most used in pharma-
cology is 4P-PDOT.15 MT2 receptor subtype full selective agonist
are still required as a pharmacological tool. Indeed, as mentioned
above the MT2 melatonin receptor subtype is probably involved
in the resynchronizing effect of melatonin. This hypothesis came
from studies performed with a combination of melatonin and 4P-
PDOT, a selective MT2 antagonist.6 The first results obtained with
transgenic mice MTÀ2 =À confirmed this hypothesis. Nevertheless,
when the same kind of studies was performed on MTÀ1 =À, the story
seems more complicated.7,15 Therefore, selective MT2 agonist are
still needed to selectively stimulate the MT2 receptor.
In previous studies, we reported the synthesis and the struc-
ture–selectivity relationships of a novel series of potent selective
MT2 antagonists.16 Indeed, introduction of a phenyl substituent
in the 3-position of the tetralin ring (8 and 9) decreased the MT1
but maintains the MT2 binding affinity, strongly suggesting the
importance of such a phenyl substituent to achieve MT2 selectivity.
* Corresponding author. Tel.: +33 3 2096 4375; fax: +33 3 2096 4913.
E-mail address: said.yous@univ-lille2.fr (S. Yous).
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.03.023

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S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
NHCOCH3
NHCOCH3
O
N
H
N
H
2 : Luzindole
1 : Melatonin
NHCOCH3
O
NHCOCH2CH3
O
O
4
3 : 4P-PDOT
O
NHCOCH3
NHCOcBu
O
6
OH
5
O
NHCOR
O
NHCOCH3
N
8 : R = Me
9 : R = c-Bu
7
O
Chart 1. Chemical structures of melatonin and some representative MT2 selective ligands.
Furthermore, when the methyl group of the acetamide was re-
placed the MT1/MT2 selectivity ratio was enhanced.
diates 28 and 29 were synthesized from methoxybenzene accord-
ing to a previously described procedure.18 Friedel-Crafts acylation
reaction gave the ketones 19–21. Subsequently, those ketones
were reacted with methyl bromoacetate in the presence of sodium
hydride in DMF and the crude esters were saponified by heating in
a 3 M NaOH solution to produce the acids 22–24. Selective reduc-
tion of the ketonic group of compounds 22–24 was achieved by
treatment with triethylsilane/trifluoroacetic acid19 to afford com-
pounds 25–27 which were cyclized to the corresponding tetralones
28 and 29 by heating in polyphosphoric acid. In these conditions,
the cyclization of compound 27 afforded exclusively indanone 30.
The tetralones 28 and 29 were cyanomethylated by a Horner-
Emmons olefination20 with diethyl cyanomethylphosphonate to
give nitriles 31 and 32. Compound 31 was hydrogenated in the
presence of Raney nickel in acetic anhydride to give, after frac-
tional recrystallization, the ( )-cis isomer of diacetamide 33. The
primary amine 34 was prepared from the nitrile 32 by hydrogena-
tion in the presence of Raney nickel in a NH3-saturated ethanol
solution, and was isolated as the hydrochloride salt after treatment
with gaseous HCl in ether. The amide 35 was then obtained in a bi-
phasic medium by treatment with cyclobutanecarboxylic acid
chloride in the presence of K2CO3.
Considering the role of the phenyl substituent, the tetrahydro-
naphthalenic compound 8 was selected as a starting point to at-
tempt the synthesis of highly selective MT2 ligands of higher
selectivity. The acyl group, the substitutions on the phenyl and
the length of the spacer were independently modulated as re-
ported in the present work.
We report here the synthesis and the structure–selectivity rela-
tionships of new tetrahydronaphthalenic MT2 ligands.
2. Results and discussion
2.1. Chemistry
The synthetic pathway for compounds 11–18 is outlined in
Scheme 1. Starting from 2-(7-methoxy-3-phenyl-1,2,3,4-tetra-
hydronaphthalen-1-yl)ethylamine hydrochloride (10),15 the N-acyl
derivatives 11–16 were obtained through two routes: (i) by treat-
ment with the appropriate acid chlorides in the presence of K2CO3
as base17 (11–15) and (ii) by a peptide coupling reaction type with
vinylacetic acid in the presence of EDCI (16).
Substitution of the bromine atom of 13 with sodium iodide in
acetone afforded the iodo derivative 17. The pyrrolidinone 18
was obtained by cyclization of the chlorobutyramide 14 with
EtONa in DMF. Compounds 33–35 were obtained following the
synthetic route described in Scheme 2. The key tetralone interme-
Amide 38 was synthesized from agomelatine21 according to the
route depicted in Scheme 3. Bromination of agomelatine using bro-
mine in acetic acid led to the 3-bromo derivative 36.12 This com-
pound was coupled with 3-methoxyphenyl boronic acid under
Suzuki conditions22 in the presence of palladium acetate to afford

S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
2965
CH3
O
NHCOR1
CH3
O
NHCOCH2I
CH3
O
NH2, HCl
a
c
13, R1 = CH2Br
11-15
17
10
14, R1 = (CH2)3Cl
d
b
O
CH3
O
N
CH3
O
NHCOCH2CH=CH2
18
16
Scheme 1. Synthesis of compounds 11–18. Reagents: (a) R1COCl, K2CO3, CHCl3/H2O; (b) (i) NaOH, H2O, (ii) H2C@CHCH2COOH, EDCI, TEA, CH2Cl2; (c) KI, acetone; (d) (i) EtONa,
EtOH, (ii) DMF.
compound 37. Partial reduction of the naphthalenic ring with lith-
ium in liquid ammonia gave after fractional recrystallization the
( )-cis isomer of compound 38.
The intrinsic activity of the most interesting compounds
(selectivity ratio higher than 50 and Ki less than to 10 nM) has
been evaluated only on the MT2 receptor, due to their weak
affinities for the MT1 subtype. The results are shown in Table
The synthetic routes to the compounds bearing amidomethyl
43 or amidopropyl side chain 48 are shown in Scheme 4. Alkaline
hydrolysis followed by a catalytic (Pd–C) hydrogenation of com-
pound 39,14 afforded after recrystallization from ethanol, the ( )-
cis isomer of acid 40. Activation of the carboxylic acid function of
40 with ethyl chloroformate and subsequent reaction with sodium
azide gave the azide 41. Curtius degradation of this azide followed
by acidic hydrolysis provided amine hydrochloride 42, which was
acetylated in standard conditions to afford acetamide 43.
Esterification of acid 40 with absolute ethanol in the presence of
thionyl chloride gave the ethyl ester 44, which was converted to
the cyanoethyl compound 47 via a three steps sequence: lithium
aluminium hydride reduction of the ethoxycarbonyl group, mesy-
lation of the resulting alcohol, and cyanation using potassium cya-
nide in DMSO. Finally, Raney nickel-catalyzed hydrogenation of 47
in acetic anhydride provided acetamide 48.
2. The [35S]-GTP
cS binding assay used to determine the func-
tional activity of the compounds was performed using Chinese
Hamster Ovarian (CHO) cell lines stably expressing the human
MT2 receptors. An agonist stimulates the [35S]-GTP
cS binding,
and this stimulation is proportional to the efficacy and intrinsic
activity of the molecule. By convention, the natural ligand mela-
tonin has an efficacy (Emax) of 100%. Full agonists stimulate [35S]-
GTPcS binding with a maximum efficacy, similar to that of mel-
atonin. If the Emax is between 30% and 70%, the compound is
considered as a partial agonist, whereas if it is less than 30%,
the compound is considered as an antagonist. In this last case,
the antagonism potency (KB) is determined against 30 or 3 nM
melatonin for MT1 or MT2, respectively.
(a) Variations of the acyl group on the C-1 side chain:
The key intermediates in the synthetic route to 2-phenyl tetra-
lin (53) and 2-benzyl tetralin (54) were the corresponding previ-
ously described tetralones 4923 and 5024 (Scheme 5). A Horner–
Emmons reaction on these ketones using sodium hydride and
diethyl cyanomethylphosphonate in anhydrous tetrahydrofuran
gave nitriles 51 and 52. These nitriles were hydrogenated in the
presence of Raney nickel in acetic anhydride to give, after frac-
tional recrystallization, the ( )-cis isomer of the N-acetyl deriva-
tives 53 and 54.
(I) The homologation of the methyl group of 8 for ethyl (com-
pound 11) or propyl (compound 12) causes a slight decrease in
MT1 affinity with a slight increase in MT2 affinity, leading to ratios
of threefold (281) and fivefold higher (350), respectively.
(II) The introduction of a terminal vinyl group (15 and 16)
induces a slight decrease in selectivity by comparison with their
saturated counterparts (11 and 12). The vinyl moiety in 15 leads
to a nearly conserved MT affinities, whereas the allyl group in 16
causes a slight decrease both binding affinities.
(III) The introduction of a halogenated alkyl side chain shows the
effect of a bulky group. A chloropropyl group, such as that in 14 is
too bulky to achieve a good MT2 affinity (90-fold decrease vs its
non-halogenated counterpart), but its MT1 affinity decreases by
about 30 times, leading to a threefold lower selectivity. Further-
more, the iodomethyl group in 17 causes a 15-fold decrease in
its MT1 affinity and only a threefold decrease in its MT2, resulting
to a sevenfold increase in selectivity compared to 8. A slightly
smaller group, such as bromomethyl 13, causes a sixfold increase
in selectivity (S = 426). In fact, its MT1 affinity is 40-fold lower than
8, whereas its MT2 affinity is only threefold lower.
(IV) The cyclization of the amide group as in pyrolidinone 18
induces sharp decreases in MT1 (124-fold) and MT2 (20-fold) affin-
ities, leading to a fivefold increase in selectivity (S = 376), thus sug-
gesting that hydrogen bonding should be more important for MT1
affinity than for MT2.
2.2. Pharmacology
Chemical structures, binding affinities and MT1/MT2 selectivity
ratios of the new tetralinic compounds are reported in Table 1.
These compounds were evaluated for their binding affinity for
membranes prepared from human MT1 and MT2 receptors stably
transfected in Human Embryonic Kidney (HEK 293) cells or Chi-
nese Hamster Ovarian (CHO) cells, using 2-[125I]iodomelatonin as
radioligand. At each receptor, binding affinities were checked for
the 54 selective and non-selective newly synthesized molecules,
either using the transfected HEK 293 or the CHO cell lines. The cor-
relation between affinities in HEK 293 and CHO cells is highly sig-
nificant (r = 0.98)25 for both receptors. This high correlation allows
the direct comparison of the affinities to draw structure–activity
relationships.

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S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
CH3
O
CH3
O
N°
R2
R2
+
X
a
19
20
21
NO2
CF3
OCH3
R2
O
O
X = OH or Cl
b
CH3
O
N°
R2
CO2H
NO2
CF3
OCH3
22
23
24
R2
O
c
CH3
O
O
CH3
O
N°
R2
CO2H
a
25 NO2
R2
26
R = OCH3
OCH3
CF3
27
OCH3
30
a1
R =NO2, CF3
O
CH3
O
N°
28
R2
R2
NO2
CF3
29
d
CN
CH3
O
CH3
O
NH2 ; HCl
N°
31
R2
f
NO2
CF3
R2
CF3
32
R2 =CF3
34
g
R2 = NO2
e
CH3
O
NHCO
CH3
O
NHCOCH3
CF3
NHCOCH3
35
33
Scheme 2. Synthesis of compounds 34 and 35. Reagents: (a) (a1) Polyphosphoric acid; (a2) AlCl3, DMF; (b) (i) BrCH2COOCH3, NaH, DMF, (ii) NaOH, MeOH, water, (iii) 6 M HCl;
(c) (Et)3SiH, CF3COOH; (d) (C2H5O)2P(O)CH2CN, NaH, THF; (e) H2, Raney nickel, (CH3CO)2O; (f) H2, Raney nickel, NH3 (g), EtOH; (g) c-C4H7COCl, K2CO3, CHCl3/H2O.
CH3
O
NHCOCH3
CH3
O
NHCOCH3
Br
a
b
36
Agomelatine
CH3
O
NHCOCH3
CH3
O
NHCOCH3
c
OCH3
OCH3
38
37
Scheme 3. Synthesis of compound 38. Reagents: (a) Br2, AcOH; (b) 3-OCH3C6H4B(OH)2; (c) Li, NH3.

S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
2967
CON3
COOH
CH3
O
CN
CH3
O
CH3
O
a
b
41
40
39
c
e
COOC2H5
NH , HCl
2
CH3
O
CH3
O
44
42
f
d
NHCOCH
3
CH3
O
CH3
O
R
45, R = OH
46, R = OMs
47, R = CN
g
h
43
i
NHCOCH3
CH3
O
48
Scheme 4. Synthesis of compounds 43, 44. Reagents: (a) (i) NaOH, MeOH, H2O, (ii) 6 M HCl, (iii) H2, Pd–C, EtOH; (b) (i) ClCOOEt, N(Et)3, acetone, (ii) NaN3, H2O; (c) (i) Toluene,
reflux, (ii) 6 M HCl; (d) CH3COCl, K2CO3, CHCl3/H2O; (e) SOCl2, EtOH; (f) LiAlH4, THF; (g) CH3SO2Cl, N(Et)3, CH2Cl2; (h) KCN, DMSO; (i) H2, Raney nickel, (CH3CO)2O.
CN
CH3
O
O
CH3
O
CH3
O
NHCOCH3
R3
R3
R3
b
a
R3
C6H5
CH2C6H5
R3
R3
N°
N°
N°
C6H5
CH2C6H5
C6H5
CH2C6H5
49
50
51
52
53
54
Scheme 5. Synthesis of compounds 53, 54. Reagents: (a) (C2H5O)2P(O)CH2CN, NaH, THF; (b) H2, Raney nickel, (CH3CO)2O.
Introduction of a phenyl (53) or a benzyl (54) group at the 2-posi-
(b) Substitutions of the phenyl in position 3
Previously reported results on benzofuran series11 led us to con-
sider various meta-substitutions of the phenyl in position 3. Adding
a methoxy group (38) leads to a fourfold increase in selectivity, by
decreasing 10-fold the MT1 affinity, whereas the MT2 affinity is
only doubled. On the contrary, a trifluoromethyl group (35) causes
a threefold decrease in MT2 affinity versus the unsubstituted phe-
nyl, 9, but a sixfold increase in MT1 affinity, resulting in a 20-fold
decrease in selectivity.
tionof thetetralinringreducesMT1 affinityand, to ahigherextent, in
theMT2 affinity. This result confirmstheimportanceof a phenylsub-
stituent at the 3-postion of the tetralin ring in achieving MT2
selectivity.
The intrinsic activities of the most interesting compounds in
this report are shown in Table 2. Almost all the tested compounds
act as MT1 antagonists and as MT2 partial agonists or antagonists.
3. Experimental
3.1. Chemistry
(c) Length of the spacer
The number of carbon atoms between the tetralin and the
amide has been modified. With 1 carbon in between compound
43, there is a slight increase in MT1 affinity, but MT2 affinity is de-
creased. This gives a fourfold lower selectivity than 8. With 3 car-
bons 48, the selectivity is unchanged in respect with 8, but the
affinities for both subtypes are somewhat lower.
Melting points were determined on a Büchi SMP-20 capillary
apparatus and are uncorrected. IR spectra were recorded on a Vector
22Brukerspectrometer. 1HNMRspectrawererecordedonanAC300
Bruker spectrometer. Chemical shifts are reported in d units (parts
(d) Substitution at 2-position of the tetralin ring

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S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
Table 1
MT1 and MT2 receptor binding affinities of tetralinic compounds: 11–18, 34, 35, 38, 43, 48
NHCOR1
n
NHCOCH3
CH3
O
CH3
O
CH3
O
NHCOCH3
R2
11-18, 34-35, 38, 43, 48
53
54
Compound
R1
R2
n
Ki SEM (nM)
Ki SEM (nM)
S
MT1
MT2
MT1/MT2
Melatonin 1
4P-PDOT 3
8
9
—
—
CH3
c-C4H7
C2H5
n-C3H7
CH2Br
C3H6Cl
CH@CH2
CH2CH@CH2
CH2I
NHCOR1=pyrrolidinone
CH3
c-C4H7
CH3
CH3
CH3
—
—
—
—
0.14 0.03
108 15
20.5 8.70
439 124
0.41 0.04
0.96 0.23
0.31 0.094
2.23 0.5
0.16 0.05
0.10 0.01
1.9 0.2
0.34
112
66
—
2
2
2
2
2
2
2
2
2
2
2
2
2
1
3
—
—
H
H
H
H
H
H
H
H
H
H
191
281
350
426
110
220
192
299
376
>141
10
278
15
65
> 29
44
11
12
13
14
15
16
17
18
34
35
38
43
48
53
54
45
35
6
3
809 232
981 50
8.9 1.5
33
2
0.15 0.02
0.66 0.17
1.04 0.31
6.6 0.8
71 27
6.0 0.5
0.89 0.13
0.88 0.01
0.78 0.18
127 31
311 45
2480 435
>1000
NHCOCH3
CF3
OCH3
H
H
—
61
247 30
13
5
3
51 19
>1000
>1000
173
6
—
—
52 25
Concentration–response curves were analyzed by non-linear regression comparing a one-site and a two sites analysis. All the curves were found to be monophasic with a Hill
number close to unity (not shown). Binding affinities (nM) are expressed as mean Ki S.E.M of at least 3 independent experiments. The selectivity ratio between MT1 and MT2
receptors is calculated for compound.
Table 2
Activity values
Compound
MT1
MT2
EC50 SEM (nM)
Emax SEM (%)
KB SEM (nM)
EC50 SEM (nM)
Emax SEM (%)
KB SEM (nM)
Melatonin 1
2.24 0.35
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
110
<10
<10
<10
<10
<10
<10
<10
2
nd
0.49 0.04
1.28 0.39
Inactive
0.41 0.03
0.74 0.03
Inactive
104
37.4 3.0
<10
57
55
<10
<10
<10
6
nd
8a
126 24
105 13
32.1 11
43.6 17.9
40.6 8.8
nd
0.53 0.18
2.75 0.9
>10 lM
0.52 0.001
6.32 0.38
nd
9a
12
15
18
38
43
2
1
Inactive
Inactive
nd
nd
Concentration–response curves were analyzed by non-linear regression. Agonist potency was expressed as EC50 S.E.M. (nM) while the maximal efficacy, Emax S.E.M. was
expressed as a percentage of that observed with melatonin 1 M (=100%). Antagonist potency to inhibit the effect of melatonin (30 or 3 nM respectively for MT1 and MT2
l
receptors) was expressed as KB S.E.M. Data are mean of at least 3 independent experiments.
Inactive: no dose–response effect and nd: not determined.
a
Ref. 16.
per million) relative to (Me)4Si. Elemental analyses for final sub-
stances were performed by CNRS Laboratories (Vernaison, France).
Obtained results were within 0.4% of the theoretical values.
For all final compounds, fractional recrystallization in adequate
solvent gave the ( )-cis isomer. The relative configuration of the
tetralinic cyclic carbons (C1 and C3) was assigned through ROESY
(mixing time: 1 s). The observed cross-peaks between H1 and H3
and the lack of cross-peaks between H3 and the CH2 of the ethyl side
chain were unambiguously indicative of the cis-arrangement.15
1-yl)ethylamine hydrochloride (1.1 g, 3.5 mmol), in 60 mL of water
and 80 mL of chloroform. After stirring for 10 min at 0 °C, 4.0 mmol
of the appropriate acid chloride was added dropwise at this tem-
perature. The reaction mixture was stirred at room temperature
for 2 h. The organic phase was separated, washed with a 1 M HCl
solution and water, dried over MgSO4, filtered and concentrated
under reduced pressure to give the desired amide 11–15.
3.2.1. ( )-cis-N-[2-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethyl]propionamide (11)
3.2. General procedure for the preparation of amides (11–15)
Recrystallized from isopropyl ether; yield 43%; mp 127–129 °C;
IR (neat, cmÀ1) 3300, 1641; 1H NMR (300 MHz, DMSO-d6) d 0.97 (t,
J = 7.7 Hz, 3H), 1.52–1.64 (m, 2H), 2.01–2.14 (m, 4H), 2.76–2.86 (m,
3H), 2.98 (m, 1H), 3.11 (m, 2H), 3.72 (s, 3H), 6.70 (dd, J = 8.5 and
Potassium carbonate (1.45 g, 10.5 mmol) was added to a solu-
tion of cis-2-(7-methoxy-3-phenyl-1,2,3,4-tetrahydronaphthalen-

S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
2969
2.2 Hz, 1H), 6.84 (d, J = 2.2 Hz, 1H), 6.99 (d, J = 8.5 Hz, 1H), 7.22 (m,
1H), 7.31–7.35 (m, 4H), 7.77 (br s, 1H). Anal. Calcd for C22H27NO2:
C, 78.30; H, 8.06; N, 4.15. Found: C, 78.07; H, 8.13; N, 4.27.
2H), 5.89 (m, 1H), 6.71 (dd, J = 8.4 and 2.2 Hz, 1H), 6.85 (d,
J = 2.2 Hz, 1H), 7.00 (d, J = 8.4 Hz, 1H), 7.23 (m, 1H), 7.28–7.37
(m, 4H), 7.89 (br s, 1H). Anal. Calcd for C23H27NO2: C, 79.05; H,
7.79; N, 4.01. Found: C, 78.67; H, 7.86; N, 4.17.
3.2.2. ( )-cis-N-[2-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethyl]butyramide (12)
3.2.7. ( )-cis-N-[2-(7-Methoxy-3-phenyl-1,2,3,4-
Recrystallized from isopropyl ether; yield 41%; mp 119–121 °C;
IR (neat, cmÀ1) 3309, 1639; 1H NMR (300 MHz, DMSO-d6) d 0.84 (t,
J = 7,3 Hz, 3H), 1.55 (q, J = 7,3 Hz, 2H), 1.57–1.71 (m, 2H), 2.03 (t,
J = 7,3 Hz, 2H), 2.08–2.18 (m, 2H), 2.76–2.84 (m, 3H), 2.99 (m,
1H), 3.14 (m, 2H), 3.74 (s, 3H), 6.71 (dd, J = 8,4 and 2,2 Hz, 1H),
6.85 (d, J = 2,2 Hz, 1H), 7.01 (d, J = 8,4 Hz, 1H), 7.23 (m, 1H), 7.20–
7.27 (m, 4H), 7.83 (br s, 1H). Anal. Calcd for C23H29NO2: C, 78.60;
H, 8.32; N, 3.98. Found: C, 78.41; H, 8.44; N, 4.15.
tetrahydronaphthalen-1-yl)ethyl]iodoacetamide (17)
A solution of compound 13 (1 g, 2.5 mmol) in 40 mL of anhy-
drous acetone was treated with sodium iodide (0.45 g,
3.0 mmol). The mixture was refluxed for 2 h, cooled to room
temperature and filtered. Acetone was evaporated under reduced
pressure and the residue was crystallized from acetonitrile to
give 1.1 g (43% yield) of 17; mp 135–138 °C; IR (neat, cmÀ1
)
3288, 1643; 1H NMR (300 MHz, DMSO-d6) d 1.52–1.65 (m, 2H),
2.08–2.19 (m, 2H), 2.77–2.84 (m, 3H), 3.03 (m, 1H), 3.17 (m,
2H), 3.62 (s, 2H), 3.74 (s, 3H), 6.72 (dd, J = 8.3 and 2.4 Hz, 1H),
6.85 (d, J = 2.4 Hz, 1H), 7.01 (d, J = 8.3 Hz, 1H), 7.22 (m, 1H),
7.32–7.35 (m, 4H), 8.32 (br s, J = 5.2 Hz, 1H). Anal. Calcd for
C21H24INO2: C, 56.13; H, 5.38; N, 3.12. Found: C, 55.83; H,
5.32; N, 3.08.
3.2.3. ( )-cis-N-[2-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethyl]bromoacetamide (13)
Recrystallized from acetonitrile; yield 38%; mp 125–126 °C; IR
(neat, cmÀ1) 3291, 1650; 1H NMR (300 MHz, DMSO-d6) d 1.53–
1.71 (m, 2H), 2.07–2.18 (m, 2H), 2.77–2.84 (m, 3H), 2.99 (m, 1H),
3.17 (m, 2H), 3.73 (s, 3H), 3.83 (s, 2H), 6.71 (d, J = 8.5 Hz, 1H),
6.85 (s, 1H), 7.00 (d, J = 8.5 Hz, 1H), 7.22 (m, 1H), 7.28–7.36 (m,
4H), 8.35 (br s, 1H). Anal. Calcd for C21H24BrNO2: C, 62.69; H,
6.01; N, 3.48. Found: C, 62.61; H, 6.20; N, 3.63.
3.2.8. ( )-cis-N-[2-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethyl]pyrrolidin-2-one (18)
A solution of 14 (0.8 g, 2.0 mmol) in 10 mL of absolute ethanol
was added dropwise to a solution of sodium (0.08 g, 3.5 gr/at) in
30 mL of absolute ethanol. The mixture was stirred at room tem-
perature for 1 h, and then ethanol was evaporated under reduced
pressure. The residue was taken off with 40 mL of dimethylform-
amide and refluxed for 6 h. After cooling, the mixture was hydro-
lyzed with water and extracted with diethyl ether. The organic
phase was dried over MgSO4, filtered, and concentrated under re-
duced pressure. The residue was precipitated in petroleum ether
and recrystallized from isopropyl ether to give 0.38 g (38% yield)
of 18; mp 112–115 °C; IR (neat, cmÀ1) 1671; 1H NMR (300 MHz,
DMSO-d6) d 1.56–1.77 (m, 2H), 1.89 (m, 2H), 2.08–2.25 (m, 4H),
2.76–2.83 (m, 3H), 2.95 (m, 1H), 3.16 (m, 2H), 3.36 (m, 2H),
3.74 (s, 3H), 6.72 (d, J = 8.2 Hz, 1H), 6.89 (s, 1H), 7.01 (d,
J = 8.2 Hz, 1H), 7.23 (m, 1H), 7.31–7.36 (m, 4H). Anal. Calcd for
C23H27NO2: C, 79.05.13; H, 7.79; N, 4.01. Found: C, 78.67; H,
7.70; N, 4.12.
3.2.4. ( )-cis-4-Chloro-N-[2-(7-methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethyl] butyramide (14)
Recrystallized from acetonitrile; yield 45%; mp 114–117 °C; IR
(neat, cmÀ1) 3307, 1640; 1H NMR (300 MHz, DMSO-d6) d 1.52–
1.70 (m, 2H), 1.93 (m, 2H), 2.08–2.15 (m, 2H), 2.35 (t, J = 6,9 Hz,
2H), 2.76–2.84 (m, 3H), 3.00 (m, 1H), 3.16 (m, 2H), 3.63 (t,
J = 6,5 Hz, 2H), 3.74 (s, 3H), 6.71 (dd, J = 8,1 and 2,3 Hz, 1H), 6.86
(d, J = 2,3 Hz, 1H), 7.00 (d, J = 8,1 Hz, 1H), 7.22 (m, 1H), 7.31–7.35
(m, 4H), 7.94 (br s, 1H). Anal. Calcd for C23H28ClNO2: C, 71.58; H,
7.31; N, 3.63. Found: C, 71.55; H, 7.48; N, 3.79.
3.2.5. ( )-cis-N-[2-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethyl]vinylamide (15)
Recrystallized from isopropyl ether; yield 39%; mp 96–99 °C; IR
(neat, cmÀ1) 3266, 1655; 1H NMR (300 MHz, DMSO-d6) d 1.55–1.76
(m, 2H), 2.08–2.21 (m, 2H), 2.73–2.88 (m, 3H), 3.01 (m, 1H), 3.19
(m, 2H), 3.73 (s, 3H), 5.57 (dd, J = 9.9 and 1.9 Hz, 1H), 6.07 (dd,
J = 17.2 and 1.9 Hz, 1H), 6.22 (dd, J = 17.2 and 9.9 Hz, 1H), 6.73
(d, J = 8.3 Hz, 1H), 6.86 (s, 1H), 7.01 (d, J = 8.3 Hz, 1H), 7.24 (m,
1H), 7.28–7.37 (m, 4H), 8.15 (br s, 1H). Anal. Calcd for
C22H25NO2: C, 78.77; H, 7.51; N, 4.18. Found: C, 78.76; H, 7.50;
N, 4.21.
3.2.9. [1-(4-Methoxyphenyl)-2-(3-nitrophenyl]ethanone (19)
3-Nitrophenylacetic acid (27 g, 147 mmol) was added portion-
wise to a mixture of polyphosphoric acid (270 g) and anisole
(32 mL, 294 mmol) at 70 °C. After stirring at the same temperature
for 2 h, the mixture was cooled, poured into water and extracted
with ether. The organic phase was washed with a 5% K2CO3 solu-
tion then with water, dried over MgSO4, filtered, and concentrated
under reduced pressure to afford a residue which was recrystal-
lized from cyclohexane to give 39.87 g (85% yield) of 19; mp 57–
58 °C; IR (neat, cmÀ1) 1676; 1H NMR (300 MHz, DMSO-d6) d 3.85
(s, 3H), 4.58 (s, 2H), 7.08 (d, J = 8.9 Hz, 2H), 7.62 (t, J = 7.7 Hz,
1H), 7.72 (d, J = 7.7 Hz, 1H), 8.06 (d, J = 8.9 Hz, 2H), 8.12 (d,
J = 7.7 Hz, 1H), 8.18 (s, 1H).
3.2.6. ( )-cis-N-[2-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethyl]vinylacetamide (16)
A solution of vinylacetic acid (0.7 mL, 8.0 mmol) in 40 mL of
methylene chloride was stirred at À10 °C for 20 min. Then, trieth-
ylamine (0.61 g, 6.1 mmol) and EDCI (2.1 g, 11.0 mmol) were
added, and the mixture was stirred at À10 °C for 30 min. A solution
of
N-[2-(7-methoxy-3-phenyl-1,2,3,4-tetrahydronaphthalen-1-
yl)ethyl]ethylamine (10) (1.60 g, 5.3 mmol) in 10 mL of methylene
chloride was cooled at À10 °C and added dropwise. After 2 h of
stirring at room temperature, the reaction mixture was washed
with water, a 1 M HCl solution, water, a 10% NaOH solution, and
water until pH 7 was reached. The organic phase was dried over
MgSO4, filtered, and concentrated under reduced pressure. The res-
idue was precipitated in petroleum ether and recrystallized from
isopropyl ether to give 0.83 g (45% yield) of 16; mp 127–128 °C;
IR (neat, cmÀ1) 3297, 1645; 1H NMR (300 MHz, DMSO-d6) d 1.53–
1.72 (m, 2H), 2.06–2.19 (m, 2H), 2.73–2.83 (m, 3H), 2.87 (d,
J = 6.8 Hz, 2H), 2.99 (m, 1H), 3.14 (m, 2H), 3.73 (s, 3H), 5.07 (m,
3.2.10. [(1-(4-Methoxyphenyl)-2-(3-
trifluoromethylphenyl)]ethanone (20)
3-Trifluoromethylphenyl acetyl chloride (20 g, 90.0 mmol) was
added dropwise to aluminium chloride (18 g, 135 mmol) in anisole
(39 g, 360 mmol). After stirring for 2 h at room temperature, the
reaction mixture was poured into ice-water. The precipitate was
filtered and recrystallized from cyclohexane, affording 26.5 g
(70% yield) of 20; mp 94–96 °C; IR (neat, cmÀ1) 1665; 1H NMR
(300 MHz, DMSO-d6)
d 3.86 (s, 3H), 4.51 (s, 2H), 7.08 (d,
J = 9.0 Hz, 2H), 7.56–7.60 (m, 3H), 7.66 (s, 1H), 8,06 (d, J = 9.0 Hz,
2H).

2970
S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
3.2.11. [(1-(4-Methoxyphenyl)-2-(3-methoxyphenyl)]ethanone
(21)
3.2.16. [4-(4-Methoxyphenyl)-3-(3-
trifluoromethylphenyl)]butyric acid (26)
Starting from 3-methoxyphenyl acetic acid and anisole, com-
pound 17 was obtained as colorless oil according to the procedure
described for 19. Purified by column chromatography (SiO2, ethyl
acetate/cyclohexane (1:9)); oil; yield 61%; IR (neat, cmÀ1) 1668;
1H NMR (300 MHz, DMSO-d6) d 3.76 (s, 3H), 3.85 (s, 3H), 4.31 (s,
2H), 6.77–7.00 (m, 5H), 7.25 (t, J = 7.7 Hz, 1H), 8.01 (d, J = 7.7 Hz,
2H).
Starting from 23, compound 26 was obtained according to the
procedure described for 25. Recrystallized from cyclohexane; yield
87%; mp 99–101 °C; IR (neat, cmÀ1) 3110–2850, 1700; 1H NMR
(DMSO-d6) d 2.56–2.67 (m, 2H), 2.77–2.92 (m, 2H), 3.38 (m, 1H),
3.69 (s, 3H), 6.79 (d, J = 8.3 Hz, 2H), 7.00 (d, J = 8.3 Hz, 2H), 7.44–
7.57 (m, 4H), 12.12 (br s, 1H).
3.2.17. [4-(4-Methoxyphenyl)-3-(3-methoxyphenyl)]butyric
acid (27)
3.2.12. [4-(4-Methoxyphenyl)-4-oxo-3-(3-nitrophenyl)]butyric
acid (22)
Starting from 24, compound 27 was obtained according to the
procedure described for 25. Recrystallized from toluene; yield
96%; mp 147–150 °C; IR (neat, cmÀ1) 3100–2830, 1702; 1H NMR
(DMSO-d6) d 2.52 (m, 1H), 2.79–2.81 (m, 2H), 3.23 (m, 1H), 3.34
(m, 1H), 3.70 (m, 6H), 6.72–6.80 (m, 5H), 7.01 (d, J = 7.4 Hz, 2H),
7.16 (t, J = 7.4 Hz, 1H),12.01 (br s, 1H).
NaH (60% in mineral oil) (5.2 g, 130 mmol) was added portion-
wise to a cooled solution of methyl bromoacetate (12.4 mL,
130 mmol) and 19 (27.1 g, 100 mmol) in dry DMF (150 mL). The
reaction mixture was stirred at room temperature for 16 h and
then poured into ice-water. The aqueous phase was extracted with
ether and the organic layer was washed with water, aqueous
potassium bicarbonate solution, and concentrated under reduced
pressure. The residue was dissolved in 100 mL of methanol. After
addition of 100 mL of aqueous sodium hydroxide solution (20 g,
0.5 mol), the mixture was refluxed for 1 h and then extracted twice
with diethyl ether. The aqueous phase was acidified with 6 M HCl
and the precipitate was filtered and recrystallized from toluene to
3.2.18. 7-Methoxy-3-(3-nitrophenyl)-3,4-dihydro-2H-
naphthalen-1-one (28)
A mixture of 25 (9.5 g, 30 mmol) in polyphosphoric acid (95 g)
was stirred at 70 °C for 4 h. The reaction mixture was poured into
200 mL of ice-water and the precipitate was filtered, washed with
water and dried. Recrystallization from toluene gave 5.2 g (58%
yield) of 28; mp 123–124 °C; IR (neat, cmÀ1) 1679; 1H NMR
(DMSO-d6) d 2.78 (dd, J = 16.5 and 1.7 Hz, 1H), 3.03–3.29 (m, 3H),
3.61 (m, 1H), 3.81 (s, 3H), 7.21 (dd, J = 8.3 and 2.1 Hz, 1H), 7.34–
7.41 (m, 2H), 7.67 (t, J = 8.0 Hz, 1H), 7.91 (d, J = 7.8 Hz, 1H), 7.97
(m, 1H), 8.14 (dd, J = 8.0 and 1.0 Hz, 1H).
give 16.8 g (51% yield) of 22; mp 143–146 °C; IR (neat, cmÀ1
)
3065–2840, 1704, 1668; 1H NMR (DMSO-d6) d 2.69 (dd, J = 17.0
and 4.2 Hz, 1H), 3.19 (dd, J = 17.0 and 10.5 Hz, 1H), 3.80 (s, 3H),
5.42 (dd, J = 10.5 and 4.2 Hz, 1H), 7.00 (d, J = 8.5 Hz, 2H), 7.60 (t,
J = 7.9 Hz, 1H), 7.80 (d, J = 7.9 Hz, 1H), 8.02–8.10 (m, 3H), 8.26 (s,
1H), 12.37 (br s, 1H).
3.2.19. 7-Methoxy-3-(3-trifluoromethylphenyl)-3,4-dihydro-
2H-naphthalen-1-one (29)
3.2.13. [4-(4-Methoxyphenyl)-4-oxo-3-(3-
trifluoromethylphenyl)]butyric acid (23)
Starting from 26, compound 29 was obtained according to the
procedure described for 28. Recrystallized from petroleum ether;
yield 89%; mp 73–75 °C; IR (neat, cmÀ1) 1675; 1H NMR (DMSO-
d6) d 2.77 (dd, J = 17.3 and 1.7 Hz, 1H), 3.01–3.26 (m, 3H), 3.56
(m, 1H), 3.80 (s, 3H), 7.19 (dd, J = 8.3 and 2.9 Hz, 1H), 7.34–7.38
(d, J = 8.3 Hz, 1H), 7.40 (d, J = 2.9 Hz, 1H), 7.56–7.64 (m, 2H),
7.72–7.78 (m, 2H).
Starting from 20, compound 23 was obtained according to the
procedure described for 22. Recrystallized from cyclohexane; yield
40%; mp 86–88 °C; IR (neat, cmÀ1) 3060–2840, 1705, 1665; 1H
NMR (DMSO-d6) d 2.67 (dd, J = 17.0 and 4.5 Hz, 1H), 3.19 (dd,
J = 17.0 and 10.4 Hz, 1H), 3.80 (s, 3H), 5.35 (dd, J = 10.4 Hz and
4.5 Hz, 1H), 7.00 (d, J = 8.8 Hz, 2H), 7.50–7.60 (m, 2H), 7.66 (d,
J = 7.4 Hz, 1H), 7.77 (s, 1H), 8.06 (d, J = 8.8 Hz, 2H), 12.36 (br s, 1H).
3.2.20. 5-Methoxy-3-(4-methoxybenzyl)indan-1-one (30)
Starting from 27, compound 30 was obtained according to the
procedure described for 28. Recrystallized from ethanol; yield
49%; mp 89–91 °C; IR (neat, cmÀ1) 1693; 1H NMR (DMSO-d6) d
2.29 (dd, J = 13.6 and 3.0 Hz, 1H), 2.57–2.72 (m, 2H), 3.16 (dd,
J = 13.6 and 5.3 Hz, 1H), 3.60 (m, 1H), 3.73 (s, 3H), 3.85 (s, 3H),
6.86 (d, J = 8.7 Hz, 2H), 6.98 (dd, J = 8.7 and 1.1 Hz, 1H), 7.12 (d,
J = 1.1 Hz, 1H), 7.17 (d, J = 8.7 Hz, 2H), 7.91 (d, J = 8.7 Hz, 1H).
3.2.14. [4-(4-Methoxyphenyl)-4-oxo-3-(3-
methoxyphenyl)]butyric acid (24)
Starting from 21, compound 24 was obtained according to the
procedure described for 22. Recrystallized from toluene; yield
32%; mp 158–161 °C; IR (neat, cmÀ1) 3100–2840, 1702, 1672, 1H
NMR (DMSO-d6) d 2.58 (dd, J = 17.2 and 4.0 Hz, 1H), 3.14 (dd,
J = 17.2 and 10.6 Hz, 1H), 3.70 (s, 3H), 3.80 (s, 3H), 5.12 (dd,
J = 10.6 and 4.0 Hz, 1H), 6.78 (dd, J = 7.6 and 2.0 Hz, 1H), 6.87 (d,
J = 7.6 Hz, 1H), 6.94 (s, 1H), 6.99 (d, J = 8.6 Hz, 2H), 7.20 (t,
J = 7.6 Hz, 1H), 8.02 (d, J = 8.6 Hz, 2H), 12.31 (br s, 1H).
3.2.21. E-(7-Methoxy-3-(3-nitrophenyl)-3,4-dihydro-2H-
naphthalen-1-ylidene)acetonitrile (31)
A
solution of diethyl cyanomethylphosphonate (6.3 mL,
3.2.15. [4-(4-Methoxyphenyl)-3-(3-nitrophenyl)]butyric acid
(25)
40 mmol) in 30 mL of anhydrous THF was added dropwise to a stir-
red mixture of NaH (1.6 g, 40 mmol) (60% in mineral oil) and 50 mL
of anhydrous THF at À10 °C under N2. After 1 h, a solution of 28
(5.95 g, 20 mmol) in 60 mL of anhydrous THF was added dropwise
and the mixture was stirred at room temperature for 16 h. The
mixture was then poured into cold water and the solid was col-
lected by filtration, washed with water, and diethyl ether. Recrys-
tallization from ethanol gave 6.4 g (84%) of pure 31; mp 173–
174 °C; IR (neat, cmÀ1) 2202; 1H NMR (300 MHz, DMSO-d6) d
2.97–3.18 (m, 4H), 3.34 (m, 1H), 3.80 (s, 3H), 6.47 (s, 1H), 7.05
(d, J = 8.3 Hz, 1H), 7.23 (d, J = 8.3 Hz, 1H), 7.42 (s, 1H), 7.68 (t,
J = 7.3 Hz, 1H), 7.91 (d, J = 7.3 Hz, 1H), 8.15 (d, J = 7.3 Hz, 1H),
8.28 (s, 1H).
Triethylsilane (21 mL, 132 mmol) was added dropwise to a
solution of 22 (19.8 g, 60 mmol) in 80 mL of trifluoroacetic acid.
The reaction mixture was stirred vigourously at room temperature
for 48 h. Trifluoroacetic acid was then evaporated under reduced
pressure and the residue was taken off with petroleum ether.
The resulting precipitate was filtered and recrystallized from tolu-
ene to give 13.8 g (73% yield) of 25; mp 137–139 °C; IR (neat, cmÀ1
)
3100–2850, 1704; 1H NMR (DMSO-d6) d 2.64 (m, 2H), 2.88 (m, 2H),
3.45 (m, 1H), 3.68 (s, 3H), 6.78 (d, J = 8.5 Hz, 2H), 7.02 (d, J = 8.5 Hz,
2H), 7.55 (t, J = 7.6 Hz, 1H), 7.69 (d, J = 7.6 Hz, 1H), 8.04 (d,
J = 7.6 Hz, 1H), 8.08 (s, 1H), 12.14 (br s, 1H).

S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
2971
3.2.22. E-(7-Methoxy-3-(3-trifluoromethylphenyl)-3,4-dihydro-
2H-naphthalen-1-ylidene)acetonitrile (32)
J = 2.4 Hz, 1H), 7.83 (d, J = 9.0 Hz, 1H), 8.00 (d, J = 2.0 Hz, 1H),
8.14 (br s, 1H).
Starting from 29, compound 32 was obtained according to the
procedure described for 31. Recrystallized from ethanol/water
(1:1); yield 62%; mp 107–108 °C; IR (neat, cmÀ1) 2210; 1H NMR
(DMSO-d6) d 2.98–3.25 (m, 5H), 3.80 (s, 3H), 6.44 (s, 1H), 7.01
(dd, J = 8.3 and 2.1 Hz, 1H), 7.20 (d, J = 8.3 Hz, 1H), 7.40 (d,
J = 2.1 Hz, 1H), 7.54–7.77 (m, 4H).
3.2.27. N-[2-(3-(3-Methoxyphenyl)-7-methoxynaphthalen-1-
yl)ethyl]acetamide (37)
A solution of 36 (1.2 g, 0.004 mol), 3-methoxyphenylboronic
acid (0.61 g, 4.0 mmol), palladium acetate (0.1 g), potassium car-
bonate (1.0 g, 7.0 mmol) and tetrabutylammonium bromide
(15 mg) in 20 mL of dioxane and 10 mL of water was refluxed for
4 h under N2. After cooling and filtration, the filtrate was taken
with ethyl acetate and washed with water. The organic phase
was dried over MgSO4, filtered and concentrated under reduced
pressure. The residue was recrystallized from toluene to give
0.92 g (71% yield) of pure 37; mp 94–96 °C; IR (neat, cmÀ1); 1H
NMR (300 MHz, DMSO-d6) d 1.85 (s, 3H), 3.22 (t, J = 7.4 Hz, 2H),
3.40 (m, 2H), 3.86 (s, 3H), 3.97 (s, 3H), 6.95 (dd, J = 8.8 and
1.7 Hz, 1H), 7.21 (dd, J = 8.8 and 1.7 Hz, 1H), 7.33 (d, J = 1.7 Hz,
1H),7.37–7.44 (m, 2H), 7.66 (d, J = 1.7 Hz, 1H), 7.69 (s, 1H), 7.92
(d, J = 8.8 Hz, 1H), 8.05 (s, 1H),8.17 (br s, 1H).
3.2.23. ( )-cis-N-(3-(4-(2-Acetylaminoethyl)-6-methoxy-1,2,3,4-
tetrahydronaphthalen-2-yl)phenyl) acetamide (33)
A solution of 31 (3.21 g, 10 mmol) in 100 mL of acetic anhydride
was hydrogenated over Raney nickel under pressure (50 bar) at
60 °C for 12 h. After filtration and evaporation, the residue was ta-
ken off with water and extracted with ethyl acetate. The organic
phase was washed with a 10% K2CO3 solution then with water,
dried over MgSO4, filtered, and concentrated under reduced pres-
sure to afford a residue which was recrystallized from acetonitrile
to give 1.67 g (44% yield) of 33; mp 147–148 °C; IR (neat, cmÀ1
)
3296, 1661, 1631; 1H NMR (300 MHz, DMSO-d6) d 1.72–1.77 (m,
2H), 1.80 (s, 3H), 2.04 (s, 3H), 2.05–2.19 (m, 2H), 2.66–2.84 (m,
3H), 2.99 (m, 1H), 3.13 (m, 2H), 3.73 (s, 3H), 6.70 (dd, J = 8.2 and
2.3 Hz, 1H), 6.85 (d, J = 2.3 Hz, 1H), 6.98–7.02 (m, 2H), 7.24 (t,
J = 8.7 Hz, 1H), 7.46–7.51 (m, 2H), 7.89 (br s, 1H), 9.92 (br s, 1H).
Anal. Calcd for C23H28N2O3: C, 72.60; H, 7.41; O, 12.61. Found: C,
72.35; H, 7.38; O, 12.96.
3.2.28. ( )-cis-N-(2-(7-Methoxy-3-(3-methoxyphenyl)-1,2,3,4-
tetrahydronaphthalen-1-yl)ethyl) acetamide (38)
Liquid ammonia (100 mL) was added at À33 °C to a solution of
37 (1 g, 3.0 mmol) in 50 mL of anhydrous THF under Ar. Lithium
(0.2 g, 3.0 mmol) was then added portionwise and the mixture
was stirred vigorously at the same temperature until the gray color
of the solution has completely disappeared. A saturated aqueous
solution of ammonium chloride was added dropwise then the mix-
ture was extracted with ethyl acetate. The organic phase was dried
over MgSO4, filtered and concentrated under reduced pressure,
affording a residue which was crystallized from isopropyl ether
3.2.24. ( )-cis-(7-Methoxy-3-(3-trifluoromethylphenyl)-1,2,3,4-
tetrahydronaphthalen-1-yl)ethylamine hydrochloride (34)
A saturated ammonia solution of 32 (3 g, 9.0 mmol) in 150 mL
of ethanol was hydrogenated for 5 h over Raney nickel under pres-
sure (60 bars) at 60 °C. After filtration and evaporation, the residual
oil was dissolved in dry diethyl ether and treated with gaseous HCl.
The obtained solid was filtered and recrystallized from ethyl ace-
tate to give 1.18 g (35% yield) of 34; mp 185–187 °C; IR (neat,
cmÀ1) 3120–2740; 1H NMR (300 MHz, DMSO-d6) d 1.73–2.34 (m,
4H), 2.75–3.52 (m, 4H), 3.71 (m, 2H), 3.80 (s, 3H), 6.79 (dd,
J = 8.6 and 2.0 Hz, 1H), 6.97 (d, J = 2.0 Hz, 1H), 7.08 (d, J = 8.6 Hz,
1H), 7.59–7.75 (m, 4H), 8.15–8.23 (br s, 3H).
to give 0.21 g (21% yield) of 38; mp 107–109 °C; IR (neat, cmÀ1
)
3303, 1633; 1H NMR (300 MHz, DMSO-d6) d 1.57–1.72 (m, 2H),
1.80 (s, 3H), 2.05–2.18 (m, 2H), 2.76–2.83 (m, 3H), 3.01 (m, 1H),
3.10–3.20 (m, 2H), 3.74 (s, 3H), 3.76 (s, 3H), 6.71 (dd, J = 8.5 and
2.4 Hz, 1H), 6.80 (dd, J = 8.0 and 2.4 Hz, 1H), 6.85 (d, J = 2.4 Hz,
1H), 6.88–6.93 (m, 2H), 7.00 (d, J = 8.5 Hz, 1H), 7.25 (t, J = 8.0 Hz,
1H), 7.90 (br s, 1H). Anal. Calcd for C22H27NO3 : C, 74.76; H, 7.70;
N, 3.96. Found: C, 74.51; H, 7.79; N, 3.98.
3.2.25. ( )-cis-N-(2-(7-Methoxy-3-(3-trifluoromethylphenyl)-
1,2,3,4-tetrahydronaphthalen-1-yl)ethyl)
3.2.29. ( )-cis-((7-Methoxy-3-phenyl)-1,2,3,4-
tetrahydronaphthalen-1-yl) acetic acid (40)
cyclobutylcarboxamide (35)
A mixture of compound 39 (4 g, 145 mmol) in 60 mL of metha-
nol and 60 mL of an aqueous sodium hydroxide solution (23.2 g,
580 mmol) was refluxed for 4 days. The mixture was then poured
into cold water and washed with ether. The aqueous phase was
acidified with concentrated HCl, afforded a precipitate which was
filtered, dissolved in 150 mL of ethanol and hydrogenated over
10% palladium charcoal (0.5 g) under pressure (50 bars) at room
temperature for 12 h. After filtration and evaporation, the residue
was recrystallized from ethanol to give 2.41 g (56% yield) of 40;
mp 141–142 °C; IR (neat, cmÀ1) 3250–2550, 1702; 1H NMR
(300 MHz, DMSO-d6) d 1.77 (m, 1H), 2.36 (m,1H), 2.56 (dd,
J = 15.7 and 9.4 Hz, 1H), 2.88–3.02 (m, 3H), 3.09 (dd, J = 15.7 and
4.3 Hz, 1H), 3.52 (m, 1H), 3.81 (s, 3H), 6.77 (dd, J = 8.5 and
2.4 Hz, 1H), 6.84 (d, J = 2.4 Hz, 1H), 7.06 (d, J = 8.5 Hz, 1H), 7.24–
7.40 (m, 5H), 12.00 (br s, 1H).
Starting from 34, compound 35 was obtained according to the
procedure described for compounds 11–15. Recrystallized from
isopropyl ether; yield 37%; mp 115–117 °C; IR (neat, cmÀ1) 1654;
1H NMR (CDCl3) d 1.62–2.32 (m, 10H), 2.77–3.02 (m, 4H), 3.12
(m, 1H), 3.40 (m, 2H), 3.82 (s, 3H), 5.37 (br s, 1H), 6.73 (dd,
J = 8.4 and 2.4 Hz, 1H), 6.88 (d, J = 2.4 Hz, 1H), 7.03 (d, J = 8.4 Hz,
1H), 7.43–7.52 (m, 4H). Anal. Calcd for C22H24F3NO2: C, 67.51; H,
6.18; N, 3.58. Found: C, 67.61; H, 6.15; N, 3.35.
3.2.26. N-[2-(3-Bromo-7-methoxynaphthalen-1-
yl)ethyl]acetamide (36)
To a solution of N-[2-(7-methoxynaphthalen-1-yl)ethyl] acet-
amide (2 g, 8.0 mmol) in 40 mL of glacial acetic acid was added
dropwise at 70 °C a solution of bromine (1.6 mL, 10 mmol) in
6 mL of glacial acetic acid. After stirring for 6 h at this temperature,
the mixture was cooled, poured into ice-water and extracted with
ethyl acetate. The organic phase was dried over MgSO4, filtered,
and concentrated under reduced pressure. The residue was recrys-
tallized from toluene to give 1.90 g (73% yield) of pure 36; mp 104–
106 °C; IR (neat, cmÀ1) 3293, 1633; 1H NMR (300 MHz, DMSO-d6) d
1.83 (s, 3H), 3.12 (t, J = 8.3 Hz, 2H), 3.33 (m, 2H), 3.94 (s, 3H), 7.22
(dd, J = 9.0 and 2.4 Hz, 1H), 7.46 (d, J = 2.0 Hz, 1H), 7.63 (d,
3.2.30. ( )-cis-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)acetylazide (41)
Triethylamine (2 mL, 15 mmol) and ethyl chloroformate
(1.5 mL, 15.0 mmol) were added at 0 °C to a stirred solution of acid
40 (3 g, 10.0 mmol) in 50 mL of acetone. After 1 h of stirring at 0 °C,
sodium azide (0.98 g, 15.0 mmol) dissolved in 1 mL of water was
added, then the mixture was stirred at room temperature for 1 h,
poured into water and extracted with methylene chloride. The or-

2972
S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
ganic phase was dried over MgSO4, filtered and concentrated under
reduced pressure and without heating. The residue was precipi-
tated from petroleum ether and filtered to give 2.51 g (77% yield)
2.26 (m, 1H), 2.49 (m, 1H), 2.82–2.95 (m, 3H), 3.31 (m, 1H), 3.85
(s, 3H), 4.11 (t, J = 7.1 Hz, 2H), 6.74 (dd, J = 8.4 and 2.4 Hz, 1H),
6.89 (d, J = 2.4 Hz, 1H), 7.03 (d, J = 8.4 Hz, 1H), 7.25–7.40 (m, 5H).
of 41; mp 46–47 °C; IR (neat, cmÀ1
)
2258, 1610; 1H NMR
(300 MHz, DMSO-d6) d 1.88 (m, 1H), 2.29 (m, 1H), 2.87–3.04 (m,
3H), 3.27–3.31 (m, 1H), 3.62 (dd, J = 13.1 and 6.2 Hz, 1H), 3.70
(dd, J = 13.1 and 3.8 Hz, 1H), 3.83 (s, 3H), 6.79 (dd, J = 8.3 and
2.8 Hz, 1H), 6.82 (d, J = 2.8 Hz, 1H), 7.08 (d, J = 8.3 Hz, 1H), 7.22–
7.40 (m, 5H).
3.2.35. ( )-cis-2-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)methanesulfonylethanol (46)
Triethylamine (0.5 mL, 4.0 mmol), and then methane sulfonyl
chloride (0.3 mL, 4.0 mmol) were added dropwise at À10 °C to 45
(0.9 g, 3.0 mmol) dissolved in 50 mL of methylene chloride. The
reaction mixture was stirred for 1 h at room temperature and
washed twice with 20 mL of 3 M HCl, then with water. The organic
phase was dried over MgSO4, filtered and concentrated under re-
duced pressure. The residue was precipitated from petroleum
ether and filtered to afford 0.85 g (74% yield) of 46; mp 88–
89 °C; IR (neat, cmÀ1) 1354 and 1169; 1H NMR (300 MHz, DMSO-
d6) d 1.68 (m, 1H), 2.08 (m,1H), 2.29 (m, 1H), 2.51 (m, 1H), 2.85–
2.97 (m, 3H), 3.00 (s, 3H), 3.26 (m, 1H), 3.84 (s, 3H), 4.36 (t,
J = 7.6 Hz, 2H), 6.76 (dd, J = 8.4 and 2.4 Hz, 1H), 6.87 (d, J = 2.4 Hz,
1H), 7.05 (d, J = 8.4 Hz, 1H), 7.24–7.29 (m, 5H).
3.2.31. ( )-cis-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)methylamine hydrochloride (42)
A solution of 41 (2.5 g, 8.0 mmol) in 30 mL of anhydrous toluene
was refluxed until nitrogen was completely liberated. After evapo-
ration, the residue was taken off with 50 mL of 6 M HCl and re-
fluxed for 5 h. The mixture was evaporated under reduced
pressure and the residue was taken off with acetonitrile. The pre-
cipitate was filtered and recrystallized from acetonitrile/methanol,
9:1, affording 2.36 g (38% yield) of 32; mp 262–263 °C; IR (neat,
cmÀ1) 3150–2750; 1H NMR (300 MHz, DMSO-d6) d 1.75 (m, 1H),
2.25 (m, 1H), 2.82–2.90 (m, 4H), 2.95 (m, 1H), 3.51 (m, 1H), 3.78
(s, 3H), 6.78 (d, J = 8.3 Hz, 1H), 6.95 (s, 1H), 7.07 (d, J = 8.3 Hz,
1H), 7.25 (m, 1H), 7.31–7.40 (m, 4H), 8.12–8.23 (br s, 3H).
3.2.36. ( )-cis-3-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)propionitrile (47)
Potassium cyanide (0.4 g, 7.0 mmol) was added to a solution of
46 (0.8 g, 2.0 mmol) in 20 mL of dimethylsulfoxyde. After stirring
at 80 °C for 1 h, the reaction mixture was poured into water and
extracted with ether. The organic phase was dried over MgSO4, fil-
tered and concentrated under reduced pressure. The residue was
precipitated from petroleum ether, filtered and recrystallized from
ethanol/water, 2:1, affording 0.30 g (93% yield) of pure 47; mp 89–
90 °C; IR (neat, cmÀ1) 2246; 1H NMR (300 MHz, DMSO-d6) d 1.62
(m, 1H), 2.03 (m, 1H), 2.25 (m, 1H), 2.31–2.46 (m, 3H), 2.85–3.01
(m, 3H), 3.25 (m, 1H), 3.83 (s, 3H), 6.76 (dd, J = 8.2 and 2.4 Hz,
1H), 6.83 (d, J = 2.4 Hz, 1H), 7.06 (d, J = 8.2 Hz, 1H), 7.27–7.35 (m,
5H).
3.2.32. ( )-cis-N-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)methylacetamide (43)
Starting from 42 and acetyl chloride, compound 43 was ob-
tained according to the procedure previously described for com-
pounds (11–15). Recrystallized from isopropyl ether; yield 42%;
mp 137–139 °C; IR (neat, cmÀ1) 3270, 1639; 1H NMR (DMSO-d6)
d 1.62 (m, 1H), 1.80 (s, 3H), 2.11 (m, 1H), 2.79–2.88 (m, 3H), 3.07
(m, 1H), 3.19 (m, 1H), 3.67 (m, 1H), 3.74 (s, 3H), 6.74 (dd, J = 8.4
and 2.4 Hz, 1H), 6.90 (d, J = 2.4 Hz, 1H), 7.03 (d, J = 8.4 Hz, 1H),
7.23 (m, 1H), 7.30–7.38 (m, 4H), 7.89–7.95 (br s, 1H). Anal. Calcd
for C20H23NO2: C, 77.64; H, 7.49; N, 4.53. Found: C, 77.71; H,
7.59; N, 4.30.
3.2.37. ( )-cis-N-[3-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)propyl]acetamide (48)
3.2.33. ( )-cis-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethylacetate (44)
A solution of 47 (0.6 g, 2.0 mmol) in acetic anhydride was
hydrogenated over Raney nickel (0.2 g) under pressure (50 bars)
at 60 °C for 12 h. After cooling, acetic anhydride was evaporated,
then the residue was taken off with water and extracted with ethyl
acetate. The organic phase was washed with a 10% aqueous potas-
sium carbonate solution and with water, dried over MgSO4, filtered
and concentrated under reduced pressure. The residue was recrys-
tallized from isopropylic ether, affording 0.33 g (47% yield) of pure
Thionyl chloride (15.1 mL, 208 mmol) was added dropwise at
À10 °C to a stirred solution of acid 40 (3 g, 10 mmol) in 100 mL
of absolute ethanol. After 12 h of stirring at room temperature,
the reaction mixture was evaporated. The residue was taken off
with ether, washed twice with a 10% aqueous potassium carbonate
solution, dried over MgSO4, filtered and concentrated under re-
duced pressure. The residue was precipitated from petroleum
ether, filtered and recrystallized from ethanol to give 1.44 g (44%
yield) of 44; mp 77–78 °C; IR (neat, cmÀ1) 1716; 1H NMR
(300 MHz, DMSO-d6) d 1.17 (t, J = 7.0 Hz, 3H), 1.74 (m, 1H), 2.11
(m,1H), 2.46 (dd, J = 15.7 and 9.2 Hz, 1H), 2.72–2.95 (m, 3H), 3.07
(dd, J = 15.7 and 4.3 Hz, 1H), 3.35 (m, 1H), 3.72 (s, 3H), 4.08 (q,
J = 7.0 Hz, 2H), 6.73 (dd, J = 8.4 and 2.4 Hz, 1H), 6.88 (d, J = 2.4 Hz,
1H), 7.01 (d, J = 8.4 Hz, 1H), 7.22 (m, 1H), 7.26–7.37 (m, 4H).
48; mp 102–104 °C; IR (neat, cmÀ1
)
3290, 1644; 1H NMR
(300 MHz, CDCl3) d 1.52–1.74 (m, 5H), 1.97 (s, 3H), 2.22 (m, 1H),
2.82–2.98 (m, 3H), 3.09 (m, 1H), 3.29 (m, 2H), 3.83 (s, 3H), 6.73
(dd, J = 8.4 and 2.6 Hz, 1H), 6.86 (d, J = 2.6 Hz, 1H), 7.03 (d,
J = 8.4 Hz, 1H), 7.22–7.38 (m, 5H), 7.78 (br s, 1H). Anal. Calcd for
C22H27NO2: C, 78.30; H, 8.06; N, 4.15. Found: C, 78.02; H, 8.02; N,
4.19.
3.2.38. (7-Methoxy-2-phenyl-3,4-dihydro-2H-naphthalen-1-
ylidene)acetonitrile (51)
3.2.34. ( )-cis-2-(7-Methoxy-3-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethanol (45)
Diethyl cyanomethylphosphonate (8.5 mL, 54 mmol) in 30 mL
of anhydrous THF was added dropwise at À10 °C to a stirred mix-
ture of NaH (60% in mineral oil) (2.2 g, 54 mmol) and 50 mL of
anhydrous THF under N2. After 1 h, a solution of 49 (6.8 g,
27 mmol) in 60 mL of anhydrous THF was added dropwise and
the mixture was stirred at room temperature for 16 h. The mixture
was then poured into ice-water and extracted with diethyl ether.
The organic phase was dried over MgSO4, filtered and concentrated
under reduced pressure to give a oily residue which was purified
by column chromatography (SiO2, cyclohexane/acetone (9.5/0.5)),
affording 2.2 g (30% yield) of pure 51; mp 107–109 °C; IR (neat,
Lithium aluminium hydride (0.3 g, 9.0 mmol) was added por-
tionwise to 44 (1.4 g, 4.0 mmol) in 30 mL of ether. After 30 min
of stirring at room temperature, the reaction mixture was drop-
wise hydrolyzed with 3 M HCl. The precipitate was filtered and
washed twice with 50 mL of ethyl acetate. The filtrate was dried
over MgSO4, filtered and concentrated under reduced pressure.
The residue was precipitated from petroleum ether, filtered and
recrystallized from ethanol/water, 1:1, affording 0.95 g (78% yield)
of 45; mp 78–80 °C; IR (neat, cmÀ1
)
3500–3100; 1H NMR
(300 MHz, DMSO-d6) d 1.60 (br s, 1H), 1.69 (m, 1H), 2.04 (m,1H),

S. Durieux et al. / Bioorg. Med. Chem. 17 (2009) 2963–2974
2973
cmÀ1) 2215; 1H NMR (300 MHz, DMSO-d6) d 2.10–2.70 (m, 4H),
3.83 (s, 3H), 4.45 (m, 1H), 6.60 (s, 1H), 7.01 (dd, J = 8.5 and
2.5 Hz, 1H), 7.01–7.15 (m, 3H), 7.20–7.33 (m, 3H), 7.48 (d,
J = 2.5 Hz, 1H).
37 °C, reaction was stopped by rapid filtration through GF/B filters
presoaked in 0.5% (v/v) polyethylenimine. Filters were washed
three times with 1 mL of ice-cold 50 mM Tris–Cl buffer, pH 7.4.
Data from the dose–response curves (seven concentrations in
duplicate) were analyzed using the program PRISM (Graph Pad
Software Inc., San Diego, CA) to yield IC50 (inhibitory concentration
50). Results are expressed as Ki = IC50/1 + ([L]/KD), where [L] is the
concentration of radioligand used in the assay and KD, the dissoci-
ation constant of the radioligand characterizing the membrane
preparation.
3.2.39. (7-Methoxy-2-benzyl-3,4-dihydro-2H-naphthalen-1-
ylidene)acetonitrile (52)
Starting from 50, compound 52 was obtained according to the
procedure described for 51; yield 59%; mp 112–113 °C; IR (neat,
cmÀ1) 2212; 1H NMR (300 MHz, DMSO-d6) d 1.74–1.76 (m, 2H),
2.61–2.79 (m, 3H), 3.02 (m, 1H), 3.31 (m, 1H), 3.79 (s, 3H), 6.30
(s, 1H), 7.02 (dd, J = 8.6 and 2.5 Hz, 1H), 7.16–7.34 (m, 7H).
[
35S]-GTP
cS binding assay was performed according to pub-
lished methodology.25 Briefly, membranes from transfected CHO
cells expressing MT2 receptor subtype and compounds were di-
luted in binding buffer (20 mM HEPES, pH 7.4, 100 mM NaCl,
3.2.40. ( )-cis-N-(7-Methoxy-2-phenyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethylacetamide (53)
3
l
M GDP, 3 mM MgCl2, and 20
started by the addition of 0.2 nM [35S]-GTP
(20 g/mL) and drugs, and further followed for 1 h at room tem-
l
g/mL saponin). Incubation was
Starting from 51, compound 53 was obtained according to the
procedure described for 48. Recrystallized from isopropyl ether;
yield 76%; mp 126–128 °C; IR 1648 (neat, cmÀ1); 1H NMR
(300 MHz, DMSO-d6) d 1.30–1.41 (m, 2H), 1.68 (s, 3H), 1.95 (m,
1H), 2.12 (m, 1H), 2.71–2.93 (m, 5H), 3.13 (m, 1H), 3.74 (s, 3H),
6.74–6.78 (m, 2H), 7.09 (d, J = 9.0 Hz, 1H), 7.19–7.26 (m, 3H),
7.30–7.36 (m, 2H), 7.67 (br s, 1H). Anal. Calcd for C20H23NO2: C,
77.99; H, 7.79; N, 4.33. Found: C, 77.79; H, 7.57; N, 4.42.
c
S to membranes
l
perature. For experiments with antagonists, membranes were pre-
incubated with both the melatonin (3 nM) and the antagonist for
30 min prior the addition of [35S]-GTP
c
S. Non-specific binding
was defined using cold GTPcS (10 lM). Reaction was stopped by
rapid filtration through GF/B filters followed by three successive
washes with ice-cold buffer.
S binding (expressed in dpm) were for
CHO-MT2 membranes: 2000 for basal activity, 8000 in the presence
of melatonin 1 M and 180 in the presence of GTPccS 10
Usual levels of [35S]-GTP
c
3.2.41. ( )-cis-N-(7-Methoxy-2-benzyl-1,2,3,4-
tetrahydronaphthalen-1-yl)ethylacetamide (54)
l
lM
Starting from 52, compound 53 was obtained according to the
procedure described for 48. Recrystallized from isopropyl ether;
which defined the non-specific binding. Data from the dose–re-
sponse curves (seven concentrations in duplicate) were analyzed
by using the program PRISM (Graph Pad Software Inc., San Diego,
CA) to yield EC50 (effective concentration 50%) and Emax (maximal
yield 25%; mp 74–75 °C; IR (neat, cmÀ1
)
1650; 1H NMR
(300 MHz, DMSO-d6) d 1.36 (m, 1H), 1.54–1.68 (m, 2H), 1.79 (s,
3H), 1.86 (m, 1H), 2.01 (m, 1H), 2.45–2.83 (m, 5H), 3.08 (m, 2H),
3.69 (s, 3H), 6.66–6.71 (m, 2H), 7.91 (d, J = 9.1 Hz, 1H), 7.16–7.32
(m, 5H), 7.87 (br s, 1H). Anal. Calcd for C22H27NO2: C, 78.30; H,
8.06; N, 4.15. Found: C, 78.49; H, 7.98; N, 4.22.
effect) for agonists. Antagonist potencies are expressed as KB = IC50
1 + ([Ago]/EC50 ago), where IC50 is the inhibitory concentration of
antagonist that gives 50% inhibition of [35S]-GTP
S binding in the
/
c
presence of a fixed concentration of melatonin ([Ago]) and EC50
ago is the EC50 of the molecule when tested alone. Imax (maximal
inhibitory effect) was expressed as a percentage of that observed
with melatonin at 3 nM for MT2 receptor.
3.3. Pharmacology
3.3.1. Reagents and chemicals
2-[125I]Iodomelatonin (2200 Ci/mmol) was purchased from
NEN (Boston, MA). Other drugs and chemicals were purchased
from Sigma–Aldrich (Saint Quentin, France).
Acknowledgments
The 300 MHz NMR facilities were funded by the Région Nord-
Pas de Calais (France), the Ministère de la Jeunesse, de l’Education
Nationale et de la Recherche (MJENR) and the Fonds Européens de
Développement Régional (FEDER).
3.3.2. Cell culture
HEK (provided by A.D. Strosberg, Paris, France) and CHO cell
lines stably expressing the human melatonin MT1 or MT2 receptors
were grown in DMEM medium supplemented with 10% fetal calf
References and notes
serum, 2 mM glutamine, 100 IU/mL penicillin and 100 lg/ml strep-
tomycin. Grown at confluence at 37 °C (95%O2/5%CO2), they were
harvested in PBS containing EDTA 2 mM and centrifuged at
1000g for 5 min (4 °C). The resulting pellet was suspended in Tris
5 mM (pH 7.5), containing EDTA 2 mM and homogenized using a
Kinematica polytron. The homogenate was then centrifuged
(95,00g, 30 min, 4 °C) and the resulting pellet suspended in
75 mM Tris (pH 7.5), 12.5 mM MgCl2 and 2 mM EDTA. Aliquots
of membrane preparations were stored at À80 °C until use.
1. Reiter, R. J. Endocr. Rev. 1991, 12, 151.
2. Pevet, P.; Bothorel, B.; Slotten, H.; Saboureau, M. Cell Tissue Res. 2002, 309, 183.
3. Reppert, S S. M.; Weaver, D. R.; Ebisawa, T. Neuron 1994, 13, 1177.
4. Dubocovich, M. L.; Cardinali, D. P.; Delagrange, P.; Krause, D. N.; Strosberg, A.
D.; Sugden, D.; Yocca, F. D.; IUPHAR Media: London, 2000.
5. Li, P.-K.; Witt-Enderby, P. A. Drug Future 2000, 25, 945.
6. Dubocovich, M. L.; Yun, K.; Al-Ghoul, W. M.; Benloucif, S.; Masana, M. I. FASEB J.
1998, 12, 1211.
7. Liu, C.; Weaver, D. R.; Jin, X.; Shearman, L. P.; Pieschl, R. L.; Gribkoff, V. K.;
Reppert, S. M. Neuron 1997, 19, 91.
8. Doolen, S.; Krause, D. N.; Dubocovich, M. L.; Duckles, S. P. Eur. J. Pharmacol.
1998, 345, 67.
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2001, 280, C110.
10. Dubocovich, M. L.; Masana, M. I.; Iacob, S.; Sauri, D. M. Naunyn-Schmiedeberg’s
Arch. Pharmacol. 1997, 355, 365.
11. Wallez, V.; Durieux-Poissonnier, S.; Chavatte, P.; Boutin, J. A.; Audinot, V.;
Nicolas, J.-P.; Bennejean, C.; Delagrange, P.; Renard, P.; Lesieur, D. J. Med. Chem.
2002, 45, 2788.
12. Durieux-Poissonier, S.; Ettaoussi, M.; Pérès, B.; Boutin, J.-A.; Audinot, V.;
Bennejean, C.; Delagrange, D.; Caignard, D.-H.; Renard, P.; Berthelot, P.; Lesieur,
D.; Yous, S. Bioorg. Med. Chem. 2008, 16, 8339.
3.3.3. Binding asays
2-[125II]Iodomelatonin binding assay conditions were essen-
tially as previously described.25 Briefly, binding was initiated by
addition of membrane preparations from stable transfected HEK
or CHO cells diluted in binding buffer (50 mM Tris–Cl buffer, pH
7.4, containing 5 mM MgCl2) to 2-[125II]iodomelatonin (25 or
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