Structure–activity relationship studies on quinoxalin-2(1H-one derivatives containing thiazol-2-amine against hepatitis C virus leading to the discovery of BH6870

Article abstract of DOI:10.1007/s11030-015-9610-6

Abstract: Chronic hepatitis C virus infection represents a serious global public health problem, typically resulting in fibrosis, cirrhosis, and ultimately hepatocellular carcinoma. Based on our previous discovery of lead compound 2 (Liu et al. J Med Chem 54:5747–5768, 2011), 35 new quinoxalinone derivatives were explored in this study. Outline of the structure–activity relationships (SARs) revealed that compound BH6870 (36) showed high anti-HCV potency (EC₅₀ = 0.21μM) and a good cell safety index (SI =47.19). SARs analysis indicated that quinoxalin-2(1H-one containing a 4-aryl-substituted thiazol-2-amine moiety was optimal for antiviral activity. Introducing a hydrogen-bond acceptor (such as ester or amide group) at the C-3 position of quinoxalin-2(1H-one was beneficial for the antiviral potency, and especially, N,N-disubstituted amide was far superior to N-monosubstituted amide. Incorporation of more than one halogen (fluorine or chlorine atom) or a strong electron-withdrawing group on the benzene ring of the thiazole-phenyl moiety might reduce electron atmosphere density further and resulted in a dramatical loss of activity. The NH-group of the lactam moiety was clearly required for anti-HCV activity. Graphical Abstract: Design and synthesis of quinoxalin-2(1H-one derivatives as new non-nucleoside small-molecule HCV inhibitors. BH6870 (36), showing higher antiviral potency and a good cell safety index, was identified. [Figure not available: see fulltext.]

Full text of DOI:10.1007/s11030-015-9610-6

Mol Divers
DOI 10.1007/s11030-015-9610-6
FULL-LENGTH PAPER
Structure–activity relationship studies on quinoxalin-2(1H)-one
derivatives containing thiazol-2-amine against hepatitis C virus
leading to the discovery of BH6870
Qi-Fei Zhong1 · Rui Liu1 · Gang Liu1,2
Received: 11 April 2015 / Accepted: 26 June 2015
© Springer International Publishing Switzerland 2015
Abstract Chronic hepatitis C virus infection represents
a serious global public health problem, typically resulting
in fibrosis, cirrhosis, and ultimately hepatocellular carci-
noma. Based on our previous discovery of lead compound
2 (Liu et al. J Med Chem 54:5747–5768, 2011), 35 new
quinoxalinone derivatives were explored in this study. Out-
line of the structure–activity relationships (SARs) revealed
that compound BH6870 (36) showed high anti-HCV potency
(EC50 = 0.21 μM) and a good cell safety index (SI =
47.19). SARs analysis indicated that quinoxalin-2(1H)-one
containing a 4-aryl-substituted thiazol-2-amine moiety was
optimal for antiviral activity. Introducing a hydrogen-bond
acceptor (such as ester or amide group) at the C-3 posi-
tion of quinoxalin-2(1H)-one was beneficial for the antiviral
potency, and especially, N,N-disubstituted amide was far
superior to N-monosubstituted amide. Incorporation of more
than one halogen (fluorine or chlorine atom) or a strong
electron-withdrawing group on the benzene ring of the
thiazole-phenyl moiety might reduce electron atmosphere
density further and resulted in a dramatical loss of activity.
The NH-group of the lactam moiety was clearly required for
anti-HCV activity.
Graphical Abstract Design and synthesis of quinoxalin-
2(1H)-one derivatives as new non-nucleoside small-molecu-
le HCV inhibitors. BH6870 (36), showing higher antiviral
potency and a good cell safety index, was identified.
Keywords Antiviral activity · Hepatitis C virus ·
Quinoxalinone · Structure–activity relationships
Introduction
In1989, thevirusresponsibleformosttransfusion-associated
non-A and non-B hepatitis was identified and cloned, and
named hepatitis C virus (HCV) [1]. HCV belongs to the Fla-
viviridae family and is described as having positive-sense,
single-stranded RNA genomes [2]. HCV infection typically
progresses to a chronic state, may resulting in fibrosis, cir-
rhosis, and hepatocellular carcinoma, and has emerged as a
leading cause for liver transplantation [3]. There are at least
six distinct HCV genotypes (genotypes 1–6), of which geno-
type 1 accounts for the majority of infections in the U.S.,
Europe, and Asia and has been particularly difficult to treat
[4,5]. Currently, chronic HCV infection represents a seri-
ous global public health problem. It has been estimated that
Electronic supplementary material The online version of this
article (doi:10.1007/s11030-015-9610-6) contains supplementary
material, which is available to authorized users.
Gang Liu
B
gangliu27@gmail.com, gangliu27@tsinghua.edu.cn
1
Institute of Materia Medica, Chinese Academy of Medical
Sciences and Peking Union Medical College, 2 Nanwei Rd.,
Xicheng Dist., Beijing 100050, People’s Republic of China
2
Tsinghua-Peking Center for Life Sciences and Department
of Pharmacology and Pharmaceutical Sciences, School of
Medicine, Tsinghua University, Haidian Dist.,
Beijing 100084, People’s Republic of China
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Fig. 1 Anti-HCV agents in late-stage clinical development or launched
150 million people worldwide are chronically infected with
HCV and that approximately 3–4 million people are newly
infected each year, with more than 350,000 deaths annually
due to hepatitis C-related liver diseases [6].
inhibitor boceprevir or telaprevir with PEG-IFN and rib-
avirin, increasing the rate of sustained virologic response
(SVR) to nearly 70% [23]. Two years later, the second-
generation NS3/4A protease inhibitor simeprevir launched
in 2013 for use in combination with PEG-IFN and ribavirin
for the treatment of genotype 1 chronic HCV patients (Fig. 1)
[24–28]. The other small-molecule inhibitors of NS3/4A pro-
tease will be available in clinics in the near future (Fig. 1)
[29]. For example, faldaprevir [30,31], vaniprevir [32–34],
and asunaprevir [35,36] are currently in phase III trials. In
addition to the NS3/4A protease, the RNA-dependent RNA
polymerase NS5B is another attractive target for antiviral
therapy. Several classes of inhibitors for NS5B polymerase
are in late-stage clinical trials or have been recently approved.
The inhibitors of NS5B polymerase include nucleoside
(such as sofosbuvir [37,38] and R7128 [39,40]) and non-
nucleoside polymerase inhibitors (e.g., deleobuvir [41,42],
tegobuvir [43–45]) (Fig. 1). However, the high mutation rate
of HCV and the rapid emergence of drug resistance have
prompted continuous efforts to discover and develop drugs
with high efficacy and novel mechanisms of action [46–
48].
HCV has a small genome encoding six nonstructural
proteins, including NS2, NS3, NS4A, NS4B, NS5A, and
NS5B. It is believed that the nonstructural (NS) proteins
provide the catalytic machinery for viral replication [7].
Until recently, the standard of care (SOC) for HCV infec-
tion consists in the combination of nonspecific immune
modulatory agent pegylated interferon (PEG-IFN) plus the
antiviral agent ribavirin, which have limited efficacy partic-
ularly against major genotype 1 [8] and severe side effects.
To address these deficiencies, many molecular targets have
been pursued in an effort to identify direct-acting antivi-
ral agents (DAAs) as anti-HCV drugs [9–13]. In 2011, the
massive efforts devoted to developing new HCV DAAs
were rewarded by the approval of the first-generation of
HCV NS3/4A protease inhibitors, boceprevir [14–16] and
telaprevir (Fig. 1) [17–22]. Consequently, the new SOC for
patients infected with genotype 1a or 1b has been put into
practice by using a combination of the NS3/4A protease
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Fig. 2 Key lead series discovered as small-molecule HCV inhibitors
Quinoxalin-2(1H)-onederivativeshavebeenfirstreported
by our group [49] to be potent inhibitors against HCV. Con-
sidering the potential cytotoxicity of the analogues with a
thiourea group such as compound 1, cyclization strategy
was carried out to identify 2 as a potent inhibitor of the
HCV with lower cell toxicity properties in vitro (Fig. 2).
We demonstrated that the thiazole-phenyl moiety was opti-
mal for anti-HCV activity, and steric conformation in the
position C-6 was necessary for inhibition of the HCV repli-
con system. Moreover, there may be a steric limitation at
the C-3 position of quinoxalin-2(1H)-one. Consequently,
further work aimed at optimization of moieties at the C-
3 position and exploration of optimal substituents on the
benzene ring of the thiazole-phenyl moiety was undertaken.
Herein, we report our findings that led to the discovery of
BH6870.
treatmentwithpotassiumcarbonate. Finally, fortheconstruc-
tion of the thiazole ring, thiourea substrates were utilized
to react with suitably substituted 2-bromoacetophenones to
afford target compounds 8–19.
Tricyclic quinoxalinone compounds were effectively pre-
pared in a 6-step procedure from DFDNB (Scheme 2).
Reaction of monosubstituted intermediate 3a with dimethyl
1H-imidazole-4,5-dicarboxylate in acetone and with potas-
sium carbonate under reflux for 6 h gave smoothly the
key 4,6-dinitro intermediate 20. Reductive cyclization of
20 to the corresponding imidazo[1,5-a]quinoxalin-4-one 21
was initially attempted according to the hydrogenation pro-
cedures used above. Unfortunately, it was found that the
products were a complex mixture of several components,
of which only a small amount of the desired compound
21 was observed by HPLC-MS, but the major product was
its hydroxylamine intermediate. Finally, it was found that
the combination of sodium dithionite [50] in concentrated
hydrochloric acid was the effective condition of choice for
conducting the reductive cyclization of 20 to 21 and its
product of ester hydrolysis, which was next converted con-
veniently to the desired product 21 after the reaction mixture
wasfilteredandconcentratedinvacuofollowedbyanesterifi-
cation reaction with methanol in the presence of concentrated
sulfuric acid. Finally, the target compounds 24–27 could eas-
ily be obtained by the introduction of a thiourea moiety into
the free amino group of intermediate 21 and then perform-
ing a cyclization in 3 steps following reaction steps d–f in
Scheme 1.
Results and discussion
Chemistry
Preparation of the ester-substituted quinoxalinone analogues
is depicted in Scheme 1. The core structure 5 was constructed
according to our previous report [49]. In the first step, sec-
ondary amines were used as nucleophiles to replace quanti-
tatively one fluorine atom of 1,5-difluoro-2,4-dinitrobenzene
(DFDNB) in the presence of N,N-diisopropylethylamine
(DIPEA) or potassium carbonate (K2CO3). Subsequently,
the remaining fluorine was substituted by primary amines
to give 4a–f. Then 10% palladium on activated carbon was
utilizedtoconvertthedinitrosubstratestodiaminointermedi-
atesfollowedbyaself-cyclizationtoobtainkeyintermediates
5a–f. Accordingly, subsequent nucleophilic addition with
benzoyl isothiocyanate in acetone, followed by deprotection
of the benzoyl group provided thiourea compounds 7a–f after
Amide-substituted quinoxalinones were obtained accord-
ing to the synthetic route shown in Scheme 3. Treatment of 5
with lithium hydroxide (LiOH) easily gave the correspond-
ing carboxylic acid intermediates. And then, the intermediate
was incorporated to commercially available methylamine or
dimethylamine solution in tetrahydrofuran using EDCI and
HOBtascondensationagentstodelivertheamide-substituted
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Scheme 1 Synthesis of ester-substituted quinoxalinone analogues 8–
19. Reagents and conditions: a R1H, DIPEA, THF, rt or R1H, K2CO3,
THF, reflux; b NH2CHCO2R2(CH2CH2)nCO2R2· HCl, DIPEA, THF,
reflux; c 10% Pd/C, NH4COOH, THF/EtOH (1:1, v/v), rt; d PhCONCS,
acetone, reflux; e K2CO3, EtOH/H2O (4:1, v/v), 75 ◦C; f R3COCH2Br,
EtOH, reflux
Scheme 2 Synthesis of tricyclic quinoxalinone analogues 24–27.
Reagents and conditions: a N-methylcyclohexylamine, DIPEA, THF,
rt; b dimethyl 1H-imidazole-4,5-dicarboxylate, K2CO3, acetone,
reflux; c Na2S2O4, concd. HCl, MeOH/H2O (1:1, v/v), 70 ◦C; then
concd. H2SO4, MeOH, reflux; d PhCONCS, acetone, reflux; e NaOMe,
MeOH, 50 ◦C; f R3COCH2Br, MeOH, reflux
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Scheme 3 Synthesis of amide-substituted quinoxalinone analogues 31–48. Reagents and conditions: a (i) LiOH·H2O, EtOH/H2O (5:1, v/v), 50 ◦C;
(ii) 2M MeNHR4 in THF, EDCI, HOBt, THF, 60 ◦C; b PhCONCS, acetone, reflux; c K2CO3, EtOH/H2O (4:1, v/v), 75 ◦C; d R3COCH2Br, EtOH,
reflux
intermediates 28a–h. Subsequently, the target compounds
31–48 could be smoothly provided using the aforementioned
introduction of the thiourea moiety and cyclization condi-
tions.
Synthesis of 1-N-substituted quinoxalinone 53 was acco-
mplished as outlined in Scheme 4. Treatment of lactam 5d
with methyl iodide using potassium carbonate as a base
resulted in the 1-N-substituted quinoxalinone intermedi-
ate 49 followed by an ester hydrolysis and coupling with
dimethylamine to yield amide 50. Accordingly, target com-
pound 53 was readily obtained following the same protocol
shown in Scheme 1.
[49,51]. The results are currently summarized in Tables 1,
α
2, 3, 4. rIFN -2b (recombinant human interferon alfa-2b) is
α
a fused form of IFN -2b with human serum albumin used
as a positive control for inhibition of HCV with an approxi-
mate EC50 of 0.08 IU/mL [49]. Briefly, the concentration of
compound to inhibit HCV RNA replication activity by 50%
(EC50), the concentration of compound to decrease cell via-
bility by 50% (CC50), and the selective index (SI) calculated
as the CC50/EC50 ratio are presented.
Previous studies on structure–activity relationships (SA-
Rs) indicated that there may be a steric limitation at the C-3
position of quinoxalin-2(1H)-one [49]. Initially, the hydro-
gen atom at the C-3 position was replaced by an ester group.
These modifications were intended to introduce a hydrogen-
bond acceptor and change the distance between the ester
group and quinoxalinone skeleton, thus making the resulting
compounds show an improved anti-HCV activity. Results of
these modifications are summarized in Table 1.
Anti-HCV activity in vitro and SAR studies
The anti-HCV activity and cytotoxicity of synthesized
quinoxalinone derivatives were evaluated in the HCV RNA
replicon system in Huh7-ET cells, as previously described
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Scheme 4 Synthesis of 1-N-substituted quinoxalinone 53. Reagents
and conditions: a CH3I, K2CO3, acetone, 50 ◦C; b (i) LiOH · H2O,
EtOH/H2O (5:1, v/v), 50 ◦C; (ii) 2M dimethylamine in THF, EDCI,
HOBt, THF, 60 ◦C; c PhCONCS, acetone, reflux; d K2CO3, EtOH/H2O
(4:1, v/v), 75 ◦C; e 4-FC6H4COCH2Br, MeOH, reflux
Thus, replacement of hydrogen atom at the C-3 position
Previous SARs from our group indicated that the mimic
of 3,4-double bond of quinoxalinone by a five-membered
ring provided a slight improvement in binding potency [49].
Thus, in order to balance the lipid/water partition coeffi-
cient, we selected the hydrophilic imidazole ring to mimic
the 3,4-double bond of quinoxalinone and incorporated an
ester group on the five-membered ring to further study
the effect of steric limitation. Cellular data of compounds
with double bond mimics are tabulated in Table 2. Prepa-
ration of inhibitor 25, bearing a fluorine atom in the para
of 2 with propionate side chain resulted in 8 with EC50
=
7.13 μM, fourfold less active than 2 (EC50 = 1.67 μM).
Incorporation of a fluorine atom on the phenyl ring of 8
resulted in compound 9 exerting no antiviral activity against
HCV. Replacement of N-methylcyclohexylamine at the C-
6 position of 8 with N-methylaniline side chain resulted in
10 and 11. Interestingly, fluorine-substituted compound 11
exhibited potent activity against HCV with EC50 = 1.30 μM
similar to that of inhibitor 2. However, introduction of a
morpholine group (12 and 13) in the position C-6 was unfa-
vorable for the antiviral potency. This could have been due
to the fact that a compound containing hydrophobic groups
may effectively improve its binding to the target protein.
When the substituent at the C-6 position was kept con-
stant as N-methylcyclohexylamine, decreasing the distance
between the ester group and quinoxalinone skeleton resulted
in 14 and 15. Similarly, compound 14 bearing a fluorine
atom had an excellent cellular potency against HCV with
position, resulted in a slightly lower potency (EC50
=
4.14 μM) than that of 14 (EC50 = 1.14 μM). Attempts
to replace the fluorine atom with a chlorine atom (26,
EC50 = 4.94μM) or directly remove the halogen (24,
EC50 = 3.94 μM) failed to provide improvement in bind-
π
π
interactions (27,
ing potency. Moreover, enhancing
−
EC50 = 6.14 μM) did not show appreciable binding affinity
with the target either. It can be concluded from the data in
Table 2 that increase of steric hindrance and hydrophilicity
is unfavorable for the anti-HCV activity, but the 3,4-double
bond can be to some extent mimicked by a five-membered
ring.
π
π
interactions
EC50 = 1.14 μM. However, enhancing
−
(15) significantly decreased the antiviral activity. Further-
more, neither the introduction of N-methylaniline side chain
at the C-6 position (16 and 17) nor morpholine group (18 and
19) provided an obvious potency against HCV or improve-
ment in the selectivity index. Consequently, although no
single compound displayed significantly increased potency
against the HCV replicon compared to 2, it was encour-
aging to see this kind of activity with ester-substituted
compounds.
Bioisosteres modulate biological activity by virtue of
subtle differences in their physicochemical properties. A
classical divalent bioisosteric replacement involving two sin-
gle bonds is –O– with –NH–. This replacement has been
widely used in the drug discovery process [52]. On the
basis of the observed SARs, it was encouraging to know
that replacement of the hydrogen atom at the C-3 posi-
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Table 1 Inhibitory effects of
ester-substituted
quinoxalin-2(1H)-one
derivatives on HCV replication
in Huh7
Anti-HCV activity Cytotoxicity
Compound
R1
R2
R3
n
1
SIa
EC50 (μM)
CC50 (μM)
Me
7.13
8.78
1.23
8
Me
Me
Me
Me
1
1
1
1
>10
>10
1.30
>10
>10
>10
2.98
>10
1.00
1.00
2.29
1.00
9
10
11
12
Me
Et
1
0
0
0
0
>10
1.14
>10
>10
>10
9.59
>10
>10
>10
7.59
>10
>10
1.00
>8.77
1.00
13
14
15
16
17
18
Et
Et
<0.76
1.00
Et
Et
Et
0
0
>1.04
19
9.85
9.60
0.97
0.06 IU/mL
>2 IU/mL
>33.3
rIFNα-2b
a
The selectivity index (SI) is calculated as CC50/EC50
tion with an ester group preserved antiviral activity against
HCV. Consequently, we decided to further explore optimal
substituents for the hydrogen atom at the C-3 position by
introducing an amide group as ester bioisostere. The effect on
the anti-HCV activity of the bioisostere derivatives is shown
in Table 3. Initially, retaining N-methylcyclohexylamine
as R1 group, incorporation of N-substituted propionamide
side chain resulted in 31 and 32 with EC50 = 11.62
and 3.16 μM, respectively. Introduction of a morpholine
group as a replacement of the N-methylcyclohexylamine
yielded N-monosubstituted amide 33 and N,N-disubstituted
amide 34 with lower binding affinity (EC50 > 20 μM and
EC50 = 6.03 μM, respectively). Interestingly, it was obvi-
ously found that amide types of 32 (EC50 = 3.16 μM)
and 34 (EC50 = 6.03 μM) exhibited significant enhance-
ment in activity compared to the corresponding ester types
of 9 (EC50 > 10 μM) and 12 (EC50 > 10 μM). Further,
the N,N-disubstituted amide inhibitor was far superior to
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Table 2 Inhibitory effects of
tricyclic quinoxalinone
derivatives on HCV replication
in Huh7 cells
Anti-HCV activity Cytotoxicity
Compound
24
R3
SIa
EC50 (μM)
CC50 (μM)
3.94
4.54
1.15
4.14
4.94
3.99
4.85
0.96
0.98
25
26
27
6.14
5.11
0.83
>25
0.08 IU/mL
>2 IU/mL
rIFNα-2b
a
The selectivity index (SI) is calculated as CC50/EC50
the N-monosubstituted amide compound in antiviral activ-
ity against HCV. Similarly, the rules deduced from further
results of incorporation of a formamide group were con-
sistent with the data obtained from the introduction of
propionamide side chain above. Thus, it was encouraging
to see that the antiviral potency of inhibitors 35 and 36
was greatly improved with N-methylcyclohexylamine as
R1 group with EC50 = 1.12 μM and 0.21 μM, a fivefold
improvement in potency compared to the respective ana-
logues of the corresponding ester type 14. In addition, it
was evident that the application of bioisostere provided bet-
ter selectivity (36, SI = 47.19). When the N-methylaniline
moiety was introduced to C-6 position, removal of the flu-
orine atom from the benzene ring resulted in compounds
37 (EC50 > 20 μM) and 38 (EC50 = 1.25 μM), which
also demonstrated that N,N-disubstituted amide inhibitor
did appreciably improve target binding or cellular activity.
However, replacement of phenyl with the naphthalene group
yielded compounds 39 and 40 with EC50 > 20 μM and
EC50 = 7.78 μM, respectively. This result clearly reinforced
did appreciably improve antiviral activity against HCV.
Thus, to further explore amide analogues with high potency
and excellent selectivity, compounds bearing a wide vari-
ety of halogen substituents attached to the benzene ring
were synthesized. N-methylcyclohexylamine was retained
as R1 side chain because it demonstrated improved activ-
ity against HCV in comparison to other R1 moieties. Data
for the resulting compounds are summarized in Table 4.
Moving the fluorine atom to ortho or meta position of
phenyl resulted in 42 and 43 with EC50 = 3.58 μM and
3.08 μM, respectively, a 19- to 22-fold loss in activity com-
pared to inhibitor 36 which exhibited potent activity against
HCV (EC50 = 0.16 μM). However, removal of the fluo-
rine atom in 42 gave 41, a slightly more active compound
with EC50 = 1.58 μM. The same effect was observed when
incorporating more than one fluorine or chlorine atom on
the benzene ring (compounds 44–47). On the other hand,
replacement of the hydrogen atom in 41 with a cyano group
in the para position of phenyl yielded 48 with similar
potency (EC50 = 2.48 μM). All the above data suggested
that introduction of more than one halogen (fluorine or
chlorine atom) or a strong electron-withdrawing group on
the benzene ring might reduce electron atmosphere den-
π
π
interactions resulted in loss of
the fact that enhancing
potency.
−
In view of the observed SARs above, it was clear that
π
π
interactions, and this may
incorporation of the N,N-disubstituted formamide moiety
sity further and affect the
−
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Table 3 Inhibitory effects of
amide-substituted
quinoxalin-2(1H)-one
derivatives on HCV replication
in Huh7 cells
Anti-HCV activity Cytotoxicity
Compound
R1
R4
H
R3
n
1
1
SIa
EC50 (μM)
CC50 (μM)
11.62
11.88
1.02
1.77
31
32
Me
3.16
>20
6.03
1.12
0.21
>20
1.25
5.58
>20
H
Me
H
1
1
0
0
0
0
1.00
>3.32
11.47
47.19
1.00
33
34
35
>20
12.85
9.91
>20
36
Me
H
(BH6870)
37
38
Me
11.25
9.00
H
0
0
>20
>20
1.00
39
Me
7.78
10.02
1.29
>50
40
0.04 IU/mL
>2 IU/mL
rIFNα-2b
a
The selectivity index (SI) is calculated as CC50/EC50
contribute to the difference in potency and cytotoxicity.
Moreover, based on inhibitor 36, modification by blocking
the lactam NH-group of quinoxalin-2(1H)-one was per-
formed to result in 53 with EC50 = 3.43 μM, with a 21-fold
loss in activity, which demonstrated that the NH-group on
the lactam moiety was definitely required for anti-HCV
activity.
antiviral potency (EC50 = 0.21 μM) and a good cell safety
index (SI = 47.19).
In conclusion, quinoxalin-2(1H)-one containing a 4-aryl-
substituted thiazol-2-amine moiety was optimal for antiviral
activity. Increase of steric hindrance and hydrophilicity
was unfavorable for the anti-HCV activity although the
3,4-double bond could be to some extent mimicked by a
five-membered ring. Introducing a hydrogen-bond accep-
tor (such as ester or amide group) at the C-3 position
of quinoxalin-2(1H)-one was beneficial for the antiviral
potency, especially when N,N-disubstituted amide was far
superior to N-monosubstituted amide. Moreover, incorpora-
tion of more than one halogen (fluorine or chlorine atom)
or a strong electron-withdrawing group on the benzene ring
of thiazole-phenyl moiety might reduce electron atmosphere
density further and resulted in a dramatical loss of potency,
and the NH-group of the lactam moiety was clearly required
for anti-HCV activity.
Conclusions
This study has identified new quinoxalin-2(1H)-one deriv-
atives as potent inhibitors against HCV. On the basis of
lead compound 2, 35 new quinoxalinone derivatives were
designed and synthesized. The anti-HCV activity and a fur-
ther SARs study of these compounds were carried out in an
effort to lead to the the discovery of BH6870 (36) as a new
non-nucleoside small-molecule HCV inhibitor showing high
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Table 4 Inhibitory effects of
N,N-dimethyl formamide
substituted quinoxalin-2-one
derivatives on HCV replication
in Huh7 cells
Anti-HCV activity Cytotoxicity
Compound
R3
R5
H
SIa
61.75
4.54
EC50 (μM)
CC50 (μM)
36
0.16
9.88
(BH6870)b
41
H
1.58
3.58
7.17
7.78
H
H
H
H
H
H
2.17
2.24
2.32
2.80
3.34
42
3.08
2.97
3.26
3.11
6.90
6.89
43
44
45
46
9.14
10.40
3.38
2.48
6.62
4.48
1.96
1.81
47
48
H
Me
3.43
6.85
2.00
53
0.09 IU/mL
>2 IU/mL
>22.2
rIFNα-2b
a
The selectivity index (SI) is calculated as CC50/EC50
The repeated data confirmed in the same assays
b
1
Experimental
Chemistry
wise noted. H NMR and 13C NMR spectra were recorded
at 300 and 150 MHz, respectively, on Varian Mercury and
Varian NMR System spectrometers in acetone-d6 or DMSO-
d6 with TMS as the internal standard. Chemical shifts were
General All of the chemicals used were obtained from
commercialsources(AcrosOrganics, AlfaAesar, andSigma-
Aldrich), and were used without further purification. Sol-
vents were used without purification or drying, unless other-
reported in ppm ( ) relative to the solvent, and coupling
δ
constants (J) were reported in Hz. Melting points were deter-
mined without correction with a Yanaco micromelting point
apparatus. Automatic HPLC-MS analysis was performed
123

Mol Divers
on a Thermo Finnigan LCQ Advantage mass spectrometer
equipped with an Agilent pump, an Agilent detector, an Agi-
lent liquid handler, and a fluent splitter. The column used
was a Kromasil C18 column (4.6 μm, 4.6 mm × 50 mm)
from DIKMA for analysis. The eluent was a mixture of ace-
tonitrile and water containing 0.05% HCOOH with a linear
gradient from 5:95 to 95:5 (v/v) of acetonitrile–H2O within
5 min at a 1 mL/min flow rate for analysis. The UV detec-
tion was carried out at a UV wavelength of 254 nm. The
5% of the eluent was split into the MS system. Mass spectra
were recorded in either positive or negative ion mode using
electrospray ionization (ESI). High-resolution mass spectra
(HRMS) were recorded on Thermo Scientific Exactive Plus
System. The ion source is ESI. Flash column chromatogra-
phy was performed with silica gel 60 (200–300 mesh) from
Qingdao Haiyang Chemical Co., Ltd. All tested compounds
were purified until the purity was ≥95%, detected by HPLC-
MS under UV 254 nm wavelength, NMR, melting point, and
HRMS.
HRMS-ESI m/z [M+H]+ calcdforC20H29N4O8: 453.1980,
found: 453.1976.
Dimethyl 2-((5-morpholino-2,4-dinitrophenyl)amino)
pentanedioate (4c)
Following general procedure A starting from morpholine
(0.87 mL, 10 mmol) yielded a dark-yellow powder (3.28 g,
77% over two steps); mp: 142–144 ◦C; 1H NMR (300 MHz,
Acetone-d6): = 8.87 (d, J = 7.2 Hz, 1H), 8.83 (s, 1H), 6.46
δ
(s, 1H), 4.78 (q, J = 7.2 Hz, 1H), 3.81 (s, 3H), 3.78 (t, J
= 4.5 Hz, 4H), 3.62 (s, 3H), 3.24 (t, J = 4.5 Hz, 4H), 2.53
(t, J = 7.2 Hz, 2H), 2.28 ppm (q, J = 7.2 Hz, 2H); HRMS-
ESI m/z [M +H]+ calcd for C17H23N4O9: 427.1460, found:
427.1456.
Diethyl 2-((5-(cyclohexyl(methyl)amino)-2,4-
dinitrophenyl)amino)malonate (4d)
Following general procedure A starting from N-methylcyc-
lohexylamine (1.30 mL, 10 mmol) yielded a dark-yellow
powder (3.62 g, 80% over two steps); mp: 123–124 ◦C; 1H
General procedure A for the synthesis of compounds 4a, 4c,
4d, and 4f
NMR (300 MHz, Acetone-d6): = 9.13 (d, J = 6.0 Hz, 1H),
δ
To a stirred solution of 1,5-difluoro-2,4-dinitrobenzene
(DFDNB; 2.04 g, 10 mmol) in THF (50 mL) was added
DIPEA (1.75 mL, 10 mmol) and N-methylcyclohexylamine
(1.30 mL, 10 mmol) or morpholine (0.87 mL, 10 mmol).
After vigorously stirring at room temperature until the total
disappearance of DFDNB monitored by HPLC-MS analysis,
intermediate (3a or 3c) was obtained without purification.
Then, DIPEA (3.50 mL, 20 mmol) and L-glutamic acid
dimethyl ester hydrochloride (2.12 g, 10 mmol) or diethyl
aminomalonate hydrochloride (2.12 g, 10 mmol) were added
and stirred under reflux for 6–36 h. After the reaction was
complete(monitoredbyHPLC-MSanalysis), thesolventwas
evaporated in vacuo. Saturated ammonium chloride solution
(50 mL) was added to the resulting product and was fur-
ther extracted by CH2Cl2 (2 × 50 mL). The organic layers
were combined, dried over anhydrous Na2SO4, and evapo-
rated in vacuo. Intermediate compound (4a, 4c, 4d or 4f) was
obtained after purification by silica gel column chromatog-
raphy.
8.71 (s, 1H), 6.19 (s, 1H), 5.31 (d, J = 6.0 Hz, 1H), 4.42–
4.25 (m, 4H), 3.53–3.43 (m, 1H), 2.78 (s, 3H), 1.88–1.84 (m,
4H), 1.72–1.60 (m, 3H), 1.52–1.36 (m, 2H), 1.29 (t, J = 7.2
Hz, 6H), 1.24–1.06 ppm (m, 1H); HRMS-ESI m/z [M+H]+
calcd for C20H29N4O8: 453.1980, found: 453.1978.
Diethyl 2-((5-morpholino-2,4-dinitrophenyl)amino)
malonate (4f)
Following general procedure A starting from morpholine
(0.87 mL, 10 mmol) yielded a dark-yellow powder (3.07 g,
72% over two steps); mp: 121–122 ◦C; 1H NMR (300 MHz,
Acetone-d6): = 9.20–9.18 (m, 1H), 8.84 (s, 1H), 6.34 (s,
δ
1H), 5.41–5.39 (m, 1H), 4.38–4.28 (m, 4H), 3.79 (t, J =
4.5 Hz, 4H), 3.23 (t, J = 4.5 Hz, 4H), 1.29 ppm (t, J = 7.2
Hz, 6H); HRMS-ESI m/z [M+H]+ calcd for C17H23N4O9:
427.1460, found: 427.1458.
General procedure B for the synthesis of compounds 4b and
4e
Dimethyl 2-((5-(cyclohexyl(methyl)amino)-2,4-
dinitrophenyl)amino)pentanedioate (4a)
To a stirred solution of 1,5-difluoro-2,4-dinitrobenzene
(DFDNB; 2.04 g, 10 mmol) in THF (50 mL) was added
K2CO3 (1.38 g, 10 mmol) and N-methylaniline (1.08 mL,
10 mmol). The mixture was stirred under reflux for 36 h.
The suspension was cooled and filtered. Then, the filtrate
was concentrated under reduced pressure. The residue was
dissolved in saturated ammonium chloride solution (50 mL)
and extracted by CH2Cl2 (2 × 50 mL). The organic phases
were combined, dried over anhydrous Na2SO4, and evap-
Following general procedure A starting from N-methylcyc-
lohexylamine(1.30mL, 10mmol)yieldedanorangeoil(3.75
g, 83% over two steps); 1H NMR (300 MHz, Acetone-d6):
= 8.70−8.67 (m, 2H), 6.23 (s, 1H), 4.65 (q, J = 6.9 Hz,
δ
1H), 3.80 (s, 3H), 3.62 (s, 3H), 3.49–3.41 (m, 1H), 2.80 (s,
3H), 2.54 (t, J = 7.2 Hz, 2H), 2.29 (q, J = 6.9 Hz, 2H), 1.86–
1.82 (m, 4H), 1.72–1.59 (m, 3H), 1.49–1.08 ppm (m, 3H);
123

Mol Divers
orated in vacuo to give crude intermediate 3b. Then, the
residue was dissolved in THF (50 mL). DIPEA (3.50 mL,
20 mmol) and L-glutamic acid dimethyl ester hydrochloride
(2.12 g, 10 mmol) or diethyl aminomalonate hydrochloride
(2.12 g, 10 mmol) were added and stirred under reflux for
12–24 h. After the reaction was completed (monitored by
HPLC-MS analysis), the solvent was evaporated in vacuo.
Saturated ammonium chloride solution (50 mL) was added
to the resulting product and was further extracted by CH2Cl2
(2 × 50 mL). The organic layers were combined, dried over
anhydrous Na2SO4, and evaporated in vacuo. Intermediate
compound (4b or 4e) was obtained after purification by silica
gel column chromatography.
(s, 1H), 7.16 (s, 1H), 6.46 (s, 1H), 5.55 (s, 2H), 3.60 (s, 3H),
2.93 (t, J = 7.2 Hz, 2H), 2.72 (t, J = 7.2 Hz, 2H), 2.69–2.66
(m, 1H), 2.56 (s, 3H), 1.77–1.69 (m, 4H), 1.56–1.52 (m, 1H),
1.38–1.04 ppm (m, 5H); HRMS-ESI m/z [M + H]+ calcd
for C19H27N4O3: 359.2078, found: 359.2074.
Methyl 3-(6-amino-7-(methyl(phenyl)amino)-3-oxo-3,4-
dihydroquinoxalin-2-yl) propanoate (5b)
Following general procedure C starting from 4b (3 g,
6.73 mmol) yielded a light-yellow powder (1.99 g, 84%);
1
mp: 183−185 ◦C; H NMR (300 MHz, DMSO-d6):
=
δ
12.04 (s, 1H), 7.16–7.11 (m, 3H), 6.68 (t, J = 7.5 Hz, 1H),
6.58–6.56 (m, 3H), 5.67 (s, 2H), 3.56 (s, 3H), 3.11 (s, 3H),
2.92 (t, J = 6.9 Hz, 2H), 2.69 ppm (t, J = 6.9 Hz, 2H); HRMS-
ESI m/z [M+H]+ calcd for C19H21N4O3: 353.1608, found:
353.1606.
Dimethyl 2-((5-(methyl(phenyl)amino)-2,4-dinitrophenyl)
amino)pentanedioate (4b)
Following general procedure B yielded an orange oil (3.35
g, 75% over two steps); 1H NMR (300 MHz, Acetone-d6):
δ
Methyl 3-(6-amino-7-morpholino-3-oxo-3,4-
dihydroquinoxalin-2-yl)propaneate (5c)
= 8.90 (d, J = 6.9 Hz, 1H), 8.70 (s, 1H), 7.32–7.26 (m, 2H),
7.09–7.04 (m, 3H), 6.76 (s, 1H), 4.82–4.76 (m, 1H), 3.82 (s,
3H), 3.62 (s, 3H), 3.52 (s, 3H), 2.54 (t, J = 6.9 Hz, 2H), 2.32
ppm (q, J = 6.9 Hz, 2H); HRMS-ESI m/z [M + H]+ calcd
for C20H23N4O8: 447.1510, found: 447.1508.
Following general procedure C starting from 4c (3 g, 7.04
mmol) yielded a brown-yellow powder (1.80 g, 77%); mp:
>300 ◦C; 1H NMR (300 MHz, DMSO-d6): = 11.97 (s, 1H),
δ
7.11 (s, 1H), 6.48 (s, 1H), 5.64 (s, 2H), 3.76 (t, J = 4.2 Hz,
4H), 3.60 (s, 3H), 2.93 (t, J = 7.2 Hz, 2H), 2.80 (t, J = 4.2 Hz,
4H), 2.72 ppm (t, J = 7.2 Hz, 2H); HRMS-ESI m/z [M+H]+
calcd for C16H21N4O4: 333.1557, found: 333.1558.
Diethyl 2-((5-(methyl(phenyl)amino)-2,4-dinitrophenyl)
amino)malonate (4e)
Following general procedure B yielded an orange powder
◦
1
(3.03 g, 68% over two steps); mp: 118–119 C; H NMR
Ethyl 6-amino-7-(cyclohexyl(methyl)amino)-3-oxo-3,4-
dihydroquinoxaline-2-carboxylate (5d)
(300 MHz, Acetone-d6): = 9.24 (d, J = 6.3 Hz, 1H), 8.69
δ
(s, 1H), 7.32–7.27 (m, 2H), 7.12–7.07 (m, 3H), 6.60 (s, 1H),
5.39 (d, J = 6.3 Hz, 1H), 4.41–4.25 (m, 4H), 3.49 (s, 3H),
1.29 ppm (t, J = 7.2 Hz, 6H); HRMS-ESI m/z [M + H]+
calcd for C20H23N4O8: 447.1510, found: 447.1507.
Following general procedure C starting from 4d (3 g,
6.64 mmol) yielded an orange powder (1.96 g, 86%); mp:
1
214−216 ◦C; H NMR (300 MHz, DMSO-d6): = 12.30
δ
(s, 1H), 7.28 (s, 1H), 6.46 (s, 1H), 6.15 (s, 2H), 4.27 (q, J
= 7.2 Hz, 2H), 2.74–2.68 (m, 1H), 2.57 (s, 3H), 1.79–1.69
(m, 4H), 1.56–1.52 (m, 1H), 1.38–1.05 ppm (m, 8H); HRMS-
ESI m/z [M +H]+ calcd for C18H25N4O3: 345.1921, found:
345.1917.
General procedure C for the synthesis of compounds 5a–f
Compound 4 (3 g) was dissolved in a mixed solvent of THF
(50 mL) and EtOH (50 mL), followed by the addition of 10%
Pd/C (3 g) and NH4COOH (6 g). The mixture was stirred at
room temperature for 2 h. After the reaction was complete
(monitored by HPLC-MS analysis), the residue solid was
filtered off, and the filtrate was concentrated in vacuo. Key
intermediate 5 was obtained after purification by silica gel
column chromatography.
Ethyl 6-amino-7-(methyl(phenyl)amino)-3-oxo-3,4-
dihydroquinoxaline-2-carboxylate (5e)
Following general procedure C starting from 4e (3 g,
6.73 mmol) yielded an orange powder (1.82 g, 80%);
Methyl 3-(6-amino-7-(cyclohexyl(methyl)amino)-3-oxo-3,4-
dihydroquinoxalin-2-yl) propanoate (5a)
mp:132−134 ◦C;1HNMR(300MHz, DMSO-d6): =12.40
δ
(s, 1H), 7.32 (s, 1H), 7.15 (t, J = 7.8 Hz, 2H), 6.70 (t, J = 7.2
Hz, 1H), 6.60 (d, J = 8.1 Hz, 2H), 6.56 (s, 1H), 6.26 (s, 2H),
4.27 (q, J = 7.2 Hz, 2H), 3.12 (s, 3H), 1.27 ppm (t, J = 7.2
Hz, 3H); HRMS-ESI m/z [M+H]+ calcd for C18H19N4O3:
339.1452, found: 339.1446.
Following general procedure C starting from 4a (3 g, 6.64
mmol) yielded a brown-yellow powder (2.07 g, 87%);
mp:207−208 ◦C;1HNMR(300MHz, DMSO-d6): =11.94
δ
123

Mol Divers
General procedure D for the synthesis of compounds 7a–f,
30a–h, and 52
Methyl 3-(7-(cyclohexyl(methyl)amino)-3-oxo-6-((4-
phenylthiazol-2-yl)amino)-3,4-dihydroquinoxalin-2
-yl)propanoate (8)
To a stirred solution of amine intermediate (5, 28 or 50, 2.0
mmol) in dry acetone (30 mL), benzoyl isothiocyanate (0.32
mL, 2.4 mmol) was added. The reaction mixture was refluxed
for 3 h. After the reaction was completed, the solvent was
evaporated in vacuo to give crude compound (6, 29 or 51)
without further purification. Then, the residue and K2CO3
(415 mg, 3.0 mmol) were dissolved in a mixed solvent of
EtOH (40 mL) and H2O (10 mL). The reaction mixture was
heated at 75 ◦C for 1 h. After the reaction was complete (mon-
itored by HPLC-MS analysis), the solvent was evaporated
carefully under reduced pressure. The thiourea intermediate
(7, 30 or 52) was characterized after purification by silica gel
column chromatography.
Following general procedure E starting from 7a (83 mg, 0.20
mmol) and 2-bromo-1-phenylethanone (48 mg, 0.24 mmol)
yielded a yellow powder (74 mg, 72%); mp: 234−236 ◦C;
1H NMR (300 MHz, DMSO-d6): = 12.68 (s, 1H), 9.69 (s,
δ
1H), 8.58 (s, 1H), 8.10 (d, J = 7.5 Hz, 2H), 7.49–7.44 (m,
4H), 7.34 (t, J = 7.5 Hz, 1H), 3.62 (s, 3H), 3.03 (t, J = 7.2 Hz,
2H), 2.79 (t, J = 7.2 Hz, 2H), 2.73 (br. s, 1H), 2.66 (s, 3H),
1.89–1.85 (m, 2H), 1.71–1.67 (m, 2H), 1.54–1.51 (m, 1H),
1.31–1.02 ppm (m, 5H); HRMS-ESI m/z [M + H]+ calcd
for C28H32N5O3S: 518.2220, found: 518.2218.
Methyl 3-(7-(cyclohexyl(methyl)amino)-6-((4-(4-
fluorophenyl)thiazol-2-yl)amino)-3-oxo-3,4-
dihydroquinoxalin-2-yl)propanoate (9)
Methyl 3-(7-(cyclohexyl(methyl)amino)-3-oxo-6-thioureido
-3,4-dihydroquinoxalin-2-yl)propanoate (7a)
Following general procedure E starting from 7a (83 mg,
0.20 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52
mg, 0.24 mmol) yielded a yellow powder (80 mg, 75%);
Following general procedure D starting from 5a (716 mg, 2.0
mmol) yielded a dark-yellow powder (584 mg, 70% over two
steps); mp: 117−119 ◦C; 1H NMR (300 MHz, DMSO-d6):
mp:247−249 ◦C;1HNMR(300MHz, DMSO-d6): =12.66
δ
δ
= 12.23 (s, 1H), 9.12 (s, 1H), 8.17 (s, 1H), 7.93 (s, 2H), 7.37
(s, 1H), 3.60 (s, 3H), 3.02 (t, J = 7.2 Hz, 2H), 2.77 (t, J =
7.2 Hz, 2H), 2.72–2.68 (m, 1H), 2.63 (s, 3H), 1.80–1.69 (m,
4H), 1.56–1.53 (m, 1H), 1.36–1.01 ppm (m, 5H); HRMS-ESI
m/z [M + H]+ calcd for C20H28N5O3S: 418.1907, found:
418.1902.
(s, 1H), 9.71 (s, 1H), 8.56 (s, 1H), 8.13 (dd, J = 8.7 Hz, 5.7
Hz, 2H), 7.47 (s, 1H), 7.43 (s, 1H), 7.26 (t, J = 9.0 Hz,
2H), 3.61 (s, 3H), 3.01 (t, J = 7.2 Hz, 2H), 2.77 (t, J = 7.2
Hz, 2H), 2.71 (br. s, 1H), 2.65 (s, 3H), 1.87–1.83 (m, 2H),
1.69–1.66 (m, 2H), 1.53–1.50 (m, 1H), 1.29–1.00 ppm (m,
5H); HRMS-ESI m/z [M + H]+ calcd for C28H31FN5O3S:
536.2126, found: 536.2122.
Methyl 3-(7-(methyl(phenyl)amino)-3-oxo-6-thioureido
-3,4-dihydroquinoxalin-2-yl) propanoate (7b)
Methyl 3-(7-(methyl(phenyl)amino)-3-oxo-6-((4-
phenylthiazol-2-yl)amino)-3,4-dihy
Following general procedure D starting from 5b (704 mg,
2.0 mmol) yielded a yellow powder (534 mg, 65% over two
steps); mp: 125−127 ◦C; 1H NMR (300 MHz, DMSO-d6):
droquinoxalin-2-yl)propanoate (10)
Following general procedure E starting from 7b (82 mg,
0.20 mmol) and 2-bromo-1-phenylethanone (48 mg, 0.24
mmol) yielded a brown-yellow powder (85 mg, 83%);
= 12.37 (s, 1H), 9.21 (s, 1H), 8.43 (s, 1H), 7.86 (br. s, 2H),
δ
7.36 (s, 1H), 7.18 (t, J = 7.8 Hz, 2H), 6.76 (t, J = 7.2 Hz, 1H),
6.67 (d, J = 8.1 Hz, 2H), 3.56 (s, 3H), 3.11 (s, 3H), 3.01 (t,
J = 6.9 Hz, 2H), 2.73 ppm (t, J = 6.9 Hz, 2H); HRMS-ESI
m/z [M + H]+ calcd for C20H22N5O3S: 412.1438, found:
412.1437.
mp:234−236 ◦C;1HNMR(300MHz, DMSO-d6): =12.80
δ
(s, 1H), 10.06 (s, 1H), 8.87 (s, 1H), 8.11 (d, J = 7.2 Hz, 2H),
7.49–7.43 (m, 3H), 7.35–7.31 (m, 2H), 7.16 (t, J = 7.8 Hz,
2H), 6.73 (t, J = 7.2 Hz, 1H), 6.62 (d, J = 7.8 Hz, 2H), 3.56
(s, 3H), 3.14 (s, 3H), 3.00 (t, J = 6.9 Hz, 2H), 2.73 ppm
(t, J = 6.9 Hz, 2H); HRMS-ESI m/z [M + H]+ calcd for
C28H26N5O3S: 512.1751, found: 512.1746.
General procedure E for the synthesis of compounds 8–19,
24–27, 31–48, and 53
Thiourea intermediate (7, 23, 30 or 52, 0.20 mmol) and
various α-bromo-substituted ketones (0.24 mmol) were dis-
solved in EtOH (6 mL) and refluxed until the total disap-
pearance of thiourea intermediate monitored by HPLC-MS
analysis. The mixture was concentrated in vacuo, and the
final products 8–19, 24–27, 31–48, and 53 were character-
ized after purification by silica gel column chromatography.
Methyl 3-(6-((4-(4-fluorophenyl)thiazol-2-yl)amino)-7-
(methyl(phenyl)amino)-3-oxo-3,4-dihydroquinoxalin-2
-yl)propanoate (11)
Following general procedure E starting from 7b (82 mg,
0.20 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52
mg, 0.24 mmol) yielded a brown-yellow powder (84 mg,
123

Mol Divers
1
79%); mp: 253−254 ◦C; 1H NMR (300 MHz, DMSO-d6):
= 163.85, 161.92, 161.72 (d, JC−F = 243.2 Hz), 153.07,
= 12.80 (s, 1H), 10.08 (s, 1H), 8.86 (s, 1H), 8.16 (dd, J =
149.10, 145.24, 141.37, 137.73, 131.88, 130.81 (d, 4 JC−F
=
δ
8.7 Hz, 5.7 Hz, 2H), 7.42 (s, 1H), 7.35 (s, 1H), 7.27 (t, J =
9.0 Hz, 2H), 7.16 (t, J = 7.8 Hz, 2H), 6.73 (t, J = 7.2 Hz,
1H), 6.62 (d, J = 8.1 Hz, 2H), 3.56 (s, 3H), 3.13 (s, 3H), 3.01
(t, J = 6.9 Hz, 2H), 2.73 ppm (t, J = 6.9 Hz, 2H); HRMS-ESI
m/z [M + H]+ calcd for C28H25FN5O3S: 530.1657, found:
530.1653.
2.4 Hz), 128.10 (d, 3 JC−F = 7.6 Hz), 125.69, 123.92, 115.37
(d, 2 JC−F = 21.2 Hz), 105.26, 100.76, 62.02, 61.28, 38.46,
29.11, 25.50, 24.99, 14.05 ppm; HRMS-ESI m/z [M + H]+
calcd for C27H29FN5O3S: 522.1970, found: 522.1971.
Ethyl 7-(cyclohexyl(methyl)amino)-6-((4-(naphthalen-1-
yl)thiazol-2-yl)amino)-3-oxo-3,4-dihydroquinoxaline-2-
carboxylate (15)
Methyl 3-(6-((4-(4-fluorophenyl)thiazol-2-yl)amino)-7-
morpholino-3-oxo-3,4-dihydroquinoxalin-2-yl)propanoate
(12)
Following general procedure E starting from 7d (81 mg,
0.20 mmol) and 2-bromo-1-(naphthalen-1-yl)ethanone (60
mg, 0.24 mmol) yielded an orange powder (83 mg, 75%);
Following general procedure E starting from 7c (78 mg,
0.20 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52
mg, 0.24 mmol) yielded a yellow powder (90 mg, 88%);
mp: 132−134 ◦C; 1H NMR (300 MHz, DMSO-d6):
=
δ
12.85 (s, 1H), 9.92 (s, 1H), 8.40–8.38 (m, 2H), 8.03–7.90
(m, 3H), 7.65–7.55 (m, 4H), 7.33 (s, 1H), 4.32 (q, J = 7.2
Hz, 2H), 2.82–2.75 (m, 1H), 2.69 (s, 3H), 1.93–1.89 (m,
2H), 1.74–1.70 (m, 2H), 1.57–1.54 (m, 1H), 1.33–1.05 ppm
mp:254−256 ◦C;1HNMR(300MHz, DMSO-d6): =12.65
δ
(s, 1H), 9.59 (s, 1H), 8.57 (s, 1H), 8.12 (dd, J = 8.7 Hz, 5.7
Hz, 2H), 7.45 (s, 1H), 7.42 (s, 1H), 7.26 (t, J = 9.0 Hz,
2H), 3.86 (br. s, 4H), 3.61 (s, 3H), 3.02 (t, J = 6.9 Hz, 2H),
2.85 (br. s, 4H), 2.77 ppm (t, J = 6.9 Hz, 2H); HRMS-ESI
m/z [M + H]+ calcd for C25H25FN5O4S: 510.1606, found:
510.1604.
(m, 8H); 13C NMR (150 MHz, DMSO-d6): = 163.82,
δ
161.59, 152.82, 149.45, 145.29, 141.40, 137.80, 133.49,
132.68, 131.87, 130.64, 128.31, 128.23, 127.46, 126.48,
125.87, 125.68, 125.51, 125.48, 123.87, 109.64, 100.59,
61.91, 61.24, 38.27, 29.14, 25.50, 25.01, 14.03 ppm; HRMS-
ESI m/z [M + H]+ calcd for C31H32N5O3S: 554.2220,
found: 554.2219.
Methyl 3-(7-morpholino-6-((4-(naphthalen-1-yl)thiazol-2-
yl)amino)-3-oxo-3,4-dihydroquinoxalin-2-yl)propanoate
(13)
Ethyl 7-(methyl(phenyl)amino)-3-oxo-6-((4-phenylthiazol-
Following general procedure E starting from 7c (78 mg, 0.20
mmol) and 2-bromo-1-(naphthalen-1-yl)ethanone (60 mg,
0.24 mmol) yielded a brown-yellow powder (76 mg, 70%);
2-yl)amino)-3,4-dihydroquinoxaline-2-carboxylate (16)
Following general procedure E starting from 7e (79 mg,
0.20 mmol) and 2-bromo-1-phenylethanone (48 mg, 0.24
mmol) yielded a dark-yellow powder (62 mg, 62%); mp:
mp:236−237 ◦C;1HNMR(300MHz, DMSO-d6): =12.35
δ
(s, 1H), 9.57 (s, 1H), 8.42–8.38 (m, 1H), 8.26 (s, 1H), 8.00–
7.94 (m, 2H), 7.88 (d, J = 6.3 Hz, 1H), 7.62–7.53 (m, 3H),
7.41 (s, 1H), 7.26 (s, 1H), 3.87 (br. s, 4H), 3.60 (s, 3H), 2.98
(t, J = 7.2 Hz, 2H), 2.88 (br. s, 4H), 2.75 ppm (t, J = 7.2 Hz,
2H); HRMS-ESI m/z [M + H]+ calcd for C29H28N5O4S:
542.1856, found: 542.1853.
255−257 ◦C; 1H NMR (300 MHz, DMSO-d6): = 13.26 (s,
δ
1H), 10.26 (s, 1H), 8.92 (s, 1H), 8.12 (d, J = 7.2 Hz, 2H),
7.54–7.45 (m, 4H), 7.34 (t, J = 7.2 Hz, 1H), 7.17 (t, J = 7.8
Hz, 2H), 6.75 (t, J = 7.2 Hz, 1H), 6.65 (d, J = 7.8 Hz, 2H),
4.31 (q, J = 7.2 Hz, 2H), 3.15 (s, 3H), 1.29 ppm (t, J = 7.2
Hz, 3H); HRMS-ESI m/z [M+H]+ calcd for C27H24N5O3S:
498.1594, found: 498.1590.
Ethyl 7-(cyclohexyl(methyl)amino)-6-((4-(4-fluorophenyl)
thiazol-2-yl)amino)-3-oxo-3,4-dihydroquinoxaline-2-
carboxylate (14)
Ethyl 7-(methyl(phenyl)amino)-6-((4-(naphthalen-1-yl)
thiazol-2-yl)amino)-3-oxo-3,4-dihydroquinoxaline-2-
carboxylate (17)
Following general procedure E starting from 7d (81 mg,
0.20 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52
mg, 0.24 mmol) yielded an orange powder (84 mg, 81%);
Following general procedure E starting from 7e (79 mg,
0.20 mmol) and 2-bromo-1-(naphthalen-1-yl)ethanone (60
mg, 0.24 mmol) yielded an orange powder (83 mg, 76%);
mp: 184−186 ◦C; 1H NMR (300 MHz, DMSO-d6):
=
δ
13.14 (s, 1H), 9.96 (s, 1H), 8.66 (s, 1H), 8.16 (dd, J =
8.7 Hz, 5.7 Hz, 2H), 7.65 (s, 1H), 7.52 (s, 1H), 7.29 (t,
J = 9.0 Hz, 2H), 4.34 (q, J = 7.2 Hz, 2H), 2.78–2.70
(m, 1H), 2.66 (s, 3H), 1.90–1.87 (m, 2H), 1.71–1.68 (m,
2H), 1.55–1.52 (m, 1H), 1.32 (t, J = 7.2 Hz, 3H), 1.24–
mp:135−137 ◦C;1HNMR(300MHz, DMSO-d6): =12.95
δ
(s, 1H), 10.27 (s, 1H), 8.73 (s, 1H), 8.39–8.36 (m, 1H), 8.02–
7.92 (m, 3H), 7.63 (t, J = 7.5 Hz, 1H), 7.57–7.53 (m, 3H),
7.28 (s, 1H), 7.19 (t, J = 7.8 Hz, 2H), 6.76 (t, J = 7.2 Hz, 1H),
6.68 (d, J = 8.1 Hz, 2H), 4.29 (q, J = 7.2 Hz, 2H), 3.18 (s,
1.06 ppm (m, 5H); 13C NMR (150 MHz, DMSO-d6):
δ
123

Mol Divers
3H), 1.27 ppm (t, J = 7.2 Hz, 3H); HRMS-ESI m/z [M+H]+
20 was obtained after purification by silica gel column chro-
matography as a dark-yellow powder (3.32 g, 72% over two
steps); mp: 165 − 167 ◦C; 1H NMR (300 MHz, DMSO-d6):
calcd for C31H26N5O3S: 548.1751, found: 548.1749.
Ethyl 7-morpholino-3-oxo-6-((4-phenylthiazol-2-yl)amino)-
= 8.72 (s, 1H), 8.22 (s, 1H), 7.60 (s, 1H), 3.86 (s, 3H), 3.82–
δ
3,4-dihydroquinoxaline-2-carboxylate (18)
3.75 (m, 1H), 3.68 (s, 3H), 2.74 (s, 3H), 1.78–1.56 (m, 7H),
1.44–1.06 ppm (m, 3H); HRMS-ESI m/z [M + H]+ calcd
for C20H24N5O8: 462.1619, found: 462.1618.
Following general procedure E starting from 7f (75 mg, 0.20
mmol) and 2-bromo-1-phenylethanone (48 mg, 0.24 mmol)
yielded an umber powder (67 mg, 70%); mp: 263−265 ◦C;
Methyl 7-amino-8-(cyclohexyl(methyl)amino)-4-oxo-4,5-
dihydroimidazo[1,5-a]quinoxaline-3-carboxylate (21)
1H NMR (300 MHz, DMSO-d6): = 13.13 (s, 1H), 9.80 (s,
δ
1H), 8.67 (s, 1H), 8.10 (d, J = 7.5 Hz, 2H), 7.60 (s, 1H), 7.55
(s, 1H), 7.47 (t, J = 7.5 Hz, 2H), 7.35 (t, J = 7.5 Hz, 1H),
4.34 (q, J = 7.2 Hz, 2H), 3.89 (br. s, 4H), 2.88 (br. s, 4H),
1.32 ppm (t, J = 7.2 Hz, 3H); HRMS-ESI m/z [M + H]+
calcd for C24H24N5O4S: 478.1544, found: 478.1542.
To a stirred solution of intermediate 20 (4.61 g, 10 mmol)
in a mixed solvent of MeOH (150 mL) and H2O (150 mL)
was added sodium dithionite (17.41 g, 100 mmol), and the
mixture was heated at 70 ◦C. Concentrated hydrochloric acid
(10 mL) was added drop-wise, and the reaction mixture was
stirred at 70 ◦C for 1 h. After the reaction was complete
(monitored by HPLC-MS analysis), the reaction mixture
was cooled and filtered. The filtrate was concentrated under
reduced pressure to give a yellow solid residue, which was
then dissolved in MeOH (300 mL), acidified to pH 1–2 with
concentrated sulfuric acid, and stirred under reflux for 4
h. The reaction mixture was cooled, neutralized using 2 M
sodium hydroxide solution with good stirring, and concen-
trated in vacuo to give a brown-green solid residue, which
was purified by silica gel column chromatography to give
the key intermediate 21 as a brown-green powder (3.21 g,
87%); mp: 258−260 ◦C; 1H NMR (300 MHz, DMSO-d6):
Ethyl 6-((4-(4-fluorophenyl)thiazol-2-yl)amino)-7-
morpholino-3-oxo-3,4-dihydroquinoxaline-2-carboxylate
(19)
Following general procedure E starting from 7f (75 mg,
0.20 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52
mg, 0.24 mmol) yielded an orange powder (77 mg, 78%);
mp: 264–266 ◦C; 1H NMR (300 MHz, DMSO-d6): = 13.13
δ
(s, 1H), 9.82 (s, 1H), 8.67 (s, 1H), 8.15 (dd, J = 8.4 Hz, 5.7
Hz, 2H), 7.60 (s, 1H), 7.53 (s, 1H), 7.28 (t, J = 8.7 Hz, 2H),
4.34 (q, J = 7.2 Hz, 2H), 3.89 (br. s, 4H), 2.88 (br. s, 4H),
1.32 ppm (t, J = 7.2 Hz, 3H); HRMS-ESI m/z [M + H]+
calcd for C24H23FN5O4S: 496.1449, found: 496.1445.
= 11.32 (s, 1H), 9.02 (s, 1H), 7.82 (s, 1H), 6.59 (s, 1H),
δ
5.26 (br. s, 2H), 3.82 (s, 3H), 2.80–2.73 (m, 1H), 2.62 (s,
3H), 1.80–1.70 (m, 4H), 1.56–1.51 (m, 1H), 1.40–1.06 ppm
(m, 5H); HRMS-ESI m/z [M + H]+ calcd for C19H24N5O3:
370.1874, found: 370.1875.
Dimethyl 1-(5-(cyclohexyl(methyl)amino)-2,4-
dinitrophenyl)-1H-imidazole-4,5-dicarboxylate (20)
To a stirred solution of 1,5-difluoro-2,4-dinitrobenzene
(DFDNB; 2.04 g, 10 mmol) in THF (50 mL) was added
DIPEA (1.75 mL, 10 mmol) and N-methylcyclohexylamine
(1.30 mL, 10 mmol). The reaction mixture was stirred at
room temperature until the total disappearance of DFDNB
monitored by HPLC-MS analysis. The solvent was evap-
orated under reduced pressure, and the oily residue was
dissolved in saturated ammonium chloride solution (50 mL)
and extracted by CH2Cl2 (2 × 50 mL). The organic phases
were combined, dried over anhydrous Na2SO4, and evapo-
ratedinvacuotogivecrudeintermediate3a. Then, theresidue
was dissolved in acetone (70 mL). Dimethyl 1H-imidazole-
4,5-dicarboxylate (1.84 g, 10 mmol) and K2CO3 (2.76 g, 20
mmol) were added and stirred under reflux for 6 h. After the
reaction was complete (monitored by HPLC-MS analysis),
the solvent was evaporated in vacuo. Saturated ammonium
chloride solution (50 mL) was added to the resulting prod-
uct and was further extracted by CH2Cl2 (2 × 50 mL).
The organic layers were combined, dried over anhydrous
Na2SO4, and evaporated in vacuo. Intermediate compound
General procedure F for the synthesis of compounds 24–27
To a stirred solution of 21 (1.85 g, 5 mmol) in 80 mL of
dry acetone, benzoyl isothiocyanate (0.81 mL, 6 mmol) was
added. The reaction mixture was refluxed for 3 h. After
the reaction was completed, the solvent was evaporated in
vacuo to give crude compound 22 without further purifica-
tion. Then, the residue was dissolved in MeOH (30 mL), and
the mixture was heated at 50 ◦C. Sodium methoxide (0.54 g,
10 mmol) in methanol (50 mL) was added drop-wise, and
the reaction mixture was stirred at 50 ◦C for 1 h. The reac-
tion mixture was cooled, neutralized using 5% hydrochloric
acid, and concentrated under reduced pressure to give a yel-
low solid residue, which was purified by silica gel column
chromatography. Intermediate compound 23 was obtained
as a yellow powder in 76% yield over two steps. Finally,
thiourea compound 23 (86 mg, 0.20 mmol) and various α-
bromo-substituted ketones (0.24 mmol) were dissolved in
MeOH (6 mL) and refluxed until the total disappearance of
123

Mol Divers
23 monitored by HPLC-MS analysis. The reaction mixture
was concentrated in vacuo, and the final products 24–27 were
characterized after purification by silica gel column chro-
matography.
(m, 2H), 1.73–1.69 (m, 2H), 1.55–1.51 (m, 1H), 1.36–1.04
ppm (m, 5H); 13C NMR (150 MHz, DMSO-d6): = 162.65,
δ
162.60, 153.18, 148.82, 136.90, 133.32, 133.21, 131.97,
131.92, 128.50, 127.78, 126.28, 121.63, 113.60, 111.82,
105.11, 104.02, 62.07, 51.83, 38.20, 29.24, 25.47, 25.01
ppm; HRMS-ESI m/z [M+H]+ calcd for C28H28ClN6O3S:
563.1627, found: 563.1624.
Methyl 8-(cyclohexyl(methyl)amino)-4-oxo-7-((4-
phenylthiazol-2-yl)amino)-4,5-dihydroimidazo
[1,5-a]quinoxaline-3-carboxylate (24)
Following general procedure F starting from 2-bromo-1-
phenylethanone (48 mg, 0.24 mmol) yielded a yellow powder
(86 mg, 81%); mp: 248−250 ◦C; 1H NMR (300 MHz,
Methyl 8-(cyclohexyl(methyl)amino)-7-((4-(naphthalen-1-
yl)thiazol-2-yl)amino)-4-oxo-4,5-dihydroimidazo[1,5-
a]quinoxaline-3-carboxylate (27)
DMSO-d6): = 11.96 (s, 1H), 9.53 (s, 1H), 9.16 (s, 1H),
δ
8.56 (s, 1H), 8.15 (s, 1H), 8.10 (d, J = 7.5 Hz, 2H), 7.46 (t,
J = 7.5 Hz, 2H), 7.43 (s, 1H), 7.34 (t, J = 7.2 Hz, 1H), 3.85
(s, 3H), 2.82–2.75 (m, 1H), 2.71 (s, 3H), 1.91–1.87 (m, 2H),
1.72–1.69 (m, 2H), 1.55–1.52 (m, 1H), 1.36–1.04 ppm (m,
Following general procedure F starting from 2-bromo-1-
(naphthalen-1-yl)ethanone (60 mg, 0.24 mmol) yielded a
1
light-yellow powder (87 mg, 75%); mp: 257−258 ◦C; H
NMR (300 MHz, DMSO-d6): = 11.68 (s, 1H), 9.52 (s,
δ
5H); 13C NMR (150 MHz, DMSO-d6): = 162.62, 162.46,
δ
1H), 9.16 (s, 1H), 8.42–8.39 (m, 1H), 8.25 (s, 1H), 8.14
(s, 1H), 8.01–7.95 (m, 2H), 7.90–7.86 (m, 1H), 7.64–7.54
(m, 3H), 7.20 (s, 1H), 3.83 (s, 3H), 2.89–2.81 (m, 1H), 2.73
(s, 3H), 1.92–1.88 (m, 2H), 1.75–1.71 (m, 2H), 1.57–1.53
(m, 1H), 1.40–1.06 ppm (m, 5H); 13C NMR (150 MHz,
153.17, 150.15, 136.98, 136.37, 134.33, 133.31, 131.96,
128.54, 127.53, 126.29, 126.05, 121.64, 113.54, 111.79,
104.25, 103.99, 62.03, 51.82, 38.15, 29.27, 25.48, 25.02
ppm; HRMS-ESI m/z [M + H]+ calcd for C28H29N6O3S:
529.2016, found: 529.2014.
DMSO-d6): = 162.66, 162.61, 152.90, 149.38, 136.69,
δ
133.48, 133.32, 132.82, 132.02, 130.66, 128.27, 128.14,
127.39, 127.34, 126.34, 126.13, 125.82, 125.60, 125.49,
121.62, 113.93, 111.52, 108.12, 104.75, 61.99, 51.80, 37.66,
29.24, 25.47, 25.10 ppm; HRMS-ESI m/z [M + H]+ calcd
for C32H31N6O3S: 579.2173, found: 579.2170.
Methyl 8-(cyclohexyl(methyl)amino)-7-((4-(4-
fluorophenyl)thiazol-2-yl)amino)-4-oxo-4,5-
dihydroimidazo[1,5-a]quinoxaline-3-carboxylate (25)
Following general procedure F starting from 2-bromo-1-(4-
fluorophenyl)ethanone (52 mg, 0.24 mmol) yielded a light-
1
yellow powder (85 mg, 78%); mp: 262−264 ◦C; H NMR
(300 MHz, DMSO-d6): = 11.95 (s, 1H), 9.55 (s, 1H), 9.16
General procedure G for the synthesis of compounds 28a–h
and 50
δ
(s, 1H), 8.57 (s, 1H), 8.17–8.12 (m, 3H), 7.41 (s, 1H), 7.28 (t,
J = 9.0 Hz, 2H), 3.85 (s, 3H), 2.81–2.74 (m, 1H), 2.70 (s, 3H),
1.91–1.87 (m, 2H), 1.73–1.69 (m, 2H), 1.55–1.52 (m, 1H),
1.36–1.10 ppm (m, 5H); 13C NMR (150 MHz, DMSO-d6):
To a stirred solution of ester intermediate (5a, 5c, 5d, 5e or
49, 5 mmol) in a mixed solvent of EtOH (25 mL) and H2O
(5 mL), lithium hydroxide monohydrate (629 mg, 15 mmol)
was added. The reaction mixture was stirred at 50 ◦C for 1
h. After the reaction was complete (monitored by HPLC-MS
analysis), a partial volume of the solvent was evaporated in
vacuo, and the remaining mixture was acidified to pH 5–6
with 5% hydrochloric acid. The formed precipitate was col-
lected by filtration to give the corresponding crude carboxylic
acid intermediate as a yellow solid. The intermediate (3.0
mmol) was dissolved in THF (50 mL), and then, HOBt (486
mg, 3.6 mmol) and EDCI (690 mg, 3.6 mmol) were added,
followed by the addition of methylamine or dimethylamine
(4.5 mmol, 2 M in THF) drop-wise. The reaction mixture
was stirred at 60 ◦C. After the reaction was complete (mon-
itored by HPLC-MS analysis), the solvent was evaporated
carefully under reduced pressure to give a black oily residue,
which was purified by silica gel column chromatography to
give the amide intermediate (28 or 50).
= 162.61, 162.58, 161.65 (d, 1 J
= 243.2 Hz), 153.17,
δ
C−F
149.05, 136.96, 136.38, 133.32, 131.96, 130.97 (d, 4 JC−F
=
2.7 Hz), 128.08 (d, 3 JC−F = 7.8 Hz), 126.26, 121.63, 115.30
(d, 2 JC−F = 21.3 Hz), 113.55, 111.81, 104.00, 103.96, 62.03,
51.83, 38.18, 29.27, 25.48, 25.02ppm;HRMS-ESI m/z [M+
H]+ calcd for C28H28FN6O3S: 547.1922, found: 547.1920.
Methyl 7-((4-(4-chlorophenyl)thiazol-2-yl)amino)-8-
(cyclohexyl(methyl)amino)-4-oxo-4,5-dihydroimidazo[1,5
-a]quinoxaline-3-carboxylate (26)
Following general procedure F starting from 2-bromo-1-
(4-chlorophenyl)ethanone (56 mg, 0.24 mmol) yielded a
light-yellow powder (81 mg, 72%); mp: 261−263 ◦C; H
1
NMR (300 MHz, DMSO-d6): = 11.95 (s, 1H), 9.59 (s, 1H),
δ
9.16 (s, 1H), 8.56 (s, 1H), 8.16–8.11 (m, 3H), 7.52–7.49 (m,
3H), 3.85 (s, 3H), 2.82–2.74 (m, 1H), 2.70 (s, 3H), 1.91–1.87
123

Mol Divers
3-(6-Amino-7-(cyclohexyl(methyl)amino)-3-oxo-3,4-
6-Amino-7-(cyclohexyl(methyl)amino)-N-methyl-3-oxo-3,4-
dihydroquinoxalin-2-yl)-N-methylpropanamide (28a)
dihydroquinoxaline-2-carboxamide (28e)
Following general procedure G starting from carboxylic acid
type of 5a (1.03 g, 3.0 mmol) yielded a yellow powder (760
mg, 71%); mp: 125−127 ◦C; 1H NMR (300 MHz, DMSO-
Following general procedure G starting from carboxylic acid
type of 5d (948 mg, 3.0 mmol) yielded a dark-yellow pow-
der (622 mg, 63%); mp: 277−278 ◦C; 1H NMR (300 MHz,
d6): = 11.91 (s, 1H), 7.78 (q, J = 4.5 Hz, 1H), 7.18 (s,
DMSO-d6): = 12.53 (s, 1H), 9.37 (q, J = 4.8 Hz, 1H),
δ
δ
1H), 6.46 (s, 1H), 5.54 (s, 2H), 2.88 (t, J = 7.2 Hz, 2H),
2.74–2.67 (m, 1H), 2.58–2.56 (m, 6H), 2.47 (t, J = 7.2 Hz,
2H), 1.78–1.69 (m, 4H), 1.56–1.52 (m, 1H), 1.38–1.04 ppm
(m, 5H); HRMS-ESI m/z [M + H]+ calcd for C19H28N5O2:
358.2238, found: 358.2237.
7.34 (s, 1H), 6.50 (s, 1H), 6.19 (s, 2H), 2.83 (d, J = 4.8
Hz, 3H), 2.76–2.70 (m, 1H), 2.58 (s, 3H), 1.80–1.69 (m,
4H), 1.56–1.53 (m, 1H), 1.39–1.06 ppm (m, 5H); HRMS-
ESI m/z [M+H]+ calcd for C17H24N5O2: 330.1924, found:
330.1922.
3-(6-Amino-7-(cyclohexyl(methyl)amino)-3-oxo-3,4-
dihydroquinoxalin-2-yl)-N,N-dimethylpropanamide (28b)
6-Amino-7-(cyclohexyl(methyl)amino)-N,N-dimethyl-3-
oxo-3,4-dihydroquinoxaline-2-carboxamide (28f)
Following general procedure G starting from carboxylic acid
type of 5a (1.03 g, 3.0 mmol) yielded an orange powder (790
mg, 71%); mp: 190−192 ◦C; 1H NMR (300 MHz, DMSO-
Following general procedure G starting from carboxylic acid
type of 5d (948 mg, 3.0 mmol) yielded a yellow powder (731
mg, 71%); mp: 253−255 ◦C; 1H NMR (300 MHz, DMSO-
d6): = 11.90 (s, 1H), 7.18 (s, 1H), 6.46 (s, 1H), 5.53 (s, 2H),
δ
d6): = 12.24 (s, 1H), 7.24 (s, 1H), 6.49 (s, 1H), 5.85 (s,
δ
3.02 (s, 3H), 2.88 (t, J = 7.2 Hz, 2H), 2.82 (s, 3H), 2.74–2.66
(m, 3H), 2.56 (s, 3H), 1.77–1.69 (m, 4H), 1.55–1.52 (m, 1H),
1.37–1.03 ppm (m, 5H); HRMS-ESI m/z [M+H]+ calcd for
C20H30N5O2: 372.2394, found: 372.2394.
2H), 2.96 (s, 3H), 2.85 (s, 3H), 2.74–2.68 (m, 1H), 2.56 (s,
3H), 1.79–1.69 (m, 4H), 1.56–1.53 (m, 1H), 1.38–1.05 ppm
(m, 5H); HRMS-ESI m/z [M + H]+ calcd for C18H26N5O2:
344.2081, found: 344.2076.
3-(6-Amino-7-morpholino-3-oxo-3,4-dihydroquinoxalin-2-
yl)-N-methylpropanamide (28c)
6-Amino-N-methyl-7-(methyl(phenyl)amino)-3-oxo-3,4-
dihydroquinoxaline-2-carboxamide (28g)
Following general procedure G starting from carboxylic acid
type of 5c (954 mg, 3.0 mmol) yielded a brown-yellow pow-
der (705 mg, 71%); mp: 248 − 250 ◦C; 1H NMR (300 MHz,
Following general procedure G starting from carboxylic acid
type of 5e (930 mg, 3.0 mmol) yielded an orange powder (795
mg, 82%); mp: 270−272 ◦C; 1H NMR (300 MHz, DMSO-
DMSO-d6): = 11.93 (s, 1H), 7.78 (q, J = 4.5 Hz, 1H),
δ
d6): = 12.57 (s, 1H), 9.20 (q, J = 4.8 Hz, 1H), 7.38 (s, 1H),
δ
7.13 (s, 1H), 6.48 (s, 1H), 5.62 (s, 2H), 3.77 (t, J = 4.2 Hz,
4H), 2.88 (t, J = 7.2 Hz, 2H), 2.80 (t, J = 4.2 Hz, 4H), 2.57
(d, J = 4.5 Hz, 3H), 2.47 ppm (t, J = 7.2 Hz, 2H); HRMS-
ESI m/z [M+H]+ calcd for C16H22N5O3: 332.1717, found:
332.1715.
7.16 (t, J = 7.8 Hz, 2H), 6.71 (t, J = 7.2 Hz, 1H), 6.61 (d, J
= 7.8 Hz, 2H), 6.60 (s, 1H), 6.27 (s, 2H), 3.14 (s, 3H), 2.81
ppm (d, J = 4.8 Hz, 3H); HRMS-ESI m/z [M + H]+ calcd
for C17H18N5O2: 324.1455, found: 324.1452.
3-(6-Amino-7-morpholino-3-oxo-3,4-dihydroquinoxalin-2-
6-Amino-N,N-dimethyl-7-(methyl(phenyl)amino)-3-oxo-
yl)-N,N-dimethylpropanamide (28d)
3,4-dihydroquinoxaline-2-carboxamide (28h)
Following general procedure G starting from carboxylic acid
Following general procedure G starting from carboxylic acid
type of 5e (930 mg, 3.0 mmol) yielded a yellow powder (728
mg, 72%); mp: 265−267 ◦C; 1H NMR (300 MHz, DMSO-
type of 5c (954 mg, 3.0 mmol) yielded a tan powder (725 mg,
70%); mp: >300 ◦C; 1H NMR (300 MHz, DMSO-d6):
=
δ
11.93 (s, 1H), 7.13 (s, 1H), 6.48 (s, 1H), 5.61 (s, 2H), 3.76
(t, J = 4.2 Hz, 4H), 3.03 (s, 3H), 2.89 (t, J = 7.2 Hz, 2H),
2.82 (s, 3H), 2.80 (t, J = 4.2 Hz, 4H), 2.68 ppm (t, J = 7.2
Hz, 2H); HRMS-ESI m/z [M+H]+ calcd for C17H24N5O3:
346.1874, found: 346.1868.
d6): = 12.34 (s, 1H), 7.27 (s, 1H), 7.14 (t, J = 7.8 Hz,
δ
2H), 6.69 (t, J = 7.2 Hz, 1H), 6.60–6.58 (m, 3H), 5.98 (s,
2H), 3.12 (s, 3H), 2.95 (s, 3H), 2.86 ppm (s, 3H); HRMS-
ESI m/z [M+H]+ calcd for C18H20N5O2: 338.1612, found:
338.1612.
123

Mol Divers
3-(7-(Cyclohexyl(methyl)amino)-3-oxo-6-thioureido-3,4-
dihydroquinoxalin-2-yl)-N-methylpropanamide (30a)
7-(Cyclohexyl(methyl)amino)-N-methyl-3-oxo-6-
thioureido-3,4-dihydroquinoxaline-2-
carboxamide (30e)
Following general procedure D starting from 28a (714 mg,
2.0 mmol) yielded a dark-yellow powder (607 mg, 73% over
two steps); mp: >300 ◦C; 1H NMR (300 MHz, DMSO-d6):
Following general procedure D starting from 28e (658 mg,
2.0 mmol) yielded an orange powder (566 mg, 73% over two
= 12.18 (s, 1H), 9.10 (s, 1H), 8.16 (s, 1H), 7.92 (s, 2H),
steps); mp: > 300 ◦C; 1H NMR (300 MHz, DMSO-d6): =
δ
δ
7.80 (q, J = 4.5 Hz, 1H), 7.38 (s, 1H), 2.96 (t, J = 7.5 Hz,
2H), 2.72–2.67 (m, 1H), 2.63 (s, 3H), 2.57 (d, J = 4.5 Hz,
3H), 2.52 (t, J = 7.5 Hz, 2H), 1.80–1.69 (m, 4H), 1.56–1.53
(m, 1H), 1.36–1.02 ppm (m, 5H); HRMS-ESI m/z [M+H]+
calcd for C20H29N6O2S: 417.2067, found: 417.2065.
12.77 (s, 1H), 9.28 (s, 1H), 9.09 (q, J = 4.8 Hz, 1H), 8.45 (s,
1H), 8.12 (s, 2H), 7.59 (s, 1H), 2.82 (d, J = 4.8 Hz, 3H), 2.71–
2.67 (m, 1H), 2.64 (s, 3H), 1.82–1.70 (m, 4H), 1.56–1.53 (m,
1H), 1.36–1.02 ppm (m, 5H); HRMS-ESI m/z [M + H]+
calcd for C18H25N6O2S: 389.1754, found: 389.1748.
3-(7-(Cyclohexyl(methyl)amino)-3-oxo-6-thioureido-3,4-
dihydroquinoxalin-2-yl)-N,N-dimethylpropanamide (30b)
7-(Cyclohexyl(methyl)amino)-N,N-dimethyl-3-oxo-6-
thioureido-3,4-dihydroquinoxaline-2-carboxamide (30f)
Following general procedure D starting from 28b (742 mg,
Following general procedure D starting from 28f (686 mg,
2.0 mmol) yielded a yellow powder (659 mg, 82% over two
steps); mp: 230−232 ◦C; 1H NMR (300 MHz, DMSO-d6):
2.0 mmol) yielded a yellow powder (611 mg, 71% over two
steps); mp: >300 ◦C; 1H NMR (300 MHz, DMSO-d6):
=
δ
12.18 (s, 1H), 9.12 (s, 1H), 8.17 (s, 1H), 7.92 (s, 2H), 7.39
(s, 1H), 3.03 (s, 3H), 2.97 (t, J = 7.2 Hz, 2H), 2.82 (s, 3H),
2.75 (t, J = 7.2 Hz, 2H), 2.68–2.59 (m, 4H), 1.80–1.69 (m,
4H), 1.56–1.53 (m, 1H), 1.36–1.01 ppm (m, 5H); HRMS-ESI
m/z [M + H]+ calcd for C21H31N6O2S: 431.2224, found:
431.2224.
= 12.58 (br. s, 1H), 9.19 (s, 1H), 8.26 (s, 1H), 8.01 (s,
δ
2H), 7.46 (s, 1H), 2.98 (s, 3H), 2.87 (s, 3H), 2.70–2.66 (m,
1H), 2.62 (s, 3H), 1.81–1.69 (m, 4H), 1.56–1.53 (m, 1H),
1.36–1.01 ppm (m, 5H); HRMS-ESI m/z [M + H]+ calcd
for C19H27N6O2S: 403.1911, found: 403.1907.
N-methyl-7-(methyl(phenyl)amino)-3-oxo-6-thioureido-3,4-
dihydroquinoxaline-2-carboxamide (30g)
N-methyl-3-(7-morpholino-3-oxo-6-thioureido-3,4-
dihydroquinoxalin-2-yl)propanamide (30c)
Following general procedure D starting from 28g (646 mg,
2.0 mmol) yielded an orange powder (573 mg, 75% over two
Following general procedure D starting from 28c (662 mg,
2.0 mmol) yielded a yellow powder (585 mg, 75% over two
steps); mp: 192−194 ◦C; 1H NMR (300 MHz, DMSO-d6):
steps); mp: 240−242 ◦C; 1H NMR (300 MHz, DMSO-d6):
δ
= 12.85 (s, 1H), 9.34 (s, 1H), 8.96 (q, J = 4.8 Hz, 1H), 8.70 (s,
1H), 8.04 (s, 2H), 7.56 (s, 1H), 7.18 (t, J = 7.8 Hz, 2H), 6.78
(t, J = 7.2 Hz, 1H), 6.68 (d, J = 8.1 Hz, 2H), 3.14 (s, 3H),
2.80 ppm (d, J = 4.8 Hz, 3H); HRMS-ESI m/z [M + H]+
calcd for C18H19N6O2S: 383.1285, found: 383.1282.
= 12.21 (s, 1H), 9.06 (s, 1H), 8.03 (s, 1H), 7.94 (br. s, 2H),
δ
7.81 (q, J = 4.5 Hz, 1H), 7.34 (s, 1H), 3.81 (br. s, 4H), 2.97
(t, J = 7.2 Hz, 2H), 2.83 (br. s, 4H), 2.57 (d, J = 4.5 Hz, 3H),
2.52 ppm (t, J = 7.2 Hz, 2H); HRMS-ESI m/z [M + H]+
calcd for C17H23N6O3S: 391.1547, found: 391.1541.
N,N-dimethyl-3-(7-morpholino-3-oxo-6-thioureido-3,4-
N,N-dimethyl-7-(methyl(phenyl)amino)-3-oxo-6-
dihydroquinoxalin-2-yl)propanamide (30d)
thioureido-3,4-dihydroquinoxaline-2-carboxamide (30h)
Following general procedure D starting from 28d (690 mg,
2.0 mmol) yielded a yellow powder (614 mg, 76% over two
steps); mp: 184 − 186 ◦C; 1H NMR (300 MHz, DMSO-d6):
Following general procedure D starting from 28h (674 mg,
2.0 mmol) yielded an orange powder (578 mg, 73% over two
steps); mp: 184−186 ◦C; 1H NMR (300 MHz, DMSO-d6):
= 12.21 (s, 1H), 9.06 (s, 1H), 8.03 (s, 1H), 7.93 (br. s, 2H),
= 12.73 (s, 1H), 9.27 (s, 1H), 8.62 (s, 1H), 7.96 (br. s, 2H),
δ
δ
7.35 (s, 1H), 3.80 (br. s, 4H), 3.04 (s, 3H), 2.97 (t, J = 7.2 Hz,
2H), 2.84 (br. s, 4H), 2.82 (s, 3H), 2.75 ppm (t, J = 7.2 Hz,
2H); HRMS-ESI m/z [M + H]+ calcd for C18H25N6O3S:
405.1703, found: 405.1703.
7.49 (s, 1H), 7.18 (t, J = 7.8 Hz, 2H), 6.77 (t, J = 7.2 Hz, 1H),
6.68 (d, J = 8.1 Hz, 2H), 3.13 (s, 3H), 2.97 (s, 3H), 2.88 ppm
(s, 3H); HRMS-ESI m/z [M+H]+ calcd for C19H21N6O2S:
397.1441, found: 397.1438.
123

Mol Divers
3-(7-(Cyclohexyl(methyl)amino)-6-((4-(4-
fluorophenyl)thiazol-2-yl)amino)-3-oxo-3,4-
dihydroquinoxalin-2-yl)-N-methylpropanamide (31)
3-(6-((4-(4-Fluorophenyl)thiazol-2-yl)amino)-7-
morpholino-3-oxo-3,4-dihydroquinoxalin-2-yl)-N,N-
dimethylpropanamide (34)
Following general procedure E starting from 30a (83 mg,
0.2mmol)and2-bromo-1-(4-fluorophenyl)ethanone(52mg,
0.24 mmol) yielded a light-yellow powder (69 mg, 65%);
Following general procedure E starting from 30d (81 mg,
0.2 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52
mg, 0.24 mmol) yielded a yellow powder (74 mg, 71%);
mp:120−122 ◦C;1HNMR(300MHz, DMSO-d6): =12.63
mp: 257−259 ◦C; 1H NMR (300 MHz, DMSO-d6):
=
δ
δ
(s, 1H), 9.71(s, 1H), 8.57(s, 1H), 8.15(dd, J =8.7Hz, 5.7Hz,
2H), 7.82 (q, J = 4.5 Hz, 1H), 7.50 (s, 1H), 7.45 (s, 1H), 7.27
(t, J = 9.0 Hz, 2H), 2.97 (t, J = 7.8 Hz, 2H), 2.76–2.68 (m,
1H), 2.66 (s, 3H), 2.59 (d, J = 4.5 Hz, 3H), 2.54 (t, J = 7.8 Hz,
2H), 1.89–1.85 (m, 2H), 1.71–1.67 (m, 2H), 1.55–1.51 (m,
12.61 (s, 1H), 9.59 (s, 1H), 8.57 (s, 1H), 8.13 (dd, J = 8.7
Hz, 5.7 Hz, 2H), 7.46 (s, 2H), 7.27 (t, J = 9.0 Hz, 2H),
3.88 (br. s, 4H), 3.05 (s, 3H), 2.98 (t, J = 7.2 Hz, 2H), 2.86
(br. s, 4H), 2.84 (s, 3H), 2.76 ppm (t, J = 7.2 Hz, 2H); 13C
NMR (150 MHz, DMSO-d6): = 171.27, 162.46, 161.66
δ
1H), 1.31–1.02 ppm (m, 5H); 13C NMR (150 MHz, DMSO-
(d, JC−F = 243.2 Hz), 157.48, 155.13, 148.92, 137.45,
1
1
4
d6): = 171.86, 162.29, 161.67 (d, JC−F = 243.2 Hz),
136.76, 130.94 (d, JC−F = 2.6 Hz), 129.52, 128.06 (d,
δ
157.04, 155.13, 149.02, 138.67, 136.54, 130.93 (d, 4 JC−F
=
3 JC−F = 8.0 Hz), 126.68, 119.28, 115.33 (d, 2 JC−F = 21.2
Hz), 104.59, 102.31, 65.99, 52.39, 36.72, 34.89, 28.86, 27.94
ppm; HRMS-ESI m/z [M + H]+ calcd for C26H28FN6O3S:
523.1922, found: 523.1926.
2.7 Hz), 129.84, 128.07 (d, 3 JC−F = 8.1 Hz), 126.40, 122.68,
115.34 (d, 2 JC−F = 21.2 Hz), 104.35, 101.39, 62.14, 38.65,
31.64, 29.23, 28.37, 25.52, 25.00, 24.97 ppm; HRMS-ESI
m/z [M + H]+ calcd for C28H32FN6O2S: 535.2286, found:
535.2285.
7-(Cyclohexyl(methyl)amino)-6-((4-(4-
fluorophenyl)thiazol-2-yl)amino)-N-methyl-3-oxo-3,4-
dihydroquinoxaline-2-carboxamide (35)
3-(7-(Cyclohexyl(methyl)amino)-6-((4-(4-
fluorophenyl)thiazol-2-yl)amino)-3-oxo-3,4-
dihydroquinoxalin-2-yl)-N,N-dimethylpropanamide (32)
Following general procedure E starting from 30e (78 mg,
0.2 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52 mg,
0.24 mmol) yielded an orange powder (69 mg, 68%);
Following general procedure E starting from 30b (86 mg,
0.2 mmol) and 2-bromo-1-(4-fluorophenyl) ethanone (52
mg, 0.24 mmol) yielded a yellow powder (89 mg, 81%);
mp:252−254 ◦C;1HNMR(300MHz, DMSO-d6): =13.23
δ
(s, 1H), 9.97 (s, 1H), 9.20 (q, J = 4.8 Hz, 1H), 8.68 (s, 1H),
8.16 (dd, J = 8.7 Hz, 5.7 Hz, 2H), 7.69 (s, 1H), 7.52 (s, 1H),
7.29 (t, J = 9.0 Hz, 2H), 2.85 (d, J = 4.8 Hz, 3H), 2.79–
2.73(m, 1H), 2.68 (s, 3H), 1.91–1.87 (m, 2H), 1.72–1.68 (m,
2H), 1.55–1.52 (m, 1H), 1.32–1.02 ppm (m, 5H); HRMS-ESI
m/z [M + H]+ calcd for C26H28FN6O2S: 507.1973, found:
507.1972.
mp:151−153 ◦C;1HNMR(300MHz, DMSO-d6): =12.63
δ
(s, 1H), 9.71 (s, 1H), 8.56 (s, 1H), 8.15 (dd, J = 8.7 Hz, 5.7
Hz, 2H), 7.51 (s, 1H), 7.45 (s, 1H), 7.28 (t, J = 9.0 Hz, 2H),
3.05 (s, 3H), 2.98 (t, J = 7.2 Hz, 2H), 2.84 (s, 3H), 2.78–
2.74 (m, 3H), 2.66 (s, 3H), 1.89–1.85 (m, 2H), 1.71–1.67 (m,
2H), 1.55–1.52 (m, 1H), 1.31–1.02 ppm (m, 5H); HRMS-ESI
m/z [M + H]+ calcd for C29H34FN6O2S: 549.2442, found:
549.2441.
7-(Cyclohexyl(methyl)amino)-6-((4-(4-
fluorophenyl)thiazol-2-yl)amino)-N,N-dimethyl-3-oxo-3,4-
dihydroquinoxaline-2-carboxamide (36)
3-(6-((4-(4-Fluorophenyl)thiazol-2-yl)amino)-7-
morpholino-3-oxo-3,4-dihydroquinoxalin-2-yl)-N-
methylpropanamide (33)
Following general procedure E starting from 30f (80 mg,
0.2mmol)and2-bromo-1-(4-fluorophenyl)ethanone(52mg,
0.24 mmol) yielded a dark-yellow powder (84 mg, 81%);
Following general procedure E starting from 30c (78 mg,
0.2 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52 mg,
0.24 mmol) yielded a flavo-green powder (65 mg, 64%);
mp:163−165 ◦C;1HNMR(300MHz, DMSO-d6): =13.02
δ
(s, 1H), 9.85 (s, 1H), 8.65 (s, 1H), 8.16 (dd, J = 8.4 Hz, 5.7
Hz, 2H), 7.59 (s, 1H), 7.49 (s, 1H), 7.28 (t, J = 8.7 Hz, 2H),
3.00 (s, 3H), 2.91 (s, 3H), 2.77–2.70 (m, 1H), 2.66 (s, 3H),
1.90–1.86 (m, 2H), 1.71–1.68 (m, 2H), 1.55–1.52 (m, 1H),
1.29–0.98 ppm (m, 5H); 13C NMR (150 MHz, DMSO-d6):
mp:261−263 ◦C;1HNMR(300MHz, DMSO-d6): =12.62
δ
(s, 1H), 9.60 (s, 1H), 8.57 (s, 1H), 8.13 (dd, J = 8.7, 5.7 Hz,
2H), 7.82 (q, J = 4.5 Hz, 1H), 7.46 (s, 1H), 7.45 (s, 1H),
7.27 (t, J = 9.0 Hz, 2H), 3.88 (br. s, 4H), 2.98 (t, J = 7.5
Hz, 2H), 2.86 (br. s, 4H), 2.59 (d, J = 4.5 Hz, 3H), 2.54 ppm
(t, J = 7.5 Hz, 2H); HRMS-ESI m/z [M + H]+ calcd for
C25H26FN6O3S: 509.1766, found: 509.1768.
= 165.24, 162.12, 161.71 (d, 1 J
= 243.4 Hz), 153.22,
δ
C−F
151.21, 149.04, 140.22, 137.36, 130.87 (d, 4 JC−F = 2.6 Hz),
130.75, 128.09 (d, 3 JC−F = 8.0 Hz), 126.14, 123.31, 115.37
(d, 2 JC−F = 21.3 Hz), 104.87, 101.37, 62.07, 38.49, 36.94,
123

Mol Divers
33.74, 29.16, 25.50, 24.99 ppm; HRMS-ESI m/z [M + H]+
DMSO-d6): = 163.22, 161.85, 154.78, 149.47, 149.09,
δ
calcd for C27H30FN6O2S: 521.2130, found: 521.2128.
145.92, 141.95, 134.63, 133.52, 132.77, 132.74, 130.66,
128.77, 128.32, 128.18, 127.49, 126.85, 126.49, 125.87,
125.55, 125.46, 117.91, 114.23, 109.96, 101.53, 39.45, 25.70
ppm; HRMS-ESI m/z [M + H]+ calcd for C30H25N6O2S:
533.1754, found: 533.1756.
N-methyl-7-(methyl(phenyl)amino)-3-oxo-6-((4-
phenylthiazol-2-yl)amino)-3,4-dihydroquinoxaline-2-
carboxamide (37)
Following general procedure E starting from 30g (76 mg, 0.2
mmol) and 2-bromo-1-phenylethanone (48 mg, 0.24 mmol)
yielded an orange powder (79 mg, 82%); mp: 171−173 ◦C;
N,N-dimethyl-7-(methyl(phenyl)amino)-6-((4-(naphthalen-
1-yl)thiazol-2-yl)amino)-3-oxo-3,4-dihydroquinoxaline-2-
carboxamide (40)
1H NMR (300 MHz, DMSO-d6): = 13.31 (s, 1H), 10.28
δ
(s, 1H), 9.06 (q, J = 4.8 Hz, 1H), 8.95 (s, 1H), 8.14 (d, J
= 7.5 Hz, 2H), 7.57 (s, 1H), 7.51–7.46 (m, 3H), 7.36 (t, J
= 7.5 Hz, 1H), 7.19 (t, J = 7.8 Hz, 2H), 6.76 (t, J = 7.5
Hz, 1H), 6.66 (d, J = 8.1 Hz, 2H), 3.17 (s, 3H), 2.82 ppm
Following general procedure E starting from 30h (79 mg, 0.2
mmol) and 2-bromo-1-(naphthalen-1-yl)ethanone (60 mg,
0.24 mmol) yielded a dark-yellow powder (81 mg, 74%);
mp:162−164 ◦C;1HNMR(300MHz, DMSO-d6): =12.85
δ
(d, J = 4.8 Hz, 3H); 13C NMR (150 MHz, DMSO-d6):
(s, 1H), 10.19 (s, 1H), 8.73 (s, 1H), 8.42–8.39 (m, 1H), 8.03–
7.93 (m, 3H), 7.64 (t, J = 7.5 Hz, 1H), 7.60–7.54 (m, 2H),
7.49 (s, 1H), 7.27 (s, 1H), 7.20 (t, J = 7.8 Hz, 2H), 6.76 (t, J
= 7.2 Hz, 1H), 6.68 (d, J = 8.1 Hz, 2H), 3.19 (s, 3H), 2.96 (s,
δ
= 163.27, 162.03, 154.99, 149.96, 149.47, 146.00, 141.81,
134.60, 134.17, 132.80, 128.75, 128.62, 128.17, 127.63,
126.84, 126.09, 117.89, 114.20, 105.77, 101.52, 39.43, 25.73
ppm; HRMS-ESI m/z [M + H]+ calcd for C26H23N6O2S:
483.1598, found: 483.1597.
3H), 2.86 ppm (s, 3H); 13C NMR (150 MHz, DMSO-d6):
δ
= 165.03, 162.00, 153.10, 151.60, 149.43, 149.07, 141.20,
133.96, 133.51, 132.77, 132.28, 130.65, 128.77, 128.31,
128.15, 127.50, 127.47, 126.57, 126.48, 125.85, 125.54,
125.48, 117.76, 114.08, 109.64, 102.20, 39.41, 36.89, 33.70
ppm; HRMS-ESI m/z [M + H]+ calcd for C31H27N6O2S:
547.1911, found: 547.1908.
N,N-dimethyl-7-(methyl(phenyl)amino)-3-oxo-6-((4-
phenylthiazol-2-yl)amino)-3,4-dihydroquinoxaline-2-
carboxamide (38)
Following general procedure E starting from 30h (79
mg, 0.2 mmol) and 2-bromo-1-phenylethanone (48 mg,
0.24 mmol) yielded a dark-yellow powder (73 mg, 74%);
7-(Cyclohexyl(methyl)amino)-N,N-dimethyl-3-oxo-6-((4-
phenylthiazol-2-yl)amino)-3,4-dihydroquinoxaline-2-
carboxamide (41)
mp:165−167 ◦C;1HNMR(300MHz, DMSO-d6): =13.17
δ
(s, 1H), 10.19 (s, 1H), 8.94 (s, 1H), 8.13 (d, J = 7.5 Hz, 2H),
7.51–7.46 (m, 4H), 7.35 (t, J = 7.2 Hz, 1H), 7.18 (t, J =
7.8 Hz, 2H), 6.75 (t, J = 7.2 Hz, 1H), 6.66 (d, J = 8.1 Hz,
2H), 3.17 (s, 3H), 2.98 (s, 3H), 2.90 ppm (s, 3H); 13C NMR
Following general procedure E starting from 30f (80 mg, 0.2
mmol) and 2-bromo-1-phenylethanone (48 mg, 0.24 mmol)
yielded an orange powder (86 mg, 86%); mp: 165−167 ◦C;
(150 MHz, DMSO-d6): = 165.06, 162.16, 153.34, 151.59,
1H NMR (300 MHz, DMSO-d6): = 13.02 (s, 1H), 9.84
δ
δ
149.89, 149.45, 141.08, 134.21, 133.92, 132.30, 128.76,
128.60, 127.60, 127.50, 126.57, 126.09, 117.74, 114.06,
105.46, 102.18, 36.92, 33.72ppm;HRMS-ESIm/z [M+H]+
calcd for C27H25N6O2S: 497.1754, found: 497.1752.
(s, 1H), 8.65 (s, 1H), 8.11 (d, J = 7.2 Hz, 2H), 7.60 (s,
1H), 7.51 (s, 1H), 7.47 (t, J = 7.8 Hz, 2H), 7.35 (t, J =
7.5 Hz, 1H), 3.00 (s, 3H), 2.91 (s, 3H), 2.78–2.71 (m, 1H),
2.67 (s, 3H), 1.91–1.87 (m, 2H), 1.72–1.68 (m, 2H), 1.55–
1.52 (m, 1H), 1.33–1.03 ppm (m, 5H); 13C NMR (150 MHz,
N-methyl-7-(methyl(phenyl)amino)-6-((4-(naphthalen-1-
yl)thiazol-2-yl)amino)-3-oxo-3,4-dihydroquinoxaline-2-
carboxamide (39)
DMSO-d6): = 165.23, 161.96, 153.21, 151.18, 150.13,
δ
140.22, 137.31, 134.21, 130.77, 128.58, 127.62, 126.11,
126.04, 123.28, 105.10, 101.33, 62.06, 38.46, 36.92, 33.73,
29.15, 25.49, 24.98 ppm; HRMS-ESI m/z [M + H]+ calcd
for C27H31N6O2S: 503.2224, found: 503.2223.
Following general procedure E starting from 30g (76 mg, 0.2
mmol) and 2-bromo-1-(naphthalen-1-yl)ethanone (60 mg,
0.24 mmol) yielded a dark-yellow powder (78 mg, 73%);
7-(Cyclohexyl(methyl)amino)-6-((4-(2-
fluorophenyl)thiazol-2-yl)amino)-N,N-dimethyl-3-oxo-3,4-
dihydroquinoxaline-2-carboxamide (42)
mp:282−284 ◦C;1HNMR(300MHz, DMSO-d6): =13.00
δ
(s, 1H), 10.28 (s, 1H), 9.03 (q, J = 4.8 Hz, 1H), 8.75 (s, 1H),
8.41–8.38 (m, 1H), 8.03–7.94 (m, 3H), 7.64 (t, J = 7.5 Hz,
1H), 7.60–7.54 (m, 3H), 7.29 (s, 1H), 7.21 (t, J = 7.8 Hz,
2H), 6.77 (t, J = 7.2 Hz, 1H), 6.69 (d, J = 8.1 Hz, 2H), 3.20
(s, 3H), 2.79 ppm (d, J = 4.8 Hz, 3H); 13C NMR (150 MHz,
Following general procedure E starting from 30f (80 mg,
0.2mmol)and2-bromo-1-(2-fluorophenyl)ethanone(52mg,
0.24 mmol) yielded a dark-yellow powder (76 mg, 73%);
123

Mol Divers
mp:153−155 ◦C;1HNMR(300MHz, DMSO-d6): =13.02
6-((4-(3-Chloro-4-fluorophenyl)thiazol-2-yl)amino)-7-
(cyclohexyl(methyl)amino)-N,N-dimethyl-3-oxo-3,4-
dihydroquinoxaline-2-carboxamide (45)
δ
(s, 1H), 9.89 (s, 1H), 8.61 (s, 1H), 8.49–8.43 (m, 1H), 7.60
(s, 1H), 7.42–7.28 (m, 4H), 3.00 (s, 3H), 2.91 (s, 3H), 2.77–
2.70 (m, 1H), 2.67 (s, 3H), 1.91–1.87 (m, 2H), 1.72–1.68
(m, 2H), 1.55–1.52 (m, 1H), 1.33–1.02 ppm (m, 5H); 13C
Following general procedure E starting from 30f (80 mg, 0.2
mmol) and 2-bromo-1-(3-chloro-4-fluorophenyl)ethanone
(60 mg, 0.24 mmol) yielded a dark-yellow powder (78 mg,
70%); mp: 164−166 ◦C; 1H NMR (300 MHz, DMSO-d6):
NMR (150 MHz, DMSO-d6): = 165.21, 161.40, 159.60 (d,
δ
1 JC−F = 247.4 Hz), 153.20, 151.27, 143.67, 140.14, 137.42,
4
3
130.70, 130.42 (d, JC−F = 2.4 Hz), 129.14 (d, JC−F
=
3
8.4 Hz), 126.18, 124.83, 123.30, 121.74 (d, JC−F = 10.5
Hz), 115.80 (d, 2 JC−F = 22.2 Hz), 109.91 (d, 2 JC−F = 15.9
Hz), 101.41, 62.05, 38.40, 36.92, 33.73, 29.13, 25.49, 24.99
ppm; HRMS-ESI m/z [M + H]+ calcd for C27H30FN6O2S:
521.2129, found: 521.2131.
= 13.03 (s, 1H), 9.89 (s, 1H), 8.60 (s, 1H), 8.24–7.97
δ
(m, 2H), 7.64 (s, 1H), 7.59 (s, 1H), 7.49 (t, J = 9.0 Hz,
1H), 3.00 (s, 3H), 2.91 (s, 3H), 2.77–2.70 (m, 1H), 2.66 (s,
3H), 1.90–1.86 (m, 2H), 1.71–1.68 (m, 2H), 1.55–1.52 (m,
1H), 1.32–1.02 ppm (m, 5H); 13C NMR (150 MHz, DMSO-
1
d6): = 165.21, 162.35, 156.61 (d, JC−F = 245.8 Hz),
δ
4
153.16, 151.30, 147.68, 140.08, 137.45, 132.16 (d, JC−F
3
= 3.2 Hz), 130.68, 127.50, 126.82 (d, JC−F = 7.0 Hz),
2
7-(Cyclohexyl(methyl)amino)-6-((4-(3-
fluorophenyl)thiazol-2-yl)amino)-N,N-dimethyl-3-oxo-3,4-
dihydroquinoxaline-2-carboxamide (43)
126.22, 123.26, 119.85 (d, JC−F = 17.7 Hz), 117.00 (d,
2 JC−F = 20.8 Hz), 106.41, 101.47, 62.03, 38.38, 36.92,
33.73, 29.12, 25.49, 25.00 ppm; HRMS-ESI m/z [M + H]+
calcd for C27H29ClFN6O2S: 555.1740, found: 555.1741.
Following general procedure E starting from 30f (80 mg,
0.2mmol)and2-bromo-1-(3-fluorophenyl)ethanone(52mg,
0.24 mmol) yielded a dark-yellow powder (88 mg, 85%);
7-(Cyclohexyl(methyl)amino)-6-((4-(2,4-dichloro-5-
fluorophenyl)thiazol-2-yl)amino)-N,N-dimethyl-3-oxo-3,4-
dihydroquinoxaline-2-carboxamide (46)
mp:155−157 ◦C;1HNMR(300MHz, DMSO-d6): =13.05
δ
(s, 1H), 9.88 (s, 1H), 8.63 (s, 1H), 7.97–7.89 (m, 2H), 7.63 (s,
1H), 7.60 (s, 1H), 7.54–7.47 (m, 1H), 7.17 (td, J = 8.7 Hz, 2.1
Hz, 1H), 3.00 (s, 3H), 2.91 (s, 3H), 2.77–2.70 (m, 1H), 2.66
(s, 3H), 1.91–1.87 (m, 2H), 1.72–1.68 (m, 2H), 1.55–1.52
(m, 1H), 1.32–1.02 ppm (m, 5H); HRMS-ESI m/z [M+H]+
calcd for C27H30FN6O2S: 521.2129, found: 521.2130.
Following general procedure E starting from 30f (80 mg, 0.2
mmol) and 2-bromo-1-(2,4-dichloro-5-fluorophenyl)ethan-
one (69 mg, 0.24 mmol) yielded a dark-yellow powder (102
mg, 87%); mp: 157−159 ◦C; 1H NMR (300 MHz, DMSO-
d6): = 12.96 (s, 1H), 9.92 (s, 1H), 8.47 (s, 1H), 8.17 (d, J =
δ
10.5 Hz, 1H), 7.93 (d, J = 6.9 Hz, 1H), 7.76 (s, 1H), 7.58 (s,
1H), 3.00 (s, 3H), 2.90 (s, 3H), 2.76–2.70 (m, 1H), 2.66 (s,
3H), 1.90–1.86 (m, 2H), 1.71–1.68 (m, 2H), 1.55–1.52 (m,
7-(Cyclohexyl(methyl)amino)-6-((4-(3,5-
difluorophenyl)thiazol-2-yl)amino)-N,N-dimethyl-3-oxo-
3,4-dihydroquinoxaline-2-carboxamide (44)
1H), 1.33–1.02 ppm (m, 5H); 13C NMR (150 MHz, DMSO-
1
d6): = 165.18, 161.46, 156.14 (d, JC−F = 245.2 Hz),
δ
153.09, 151.39, 144.13, 139.95, 137.59, 133.15 (d, 3 JC−F
=
7.2 Hz), 131.76, 130.57, 126.30, 126.13 (d, 4 JC−F = 2.6 Hz),
2
2
Following general procedure E starting from 30f (80 mg,
0.2 mmol) and 2-bromo-1-(3,5-difluorophenyl) ethanone (56
mg, 0.24mmol)yieldedadark-yellowpowder(87mg, 81%);
123.20, 119.14 (d, JC−F = 19.2 Hz), 118.70 (d, JC−F
=
23.7 Hz), 112.18, 101.58, 61.98, 38.20, 36.91, 33.72, 29.06,
25.50, 25.02 ppm; HRMS-ESI m/z [M + H]+ calcd for
C27H28Cl2FN6O2S: 589.1350, found: 589.1349.
mp:261−263 ◦C;1HNMR(300MHz, DMSO-d6): =13.08
δ
(s, 1H), 9.92 (s, 1H), 8.61 (s, 1H), 7.81 (dd, J = 8.7 Hz, 1.8
Hz, 2H), 7.75 (s, 1H), 7.60 (s, 1H), 7.20 (tt, J = 9.3 Hz, 1.8
Hz, 1H), 3.00 (s, 3H), 2.91 (s, 3H), 2.77–2.70 (m, 1H), 2.66
(s, 3H), 1.90–1.87 (m, 2H), 1.71–1.68 (m, 2H), 1.55–1.51 (m,
1H), 1.32–1.02 ppm (m, 5H); 13C NMR (150 MHz, DMSO-
7-(Cyclohexyl(methyl)amino)-N,N-dimethyl-3-oxo-6-((4-
(2,4,6-trifluorophenyl)thiazol-2-yl)amino)-3,4-
dihydroquinoxaline-2-carboxamide (47)
d6): = 165.21, 162.80 (dd, 1,3 JC−F = 243.4 Hz, 13.6 Hz),
Following general procedure E starting from 30f (80 mg,
0.2 mmol) and 2-bromo-1-(2,4,6-trifluorophenyl)ethanone
(61 mg, 0.24 mmol) yielded a dark-yellow powder (90 mg,
81%); mp: 234−235 ◦C; 1H NMR (300 MHz, DMSO-d6):
δ
3
162.31, 153.16, 151.34, 147.83, 140.01, 137.71 (t, JC−F
= 10.2 Hz), 137.46, 130.67, 126.24, 123.28, 108.88 (dd,
2,4
J
C−F
= 20.7 Hz, 5.2 Hz), 108.12, 102.78 (t, 2 JC−F = 25.8
Hz), 101.58, 62.05, 38.40, 36.92, 33.73, 29.11, 25.49, 25.00
ppm; HRMS-ESI m/z [M+H]+ calcd for C27H29F2N6O2S:
539.2035, found: 539.2034.
= 12.70 (s, 1H), 9.84 (s, 1H), 8.37 (s, 1H), 7.58 (s, 1H),
δ
7.33 (t, J = 8.7 Hz, 2H), 7.29 (s, 1H), 2.98 (s, 3H), 2.88 (s,
3H), 2.78–2.71 (m, 1H), 2.66 (s, 3H), 1.90–1.86 (m, 2H),
123

Mol Divers
1.72–1.68 (m, 2H), 1.56–1.52 (m, 1H), 1.33–1.03 ppm (m,
5H); HRMS-ESI m/z [M + H]+ calcd for C27H28F3N6O2S:
557.1941, found: 557.1939.
3H), 1.79–1.70 (m, 4H), 1.56–1.52 (m, 1H), 1.40–1.07 ppm
(m, 5H); HRMS-ESI m/z [M + H]+ calcd for C19H28N5O2:
358.2238, found: 358.2238.
6-((4-(4-Cyanophenyl)thiazol-2-yl)amino)-7-
(cyclohexyl(methyl)amino)-N,N-dimethyl-3-oxo-3,4-
dihydroquinoxaline-2-carboxamide (48)
7-(Cyclohexyl(methyl)amino)-N,N,4-trimethyl-3-oxo-6-
thioureido-3,4-dihydroquinoxaline-2-carboxamide (52)
Following general procedure D starting from 50 (714 mg, 2.0
mmol) yielded a dark-yellow powder (632 mg, 76% over two
steps); mp: 192−194 ◦C; 1H NMR (300 MHz, DMSO-d6):
Following general procedure E starting from 30f (80 mg,
0.2 mmol) and 4-(2-bromoacetyl)benzonitrile (54 mg, 0.24
mmol) yielded an orange powder (80 mg, 76%); mp:
= 9.32 (s, 1H), 8.76 (s, 1H), 8.15 (s, 2H), 7.56 (s, 1H), 3.58
δ
1
249−251 ◦C; H NMR (300 MHz, DMSO-d6): = 13.07
(s, 3H), 2.99 (s, 3H), 2.87 (s, 3H), 2.73–2.67 (m, 1H), 2.65 (s,
3H), 1.83–1.70 (m, 4H), 1.56–1.53 (m, 1H), 1.36–1.02 ppm
(m, 5H); HRMS-ESI m/z [M+H]+ calcd for C20H29N6O2S:
417.2067, found: 417.2066.
δ
(s, 1H), 9.98 (s, 1H), 8.68 (s, 1H), 8.31 (d, J = 8.7 Hz,
2H), 7.92 (d, J = 8.7 Hz, 2H), 7.81 (s, 1H), 7.60 (s, 1H),
3.00 (s, 3H), 2.91 (s, 3H), 2.77–2.70 (m, 1H), 2.66 (s, 3H),
1.91–1.87 (m, 2H), 1.71–1.68 (m, 2H), 1.55–1.52 (m, 1H),
1.32–1.02 ppm (m, 5H); 13C NMR (150 MHz, DMSO-d6):
7-(Cyclohexyl(methyl)amino)-6-((4-(4-
= 165.20, 162.41, 153.21, 151.34, 148.27, 140.10, 138.33,
fluorophenyl)thiazol-2-yl)amino)-N,N,4-trimethyl-3-oxo-
3,4-dihydroquinoxaline-2-carboxamide (53)
δ
137.45, 132.60, 130.67, 126.64, 126.22, 123.35, 119.06,
109.67, 109.07, 101.57, 62.08, 38.51, 36.93, 33.73, 29.13,
25.50, 24.99 ppm; HRMS-ESI m/z [M + H]+ calcd for
C28H30N7O2S: 528.2176, found: 528.2175.
Following general procedure E starting from 52 (83 mg,
0.2 mmol) and 2-bromo-1-(4-fluorophenyl)ethanone (52 mg,
0.24 mmol) yielded a dark-yellow powder (90 mg, 84%);
Ethyl 6-amino-7-(cyclohexyl(methyl)amino)-4-methyl-3-
oxo-3,4-dihydroquinoxaline-2-carboxylate (49)
mp:223−224 ◦C;1HNMR(300MHz, DMSO-d6): =10.02
δ
(s, 1H), 8.97 (s, 1H), 8.03 (dd, J = 8.7 Hz, 5.7 Hz, 2H), 7.65
(s, 1H), 7.51 (s, 1H), 7.31 (t, J = 8.7 Hz, 2H), 3.73 (s, 3H),
3.01 (s, 3H), 2.89 (s, 3H), 2.81–2.74 (m, 1H), 2.68 (s, 3H),
1.92–1.88 (m, 2H), 1.72–1.68 (m, 2H), 1.55–1.52 (m, 1H),
1.34–1.03 ppm (m, 5H); 13C NMR (150 MHz, DMSO-d6):
To a stirred solution of intermediate 5d (2.75 g, 8.0 mmol)
in acetone (150 mL) was added K2CO3 (1.66 g, 12 mmol)
and methyl iodide (0.60 mL, 9.6 mmol), and the mixture
was stirred at 50 ◦C for 6 h. The suspension was cooled and
filtered. Then, the filtrate was concentrated under reduced
pressure. The residue was dissolved in saturated ammo-
nium chloride solution (100 mL) and extracted by CH2Cl2
(2 × 100 mL). The organic phases were combined, dried
over anhydrous Na2SO4, and evaporated in vacuo to give
a dark-yellow solid residue, which was purified by silica
gel column chromatography (CH2Cl2/MeOH, 80:1) to give
the title compound as a dark-yellow powder (2.21 g, 77%);
= 165.16, 162.33, 161.66 (d, 1 J
= 243.4 Hz), 152.38,
δ
C−F
149.76, 148.59, 140.46, 137.27, 131.78, 130.96, 127.51 (d,
3 JC−F = 8.0 Hz), 126.46, 124.05, 115.63 (d, 2 JC−F = 21.4
Hz), 105.12, 101.15, 61.94, 38.36, 36.94, 33.72, 29.10, 28.92,
25.50, 24.99 ppm; HRMS-ESI m/z [M + H]+ calcd for
C28H32FN6O2S: 535.2286, found: 535.2286.
Biology
mp: 187−188 ◦C; 1H NMR (300 MHz, DMSO-d6): = 7.32
HCV antiviral assay The Huh7-ET (luc-ubi-neo/ET) cell
line which harbors a dicistronic self-replicating HCV RNA
replicon with a firefly luciferase gene was used for antivi-
ral evaluation [51]. The activity of the luciferase reporter is
directly proportional to HCV RNA levels. Briefly, the ET
cells were cultured in Dulbecco’s modified Eagle’s medium
(DMEM), supplemented with 2 mM L-glutamine, nonessen-
tial amino acids, 10% fetal bovine serum (FBS), and 0.25
mg/mL G418 (Invitrogen, Carlsbad, CA). The cells were
seeded in two identical sets of 96-well plates used for analysis
of antiviral activity or cell numbers (cytotoxicity) at a density
of 5000/well in 100 μL of DMEM without G418 overnight.
Serial dilutions of compounds solubilized in DMSO were
prepared in DMEM and then added to the appropriate wells.
After 72 h of incubation, one set of the cells was processed
δ
(s, 1H), 6.62 (s, 1H), 6.20 (s, 2H), 4.28 (q, J = 7.2 Hz, 2H),
3.50 (s, 3H), 2.78–2.71 (m, 1H), 2.59 (s, 3H), 1.79–1.70 (m,
4H), 1.56–1.52 (m, 1H), 1.40–1.05 ppm (m, 8H); HRMS-
ESI m/z [M+H]+ calcd for C19H27N4O3: 359.2078, found:
359.2077.
6-Amino-7-(cyclohexyl(methyl)amino)-N,N,4-trimethyl-3-
oxo-3,4-dihydroquinoxaline-2-carboxamide (50)
Following general procedure G starting from carboxylic acid
type of 49 (991 mg, 3.0 mmol) yielded a yellow powder (890
mg, 83%); mp: 215−216 ◦C; 1H NMR (300 MHz, DMSO-
d6): = 7.29 (s, 1H), 6.66 (s, 1H), 5.91 (s, 2H), 3.51 (s,
δ
3H), 2.97 (s, 3H), 2.84 (s, 3H), 2.78–2.71 (m, 1H), 2.58 (s,
123

Mol Divers
to assess the replicon-derived luciferase activity with the
Steady-Glo luciferase assay system (Promega, Madison,
WI) according to manufacturer’s instruction. Another set
of the plates was used to determine cytotoxic effect of the
compounds using a tetrazolium-based CytoTox-1 cell pro-
liferation assay (Promega, Madison WI). Each data point
represents an average of four replicates to derive EC50
(concentration of compound to inhibit HCV RNA replica-
tion activity by 50%), CC50 (concentration of compound to
decrease cell viability by 50%), and SI50 (selective index
calculated as the CC50/EC50 ratio) values.
14. Poordad F, McCone J Jr, Bacon BR, Bruno S, Manns MP,
Sulkowski MS, Jacobson IM, Reddy KR, Goodman ZD, Boparai N,
DiNubile MJ, Sniukiene V, Brass CA, Albrecht JK, Bronowicki JP
(2011) Boceprevir for untreated chronic HCV genotype 1 infection.
N Engl J Med 364:1195–1206. doi:10.1056/NEJMoa1010494
15. Bacon BR, Gordon SC, Lawitz E, Marcellin P, Vierling JM,
Zeuzem S, Poordad F, Goodman ZD, Sings HL, Boparai N, Bur-
roughs M, Brass CA, Albrecht JK, Esteban R (2011) Boceprevir
for previously treated chronic HCV genotype 1 infection. N Engl
J Med 364:1207–1217. doi:10.1056/NEJMoa1009482
16. Malcolm BA, Liu R, Lahser F, Agrawal S, Belanger B, Butkiewicz
N, Chase R, Gheyas F, Hart A, Hesk D, Ingravallo P, Jiang C, Kong
R, Lu J, Pichardo J, Prongay A, Skelton A, Tong X, Venkatraman
S, Xia E, Girijavallabhan V, Njoroge FG (2006) SCH 503034, a
mechanism-based inhibitor of hepatitis C virus NS3 protease, sup-
presses polyprotein maturation and enhances the antiviral activity
of alpha interferon in replicon cells. Antimicrob Agents Chemother
50:1013–1020. doi:10.1128/AAC.50.3.1013-1020.2006
17. Perni RB, Almquist SJ, Byrn RA, Chandorkar G, Chaturvedi PR,
Courtney LF, Decker CJ, Dinehart K, Gates CA, Harbeson SL,
Heiser A, Kalkeri G, Kolaczkowski E, Lin K, Luong YP, Rao BG,
Taylor WP, Thomson JA, Tung RD, Wei Y, Kwong AD, Lin C
(2006) Preclinical profile of VX-950, a potent, selective, and orally
bioavailable inhibitor of hepatitis C virus NS3-4A serine protease.
Antimicrob Agents Chemother 50:899–909. doi:10.1128/AAC.50.
3.899-909.2006
18. McHutchison JG, Everson GT, Gordon SC, Jacobson IM,
Sulkowski M, Kauffman R, McNair L, Alam J, Muir AJ (2009)
Telaprevir with peginterferon and ribavirin for chronic HCV geno-
type 1 infection. N Engl J Med 360:1827–1838. doi:10.1056/
NEJMoa0806104
19. Hézode C, Forestier N, Dusheiko G, Ferenci P, Pol S, Goeser
T, Bronowicki JP, Bourlière M, Gharakhanian S, Bengtsson L,
McNair L, George S, Kieffer T, Kwong A, Kauffman RS, Alam
J, Pawlotsky JM, Zeuzem S (2009) Telaprevir and peginterferon
with or without ribavirin for chronic HCV infection. N Engl J Med
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Acknowledgments This work was supported financially by the
National Natural Science Foundation of China (No. 90713045). We
gratefully acknowledge Dr. Zhuhui Huang and Dr. Michael G. Murray
(Southern Research Institute, 431 Aviation Way, Frederick, Maryland
21701, United States) for their assistance of screening our compounds.
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