Silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a highly efficient, heterogeneous and recyclable silica-supported ionic liquid catalyst for the synthesis of benzo[b]pyran, bis(benzo[b]pyran) and spiro-pyran derivatives

Article abstract of DOI:10.1016/j.molcata.2013.02.022

The reaction of 3-chloropropyl silica (SilprCl) with 1,8-diazabicyclo[5.4. 0]undec-7-ene (DBU) in dry acetone affords silica-bonded 5-n-propyl-octahydro- pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a new silica-supported ionic liquid catalyst. Afterwa

Full text of DOI:10.1016/j.molcata.2013.02.022

Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
Silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride
(SB-DBU)Cl as a highly efficient, heterogeneous and recyclable silica-supported
ionic liquid catalyst for the synthesis of benzo[b]pyran, bis(benzo[b]pyran) and
spiro-pyran derivatives
Alireza Hasaninejada,∗, Nooshin Golzara, Maryam Beyratia,
Abdolkarim Zareb, Mohammad Mahdi Doroodmandc
a Department of Chemistry, Faculty of Sciences, Persian Gulf University, Bushehr 75169, Iran
b Department of Chemistry, Payame Noor University (PNU), Tehran 19395-4697, Iran
c Department of Chemistry, College of Science, Shiraz University, Shiraz 71454, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 January 2013
Received in revised form 24 February 2013
Accepted 25 February 2013
Available online 4 March 2013
The reaction of 3-chloropropyl silica (SilprCl) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dry
acetone affords silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as
a new silica-supported ionic liquid catalyst. Afterward, (SB-DBU)Cl is used for the efficient synthesis
of 4H-benzo[b]pyran derivatives via the one-pot, three-component reaction of carbonyl compounds
(cyclohexane-1,3-dione, 5,5-dimethylcyclohexane-1,3-dione or 3-methyl-1-phenyl-2-pyrazolin-5-one)
with aromatic aldehydes and alkylmalonates. Moreover, some novel bis(benzo[b]pyran)s and a broad
range of structurally diverse spiro-pyrans containing oxindole and/or quinoxaline moiety in their struc-
tures are synthesized using (SB-DBU)Cl. The catalyst is recycled and reused fifteen times with unchanged
yield.
Keywords:
Silica-bonded 5-n-propyl-octahydro-
pyrimido[1,2-a]azepinium chloride
(SB-DBU)Cl
© 2013 Elsevier B.V. All rights reserved.
4H-benzo[b]pyran
Spiro-pyrans
Silica-supported catalyst
Malono derivatives
1. Introduction
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is an amidine base
which has been used as catalyst in different organic transforma-
The important advantages of solid acids and bases such as
operational simplicity, environmental compatibility, non-toxicity,
reusability, low cost, and ease of isolation recommend them as suit-
able catalytic systems in organic synthesis [1]. In fact, simplified
recovery and reusability are critical advantages of heterogeneous
catalytic systems, which could lead to novel environmentally
benign chemical procedures for academia and industry [2]. Metal
colloids, mineral clays and supported reagents on silica gel, alumina
and other solid supports are various types of heterogeneous and
reusable catalytic systems, which have been designed and used in
organic synthesis. Between them, silica-supported catalysts have
attracted more attention because they are inexpensive, easy to
prepare, and insoluble in most of organic solvents, which makes
them being recycled from various reactions.
tions [3–6]. It is especially useful where side reactions are problem
due to the inherent nucleophilicity of basic nitrogen [7–9]. DBU has
some unique properties, and is useful catalyst in organic synthe-
sis; nevertheless, its liquid form at room temperature makes the
work-up procedure very hard [10–14]. Moreover, DBU cannot be
recovered, and eliminated as residue in many reported procedures
[10–14]. Recent efforts in order to overcome this problem were led
to the preparation of ionic liquids based DBU such as [DBU][Ac],
[DBU][Lac] and [DBU][Tfa] [15,16,6]. These types of catalysts are
recoverable; however tedious work-up procedures are needed to
recover the catalyst from the reaction media [15,16,6]. Thus, search
for finding a heterogeneous, recoverable and reusable derivative of
DBU is very desirable.
2-Amino-4H-benzo[b] pyran derivatives are of importance
as they have been used in cosmetics and pigments, and
also as potentially biodegradable agrochemicals [17]. More-
over, poly-functionalized 4H-benzo[b]pyrans constitute structural
units of many natural products [18] and biologically interest-
ing compounds possessing various pharmacological properties
∗
Corresponding author. Fax: +98 771 4222319.
E-mail address: a hasaninejad@yahoo.com (A. Hasaninejad).
1381-1169/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molcata.2013.02.022

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A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
Scheme 1. The preparation of (SB-DBU)Cl.
[19], such as antitum or [20], and antibacterial [21–23] activ-
ities. 4H-benzo[b]pyrans are also potential calcium channel
antagonists, which are structurally similar to biologically active 1,4-
dihydropyridines [24]. Some catalysts such as hexadecyltrimethyl
ammonium bromide (HMTAB) [25], triethylbenzylammonium
chloride (TEBA) [26], rare earth perfluorooctanoate [RE(PFO)3]
[27], and (S)-proline [28] have been used for the synthesis of 4H-
benzo[b]pyrans. However, most of these methods suffer from some
drawbacks such as low yields, long reaction times, and the use of
expensive catalysts, harsh reaction conditions and tedious work-
up. Moreover, in most of them, catalyst is not recyclable.
In continuation of our researches on the design and application
of heterogeneous and reusable solid catalysts in organic synthe-
sis and multi-component reactions [29–33], recently we prepared
SB-DABCO that was used for the synthesis of 4H-benzo[b]pyrans
[33]. However, this paper explained the bonding of DABCO as a
solid base to silica. In some cases, DABCO could be separated from
the reaction mixture without the need to bond to a bed. In con-
tinuation of our work to develop new and eco-friendly synthetic
methodologies and studies on basic catalysts, we found that DBU
has many unique properties, but its liquid form with low boil-
ing point makes the application of this catalyst and also work-up
procedure very hard. However some efforts have been done to
prepare ionic liquids based-DBU but tedious work-up to recover the
catalyst from the reaction media shows that supporting of DBU on a
bed and heterogenization of this catalyst is highly desirable. Herein
we wish to describe the preparation of silica-bonded 5-n-propyl-
octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl from
3-chloropropyl silica (SilprCl) and 1,8-diazabicyclo[5.4.0]undec-
7-ene (DBU) (Scheme 1), and its application as a heterogeneous
and easy recoverable silica-supported ionic liquid catalyst for
the synthesis of benzo[b]pyrans, novel bis(benzo[b]pyran)s,
2ꢀ-aminospiro[indoline-3,4ꢀ-pyran]-2-one and spiro[indeno[1,2-
b]quinoxaline-11,4ꢀ-pyran]-2ꢀ-amine derivatives (Scheme 2).
2. Experimental
2.1. Chemicals and apparatus
All chemicals were purchased from Merck or Fluka Chemical
Companies. The chemicals were used in this study with their
purity included: 1,3-cyclohexanedione (≥98%), 3-methyl-1-
phenyl-2-pyrazolin-5-one (≥98%), 4-hydroxycoumarin (≥98%),
4-nitrobenzaldehyde (≥98%), thiophen-2-carbaldehyde (≥98%),
Scheme 2. The synthesis of 4H-benzo[b]pyran, bis(benzo[b]pyran) and spiro-pyran derivatives using (SB-DBU)Cl.

A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
139
4-(trifluoromethyl)-benzaldehyde (≥98%), 4-Chlorobenzaldehyde
(≥98%), 2-chlorobenzaldehyde (≥98%), 4-hydroxybenzaldehyde
(≥98%), malononitrile (≥98%), ethyl cyanoacetate (≥98%),
methyl cyanoacetate (≥98%), 1,8-diazabicyclo[5.4.0]undec-7-
ene (≥98%), isophthaldialdehyde (≥98%), terephthalddialdehyde
(≥98%), isatin (≥98%), 1,2-diaminobenzene (≥98%), dimedone
(99%), benzaldehyde (≥99%), 4-ethoxybenzaldehyde (≥99%),
4-ethoxybenzaldehyde (≥99%), 3-phenoxybenzaldehyde (≥99%),
4-isopropylbenzaldehyde (≥99%), 5-fluoroisatin (≥99%), ninhydrin
(≥99%), acetone (≥99.5%), ethanol (≥99.5%), acenaphthenquinone
(≥97%), 2-naphthaldehyde (≥97%), phenylglyoxal monohydrate
(≥97%), 4-methylbenzaldehyde (≥97%), 4-cyanobenzaldehyde
(95%), 5-methylisatin (95%), 5-bromoisatin (90%), 3-chloropropyl
silica (230–400 mesh, estent of labeling: 2.5% loading, matrix active
group 8% functionalized). All known compounds were identified
by comparison of their melting points and 1H NMR data with
those reported in the literature. The 1H NMR (500 MHz) and 13C
NMR (125 MHz) were run on a Bruker Avance DPX-250, FT-NMR
spectrometer. Microanalysis was performed on a Perkin-Elmer
240-B microanalyzer. Measurements of surface area and pore size
distribution were made using the Brunauer–Emmet–Teller (BET)
method in a Quanta Sorb machine. Melting points were recorded
on a Stuart Scientific Apparatus SMP3 (UK) in open capillary tubes.
3-Chloropropyl silica (1, SilprCl) was prepared according to the
reported procedure [39].
TG analysis. The desorption temperature and amount of desorbed
CO2 were considered as indexes of base strength and total number
of basic sites, respectively. As the desorption temperature strongly
depends the amount of oxygen as well as the temperature ramp
during the TG analysis, therefore in this experiment, to have more
reproducible data during the thermal analysis of the sample, the
analysis was operated at trace amount of air as oxidant as well as
low temperature ram 2 ◦C min−1. Consequently the temperature
was run up to higher temperature such as 400 ◦C.
It was observed that only one major weight loss occurred over
SiprCl at range of 260–280 ◦C, whereas two major weight losses
occurred over SB-DBU at ranges of 270–290 ◦C and 300–310 ◦C, cor-
respondingly. Although it was difficult to calculate exactly the basic
strength on a definite scale and to count the number of basic sites
quantitatively, TPD could be used to evaluate the relative strength
of basic sites. The diagram of CO2-TPD from SiprCl and (SB-DBU)Cl
indicated that (SB-DBU)Cl was a basic catalyst according to desorp-
tion temperature and intensity of CO2 absorbed on this catalyst (the
CO2-TPD plots of SiPrCl and (SB-DBU)Cl are available in Supporting
Information (Fig. S[4])).
Thermogravimetric (TG) analysis of (SB-DBU)Cl and SiO2 was
also studied. In this study, (SB-DBU)Cl showed almost 10% weight
losses; this weight can be related to the organic moiety (DBU) of
(SB-DBU)Cl (about 0.45 mmol of DBU per 1.0 g of the catalyst). These
results, which were in accordance with the results obtained from
the previous mentioned studies, also confirmed the structure of
(SB-DBU)Cl (the thermogram of (SB-DBU)Cl and SiO2 are available
in Supporting Information Fig. S[5]).
2.2. Preparation of silica-bonded
5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride
(SB-DBU)Cl
2.3. General procedure for the preparation of 4H-benzo[b]pyran
derivatives
A mixture of 3-chloropropyl silica (1.0 g) and DBU (0.76 g,
5.0 mmol) in dry acetone (30 mL) was added to a 50 mL round-
bottomed flask connected to a reflux condenser. The mixture was
stirred under reflux conditions for 36 h. The resulting mixture was
then filtered, washed with dry acetone (30 mL) and dried at room
temperature to give (SB-DBU)Cl as a white powder (1.10 g).
Carbonyl compound (1.0 mmol), malononitrile (1.0 mmol) and
aromatic aldehyde (1.0 mmol) were added in a 25.0 mL round-
bottomed flask contained (SB-DBU)Cl (0.11 g, 5.0 mol%) and EtOH
(5.0 mL). The resulting mixture was stirred at room temperature
(method A) [in order of alkyl cyanoacetates, the reaction was car-
ried out in EtOH/H2O (1:1) under reflux conditions (method B)].
After completion of the reaction, as monitored by TLC, ethanol
(5 mL) was added to the reaction mixture and heated at 60 ◦C
for ∼5 min to dissolve the product followed by centrifugation for
10 min to separate the (SB-DBU)Cl. The EtOH was evaporated under
reduced pressure to give the crude product. The crude product was
dissolved in warm EtOH or aqueous EtOH (6.0 mL) and was allowed
to stand at room temperature for 3–5 h. The crystalline solids were
collected, washed with ethanol and dried. The same procedure was
applied for the preparation of spiro-pyran derivatives and complex
compounds; however, in the case of the preparation of complex
compounds, 2.0 mmol of carbonyl compound, 2.0 mmol of alkyl-
malonate and 1.0 mmol of dialdehyde were used. The recovered
(SB-DBU)Cl was reused for another time without loss of its activity.
Percent yields of the products were calculated as follows:
Initially, silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-
a]azepinium chloride (SB-DBU)Cl was prepared by the
reaction of 3-chloropropyl silica (SilprCl) (1) with 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU) in dry acetone (Scheme 1).
The catalyst structure was characterized by infrared (IR) spec-
troscopy (sp3
C
H stretching at 2920–2980 cm−1, C N stretching
at 1650 cm−1, CH2 bending at 1460 cm−1, Si C stretching at
1220 cm−1 and Si O stretching at 1080–1120 cm−1 as a broad
bond) (the IR spectra of silica-n-propyl chloride and (SB-DBU)Cl
are available in Supporting Information (Figs. S[1] and S[2])).
We also determined the loading level of DBU based on the
chlorine content by titrimetric analysis according to the reported
procedure [34] [primary standard: CNaCl = 0.02 M; titrant (standard
solution): CAgNO = 0.0204 M; indicator: K2CrO4; titrate: SB-DBU
3
(129.2 mg), deionized water (25 mL) and K2CrO4 (0.25 mL)]. For
further confidence on the results obtained from the precipitate
titration, potentiometric titration was also performed. For this pur-
pose, 0.2 g of the sample was added to 5.0 mL of H2O, and titrated
by Ag+ standard solution using a potentiometer (Model: LT, Lutron,
PH-207). Pt disk and Ag/AgCl (3.0 M) electrodes were applied as the
indicator and reference probes, respectively. The results showed
actual yield (g)
theoretical yield (g)
%yield =
× 100
3. Some selected spectral data of the products
that the loading level of DBU was ∼0.45 mmol g−1
.
The adsorptionbehaviorsof nitrogengas on both SilprCland (SB-
DBU)Cl were studied using the thermogravimetric (TG) analysis
instrumentation system in nitrogen atmosphere at 77 K (Fig. S[3],
Supporting Information). According to the BET surface area calcu-
lated from the adsorption data (Fig. S[3], Supporting Information),
3.1. 2-Amino-4-(4-ethoxyphenyl)-7,7-dimethyl-5-oxo-5,6,7,8-
tetrahydro-4H-chromene-3-carbonitrile (6c)
M.p. = 233–235 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.94 (s, 3H),
1.02 (s, 3H), 1.29 (t, J = 6.75 Hz, 3H), 2.09 (d, J = 16.0 Hz, 1H), 2.23 (d,
J = 16.0 Hz, 1H), 2.45–2.53 (m, 2H), 3.96–3.97 (m, 2H), 4.11 (s, 1H),
6.81 (d, J = 8.5 Hz, 2H), 6.93 (s, 2H), 7.03 (d, J = 8.5 Hz, 2H). 13C NMR
(DMSO-d6, 125 MHz): ␦ 15.5, 27.9, 29.2, 32.9, 35.6, 50.8, 59.4, 63.7,
the active surface of the silica support increased to ∼70 m2 g−1
.
In another study, the total basicity of SilprCl and (SB-DBU)Cl was
measured by temperature programmed desorption (TPD) of CO2 by

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A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
113.9, 114.9, 120.6, 129.0, 137.5, 158.0, 159.3, 162.9, 196.5. Anal.
Calcd. for C20H22N2O3: C, 70.99; H, 6.55; N, 8.28. Found: C, 70.93;
H, 6.56; N, 8.25.
for C24H25NO4: C, 73.64; H, 6.44; N, 3.58. Found: C, 73.67; H, 6.49;
N, 3.63.
3.7. Methyl 2-amino-4-(4-cyanophenyl)-7,7-dimethyl-5-oxo-
5,6,7,8-tetrahydro-4H-chromene-3-carboxylate (6k)
3.2. 2-Amino-7,7-dimethyl-4-(naphthalen-2-yl)-5-oxo-5,6,7,8-
tetrahydro-4H-chromene-3-carbonitrile (6e)
M.p. = 180–182 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.86 (s,
3H), 1.02 (s, 3H), 2.06 (d, J = 16.0 Hz, 1H), 2.26 (d, J = 16.0 Hz, 1H),
2.45–2.57 (m, 2H), 3.48 (s, 3H), 4.55 (s, 1H), 7.32 (d, J = 8.0 Hz, 2H),
7.66–7.68 (m, 4H). 13C NMR (DMSO-d6, 125 MHz): ␦ 27.3, 29.4, 32.7,
34.7, 50.7, 51.4, 77.3, 109.5, 115.4, 119.7, 129.5, 132.7, 152.7, 160.1,
163.5, 168.8, 196.6. Anal. Calcd. for C20H20N2O4: C, 68.17; H, 5.72;
N, 7.95. Found: C, 68.23; H, 5.71; N, 7.99.
M.p. = 258–260 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.92 (s, 3H),
1.01 (s, 3H), 1.87–1.92 (m, 1H), 1.94–1.97 (m, 1H), 2.61–2.69 (m,
2H), 4.39 (s, 1H), 7.06 (s, 2H), 7.32–7.34 (d, J = 10 Hz, 1H), 7.44–7.50
(m, 2H), 7.69 (s, 1H), 7.83–7.86 (m, 2H), 7.89 (d, J = 8.0 Hz, 1H). 13
C
NMR (DMSO-d6, 125 MHz): ␦ 20.6, 21.4, 23.3, 27.4, 36.6, 37.2, 58.9,
114.4, 120.6, 126.4, 126.5, 126.5, 126.9, 128.2, 128.5, 128.9, 132.8,
133.7, 143.0, 159.3, 165.4, 196.7. Anal. Calcd. for C22H20N2O2: C,
76.72; H, 5.85; N, 8.13. Found: C, 76.75; H, 5.88; N, 8.12.
3.8. 2-Amino-5-oxo-4-p-tolyl-5,6,7,8-tetrahydro-4H-chromene-
3-carbonitrile (6o)
M.p. = 232–233 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.84–1.88
(m, 1H), 1.92–1.97 (m, 1H), 2.21–2.29 (m, 5H) 2.57–2.61 (m, 2H),
4.15 (s, 1H), 6.95 (s, 2H), 7.04 (d, J = 8.0 Hz, 2H), 7.07 (d, J = 8.0 Hz,
2H). 13C NMR (DMSO-d6, 125 MHz): ␦ 20.6, 21.4, 27.3, 35.9, 37.2,
59.2, 114.8, 120.6, 127.9, 129.7, 136.4, 142.7, 159.3, 165.1, 196.6.
Anal. Calcd. for C17H16N2O2: C, 72.84; H, 5.75; N, 9.99. Found: C,
72.88; H, 5.73; N, 10.04.
3.3. 2-Amino-7,7-dimethyl-5-oxo-4-(3-phenoxyphenyl)-5,6,7,8-
tetrahydro-4H-chromene-3-carbonitrile (6f)
M.p. = 193–194 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.91 (s,
3H), 1.02 (s, 3H), 2.10 (d, J = 16.0 Hz, 1H), 2.26 (d, J = 16.0 Hz, 1H),
2.41–2.53 (m, 2H), 4.17 (s, 1H), 6.75 (s, 1H), 6.80 (d, J = 8.0 Hz, 1H),
6.92 (d, J = 8.0 Hz, 1H), 6.92–7.01 (m, 4H), 7.13 (t, J = 7.2 Hz, 1H),
7.29 (t, J = 7.7 Hz, 1H), 7.37 (t, J = 8.0 Hz, 2H). 13C NMR (DMSO-d6,
125 MHz): ␦ 27.5, 29.3, 32.5, 36.2, 50.8, 58.8, 113.2, 117.4, 118.0,
119.4, 120.4, 123.0, 124.3, 130.8, 130.8, 147.8, 157.2, 157.5, 159.3,
163.5, 196.4. Anal. Calcd. for C24H22N2O3: C, 74.59; H, 5.74; N, 7.25.
Found: C, 74.62; H, 5.78; N, 7.26.
3.9. 2-Amino-4-(naphthalen-2-yl)-5-oxo-5,6,7,8-tetrahydro-4H-
chromene-3-carbonitrile (6p)
M.p. = 254–255 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.87–1.92
(m, 1H), 1.94–1.97 (m, 1H), 2.21–2.26 (m, 1H), 2.27–2.32 (m, 1H),
2.61–2.69 (m, 2H), 4.39 (s, 1H), 7.06 (s, 2H), 7.32–7.34 (d, J = 8.5 Hz,
1H), 7.44–7.50 (m, 2H), 7.69 (s, 1H), 7.83–7.86 (m, 2H), 7.89 (d,
J = 8.0 Hz, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 20.6, 27.4, 36.6,
37.2, 58.9, 114.4, 120.6, 126.4, 126.5, 126.5, 126.9, 128.2, 128.5,
128.9, 132.8, 133.7, 143.0, 159.3, 165.4, 196.7. Anal. Calcd. for
C20H16N2O2: C, 75.93; H, 5.10; N, 8.86. Found: C, 75.97; H, 5.16;
N, 8.83.
3.4. 2-Amino-7,7-dimethyl-5-oxo-4-(thiophen-2-yl)-5,6,7,8-
tetrahydro-4H-chromene-3-carbonitrile (6g)
M.p. = 220–222 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.97 (s, 3H),
1.06 (s, 3H), 2.14 (d, J = 16.0 Hz, 1H), 2.29 (d, J = 16.0 Hz, 1H), 2.42
(d, J = 16.0 Hz, 1H), 2.52 (d, J = 16.0 Hz, 1H), 4.53 (s, 1H), 6.85 (d,
J = 3.5 Hz, 1H), 6.89–6.91 (m, 1H), 7.10 (s, 2H), 7.30–7.31 (m, 1H).
13C NMR (DMSO-d6, 125 MHz): ␦ 27.3, 29.5, 31.2, 32.6, 50.7, 58.9,
113.8, 120.4, 124.8, 125.2, 127.6, 150.1, 159.7, 163.3, 196.3. Anal.
Calcd. for C16H16N2O2S: C, 63.98; H, 5.37; N, 9.33. Found: C, 63.92;
H, 5.41; N, 9.37.
3.10. Methyl 2-amino-4-(4-ethoxyphenyl)-5-oxo-5,6,7,8-
tetrahydro-4H-chromene-3-carboxylate (6s)
M.p. = 149–150 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.27 (m, 3H),
1.79 (m, 1H), 1.92 (m, 1H), 2.23–2.25 (m, 2H), 2.49–2.58 (m, 2H),
3.49 (s, 3H), 3.92 (m, 2H), 4.49 (s, 1H), 6.73 (m, 2H), 7.02 (m, 2H),
7.50 (s, 2H). 13C NMR (DMSO-d6, 125 MHz): ␦ 15.5, 20.7, 27.1, 32.9,
37.2, 51.3, 63.6, 78.7, 114.5, 118.0, 129.2, 139.3, 157.5, 160.1, 164.5,
169.2, 196.8. Anal. Calcd. for C19H21NO5: C, 66.46; H, 6.16; N, 4.08.
Found: C, 66.51; H, 6.23; N, 4.16.
3.5. 2-Amino-4-benzoyl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-
4H-chromene-3-carbonitrile (6h)
M.p. = 220–221 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.05 (s, 3H),
1.07 (s, 3H), 2.12 (d, J = 16.0 Hz, 1H), 2.34 (d, J = 16.0 Hz, 1H), 2.41
(d, J = 17.5 Hz, 1H), 2.61 (d, J = 17.5 Hz, 1H), 4.98 (s, 1H), 7.23 (s, 2H),
7.55 (t, J = 7.75 Hz, 2H), 7.68 (t, J = 7.5 Hz, 1H), 8.05 (d, J = 7.5 Hz, 2H).
13C NMR (DMSO-d6, 125 MHz): ␦ 27.2, 29.5, 33.2, 36.7, 50.4, 53.0,
111.5, 119.9, 129.5, 129.7, 134.4, 136.6, 160.9, 164.8, 196.8, 199.4.
Anal. Calcd. for C19H18N2O3: C, 70.79; H, 5.63; N, 8.69. Found: C,
70.83; H, 5.62; N, 8.72.
3.11. 6-Amino-4-(4-cyanophenyl)-3-methyl-1-phenyl-1,4-
dihydropyrano[2,3-c]pyrazole-5-carbonitrile (6t)
M.p. = 217–219 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.77 (s, 3H),
4.83 (s, 1H), 7.30–7.33 (m, 3H), 7.47–7.50 (m, 4H), 7.78 (d, J = 8.5 Hz,
2H), 7.82 (d, J = 8.0 Hz, 2H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.4,
37.5, 57.9, 98.5, 110.8, 119.6, 120.6, 120.9, 127.1, 129.8, 130.1, 133.5,
138.3, 144.9, 145.9, 150.0, 160.5. Anal. Calcd. for C21H15N5O: C,
71.38; H, 4.28; N, 19.82. Found: C, 71.43; H, 4.22; N, 19.86.
3.6. Ethyl 2-amino-7,7-dimethyl-4-(naphthalen-2-yl)-5-oxo-
5,6,7,8-tetrahydro-4H-chromene-3-carboxylate (6j)
M.p. = 188–190 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.88 (s, 3H),
1.03 (s, 3H), 1.07 (t, J = 7.5 Hz, 3H), 2.03 (d, J = 16.0 Hz, 1H), 2.26
(d, J = 16.0 Hz, 1H), 2.50 (d, J = 14.5 Hz, 1H), 2.57 (d, J = 17.5 Hz, 1H),
3.87–3.98 (m, 2H), 4.67 (s, 1H), 7.30 (d, J = 8.5 Hz, 1H), 7.39–7.45
(m, 2H), 7.59 (s, 2H), 7.63 (s, 1H), 7.75 (d, J = 8.5 Hz, 1H), 7.78–7.83
(m, 2H). 13C NMR (DMSO-d6, 125 MHz): ␦ 15.0, 27.2, 29.5, 32.7,
34.4, 50.8, 59.6, 78.5, 116.1, 126.1, 126.7, 126.9, 127.3, 128.1, 128.1,
128.3, 132.5, 133.5, 144.5, 159.9, 163.1, 168.8, 196.7. Anal. Calcd.
3.12. 6-Amino-3-methyl-1-phenyl-4-(4-(trifluoromethyl)
phenyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (6u)
M.p. = 182–184 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.78 (s, 3H),
4.84 (s, 1H), 7.31–7.34 (m, 3H), 7.48–7.51 (m, 4H), 7.72 (d, J = 7.5 Hz,
2H), 7.78 (d, J = 7.5 Hz, 2H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.4,
37.3, 58.2, 98.7, 120.6, 120.9, 126.4, 127.1, 129.5, 130.2, 138.3, 144.8,

A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
141
146.0, 149.1, 160.5. Anal. Calcd. for C21H15F3N4O: C, 63.63; H, 3.81;
3.19. 4,4ꢀ-(1,4-Phenylene)bis(2-amino-7,7-dimethyl-5-oxo-
N, 14.14. Found: C, 63.68; H, 3.88; N, 14.19.
5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile) (8e)
Mp. = 270 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 0.98 (s, 6H),
1.03 (s, 6H), 2.15–2.24 (m, 4H), 2.46–2.55 (m, 4H), 4.13 (s, 2H), 6.94
(s, 4H), 7.03 (s, 4H). 13C NMR (DMSO-d6, 125 MHz): ␦ 27.8, 28.0,
29.0, 32.7, 35.8, 50.8, 59.2, 113.7, 120.6, 127.8, 143.7, 159.5, 163.4,
196.6. Anal. Calcd. for C30H30N4O4: C, 70.57; H, 5.92; N, 10.97; found
C, 70.58; H, 5.97; N, 11.06.
3.13. 6-Amino-3-methyl-1-phenyl-4-(thiophen-2-yl)-1,4-
dihydropyrano[2,3-c]pyrazole-5-carbonitrile (6v)
M.p. = 168–169 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.92 (s, 3H),
5.08 (s, 1H), 6.97 (m, 1H), 7.07 (d, J = 3.0 Hz, 1H), 7.27 (s, 2H), 7.32
(t, J = 7.5 Hz, 1H), 7.43 (d, J = 5.0 Hz, 1H), 7.49 (t, J = 8.0 Hz, 2H), 7.77
(d, J = 8.0 Hz, 2H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.3, 32.8, 59.4,
99.5, 120.6, 120.8, 125.8, 126.3, 127.1, 127.5, 130.2, 138.2, 144.3,
146.2, 149.6, 160.0. Anal. Calcd. for C18H14N4OS: C, 64.65; H, 4.22;
N, 16.75. Found: C, 64.66; H, 4.21; N, 16.79.
3.20. 4,4ꢀ-(1,4-phenylene)bis(6-amino-3-methyl-1-phenyl-1,4-
dihydropyrano[2,3-c]pyrazole-5-carbonitrile) (8f)
M.p. = 296 ◦C (dec.) 1H NMR (DMSO-d6, 500 MHz): 2.19 (s, 3H),
4.72 (s, 1H), 7.21–7.22 (m, 2H), 7.37–7.47 (m, 3H), 7.60–7.62 (m,
2H), 7.69–7.79 (m, 2H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.4, 37.5,
58.9, 99.5, 120.7, 120.8, 127.0, 127.5, 128.2, 130.2, 138.4, 144.7,
146.2, 160.4. Anal. Calcd. for C34H26N8O2: C, 70.58; H, 4.53; N,
19.37; found C, 70.64; H, 4.48; N, 19.40.
3.14. 6-Amino-4-(4-isopropylphenyl)-3-methyl-1-phenyl-1,4-
dihydropyrano[2,3-c]pyrazole-5-carbonitrile (6x)
M.p. = 156–180 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.19 (d,
J = 8.3 Hz, 6H), 1.79 (s, 3H), 2.86 (m, 1H), 4.63 (s, 1H), 7.16–7.71
(m, 11H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.3, 32.8, 59.4, 99.5,
120.6, 120.8, 125.8, 126.3, 127.1, 127.5, 130.2, 138.2, 144.3, 146.2,
149.6, 160.0. Anal. Calcd. for C23H22N4O: C, 74.57; H, 5.99; N, 15.12.
Found: C, 74.73; H, 5.63; N, 15.19.
3.21. 2-Amino-2ꢀ,5-dioxo-5,6,7,8-tetrahydrospiro[chromene-
4,3ꢀ-indoline]-3-carbonitrile (12a)
3.15. Dimethyl 4,4ꢀ-(1,4-phenylene)bis(2-amino-7,7-dimethyl-5-
oxo-5,6,7,8-tetrahydro-4H-chromene-3-carboxylate) (8a)
M.p. = 297–299 ◦C (Lit.[35] 298–299 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 1.90–1.93 (m, 2H), 217–249 (m, 2H), 2.51–2.66 (m,
2H), 6.77 (d, J = 7.2 Hz, 1H), 6.9 (d, J = 7.0 Hz, 1H), 7.13 (t, J = 7.5 Hz,
1H), 7.18 (s, 2H), 10.37 (s, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦
19.4, 20.6, 27.6, 37.2, 47.7, 58.4, 110.0, 112.7, 118.1, 122.4, 124.0,
128.9, 135.4, 142.8, 159.5, 166.8, 178.9, 195.8. Anal. Calcd. for
M.p. = 226–288 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.81 (s, 6H),
1.00 (s, 6H), 2.05 (d, J = 16.0 Hz, 2H), 2.22 (d, J = 16.5 Hz, 2H), 2.4–2.5
(m, 4H), 3.47 (s, 6H), 4.45 (s, 2H), 6.93 (s, 4H), 7.5 (s, 4H). 13C
NMR (DMSO-d6, 125 MHz): ␦ 27.0, 29.5, 32.7, 33.2, 50.7, 51.3,
78.5, 116.8, 127.6, 144.5, 160.3, 163.0, 169.1, 196.6. Anal. Calcd. for
C17H13N3O3: C, 66.44; H, 4.26; N, 13.67; found C, 66.52; H, 4.33;
N, 13.69.
C32H36N2O8: C, 66.65; H, 6.29; N, 4.86. Found: C, 66.71; H, 6.34; N,
4.89.
3.22. 2-Amino-5ꢀ-bromo-2ꢀ,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carbonitrile (12b)
3.16. 4,4ꢀ-(1,3-Phenylene)bis(2-amino-7,7-dimethyl-5-oxo-
5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile) (8b)
M.p. = 289 ◦C (dec.) (Lit.[35] 290–292 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 1.91–1.96 (m, 2H), 2.23–2.25 (m, 2H), 2.63–2.64 (m,
2H), 6.74 (d, J = 8.0 Hz, 1H), 7.18–7.21 (m, 2H), 7.25 (s, 2H), 10.53 (s,
1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 20.5, 27.6, 37.1, 47.9, 57.7,
111.9, 112.1, 114.2, 118.0, 126.9, 131.7, 137.8, 142.2, 159.5, 167.4,
178.6, 196.0. Anal. Calcd. for C17H12BrN3O3: C, 52.87; H, 3.13; N,
10.88; found C, 52.88; H, 3.16; N, 10.91.
M.p. = 165 ◦C dec. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.94 (s, 6H),
1.05 (s, 6H), 2.04 (d, J = 16.0 Hz, 2H), 2.27 (d, J = 16.0 Hz, 2H), 2.38
(d, J = 17.3, 2H), 2.49–2.60 (m, 4H), 4.10 (s, 2H), 6.79 (s, 1H), 6.90
(s, 4H), 6.99–7.00 (m, 2H), 7.18 (t, J = 7.5, 1H). 13C NMR (DMSO-
d6, 125 MHz): ␦ 27.36, 29.70, 32.52, 36.20, 41.32, 113.66, 120.53,
125.54, 126.64, 128.73, 145.89, 159.41, 163.35, 196.27. Anal. Calcd.
for C30H30N4O4: C, 70.57; H, 5.92; N, 10.97; found C, 70.59; H, 5.88;
N, 11.01.
3.23. 2-Amino-5ꢀ-fluoro-2ꢀ,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carbonitrile (12c)
3.17. 4,4ꢀ-(1,3-Phenylene)bis(6-amino-3-methyl-1-phenyl-1,4-
dihydropyrano[2,3-c]pyrazole-5-carbonitrile) (8c)
M.p. = 283–284 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.92–1.93
(m, 2H), 2.19–2.23 (m, 2H), 2.60–2.68 (m, 2H), 6.74–6.77 (m, 1H),
6.94–6.98 (m, 2H), 7.26 (s, 2H), 10.40 (s, 1H). 13C NMR (DMSO-d6,
125 MHz): ␦ 20.5, 27.6, 37.1, 112.0, 112.2, 115.0, 118.0, 137.1, 139.0,
159.5, 167.2, 179.0, 195.9. Anal. Calcd. for C17H12FN3O3: C, 62.77;
H, 3.72; N, 12.92; found C, 62.80; H, 3.73; N, 12.94.
M.p. = 198 ◦C (dec.) 1H NMR (DMSO-d6, 500 MHz): ␦ 1.78 (s, 6H),
4.7 (s, 2H), 7.14–7.18 (m, 6H), 7.29–7.35 (m, 4H), 7.48 (t, J = 8.0 Hz,
4H), 7.76 (d, J = 7.5 Hz, 4H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.4,
37.5, 58.9, 99.5, 120.7, 120.8, 127.0, 127.4, 128.1, 130.1, 138.4, 144.6,
146.2, 160.3. Anal. Calcd. for C34H26N8O2: C, 70.58; H, 4.53; N,
19.37; found C, 70.65; H, 4.51; N, 19.39.
3.24. 2-Amino-5ꢀ-methyl-2ꢀ,5-dioxo-5,6,7,8-
3.18. 4,4ꢀ-(1,4-Phenylene)bis(2-amino-5-oxo-5,6,7,8-tetrahydro-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carbonitrile (12d)
4H-chromene-3-carbonitrile) (8d)
M.p. = 282–284 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.76–1.78
(m, 2H), 2.18 (s, 3H), 2.21–2.23 (m, 2H), 2.41–2.44 (m, 2H), 6.68 (d,
J = 7.0 Hz, 1H), 6.76 (s, 1H), 6.96 (d, J = 7.75 Hz, 1H), 7.16 (s, 2H), 10.28
(s, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 20.4, 27.8, 37.8, 47.9, 51.0,
76.9, 110.7, 112.9, 114.4, 126.1, 130.7, 139.3, 144.1, 159.8, 165.7,
168.3, 177.4, 195.8. Anal. Calcd. for C18H15N3O3: C, 67.28; H, 4.71;
N, 13.08; found C, 67.33; H, 4.73; N, 13.11.
M.p. = 304 ◦C (dec.) 1H NMR (DMSO-d6, 500 MHz): ␦ 1.94 (m,
4H), 2.28 (m, 4H), 2.60 (m, 4H), 4.14 (s, 2H), 6.95 (s, 4H), 7.05 (s,
4H). 13C NMR (DMSO-d6, 125 MHz): ␦ 20.5, 27.3, 35.7, 37.1, 59.0,
59.1, 114.7, 120.7, 127.9, 143.7, 159.4, 159.5, 165.4, 165.5, 196.8.
Anal. Calcd. for C26H22N4O4: C, 68.71; H, 4.88; N, 12.33; found C,
68.78; H, 4.92; N, 12.39.

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3.25. Methyl 2-amino-5ꢀ-bromo-2ꢀ,5-dioxo-5,6,7,8-
108.9, 113.9, 121.3, 123.0, 128.0, 136.8, 144.9, 159.9, 163.2, 168.5,
180.6, 195.5. Anal. Calcd. for C21H22N2O5: C, 65.96; H, 5.80; N, 7.33;
found C, 65.98; H, 5.84; N, 7.39.
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carboxylate (12e)
M.p. = 274 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 1.86–1.88
(m, 2H), 2.17–2.21 (m, 2H), 2.62–2.64 (m, 2H), 3.27 (s, 3H), 6.62
(d, J = 8.0 Hz, 1H), 7.02 (s, 1H), 7.19 (dd, J = 2.0, 8.0 Hz, 1H), 7.87 (s,
1H), 10.29 (s, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 20.4, 27.8, 37.8,
47.9, 51.0, 76.9, 110.7, 112.9, 114.4, 126.1, 130.7, 139.3, 144.1, 159.8,
165.7, 168.3, 180.4, 195.8. Anal. Calcd. for C18H15BrN2O5: C, 51.57;
H, 3.61; N, 6.68; found C, 51.61; H, 3.61; N, 6.67.
3.31. 2ꢀ-Amino-7ꢀ,7ꢀ-dimethyl-2,5ꢀ-dioxo-5ꢀ,6ꢀ,7ꢀ,8ꢀ-tetrahydro-
2H-spiro[acenaphthylene-1,4ꢀ-chromene]-3ꢀ-carbonitrile (12k)
M.p. = 262–264 ◦C (Lit.[36] 260–262 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 1.02 (s, 3H), 1.03 (s, 3H), 2.04–2.12 (m, 2H), 2.58–2.66
(m, 2H), 7.30 (s, 2H), 7.38 (d, J = 7.0 Hz, 1H), 7.65 (t, J = 7.5 Hz, 1H),
7.82 (t, J = 7.5 Hz, 1H), 7.92–7.94 (m, 2H), 8.26 (d, J = 8.0 Hz, 1H).
13C NMR (DMSO-d6, 125 MHz): ␦ 26.6, 26.8, 33.2, 36.5, 52.8, 53.6,
56.6, 99.3, 117.8, 119.3, 123.6, 126.4, 127.9, 128.3, 129.1, 130.9,
131.8, 134.1, 134.6, 153.5, 158.3, 195.9, 198.3. Anal. Calcd. for
3.26. Ethyl 2-amino-5ꢀ-bromo-2ꢀ,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carboxylate (12f)
M.p. = 274–276 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.82 (t,
J = 7.0 Hz, 3H), 1.86–1.89 (m, 2H), 2.17–2.22 (m, 2H), 2.62–2.64 (m,
2H), 3.69–3.75 (m, 2H), 6.62 (d, J = 8.0 Hz, 1H), 7.03 (s, 1H), 7.20–7.22
(m, 1H), 7.91 (s, 2H), 10.30 (s, 1H). 13C NMR (DMSO-d6, 125 MHz):
␦ 14.0, 20.4, 27.8, 37.8, 47.8, 59.8, 76.6, 110.7, 112.9, 114.4, 126.1,
130.6, 139.4, 144.3, 159.9, 165.6, 168.3, 180.3, 195.8. Anal. Calcd. for
C19H17BrN2O5: C, 52.67; H, 3.95; N, 6.47; found C, 52.68; H, 3.98;
N, 6.49.
C23H18N2O3: C, 74.58; H, 4.90; N, 7.56; found C, 74.63; H, 4.93;
N, 7.62.
3.32. Ethyl 2-amino-5ꢀ-bromo-7,7-dimethyl-2ꢀ,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carboxylate (12l)
M.p. = 274 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 0.82 (t,
J = 7.2 Hz, 3H), 1.04 (s, 3H), 1.05 (s, 3H), 2.05–2.14 (m, 2H), 2.49–2.53
(m, 2H), 3.69–3.75 (m, 2H), 6.63 (d, J = 8.0 Hz, 1H), 7.00 (s, 1H), 7.21
3.27. 2-Amino-7,7-dimethyl-2ꢀ,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carbonitrile (12g)
(d, J = 8.0 Hz, 1H), 7.91 (s, 2H), 10.30 (s, 1H). 13C NMR (DMSO-d6,
125 MHz): ␦ 14.3, 27.1, 27.3, 33.2, 35.6, 40.1, 43.9, 49.3, 50.4, 54.6,
61.3, 111.3, 120.1, 125.9, 127.3, 130.9, 136.5, 138.4, 151.2, 171.5,
174.5, 199.6. Anal. Calcd. for C21H21BrN2O5: C, 54.68; H, 4.59; N,
6.07; found C, 54.69; H, 4.62; N, 6.11.
M.p. = 289–291 ◦C (Lit.[35] 290–292 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 1.00 (s, 3H), 1.03 (s, 3H), 2.07–2.18 (m, 2H), 2.55–2.56
(m, 2H), 6.78 (d, J = 7.5 Hz, 1H), 6.87–6.90 (m, 1H), 6.97 (d, J = 7.0 Hz,
1H), 7.12–7.15 (m, 1H), 7.20 (s, 2H), 10.38 (s, 1H). 13C NMR (DMSO-
d6, 125 MHz): ␦ 19.4, 27.8, 28.4, 32.8, 47.6, 50.8, 58.3, 110.0, 111.6,
118.1, 122.5, 123.8, 129.0, 135.2, 142.9, 159.6, 164.9, 178.8, 195.7.
Anal. Calcd. for C19H17N3O3: C, 68.05; H, 5.11; N, 12.53; found C,
68.11; H, 5.14; N, 12.57.
3.33. 2-Amino-5ꢀ,7,7-trimethyl-2ꢀ,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carbonitrile (12m)
3.28. 2-Amino-5ꢀ-bromo-7,7-dimethyl-2ꢀ,5-dioxo-5,6,7,8-
M.p. = 277–279 ◦C (Lit.[37] 279–280 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 1.01 (s, 3H), 1.03 (s, 3H), 2.09–2.17 (m, 2H), 2.19 (s,
3H), 2.55–2.59 (m, 2H), 6.67 (d, J = 7.5 Hz, 1H), 6.78 (s, 1H), 6.93
(d, J = 7.5 Hz, 1H), 7.18 (s, 2H), 10.27 (s, 1H). 13C NMR (DMSO-d6,
125 MHz): ␦ 19.4, 21.53, 28.0, 28.3, 47.7, 50.9, 58.6, 109.8, 111.7,
118.2, 124.4, 129.3, 131.3, 135.3, 140.4, 159.5, 164.8, 178.8, 195.7.
Anal. Calcd. for C20H19N3O3: C, 68.75; H, 5.48; N, 12.03; found C,
68.77; H, 5.51; N, 12.04.
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carbonitrile (12h)
M.p. = 304–305 ◦C (Lit.[35] >300 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 1.00 (s, 3H), 1.02 (s, 3H), 2.11–2.19 (m, 2H), 2.56–2.61
(m, 2H), 6.75 (d, J = 8.0 Hz, 1H), 7.20 (s, 1H), 7.31–7.32 (m, 3H), 10.54
(s, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 28.0, 28.4, 32.8, 47.9, 50.8,
27.6, 111.0, 112.0, 114.1, 118.0, 126.8, 131.7, 137.6, 142.3, 159.7,
165.4, 178.5, 195.9. Anal. Calcd. for C19H16BrN3O3: C, 55.09; H, 3.89;
N, 10.14; found C, 55.12; H, 3.95; N, 10.19.
3.34. Methyl 2-amino-5ꢀ-bromo-7,7-dimethyl-2ꢀ,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carboxylate (12n)
3.29. 2-Amino-5ꢀ-fluoro-7,7-dimethyl-2ꢀ,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carbonitrile (12i)
M.p. = 263–265 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.96 (s, 3H),
1.00 (s, 3H), 2.05–2.15 (m, 2H), 2.46–2.53 (m, 2H), 3.27 (s, 3H), 6.65
(d, J = 8.0 Hz, 1H), 6.99 (d, J = 2.0 Hz, 1H), 7.20 (dd, J = 2.0, 8.0 Hz, 1H),
7.85 (s, 2H), 10.30 (s, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 27.9,
28.3, 32.4, 47.8, 51.0, 51.4, 76.8, 110.8, 112.9, 130.8, 139.2, 144.1,
159.9, 163.8, 168.3, 180.3, 195.7. Anal. Calcd. for C20H19BrN2O5: C,
53.71; H, 4.28; N, 6.26; found C, 53.75; H, 4.29; N, 6.28.
M.p. = 293 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 0.97 (s, 3H),
0.98 (s, 3H), 2.11–2.18 (m, 2H), 2.54–2.58 (m, 2H), 6.75–6.78 (m,
1H), 6.94–6.98 (m, 2H), 7.27 (s, 2H), 10.40 (s, 1H). 13C NMR (DMSO-
d6, 125 MHz): ␦ 27.3, 27.9, 31.8, 37.9, 51.3, 56.8, 109.1, 111.0, 113.6,
116.3, 116.9, 128.3, 136.3, 154.8, 158.9, 159.4, 171.1, 197.3. Anal.
Calcd. for C19H16FN3O3: C, 64.58; H, 4.56; N, 11.89; found C, 64.59;
H, 4.59; N, 11.95.
3.35. 6ꢀ-Amino-5-fluoro-3ꢀ-methyl-2-oxo-1ꢀ-phenyl-1ꢀH-
3.30. Ethyl 2-amino-7,7-dimethyl-2ꢀ,5-dioxo-5,6,7,8-
spiro[indoline-3,4ꢀ-pyrano[2,3-c]pyrazole]-5ꢀ-carbonitrile (12o)
tetrahydrospiro[chromene-4,3ꢀ-indoline]-3-carboxylate (12j)
M.p. = 214 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 1.05 (s,
3H), 6.94–7.17 (m, 3H), 7.35–7.78 (m, 7H), 10.75 (s, 1H). 13C NMR
(DMSO-d6, 125 MHz): ␦ 12.7, 48.6, 57.3, 111.3, 112.9, 115.8, 116.3,
119.3, 122.4, 125.1, 127.4, 127.8, 135.5, 136.3, 145.9, 154.6, 158.3,
168.9, 177.3. Anal. Calcd. for C21H14FN5O2: C, 65.11; H, 3.64; N,
18.08; found C, 65.14; H, 3.66; N, 18.13.
M.p. = 242–244 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.79 (t,
J = 7.0 Hz, 3H), 0.94 (s, 3H), 1.01 (s, 3H), 2.01 (d, J = 16.0 Hz, 1H),
2.15 (d, J = 16.0 Hz, 1H), 2.54–2.59 (m, 2H), 3.66–3.73 (m, 2H), 6.66
(d, J = 7.5 Hz, 1H), 6.75 (t, J = 7.2 Hz, 1H), 6.79–6.84 (m, 1H), 7.05
(t, J = 7.7 Hz, 1H), 7.84 (s, 2H), 10.12 (s, 1H). 13C NMR (DMSO-d6,
125 MHz): ␦ 13.9, 26.8, 27.5, 28.6, 32.4, 47.4, 51.5, 59.5, 77.2, 101.7,

A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
143
3.36. 6ꢀ-Amino-5-bromo-3ꢀ-methyl-2-oxo-1ꢀ-phenyl-1ꢀH-
7.76 (t, J = 8.5 Hz, 1H), 7.94 (d, J = 8.0 Hz, 1H), 10.70 (s, 1H). 13C NMR
(DMSO-d6, 125 MHz): ␦ 44.9, 56.3, 85.3, 111.1, 113.8, 116.3, 116.9,
117.4, 122.9, 123.4, 125.1, 128.9, 135.6, 136.1, 153.8, 157.6, 158.3,
168.9, 177.3, 181.5. Anal. Calcd. for C20H10FN3O4: C, 64.00; H, 2.69;
N, 11.20; found C, 64.04; H, 2.76; N, 11.28.
spiro[indoline-3,4ꢀ-pyrano[2,3-c]pyrazole]-5ꢀ-carbonitrile (12p)
M.p. = 227–229 ◦C (Lit.[35] 225–226 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 1.57 (s, 3H), 6.85–6.90 (m, 2H), 6.95 (d, J = 7.0 Hz, 1H),
7.16 (t, J = 7.5 Hz, 1H), 7.47 (t, J = 8.0 Hz, 1H), 7.52 (t, J = 8.2 Hz, 2H),
7.80 (d, J = 8.5 Hz, 2H), 8.15 (s, 1H), 10.71 (s, 1H). 13C NMR (DMSO-
d6, 125 MHz): ␦ 12.5, 51.3, 99.1, 109.7, 120.8, 122.6, 124.0, 127.1,
128.6, 130.2, 136.4, 138.2, 142.8, 144.8, 145.0, 162.1, 168.9, 180.0.
Anal. Calcd. for C21H14BrN5O2: C, 56.27; H, 3.15; N, 15.62; found C,
56.31; H, 3.14; N, 15.69.
3.42. 2ꢀ-Amino-2,5ꢀ-dioxo-2H,5ꢀH-spiro[acenaphthylene-1,4ꢀ-
pyrano[2,3-b]chromene]-3ꢀ-carbonitrile (12w)
M.p. = 289 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 7.47 (d,
J = 7.0 Hz, 1H), 7.56 (m, 1H), 7.63–7.76 (m, 5H), 7.88 (m, 1H),
8.00–8.02 (m, 3H), 8.34 (d, J = 7.5 Hz, 1H). 13C NMR (DMSO-d6,
125 MHz): ␦ 58.5, 103.1, 113.4, 117.6, 117.9, 121.9, 123.0, 123.6,
125.9, 126.0, 129.5, 129.9, 130.7, 132.2, 133.0, 134.5, 142.0, 142.6,
152.9, 156.2, 159.3, 159.7, 203.9. Anal. Calcd. for C24H12N2O4: C,
73.47; H, 3.08; N, 7.14; found C, 73.54; H, 3.11; N, 7.18.
3.37. Methyl 6ꢀ-amino-5-bromo-3ꢀ-methyl-2-oxo-1ꢀ-phenyl-1ꢀH-
spiro[indoline-3,4ꢀ-pyrano[2,3-c]pyrazole]-5ꢀ-carboxylate (12r)
M.p. = 225 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 1.61 (s, 3H),
3.41 (s, 3H), 6.83 (d, J = 8.5 Hz, 1H), 7.21 (s, 1H), 7.32–7.35 (m, 2H),
7.51 (t, J = 7.7 Hz, 2H), 8.19 (s, 2H), 10.65 (s, 1H). 13C NMR (DMSO-
d6, 125 MHz): ␦ 12.6, 19.4, 48.6, 51.4, 56.9, 75.1, 98.4, 111.6, 114.3,
120.9, 127.0, 127.2, 130.2, 131.4, 138.2, 138.9, 142.1, 144.8, 144.9,
162.2, 168.6, 179.6. Anal. Calcd. for C22H17BrN4O4: C, 54.90; H, 3.56;
N, 11.64; found C, 54.97; H, 3.58; N, 11.69.
3.43. Ethyl 2ꢀ-amino-2,5ꢀ-dioxo-2H,5ꢀH-spiro[acenaphthylene-
1,4ꢀ-pyrano[2,3-b]chromene]-3ꢀ-carboxylate (12x)
M.p. = 242–243 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.22 (t,
J = 7.0 Hz, 3H), 3.32–3.37 (m, 2H), 7.42 (d, J = 7.5 Hz, 2H), 7.52–7.57
(m, 2H), 7.72–7.79 (m, 2H), 7.67 (d, J = 7.5 Hz, 2H), 8.08 (d, J = 7.5 Hz,
1H), 8.17–8.20 (m, 3H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.1, 52.1,
59.5, 77.3, 105.8, 113.4, 117.3, 120.8, 120.9, 123.6, 123.7, 125.2,
125.7, 128.8, 129.2, 130.1, 131.1, 134.3, 135.8, 142.2, 144.7, 152.7,
154.9, 159.6, 159.7, 167.8, 205.6. Anal. Calcd. for C26H17NO6: C,
71.07; H, 3.90; N, 3.19; found C, 71.15; H, 3.98; N, 3.26.
3.38. Ethyl 6ꢀ-amino-5-bromo-3ꢀ-methyl-2-oxo-1ꢀ-phenyl-1ꢀH-
spiro[indoline-3,4ꢀ-pyrano[2,3-c]pyrazole]-5ꢀ-carboxylate (12s)
M.p. = 233–235 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 0.79 (t,
J = 8.0 Hz, 3H), 1.64 (s, 3H), 3.72–3.82 (m, 2H), 6.82 (d, J = 8.5 Hz,
1H), 7.21 (s, 1H), 7.32–7.36 (m, 2H), 7.51 (t, J = 7.7 Hz, 2H), 7.81
(d, J = 8.0 Hz, 2H), 8.25 (s, 2H), 10.65 (s, 1H). 13C NMR (DMSO-d6,
125 MHz): ␦ 12.6, 14.0, 48.5, 59.9, 74.9, 98.4, 111.6, 114.3, 120.9,
127.0, 127.2, 130.2, 131.3, 138.2, 139.1, 142.3, 144.8, 144.9, 162.3,
168.5, 179.7. Anal. Calcd. for C23H19BrN4O4: C, 55.77; H, 3.87; N,
11.31; found C, 55.78; H, 3.90; N, 11.37.
3.44. 2-Amino-5-oxo-5,6,7,8-tetrahydrospiro[chromene-4,11ꢀ-
indeno[2,1-b]quinoxaline]-3-carbonitrile (12y)
M.p. = 278 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 1.89–1.94
(m, 2H), 2.07–2.14 (m, 2H), 2.73–2.81 (m, 2H), 7.33 (s, 2H),
7.52–7.61 (m, 2H), 7.75–7.84 (m, 2H), 8.06–8.09 (m, 2H), 8.16 (dd,
J = 1.0, 8.0 Hz, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 20.6, 27.8, 37.4,
48.0, 59.5, 113.8, 118.4, 122.2, 125.5, 129.66, 129.69, 129.7, 129.9,
130.5, 136.9, 141.7, 142.4, 152.9, 155.0, 159.6, 166.5, 167.5, 195.9.
Anal. Calcd. for C24H16N4O2: C, 73.46; H, 4.11; N, 14.28; found C,
73.54; H, 4.18; N, 14.36.
3.39. 6ꢀ-Amino-3ꢀ-methyl-2-oxo-1ꢀ-phenyl-1ꢀH,2H-
spiro[acenaphthylene-1,4ꢀ-pyrano[2,3-c]pyrazole]-5ꢀ-
carbonitrile (12t)
M.p. = 195–196 ◦C. 1H NMR (DMSO-d6, 500 MHz): ␦ 1.06 (s, 3H),
7.35–7.37 (m, 1H), 7.51–7.54 (m, 2H), 7.59–7.64 (m, 3H), 7.78–7.82
(m, 3H), 7.92–7.95 (m, 1H), 8.08–8.11 (m, 2H), 8.42 (d, J = 8.0 Hz,
1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 12.9, 53.6, 58.6, 116.5, 118.9,
121.1, 122.5, 124.6, 125.3, 125.6, 126.8, 128.9, 129.7, 129.9, 130.8,
131.4, 132.7, 136.2, 141.9, 152.5, 177.3, 197.8. Anal. Calcd. for
3.45. 2-Amino-7,7-dimethyl-5-oxo-5,6,7,8-
tetrahydrospiro[chromene-4,11ꢀ-indeno[2,1-b]quinoxaline]-3-
carbonitrile (12z)
C
25H16N4O2: C, 74.25; H, 3.99; N, 13.85; found C, 74.28; H, 4.02;
M.p. = 280 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 1.00 (s, 3H),
1.03 (s, 3H), 1.97–2.08 (m, 2H), 2.61–2.75 (m, 2H), 7.33 (s, 2H),
7.51–7.55 (m, 2H), 7.59–7.60 (m, 1H), 7.75–7.78 (m, 1H), 7.81–7.84
(m, 1H), 8.05 (dd, J = 1.5, 8.2 Hz, 1H), 8.08 (d, J = 7.5 Hz, 1H), 8.15 (dd,
J = 1.0, 8.0 Hz, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 27.5, 27.9, 31.9,
37.8, 43.8, 51.2, 56.3, 107.9, 117.9, 121.3, 125.8, 127.6, 127.7, 127.8,
127.9, 128.8, 129.3, 136.1, 136.9, 139.9, 141.6, 154.3, 158.6, 159.3,
198.9. Anal. Calcd. for C26H20N4O2: C, 74.27; H, 4.79; N, 13.33; found
C, 74.31; H, 4.82; N, 13.36.
N, 13.88.
3.40. 2ꢀ-Amino-5-bromo-2,5ꢀ-dioxo-5ꢀH-spiro[indoline-3,4ꢀ-
pyrano[2,3-b]chromene]-3ꢀ-carbonitrile (12u)
M.p. = 310 ◦C (dec.) (Lit.[35] >300 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 6.82 (d, J = 8.0 Hz, 1H), 7.39 (dd, J = 2.0, 8.5 Hz, 1H), 7.49
(d, J = 8.5 Hz, 1H), 7.54 (t, J = 7.5 Hz, 2H), 7.72–7.78 (m, 3H), 7.93 (dd,
J = 1.0, 8.0 Hz, 1H), 10.80 (s, 1H). 13C NMR (DMSO-d6, 125 MHz):
␦ 48.7, 57.3, 101.6, 112.2, 113.5, 114.6, 117.5, 117.7, 123.6, 125.8,
128.1, 132.5, 134.5, 136.2, 142.4, 152.9, 156.3, 159.3, 159.4, 177.7.
Anal. Calcd. for C20H10BrN3O4: C, 55.07; H, 2.31; N, 9.63; found C,
55.11; H, 2.33; N, 9.67.
3.46. Methyl 2-amino-7,7-dimethyl-5-oxo-5,6,7,8-
tetrahydrospiro[chromene-4,11ꢀ-indeno[2,1-b]quinoxaline]-3-
carboxylate (12aa)
M.p. = 269 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 0.94 (s, 3H),
0.99 (s, 3H), 1.84–2.01 (m, 2H), 2.55–2.74 (m, 2H), 2.82 (s, 3H),
7.38–7.48 (m, 3H), 7.64–7.74 (m, 2H), 7.88 (s, 2H), 7.92–7.93 (m,
1H), 8.02 (d, J = 7.0 Hz, 1H), 8.09–8.11 (m, 1H). 13C NMR (DMSO-d6,
125 MHz): ␦ 13.7, 19.4, 27.5, 28.7, 32.6, 47.9, 50.7, 51.2, 56.9, 59.2,
78.0, 114.8, 121.6, 124.6, 128.6, 129.0, 129.45, 129.49, 132.2, 138.6,
141.4, 141.7, 153.8, 157.3, 160.1, 164.2, 167.8, 169.4, 195.7. Anal.
3.41. 2ꢀ-Amino-5-fluoro-2,5ꢀ-dioxo-5ꢀH-spiro[indoline-3,4ꢀ-
pyrano[2,3-b]chromene]-3ꢀ-carbonitrile (12v)
M.p. = 304 ◦C (dec.) (Lit.[35] >300 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 6.84–6.86 (m, 1H), 7.02–7.06 (m, 1H), 7.25 (dd, J = 2.5,
8.2 Hz, 1H), 7.49 (d, J = 8.5 Hz, 1H), 7.54 (t, J = 7.7 Hz, 1H), 7.71 (s, 2H),

144
A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
Calcd. for C27H23N3O4: C, 71.51; H, 5.11; N, 9.27; found C, 71.54; H,
5.19; N, 9.36.
O
O
CHO
CN
SB-DBU
CN
CN
(5)
3.47. Ethyl 2-amino-7,7-dimethyl-5-oxo-5,6,7,8-
tetrahydrospiro[chromene-4,11ꢀ-indeno[2,1-b]quinoxaline]-3-
carboxylate (12ab)
+
O
+
O
NH2
(6a)
(3a)
(4b)
M.p. = 272 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 0.99 (s, 3H),
1.04 (s, 3H), 1.08 (t, J = 7.0 Hz, 3H), 1.85–2.01 (m, 2H), 2.56–2.74 (m,
2H), 3.32–3.45 (m, 2H), 7.39 (d, J = 7.5 Hz, 1H), 7.44 (t, J = 7.2 Hz,
1H), 7.49 (t, J = 7.2, 1H), 7.65–7.68 (m, 1H), 7.71–7.74 (m, 1H),
7.93 (d, J = 8.0 Hz, 1H), 7.98 (s, 2H), 8.02 (d, J = 7.0 Hz, 1H), 8.10 (d,
J = 8.5 Hz, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.7, 19.4, 27.5,
28.7, 32.5, 47.8, 51.3, 56.8, 9.2, 77.8, 114.9, 121.5, 124.7, 128.6,
129.0, 129.4, 132.2, 138.8, 141.3, 141.8, 169.4, 195.7. Anal. Calcd.
for C28H25N3O4: C, 71.93; H, 5.39; N, 8.99; found C, 71.99; H, 5.42;
N, 9.05.
Scheme 3. The reaction of benzaldehyde (3a) with 5,5-dimethylcyclohexane-1,3-
dione (4b) and malononitrile (5) using (SB-DBU)Cl.
4. Results and discussions
To assess the efficacy and the scope of our new catalyst, initially,
the synthesis of 4H-benzo[b]pyran derivatives via the condensa-
tion reaction of C H activated ketones with aromatic aldehydes
and alkylmalonates were studied. To optimize the reaction con-
ditions, the condensation of benzaldehyde (3a) (1.0 mmol) with
5,5-dimethylcyclohexane-1,3-dione (4b) (1 mmol) and malonon-
itrile (5) (1.0 mmol) was selected as a model reaction (Scheme 3).
To compare the effect of catalyst loadings, reaction times, and
solvents on the reaction, various parametric investigations were
examined. The model reaction was examined in the presence of
different molar ratios of (SB-DBU)Cl in various solvents at room
temperature. The results are summarized in Table 1. As Table 1
indicates, higher yield and shorter reaction time were obtained
when the reaction was carried out in the presence of 5 mol% of
the catalyst in ethanol; in these conditions, the corresponding 4H-
benzo[b]pyran 6a was produced in 94% yield within 35 min (Table 1,
entry 8). In this case, average turnover frequency (TOF) value of the
catalyst was also higher. Increasing the amount of catalyst to 7 mol%
showed no substantial improvement in the yield, whereas the yield
was decreased by decreasing the amount of catalyst to 2.5 mol%.
Moreover, it was observed that the reaction did not proceed effi-
ciently in the absence of (SB-DBU)Cl after a long time (6 h) (Table 1,
entry 10).
3.48. 6ꢀ-Amino-3ꢀ-methyl-1ꢀ-phenyl-1ꢀH-spiro[indeno[2,1-
b]quinoxaline-11,4ꢀ-pyrano[2,3-c]pyrazole]-5ꢀ-
carbonitrile (12ac)
M.p. = 240 ◦C (dec.) (Lit.[38] 236 ◦C). 1H NMR (DMSO-d6,
500 MHz): ␦ 1.10 (s, 3H), 7.37 (t, J = 7.5 Hz, 1H), 7.54 (t, J = 7.7 Hz,
2H), 7.64–7.71 (m, 5H), 7.81–7.90 (m, 4H), 8.12 (d, J = 8.5 Hz, 1H),
8.20 (t, J = 8.5 Hz, 2H). 13C NMR (DMSO-d6, 125 MHz): ␦ 13.8, 43.6,
58.4, 116.9, 118.9, 121.8, 122.7, 125.8, 125.9, 128.8, 128.91, 128.97,
129.0, 129.6, 129.8, 129.9, 135.9, 136.7, 136.9, 139.8, 142.3, 146.1,
154.2, 159.1, 175.9. Anal. Calcd. for C28
H18N6O: C, 74.00; H, 3.99;
N, 18.49; found C, 74.10; H, 4.09; N, 18.56.
3.49. 2ꢀ-Amino-5ꢀ-oxo-5ꢀH-spiro[indeno[2,1-b]quinoxaline-
11,4ꢀ-pyrano[2,3-b]chromene]-3ꢀ-carbonitrile (12ad)
M.p. = 297 ◦C (dec.). 1H NMR (DMSO-d6, 500 MHz): ␦ 7.44 (d,
J = 8.0 Hz, 1H), 7.57–7.63 (m, 3H), 7.74–7.81 (m, 5H), 7.84–7.86 (m,
1H), 8.05–8.08 (m, 2H), 8.15–8.20 (m, 1H), 8.19–8.21 (dd, J = 1.0,
8.5 Hz, 1H). 13C NMR (DMSO-d6, 125 MHz): ␦ 113.5, 117.5, 118.0,
122.5, 123.7, 125.9, 126.3, 129.81, 129.88, 130.3, 130.4, 131.0, 133.4,
134.5, 137.3, 141.8, 142.8, 151.5, 153.0, 154.8, 156.5, 159.1, 159.4,
165.4. Anal. Calcd. for C27H14N4O3: C, 73.30; H, 3.19; N, 12.66; found
C, 73.36; H, 3.25; N, 12.69.
The product yields were also measured at different times
(Table 1, entries 5–7). As it can be seen in Table 1, the yields of
the product in the initial times (5, 10 and 15 min) were low. In
these times, the most amounts of the starting materials (benzalde-
hyde, 5,5-dimethylcyclohexane-1,3-dione and malononitrile) were
consumed; however, the product yields were low. This can be
Table 1
The reaction of benzaldehyde (1.0 mmol) with malononitrile (1.0 mmol) and 5,5-dimethylcyclohexane-1,3-dione (1.0 mmol) using (SB-DBU)Cl in different solvents (5 mL) at
room temperature.
Entry
Solvent
Catalyst (mol%)
Time (min)
Yielda (%)
TONb/TOFc (min−1
)
1
2
3
4
5
6
7
8
9
10
12
13
14
15
16
17
18
19
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
CHCl3
CHCl3
CH3CN
CH3CN
EtOAc
EtOAc
H2O
1.5
1.5
2.5
2.5
5
5
5
5
7
-
5
5
5
5
5
5
5
35
360
35
180
5
10
15
35
30
360
35
360
35
200
35
360
35
Trace
40
25
82
10
23
40
94
94
Trace
18
71
25
87
10
48
40
83
–
26.67/0.07
10/0.29
32.8/0.18
2/0.4
4.6/0.46
8/0.53
18.8/0.54
13.43/0.45
3.6/0.1
14.2/0.04
5/0.14
17.4/0.09
2/0.06
9.6/0.03
8/0.23
H2O
5
120
16.6/0.14
a
Isolated yield.
b
c
Average turn over number (mol of product/mol of catalyst).
Average turn over frequency [mol of product/(mol of catalyst × reaction time)].

A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
145
Table 2
The synthesis of 4H-benzo[b]pyran derivatives from the reaction of C H activated carbonyl compound (1.0 mmol), aryl aldehyde (1.0 mmol) and malono derivative (1.0 mmol)
in the presence of (SB-DBU)Cl (0.05 mmol) in ethanol (5.0 mL) at room temperature.
Entry
Sub.
R
X
Time (min)
Yielda (%)
TONb/TOFc (min−1
)
6a
6b
6c
6d
6e
6f
6g
6h
6id
6jd
6kd
6ld
6m
6n
6o
6p
6q
6rd
6sd
6t
4b
4b
4b
4b
4b
4b
4b
4b
4b
4b
4b
4b
4a
4a
4a
4a
4a
4a
4a
4c
4c
4c
4c
4c
C6H5
4-ClC6H4
CN
CN
CN
CN
CN
CN
CN
CN
CO2Et
CO2Et
CO2Me
CO2Me
CN
CN
CN
CN
CN
35
20
90
15
60
35
35
25
240
280
210
180
45
20
75
50
30
94
93
92
95
97
92
90
95
92
94
91
96
92
92
90
94
96
93
95
92
94
92
94
93
18.8/0.54
18.6/0.93
18.4/0.20
19/1.27
19.4/0.32
18.4/0.53
18/0.51
4-OEtC6H4
4-NO2C6H4
2-Naphthyl
3-PhOC6H4
2-Thienyl
C6H5-CO
4-CF3C6H4
2-Naphthyl
4-CNC6H4
4-ClC6H4
19/0.76
18.4/0.08
18.8/0.07
18.2/0.09
19.2/0.11
18.4/0.41
18.4/0.92
18.0/0.24
18.8/0.37
19.2/0.64
18.6/0.10
19/0.05
18.4/0.53
18.8/0.63
18.4/0.53
18.8/0.27
18.6/0.31
4-ClC6H4
4-NO2C6H4
4-CH3C6H4
2-Naphthyl
2-ClC6H4
4-ClC6H4
CO2Et
CO2Me
CN
CN
CN
180
360
35
30
35
4-EtOC6H4
4-CNC6H4
4-CF3C6H4
2-Thienyl
4-HOC6H4
4-iso-Propyl C6H4
6u
6v
6w
6x
CN
CN
70
60
a
Isolated yield.
b
c
Average turn over number (mol of product/mol of catalyst).
Average turn over frequency [mol of product/(mol of catalyst × reaction time)].
d
This reaction was carried out in H2O/EtOH (1/1) under reflux conditions.
attributed to the formation of intermediates during the reaction;
according to the results, the time required for the conversion of the
starting materials to intermediates, and then to the product was
35 min.
The model reaction was also examined in the presence of (SB-
DBU)Cl at room temperature in several solvents including CHCl3,
CH3CN, EtOAc and H2O (Table 1 entries 12–19). In aprotic sol-
vents (CHCl3, CH3CN and EtOAc) the yield of product were low,
whereas change of solvent from aprotic to protic (EtOH and H2O)
in the same conditions resulted in increasing in the yield of prod-
uct that this observations can be because of polarity of intermediate
and solvation of activated complex. However, as it can be seen in
Table 1, ethanol was the best solvent for Knovenagel condensation,
Michael addition and finally cyclization reaction of intermediate to
form the related product. The condensation of benzaldehyde (3a)
with 5,5-dimethylcyclohexane-1,3-dione (4b) and malononitrile
(5) was also tested using SiO2 separately in which the product was
obtained in 70% yield within 240 min. Furthermore, the reaction
was examined using DBU as catalyst (5.0 mol%) which afforded the
product in 78% after 60 min, and DBU could not be recovered. The
efficiency of 3-aminopropyl-modified silica gel as a commercially
available silica-supported catalyst on the reaction of benzalde-
hyde with 5,5-dimethylcyclohexane-1,3-dione and malononitrile
was also investigated. This catalyst gave the product in 75% within
120 min; this low yield of the product may be related to the reaction
of amino group of the catalyst with benzaldehyde. These studies
Scheme 4. The synthesis of complex compounds via the condensation of 2.0 equiv. of carbonyl compounds with 2.0 equiv. of alkylmalonates and 1.0 equiv. of dialdehydes.

146
A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
Table 3
The synthesis of bis-pyranes from the reaction of C H activated carbonyl compounds (2.0 mmol), alkylmalonates (2.0 mmol) and dialdehydes (1.0 mmol) using (SB-DBU)Cl
(0.1 mmol) in ethanol (10 mL) at room temperature.
Entry
Subs./X
Product
Time (min)
Yielda (%)
TONb/TOFc (min−1
)
H2N
O
MeO2C
O
O
8ad
4b/CO2Me
210
92
18.4/0.09
CO2Me
NH2
O
O
H2N
O
O
NC
NC
8b
4b/CN
260
90
18/0.07
H2N
O
Ph
N
N
O
H2N
NC
NC
8c
4c/CN
380
95
19/0.05
H2N
O
N
N
Ph
H2N
NC
O
O
8d
4a/CN
130
91
18.2/0.14
O
CN
O
NH2
H2N
O
NC
O
O
8e
4b/CN
140
95
19/0.14
CN
O
NH2

A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
147
Table 3 (Continued)
Entry
Subs./X
Product
H2N
Time (min)
Yielda (%)
TONb/TOFc (min−1
)
Ph
O
N
N
NC
8f
4c/CN
250
93
18.6/0.07
CN
NH2
N
N
Ph
O
a
Isolated yield.
b
Average turn over number (mol of product/mol of catalyst).
c
Average turn over frequency [mol of product/(mol of catalyst × reaction time)].
d
Method B was applied for the synthesis of this compound.
confirmed the high efficiency of (SB-DBU)Cl, and its critical role in
the reaction.
reaction rate (Table 2, compounds 6d, 6h, 6i, 6k, 6n, 6t and
6u), whereas electron-releasing substituents decreased the reac-
tion rate (Table 2, compounds 6c, 6o, 6s, 6w and 6x). Moreover,
the nature of the substituents did not affect on the reaction
yields. Aromatic aldehydes bearing sensitive substituents were
also successfully applied in the reaction without producing by-
products (Table 2, compounds 6k and 6t). Furthermore, SB-DBU
efficiently catalyzed the reaction when hetero-aromatic aldehydes
were applied (Table 2, compounds 6 g and 6 v). In these studies,
we found that reflux condition [in H2O/EtOH (1:1)] was required
for the condensation of alkylcyanoacetates with aromatic aldehyde
and carbonyl compounds. This can attributed to lower reactivity of
alkyl cyanoacetates in comparison with malononitrile.
After optimization of the reaction conditions,
a broad
range of structurally diverse aldehydes (3) were condensed
with carbonyl compounds [cyclohexane-1,3-dione (4a), 5,5-
dimethylcyclohexane-1,3-dione (4b) or 3-methyl-1-phenyl-2-
pyrazolin-5-one (4c)] and alkylmaloates (5) in the presence of
(SB-DBU)Cl to furnish the corresponding products in high yields
and in short reaction times (Table 2). For each reaction, turn over
number (TON) and turn over frequency TOF values of (SB-DBU)Cl
were also calculated (Table 2).
As it is shown in Table 2, the presence of electron-withdrawing
substituents on the aromatic ring of aldehydes accelerated the
Scheme 5. The synthesis of spiro-pyrans in the presence of (SB-DBU)Cl.

148
A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
Table 4
The synthesis of spiro-pyran derivatives from the reaction of C H activated carbonyl compound (1 mmol), malono derivative (1 mmol) and isatin derivative (1 mmol) in the
presence of SB-DBU (0.05 mmol) in ethanol (5 mL) at room temperature.
Entry
Subs./X
Carbonyl compound
Time (min)
Yielda (%)
TONb/TOFc (min−1
)
M.p. ◦C (Lit.)
12a
12b
12c
12d
12ed
12fd
12g
12h
12i
4a/CN
4a/CN
4a/CN
4a/CN
4a/CO2Me
4a/CO2Et
4b/CN
4b/CN
4b/CN
4b/CO2Et
4b/CN
4b/CO2Et
4b/CN
4b/CO2Me
4c/CN
4c/CN
4c/CO2Me
4c/CO2Me
4c/CO2Et
4c/CN
4d/CN
4d/CN
9a
9b
9c
9d
9b
9b
9a
9b
9c
9a
10
9b
9d
9b
9c
9b
9a
9b
9b
10
9b
9c
10
10
11
11
11
11
11
11
120
180
300
210
540
540
150
150
210
420
60
420
180
360
150
180
420
540
540
90
270
270
270
360
240
240
300
390
390
480
95
96
96
95
96
97
97
98
98
97
98
97
96
98
96
95
96
97
97
97
97
98
98
97
97
98
96
98
95
98
19/0.16
297–299 (298–299) [35]
289 (dec.) (290–292) [35]
283–284
282–284
274 (dec.)
19.2/0.11
19.2/0.06
19/0.09
19.2/0.04
19.4/0.04
19.4/0.13
19.6/0.13
19.6/0.09
19.4/0.05
19.6/0.33
19.4/0.05
19.2/0.11
19.6/0.05
19.2/0.13
19/0.11
19.2/0.05
19.4/0.04
19.4/0.04
19.4/0.22
19.4/0.07
19.6/0.07
19.6/0.07
19.4/0.05
19.4/0.08
19.6/0.08
19.2/0.06
19.6/0.05
19/0.05
274–276
289–291 (290–292) [35]
304–305 (>300) [35]
293 (dec.)
242–244
262–264 (260–262) [36]
274 (dec.)
277–280 (278–280) [37]
263–265
242 (dec.)
227–229 (225–226) [35]
227–228
225 (dec.)
233–235
195–196
310 (dec.) (>300) [35]
304 (dec.)
289 (dec.)
242–243
278 (dec.)
280 (dec.)
269 (dec.)
12jd
12k
12ld
12m
12nd
12o
12p
12qd
12rd
12sd
12t
12u
12v
12w
12xd
12y
4d/CN
4d/CO2Et
4a/CN
12z
4b/CN
12aad
12abd
12ac
12ad
4b/CO2Me
4b/CO2Et
4c/CN
272 (dec.)
240 (dec.) (236) [38]
297 (dec.)
4d/CN
19.6/0.04
a
Isolated yield.
b
c
Average turn over number (mol of product/mol of catalyst).
Average turn over frequency [mol of product/(mol of catalyst × reaction time)].
d
Method B was applied for the synthesis of this compound.
(SB-DBU)Cl also efficiently catalyzed the synthesis of novel com-
with carbonyl compounds (4a–4d) and alkylmalonates (5) in
the presence of (SB-DBU)Cl in EtOH at room temperature or in
EtOH/H2O (1:1) under reflux conditions (Scheme 5). The results
are displayed in Table 4. As Table 4 indicates, the procedure
worked well when a wide range of substrates were utilized.
Four types of substituted isatins and acenaphthenequinone, as
well as 11H-indeno[1,2-b]quinoxalin-11-one were condensed suc-
cessfully with C H activated ketones (1,3-cyclohexanediones,
4-hydroxycumarin or 3-methyl-1-phenyl-2-pyrazolin-5-one) and
alkylmalonates to afford a broad range of structurally diverse spiro-
pyran compounds in excellent yields and in short reaction times.
plex compounds 8a–8f via the reaction of 2.0 equiv. of carbonyl
compounds with 2.0 equiv. of alkylmalonates and 1.0 equiv. of
dialdehyde (7) (Scheme 4). The respective results are shown in
Table 3.
After the successful application of (SB-DBU)Cl for the synthesis
of 4H-benzo[b]pyran and bisbenzo[b]pyran derivatives, we decided
to apply this catalyst for the synthesis of spiro-pyran compounds
containing oxindole or quinoxaline moiety in their structures.
For this purpose, isatin derivatives (9a–9d), acenaphthenquinone
(10) or 11H-indeno[1,2-b]quinoxalin-11-one (11) [40] were treated
Fig. 1. The reaction of benzaldehyde (1.0 mmol) with malononitrile (1.0 mmol) and 5,5-dimethylcyclohexane-1,3-dione (1.0 mmol) in ethanol (5.0 mL) in the presence of
recovered (SB-DBU)Cl at room temperature.

A. Hasaninejad et al. / Journal of Molecular Catalysis A: Chemical 372 (2013) 137–150
149
of product/mol of catalyst) and TOF [mol of product/(mol of cata-
lyst × reaction time)] amounts of the reused (SB-DBU)Cl were 18.55
and 0.53 (min−1), respectively.
A proposed mechanism for the synthesis of benzo[b]pyrans is
outlined in Scheme 6. Based on this mechanism, (SB-DBU)Cl is an
effective catalyst for the formation of olefin 13 which readily pre-
pares in situ by Knoevenagel condensation of aryl aldehyde 3 with
the active methylene of compound 5. Afterward, carbonyl com-
pound 4 converts to its corresponding enolate form, 14, in the
presence of (SB-DBU)Cl, which easily reacts with olefin 13 to pro-
duce intermediate 15. Intermediate 15 converts to product 6, after
proton transfer and tautomerization.
5. Conclusions
In summary, we have introduced
a novel heterogeneous
silica-supported ionic liquid catalyst, silica-bonded 5-n-propyl-
octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl, from
commercially available and relatively inexpensive starting mate-
rials by a simple method. Conversion of a liquid base with low
boiling point (DBU) to a heterogeneous catalyst has an improve-
ment in our studies and more advantages than a solid base to
become heterogeneous. (SB-DBU)Cl efficiently catalyzed the con-
densation reactions between C H activated carbonyl compounds,
aromatic aldehydes and alkylmalonates to give 4H-benzo[b]pyran
derivatives in excellent yields. This catalyst was recovered and
reused for fourteen reaction cycles with unchanged yield. More-
over, our presented method was highlighted with its efficiency for
the synthesis of novel complex compounds, bis(benzo[b]pyran)s,
via the reaction of dialdehydes (1 equiv.) with carbonyl compounds
(2 equiv.) and alkylmalonates (2 equiv.). Beside these, a broad range
of structurally diverse spiro-pyran derivatives containing oxindole
or quinoxaline moiety in their structures were prepared in excel-
lent yields and in short reaction times using (SB-DBU)Cl. Other
advantages of our catalyst are its generality and its easy recov-
ery and reusability. In this study we found that, (SB-DBU)Cl works
efficiently with 5.0 mol% in comparison with 10 mol% SB-DABCO.
For the (SB-DBU)Cl catalyst more than 30 products containing
bis(benzo[b]pyran)s and spiro-benzo[b]pyrans with oxindole or
quinoxaline moiety in their structures were prepared, that have
not prepared with SB-DABCO.
Acknowledgements
The authors thank the Research Committee of Persian Gulf Uni-
versity and Payame Noor University (PNU) for the financial support
of this work.
Scheme 6. The proposed mechanism for the synthesis of 4H-benzo[b]pyrans using
(SB-DBU)Cl.
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/j.molcata.
2013.02.022.
In another study, reusability of the catalyst was studied.
For this purpose, the reaction of benzaldehyde (1.0 mmol) with
5,5-dimethylcyclohexane-1,3-dione (1.0 mmol) and malononitrile
(1.0 mmol) was performed in the presence (SB-DBU)Cl (0.11 g,
5.0 mol%) in EtOH (5 mL) at room temperature. After completion
of the reaction, as monitored by TLC, ethanol (5 mL) was added to
the reaction mixture and heated at 60 ◦C for ∼5 min to dissolve the
product followed by centrifugation for 10 min to separate the (SB-
DBU)Cl and minimize the handling loss of catalyst. After isolation
of the product, hot ethanol was added to the recovered (SB-DBU)Cl
followed by centrifugation, (SB-DBU)Cl was then dried and success-
fully used for the next run under identical reaction conditions.
The reusability results are summarized in Fig. 1. As Fig. 1 indi-
cates, (SB-DBU)Cl was successfully recycled and reused for fourteen
cycles with unchanged yield. For the reaction, the average TON (mol
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