Synthesis of 2-quinolinecarboxamide derivatives as potential HDAC inhibitors

Article abstract of DOI:10.1007/s10593-011-0825-x

Inhibition of histone deacetylase activity appears as an original and effective approach for the treatment of cancer. A series of novel quinoline-containing derivatives has been synthesized and found that some of these compounds possess nanomolar histone deacetylase inhibitory activity.

Full text of DOI:10.1007/s10593-011-0825-x

Chemistry of Heterocyclic Compounds, Vol. 47, No. 6, September 2011 (Russian original Vol. 47, No. 6, June, 2011)
SYNTHESIS OF 2-QUINOLINE-
CARBOXAMIDE DERIVATIVES
AS POTENTIAL HDAC INHIBITORS
O. Habarova1*, O. Bobiꢀeva1, E. Loža1, and N. Romanꢁikova1
Inhibition of histone deacetylase activity appears as an original and effective approach for the treatment
of cancer. A series of novel quinoline-containing derivatives has been synthesized and found that some
of these compounds possess nanomolar histone deacetylase inhibitory activity.
Keywords: inhibitors of histone deacetylase, quinoline, Zn2+ chelating groups.
Histone deacetylases (HDAC) are a group of enzymes that catalyze and regulate the process of deacety-
lation of histones. The process of acetylation-deacetylation of histones is involved in the regulation of chromatin
structure and gene expression. Numerous studies have shown that HDAC inhibition leads to the tumor cell
differentiation, proliferation, and apoptosis [1, 2]. These findings immensely stimulated a search for substances,
both natural and synthetic, which could serve as HDAC inhibitors. As a result of these studies a number of
HDAC inhibitors are currently under clinical trials as anticancer agents [3].
A widely accepted pharmacophoric description of simple HDAC inhibitors can be conditionally repre-
sented by three linearly bonded groups AꢀLꢀX, where A represents a surface recognition zone (CAP), usually
an aryl group, which provides potency and selectivity, L is predominantly a hydrophobic linking group, and X
represents a moiety that interacts with the catalytic Zn2+ ion at the HDAC active site, usually a hydroxamic acid
group [3].
During our recent search for new HDACs inhibitors that would contain a quinoline cycle in the A part of
the molecule [4], a new active 2-quinoline derivative 1 (Figure 1) with IC50 = 4 nM for HeLa extract was found
(HeLa extract is a cell type in an immortal cell line that is used in cancer research).
A beneficial role of the 2-quinolinyl cycle presence in the A part of the structure 1 on the increase of
HDAC inhibitory activity can be clearly demonstrated by comparing the activities of the compounds 1ꢀ3. Thus,
the hydroxamate 2 [5] with the phenyl moiety is a more than 200 times weaker HDAC inhibitor in comparison
to the quinoline derivative 1. Although a significant increase of the activity can be gained by changing the
phenyl group of the structure 2 to the 2-naphthyl group, the naphthyl derivative 3 [6] is still 5 times less active
than the compound 1. One can quite easily recognize the above-mentioned pharmacophoric regions AꢀLꢀX in
the structures 1ꢀ3.
_______________
*To whom correspondence should be addressed, ꢀ-mail: olgahabarova@osi.lv.
1Latvian Institute of Organic Synthesis, 21 Aizkraukles St., Riga, LV-1006.
__________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 871–880, June, 2011. Original
article received August 26, 2010.
0009-3122/11/4706-0719©2011 Springer Science+Business Media, Inc.
719
ꢀ

A
L
X
O
H
N
OH
Ar
N
H
O
1–3
1 Ar = quinolin-2-yl, IC50 = 4 nM,
2 Ar = phenyl, IC50 = 900 nM,
3 Ar = naphth-2-yl, IC50 = 21 nM
Fig. 1 General structure of a potential HDAC inhibitors
A great majority of known HDAC inhibitors contain hydroxamic acid as a Zn2+ binder. Although many
hydroxamic acid-based HDAC inhibitors possess strong in vitro and in vivo activity, they in general exhibit
unfavorable pharmacokinetic properties [7], including the potential for chronic toxicities.
The main purpose of the present work was to synthesize and assess the HDAC inhibitory potential of a
series of such analogs of the compound 1, in which the hydroxamic acid part of the molecule would be replaced
by diverse functional groups a priori capable for more or less effective binding with the Zn2+ ion.
The compounds 4ꢀ12 prepared for this study are shown in Table 1. The routes used for the synthesis of
the compounds 4ꢀ18 are depicted in Schemes 1ꢀ4. The intermediates 13ꢀ15 were prepared from carboxylic acid
19 as shown in Scheme 1. Thus, condensation of the carboxylic acid 19 with 5-aminopentan-1-ol in the presence
of N,N'-carbonyldiimidazole (CDI) afforded the hydroxy derivative 13. Similar condensation of the acid 19 with
tert-butyl 5-aminopentylcarbamate followed by acidic elimination of the N-tert-butoxycarbonyl (Boc) protective
group gave the amine hydrochloride 14, but the use of methyl 6-aminohexanoate in the reaction with the acid 19
after ester hydrolysis gave the expected carboxylate 15.
Scheme 1
CDI,
H2N
H2N
OH
( )5
H
N
Quin
Quin
OH
( )5
O
O
13
1. CDI,
NHBoc
( ) 5
H
N
NH2
( )5
OH
2. HCl/MeOH
.
HCl
N
O
14
O
19
H N
Me
1. CDI,
O
2
( )5
H
O
Quin
N
( )5
OH
2. aq. NaOH
O
15
Quin = quinolin-2-yl
Bromination of the hydroxy derivative 13 yielded bromide 16, which in turn served as a common inter-
mediate for further synthesis of compounds 4ꢀ9 (Scheme 2).
720
ꢀ

Scheme 2
O
O
H
N
H
N
Oxone
S
Quin
S
Quin
S
( )5
Me
( )5
Me
7
O
13
O
O
8
PPh3, CBr4
NaSMe
Br
H
N
H
N
Quin
Quin
KSAc
( )5
( )5
16
Me
O
4
Me
O
MeO
O
P
NaOH
MeEt3N+
O
Me
O
H
N
H
N
H
N
H
O
Quin
SH
Quin
Quin
S
S
N
Quin
( )5
( )5
P
Me
( )5
( )5
O
O
O
9
O
O
5
17
O
NaOH,
O
NaBH4 Br
Br
CF3
OH
CF3
O
H
H
N
S
N
Quin
S
Quin
( )5
( )5
CF3
CF3
O
O
6
18
Thus, the bromide 16 was treated with potassium ethanethioate to give S-ethanethioate derivative 4,
which was converted by a solution of sodium hydroxide in methanol into, presumably, thiol 17. However, all
attempts to obtain the thiol 17 in a pure state were unsuccessful, and only disulfane 5 was isolated from the
reaction mixture. It is noteworthy that we were not able to obtain the expected SN-substitution product 18 of this
envisaged thiol 17 with such a reactive electrophile as 3-bromo-1,1,1-trifluoroacetone even upon one-pot
conditions by adding the latter to the reaction mixture directly after the removal of the acetyl group from the
ethanethioate 4. As the only product of the reaction the disulfane 5 was isolated. Treatment of the dimeric
compound 5 with sodium borohydride and sodium hydroxide in the presence of 3-bromo-1,1,1-trifluoroacetone
1
yielded 2-hydroxypropylsulfanyl derivative 6. Although H NMR spectra of the compound 5 did not provide
unequivocal evidence in favor of a dimeric structure ꢀSꢀSꢀ to a monomer –SH, the dimer structure of the
substance 5 was assigned on the basis of its electrospray ionization mass spectrum and chemical behavior.
The methylsulfanyl derivative 7 was obtained by alkylation of sodium methanethiolate with the bromide
16. Further oxidation of the compound 7 with 2 equivalents of oxone gave the sulfonyl derivative 8 (Scheme 2).
The ester 9 was prepared by the reaction of the bromide 16 with N,N-diethyl-N-methylethanaminium
methyl methylphosphonate (Scheme 2).
The phosphonamidoate 10 was obtained by condensation of the amine 14 and methyl hydrogen methyl-
phosphonate in the presence of 3-(3-dimethylaminopropyl)-1-ethylcarbodiimide (Scheme 3).
The compounds 11 and 12 were synthesized from the carboxylic acid 15 as depicted in Scheme 4. The
acid 15 was converted by oxalyl chloride into the corresponding acid chloride, which, without additional
purification, upon treatment with 2,2,2-trifluoroethanethiol yielded S-trifluoroethyl thioate 11. The obtained
compound 11 was found to be unstable under chromatographic purification conditions, and a significant amount
of the product 11 was converted back to the starting acid 15, reducing the yield of the reaction. The
N-acylmethanesulfonamide 12 was obtained by condensing the acid 15 and methanesulfonamide in the presence
of CDI and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).
721
ꢀ

Scheme 3
Me
OH
O
Me
P
Me
H
N
H
N
O
O
Quin
( )5
14
P
Me
EDC
O
O
10
EDC ꢀ 3-(3-dimethylaminopropyl)-1-ethylcarbodiimide
Scheme 4
O
O
O
O
H
N
H
N
1. (COCl)2
1. CDI, DBU
2. NH2SO2Me
S
Quin
Quin
15
( )5
N
( )5
CF3
S
Me
2. CF3CH2SH
H
O
O
12
11
The compounds 4ꢀ12 synthesized in this study were tested in vitro using HeLa nuclear extract assay. In
all cases, the enzyme activity was determined with a fluorometric assay. The results are summarized in Table 1.
Trichostatin A (TSA) was used as a positive control that inhibited 100% of the HDAC activity at 1 ꢁM.
Among the synthesized compounds 4ꢀ12 the most active turned out to be the sulfanyl derivatives 4ꢀ7.
In the case of the compounds 4 and 5, as a possible mechanism for their action, an initial thioate hydrolysis or
reduction of the disulfanyl group could not be ruled out. In the next step the thiol group creates a monodentate
complex with the Zn2+ ion in the active center of the enzyme [8].
Within this project the sulfone 8 and sulfonamide 12 were found to be inactive, although sulfonamides
are well-known inhibitors of carbonic anhydrase and other Zn2+ ion-dependent enzymes [9, 10].
TABLE 1. HDAC Enzyme Inhibition Data for Compounds 4ꢀ12
H
R
N
( )5
N
O
Inhibition (HeLa), %*
Compound
R
1 ꢁM
5 ꢁM
20 ꢁM
4
ꢀSAc
33
48
105
H
N
S
5
20
37
71
( )5
S
N
O
6
ꢀSCH2CH(OH)CF3
ꢀSMe
0
18
0
55
23
0
7
0
8
ꢀSO2Me
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
9
ꢀOP(O)Me(OMe)
ꢀNHP(O)Me(OMe)
ꢀC(O)SCH2CF3
ꢀC(O)NHSO2Me
0
10
0
11
0
12
0
_____________
* NT = not tested.
722
ꢀ

Phosphonic acid derivatives are known as metalloenzyme (thermolysin and carboxypeptidase A) inhibi-
tors [11, 12]. Unfortunately, the phosphorus-based compounds 9 and 10 were found to be completely inactive in
the experiments with the HeLa extract.
Compounds 8ꢀ12 were found to be inactive at the 20 ꢁM concentration. Because of their weak inhibi-
tion potential, further studies of this group of compounds were stopped.
In conclusion, we have obtained and tested new HDAC inhibitors with low micromolar activity against
HeLa extract. The active compounds are worthy of further investigation and optimization.
EXPERIMENTAL
Final compounds were assessed for their ability to inhibit HDAC activity. Enzyme activity was deter-
mined with a fluorometric assay.
The activity of the compounds as HDAC inhibitors was determined with a commercially available fluo-
rescent assay kit Fluor de LysTM, BioMol Research Labs, Inc. (Plymouth Meeting, USA). HeLa extract was
incubated for 30ꢀ60 min at 37ºC in assay buffer (25 mM HEPES, 137 mM NaCl, 2.7 mM KCl, 1 mM MgCl2,
pH 8.0) with 15 ꢁM acetylated substrate in the presence of the test compound (HDAC inhibitor). The extent of
deacetylation was determined by the addition of 50 ꢁM of 1-in-500 dilution of developer and measurement of
the fluorescence (excitation 355 nm, emission 460 nm), according to the instructions provided with the kit.
Percent activity (% activity) was calculated for each test compound ([(SCꢀB)/(S0ꢀB)]ꢂ100, wherein SC
denotes the signal measured in the presence of the compound being tested, S0 the signal measured in the absence
of the compound being tested, and B the background signal measured in blank wells containing the medium only).
1H NMR spectra were recorded on Varian 200 and Varian 400 Oxford NMR spectrometers (200 and
400 MHz respectively) in solvent as indicated. Chemical shifts are referenced to HMDSO as internal standard
(ꢂ = 0.055 ppm) or using the signal of the corresponding residual protonated solvent (for DMSO-d6
ꢂ = 2.50, for CDCl3 ꢂ = 7.26 ppm). Melting points were determined using a Gallenkamp melting point apparatus.
High-resolution mass spectra (HRMS) analyses were performed using a Micromass Q-TOF Micro quadrupole-time-
of-flight high-resolution mass spectrometer. Leucine enkephalin was used as internal lock mass for accurate
mass calculation (m/z 566.2771). LC-MS analyses were performed on an Acquity UPLC system (Waters)
connected to the Micromass Q-TOF micro hybrid quadrupole-time-of-flight mass spectrometer operating in the
electrospray ionization (ESI) positive ion mode and using a reverse-phase Acquity UPLC BEH C18 column
(1.7 -m, 2.1×50 mm) on a gradient of 5ꢀ98% acetonitrile–water–0.1% formic acid. HPLC analysis was
performed on the Waters HPLC equipped with a LiChrospher RP Select B column (eluent acetonitrile – 0.1%
H3PO4). Elemental analyses were performed on Carlo Erba CHNS-O EA-1108 apparatus. Organic solvents were
dried prior to use by standard procedures. Reagents and solvents were purchased from Aldrich, Acros, and Alfa
Aesar Chemical Industries.
N-(5-Hydroxypentyl)-2-quinolinecarboxamide (13). 2-Quinolinecarboxylic acid (19) (0.50 g,
2.89 mmol) was dissolved in 20 ml THF, then CDI (0.56 g, 3.47 mmol) was added, and the solution was stirred
at room temperature for 1 h. After addition of 5-amino-1-pentanol (0.36 g, 3.47 mmol), the mixture was stirred
at room temperature for 3 h. The reaction mixture was evaporated and after addition of EtOAc, the organic
phase was washed with H2O, 3% HCl, dried over Na2SO4, filtered, and evaporated. Yield 0.68 g (91%); mp 63–
1
64ºC. H NMR spectrum (400 MHz, DMSO-d6), ꢂ, ppm (J, Hz): 1.35 (2H, m, CH2); 1.46 (2H, quint, J = 6.9,
CH2); 1.59 (2H, quint, J = 7.3, CH2); 3.28–3.44 (4H, m overlapped with H2O, 2CH2); 4.35 (1H, t, J = 5.2, OH);
7.72 (1H, ddd, J = 1.1, J = 7.0, J = 8.1, H Quin); 7.87 (1H, ddd, J = 1.3, J = 7.0, J = 8.3, H Quin); 8.08 (1H, d,
J = 8.1, H Quin); 8.14 (1H, d, J = 8.3, H Quin); 8.15 (1H, d, J = 8.5, H Quin); 8.55 (1H, d, J = 8.5, H Quin); 8.90
(1H, t, J = 6.0, NH). Mass spectrum, m/z: 259 [M+H]+. Found, %: C 69.45; H 7.02; N 10.79. C15H18N2O2.
Calculated, %: C 69.75; H 7.02; N 10.84.
N-(5-Aminopentyl)-2-quinolinecarboxamide Hydrochloride (14). Starting tert-butyl N-{5-[(2-quinoli-
nylcarbonyl)amino]pentyl}carbamate was obtained as described for the compound 13. Yield 86% of a wax-like
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ꢀ

product. 1H NMR spectrum (400 MHz, DMSO-d6), ꢂ, ppm (J, Hz): 1.25–1.46 (4H, m, 2CH2); 1.35 (9H, s, 3CH3);
1.58 (2H, quint, J = 7.3, CH2); 2.91 (2H, q, J = 6.5, CH2); 3.29–3.40 (2H, m overlapped with H2O); 6.76 (1H, t,
J = 5.7, NH); 7.72 (1H, ddd, J = 1.1, J = 6.9, J = 8.1, H Quin); 7.87 (1H, ddd, J = 1.4, J = 6.9, J = 8.4, H Quin);
8.08 (1H, d, J = 8.1, H Quin); 8.14 (1H, d, J = 8.4, H Quin); 8.15 (1H, d, J = 8.5, H Quin); 8.55 (1H, d, J = 8.5,
H Quin); 8.89 (1H, t, J = 6.0, NH).
tert-Butyl N-{5-[(2-quinolinylcarbonyl)amino]pentyl}carbamate (2.40 g, 6.71 mmol) was dissolved in
50 ml of 1 N HCl solution in MeOH and stirred at room temperature for 1 h. The reaction mixture was evapo-
rated and the residue was kept for 12 h at 0ºC. The obtained wax-like solid was recrystallized at 0–5ºC from
MeCN–EtOH (10:1). Yield 1.07 g (54%). 1H NMR spectrum (200 MHz, DMSO-d6), ꢂ, ppm (J, Hz): 1.44 (2H,
m, CH2); 1.67 (4H, m, 2CH2); 2.82 (2H, sextet, J = 6.4, CH2); 3.42 (2H, q, J = 6.7, CH2); 4.00–4.50 (3H, br. s
overlapped with H2O, NH3); 7.77 (1H, t, J = 7.7, H Quin); 7.93 (1H, t, J = 7.7, H Quin); 8.14 (1H, d,
J = 8.0, H Quin); 8.21 (1H, d, J = 8.4, H Quin); 8.22 (1H, d, J = 8.5, H Quin); 8.64 (1H, d, J = 8.5, H Quin);
9.04 (1H, t, J = 6.0, NH). HRMS (ESI), m/z: Found: 258.1646 [M+H]+. C15H19N3O. Calculated: M = 258.1606.
6-[(2-Quinolinylcarbonyl)amino]hexanoic acid (15). Starting methyl 6-[(2-quinolinylcarbonyl)ami-
1
no]hexanoate was obtained as described for the compound 13. Yield 60% of a wax-like product. H NMR
spectrum (200 MHz, DMSO-d6), ꢂ, ppm (J, Hz): 1.27–1.43 (2H, m, CH2); 1.48–1.68 (4H, m, 2CH2); 2.32 (2H, t,
J = 7.1, CH2); 3.36 (2H, q overlapped with H2O, J = 6.7, CH2); 3.57 (3H, s, CH3); 7.72 (1H, ddd, J = 1.2, J = 6.9,
J = 8.2, H Quin); 7.87 (1H, ddd, J = 1.5, J = 6.9, J = 8.4, H Quin); 8.08 (1H, dd, J = 1.5, J = 8.2, H Quin); 8.14 (1H,
dd, J = 1.2, J = 8.4, H Quin); 8.16 (1H, d, J = 8.5, H Quin); 8.56 (1H, J = 8.5, H Quin); 8.93 (1H, t, J = 6.1, NH).
Methyl 6-[(2-quinolinylcarbonyl)amino]hexanoate (0.52 g, 1.73 mmol) was added to a solution of
NaOH (0.25 g, 6.25 mmol) in 10 ml of EtOH and stirred at room temperature for 15 min. The solvent was
evaporated. The residue was dissolved in 10 ml of H2O, acidified to pH 3 with 18% HCl, and extracted with
EtOAc. The organic phase was washed with H2O, dried over Na2SO4, filtered, and evaporated. Yield 0.31 g
1
(62%); mp 70–71ºC. H NMR spectrum (400 MHz, DMSO-d6), ꢂ, ppm (J, Hz): 1.26–1.42 (2H, m, CH2); 1.55
(2H, quint, J = 7.6, CH2); 1.59 (2H, quint, J = 7.6, CH2); 2.22 (2H, t, J = 7.3, CH2); 3.35 (2H, q overlapped with
H2O, J = 6.7, CH2); 7.72 (1H, ddd, J = 1.2, J = 6.9, J = 8.1, H Quin); 7.87 (1H, ddd, J = 1.6, J = 6.9, J = 8.5,
H Quin); 8.08 (1H, dd, J = 1.6, J = 8.1, H Quin); 8.14 (1H, d, J = 8.5, H Quin); 8.15 (1H, d, J = 8.6, H Quin);
8.56 (1H, d, J = 8.6, H Quin); 8.94 (1H, t, J = 6.2, NH); 12.00 (1H, br. s, OH). HRMS (ESI), m/z: Found:
287.1365 [M+H]+. C16H18N2O3. Calculated: M = 287.1396.
N-(5-Bromopentyl)-2-quinolinecarboxamide (16). Compound 13 (2.50 g, 9.68 mmol) was dissolved in
20 ml of MeCN, then Ph3P (3.05 g, 11.62 mmol) and CBr4 (3.90 g, 11.76 mmol) were added, and the solution
was stirred at room temperature for 24 h. The reaction mixture was evaporated and after addition of EtOAc, the
organic phase was washed with H2O, brine, dried over Na2SO4, filtered, and evaporated. The crude product was
purified by flash chromatography with EtOAc–light petroleum (1:2) as eluent. Yield 1.71 g (54%) of a wax-like
product. 1H NMR spectrum (400 MHz, DMSO-d6), ꢂ, ppm (J, Hz): 1.44 (2H, m, CH2); 1.61 (2H, quint, J = 7.3,
CH2); 1.85 (2H, quint, J = 7.1, CH2); 3.37 (2H, q overlapped with H2O, J = 6.8, CH2); 3.55 (1H, t, J = 6.7, CH2);
7.72 (1H, ddd, J = 1.2, J = 7.0, J = 8.1, H Quin); 7.87 (1H, ddd, J = 1.4, J = 7.0, J = 8.4, H Quin); 8.08 (1H, d,
J = 8.1, H Quin); 8.14 (1H, d, J = 8.4, H Quin); 8.15 (1H, d, J = 8.5, H Quin); 8.55 (1H, d, J = 8.5, H Quin); 8.94
(1H, t, J = 5.8, NH). HRMS (ESI), m/z: Found: 321.0568 [M+H]+. C15H17BrN2O. Calculated: M = 321.0602.
S-{5-[(2-Quinolinylcarbonyl)amino]pentyl} Ethanethioate (4). Compound 16 (0.10 g, 0.31 mmol)
was dissolved in 7 ml of MeCN under Ar atmosphere, and potassium ethanethioate (0.07 g, 0.62 mmol) was
added. The obtained solution was stirred at room temperature for 24 h. The reaction mixture was filtered, the
filtrate was evaporated, dissolved in ethyl acetate, and washed with H2O, 10% solution of citric acid, H2O, dried
over Na2SO4, filtered, and evaporated. Yield 0.08 g (84%) of a wax-like product. 1H NMR spectrum (400 MHz,
DMSO-d6), ꢂ, ppm (J, Hz): 1.33–1.42 (2H, m, CH2); 1.56 (2H, quint, J = 7.4, CH2); 1.59 (2H, quint, J = 7.4,
CH2); 2.30 (3H, s, CH3); 2.84 (2H, t, J = 7.2, CH2); 3.35 (2H, q overlapped with H2O, J = 6.9, CH2); 7.72 (1H,
ddd, J = 1.2, J = 7.0, J = 8.1, H Quin); 7.87 (1H, ddd, J = 1.5, J = 7.0, J = 8.4, H Quin); 8.08 (1H, d, J = 8.1,
H Quin); 8.14 (1H, d, J = 8.4, H Quin); 8.15 (1H, d, J = 8.5, H Quin); 8.56 (1H, d, J = 8.5, H Quin); 8.92 (1H, t,
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ꢀ

J = 5.9, NH). Mass spectrum, m/z: 317 [M+H]+. Found, %: C 63.40; H 6.01; N 8.55. C17H20N2O2S·0.3H2O.
Calculated, %: C 63.45; H 6.45; N 8.70.
N,N'-[Disulfanediyldi(pentane-5,1-diyl)]diquinoline-2-carboxamide (5). Compound
4
(0.27 g,
0.85 mmol) was dissolved in 10 ml of MeOH under Ar atmosphere, and a solution of NaOH (0.04 g, 1.00 mmol)
in 4 ml of MeOH was added and stirred at room temperature for 1 h. The reaction mixture was evaporated, and
the obtained residue was dissolved in EtOAc, washed with H2O, dried over Na2SO4, filtered, and evaporated.
The crude product was purified by flash chromatography with EtOAc–light petroleum (1:2) as eluent. Yield 0.14 g
(60%) of a wax-like product. 1H NMR spectrum (400 MHz, CDCl3), ꢂ, ppm (J, Hz): 1.45–1.62 (4H, m, 2CH2);
1.62–1.84 (8H, m, 4CH2); 2.70 (4H, t, J = 7.2, 2CH2); 3.53 (4H, q, J = 6.6, 2CH2); 7.60 (2H, ddd, J = 1.3,
J = 7.0, J = 8.1, H Quin); 7.75 (2H, ddd, J = 1.5, J = 7.0, J = 8.4, H Quin); 7.86 (2H, dd, J = 1.5, J = 8.1, H Quin);
8.09 (2H, d, J = 8.4, H Quin); 8.28 (2H, d, J = 8.6, H Quin); 8.29 (2H, d, J = 8.6, H Quin); 8.33 (2H, unresolved t,
2NH). HRMS (ESI), m/z: Found: 547.2144 [M+H]+. C32H34N4O2S2. Calculated: M = 547.2201.
N-{5-[(3,3,3-Trifluoro-2-hydroxypropyl)sulfanyl]pentyl}-2-quinolinecarboxamide (6). Compound
5
(0.13 g, 0.24 mmol) was dissolved in 5 ml of EtOH under Ar atmosphere at 0ºC, and to this solution solid NaOH
(0.02 g, 0.47 mmol) and NaBH4 (0.02 g, 0.52 mmol) were added, and the reaction mixture was stirred for 1 h at
0ºC. Then 3-bromo-1,1,1-trifluoropropan-2-one (0.06 ml, 0.56 mmol) was added, and the reaction mixture was
stirred for 3 h at room temperature. The solvent was evaporated and the obtained residue was dissolved in
EtOAc, washed with H2O, dried over Na2SO4, filtered, and evaporated. Yield 0.11 g (58%) of a wax-like
1
product. H NMR spectrum (400 MHz, CDCl3), ꢂ, ppm (J, Hz): 1.46–1.60 (2H, m, CH2); 1.65–1.80 (4H, m,
2CH2); 2.69 (2H, t, J = 7.3, CH2); 2.93 (1H, br. s, OH); 3.48 (1H, dd, J = 8.4, J = 11.1, CH); 3.52 (2H, q, J = 6.8,
CH2); 3.62 (1H, dd, J = 3.0, J = 11.1, CH); 4.23 (1H, m, CH); 7.60 (1H, ddd, J = 1.2, J = 7.0, J = 8.2, H Quin);
7.75 (1H, ddd, J = 1.4, J = 7.0, J = 8.4, H Quin); 7.86 (1H, ddd, J = 0.6, J = 1.4, J = 8.2, H Quin); 8.09 (1H, d,
J = 8.4, H Quin); 8.26–8.34 (3H, m, 2H Quin and NH). HRMS (ESI), m/z: Found: 387.1354 [M+H]+.
C18H21F3N2O2S. Calculated: M = 387.1354.
N-[5-(Methylsulfanyl)pentyl]-2-quinolinecarboxamide (7). Compound 16 (0.50 g, 1.55 mmol) was
dissolved in 15 ml of EtOH, a solution of sodium methanethiolate (0.23 g, 3.28 mmol) in 15 ml of EtOHꢀH2O
(1:1) was added, and the reaction mixture was stirred for 12 h at 50ºC. The solvent was evaporated, and the
obtained residue was dissolved in EtOAc, washed with H2O, brine, dried over Na2SO4, filtered, and evaporated.
Yield 0.32 g (71%) of a wax-like product. 1H NMR spectrum (400 MHz, DMSO-d6), ꢂ, ppm (J, Hz): 1.36–1.47
(2H, m, CH2); 1.54–1.65 (4H, m, 2CH2); 2.02 (3H, s, CH3); 2.47 (2H, t overlapped with DMSO, J = 7.3, CH2);
3.37 (2H, q overlapped with H2O, J = 6.8, CH2); 7.72 (1H, ddd, J = 1.1, J = 7.0, J = 8.1, H Quin); 7.87 (1H, ddd,
J = 1.4, J = 7.0, J = 8.4, H Quin); 8.08 (1H, d, J = 8.1, H Quin); 8.14 (1H, d, J = 8.4, H Quin); 8.15 (1H, d, J = 8.5,
H Quin); 8.56 (1H, d, J = 8.5, H Quin); 8.92 (1H, t, J = 6.0, NH). HRMS (ESI), m/z: Found: 289.1361 [M+H]+.
C16H20N2OS. Calculated: M = 289.1375.
N-[5-(Methylsulfonyl)pentyl]-2-quinolinecarboxamide (8). To a solution of compound 7 (0.15 g,
0.52 mmol) in 5 ml of DMF, a solution of oxone (2KHSO5·KHSO4·K2SO4) (0.64 g, 1.04 mmol) in 5 ml of H2O
was added, and the reaction mixture was stirred for 12 h at room temperature. To the reaction mixture 15 ml of
H2O was added; the product was extracted with EtOAc, washed with H2O and brine, dried over Na2SO4, filtered,
1
and evaporated. Yield 0.07 g (44%); mp 84–86ºC. H NMR spectrum (400 MHz, CDCl3), ꢂ, ppm (J, Hz): 1.61
(2H, m, CH2); 1.77 (2H, quint, J = 7.4, CH2); 1.95 (2H, m, CH2); 2.90 (3H, s, CH3); 3.04 (2H, m, CH2); 3.57 (2H,
q, J = 6.7, CH2); 7.62 (1H, t, J = 7.4, H Quin); 7.77 (1H, t, J = 7.6, H Quin); 7.87 (1H, d, J = 8.0, H Quin); 8.11
(1H, d, J = 8.5, H Quin); 8.30 (1H, d, J = 8.6, H Quin); 8.31 (1H, d, J = 8.6, H Quin); 8.34 (1H, unresolved t,
NH). Mass spectrum, m/z: 321 [M+H]+. Found, %: C 59.91; H 6.01; N 8.62. C16H20N2O3S. Calculated, %:
C 59.98; H 6.29; N 8.74.
Methyl 5-[(2-quinolinylcarbonyl)amino]pentyl Methylphosphonate (9). To a solution of compound
16 (0.34 g, 1.06 mmol) in 5 ml of CHCl3, N,N-diethyl-N-methylethanaminium methyl methylphosphonate
(0.28 g, 2.12 mmol) was added, and the reaction mixture was stirred in a closed vessel for 12 h at 100ºC. The
reaction mixture was evaporated, the obtained residue was dissolved in CHCl3, washed with H2O, brine, dried
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over Na2SO4, filtered, and evaporated. The crude product was purified by flash chromatography with
1
CHCl3ꢀMeOH (10:1) as eluent. Yield 0.24 g (65%) of a wax-like product. H NMR spectrum (400 MHz,
CDCl3), ꢂ, ppm (J, Hz): 1.46 (3H, d, J = 17.4, CH3); 1.50–1.58 (2H, m, CH2); 1.70–1.80 (4H, m, 2CH2); 3.55
(2H, q, J = 6.8, CH2); 3.70 (3H, d, J = 11.1, OCH3); 4.00–4.10 (2H, m, CH2); 7.61 (1H, ddd, J = 1.2, J = 6.9,
J = 8.1, H Quin); 7.76 (1H, ddd, J = 1.5, J = 6.9, J = 8.4, H Quin); 7.88 (1H, d, J = 8.1, H Quin); 8.10 (1H, d,
J = 8.4, H Quin); 8.28–8.33 (3H, m, 2H Quin and NH). HRMS (ESI), m/z: Found: 351.1448 [M+H]+.
C17H23N2O4P. Calculated: M = 351.1474.
Methyl P-Methyl-N-{5-[(2-quinolinylcarbonyl)amino]pentyl}phosphonamidoate (10). To a solution
of N-(5-aminopentyl)-2-quinolinecarboxamide hydrochloride (14) (0.20 g, 0.68 mmol) in 10 ml of DMF were
added successively EDC (0.18 g, 0.94 mmol), triethylamine (0.13 ml, 0.94 mmol), and methyl hydrogen
methylphosphonate (0.11 g, 0.86 mmol), and the reaction mixture was stirred for 15 h at 100ºC. To the reaction
mixture 20 ml of H2O was added, the product was extracted with EtOAc, washed with H2O and brine, dried over
Na2SO4, filtered, and evaporated. The crude product was purified by flash chromatography with CHCl3ꢀMeOH
1
(10:1) as eluent. Yield 0.21 g (88%); mp 75–77ºC. H NMR spectrum (400 MHz, DMSO-d6), ꢂ, ppm (J, Hz):
1.27 (3H, d, J = 16.4, CH3); 1.31ꢀ1.39 (2H, m, CH2); 1.44 (2H, quint, J = 7.2, CH2); 1.59 (2H, quint, J = 7.4,
CH2); 2.50ꢀ2.56 (2H, m overlapped with DMSO, CH2); 3.32ꢀ3.39 (2H, m overlapped with H2O, CH2); 3.44 (3H,
d, J = 11.0, OCH3); 7.72 (1H, ddd, J = 1.1, J = 7.0, J = 8.1, H Quin); 7.87 (1H, ddd, J = 1.4, J = 7.0, J = 8.4,
H Quin); 7.99 (1H, br. s, NH); 8.08 (1H, d, J = 8.1, H Quin); 8.14 (1H, d, J = 8.4, H Quin); 8.15 (1H, d, J = 8.5,
H Quin); 8.56 (1H, d, J = 8.5, H Quin); 8.91 (1H, t, J = 5.9, NH). Found, %: C 57.19; H 6.72; N 11.60.
C17H24N3O3P·0.4H2O. Calculated, %: C 57.26; H 7.01; N 11.78.
S-(2,2,2-Trifluoroethyl) 6-[(2-Quinolinylcarbonyl)amino]hexanethioate (11). To a solution of com-
pound 15 (0.40 g, 1.40 mmol) in 10 ml of THF were added dropwise oxalyl dichloride (0.34 ml, 3.96 mmol) and
two drops of DMF. The reaction mixture was stirred for 10 min at room temperature, and the precipitated
crystals were collected by filtration to give 0.35 g (81%) of 6-[(2-quinolinylcarbonyl)amino]hexanoyl chloride
which was used in the next reaction immediately. To a solution of 6-[(2-quinolinylcarbonyl)amino]hexanoyl
chloride (0.35 g, 1.40 mmol) in 10 ml of CH2Cl2 under Ar atmosphere triethylamine (0.20 ml, 1.42 mmol) was
added dropwise, the reaction mixture was stirred for 20 min at room temperature, then 2,2,2-trifluoroethanethiol
(0.23 ml, 2.58 mmol) was added, and the reaction mixture was stirred for 6 h at room temperature. The reaction
mixture was evaporated and the obtained residue was dissolved in CH2Cl2, washed with H2O and brine, dried
over Na2SO4, filtered, and evaporated. The residue was purified by flash chromatography with EtOAc–light
petroleum (1:2) as eluent, yielding 0.11 g of the starting acid 15 (30%) and 0.07 g of the product 11 (13%) with
1
mp 39–41ºC. H NMR spectrum (400 MHz, CDCl3), ꢂ, ppm (J, Hz): 1.44–1.54 (2H, m, CH2); 1.72 (2H, quint,
J = 7.5, CH2); 1.78 (2H, quint, J = 7.6, CH2); 2.67 (2H, t, J = 7.4, CH2); 3.54 (2H, q, J = 6.8, CH2); 3.57 (2H, q,
J = 9.9, CH2); 7.61 (1H, ddd, J = 1.2, J = 7.0, J = 8.1, H Quin); 7.76 (1H, ddd, J = 1.4, J = 7.0, J = 8.4, H Quin);
7.88 (1H, d, J = 8.1, H Quin); 8.10 (1H, d, J = 8.4, H Quin); 8.26–8.33 (3H, m, 2H Quin and NH). Mass
spectrum, m/z: 385 [M+H]+. Found, %: C 56.32; H 5.10; N 7.17. C18H19F3N2O2S. Calculated, %: C 56.24;
H 4.98; N 7.29.
N-{6-[(Methylsulfonyl)amino]-6-oxohexyl}-2-quinolinecarboxamide (12). To a solution of com-
pound 15 (0.40 g, 1.40 mmol) in 15 ml of DMF was added CDI (0.27 g, 1.68 mmol), and the reaction mixture
was stirred for 1 h at room temperature. Then DBU (0.21 ml, 1.40 mmol) and methanesulfonamide (0.16 g,
1.68 mmol) were added and the reaction mixture was stirred for 2 h at room temperature. The reaction mixture
was poured into H2O and extracted with EtOAc; the extract was washed with H2O and brine, dried over Na2SO4,
filtered, and evaporated. The crude product was recrystallized from Et2O. Yield 0.44 g (86%); mp 165–167ºC.
1H NMR spectrum (400 MHz, DMSO-d6), ꢂ, ppm (J, Hz): 1.27–1.37 (2H, m, CH2); 1.57 (2H, quint, J = 7.6,
CH2); 1.59 (2H, quint, J = 7.5, CH2); 2.28 (2H, t, J = 7.2, CH2); 3.21 (3H, s, CH3); 3.35 (2H, q overlapped with
H2O, J = 6.7, CH2); 7.72 (1H, ddd, J = 1.2, J = 6.9, J = 8.1, H Quin); 7.87 (1H, ddd, J = 1.4, J = 6.9, J = 8.4,
H Quin); 8.08 (1H, dd, J = 1.4, J = 8.1, H Quin); 8.14 (1H, dd, J = 1.2, J = 8.4, H Quin); 8.15 (1H, d, J = 8.5,
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H Quin); 8.55 (1H, J = 8.5, H Quin); 8.92 (1H, t, J = 5.9, NH); 11.65 (1H, br. s, NH). Mass spectrum, m/z: 364
[M+H]+. Found, %: C 55.93; H 5.47; N 11.33. C17H21N3O4S. Calculated, %: C 56.18; H 5.82; N 11.56.
This work was supported by the European Social Fund (No. 2009/0203/1DP/1.1.1.2.0/09/APIA/VIAA/
023).
REFERENCES
1.
2.
3.
4.
A. T. Miller, J. D. Witter, and S. Belvedere, J. Med. Chem., 46, 5097 (2003).
M. Curtin and K. Glaser, Curr. Med. Chem., 10, 2373 (2003).
M. Paris, M. Porcelloni, M. Binaschi, and D. Fattori, J. Med. Chem., 51, 1505 (2008).
P. W. Finn, I. Kalvinsh, E. Loza, V. Andrianov, O. Habarova, D. Lolya, and I. Piskunova, US Pat.
2006/0079528 (2006).
5.
6.
M. Jung, G. Brosch, D. Kolle, H. Scherf, C. Gerhauser, and P. Loidl, J. Med. Chem., 42, 4669 (1999).
V. Andrianov, V. Gailite, D. Lolya, E. Loza, V. Semenihina, I. Kalvinsh, P. W. Finn, K. D. Petersen,
J. W. A. Ritchie, N. Khan, A. Tumber, L. S. Collins, S. M. Vadlamudi, F. Bjorkling, and M. Sehested,
Eur. J. Med. Chem., 44, 1067 (2009).
7.
8.
9.
M. Korner and U. Tibes, Prog. Med. Chem., 46, 205 (2008).
P. Bertrand, Eur. J. Med. Chem., 45, 2095 (2010).
O. Guzel, A. Innocenti, R. A. Hall, A. Scozzafava, F. A. Muhlschlegel, and C. T. Supuran, Bioorg. Med.
Chem., 17, 3212 (2009).
10.
11.
12.
C. S. Grossman, H.-S. Lin, P. A. Hipskind, T. H. Corbett, K. L. Lobb, and C. Shin, AU Pat. 2002259204
(2002).
D. J. Payne, J. H. Bateson, D. Tolson, B. Gasson, T. Khushi, P. Ledent, and J.-M. Frère, Biochem. J.,
314, 457 (1996).
D. A. Campbell, D. V. Patel, and X.-Y. Xiao, US Pat. 5831004 (1998).
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