Synthesis of 2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential Anti-Folate Agents

Article abstract of DOI:10.1002/jhet.2474

Anti-folate agents had a significant impact on therapeutic treatment plans for diseases such as cancer, and bacterial and parasitic infections, notably malaria. Quinoxaline derivatives showed in vitro anticancer activity and were able to inhibit both the dihydrofolate reductase and thymidylate synthase. Here, we decided to combine the chemical properties of quinoxalines and quinoxaline 1,4-dioxides with those of benzotriazole nucleus with the aim to evaluate the resulting biological properties. Two main new series, including more than 60 compounds, were prepared. In the first one, the benzotriazole moiety was linked through the nitrogen atoms 1, 2, or 3, to a glutaric acid substituent to simulate a glutamic moiety. In the second series, the glutaric acid was substituted with acetic acid moiety to evaluate the effects of steric hindrance. Here, we describe the multistep chemical processes to obtain all titled quinoxalines starting from commercially available diamines. The classical oxidation of selected quinoxalines was unsuccessful, and we have come to an independent synthetic pathway to obtain new derivatives linked to the benzotriazole moieties starting from synthons bearing N-oxide functionality.

Full text of DOI:10.1002/jhet.2474

Month 2015
Synthesis of 2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic
Derivatives as Potential Anti-Folate Agents
*
I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Department of Chemistry and Pharmacy, University of Sassari, Via Muroni 23a, 07100 Sassari, Italy
*
E-mail: ibriguglio@uniss.it
Received December 11, 2014
DOI 10.1002/jhet.2474
Published online 00 Month 2015 in Wiley Online Library (wileyonlinelibrary.com).
Anti-folate agents had a significant impact on therapeutic treatment plans for diseases such as cancer, and
bacterial and parasitic infections, notably malaria. Quinoxaline derivatives showed in vitro anticancer activ-
ity and were able to inhibit both the dihydrofolate reductase and thymidylate synthase. Here, we decided to
combine the chemical properties of quinoxalines and quinoxaline 1,4-dioxides with those of benzotriazole
nucleus with the aim to evaluate the resulting biological properties. Two main new series, including more
than 60 compounds, were prepared. In the first one, the benzotriazole moiety was linked through the nitrogen
atoms 1, 2, or 3, to a glutaric acid substituent to simulate a glutamic moiety. In the second series, the glutaric
acid was substituted with acetic acid moiety to evaluate the effects of steric hindrance. Here, we describe the
multistep chemical processes to obtain all titled quinoxalines starting from commercially available diamines.
The classical oxidation of selected quinoxalines was unsuccessful, and we have come to an independent syn-
thetic pathway to obtain new derivatives linked to the benzotriazole moieties starting from synthons bearing
N-oxide functionality.
J. Heterocyclic Chem., 00, 00 (2015).
INTRODUCTION
quinoxaline (II) [15] or, in addition, eliminating the
glutaric acid moiety (III) [16].
Numerous quinoxaline derivatives were synthesized in
the last decades. They showed significant biological
activities [1,2]. Numerous synthetic pathways have been
developed in the past for the synthesis of quinoxaline de-
rivatives of anticancer, anti-infective, and veterinarian
interest [3–14]. Interesting is the potential anti-folate activ-
ity reported for some of them. Figure 1 shows the chemical
structures of folic acid (I) and the first two attempts to build
its analogs by replacing the pteridin nucleus with the
After these first attempts, many other bioisosteric mole-
cules of the folic acid were synthesized. These compounds
were able to inhibit the two most important folate enzymes:
the dihydrofolate reductase (DHFR) and the thymidylate
synthase (TS). From them emerged methotrexate and
tomudex, currently among the most effective and com-
monly used drugs in therapy. Their structures are depicted
in Figure 2. Subsequent research based on these two
models allowed the synthesis of a new analogue, the
© 2015 HeteroCorporation

I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Vol 000
Figure 1. Chemical structures of the folic acid (I) and its analogs (II and III).
Figure 2. Chemical structures of the most commonly used anticancer drugs.
trimetrexate. All three derivatives were devoid of the
quinoxaline scaffold, as shown in Figure 2.
showed in vitro anticancer activity, were able to inhibit ei-
ther DHFR or TS [27,31,33–35].
Furthermore, in the last 60 years, new drugs targeting the
folate pathway had a significant impact on therapeutic
treatment plans for cancer [17], bacterial infections [18],
and certain parasitic diseases, notably malaria [19]. Based
on these premises, in an attempt to investigate the potential
of the quinoxaline derivatives as anti-folate agents, our re-
search group synthesized and tested hundreds of new mol-
ecules. We reported the anticancer activity data concerning
a wide amount of different quinoxaline series [20–37], and
among these, the most interesting compounds were se-
lected for in depth in vivo investigations [21,23,24,28]. In
Figure 3 are summarized the chemical structures of all
the compounds synthesized with the purpose to identify
potent and selective inhibitors. Through these studies, we
have demonstrated that several of these compounds, which
Furthermore, it was known that the quinoxaline
1,4-dioxides have significant biological activities and
therapeutic applications in various fields [1]. In particular,
we reported the synthesis, and anti-mycobacterial, anti-
trichomonas, and anti-Candida activities of various
2,3,6,7-substituted-quinoxaline 1,4-dioxides [38,39].
In addition, even 1H-benzo[d][1,2,3]triazole (BT) and
its derivatives have been widely investigated, highlighting
their versatile biological properties, the mode of action,
and structure–activity relationship [40], particularly as an-
tiproliferative agents [41–43].
Here, we decided to combine chemical and biological
properties of quinoxalines and quinoxaline 1,4-dioxides
with those of BT. In the first two series (compounds IV
and V, Fig. 4) at the BT moiety, we linked, on the 1, 2,
Figure 3. Chemical structures of previously synthesized quinoxaline derivatives as anti-folate agents.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential
Anti-Folate Agents
On this basis, all newly synthesized compounds have
been assayed to evaluate their antiproliferative activity.
Evaluation of the anticancer activity of the synthesized
quinoxaline (15–25) and 1,4 dioxide-quinoxaline (28–33)
derivatives was performed at the National Cancer Institute,
Bethesda USA (NCI). Among the synthesized compounds,
only 15 were accepted by NCI after a preliminary screen.
First, all quinoxaline derivatives were evaluated in primary
anticancer assay at 10À4 M concentration against NCI-H460
(lung), MCF7 (breast), and SF-268 (CNS) cell lines. In the
assay protocol, each cell line was inoculated and preincu-
bated on a microtiter plate. Test agents were added in a single
concentration (10À4 M), and the culture was incubated for
48h. End-point determinations were made with alamar blue.
For the NCI criteria, compounds that reduce the growth
of anyone of the cancer cell lines to 32% or less (negative
numbers indicate cell kill) are identified as “active” and
subsequently are evaluated in a full panel of 60 human cell
lines over a 5-log dose range.
Figure 4. Chemical structures of diethyl 2-(6-(quinoxalin-2-ylamino)-1/2/
3H-benzo[d][1,2,3]triazol-1/2/3-yl)pentanedioate (IV) and diethyl 2-(6-
((1,4-dioxide-quinoxalin-2-yl)amino)-1/2/3H-benzo[d][1,2,3]triazol-1/
2/3-yl)pentanedioate (V) derivatives.
or 3 nitrogen atoms, a glutaric substituent to simulate the
glutamic acid.
In the second series (compounds VI and VII, Fig. 5), the
glutaric acid was substituted with acetic acid to evaluate
the decreased steric hindrance.
The quinoxaline derivatives (15d,e, 16e, and 17e) and 1,4
dioxide-quinoxaline derivatives (31c–e, 32c–e, and 33c–e)
matched these criteria and were evaluated for their anticancer
activity following the known in vitro disease-oriented anti-
tumor screening program that is based upon use of multiple
panels of 60 human cancer cell lines [44]. A 48h drug expo-
sure protocol was used, and a sulforhodamine B protein as-
say was employed to estimate cell viability or growth [45].
The anticancer activity of a tested compound is given by
three parameters for each cell line: log10 GI50 value
(GI50 =molar concentration of the compound that inhibits
50% net cell growth), log10 TGI value (TGI=molar concen-
tration of the compound leading to total inhibition of net cell
growth), and log10 LC50 value (LC50=molar concentration
of the compound leading to 50% net cell death). Further-
more, a mean graph midpoint (MG-MID) is calculated for
each of the mentioned parameters, giving an averaged activ-
ity of each compound deduced from dose response curves.
The log10 GI50, log10 TGI, and log10 LC50 values
provided by NCI for selected compounds 15d,e, 16e,
17e, 31c–e, 32c–e, and 32c–e are reported in Table 1,
whereas Tables 2 reports the results of percent growth inhi-
bition (I%) recorded at 10À4 M concentration.
In Figure 6, we reported the simulated overlap of our
most representative derivative (yellow) with the folic acid
(green) and methotrexate (pink).
As is clearly visible from the figure, the overlap of the
molecules is almost complete. This observation supports
our hypothesis that our derivatives may show a good abil-
ity inhibiting the folate enzymes and consequently also act
as anticancer agents.
Figure 5. Chemical structures of ethyl 2-(6-(quinoxalin-2-ylamino)-1/2/
3H-benzo[d][1,2,3]triazol-1/2/3-yl)acetate and acid (VI) and ethyl 2-(6-
((1,4-dioxide-quinoxalin-2-yl)amino)-1/2/3H-benzo[d][1,2,3]triazol-1-yl)
acetate (VII) derivatives.
The data showed that all compounds exhibited moderate
activity against all human tumor cell lines at 0.1 mM. Struc-
tural analysis highlighted how only some [(benzotriazol-
5-yl)amino]quinoxalines (15d and 15–17e) demonstrate
antiproliferative activity. [(benzotriazol-5-yl)amino]1,4
dioxidequinoxalines (28e, 29e, 31c–e, 32c–e, and 33c–e)
resulted more powerful than quinoxaline derivatives. Com-
pounds 32c, 33c, and 33d showed the highest values of
activity (MG-MID, log10, and GI50 are À4.63, À4.39,
and À4.55, respectively) against all cell lines. Particularly,
compound 32c exhibited interesting antiproliferative activ-
ity on 54 of 58 tumor cell lines with I% values ranged
Figure 6. Overlap of the most representative ((quinoxalin-2-yl amino)-
1H-benzotriazol-1-yl)pentanedioate derivative (yellow) with folic acid
(green) and methotrexate (pink). [Color figure can be viewed in the online
issue, which is available at wileyonlinelibrary.com.]
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Vol 000
Table 1
are reported in the Experimental section. They were sub-
sequently subjected to POCl3 chlorination with heating
at 100°C, to give the new chloro-quinoxalines 7a–e, 8,
and 9.
Mean graph midpoint.
Compound
Log GI50
Log TGI
Log LC50
15d
15e
16e
17e
28e
29e
31c
31d
31e
32c
32d
32e
33c
33d
33e
À4.12
À4.19
À4.19
À4.11
À4.20
À4.13
À4.16
À4.20
À4.12
À4.63
À4.17
À4.27
À4.39
À4.55
À4.28
À4.03
À4.05
À4.02
À4.01
À4.02
À4.01
À4.00
À4.00
À4.01
À4.18
À4.00
À4.04
À4.02
À4.17
À4.03
À4.01
À4.00
À4.00
À4.00
À4.00
À4.00
À4.00
À4.00
À4.00
À4.02
À4.00
À4.00
À4.00
À4.03
À4.00
Benzotriazolic synthones 12a–c were in turn synthesized
according to the sequence of reactions depicted in Scheme 2,
utilizing classical diazotization of diamine 2 [46], furnishing
the 5-nitro-benzotriazole 10. The known intermediates 11a–c
were prepared by condensation of ethyl 2-chloroacetate with
5-nitro-benzotriazole 10 in DMF at reflux in the presence of
triethylamine, modifying the method previously described
by Schellhammer et al. [47].
Separation of the isomeric mixtures was performed by
column chromatography, and the structures of the single
1
isomers were assigned on the basis of H- and 13C-NMR
spectroscopy, using the method proposed by Carta [48].
Finally, palladium-catalyzed reduction of aromatic nitro
group to obtain the new amines 12a–c was accomplished
in high yield by introduction of gaseous hydrogen into a
sealed reaction system.
between 182 (melanoma: LOX IMVI) and 61 (colon can-
cer: KM12). Biological data suggest the relevance of 1,4
dioxide function paired with a chlorine substitution on
quinoxaline moiety. Best results are obtained when the
benzotriazole moiety is linked through the nitrogen atom
2 to a glutaric acid substituent.
Sustained by the structural similarities between our se-
lected compounds and methotrexate, and supported by
the reported antiproliferative activities, we can reasonably
deduce that the prepared [(benzotriazol-5-yl)amino]1,4
dioxide-quinoxaline derivatives behave as inhibitors of
the folic acid enzyme complex. More in vitro analyses
are ongoing projects.
Finally, we synthesized the corresponding benzotriazole
derivatives linked to glutaric acid moieties 14a–c to evalu-
ate the steric hindrance relevance of this group. The
synthetic pathway is depicted in Scheme 3. Diethyl
2-bromopentanedioate 15 (which was prepared as reported
in the literature [49,50]) was used to alkylate 5-nitro-
benzotriazole 10 as described earlier, giving rise to iso-
meric mixtures of derivatives 13a–c. After separation
by column chromatography, the single isomers were
assigned using the method proposed by Carta [48]. The
corresponding amines 14a–c were obtained, as earlier,
through Pd/C-catalyzed hydrogenation of the nitro parents
13a–c.
RESULTS AND DISCUSSION
Scheme 4 illustrates the condensation reaction of
chloro-quinoxalines 7a–e with the ethyl 2-(5-amino-1H-
benzo[d][1,2,3]triazolyl)acetates 12a–c. Particularly, con-
densation through aminoderivatives 12a (1-yl) and 12c
(3-yl) and chloro-quinoxalines bearing a carboxylic group
(7e) or a small substituent (7a–c) on the adjacent position
at the chorine atom proceed in good yields. This observa-
tion is justified considering the electron withdrawn effect
in the first case, and the lower steric hindrance in the sec-
ond one. On the contrary, the yields noticeably decrease
in the presence of a phenyl group, due its major steric hin-
drance. Moreover, lower reactivity is observed when the
nucleophile is the aminoderivative 12b (2-yl), which reacts
only in one case, giving the adduct 16e. In fact, the elec-
tronic effects determined by substitution on triazole posi-
tion 2 (2-yl) make the amino group less nucleophilic
[48]. To evaluate the biological activity, selected esters
were easily hydrolyzed in alkaline medium (NaOH 2M,
100°C), obtaining from 15a–b and 17a–b the correspond-
ing isomeric monocarboxylic acids 18a–b and 19a–b, re-
spectively. Moreover, dicarboxylic acids 20–22 were in
All quinoxaline derivatives in the first series were pre-
pared starting from commercially available diamines 1
and 2 as depicted in Scheme 1. Generally, the appropriate
diamine was reacted with adequate α-keto esters or acids
3a–e, in 10% H2SO4 at 60–100°C for 0.5–2 h, obtaining
the quinoxalinones 4a–e, 5, and 6 with good yields
(70–98%), with the sole exception of compound 6 (10%
of yield). Notably, this chemical behavior confirms the pre-
viously observed selectively in the condensation passing
trough substituted o-phenylene-diamines and α-dicarbonyl
intermediates [8]. In fact, in acid solution, the amino group
at position 2 of the 4-nitrobenzene-1,2-diamine (2), more
basic than the other one due to the presence of an electron
withdrawing group (NO2), is protonated and thus posi-
tively charged. This leads to a preferential attack of the
amino group in position 1 on the carboxyl group of the re-
agent (3d), with a favored formation of the quinoxalinone
5 rather than the isomeric derivative 6.
All quinoxalinone intermediates 4a–e, 5, and 6 were
described in literature, and the corresponding references
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential
Anti-Folate Agents
Table 2
Percent tumor growth inhibition recorded on subpanel cell lines at 10À4 M concentration of compounds 15d,e, 16e, 17e, 31c–e, 32c–e, and 33c–e.
Panel cell lines
15d
15e
16e
17e
28e
29e
31c
31d
31e
32c
32d
32e
33c
33d
33e
Leukemia
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
CCRF-CEM
HL-60(TB)
K-562
MOLT-4
RPMI-8226
SR
88
76
61
85
86
64
77
87
83
72
80
93
83
97
109
129
82
91
79
a
a
63
88
74
71
78
72
86
92
77
133
90
a
a
a
a
a
a
a
a
115
73
82
84
93
98
Non-small cell lung cancer
A549/ATCC
EKVX
HOP-62
HOP-92
NCI-H226
NCI-H23
NCI-H322M
NCI-H460
NCI-H522
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
141
152
152
114
136
134
78
67
113
84
82
107
62
98
77
154
109
118
78
94
67
110
101
110
78
101
153
105
81
67
a
a
a
72
62
98
76
105
84
62
95
a
a
140
71
127
118
64
105
93
90
69
59
70
64
61
a
a
a
a
a
a
a
67
87
84
60
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
75
62
83
90
a
a
a
a
a
a
a
a
89
a
67
82
69
180
91
119
74
89
84
73
72
89
143
a
a
a
61
79
Colon cancer
COLO 205
HCC-2998
HCT-116
HT29
KM12
HCT-15
SW-620
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
78
78
92
151
127
97
61
97
95
184
132
98
120
105
108
a
a
a
a
115
72
a
a
66
66
93
66
80
61
a
a
a
a
a
a
71
62
63
73
66
a
a
a
a
a
a
a
a
a
a
a
a
a
65
73
91
89
129
70
a
a
a
a
90
CSN cancer
SF-268
SF-295
SF-539
SNB-19
SNB-75
U251
61
92
89
122
81
167
89
72
70
139
97
163
78
98
81
104
62
80
78
83
79
102
70
76
84
166
99
141
156
155
74
149
83
122
99
176
124
96
85
128
60
96
a
a
a
a
84
84
76
a
a
a
a
a
a
a
a
a
a
a
65
60
81
166
123
a
a
a
a
a
a
a
a
a
a
102
a
a
100
141
89
74
62
68
a
a
91
80
149
69
Melanoma
LOX IMVI
MALME-3M
M14
SK-MEL-2
SK-MEL-5
UACC-257
UACC-62
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
69
60
182
89
95
63
98
173
173
161
95
85
64
93
72
a
a
a
a
78
a
a
a
a
a
a
a
a
a
71
83
88
85
175
94
a
71
82
98
122
67
129
a
a
a
a
a
a
71
82
64
a
a
a
a
a
a
69
116
99
192
175
163
155
a
60
61
84
Ovarian cancer
IGROVI
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
78
97
91
91
119
148
82
97
82
68
79
63
111
180
162
74
73
120
OVCAR-3
OVCAR-4
OVCAR-5
OVCAR-8
SK-OV-3
78
72
82
84
a
a
a
78
61
76
84
a
a
a
a
a
a
a
a
a
a
63
a
a
a
a
a
64
82
92
131
a
a
a
63
90
67
Renal cancer
786-0
A498
a
a
a
a
a
a
a
a
a
a
a
90
77
94
77
91
64
84
176
133
181
85
187
139
95
116
73
82
70
a
a
a
a
a
a
a
a
64
a
a
a
a
a
a
a
ACHN
91
104
62
64
70
65
75
97
72
96
70
59
76
89
90
125
120
57
70
60
76
a
a
a
a
a
a
CAKI-1
RXF 393
SN12C
TK-10
60
117
130
89
100
136
65
65
147
86
154
a
a
a
a
a
a
a
a
a
a
74
a
a
a
a
a
a
126
196
127
142
85
97
78
71
123
117
72
73
66
a
a
a
UO-31
89
162
78
66
Prostate cancer
PC-3
DU-145
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
77
65
88
a
154
122
70
62
(Continued)
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Vol 000
Table 2
(Continued)
Panel cell lines
15d
15e
16e
17e
28e
29e
31c
31d
31e
32c
32d
32e
33c
33d
33e
Breast cancer
MCF7
MCF7/ADR-RES
HS 578T
MDA-MB-135
MDA-N
BT-549
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
56
68
104
111
121
139
127
82
74
96
76
63
60
137
182
94
98
117
a
a
a
60
87
91
a
a
a
a
a
a
a
83
97
97
91
91
84
64
104
a
a
a
a
a
a
a
a
a
a
62
69
68
65
92
161
79
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
75
a
a
59
80
111
149
a
a
T-47D
82
82
75
132
81
97
aBelow 40%.
Scheme 1. Synthesis of compounds chloro-quinoxalines 7a–e, 8 and 9.
Scheme 2. Synthesis of benzotriazolic synthones 12a–c.
Scheme 3. Synthesis of diethyl 2-(6-amino-1/2/3H-benzotriazol-1/2/3-yl)pentanedioates 14a–c.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential
Anti-Folate Agents
Scheme 4. Synthetic pathways for ethyl 2-(5-(quinoxalin-2-ylmethyl)-1/2/3H-benzo[d][1,2,3]triazol-1/2/3-yl)acetate derivatives (15,17a–e, 16e) and
corresponding isomeric monocarboxylic (18,19a–b) and dicarboxylic (20–22) acids.
the same way obtained by simultaneous hydrolysis of the
two ethyl ester functions in derivatives 15–17e.
observed the hydrolysis of the terminal ester functions,
with the isolation of monocarboxylic acids (like 18a from
15a) or dicarboxylic acids (like 22 from 17e), in low yield
(30–40%). We tried to push reaction conditions raising the
temperature up to 90°C to investigate the parameter rele-
vance in the chemical behavior, and we observed, for com-
pound 15e, not only the formation of dicarboxylic acid 21
(15–30% yield) but also the formation of its precursor,
quinoxalinone 4e (50–60% yield). All of these confirm,
as previously reported [51], that the increase of tempera-
ture over 60°C in this oxidative conditions on quinoxaline
derivatives does not lead to N-oxidation but rather to the
oxidation at position 2 and eventually to hydrolysis of sus-
ceptible functions.
With the aim to implement the quinoxaline derivatives
structure–activity relationships, quinoline derivative 7e
was submitted to condensation with the most sterically
hindered benzotriazoles 14a–c. Reaction conditions were
the same as reported earlier and chemically lead to the syn-
thesis of benzotriazolyl amino quinoxalines carboxylate
23–25, as depicted in Scheme 5.
In an attempt to prepare quinoxaline 1,4-dioxides, we
tried to oxidize some of the prepared quinoxalines from se-
ries 15, 16, and 17, using glacial acetic acid and H2O2
30%, monitoring temperature to maintain it between 0°C
and 40°C, but unfortunately, oxidation products were not
observed on nitrogens from quinoxaline or benzotriazolic
moieties. Raising the temperature from 40°C to 60°C, we
After this observation, and taking advantage of the pre-
vious experience gained in the synthesis of quinoxaline
Scheme 5. Synthesis of benzotriazolyl amino quinoxalines carboxylate 23–25.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Vol 000
dioxide, we have come to an independent synthetic path-
way to obtain new derivatives linked to the benzotriazole
moiety. For this purpose, we have prepared the appropriate
synthons bearing the function N-oxide already in the
system, as previously reported [39], obtaining the desired
2-chloro-3-substituted quinoxaline 1,4-dioxides 26a–e in
good yield. The reaction sequence employed for the syn-
thesis is reported in Scheme 6.
The next step was the condensation between quinoxaline
1,4-dioxides 26a–e with the appropriate amino benzotriazolyl
acetates 12a–c or benzotriazolyl pentanedioates 14a–c,
obtaining in almost all cases the desired esters, which when
washed with ethanol or purified by chromatography afforded
the derivatives of substitution of the benzotriazole N1 (28a–e
and 31a,c–e), N2 (29a,b,e and 32a,c–e), and N3 (30a–e and
33a,c–e) (Scheme 7). All these confirm that reported earlier
for this type of reaction. Again, structures of the single iso-
mers were assigned on the basis of 1H- and 13C-NMR
spectra.
EXPERIMENTAL
Melting points were uncorrected and were taken in open
capillaries in a Digital Electrothermal IA9100 melting
point apparatus. H-NMR and 13C-NMR spectra were re-
1
corded on a Varian Bruker Avance II 600-MHz spectrom-
eter, using TMS as internal standard. The chemical shift
values are reported in ppm (δ) and coupling constants (J)
in Hertz (Hz). Signal multiplicities are represented by the
following: s (singlet), d (doublet), dd (double doublet), t
(triplet), q (quadruplet), and m (multiplet). Column chro-
matography was performed using 70–230mesh (Merck sil-
ica gel 60). Light petroleum refers to the fraction with bp
40–60°C. The progress of the reactions and the Rf were
monitored by TLC using Merck F-254 commercial plates.
Analyses indicated by the symbols of the elements were
within 0.4% of the theoretical values.
Chromatographic separation was performed on an
Agilent 1100 LC System that included a binary pump,
Diode-Array Detector, column thermostat, degasser, and
Scheme 6. Synthetic pathway for 2-chloro-3-substitued quinoxaline 1,4-dioxides 26a–e.
Scheme 7. Synthetic pathway for ethyl 2-(5-((3-methyl-1,4-dioxide-quinoxalin-2-yl)amino)-1/2/3H-benzo[d][1,2,3]triazol-1/2/3-yl)acetate (28a–e, 29a,b,e,
30a–e) and pentanedioates (31–33a,c–e) derivatives.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential
Anti-Folate Agents
HTS-PAL autosampler (Agilent Technologies, Paolo Alto,
CA, USA). The HPLC column was a Luna C18 (2)
(4.6 ∙ 150mm, 3 μm) from Phenomenex (Torrance, CA,
USA) with a security guard cartridge (4 ∙2 mm). The mo-
bile phase consisted of Eluent A water with 0.1% acetic
acid and Eluent B acetonitrile. The flow rate was set at
0.5mL/min, and the column temperature was 33°C. Total
run time was 30 min. Gradient program in Table 3.
The Diode Array Detector was set at 280 and 220nm
Bw = 4 Reference 800. Elemental analyses were performed
on Agilent Chemstation HP A.10.02.
Starting materials, intermediates, and known compounds.
Quinoxalinone intermediates 4a [52], 4b [53], 4c [53], 4d
[54], 4e [55], 5 [10], and 6 [10]; corresponding amines 7a
[56], 7b [57], 7c [57], 7d [57], and 7e [23]; and 5-nitro-
benzotriazole 10 [58] were prepared using previously
reported procedures. All other chemicals used in this
study were commercially available.
drop. The temperature was maintained for 1h. The mixture
reaction was cooled, the triethylamine hydrochloride was
filtered apart, and solvent was evaporated to dryness in
vacuo. The solid residue was purified by chromatography
on silica gel column, eluting with a mixture of diethyl
ether-petroleum ether (1:1) to afford 11a–c in the order
reported below.
Ethyl 2-(5-nitro-2H-benzo[d][1,2,3]triazol-2-yl)acetate
1
(11b). Yield 33%. Mp: 124–126°C. H-NMR (CDCl3):
δ 8.91 (d, 1H, J= 2.0 Hz, H-4), 8.27 (dd, 1H, J =9.8 and
2.0 Hz, H-6), 8.03 (d, 1H, J =9.8 Hz, H-7), 5.60 (s, 2H,
CH2), 4.31 (q, 2H, J= 7.2 Hz, CH2–CH3), 1.31 (s, 3H,
CH2–CH3). 13C-NMR (CDCl3): δ 165.28 (CO), 146.70
(C-5), 146.63 (C-7a), 143.28 (C-3a), 120.33 (C-6),
119.52 (C-7), 116.32 (C-4), 62.63 (O-CH2), 57.70
(N-CH2), 13.92 (CH3). LC/MS: 251 (M + H). Anal. Calcd
for C10H10N4O4: C, 48.00; H, 4.03; N, 22.39. Found C,
47.81; H, 3.98; N, 22.31.
Ethyl 2-(6-nitro-1H-benzo[d][1,2,3]triazol-1-yl)acetate (11c).
General procedure for preparation of chloro-nitro-
Yield 28%. Mp: 116–117°C. 1H-NMR (CDCl3): δ 8.51 (d,
1H, J = 2.0 Hz, H-4), 8.31 (dd, 1H, J = 9.6 and 2.0 Hz, H-
6), 8.22 (d, 1H, J = 9.6 Hz, H-7), 5.56 (s, 2H, CH2), 4.31
(q, 2H, J = 7.2 Hz, CH2–CH3), 1.33 (s, 3H, CH2–CH3).
13C-NMR (CDCl3): δ 165.68 (CO), 148.02 (C-7a),
147.14 (C-5), 132.27 (C-3a), 120.99 (C-7), 118.99 (C-6),
106.91 (C-4), 62.66 (O-CH2), 49.45 (N-CH2), 13.92
(CH3). LC/MS: 251 (M + H). Anal. Calcd for
C10H10N4O4: C, 48.00; H, 4.03; N, 22.39. Found C,
phenylquinoxalines
8
and 9.
25 mmol of nitro-
phenylquinoxalin-2(1H)-one 5 and 6 was added to 30mmol
of POCl3. Heated at 100°C for 2h, with continuous stirring.
The mixture was poured into crushed ice (100g). The
resulting solid was collected, washed with water, and dried
in an oven. The solid was chromatographically purified to
give 8 in 72% yield and 9 in 63% yield.
2-chloro-6-nitro-3-phenylquinoxaline (8).
Yield 72%.
Mp: 141–143°C. 1H-NMR (CDCl3): δ 8.96 (d, 1H,
J =2.4 Hz, H-8), 8.57 (dd, 1H, J= 9.2 and 2.4 Hz, H-6),
8.30 (d, 1H, J = 9.2 Hz, H-5), 7.94–7.89 (m, 2H, Ph),
7.60–7.57 (m, 3H, Ph). LC/MS: 286 (M + H). Anal.
Calcd for C14H8ClN3O2: C, 58.86; H, 2.82; Cl, 12.41; N,
14.71. Found C, 58.71; H, 2.79; Cl, 12.35; N, 14.66.
47.79; H, 3.99; N, 22.32.
Ethyl 2-(5-nitro-1H-benzo[d][1,2,3]triazol-1-yl)acetate (11a).
1
Yield 32%. Mp: 91–92°C. H-NMR (CDCl3): δ 9.03 (d,
1H, J = 2.0 Hz, H-4), 8.44 (dd, 1H, J = 9.2 and 2.0 Hz,
H-6), 7.64 (d, 1H, J=9.2Hz, H-7), 5.52 (s, 2H, CH2), 4.30
(q, 2H, J=7.2Hz, CH2–CH3), 1.31 (s, 3H, CH2–CH3).
13C-NMR (CDCl3): δ 165.64 (CO), 145.06 (C-3a), 144.78
(C-5), 136.06 (C-7a), 122.81 (C-4), 117.21 (C-6), 110.24
(C-7), 62.63 (O-CH2), 49.33 (N-CH2), 13.93 (CH3).
LC/MS: 251 (M+H). Anal. Calcd for C10H10N4O4: C,
48.00; H, 4.03; N, 22.39. Found C, 47.76; H, 3.97; N, 22.34.
General procedure for preparation of ethyl-amino-1H-
3-chloro-6-nitro-2-phenylquinoxaline (9).
Yield 63%.
1
Mp: 158–160°C. H-NMR (CDCl3): δ 9.07 (s, 1H, H-5),
8.66 (d, 1H, J =9.4 Hz, H-7), 8.02 (d, 1H, J= 9.4 Hz,
H-8), 7.90–7.35 (m, 5H, Ph). LC/MS: 286 (M + H). Anal.
Calcd for C14H8ClN3O2: C, 58.86; H, 2.82; Cl, 12.41; N,
14.71. Found C, 59.12; H, 2.58; Cl, 12.27; N, 14.92.
General procedure for preparation of ethyl nitro-1H-benzo[d]
benzo[d][1,2,3]triazol-yl acetates 12a–c.
A suspension of
[1,2,3]triazol-yl acetates 11a–c.
10 mL of triethylamine
1.5g (6mmol) of appropriate nitro-1H-benzo[d][1,2,3]triazol-yl
acetate 11a–c was dissolved in 150mL of ethanol followed
by the addition of 0.12g of 10% palladium on charcoal.
This mixture was hydrogenated at 3atm for 2h. After
filtering and washing the catalyst thoroughly with ethanol,
the filtrate was concentrated in vacuo. Derivatives 12a–c
was added to a solution of 3 g (18 mmol) of 5-nitro-1H-
benzo[d][1,2,3]triazole 10 in DMF (20 mL). The solution
was heated at reflux with continuous stirring, then 4.48g
(36 mmol) of ethyl 2-chloroacetate were added drop by
were obtained as white solids.
Table 3
Ethyl 2-(5-amino-1H-benzo[d][1,2,3]triazol-1-yl)acetate (12a).
Yield 94%. Mp: 94–96°C. 1H-NMR (CDCl3): δ 7.26 (d, 1H,
J=8.4Hz, H-7), 7.21 (d, 1H, J=1.8Hz, H-4), 6.94 (dd, 1H,
J=8.4 and 1.8Hz, H-6), 5.34 (s, 2H, CH2), 4.24 (q, 2H,
J=7.2Hz, CH2–CH3), 1.26 (s, 3H, CH2–CH3). 13C-NMR
(CDCl3): δ 166.41 (CO), 147.29 (C-3a), 143.74 (C-5),
128.03 (C-7a), 119.76 (C-6), 109.54 (C-7), 101.15 (C-4),
Gradient program.
Time (min)
Phase A (%)
Phase B (%)
Flow (mL/min)
0
20
30
60
20
10
40
80
90
0.5
0.5
0.5
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Vol 000
62.05 (O-CH2), 48.37 (N-CH2), 13.87 (CH3). LC/MS: 221
5.88 (m, 1H, CH, C-2), 4.27 (q, 2H, J=7.4Hz, OCH2–CH3,
(M+H). Anal. Calcd for C10H12N4O2: C, 54.54; H, 5.49;
C-1), 4.10 (q, 2H, J=7.2Hz, OCH2–CH3, C-5), 2.81 (m,
2H, CH2, C-3), 2.34 (m, 2H, CH2, C-4), 1.25 (m, 6H, 2
OCH2–CH3). 13C-NMR (CDCl3): δ 171.67 (C=O), 167.62
(C=O), 148.23 (C-5′), 147.10 (C-7′a), 132.31 (C-3′a),
121.11 (C-7′), 119.12 (C-6′), 107.50 (C-4′), 62.77 (C-2),
61.15 (CH2–CH3), 60.89 (CH2–CH3), 29.85 (C-3), 26.10
(C-4), 14.01 (CH3), 13.10 (CH3). LC/MS: 351 (M+ H).
Anal. Calcd for C15H18N4O6: C, 51.43; H, 5.18; N, 15.99.
N, 25.44. Found C, 54.41; H, 5.42; N, 25.36.
Ethyl 2-(5-amino-2H-benzo[d][1,2,3]triazol-2-yl)acetate
1
(12b). Yield 83%. Mp: 86–87°C. H-NMR (CDCl3): δ
8.13 (d, 1H, J =1.8 Hz, H-4), 7.93 (d, 1H, J= 9.2 Hz,
H-7), 7.59 (dd, 1H, J =9.2 and 1.8 Hz, H-6), 5.55 (s, 2H,
CH2), 4.29 (q, 2H, J = 7.2 Hz, CH2–CH3), 1.30 (s, 3H,
CH2–CH3). 13C-NMR (CDCl3): δ 166.43 (CO), 147.26
(C-3a), 145.41 (C-5), 140.36 (C-7a), 121.27 (C-6),
118.73 (C-7), 96.40 (C-4), 62.13 (O-CH2), 56.52
(N-CH2), 13.92 (CH3). LC/MS: 221 (M + H). Anal. Calcd
for C10H12N4O2: C, 54.54; H, 5.49; N, 25.44. Found C,
Found C, 51.38; H, 5.09; N, 15.87.
Diethyl 2-(5-nitro-1H-benzo[d][1,2,3]triazol-1-yl)pentanedioate
(13a).
Yield 32%. 1H-NMR (CDCl3): δ 9.05 (d, 1H,
J = 2.0 Hz, H-4′), 8.43 (dd, 1H, J = 8.8 and 2.0, H-6′), 7.70
(d, 1H, J =8.8 Hz, H-7′), 5.86 (m, 1H, CH, C-2), 4.25 (q,
2H, J = 7.2 Hz, OCH2–CH3, C-1), 4.12 (q, 2H, J =7.2 Hz,
OCH2–CH3, C-5), 2.81 (m, 2H, CH2, C-3), 2.36 (m, 2H,
CH2, C-4), 1.22 (m, 6H, 2 OCH2–CH3). 13C-NMR
(CDCl3): δ 171.70 (C=O), 167.59 (C=O), 145.17 (C-3′a),
144.75 (C-5′), 135.60 (C-7′a), 122.63 (C-4′), 117.21
(C-6′), 110.81 (C-7′), 62.60 (C-2), 60.83 (CH2–CH3),
60.74 (CH2–CH3), 29.70 (C-3), 25.87 (C-4), 13.93 (CH3),
13.83 (CH3). LC/MS: 351 (M+ H). Anal. Calcd for
C15H18N4O6: C, 51.43; H, 5.18; N, 15.99. Found C,
51.39; H, 5.11; N, 15.87.
54.43; H, 5.45; N, 25.37.
Ethyl 2-(6-amino-1H-benzo[d][1,2,3]triazol-1-yl)acetate
1
(12c). Yield 84%. Mp: 81–83°C. H-NMR (CDCl3): δ
7.79 (d, 1H, J= 8.8 Hz, H-7), 6.74 (dd, 1H, J = 8.4 and
1.8Hz, H-6), 6.43 (d, 1H, J= 1.8 Hz, H-4), 5.25 (s, 2H,
CH2), 4.24 (q, 2H, J = 7.2 Hz, CH2–CH3), 1.26 (s, 3H,
CH2–CH3). 13C-NMR (CDCl3): δ 167.49 (CO), 149.19
(C-5), 138.69 (C-7a), 135.40 (C-3a), 119.40 (C-7),
115.56 (C-6), 88.76 (C-4), 61.337 (O-CH2), 48.03
(N-CH2), 13.99 (CH3). LC/MS: 221 (M + H). Anal. Calcd
for C10H12N4O2: C, 54.54; H, 5.49; N, 25.44. Found C,
54.40; H, 5.43; N, 25.37.
General procedure to prepare diethyl amino-(1H-benzo[d]
[1,2,3]triazolyl)pentanedioates 14a–c. A suspension of 0.5 g
General procedure to prepare diethyl nitro-1H-benzotriazol-
1-yl pentanedioates 13a–c. 0.55g (3.3mmol) of 5-nitro-1H-
(1.4mmol) of appropriate nitro-1H-benzotriazol-1-yl
pentanedioates 13a–c was dissolved in 50mL of ethanol
followed by the addition of 0.05g of 10% palladium on
charcoal. This mixture was hydrogenated at 3atm for 3h.
After filtering and washing the catalyst thoroughly with
ethanol, the filtrate was concentrated in vacuo. Derivatives
benzo[d][1,2,3]triazole was dissolved in 10mL of DMF and
added with 0.36g (3.3mmol) of triethylamine and 0.9g
(3.3mmol) of diethyl 2-bromopentanedioate. The reaction
mixture was heated to 100°C for 4h, then cooled and
diluted with 100mL of water.
The aqueous solution was extracted with diethyl ether
(2 × 50 mL), and the organic phase was evaporated. The
obtained liquid residue was purified by chromatography
on silica gel column, eluting with a mixture of diethyl
ether-petroleum ether (1:1) to afford, as pure liquid, deriv-
14a–c were obtained as white solids.
Diethyl 2-(5-amino-1H-benzo[d][1,2,3]triazol-1-yl)pentanedioate
(14a).
Yield 72%. 1H-NMR (CDCl3): δ 7.34 (d, 1H,
J = 9.0 Hz, H-7′), 7.22 (d, 1H, J = 2.0 Hz, H-4′), 6.94 (dd,
1H, J= 9.0 and 2.0 Hz, H-6′), 5.66 (m, 1H, CH, C-2), 4.20
(q, 2H, J =7.2 Hz, O–CH2–CH3, C-1), 4.08 (q, 2H,
J = 7.2 Hz, O–CH2–CH3, C-5), 2.72 (m, 2H, CH2, C-3),
2.25 (m, 2H, CH2, C-4), 1.21 (m, 6H, 2 O–CH2–CH3).
13C-NMR (CDCl3): δ 171.83 (C=O), 168.12 (C=O),
147.48 (C-3′a), 143.91 (C-5′), 127.18 (C-7′a), 119.52 (C-
4′), 110.13 (C-6′), 100.91 (C-7′), 61.10 (C-2), 60.43
(CH2–CH3), 60.28 (CH2–CH3), 29.71 (C-3), 25.61 (C-4),
13.80 (CH3), 13.69 (CH3). LC/MS: 321 (M + H). Anal.
Calcd for C15H20N4O4: C, 56.24; H, 6.29; N, 17.49.
atives 13a–c in the order reported below.
Diethyl 2-(5-nitro-2H-benzo[d][1,2,3]triazol-2-yl)pentanedioate
(13b).
Yield 32%. 1H-NMR (CDCl3): δ 8.91 (d, 1H,
J=2.0Hz, H-4′), 8.27 (dd, 1H, J=9.0 and 2.0Hz, H-6′),
8.02 (d, 1H, J=9.2Hz, H-7′), 5.82 (m, 1H, CH, C-2), 4.26
(q, 2H, J=7.2Hz, OCH2–CH3, C-1), 4.13 (q, 2H,
J=7.4Hz, OCH2–CH3, C-5), 2.85 (m, 2H, CH2, C-3), 2.33
(m, 2H, CH2, C-4), 1.24 (m, 6H, 2 OCH2–CH3). 13C-NMR
(CDCl3): δ 171.64 (C=O), 167.66 (C=O), 146.66 (C-5′),
146.26 (C-7′a), 142.88 (C-3′a), 120.97 (C-4′), 119.60
(C-7′), 116.40 (C-6′), 68.23 (C-2), 62.60 (CH2–CH3), 60.71
(CH2–CH3), 29.89 (C-3), 26.41 (C-4), 14.01 (CH3), 13.85
(CH3). LC/MS: 351 (M+H). Anal. Calcd for C15H18N4O6:
C, 51.43; H, 5.18; N, 15.99. Found C, 51.34; H, 5.07; N,
Found C, 56.19; H, 6.21; N, 17.45.
Diethyl 2-(5-amino-2H-benzo[d][1,2,3]triazol-2-yl)pentanedioate
(14b). Yield 73%. 1H-NMR (CDCl3): δ 7.67 (dd, 1H, J=7.2
and 2.0Hz, H-6′), 6.89 (d, 1H, J=2.0Hz, H-4′), 6.87 (dd, 1H,
J= 7.2 and 2.0 Hz, H-6′), 5.58 (m, 1H, CH, C-2), 4.21 (q, 2H,
J=7.4Hz, O–CH2–CH3, C-1), 4.11 (q, 2H, J=7.2Hz,
O–CH2–CH3, C-5), 2.77 (m, 2H, CH2, C-3), 2.29 (m, 2H,
CH2, C-4), 1.23 (m, 6H, 2 O–CH2–CH3). 13C-NMR
(CDCl3): δ 171.93 (C=O), 168.03 (C=O), 145.82 (C-3′a),
15.79.
Diethyl 2-(6-nitro-1H-benzo[d][1,2,3]triazol-1-yl)pentanedioate
(13c). Yield 22%. 1H-NMR (CDCl3): δ 8.56 (s, 1H, H-4′),
8.31 (d, 1H, J=9.2, H-6′), 8.23 (d, 1H, J=9.2Hz, H-7′),
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2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential
Anti-Folate Agents
145.44 (C-5′), 139.80 (C-7′a), 121.08 (C-7′), 118.70 (C-4′),
96.24 (C-6′), 66.71 (C-2), 62.04 (CH2–CH3), 60.45 (CH2–
CH3), 30.00 (C-3), 28.30 (C-4), 13.92 (CH3), 13.77 (CH3).
(t, 3H, J=7.2Hz, CH2–CH3, C-3ʺ). LC/MS: 391 (M+ H).
Anal. Calcd for C21H22N6O2: C, 64.60; H, 5.68; N, 21.52.
Found C, 64.53; H, 5.59; N, 21.38.
Ethyl 2-(5-((3-isopropylquinoxalin-2-yl)amino)-1H-benzo[d]
LC/MS: 321 (M + H). Anal. Calcd for C15H20N4O4: C,
56.24; H, 6.29; N, 17.49. Found C, 56.19; H, 6.23; N, 17.39.
Diethyl 2-(6-amino-1H-benzo[d][1,2,3]triazol-1-yl)pentanedioate
[1,2,3]triazol-1-yl)acetate (15c).
Yield 79%. Reflux for
1
70h. Mp: 203–204°C. H-NMR (CDCl3): δ 8.86 (s, 1H,
NH), 8.75 (s, 1H, H-4′), 7.97 (d, 1H, J= 8.8 Hz, H-8ʺ),
7.68 (m, 2H, H-5ʺ and H-6′), 7.58 (m, 1H, H-7ʺ), 7.43
(m, 1H, H-6ʺ), 5.62 (s, 2H, CH2, C-1), 4.25 (q, 2H,
J = 7.2 Hz, OCH2–CH3), 3.16 (m, 1H, CH), 1.43 (s, 3H,
CH–CH3), 1.40 (s, 3H, CH–CH3) , 1.30 (t, 3H,
J = 6.8 Hz, OCH2–CH3). LC/MS: 391 (M + H). Anal.
Calcd for C21H22N6O2: C, 64.60; H, 5.68; N, 21.52.
Found C, 64.51; H, 5.53; N, 21.42.
(14c).
Yield 73%. 1H-NMR (CDCl3): δ 7.80 (d, 1H,
J=8.8Hz, H-7′), 7.76 (dd, 1H, J=8.8 and 2.0 Hz, H-6′),
6.60 (d, 1H, J=2.0Hz, H-4′), 5.58 (m, 1H, CH, C-2), 4.20
(q, 2H, J=7.2Hz, O–CH2–CH3, C-1), 4.09 (q, 2H,
J=7.2Hz, O–CH2–CH3, C-5), 2.72 (m, 2H, CH2, C-3), 2.27
(m, 2H, CH2, C-4), 1.24 (m, 6H, 2 O–CH2–CH3). 13C-NMR
(CDCl3): δ 171.78 (C=O), 168.15 (C=O), 147.45 (C-5′),
139.92 (C-3′a), 134.30 (C-7′a), 121.08 (C-7′a), 119.98
(C-7′), 115.63 (C-6′), 90.27 (C-4′), 61.71 (C-2), 60.21
(CH2–CH3), 59.15 (CH2–CH3), 29.58 (C-3), 25.17 (C-4),
13.58 (CH3), 13.47 (CH3). LC/MS: 321 (M + H). Anal.
Calcd for C15H20N4O4: C, 56.24; H, 6.29; N, 17.49. Found
C, 56.17; H, 6.22; N, 17.36.
Ethyl
2-(5-((3-phenylquinoxalin-2-yl)amino)-1H-benzo[d]
[1,2,3]triazol-1-yl)acetate (15d).
Yield 33%. Reflux for
1
87h. Mp: 152–153°C. H-NMR (CDCl3): δ 10.21 (s, 1H,
NH), 9.03 (s, 1H, H-4′), 7.97 (d, 1H, J = 8.2 Hz, H-7′),
7.87 (m, 3H, H-5ʺ, H-8ʺ and H-6′), 7.66 (m, 4H, H-6ʺ,
H-7ʺ and 2 CHphenyl), 7.47 (m, 3H, 3 CHphenyl), 5.44 (s,
2H, CH2, C-1), 4.27 (q, 2H, J =7.2 Hz, OCH2–CH3),
1.29 (t, 3H, J= 6.8 Hz, OCH2–CH3). LC/MS: 425 (M
+ H). Anal. Calcd for C24H20N6O2: C, 67.80; H, 4.67; N,
General procedure to prepare ethyl quinoxalin-2-yl
amino-1H-benzo[d][1,2,3]triazolyl acetates 15a–e, 16e, and
17a–e. A solution of equimolar amounts (1.33–9.1 mmol)
of the appropriate chloroquinoxalines 7a–e and the
suitable ethyl-amino-1H-benzo[d][1,2,3]triazol-yl acetates
12a–c in ethanol (10–30mL) was stirred and refluxed for
13–155h. Progress of the reaction was monitored by TLC
using diethyl ether/petroleum ether (8:2). On cooling to
room temperature from the reaction mixture, a crude
precipitate was formed and collected by filtration. Solvent
was evaporated, and the obtained solid was purified by
chromatography on silica gel column, eluting with an 8:2
mixture of diethyl ether/petroleum ether. Ethyl quinoxalin-
2-yl amino-1H-benzo[d][1,2,3]triazolyl acetates 16a–d were
19.67. Found C, 67.51; H, 4.95; N, 19.31.
Ethyl 3-((1-(2-ethoxy-2-oxoethyl)-1H-benzo[d][1,2,3]triazol-
5-yl)amino)quinoxaline-2-carboxylate (15e).
Yield 94%.
1
Reflux for 70h. Mp: 192–194°C. H-NMR (CDCl3): δ
10.57 (s, 1H, NH), 9.18 (s, 1H, H-4′), 8.06 (d, 1H,
J = 8.8 Hz, H-7′), 7.87 (d, 1H, J = 8.4 Hz, H-6′), 7.75 (d,
1H, J = 7.8 Hz, H-8ʺ), 7.64 (d, 1H, J= 7.8 Hz, H-5ʺ), 7.52
(m, 2H, H-6ʺ and H-7ʺ), 5.42 (s, 2H, CH2, C-1), 4.62 (q,
2H, J = 7.0 Hz, OCH2–CH3), 4.27 (q, 2H, J =7.2 Hz,
CH2–CH3, C-3ʺ), 1.55 (t, 3H, J= 7.0 Hz, OCH2–CH3),
1.28 (t, 3H, J= 7.2 Hz, OCH2–CH3). LC/MS: 421 (M
+ H). Anal. Calcd for C21H20N6O4: C, 59.99; H, 4.79; N,
not obtained.
Ethyl 2-(5-((3-ethylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]
triazol-1-yl)acetate (15a). Yield 70%. Reflux for 28h. Mp:
19.99. Found C, 59.76; H, 4.67; N, 19.76.
1
191–193°C. H-NMR (CDCl3): δ 10.93 (s, 1H, NH), 8.66
Ethyl 3-((2-(2-ethoxy-2-oxoethyl)-2H-benzo[d][1,2,3]triazol-
5-yl)amino)quinoxaline-2-carboxylate (16e).
Yield 78%.
(s, 1H, H-4′), 8.07 (d, 1H, J=8.0Hz, H-7′), 7.90 (d, 1H,
J=8.2Hz, H-8ʺ), 7.62 (d, 1H, J=8.2Hz, H-5ʺ), 7.70 (d,
1H, J=9.0Hz, H-6′), 7.59 (m, 2H, H-6ʺ and H-7ʺ), 5.59
(s, 2H, CH2, C-1), 4.28 (q, 2H, J=7.0Hz, OCH2–CH3),
3.37 (q, 2H, J=7.2Hz, CH2–CH3, C-3ʺ), 1.51 (t, 3H,
J=7.0Hz, OCH2–CH3), 1.35 (t, 3H, J=7.2Hz, CH2–CH3,
C-3ʺ). LC/MS: 377 (M+H). Anal. Calcd for C20H20N6O2:
C, 63.82; H, 5.36; N, 22.33. Found C, 63.73; H, 5.31; N,
1
Reflux for 16h. Mp: 148–150°C. H-NMR (CDCl3): δ
10.64 (s, 1H, NH), 9.15 (s, 1H, H-4′), 8.70 (d, 1H,
J = 8.2 Hz, H-7′′), 7.87 (m, 2H, H-8′′ and H-5′′), 7.75 (m,
1H, H-6′′), 7.53 (m, 1H, H-7′′), 7.40 (d, 1H, J =9.0 Hz,
H-6′), 5.54 (s, 2H, CH2, C-1), 4.62 (q, 2H, J =7.2 Hz,
OCH2–CH3, C-3′′), 4.29 (q, 2H, J =7.2 Hz, OCH2–CH3,
C-2), 1.55 (t, 3H, J =7.2 Hz, OCH2–CH3, C-3′′), 1.29
(t, 3H, J= 7.2 Hz, OCH2–CH3, C-2). LC/MS: 421 (M
+ H). Anal. Calcd for C21H20N6O4: C, 59.99; H, 4.79; N,
22.24.
Ethyl 2-(5-((3-propylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]
triazol-1-yl)acetate (15b). Yield 67%. Reflux for 70h. Mp:
19.99. Found C, 59.77; H, 4.66; N, 19.87.
150–151°C. 1H-NMR (CDCl3): δ 8.90 (s, 1H, NH), 8.41 (s,
1H, H-4′), 7.95 (d, 1H, J=8.8Hz, H-8ʺ), 7.40 (d, 1H,
J=8.8Hz, H-5ʺ), 7.73 (d, 1H, J=8.0Hz, H-7′), 7.56 (m,
2H, H-6ʺ and H-7ʺ), 7.47 (d, 1H, J=9.0Hz, H-6′) 5.52 (s,
2H, CH2, C-1), 4.27 (q, 2H, J=6.8Hz, OCH2–CH3), 3.10
(t, 2H, J=7.8Hz, CH2–CH2–CH3), 1.97 (m, 2H, CH2–
CH2–CH3), 1.31 (t, 3H, J=6.8Hz, OCH2–CH3), 1.13
Ethyl 2-(6-((3-ethylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]
triazol-1-yl)acetate (17a). Yield 86%. Reflux for 24 h. Mp:
1
226–228°C. H-NMR (CDCl3): δ 8.77 (s, 1H, NH), 8.61
(s, 1H, H-4′), 7.94 (d, 1H, J=8.6Hz, H-7′′), 7.87 (d, 1H,
J=8.2Hz, H-6′), 7.69(m, 2H, H-8′′ and H-5′′), 7.58 (m, 2H,
H-6′′ and H-7′′), 5.52 (s, 2H, CH2, C-1), 4.29 (q, 2H,
J=7.2Hz, OCH2–CH3), 3.15 (q, 2H, J=7.2Hz, CH2–CH3,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Vol 000
C-3′′), 1.46 (t, 3H, J=7.2Hz, OCH2–CH3), 1.31 (t, 3H,
J=7.2Hz, CH2–CH3, C-3′′). LC/MS: 377 (M+H). Anal.
Calcd for C20H20N6O2: C, 63.82; H, 5.36; N, 22.33. Found
C, 63.79; H, 5.24; N, 22.24.
Ethyl 2-(6-((3-propylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]
drop by drop to the solution until pH= 4. The precipitate
obtained was filtered off, washed with water, and dried to
give the corresponding carboxylic acid. The solid residues
were purified by recrystallization from a mixture of acetone
and ethanol (1:1).
2-(5-((3-ethylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]triazol-
triazol-1-yl)acetate (17b). Yield 86%. Reflux for 155 h. Mp:
1-yl)acetic acid (18a). Yield 87%. Mp: 256–258°C. 1H-NMR
1
181–183°C. H-NMR (CDCl3): δ 7.09 (s, 1H, NH), 8.84
(CDCl3): δ 8.90 (s, 1H, NH), 8.80 (s, 1H, H-4′), 7.97 (d, 1H,
J=8.2Hz, H-7′), 7.82 (m, 2H, H-8′′, H-5′′), 7.71 (d, 1H,
J=8.2Hz, H-6′), 7.60 (m, 1H, H-7′′), 7.47 (m, 1H, H-6′′),
5.66 (s, 2H, CH2). LC/MS: 349 (M+ H). Anal. Calcd for
C18H16N6O2: C, 62.06; H, 4.63; N, 24.12. Found C, 61.88;
H, 4.57; N, 23.05.
2-(5-((3-propylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]
triazol-1-yl)acetic acid (18b). Yield 94%. Mp: 251–252°C.
(s, 1H, H-4′), 7.99 (d, 1H, J= 9.0 Hz, H-7′′), 7.93 (d, 1H,
J =8.2 Hz, H-8′′), 7.81 (d, 1H, J = 8.2 Hz, H-5′′), 7.63
(m, 1H, H-7′′), 7.54 (m, 1H, H-6′′), 7.28 (m, 1H, H-6′),
5.45 (s, 2H, CH2, C-1), 4.29 (q, 2H, J =7.2 Hz, OCH2–
CH3), 2.97 (t, 2H, J= 8.0 Hz, CH2–CH2CH3), 2.00 (m,
2H, CH2–CH2–CH3), 1.28 (t, 3H, J= 7.2 Hz, OCH2–
CH3), 1.15 (t, 3H, J = 7.2 Hz, CH2CH2–CH3). LC/MS:
391 (M + H). Anal. Calcd for C21H22N6O2: C, 64.60; H,
1H-NMR (CDCl3): δ 8.86 (s, 1H, NH), 8.60 (s, 1H, H-4′),
7.95 (d, 1H, J = 9.2 Hz, H-7′), 7.85 (m, 1H, H-6′), 7.68 (m,
2H, H-8′′, H-5′′), 7.48 (m, 2H, H-6′′, H-7′′), 5.49 (s, 2H,
CH2, C-1), 3.09 (t, 2H, CH2–CH2CH3), 1.96 (m, 2H,
CH2–CH2–CH3), 1.25 (t, 3H, J = 7.2 Hz, CH2CH2–CH3).
LC/MS: 363 (M +H). Anal. Calcd for C19H18N6O2: C,
62.97; H, 5.01; N, 23.19. Found C, 62.78; H, 4.96; N,
23.08.
2-(6-((3-ethylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]triazol-
1-yl)acetic acid (19a). Yield 63%. Mp: 268–271°C. 1H-NMR
(CDCl3): δ 8.97 (s, 1H, NH), 8.53 (s, 1H, H-4′), 7.91 (d, 1H,
J=8.6Hz, H-7′), 7.79 (m, 3H, H-8′′, H-5′′ and H-6′), 7.59
(m, 1H, H-7′′), 7.46 (m, 1H, H-6′′), 5.06 (s, 2H, CH2).
LC/MS: 349 (M + H). Anal. Calcd for C18H16N6O2: C,
62.06; H, 4.63; N, 24.12. Found C, 61.85; H, 4.57; N, 24.03.
2-(6-((3-propylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]
triazol-1-yl)acetic acid (19b). Yield 87%. Mp: 271–273°C.
1H-NMR (CDCl3): δ 8.76 (s, 1H, NH), 8.71 (s, 1H, H-4′),
7.93 (d, 1H, J =8.2 Hz, H-7′), 7.82 (m, 3H, H-6′, H-8′′ and
H-5′′), 7.58 (m, 1H, H-7′′), 7.45 (m, 1H, H-6′′), 5.47 (s,
2H, CH2, C-1), 3.11 (t, 2H, CH2–CH2CH3), 1.94 (m, 2H,
CH2–CH2–CH3), 1.14 (t, 3H, J = 7.2 Hz, CH2CH2–CH3).
LC/MS: 363 (M +H). Anal. Calcd for C19H18N6O2: C,
62.97; H, 5.01; N, 23.19. Found C, 62.76; H, 4.93; N,
5.68; N, 21.52. Found C, 64.49; H, 5.53; N, 21.39.
Ethyl 2-(6-((3-isopropylquinoxalin-2-yl)amino)-1H-benzo[d]
[1,2,3]triazol-1-yl)acetate (17c).
Yield 40%. Reflux for
1
72h. Mp: 203–205°C. H-NMR (CDCl3): δ 7.09 (s, 1H,
NH), 8.84 (s, 1H, H-4′), 7.99 (d, 1H, J=9.0Hz, H-7′),
7.93 (d, 1H, J=8.2Hz, H-8′′), 7.81 (d, 1H, J=8.2Hz,
H-5′′), 7.63 (m, 1H, H-7′′), 7.54 (m, 1H, H-6′′), 7.28 (m,
1H, H-6′), 5.45 (s, 2H, CH2, C-1), 4.29 (q, 2H, J=7.2Hz,
OCH2–CH3), 2.97 (t, 2H, J=8.0Hz, CH2–CH2CH3), 2.00
(m, 2H, CH2–CH2–CH3), 1.28 (t, 3H, J=7.2Hz, OCH2–
CH3), 1.15 (t, 3H, J=7.2Hz, CH2CH2–CH3). LC/MS: 391
(M+H). Anal. Calcd for C21H22N6O2: C, 64.60; H, 5.68;
N, 21.52. Found C, 64.54; H, 5.51; N, 21.43.
Ethyl 2-(6-((3-phenylquinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]
triazol-1-yl)acetate (17d). Yield 34%. Reflux for 94h. Mp:
1
192–193°C. H-NMR (CDCl3): δ 8.96 (s, 1H, NH), 8.54
(s, 1H, H-4′), 7.98 (d, 1H, J =8.4 Hz, H-7′), 7.87 (m, 4H,
H-8′′, H-5′′, H-6′′ H-6′), 7.65 (m, 6H, H-7′′, 5 CH, Ph),
5.75 (s, 2H, CH2, C-1), 4.22 (q, 2H, J =7.2 Hz, OCH2–
CH3), 1.24 (t, 3H, J= 7.2 Hz, OCH2–CH3). LC/MS: 425
(M + H). Anal. Calcd for C24H20N6O2: C, 67.91; H, 4.75;
N, 19.80. Found C, 67.68; H, 4.69; N, 19.62.
Ethyl 3-((1-(2-ethoxy-2-oxoethyl)-1H-benzo[d][1,2,3]triazol-
6-yl)amino)quinoxaline-2-carboxylate (17e).
Yield 93%.
23.13.
1
Reflux for 23h. Mp: 191–193°C. H-NMR (CDCl3): δ
10.78 (s, 1H, NH), 8.81 (s, 1H, H-4′), 8.09 (d, 1H,
J =9.0 Hz, H-7′), 8.02 (d, 1H, J = 9.0 Hz, H-6′), 7.78 (m,
2H, H-8′′, H-5′′), 7.56 (m, 1H, H-6′′), 7.40 (m, 1H, H-7′
′), 5.45 (s, 2H, CH2, C-1), 4.62 (q, 2H, J= 7.2 Hz,
OCH2–CH3, C-3′′), 4.29 (q, 2H, J= 7.2 Hz, OCH2–CH3,
C-2), 1.55 (t, 3H, J = 7.2 Hz, OCH2–CH3, C-3′′), 1.27 (t,
3H, J = 7.2Hz, OCH2–CH3, C-2). LC/MS: 421 (M + H).
Anal. Calcd for C21H20N6O2: C, 59.99; H, 4.79; N,
19.99. Found C, 59.72; H, 4.73; N, 19.81.
3-((1-(carboxymethyl)-1H-benzo[d][1,2,3]triazol-5-yl)amino)
quinoxaline-2-carboxylic acid (20). Yield 97%. Mp: 286–
288°C. H-NMR (CDCl3): δ 10.72 (s, 1H, NH), 9.03 (s,
1H, H-4′), 8.01 (d, 1H, J =8.2 Hz, H-7′), 7.83 (m, 3H, H-
8′′, H-5′′ and H-6′), 7.62 (m, 2H, H-6′′ and H-7′′), 5.67
(s, 2H, CH2). LC/MS: 365 (M + H). Anal. Calcd for
C17H12N6O4: C, 56.05; H, 3.32; N, 23.07. Found C,
55.87; H, 3.28; N, 22.89.
1
3-((2-(carboxymethyl)-2H-benzo[d][1,2,3]triazol-5-yl)amino)
quinoxaline-2-carboxylic acid (21). Yield 90%. Mp: 250–
1
251°C. H-NMR (CDCl3): δ 10.82 (s, 1H, NH), 9.04 (s,
General procedure to prepare quinoxalin-2-yl amino-(1H-
benzotriazol-1-yl)acetic acids 18–19a,b and ((carboxymethyl-
1H-benzotriazol-yl) amino) quinoxaline-2-carboxylic acids 20–
22. A mixture of the carboxylates 15a,b,e, 16e, and 17a,b,e
(0.69–1.18mmol) and NaOH 2M (25–50mL) was stirred at
100°C for 2 h. After cooling to rt, HCl conc. was added
1H, H-4′), 7.99 (m, 2H, H-7′ and H-6′), 7.89 (m, 2H, H-
8′′ and H-5′′), 7.62 (m, 1H, H-7′′), 7.49 (m, 1H, H-6′′),
5.65 (s, 2H, CH2). LC/MS: 365 (M + H). Anal. Calcd for
C17H12N6O4: C, 56.05; H, 3.32; N, 23.07. Found C,
55.79; H, 3.28; N, 22.99.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential
Anti-Folate Agents
3-((1-(carboxymethyl)-1H-benzo[d][1,2,3]triazol-6-yl)amino)
General procedure to prepare ethyl 2-(5-((6,7-substituted-3-
quinoxaline-2-carboxylic acid (22). Yield 92%. Mp: 286–
288°C. H-NMR (CDCl3): δ 10.95 (s, 1H, NH), 8.83 (s,
methyl-1,4 dioxide-quinoxalin2-yl)amino)-1H-benzo[d][1,2,3]
1
triazol-1(2)(3)-yl)acetates 28a–e, 29a,b,e, and 30a–e.
Title
compounds were prepared by condensation of the appropriate
2-chloro-3-methylquinoxaline 1,4-dioxides (27a–e) (1.33–
9.1 mmol) with an equimolar amount of the suitable ethyl
2-(5-amino-1H-benzo[d][1,2,3]triazol-1(2)(3)-yl)acetates
(12a–c) in refluxed ethanol (20–100 mL) for 8–24h. Progress
of the reaction was monitored by TLC using diethyl ether.
After cooling to rt, the resulting precipitate was filtered off,
1H, H-4′), 8.04 (m, 2H, H-7′ and H-6′), 7.88 (m, 2H,
H-8′′ and H-5′′), 7.59 (m, 2H, H-6′′ and H-7′′), 5.68
(s, 2H, CH2). LC/MS: 365 (M + H). Anal. Calcd for
C17H12N6O4: C, 56.05; H, 3.32; N, 23.07. Found C,
55.93; H, 3.21; N, 22.96.
General procedure to prepare benzotriazolyl amino
quinoxalines carboxylates 23–25. Compounds in title were
synthesized by condensation of the ethyl 3-chloroquinoxaline-
2-carboxylate (7e) (0.78 mmol) with an equimolar amount
of the suitable diethyl 2-(1H-benzo[d][1,2,3]triazol-1(2)(3)-
yl)pentanedioate in refluxed ethanol (30mL) for 29–140h.
Progress of the reaction was monitored by TLC using
diethyl ether. The solution was evaporated to dryness in
vacuo, and the solid residue was purified by chromatography
on silica gel column, eluting with diethyl ether.
washed with ethanol, and dried.
Ethyl 2-(5-((3-methyl-1,4 dioxide-quinoxalin-2-yl)amino)-1H-
benzo[d][1,2,3]triazol-1-yl)acetate (28a). Yield 55%. Reflux
for 8h. Mp: 201–202°C. 1H-NMR (CDCl3): δ 9.25 (s, 1H,
NH), 8.58 (m, 2H, H-8′′, H-5′′), 7.87 (m, 1H, H-7′′), 7.77
(m, 1H, H-6′′), 7.64 (m, 2H, H-7′, H-4′), 7.37 (d, 1H,
J=8.8Hz, H-6′), 5.53 (s, 2H, CH2, C-1), 4.28 (q, 2H,
J=7.2Hz, OCH2–CH3), 2.31 (s, 3H, CH3, C-3′′), 1.31 (t,
3H, J=7.2Hz, OCH2–CH3). LC/MS: 395 (M+H). Anal.
Calcd for C19H18N6O4: C, 57.86; H, 4.60; N, 21.31. Found
Diethyl 2-(5-((3-(ethoxycarbonyl)quinoxalin-2-yl)amino)-1H-
benzo[d][1,2,3]triazol-1-yl)pentanedioate (23).
Yield 59%.
Reflux for 50h. Mp: 111–113°C. 1H-NMR (CDCl3): δ
10.59 (s, 1H, NH), 9.17 (s, 1H, H-4′), 7.07 (d, 1H,
J=10.2Hz, H-8′′), 7.89 (d, 1H, J=8.6Hz, H-5′′), 7.76
(m, 1H, H-7′′), 7.58 (m, 3H, H-6′′, H-7′ and H-6′), 5.76
(m, 1H, CH, C-2), 4.63 (q, 2H, J=7.2Hz, OCH2–CH3,
C-3′′), 4.24 (q, 2H, J=7.2Hz, OCH2–CH3, C-1), 4.10
(q, 2H, J=7.0Hz, OCH2–CH3, C-5), 2.78 (m, 2H, CH2,
C-3), 2.30 (m, 2H, CH2, C-4), 1.56 (t, 3H, J=7.0Hz,
OCH2–CH3, C-3′′), 1.22 (m, 6H, 2 OCH2–CH3). LC/MS:
521 (M+H). Anal. Calcd for C26H28N6O6: C, 59.99; H,
5.42; N, 16.14. Found C, 59.84; H, 5.39; N, 16.09.
C, 57.78; H, 4.56; N, 21.24.
Ethyl 2-(5-((3,7-dimethyl-1,4 dioxide-quinoxalin-2-yl)amino)-
1H-benzo[d][1,2,3]triazol-1-yl)acetate (28b). Yield 72%. Reflux
for 24 h. Mp: 185–186°C. 1H-NMR (CDCl3): δ 8.94 (s, 1H,
NH), 8.50 (d, 1H, J=8.4Hz, H-5′′), 8.36 (s, 1H, H-8′′),
7.69 (s, 1H, H-4′), 7.50 (m, 2H, H-7′ and H-6′′), 7.27 (d,
1H, J=8.6Hz, H-6′), 5.43 (s, 2H, CH2, C-1), 4.28 (q, 2H,
J=7.2Hz, OCH2–CH3), 2.63 (s, 3H, CH3, C-7′′), 2.29 (s,
3H, CH3, C-3′′), 1.29 (t, 3H, J=7.2Hz, OCH2–CH3).
LC/MS: 409 (M+ H). Anal. Calcd for C20H20N6O4: C,
58.82; H, 4.94; N, 20.58. Found C, 58.73; H, 4.93; N, 20.52.
Ethyl 2-(5-((7-chloro-3-methyl-1,4 dioxide quinoxalin-2-yl)amino)-
Diethyl 2-(5-((3-(ethoxycarbonyl)quinoxalin-2-yl)amino)-2H-
benzo[d][1,2,3]triazol-2-yl)pentanedioate (24).
Yield 57%.
1H-benzo[d][1,2,3]triazol-1-yl)acetate (28c).
Yield 62%.
1
1
Reflux for 29h. Mp: 96–97°C. H-NMR (CDCl3): δ 10.65
(s, 1H, NH), 9.16 (s, 1H, H-4′), 8.07 (d, 1H, J=8.4Hz, H-
8′′), 7.88 (m, 2H, H-5′′ and H-7′), 7.76 (m, 1H, H-7′′),
7.53 (m, 1H, H-6′′), 7.40 (d, 1H, J=8.6Hz, H-6′), 5.69 (m,
1H, CH, C-2), 4.63 (q, 2H, J=7.2Hz, OCH2–CH3, C-3′′),
4.19 (m, 4H, 2 OCH2–CH3, C-1 and C-5), 2.84 (m, 2H,
CH2, C-3), 2.33 (m, 2H, CH2, C-4), 1.55 (t, 3H, J=7.0Hz,
OCH2–CH3, C-3′′), 1.24 (m, 6H, 2 OCH2–CH3). LC/MS:
521 (M+H). Anal. Calcd for C26H28N6O6: C, 59.99; H,
5.42; N, 16.14. Found C, 59.83; H, 5.38; N, 16.06.
Reflux for 24h. Mp: 184–185°C. H-NMR (CDCl3): δ
9.12 (s, 1H, NH), 8.56 (m, 2H, H-5′′ and H-8′′), 7.69 (d,
1H, J= 9.4 Hz, H-6′′), 7.61 (d, 1H, J= 8.8 Hz, H-7′), 7.52
(s, 1H, H-4′), 7.33 (d, 1H, J= 8.6 Hz, H-6′), 5.48 (s, 2H,
CH2, C-1), 4.29 (q, 2H, J = 7.2 Hz, OCH2–CH3), 2.29 (s,
3H, CH3, C-3′′), 1.30 (t, 3H, J = 7.2 Hz, OCH2–CH3).
LC/MS: 429 (M+ H). Anal. Calcd for C19H17ClN6O4: C,
53.22; H, 4.00; Cl, 8.27; N, 19.60. Found C, 53.08; H,
3.93; Cl, 8.19; N, 19.44.
Ethyl 2-(5-((6-chloro-3-methyl-1,4 dioxide-quinoxalin-2-yl)amino)-
1H-benzo[d][1,2,3]triazol-1-yl)acetate (28d).
Yield 58%.
Diethyl 2-(6-((3-(ethoxycarbonyl)quinoxalin-2-yl)amino)-1H-
1
benzo[d][1,2,3]triazol-1-yl)pentanedioate (25).
Yield 54%.
Reflux for 24h. Mp: 218–219°C. H-NMR (CDCl3): δ
9.24 (s, 1H, NH), 8.53 (m, 2H, H-5′′ and H-8′′), 7.79
(d, 1H, J =9.2 Hz, H-6′′), 7.68 (s, 1H, H-4′), 7.59 (d, 1H,
J = 8.4 Hz, H-7′), 7.36 (d, 1H, J =7.0 Hz, H-6′), 5.51 (s,
2H, CH2, C-1), 4.29 (q, 2H, J =7.2 Hz, OCH2–CH3), 2.30
(s, 3H, CH3, C-3′′), 1.31 (t, 3H, J = 7.2 Hz, OCH2–CH3).
LC/MS: 429 (M+ H). Anal. Calcd for C19H17ClN6O4: C,
53.22; H, 4.00; Cl, 8.27; N, 19.60. Found C, 53.03; H,
Reflux for 140h. Mp: 98–100°C. 1H-NMR (CDCl3): δ
10.81 (s, 1H, NH), 9.06 (s, 1H, H-4′), 8.06 (m, 3H, H-8′′,
H-5′′ and H-7′), 7.81 (m, 1H, H-7′′), 7.57 (m, 1H, H-6′′),
7.35 (d, 1H, J=8.8Hz, H-6′), 5.83 (m, 1H, CH, C-2), 4.63
(q, 2H, J=7.0Hz, OCH2–CH3, C-3′′), 4.25 (q, 2H,
J=7.4Hz, OCH2–CH3, C-1), 4.08 (q, 2H, J=7.0Hz,
OCH2–CH3, C-5), 2.84 (m, 2H, CH2, C-3), 2.33 (m, 2H,
CH2, C-4), 1.56 (t, 3H, J=7.0Hz, OCH2–CH3, C-3′′), 1.17
(m, 6H, 2 OCH2–CH3). LC/MS: 521 (M+H). Anal. Calcd
for C26H28N6O6: C, 59.99; H, 5.42; N, 16.14. Found C,
59.86; H, 5.35; N, 16.09.
3.96; Cl, 8.23; N, 19.47.
Ethyl 2-(5-((7-ethoxy-6-fluoro-3-methyl-1,4 dioxide-quinoxalin-
2-yl)amino)-1H-benzo[d][1,2,3]triazol-1-yl)acetate (28e).
Yield
67%. Reflux for 12 h. Mp: 217–218°C. 1H-NMR (CDCl3): δ
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Vol 000
9.04 (s, 1H, NH), 8.25 (d, 1H, J=10.2Hz, H-5′′), 7.99 (d, 1H,
J=7.4Hz, H-7′), 7.69 (s, 1H, H-4′), 7.63 (d, 1H, J=9.8Hz,
H-8′′), 7.35 (d, 1H, J=7.6Hz, H-6′), 5.51 (s, 2H, CH2, C-
1), 4.32 (m, 4H, 2 OCH2–CH3), 2.28 (s, 3H, CH3, C-3′′),
1.58 (t, 3H, J=7.2Hz, OCH2–CH3). LC/MS: 457 (M+ H).
Anal. Calcd for C21H21FN6O5: C, 55.26; H, 4.64; F, 4.16;
J=8.6Hz, H-7′), 7.09 (d, 1H, J=8.8Hz, H-6′), 7.03 (s,
1H, H-4′), 5.32 (s, 2H, CH2, C-1), 4.18 (q, 2H, J=7.0Hz,
OCH2–CH3), 2.60 (s, 3H, CH3, C-7′′), 2.32 (s, 3H, CH3,
C-3′′), 1.23 (t, 3H, J=7.2Hz, OCH2–CH3). LC/MS: 409
(M+H). Anal. Calcd for C20H20N6O4: C, 58.82; H, 4.94;
N, 20.58. Found C, 58.67; H, 4.88; N, 20.47.
Ethyl 2-(5-((7-chloro-3-methyl-1,4 dioxide-quinoxalin-2-yl)
N, 18.41. Found C, 55.20; H, 4.59; F, 4.07; N, 18.29.
Ethyl 2-(5-((3-methyl-1,4 dioxide-quinoxalin-2-yl)amino)-
amino)-1H-benzo[d][1,2,3]triazol-3-yl)acetate (30c).
Yield
1
1H-benzo[d][1,2,3]triazol-1-yl)acetate (29a).
Yield 54%.
55%. Reflux for 24h. Mp: 215–216°C. H-NMR (CDCl3):
δ 9.43 (s, 1H, NH), 8.54 (m, 2H, H-5′′ and H-8′′), 7.97 (d,
1H, J=8.8Hz, H-6′′), 7.80 (d, 1H, J=9.2Hz, H-7′), 7.27
(d, 1H, J=8.6Hz, H-6′), 7.21 (s, 1H, H-4′), 5.47 (s, 2H,
CH2, C-1), 4.22 (q, 2H, J=7.2Hz, OCH2–CH3), 2.33 (s,
3H, CH3, C-3′′), 1.28 (t, 3H, J=7.2Hz, OCH2–CH3).
LC/MS: 429 (M+H). Anal. Calcd for C19H17ClN6O4: C,
53.22; H, 4.00; Cl, 8.27; N, 19.60. Found C, 53.14; H,
1
Reflux for 16h. Mp: 176–177°C. H-NMR (CDCl3): δ
8.87 (s, 1H, NH), 8.60 (m, 2H, H-8′′, H-5′′), 7.85 (m, 2H,
H-7′ and H-7′′), 7.72 (m, 1H, H-6′′), 7.27 (s, 1H, H-4′),
7.19 (d, 1H, J = 9.2 Hz, H-6′), 5.50 (s, 2H, CH2, C-1),
4.29 (q, 2H, J= 7.2 Hz, OCH2–CH3), 2.38 (s, 3H, CH3,
C-3′′), 1.30 (t, 3H, J =7.2 Hz, OCH2–CH3). LC/MS: 395
(M + H). Anal. Calcd for C19H18N6O4: C, 57.86; H, 4.60;
N, 21.31. Found C, 57.79; H, 4.55; N, 21.23.
Ethyl 2-(5-((3,7-dimethyl-1,4 dioxide-quinoxalin-2-yl)amino)-
3.93; Cl, 8.23; N, 19.49.
Ethyl 2-(5-((6-chloro-3-methyl-1,4 dioxide-quinoxalin-2-yl)
1H-benzo[d][1,2,3]triazol-2-yl)acetate (29b).
Yield 77%.
amino)-1H-benzo[d][1,2,3]triazol-3-yl)acetate (30d).
Yield
Reflux for 24h. Mp: 177–179°C. 1H-NMR (CDCl3): δ
8.93 (s, 1H, NH), 8.48 (d, 1H, J=8.6Hz, H-5′′), 8.36 (s,
1H, H-8′′), 7.87 (d, 1H, J=9.0, H-7′), 7.53 (d, 1H,
J=8.6Hz, H-6′′), 7.38 (s, 1H, H-4′), 7.22 (d, 1H,
J=9.2Hz, H-6′), 5.51 (s, 2H, CH2, C-1), 4.29 (q, 2H,
J=7.2Hz, OCH2–CH3), 2.62 (s, 3H, CH3, C-7′′), 2.36 (s,
3H, CH3, C-3′′), 1.30 (t, 3H, J=7.2Hz, OCH2–CH3).
LC/MS: 409 (M+H). Anal. Calcd for C20H20N6O4: C,
61%. Reflux for 24h. Mp: 203–204°C. H-NMR (CDCl3):
δ 9.15 (s, 1H, NH), 8.54 (m, 2H, H-5′′ and H-8′′), 8.02 (d,
1H, J=8.8Hz, H-6′′), 7.67 (d, 1H, J=9.2Hz, H-7′), 7.15
(m, 2H, H-4′ and H-6′), 5.40 (s, 2H, CH2, C-1), 4.23 (q,
2H, J=7.2Hz, OCH2–CH3), 2.32 (s, 3H, CH3, C-3′′), 1.28
(t, 3H, J=7.2Hz, OCH2–CH3). LC/MS: 429 (M+H).
Anal. Calcd for C19H17ClN6O4: C, 53.22; H, 4.00; Cl,
1
8.27; N, 19.60. Found C, 53.12; H, 3.93; Cl, 8.19; N, 19.47.
Ethyl 2-(5-((7-ethoxy-6-fluoro-3-methyl-1,4 dioxide-quinoxalin-
2-yl)amino)-1H-benzo[d][1,2,3]triazol-3-yl)acetate (30e).
58.82; H, 4.94; N, 20.58. Found C, 58.77; H, 4.87; N, 20.52.
Ethyl 2-(5-((7-ethoxy-6-fluoro-3-methyl-1,4 dioxide-quinoxalin-
Yield
40%. Reflux for 12 h. Mp: 212–213°C. 1H-NMR (CDCl3): δ
8.87 (s, 1H, NH), 8.60 (m, 2H, H-5′′ and H-8′′), 7.85 (m,
2H, H-7′ and H-7′′), 7.72 (m, 1H, H-6′′), 7.27 (s, 1H, H-4′),
7.19 (d, 1H, J=9.2Hz, H-6′), 5.50 (s, 2H, CH2, C-1), 4.29
(m, 4H, 2 OCH2–CH3), 2.38 (s, 3H, CH3, C-3′′), 1.30 (t,
3H, J=7.2Hz, OCH2–CH3). LC/MS: 457 (M+H). Anal.
Calcd for C21H21FN6O5: C, 55.26; H, 4.64; F, 4.16; N,
2-yl)amino)-1H-benzo[d][1,2,3]triazol-2-yl)acetate (29e).
Yield
66%. Reflux for 12 h. Mp: 221–222°C. 1H-NMR (CDCl3):
δ 8.69 (s, 1H, NH), 8.27 (d, 1H, J= 10.8 Hz, H-5′′), 7.96
(d, 1H, J =7.6 Hz, H-7′), 7.87 (d, 1H, J =9.2 Hz, H-8′′),
7.39 (s, 1H, H-4′), 7.17 (d, 1H, J = 8.6 Hz, H-6′), 5.48 (s,
2H, CH2, C-1), 4.31 (m, 4H, 2 OCH2–CH3), 2.33 (s, 3H,
CH3, C-3′′), 1.57 (t, 3H, J = 7.2 Hz, OCH2–CH3). LC/MS:
457 (M + H). Anal. Calcd for C21H21FN6O5: C, 55.26; H,
4.64; F, 4.16; N, 18.41. Found C, 55.13; H, 4.58; F, 4.08;
18.41. Found C, 55.15; H, 4.59; F, 4.12; N, 18.38.
General procedure to prepare diethyl 2-(5-((6,7-
substituted-3-methyl-1,4 dioxide-quinoxalin-2-yl)amino)-1H-
benzo[d][1,2,3]triazol-1-yl)pentanedioates 31a,c–e, 32a,c–e, and
33a,c–e. Title compounds were prepared by condensation of
N, 18.33.
Ethyl 2-(5-((3-methyl-1,4 dioxide-quinoxalin-2-yl)amino)-
1H-benzo[d][1,2,3]triazol-3-yl)acetate (30a).
Yied 54%.
1
the appropriate 2-chloro-3-methylquinoxaline 1,4-dioxides
(27a–e) (0.78 mmol) with an equimolar amount of the
suitable diethyl 2-(6-amino-1H-benzo[d][1,2,3]triazol-1(2)(3)-
yl)pentanedioates (14a–c) in refluxed ethanol (30 mL) for
23–120 h. Progress of the reaction was monitored by TLC
using diethyl ether/petroleum ether (1:1). After cooling to
rt, the EtOH solution was evaporated. The solid residue
obtained was purified by chromatography on silica gel,
Reflux for 16h. Mp: 164–166°C. H-NMR (CDCl3): δ
9.22 (s, 1H, NH), 8.55 (m, 2H, H-8′′ and H-5′′), 7.97 (d,
1H, J = 8.8Hz, H-7′), 7.85 (m, 1H, H-7′′), 7.73 (m, 1H,
H-6′′), 7.20 (d, 1H, J= 8.8 Hz, H-6′), 7.15 (s, 1H, H-4′),
5.41 (s, 2H, CH2, C-1), 4.20 (q, 2H, J = 7.2 Hz, OCH2–
CH3), 2.35 (s, 3H, CH3, C-3′′), 1.25 (t, 3H, J= 7.2 Hz,
OCH2–CH3). LC/MS: 395 (M +H). Anal. Calcd for
C19H18N6O4: C, 57.86; H, 4.60; N, 21.31. Found C,
eluting by ethyl ether to give the desired compounds.
57.78; H, 4.53; N, 21.24.
Ethyl 2-(5-((3,7-dimethyl-1,4 dioxide-quinoxalin-2-yl)amino)-
Diethyl 2-(5-((3-methyl-1,4 dioxide-quinoxalin-2-yl)amino)-
1H-benzo[d][1,2,3]triazol-1-yl)pentanedioate (31a).
Yield
1H-benzo[d][1,2,3]triazol-3-yl)acetate (30b).
Yield 81%.
Reflux for 24h. Mp: 158–160°C. 1H-NMR (CDCl3): δ
8.93 (s, 1H, NH), 8.40 (d, 1H, J=8.6Hz, H-5′′), 8.28 (s,
1H, H-8′′), 7.96 (d, 1H, J=8.6Hz, H-6′′), 7.50 (d, 1H,
31%. Reflux for 38h. Mp: 125–127°C. 1H-NMR
(CDCl3): δ 8.86 (s, 1H, NH), 8.61 (m, 2H, H-8′′ and H-5′
′), 7.87 (m, 1H, H-7′′), 7.73 (m, 2H, H-6′′ and H-4′), 7.58
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential
Anti-Folate Agents
Calcd for C24H26N6O6: C, 58.29; H, 5.30; N, 16.99.
Found C, 58.21; H, 5.25; N, 16.89.
(d, 1H, J = 8.8Hz, H-7′), 7.29 (d, 1H, J = 7.8 Hz, H-6′), 5.77
(m, 1H, CH, C-2), 4.24 (q, 2H, J = 7.2 Hz, OCH2–CH3, C-
1), 4.13 (q, 2H, J= 7.2 Hz, OCH2–CH3, C-5), 2.82 (m,
2H, CH2, C-3), 2.34 (m, 5H, CH2, C-4 and CH3, C-3′′),
1.22 (m, 6H, 2 OCH2–CH3). LC/MS: 495 (M +H). Anal.
Calcd for C24H26N6O6: C, 58.29; H, 5.30; N, 16.99.
Diethyl 2-(5-((6-chloro-3-methyl-1,4 dioxide-quinoxalin-2-
yl)amino)-1H-benzo[d][1,2,3]triazol-2-yl)pentanedioate
1
(32c). Yield 24%. Reflux for 25h. Mp: 111–113°C. H-
NMR (CDCl3): δ 8.89 (s, 1H, NH), 8.72 (s, 1H, H-5′′),
8.47 (s, 1H, H-4′), 7.81 (m, 2H, H-7′′ and H-8′′), 7.59 (d,
1H, J=8.8Hz, H-7′), 7.36 (d, 1H, J=8.8Hz, H-6′), 5.72
(m, 1H, CH, C-2), 4.21 (m, 4H, 2 OCH2–CH3), 2.85 (m,
2H, CH2, C-3), 2.74 (s, 3H, CH3, C-3′′), 2.33 (m, 2H, CH2,
C-4), 1.26 (m, 6H, 2 OCH2–CH3). LC/MS: 529 (M+H).
Anal. Calcd for C24H25ClN6O6: C, 54.50; H, 4.76; Cl, 6.70;
Found C, 58.25; H, 5.28; N, 16.89.
Diethyl 2-(5-((6-chloro-3-methyl-1,4 dioxide-quinoxalin-2-
yl)amino)-1H-benzo[d][1,2,3]triazol-1-yl)pentanedioate
1
(31c). Yield 56%. Reflux for 40 h. Mp: 122–124°C. H-
NMR (CDCl3): δ 8.82 (s, 1H, NH), 8.62 (s, 1H, H-5′′),
8.53 (d, 1H, J= 9.0 Hz, H-8′′), 7.79 (d, 1H, J= 8.8 Hz,
H-7′′), 7.72 (s, 1H, H-4′), 7.59 (d, 1H, J = 8.8 Hz, H-7′),
7.28 (d, 1H, J= 8.8 Hz, H-6′), 5.77 (m, 1H, CH, C-2),
4.24 (q, 2H, J =7.0 Hz, OCH2–CH3, C-1), 4.10 (q, 2H,
J =7.2 Hz, OCH2–CH3, C-5), 2.78 (m, 2H, CH2, C-3),
2.32 (m, 5H, CH2, C-4 and CH3, C-3′′), 1.22 (m, 6H, 2
OCH2–CH3). LC/MS: 529 (M + H). Anal. Calcd for
C24H25ClN6O6: C, 54.50; H, 4.76; Cl, 6.70; N, 15.89.
N, 15.89. Found C, 54.45; H, 4.72; Cl, 6.55; N, 15.80.
Diethyl 2-(5-((7-chloro-3-methyl-1,4 dioxide-quinoxalin-2-
yl)amino)-1H-benzo[d][1,2,3]triazol-2-yl)pentanedioate
(32d).
Yield 25%. Reflux for 26h. Mp: 157–158°C.
1H-NMR (CDCl3): δ 8.85 (s, 1H, NH), 8.56 (m, 2H, H-8′′
and H-5′′), 7.91 (d, 1H, J = 9.0 Hz, H-6′′), 7.64 (d, 1H,
J = 8.6 Hz, H-7′), 7.47 (s, 1H, H-4′), 7.19 (d, 1H,
J = 8.8 Hz, H-6′), 5.71 (m, 1H, CH, C-2), 4.25 (q, 2H,
J = 7.2 Hz, OCH2–CH3, C-1), 4.13 (q, 2H, J =7.0 Hz,
OCH2–CH3, C-5), 2.80 (m, 2H, CH2, C-3), 2.36 (s, 3H,
CH3, C-3′′), 2.31 (m, 2H, CH2, C-4), 1.21 (m, 6H, 2
OCH2–CH3). LC/MS: 529 (M + H). Anal. Calcd for
C24H25ClN6O6: C, 54.50; H, 4.76; Cl, 6.70; N, 15.89.
Found C, 54.47; H, 4.70; Cl, 6.56; N, 15.86.
Diethyl 2-(5-((7-chloro-3-methyl-1,4 dioxide-quinoxalin-2-
yl)amino)-1H-benzo[d][1,2,3]triazol-1-yl)pentanedioate
1
(31d). Yield 35%. Reflux for 26 h. Mp: 166–168°C. H-
NMR (CDCl3): δ 8.94 (s, 1H, NH), 8.55 (m, 2H, H-8′′
and H-5′′), 7.74 (s, 1H, H-4′), 7.62 (m, 2H, H-7 and H-6′
′), 7.29 (d, 1H, J =8.0 Hz, H-6′), 5.77 (m, 1H, CH, C-2),
4.25 (q, 2H, J =7.2 Hz, OCH2–CH3, C-1), 4.09 (q, 2H,
J =7.2 Hz, OCH2–CH3, C-5), 2.79 (m, 2H, CH2, C-3),
2.30 (m, 5H, CH2, C-4 and CH3, C-3′′), 1.26 (m, 6H, 2
OCH2–CH3). LC/MS: 529 (M +H). Anal. Calcd for
C24H25ClN6O6: C, 54.50; H, 4.76; Cl, 6.70; N, 15.89.
Found C, 54.59; H, 4.71; Cl, 6.65; N, 15.84.
Diethyl 2-(5-((7-ethoxy-6-fluoro-3-methyl-1,4 dioxide-
quinoxalin-2-yl)amino)-1H-benzo[d][1,2,3]triazol-2-yl)pentanedioate
1
(32e). Yield 26%. Reflux for 72h. Mp: 171–173°C. H-
NMR (CDCl3): δ 8.68 (s, 1H, NH), 8.30 (d, 1H,
J = 10.6Hz, H-5′′), 7.98 (d, 1H, J = 7.8 Hz, H-8′′), 7.90
(d, 1H, J= 9.0 Hz, H-7′), 7.42 (s, 1H, H-4′), 7.18 (d, 1H,
J = 8.6 Hz, H-6′), 5.71 (m, 1H, CH, C-2), 4.30 (m, 6H, 3
OCH2–CH3), 2.81 (m, 2H, CH2, C-3), 2.35 (m, 5H, CH2,
C-4 and CH3, C-3′′), 1.58 (m, 6H, 2 OCH2–CH3, C-1
and C-5), 1.25 (t, 3H, J= 7.2 Hz, OCH2–CH3, C-7′′).
LC/MS: 557 (M + H). Anal. Calcd for C26H29FN6O7: C,
56.11; H, 5.25; F, 3.41; N, 15.10. Found C, 56.09; H,
Found C, 54.48; H, 4.69; Cl, 6.65; N, 15.80.
Diethyl 2-(5-((7-ethoxy-6-fluoro-3-methyl-1,4 dioxide-quinoxalin-2-yl)
amino)-1H-benzo[d][1,2,3]triazol-1-yl)pentanedioate (31e). Yield
1
48%. Reflux for 96h. Mp: 191–193°C. H-NMR (CDCl3):
δ 8.71 (s, 1H, NH), 8.28 (d, 1H, J=10.8Hz, H-5′′), 7.97
(d, 1H, J=7.6Hz, H-8′′), 7.70 (s, 1H, H-4′), 7.57 (d, 1H,
J=8.8Hz, H-7′), 7.26 (d, 1H, J=8.6Hz, H-6′), 5.76 (m,
1H, CH, C-2), 4.29 (m, 4H, 2 OCH2–CH3, C-1 and C-5),
4.08 (q, 2H, J=7.2Hz, OCH2–CH3, C-7′′), 2.72 (m, 2H,
CH2, C-3), 2.33 (m, 2H, CH2, C-4), 2.29 (s, 3H, CH3, C-3′
′), 1.59 (m, 6H, 2 OCH2–CH3, C-1 and C-5), 1.22 (t, 3H,
J=7.2Hz, OCH2–CH3, C-7′′). LC/MS: 557 (M+H). Anal.
Calcd for C26H29FN6O7: C, 56.11; H, 5.25; F, 3.41; N,
5.23; F, 3.32; N, 15.08.
Diethyl 2-(5-((3-methyl-1,4 dioxide-quinoxalin-2-yl)amino)-
1H-benzo[d][1,2,3]triazol-3-yl)pentanedioate (33a).
Yield
54%. Reflux for 31h. Mp: 151–153°C. 1H-NMR
(CDCl3): δ 8.82 (s, 1H, NH), 8.62 (m, 2H, H-8′′ and
H-5′′), 8.07 (d, J= 9.2 Hz, H-7′), 7.87 (m, 2H, H-7′′),
7.75 (m, 1H, H-6′′),7.15 (m, 2H, H-4′ and H-6′), 5.59
(m, 1H, CH, C-2), 4.22 (q, 2H, J = 7.2 Hz, OCH2–CH3,
C-1), 4.07 (q, 2H, J = 7.0 Hz, OCH2–CH3, C-5), 2.72 (m,
2H, CH2, C-3), 2.37 (s, 3H, CH3, C-3′′), 2.26 (m, 2H,
CH2, C-4) 1.21 (m, 6H, 2 OCH2–CH3). LC/MS: 495 (M
+ H). Anal. Calcd for C24H26N6O6: C, 58.29; H, 5.30; N,
15.10. Found C, 56.02; H, 5.19; F, 3.36; N, 15.05.
Diethyl 2-(5-((3-methyl-1,4 dioxide-quinoxalin-2-yl)amino)-
1H-benzo[d][1,2,3]triazol-2-yl)pentanedioate (32a).
Yield
34%. Reflux for 23 h. Mp: 123–125°C. 1H-NMR
(CDCl3): δ 8.78 (s, 1H, NH), 8.61 (m, 2H, H-8′′ and
H-5′′), 7.87 (m, 2H, H-7′ and H-7′′), 7.43 (s, 1H, H-4′),
7.29 (m, 1H, H-6′′), 7.18 (d, 1H, J = 8.0 Hz, H-6′), 5.69
(m, 1H, CH, C-2), 4.24 (q, 2H, J =7.2 Hz, OCH2–CH3,
C-1), 4.13 (q, 2H, J = 7.2 Hz, OCH2–CH3, C-5), 2.81 (m,
2H, CH2, C-3), 2.32 (m, 5H, CH2, C-4 and CH3, C-3′′),
1.24 (m, 6H, 2 OCH2–CH3). LC/MS: 495 (M+ H). Anal.
16.99. Found C, 58.23; H, 5.26; N, 16.92.
Diethyl 2-(5-((6-chloro-3-methyl-1,4 dioxide-quinoxalin-2-
yl)amino)-1H-benzo[d][1,2,3]triazol-3-yl)pentanedioate
1
(33c). Yield 44%. Reflux for 36h. Mp: 114–116°C. H-
NMR (CDCl3): δ 8.81 (s, 1H, NH), 8.63 (s, 1H, H-5′′),
8.53 (d, 1H, J =8.2 Hz, H-8′′), 8.07 (d, 1H, J= 8.4Hz, H-
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

I. Briguglio, S. Piras, P. Corona, M. A. Pirisi, L. Burrai, G. Boatto, E. Gavini, and G. Rassu
Vol 000
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Busonera, B.; Collu, G.; Loddo, R. Med Chem 2006, 2, 113.
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7′′), 7.77 (d, 1H, J= 9.0 Hz, H-7′), 7.14 (m, 2H, H-4′ and
H-6′), 5.71 (m, 1H, CH, C-2), 4.17 (m, 4H, 2 OCH2–
CH3), 2.71 (m, 2H, CH2, C-3), 2.35 (s, 3H, CH3, C-3′′),
2.29 (m, 2H, CH2, C-4), 1.23 (m, 6H, 2 OCH2–CH3).
LC/MS: 529 (M + H). Anal. Calcd for C24H25ClN6O6: C,
54.50; H, 4.76; Cl, 6.70; N, 15.89. Found C, 54.44; H,
4.70; Cl, 6.64; N, 15.85.
Diethyl 2-(5-((7-chloro-3-methyl-1,4 dioxide-quinoxalin-2-
yl)amino)-1H-benzo[d][1,2,3]triazol-3-yl)pentanedioate
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1996, 51, 559.
1
(33d). Yield 35%. Reflux for 24h. Mp: 161–163°C. H-
NMR (CDCl3): δ 8.89 (s, 1H, NH), 8.56 (m, 2H, H-5′′
and H-8′′), 8.07 (d, 1H, J=9.0Hz, H-67′′), 7.66 (d, 1H,
J=7.4Hz, H-7′), 7.14 (m, 2H, H-4′ and H-6′), 5.71 (m,
1H, CH, C-2), 4.22 (q, 2H, J=7.0Hz, OCH2–CH3, C-1),
4.07 (q, 2H, J=7.2Hz, OCH2–CH3, C-5), 2.72 (m, 2H,
CH2, C-3), 2.33 (s, 3H, CH3, C-3′′), 2.26 (m, 2H, CH2, C-4),
1.22 (m, 6H, 2 OCH2–CH3). LC/MS: 529 (M+ H). Anal.
Calcd for C24H25ClN6O6: C, 54.50; H, 4.76; Cl, 6.70; N,
[22] Piras, S.; Loriga, M.; Paglietti, G.; Demontis, M. P.; Varoni,
M. P.; Fattacio, M. C.; Anania, V. Farmaco Sci 1996, 51, 569.
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15.89. Found C, 54.46; H, 4.70; Cl, 6.61; N, 15.82.
Diethyl 2-(5-((7-ethoxy-6-fluoro-3-methyl-1,4 dioxide-quinoxalin-
2-yl)amino)-1H-benzo[d][1,2,3]triazol-3-yl)pentanedioate (33e).
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1
Yield 53%. Reflux for 120 h. Mp: 140–142°C. H-NMR
(CDCl3): δ 8.87 (s, 1H, NH), 8.29 (d, 1H, J= 10.6Hz, H-
5′′), 8.05 (d, 1H, J = 9.4 Hz, H-7′), 7.96 (d, 1H, J= 7.4 Hz,
H-8′′), 7.12 (m, 2H, H-4′ and H-6′), 5.69 (m, 1H, CH, C-2),
4.29 (m, 4H, 2 OCH2–CH3, C-1 and C-5), 4.07 (q, 2H,
J=7.0Hz, OCH2–CH3, C-7′′), 2.72 (m, 2H, CH2, C-3),
2.33 (s, 3H, CH3, C-3′′), 2.26 (m, 2H, CH2, C-4), 1.59
(m, 6H, 2 OCH2–CH3, C-1 and C-5), 1.21 (t, 3H,
J =7.0 Hz, OCH2–CH3, C-7′′). LC/MS: 557 (M + H).
Anal. Calcd for C26H29FN6O7: C, 56.11; H, 5.25; F, 3.41;
N, 15.10. Found C, 56.03; H, 5.23; F, 3.36; N, 15.01.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2015
2-(Quinoxalin-2-ylamino-benzotriazolyl) Pentanedioic Derivatives as Potential
Anti-Folate Agents
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet