Synthesis and biological evaluation of novel 2-arylamino-3-(arylsulfonyl) quinoxalines as PI3Kα inhibitors

Article abstract of DOI:10.1016/j.ejmech.2011.09.015

A series of novel 2-arylamino-3-(arylsulfonyl)quinoxalines was synthesized through a newly developed approach. All synthesized target compounds were screened for their cytotoxicities against cancer cell lines including PC3, A549, HCT116, HL60 and KB. Representative compounds with favorable cytotoxicities were tested for their PI3Kα inhibitory activities. Among the synthesized target compounds, 17 (PI3Kα IC₅₀: 0.07 μM) displayed the most potent cellular activities (IC₅₀ values of 0.14 μM, 0.07 μM, 0.95 μM and 0.05 μM against PC3, A549, HCT116 and HL 60, respectively).

Full text of DOI:10.1016/j.ejmech.2011.09.015

European Journal of Medicinal Chemistry 46 (2011) 5540e5548
Contents lists available at SciVerse ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and biological evaluation of novel 2-arylamino-3-(arylsulfonyl)
quinoxalines as PI3K inhibitors
a
Peng Wua, Yi Sub, Xiaowen Liub, Lei Zhangb, Yong Yea, Jianchao Xua, Shaoyu Wenga, Yani Lia, Tao Liua,
,
Shufang Huanga, Bo Yangb, Qiaojun Heb, Yongzhou Hua
*
a ZJU-ENS Joint laboratory of Medicinal Chemistry, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
b Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of novel 2-arylamino-3-(arylsulfonyl)quinoxalines was synthesized through a newly developed
approach. All synthesized target compounds were screened for their cytotoxicities against cancer cell
lines including PC3, A549, HCT116, HL60 and KB. Representative compounds with favorable cytotoxicities
Received 5 August 2011
Received in revised form
5 September 2011
Accepted 12 September 2011
Available online 17 September 2011
were tested for their PI3K
IC50: 0.07 M) displayed the most potent cellular activities (IC50 values of 0.14
0.05 M against PC3, A549, HCT116 and HL 60, respectively).
a
inhibitory activities. Among the synthesized target compounds, 17 (PI3K
a
m
m
M, 0.07 M, 0.95 M and
m
m
m
Ó 2011 Elsevier Masson SAS. All rights reserved.
Keywords:
2-Arylamino-3-(arylsulfonyl)quinoxaline
PI3K
PI3Ka
Cytotoxicity
1. Introduction
quinoxaline core which is a favored lead structure for antitumor
agents [10] and structural features of XL-765 and XL-147, a series of
novel 2-arylamino-3-(arylsulfonyl)quinoxalines was designed
incorporating the following concepts: 1) retaining the 2,3-
disubstituted quinoxaline core scaffold, 2) lending and mimicking
the 2-arylamine substituent from that of XL-765; 3) simplifying the
arylsulfonamide substituent by replacing it with arylsulfonyl
substituent to investigate its impact on binding mode with PI3K.
We report herein the synthesis and biological evaluation of this
Phosphoinositide 3-kinases (PI3Ks), key components of the
PI3 K/Akt/mTOR pathway which plays essential roles in various
cellular activities, are lipid kinases that phosphorylate the
3-hydroxyl group of phosphoinositides [1]. Three classes of PI3Ks
have been identified within the PI3K family, with the
class I PI3K, PI3K , being of crucial importance in tumorgenesis [2].
Either gain-of-function mutations in Pik3ca, the gene encodes the
p110 catalytic subunit of PI3K , or loss-of-function mutations in
a isoform of
a
a
a
new series of PI3Ka inhibitors, together with a preliminary struc-
PTEN, a phosphatase catalyzes the dephosphorylation process,
leads to the activation of PI3K signaling, which is a common
phenomenon in many human cancers. Thus, a strong interest has
tureeactivity relationship (SAR) study of the target compounds
based on in vitro data.
been stimulated in targeting PI3Ks, especially PI3Ka, for cancer
therapy [3e6].
2. Results and discussion
Considerable PI3K inhibitors have been identified since the
unfolding of the very first two PI3K inhibitors, LY294002 and
wortmannin (Fig. 1a and b) [7,8], and several of them with varied
chemical scaffolds are currently under clinical trials in varied
phases, such as the two quinoxaline derivatives XL-765 and XL-147,
which are currently in phase I and II trials for cancer treatment
developed by Exelixis and Sanofi (Fig. 1c) [9]. Based on the
2.1. Chemistry
The synthesis of target 2-arylamino-3-(arylsulfonyl)quinoxa-
lines 15e59 is outlined in Scheme 1. Reaction of benzene-1,2-
diamine (1) with diethyl oxalate in refluxing 4 N HCl aqueous
solution gave quinoxaline-2,3-dione (2), whose chlorination with
SOCl2 in the presence of DMF afforded 2,3-dichloroquinoxaline (3)
[11]. Treatment of arylsulfonyl chloride (4) with 85% hydrazine
hydrate in H2O gave arylsulfonylhydrazides (5e9) [12]. We found
accidentally that the reaction of arylsulfonylhydrazides with 2,3-
* Corresponding author.
E-mail address: huyz@zjuem.zju.edu.cn (Y. Hu).
0223-5234/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.09.015

P. Wu et al. / European Journal of Medicinal Chemistry 46 (2011) 5540e5548
5541
2.2. Biological activity and molecular modeling
2.2.1. Cytotoxicity
The obtained 2-arylamino-3-(arylsulfonyl)quinoxalines 15e59
were tested for their cytotoxicities in vitro against five human
cancer cell lines including human pancreatic carcinoma cells PC3,
human lung adenocarcinoma epithelial cells A549, human colon
cancer cells HCT116, human promyelocytic leukemia cells HL60,
and human nasopharyngeal carcinoma cells KB. The widely used
PI3K pan-inhibitor LY294002 as mentioned above was used as the
positive control [7,16]. The results are summarized in Table 1.
As shown in Table 1, a significant improvement in cytotoxicity
against five tested cell lines comparing with that of LY294002 was
observed for almost all target compounds. A glimpse of different
substituents at the 4-position of sulfonylphenyl ring showed that
introduction of methyl, methoxy, bromo or fluoro group had
limited effect on cytotoxicity. Comparing the various substituents
on the aminophenyl ring revealed that unsubstituted aminophenyl
ring and the presence of 4-methoxy, 3,5-dimethoxy, 3,4,5-
trimethoxy, 4-amino, 3-amino, 3-hydroxy and 4-trifluoromethyl
are favored for cellular potencies, while the existence of either
a fluoro or chloro atom is attached with reduced potencies. For
example, compound 15 (PC3, IC50: 0.59
aminophenyl ring, 16 (PC3, IC50: 1.51
group on aminophenyl ring and 24 (PC3, IC50: 3.55
trifluoromethyl group on aminophenyl ring showed better
m
M) with unsubstituted
M) with a 4-dimethoxy
M) with a 4-
m
m
potency than that of 22 (PC3, IC50: 14.15
on aminophenyl ring and 23 (IC50: 15.26
m
M) with a 4-fluoro group
mM) with a 4-chloro group
on aminophenyl ring. It is interesting that compound 17, 2-(3,5-
dimethoxyphenylamino)-3-(phenylsulfonyl)quinoxaline, exhibited
the most potent cytotoxicity against all tested cell lines, with IC50
values in the range of 0.05e0.95 mM.
2.2.2. PI3K
Selected compounds 17, 21, 31, 41, and 51, were evaluated for
their PI3K enzymatic activity using a competitive fluorescence
a enzymatic activity
Fig. 1. Structures of LY294002 (a) and wortmannin (b), and the design concept based
on XL-765 and XL-147 (c).
a
polarization kinase activity assay [17]. The results are presented in
Table 2.
dichloroquinoxaline (3) in refluxing ethanol yielded 2-chloro-3-
(arylsulfonyl)quinoxalines (10e14) rather than 2-chloro-3-(aryl-
sulfonylhydrazide)quinoxalines. It is a novel and one-pot route to
synthesize arylsulfonylquinoxalines in comparison with the known
methods [13e15]. Finally, treatment of 2-chloro-3-(arylsulfonyl)
quinoxalines (10e14) with arylamines in refluxing toluene afforded
the target compounds (15e59).
The most potent compound 17 exhibited PI3K
activity of 0.07 M, which is almost ten-fold better than that of
LY294002 (PI3K IC50: 0.63 M) [16]. Although there was no
a inhibitory
m
a
m
obvious disparity among the cytotoxicities of 21, 31, 41, and 51,
compound 51 with a 4-bromo group on the sulfonylphenyl ring
displayed better PI3Ka inhibitory activity, it seemed that the
Scheme 1. The synthetic route for target compounds 15e59. Reagents and conditions: (a) 4 N HCl (aq.), oxalic acid diethyl ester, reflux; (b) SOCl2, DMF, reflux; (c) hydrazine hydrate,
H2O, 0 ꢀC-r.t.; (d) ethanol, reflux; (e) arylamines, toluene, reflux.

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P. Wu et al. / European Journal of Medicinal Chemistry 46 (2011) 5540e5548
Table 1
Cytotoxicity in vitro of target compounds against five cancer cell lines.
R2
N
N
NH
O
S
O
R1
R1
R2
Cytotoxicity IC50
PC3
(mM)
a
Compound
A549
HCT116
HL60
KB
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
LY294002
H
H
H
H
H
H
H
H
H
0.59
1.51
0.14
29.13
5.83
2.15
1.68
14.15
15.26
3.55
1.06
>50
2.94
4.85
5.00
2.00
1.69
13.07
9.66
2.54
1.26
8.71
6.22
7.85
9.64
8.60
1.63
2.20
31.79
0.33
1.18
1.11
18.15
19.81
2.33
9.01
1.70
9.16
7.46
4.15
4.33
4.53
>50
2.05
1.98
61.35
26.27
11.9
0.07
9.66
12.85
1.59
5.73
>50
30.74
>50
12.53
>50
8.06
5.61
24.56
1.95
6.08
39.22
54.23
13.46
13.19
8.26
12.71
5.17
2.99
0.34
6.11
1.24
87.30
4.81
10.76
3.34
15.85
6.11
1.02
1.12
8.00
4.36
61.42
>50
4.84
5.45
>50
12.69
6.84
89.65
1.63
2.42
0.95
>50
10.77
1.54
1.15
5.19
2.00
2.09
1.07
>50
>50
10.76
11.53
2.39
3.81
10.5
2.05
0.95
1.26
29.06
13.44
>50
6.30
3.71
0.82
2.11
26.49
0.11
1.11
3.4
>50
13.01
1.39
3.28
0.54
1.67
10.62
2.61
3.01
3.93
3.11
10.06
6.79
56.01
0.14
0.64
0.05
1.77
8.72
1.75
0.22
1.01
1.92
0.30
0.40
2.79
0.02
0.32
1.22
1.08
0.40
5.10
17.52
0.27
0.26
1.19
1.71
0.68
0.71
1.49
0.14
0.61
19.61
0.22
0.13
1.19
2.54
1.02
0.73
1.37
0.20
0.26
16.39
0.28
1.20
2.36
4.79
1.62
4.04
9.94
22.58
NTb
4-Methoxy
3,5-Dimethoxy
3,4,5-Trimethoxy
4-Amino
3-Amino
3-Hydroxy
4-Fluoro
4-Chloro
4-Trifluoromethyl
H
4-Methoxy
3,5-Dimethoxy
3,4,5-Trimethoxy
4-Amino
3-Amino
3-Hydroxy
4-Fluoro
4-Chloro
4-Trifluoromethyl
H
4-Methoxy
3,5-Dimethoxy
3,4,5-Trimethoxy
4-Amino
3-Amino
3-Hydroxy
4-Fluoro
NTb
NTb
3.4
4.29
8.42
>50
41.23
>50
18.98
NTb
H
H
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methoxy
Methoxy
Methoxy
Methoxy
Methoxy
Methoxy
Methoxy
Methoxy
Methoxy
Methoxy
Bromo
Bromo
Bromo
Bromo
Bromo
Bromo
Bromo
Bromo
Bromo
Bromo
Fluoro
Fluoro
Fluoro
Fluoro
Fluoro
e
NTb
NTb
5.63
10.57
5.35
8.95
13.78
10.3
9.89
NTb
NTb
NTb
17.75
4.96
8.27
2.59
49.83
0.89
5.10
NTb
4-Chloro
4-Trifluoromethyl
H
4-Methoxy
3,5-Dimethoxy
3,4,5-Trimethoxy
4-Amino
3-Amino
3-Hydroxy
4-Fluoro
NTb
NTb
4.08
5.34
8.41
2.28
11.58
>50
NTb
4-Chloro
4-Trifluoromethyl
4-Methoxy
3,5-Dimethoxy
3,4,5-Trimethoxy
4-Amino
NTb
NTb
NTb
3-Amino
NTb
44.76
a
IC50, the mean value of at least two separate determinations.
NT, not tested.
b
Table 2
PI3K
presence of a 4-bromo group on the sulfonylphenyl ring is favored
for PI3K inhibition. Thus, other inhibition mechanism, which
hasn’t been identified yet, might contribute to their overall potent
a
inhibitory activities of 2-phenylamino-3-(phenylsulfonyl)quinoxalines.
a
R1
R2
PI3Ka
IC50
(
m
M)
a
Compound
17
21
31
41
H
H
3,5-Dimethoxy
3-Hydroxy
3-Hydroxy
3-Hydroxy
3-Hydroxy
0.07
>1
>1
>1
0.47
0.63
cellular performance.
Methyl
Methoxy
Bromo
e
2.2.3. Western blot analysis
To determine whether target compounds suppress activation of
Akt, a key downstream effector of PI3K and important node in the
PI3 K/Akt/mTOR signaling pathway [18], selected compounds 17,
26, 27, and 49 were tested for their suppressive effects on
51
LY294002b
a
IC50, the mean value of at least two separate determinations.
Reported value, reference no. 16.
b

P. Wu et al. / European Journal of Medicinal Chemistry 46 (2011) 5540e5548
5543
amino group of Lys833 (distance: 2.07 Å), and the third hydrogen
bond interaction between one of the quinoxaline nitrogens and the
carboxylate group of Asp964 (distance: 3.01 Å). The docking result
of LY294002 with PI3Kg indicated the existence of a hydrogen bond
interaction between the morpholino oxygen and the hinge of
Val882 (distance 1.96 Å), which is consistent with reported X-ray
co-crystal analysis (Fig. 3b and d) [22e24]. Comparing the binding
mode of compound 17 bound to PI3Kg and LY294002 bound to
PI3K revealed that the significantly improved potency of
g
compound 17 might be attributed to the following two facets:
firstly, compound 17 forms additional hydrogen bond interactions
besides the crucial one with Val882; and secondly, compound 17 is
better accommodated into the ATP-binding pocket, fills empty
space and increases hydrophobic interactions within the pocket
near Lys833.
Fig. 2. Suppression of target compounds 17, 26, 27, 49 on pAkt(Ser473) in PC3 cells.
PC3 cells were treated with 10 M of target compounds for 3 h. After treatment, the
cell lysate was subjected to SDS-PAGE and Western blot analysis. Actin was used as the
internal control.
m
3. Conclusion
A series of forty five novel 2-arylamino-3-(arylsulfonyl)qui-
noxalines 15e59 was synthesized as PI3K
a inhibitors through
pAkt(Ser473) level in PC3 cells. As shown in Fig. 2, compounds 17,
27, and 49 decreased the protein levels of pAkt(Ser473) with
different extent, while compound 26, which showed comparatively
weak cytotoxicity, exhibited little inhibitory effect on pAkt(Ser473)
level.
a newly developed approach. In vitro biological evaluation against
five human tumor cell lines revealed that most target compounds
showed impressively better cellular potencies than that of
LY294002. The most potent compound, 17 showed a PI3K
a inhibi-
tory activity of 0.07 M, an approximately ten-fold increase in
m
comparison with LY294002. This study validated the potential of
developing 2-arylamino-3-(arylsulfonyl)quinoxaline series as
2.2.4. Molecular modeling
To examine possible binding mode between compound 17 and
a means for cancer treatment by targeting PI3K
a.
PI3K
Discovery Studio 2.1 software package was performed using co-
crystallography of the more amenable PI3K as a surrogate since
the co-crystal structure of PI3K with a small ligand inhibitor has
not been resolved yet [19e21]. The docking result indicated three
hydrogen bond interactions between compound 17 and PI3K
(Fig. 3a and c): the oxygen of 3-methoxy on aminophenyl ring
forms a key hydrogen bond with the hinge of Val882 (distance:
2.80 Å), one of the sulfonyl oxygens forms an interaction with the
a, a docking analysis utilizing the C-DOCKER program within
4. Experimental
g
a
4.1. Chemistry
g
Melting points were determined with a B-540 Büchi apparatus
and are uncorrected. IR spectra were performed on a Brüker
VECTOR
22
FTIR
spectrophotometer
in
KBr
pellets
(400e4000 cmꢁ1). NMR spectra were recorded on a Brüker 500
Fig. 3. Docking mode comparison between compound 17 and LY294002. (a) Ribbon show of compound 17 bound to PI3K
g; (b) ribbon show of LY294002 bound to PI3Kg; (c) surface
show of compound 17 docked into PI3K ; (d) surface show of LY294002 docked into PI3K . Selected residues ASP964, LYS833 and VAL882 are shown in green backbones, orange
g
g
dashed lines indicate hydrogen bonds, prepared using PyMOL, PDB ID: 3L54. (For interpretation of the references to color in this figure legend, the reader is referred to the web
version of this article.)

5544
P. Wu et al. / European Journal of Medicinal Chemistry 46 (2011) 5540e5548
(500 MHz) spectrometer (chemical shifts are given in ppm(
d
)
4.1.2.1. 2-Phenylamino-3-(phenylsulfonyl)quinoxaline (15). Orange
solid, yield: 18%, mp: 200e202 ꢀC. IR (KBr, cmꢁ1): 3448 (NH), 1619
relative to TMS as internal standard, coupling constants (J) are in
hertz (Hz), and signals are designated as follows: s, singlet; d,
doublet; t, triplet; m, multiplet; br s, broad singlet, etc.) Mass
spectra (MS), ESI (positive) were recorded on an Esquire-LC-00075
spectrometer. Thin layer chromatography was carried out using
plate silica gel F254 Merck. All yields are unoptimized and generally
represent the result of a single experiment.
(aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
d 9.59 (s, 1H,
NH), 8.16 (d, 2H, J ¼ 7.5 Hz, aromatic H), 7.89 (dt, 3H, J ¼ 7.5 and
1.0 Hz, aromatic H), 7.78e7.77 (m, 1H, J ¼ 7.5 Hz, aromatic H),
7.71e7.67 (m, 2H, aromatic H), 7.60 (t, 2H, J ¼ 7.5 Hz, aromatic H),
7.48e7.41(m, 3H, aromatic H), 7.18 (t, 1H, J ¼ 7.5 Hz, aromatic H).
ESI-MS (m/z): 362 [Mþ1]þ.
4.1.1. General procedure for the synthesis of 2-chloro-3-
(arylsulfonyl)quinoxalines (10e14)
4.1.2.2. 2-(4-Methoxyphenylamino)-3-(phenylsulfonyl)quinoxaline
(16). Red solid, yield 28%, mp: 188e192 ꢀC. IR (KBr, cmꢁ1): 3448
(NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
2,3-Dichloroquinoxaline (3, 10 mmol) was dissolved in 50 mL
anhydrous ethanol, to which was gradually added arylsulfonylhy-
drazine (5e9, 10 mmol), refluxed for 100 min. The cooled reaction
mixture was then filtered and the filtrate was concentrated under
reduced pressure. The obtained residue was purified over silica gel
chromatography eluting with PE: EtOAc (10:1, v/v) to afford
yellowish to yellow solid.
d
9.36 (s, 1H, NH), 8.16 (d, 2H, J ¼ 7.5 Hz, aromatic H), 7.83 (d, 1H,
J ¼ 8.0 Hz, aromatic H), 7.76 (d, 2H, J ¼ 8.5 Hz, aromatic H),
7.72e7.64 (m, 3H, aromatic H), 7.60 (t, 2H, J ¼ 8.0 Hz, aromatic H),
7.43 (t, 1H, J ¼ 8.0 Hz, aromatic H), 6.97 (d, 2H, J ¼ 8.5 Hz, aromatic
H), 3.85 (s, 3H, OCH3). ESI-MS (m/z): 392 [Mþ1]þ.
4.1.2.3. 2-(3,5-Dimethoxyphenylamino)-3-(phenylsulfonyl)quinoxa-
line (17). Yellow solid, yield: 36%, mp: 149e151 ꢀC. IR (KBr, cmꢁ1):
3452 (NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz,
4.1.1.1. 2-Chloro-3-(phenylsulfonyl)quinoxaline (10). Yield 25%, mp:
155e157 ꢀC. 1H NMR (500 MHz, CDCl3):
d
8.02 (d, 2H, J ¼ 8.5 Hz,
aromatic H), 7.77 (d, 1H, J ¼ 8.0 Hz, aromatic H), 7.71 (d, 1H,
J ¼ 8.0 Hz, aromatic H), 7.65e7.62 (m, 2H, aromatic H), 7.56 (t, 2H,
J ¼ 8.0 Hz, aromatic H), 7.48 (dt, 1H, J ¼ 8.0 and 1.0 Hz, aromatic H).
ESI-MS (m/z): 305 [Mþ1]þ.
CDCl3): d 9.58 (s, 1H, NH, also confirmed by hydrogen/deuterium
exchange experiment), 8.16 (d, 2H, J ¼ 8.0 Hz, aromatic H), 7.88 (d,
1H, J ¼ 8.5 Hz, aromatic H), 7.78 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.71
(q, 2H, J ¼ 8.0 Hz, aromatic H), 7.60 (t, 2H, J ¼ 8.0 Hz, aromatic H),
7.49 (t, 1H, J ¼ 8.0 Hz, aromatic H), 7.16 (d, 2H, J ¼ 1.5 Hz, aromatic
H), 6.29 (s, 1H, aromatic H), 3.86 (s, 6H, OCH3). 13C NMR (125 MHz,
4.1.1.2. 2-Chloro-3-(4-methylphenylsulfonyl)quinoxaline (11). Yield
23%, mp: 129e130 ꢀC. 1H NMR (500 MHz, CDCl3):
d
7.90 (d, 2H,
CDCl3): d 161.24 (2), 145.87, 142.70, 142.30, 140.43, 138.53, 136.30,
J ¼ 8.5 Hz, aromatic H), 7.77 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.68 (m,
2H, aromatic H), 7.50 (t, 1H, J ¼ 8.0 Hz, aromatic H), 7.33 (d, 2H,
J ¼ 8.0 Hz, aromatic H), 2.44 (s, 3H, CH3). ESI-MS (m/z): 319 [Mþ1]þ.
134.64, 133.45, 129.88, 129.45 (2), 129.08 (2), 126.89, 126.80, 98.90
(2), 96.33, 55.61 (2). ESI-MS (m/z): 422.16 [Mþ1]þ.
4.1.2.4. 2-(3,4,5-Trimethoxyphenylamino)-3-(phenylsulfonyl)qui-
noxaline (18). Orange solid, yield 43%, mp: 167e169 ꢀC. IR (KBr,
cmꢁ1): 3452 (NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR
4.1.1.3. 2-Chloro-3-(4-methoxyphenylsulfonyl)quinoxaline
(12). Yield 32%, mp: 165e167 ꢀC. 1H NMR (500 MHz, CDCl3):
d 7.92
(d, 2H, J ¼ 7.5 Hz, aromatic H), 7.79 (d, 1H, J ¼ 9.0 Hz, aromatic H),
7.66 (m, 2H, aromatic H), 7.50 (dt, 1H, J ¼ 8.0 and 1.5 Hz, aromatic
H), 7.00 (dd, 2H, J ¼ 7.0 and 1.5 Hz, aromatic H), 3.88 (s, 3H, OCH3).
ESI-MS (m/z): 335 [Mþ1]þ.
(500 MHz, CDCl3):
d
9.50 (s, 1H, NH), 8.16 (d, 2H, J ¼ 8.0 Hz,
aromatic H), 7.85 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.70e7.67 (m, 3H,
aromatic H), 7.61 (t, 2H, J ¼ 8.0 Hz, aromatic H), 7.47e7.44 (m, 1H,
aromatic H), 7.23 (s, 2H, aromatic H), 3.94 (s, 6H, OCH3), 3.87 (s, 3H,
OCH3). ESI-MS (m/z): 452 [Mþ1]þ.
4.1.1.4. 2-(4-Bromophenylsulfonyl)-3-chloroquinoxaline (13). Yield
18%, mp: 169e171 ꢀC. 1H NMR (500 MHz, CDCl3):
d
7.86 (d, 2H,
4.1.2.5. 2-(4-Aminophenylamino)-3-(phenylsulfonyl)quinoxaline
(19). Red solid, yield 31%, mp: 175 ꢀC. IR (KBr, cmꢁ1): 3457 (NH),
3372 (NH2), 1632 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz,
J ¼ 8.5 Hz, aromatic H), 7.75 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.70 (t,
3H, J ¼ 8.5 Hz, aromatic H), 7.65 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.46
(t, 1H, J ¼ 8.0 Hz, aromatic H). ESI-MS (m/z): 384 [Mþ1]þ.
CDCl3):
d
9.27 (s, 1H, NH), 8.15 (d, 2H, J ¼ 8.0 Hz, aromatic H), 7.83
(d, 1H, J ¼ 8.5 Hz, aromatic H), 7.69e7.63 (m, 3H, aromatic H),
7.61e7.56 (m, 4H, aromatic H), 7.41 (t, 1H, J ¼ 7.5 Hz, aromatic H),
6.76 (d, 2H, J ¼ 8.5 Hz, aromatic H), 3.67 (br s, 2H, NH2). ESI-MS (m/
z): 377 [Mþ1]þ.
4.1.1.5. 2-Chloro-3-(4-fluorophenylsulfonyl)quinoxaline (14). Yield
14%, mp: 146 ꢀC. 1H NMR (500 MHz, CDCl3):
d 8.14e8.11 (m, 2H,
aromatic H), 8.09 (d, 1H, J ¼ 8.5 Hz, aromatic H), 8.05 (d, 1H,
J ¼ 8.5 Hz, aromatic H), 7.96 (dt, 1H, J ¼ 8.5 and 1.0 Hz, aromatic H),
7.87 (dt, 1H, J ¼ 8.5 and 1.0 Hz, aromatic H), 7.31 (t, 2H, J ¼ 8.5 Hz,
aromatic H). ESI-MS (m/z): 323 [Mþ1]þ.
4.1.2.6. 2-(3-Aminophenylamino)-3-(phenylsulfonyl)quinoxaline
(20). Yellow solid, yield 30%, mp: 158e160 ꢀC. IR (KBr, cmꢁ1): 3444
(NH), 3361 (NH2), 1619 (aromatic ring), 1384 (SO2). 1H NMR
4.1.2. General procedure for the synthesis of 2-arylamino-3-
(arylsulfonyl)quinoxalines (15e59)
(500 MHz, CDCl3):
d
9.54 (s, 1H, NH), 8.19 (d, 2H, J ¼ 8.0 Hz,
aromatic H), 7.92 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.83 (d, 1H,
J ¼ 8.5 Hz, aromatic H), 7.75e7.70 (m, 2H, aromatic H), 7.64 (t, 2H,
J ¼ 7.5 Hz, aromatic H), 7.51 (t, 1H, J ¼ 7.5 Hz, aromatic H), 7.41 (s,
1H, aromatic H), 7.28e7.24 (m, 2H, aromatic H), 6.55e6.53 (d, 1H,
J ¼ 6.5 Hz, aromatic H), 3.82 (br s, 2H, NH2). ESI-MS (m/z): 377
[Mþ1]þ.
A mixture of 2-chloro-3-(arylsulfonyl)quinoxalines (10e14,
0.15 mmol) and arylamines (0.3 mmol) in 10 mL toluene was
heated at 110 ꢀC (4 h for compounds 15, 16, 18, 25, 26, 28, 35, 36,
38, 45, 46 and 48, 12 h for compounds 21, 24, 31, 34, 41, 44, 51 and
54, and 7 h for the rest of target compounds). After cooling to
room temperature, the reaction mixture was diluted with ethyl
acetate (30 mL), washed with water and brine, dried over anhy-
drous sodium sulfate. The residue obtained after evaporating
under vacuum was subjected to isolation over silica gel chroma-
tography eluting with PE: EtOAc (6:1 to 2:1, v/v) to afford target
compounds.
4.1.2.7. 2-(3-Hydroxyphenylamino)-3-(phenylsulfonyl)quinoxaline
(21). Yellow solid, yield 15%, mp: 186e187 ꢀC. IR (KBr, cmꢁ1): 3443
(NH), 3375 (OH), 1624 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3):
deuterium exchange experiment), 8.15 (d, 2H, J ¼ 7.5 Hz, aromatic
d 9.58 (s, 1H, NH, also confirmed by hydrogen/

P. Wu et al. / European Journal of Medicinal Chemistry 46 (2011) 5540e5548
5545
H), 7.87 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.80 (d, 1H, J ¼ 8.5 Hz,
aromatic H), 7.72e7.66 (m, 3H, aromatic H), 7.60 (t, 2H, J ¼ 7.5 Hz,
aromatic H), 7.49 (t, 1H, J ¼ 7.5 Hz, aromatic H), 7.30e7.29 (m, 2H,
aromatic H), 6.64 (d, 1H, J ¼ 7.5 Hz, aromatic H), 5.09 (br s, 1H, OH,
also confirmed by hydrogen/deuterium exchange experiment). 13C
7.70 (dt, 1H, J ¼ 8.0 and 1.5 Hz, aromatic H), 7.47 (dt, 1H, J ¼ 8.0 and
1.5 Hz, aromatic H), 7.37 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.15 (d, 2H,
J ¼ 2.0 Hz, aromatic H), 6.29 (t, 1H, J ¼ 2.0 Hz, aromatic H), 3.86 (s,
6H, OCH3), 2.43 (s, 3H, CH3). ESI-MS (m/z): 436 [Mþ1]þ.
NMR (125 MHz, CDCl3):
d
156.26, 145.80, 142.70, 142.28, 140.08,
4.1.2.14. 2-(3,4,5-Trimethoxyphenylamino)-3-tosylquinoxaline
(28). Red solid, yield 21%, mp: 127e129 ꢀC. IR (KBr, cmꢁ1): 3452
(NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
138.48, 136.31, 134.65, 133.48, 130.10, 129.90, 129.44 (2), 129.08 (2),
126.80, 126.78, 112.98, 110.86, 107.58. ESI-MS (m/z): 378 [Mþ1]þ.
d
9.52 (s, 1H, NH), 8.04 (d, 2H, J ¼ 8.0 Hz, aromatic H), 7.86 (d, 1H,
4.1.2.8. 2-(4-Fluorophenylamino)-3-(phenylsulfonyl)quinoxaline
(22). Orange solid, yield 28%, mp: 212e214 ꢀC. IR (KBr, cmꢁ1): 3449
(NH), 1623 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
J ¼ 8.5 Hz, aromatic H), 7.70e7.68 (m, 2H, aromatic H), 7.47e7.43
(m, 1H, aromatic H), 7.40 (d, 2H, J ¼ 8.0 Hz, aromatic H), 7.24 (s, 2H,
aromatic H), 3.94 (s, 6H, OCH3), 3.87 (s, 3H, OCH3), 2.45 (s, 3H, CH3).
ESI-MS (m/z): 466 [Mþ1]þ.
d
9.48 (s, 1H, NH), 8.15 (d, 2H, J ¼ 7.5 Hz, aromatic H), 7.85e7.80 (m,
3H, aromatic H), 7.75 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.70 (t, 2H,
J ¼ 7.5 Hz, aromatic H), 7.61 (t, 2H, J ¼ 7.5 Hz, aromatic H), 7.47 (t,
1H, J ¼ 7.5 Hz, aromatic H), 7.13 (t, 2H, J ¼ 8.5 Hz, aromatic H). ESI-
MS (m/z): 380 [Mþ1]þ.
4.1.2.15. 2-(4-Aminophenylamino)-3-tosylquinoxaline
solid, yield 55%, mp: 190e191 ꢀC. IR (KBr, cmꢁ1): 3449 (NH), 1635
(aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
9.51 (s, 1H,
(29). Red
d
NH), 8.02 (d, 2H, J ¼ 8.0 Hz, aromatic H), 7.88 (d, 1H, J ¼ 8.5 Hz,
aromatic H), 7.78 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.69 (t, 1H,
J ¼ 7.5 Hz, aromatic H), 7.45 (t, 1H, J ¼ 7.5 Hz, aromatic H), 7.37e7.36
(m, 3H, aromatic H), 7.24e7.17 (m, 2H, aromatic H), 6.50 (d, 1H,
J ¼ 8.0 Hz, aromatic H), 3.77 (br s, 2H, NH2) 2.43 (s, 3H, CH3). ESI-MS
(m/z): 391 [Mþ1]þ.
4.1.2.9. 2-(4-Chlorophenylamino)-3-(phenylsulfonyl)quinoxaline
(23). Yellow solid, yield 16%, mp: 203e205 ꢀC. IR (KBr, cmꢁ1): 3452
(NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
d
9.57 (s, 1H, NH), 8.15 (d, 2H, J ¼ 8.0 Hz, aromatic H), 7.86e7.83 (m,
3H, aromatic H), 7.78 (d,1H, J ¼ 8.0 Hz, aromatic H), 7.70 (t,1H, J ¼ 8.
Hz, aromatic H), 7.63e7.58 (m, 3H, aromatic H), 7.49 (t, 1H,
J ¼ 8.0 Hz, aromatic H), 7.39 (d, 2H, J ¼ 8.5 Hz, aromatic H). ESI-MS
(m/z): 396 [Mþ1]þ.
4.1.2.16. 2-(3-Aminophenylamino)-3-tosylquinoxaline
solid, yield 22%, mp: 129e131 ꢀC. IR (KBr, cmꢁ1): 3452 (NH), 1628
(aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
9.51 (s, 1H,
(30). Red
d
4.1.2.10. 2-(4-Trifluoromethylphenylamino)-3-(phenylsulfonyl)qui-
noxaline (24). Yellow solid, yield 20%, mp: 208e209 ꢀC. IR (KBr,
cmꢁ1): 3450 (NH), 1627 (aromatic ring), 1384 (SO2). 1H NMR
NH), 8.02 (d, 2H, J ¼ 8.0 Hz, aromatic H), 7.88 (d, 1H, J ¼ 8.5 Hz,
aromatic H), 7.78 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.69 (t, 1H,
J ¼ 7.5 Hz, aromatic H), 7.45 (t, 1H, J ¼ 7.5 Hz, aromatic H), 7.37e7.36
(m, 3H, aromatic H), 7.24e7.17 (m, 2H, aromatic H), 6.50 (d, 1H,
J ¼ 6.5 Hz, aromatic H), 3.77 (br s, 2H, NH2) 2.43 (s, 3H, CH3). ESI-MS
(m/z): 391 [Mþ1]þ.
(500 MHz, CDCl3):
d 9.80 (s, 1H, NH, also confirmed by hydrogen/
deuterium exchange experiment), 8.17 (d, 2H, J ¼ 8.5 Hz, aromatic
H), 8.05 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.90 (d, 1H, J ¼ 8.5 Hz,
aromatic H), 7.83 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.77 (t, 1H,
J ¼ 7.5 Hz, aromatic H), 7.72e7.67 (m, 3H, aromatic H), 7.62 (t, 2H,
J ¼ 7.5 Hz, aromatic H), 7.54 (t, 1H, J ¼ 7.5 Hz, aromatic H). 13C NMR
4.1.2.17. 2-(3-Hydroxyphenylamino)-3-tosylquinoxaline
(31). Yellow solid, yield 18%, mp: 188e191 ꢀC. IR (KBr, cmꢁ1):
(125 MHz, CDCl3):
d 145.43, 142.38, 141.92, 138.27, 136.61, 134.77,
3449 (NH), 3335 (OH), 1614 (aromatic ring), 1386 (SO2). 1H NMR
133.70, 129.94, 129.48 (2), 129.18 (2), 127.35, 126.91, 126.46, 126.44,
(500 MHz, CDCl3):
d
9.60 (s, 1H, NH), 8.02 (d, 2H, J ¼ 8.5 Hz,
126.40, 126.37, 125.49, 119.92 (2). ESI-MS (m/z): 430 [Mþ1]þ.
aromatic H), 7.88 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.80 (d, 1H,
J ¼ 8.5 Hz, aromatic H), 7.71e7.68 (m, 2H, aromatic H), 7.48 (t, 1H,
J ¼ 7.5 Hz, aromatic H), 7.38 (d, 2H, J ¼ 8.5 Hz, aromatic H),
7.30e7.28 (m, 2H, aromatic H), 6.64 (d, 1H, J ¼ 7.5 Hz, aromatic
H), 5.01 (br s, 1H, OH), 2.44 (s, 3H, CH3). ESI-MS (m/z): 392
[Mþ1]þ.
4.1.2.11. 2-Phenylamino-3-tosylquinoxaline (25). Yellow solid, yield
13%, mp: 162e164 ꢀC. IR (KBr, cmꢁ1): 3449 (NH), 1636 (aromatic
ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
d 9.58 (s, 1H, NH),
8.03 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.89e7.87 (m, 3H, aromatic
H), 7.78e7.76 (m, 1H, aromatic H), 7.70 (dt, 1H, J ¼ 8.0 and 1.0 Hz,
aromatic H), 7.47 (dd, 1H, J ¼ 8.0 and 1.0 Hz, aromatic H), 7.44 (dt,
2H, J ¼ 8.5 and 2.0 Hz, aromatic H), 7.38 (d, 2H, J ¼ 8.5 Hz,
aromatic H), 7.17 (t, 1H, J ¼ 7.5 Hz, aromatic H), 2.44 (s, 3H, CH3).
ESI-MS (m/z): 376 [Mþ1]þ.
4.1.2.18. 2-(4-Fluorophenylamino)-3-tosylquinoxaline (32). Orange
solid, yield 24%, mp: 183e185 ꢀC. IR (KBr, cmꢁ1): 3447 (NH), 1620
(aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
d 9.50 (s, 1H,
NH), 8.03 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.86e7.80 (m, 3H, aromatic
H), 7.74 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.69 (dt, 1H, J ¼ 8.5 and
1.5 Hz, aromatic H), 7.46 (dt,1H, J ¼ 8.5 and 1.5 Hz, aromatic H), 7.38
(d, 2H, J ¼ 8.5 Hz, aromatic H), 7.13 (t, 2H, J ¼ 8.5 Hz, aromatic H),
2.44 (s, 3H, aromatic CH3). ESI-MS (m/z): 394 [Mþ1]þ.
4.1.2.12. 2-(4-Methoxyphenylamino)-3-tosylquinoxaline (26). Red
solid, yield 24%, mp: 164e166 ꢀC. IR (KBr, cmꢁ1): 3455 (NH), 1636
(aromatic ring),1386 (SO2). 1H NMR (500 MHz, CDCl3):
d 9.39 (s, 1H,
NH), 8.03 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.86 (d, 1H, J ¼ 8.0 Hz,
aromatic H), 7.76 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.71 (d, 1H,
J ¼ 8.0 Hz, aromatic H), 7.67 (dt, 1H, J ¼ 8.0 and 1.0 Hz, aromatic H),
7.43 (dt, 1H, J ¼ 8.0 and 1.0 Hz, aromatic H), 7.38 (d, 2H, J ¼ 8.5 Hz,
aromatic H), 6.97 (d, 2H, J ¼ 8.5 Hz, aromatic H), 3.85 (s, 3H, OCH3),
2.44 (s, 3H, CH3). ESI-MS (m/z): 406 [Mþ1]þ.
4.1.2.19. 2-(4-Chlorophenylamino)-3-tosylquinoxaline (33). Yellow
solid, yield 28%, mp: 200e201 ꢀC. IR (KBr, cmꢁ1): 3455 (NH), 1637
(aromatic ring), 1386 (SO2). 1H NMR (500 MHz, CDCl3):
d 9.59 (s, 1H,
NH), 8.02 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.87 (t, 3H, J ¼ 8.5 Hz,
aromatic H), 7.77 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.71 (t, 1H,
J ¼ 8.0 Hz, aromatic H), 7.48 (t, 1H, J ¼ 8.0 Hz, aromatic H),
7.38e7.36 (m, 4H, aromatic H), 2.44 (s, 3H, aromatic CH3). ESI-MS
(m/z): 410 [Mþ1]þ.
4.1.2.13. 2-(3,5-Dimethoxyphenylamino)-3-tosylquinoxaline
(27). Orange solid, yield 38%, mp: 168e169 ꢀC. IR (KBr, cmꢁ1): 3450
(NH), 1637 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
d
9.58 (s, 1H, NH), 8.02 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.87 (dd, 1H,
4.1.2.20. 2-(4-Trifluoromethylphenylamino)-3-tosylquinoxaline
(34). Yellow solid, yield 14%, mp: 200e202 ꢀC. IR (KBr, cmꢁ1): 3452
J ¼ 8.5 and 1.0 Hz, aromatic H), 7.77 (d, 1H, J ¼ 8.5 Hz, aromatic H),

5546
P. Wu et al. / European Journal of Medicinal Chemistry 46 (2011) 5540e5548
(NH), 1637 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
9.84 (s, 1H, NH), 8.06e8.04 (m, 4H, aromatic H), 7.93 (d, 1H,
J ¼ 8.5 Hz, aromatic H), 7.85 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.77 (t,
1H, J ¼ 7.5 Hz, aromatic H), 7.70 (d, 2H, J ¼ 8.0 Hz, aromatic H), 7.55
(t, 1H, J ¼ 7.5 Hz, aromatic H), 7.41 (d, 2H, J ¼ 8.0 Hz, aromatic H),
2.47 (s, 3H, aromatic CH3). ESI-MS (m/z): 444 [Mþ1]þ.
aromatic H), 7.87 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.77 (d, 1H,
J ¼ 8.0 Hz, aromatic H), 7.69 (t, 1H, J ¼ 7.5 Hz, aromatic H), 7.46 (t,
1H, J ¼ 7.5 Hz, aromatic H), 7.37 (s, 1H, aromatic H), 7.23e7.19 (m,
2H, aromatic H), 7.03 (d, 2H, J ¼ 9.0 Hz, aromatic H), 6.50 (d, 1H,
J ¼ 6.5 Hz, aromatic H), 3.87 (s, 3H, OCH3), 3.77 (br s, 2H, NH2). ESI-
MS (m/z): 407 [Mþ1]þ.
d
4.1.2.21. 2-Phenylamino-3-(4-methoxyphenylsulfonyl)quinoxaline
(35). Yellow solid, yield 30%, mp: 150e152 ꢀC. IR (KBr, cmꢁ1):
3449 (NH), 1596 (aromatic ring), 1386 (SO2). 1H NMR (500 MHz,
4.1.2.27. 2-(3-Hydroxyphenylamino)-3-(4-methoxyphenylsulfonyl)
quinoxaline (41). Yellow solid, yield 37%, mp: 159e161 ꢀC. IR (KBr,
cmꢁ1): 3471 (NH), 3341 (OH), 1614 (aromatic ring), 1384 (SO2). 1H
CDCl3):
d
9.58 (s, 1H, NH), 8.08 (d, 2H, J ¼ 8.5 Hz, aromatic H),
NMR (500 MHz, CDCl3):
d
9.57 (s, 1H, NH), 8.07 (d, 2H, J ¼ 9.0 Hz,
7.90 (t, 3H, J ¼ 8.5 Hz, aromatic H), 7.78 (d, 1H, J ¼ 8.5 Hz,
aromatic H), 7.70e7.67 (m, 1H, aromatic H), 7.47e7.46 (m, 1H,
aromatic H), 7.44 (t, 2H, J ¼ 8.0 Hz, aromatic H), 7.17 (t, 1H,
J ¼ 7.5 Hz, aromatic H), 7.04 (d, 2H, J ¼ 8.0 Hz, aromatic H), 3.87
aromatic H), 7.87 (d, 1H, J ¼ 8.0 Hz, aromatic H), 7.77 (d, 1H,
J ¼ 8.5 Hz, aromatic H), 7.69 (dt, 2H, J ¼ 8.0 and 1.0 Hz, aromatic H),
7.46 (dt, 1H, J ¼ 8.0 and 1.0 Hz, aromatic H), 7.28e7.25 (m, 2H,
aromatic H), 7.03 (d, 2H, J ¼ 9.0 Hz, aromatic H), 6.78 (d, 1H,
J ¼ 8.5 Hz, aromatic H), 5.35 (br s, 1H, OH), 3.86 (s, 3H, OCH3). ESI-
MS (m/z): 408 [Mþ1]þ.
(s, 3H, OCH3). 13C NMR (125 MHz, CDCl3):
d 164.65, 145.79,
142.92, 142.71, 138.86, 136.32, 133.17, 131.41 (2), 129.83, 129.75,
129.14 (2), 126.77, 126.53, 123.86, 120.56 (2), 114.73 (2), 55.89.
ESI-MS (m/z): 392 [Mþ1]þ.
4.1.2.28. 2-(4-Fluorophenylamino)-3-(4-methoxyphenylsulfonyl)qui-
noxaline (42). Yellow solid, yield 32%, mp: 148e150 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 1621 (aromatic ring), 1384 (SO2). 1H NMR
4.1.2.22. 2-(4-Methoxyphenylamino)-3-(4-methoxyphenylsulfonyl)
quinoxaline (36). Yellow solid, yield 39%, mp: 171e173 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3): d 9.50 (s, 1H, NH), 7.86e7.80 (m, 3H, aromatic H),
7.74 (d, 1H, J ¼ 8.0 Hz, aromatic H), 7.69 (t, 1H, J ¼ 7.5 Hz, aromatic
H), 7.46 (t, 1H, J ¼ 7.5 Hz, aromatic H), 7.13 (d, 3H, J ¼ 8.0 Hz,
aromatic H), 7.04 (d, 2H, J ¼ 8.5 Hz, aromatic H), 3.88 (s, 3H,
aromatic OCH3). ESI-MS (m/z): 410 [Mþ1]þ.
(500 MHz, CDCl3):
d
9.38 (s, 1H, NH), 8.08 (d, 2H, J ¼ 9.0 Hz,
aromatic H), 7.84 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.76 (d, 2H,
J ¼ 9.0 Hz, aromatic H), 7.71 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.66 (t,
1H, J ¼ 8.0 Hz, aromatic H), 7.42 (t, 1H, J ¼ 7.5 Hz, aromatic H),
7.04 (d, 2H, J ¼ 9.0 Hz, aromatic H), 6.97 (d, 2H, J ¼ 9.0 Hz,
aromatic H), 3.87 (s, 3H, OCH3), 3.85 (s, 3H, OCH3). ESI-MS (m/z):
422 [Mþ1]þ.
4.1.2.29. 2-(4-Chlorophenylamino)-3-(4-methoxyphenylsulfonyl)qui-
noxaline (43). Orange solid, yield 41%, mp: 168e170 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3):
d
9.59 (s, 1H, NH), 8.08 (d, 2H, J ¼ 8.0 Hz,
4.1.2.23. 2-(3,5-Dimethoxyphenylamino)-3-(4-methoxyphenylsul-
fonyl)quinoxaline (37). Yellow solid, yield 39%, mp: 161e163 ꢀC. IR
(KBr, cmꢁ1): 3451 (NH), 1617 (aromatic ring), 1384 (SO2). 1H NMR
aromatic H), 7.87e7.84 (m, 3H, aromatic H), 7.77 (dd, 1H, J ¼ 8.5 and
1.5 Hz, aromatic H), 7.71 (dt, 1H, J ¼ 8.0 and 1.5 Hz, aromatic H), 7.49
(dt, 1H, J ¼ 8.0 and 1.5 Hz, aromatic H), 7.38 (d, 2H, J ¼ 9.0 Hz,
aromatic H), 7.05 (d, 2H, J ¼ 9.0 Hz, aromatic H), 3.88 (s, 3H,
aromatic OCH3). ESI-MS (m/z): 426 [Mþ1]þ.
(500 MHz, CDCl3):
d
9.58 (s, 1H, NH), 8.07 (d, 2H, J ¼ 8.5 Hz,
aromatic H), 7.87 (d, 1H, J ¼ 9.0 Hz, aromatic H), 7.77 (d, 1H,
J ¼ 8.0 Hz, aromatic H), 7.69 (t, 1H, J ¼ 7.5 Hz, aromatic H), 7.47 (t,
1H, J ¼ 7.5 Hz, aromatic H), 7.16 (d, 2H, J ¼ 1.5 Hz, aromatic H), 7.04
(d, 2H, J ¼ 9.0 Hz, aromatic H), 6.28 (s, 1H, aromatic H), 3.87 (s, 3H,
OCH3), 3.86 (s, 6H, OCH3). ESI-MS (m/z): 452 [Mþ1]þ.
4.1.2.30. 2-(4-Trifluoromethylphenylamino)-3-(4-methoxyphenylsul-
fonyl)quinoxaline (44). Yellow solid, yield 20%, mp: 206e208 ꢀC. IR
(KBr, cmꢁ1): 3427 (NH), 1621 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3):
d 9.70 (s, 1H, NH), 8.03e8.01 (m, 4H, aromatic
4.1.2.24. 2-(3,4,5-Trimethoxyphenylamino)-3-(4-methoxyphenylsul-
fonyl)quinoxaline (38). Red solid, yield 31%, mp: 177e178 ꢀC. IR
(KBr, cmꢁ1): 3447 (NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR
H), 7.88 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.84 (d, 1H, J ¼ 8.5 Hz,
aromatic H), 7.78e7.74 (m, 3H, aromatic H), 7.68 (d, 2H, J ¼ 8.5 Hz,
aromatic H), 7.76 (t, 1H, J ¼ 8.0 Hz, aromatic H). ESI-MS (m/z): 460
[Mþ1]þ.
(500 MHz, CDCl3):
d
9.52 (s, 1H, NH), 8.09 (d, 2H, J ¼ 9.0 Hz,
aromatic H), 7.86 (d, 1H, J ¼ 8.0 Hz, aromatic H), 7.70e7.66 (m, 2H,
aromatic H), 7.47 (dt, 1H, J ¼ 8.0 and 2.0 Hz, aromatic H), 7.21 (s,
2H, aromatic H), 7.05 (d, 2H, J ¼ 9.0 Hz, aromatic H), 3.94 (s, 6H,
OCH3), 3.88 (s, 3H, OCH3), 3.87 (s, 3H, OCH3). ESI-MS (m/z): 482
[Mþ1]þ.
4.1.2.31. 2-Phenylamino-3-(4-bromophenylsulfonyl)quinoxaline
(45). Yellow solid, yield 17%, mp: 170e173 ꢀC. IR (KBr, cmꢁ1): 3450
(NH), 1637 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz, CDCl3):
d
9.46 (s, 1H, NH), 8.02 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.88 (d, 2H,
J ¼ 8.0 Hz, aromatic H), 7.85 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.79 (d,
1H, J ¼ 8.5 Hz, aromatic H), 7.74 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.71
(d, 1H, J ¼ 8.0 Hz, aromatic H), 7.49 (t, 1H, J ¼ 6.0 Hz, aromatic H),
7.45e7.41 (m, 2H, aromatic H), 7.18 (t, 1H, J ¼ 8.0 Hz, aromatic H).
ESI-MS (m/z): 442 [Mþ1]þ.
4.1.2.25. 2-(4-Aminophenylamino)-3-(4-methoxyphenylsulfonyl)qui-
noxaline (39). Red solid, yield 31%, mp: 179e182 ꢀC. IR (KBr, cmꢁ1):
3452 (NH), 3352 (NH2), 1634 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3):
d
9.29 (s, 1H, NH), 8.07 (d, 2H, J ¼ 7.5 Hz,
aromatic H), 7.84 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.69 (d, 1H,
J ¼ 7.5 Hz, aromatic H), 7.63e7.60 (m, 3H, aromatic H), 7.41e7.40 (m,
1H, aromatic H), 7.03 (d, 2H, J ¼ 7.5 Hz, aromatic H), 6.76 (d, 2H,
J ¼ 7.5 Hz, aromatic H), 3.87 (s, 3H, OCH3), 3.66 (br s, 2H, NH2). ESI-
MS (m/z): 407 [Mþ1]þ.
4.1.2.32. 2-(4-Methoxyphenylamino)-3-(4-bromophenylsulfonyl)qui-
noxaline (46). Red solid, yield 43%, mp: 132e134 ꢀC. IR (KBr, cmꢁ1):
3449 (NH), 1619 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz,
CDCl3):
d
9.26 (s, 1H, NH), 8.10 (d, 1H, J ¼ 8.0 Hz, aromatic H), 8.06
(d, 1H, J ¼ 8.0 Hz, aromatic H), 8.01 (d, 1H, J ¼ 8.0 Hz, aromatic H),
7.96e7.93 (m, 2H, aromatic H), 7.87 (t, 1H, J ¼ 7.5 Hz, aromatic H),
7.78e7.70 (m, 3H, aromatic H), 7.44 (t, 1H, J ¼ 7.5 Hz, aromatic H),
6.97 (d, 2H, J ¼ 8.0 Hz, aromatic H), 3.85 (s, 3H, OCH3). ESI-MS (m/z):
472 [Mþ1]þ.
4.1.2.26. 2-(3-Aminophenylamino)-3-(4-methoxyphenylsulfonyl)qui-
noxaline (40). Red solid, yield 22%, mp: 164e166 ꢀC. IR (KBr, cmꢁ1):
3436 (NH), 3338 (NH2), 1618 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3):
d
9.51 (s, 1H, NH), 8.07 (d, 2H, J ¼ 8.5 Hz,

P. Wu et al. / European Journal of Medicinal Chemistry 46 (2011) 5540e5548
5547
4.1.2.33. 2-(3,5-Dimethoxyphenylamino)-3-(4-bromophenylsulfonyl)
quinoxaline (47). Orange solid, yield 51%, mp: 187e188 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 1624 (aromatic ring), 1384 (SO2). 1H NMR
J ¼ 8.5 Hz, aromatic H), 7.75e7.71 (m, 3H, aromatic H), 7.50 (dt, 1H,
J ¼ 8.0 and 1.5 Hz, aromatic H), 7.38 (d, 2H, J ¼ 8.5 Hz, aromatic H).
ESI-MS (m/z): 476 [Mþ1]þ.
(500 MHz, CDCl3):
d
9.46 (s, 1H, NH), 8.01 (d, 2H, J ¼ 9.0 Hz,
aromatic H), 7.84 (d, 1H, J ¼ 8.0 Hz, aromatic H), 7.78 (d, 1H,
J ¼ 8.5 Hz, aromatic H), 7.74 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.70 (dd,
1H, J ¼ 8.5 and 1.5 Hz, aromatic H), 7.49 (dt, 1H, J ¼ 8.0 and 1.0 Hz,
aromatic H), 7.14 (d, 2H, J ¼ 2.0 Hz, aromatic H), 6.30 (t, 1H,
J ¼ 2.0 Hz, aromatic H), 3.86 (s, 6H, OCH3). ESI-MS (m/z): 502
[Mþ1]þ.
4.1.2.40. 2-(4-Trifluoromethylphenylamino)-3-(4-bromophenylsul-
fonyl)quinoxaline (54). Yellow solid, yield 16%, mp: 219e221 ꢀC. IR
(KBr, cmꢁ1): 3448 (NH), 1628 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3):
d 9.69 (s, 1H, NH), 8.03e8.01 (m, 4H, aromatic
H), 7.88 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.84 (d, 1H, J ¼ 8.5 Hz,
aromatic H), 7.78e7.74 (m, 3H, aromatic H), 7.69 (d, 2H, J ¼ 8.5 Hz,
aromatic H), 7.76 (t, 1H, J ¼ 7.5 Hz, aromatic H). ESI-MS (m/z): 510
[Mþ1]þ.
4.1.2.34. 2-(3,4,5-Trimethoxyphenylamino)-3-(4-bromophenylsul-
fonyl)quinoxaline (48). Orange solid, yield 29%, mp: 188e189 ꢀC. IR
(KBr, cmꢁ1): 3450 (NH), 1612 (aromatic ring), 1384 (SO2). 1H NMR
4.1.2.41. 2-(4-Methoxyphenylamino)-3-(4-fluorophenylsulfonyl)qui-
noxaline (55). Red solid, yield 60%, mp: 159e161 ꢀC. IR (KBr, cmꢁ1):
3446 (NH), 1618 (aromatic ring), 1384 (SO2). 1H NMR (500 MHz,
(500 MHz, CDCl3):
d
9.39 (s, 1H, NH), 8.02 (d, 2H, J ¼ 9.0 Hz,
aromatic H), 7.83 (d, 1H, J ¼ 9.0 Hz, aromatic H), 7.77e7.73 (m, 3H,
aromatic H), 7.71e7.70 (m, 2H, aromatic H), 7.19 (s, 2H, aromatic H),
3.94 (s, 6H, OCH3), 3.87 (s, 3H, OCH3). ESI-MS (m/z): 532 [Mþ1]þ.
CDCl3): d 9.28 (s,1H, NH), 8.19e8.16 (m, 2H, aromatic H), 7.81 (d,1H,
J ¼ 8.5 Hz, aromatic H), 7.75e7.77 (m, 3H, aromatic H), 7.68 (t, 1H,
J ¼ 7.5 Hz, aromatic H), 7.44 (t,1H, J ¼ 7.5 Hz, aromatic H), 7.30e7.26
(m, 2H, aromatic H), 6.98 (d, 2H, J ¼ 9.0 Hz, aromatic H), 3.85 (s, 3H,
OCH3). ESI-MS (m/z): 410 [Mþ1]þ.
4.1.2.35. 2-(4-Aminophenylamino)-3-(4-bromophenylsulfonyl)qui-
noxaline (49). Red solid, yield 54%, mp: 177e180 ꢀC. IR (KBr, cmꢁ1):
3445 (NH), 3370 (NH2), 1631 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3):
d
9.22 (s, 1H, NH), 8.05 (d, 2H, J ¼ 8.5 Hz,
4.1.2.42. 2-(3,5-Dimethoxyphenylamino)-3-(4-fluorophenylsulfonyl)
quinoxaline (56). Yellow solid, yield 37%, mp: 158e160 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 1624 (aromatic ring), 1384 (SO2). 1H NMR
aromatic H), 7.85 (d, 1H, J ¼ 8.0 Hz, aromatic H), 7.78e7.77 (m, 4H,
aromatic H), 7.64 (d, 2H, J ¼ 8.5 Hz, aromatic H), 7.46e7.43 (m, 1H,
aromatic H), 6.80 (d, 2H, J ¼ 8.5 Hz, aromatic H), 3.72 (br s, 2H, NH2).
ESI-MS (m/z): 457 [Mþ1]þ.
(500 MHz, CDCl3): d 9.48 (s, 1H, NH), 8.18e8.16 (m, 2H, aromatic H),
7.83 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.78 (d, 1H, J ¼ 8.5 Hz, aromatic
H), 7.71 (t, 1H, J ¼ 8.0 Hz, aromatic H), 7.48 (t, 1H, J ¼ 8.0 Hz,
aromatic H), 7.28e7.25 (m, 2H, aromatic H), 7.14 (d, 2H, J ¼ 2.5 Hz,
aromatic H), 6.30 (t, 1H, J ¼ 2.5 Hz, aromatic H), 3.86 (s, 6H, OCH3).
ESI-MS (m/z): 440 [Mþ1]þ.
4.1.2.36. 2-(3-Aminophenylamino)-3-(4-bromophenylsulfonyl)qui-
noxaline (50). Red solid, yield 16%, mp: 178e181 ꢀC. IR (KBr, cmꢁ1):
3427 (NH), 3355 (NH2), 1625 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3):
d
9.38 (s, 1H, NH), 8.00 (d, 2H, J ¼ 8.5 Hz,
aromatic H), 7.84 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.78 (d, 1H,
J ¼ 8.0 Hz, aromatic H), 7.30 (d, 2H, J ¼ 8.5 Hz, aromatic H),
7.47e7.43 (m, 2H, aromatic H), 7.35 (s, 1H, aromatic H), 7.20e7.19
(m, 2H, aromatic H), 6.50 (d, 1H, J ¼ 6.5 Hz, aromatic H), 3.80 (br s,
2H, NH2). ESI-MS (m/z): 457 [Mþ1]þ.
4.1.2.43. 2-(3,4,5-Trimethoxyphenylamino)-3-(4-fluorophenylsul-
fonyl)quinoxaline (57). Yellow solid, yield 57%, mp: 234e235 ꢀC. IR
(KBr, cmꢁ1): 3448 (NH), 1636 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3): d 9.42 (s, 1H, NH), 8.20e8.17 (m, 2H, aromatic H),
7.83 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.71e7.70 (m, 2H, aromatic H),
7.50e7.45 (m, 1H, aromatic H), 7.30 (t, 2H, J ¼ 8.5 Hz, aromatic H),
7.20 (s, 2H, aromatic H), 3.94 (s, 6H, OCH3), 3.87 (s, 3H, OCH3). ESI-
MS (m/z): 470 [Mþ1]þ.
4.1.2.37. 2-(3-Hydroxyphenylamino)-3-(4-bromophenylsulfonyl)qui-
noxaline (51). Orange solid, yield 28%, mp: 208e209 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 3370 (OH), 1611 (aromatic ring), 1384 (SO2). 1H
NMR (500 MHz, CDCl3):
d
9.47 (s, 1H, NH), 8.00 (d, 2H, J ¼ 8.5 Hz,
4.1.2.44. 2-(4-Aminophenylamino)-3-(4-fluorophenylsulfonyl)qui-
noxaline (58). Red solid, yield 69%, mp: 168e169 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 1627 (aromatic ring), 1384 (SO2). 1H NMR
aromatic H), 7.84e7.79 (m, 2H, aromatic H), 7.74e7.71 (m, 3H,
aromatic H), 7.66 (s, 1H, aromatic H), 7.49 (t, 1H, J ¼ 7.5 Hz, aromatic
H), 7. 28e7.26 (m, 2H, aromatic H), 6.64 (d, 1H, J ¼ 6.5 Hz, aromatic
H), 4.88 (s, 1H, OH). ESI-MS (m/z): 457 [Mþ1]þ.
(500 MHz, CDCl3):
d 9.19 (s, 1H, NH, also confirmed by hydrogen/
deuterium exchange experiment), 8.18e8.15 (m, 2H, aromatic H),
7.79 (d, 1H, J ¼ 8.5 Hz, aromatic H), 7.70 (d, 1H, J ¼ 8.0 Hz, aromatic
H), 7.69 (t, 1H, J ¼ 8.0 Hz, aromatic H), 7.60 (d, 2H, J ¼ 8.5 Hz,
aromatic H), 7.41 (t, 1H, J ¼ 8.0 Hz, aromatic H), 7.27e7.24 (m, 2H,
aromatic H), 6.76 (d, 2H, J ¼ 8.5 Hz, aromatic H), 3.67 (br s, 2H,
NH2, also confirmed by hydrogen/deuterium exchange experi-
4.1.2.38. 2-(4-Fluorophenylamino)-3-(4-bromophenylsulfonyl)qui-
noxaline (52). Yellow solid, yield 27%, mp: 206e208 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 1622 (aromatic ring), 1385 (SO2). 1H NMR
(500 MHz, CDCl3):
deuterium exchange experiment), 8.01 (d, 2H,
d
9.38 (s, 1H, NH, also confirmed by hydrogen/
8.5 Hz,
J
¼
ment). 13C NMR (125 MHz, CDCl3):
d 167.51, 165.45, 146.28, 143.29,
aromatic H), 7.83e7.80 (m, 3H, aromatic H), 7.75e7.73 (m, 3H,
aromatic H), 7.72 (t, 1H, J ¼ 7.0 Hz, aromatic H), 7.748 (t, 1H,
J ¼ 8.5 Hz, aromatic H), 7.14 (t, 2H, J ¼ 8.5 Hz, aromatic H). 13C
143.21, 142.06, 136.03, 134.53, 134.50, 133.31, 132.13, 132.05,
129.88, 129.74, 126.68, 126.13, 122.87, 116.86, 116.68, 115.63. ESI-
MS (m/z): 395 [Mþ1]þ.
NMR (125 MHz, CDCl3):
d 161.30, 158.37, 145.85, 142.76, 141.80,
137.30, 136.28, 134.60, 134.58, 133.65, 132.75, 130.66, 130.33,
129.82, 126.82, 126.77, 122.53, 122.46, 115.90, 115.72. ESI-MS (m/
z): 460 [Mþ1]þ.
4.1.2.45. 2-(3-Aminophenylamino)-3-(4-fluorophenylsulfonyl)qui-
noxaline (59). Yellow solid, yield 41%, mp: 166e168 ꢀC. IR (KBr,
cmꢁ1): 3451 (NH), 1625 (aromatic ring), 1384 (SO2). 1H NMR
(500 MHz, CDCl3): d 9.40 (s, 1H, NH), 8.18e8.15 (m, 2H, aromatic H),
4.1.2.39. 2-(4-Chlorophenylamino)-3-(4-bromophenylsulfonyl)qui-
noxaline (53). Yellow solid, yield 26%, mp: 202e203 ꢀC. IR (KBr,
cmꢁ1): 3448 (NH), 1616 (aromatic ring), 1384 (SO2). 1H NMR
7.83 (d, 1H, J ¼ 8.0 Hz, aromatic H), 7.78 (d, 1H, J ¼ 8.5 Hz, aromatic
H), 7.70 (t, 1H, J ¼ 7.5 Hz, aromatic H), 7.42 (t, 1H, J ¼ 7.5 Hz,
aromatic H), 7.35 (s, 1H, aromatic H), 7.27e7.24 (m, 2H, aromatic H),
7.21e7.17 (m, 2H, aromatic H), 6.50 (d, 1H, J ¼ 7.5 Hz, aromatic H),
3.76 (br s, 2H, NH2). ESI-MS (m/z): 395 [Mþ1]þ.
(500 MHz, CDCl3):
d
9.46 (s, 1H, NH), 8.01 (d, 2H, J ¼ 9.0 Hz,
aromatic H), 7.84 (d, 3H, J ¼ 9.0 Hz, aromatic H), 7.78 (d, 1H,

5548
P. Wu et al. / European Journal of Medicinal Chemistry 46 (2011) 5540e5548
4.2. Pharmacology
preparation, the hydrogen atoms were added, and the CHARMm
force field was employed. The whole PI3K enzyme was defined as
g
Five human cancer cell lines (PC3, A549, HCT116, HL60, and KB)
were purchased from cell bank of China Science Academy,
Shanghai, China. The above cells were cultured in RPMI-1640
(Invitrogen Corp., Carlsbad, CA) medium with heat-inactivated
10% fetal bovine serum, penicillin (100 units/mL) and strepto-
a receptor and the site sphere was selected based on the ligand
binding location of LXX, then the LXX molecule was removed and
compound 17 or LY294002 was placed during the molecular
docking procedure. Types of interactions of the docked enzyme
with ligand were analyzed after end of molecular docking. Ten
docking poses were saved for each ligand and the final docked
conformation was scored and selected based on calculated
C-DOCKER-energy [25].
mycin (100
mg/mL) and incubated in atmosphere with 20% O2, 5%
CO2 at 37 ꢀC.
4.2.1. Cytotoxicity assay
The cytotoxic activity in vitro was measured using the MTT assay.
All the compounds were dissolved in DMSO at the concentration of
10.0 mg/mL and were then diluted to appropriate concentrations.
Cells were plated in 96-well plates for 24 h and subsequently
treated with different concentrations of all tested compounds for
72 h. Viable cells were determined using 3-(4,5-dimethylthiazol-2-
yl)-2,5-diphenyltetrazolium bromide assay kit (MTT, Sigma)
according to the manufacturer’s instructions. The concentration of
drug causing 50% inhibition in absorbance compared with control
cells (IC50) was calculated using the software of doseeeffect anal-
ysis with microcomputers.
Acknowledgments
We thank Ms Jianyang Pan for doing the NMR tests.
References
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a enzyme assay
The inhibition of PI3K
a
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volumes were 10 l. For evaluation of PI3K inhibitors, 50 ng of
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1
m
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The PI3K
ID: 3L54) was chosen as the template to compare the docking mode
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g
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