Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C Bond Formation: An Innovative Pathway for Acrylonitrile Derivatives

Article abstract of DOI:10.1007/s10562-016-1793-7

Abstract: A new silica bonded N-(propylcarbamoyl)sulfamic acid (SBPCSA) catalyst has been prepared for the highly efficient synthesis of a series of acrylonitrile derivatives via solvent-free facile Knoevenagel condensation between differently substituted

Full text of DOI:10.1007/s10562-016-1793-7

Catal Lett
DOI 10.1007/s10562-016-1793-7
Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA)
Mediated Expeditious Approach to C–C Bond Formation:
An Innovative Pathway for Acrylonitrile Derivatives
Mehtab Parveen1 Shaista Azaz1 Faheem Ahmad1 Ali Mohammed Malla1
·
·
·
·
Mahboob Alam2
Received: 18 April 2016 / Accepted: 11 June 2016
© Springer Science+Business Media New York 2016
Abstract A new silica bonded N-(propylcarbamoyl)sul-
famic acid (SBPCSA) catalyst has been prepared for the
highly efficient synthesis of a series of acrylonitrile
derivatives via solvent-free facile Knoevenagel condensa-
tion between differently substituted heterocyclic/aromatic
aldehydes 1 (a–o) and 2-thiopheneacetonitrile (2). The
catalyst was characterized by FT-IR, SEM-EDX and XRD
techniques. The thermal stability of the catalyst was eval-
uated with TGA and DT analysis. The remarkable features
of the present protocol are solvent free synthesis, recycla-
bility of the catalyst, mild reaction conditions, shorter
reaction profile, excellent yield of products with applica-
bility to broader substrate scope (electron rich and electron
deficient) and exclusive formation of E-isomer of the
product. DFT calculations also revealed that E-isomer of
compound 3f is stabilized by 12.53 kcal mol−1 more than
the Z-isomer.
Graphical Abstract Efficient and economical synthesis of
acrylonitrile derivatives.
H
O
O
SiO2
O
O
Si
O
O
N
H
S
N
H
O
H
O
O
Ar
H
C
N
C
Ar
H
S
N
S
Examples:15
-
Yield: 92 98%
Solvent-free
Stirring/ 80oC
Keywords Acrylonitrile · SBPCSA · Knoevenagel
condensation · E-isomer · DFT studies
1 Introduction
In the last few decades, there has been an upsurge usage for
environmentally benign and sustainable catalyst in the
chemical industry [1, 2]. Recycling of homogeneous cata-
lysts is the main issue in large-scale production of
chemicals [3]. In this regard, substantial research efforts
have been devoted to develop catalysts with high efficacy,
selectivity and stability. Immobilization of catalysts on
solid support, leads to clean chemical synthesis for envi-
ronmental as well as economical point of view [4, 5].
Heterogeneous catalysts have gained much attraction of
Electronic supplementary material The online version of this
article (doi:10.1007/s10562-016-1793-7) contains supplementary
material, which is available to authorized users.
& Mehtab Parveen
mehtab.organic2009@gmail.com
1
Division of Organic Synthesis, Aligarh Muslim University,
Aligarh 202002, India
2
Division of Bioscience, Dongguk University,
Gyeongju 780-714, Republic of Korea
123

M. Parveen et al.
CH3
H3C
O
CH3
CH3
CH3
H
N
O
N
H
O
N
H
H
O
CH3
H
C2
N
N
5
N
H3C
N
C
H
3C
NC
C2H5
N
C
HN
O
CH3
CH3
NO2
N
C
H
3C
Rilpivirine (Edurant) [36]
Entacapone [21]
Cyenopyrafen (starmite) [37]
H
N
O
H2
C
H2
C
H
H2
C
C
H2
C
H2
C
CN
CH3
H2
C
H2
N
H2C
CH2
CH3
H
2C
N
CH3
Dynole 34-2 [38]
Fig. 1 Drugs in the market with acrylonitrile moiety in their structural framework
chemist due to economic and environmental importance
[6]. These catalysts are advantageous over homogeneous
catalysts as they can be easily recovered from the reaction
mixture by simple filtration and can be reused after acti-
vation, thereby making the process economically valuable.
Due to the favorable chemical and physical properties of
silica surfaces, it is possible to impart any reactive func-
tional group e.g., sulfonic, amine, carboxyl and thiol etc. on
silica surfaces through well-known silane chemistry [7, 8].
Therefore, use of supported and recoverable catalysts in
organic transformations has economical and environmental
benefits [9]. In this regards, carbon based solid acid cata-
lysts have attracted much more attention due to more
activity and selectivity [10–12]. These sulfonated sil-
ica/carbon hybrids have been prepared from the sulfonation
of carbonized biomaterials have been extensively used in
organic syntheses [13–15].
separation and reusability [24]. Therefore there is a need
for exploring the cheap and easily available catalysts for
Knoevenagel condensation.
Over the past few decades there has been an upsurge in
the number of biologically active compounds that contain
an acrylonitrile moiety. Acrylonitrile derivatives constitute
an important class of compounds in organic chemistry due
to their promising biological activities such as antiprolif-
erative [25], antifungal [26], antitumor [27], antibacterial
[28], antitubercular [29], antioxidative [30, 31], tubercu-
lostatic [32], antitrichomonal [33] and antiparasitic [34].
Various medicinally important drugs also possess acry-
lonitrile moiety in their structural framework viz. DG172
[35], Rilpivirine (Edurant) [36] Entacapone [21], Cyenopy-
rafen [37] and Dynole 34-2 [38] (Fig. 1).
The synthesis of acrylonitrile compounds have been
previously achieved by the use of Wittig reactions [39],
McMurry coupling [40] and the Heck reaction [41]. It is
pertinent to mention here that Knoevenagel condensation is
a facile and versatile method for the formation of acry-
lonitrile derivatives [42–44]. In the quest to achieve higher
efficiency several catalysts have been employed viz
Brønsted acid catalysts [45], Lewis acids such as MgBr2·
OEt2 [46], SnCl2 [47], Al2O3 [48] ionic liquids [C6-mim]
PF6 [49], [Bmim]Cl·xAlCl3 [50], [Bpy]Cl·xAlCl3 [50],
[Bmim]BF4 [51], ethylammonium nitrate (EAN) [52] and
silica supported acid catalyst [53, 54].
Carbon–carbon (C–C) bond formation reactions are of
significant importance in organic synthesis as they unlock
new pathways to new chemical entities [16–18]. The
Knoevenagel condensation between aldehydes and ketones
with activated methylene compounds is one of the reac-
tions which facilitates C–C bond formation [19, 20] and
has been exploited in the synthesis of some vital drugs such
as entacapone [21] pioglitazone [22] and lumefantrine [23].
The use of ammonia, amines, pyridine, piperidine and their
salts as basic catalysts in Knoevenagel condensation
restricts their applications due to their hazardous environ-
mental concerns, carcinogenic nature, problem in product
In continuation of our ongoing interest for exploring
novel synthetic methodologies for organic transformations
123

Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C…
H
O
H
O
H
O
SiO2
H
O
H
O
(MeO)
l
C
3S
i
Toluene, Reflux, 48h
O
H
H
O
O
O
O Si
O
O Si
NH2CONH2
SiO2
l
C
N
H
NH2
S O2
i
Ethanol, Reflux, 8h
O
O
ClSO3H
Dry CH2Cl2
Room temp., 2 h
O
O
S
H
O
O
O Si
SiO2
N
H
N
H
H
O
O
O
BP
A
S CS
Scheme 1 Synthetic scheme for the formation of catalyst SBPCSA
Fig. 2 FT-IR spectrum of the catalyst SBPCSA
[55, 56] under the principle of green chemistry, herein, we
first time report the synthesis of novel silica bonded N-
(propylcarbamoyl)sulfamic acid (SBPCSA) as a green,
efficient and recyclable catalyst for the synthesis of
acrylonitrile derivatives. In comparison with the present
reported methods of acrylonitrile synthesis, our approach
displays specific advantages and become more practical
than existing synthetic methodologies as it gives excellent
123

M. Parveen et al.
Fig. 3 SEM analysis of a SiO2 b catalyst SBPCSA
yields (92–98 %) within a minimum reaction time and
applicable to a broader substrate scope (electron-rich and
electron-deficient).
2 Results and Discussion
2.1 Characterization of the Catalyst
The catalyst SBPCSA was prepared by the concise route
outlined in Scheme 1. The SBPCSA was fully character-
ized by FT-IR, SEM-EDX and XRD. The FT-IR spectrum
of the catalyst (SBPCSA) is depicted in Fig. 2. The FT-IR
spectrum displayed peaks at 3152 cm−1 attributed to the
presence of the N–H bond stretching frequency of sul-
phonamide groups, which has been overlapped with O–H
stretching frequency of silanol group or the adsorbed water
molecules [57]. The corresponding C=O stretching and
bending frequency of N–H were observed at 1717 and
1575 cm−1, respectively. The peak at 1401.96 cm−1 is
assigned for C–H bending. Further, the peak at about 797
and 1112 cm−1 is attributed to the typical symmetric
stretching vibration of Si–O–Si and S=O bond of supported
SO3H group, respectively. Moreover stretching vibration of
S–N bond in the –HN–SO3H is observed at 767 cm−1 [58].
To study the surface morphology of the catalyst, SEM
micrographs of the catalyst was employed (Fig. 3). The
SEM result showed the adsorption of N-(propylcar-
bamoyl)sulfamic acid on silica surfaces. The composite is a
fine homogeneous powder in which particles were of
uneven size and shape, well dispersed on the surface of the
silica gel. The successful incorporation of urea and SO3H
groups was also confirmed by EDX analysis (Fig. 4) of the
catalyst, which showed the presence of N, S, O and Si
Fig. 4 EDX analysis of catalyst SBPCSA
elements signifying the formation of expected catalytic
system. The weight % and atomic % of elements present in
the catalyst has been showed in Table S1 (ESI). In the fresh
catalyst S is present by weight % 13.38 and atomic % 6.79
while N is present by weight % 22.37 and atomic % 26.00.
Further elemental mapping of the catalyst showed the
uniform distribution of elements present in the catalyst
(Fig. 5).
The chemical modification of silica support with N-
(propylcarbamoyl)sulfamic acid, was further explored by
powder XRD analysis (Fig. 6). The XRD pattern of the
catalyst were recorded in the 2θ range of 10°–80°. The
XRD of the catalyst showed characteristic single broad
peak of silica in the range of 2θ = 18°–25° displaying
amorphous nature of silica. However, the XRD of SPBCSA
also showed crystallinity with the characteristic peaks of
urea [59].
The thermal stability of the catalyst was evaluated by
TG analysis (Fig. 7). The TG curve showed first weight
loss of 62.84 % around 336 °C which can be attributed to
the decomposition of amide chain along with SO3H group
123

Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C…
Fig. 5 Elemental mapping of catalyst SBPCSA a carbon b nitrogen c oxygen d silicon e sulfur showing uniform distribution of catalyst surface
and physically adsorbed water molecules. Further another
weight loss of 9.1 % at 442 °C can be attributed to the loss
of Si group covalently bonded to silica surface. Hence it
can be concluded that catalyst is stable up to 336 °C. TGA
is further supported by DT analysis (Fig. 7) in which a
prominent peak at 297 and 365 °C showed endothermic
reaction which help in the removal of water, SO3H group,
amide moiety, Si group.
The optimum concentration of H+ ion was determined
by acid–base titration of the aqueous suspension of the
weighed amount of thoroughly washed catalyst with stan-
dard NaOH (0.01 N) solution and was found to be
123

M. Parveen et al.
1
on the basis of elemental analysis (C, H, N), IR, H NMR,
3000
2500
2000
1500
1000
500
13C NMR and mass spectral analysis. The results for C, H
and N analysis were within 0.3 % of the theoretical
values. The spectral analysis has been in good corrobora-
tion with the expected structural framework of the
synthesized compounds. All the synthesized compounds
showed the absence of the carbonyl peak in the IR spec-
trum, which confirmed the reaction at the carbonyl moiety.
Moreover, all compounds exhibited a characteristic peak
for cyano group resonating at around 2200–2220 cm−1.
Other characteristic peaks for the different functional
groups such as C=Oγ-pyrone, OH and NO2 are discussed in
experimental section. The 1H NMR spectrum of each
compound displayed a sharp singlet at around δ 7.40–8.21
ascribed to the olefinic proton (H-1´´). Similarly, sharp
singlets resonating at around δ 7.25, 7.01, 7.28, 7.23 each
integrating for one proton, has been attributed to H-2
protons of γ-pyrone ring of chromones 3a, 3b, 3c and 3d
respectively. Doublet at around δ 7.12–7.39 and 7.26–7.78
have been attributed to H-3´ and H-5´ protons of thiophene
ring and a multiplet at around δ 7.13–7.43 has been
attributed to H-4´ proton of thiophene ring. 13C NMR
spectra, showed a series of signals resonating at around δ
106.86–178.45 which have been assigned to aromatic
carbons, peaks resonating at around δ 126.00–137.73 have
been ascribed to carbons of thiophene ring. Similarly,
peaks resonating at around δ 117.38–119.70 corresponds to
–C≡N moiety and the signals at δ 178.50, 177.82, 177.09,
177.87 and 178.10 have been attributed to carbonyl group
(C=Oγ-pyrone) of compounds 3a, 3b, 3c, 3d and 3e,
respectively. Furthermore peaks at δ 107.20–115.49 and
152.12–153.90 corresponds to C-1′′ and C-2″, respectively.
0
10
20
30
40
50
60
70
80
2θ (degree)
Fig. 6 XRD analysis of catalyst SBPCSA
0.49 meq/g of the support. The concentration of the
residual H+ ion of the recovered catalyst was also mea-
sured and found to be small loss of H+ ion. It signified that
SO3H moiety was tightly anchored with SPBCSA, possibly
due to a covalent linkage.
2.2 Chemistry
The synthetic pathways of a series of new acrylonitrile
derivatives 3(a–o) have been shown in Scheme 2. Herein,
each series was typically accessed via Knoevenagel con-
densation between 2-thiopheneacetinitrile (2) and appro-
priately substituted heterocyclic/aromatic aldehydes 1(a–o) to
yield target acrylonitrile derivatives in excellent yields
(92–98 %) with high purity. The structural elucidation of
the synthesized compounds 3(a–o) have been established
Fig. 7 TGA/DTA analysis of catalyst SBPCSA
123

Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C…
O
H
S
SBPCSA (80 mg)
Solvent free, 80 oC
20-30 min
N
C
H
Ar
1
S
Ar
N
C
(a-o)
2
(a-o)
3
Products
Ar
Products
Ar
O
3i
3a
3b
3c
H
3CO
O
H
OC
3
O
H
3C
H
3CO
3j
O
O
H
3CO
H
OC
3
F
3k
H
O
O
O
H
O
Br
H
O
3d
O
3l
O
H
O
3e
3f
NH2
O
3m
N
H
H
3C
N
O2
3n
3o
N
H
3g
3h
N
O2
H
O
N
H
3C
H
N
CH3
Scheme 2 Synthetic scheme for the formation of acrylonitrile derivatives
The mass spectral analysis of the synthesized compounds
was also in good conformity with the proposed structures.
In the present study, it was not possible to confirm
obtained as the sole product. To probe the relative stability of
the two possible isomers, MM2 energy-minimization cal-
culations were performed. It was found that the E-isomer is
stabilized by 12.53 kcal/mol of energy than Z-isomer and this
energy difference is satisfactory enough to suggest that
during the crystallization process, the E-isomer gets exclu-
sively crystallized out from the solution. The ground state
optimized structure of E-isomer interpreted by DFT is shown
in Fig. 8, wherein the thiophene part of the molecule is planar
with the acrylic moiety, while the nitrophenyl group is
1
geometry across C=C on the basis of H NMR analysis. In
order to gain some insight into the influence of the electronic
interactions on the molecular geometry, we have performed
quantum mechanical calculations of the equilibrium geom-
etry of the free molecule. For this purpose we choose
compound 3f for the DFT study. Of the two possible geo-
metrical isomers (E/Z) of the compound 3f, E-isomer was
123

M. Parveen et al.
Fig. 8 Ground state optimized structure of a (E)-isomer and b (Z)-isomer of compound 3f
Fig. 9 Electron density distribution in a HOMO and b LUMO of (E)-isomer of compound 3f
Fig. 10 Dreiding models of the E and Z-geometrical isomers of the compound 3f
pushed out of the plane, probably by the electronic interac-
tions between the two lone pairs of sulfur atom of thiophene
ring and hydrogen atom (H23) of nitrophenyl ring (:S:–H23).
The optimized geometry exhibits the E-configuration of the
thiophene and nitrophenyl group about the acrylic double
bond (Fig. 8). The energies of highest occupied molecular
orbital (EHOMO) and lowest unoccupied molecular orbital
(ELUMO) and their distributions using DFT-B3LYP/6-311G
were calculated using grid based density functional theory
(DFT) at the B3LYP/6-311G basis set level. The calculated
energies of HOMO and LUMO were found to be −11.89 and
−4.36 eV, respectively, for the optimized E-isomer. The
energies of HOMO and LUMO, including neighboring
orbitals, were all negative, indicating that E-isomer is stable.
It was observed that the highest occupied molecular orbitals
in E-isomer is located in the thiophene ring and acrylic
123

Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C…
Table 1 Effect of different solvents on model reaction
Entry
Solvent
Temp (oC)
Time (h)a
Yield (%)b
1
2
3
4
5
6
7
MeOH
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
6
70
68
66
75
65
63
98
EtOH
8
Water
3
CH3COOH
CH2Cl2
DMF
3
6.5
7
20c
Solvent-free
Reaction condition 3-nitrobenzaldehyde (1f, 2 mmol), 2-thiopheneacetonitrile (2, 2 mmol), different solvents (20 mL), SBPCSA (80 mg), 80 °C
a
Reaction progress monitored by TLC
b
Isolated yield of products
c
Reaction progress monitored by TLC (entry 7, min)
Table 2 Effect of catalyst loading on model reaction
Entry
Catalyst (mg)
Time (min)a
Yield (%)b
1
2
3
4
5
6
10
20
120
80
55
40
20
20
65
72
79
84
98
98
40
60
80
100
Reaction condition 3-nitrobenzaldehyde (1f, 2 mmol), 2-thiopheneacetonitrile (2, 2 mmol), solvent free, SBPCSA (10–100 mg), 80 °C
a
Reaction progress monitored by TLC
b
Isolated yield of products
2.3 Optimization of Reaction Conditions
moiety while lowest unoccupied molecular orbitals is mainly
localized on the nitro phenyl ring (Fig. 9). E-isomer selec-
tivity in the present protocol was further verified on the basis
of dreiding energy concept calculated by using ChemAxon,
E and Z-isomers were found to have 63.70 and 92.21 kcal/-
mol of dreiding energy, respectively. This energy difference
of 29.15 kcal/mol is favorable for the selective formation of
E-isomer (Fig. 10). On the basis of these results it was
believed that all the synthesized compounds possess E-
configuration.
Initially, we focused our study to probe the optimized
reaction conditions for the present protocol regarding the
choice of solvent, amount of catalyst, temperature of
reaction and investigating efficiency of various catalyst on
a selected model reaction using 3-nitrobenzaldehyde (1f)
and 2-thiopheneacetonitrile (2) in the presence of SBPCSA
to establish the best possible reaction conditions for the
synthesis of acrylonitrile 3f.
123

M. Parveen et al.
Table 3 Effect of temperature on model reaction
Entry
Temperature (oC)
Time (h)a
Yield (%)b
1
2
3
4
5
6
Room temp
3.0
2.5
2.0
1.0
20c
20c
66
72
85
92
98
98
40
55
70
80
100
Reaction condition 3-nitrobenzaldehyde (1f, 2 mmol), 2-thiopheneacetonitrile (2, 2 mmol), solvent free, SBPCSA (80 mg), 25–100 °C
a
Reaction progress monitored by TLC
b
Isolated yield of products
c
Reaction progress monitored by TLC (entry 5–6, min)
Table 4 Comparison of the efficiency of SBPCSA with different catalysts on the model reaction
Entry
Catalyst
Time h/(min)a
Yield (%)b
1
2
3
4
5
6
7
8
9
–
300
240
80
Traces
40
SiO2
SiO2–NH4SO4
SiO2–Cl
SiO2–H2SO4
SiO2–HClO4
NH2SO3H
SBNPU
74
100
65
70
76
48
81
55
89
60
83
SBPCSA
20
98
Reaction condition 3-nitrobenzaldehyde (1f, 2 mmol), 2-thiopheneacetonitrile (2, 2 mmol), solvent free, different catalysts (80 mg), 80 °C
a
Reaction progress monitored by TLC
b
Isolated yield of products
2.3.1 Effect of Different Reaction Media
the product 70 and 68 %, respectively, was obtained after a
stretched time period (6–8 h). This moderate yield can be
attributed to the nucleophilic nature of these solvents,
which may force the reaction to undergo nucleophilic
competition between these solvents (MeOH, EtOH) and
active methylene (2-thiopheneacetonitrile) for electrophilic
carbon of carbonyl group that will eventually results in
In order to optimize the reaction conditions we first probed
the effect of solvents by carrying out the model reaction in
various conventional organic solvent systems. Initially the
model reaction was performed in organic solvents like
MeOH and EtOH (Table 1, entries 1–2) a moderate yield of
123

Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C…
Table 5 Synthesis of acrylonitrile derivatives 3(a–o)
Product
Structure
Reaction in presence of piperidinea Reaction inpresence of catalystb M.P °C
Time yield
(h)
Time yield
(min)
(%)
69
(%)
96
3a
6.0
20
213–214
3b
3c
3d
3e
7.5
6.0
7.0
7.5
72
70
70
68
24
20
22
25
94
98
96
94
198–200
211
220
230–232
3f
6.5
70
20
98
150
3g
3h
6.0
7.5
72
67
20
25
96
98
125
132
3i
3j
8.0
8.0
60
68
26
30
98
95
136
149
123

M. Parveen et al.
Table 5 continued
Product
Structure
Reaction in presence of piperidinea Reaction inpresence of catalystb M.P °C
Time yield
(h)
Time yield
(min)
(%)
62
(%)
92
3k
8.0
26
158
3l
7.0
6.0
60
65
30
20
94
98
132
195
3m
3n
3o
a
6.5
62
22
94
198
7.0
68
24
95
210
Reaction conditions Differently substituted heterocyclic/aromatic aldehydes 1(a–o) with 2-thiopheneacetonitrile (2) under reflux in ethanol in
the presence of piperidine (5 mol%)
b
Reaction conditions Differently substituted heterocyclic/aromatic aldehydes 1(a–o) with 2-thiopheneacetonitrile (2) in presence of SBPCSA
(80 mg) at 80 °C
lower yield of the desired product (3f), whereas in water
(Table 1, entry 3) the product was obtained in 66 % yield
after refluxing for 3 h. This apparent drop in reaction time
in water is believed to be due to the hydrogen bonding
between the water and carbonyl group of the substrate,
which may stabilizes the intermediate structure during the
formation of product. In CH3COOH, the yield of the
desired product increased significantly (75 %) with reduced
reaction time (Table 1, entry 4). This enhancement in yield
in CH3COOH solvent is probably due to its ability to
trigger the carbonyl group of the reactants by electromeric
effect, thereby enhancing the electrophilicity of carbon,
rendering it more feasible for nucleophilic attack by the
active methylene 2-thiopheneacetonitrile. However, when
the reaction was carried out in non-coordinating solvents
like CH2Cl2 and DMF no further significant increase in the
yield of the product was observed in comparison to CH3
COOH after a stretched reaction time (Table 1, entries 5
and 6). Moreover, when the model reaction was explored in
solvent-free condition, there was remarkable increase in the
yield of the product (98 %) with prominent fall in reaction
time (20 min) (Table 1, entry 7). It is evident from the
result that nature of solvent plays a crucial role in the
degree of selectivity of the desired product (3f). In view of
123

Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C…
the above results, it was concluded that solvent-free con-
dition is the best condition for the synthesis of acrylonitrile
derivatives.
reaction was tested with blank-SiO2, SiO2–NH4SO4 and
SiO2–Cl, moderate yield of products were obtain with
prolonged time period (Table 4, entries 2–4). When the
reaction was carried out in presence of SiO2–H2SO4 and
SiO2–HClO4 there was an increase in the yield of product
with decrease in the reaction time (Table 4, entries 5, 6). To
obtain better yield in less reaction time we further use
sulfamic acid and SBNPU to catalyze the reaction and
found better results in term of yield and time (Table 4,
entries 7, 8). Moreover, when the model reaction was
probed with SBPCSA the yield of product (3f) increased
exponentially (98 %) with a prominent dip in reaction time
(20 min).
2.3.2 Effect of Catalyst Loading
To achieve the optimum concentration of the catalyst for
the present protocol, the model reaction was investigated at
different concentrations i.e., 10, 20, 40, 60, 80 and 100 mg
(Table 2) of the catalyst SBPCSA at 80 °C under solvent-
free condition and the results were noted in terms of
reaction time and yield. It was inferred from Table 2 that
with every subsequent increase in concentration of catalyst
from 10 to 80 mg, there has been a noteworthy improve-
ment in the yield from 65 to 98 %, with prominent drop in
reaction time from 120 to 20 min (entries 1–5, Table 2).
However, further increase in the concentration of the cat-
alyst ([80 mg) did not have any significant effect on the
reaction. Thus, it can be concluded from the above results
that 80 mg of the catalyst is adequate to gain the optimum
yield in the shortest reaction time under neat conditions at
80 °C, therefore 80 mg of the catalyst was selected for
further studies.
98
95
91
100
86
85
80
Time (min)
60
Yield (%)
40
20
20
20
20
0
20
20
5
1
2
3
4
6
Fig. 11 Recyclability of the catalyst SBPCSA for the model reaction
2.3.3 Effect of Temperature
To optimize the reaction temperature, the model reaction
was carried out at different temperatures in presence of
catalyst SBPCSA (Table 3). The reaction was initially
tested at room temperature and does not give satisfactory
yield of desired product 3f (Table 3, entry 1). It was
observed that the increase in temperature from 25 to 80 °C,
has a noteworthy effect on the model reaction with increase
in the yield of desired product 3f (66–98 %) with the
prominent decrease in the reaction time (Table 3, entry 1–
5). However, a further increase in the temperature from 80
to 100 °C did not show any further increase in the yield of
the product 3f (Table 3, entry 6). Thus, keeping in view the
above optimized reaction conditions; 80 °C was preferred
as the optimal temperature for all the reactions in the
presence of 80 mg of SBPCSA under solvent-free
conditions.
2.3.4 Comparison of Efficacy of Silica Bonded N-
(Propylcarbamoyl)sulfamic acid (SBPCSA)
A comparative study of a variety of catalysts was con-
ducted to probe the superiority of our catalyst SBPCSA
(Table 4). The model reaction was first investigated with-
out catalyst and it was found that the reaction took
prolonged reaction time with trace of the yield. Further the
Fig. 12 SEM and EDX analysis of recovered catalyst SBPCSA
123

M. Parveen et al.
Using these optimized reaction conditions as discussed
above, the efficacy of this approach was explored for a
wide variety of heterocyclic/aromatic aldehydes possessing
electron-withdrawing and electron-donating groups for the
synthesis of acrylonitrile derivatives in excellent yields
(92–98 %) (Table 5). In the present study a comparative
study has also been carried out for the present protocol with
the conventional Knoevenagel condensation by carrying
out the reaction of aldehydes with 2-thiopheneacetonitrile
under reflux in ethanol in the presence of 5 mol% of
piperidine. It was observed that the reaction took prolonged
reaction time (6–8 h) for completion with moderate yield
(60–72 %). The results revealed that employing SBPCSA
in the present protocol enhances selectivity and product
conversion thus, proves beneficial over the conventional
method for the synthesis of acrylonitrile in terms of yield
and reaction times.
process. After completion of the reaction, catalyst was
removed by simple filtration, washed with ethanol and
dried under vacuum at 80 °C for 6 h and was further tested
up to four more reaction cycles. Recycling and reuse of the
catalyst showed minimal decreases in yields (Fig. 11).
Although the reaction rate get decreased gradually with
repetition of the reaction cycle, however we succeeded in
obtaining the desired product 3f in satisfactory yield (85 %)
even after 5th repetition of the model reaction without any
addition of the fresh catalyst (Fig. 11). To ascertain the
variation in morphological features of the recovered cata-
lyst, we carry out its SEM-EDX analysis (Fig. 12). It was
observed that the composition of the catalytic system was
almost consistent with the fresh catalyst and also there was
no significant change observed in the morphology of the
catalyst as compared to the fresh catalyst.
2.5 Reaction Mechanism
2.4 Recyclability of the Catalyst
A plausible mechanistic pathway is proposed in Scheme 3,
to illustrate the synthesis of acrylonitrile derivatives cat-
alyzed by SBPCSA. The initial step is assumed to be the
The reusability of the catalyst was also explored for the
selected model reaction in order to reduce the cost of the
O
O
S
O
H
O
O
O
O
Si
N
H
N
H
OH
SiO2
H
S
r
A
O
S
O
O
N
C
H
O
SiO2
H
r
A
H
2O
Acrylonitrile
SBPCSA
(I)
O
S
O
H
H
O
S
SiO2
O
H
O
Catalytic Cycle
r
A
H
r
A
H
N
(III)
C
(II)
O
S
O
SiO2
O
Condensation
H
O
O
S
O
H
H
SiO2
O
r
A
H
N
S
C
H
H
S
C
N
Scheme 3 Plausible mechanistic pathway for the synthesis of acrylonitrile derivatives
123

Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C…
protonation of formyl group (–CHO) of substrates (I) by
protic SBPCSA catalyst to form intermediate (II), which
facilitates the nucleophilic attack of 2-thiopheneacetonitrile
to promote the formation of C–C bond to yield interme-
diate (III).The subsequent elimination of H2O molecule
from intermediate (III) promoted by catalyst SBPCSA
eventually yielded target compound followed by regener-
ation of the catalyst.
chromatography (TLC) glass plates (20 9 5 cm) were
coated with silica gel G (Merck) using benzene-acetone
(8:2) mixture as mobile phase and exposed to iodine vapors
to check the homogeneity as well as the progress of the
reaction.
4.2 Synthesis of Catalyst
4.2.1 Preparation of 3-Chloropropylsilica [60]
3 Conclusions
In a typical procedure 5 mL (25 mmol) of (3-chloro-
propyl)-trimethoxysilane was dissolved in 100 mL of dried
toluene. 5 g of SiO2 was added to this mixture and the
solution was stirred for 18 h at 60 °C. Then the solid
residue was filtered, washed with toluene and dried in
vacuum.
The present protocol reports a convenient, eco-friendly and
sustainable approach for the synthesis of E-acrylonitrile
derivatives 3(a–o) in excellent yields (92–98 %) by
employing SBPCSA as a catalyst. This solvent-free, green
synthetic procedure eliminates the use of toxic solvents and
thus makes it distinctive one in organic synthesis. The pro-
tocol offers mild reaction conditions, shorter reaction time,
high purity, operational simplicity, cleaner reaction profile,
enhanced reaction rates and easy workup. The catalyst
SBPCSA is easily synthesized and can be used up to five
cycles without any significant loss in catalytic activity. We
believe that this synthetic approach provides a better scope
for the synthesis of acrylonitrile analogues and will be a
more practical alternative to the other existing methods.
4.2.2 Preparation of Urea Functionalized Propylsilica
The synthesized chloropropyl silica (3 g) was added to a
solution of urea (1.2 g, 20 mmol) in ethanol (50 mL) in a
round-bottom flask and the mixture was stirred under reflux
condition for 8 h. The obtained solid was then filtered and
washed with ethanol followed by drying at 80 °C for 12 h.
4.2.3 Preparation of Silica Bonded N-
(Propycarbamoyl)sulfamic acid (SBPCSA) [61]
4 Experimental
To a mixture of urea functionalized propyl silica (2.5 g) in
CH2Cl2 (20 mL), chlorosulphonic acid (1.2 mL) was added
drop wise at room temperature over a period of 30 min.
After addition was completed, the mixture was further
stirred for 90 min and HCl gas evolution was monitored
with a pH paper indicator. The mixture was filtered and
washed with CH2Cl2 (50 mL) and dried in vacuum at 80 °C
to afford SBPCSA.
4.1 Materials and General Methods
Chemicals were purchased from Merck and Sigma-Aldrich
as ‘synthesis grade’ and used without further purification.
Elemental analysis (C, H, N) was conducted using Carlo
Erba analyzer model 1108. Melting points were determined
on a Kofler apparatus and are uncorrected. The IR spectra
were recorded with a Shimadzu IR-408 Perkin-Elmer1800
instrument (FTIR), and the values are given in cm−1. H
1
NMR and 13C NMR spectra were run in DMSO-d6 on a
Bruker Avance-II 400 MHz instrument with TMS as an
internal standard and J values measured in Hertz. Chemical
shifts are reported in ppm (δ) relative to TMS. Mass spectra
were recorded on a JEOLD-300 mass spectrometer. X-ray
diffractogram (XRD) of the catalyst were recorded in the
2θ range of 20°–80° with a scan rate of 41 min−1 on a
Shimadzu-6100 X-ray diffractometer with Ni-filtered Cu
Kα radiation at a wavelength of 1.54060 Å. The scanning
electron microscope (SEM-EDX) analysis was obtained
using a JEOL (JSM-6510) equipped with an energy dis-
persive X-ray spectrometer at different magnification. TGA
has been carried out with DTG-60H (Simultaneous DTA-
TG Apparatus), Shimadzu instrument. Thin layer
4.3 General Procedure for the Synthesis
of Acrylonitrile Derivatives
To a mixture of substituted aromatic aldehydes 1(a–
o) (2 mmol) and 2-thiopheneacetonitrile 2 (2 mmol), 80 mg
of SBPCSA was added and the reaction mixture was heated
on an oil bath at 80 °C for (20–30 min) with stirring. After
completion of the reaction as evident from thin layer
chromatography (TLC), the reaction mixture was diluted
with ethanol and filtered off to recover the catalyst for
further use in catalytic cycles. The filtrate was evaporated
under reduced pressure to obtain the product. The crude
product was further purified by crystallization from
appropriate solvent to afford the pure product 3(a–o).
123

M. Parveen et al.
4.4 Spectral Characterization
(C-1´´), 152.12 (C-2´´), 177.09 (C=O), 118.13 (CN). MS
(EI): (m/z) 297.03 [M+·].
4.4.1 (E)-3-(4-Oxo-4H-chromen-3-yl)-2-(thiophen-2-yl)
acrylonitrile (3a)
4.4.4 (E)-3-(6-Bromo-4-oxo-4H-chromen-3-yl)-2-
(thiophen-2-yl)acrylonitrile (3d)
Yellow crystalline solid, yield 96 %, m.p. 213–214 °C,
Analytical cal. C16H9NO2S: C, 68.80; H, 3.25; N, 5.01;
found: C, 68.77; H, 3.26; N, 5.03. IR (KBr cm−1): 2219
(C≡N), 1652 (C=Oγ-pyrone), 1612 (C=Cγ-pyrone), 1560, 1462
(C=Caromatic). 1H NMR (400 MHz, DMSO-d6, δ, ppm):7.25
(s, 1H, H-2), 8.01 (d, 1H, H-5), 7.45 (m, 1H, H-6), 7.58 (m,
1H, H-7), 7.58 (d, 1H, H-8), 7.40 (s, 1H, =CHolifinic), 7.38
(d, 1H, H-3´), 7.20 (m, 1H, H-4´), 7.70 (d, 1H, H-5´). 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 150.12 (C-2), 118.50
(C-3), 178.45 (C-4), 124.82 (C-5), 123.83 (C-6), 135.51
(C-7), 116.82 (C-8), 125.54 (C-4a), 152.44 (C-8a), 136.05
(C-2´), 127.42 (C-3´), 127.15 (C-4´), 131.51 (C-5´), 110.45
(C-1´´), 152.84 (C-2´´), 178.50 (C=O), 117.91 (CN). MS
(EI): (m/z) 279.04 [M+·].
Yellow solid, yield 96 %, m.p. 220 °C, Analytical cal.
C16H8BrNO2S: C, 53.65; H, 2.25; N, 3.91; found: C, 53.63;
H, 2.26; N, 3.93. IR (KBr cm−1): 2214 (C≡N), 1665
(C=Oγ-pyrone), 1627 (C=Cγ-pyrone), 1554, 1467 (C=Caromatic).
1H NMR (400 MHz, DMSO-d6, δ, ppm): 7.23 (s, 1H, H-2),
7.94 (s, 1H, H-5), 7.78 (d, 1H, H-7), 7.10 (d, 1H, H-8), 8.09
(s, 1H, =CH olifinic), 7.38 (d, 1H, H-3´), 7.20 (m, 1H, H-4´),
7.63 (d, 1H, H-5´). 13C NMR (100 MHz, DMSO-d6, δ,
ppm): 149.90 (C-2), 119.08 (C-3), 177.81 (C-4), 135.82 (C-
5), 124.8 (C-6), 143.51 (C-7), 118.70 (C-8), 127.25 (C-4a),
157.91 (C-8a), 136.90 (C-2´), 128.26 (C-3´), 129.81 (C-4´),
131.82 (C-5´), 107.20 (C-1´´), 153.15 (C-2´´), 177.87
(C=O), 118.90 (CN). MS (EI): (m/z) 358.94 [M+·].
4.4.2 (E)-3-(6-Methyl-4-oxo-4H-chromen-3-yl)-2-
4.4.5 (E)-3-(2-Amino-4-oxo-4H-chromen-3-yl)-2-
(thiophen-2-yl)acrylonitrile (3b)
(thiophen-2-yl)acrylonitrile (3e)
Yellow solid, yield 94 %, m.p. 198–200 °C, Analytical cal.
C17H11NO2S: C, 69.61; H, 3.78; N, 4.77; found: C, 69.60;
H, 3.79; N, 4.74. IR (KBr cm−1): 2215 (C≡N), 1658
(C=Oγ-pyrone), 1618 (C=Cγ-pyrone), 1558, 1461 (C=Caromatic).
1H NMR (400 MHz, DMSO-d6, δ, ppm): 7.01 (s, 1H, H-2),
7.80 (s, 1H, H-5), 7.84 (m, 1H, H-7), 7.58 (d, 1H, H-8),
2.38 (s, 3H, CH3), 7.45 (s, 1H, =CHolifinic), 7.39 (d, 1H,
H-3´), 7.22 (m, 1H, H-4´), 7.75 (d, 1H, H-5´). 13C NMR
(100 MHz, DMSO-d6, δ, ppm): 150.56 (C-2), 118.96 (C-3),
177.82 (C-4), 123.87 (C-5), 133.92 (C-6), 137.43 (C-7),
113.12 (C-8), 21.81 (CH3), 125.77 (C-4a), 152.32 (C-8a),
134.89 (C-2´), 127.53 (C-3´), 127.01 (C-4´), 131.84 (C-5´),
115.49 (C-1´´), 154.80 (C-2´´), 177.82 (C=O), 117.38
(CN). MS (EI): (m/z) 293.05 [M+·].
Yellow solid, yield 94 %, m.p. 230–232 °C, Analytical cal.
C16H10N2O2S: C, 65.29; H, 3.42; N, 9.52; found: C, 65.26;
H, 3.44; N, 9.53.IR (KBr cm−1): 2220 (C≡N), 1651
(C=Oγ-pyrone), 1614 (C=Cγ-pyrone), 1565, 1461 (C=Caromatic).
1H NMR (400 MHz, DMSO-d6, δ, ppm): 8.5 (s, 2H, N–H,
D2O exchangeable), 7.75 (d, 1H, H-5), 7.48 (m, 1H, H-6),
7.58 (m, 1H, H-7), 7.56 (d, 1H, H-8), 8.12 (s, 1H,
=CHolifinic), 7.36 (d, 1H, H-3´), 7.18 (m, 1H, H-4´), 7.70 (d,
1H, H-5´). 13C NMR (100 MHz, DMSO-d6, δ, ppm):
168.12 (C-2), 106.88 (C-3), 178.14 (C-4), 125.80 (C-5),
124.81 (C-6), 135.85 (C-7), 117.02 (C-8), 124.51 (C-4a),
158.45 (C-8a), 136.33 (C-2´), 126.42 (C-3´), 127.71 (C-4´),
131.73 (C-5´), 114.28 (C-1´´), 153.56 (C-2´´), 178.10
(C=O), 118.06 (CN). MS (EI): (m/z) 294.05 [M+·].
4.4.3 (E)-3-(6-Fluoro-4-oxo-4H-chromen-3-Yl)-2-
(thiophen-2-Yl)acrylonitrile (3c)
4.4.6 (E)-3-(3-Nitrophenyl)-2-(thiophen-2-yl)acrylonitrile
(3f)
Yellow crystalline solid, yield 98 %, m.p. 211 °C, Ana-
lytical cal. C16H8FNO2S: C, 64.64; H, 2.71; N, 4.71; found:
C, 64.62; H, 2.70; N, 4.74. IR (KBr cm−1): 2219 (C≡N),
1662 (C=Oγ-pyrone), 1620 (C=Cγ-pyrone), 1559, 1464
Yellow crystalline solid, yield 98 %, m.p. 150 °C, Ana-
lytical cal. C13H8N2O2S: C, 60.93; H, 3.15; N, 10.93;
found: C, 60.90; H, 3.16; N, 10.95. IR (KBr cm−1): 2218
1
(C=Caromatic). H NMR (400 MHz, DMSO-d6, δ, ppm):
1
(C ≡ N), 1562, 1440 (C=Caromatic), 1518, 1320 (NO2). H
7.28 (s, 1H, H-2), 7.80 (s, 1H, H-5), 7.68 (d, 1H, H-7), 7.50
(d, 1H, H-8), 7.48 (s, 1H, =CHolifinic), 7.36 (d, 1H, H-3´),
7.20 (m, 1H, H-4´), 7.73 (d, 1H, H-5´). 13C NMR
(100 MHz, DMSO-d6, δ, ppm): 149.61 (C-2), 118.02 (C-3),
177.00 (C-4), 109.81 (C-5), 161.84 (C-6), 123.52 (C-7),
121.73 (C-8), 125.22 (C-4a), 152.91 (C-8a), 136.73 (C-2´),
127.26 (C-3´), 128.84 (C-4´), 131.03 (C-5´), 112.22
NMR (400 MHz, DMSO-d6, δ, ppm): 8.50 (s, 1H, H-2),
7.48 (d, 1H, H-4), 8.26–8.31 (t, 1H, H-5), 7.47–7.48 (d, 1H,
H-6), 7.67 (s, 1H, =CHolifinic), 7.12–7.14 (d, 1H, H-3´),
7.39–7.43 (t, 1H, H-4´), 7.26 (d, 1H, H-5´). 13C NMR
(100 MHz, DMSO-d6, δ, ppm): 136.51 (C-1), 122.12 (C-2),
147.35 (C-3), 124.82 (C-4), 129.26 (C-5), 136.11 (C-6),
123

Silica Bonded N-(Propylcarbamoyl)sulfamic acid (SBPCSA) Mediated Expeditious Approach to C–C…
4.4.10 (E)-2-(Thiophen-2-yl)-3-(3,4,5-trimethoxyphenyl)
135.21 (C-2´), 126.72 (C-3´), 128.90 (C-4´), 130.18 (C-5´),
107.68 (C-1´´), 152.44 (C-2´´), 118.34 (CN). MS (EI): (m/
z) 256.03 [M+·].
acrylonitrile (3j)
Yellow crystalline solid, yield 95 %, m.p. 149 °C, Analyt-
ical cal. C16H15NO3S: C, 63.77; H, 5.02; N, 4.65; found: C,
63.75; H, 5.05; N, 4.64. IR (KBr cm−1): 2212 (C≡N), 1562,
1449 (C=Caromatic). 1H NMR (400 MHz, DMSO-d6, δ,
ppm): 7.12 (s, 2H, H-2 and H-6), 7.97 (s, 1H, =CHolifinic),
7.33 (d, 1H, H-3´), 7.21 (m, 1H, H-4´), 7.78 (d, 1H, H-5´),
3.89 (s, 9H, OCH3 9 3). 13C NMR (100 MHz, DMSO-d6, δ,
ppm): 128.21 (C-1), 107.62 (C-2 and C-6), 154.84 (C-3 and
C-5), 138.86 (C-4), 135.94 (C-2´), 127.02 (C-3´), 128.90
(C-4´), 131.91 (C-5´), 108.22 (C-1´´), 152.12 (C-2´´),
117.90 (CN), 56.51 (CH3). MS (EI): (m/z) 301.08 [M+·].
4.4.7 (E)-3-(4-Nitrophenyl)-2-(thiophen-2-yl)acrylonitrile
(3g)
Yellow crystalline solid, yield 96 %, m.p. 125 °C, Ana-
lytical cal. C13H8N2O2S: C, 60.93; H, 3.15; N, 10.93;
found: C, 60.90; H, 3.17; N, 10.94. IR (KBr cm−1): 2214
(C≡N), 1560, 1445 (C=Caromatic), 1512, 1322 (NO2).1H
NMR (400 MHz, DMSO-d6, δ, ppm): 8.0 (dd, 2H, H-2 and
H-6), 8.15 (dd, 2H, H-4 and H-6), 7.41 (s, 1H, =CHolifinic),
7.20 (d, 1H, H-3´), 7.17 (m, 1H, H-4´), 7.60 (d, 1H, H-5´).
13C NMR (100 MHz, DMSO-d6, δ, ppm): 141.04 (C-1),
128.51 (C-2 and C-6), 122.80 (C-3 and C-5), 157.81 (C-4),
136.61 (C-2´), 126.62 (C-3´), 128.34 (C-4´), 131.52 (C-5´),
108.26 (C-1´´), 153.18 (C-2´´), 119.70 (CN). MS (EI): (m/
z) 256.03 [M+·].
4.4.11 (E)-2-(Thiophen-2-yl)-3-(3,4,5-trihydroxyphenyl)
acrylonitrile (3k)
Yellow solid, yield 92 %, m.p. 158 °C, Analytical cal.
C13H9NO3S: C, 60.22; H, 3.50; N, 5.40; found: C, 60.20; H,
3.53; N, 5.39. IR (KBr cm−1): 2214 (C≡N), 1556, 1448
(C=Caromatic). 1H NMR (400 MHz, DMSO-d6, δ, ppm): 7.42
(s, 2H, H-2 and H-6), 8.00 (s, 1H, =CHolifinic), 7.32 (d, 1H,
H-3´), 7.13 (m, 1H, H-4´), 7.54 (d, 1H, H-5´), 5.35 (s, 3H,
-OH 9 3, D2O-exchangeable). 13C NMR (100 MHz, DMSO-
d6, δ, ppm): 131.24 (C-1), 107.41 (C-2), 148.80 (C-3), 134.54
(C-4), 146.32 (C-5), 106.86 (C-6), 135.81 (C-2´), 127.85
(C-3´), 127.90 (C-4´), 131.08 (C-5´), 108.45 (C-1´´), 152.44
(C-2´´), 118.22 (CN). MS (EI): (m/z) 259.03 [M+·].
4.4.8 (E)-3-(4-(Dimethylamino)phenyl)-2-(thiophen-2-yl)
acrylonitrile (3h)
Brown crystalline solid, yield 98 %, m.p. 132 °C, Analyt-
ical cal. C15H14N2S: C, 70.83; H, 5.55; N, 11.01; found: C,
70.80; H, 5.56; N, 11.03; IR (KBr cm−1): 2218 (C≡N),
1567, 1445 (C=Caromatic).1H NMR (400 MHz, DMSO-d6,
δ, ppm): 7.62 (dd, 2H, H-2 and H-6), 6.82 (dd, H-3 and
H-5), 8.02 (s, 1H, =CHolifinic), 7.24 (d, 1H, H-3´), 7.18 (m,
1H, H-4´), 7.54 (d, 1H, H-5´), 3.11 (s, 6H, CH3 9 2). 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 124.01 (C-1), 128.50
(C-2 and C-6), 112.32 (C-3 and C-5), 151.85 (C-4), 137.73
(C-2´), 126.00 (C-3´), 127.31 (C-4´), 137.73 (C-5´), 108.10
(C-1´´), 153.80 (C-2´´), 118.42 (CN), 42.15 (CH3). MS
(EI): (m/z) 254.09 [M+·].
4.4.12 (E)-3-(2-Hydroxynaphthalen-1-yl)-2-(thiophen-2-yl)
acrylonitrile (3l)
Bright yellow solid, yield 94 %, m.p. 132 °C, Analytical
cal. C17H11NOS: C, 73.62; H, 4.00; N, 5.05; found: C,
73.62; H, 4.03; N, 5.02. IR (KBr cm−1): 2212 (C≡N), 1565,
1448 (C=Caromatic). 1H NMR (400 MHz, DMSO-d6, δ,
ppm): 7.69 (d, 1H, H-3), 7.90 (d, 1H, H-4), 7.62 (m, 1H,
H-5), 7.53 (m, 1H, H-6), 7.95 (m, 1H, H-7), 8.40 (d, 1H,
H-8), 8.21 (s, 1H, =CHolifinic), 7.38 (d, 1H, H-3´), 7.20 (m,
1H, H-4´), 7.68 (d, 1H, H-5´), 5.35 (s, 1H, -OH, D2O-
exchangeable). 13C NMR (100 MHz, DMSO-d6, δ, ppm):
107.50 (C-1), 158.02 (C-2), 110.89 (C-3), 127.01(C-4),
127.22 (C-5), 123.90 (C-6), 128.21 (C-7), 115.56 (C-8),
124.96 (C-9), 141.11 (C-10), 135.91 (C-2´), 126.41 (C-3´),
127.90 (C-4´), 131.18 (C-5´), 108.08 (C-1´´), 153.41 (C-
2´´), 118.20 (CN). MS (EI): (m/z) 227.04 [M+·].
4.4.9 (E)-3-(3,4-Dimethoxyphenyl)-2-(thiophen-2-yl)
acrylonitrile (3i)
Pale yellow solid, yield 98 %, m.p. 136 °C, Analytical cal.
C15H13NO2S: C, 66.40; H, 4.83; N, 5.16; found: C, 66.41;
H, 4.80; N, 5.18. IR (KBr cm−1): 2215 (C≡N), 1560, 1445
1
(C=Caromatic). H NMR (400 MHz, DMSO-d6, δ, ppm):
7.82 (s, 1H, H-2), 7.1 (d, 1H, H-5), 7.76 (d, 1H, H-6), 7.45
(s, 1H, =CHolifinic), 7.39 (d, 1H, H-3´), 7.20 (m, 1H, H-4´),
7.68 (d, 1H, H-5´), 3.86 (s, 6H, OCH3 9 2). 13C NMR
(100 MHz, DMSO-d6, δ, ppm): 129.21 (C-1), 112.61 (C-2),
149.83 (C-3), 148.84 (C-4), 117.35 (C-5), 123.80 (C-6),
135.05 (C-2´), 127.91 (C-3´), 128.73 (C-4´), 132.94 (C-5´),
108.08 (C-1´´), 153.42 (C-2´´), 118.20 (CN), 56.21 (CH3).
MS (EI): (m/z) 271.07 [M+·].
4.4.13 (E)-3-(1H-Indol-3-yl)-2-(thiophen-2-yl)acrylonitrile
(3m)
Yellow crystalline solid, yield 98 %, m.p. 195 °C, Ana-
lytical cal. C15H10N2S: C, 71.97; H, 4.03; N, 11.19; found:
123

M. Parveen et al.
C, 71.97; H, 4.03; N, 11.19. IR (KBr cm−1): 2212 (C≡N),
1550, 1445 (C=Caromatic). H NMR (400 MHz, DMSO-d6,
Yang–Parr correlation function) [62, 63] at the 6-311G
basis set using the GAMESS interface in ChemBio3D ultra
ver. 14.0 (PerkinElmer, MA, USA).
1
δ, ppm): 7.79 (s, 1H, H-2), 8.13 (d, 1H, H-4), 7.94-7.97 (m,
2H, H-5 and H-6), 8.28 (d, 1H, H-7), 10.17 (s, 1H, -NH,
D2O-exchangeable), 8.09 (s, 1H, =CHolifinic), 7.39 (d, 1H,
H-3´), 7.13-7.15 (m, 1H, H-4´), 7.58 (d, 1H, H-5´). 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 127.50 (C-2), 110.16
(C-3), 118.09 (C-4), 119.36 (C-5), 122.92 (C-6), 111.32(C-
7), 128.19 (C-3a), 137.43 (C-7a), 136.84 (C-2´), 126.27 (C-
3´), 129.05 (C-4´), 131.56 (C-5´), 114.49 (C-1´´), 153.90
(C-2´´), 118.09 (CN). MS (EI): (m/z) 250.06 [M+·].
Acknowledgments Shaista Azaz, thanks the Chairman, Department
of Chemistry, AMU, Aligarh, for providing the necessary research
facilities, University Sophisticated Instrumentation Facility (USIF),
AMU, Aligarh and Sophisticated Analytical Instrumentation Facility
(SAIF), Chandigarh, is credited for spectral analysis. UGC is also
gratefully acknowledged for research fellowship to S. Azaz and F.
Ahmad.
4.4.14 (E)-3-(5-Methyl-1H-indol-3-yl)-2-(thiophen-2-yl)
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