Synthesis of potential Rho-kinase inhibitors based on the chemistry of an original heterocycle: 4,4-Dimethyl-3,4-dihydro-1H-quinolin-2-one

Article abstract of DOI:10.1016/j.ejmech.2007.11.010

A new series of substituted 4,4-dimethyl-3,4-dihydro-1H-quinolin-2-one have been prepared via condensation of 3,3-dimethylacryloyl chloride with aniline. Details of synthetic procedures are shown. Our aim was to investigate the potency of our original het

Full text of DOI:10.1016/j.ejmech.2007.11.010

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European Journal of Medicinal Chemistry 43 (2008) 1730e1736
http://www.elsevier.com/locate/ejmech
Short communication
Synthesis of potential Rho-kinase inhibitors based on the chemistry of
an original heterocycle: 4,4-Dimethyl-3,4-dihydro-1H-quinolin-2-one
a
Marie-Anne Letellier , Jerome Guillard , Daniel-Henri Caignard , Gilles Ferry ,
a
b
c
´ ˆ
Jean A. Boutin c, Marie-Claude Viaud-Massuard a,
*
a Laboratoire de Chimie Organique, EA 3857, UFR des Sciences Pharmaceutiques, 31 Avenue Monge, 37200 Tours, France
b Etudes Exte´rieures et Alliances Strate´giques, Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, France
c Pharmacologie Mole´culaire et Cellulaire, Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, France
Received 5 June 2007; received in revised form 5 November 2007; accepted 12 November 2007
Available online 23 November 2007
Abstract
A new series of substituted 4,4-dimethyl-3,4-dihydro-1H-quinolin-2-one have been prepared via condensation of 3,3-dimethylacryloyl chlo-
ride with aniline. Details of synthetic procedures are shown. Our aim was to investigate the potency of our original heterocycle in the inhibition
of the Rho-kinase enzyme, known to be of major importance in the cascade reactions leading to arterial hypertension. Biological activity for the
seven compounds has been investigated and is presented.
Ó 2007 Elsevier Masson SAS. All rights reserved.
Keywords: Rho-kinase inhibitors; Hypertension; Heterocyclic chemistry
1. Introduction
smooth-muscle contraction by inhibiting Ca2þ sensitization
[6e8], and HA-1077, an isoquinolinesulfonamide derivative
which has an antispatic effect on the cerebral artery [9e11]
(Fig. 1).
Hypertension, commonly referred to as ‘‘high blood pres-
sure’’, is a medical condition where the blood pressure is
chronically elevated. It is one of the most important cardio-
vascular risk factors (as diabetes mellitus, dyslipidemia and
tobacco) all over the world. Twenty percentage of the indus-
trial population is concerned according to the World Health
Organization.
This disease is defined by a rise in the blood pressure in the
arteries due to the abnormal contraction of the smooth muscle.
The contraction being regulated by the cytosolic calcium con-
centration to which the Rho/Rho-kinase intracellular pathway
is associated, designing compounds that inhibit the enzyme
seem to be of great interest [1e5]. Different kinds of mole-
cules have already been studied. Two of most effective inhib-
itors of Rho-kinase are now considered as the research leaders:
Y-27632, a pyridine derivative which selectively inhibits
Considering these two molecules Takami et al. [12] studied
Rho-kinase ligand-binding site. They described it as a three re-
gion (A, F and D) pocket. The A region, composing the bot-
tom of the cavity, is flat and possesses an amine function
(NH of Met 167) allowing the formation of a hydrogen bond
with any heteroatom correctly oriented. The F region is spher-
ical and relatively spacious. Docking simulation indicated that
several chemical fragments could occupy this space especially
planar linkers such as amide or urea moieties. The third region
(D region) being also hydrophobic and cleft-like in shape, sub-
stituents should preferably be aromatic (Fig. 2).
Inspired by Takami et al.’s work [13,14], we elaborated new
potential Rho-kinase inhibitors investigating the synthesis of
4,4-dimethyl-3,4-dihydro-1H-quinolin-2-one [15]. This 6e6
ring system should enable the substrate to settle Rho-kinase’s
active site twice by the presence of its two hydrogen acceptors.
Hopefully thinking of imitating the HA-1077 sequence we
* Corresponding author. Tel.: þ33 2 47367227; fax: þ33 2 47367229.
E-mail address: mcviaud@univ-tours.fr (M.-C. Viaud-Massuard).
0223-5234/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2007.11.010

M.-A. Letellier et al. / European Journal of Medicinal Chemistry 43 (2008) 1730e1736
1731
O
H
N
NH2
O
i
HN
NH
N
N
S
O
O
H2N
1
N
ii
Y-27632
HA-1077
Fig. 1. Two most effective inhibitors of Rho-kinase.
H
N
H
N
O
O
iii
also wished to evaluate the relevance of the same sulfonamide
linker.
ClO2S
3
2
2. Chemistry
Scheme 1. Synthesis of 4,4-dimethyl-2-oxo-1,2,3,4-tetrahydroquinoline-6-sul-
fonyl chloride. Reagents: (i) 3,3-dimethylacryloyl chloride, pyridine; (ii)
AlCl3, DCM; (iii) ClSO3H.
The sulfonyl chloride key intermediate was synthesized in
three steps starting from the commercially available aniline.
Condensation of 3,3-dimethylacryloyl chloride in pyridine
yielded the desired amide 1 [16] which was further cyclized
by a Friedel and Crafts reaction [17]. Chlorosulfonylation
of the quinolinone 2 was then carried out under rather drastic
conditions: direct introduction into pure chlorosulfonic acid
(Scheme 1).
The last step to afford the desired sulfonamide derivatives
was carried out either in dichloromethane with triethylamine
or by using pyridine as the solvent as well as the required base.
It is noteworthy we investigated among others the insertion
of 2-methylpiperazine described by Hidaka [18,19] as a more
rigid configuration of the homopiperazine moiety of HA-1077
(Scheme 2).
also elaborated as shown in Scheme 3. Classical methylation re-
action provided the expected product starting from the amide 2.
Several attempts were necessary to find the right conditions in
order to afford the correctly substituted nitro-intermediate 11.
First cyclization of 3-methyl-N-(4-nitrophenyl)but-2-enamide
was investigated but never we were able to achieve the reaction
within the conditions previously elaborated. Nitration of the in-
termediate 10 was therefore carried out in an inert solvent
where the nitronium ion NOþ2 is directly generated by concen-
trated nitric acid (Scheme 3).
The best conditions were identified as being the addition of
nitric acid at 0 ꢀC in dichloromethane. The reduction was next
carried out under rather mild conditions with tin(II) chloride
dihydrate to afford the amine derivative 12 in a good yield.
Treatment with a pretty bulky and flat sulfonyl chloride led
to the desired sulfonamide 13 (Scheme 4).
In order to investigate the relevance of the linker’s sequence,
the synthesis of a molecule containing a switched linker was
3. Biological activity
The seven synthesized compounds have been studied for
possible future biological functions.
3.1. Purification of the recombinant Rho-kinase
The plasmid encoding for human Rho-kinase as a fusion
protein with glutathione-S-transferase was a generous gift
from Prof. Pierre Pacaud (Nantes). The protein was expressed
by baculovirus infection of the Tn5 insect cell line. Fifty mil-
liliters of Tn5 cells (1 L of culture) was solubilized in 150 mL
of extraction buffer (20 mM TriseHCl, pH 7.2, 10 mM glyc-
erophosphate, 10 mM MgCl2, 100 mM EGTA, 1 mM DTT, in-
cluding complete RocheÒ protease inhibitor cocktail). The
suspension was sonicated three times for 15 s in cold. The ex-
tract was then centrifuged (10,000g, 15 min, 4 ꢀC) and the pel-
let thereof was re-suspended in the same buffer, sonicated and
centrifuged as above. Both supernatants were saved and used
as material for the purification of the enzyme. In brief, affinity
chromatography was achieved on a glutathioneesepharose
column equilibrated in the extraction buffer. Four hundred
Fig. 2. Ligand-binding pocket of Rho-kinase homology model. A docking
model of ATP is shown. Hydrogen bonds between N1 of ATP and HN of
Met167, and the amino group at the 6-position and C]O of Glu165 are indi-
cated as dashed lines [12].

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M.-A. Letellier et al. / European Journal of Medicinal Chemistry 43 (2008) 1730e1736
H
N
HN
N
O
HN
ii
NH
N
Het
N
NH
N
N
S
63 %
N
61 %
i
O2
ClO2S
O2S
Het
Cl
3
4
9
HN
N
HN
NH
98%
Cl
HN
N
HN
N
97 %
i
i
NH
i
90 %
57 %
N
O2S
Het
Cl
8
O2S
Het
N
N
N
N
N
N
O2S
Het
O2S
Het
Cl
5
6
7
Scheme 2. Synthesis of 4,4-dimethyl-2-oxo-1,2,3,4-tetrahydroquinoline-6-sulfonamide derivatives. Reagents: (i) pyridine; (ii) Et3N, DCM; (iii) DCM.
milliliters of extraction fluid, obtained above, was chromato-
graphed in a 100 mL column at 4 mL/min flow speed. The col-
umn was then developed with a rinsing buffer (extraction
buffer supplemented with 150 mM NaCl) and then with an
elution buffer (20 mM TriseHCl, pH 7.2, 10 mM glycero-
phosphate, 10 mM MgCl2, 100 mM EGTA, 1 mM DTT, and
10 mM GSH). The elution fractions, containing the Rho-
kinase activity, were then concentrated on PEG 20000 bead
bed, pooled and snap frozen at ꢁ80 ꢀC until further use.
with or without the tested compound solubilized in pure
DMSO at a final concentration leading to a DMSO concentra-
tion not exceeding 2%. The reaction was allowed to continue
for 15 min and stopped by eliminating the fluids from the wells.
The wells were then washed four times with PBS buffer with
0.01% Tween 20. The radioactivity associated with the substrate
in the plates was evaluated by counting in a TopCount-NXT
(Packard) counter.
4. Results and discussion
3.2. Measurement of Rho-kinase catalytic activity
In order to validate the relevance of our tests we also eval-
uated the IC50 of the most effective compound among Takami’s
molecules. Despite the introduction of various substituents on
our original heterocycle and the inversion into the linker’s
chain none of our compounds showed significant activity for
the inhibition of Rho-kinase.
The phosphorylation of the biotinylated substrate S6 (bio-
tinyl Ala-Lys-Arg-Arg-Arg-Leu-Ser-Ser-Leu-Arg-Ala) was per-
formed in the wells of a 96-well plate coated with streptavidin
(Flasplate), in which the enzyme was added with 1 mM ATP
containing 0.2 mCi of [g-33P]ATP in a total volume of 100 mL,
5. Conclusion
R
N
O
To conclude, we described the synthesis of seven analogs of
Rho-kinase inhibitors which possess an original heterocyclic
skeleton. Unfortunately, among all the molecules synthesized
and tested none showed significant activity. Neither our novel
4,4-dimethyl-3,4-dihydro-1H-quinolin-2-one heterocycle nor
the introduction of the sulfonamide linker improved affinity
for the Rho-kinase binding site. Another novel heterocycle is
currently under investigation whose results will be reported
elsewhere.
NO2
11 R = CH3
Cyclization
i
Nitration
ii
H
N
O
N
6. Experimental
O
NO2
6.1. Chemicals
3-methyl-N-(4-nitrophenyl)but-2-enamide
10
Starting materials, aniline, 3,3-dimethylacryloyl chloride,
chlorosulfonic acid, 1-(2-pyridyl) piperazine, N-(3,5-dichloro-
phenyl)piperazine, N-phenylpiperazine, 1-benzylpiperazine,
homopiperazine, 2-methylpiperazine, naphthalene-1-sulfonyl
R = H or CH3
Scheme 3. Study for the achievement of the intermediate 11. Reagents and
conditions: (i) AlCl3, DCM; (ii) HNO3, DCM, 0 ꢀC.

M.-A. Letellier et al. / European Journal of Medicinal Chemistry 43 (2008) 1730e1736
1733
H
N
O
O
O
N
N
i
ii
quantitative
63%
O2N
2
10
11
iii 84%
SO2Cl
O
N
O
N
O
S
iv
92%
N
H
H2N
O
13
12
Scheme 4. Synthesis of the switched linker compound. Reagents and conditions: (i) MeI, NaH, DMF; (ii) HNO3, DCM, 0 ꢀC; (iii) SnCl2$2H2O, EtOH; (iv)
pyridine.
chloride, tin chloride dihydrate and solvents (chloroform, pe-
troleum ether, diethyl ether, ethyl acetate, dichloromethane,
pyridine, heptane, triethylamine, methanol, 2-propanol and
ethanol) were all purchased from either Aldrich Ltd., Acros
or VWR and were used as received.
(t, 2H, J3e4 ¼ J3e2 ¼ J5e4 ¼ J5e6 ¼ 7.5 Hz, H3 þ H5); 7.52 (d,
2H, J2e3 ¼ J6e5 ¼ 7.5 Hz, H2 þ H6). 13C NMR (CDCl3)
d (ppm): 20.4 (C11 or C12); 27.8 (C12 or C11); 119.0 (C9);
120.2 (C2 þ C6); 124.4 (C4); 129.4 (C3 þ C5); 138.6 (C1);
153.9 (C10); 165.5 (C8). MS (IC): m/z ¼ 175 [M].
Under an inert atmosphere, a solution of 3-methyl-but-2-
enoic acid phenylamide 1 (5 g, 28.5 mmol) in anhydrous di-
chloromethane (50 mL) was cooled down to 0 ꢀC. Aluminum
chloride (15.2 g, 114 mmol) was added portionwise for at least
1 h period of time and the mixture was allowed to warm to
room temperature. The reaction was completed within the
hour. The mixture was then poured onto ice and the product
was extracted with diethyl ether. The organic layers were com-
bined and successively washed with water, a saturated solution
of sodium hydrogenocarbonate and a saturated solution of so-
dium chloride. They were then dried over MgSO4 and the sol-
vents were removed under reduced pressure. Recrystallisation
in absolute ethanol provided 4,4-dimethyl-3,4-dihydro-1H-
quinolin-2-one 2 as a white solid.
6.2. Equipment
Melting points are uncorrected. MS results were recorded
on a PerkineElmer SCIEX API 3000 spectrometer. Reaction
products were purified, unless otherwise notified, by flash
chromatography using silica gel (Merck 230e400 mesh). An-
alytical TLC was carried out on silica gel F254 plates. All an-
hydrous reactions were performed in oven-dried glassware
under an atmosphere of argon.
1H NMR and 13C NMR spectra were recorded on a Bruker
200 MHz using CDCl3 as a solvent. The solvent characteristic
signals were observed, respectively, as a singlet at 7.26 ppm
and as a triplet at 77.1 ppm.
1
Yield 90%. M.p. 111e112 ꢀC (lit. 116 ꢀC [8]). H NMR
6.3. Compound synthesis and analyses
(CDCl3) d (ppm): 1.33 (s, 6H, 2 ꢂ CH3); 2.50 (s, 2H, H3);
6.83 (dd, 1H, J5e6 ¼ 7.6 Hz, J5e7 ¼ 1.3 Hz, H5); 7.05 (ddd,
1H, J7e6 ¼ 7.5 Hz, J7e8 ¼ 7.5 Hz, J7e5 ¼ 1.3 Hz, H7); 7.18
(dd, 1H, J6e5 ¼ 7.6 Hz, J6e7 ¼ 7.5 Hz, H6); 7.29 (d, 1H,
J8e7 ¼ 7.5 Hz, H8); 8.84 (s, 1H, NH ). 13C NMR (CDCl3)
d (ppm): 28.1 (2 ꢂ CH3); 34.4 (C4); 45.7 (C3); 116.2 (C8);
124.0 (C6); 124.9 (C5); 127.9 (C7); 132.9 (Ca); 136.2 (Cb);
171.5 (C2). MS (IC): m/z ¼ 175 [M].
6.3.1. General procedure for the preparation of
4,4-dimethyl-2-oxo-1,2,3,4-tetrahydroquinoline-6-
sulfonyl chloride: synthesis of compounds 1e3
Under an atmosphere of argon, aniline (5 g, 53.7 mmol)
was dissolved in dry pyridine (15 mL), cooled down to 0 ꢀC
and treated with 3,3-dimethylacryloyl chloride (7.17 mL,
64.4 mmol). After 1 h at room temperature, the reaction was
completed. A solution of HCl 1 N was added and the resulting
Chlorosulfonic acid (0.38 mL, 5.71 mmol) was cooled
down to 0 ꢀC under an inert atmosphere. 4,4-Dimethyl-3,4-
dihydro-1H-quinolin-2-one 2 was added portionwise over
a 15 min period. The reaction was allowed to warm to room
temperature and stirred for 1 h. The mixture was then poured
onto ice and extracted with ethyl acetate. The organic layer
was successively washed with a saturated solution of sodium
hydrogenocarbonate and a saturated solution of sodium
chloride. After drying the organic extract over anhydrous
MgSO4, evaporation of the solvent afforded the desired
orange precipitate was filtered on Buchner filter and washed
¨
with water and heptane. Recrystallisation was then carried
out in 2-propanol and 3-methyl-but-2-enoic acid phenylamide
1 was isolated as a white solid.
Yield 95%. M.p. 129e130 ꢀC (lit. 129e130 ꢀC [7]). 1H NMR
(CDCl3) d (ppm): 1.90 (d, 3H, J11e9 ¼ 0.9 Hz, H11); 2.21 (d, 3H,
J12e9 ¼ 0.9 Hz, H12); 5.70 (t, 1H, J9e11 ¼ J9e12 ¼ 0.9 Hz, H9);
7.07 (t, 1H, J4e3 ¼ J4e5 ¼ 7.5 Hz, H4); 7.15 (s, 1H, NH ); 7.30

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M.-A. Letellier et al. / European Journal of Medicinal Chemistry 43 (2008) 1730e1736
4,4-dimethyl-2-oxo-1,2,3,4-tetrahydroquinoline-6-sulfonyl
chloride 3 as a beige solid used without further purification.
J13ae14b ¼ 5.6 Hz, H13 þ H14); 6.90e6.98 (m, 3H, J17e18
¼
J21e20 ¼ 8.5 Hz, H17 þ H19 þ H21); 7.02 (d, 1H, J8e7 ¼ 8.2
1
Yield 70%. M.p. 177e178 ꢀC. H NMR (CDCl3) d (ppm):
Hz, H8); 7.30 (dd, 2H, J18e17 ¼ J20e21 ¼ 8.5 Hz, J18e19 ¼
1.45 (s, 6H, 2 ꢂ CH3); 2.63 (s, 2H, H3); 7.07 (d, 1H,
J8e7 ¼ 8.4 Hz, H8); 7.90e7.98 (m, 2H, H5 þ H7); 9.55 (s,
1H, NH ). 13C NMR (CDCl3) d (ppm): 27.9 (2 ꢂ CH3); 34.8
(C4); 44.9 (C3); 116.9 (C8); 124.6 (C5); 127.9 (C7); 134.2
(C6); 139.2 (Cb); 142.5 (Ca); 171.6 (C2). MS (IC): m/z ¼ 274
[M þ 1].
J20e19 ¼ 7.4 Hz, H18 þ H20); 7.67 (dd, 1H, J7e8 ¼ 8.2 Hz,
J7e5 ¼ 1.9 Hz, H7); 7.72 (d, 1H, J5e7 ¼ 1.9 Hz, H5). 13C
NMR (CDCl3) d (ppm): 28.0 (2 ꢂ CH3); 34.6 (C4); 45.1
(C3); 46.4 (C13); 49.6 (C14); 116.6 (C19); 117.3 (C17 þ C21);
121.3 (C8); 125.0 (C5); 128.3 (C7); 129.7 (C18 þ C20); 130.5
(C6); 133.7 (Ca); 140.6 (Cb); 151.0 (C16); 171.7 (C2). MS
(IC): m/z ¼ 399 [M].
6.3.2. General procedure for the preparation
of 4,4-dimethyl-2-oxo-1,2,3,4-tetrahydroquinoline-
6-sulfonamide derivatives 4e9
6.3.2.1.4. 6-(4-Benzylpiperazin-1-ylsulfonyl)-4,4-dimethyl-
3,4-dihydroquinolin-2(1H )-one 7. Beige solid. Yield 57%.
M.p. 95e96 ꢀC. 1H NMR (CDCl3) d (ppm): 1.40 (s, 6H,
2 ꢂ CH3); 2.55e2.60 (m, 6H, H3 þ H14); 3.04e3.09 (m, 4H,
H13); 3.53 (s, 2H, H16); 6.97 (d, 1H, J8e7 ¼ 8.2 Hz, H8);
7.29e7.33 (m, 5H, H18eH22); 7.61 (dd, 1H, J7e8 ¼ 8.2 Hz,
J7e5 ¼ 1.9 Hz, H7); 7.68 (d, 1H, J5e7 ¼ 1.9 Hz, H5); 9.03 (s,
1H, NH ). 13C NMR (CDCl3) d (ppm): 28.0 (2 ꢂ CH3); 34.6
(C4); 45.1 (C3); 46.4 (C13); 52.5 (C14); 63.1 (C16); 116.4
(C8); 125.1 (C5); 127.8 (C20); 128.2 (C7); 128.8 (C19 þ C21);
129.6 (C18 þ C22); 130.6 (C6); 133.6 (Ca); 137.7 (C17);
140.4 (Cb); 171.4 (C2). MS (IC): m/z ¼ 413 [M].
6.3.2.1. General procedure for compounds 4e7 [20]. Under
an argon atmosphere, the appropriate amine (0.36 mmol)
was dissolved in dry pyridine (3 mL). The sulfonyl chloride
derivative 3 (0.1 g, 0.36 mmol) was added portionwise and
the reaction mixture was allowed to stir at room temperature
until the reaction was completed (0.5e4 h). Then water was
added and the product was extracted with ethyl acetate. The
organic layers were washed several times with a solution of
HCl 1 N and finally with a saturated solution of sodium
chloride. The extract was dried over anhydrous MgSO4
and solvents were removed under reduced pressure. Recrys-
tallisation in 2-propanol afforded the desired sulfonamides
4e7.
6.3.2.2. 6-(1,4-Diazepan-1-ylsulfonyl)-4,4-dimethyl-3,4-dihy-
droquinolin-2(1H )-one 8. Under an inert atmosphere,
homopiperazine (73 mg, 0.73 mmol) was dissolved in dry di-
chloromethane (5 mL) and the reaction mixture was cooled
down to 0 ꢀC. The sulfonyl chloride 3 (0.1 g, 0.36 mmol)
was also dissolved in dry dichloromethane (5 mL), cooled
down to 0 ꢀC and canulated over the homopiperazine solution.
The reaction mixture was allowed to warm to room tempera-
ture and stirred for 0.5 h. After removal of the solvent under
reduced pressure, the crude product was purified by column
chromatography on silica gel (DCM/MeOH).
Beige solid. Yield 98%. M.p. 177e178 ꢀC. 1H NMR
(CDCl3) d (ppm): 1.41 (s, 6H, 2 ꢂ CH3); 1.76 (s, 1H, NH );
1.84e1.90 (m, 2H, H14); 2.57 (s, 2H, H3); 2.94e3.04 (m,
4H, H15 þ H17); 3.34e3.45 (m, 4H, H13 þ H18); 6.95 (d, 1H,
J8e7 ¼ 8.3 Hz, H8); 7.66 (dd, 1H, J7e8 ¼ 8.3 Hz, J7e5 ¼ 2.0
Hz, H7); 7.75 (d, 1H, J5e7 ¼ 2.0 Hz, H5); 8.87 (s, 1H, NH ).
13C NMR (CDCl3) d (ppm): 27.8 (2 ꢂ CH3); 34.6 (C4); 41.6
(C14); 45.0 (C3); 46.2 (C13); 48.3 (C15); 50.1 (C17); 51.5
(C18); 116.8 (C8); 124.0 (C5); 127.5 (C7); 132.5 (C6); 133.7
(Ca); 141.9 (Cb); 170.4 (C2). MS (IC): m/z ¼ 338 [M þ 1].
6.3.2.1.1. 4,4-Dimethyl-6-(4-(pyridin-2-yl)piperazin-1-ylsul-
fonyl)-3,4-dihydroquinolin-2(1H )-one 4. White solid. Yield
1
63%. M.p. 232e233 ꢀC. H NMR (CDCl3) d (ppm): 1.40 (s,
6H, 2 ꢂ CH3); 2.57 (s, 2H, H3); 3.12e3.17 (m, 4H, H14);
3.66e3.71 (m, 4H, H13); 6.56e6.67 (m, 2H, H17 þ H19); 6.93
(d, 1H, J8e7 ¼ 8.2 Hz, H8); 7.43e7.51 (m, 1H, H18); 7.60
(dd, 1H, J7e8 ¼ 8.2 Hz, J7e5 ¼ 1.9 Hz, H7); 7.66 (d, 1H,
J5e7 ¼ 1.9 Hz, H5); 8.13e8.15 (m, 1H, H20); 8.92 (s, 1H,
NH ). 13C NMR (CDCl3) d (ppm): 28.0 (2 ꢂ CH3); 34.6 (C4);
45.1 (C13 or C14); 45.2 (C14 or C13); 46.2 (C3); 107.6 (C17);
114.5 (C19); 116.4 (C8); 125.1 (C5); 128.2 (C7); 130.5 (C6);
133.7 (Cb); 138.1 (C18); 140.5 (Ca); 148.4 (C20); 159.1 (C16);
171.1 (C2). MS (IC): m/z ¼ 400 [M].
6.3.2.1.2. 6-(4-(3,5-Dichlorophenyl)piperazin-1-ylsulfonyl)-
4,4-dimethyl-3,4-dihydroquinolin-2(1H )-one 5. Beige solid.
1
Yield 97%. M.p. 218e219 ꢀC. H NMR (CDCl3) d (ppm):
1.42 (s, 6H, 2 ꢂ CH3); 2.59 (s, 2H, H3); 3.18e3.29 (m, 8H,
4 ꢂ CH2); 6.73 (d, 1H, J19e17 ¼ J19e21 ¼ 8.9 Hz, H19); 6.97
(d, 1H, J8e7 ¼ 8.2 Hz, H8); 7.31 (d, 2H, J17e19
¼
6.3.2.3. 4,4-Dimethyl-6-(2-methylpiperazin-1-ylsulfonyl)-3,4-
J21e19 ¼ 8.9 Hz, H17 þ H21); 7.65 (dd, 1H, J7e8 ¼ 8.2 Hz,
J7e5 ¼ 2.0 Hz, H7); 7.72 (d, 1H, J5e7 ¼ 2.0 Hz, H5); 8.70 (s,
1H, NH ). 13C NMR (CDCl3) d (ppm): 28.0 (2 ꢂ CH3); 34.6
(C4); 45.1 (C3); 46.1 (C13); 49.1 (C14); 116.5e116.7
(C17 þ C21); 118.6 (C19); 124.0 (Ca); 125.0 (C5); 128.2 (C7);
130.3 (C6); 131.0 (C8); 133.4e133.7 (C18 þ C20); 140.7
(Cb); 150.3 (C16); 171.8 (C2). MS (IC): m/z ¼ 469 [M þ 1].
6.3.2.1.3. 4,4-Dimethyl-6-(4-phenylpiperazin-1-ylsulfonyl)-
3,4-dihydroquinolin-2(1H )-one 6. Beige solid. Yield 90%.
dihydroquinolin-2(1H )-one
9
[21,22]. Under an inert
atmosphere, 2-methylpiperazine (73 mg, 0.73 mmol) was dis-
solved in dry dichloromethane (10 mL) and triethylamine
(0.1 mL, 0.73 mmol) was added. The mixture was cooled
down to 0 ꢀC. The sulfonyl chloride 3 (0.1 g, 0.36 mmol)
was also dissolved in dichloromethane (10 mL) and the solu-
tion was cooled down using an ice/water bath. The sulfonyl
chloride solution was canulated over piperazine and base mix-
ture. After 3 h at 0 ꢀC, the reaction was completed and water
was added. The product was extracted with dichloromethane
and the combined organic layers were successively washed
1
M.p. 224e225 ꢀC. H NMR (CDCl3) d (ppm): 1.42 (s, 6H,
2 ꢂ CH3); 2.60 (s, 2H, H3); 3.25 (dd, 8H, J13ae14a ¼ 15.3 Hz,

M.-A. Letellier et al. / European Journal of Medicinal Chemistry 43 (2008) 1730e1736
1735
with water and a saturated solution of sodium chloride, dried
over anhydrous MgSO4 and solvents were evaporated. The
crude product was purified by column chromatography on sil-
ica gel (DCM/MeOH).
7.09 (d, 1H, J8e7 ¼ 9.5 Hz, H8); 8.14e8.19 (m, 2H,
H5 þ H7). 13C NMR (CDCl3) d (ppm): 27.6 (2 ꢂ CH3);
0
30.2 (C1 ); 33.7 (C4); 45.6 (C3); 115.4 (C7); 120.7 (C5);
124.0 (C8); 136.0 (Cb); 143.6 (Ca); 145.1 (C6); 169.6 (C2).
MS (IC): m/z ¼ 234 [M].
Beige solid. Yield 61%. M.p. 198e199 ꢀC. 1H NMR (CDCl3)
0
0
d (ppm): 1.08 (d, 3H, J13 e13 ¼ 6.3 Hz, H13 ); 1.41 (s, 6H,
2 ꢂ CH3); 1.94 (t, 1H, J17ae16a ¼ J17ae16b ¼ 10.6 Hz, H17a);
2.33 (dt, 1H, J16ae17a ¼ J16ae17b ¼ 10.6 Hz, J16ae16b ¼ 4.2 Hz,
Tin chloride dihydrate (0.482 g, 2.14 mmol) was added to
a solution of 11 (0.1 g, 0.43 mmol) in absolute ethanol
(10 mL). A few milliliters of ethyl acetate was added to acti-
vate tin chloride and the reaction mixture was refluxed for
3 h. The solvents were then removed under reduced pressure
and the crude residue was taken up in a solution of sodium hy-
droxide 10% and extracted with ethyl acetate. The combined
organic layers were washed with a saturated solution of so-
dium chloride and the solvent was evaporated. The product
was purified by column chromatography on silica gel
(DCM) to provide 6-amino-1,4,4-trimethyl-3,4-dihydroquino-
lin-2(1H )-one 12 as a yellow oil.
H
16a); 2.58 (s, 2H, H3); 2.92e3.04 (m, 3H, H13 þ H14); 3.62e
3.67 (m, 2H, H16b þ H17b); 6.98 (d, 1H, J8e7 ¼ 8.2 Hz, H8);
7.62 (dd, 1H, J7e8 ¼ 8.2 Hz, J7e5 ¼ 1.9 Hz, H7); 7.68 (d, 1H,
J5e7 ¼ 1.9 Hz, H5); 9.07 (s, 1H, NH ). 13C NMR (CDCl3)
0
d (ppm): 19.6 (C13 ); 27.7 (2 ꢂ CH3); 34.3 (C4); 44.8 (C3);
45.3 (C14); 46.2 (C16); 50.3 (C13); 52.8 (C17); 116.2 (C8);
124.7 (C5); 127.9 (C7); 130.3 (C6); 133.3 (Ca); 140.1 (Cb);
171.1 (C2). MS (IC): m/z ¼ 338 [M þ 1].
6.3.3. General procedure for the preparation of N-
(1,4,4-trimethyl-2-oxo-1,2,3,4-tetrahydroquinolin-6-yl)
naphthalene-1-sulfonamide: synthesis of compounds
10e13
Yield 88%. 1H NMR (CDCl3) d (ppm): 1.25 (s, 6H,
0
2 ꢂ CH3); 2.45 (s, 2H, H3); 3.34 (s, 3H, H1 ); 3.58 (s, 2H,
NH2); 6.57 (dd, 1H, J7e8 ¼ 8.4 Hz, J7e5 ¼ 2.6 Hz, H7); 6.66
13
(d, 1H, J5e7 ¼ 2.6 Hz, H5); 6.81 (d, 1H, J8e7 ¼ 8.4 Hz, H8).
0
Under an argon atmosphere, a solution of 4,4-dimethyl-3,4-
dihydro-1H-quinolin-2-one 2 (0.525 g, 3 mmol) in dry DMF
(10 mL) was cooled down to 0 ꢀC and canulated dropwise
over a suspension of sodium hydride, a 60% dispersion in min-
eral oil (0.120 g, 3 mmol), in dry DMF (5 mL) at 0 ꢀC. After
5 min, methyl iodide (0.28 mL, 4.5 mmol) was added drop-
wise to the mixture still at 0 ꢀC. The reaction mixture was al-
lowed to warm up to room temperature and stirring was
maintained for 2 h. After hydrolysis, the product was extracted
with ethyl acetate and the combined organic layers were
washed several times with a saturated solution of ammonium
chloride, dried over anhydrous MgSO4 and solvents were re-
moved under reduced pressure. The crude product was purified
by column chromatography on silica gel (EP/DCM) to provide
the desired 1,4,4-trimethyl-3,4-dihydroquinolin-2(1H )-one 10
as a yellow oil [15].
C NMR (CDCl3) d (ppm): 27.7 (2 ꢂ CH3); 29.8 (C1 ); 33.4
(C4); 46.4 (C3); 111.9 (C5); 113.8 (C7); 116.5 (C8); 131.9
(Cb); 136.5 (Ca); 142.6 (C6); 169.4 (C2). MS (IC): m/z ¼ 204
[M].
Under an inert atmosphere, to a solution of 12 (0.06 g,
0.29 mmol) in dry pyridine (3 mL) was added naphthalene-1-
sulfonyl chloride (0.067 g, 0.29 mmol). After 0.5 h at room
temperature, water was added to the reaction mixture and the
product was extracted with ethyl acetate. The organic layer
was then washed successively with a solution of HCl 1 N and
a saturated solution of sodium chloride. Recrystallisation in
2-propanol afforded the desired N-(1,4,4-trimethyl-2-oxo-1,2,
3,4-tetrahydroquinolin-6-yl)naphthalene-1-sulfonamide 13 as
an orange solid.
1
Yield 92%. M.p. 218e219 ꢀC. H NMR (CDCl3) d (ppm):
0
0.99 (s, 6H, 2 ꢂ CH3); 2.34 (s, 2H, H3); 3.27 (s, 3H, H1 ); 6.62
Yield 99%. 1H NMR (CDCl3) d (ppm): 1.33 (s, 6H,
(d, 1H, J5e7 ¼ 2.4 Hz, H5); 6.75 (d, 1H, J8e7 ¼ 8.6 Hz, H8);
6.85 (dd, 1H, J7e8 ¼ 8.6 Hz, J7e5 ¼ 2.4 Hz, H7); 7.45 (dd,
1H, J15e16 ¼ 8.2 Hz, J15e14 ¼ 7.5 Hz, H15); 7.65 (dddd, 2H,
0
2 ꢂ CH3); 2.55 (s, 2H, H3); 3.43 (s, 3H, H1 ); 7.06e7.15 (m,
2H, H7 þ H8); 7.27e7.36 (m, 2H, H5 þ H6). 13C NMR
0
(CDCl3) d (ppm): 27.5 (2 ꢂ CH3); 29.5 (C1 ); 33.1 (C4); 46.0
J19e18 ¼ 7.6 Hz, J20e21 ¼ 7.2 Hz, J20e18 ¼ 1.8 Hz, J19e21 ¼
(C3); 115.1 (C8); 123.4 (C6); 124.3 (C5); 127.4 (C7); 134.8
(Ca); 139.4 (Cb); 169.7 (C2). MS (IC): m/z ¼ 189 [M].
A solution of 1,4,4-trimethyl-3,4-dihydroquinolin-2(1H )-
one 10 in dry dichloromethane was cooled down to 0 ꢀC un-
der an argon atmosphere. Extra pure nitric acid was added
carefully and the mixture was allowed to stir at 0 ꢀC for 3 h
before hydrolysis over ice. The product was extracted with di-
chloromethane and the combined organic layers were succes-
sively washed with a solution of sodium hydrogenocarbonate
and sodium chloride, and dried over MgSO4. The solvents
were then evaporated. The crude product was purified by col-
umn chromatography on silica gel (EP/AcOEt) to afford
1,4,4-trimethyl-6-nitro-3,4-dihydroquinolin-2(1H )-one 11 as
a yellow solid.
1.3 Hz, H19 þ H20); 7.95 (dd, 1H, J18e19 ¼ 7.6 Hz,
J18e20 ¼ 1.8 Hz, H18); 8.04 (d, 1H, J16e14 ¼ 8.0 Hz, H16);
8.14 (dd, 1H, J21e20 ¼ 7.2 Hz, J21e19 ¼ 1.3 Hz, H21); 8.65
(d, 1H, J14e16 ¼ 8.0 Hz, H14). 13C NMR (CDCl3) d (ppm):
0
27.4 (2 ꢂ CH3); 29.8 (C1 ); 33.2 (C4); 45.8 (C3); 115.9 (C5);
120.2 (C7); 123.0 (C8); 124.5 (C20); 124.6 (C19); 127.4
(C14); 128.7 (Cb); 128.9 (C15); 129.6 (C21); 131.0 (C18);
131.6 (C22); 134.3 (C17); 134.5 (C6); 135.0 (C16); 136.0
(Ca); 137.8 (C13); 169.5 (C2). MS (IC): m/z ¼ 394 [M].
Acknowledgements
1
Yield 68%. M.p. 130e131 ꢀC. H NMR (CDCl3) d (ppm):
We wish to thank the SERVIER industries and the Region
Centre for their financial support.
0
1.36 (s, 6H, 2 ꢂ CH3); 2.58 (s, 2H, H3); 3.44 (s, 3H, H1 );

1736
M.-A. Letellier et al. / European Journal of Medicinal Chemistry 43 (2008) 1730e1736
[12] A. Takami, M. Iwakubo, Y. Okada, T. Kawata, H. Odai, N. Takahashi,
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