One-Pot Synthesis of Bicyclic ortho-Aminocarbonitrile and Multisubstituted Cyclohexa-1,3-dienamine Derivatives

Full text of DOI:10.1080/00304948.2017.1384282

Organic Preparations and Procedures International
The New Journal for Organic Synthesis
ISSN: 0030-4948 (Print) 1945-5453 (Online) Journal homepage: http://www.tandfonline.com/loi/uopp20
One-Pot Synthesis of Bicyclic ortho-
Aminocarbonitrile and Multisubstituted
Cyclohexa-1,3-dienamine Derivatives
Behrooz Maleki, Roghaie Rooky, Esmail Rezaei-Seresht & Reza Tayebee
To cite this article: Behrooz Maleki, Roghaie Rooky, Esmail Rezaei-Seresht & Reza Tayebee
(2017) One-Pot Synthesis of Bicyclic ortho-Aminocarbonitrile and Multisubstituted Cyclohexa-1,3-
dienamine Derivatives, Organic Preparations and Procedures International, 49:6, 557-567, DOI:
10.1080/00304948.2017.1384282
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Date: 02 December 2017, At: 03:36

Organic Preparations and Procedures International, 49:557–567, 2017
Copyright Ó Taylor and Francis Group, LLC
ISSN: 0030-4948 print / 1945-5453 online
DOI: 10.1080/00304948.2017.1384282
OPPI BRIEF
One-Pot Synthesis of Bicyclic ortho-
Aminocarbonitrile and Multisubstituted Cyclohexa-
1,3-dienamine Derivatives
Behrooz Maleki, Roghaie Rooky, Esmail Rezaei-Seresht,
and Reza Tayebee
Department of Chemistry, Hakim Sabzevari University, Sabzevar, 96179-76487,
Iran
Creation of molecular functionality and diversity1 from common starting materials while
mindful of economic and environmental considerations constitutes a great challenge in modern
organic chemistry.2–4 Multi-component reactions (MCRs) are the best agents for reaching this
ideal goal. MCRs are convergent reactions, in which three or more starting materials react to
form a product, where all or most of the atoms contribute to the newly formed product. The
major advantages of MCRs include lower cost, shorter reaction time, high atom-economy,
energy saving, and the avoidance of time consuming and expensive purification processes.5–8
Derivatives of bicyclic ortho-aminocarbonitrile and multisubstituted cyclohexa-1,
3-dienamine are considered important organic intermediates9-10 due to their applications
in the synthesis of heterocyclic compounds.11 Moreover, these compounds are useful pre-
cursors for the preparation of their respective dicyanoanilines12 which are significant for
their optical properties.13
These features make the preparation of bicyclic ortho-aminocarbonitriles and multi-
substituted cyclohexa-1,3-dienamines very attractive to synthetic chemists, and conse-
quently several methods have been introduced in recent years for their synthesis.14-20 One
of the simplest and most general methods involves the condensation of aldehydes (1
equiv.) and malononitrile (2 equiv.) with ketones (1 equiv.) under a variety of conditions.
This reaction has been carried out using catalysts or reagents such as 1-methylpiperidin-
4-one,21 N-butylpyridinium tetrafluoroborate [BPy]BF4,22 ammonium acetate,23 imidaz-
ole,24 Borax,25 ethanediamine,26 and b-1-imidazol-2,3,4,6-tetraacetyl-D-glucopyranosyl
bromide ([Bmim-G]C[Br]¡).27 However, many of these catalysts have disadvantages,
such as low yields, the need to activate the catalyst prior to use, the use of commercially
unavailable reactants or catalysts, harsh conditions, tedious work-up procedures, the need
to use high catalyst loading, and multistep procedures.
Received August 5, 2016; in final form August 3, 2017.
Address correspondence to Behrooz Maleki, Department of Chemistry, Hakim Sabzevari
University, Sabzevar, 96179-76487, Iran. E-mail: malekibehrooz@gmail.com
557

558
Maleki et al.
Considering the importance of these compounds, and as a continuation of our develop-
ment of efficient environmentally benign catalysts,28-36 we now report an efficient, eco-
Scheme 1
friendly, safe, green, and practical method for the synthesis of bicyclic ortho-aminocarbonitrile
and multisubstituted cyclohexa-1,3-dienamine derivatives using ortho-benzenedisulfonimide
(OBS) and triethylammonium acetate (Et3NHCOAc¡) as catalysts (Scheme 1).
We have recently reported the use of catalytic amounts of OBS as a safe, nonvolatile,
and noncorrosive Brønsted acid in several acid-catalyzed organic reactions that gave
excellent results.37–38
In general, all synthetic methods should have mild reaction conditions, short reaction
times, good selectivity and the absence of by-products. It is worthwhile to highlight the
further valuable aspect of the above reactions, namely the fact that OBS can easily be
recovered from the reaction mixtures, in good to high yield, due to its complete solubility
in water. This permits its reuse in catalytic amounts in other reactions, either directly or
after a fast purification run on a cation-exchange resin, without the loss of catalytic activ-
ity. This obviously has economic and ecological advantages.39–41
In order to optimize the reaction conditions and obtain the best catalytic activity, the
reaction of benzaldehyde (1 mmol), malononitrile (2 mmol), and cyclohexanone
(1 mmol) was used as a model and conducted with varying reaction parameters such as
solvent, temperature and amount of catalyst. The best results were obtained using
25 mol% of OBS as catalyst under reflux conditions in ethanol.
A series of bicyclic ortho-aminocarbonitrile derivatives was prepared successfully
from different aromatic aldehydes bearing electron-withdrawing and electron-donating
groups, cyclohexanone or aromatic ketones and malononitrile at 80ꢀC. In all cases, the
corresponding products 4a-k, 6a-d were obtained in good to excellent yields (Table 1).
Due to the increase in environmental consciousness in chemical research and industry, the
challenge for sustainable chemistry calls for clean procedures that avoid the use of harmful
organic solvents. In recent years, ionic liquids (ILs) have attracted increasing interest and been
successfully used in a variety of reactions as environmentally benign solvents and catalysts
due to their relatively low viscosity and vapor pressure, high thermal and chemical stability,
high conductivity, wide electrochemical window and the high solubility of inorganic, organic,
polymeric materials and gases. Much attention is currently being focused on organic reactions
with ILs as catalysts or solvents, and many chemical reactions have been performed in ILs

Bicyclic ortho-Aminocarbonitriles and Cyclohexa-1,3-dienamines
559
Table 1
Synthesis of Bicyclic ortho-Aminocarbonitrile and Multisubstituted Cyclohexa-1,3-dien-
amine Derivatives in the Presence of OBS and TEAA
mp (ꢀC)
Entry
Products (4 a-k, 6 a-d)
Yielda (%) I-II Time (h) I-II Found
93–93 6-3
255–257 255–25722
Lit.
4 a
4b
90–91
5-4
265–267 265–26822
4 c
90–88
5–4
244–246 248–25022
(Continued on next page)

560
Maleki et al.
Table 1
Synthesis of Bicyclic ortho-Aminocarbonitrile and Multisubstituted Cyclohexa-1,3-dien-
amine Derivatives in the Presence of OBS and TEAA (Continued)
mp (ꢀC)
Entry
Products (4 a-k, 6 a-d)
Yielda (%) I-II Time (h) I-II Found
82–84 7–6
266–268 271–27222
Lit.
4 d
4e
92–94
5-4
262-264 257-26022
4f
92–90
5-4
255–257 261–26222
(Continued on next page)

Bicyclic ortho-Aminocarbonitriles and Cyclohexa-1,3-dienamines
561
Table 1
Synthesis of Bicyclic ortho-Aminocarbonitrile and Multisubstituted Cyclohexa-1,3-dien-
amine Derivatives in the Presence of OBS and TEAA (Continued)
mp (ꢀC)
Entry
Products (4 a-k, 6 a-d)
Yielda (%) I-II Time (h) I-II Found
86–88 6-3
265–266 264–26522
Lit.
4 g
4 h
82–90
7-5
250–252 254–25522
4i
90–90
6-3
264-266 266-26818
(Continued on next page)

562
Maleki et al.
Table 1
Synthesis of Bicyclic ortho-Aminocarbonitrile and Multisubstituted Cyclohexa-1,3-dien-
amine Derivatives in the Presence of OBS and TEAA (Continued)
mp (ꢀC)
Entry
Products (4 a-k, 6 a-d)
Yielda (%) I-II Time (h) I-II Found
Lit.
239–241 245–24822
4j
80–83
7-6
4 k
85–89
5–4
262–264 265–26722
6 a
86–90
6–5
156–158 158–16026
(Continued on next page)

Bicyclic ortho-Aminocarbonitriles and Cyclohexa-1,3-dienamines
563
Table 1
Synthesis of Bicyclic ortho-Aminocarbonitrile and Multisubstituted Cyclohexa-1,3-dien-
amine Derivatives in the Presence of OBS and TEAA (Continued)
mp (ꢀC)
Entry
Products (4 a-k, 6 a-d)
Yielda (%) I-II Time (h) I-II Found
90–92 7–5
252–254 253–25524
Lit.
6b
6 c
88–90
7–6
245–247 246–24824
6 d
89–91
6–5
202–204 205–20926
aThe yields and times by OBS (I), and TEAA (II).
with excellent outcomes.42–49 In continuation of our recent investigations on the synthesis and
applications of the ionic liquids,50–51 we now report that triethylammonium acetate (TEAA) is
a green catalyst for the synthesis of bicyclic ortho-aminocarbonitriles (Scheme 1).
To check the suitability of TEAA for this MCR, initially the reaction of benzaldehyde
(1 mmol), malononitrile (2 mmol), and cyclohexanone (1 mmol) was tested in the presence of
TEAA (0.1 ml) under solvent–free conditions at 80ꢀC. Interestingly, in this case we also

564
Maleki et al.
achieved a 93% yield of 4a within 3 h. Then, different reaction parameters such as solvent,
temperature and amount of catalyst were investigated. Also, in comparison with¡TEAA, the
use of Et3NHC HCOO¡ (TEAF), Et3NHC HSO4¡ (TEAS), Et3NHC HNO3 (TEAN),
Et3NHC H2PO4¡ (TEAP), and Et3NHC ClSO3¡ (TEAClS) as catalysts afforded lower yields
in the model reaction under solvent-free conditions at 80ꢀC. This investigation showed that
TEAA was the most efficient catalyst in terms of the yield of 4a.
Further, to show the generality and versatility of TEAA as a catalyst, this proto-
col was extended to the synthesis of bicyclic ortho-aminocarbonitrile derivatives
(4a-k) and multisubstituted cyclohexa-1,3-dienamines (6a-d) by a one-pot reaction
of benzaldehyde (1 mmol), malononitrile (2 mmol), and cyclohexanone or aromatic
ketones (1 mmol) in the presence of TEAA (0.1 ml) under solvent–free conditions at
80ꢀC (Table 1).
The recycling of OBS was investigated using the synthesis of 4a. The catalyst
was recovered by evaporation of the combined aqueous layer and aqueous washings
under reduced pressure. The residue was passed through a column of acidic Dowex
AG 50 W-X8 ion-exchange resin (100–200 mesh, 160 mg resin/500 mg product)
with water as eluent. After removal of the water under reduced pressure, the pure
OBS was recovered as a white solid; mp 192–193ꢀC (lit.38 192–193ꢀC). It was re-
used in the model reactions to give 4a in yields of 93%, 89%, and 88%, for three
consecutive runs.
The re-usability of the TEAA was also evaluated by performing the model reaction
under the optimized conditions. After the completion of the reaction, the catalyst was
recovered and could be re-used three times without any substantial decrease in the yield
of product (93, 90, and 89%) for three consecutive runs.
In conclusion, efficient, simple, and safe procedures for the preparation of the
ortho-aminocarbonitriles and multisubstituted cyclohexa-1,3-dienamines were
reported in this work. This protocol has the advantages of including high yields,
ready availability, lower cost of the catalyst, operational simplicity, and minimiza-
tion of cost and waste generation owing to recycling of the catalyst. The reagents
are non-volatile and non-corrosive. Column chromatographic separation is not
required.
Experimental Section
All reagents were obtained from commercial sources and were used without purification.
The ionic liquids TEAA, TEAF, TEAS, TEAN, TEAP, and TEAClS were prepared
according to our previous procedure.51 IR spectra were recorded as KBr pellets on a Shi-
1
madzu 435-U-04 spectrophotometer. H and 13C NMR spectra were determined on a
Bruker DRX-300 Avance spectrometer in DMSO-d6, and shifts are given in d downfield
from tetramethylsilane (TMS) as an internal standard. Melting points were determined
using an Electrothermal 9200 apparatus and are uncorrected.
General Procedure for the Synthesis of Compounds 4a-k, 6a-d using OBS
o-Benzenedisulfonimide (0.055 g, 0.25 mmol), was added to a mixture of the aldehydes
(1 mmol), malononitrile (0.14 g, 2 mmol), cyclohexanone or aromatic ketones (1 mmol)
and 2 mL of ethanol in a 10 mL flask fitted with a reflux condenser. The resulting mixture
was heated to reflux (oil bath) for the appropriate time (see Table 1) with stirring. After
completion of the reaction as determined by TLC (silica gel; hexane-ethyl acetate, 4:1),

Bicyclic ortho-Aminocarbonitriles and Cyclohexa-1,3-dienamines
565
the mixture was poured onto crushed ice and the solid product that separated out was col-
lected, washed with water, dried and recrystallized from ethanol (96%, 10 ml) to afford
the pure compound 4a-k, 6a-d.
General Procedure for the Synthesis of Compounds 4a-k, 6a-d using TEAA
TEAA (0.1 ml), was added to a mixture of the aldehydes (1 mmol), malononitrile (0.14 g,
2 mmol) and cyclohexanone or aromatic ketones (1 mmol) in a 10 mL flask at room tem-
perature. The temperature was then raised to 80ꢀC and maintained for the appropriate
time (see Table 1) with stirring. After completion of the reaction as determined by TLC
(silica gel; hexane-ethyl acetate, 4:1), hot 96% EtOH (2 ml) was added and the mixture
was stirred for 2 min. It was then poured onto crushed ice and the solid product that sepa-
rated out was collected, washed with water, dried and recrystallized from ethanol (96%,
6 ml) to afford the pure compounds 4a-k, 6a-d.
To recover the catalyst, the filtrate from above [(containing the catalyst (TEAA)] was
extracted with CH2Cl2 (5 ml) to remove non-ionic organic impurities. Then the water was
evaporated from the aqueous phase and the residue was dried at 60ꢀC under reduced pres-
sure for 2 h and re-used it for subsequent reactions.
Analytical Data for Selected Compounds
2-Amino-4-(phenyl)-4 a,5,6,7-tetrahydronaphthalene-1,3,3-(4 H)-tricarbonitrile (4a).
IR (KBr): 3420, 3340, 3250, 3007, 2950, 2870, 2830, 2215, 1640, 1590, 1480, 1440,
1430, 1410, 1390, 1340, 1310, 1270, 1210, 1160, 950; 1H NMR (300 MHz, DMSO-d6): d
0.64-0.82 (m, 1 H, CH), 1.34-1.42 (m, 2 H, CH2), 1.60-1.82 (m, 1 H, CH), 1.92-2.25 (m,
2 H, CH2), 2.89 (m, 1 H, CH), 3.54 (d, 1 H, CH), 5.76 (s, 1 H, CH), 7.28-7.89 (m, 7 H,
NH2 and ArH); 13C NMR (75 MHz, DMSO-d6): d 21.36, 24.67, 27.56, 34.28, 43.08,
51.34, 81.96, 112.97, 117.89, 121.84, 126.78, 129.07, 133.56, 136.01, 143.92.
2-Amino-4-(4-nitrophenyl)-4 a,5,6,7-tetrahydronaphthalene-1,3,3-(4 H)-tricarbonitrile
(4i). IR (KBr): 3480, 3350, 3240, 3002, 2900, 2890, 2240, 1670, 1600, 1530, 1450,
1
1400, 1390, 1260, 1220, 1160, 880; H NMR (300 MHz, DMSO-d6): d 0.81–0.92 (m, 1
H, CH), 1.42–1.51 (m, 2 H, CH2), 1.68–1.74 (m, 1 H, CH), 2.12–2.27 (m, 2 H, CH2),
2.79–2.88 (m, 1 H, CH), 3.68 (d, 1 H, CH), 5.89 (s, 1 H, CH), 7.23 (d, 1 H, ArH), 7.39–
7.41 (m, 3 H, NH2 and ArH), 7.82–7.88 (m, 2 H, ArH); 13C NMR (75 MHz, DMSO-d6):
d 22.67, 25.09, 27.98, 34.69, 45.87, 51.66, 82.81, 113.07, 117.88, 122.09, 128.08, 129.86,
133.86, 136.75, 145.02.
2-Amino-6-(4-chlorophenyl)-4-phenylcyclohexa-2,4-diene-1,1,3-tricarbonitrile (6c). IR
(KBr): 3360, 3340, 3210, 3070, 3050, 2220, 2215, 1660, 1610, 1550, 1530, 1490, 1440,
1400, 1310, 1215, 1090, 1010, 970; 1H NMR (300 MHz, DMSO-d6): d 6.49 (d, 1 H), 7.25
(d, 2 H), 7.42–7.56 (m, 1 H), 7.65 (d, 2 H), 8.45 (s, 1 H), 9.13 (s, 1 H); 13C NMR
(75 MHz, DMSO-d6): d 44.12, 48.09, 81.94, 110.45, 112.87, 114.76, 115.90, 116.07,
116.82, 129.32, 129.41, 130.04, 132.56, 133.18, 135.09, 145.12, 163.34.

566
Maleki et al.
Acknowledgment
The authors thank the Research Council of Hakim Sabzevari University for partial sup-
port of this work.
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