One-pot oxidative Ugi-type three-component reaction of aromatic hydrocarbons of petroleum naphtha: comparing catalytic effect of cellulose- and wool-SO3H supported with manganese dioxide nanostructures

Article abstract of DOI:10.1039/c5ra16608j

A novel domino oxidative Ugi-type three-component reaction of aromatic hydrocarbons (OU-3CR) has been investigated with aromatic hydrocarbons of petroleum naphtha using two biopolymer supported MnO₂ nanostructured catalysts, MnO₂@cellulose-SO₃H and MnO₂@wool-SO₃H, for the synthesis of α-amino amides, 3,4-dihydroquinoxalin-2-amine, 4H-benzo[b][1,4]thiazin-2-amine, and cyanophenylamino-acetamide derivatives. Nano-MnO₂@cellulose-SO₃H and nano-MnO₂@wool-SO₃H were used as biodegradable oxidation and solid acid catalysts. The best results for oxidation and condensation processes are obtained with MnO₂@cellulose-SO₃H and MnO₂@wool-SO₃H, respectively. To the best of our knowledge this approach can be considered as the first example of OU-3CR of alkyl arenes with a nano-MnO₂ catalyst which would be very useful from a practical point of view.

Full text of DOI:10.1039/c5ra16608j

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One-pot oxidative Ugi-type three-component
reaction of aromatic hydrocarbons of petroleum
naphtha: comparing catalytic effect of cellulose-
and wool–SO3H supported with manganese
dioxide nanostructures
Cite this: RSC Adv., 2015, 5, 91966
*
Ahmad Shaabani, Zeinab Hezarkhani and Elham Badali
A novel domino oxidative Ugi-type three-component reaction of aromatic hydrocarbons (OU-3CR) has
been investigated with aromatic hydrocarbons of petroleum naphtha using two biopolymer supported
MnO2 nanostructured catalysts, MnO2@cellulose–SO3H and MnO2@wool–SO3H, for the synthesis of a-
amino amides, 3,4-dihydroquinoxalin-2-amine, 4H-benzo[b][1,4]thiazin-2-amine, and cyanophenylamino-
acetamide derivatives. Nano-MnO2@cellulose–SO3H and nano-MnO2@wool–SO3H were used as
biodegradable oxidation and solid acid catalysts. The best results for oxidation and condensation
processes are obtained with MnO2@cellulose–SO3H and MnO2@wool–SO3H, respectively. To the best of
our knowledge this approach can be considered as the first example of OU-3CR of alkyl arenes with
a nano-MnO2 catalyst which would be very useful from a practical point of view.
Received 17th August 2015
Accepted 19th October 2015
DOI: 10.1039/c5ra16608j
www.rsc.org/advances
industry to introduce and modify functional groups,19 this
useful strategy (domino aerobic oxidation/MCRs) can be
1. Introduction
developed with either primary or secondary alkyl arenes instead
of their corresponding aldehydes or ketones in the IMCRs. To
the best of our knowledge, there is currently no report of
employing alkyl arenes in one-pot oxidative Ugi-type multi-
component reactions (OU-MCRs).
In our previous reports evidenced that the prepared
MnO2@cellulose and MnO2@wool catalysts showed high
selectivity in the oxidation of the alkyl arenes to the related
aldehydes or ketones.20,21 In this work, we used MnO2@
cellulose–SO3H and MnO2@wool–SO3H as two biopolymer
based catalysts in OU-3CR with the toluene and three xylene
isomers. The double nature of the prepared catalysts (oxidation
capability and acidic property) was made capable us to use these
catalysts in the both oxidation and synthetic sections of the
reactions.
The mixtures of benzene, toluene, and the three xylene isomers,
BTX, are very important petrochemical materials. BTX can be
made by various processes. However, most BTX production is
based on the recovery of aromatics derived from the catalytic
reforming of naphtha in petroleum reneries. Among the BTX
family members, toluene and xylenes (TXs) were modied by
chemical processing and a large number of ne chemicals and
petrochemicals were produced from them.1
Multicomponent reactions (MCRs)2,3 and specially iso-
cyanide based MCRs (IMCRs)4,5 are powerful tools for the
synthesis of biologically heterocyclic molecules and have enor-
mous applications in the eld of drugs and pharmaceutical
industries. One of the most important reactants in IMCRs is
carbonyl compounds which unfortunately this limits the
versatility of these reactions. To solving this issue, one-pot
oxidative MCRs protocol can be done by transforming an inert
substance into a reactive substrate of the IMCRs. These trans-
formations involve in situ oxidation of one reagent or the
oxidation is performed as a separate step.6 Very recently it has
been shown that the direct use of alcohols and N-alkyl amines
in Passerini and Ugi reactions, respectively, could signicantly
widen the versatility and the scope of well-known aldehyde-
based multicomponent.7–18 Since, the oxidation of alkyl arenes
is among the most important transformations in chemistry and
2. Materials and methods
2.1. General
All reagents were obtained from Aldrich or Merck and used
without further purication. Scanning electron microscopy
(SEM) observations were carried out on an electron microscopy
Philips XL-30 ESEM. All samples were sputtered with gold
before observation. Mn(IV) determination was carried out on an
FAAS (Shimadzu model AA-680 ame atomic absorption spec-
trometer) with a Mn hollow cathode lamp at 279.5 nm, using an
air–acetylene ame. Thermogravimetric analysis (TGA) was
Faculty of Chemistry, Shahid Beheshti University, G. C., P. O. Box 19396-4716, Tehran,
Iran. E-mail: a-shaabani@sbu.ac.ir
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Scheme 1 Preparation of MnO2@cellulose–SO3H catalyst.
points were measured on an Electrothermal 9200 apparatus. IR
1
spectra were recorded on a Shimadzu IR-470 spectrometer. H
NMR spectra were recorded on a Bruker DRX-300 Avance
spectrometer 300.13 MHz; chemical shis are reported in parts
per million (ppm). The 13C NMR spectra were recorded at 75.47
MHz; chemical shis are reported in parts per million (ppm).
The elemental analyses were performed with an Elementar
Analysen systeme GmbH VarioEL.
Scheme 2 Preparation of MnO2@wool–SO3H catalyst.
2.2. Preparation of catalysts
carried out using STA 1500 instrument at a heating rate of 10 ꢀC
minꢁ1 in air. X-ray diffraction (XRD) pattern of product was
recorded on a STOE STADI P with scintillation detector,
secondary monochromator using Cu Ka radiation (l ¼ 0.1540
nm). Products were analyzed using a Varian 3900 GC. Melting
2.2.1. Preparation of MnO2@cellulose–SO3H. According to
our previous works,22–24 chlorosulfonic acid (0.40 g, 3.60 mmol)
was added dropwise to a magnetically stirred mixture of cellu-
lose (1.00 g) in CHCl3 (20 mL) at 0 ꢀC during 2 h. Then, the
mixture was stirred for 3 h at room temperature until HCl was
Fig. 1 SEM images of MnO2@cellulose–SO3H (a–c) in different scales, cellulose (d), wool (e and f), and MnO2@wool–SO3H (g and h) in different
scales.
Fig. 2 TG curves of cellulose–SO3H (I), MnO2@cellulose–SO3H (II), wool (III), and MnO2@wool–SO3H (IV) in air.
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Fig. 3 XRD patterns of cellulose–SO3H (I) and wool (III), nano-MnO2@cellulose–SO3H (II), and nano-MnO2@wool–SO3H (IV).
removed from the reaction vessel. The mixture was ltered and mixture was ltered and washed with acetone (3 ꢂ 10 mL) and
washed with methanol (5 ꢂ 10 mL). The product was dried at EtOH (3 ꢂ 10 mL), successively and dried under vacuum at
room temperature to obtain cellulose sulfuric acid as white 60 C for 24 h to give MnO2@wool–SO3H (Scheme 2).21
ꢀ
powder. Manganese dioxide nanostructures on sulfonated
cellulose bers was prepared according to the our previous
report to synthesis of MnO2@cellulose.20 A solution of KMnO4
2.3. General procedure for the preparation of products 4a–c,
5a–d, 6a–c, 7a–c, and 8a–d
ꢀ
(0.01 M, 90 mL) at 60 C, and a solution of MnCl2 (0.02 M, 75
ꢀ
mL) at 70 C were added dropwise to a mixture of sulfonated
In a typical reaction, an aromatic hydrocarbon (2.00 mL) was
added to a two-necked ask containing catalyst (0.09 g, 10
mol% for MnO2@cellulose–SO3H or 0.10 g, 10 mol% for
MnO2@wool–SO3H catalyst) and stirred under reux conditions
and air blowing. The progress of the reaction was followed by
GC method. Aer the indicated time in Table 2, the mixture of
reaction was cooled. Amine (1.00 mmol), isocyanide (1.00
mmol), and 5 mL of ethanol 96% was added to the reaction
media and stirred at room temperature. The progress of the
reaction was monitored by TLC. Aer completion, the reaction
mixture was ltered off and washed with ethanol, and then the
precipitation of ltrate was done to give products 4a–c, 5a–d,
6a–c, 7a–c, and 8a–d.
cellulose (1.00 g) in 50 mL of H2O at 60 ꢀC for 12 h. The mixture
was stirred for 24 h at room temperature. Then, the reaction
ꢀ
mixture was ltered, washed and dried under vacuum at 70 C
(Scheme 1).
2.2.2. Preparation of MnO2@wool–SO3H. Natural white
wool (sheep of Kangavar/Iran) was washed with NaOH solution
(0.01 M), distilled water, methanol, and ethanol, then cut with
scissors to very short pieces (about 50–500 mm, based on SEM
images). A solution of KMnO4 (0.01 M, 180 mL) was added
dropwise to a magnetically stirred suspention of the wool pieces
(1.00 g) in 100 mL of H2O during 12 h at room temperature. The
stirring was continued at room temperature for 24 h. The
Scheme 3 Synthesis of a-amino amide, 3,4-dihydroquinoxalin-2-amine, 4H-benzo[b][1,4]thiazin-2-amine, and cyanophenylamino-acetamide
derivatives.
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In order to obtain the optimum reaction conditions, toluene
has been oxidized in the presence of the MnO2@cellulose–SO3H
or MnO2@wool–SO3H catalyst in the reux reaction conditions
at the reaction times which have been presented in the Table 1.
Aer cooling the reaction media 2-amino-5-methylphenol (2a)
and cyclohexyl isocyanide (3) in various organic solvents and
water were allowed to react at room temperature. As can be seen
from Table 1, commercially available ethanol 96% is the best
solvents for the synthesis of compound N-cyclohexyl-2-((2-
hydroxy-4-methylphenyl)amino)-2-phenylacetamide (4a) respect
to yield and reaction times. In order to nd the best conditions,
toluene and the three xylene isomers (1a–d) and various amines
(2a–e) were examined in this reaction. The results have been
shown in Table 2.
2.4. Caracterization of catalyst
The MnO2@cellulose–SO3H and MnO2@wool–SO3H were
characterized by scanning electron microscopy (SEM), ame
atomic absorption spectrometer (FAAS), thermogravimetric
analysis (TGA), and X-ray diffraction (XRD). From the Fig. 1a–
d it is evident that the sulfunation of cellulose with chlor-
osulfonic acid have not been altered the morphology of the
cellulose support. Also, Fig. 1e–h shows SEM images of wool
(Fig. 1e and f) and the synthesized MnO2@wool–SO3H (Fig. 1g
and h) which indicated the relatively retained morphology of
wool aer functionalizing with oxidation of –S–S– bonds to
–SO3H groups. As predicted, MnO2 nanostructures were well
dispersed on the surface of cellulose–SO3H and wool–SO3H
bers (Fig. 1c and h, respectively).
The successfully carrying out of the reactions had conrmed
the usability of the synthesized catalyst for the rst-(aerobic
oxidation) and second-step (solid acid catalyst), as it has been
designed.
The Mn(IV) contents of the MnO2@cellulose–SO3H and
MnO2@wool–SO3H catalysts was determined using FAAS
method. The amounts of MnO2 in the MnO2@cellulose–SO3H
and MnO2@wool–SO3H were determined 9.13% and 8.82%,
respectively.
In order to investigate the scope and limitations of this
reaction, we extended it to o-phenylenediamine (2b), 2-amino-
thiophenol (2c), 2-aminobenzamide (2d), and 2,3-dia-
minomaleonitrile (2e) instead of 2-amino-5-methylphenol (2a).
Due to intramolecular nucleophilic attack of NH and SH groups
to the activated nitrile moiety, interesting products such as 3,4-
dihydroquinoxalin-2-amines 4a–c and 4H-benzo[b][1,4]thiazin-
2-amines 5a–d were obtained but in the case of using 2-
amino-5-methylphenol (2a) and 2-aminobenzamide (2d) the
cyclyzation product was not obtained (Table 2).
The reaction of 2,3-diaminomaleonitrile, aldehyde, and iso-
cyanide was known to produce Schiff base and nucleophilic
attack by isocyanide does not occur.28 So, the isolated
compounds were intermediates 8a–d. Unfortunately, in the case
of using m-xylene as an alkyl arene, the yield of reactions was
In continue, these catalysts were characterized by thermog-
ravimetric analysis (TGA) that conrmed functionalization of
supports and the presence of MnO2 in the supports. Fig. 2
shows the thermal behavior of cellulose–SO3H (I), MnO2@
cellulose–SO3H (II), wool (III), and MnO2@wool–SO3H (IV). The
thermogram of cellulose–SO3H and MnO2@cellulose–SO3H
show a weight loss of around 100% and 90% at temperature
higher than 700 ꢀC, respectively. In the case of MnO2@
cellulose–SO3H, the decreased 10% weight loss is directly
related to the presence of the MnO2. In the case of the
MnO2@wool–SO3H at the temperature higher than 720 ꢀC a lose
in weight about 91% is observable; the remaining weight is
related to the MnO2 loaded on the catalyst.
The XRD patterns of cellulose–SO3H and wool bers and
MnO2@cellulose–SO3H and MnO2@wool–SO3H catalysts were
employed to investigate the structures of the synthetic catalysts
(Fig. 3). In the XRD patterns I and II the characters of cellulose–
SO3H and MnO2@cellulose–SO3H were observable, respectively.
The XRD pattern of wool bers and MnO2@wool–SO3H is
shown in XRD patterns III and IV. The peaks related to MnO2 (2q
¼ 13.90ꢀ, 24.28ꢀ, 34.60ꢀ, and 65.26ꢀ) can be ascribed to the
MnO2 nanostructures dispersed onto the surface of support
bers.
Table 1 Optimization of the reaction conditions for the synthesis of
compound N-cyclohexyl-2-((2-hydroxy-4-methylphenyl)amino)-2-
phenylacetamide (4a) by MnO2@cellulose–SO3H and MnO2@wool–
SO3H catalystsa
3. Results and discussion
Entry Catalyst (MnO2 content/mol%) t1 (h) Solvent Yieldb (%)
During the course of our studies toward the development of new
routes to the synthesis of organic compounds using green reac-
tion media25–28 and introduction of wool–SO3H and cellulose–
SO3H for the rst time as a biopolymer solid acid catalyst,22–24 and
using nano-MnO2@cellulose and nano-MnO2@wool for the
oxidation of the alkyl arenes,20,21 herein, we report the one-pot OU-
3CR with the TXs to synthesis of a-amino amides, 3,4-
dihydroquinoxalin-2-amine, 4H-benzo[b][1,4]thiazin-2-amine, and
cyanophenylamino-acetamide derivatives in the presence of
MnO2@cellulose–SO3H and MnO2@wool–SO3H as biodegradable
oxidation and solid acid catalysts (Scheme 3).
1
2
3
4
5
6
7
8
MnO2@cellulose–SO3H (10)
MnO2@wool–SO3H (10)
MnO2@cellulose–SO3H (10)
MnO2@wool–SO3H (10)
MnO2@cellulose–SO3H (10)
MnO2@wool–SO3H (10)
MnO2@cellulose–SO3H (10)
MnO2@woolSO3H (10)
8
10
8
10
8
10
8
10
MeOH
MeOH
EtOH
EtOH
H2O
H2O
—
56
78
91
96
Trace
Trace
Trace
Trace
—
a
Reaction conditions: rst step: toluene (2.00 mL), air as oxidant;
second step: 2-amino-5-methylphenol (1.00 mmol), cyclohexyl
isocyanide (1.00 mmol), solvent (5.00 mL). b Isolated yield.
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Table 2 The synthesis of a-amino amides, 3,4-dihydroquinoxalin-2-amine, 4H-benzo[b][1,4]thiazin-2-amine, cyanophenylamino-acetamide
derivatives by MnO2@cellulose–SO3H and MnO2@wool–SO3H catalystsa
Mp (ꢀC)
Yieldb
Entry Arenes
Amines
Catalyst
t1 (h) t2 (h) (%)
Found
Reported
1
Toluene
Toluene
Toluene
Toluene
Toluene
o-Xylene
o-Xylene
o-Xylene
o-Xylene
o-Xylene
p-Xylene
p-Xylene
p-Xylene
p-Xylene
p-Xylene
2-Amino-5-methylphenol MnO2@cellulose–SO3H
MnO2@wool–SO3H
8
10
8
10
8
10
8
10
8
10
6
7
6
7
6
7
6
7
6
7
6
7
6
7
6
7
6
7
6
7
9
10
9
10
48
48
12
12
48
48
48
48
12
12
48
48
12
12
48
48
48
48
12
12
48
48
12
12
48
48
48
48
12
12
48
48
48
48
4a 91 261–263
260–261 (ref. 29)
96
2
o-Phenylenediamine
2-Aminothiophenol
2-Aminobenzamide
MnO2@cellulose–SO3H
MnO2@wool–SO3H
MnO2@cellulose–SO3H
MnO2@wool–SO3H
MnO2@cellulose–SO3H
MnO2@wool–SO3H
5a 88 186–187
185–187 (ref. 25 and 30)
87
3
6a 76 190–192
192 (ref. 24 and 31)
74
4
7a 77 141–143
142–144 (ref. 26)
70
5
2,3-Diaminomaleonitrile MnO2@cellulose–SO3H
MnO2@wool–SO3H
2-Amino-5-methylphenol MnO2@cellulose–SO3H
MnO2@wool–SO3H
8a 91 205–206
205–207 (ref. 28)
93
6
4b 92 195–196 (ref. 32)
—
88
7
o-Phenylenediamine
2-Aminothiophenol
2-Aminobenzamide
MnO2@cellulose–SO3H
MnO2@wool–SO3H
MnO2@cellulose–SO3H
MnO2@wool–SO3H
MnO2@cellulose–SO3H
MnO2@wool–SO3H
5b 87 216–217 (ref. 32)
—
85
8
6b 80 156–157 (ref. 32)
—
76
9
7b 73 170–173 (ref. 32)
—
75
10
11
12
13
14
15
16
17
2,3-Diaminomaleonitrile MnO2@cellulose–SO3H
MnO2@wool–SO3H
2-Amino-5-methylphenol MnO2@cellulose–SO3H
MnO2@wool–SO3H
8b 91 186–187 (ref. 32)
—
90
4c 90 >290
>290 (ref. 29)
94
o-Phenylenediamine
2-Aminothiophenol
2-Aminobenzamide
MnO2@cellulose–SO3H
MnO2@wool–SO3H
MnO2@cellulose–SO3H
MnO2@wool–SO3H
MnO2@cellulose–SO3H
MnO2@wool–SO3H
5c 85 200–202
201 (ref. 25 and 30)
81
6c 80 205–206
205 (ref. 24 and 31)
83
7c 79 178–180
178–180 (ref. 26)
77
2,3-Diaminomaleonitrile MnO2@cellulose–SO3H
MnO2@wool–SO3H
8c 90 234–235 (ref. 32)
—
—
—
86
m-Xylene o-Phenylenediamine
MnO2@cellulose–SO3H
MnO2@wool–SO3H
5d 15 189–192 (ref. 32)
18
m-Xylene 2,3-Diaminomaleonitrile MnO2@cellulose–SO3H
MnO2@wool–SO3H
8d 20 214–217 (ref. 32)
27
a
Reaction conditions: rst step: arene (2.00 mL), air as oxidant; second step: amine (1.00 mmol), cyclohexyl isocyanide (1.00 mmol), catalyst (0.09 g
for MnO2@cellulose–SO3H and 0.10 g MnO2@wool–SO3H), EtOH (5.00 mL). b Isolated yield.
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Table 3 Comparison of the efficiency of the obtained catalysts in same time for the synthesis of compound 4a
Entrya
Catalyst
Conversion of 9b (%)
1
2
MnO2@cellulose–SO3H
MnO2@wool–SO3H
17
10
Entryc
Catalyst
Yield of 4ad (%)
1
2
MnO2@cellulose–SO3H
MnO2@wool–SO3H
40
61
a
b
Reaction conditions: arene (2.00 mL), catalyst (0.09 g for MnO2@cellulose–SO3H and 0.10 g MnO2@wool–SO3H), air as oxidant. Conversion
c
determined by GC analysis. Reaction conditions: benzaldehyde (1.00 mmol), 2-amino-5-methylphenol (1.00 mmol), cyclohexyl isocyanide
(1.00 mmol), catalyst (0.09 g for MnO2@cellulose–SO3H and 0.10 g MnO2@wool–SO3H). Isolated yield.
d
very low and only 4d and 8d products have been separated from and reused for ve times. Results are shown in Fig. 4. It is clear
reaction media.
that by successive use of catalysts their activity and performance
To select the best catalyst from reaction yield point of view, have not been decreased in a considerable amount (Fig. 4).
the synthesis of compound N-cyclohexyl-2-((2-hydroxy-4-
methylphenyl)amino)-2-phenylacetamide (4a) has been
studied. The reactions have been studied in the same reaction
4. Conclusion
time. The reactions and obtained results have been presented in
the Table 3. From the data it has been cleareed that
MnO2@cellulose–SO3H acts as the better catalyst for the
oxidation processes in the step 1 while the MnO2@wool–SO3H
In conclusion, we have developed a novel domino, aerobic,
oxidative Ugi-type three-component reaction of aromatic
hydrocarbons using biodegradable catalysts. The MnO2@
cellulose–SO3H and MnO2@wool–SO3H catalysts have been
catalyst acts as the better acid catalyst in the step 2.
used successfully to oxidize the low-price aromatic hydrocar-
Recyclability of the catalysts in the both oxidation and solid-
bons (toluene and xylenes) to valuable aldehydes. The double
acid-catalyzed steps were examined. The catalysts which were
nature of the prepared catalysts (oxidation capability and acidic
recovered from OU-3CR between toluene, 2-amino-5-
property) was made capable us to use the same catalyst in the
methylphenol, and cyclohexyl isocyanide by ltration, dried
synthetic section of the reactions, as well. The green aspect of
the catalysts is increasing the usability of the catalyst in the
situation which environment pollutant materials are restricted
to be used.
Acknowledgements
We gratefully acknowledge nancial support of the Iran
National Elites Foundation (INEF) and the Research Council of
Shahid Beheshti University.
References and notes
1 Chemistry of Petrochemical Processes, ed. S. Matar and L. F.
Fig. 4 Successive use of the prepared catalysts for the synthesis of
Hatch, Gulf Professional Publishing, Woburn, 2nd edn,
2001.
compound N-cyclohexyl-2-((2-hydroxy-4-methylphenyl)amino)-2-
phenylacetamide (4a).
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¨
2 I. Ugi, Journal fur Praktische Chemie/Chemiker-Zeitung, 1997, 32 Spectral data of new compounds: N-Cyclohexyl-2-((2-
339, 499–516.
hydroxy-4-methylphenyl)amino)-2-(o-tolyl)acetamide (4b):
cream powder; mp 195–196 C; IR (KBr, cmꢁ1) 3362, 3038,
ꢀ
3 R. W. Armstrong, A. P. Combs, P. A. Tempest, S. D. Brown
and T. A. Keating, Acc. Chem. Res., 1996, 29, 123–131.
1
2927, 2854, 2427, 1582, 1517, 1450; H NMR (300.13 MHz,
¨
4 A. Domling, Chem. Rev., 2006, 106, 17–89.
DMSO-d6) d 1.10–1.99 (10H, m, 5CH2 of cyclohexyl), 2.05
(3H, s, CH3), 2.12 (3H, s, CH3), 4.10 (1H, br s, CH–NH),
5.27 (1H, s, CH–Ph), 6.37–7.25 (9H, m, H–Ar and 2NH),
9.47 (1H, br s, OH). 13C NMR (75.47 MHz, DMSO-d6)
d 20.8, 21.1, 21.3, 25.1, 25.2, 25.7, 32.2, 49.0, 85.8, 114.3,
115.7, 116.9, 119.7, 123.0, 123.9, 126.4, 127.5, 129.7, 131.1,
139.2, 143.2, 154.0. Anal. calcd for C22H28N2O2: C, 74.97;
H, 8.01; N, 7.95. Found C, 74.82; H, 7.85; N, 7.99. N-
Cyclohexyl-3-(o-tolyl)-3,4-dihydroquinoxalin-2-amine (5b):
¨
5 A. Domling and I. Ugi, Angew. Chem., Int. Ed., 2000, 39, 3168–
3210.
6 J. Zhu, Q. Wang and M. Wang, Multicomponent Reactions in
Organic Synthesis, John Wiley & Sons, 2014.
7 P. Fontaine, A. Chiaroni, G. Masson and J. Zhu, Org. Lett.,
2008, 10, 1509–1512.
8 N. Shapiro and A. Vigalok, Angew. Chem., 2008, 47, 2849–
2852.
9 F. de Moliner, S. Crosignani, A. Galatini, R. Riva and
A. Basso, ACS Comb. Sci., 2011, 13, 453–457.
10 T. Ngouansavanh and J. Zhu, Angew. Chem., 2006, 118, 3575–
3577.
11 T. Ngouansavanh and J. Zhu, Angew. Chem., 2007, 46, 5775–
5778.
12 B. Karimi and E. Farhangi, Adv. Synth. Catal., 2013, 355, 508–
516.
13 R. J. K. Taylor, M. Reid, J. Foot and S. A. Raw, Acc. Chem. Res.,
2005, 38, 851–869.
14 G. Jiang, J. Chen, J.-S. Huang and C.-M. Che, Org. Lett., 2009,
11, 4568–4571.
cream powder; mp 216–217 C; IR (KBr, cmꢁ1) 3740, 3433,
ꢀ
2929, 2857, 1646, 1507, 1448; 1H NMR (300.13 MHz,
CDCl3) d 1.12–2.13 (10H, m, 5CH2 of cyclohexyl), 2.78 (3H,
s, CH3), 4.20 (1H, br s, CH–NH), 5.42 (1H, s, CH–Ph), 5.88
(1H, br s, NH), 6.53–7.40 (9H, m, H–Ar and NH). 13C NMR
(75.47 MHz, CDCl3) d 18.2, 20.0, 20.9, 21.3, 48.0, 52.9,
125.8, 128.6, 129.2, 129.5, 130.2, 130.7, 134.0, 134.3, 137.5,
140.0, 141.6, 142.3, 150.3. Anal. calcd for C21H25N3: C,
78.96; H, 7.89; N, 13.15. Found C, 78.79; H, 7.96; N, 12.98.
N-Cyclohexyl-3-(m-tolyl)-3,4-dihydroquinoxalin-2-amine (5d):
cream powder; mp 189–192 C; IR (KBr, cmꢁ1) 3244, 3046,
ꢀ
1
2931, 2855, 1654, 1598, 1504, 1449; H NMR (300.13 MHz,
15 S. U. Dighe, S. Kolle and S. Batra, Eur. J. Org. Chem., 2015,
2015, 4238–4245.
CDCl3) d 0.91–2.17 (10H, m, 5CH2 of cyclohexyl), 2.31 (3H,
s, CH3), 4.78 (1H, br s, CH–NH), 5.16 (1H, s, CH–Ph), 6.67–
8.07 (10H, m, H–Ar and 2NH). Anal. calcd for C21H25N3: C,
78.96; H, 7.89; N, 13.15. Found C, 79.01; H, 7.95; N, 13.02.
N-Cyclohexyl-3-(o-tolyl)-4H-benzo[b][1,4]thiazin-2-amine (6b):
16 C. Xie and L. Han, Tetrahedron Lett., 2014, 55, 240–243.
17 C. Vila and M. Rueping, Green Chem., 2013, 15, 2056–2059.
18 X. Ye, C. Xie, R. Huang and J. Liu, Synlett, 2012, 409–412.
19 Handbook of Reagents for Organic Synthesis, Oxidizing and
Reducing Agents, ed. S. D. Burke and R. L. Danheiser, John
Wiley and Sons, Chichester, UK, 1999.
20 A. Shaabani, Z. Hezarkhani and S. Shaabani, RSC Adv., 2014,
4, 64419–64428.
21 A. Shaabani, Z. Hezarkhani and E. Badali, RSC Adv., 2015, 5,
61759–61767.
yellow powder; mp 156–157 C; IR (KBr, cmꢁ1) 3056, 2938,
ꢀ
1
2861, 2608, 2551, 2049, 1673, 1536, 1456; H NMR (300.13
MHz, CDCl3) d 1.00–1.92 (10H, m, 5CH2 of cyclohexyl), 2.40
(3H, s, CH3), 2.86 (1H, br s, CH–NH), 7.21–7.79 (10H, m,
H–Ar and 2NH). 13C NMR (75.47 MHz, CDCl3) d 21.4, 24.3,
24.6, 30.6, 50.7, 125.7, 125.8, 126.1, 126.2, 126.2, 126.8,
128.6, 128.7, 128.9, 128.9, 129.1, 129.9, 140.7, 141.4. Anal.
calcd for C21H24N2S: C, 74.96; H, 7.19; N, 8.33. Found C,
75.03; H, 7.12; N, 8.27. 2-((2-Cyanophenyl)amino)-N-
cyclohexyl-2-(o-tolyl)acetamide (7b): cream powder; mp 170–
22 A. Shaabani and A. Maleki, Appl. Catal., A, 2007, 331, 149–
151.
23 A. Shaabani, A. Rahmati and Z. Badri, Catal. Commun., 2008,
9, 13–16.
173 C; IR (KBr, cmꢁ1) 3470, 3396, 3062, 2925, 2846, 2202,
ꢀ
24 H. Mofakham, Z. Hezarkhani and A. Shaabani, J. Mol. Catal.
A: Chem., 2012, 360, 26–34.
25 A. Shaabani, A. Maleki, H. Mofakham and H. R. Khavasi, J.
Comb. Chem., 2008, 10, 323–326.
26 A. Shaabani, A. Maleki, H. Mofakham and H. R. Khavasi, J.
Comb. Chem., 2008, 10, 883–885.
27 A. Shaabani, A. Maleki, H. Mofakham and J. Moghimi-Rad, J.
Org. Chem., 2008, 73, 3925–3927.
28 A. Shaabani, A. Maleki and J. Moghimi-Rad, J. Org. Chem.,
2007, 72, 6309–6311.
29 A. Shaabani, S. Keshipour, S. Shaabani and M. Mahyari,
Tetrahedron Lett., 2012, 53, 1641–1644.
30 M. M. Heravi, B. Baghernejad and H. A. Oskooie, Tetrahedron
Lett., 2009, 50, 767–769.
31 M. M. Heravi, B. Baghernejad and H. A. Oskooie, Synlett,
2009, 2009, 1123–1125.
1645, 1588, 1506, 1327; 1H NMR (300.13 MHz, CDCl3)
d 1.26–2.38 (13H, m, 5CH2 of cyclohexyl and CH3), 3.24
(1H, br s, CH–NH), 3.52 (1H, br s, NH), 4.48 (1H, s, CH–
Ph), 6.96–8.66 (9H, m, H–Ar and NH). Anal. calcd for
C22H25N3O: C, 76.05; H, 7.25; N, 12.09. Found C, 76.12; H,
7.35; N, 12.15. 2-Amino-3-(((E)-2-methylbenzylidene)amino)
maleonitrile (8b): yellow powder; mp 186–187 ꢀC; IR (KBr,
cmꢁ1) 3430, 3316, 3160, 2239, 2199, 1604, 1447, 1373; 1H
NMR (300.13 MHz, DMSO-d6) d 2.50 (3H, s, CH3), 7.25–7.40
(3H, m, H–Ar), 7.92 (2H, br s, NH2), 8.24 (1H, d, 3JHH ¼ 7.5
Hz, H–Ar), 8.50 (1H, s, CH). 13C NMR (75.47 MHz, DMSO-d6)
d 19.2, 103.8, 114.2, 114.9, 126.6, 127.1, 128.1, 131.4, 131.7,
133.5, 139.0, 153.4. Anal. calcd for C12H10N4: C, 68.56; H,
4.79; N, 26.65. Found C, 68.51; H, 4.72; N, 26.73. 2-Amino-3-
(((E)-4-methylbenzylidene)amino)maleonitrile (8c): yellow
powder; mp 234–235 ꢀC; IR (KBr, cmꢁ1) 3413, 3301, 2902,
91972 | RSC Adv., 2015, 5, 91966–91973
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2230, 2196, 1908, 1611, 1374; 1H NMR (300.13 MHz, DMSO-d6)
RSC Advances
cmꢁ1) 3460, 3334, 3104, 2924, 2197, 1950, 1688, 1594, 1518,
1334; H NMR (300.13 MHz, DMSO-d6) d 2.63 (3H, s, CH3),
d 2.96 (3H, s, CH3), 7.28 (2H, d, 3JHH ¼ 7.8 Hz, H–Ar), 7.80 (2H,
br s, NH2), 7.91 (2H, d, 3JHH ¼ 7.8 Hz, H–Ar), 8.22 (1H, s, CH).
13C NMR (75.47 MHz, DMSO-d6) d 21.7, 103.3, 114.2, 114.9,
127.0, 129.5, 129.8, 133.4, 142.2, 155.5. Anal. calcd for
C12H10N4: C, 68.56; H, 4.79; N, 26.65. Found C, 68.62; H,
4.74; N, 26.70. 2-Amino-3-(((E)-3-methylbenzylidene)amino)
maleonitrile (8d): yellow powder; mp 214–217 ꢀC; IR (KBr,
1
7.22-7.25 (2H, m, H–Ar), 7.37–7.40 (2H, m, H–Ar and CH),
7.61 (2H, br s, NH2), 7.74 (1H, d, JHH ¼ 6.9 Hz, H–Ar). 13C
3
NMR (75.47 MHz, DMSO-d6) d 21.5, 122.4, 126.0, 126.4, 128.6,
129.8, 129.9, 130.4, 131.7, 137.5, 138.3, 152.3. Anal. calcd for
C12H10N4: C, 68.56; H, 4.79; N, 26.65. Found C, 68.50; H,
4.65; N, 26.75.
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RSC Adv., 2015, 5, 91966–91973 | 91973