Direct oxidative C–H amination of quinoxalinones under copper-organic framework catalysis

Article abstract of DOI:10.1016/j.catcom.2017.07.012

A copper-organic framework Cu-CPO-27 was synthesized, and utilized as a recyclable heterogeneous catalyst for the direct C–H amination of quinoxalin-2(1H)-ones with amines to produce 3-aminoquinoxalin-2(1H)-ones. High yields were achieved in the presence of molecular oxygen as the oxidant. This framework was more catalytically active than a number of MOF-based catalysts. The Cu-CPO-27 also displayed higher performance than CuFe₂O₄ nanoparticles. The copper-organic framework catalyst could be reutilized in the synthesis of 3-aminoquinoxalin-2(1H)-ones via the direct C–H amination reaction without a remarkable deterioration in catalytic performance. To our best knowledge, this is the first heterogeneous catalytic protocol to generate 3-aminoquinoxalin-2(1H)-ones.

Full text of DOI:10.1016/j.catcom.2017.07.012

Accepted Manuscript
Direct oxidative C-H amination of quinoxalinones under copper-
organic framework catalysis
Thanh T. Hoang, Tuong A. To, Vi T.T. Cao, Anh T. Nguyen, Tung
T. Nguyen, Nam T.S. Phan
PII:
DOI:
Reference:
S1566-7367(17)30305-9
doi: 10.1016/j.catcom.2017.07.012
CATCOM 5131
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
18 May 2017
17 July 2017
17 July 2017
Please cite this article as: Thanh T. Hoang, Tuong A. To, Vi T.T. Cao, Anh T. Nguyen,
Tung T. Nguyen, Nam T.S. Phan , Direct oxidative C-H amination of quinoxalinones
under copper-organic framework catalysis. The address for the corresponding author was
captured as affiliation for all authors. Please check if appropriate. Catcom(2017), doi:
10.1016/j.catcom.2017.07.012
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ACCEPTED MANUSCRIPT
Direct oxidative C-H amination of quinoxalinones under copper-organic framework
catalysis
Thanh T. Hoang, Tuong A. To, Vi T. T. Cao, Anh T. Nguyen, Tung T. Nguyen, Nam T. S.
Phan*
Faculty of Chemical Engineering, HCMC University of Technology, VNU-HCM,
268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Viet Nam
*Email: ptsnam@hcmut.edu.vn
Ph: (+84 8) 38647256 ext. 5681 Fx: (+84 8) 38637504

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Abstract
A copper-organic framework Cu-CPO-27 was synthesized, and utilized as a recyclable
heterogeneous catalyst for the direct C-H amination of quinoxalin-2(1H)-ones with amines to
produce 3-aminoquinoxalin-2(1H)-ones. High yields were achieved in the presence of molecular
oxygen as the oxidant. This framework was more catalytically active than a number of MOF-
based catalysts. The Cu-CPO-27 also displayed higher performance than CuFe2O4 nanoparticles.
The copper-organic framework catalyst could be reutilized in the synthesis of 3-
aminoquinoxalin-2(1H)-ones via the direct C-H amination reaction
without a remarkable
deterioration in catalytic performance. To our best knowledge, this is the first heterogeneous
catalytic protocol to generate 3-aminoquinoxalin-2(1H)-ones.
Keywords: Quinoxalinones; amination; C-H activation; copper; metal-organic frameworks.

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1. Introduction
Quinoxalinone derivatives have emerged as essential intermediates for the synthesis of
innumerable compounds with potentially valuable biological activities, thus attracting enormous
interests in agricultural and pharmaceutical industries as well as in materials science [1-4]. Over
last decades, transition metal-catalyzed organic transformations have been considered as an
influential approach for the generation of numerous molecular skeletons [5, 6]. Nevertheless, the
presence of two active functional groups in both starting materials was required [7, 8]. In this
context, reactions proceeded via direct C-H bond activation should be explored since synthetic
steps could be minimized. Following pioneering reports by Hartwig, Buchwald and co-workers
[9, 10], reactions via direct C-N bond formation utilizing transition metal catalysts have allured
considerable attention [11]. Indeed, palladium- [12, 13], rhodium- [14, 15], and ruthenium [16]-
catalyzed direct coupling transformations were previously reported. Recently, Cui and co-
workers demonstrated a Cu(OAc)2-catalyzed direct oxidative C-H amination of quinoxalin-
2(1H)-ones utilizing both secondary and primary amines as the nitrogen sources [17]. Although
fascinating results were obtained, the homogeneous copper catalyst could not be reutilized.
Therefore, the development of more environmentally benign protocols for the synthesis of
quinoxalinone derivatives is still the target of further investigation in the near future.
Metal-organic frameworks (MOFs) have turned up as intriguing series of crystalline materials,
consisting of metal cations interconnected by multifunctionalized organic ligands during a self-
assembly procedure [18-20]. Potential applications of these networks have expanded from gas
capture and storage to other domains such as catalysis, conductivity, chemical sensors,

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optoelectronics, biomedical imaging, drug storage and delivery [21, 22]. Nevertheless, studies
on catalytic applications of MOFs are still somewhat delaying behind other domains. Several
attempts have been accomplished to explore the possibility of utilizing MOFs as heterogeneous
catalysts, and indeed, this special subject is highly fascinating to the catalysis community. All
over the last few years, large numbers of organic reactions conducted utilizing MOFs-based
catalysts have been declared in the literature [23-30]. Cu-CPO-27, a honeycomb-like MOF based
on the coordination of tetradeprotonated 2,5-dihydroxy-terephthalic acid moieties to Cu(II) ions,
was previously investigated by Farha [31], Sanz [32], Martínez [33] and co-workers. In this
manuscript, we would like to illustrate an efficient access to 3-aminoquinoxalin-2(1H)-ones via
direct oxidative C-H amination transformation under Cu-CPO-27 catalysis. To the best of our
knowledge, this synthetic route was not previously conducted under heterogeneous catalysis
conditions.
2. Experimental
The copper-based framework was prepared from dihydroxyterephthalic acid and copper nitrate
trihydrate using a literature approach [31-33], and was characterized by traditional analysis
methods (see Supporting information). In a representative experiment, a solution of quinoxalin-
2(1H)-one (0.029 g, 0.20 mmol), morpholine (0.035 g, 0.40 mmol), and diphenyl ether (0.034 g,
0.20 mmol) as an internal standard in dimethylacetamide (1 mL) was added into a 8 mL screw-
cap vial. Pre-calculated amount of Cu-CPO-27 catalyst was then introduce to the vial. The
catalyst quantity was enumerated with reference to the copper/quinoxalin-2(1H)-one molar ratio.
o
The reaction mixture was magnetically stirred at 80 C for 16 h under an oxygen atmosphere.

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The reaction yield was determined by withdrawing samples from the reaction mixture, and
quenching with brine (1 mL). The organic compounds were subsequently extracted into ethyl
acetate phase (3 mL), dried utilizing anhydrous Na2SO4, and analyzed by GC regarding diphenyl
ether. The product of the reaction was purified by column chromatography. 1H NMR, 13C NMR,
and GC-MS analyses were conducted to validate the identity of the product.
3. Results and discussion
Cu-CPO-27:
O
N
N
N
O
Cu-CPO-27
O
+
HN
DMA, 80 oC, 16h, O2
N
H
O
N
H
Scheme 1. The direct C-H amination of quinoxalin-2(1H)-one with morpholine utilizing Cu-
CPO-27 catalyst.
The copper-based framework was utilized as heterogeneous catalyst for the direct C-H amination
of quinoxalin-2(1H)-one with morpholine to produce 3-morpholinoquinoxalin-2(1H)-one as the

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major product (Scheme 1). Cui and co-workers previously demonstrated that the reaction should
be carried out at 100 oC [17]. Therefore, the impact of temperature on the yield of 3-
morpholinoquinoxalin-2(1H)-one was investigated (Entry 1-7, Table 1). The reaction was
conducted at 5 mol% catalyst in DMA for 16 h under an oxygen atmosphere, with 1.5
o
o
o
o
o
o
equivalents of morpholine, at room temperature, 60 C, 70 C, 80 C, 90 C, 100 C, 110 C, and
o
120 C, respectively. No product was detected for the reaction carried out at room temperature.
o
Performing the experiment at 60 C afforded 56% yield after 16 h, while this value was enhanced
o
to 69% for the reaction conducted at 70 C. The yield of the desired product was upgraded to
o
o
74% when the temperature was extended to 80 C. Elevating the temperature to more than 80 C
was not necessary, since the yield was not improved noticeably. Increasing the temperature to
o
120 C exhibited a negative effect on the transformation, with only 53% yield of the major
o
product being probed. Indeed, GC-MS analysis of the reaction mixture at 120 C indicated the
presence of morpholine-4-carbaldehyde, probably due to the decomposition of product at high
temperature. Moreover, 1-morpholinoethanone was also detected, showing that the
transamidation between morpholine and dimethylacetamide might occur under this condition.
This by-reaction reduced the amount of morpholine, thus, reducing the yield of 3-
morpholinoquinoxalin-2(1H)-one.
Table 1. Screening the reaction conditionsa.
Entry
1
Temperature
Solvent
DMA
Reactant
molar ratio
1:1.5
Catalyst amount
Yield (%)
56
(oC)
60
(mol%)
5

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2
3
4
5
6
7
70
80
DMA
DMA
DMA
DMA
DMA
DMA
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
5
5
5
5
5
5
69
74
74
72
71
53
90
100
110
120
8
80
80
80
80
80
80
80
80
80
80
80
80
80
80
DMSO
DMPU
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
1:1.5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
76
56
74
73
61
41
12
18
26
10
3
9
10
11
12
13
14
15
16
17
18
19
20
21
DMA
DMF
NMP
Acetonitrile
n-Butanol
DEG
Water
Dioxane
Dichlorobenzene
Dichloroethane
Toluene
2
2
Xylene
2
22
80
DMA
1.5:1
5
44

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23
24
25
26
27
80
80
80
80
80
DMA
DMA
DMA
DMA
DMA
1.25:1
1:1
5
5
5
5
5
45
45
54
74
80
1:1.25
1:1.5
1:2
28
29
30
31
32
33
34
35
36
80
80
80
80
80
80
80
80
80
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
DMA
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
0
1
1
43
59
75
77
80
81
84
84
2
3
4
5
6
8
10
a
The direct C-H amination of quinoxalin-2(1H)-one with morpholine to produce 3-
morpholinoquinoxalin-2(1H)-one was used as model reaction. Quinoxalin-2(1H)-one (0.2
o
mmol), solvent (1 ml), 80 C, under an oxygen atmosphere, 16 h. DMA: Dimethylacetamide;
DMSO: Dimethyl sulfoxide; DMPU: 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone;
DMF: N,N’-dimethylformamide; DEG: Diethylene glycol.

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Since the reaction was conducted in liquid phase, the nature of solvent might display a notable
impact on the transformation. We then explored the influence of solvent on the yield of 3-
morpholinoquinoxalin-2(1H)-one (Entry 8-21, Table 1). It was noticed that dichlorobenzene,
dichloroethane, toluene, and p-xylene were entirely inappropriate for this reaction, with less than
5% yield of the expected product being recorded. Similarly, n-butanol, diethylene glycol, water,
and dioxane should not be utilized as solvent for this transformation. The yield was improved to
41%, 56%, and 61% for the reaction performed in acetonitrile, DMPU, and NMP, respectively.
Among these solvents, DMSO, DMA, and DMF emerged as suitable solvent for the reaction,
producing the desired product in 76%, 74%, and 73% yields, respectively. Although DMSO
offered best yield, its high viscosity made this solvent less desirable for the catalyst recovery and
recycling. Therefore, DMA was utilized as solvent for the transformation in further studies.
Another factor that should be studied is the reactant molar ratio (Entry 22-27, Table 1).
Previously, Cui and co-workers employed 3 equivalents of amine for this transformation [17].
The reaction utilizing
1
equivalent of morpholine proceeded slowly, generating 3-
morpholinoquinoxalin-2(1H)-one in 45% yield. Employing excess quinoxalin-2(1H)-one was
noted to be inappropriate. Experimental data revealed that this transformation was favored when
excess amine was used. Certainly, extending the amount of morpholine to 1.25 equivalents led to
54% yield of the desired product being obtained. As previously noted, the transformation
utilizing 1.5 equivalents of morpholine progressed to 74% yield. This value could be upgraded to
80% in the presence of 2 equivalents of morpholine. As inspired by green chemistry principles, a
large excess of reactants should be avoided. Therefore, more than 2 equivalents of morpholine
was not employed.

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Having these data in mind, we subsequently investigate the influence of catalyst concentration on
the reaction (Entry 28-36). Only 1% yield was probed in the absence of the copper-based
framework catalyst, implying the importance of copper site for this transformation. The yield of
the expected product was amended noticeably to 43% when 1 mol% catalyst was employed for
the reaction. Extending the amount of the catalyst led to a remarkable improvement in the
reaction yield. Increasing the catalyst quantity to 4 mol% resulted in 77% yield being recorded
after 16 h. As previously noted, when 5 mol% catalyst was utilized for the reaction, 80% yield of
the major product was achieved. This value could be amended to 81% for the case of 6 mol%
catalyst. It was noticed that 84% yield of the desired product was obtained for the reaction
utilizing 8 mol% catalyst. Employing more than 8 mol% catalyst was noted to be redundant since
the reaction yield was not enhanced considerably.
As the reaction was performed in solution phase, it must be important to investigate the
potentiality that the solid catalyst might be partially decomposed, leading to the leaching of
active sites into solution during the catalytic transformation. In order to clarify if active copper
species dissolved from the copper-based framework catalyst were active for the reaction, a
control experiment was subsequently performed. After the initial 4 h reaction period with 37%
yield being analyzed, the copper-organic framework catalyst was separated from the reactor by
o
centrifugation. The solution phase was afterwards shifted to a new reactor, and heated at 80 C
with magnetic stirring for an extra 12 h. It was noticed that under this condition, almost no
further 3-morpholinoquinoxalin-2(1H)-one was generated after the isolation of the solid
framework catalyst. Furthermore, ICP analysis of the filtrate indicated that approximately 2

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mol% of copper (calculated regarding the total amount of copper in the catalyst) was dissolved
into the liquid phase during the course of the reaction. However, these copper species did not
contribute significantly to the catalytic transformation.
These data would verify that the
transformation progressed under heterogeneous catalysis, and yield was only possible in the
presence of the copper-organic framework.
To acquire understanding into the pathway of the transformation, additional mechanistic
experiments were subsequently performed. Initially, the transformation was carried out under an
argon atmosphere. Only 4% yield of 3-morpholinoquinoxalin-2(1H)-one was obtained. Next, the
reaction was executed under air for 16 h. The direct C-H amination transformation was
remarkably accelerated in the presence of air, producing the desired product in 32% yield. Under
an oxygen atmosphere, the yield was considerably improved to 84%. These data confirmed that
oxygen as oxidant should be essential for the transformation. The reaction was also performed
under an oxygen atmosphere in the presence of ascorbic acid as an antioxidant. Experimental
data displayed that the reaction was noticeably affected by the antioxidant, with only 2% yield
being recorded. Based on these observations and the literature [17, 34, 35], the reaction
mechanism was proposed in Scheme 2. Initially, deprotonation of quinoxalin-2(1H)-one formed
pyridinocopper(II) species, probably due to acidity of C-H bond  to nitrogen [34, 35].
Subsequently, oxidation of copper(II) by oxygen generated copper(III) species, which would
undergo nucleophilic substitution with morpholine to yield aminocopper(III) species. Reductive
elimination followed by single-electron oxidation regenerated the original catalyst. However,
further studies are needed to clarify the transformation pathway.

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Scheme 2. Proposed mechanism for the direct C-H amination reaction.
To underline the benefit of utilizing the Cu-CPO-27, its catalytic activity was compared to that of
other MOF-based catalysts (see Supporting Information for synthesis procedures) (Fig. 1). It
should be noticed that 8 mol% catalyst was utilized for all cases. Fe-MOF-235 and
Ni2(BDC)2(DABCO) were entirely inactive towards the direct C-H amination reaction, affording
3-morpholinoquinoxalin-2(1H)-one in only 1% yield. Similarly, Co-ZIF-67 was also
inappropriate for this transformation, with 17% yield being detected. As anticipated, copper-
organic frameworks displayed better catalytic efficiency than Fe-, Ni-, and Co-based MOFs. The
reaction utilizing Cu3(BTC)2 catalyst progressed slowly, producing the expected product in 39%
yield. Cu(BDC) was observed to be more active towards the reaction than Cu3(BTC)2, with 47%

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yield being recorded. Cu2(BDC)2(DABCO) expressed better exhibition, and 63% yield was
obtained for the reaction. Compared to these MOFs, Cu-CPO-27 emerged to be more
catalytically active for the direct C-H amination reaction. Certainly, the reaction using Cu-CPO-
27 catalyst offered 84% yield. Moreover, CuFe2O4 nanoparticles were also tested as catalyst for
this reaction, and only 28% yield of the desired product was detected.
100
80
60
40
20
0
5
7
2O4
F-6
BTC)2
Cu(BDC)
CuFe
-MOF-23Co-ZI
Fe
Cu3(
Cu-CPO-27
BDC)2(DABCO)
Cu2(
Ni2(BDC)2(DABCO)
Catalyst
Fig. 1. Yields of 3-morpholinoquinoxalin-2(1H)-one vs catalyst.

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100
80
60
40
20
0
1
2
3
4
5
Catalytic run
Fig. 2. Catalyst reutilizing studies.
As motivated by green chemistry principles, one point that must be investigated is the comfort of
reutilizing this Cu-MOF catalyst. The copper-organic framework catalyst was consequently
studied for reusability in the transformation over 5 consecutive runs, by isolating the Cu-MOF
from the reaction mixture after each experiment, washing it thoroughly, and afterwards
reutilizing it. At the end of each catalytic run, the catalyst was collected, washed with a large
o
amount of dimethylformamide and methanol, dried under vacuum on a Shlenk line at 150 C for
2 h, and reutilized for new experiments. Experimental data demonstrated that it was possible to
reutilize the framework catalyst numerous times without a noteworthy deterioration in catalytic
efficiency. Certainly, 86% yield of 3-morpholinoquinoxalin-2(1H)-one was obtained in the 5th
run with the recovered catalyst (Fig. 2). In addition, the recovered framework catalyst was
characterized by FT-IR and XRD. The FT-IR spectra of the reutilized Cu-MOF displayed an
absorption band comparable to the new framework (Fig. S7). XRD analysis disclosed that the

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catalyst crystallinity was maintained during the experiment, although a slight difference was
detected for the reutilized framework (Fig. 3).
10000
8000
6000
(a)
4000
2000
(b)
0
5
10
15
20
25
30
2-Theta (degree)
Fig. 3. XRD results of the new (a) and reutilized (b) Cu-CPO-27.
Table 2. Synthesis of quinoxalinone derivatives via direct C-H amination reaction utilizing Cu-
CPO-27 catalysta.
Entry
1
Reactant 1
Reactant 2
Product
Yield (%)
82
N
O
O
N
N
O
HN
N
H
O
N
H

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N
2
3
4
83
89
78
N
N
O
HN
N
H
O
O
N
H
N
N
N
HN
N
H
N
O
H
N
N
N
HN
N
O
H
N
H
O
N
5
6
56
42
N
N
O
HN
N
H
O
N
H
N
N
N
HN
O2N
N
H
O
O2N
N
O
H
N
N
7
8
76
72
N
N
N
O
HN
O
N
N
N
N
HN
O
N
O

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N
N
9
89
O
O
N
N
N
O
HN
O
N
10
11
12
Trace
65b
N
O
N
HN
N
H
O
O
O
N
H
N
N
N
O
HN
N
H
N
H
71b
N
N
H2N
H
N
N
N
O
76b
61b
N
H
13
14
H2N
N
N
N
H
O
O
N
H
O
N
H
N
N
H2N
N
H
N
H
O
N
H2N
H
15
Trace
N
N
N
H
O
O
N
O
O
H

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a
Quinoxalin-2(1H)-one (0.2 mmol), amine (0. 4 mmol), Cu-CPO-27 ( 8 mol%), DMA (1 ml), 80
b
oC, under an oxygen atmosphere, 16 h. The reaction was carried out for 24 h, in the presence of
3 equivalents of amine.
The research scope was consequently developed to the generation of many quinoxalinone
derivatives via direct C-H amination reaction utilizing Cu-CPO-27 catalyst (Table 2). Following
this protocol, 3-morpholinoquinoxalin-2(1H)-one was obtained in 82% isolated yield (Entry 1).
Piperidine displayed similar performance, producing 3-(piperidin-1-yl)quinoxalin-2(1H)-one in
83% yield (Entry 2). 4-Methylpiperidine was more reactive towards the transformation, with
89% yield of 3-(4-methylpiperidin-1-yl)quinoxalin-2(1H)-one being accomplished (Entry 3). 7-
Methyl-3-(4-methylpiperidin-1-yl)quinoxalin-2(1H)-one was formed in 78% yield (Entry 4).
Compared with piperidine, pyrrolidine expressed considerable lower reactivity in the reaction
(Entry 5). The presence of nitro group in quinoxalin-2(1H)-one remarkably disfavored the
reaction, and only 42% yield of 3-(4-methylpiperidin-1-yl)-7-nitroquinoxalin-2(1H)-one was
recorded (Entry 6). 1-Butylquinoxalin-2(1H)-one was also used, and the reaction progressed to
76% yield of 1-butyl-3-(piperidin-1-yl)quinoxalin-2(1H)-one (Entry 7) and 72% yield of 1-butyl-
3-(4-methylpiperidin-1-yl)quinoxalin-2(1H)-one (Entry 8). Morpholine was noted to be slightly
more reactive, and the reaction produced 89% yield of 1-butyl-3-morpholinoquinoxalin-2(1H)-
one (Entry 9). It was found that noncyclic secondary amines was significantly less reactive than
cyclic amines. The reaction between quinoxalin-2(1H)-one and dibutylamine afforded 3-
(dibutylamino)quinoxalin-2(1H)-one in trace amount (Entry 10). GC-MS analysis of the reaction
mixture indicated the presence of N,N-dibutylacetamide owing to the transamidation between
dibutylamine and dimethylacetamide. Similarly, diethylamine was totally unreactive.

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Interestingly, N-methyl benzylamine could react with quinoxalin-2(1H)-one, producing
3-
(benzyl(methyl)amino)quinoxalin-2(1H)-one in 65% yield (Entry 11). Primary amines could be
the nitrogen sources for the transformation. Indeed, 1-butyl-3-(cyclohexylamino)quinoxalin-
2(1H)-one
(Entry
12),
3-(butylamino)quinoxalin-2(1H)-one
(Entry
13),
and
3-
(benzylamino)quinoxalin-2(1H)-one (Entry 14) were generated in 71%, 76%, and 61% yields,
respectively. It was also noted that aromatic amines were unreactive in this direct C-H amination
reaction (Entry 15). GC-MS analysis of the reaction mixture revealed that (E)-1,2-bis(4-
methoxyphenyl)diazene was produced via the self-coupling of 4-methoxyaniline, while
quinoxalin-2(1H)-one was almost recovered.
4. Conclusions
Copper-organic framework Cu-CPO-27 was synthesized, and used as an effective heterogeneous
catalyst for the synthesis of 3-aminoquinoxalin-2(1H)-ones via direct oxidative C-H amination
transformation. The Cu-CPO-27 emerged to be more catalytically active for the reaction than a
number of MOF-based catalysts. This copper-based MOFs also displayed higher performance
than CuFe2O4 nanoparticles. The reaction using the copper-based framework catalyst was
considerably regulated by the solvent. The synthesis of 3-aminoquinoxalin-2(1H)-ones utilizing
the framework catalyst progressed under real heterogeneous catalysis, and yield was only
possible in the presence of the copper-organic framework. It was possible to reutilize the catalyst
for the reaction numerous times without a noteworthy deterioration in catalytic efficiency. The
advantages that quinoxalinone derivatives could be generated via the direct C-H amination
reaction in the presence of a recyclable catalyst would be appealing to the chemical industry.

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Acknowledgements
The Vietnam National University – Ho Chi Minh City (VNU-HCM) is acknowledged for
financial support via Project No. B2017-20-08. Dr Thach N. Tu (INOMAR Center, VNU-HCM)
is acknowledged for drawing catalyst structure.
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Graphical abstract
O
N
O
N
N
DMA, 80 oC
16h, O2
N
O
HN
H
+
O
HN
Cu-CPO-27:

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Research Highlights
 Cu-CPO-27 was used as catalyst for synthesis of 3-aminoquinoxalin-2(1H)-ones.
 Excellent yields were obtained.
 The catalyst could be recovered and reused.