A modified synthesis of some novel polycyclic aromatic phenazines and quinoxalines by using the tungstate sulfuric acid (TSA) as a reusable catalyst under solvent-free conditions

Article abstract of DOI:10.1002/jccs.201100421

Considering the synthesis of new compounds, we developed heterocyclic chemistry. We also helped to improve the classical synthetic route for the synthesis of quinoxalines and phenazines through implement in terms of solvent-free reaction. For the condensa

Full text of DOI:10.1002/jccs.201100421

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
A Modified Synthesis of Some Novel Polycyclic Aromatic Phenazines and
Quinoxalines by Using the Tungstate Sulfuric Acid (TSA) as a Reusable Catalyst
under Solvent-free Conditions
Bahador Karami,a* Saeed Khodabakhshib and Marzieh Nikroozb
aDepartment of Chemistry, Yasouj University, Yasouj, Zip Code: 75918-74831 P.O. Box 353, Iran
bIslamic Azad University, Gachsaran Branch, Gachsaran, 75817, Iran
(Received Jul. 6, 2011; Accepted Aug. 31, 2011; Published Online Sept. 5, 2011; DOI: 10.1002/jccs.201100421)
Considering the synthesis of new compounds, we developed heterocyclic chemistry. We also helped to
improve the classical synthetic route for the synthesis of quinoxalines and phenazines through implement
in terms of solvent-free reaction. For the condensation of 1,2-dicarbonyls and o-phenylenediamines under
solvent-free conditions at room temperature, tungstate sulfuric acid (TSA) was found to be an efficient
and reusable reagent. The high yield of the pure products and simple preparation of the catalyst have al-
lowed the synthesis of several phenazines and quinoxalines using this methodology.
Keywords: Tungstate sulfuric acid; Dicarbonyls; o-Phenylenediamine; Solvent-free conditions.
INTRODUCTION
Providing improved synthetic methods can be one of
duction of disulfides from thiols, oxidation of 1,4-dihydro-
pyridines,13-c N-nitrosation of secondary amines,13-d and
other processes, which are beyond the discussion of this
manuscript.
As mentioned in our earlier article,14 anhydrous so-
dium tungstate reacts in a 1:2 mole ratio with chlorosul-
fonic acid (Scheme I) to give tungstate sulfuric acid (TSA,
1) in a simple and clean reaction which did not required any
work-up (Scheme II).
the best possible assistance to the Organic Chemistry.
Seeking this goal, we found a new and modified strategy
for the synthesis of quinoxaline and phenazine derivatives.
In this manuscript, some of the most important appli-
cations of these heterocyclic compounds are described. For
example, some quinoxaline derivatives are associated with
a wide-ranging biological effects such as riboflavin (vita-
min B2), agonists and antagonists of various receptors,
agents with high antibacterial or antiviral activities (e.g.
Echinomycin, Lenomycin, Actinomycin).1,2 Also, they are
known to be applied as effective electroluminescent mate-
rials,3 organic semiconductors,4 building blocks in the syn-
thesis of anionic receptors,5 cavitands6,7 and DNA binding
agents.8,9 Besides, many phenazine compounds are found
in nature and are produced by bacteria such as Pseudomo-
nas spp., Streptomyces spp., and Pantoea agglomerans.
These phenazine natural products have been implicated in
the virulence and competitive fitness of producing organ-
isms.10,11
Preparation of tunestate sulfuric acid (TSA)
Scheme I
It should be informed that in our previous studies on
the application of inorganic solid acids,15 we reported sev-
eral syntheses by the use of TSA.16 This catalyst is rela-
tively easy to prepare, and is obtained in high yield. More-
over, it is safe, environmentally benign, easy to handle,
presents fewer disposal problems and is stable in reaction
media.
For preparing the phenazines and quinoxalines, nu-
merous methods are available in the literature. Generally,
these compounds could be prepared via the condensation
of aryl 1,2-diamines with a 1,2-dicarbonyl compounds in
refluxing organic solvents, such as ethanol or acetic acid
for 2-12 h giving 34-85% yields.12
RESULTS AND DISCUSSION
In this work, through treating the o-phenylenedi-
amines 2 with 1,2-dicarbonyl compounds 3 using a small
amount of TSA 1 at room temperature under solvent-free
conditions, polycyclic aromatic heterocycles such as phen-
Recently, silica-sulfuric acid13-a and Nafion-H®13-b
have been used for a wide variety of reactions such as pro-
* Corresponding author. E-mail: karami@mail.yu.ac.ir
J. Chin. Chem. Soc. 2012, 59, 187-192
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187

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Karami et al.
azines and quinoxalines 4 (novel and known) were pre-
vents, less hazardous chemical synthesis, atom economy
and catalysis) is a driving force towards the development of
recoverable and reusable catalysts and avoidance of the use
of any toxic and organic solvents.
pared (Scheme II).
Condensation of phenylenediamines with
1,2-dicarbonyl compounds
Scheme II
Not only the ecological profile (through helping to
decrease hazardous industrial waste), but also the eco-
nomic profile is further improved if the catalyst is recycla-
ble and conditions are solvent less.
In this process, as indicated in Fig. 1, the recycled cat-
alyst was used for five cycles during which a little appre-
ciable loss was observed in the catalytic activities.
The driving force for such reactions is presumed to be
the thermodynamically favored formation of new aromatic
compounds. After examining the various conditions in or-
der to optimize the reaction temperature and amount of the
required catalyst, it was found that the appropriate reaction
conditions involve accomplishing under solvent-free con-
ditions at room temperature and taking a small amount of
the TSA 1 (5 mol%) as catalyst. It was also observed that
further increase in the catalyst amount not only didn’t im-
prove the product yield or reaction rate, but also its effect
was reserved. This can be explained as resulting from coor-
dination of o-phenylenediamine to the excessive catalyst.
As shown in Table 1, after optimizing the reaction
conditions, the generalizability of this process was investi-
gated. Various 1,2-dicarbonyl compounds were conducted
with o-phenylenediamines to give the corresponding prod-
ucts with excellent yields. In a variation, as can be seen in
Scheme III, 1-acetylnaphthalene 5 oxidized by selenium
dioxide to afford the 1-naphthyl glyoxal hydrate 6. The aim
of this work was the use of 8 as precursor for preparing the
new quinoxaline 4h.
EXPERIMENTAL SECTION
General
The commercial starting materials were purchased
from Merck, Fluka and Aldrich. The reactions were moni-
tored by TLC (silica-gel 60 F254, n-hexane: ethyl acetate).
IR spectra were recorded on a FT-IR Shimadzu-470 Spec-
1
trometer and the H NMR Spectra were obtained with a
Bruker-Instrument DPX-400 and 500 MHz Avance 2
model. The varioEl CHN Isfahan Iindustrial University
was used for elemental analysis. All of the products (except
novel compounds 4h, 4h, 4j, 4m) were characterized by
comparison of their spectra and physical data with those re-
ported in the literature.17-20
Preparation of tungstate sulfuric acid (TSA)
Anhydrous sodium tungstate (29.38 g, 0.1 mol) was
added gradually to chlorosulfonic acid (23.304 g, 13.31
mL, 0.2 mol) contained in a 250 mL round bottomed flask
placed in an ice-bath. After the completion of the addition
the mixture was shaken for 1 h. A yellowish-white solid of
TSA was obtained (40.2 g, 98.0%), m.p. 285 °C (dec.); IR
(KBr, cm-1); 3600-2200 (OH, bs), 1240-1140 (S=O, bs),
1060 (S-O, m), 1005 (S-O, m), 880-840 (W=O, m), 450
Precursor production process for the prep-
Scheme III
aration of a new quinoxaline 4h
In many cases, in order to achieve fast synthesis in or-
ganic process, must be used a reagent as catalyst. The need
to implement green chemistry principles (e.g. safer sol-
Fig. 1. Recyclability of TSA as catalyst for the synthe-
sis of 4a at room temperature. Reaction time =
30 min.
188
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Novel Polycyclic Aromatic Phenazines and Quinoxalines
Table 1. Synthesis of quinoxaline and phenazine derivatives using o-phenylenediamine 1 mmol, 1,2-
dicarbonyl 1 mmol and TSA (5 mol%) at room temperature under solvent-free conditions
Dicarbonyl
Compound
M.p. °C
Found (Lit.)
Entry
Product a
Time (min) Yield (%) b
Cl
Cl
O
O
N
N
190-192
(195-196)17
4a
30
95
Cl
Cl
O
O
O
Me
N
N
115-117
(116-117)17
4b
4c
25
90
75
O
O
O
NO2
N
N
190-192
(192-193)18
180
O
N
N
237-239
(238-240)19
4d
4e
20
20
88
86
O
Me
N
N
230-232
(>300)19
F
F
O
O
O
N
N
134-136
(135-137)20
4f
22
25
90
92
F
F
F
F
F
O
Me
N
N
163-165
(165-167)20
4g
4h
F
O
O
N
N
H
20
30
88
85
166
144
O
O
O
N
N
H
4i
O
O
O
O
O
O
N
N
4j
4k
25
20
92
91
246
O
N
N
224-226
(223-225)18
O
O
Me
N
N
217-219
(208-210)18
4l
22
90
98
O
O
N
N
4m
20
245-247
a Identified by comparison with authentic samples. b Refers to isolated yields.
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189

Article
Karami et al.
(W-O, m).
Hz), 8.08 (d, 1H, J = 9.2 Hz), 7.38-7.35 (m, 4H), 7.22-7.15
(m, 6H); 13C-NMR (CDCl3, 100 MHz) d (ppm) :157.43,
156.8, 148.96, 144.70, 141.07, 139.23, 139.17, 131.90,
131.07, 130.99, 130.93, 130.80, 129.61, 129.54, 126.74,
124.41.
Preparation of 1-naphthyl glyoxal hydrate 6
In a round-bottomed flask, are placed 600 cc. of
dioxane, 111 g. (1 mole) of selenium dioxide, and 20 cc. of
water. The mixture is heated to 50-55º and stirred until the
solid has gone into solution, 120 g. (1 mole) of 1-acetyl-
naphthalene is added in one lot, and the resulting mixture is
refluxed with continued stirring for 24 hours. The hot solu-
tion is decanted from the precipitated selenium, and the
dioxane and water are removed under reduced pressure to
yield 1-naphthylglyoxal as an oil, then it was poured into
cool water and stirred at room temperature for 6 hours. Af-
ter the completion of the hydration reaction, the solid was
separated by simple filtration and then recrystallized from
ethyl acetate to afford pure product 6.
Acenaphtho[1,2-b]quinoxaline 4d
Yield: 95%; m.p. 237-239 °C; IR (KBr) nmax (cm-1):
3050, 1610, 1430, 1300, 830, 760; 1H-NMR (CDCl3, 400
MHz) d (ppm): 8.21 (d, 2H, J = 6.8 Hz), 8.02 (dd, 2H, J =
6.2 Hz, 3.2 Hz), 7.90 (d, 2H, J = 8.4 Hz), 7.65 (t, 2H, J = 7
Hz), 7.57 (dd, 2H, J = 6.4 Hz, 3.6 Hz); 13C-NMR (CDCl3,
100 MHz) d (ppm): 155.19, 142.39, 137.60, 132.92,
131.10, 130.47, 130.59, 130.36, 129.78, 122.96.
9-Methyl-acenaphtho[1,2-b]quinoxaline 4e
M.p. 230-232 °C; IR (KBr) nmax (cm-1): 3055, 2910,
1610, 1415, 1300, 810, 790; 1H-NMR (CDCl3, 400 MHz) d
(ppm): 8.21 (t, 2H, J = 6.4 Hz), 7.90 (dd, 3H, J = 8.2 Hz, 3.2
Hz), 7.79 (s, 1H), 7.64 (t, 2H, J = 7.4 Hz), 7.40 (dd, 1H, J =
8.4 Hz, 1.6 Hz), 2.43 (s, 3H); 13C-NMR (CDCl3, 100 MHz)
d (ppm): 131255.15, 154.44, 142.38, 140.82, 140.71,
137.35, 133.08, 132.44, 131.06, 130.46, 130.31, 130.21,
129.89, 129.72, 122.83, 122.68, 22.94.
Preparation of quinoxalines and phenazines from
o-phenylenediamines and 1,2-dicarbonyls: General
procedures
1 mmol of 1,2-dicarbonyl, 0.05 mmol TSA and 1
mmol phenylenediamine were mixed and added to a mor-
tar. The mixture was thoroughly grounded with pestle at
room temperature. The progress of the reaction was moni-
tored by TLC (ethyl acetate/n-hexane, 3:7). After the com-
pletion of the reaction, the reaction mixture was dissolved
in hot ethanol and the catalyst was filtered. The pure prod-
uct was crystallized from ethanol. The catalyst was washed
with diethyl ether, dried at 70 oC for 45 min, and reused in
another reaction.
2,3-Bis(4-flouro-phenyl)quinoxaline 4f
M.p. 134-136 °C; IR (KBr) nmax (cm-1): 3061, 1599,
1555, 1511, 1344, 1225, 839, 786; 1H-NMR (CDCl3, 400
MHz) d (ppm): 7.97 (dd, 2 H, J = 6.4 Hz, 3.6 Hz), 7.60 (dd,
2H, J = 6.4 Hz, 3.2 Hz), 7.33-7.30 (m, 4H), 6.86 (t, 4H, J =
8.8 Hz); 13C-NMR (CDCl3, 100 MHz) d (ppm): 161.99,
152.20, 141.23, 135.02, 131.82, 131.74, 130.23, 129.16,
115.65, 115.43.
2,3-Bis(4-chlorophenyl)quinoxaline 4a
1
M.p. 195-196 °C; H-NMR (CDCl3, 500 MHz) d
(ppm): 7.39 (dt, 4H, J = 8.5, 2.0 Hz), 7.51 (dt, 4H, J = 8.5
Hz, 2.0 Hz), 7.83 (dd, 2H, J = 6.3 Hz, 3.4 Hz), 8.20 (dd, 2H,
J = 6.3 Hz, 3.4 Hz); 13C-NMR (CDCl3, 120 MHz) d (ppm):
152.34, 141.67, 137.69, 135.78, 131.61, 130.79, 129.63,
129.15.
2,3-Bis(4-flouro-phenyl)-6-methylquinoxaline 4g
M.p. 163-165 °C; IR (KBr) nmax (cm-1): 2925, 2580,
1657, 1597, 1264, 1159, 833, 696; 1H-NMR (CDCl3, 400
MHz) d (ppm): 7.85 (d, 1H, J = 8.8 Hz), 7.73 (s, 1H), 7.42
(d, 1H, J = 8.8 Hz), 7.30 (dd, 4H, J = 8 Hz, 5.2 Hz), 6.58
(4H, t, J = 8.8 Hz), 2.43 (s, 3H); 13C-NMR (CDCl3, 100
MHz) d (ppm): 161.89, 152.05, 151.29, 141.28, 140.84,
139.69, 135.16, 135.13, 132.59, 131.77, 131.72, 131.69,
128.65, 127.96, 115.59, 115.37, 21.94.
6-Methyl-2,3-diphenylquinoxaline 4b
Yield: 93%; m.p. 115-117 °C; IR (KBr) nmax (cm-1):
3060, 2950, 1605, 1340, 700; 1H-NMR (CDCl3, 400 MHz)
d (ppm): 7.87 (d, 1H, J = 8.4 Hz), 7.76 (s, 1H), 7.36-7.34
(m, 5H), 7.13-7.11 (m, 6H), 2.37 (s, 3H); 13C-NMR (CDCl3,
100 MHz) d (ppm): 154.28, 153.54, 142.40, 141.43,
140.84, 140.45, 133.35, 131.14, 129.85, 129.78, 129.36,
129.18, 23.08.
3-Naphthyl-7-benzoyl-quinoxaline 4h
M.p. 166-168 °C; (KBr) nmax (cm-1): 3050, 1697,
1651, 1446, 1289; 1H-NMR (CDCl3, 400 MHz): d (ppm):
9.31 (s, 1H), 8.59 (s, 1H), 8.35 (s, 2H), 8.23 (d, 1H, J = 9.2
Hz), 8.06 (d, 1H, J = 8.4 Hz), 8 (d, 1H, J = 6.4 Hz), 7.94 (d,
2H, J = 8 Hz), 7.48 (d, 1H, J = 7.2 Hz), 7.68 (t, 2H, J = 7.6
Hz), 7.60-7.53 (m, 4H); 13C-NMR (CDCl3, 100 MHz): d
(ppm): 195.65, 155.97, 147.77, 144, 140.41, 138.31,
6-Nitro-2,3-diphenylquinoxaline 4c
M.p. 190-192 °C; IR (KBr) nmax (cm-1): 3010, 1610,
1
1519, 1327, 760, 690; H-NMR (CDCl3, 400 MHz) d
(ppm): 8.83 (d, 1H, J = 2.4 Hz), 8.27 (dd,1H, J = 9.2 Hz, 2.4
190
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Novel Polycyclic Aromatic Phenazines and Quinoxalines
137.08, 134.61, 134.07, 133.01, 132.38, 131.01, 130.67,
130.40, 130.23, 130.14, 128.90, 128.79, 128.60, 127.46,
126.89, 126.54, 125.46, 124.89; IR Anal. Calcd. For
C25H16N2O: C, 83.31; H, 4.47; N, 7.77. Found: C, 82.63, H,
4.523, N, 6.903.
NMR (CDCl3, 100 MHz): d (ppm): 196, 184.81, 153.70,
143.74, 143.45, 141.05, 137.92, 137.38, 132.95, 132.84,
132.48, 132.18, 130.99, 130.75, 130.23, 129.94, 129.40,
128.58, 128.12, 126.69, 126.36, 123.01; Anal. Calcd. For
C27H16N2O: C, 84.36 H, 4.20; N, 7.29. Found: C, 84.48, H,
4.183, N, 7.375.
3-Phenyl-7-benzoyl-quinoxaline 4i
M.p. 144-146 °C; IR (KBr) nmax (cm-1): 3053, 1650,
1595, 1454, 1294; 1H-NMR (CDCl3, 400 MHz): d (ppm):
9.43 (s, 1H), 8.51 (s, 1H), 8.28-8.25 (m, 4H), 7.29 (s, 1H),
7.91 (d, 1H, J = 1.2 Hz), 7.68-7.53 (m, 6H); 13C-NMR
(CDCl3, 100 MHz): d (ppm): 195.63, 153.31, 144.41,
144.16, 140.63, 137.88, 137.12, 136.24, 132.89, 132.33,
130.82, 130.26, 130.16, 130.09, 129.30, 128.54, 127.77,
127.60; Anal. Calcd. For C21H14N2O: C, 81.27; H, 4.55; N,
9.03. Found: C, 81.50, H, 4.516, N, 9.070.
1-Naphthylglyoxal hydrate 621
M.p. 115-117 °C; IR (KBr) nmax (cm-1): 3435, 2860,
1
2760, 1673, 1508, 1421, 10.68; H-NMR (CDCl3, 400
MHz): d (ppm): 8.93-8.3 (m, 1H), 8.17-7.42 (m, 7H), 1.15
(d, 2H, J = 12 Hz); 13C-NMR (CDCl3, 100 MHz): d (ppm):
195.30, 190.33, 135.83, 135.34, 133.93, 131.15, 129.24,
128391, 128.67, 127.67, 126.85, 125.89.
CONCLUSION
9-Benzoyl-acenaphtho[1,2-b]quinoxaline 4j
In conclusion, our pathway turned out to be cheaper
and less toxic than the majority of the traditional routes be-
cause it avoids the use of organic solvents. Because of ad-
vantages such as clean reaction under solvent-free condi-
tions, simple work-up procedure, the high yields of pure
products, and simple preparation of recoverable and
eco-friendly catalyst, this method is important from an en-
vironmental point of view and economic considerations.
M.p. 246-248 °C; IR (KBr) vmax (cm-1): 3038, 1646,
1595, 1437, 1300; 1H-NMR (CDCl3, 400 MHz): d (ppm):
8.61 (d, 1H, J = 1.6 Hz), 8.50 (d, 1H, J = 6.8 Hz), 8.44 (d,
1H, 6.8 Hz), 8.40 (d, 1H, J = 8.8 Hz), 8.28 (dd, 1H, J = 8.6
Hz, 2 Hz), 8.18 (dd, 2H, J = 8 Hz, 6 Hz), 7.96-786 (m, 4H),
7.67 (t, 1H, J = 7.6 Hz), 7.56 ( t, 2H, J = 7.6 Hz); Anal.
Calcd. For C25H14N2O: C, 83.78; H, 3.94; N, 7.82. Found:
C, 83.46, H, 3.745, N, 7.607.
ACKNOWLEDGEMENT
Dibenzo[a,c]phenazine 4k
M.p. 224-226 °C; IR (KBr) nmax (cm-1): 3055, 1600,
1
1490, 1350, 760, 720. H-NMR (CDCl3, 400 MHz) d
The authors gratefully acknowledge partial support
of this work by the Islamic Azad University, Branch of
Gachsaran, Iran.
(ppm): 9.18 (d, 2H, J = 7.6 Hz), 8.34 (d, 2H, J = 8 Hz), 8.12
(dd, 2H, J = 6.4 Hz, 3.6 Hz), 7.66-7.51 (m, 6H) );13C-NMR
(CDCl3, 100 MHz) d (ppm): 143.54, 143.28, 133.15,
131.42, 130.88, 130.57, 129.04, 127.38, 124.03.
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