Synthesis and biological evaluation of novel fluoro and iodo quinoline carboxamides as potential ligands of NK-3 receptors for in vivo imaging studies

Article abstract of DOI:10.1016/j.bmc.2004.05.020

In order to develop radioligands of human NK-3 receptor (hNK-3r) for imaging studies by positron emission tomography (PET) or single photon emission computed tomography (SPECT), a new series of fluoro- and iodo-quinoline carboxamides were synthesized and evaluated in a target receptor binding assay. Compared to the unsubstituted parent compound SB 223 412 (K_i= 27nM±9), affinity was not altered for the analogues 1c and 2c bearing a fluorine in position 8 (K_i～24-27nM), and was only slightly reduced for compounds 1b, 2b, 1e and 2e fluorinated or iodinated at the position 7 (K_i～49-67nM). A drastic reduction in binding (K _i>115nM) was observed for all other halogenated compounds 1a, 2a, 1d, 2d, 1f and 2f.

Full text of DOI:10.1016/j.bmc.2004.05.020

Bioorganic & Medicinal Chemistry 12 (2004) 4533–4541
Synthesis and biological evaluation of novel fluoro and
iodo quinoline carboxamides as potential ligands of
NK-3 receptors for in vivo imaging studies
Idriss Bennacef,a,b Sylvie Tymciu,a Martine Dhilly,a Marie-Claire Lasne,b
a
Danielle Debruyne, Cecile Perrio
a,b,
*
ꢀ
ꢀa,*
and Louisa Barre
aGroupe de Dꢀeveloppements Mꢀethodologiques en Tomographie par Emission de Positons, UMR CEA, FRE CNRS 2698,
Universitꢀe de Caen-Basse Normandie, Centre Cyceron, 15 Boulevard Henri Becquerel, 14070 Caen Cedex, France
bLaboratoire de Chimie Molꢀeculaire et Thioorganique, CNRS UMR 6507, ENSICAEN, Universitꢀe de Caen-Basse Normandie,
6 Boulevard Marꢀechal Juin, 14050 Caen Cedex, France
Received 6 February 2004; accepted 17 May 2004
Available online 26 June 2004
Abstract—In order to develop radioligands of human NK-3 receptor (hNK-3r) for imaging studies by positron emission tomo-
graphy (PET) or single photon emission computed tomography (SPECT), a new series of fluoro- and iodo-quinoline carboxamides
were synthesized and evaluated in a target receptor binding assay. Compared to the unsubstituted parent compound SB 223 412
(Ki ¼ 27 nM 9), affinity was not altered for the analogues 1c and 2c bearing a fluorine in position 8 (Ki ꢀ 24–27 nM), and was only
slightly reduced for compounds 1b, 2b, 1e and 2e fluorinated or iodinated at the position 7 (Ki ꢀ 49–67 nM). A drastic reduction in
binding (Ki > 115 nM) was observed for all other halogenated compounds 1a, 2a, 1d, 2d, 1f and 2f.
ꢀ 2004 Elsevier Ltd. All rights reserved.
1. Introduction
fined in PNS. The NK-3 receptor is characterized by a
predominant expression in CNS and its involvement in
the modulation of central monoaminergic system has
been shown. These properties make the NK-3 receptor a
potential target for central nervous system disorders
such as anxiety, psychosis, depression.12–16
The three main mammalian tachykinins, substance P
(SP), neurokinin A (NKA) and neurokinin B (NKB)
belong to the family of neuropeptides sharing the com-
mon COOH-terminal pentapeptide sequence of Phe-X-
Gly-Leu-Met-NH2. As neurotransmitters, these peptides
exert their biological activity via three distinct neuro-
kinin (NK) receptors termed as NK-1, NK-2 and NK-3.
SP binds preferentially to the NK-1 receptor, NKA to
the NK-2r and NKB to the NK-3r.1–4 These receptors
have been characterized by pharmacological studies and
binding assays, cloned and expressed in stably trans-
fected cells.5–7 Their distribution has been studied by
autoradiography, and by in situ hybridization and
immunocytochemistry.8–11 The NK-1 receptor is widely
distributed in central (CNS) and peripheral (PNS) ner-
vous system whilst the NK-2 receptor is primarily con-
Positron emission tomography (PET) and single photon
emission computed tomography (SPECT), are funda-
mental in vivo imaging techniques for the study of brain
receptors. These methods allow their visualization dur-
ing both physiological and pathophysiological condi-
tions by the interactions of the biological target with a
specific radioligand. As of present, no radioligand for
the NK-3 receptor has been described. The discovery of
SR 142801 (Osanetant)17 and SB 223412 (Talnetant)18–20
as lead compounds given that they are potent and
selective non-peptidergic NK-3r antagonists, promises
much for future in vivo biological investigations
(Scheme 1).
Keywords: NK-3 receptor; Quinoline carboxamide; Ligand; Fluorine;
Iodine.
SR 142801, has been tritiated and used in ex vivo
imaging studies.8;9 However, it displays a lower selec-
tivity than SB 223412. This latter seemed to us partic-
ularly attractive as it was found to be metabolically
* Corresponding authors. Tel.: +33-02-31-4702-81; fax: +33-02-31-47-
02-22 (C.P.); tel.: +33-02-31-47-02-24; fax: +33-02-31-47-02-22
(L.B.); e-mail addresses: perrio@cyceron.fr; barre@cyceron.fr
0968-0896/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2004.05.020

4534
I. Bennacef et al. / Bioorg. Med. Chem. 12 (2004) 4533–4541
Cl
Ph
Ph
Cl
N
F
O
NH
OH
Ph
O
NH
OR
Ph
target molecules
Ac
N
Ac
N
Me
N
N
Ph
I
SR 142801
SB 223412
R = Me
R = H
1
2
Scheme 1. h-NK3r antagonists and target molecules.
stable and able to cross the blood–brain barrier.
Moreover, SAR studies on the quinoline carboxamide
structures showed that chemical modifications on the
quinoline ring could be envisaged without loss of affinity
at NK-3r.19;21 In order to develop ligands for in vivo
imaging studies by PET or SPECT, we aimed to design
fluoro- and iodoanalogues of SB 223412 that retain the
biological activity of the parent compound. Herein, we
describe the synthesis of new halogenated methoxy- or
hydroxyquinoline carboxamides 1–2 and their in vitro
evaluation (Scheme 1).
50%. Then, we turned towards the use of BBr3; under
these conditions, fluorohydroxyacids 5a–c were ob-
tained in high yields (75–93%). In the iodinated series,
only the hydroxyacid 5d substituted in the position 6
was formed in satisfactory yield (70%). Hydroxyacids
5e,f bearing an iodine in the positions 7 and 8, respec-
tively, could not be isolated.
Methoxy- and hydroxyacids 4–5 were converted into
quinoline carboxamides 1–2 by amidation with (S)-
phenylpropylamine either in the presence of HOBt (1-
hydroxybenzotriazole) and EDCI (1-(3-dimethylamino-
propyl)-3-ethylcarbodiimide) in CH2Cl2, or via an acti-
vation with N-hydrosuccinimide in the presence of
EDCI in DMF. This step afforded methoxyquinoline
carboxamides 1a–f in yields ranging from 67% to 98%,
and the hydroxy analogues 2a–f in only 10–30% yields.
Finally, demethylation of methoxycarboxamides 1a–f
using BBr3 was found to be the method of choice to
prepare hydroxyacids 2a–f. In both fluoro- and iodo
series, yields in 2a–f were in the 64–81% range. Finally,
12 quinoline carboxamides 1a–f and 2a–f, bearing either
a methoxy or a hydroxy group in the position 3, and
either a fluorine or an iodine atom in the positions 6, 7
or 8, were prepared.
2. Results and discussion
2.1. Chemistry
Synthesis of the target compounds was based on the
Pfitzinger reaction converting isatin into quinolinic
acid.19;21;22 The previously described isatins 3a–f, bearing
a fluorine or an iodine atom in position 5, 6 or 7 were
used as starting materials.23;24 The treatment of these
latter with 2-methoxyacetophenone under basic condi-
tions led to the corresponding 3-methoxyquinolinic
acids 4a–f in 53–100% yields (Scheme 2). The same
reaction from 5-fluoroisatin 3a and 2-hydroxyaceto-
phenone afforded the corresponding hydroxyacid 5a in
poor yields (34%).
2.2. Affinity and selectivity of the synthesized ligands
Affinities of the novel quinoline carboxamides 1–2 at the
NK-3 receptor, were evaluated by analyzing the specific
displacement of [3H]-senktide binding on CHO
cells stably expressing the human recombinant NK-3
receptor (hNK-3r). In each experiment, the results were
Access to hydroxyacids 5a–f was envisaged by demeth-
ylation of methoxyacids 4a–f. In preliminary experi-
ments carried out with HI,18;19 yields did not exceed
O
NH
OR
CO2H
OR
O
4
7
O
5
8
5
8
5
6
X
i
6
7
X
ii
6
7
X
OMe
+
O
Ph
N
N
Ph
N
Ph
H
R = Me
R = H
R = Me
R = H
3
4
5
1
2
iii
iii
For isatins 3 :
For quinolines 1-2, 4-5 :
X = a) 5-F, b) 6-F, c) 7-F, d) 5- I, e) 6-I, f) 7-I I
X = a) 6-F, b) 7-F, c) 8-F, d) 6- I, e) 7-I, f) 8-I
Scheme 2. Synthesis of target quinoline carboxamides. Reagents and conditions: (i) KOH, EtOH, 70 ꢁC, 72 h; (ii) EDCI, HCl, Et3N, HOBt, (S)-
phenylpropylamine, CH2Cl2, )5 ꢁC for 1 h then rt for 18 h, or (1) EDCI, NHS, DMF, )5 ꢁC for 1 h then rt for 6 h; (2) (S)-phenylpropylamine,
CH2Cl2, D, 4 h; (ii) BBr3, CH2Cl2, )78 ꢁC for 1.5 h then rt for 3 h; (2) EtOH, )78 ꢁC.

I. Bennacef et al. / Bioorg. Med. Chem. 12 (2004) 4533–4541
4535
compared with those obtained on the same in vitro
model with endogenous NKB, the senktide itself, the
known potent synthetic antagonists SB 223412 and SB
22220025 and finally with endogenous NKA, which
exhibits preferential binding to the NK-2 receptors
(Table 1).
position 8, displayed similar affinities compared to SB
223412, senktide and NKB, whereas the corresponding
iodoanalogues 1f and 2f were devoid of significant
hNK-3r binding affinity. Compounds 1b,e and 2b,e
fluorinated or iodinated in position 7, exhibited an
approximately 2-fold lower affinity than those of the
references. Halogenation, and especially iodination, in
position 6 led to a reduction or loss of the binding
properties (compounds 1a,d and 2a,d).
As described for the SB 223412 reference compound,20
the replacement of the hydroxyl function by a methoxy
group in position 3 in the novel halogenated series, did
not modify affinities. However, the position and the
nature of the halogen atom, was crucial for affinity. The
quinolines 1c and 2c possessing a fluorine atom in
The haloquinolines 1b,c,e and 2b,c,e, which showed the
most significant affinities for NK-3r, exhibited no
affinity for NK-1r (Ki > 10 000), determined by specific
Table 1. Binding affinities of the novel quinoline carboxamides compared to NKB, senktide and the parent SB 223412 and SB 222200 compounds at
cloned hNK-3 and hNK-1 receptors
Compd
Binding affinities (Ki, nM; mean SEM)a
hNK-1c
hNK-3b
References
NKB
28 ( 3)
22 ( 1)d
27 ( 9)
31 ( 5)
>1000
––e
450 ( 40)
––e
Senktide
SB 223412
SB 222200
NKA
>10,000
>10,000
––e
SP
Quinolines
4.7 ( 1.6)
1
2
1
2
(R ¼ Me)
(R ¼ H)
(R ¼ Me)
(R ¼ H)
O
NHAlk
OR
––e
––e
F
a
162 78
115 15
N
O
Ph
NHAlk
OR
Ph
b
62 12
49
3
>10,000
>10,000
F
N
O
NHAlk
OR
c
27 11
24 13
>1000
>10,000
>10,000
N
Ph
F
O
NHAlk
––e
––e
I
OR
Ph
d
410 172
N
N
O
NHAlk
OR
e
f
57 11
67 26
>10,000
>10,000
Ph
I
O
NHAlk
OR
625 35
>1000
––e
––e
N
Ph
I
a Average of two to nine independent determinations (n ¼ 2–9).
b Inhibition of [3H]-senktide binding on hNK-3r-CHO cell membranes.26;27
c Inhibition of [125I]-Bolton-Hunter SP binding on hNK-3r-CHO cells.
d Kd 12 2 nM, determined by three independent saturation experiments.
e Not determined.

4536
I. Bennacef et al. / Bioorg. Med. Chem. 12 (2004) 4533–4541
displacement of [125I]-BH-SP (Bolton-Hunter Substance
P) binding (Table 1). Thus, the selectivity for hNK-3r
over hNK-1r was retained after substitution by a fluo-
rine atom in position 7 or 8 or by an iodine in position 7.
from Merck (0.1 mm). Plates were revealed with UV
detection or by ninhydrine (10% in ethanol) treatment
followed by heating. Flash chromatography was carried
out using Si 60 (40–63 lm) silica from Merck.
4.1.2. General procedure for the synthesis of 3-methoxy-4-
quinolinic acid hydrochlorides 4. A mixture of haloisatin
3 (1 equiv), 2-methoxyacetophenone (1.2 equiv) and
KOH pellets (85%, 3 equiv) in ethanol (5–50 mL) was
refluxed for 72 h. After concentration under vacuum, the
residue was dissolved in H2O and washed twice with
Et2O. The ice cold aqueous layer was acidified to pH 1
with HCl 37%. The precipitate formed was filtrated,
washed with H2O and dried at 65 ꢁC in an oven to give
the expected acid hydrochloride 4.
3. Conclusion
A new series of halogenated 2-phenylquinoline-4-carb-
oxamides 1–2 was prepared from the corresponding is-
atins 3. These compounds were evaluated as novel NK-3
ligands. Their binding properties were found strongly
dependent on the nature and position of the halogen
atom. The fluoro compounds 1b,c and 2b,c and the iodo
compounds 1e and 2e displayed a similar or close
affinity compared to that of unsubstituted SB 223412 as
reference. In view of the in vivo potential use of these
quinolines, work is in progress for their labelling with
fluorine-18 or iodine-123 for NK-3 receptor imaging
studies by PET or SPECT.
4.1.2.1. 6-Fluoro-3-methoxy-2-phenylquinoline-4-car-
boxylic acid hydrochloride 4a. Acid hydrochloride 4a
was obtained from 5-fluoroisatin 3a (3.0 g, 18.1 mmol),
2-methoxyacetophenone (3.27 g, 21.8 mmol) and KOH
(3.0 g, 53.6 mmol) in EtOH (25 mL): brown solid, mp
1
214–216 ꢁC; 87% (5.26 g). H NMR (DMSO-d6) d 3.60
(s, 3H), 7.35–7.62 (m, 4H), 7.67–7.72 (m, 1H), 7.93–7.97
4. Experimental
4.1. Chemistry
(m, 2H), 8.13–8.18 (m, 1H). 13C NMR (DMSO-d6) d
62.5,
108.4
(d,
2JCF ¼ 23:5 Hz),
120.0
(d,
3
2JCF ¼ 25:4 Hz), 125.6 (d, JCF ¼ 10:4 Hz), 129.3, 129.8,
130.3, 136.7 (d, 5JCF ¼ 5:6 Hz), 133.1 (d, 4JCF ¼ 9:8 Hz),
4.1.1. General considerations. All reagents were used as
supplied from commercial sources (Aldrich, Acros or
Fluka). Solvents were purchased from Carlo Erba. N,N-
Dimethylformamide (DMF) and dichloromethane
(CH2Cl2) were freshly distilled from calcium hydride
under nitrogen prior to use. Pentane, methanol
(MeOH), ethanol (EtOH), diethyl ether (Et2O), tetra-
hydrofuran (THF) and ethyl acetate (AcOEt) were used
as received. 1H and 13C nuclear magnetic resonance
spectra were recorded on a Bruker DPX 400 spectro-
meter at 400 MHz (1H) or 100.6 MHz (13C) or on a Bruker
DPX 250 at 250 MHz (1H) or 62.9 MHz (13C), and were
calibrated according to the chemical shift of tetramethyl-
silane. 19F nuclear magnetic resonance spectra were
recorded on a Bruker DPX 400 (376.5 MHz) or Bruker
DPX 250 (235 MHz) spectrometer, and were calibrated
according to the chemical shift of trifluorotoluene.
Chemical shift (d) are quoted in ppm and coupling
constants (J) in Hz. The following abbreviations are
used to denote multiplicities: s, singlet; d, doublet; dd,
double-doublet; ddd: double-double-doublet; t, triplet;
q, quartet; m, multiplet. Infrared spectra were recorded
on a Perkin–Elmer 16 PC FT IR spectrophotometer in
KBr and peaks are given in cmꢁ1. Low (EI) and high
resolution (HRMS, EI) mass spectra were recorded on a
JEOL JMS GCMate instrument at 70 eV. Optical rota-
tions were measured on a Perkin–Elmer 241 polarimeter
with a path length of 1 dm, concentrations (c) are quoted
in g/100 mL. Elemental analyses were performed on a
ThermoQuest analyzer CHNS–O, and were within
0.4% of the calculated values. Melting points (mp)
were measured on a Kofler hot-block apparatus. Thin
layer chromatography (TLC) was carried out on alu-
minium or plastic sheets coated with 60 F-254 silica
1
137.6, 142.1, 149.1, 154.4, 161.5 (d, JCF ¼ 246:0 Hz),
167.4. 19F NMR (DMSO-d6) d )(111.5–111.6) (m). IR
(KBr) 1724, 1614, 1504 and 1246. m=z 297 (MþÅ,
C17H12FNO3,100), 296 (99), 222 (43). HRMS (MþÅ,
C17H12FNO3) calcd 297.08010, found 297.08123.
4.1.2.2. 7-Fluoro-3-methoxy-2-phenylquinoline-4-car-
boxylic acid hydrochloride 4b. Acid hydrochloride 4b
was obtained from 6-fluoroisatin 3b (5.41 g, 32.9 mmol),
2-methoxyacetophenone (5.93 g, 39.5 mmol) and KOH
(5.5 g, 98.2 mmol) in EtOH (40 mL): brown solid, mp
1
218–222 ꢁC; 90% (9.87 g). H NMR (DMSO-d6) d 3.58
4
(s, 3H), 7.52–7.59 (m, 4H), 7.76 (dd, JH5F ¼ 2:7 Hz,
3JH5H6 ¼ 9:9 Hz, 1H), 8.01–8.03 (m, 2H), 8.77 (dd,
4JH8H6 ¼ 6:2 Hz, 3JH8F ¼ 9:4 Hz, 1H). 13C NMR
2
(DMSO-d6) d 62.1, 113.7 (d, JCF ¼ 20:3 Hz), 119.1 (d,
3
2JCF ¼ 25:4 Hz), 121.8, 127.6 (d, JCF ¼ 10:3 Hz), 129.3,
129.4, 129.8, 129.9, 130.4, 133.7, 137.6, 145.7 (d,
4
3JCF ¼ 12:6 Hz), 147.8 (d, JCF ¼ 2:8 Hz), 156.0, 158.8
1
(d, JCF ¼ 248 Hz), 167.5. 18F NMR (DMSO-d6) d
)(111.1–111.2) (m). IR (KBr) 3422, 1720, 1626, 1232,
1060 and 704. m=z 297 (MþÅ, C17H12FNO3, 91), 296 (90),
222 (36), 122 (37), 105 (57), 73 (100). HRMS (MþÅ,
C17H12FNO3) calcd 297.08010, found 297.08029.
4.1.2.3. 8-Fluoro-3-methoxy-2-phenylquinoline-4-car-
boxylic acid hydrochloride 4c. Acid hydrochloride 4c
was obtained from 7-fluoroisatin 3c (1.35 g, 8.2 mmol),
2-methoxyacetophenone (1.49 g, 9.9 mmol) and KOH
(1.50 g, 26.8 mmol) in EtOH (12 mL): brown solid, mp
254 ꢁC (decomposition); 53% (1.45 g). 1H NMR
(DMSO-d6) d 3.47 (s, 3H), 7.41–7.54 (m, 6H), 7.83–7.88
(m, 2H). 13C NMR (DMSO-d6) d 62.0, 113.7 (d,

I. Bennacef et al. / Bioorg. Med. Chem. 12 (2004) 4533–4541
4537
3
2JCF ¼ 19:1 Hz), 120.4 (d, JCF ¼ 4:3 Hz), 126.1 (d,
perature, the mixture was cooled to )78 ꢁC and ethanol
96% was added. The mixture was concentrated under
vacuum and the residue was dissolved in ethanol 96%,
then concentrated under vacuum and finally dissolved in
a mixture of THF/NaOH aqueous (2 N) 1:1. After stir-
ring for 1 h at 60 ꢁC, HCl 37% was added until pH 1 and
a precipitate was formed. The precipitate was filtered off,
washed with water and dried in an oven at 65 ꢁC to af-
ford hydroxyacids 5.
4JCF ¼ 2:0 Hz), 128.0, 128.8, 129.4, 130.0, 132.8 (d,
3JCF ¼ 2:8 Hz), 134.4 (d, JCF ¼ 12:0 Hz), 137.2, 148.4,
2
154.6, 156.7 (d, JCF ¼ 256 Hz), 166.9. 19F NMR
1
(DMSO-d6)
d
)123.4
(dd,
4JFH6 ¼ 3:8 Hz,
3JFH7 ¼ 7:5 Hz). IR (KBr) 2536, 1732, 1468, 1244, 1230,
762 and 702. m=z 297 (MþÅ, C17H12FNO3, 91), 296 (100),
223 (35), 222 (44). HRMS (MþÅ, C17H12FNO3) calcd
297.08010, found 297.08036.
4.1.2.4. 6-Iodo-3-methoxy-2-phenylquinoline-4-carbox-
ylic acid hydrochloride 4d. Acid hydrochloride 4d was
obtained from 5-iodoisatin (2.24 g, 8.22 mmol), 2-meth-
oxyacetophenone (1.48 g, 9.9 mmol) and KOH (1.4 g,
25.0 mmol) in EtOH (12 mL): brown solid, mp 202 ꢁC;
100% (3.62 g). 1H NMR (DMSO-d6) d 3.57 (s, 3H),
4.1.3.1. 6-Fluoro-3-hydroxy-2-phenylquinoline-4-car-
boxylic acid hydrochloride 5a. Acid hydrochloride 5a
was obtained from methoxyacid 4a (4.0 g, 12.0 mmol) in
CH2Cl2 (60 mL) and BBr3 (10.9 g, 43.3 mmol) in CH2Cl2
(60 mL): yellow solid, mp 224 ꢁC; 93% (3.55 g). 1H NMR
3
7.43–7.54 (m, 3H), 7.83 (d, JH7H8 ¼ 8:8 Hz, 1H), 7.93–
(DMSO-d6)
d
7.52–7.60 (m, 4H), 7.77 (dd,
8.01 (m, 3H), 8.10–8.12 (m, 1H). 13C NMR (DMSO-d6)
d 62.5, 95.6, 126.4, 129.3, 129.4, 129.8, 130.1, 130.4,
131.8, 132.0, 133.0, 137.6, 138.3, 143.7, 148.6, 155.5,
167.4. IR (KBr) 3504, 1702, 1448 and 1348. m=z 405
(MþÅ, C17H12INO3, 70), 404 (100). HRMS (MþÅ,
C17H12INO3) calcd 404.98680, found 404.98511.
4JH8F ¼ 2:7 Hz, 3JH8H7 ¼ 9:9 Hz, 1H), 8.00–8.02 (m, 2H),
4
3
8.77 (dd, JH5H7 ¼ 6:2 Hz, JH5F ¼ 9:5 Hz, 1H). 13C
2
NMR (DMSO-d6) d 109.1 (d, JCF ¼ 26 Hz), 116.0 (d,
2JCF ¼ 26 Hz), 126.0 (d, JCF ¼ 12 Hz), 128.3, 129.8,
3
130.0, 130.1, 131.6 (d, 3JCF ¼ 10 Hz), 136.2, 137.6, 151.5
4
1
(d, JCF ¼ 3 Hz), 156.4, 161.7 (d, JCF ¼ 245 Hz), 171.9.
19F NMR (DMSO-d6) d )111.0 (s). IR (KBr) 1918,
1630, 1600, 1526, 1450, 1406, 1374, 1322, 1292 and 1246.
m=z 283 (MþÅ, C16H10FNO3, 29), 265 (32), 238 (100), 237
(72), 208 (22), 183 (18). HRMS (MþÅ, C16H10FNO3)
calcd 283.06445, found 283.06437.
4.1.2.5. 7-Iodo-3-methoxy-2-phenylquinoline-4-carbox-
ylic acid hydrochloride 4e. Acid hydrochloride 4e was
obtained from 6-iodoisatin 3e (2.24 g, 8.20 mmol), 2-
methoxyacetophenone (1.48 g, 9.9 mmol) and KOH
(1.4 g, 25.0 mmol) in EtOH (12 mL): light brown solid,
mp 230 ꢁC (decomposition); 72% (2.61 g). 1H NMR
(DMSO-d6) d 3.59 (s, 3H), 7.55–7.58 (m, 4H), 7.92–7.97
(m, 3H), 8.48 (s, 1H). 13C NMR (DMSO-d6) d 62.4,
96.3, 124.0, 126.7, 129.3, 129.9, 130.4, 133.9, 136.9,
137.8, 138.3, 145.6, 148.3, 155.6, 167.5. IR (KBr) 3058,
2936, 1716, 1624, 1594, 1350, 1324, 1286, 1234, 1144,
1008, 724 and 698. m=z 405 (MþÅ, C17H12INO3, 100), 404
(69), 97 (21), 84 (23). HRMS (MþÅ, C17H12INO3) calcd
404.98680, found 404.98466.
4.1.3.2. 7-Fluoro-3-hydroxy-2-phenylquinoline-4-car-
boxylic acid hydrochloride 5b. Acid hydrochloride 5b
was obtained from methoxyacid 4b (5.1 g, 15.9 mmol) in
CH2Cl2 (75 mL) and BBr3 (13.8 g, 55.0 mmol) in CH2Cl2
(75 mL): orange solid, mp 228 ꢁC; 92% (4.67 g). 1H
NMR (DMSO-d6) d 7.52–7.59 (m, 4H), 7.77 (dd,
4JH5F ¼ 2:7 Hz, 3JH5H6 ¼ 9:9 Hz, 1H), 8.00–8.03 (m, 2H),
4
3
8.76 (dd, JH8H6 ¼ 6:2 Hz, JH8F ¼ 9:4 Hz, 1H). 13C
2
NMR (DMSO-d6) d 113.4 (d, JCF ¼ 20:8 Hz), 116.2,
118.6
(d,
2JCF ¼ 24:3 Hz),
123.1,
128.0
(d,
4.1.2.6. 8-Iodo-3-methoxy-2-phenylquinoline-4-carbox-
ylic acid hydrochloride 4f. Acid hydrochloride 4f was
obtained from 7-iodoisatin 3f (1.44 g, 5.29 mmol), 2-
methoxyacetophenone (0.95 g, 6.35 mmol) and KOH
(1.19 g, 21.2 mmol) in EtOH (20 mL), after extraction of
the aqueous layer with CH2Cl2 (five times), drying over
Na2SO4, filtration and concentration under vacuum:
brown solid, mp 74 ꢁC; 90% (2.09 g). 1H NMR (DMSO-
d6) d 3.71 (s, 3H), 7.35–7.42 (m, 1H), 7.52–7.61 (m, 3H),
3JCF ¼ 9:2 Hz), 129.0, 129.4, 129.8, 130.3, 130.5, 130.9,
3
137.2, 142.5 (d, JCF ¼ 11:2 Hz), 153.9, 161.0 (d,
1JCF ¼ 243 Hz), 172.0. 19F NMR (DMSO-d6) d )(115.5–
115.6) (m). IR (KBr) 3448, 1636, 1574, 1522, 1508 and
1320. m=z 283 (MþÅ, C16H10FNO3, 5), 265 (13); 239 (69),
238 (100), 211 (17). HRMS (MþÅ, C16H10FNO3) calcd
283.06445, found 283.05924.
4
3
7.96 (dd, JH5H7 ¼ 1:2 Hz, JH5H6 ¼ 9:5 Hz, 1H), 8.25–
8.28 (m, 2H), 8.32 (dd, 4JH7H5 ¼ 1:2 Hz, 3JH6H7 ¼ 7:4 Hz,
1H). 13C NMR (DMSO-d6) d 62.1, 104.8, 124.4, 125.3,
128.9, 129.5, 130.1, 133.1, 133.5, 137.0, 139.7, 148.5,
154.4, 166.9, 177.2. IR (KBr) 2936, 1718, 1342, 1196 and
760. m=z 405 (MþÅ, C17H12INO3, 36), 404 (47), 204 (19),
190 (19), 73 (100). HRMS (MþÅ, C17H12INO3) calcd
404.98680, found 404.98622.
4.1.3.3. 8-Fluoro-3-hydroxy-2-phenylquinoline-4-car-
boxylic acid hydrochloride 5c. Acid hydrochloride 5c
was obtained from methoxyacid 4c (0.69 g, 2.1 mmol) in
CH2Cl2 (12 mL) and BBr3 (1.86 g, 7.5 mmol) in CH2Cl2
(12 mL): yellow solid, mp 150 ꢁC; 75% (0.50 g). 1H NMR
(DMSO-d6) d 7.35–7.39 (m, 1H), 7.49–7.60 (m, 4H),
3
8.03–8.06 (m, 2H), 8.49 (d, JH5H6 ¼ 8:7 Hz, 1H). 13C
2
NMR (DMSO-d6) d 111.3 (d, JCF ¼ 18:2 Hz), 115.7,
4
121.3 (d, JCF ¼ 4:4 Hz), 128.0, 128.8, 128.9, 130.0,
3
130.4, 132.3 (d, JCF ¼ 11:2 Hz), 138.0, 153.0, 155.0,
4.1.3. General procedure for demethylation of 3-methoxy-
4-quinolinic acid hydrochlorides 4. BBr3 in CH2Cl2
(0.7 M, 3.6 equiv) was added dropwise in 1 h to a solu-
tion of acid 4 (0.2 M, 1 equiv) in CH2Cl2 at )78 ꢁC. After
stirring for 1.5 h at )78 ꢁC, then for 3 h at room tem-
158.6 (d, 1JCF ¼ 252:1 Hz), 172.0. 19F NMR (DMSO-d6)
d )(125.1–125.2) (m). IR (KBr) 4374, 4344, 4280, 3060,
1724, 1644, 1448 and 1238. m=z 283 (MþÅ, C16H10FNO3,
27), 265 (34); 239 (59), 238 (100), 237 (69), 208 (24).

4538
I. Bennacef et al. / Bioorg. Med. Chem. 12 (2004) 4533–4541
2
HRMS (MþÅ, C16H10FNO3) calcd 283.06445, found
283.06523.
2JCF ¼ 20:4 Hz), 118.2 (d, JCF ¼ 25:2 Hz), 122.6, 127.1
3
(d, JCF ¼ 6:1 Hz), 127.1, 128.0, 128.9, 129.1, 129.7,
3
129.9, 134.7, 137.6, 142.1, 146.3 (d, JCF ¼ 12:6 Hz),
147.9
(d,
4JCF ¼ 2:7 Hz),
156.0,
162.9
(d,
4.1.3.4. 3-Hydroxy-6-iodo-2-phenylquinoline-4-carbox-
ylic acid hydrochloride 5d. Acid hydrochloride 5d was
obtained from methoxyacid 4d (1 g, 2.5 mmol) in
CH2Cl2 (15 mL) and BBr3 (1.85 g, 7.4 mmol) in CH2Cl2
(15 mL): yellow solid, mp 236 ꢁC; 70% (0.68 g). 1H NMR
(DMSO-d6) 7.51–7.56 (m, 4H), 7.79 (d, 3JH8H7 ¼ 8:7 Hz,
1JCF ¼ 149:5 Hz), 164.8. 19F NMR (CDCl3) )(111.1–
111.2) (m). IR (KBr) 3256, 2964, 2934, 1636, 1540, 1504,
1352, 1216 and 698. m=z 414 (MþÅ, C26H23FN2O2, 47),
385 (59), 281 (54), 280 (100), 237 (38), 210 (33), 105 (81).
HRMS (MþÅ, C26H23FN2O2) calcd 414.17534, found
414.17345. Anal. (C26H23FN2O2) C, H, N.
4
3
1H), 7.85 (dd, JH7H5 ¼ 1:6 Hz, JH7H8 ¼ 8:7 Hz, 1H),
8.00–8.04 (m, 2H), 9.27 (s, 1H). 13C NMR (DMSO-d6) d
95.5, 114.0, 128.2, 128.8, 128.9, 130.4, 130.6, 130.7,
131.1, 134.0, 135.3, 153.3, 156.9, 171.9. m=z 391 (MþÅ,
C16H10INO3, 5), 347 (100), 346 (94), 219 (29), 192 (20),
165 (15), 110 (13), 85 (61). HRMS (MþÅ, C16H10INO3)
calcd 390.97055, found 390.96996.
4.1.4.3. (S)-N-(1-Phenylpropyl)-8-fluoro-3-methoxy-2-
phenylquinoline-4-carboxamide 1c. Carboxamide 1c was
obtained from methoxyacid 4c (0.43 g, 1.3 mmol): white
solid, mp 68 ꢁC; 73% (0.39 g). ½aꢂ )44.6 (c 0.5, MeOH).
D
1H NMR (CDCl3) d 1.03 (t, JHH ¼ 7:3 Hz, 3H), 1.90–
3
3
1.99 (m, 2H), 3.46 (s, 3H), 5.20 (q, JHH ¼ 8:3 Hz, 1H),
3
6.63 (d, JHH ¼ 8:5 Hz, 1H), 7.17–7.54 (m, 11H), 8.00–
4.1.4. General procedure for amidation of quinolinic acids
4–5. EDCI (2 equiv) was added slowly at )5 ꢁC to a
mixture of Et3N (2 equiv), (S)-phenylpropylamine
(1.1 equiv), HOBt (2 equiv) and acid 4 or 5 (1 equiv) in
CH2Cl2 (20–40 mL). The mixture was stirred at )5 ꢁC for
1 h, then at room temperature for 18 h. After washing
with aqueous solution of citric acid 5% (three times),
then NaHCO3 5% (three times) and finally with brine,
the organic layer was dried over MgSO4, filtered off and
concentrated under vacuum. Purification by column
chromatography (pentane/AcOEt 85:15 containing
Et3N: 1‰) yielded to quinoline carboxamides 1–2.
8.01 (m, 2H). 13C NMR (CDCl3) d 11.3, 29.6, 56.2, 62.5,
2
3
113.3 (d, JCF ¼ 18:9 Hz), 120.6 (d, JCF ¼ 4:8 Hz),
127.1, 127.3, 127.5, 127.6, 128.0, 128.9, 129.1, 129.8,
129.9,
134.4
(d,
4JCF ¼ 2:3 Hz),
135.7
(d,
3JCF ¼ 12:0 Hz), 137.6, 142.0, 149.2, 155.0, 158.5 (d,
1JCF ¼ 257:7 Hz), 164.8. 19F NMR (CDCl3) d )124.3
5
4
3
(ddd, JFH5 ¼ 3:8 Hz, JFH6 ¼ 11:3 Hz, JFH7 ¼ 15:1 Hz).
IR (KBr) 3422, 3312, 3250, 1636, 1578, 1560, 1540 and
1376. m=z 414 (MþÅ, C26H23FN2O2, 21), 385 (26), 280
(100), 237 (15), 210 (36), 105 (91). HRMS (MþÅ,
C26H23FN2O2) calcd 414.17534, found 414.17553. Anal.
(C26H23FN2O2) C, H, N.
4.1.4.4. (S)-N-(1-Phenylpropyl)-6-iodo-3-methoxy-2-
phenylquinoline-4-carboxamide 1d. Carboxamide 1d
was obtained from methoxyacid 4d (0.71 g, 1.60 mmol):
4.1.4.1. (S)-N-(1-Phenylpropyl)-6-fluoro-3-methoxy-2-
phenylquinoline-4-carboxamide 1a. Carboxamide 1a was
obtained from methoxyacid 4a (1.35 g, 4.0 mmol): white
white solid, mp 82 ꢁC; 78% (0.65 g). ½aꢂ )62.4 (c 0.5,
solid, mp 158 ꢁC; 67% (1.1 g). ½aꢂ )46.8 (c 0.5, MeOH).
D
D
1
3
3
1H NMR (CDCl3) d 1.07 (t, JHH ¼ 7:4 Hz, 3H), 1.95–
MeOH). H NMR (CDCl3) d 1.09 (t, JHH ¼ 7:38 Hz,
3
3H), 2.00–2.06 (m, 2H), 3.53 (s, 3H), 5.28 (q,
2.02 (m, 2H), 3.48 (s, 3H), 5.28 (q, JHH ¼ 8:1 Hz, 1H),
3
3JHH ¼ 7:5 Hz, 1H), 6.43 (d, JHH ¼ 7:6 Hz, 1H), 7.28–
3
6.68 (d, JHH ¼ 8:5 Hz, 1H), 7.28–7.54 (m, 10H), 7.95–
3
4
3
7.55 (m, 8H), 7.84 (d, JH8H7 ¼ 8:8 Hz, 1H), 7.91 (dd,
7.97 (m, 2H), 8.06 (dd, JHF ¼ 3:1 Hz, JH8H7 ¼ 10:0 Hz,
1H). 13C NMR (CDCl3) d 11.3, 29.5, 56.1, 62.5, 108.7 (d,
3
4JH7H5 ¼ 1:9 Hz, JH7H8 ¼ 8:8 Hz), 7.99–8.01 (m, 2H),
4
8.29 (d, JH5H7 ¼ 1:8 Hz, 1H). 13C NMR (CDCl3) d 9.8,
2
2JCF ¼ 23:8 Hz), 119.4 (d, JCF ¼ 25:9 Hz), 126.7, 126.8,
28.0, 54.8, 61.2, 92.7, 125.7, 125.9, 126.7, 127.5, 127.9,
128.2, 128.4, 130.2, 131.6, 132.3, 136.2, 136.6, 140.5,
143.0, 147.4, 154.1, 163.1. IR (KBr) m 3250, 2932, 1636,
1534 and 1346. m=z 523 (MHþÅ, C26H23IN2O2, 100), 387
(23), 362 (19), 348 (24), 119 (13). HRMS (MþÅ,
C26H23IN2O2) calcd 522.08044, found 522.08350. Anal.
(C26H23IN2O2) C, H, N.
127.1, 127.2, 128.1, 129.2, 129.5, 129.7, 132.5 (d,
3
3JCF ¼ 9:4 Hz), 133.7 (d, JCF ¼ 5:8 Hz), 137.6, 142.7,
149.1,
154.2
(d,
3JCF ¼ 2:9 Hz),
161.7
(d,
1JCF ¼ 249:2 Hz), 164.7. 19F NMR (CDCl3) d )111.6
4
3
3
(ddd, JFH8 ¼ 3 Hz, JFH5 ¼ 8 Hz, JFH6 ¼ 10 Hz). IR
(KBr) 3262, 2966, 2934, 1636, 1492, 1458, 1446, 1348,
1234, 1186 and 698. m=z 414 (MþÅ, C26H23FN2O2, 16),
385 (23), 281 (19), 280 (100), 237 (17), 149 (13), 86 (49),
84 (77). HRMS (MþÅ, C26H23FN2O2) calcd 414.17534,
4.1.4.5. (S)-N-(1-Phenylpropyl)-8-iodo-3-methoxy-2-
phenylquinoline-4-carboxamide 1f. Carboxamide 1f was
obtained from methoxyacid 4f (0.31 g, 0.70 mmol): white
1
4
found 414.17465. Anal. (C17H12FNO3ꢃ H2O) C, H, N.
4.1.4.2. (S)-N-(1-Phenylpropyl)-7-fluoro-3-methoxy-2-
phenylquinoline-4-carboxamide 1b. Carboxamide 1b was
obtained from methoxyacid 4b (2.24 g, 6.7 mmol): white
solid, mp 74 ꢁC; 78% (0.65 g). ½aꢂ )62.4 (c 0.5, MeOH).
D
3
1H NMR (CDCl3) d 1.24 (t, JHH ¼ 7:2 Hz, 3H), 1.92–
3
1.99 (m, 2H), 3.52 (s, 3H), 5.21 (q, JHH ¼ 8:3 Hz, 1H),
3
3
solid, mp 64 ꢁC; 70% (1.93 g). ½aꢂ )38.0 (c 0.5, MeOH).
6.50 (d, JHH ¼ 8:5 Hz, 1H), 7.14 (dd, JH6H5 ¼ 8:2 Hz,
3JH6H7 ¼ 7:4 Hz, 1H), 7.11–7.39 (m, 5H), 7.48–7.51 (m,
D
3
1H NMR (CDCl3) d 0.93 (t, JHH ¼ 7:3 Hz, 3H), 1.78–
3
4
3
1.91 (m, 2H), 3.33 (s, 3H), 5.09–5.13 (q, JHH ¼ 8:3 Hz,
3H), 7.70 (dd, JH5H7 ¼ 1:2 Hz, JH5H6 ¼ 8:3 Hz, 1H),
8.22–8.26 (m, 3H). 13C NMR (CDCl3) d 11.3, 29.5, 56.1,
62.6, 104.7, 125.7, 125.8, 127.11, 128.0, 128.8, 128.9,
129.1, 130.0, 130.1, 135.1, 137.4, 139.6, 142.0, 143.8,
149.3, 154.8, 164.7. IR (KBr) 2966, 1636, 1526, 1476,
3
1H), 6.65 (d, JHH ¼ 8:5 Hz, 1H), 7.22–7.40 (m, 9H),
4
3
7.56 (dd, JH8H6 ¼ 2:5 Hz, JH8F ¼ 10:0 Hz, 1H), 7.67
4
3
(dd, JH5F ¼ 6:0 Hz, JH5H6 ¼ 9:2 Hz, 1H), 7.83–7.88 (m,
2H). 13C NMR (CDCl3) 11.3, 29.5, 56.1, 62.5, 113.6 (d,

I. Bennacef et al. / Bioorg. Med. Chem. 12 (2004) 4533–4541
4539
1446, 1344, 1294, 700 and 692. m=z 522 (MþÅ,
C26H23IN2O2, 57), 493 (28), 388 (100). HRMS (MþÅ,
C26H23IN2O2) calcd 522.08044, found 522.0773. Anal.
(C26H23IN2O2) C, H, N.
0.48 mmol) in CH2Cl2 (10 mL) and BBr3 (0.250 g,
1.00 mmol) in CH2Cl2 (5 mL): white solid, mp 158 ꢁC;
75% (0.144 g). ½aꢂ )27.0 (c 0.5, MeOH). 1H NMR
D
3
(CDCl3) d 1.08 (t, JHH ¼ 7:4 Hz, 3H), 1.95–2.09 (m,
2H), 5.19 (q, 3JHH ¼ 7:7 Hz, 1H), 6.80 (d, 3JHH ¼ 8:1 Hz,
4
1H), 7.27–7.54 (m, 9H), 7.56 (dd, JH5H7 ¼ 2:4 Hz,
4.1.4.6. (S)-N-(1-Phenylpropyl)-7-iodo-3-methoxy-2-
phenylquinoline-4-carboxamide 1e. EDCI (0.52 g,
2.72 mmol) was added by portions at )5 ꢁC to a solution
of DMF (15 mL) containing quinolinic acid 4e (1.00 g,
3JH5F ¼ 10:6 Hz, 1H), 7.98–8.01 (m, 3H), 11.2 (s, 1H).
13C NMR (CDCl3) d 11.4, 29.4, 56.7, 106.6 (d,
2
2JCF ¼ 24:7 Hz), 116.7 (d, JCF ¼ 25:1 Hz), 125.0, 125.1,
127.2, 128.4, 128.6, 129.5, 129.8, 130.0, 133.8 (d,
3JCF ¼ 9:9 Hz), 136.9, 140.1, 141.2, 151.9, 161.6 (d,
1JCF ¼ 249:4 Hz), 168.1. 19F NMR (CDCl3) d )110.1
2.27 mmol)
and
N-hydroxysuccinimide
(0.31 g,
2.72 mmol). After stirring at )5 ꢁC for 1 h, then at room
temperature for 6 h, the mixture was concentrated under
vacuum. The residue was diluted in ethyl acetate and the
organic layer was washed successively with a solution of
citric acid 5% (three times), a solution of NaHCO3
(once) and brine (once), dried over MgSO4, filtrated off
and concentrated under vacuum to afford 1-{[(7-iodo-3-
methoxy-2-phenylquinolin-4-yl)carbonyl]oxy}pyrrolidine-
2,5-dione, which was purified by two consecutive
recrystallizations in a mixture of MeOH/Et2O: white
4
3
3
(ddd, JFH8 ¼ 7:1 Hz, JFH6 ¼ 14:1 Hz, JFH5 ¼ 11:8 Hz).
IR (KBr) 3746, 3530, 3448, 3966, 1624, 1586, 1560 and
1544. m=z 400 (MþÅ, C25H21FN2O2, 20), 282 (35), 265
(41), 237 (78), 135 (53), 119 (55), 91 (100), 84 (81).
HRMS (MþÅ, C25H21FN2O2) calcd 400.15868, found
400.15845. Anal. (C25H21FN2O2) C, H, N.
1
4.1.5.2. (S)-N-(1-Phenylpropyl)-7-fluoro-3-hydroxy-2-
phenylquinoline-4-carboxamide 2b. Carboxamide 2b
was obtained from methoxycarboxamide 1b (0.400 g,
0.97 mmol) in CH2Cl2 (20 mL) and BBr3 (0.500 g,
2.00 mmol) in CH2Cl2 (10 mL): white solid, mp 112 ꢁC;
solid, mp 72 ꢁC; 99% (1.13 g). H NMR (CDCl3) 2.97–
2.99 (m, 4H), 3.75 (s, 3H), 7.53–7.55 (m, 3H), 7.92–7.93
(m, 2H), 8.06–8.09 (m, 2H), 8.38 (d, 4JHH ¼ 0:8 Hz, 1H).
13C NMR (CDCl3) d 26.2, 63.0, 95.4, 123.9, 125.7, 126.0,
129.1, 129.6, 130.3, 137.0, 137.6, 139.1, 145.6, 150.7,
155.5, 161.8, 169.1. IR (KBr) 3242, 2941, 1666, 1534,
1527 and 1346. m=z 502 (MþÅ, C21H15IN2O, 28), 388
(100), 84 (48). HRMS (MþÅ, C21H15IN2O) calcd
502.00257, found 502.00169. Anal. (C21H15IN2O5) C, H,
N. A solution of this pyrrolidine-2,5-dione (0.375 g,
0.75 mmol) and (S)-phenylpropylamine (0.403 g,
3.0 mmol) in CH2Cl2 (5 mL) was refluxed for 4 h. After
washing with aqueous solution of citric acid 5% (three
times), then NaHCO3 5% (three times) and finally with
brine, the organic layer was dried over MgSO4, filtered
off and concentrated under vacuum. Purification by
column chromatography over silica gel (pentane/AcOEt
85:15) yielded to 1e: white solid, mp 72 ꢁC, 99%
81% (0.315 g). ½aꢂ )24.0 (c 0.5, MeOH). 1H NMR
D
3
(CDCl3) d 1.05 (t, JHH ¼ 7:3 Hz, 3H), 1.99–2.11 (m,
2H), 5.26 (q, 3JHH ¼ 7:7 Hz, 1H), 6.63 (d, 3JHH ¼ 7:8 Hz,
1H), 7.34–7.46 (m, 4H), 7.50–7.56 (m, 3H), 7.81 (dd,
4JH5F ¼ 2:7 Hz, 3JH5H6 ¼ 9:7 Hz, 1H), 8.50 (dd,
4JH8H6 ¼ 5:6 Hz, 3JH8F ¼ 9:3 Hz, 1H), 8.07–8.09 (m, 2H),
10.9 (sl, 1H). 13C NMR (CDCl3) d 11.3, 29.5, 56.7, 115.3
2
2
(d, JCF ¼ 20:2 Hz), 118.6 (d, JCF ¼ 24:7 Hz), 121.1,
3
123.8 (d, JCF ¼ 8:9 Hz), 127.1, 128.5, 128.7, 129.5,
3
130.0, 130.1, 137.0, 141.1, 144.1 (d, JCF ¼ 12:9 Hz),
153.6, 161.29 (d, JCF ¼ 248 Hz), 168.0. 19F NMR
1
(CDCl3) d )(114.6–114.7) (m). IR (KBr) 3318, 3058,
3028, 2964, 2932, 1624, 1578, 1216 and 698. m=z 400
(MþÅ, C25H21FN2O2, 24), 282 (52), 265 (58), 237 (41),
119 (63), 106 (39), 91 (100). HRMS (MþÅ, C25H21FN2O2)
(0.390 g). ½aꢂ )29.4 (c 0.5, MeOH). 1H NMR (CDCl3) d
D
3
1.07 (t, JHH ¼ 7:4 Hz, 3H), 2.00–2.04 (m, 2H), 3.52 (s,
3H), 5.28 (q, 3JHH ¼ 8:2 Hz, 1H), 6.46 (d, 3JHH ¼ 8:5 Hz,
calcd
(C25H21FN2O2) C, H, N.
400.15868,
found
400.15811.
Anal.
1H), 7.29–7.41 (m, 1H), 7.42–7.44 (m, 4H), 7.51–7.53
3
(m, 3H), 7.63 (d, JH5H6 ¼ 8:9 Hz, 1H), 7.77 (d,
3JH6H5 ¼ 8:9 Hz, 1H), 7.98–8.00 (m, 2H), 8.57 (d,
4JH8H6 ¼ 1:6 Hz, 1H). 13C NMR (CDCl3) d 9.9, 27.9,
54.6, 60.9, 93.5, 123.3, 124.6, 125.7, 126.6, 127.4, 127.7,
128.3, 128.5, 133.0, 134.9, 136.0, 137.2, 140.6, 144.4,
147.1, 154.1, 163.2. IR (KBr) 3238, 3224, 3144, 3056,
3028, 2962, 2932, 2854, 1632, 1544, 1540 and 696. m=z
522 (MþÅ, C26H23IN2O2, 22), 493 (26), 388 (100), 84 (58).
HRMS (MþÅ, C26H23IN2O2) calcd 522.08044, found
522.07837. Anal. (C26H23IN2O2) C, H, N.
4.1.6. (S)-N-(1-Phenylpropyl)-8-fluoro-3-hydroxy-2-phen-
ylquinoline-4-carboxamide 2c. Carboxamide 2c was ob-
tained from methoxycarboxamide 1c (0.200 g,
0.48 mmol) in CH2Cl2 (10 mL) and BBr3 (0.250 g,
1.00 mmol) in CH2Cl2 (5 mL): white solid, mp 136 ꢁC;
65% (0.126 g). ½aꢂ )7.6 (c 0.5, MeOH). 1H NMR
D
3
(CDCl3) d 1.00 (t, JHH ¼ 7:4 Hz, 3H), 2.00–2.09 (m,
3
3
2H), 5.25 (q, JHH ¼ 7:6 Hz), 6.74 (d, JHH ¼ 8:0 Hz,
3
1H), 7.21–7.52 (m, 10H), 7.78 (d, JH5H6 ¼ 8:6 Hz, 1H),
8.11–8.13 (m, 2H), 11.4 (sl, 1H). 13C NMR (CDCl3) d
4.1.5. Synthesis of 3-hydroxy-4-quinoline carboxamides 2
by demethylation of 3-methoxy-4-quinoline carboxamides
1. Demethylation reactions from 1 were carried out
according to the procedure described in the quinolinic
acid series.
2
11.3, 29.5, 53.7, 111.5 (d, JCF ¼ 19:4 Hz), 116.3, 117.6
4
(d, JCF ¼ 4:8 Hz), 126.1, 127.1, 128.4, 128.6, 128.8 (d,
3JCF ¼ 8:9 Hz), 129.5, 130.0, 130.3, 133.3 (d,
3JCF ¼ 11:5 Hz), 137, 141.1, 152.3, 152.5, 159.4 (d,
1JCF ¼ 258 Hz), 168.1. 19F NMR (CDCl3) d )(124.3–
124.4) (m). IR (KBr) 3448, 3442, 3384, 1734, 1718, 1648,
1624, 1578, 1570, 1560, 1540 and 1534. m=z 400 (MþÅ,
C25H21FN2O2, 18), 282 (348), 265 (42), 237 (79), 135
(54), 119 (58), 91 (100), 84 (59). HRMS (MþÅ,
4.1.5.1. (S)-N-(1-Phenylpropyl)-6-fluoro-3-hydroxy-2-
phenylquinoline-4-carboxamide 2a. Carboxamide 2a
was obtained from methoxycarboxamide 1a (0.200 g,

4540
I. Bennacef et al. / Bioorg. Med. Chem. 12 (2004) 4533–4541
C25H21FN2O2) calcd 400.15868, found: 400.15886. Anal.
(C25H21FN2O2) C, H, N.
91 (70), 84 (100). HRMS (MþÅ, C25H21IN2O2) calcd
508.06479, found: 508.06466.
4.2. Biology
4.1.6.1. (S)-N-(1-Phenylpropyl)-6-iodo-3-hydroxy-2-
phenylquinoline-4-carboxamide 2d. Carboxamide 2d
was obtained from methoxycarboxamide 1d (0.050 g,
0.0958 mmol) in CH2Cl2 (6 mL) and BBr3 (0.100 g,
0.398 mmol) in CH2Cl2 (3 mL) after purification by
column chromatography (pentane/AcOEt 90:10): white
Receptor binding assays were performed with crude
membranes from Chinese hamster ovary (CHO) cells
expressing the human NK-3 receptor (hNK-3r-CHO)
purchased from Amersham Biosciences or with CHO
cells stably transfected with the human NK-1 receptor
(hNK-1r-CHO) cDNA (generous gift from Dr. J. Grassi
and Prof. J. Y. Couraud, CEA Saclay) plated in 24-well
plates. [3H]-Senktide and [125I]-Bolton-Hunter-substance
P ([125I]-BH-SP) used as radioligands were supplied by
Perkin Elmer Life Sciences. The time necessary to reach
the steady state was previously determined by kinetic
studies; the radioligand dissociation constant (Kd) and
the maximum number of binding sites (Bmax) were ob-
tained by saturation binding experiments.
solid, mp 85 ꢁC; 64% (0.031 g). ½aꢂ )26.4 (c 0.5,
D
3
MeOH). 1H NMR (CDCl3) d 1.07 (t, JHH ¼ 7:4 Hz,
3
3H), 2.01–2.10 (m, 2H), 5.25 (q, JHH ¼ 7:6 Hz, 1H),
6.67 (d, 3JHH ¼ 8:2 Hz, 1H), 7.37–7.53 (m, 8H), 7.82 (dd,
4JH7H5 ¼ 1:6 Hz, 3JH7H8 ¼ 8:7 Hz, 1H), 7.86 (d,
3JH8H7 ¼ 8:7 Hz, 1H), 8.08 (m, 2H), 8.45 (d,
4JH5H7 ¼ 1:1 Hz, 1H). 13C NMR (CDCl3) d 11.3, 29.6,
56.6, 94.9, 115.0, 126.0, 127.0, 128.4, 128.7, 129.6, 130.0,
130.1, 131.2, 132.9, 135.7, 136.9, 141.2, 142.0, 151.9,
152.6, 153.0, 167.8. IR (KBr) 2852, 1636, 1576, 1492,
1294, 1182 and 698. m=z 508 (MþÅ, C25H21IN2O2, 22),
390 (33), 373 (37), 149 (54), 85 (79), 72 (100). HRMS
(MþÅ, C25H21IN2O2) calcd 508.06479, found: 508.06158.
4.2.1. Radioligand binding assays. Briefly, for hNK3-r
competition studies, hNK-3r-CHO membranes (ꢀ7 lg
of protein) were incubated with 3 nM [3H]-senktide in a
total volume of 170 lL of 50 mM Tris HCl (pH 7.4),
3 mM MnCl2, 1 lM phosphoramidon, 40 lg/mL baci-
tracin and 0.5% bovine serum albumin (BSA), with or
without various concentrations of tested compounds,
for 60 min at 25 ꢁC. Incubations were stopped by rapid
filtration with a Brandell tissue harvester through
Whatman GF/C filters that were presoaked for at least
60 min in 0.5% BSA. Membranes were washed three
times with ice-cold 50 mM Tris HCl (pH 7.4) and bound
radioactivity (dpm) was determined by using liquid
scintillation counting.
4.1.6.2. (S)-N-(1-Phenylpropyl)-7-iodo-3-hydroxy-2-
phenylquinoline-4-carboxamide 2e. Carboxamide 2e was
obtained from methoxycarboxamide 1e (0.193 g,
0.37 mmol) in CH2Cl2 (10 mL) and BBr3 (0.370 g,
1.47 mmol) in CH2Cl2 (6 mL): white solid, mp 112 ꢁC;
67% (0.126 g). ½aꢂ )6.6 (c 0.5, MeOH). 1H NMR
D
3
(CDCl3) d 1.01 (t, JHH ¼ 7:4 Hz, 3H), 1.94–2.10 (m,
2H), 5.20 (q, 3JHH ¼ 7:7 Hz, 1H), 6.67 (d, 3JHH ¼ 8:1 Hz,
1H), 7.33–7.42 (m, 5H), 7.48–7.52 (m, 3H), 7.64 (d,
3JH5H6 ¼ 8:9,
1H),
7.73
(dd,
4JH6H8 ¼ 1:8 Hz,
3JH6H5 ¼ 9:0 Hz, 1H), 8.03–8.06 (m, 2H), 8.48 (d,
4JH8H6 ¼ 1:7 Hz, 1H), 11.17 (sl, 1H). 13C NMR (CDCl3)
d 11.3, 29.4, 56.6, 91.4, 116.5, 123.3, 123.4, 127.1, 128.5,
128.6, 129.5, 130.0, 130.1, 136.8, 137.0, 140.0, 141.0,
143.8, 151.6, 153.0, 167.9. IR (KBr) 3854, 3448, 3344,
1624, 1560 and 698. m=z 508 (MþÅ, C25H21IN2O2, 12),
390 (33), 373 (26), 149 (30), 119 (36), 91 (68), 84 (100).
HRMS (MþÅ, C25H21IN2O2) calcd 508.06479, found:
508.06581. Anal. (C25H21IN2O2) C, H, N.
For hNK-1r competition studies, CHO cells expressing
hNK-1r (2 · 105 cells/well) were cultured as previously
described28 and washed three times with Krebs buffer
(120 mM NaCl, 4.8 mM KCl, 1.2 mM MgSO4, 70 mM
NaH2PO4, 1.6 mM CaCl2, 0.04 mM BSA, 30 mg/mL
bacitracin and 6 g/L glucose). Cells were then incubated
for 100 min at room temperature (until equilibrium) in
presence of 15 pM [125I]-BH-SP and increasing concen-
trations of cold competing ligands in a final volume of
200 lL. Finally, cells were washed three times in cold
Krebs buffer, lysed with 0.1% Triton X100 containing
1 mg/mL BSA overnight at 4 ꢁCꢁC and the radioactivity
was counted with a Cobra Auto-Gamma counter ard).
4.1.6.3. (S)-N-(1-Phenylpropyl)-8-iodo-3-hydroxy-2-
phenylquinoline-4-carboxamide 2f. Carboxamide 2e was
obtained from methoxycarboxamide 1e (0.034 g,
0.065 mmol) in CH2Cl2 (5 mL) and BBr3 (0.400 g,
1.59 mmol) in CH2Cl2 (10 mL): white solid, mp 74 ꢁC;
73% (0.024 g). ½aꢂ )24.8 (c 0.5, MeOH). 1H NMR
Concentration–response curves for each compound,
were run using duplicate samples in at least two inde-
pendent experiments following curve-fitting procedures
in SigmaPlot. Specific binding was determined by sub-
tracting total binding from nonspecific binding, which
was assessed as the binding in the presence of 10 lM
NKB or SP. Percent inhibition of specific binding was
determined for each compound concentration and the
IC50 value defined as the concentration required to in-
hibit 50% of the specific binding, obtained from con-
centration–response curves. Values presented in Table 1
were the inhibition constants (Ki), which were calculated
D
3
(CDCl3) d 1.00 (t, JHH ¼ 7:4 Hz, 3H), 1.95–2.09 (m,
2H), 5.19 (q, 3JHH ¼ 7:7 Hz, 1H), 6.64 (d, 3JHH ¼ 7:9 Hz,
3
1H), 7.19 (t, JH6H5 ¼ 3JH6H7 ¼ 8:1 Hz, 1H), 7.25–7.42
3
(m, 5H), 7.48–7.54 (m, 3H), 7.96 (d, JH5H6 ¼ 8:2 Hz,
4
3
1H), 8.18 (dd, JH7H5 ¼ 0:7 Hz, JH7H6 ¼ 8:1 Hz, 1H),
8.34 (m, 2H), 11.34 (sl, 1H). 13C NMR (CDCl3) d 10.9,
29.1, 56.3, 106.5, 116.4, 122.3, 124.1, 126.7, 128.0, 128.2,
129.0, 129.1, 129.8, 130.2, 136.4, 137.2, 140.7, 141.1,
151.8, 151.9, 167.6. IR (KBr) 2958, 2954, 2852, 2358,
1716, 1700, 1684, 1652, 1622 and 698. m=z 508 (MþÅ,
C25H21IN2O2, 14), 390 (33), 373 (20), 149 (32), 119 (36),

I. Bennacef et al. / Bioorg. Med. Chem. 12 (2004) 4533–4541
4541
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