Synthesis of novel quinoxaline derivatives and its cytotoxic activities

Article abstract of DOI:10.1016/j.bmcl.2009.06.007

Substituted dihydroquinozalin-2-ones (1-16) have been synthesized easily by the use of copper-catalyzed coupling method. The reactions of 2-haloanilines with a variety of α-amino acids in the presence of copper (I) iodide gave corresponding 3-substituted

Full text of DOI:10.1016/j.bmcl.2009.06.007

Bioorganic & Medicinal Chemistry Letters 19 (2009) 4119–4121
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis of novel quinoxaline derivatives and its cytotoxic activities
*
Shinji Tanimori , Takeshi Nishimura, Mitsunori Kirihata
Department of Bioscience and Informatics, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuencho, Nakaku, Sakai, Osaka 599-8531, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Substituted dihydroquinozalin-2-ones (1–16) have been synthesized easily by the use of copper-cata-
Received 21 April 2009
Revised 20 May 2009
Accepted 1 June 2009
Available online 6 June 2009
lyzed coupling method. The reactions of 2-haloanilines with a variety of a-amino acids in the presence
of copper (I) iodide gave corresponding 3-substituted dihydroquinozalin-2-ones in up to 86% yield. Some
new quinoxalin-2-ones (2, 4, 5, 13 and 16) have moderate cytotoxic activity toward HeLaS3 cell lines at
4.9–18.1 lM.
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Quinoxaline
Dihydroquinoxalin-2-one
Ullmann reaction
One-pot synthesis
Domino reaction
Cascade reaction
Cytotoxic activity
Dihydroquinoxalin-2-ones and derivatives are an important
structural motif for the discovery of biologically active compounds.
For example, there are a lot of pharmaceuticals and candidates
possessing such core structures including the inhibitor of histone
deacetylase,1 bradykinin B1 receptor antagonist,2 agonist and
antagonist acting through the GABAA/benzodiazepine receptor,3
vascular smooth muscle relaxants and antihypertensive agents.4
For the reason, there are rich literatures dealing with the synthetic
methods for dihydroquinoxalin-2-ones and derivatives, which in-
clude copper-catalyzed Ullmann-type N-arylation of amino acid
with O-nitroiodobenzene followed by the reduction in the pres-
ence of tin (II) chloride,5 aromatic substitution of O-fluoronitroben-
zene with amino acid followed by reductive cyclization,3,4,6
palladium-catalyzed N-heteroannulation of enamines formed by
condensation of 2-nitrobenzenamine with aldehydes,7 reaction of
O-phenylenediamine with the 1,1-dialkyl-2,2-dichloroxirane inter-
mediate generated in situ from ketone and chloroform with aque-
ous sodium hydroxide in a phase-transfer catalyzed reaction.8 In
this letter, we report an alternative convenient route to dihydro-
quinoxalin-2-ones starting from readily available 2-haloanilines
1,6 but in only 21% yield (Table 1, entry 1). The reaction with the
use of copper (I) iodide and Cs2CO3 in DMSO at 150 °C for 0.5 h pro-
duced 1 in 63% yield (entry 2). When the reaction was carried out
in DMF, the yield has decreased (entry 3). A reaction in dioxane
gave no desired product to recover only starting materials (entry
4). Copper (I) bromide also catalyzed the reaction but with the
moderate efficiency (entry 5). The use of potassium carbonate re-
sulted in the comparable yield (entry 6). The better result was ob-
served when 2-bromoaniline was used as substrate with longer
reaction time (5 h) and lower temperature (125 °C, entry 7) to pro-
duce 1 in 74% yield.11 When 2-chloroaniline was employed as a
substrate, a significant decrease of reactivity was observed to pro-
vide desired product 2 in 65% yield at higher temperature (entry 8).
A reaction of 20-bromoacetoanilide with pipecolinic acid gave no
corresponding quinoxalinone and also coupling intermediate to re-
cover the starting materials (entry 9). A control experiment with-
out the use of copper catalyst gave no desired product to recover
the starting materials (entry 10). The presence of base was essen-
tial for smooth progress of the reaction (entry 11).
A variety of substituents on aromatic ring, which include the
electron-donating and electron–withdrawing groups, were feasi-
ble to provide the corresponding dihydroquinoxalin-2-ones
(2–7) in moderate to excellent yield by the use of optimized
conditions (Table 2, entry 7). 4-Methyl, 5-trifluoromethoxy, and
4-chloro-2-bromoaniline gave the depicted tricycles (2, 3 and
4) in excellent yield (entries 1–3). Instability of cyano group over
the reaction conditions would attribute to the low yield in entry
4. The reaction rate was suppressed by the substitution of the
strong electron-withdrawing group such as nitro group (entry
and
a
-amino acids by the use of copper catalyst.9 The cytotoxic
activities of synthesized quinoxalin-2-ones toward HeLa cell lines
are also reported.
Reaction of 2-iodoaniline and pipecolinic acid in the presence of
[Pd(g
3-C3H5)Cl]2, (2-biphenyl)di-t-butylphosphine10 and Cs2CO3 in
dioxane at reflux for 15 h gave desired tricyclic quinoxalin-2-one
* Corresponding author.
E-mail address: tanimori@bioinfo.osakafu-u-ac.jp (S. Tanimori).
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.06.007

4120
S. Tanimori et al. / Bioorg. Med. Chem. Lett. 19 (2009) 4119–4121
Table 1
Reaction of 2-haloaniline with pipecolinic acid under various conditionsa
catalyst
X
+
NHR
N
base, solvent
N
H
COOH
N
H
1
O
Entry
X
R
Catalyst (mol %)
[Pd(
3-C3H5)Cl]2 (5)/L (10)c
Base
Solvent
Conditions
Yieldb (%)
1
2
3
4
5
6
7
8
9
I
I
I
I
I
I
Br
Cl
Br
I
H
H
H
H
H
H
H
H
Ac
H
H
g
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
K2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
None
Dioxane
DMSO
DMF
120 °C, 15 h
150 °C, 30 min
150 °C, 30 min
120 °C, 15 h
150 °C, 30 min
150 °C, 30 min
125 °C, 5 h
175 °C, 6 h
125 °C, 5 h
150 °C, 5 h
150 °C, 1 h
21
63
37
0
43
51
74
65
0
CuI (10)
CuI (10)
CuI (10)
CuBr (10)
CuI (10)
CuI (10)
CuI (10)
CuI (10)
None
Dioxane
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
10
11
0
15
I
CuI (10)
a
Reaction conditions: 2-haloaniline (1.0 mmol), pipecolinic acid (2.0 mmol), copper catalyst (0.1 mmol), base (2.0 mmol), solvent (1.5 mL) under N2.
Isolated yield.
L = (2-biphenyl)di-tert-butylphosphine.
b
c
Table 2
Table 3
Reaction of pipecolinic acid with substituted O-haloanilines and pyridines and
cytotoxic activities
Reaction of 2-bromoaniline with
a
-amino acids and cytotoxic activity
R1
N
Z
Z
Br
R1HN
Br
CuI (10 mol%)
R2
R3
Z
Z
N
R2
CuI (10 mol%)
+
Y
R3
+
Cs2CO3 (2 equiv)
DMSO, 125 ºC, 5 h
N
H
COOH
NH2
Cs2CO3 (2 equiv)
DMSO, 125 ºC, 5 h
N
H
O
NH2
HOOC
N
H
O
Z=CH, N
Yielda (%)
IC50
(l
M)
b
Entry
Aniline
Product
Yielda (%)
IC50
(
lM)
b
Entry
Amino acid
Product
Me
Br
NH2
Me
N
1
2
3
4
5
6
7
84
81
78
42
61
59
42
18.1
>30
4.96
7.6
N
N
H
O
1
58
62
43
56
76
86
>30
>30
>30
>30
N
H
O
O
N
H
COOH
N
Br
NH2
9
N
CF3O
Cl
N
H
O
CF3O
Cl
2
N
H
COOH
N
H
103, 4
N
Br
H
N
N
H
O
NH2
3c
4c
5
N
H
O
H2N
COOH
113, 7
NC
N
NC
Br
H
N
N
H
O
NH2
NH2
N
H
O
COOH
N
128
Br
>30
>30
>30
N
H
O
O
O2N
Me
H
N
O2N
Me
NH2
COOH
4.85
>30
N
H
O
O
N
Br
NH2
135
14
N
N
H
NH2
N
H
N
COOH
NH2
6
N
H
N
N
N
Br
N
H
O
NH2
8
a
Isolated yield.
HeLaS3 cell line.
b

S. Tanimori et al. / Bioorg. Med. Chem. Lett. 19 (2009) 4119–4121
4121
Mason, G. S.; Boyce, S.; Freidinger, R. M.; Bock, M. G. J. Am. Chem. Soc. 2003, 125,
7516.
3. TenBrink, R. E.; Im, W. B.; Sethy, V. H.; Tang, A. H.; Carter, D. B. J. Med. Chem.
1994, 37, 758.
4. Abou-Gharbia, M.; Freed, M. E.; McCaully, R. J.; Silver, P. J.; Wendt, R. L. J. Med.
Chem. 1984, 27, 1743.
5. Jiang, Q.; Jiang, D.; Jiang, Y.; Fu, H.; Zhao, Y. Synlett 2007, 1836.
6. Chicharro, R.; Castro, S.; Reino, J. L.; Aran, V. J. Eur. J. Org. Chem. 2003, 2314; Alo,
B. I.; Avent, A. G.; Hanson, J. R.; Ode, A. E. J. Chem. Soc., Perkin Trans. 1 1988,
1997.
Table 3 (continued)
Yielda (%)
68
IC50
>30
(lM)
b
Entry
Amino acid
Product
H
N
COOH
NH2
7
N
H
O
15
H
7. Soderberg, B. C. G.; Wallace, J. M.; Tamariz, J. Org. Lett. 2002, 4, 1339.
8. Lai, J. T. Synthesis 1982, 71.
9. Ma et al. recently reported the similar reaction using 2-
N
Cl
COOH
NH2
8d
40
17.2
N
H
O
halotrifluoroacetanilides with pyrrole-2-carboxylate esters in the presence of
CuI and
L-proline to produce pyrrole[1,2-a]quinoxalines. They reported that the
yield of a reaction using free aniline derivative lowered. The use of free
carboxylic acid has not been reported, see: Yuan, Q.; Ma, D. J. Org. Chem. 2008,
73, 5159.
16
a
Isolated yield.
HeLaS3 cell line.
2-Bromoaniline was used.
b
c
10. Aranyos, A.; Old, D. W.; Kiyomori, A.; Wolfe, J. P.; Sadighi, J. P.; Buchwald, S. L. J.
Am. Chem. Soc. 1999, 121, 4369.
d
2-Bromo-4-chloroaniline was used.
11. General Procedure: 16: A suspension of 2-bromoaniline (0.15 g, 0.89 mmol), dl-
pipecolinic acid (0.23 g, 1.76 mmol), cesium carbonate (0.58 g, 1.78 mmol), and
cuprous(I) iodide (17 mg, 0.089 mmol) in dry DMSO (1 mL) was deoxygenated
with nitrogen gas. The reaction mixture was then stirred at 125 °C under
nitrogen for 5 h. The mixture was treated with saturated aqueous solution of
ammonium chloride (20 mL) and the mixture was extracted three times with
EtOAc. The combined organic layer was washed with water and brine, and
dried over magnesium sulfate. After filtration, solvent was evaporated in vacuo
5). Halogenated pyridinylamine derivatives shown in entries 6
and 7 also reacted to form triazaphenanthrenones (7 and 8) in
moderate to good yields.
We next investigated the reaction using a series of
a-amino
acids and the results were summarized in Table 3.12 The diverse
amino acids including bicyclic (entry 1), five membered (proline,
to ca. 1 mL and crystallization afforded quinoxalinone
crystals.
1 (93 mg, 74%) as
Selected data, 1: ½a D22
ꢀ
+16.4 (c 0.45, CHCl3); 1H NMR d (CDCl3): 1.49 (1H, tq,
entry 2),
a,
a0-disubstituted (entries 3 and 4), and sterically hin-
J = 3.7, 12.9 Hz), 1.58–1.80 (4H, m), 1.96 (1H, br d, J = 12.4 Hz), 2.23 (1H, ddd,
J = 1.7, 3.2, 13.4 Hz), 2.74 (1H, dt, J = 3.4, 12.4 Hz, N–CH2), 3.55 (1H, dd, J = 3.2,
11.7 Hz, N–CH2), 3.79 (1H, br d, J = 12.4 Hz, CH–CO), 6.73 (1H, dd, J = 1.2,
7.6 Hz, Ar-H), 6.76–6.84 (2H, m, Ar-H), 6.99 (1H, t, J = 7.3 Hz, Ar-H), 8.49 (1H, br
s, NH). 13C NMR d (CDCl3): 23.3, 23.7, 26.8, 46.6, 59.8, 112.2, 115.3, 119.4,
124.1, 126.2, 135.6, 169.3 (C@O). FAB-MS (3-NBA) m/z (%): 202 (M+, 100), 173
((M-CO)+, 16), 136 (39).
dered (entry 7) ones were acceptable to produce desired quinoxa-
lin-2-ones in moderate to good yield.
Finally, cytotoxic activity of synthesized compounds toward
HaLaS3 cell lines was investigated (Tables 2 and 3).13 The cytotox-
icity examination is frequently used as the first stage screening for
the discovery of anti-cancer agent. Compounds 2, 4, 5, 13 and 16
Compound 1211 1H NMR d (CDCl3): 1.30–1.50 (3H, m), 1.66–1.74 (6H, m), 1.83–
:
1.93 (2H, m), 4.20 (1H, br s, NH), 6.68–6.80 (3H, m), 6.90 (1H, t, J = 7.6 Hz), 8.08
(1H, br s). 13C NMR d (CDCl3): 20.7, 25.0, 31.4, 56.8, 114.6, 114.8, 119.4, 123.6,
125.7, 132.4, 171.2.
have activities at 18.1, 4.96, 7.6, 4.85 and 17.2 lM (IC50), respec-
tively, and another compounds have no effect. It was assumed that
the substituent at C-2 (compounds 2, 4 and 5) and C-6 (compound
16) position would play an important role to exhibit the cytotoxic-
ity except for compound 13. There are a lot of reports dealing with
the cytotoxic activity of quinoxaline derivatives to show moderate
to excellent activity.14
In summary, we have found a new copper-catalyzed facile
method to synthesize quinoxaline-2-ones and some of quinoxali-
nones have moderate cytotoxic activity. Other biological studies
are now in progress.
Compound 15: ½a 2D2
ꢀ
+96.1 (c 0.5, CHCl3); 1H NMR d (CDCl3): 0.99 (9H, s, t-Bu),
3.67 (1H, s, CH), 4.23 (1H, br s, NH), 6.57–6.66 (2H, m), 6.70 (1H, d, J = 7.3 Hz),
6.82 (1H, t, J = 7.3 Hz), 9.63 (1H, br s, NH). 13C NMR d (CDCl3): 26,5 (3 ꢁ C), 37.6,
64.9, 112.3, 115.0, 118.1, 123.7, 124.8, 133.4, 166.9. FAB-MS (3-NBA) m/z (%):
205 (MH+, 100), 148 ((M-t-Bu)+, 82).
Compound 16: Rf 0.52 (1:1 hexane/AcOEt); ½a D22
ꢀ
+ 47.3 (c 0.5, CHCl3); 1H NMR
(400 MHz, CDCl3) d 9.65 (br s, 1H, NH), 6.85–6.62 (m, 3H, Ar), 4.11 (s, 1H, NH),
3.87–3.82 (m, 1H, NHCH), 2.02–1.83 (m, 1H, CHCH3), 1.60–1.48 (m, 1H, one of
CH3CH2), 1.30–1.15 (m, 1H, one of CH3CH2), 1.02 (d, 3H, J = 7.1 Hz, CHCH3), 0.89
(t, 3H, J = 7.3 Hz, CH2CH3); 13C NMR (136 MHz, CDCl3) d 168.2, 134.2, 128.7,
123.4, 118.2, 116.1, 113.0, 60.8, 37.9, 24.4, 15.3, 11.4; IR (neat, cmꢂ1) 3061
(NH), 1673 (C@O), 1507, 1404, 1083, 922, 800; MS (FAB) m/z 238 [M+], 239
[MH+], 181, 120, 107.
12. Although chiral amino acids were employed in entries 2, 5, 6, 7, and 8 (Table 3),
the optical purities of products were unknown at present.
Acknowledgment
13. Exponentially growing cells were treated with different concentrations of test
compounds for 48 h and cell growth inhibition was analyzed through MTT
assay. IC50 is defined as the concentration, which results in a 50% decrease in
cell number as compared with that of the control cultures in the absence of an
inhibitor and were calculated using the respective regression analysis.
14. For selected examples, see: Urquiola, C.; Vieites, M.; Torre, M. H.; Cabrera, M.;
Lavaggi, M. L.; Cerecetto, H.; Gonzalez, M.; de Cerain, A. L.; Monge, A.; Smircich,
P.; Garat, B.; Gambino, D. Bioorg. Med. Chem. 2009, 17, 1623; Driller, K. M.;
Libnow, S.; Hein, M.; Harms, M.; Wende, K.; Lalk, M.; Michalik, D.; Reinke, H.;
Langer, P. Org. Biomol. Chem. 2008, 6, 4218; Yan, L.; Liu, F.-W.; Dai, G.-F.; Liu, H.-
M. Bioorg. Med. Chem. Lett. 2007, 17, 609; Carta, A.; Sanna, P.; Loriga, M.; Setzu,
M. G.; La Colla, P.; Loddo, R. Farmaco 2002, 5, 19; Lawrence, D. S.; Copper, J. E.;
Smith, C. D. J. Med. Chem. 2001, 44, 594.
We thank Drs. M. Yamada, T. Emura, and S. Okazaki (Taiho Phar-
maceutical Co., Ltd.) for the evaluation of cytotoxic activities.
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