β-Cyclodextrine-SO3H: The most efficient catalyst for one-pot synthesis of 2H-indazolo[2,1-b]phthalazine-triones under solvent-free conditions

Article abstract of DOI:10.1007/s11164-015-2113-3

An environmentally benign and efficient method has been developed for the synthesis of a series of 2H-indazolo[2,1-b]phthalazine-triones derivatives with β-cyclodextrine-SO₃H as a recyclable catalyst by simply combining of various aldehydes wit

Full text of DOI:10.1007/s11164-015-2113-3

Res Chem Intermed
DOI 10.1007/s11164-015-2113-3
b-Cyclodextrine-SO3H: the most efficient catalyst
for one-pot synthesis of 2H-indazolo[2,1-b]phthalazine-
triones under solvent-free conditions
Amol B. Atar1,2 Sang Dong Lee1 Byung Gwon Cho1
•
•
•
Dae Won Cho2 Yeon Tae Jeong1
•
Received: 25 March 2015 / Accepted: 21 May 2015
Ó Springer Science+Business Media Dordrecht 2015
Abstract An environmentally benign and efficient method has been developed for the
synthesis of a series of 2H-indazolo[2,1-b]phthalazine-triones derivatives with b-cy-
clodextrine-SO3H as a recyclable catalyst by simply combining of various aldehydes
with cyclic 1,3-diketones and phthalhydrazide under solvent free condition. The ad-
vantageous features of this methodology are high atom-economy, operational simplicity,
shorter reaction time, convergence, and facile automation.
Graphical Abstract A greener, efficient, and expeditious method has been developed
for the synthesis of 2H-indazolo [2,1-b] phthalazine-triones derivatives with b-cy-
clodextrine-SO3H as a recyclable catalyst for the first time.
O
O
R1
O
O
O
β-cyclodextrin-SO3H
O
NH
NH
N
N
+
+
R1
H
R2
R2
R2
O
O
R2
Keywords b-Cyclodextrine-SO3H Á Homogeneous catalyst Á
2H-indazolo[2,1-b]phthalazine-triones Á Solvent free Á MCRs
Electronic supplementary material The online version of this article (doi:10.1007/s11164-015-2113-
3) contains supplementary material, which is available to authorized users.
&
Yeon Tae Jeong
ytjeong@pknu.ac.kr
1
2
Department of Image Science and Engineering, Pukyong National University, Busan 608-737,
Republic of Korea
Department of Chemistry, Yeungnam University, Gyeongsan, Gyeongbuk 712-749,
Republic of Korea
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A. B. Atar et al.
Introduction
Heterocyclic compounds acquired significance, as these are associated with a wide
range of potential biological and pharmaceutical activities [1]. These N-containing
heterocyclic compounds play a crucial role in the context of drug scaffolds,
synthetic organic chemistry, and medicinal chemistry as well as material sciences
[2]. 3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H, 13H)-triones derivatives
constitute a key structural motif in a number of natural and synthetic bioactive
molecules [3]. Heterocycles containing phthalazine moiety constitute as an
important structural motif attributing to their pharmacological and biological
activities [4, 5]. Besides these they are endowed with anticonvulsant [6], cardio
tonic [7] and vasorelaxant activities [8] and also comply as anti-inflammatory,
analgesic, antihypoxic and antipyretic agents [9]. Numerous protocols have been
developed for the synthesis of 3,4-dihydro-1H-indazolo[1,2-b]phthalazine-
1,6,11(2H,13H)-triones using p-TSA [10], ionic liquids [11], (S)-CSA [12],
dodecylphosphonic acid (DPA) [13], heteropoly acids [14], Ce(SO4)2Á4H2O [15],
solid acids [16], montmorillonite K-10 [17], N-halosulfonamides [11], silica-
sulfuric acid [18], phosphomolybdic acid–silica (PMA-SiO2) [19] as catalysts.
However, some of the synthetic strategies suffer from certain limitations such as
expensive catalysts, low yields of products, long reaction times, use of toxic
solvents, tedious procedures for preparation of catalysts and tedious work-up
conditions. Hence, the development of an efficient, simple, easy work-up and
environmentally benign protocol using a recyclable catalyst and a green solvent for
the synthesis of 3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H, 13H)-tri-
ones derivatives is still desirable and in demand.
In recent decades, organic reactions under solvent-free conditions have also
attracted much interest from chemists particularly from the viewpoint of green
chemistry [20]. Green chemistry approaches are significant due to the reduction in
waste production, reduction in byproducts, reduction of energy and cost [21]. The
possibility of performing multicomponent reactions under solvent-free conditions
using an environmentally friendly catalyst could enhance the efficiency from an
economic as well as ecological point of view [22]. b-cyclodextrin-SO3H is well
known supramolecular catalysts, which by reversible formation of host–guest
complexes, activate the organic molecules and catalyze the reactions [23]. Our
literature survey at this stage revealed that there is no single report on the synthesis
of 3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H, 13H)-triones derivatives
in solvent free mediated by b-cyclodextrin-SO3H, as a recyclable supramolecular
O
O
O
O
R1
O
O
O
β-cyclodextrin-SO3H
80 0C, Solvent free
O
NH
NH
N
N
+
+
R1
H
R2
R2
R2
R2
Scheme 1 Synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives by using b-cyclodextrine-
SO3H as a recyclable catalyst
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b-Cyclodextrine-SO3H: the most efficient catalyst for…
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b-Cyclodextrine-SO3H: the most efficient catalyst for…
catalyst. As part of our ongoing program toward the development of greener
chemical approaches for the synthesis of novel reaction intermediates and
heterocyclic moieties [24–28], we report herein the synthesis of 3,4-dihydro-1H-
indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-triones by the reaction of phthalhy-
drazide, 1,3-diketones, and aldehydes using b-cyclodextrin-SO3H, as a recyclable
supramolecular catalyst, in solvent free medium (Scheme 1).
Results and discussion
The studies were initiated to optimize the reaction conditions for a model reaction of
phthalhydrazide, benzaldehyde and dimedone in presence of different catalyst and
solvent (Table 1). In order to establish the real effectiveness of the catalyst for the
synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives, a comparative reac-
tion was performed without catalyst using phthalhydrazide, benzaldehyde and
dimidone in ethanol at reflux. It was found that only 35 % of product was obtained
in the absence of catalyst even after 1 h (Table 1, entry 1). In order to develop a
viable approach, the model reaction was investigated by employing different
catalyst such as CaCl2, SiO2, FeCl3, Zn(OTf)2, ZnCl2, b-cyclodextrin, CuCl2,
b-cyclodextrine-SO3H, Li(OTf), SnCl2Á2H2O and CuF2. Among all screened
catalyst b-cyclodextrine-SO3H gave the best result in view of yield and reaction
time (Table 1, entry 8). In contrast CaCl2, SiO2, Zn(OTf)2, ZnCl2, Li(OTf) and
SnCl2.2H2O did not afford the desired product in good yields (Table 1, entries 2, 3,
5, 6, 10 and 11). The b-cyclodextrine-SO3H is appeared to be more efficient than
CuF2 in terms of yield and time for completion of the reaction (Table 1, entries 8
and 13). Careful analysis of screened Lewis acid catalyst, such as b-cyclodextrin,
OH
O
HN
R
H
H+
O
N
H
O
R1
H
O
OH
β-cyclodextrin-SO3H
R
R2
R2
O
OH
R2
R2
O
R1
O
O
O
O
R1
-H
O
2O
N
N
N
HN
R2
OH
R2
R2
R2
Scheme 2 Plausible mechanism for the formation of substituted 2H-indazolo[2,1-b]phthalazine-trione
derivatives by using b-cyclodextrine-SO3H as a recyclable catalyst
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A. B. Atar et al.
Yielda (%)
Table 3 Recycling and reuse of
b-cyclodextrine-SO3H
Entry
Reaction cycle
1
2
3
4
1st (fresh run)
2nd cycle
3rd cycle
98
97
97
95
4th cycle
a
Isolated yield
CuCl2, FeCl3 and CuF2 were effective, but promising results were obtained with b-
cyclodextrine-SO3H catalyst in less time with better yield (Table 1, entries 4, 8, 9,
13 and 14).
To see the effect of solvent, we screened different solvents such as toluene,
ethanol, acetonitrile, dimethylformamide, ethylene glycol, methanol, water, and
tetrahydrofuran at room temperature. It was observed that under solvent condition
required longer times to afford comparable yields (Table 1, entries 15–21). When the
reaction was performed under solvent free conditions, high yield of target product was
obtained (Table 1, entry 8). Moreover, we found that the yields were obviously
affected by the amount of b-cyclodextrine-SO3H loaded. When 5 mol%, 10 mol%,
and 20 mol% of b-cyclodextrine-SO3H were used, the yields were 91, 98, and 95 %,
respectively (Table 1, entries 8, 22 and 23). Therefore, 10 mol% of b-cyclodextrine-
SO3H was sufficient and optimal quantity for the completion of the reaction.
Thus, we selected the optimized reaction condition to examine the universality of
this catalyst application with different electron rich and deficient substrates. It was
gratifying to observe that most of the tested substrates exhibited satisfactory
reactivity profiles, in all cases leading to a heterocyclization sequence that readily
afforded the target structures (Table 2). Various substituted aldehydes undergo the
reaction in the presence of catalytic amount of b-cyclodextrine-SO3H (10 mol%) in
solvent free condition at 80 °C. As compared to aromatic aldehydes, the
heteroaromatic aldehyde gave slightly lower yield (Table 2, entries 1–18, 26).
Compared with heteroaromatic aldehydes, aliphatic aldehydes afforded relatively
higher yields of the corresponding 2H-indazolo[2,1-b]phthalazine-trione (Table 2,
entries 19–21, 26). In general, all the reactions were clean, and the 2H-indazolo[2,1-b]
phthalazine-trione were obtained in good to excellent yields (85–98 %).
A possible mechanism of this one-pot reaction is expected on the basis of the
reported literature [13]. A plausible mechanism for the formation of substituted 2H-
indazolo[2,1-b]phthalazine-trione derivatives by using b-cyclodextrine-SO3H as a
recyclable catalyst (Scheme 2).
The reusability of the b-cyclodextrine-SO3H catalyst is one of the most important
benefits and makes it useful for commercial applications as well. Thus, the recovery
and reusability of the catalyst were investigated. The recyclability of the catalyst
was checked with model reaction (Table 3, entries 1–4). The catalyst was recovered
after completion of the first fresh run, the reaction mixture cooled to room
temperature and diluted with water. The catalyst was dissolved in water and product
was precipitated out. The precipitated crude product was separated by simple
filtration and b-cyclodextrine-SO3H was recovered by evaporating the aqueous
layer under reduced pressure. The recovered b-cyclodextrine-SO3H (10 mol %)
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b-Cyclodextrine-SO3H: the most efficient catalyst for…
was dried at 90–100 °C for 12 h and tested in up to three more reaction cycles. The
same catalyst (10 mol%) was reused for subsequent reactions (three runs) with fresh
substrates under the same conditions. The catalyst showed excellent recyclability in
all these reactions (Table 3), as the reaction times and yield remained almost the
same with a slight reduction in catalytic activity.
The reported as well as synthesized novel compounds were further characterized
by their spectral properties (1H, 13C NMR, and HRMS).
Conclusion
In summary, an environmentally benign and efficient method has been developed
for the synthesis of a series of 2H-indazolo[2,1-b]phthalazine-triones derivatives in
solvent free media with b-cyclodextrine-SO3H as a recyclable catalyst by simply
combining of various aldehydes with cyclic 1,3-diketones and phthalhydrazide. In
generally, the 2H-indazolo[2,1-b]phthalazine-triones is carried out in solvent-free
conditions without any use of anhydrous condition. To the best of our knowledge
this is the first report for using b-cyclodextrine-SO3H as a green catalyst for
synthesis of entitled compounds. Shorter reaction times, good to excellent yields
and more importantly, the recyclability of catalyst with a slight reduction in
catalytic activity, make this protocol good and attractive.
Experimental
Materials and methods
Chemicals were purchased from Aldrich and Alfa Aesar chemical companies and
used as it is. The NMR spectra were recorded in CDCl3 on a Jeol JNMECP 400
NMR instrument using TMS as an internal standard. The HRMS was recorded on a
Jeol JMS-700 mass spectrometer.
General procedure for the synthesis of b-cyclodextrin-SO3H catalyst
A b-cyclodextrin-SO3H catalyst was prepared by adopting the literature procedure
[29]. To a well stirred mixture of b-cyclodextrin (10.0 g, 4.5 mmol) in CH2Cl2
(50 mL), chlorosulfonic acid (2.00 g, 10 mmol) was added slowly at 0 °C during 3 h.
The resulting mixture was stirred for another 2 h to remove HCl from the reaction
vessel. Then, the mixture was filtered and washed with methanol (50 mL) and dried at
room temperature to obtain sulfonated b-cyclodextrin as a white powder (10.56 g).
General procedure for the synthesis of 2H-indazolo [2,1-b] phthalazine-
triones derivatives (1–25)
A mixture of phthalhydrazide (1.0 mmol), aldehyde (1 mmol), 5,5-dimethyl-
1,3-cyclohexanedione or 1,3-cyclohexanedione (1.0 mmol), b-cyclodextrin-SO3H
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A. B. Atar et al.
(10 mol %) was heated at 80 °C under solvent free condition for an appropriate
time as mentioned in Table 1. After completion of the reaction as monitored by
TLC the reaction mixture was allowed to cool to room temperature and the residue
was diluted with water. The precipitate formed was collected by filtration at pump,
washed with water, and dried. The residue recrystallized from ethanol to afford the
pure product of 2H-indazolo[2,1-b]phthalazine-trione derivatives.
3,3-Dimethyl-13-phenyl-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-
trione (1) Yellow powder, mp: 200–202 °C; 1H NMR (400 MHz, CDCl3) d (ppm)
1.23 (s, 6H, –(CH3)2), 2.35 (s, 2H, –CH2–C=), 3.26 and 3.41 (2H, AB system,
J = 16 Hz, CHaHbCO), 6.47 (s,1H, –CH–N), 7.61 (d, J = 8 Hz, 2H, Ar–H),
7.90–7.85 (m, 2H, Ar–H), 8.37–8.16 (m, 5H, Ar–H); 13C NMR (CDCl3, 100 MHz)
d (ppm) 28.5 (–CH3), 28.7 (–CH3), 34.7 (–C(CH3)2), 38.1 (–CH2–C=), 50.9
(–CH2CO), 64.9 (–CH–N), 118.6 (–HC–C–CO–), 127.1 (Ar–C), 127.7 (Ar–C),
127.9 (Ar–C), 128.7 (Ar–C), 128.9 (Ar–C), 129.1 (Ar–C), 133.6 (Ar–C), 134.5
(Ar–C), 136.4(–N–C–CH2–), 150.9 (Ar–C), 154.3 (–N–CO–), 156.1 (–N–CO–),
192.2 (–CO–); HRMS m/z calcd for C23H20N2O3 [M?] 372.4165, found 372.4167.
3,3-Dimethyl-13-(4-bromophenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,
1
11(2H, 13H)-trione (2) Yellow powder, mp: 261–263 °C; H NMR (400 MHz,
CDCl3) d (ppm) 1.20 (6H, –(CH3)2), 2.32 (s, 2H, CH2–C=), 3.22 and 3.39 (2H, AB
system, J = 16 Hz, CHaHbCO), 6.38 (s, 1H, –CH–N), 7.29 (d, J = 8 Hz, 2H, Ar–
H), 7.44 (d, J = 8 Hz, 2H, Ar–H), 7.85–7.82 (m, 2H, Ar–H), 8.25–8.22 (m, 1H, Ar–
H), 8.34–8.32 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 28.49 (–CH3),
28.78 (–CH3), 34.72 (–C(CH3)2), 38.10 (–CH2–C=), 50.96 (–CH2CO), 64.45 (–CH–
N), 118.04 (–HC–C–CO–), 122.79 (Ar–C), 127.76 (Ar–C), 128.11 (Ar–C), 128.93
(Ar–C), 129.02 (Ar–C), 131.95 (Ar–C), 133.74 (Ar–C), 134.68 (Ar–C), 135.61
(–N–C–CH2–), 151.20 (Ar–C), 154.43 (–N–CO–), 156.03 (–N–CO–), 192.12
(–CO–); HRMS m/z calcd for C23H19BrN2O3 [M?] 450.0579, found 450.0577.
3,3-Dimethyl-13-(4-ethoxyphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,
1
11(2H, 13H)-trione (3) Yellow powder, mp: 220–221 °C; H NMR (400 MHz,
CDCl3) d (ppm) 1.21 (6H, –(CH3)2), 1.35 (t, J = 12 Hz, 3H, –OCH2–CH3), 2.33 (s,
2H, CH2–C=), 3.22 and 3.40 (2H, AB system, J = 16 Hz, CHaHbCO), 3.99–3.96
(m, 2H, –OCH2–CH3), 6.39 (s, 1H, –CH–N), 6.81 (d, J = 8 Hz, 2H, Ar–H), 7.32 (d,
J = 8 Hz, 2H, Ar–H), 7.80 (d, J = 4 Hz, 2H, Ar–H), 8.32–8.23 (m, 2H, Ar–H); 13
C
NMR (CDCl3, 100 MHz) d (ppm) 14.86 (–OCH2–CH3), 28.53 (–CH3), 28.76
(–CH3), 34.65 (–C(CH3)2), 38.09 (–CH2–C =), 51.02 (–CH2CO), 63.39 (–CH–N),
64.61 –OCH2–CH3), 114.64 (Ar–C), 118.61 (–HC–C–CO–), 127.68 (Ar–C), 127.92
(Ar–C), 128.23 (Ar–C), 128.54 (Ar–C), 129.22 (Ar–C), 133.47 (Ar–C), 134.48
(–N–C–CH2–), 150.75 (Ar–C), 154.26 (Ar–C), 156.05 (–N–CO–), 159.18 (–N–CO–),
192.19 (–CO–); HRMS m/z calcd for C25H24N2O4 [M?] 416.1736, found 416.1736.
3,3-Dimethyl-13-(4-fluorophenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,
1
11(2H, 13H)-trione (4) Yellow powder, mp: 218–220 °C; H NMR (400 MHz,
CDCl3) d (ppm) 1.20 (s, 6H, –(CH3)2), 2.33 (s, 2H, CH2–C=), 3.23 and 3.40
(2H, AB system, J = 16 Hz, CHaHbCO), 6.42 (s, 1H, –CH–N), 7.02–6.98 (m, 2H,
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b-Cyclodextrine-SO3H: the most efficient catalyst for…
Ar–H), 7.41–7.38 (m, 2H, Ar–H), 7.85–7.83 (m, 2H, Ar–H), 8.24–8.23 (m, 1H, Ar–
H), 8.34–8.32 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 28.47 (–CH3),
28.72 (–CH3), 34.68 (–C(CH3)2), 38.03 (–CH2–C=), 50.92 (–CH2CO), 64.30 (–CH–
N), 115.62 (Ar–C), 115.84 (Ar–C), 118.19 (–HC–C–CO–), 127.69 (Ar–C), 128.04
(Ar–C), 129.00 (Ar–C), 129.08 (Ar–C), 132.30 (Ar–C), 133.67 (Ar–C), 134.62
(–N–C–CH2–), 151.08 (Ar–C), 154.39 (–N–CO–), 156.01 (–N–CO–), 161.46
(Ar–C), 163.92 (Ar–C), 192.23 (–CO–); HRMS m/z calcd for C23H19FN2O3 [M?]
390.1380, found 390.1380.
3,3-Dimethyl-13-(4-methylphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,
1
11(2H, 13H)-trione (5) Yellow powder, mp: 227–229 °C; H NMR (400 MHz,
CDCl3) d (ppm) 1.20 (s, 6H, –(CH3)2), 2.28 (s, 3H, –CH3), 2.32 (s, 2H, CH2–C=),
3.22 and 3.40 (2H, AB system, J = 16 Hz, CHaHbCO), 6.40 (s, 1H, –CH–N), 7.12
(d, J = 8 Hz, 2H, Ar–H), 7.30 (d, J = 8 Hz, 2H, Ar–H), 7.83–7.78 (m, 2H, Ar–H),
8.25–8.21 (m, 1H, Ar–H), 8.34–8.30 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz)
d (ppm) 21.27 (–CH3), 28.48 (–C(CH3)2), 28.78 (–C(CH3)2), 34.67 (–C(CH3)2),
38.10 (–CH2–C=), 51.00 (–CH2CO), 64.88 (–CH–N), 118.70 (–HC–C–CO–),
127.13 (Ar–C), 127.72 (Ar–C), 127.94 (Ar–C), 129.02 (Ar–C), 129.19 (Ar–C),
129.48 (Ar–C), 133.49 (Ar–C), 134.48 (–N–C–CH2–), 138.48 (Ar–C), 150.79 (Ar–
C), 154.24 (–N–CO–), 156.04 (–N–CO–), 192.16 (–CO–); HRMS m/z calcd for
C22H22N2O3 [M?] 386.1630, found 386.1632.
3,3-Dimethyl-13-(4-isopropylphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-
1,6,11(2H, 13H)-trione (6) Yellow powder, mp: 204–206 °C; 1H NMR
(400 MHz, CDCl3) d (ppm) 1.20–1.17 (m, 12H, –C(CH3)2, CH(CH3)2), 2.34 (s,
2H, CH2–C=), 2.87–2.80 (m, 1H, CH(CH3)2), 3.23 and 3.42 (2H, AB system,
J = 16 Hz, CHaHbCO), 6.43 (s, 1H, –CH–N), 7.17 (d, J = 8 Hz, 2H, Ar–H), 7.32
(d, J = 8 Hz, 2H, Ar–H), 7.84–7.80 (m, 2H, Ar–H), 8.27–8.24 (m, 1H, Ar–H),
8.34–8.31 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 23.86
(–CH(CH3)2), 28.61 (–C(CH3)2), 28.72 (–C(CH3)2), 33.80 (–C(CH3)2), 34.69
(–CH(CH3)2), 38.07 (–CH2–C=), 51.01 (–CH2CO), 64.77 (–CH–N), 118.71 (–HC–
C–CO–), 126.87 (Ar–C), 127.14 (Ar–C), 127.72 (Ar–C), 127.96 (Ar–C), 128.99
(Ar–C), 129.17 (Ar–C), 133.51 (Ar–C), 133.59 (Ar–C), 134.51 (–N–C–CH2–),
149.14 (Ar–C), 150.88 (Ar–C), 154.30 (–N–CO–), 156.08 (–N–CO–), 192.31
(–CO–); HRMS m/z calcd for C26H26N2O3 [M?] 414.1943, found 414.1945.
3,3-Dimethyl-13-(4-nitrophenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,
1
11(2H, 13H)-trione (7) Yellow powder, mp: 223–225 °C; H NMR (400 MHz,
CDCl3) d (ppm) 1.20 (6H, –C(CH3)2), 2.33 (2H, –CH2–C=), 3.26 and 3.41 (2H, AB
system, J = 16 Hz, CHaHbCO), 6.50 (s, 1H, –CH–N), 7.61 (d, J = 8 Hz, 2H,
Ar–H), 7.90–7.85 (m, 2H, Ar–H), 8.17 (d, J = 8 Hz, 2H, Ar–H), 8.24–8.22 (m, 1H,
Ar–H), 8.37–8.35 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 28.38
(–C(CH3)2), 28.70 (–C(CH3)2), 34.74 (–C(CH3)2), 38.03 (–CH2–C=), 50.80
(–CH2CO), 64.16 (–CH–N), 117.26 (–HC–C–CO–), 124.02 (Ar–C), 127.72
(Ar–C), 128.11 (Ar–C), 128.23 (Ar–C), 128.60 (Ar–C), 128.95 (Ar–C), 133.97
(Ar–C), 134.81 (–N–C–CH2–), 143.53 (Ar–C), 147.84 (Ar–C), 151.74 (Ar–C),
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A. B. Atar et al.
154.56 (–N–CO–), 155.93 (–N–CO–), 192.10 (–CO–); HRMS m/z calcd for
C23H19N3O5 [M?] 417.1325, found 417.1327.
3,3-Dimethyl-13-(3,4,5 trimethoxyphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phtha-
lazine-1,6,11(2H, 13H)-trione (8) Yellow powder, mp: 232–234 °C; 1H NMR
(400 MHz, CDCl3) d (ppm) 1.24 (6H, –C(CH3)2), 2.35 (s, 2H, –CH2–C=), 3.20 and
3.45 (2H, AB system, J = 16 Hz, CHaHbCO), 3.80 (d, J = 8 Hz, 9H, –OCH3), 6.38
(s, 1H, –CH–N), 6.63 (s, 2H, Ar–H), 7.86 (d, J = 8 Hz, 2H, Ar–H), 8.35–8.27 (m,
2H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 28.11 (–C(CH3)2), 28.97
(–C(CH3)2), 34.61 (–C(CH3)2), 38.04 (–CH2–C=), 50.92 (–CH2CO), 56.16
(–OCH3), 60.68 (–OCH3), 64.97 (–CH–N), 104.55 (Ar–C), 118.26 (–HC–C–CO–),
127.69 (Ar–C), 127.98 (Ar–C), 128.90 (Ar–C), 129.00 (Ar–C), 131.81 (Ar–C),
133.62 (Ar–C), 134.61 (–N–C–CH2–), 138.20 (Ar–C), 150.89 (Ar–C), 153.32 (Ar–C),
154.50 (–N–CO–), 156.09 (–N–CO–), 192.18 (–CO–); HRMS m/z calcd for
C26H26N2O6 [M?] 462.1791, found 462.1793.
3,3-Dimethyl-13-(4-chlorophenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,
1
11(2H, 13H)-trione (9) Yellow powder, mp: 260–262 °C; H NMR (400 MHz,
CDCl3) d (ppm) 1.20 (6H, –C(CH3)2), 2.32 (s, 2H, –CH2–C=), 3.22 and 3.40 (2H,
AB system, J = 16 Hz, CHaHbCO), 6.40 (s, 1H, –CH–N), 7.29 (d, J = 8 Hz, 2H,
Ar–H), 7.36 (d, J = 8 Hz, 2H, Ar–H), 7.86–7.82 (m, 2H, Ar–H), 8.26–8.22 (m, 1H,
Ar–H), 8.35–8.31 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 28.38
(–C(CH3)2), 28.66 (–C(CH3)2), 34.62 (–C(CH3)2), 37.98 (–CH2–C=), 50.83 (–CH2–
CO–), 64.27 (–CH–N), 117.96 (–HC–C–CO–), 127.64 (Ar–C), 127.99 (Ar–C),
128.52 (Ar–C), 128.91 (Ar–C), 133.63(Ar–C), 134.43 (Ar–C), 134.57 (Ar–C),
134.95 (–N–C–CH2–), 151.09 (Ar–C), 154.31 (–N–CO–), 155.92 (–N–CO–),
192.06 (–CO–); HRMS m/z calcd for C23H19ClN2O3 [M?] 406.1084, found
406.1087.
13-(4-Methylphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-tri-
1
one (10) Yellow powder, mp: 244–246 °C; H NMR (400 MHz, CDCl3) d (ppm)
2.24 (m, 2H, –CH2–CH2–CH2–CO–), 2.42 (t, J = 8 Hz, 2H, –CH2–CH2–CH2–CO–),
2.72 (s, 3H, –CH3), 3.37–3.53 (m, 2H, –CH2–CH2–CH2–CO–), 6.59 (s, 1H, –CH–N),
7.15–7.02 (m, 4H, Ar–H), 7.84–7.83 (m, 2H, Ar–H), 8.21–8.19 (m, 1H, Ar–H),
8.35–8.34 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 19.28 (–CH3),
22.31 (–CH2–CH2–CH2–CO–), 24.43 (–CH2–CH2–CH2–CO–), 36.85 (–CH2–CH2–
CH2–CO–), 61.48 (–CH–N), 120.81 (–HC–C–CO–), 125.27 (Ar–C), 126.42 (Ar–C),
127.53 (Ar–C), 127.97 (Ar–C), 128.37 (Ar–C), 128.96 (Ar–C), 130.62 (Ar–C),
133.47 (Ar–C), 134.47 (Ar–C), 135.08 (–N–C–CH2–), 137.03 (Ar–C), 152.04 (Ar–
C), 153.90 (–N–CO–), 155.98 (–N–CO–), 192.40 (–CO–); HRMS m/z calcd for
C22H18N2O3 [M?] 358.1317, found 358.1319.
13-(4-Chlorophenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-
1
trione (11) Yellow powder, mp: 272–273 °C; H NMR (400 MHz, CDCl3) d
(ppm) 2.26–2.23 (m, 2H, –CH2–CH2–CH2–CO–), 2.49–2.45 (m, 2H, –CH2–CH2–
CH2–CO–), 3.36–3.53 (m, 2H, –CH2–CH2–CH2–CO–), 6.40 (s, 1H, –CH–N–), 7.32
(d, J = 8 Hz, 4H, Ar–H), 7.85 (s, 2H, Ar–H), 8.30 (d, J = 8 Hz, 2H, Ar–H); 13C
123

b-Cyclodextrine-SO3H: the most efficient catalyst for…
NMR (CDCl3, 100 MHz) d (ppm) 22.42 (–CH2–CH2–CH2–CO–), 24.64 (–CH2–
CH2–CH2–CO–), 37.02 (–CH2–CH2–CH2–CO–), 64.49 (–CH–N), 119.29 (–HC–C–
CO–), 127.88 (Ar–C), 128.21 (Ar–C), 128.73 (Ar–C), 129.06 (Ar–C), 133.81 (Ar–
C), 134.65 (Ar–C), 134.77 (Ar–C), 135.04 (–N–C–CH2–), 152.68 (Ar–C), 154.49
(–N–CO–), 156.15 (–N–CO–), 192.59 (–CO–); HRMS m/z calcd for C21H15ClN2O3
[M?] 378.0771, found 378.0773.
13-(4-Ethoxyphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-
1
trione (12) Yellow powder, mp: 219–220 °C; H NMR (400 MHz, CDCl3) d
(ppm) 1.35 (t, J = 12 Hz, 3H, –O–CH2–CH3), 2.24 (m, 2H, –CH2–CH2–CH2–CO–),
2.46 (t, J = 8 Hz, 2H, –CH2–CH2–CH2–CO–), 3.33–3.53 (m, 2H, –CH2–CH2–
CH2–CO–), 3.99–3.96 (m, 2H, –O–CH2–CH3), 6.40 (s, 1H, –CH–N), 6.82 (d,
J = 8 Hz, 2H, Ar–H), 7.32 (d, J = 8 Hz, 2H, Ar–H), 7.82 (d, J = 4 Hz, 2H, Ar–
H), 8.33–8.23 (m, 2H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 14.79 (–O–
CH2–CH3), 22.31 (–CH2–CH2–CH2–CO–), 24.48 (–CH2–CH2–CH2–CO–), 36.94
(–CH2–CH2–CH2–CO–), 63.37 (–O–CH2–CH3), 64.57 (–CH–N), 114.57 (Ar–C),
119.67 (–HC–C–CO–), 127.67 (Ar–C), 127.90 (Ar–C), 128.06 (Ar–C), 128.52 (Ar–
C), 128.92 (Ar–C), 129.15 (Ar–C), 133.44 (Ar–C), 134.47 (–N–C–CH2–), 152.19
(Ar–C), 154.21 (–N–CO–), 156.04 (–N–CO–), 159.14 (Ar–C), 192.63 (–CO–);
HRMS m/z calcd for C23H20N2O4 [M?] 388.1423, found 388.1425.
13-(4-Bromophenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-
1
trione (13) Yellow powder, mp: 280–281 °C; H NMR (400 MHz, CDCl3) d
(ppm) 2.25–2.22 (m, 2H, –CH2–CH2–CH2–CO–), 2.46–2.44 (t, J = 8 Hz, 2H,
–CH2–CH2–CH2–CO–), 3.31–3.54 (m, 2H, –CH2–CH2–CH2–CO–), 6.38 (s, 1H,
–CH–N), 7.30 (d, J = 8 Hz, 2H, Ar–H), 7.44 (d, J = 4 Hz, 2H, Ar–H), 7.84 (s, 2H,
Ar–H), 8.30 (d, J = 8 Hz, 2H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 22.40
(–CH2–CH2–CH2–CO–), 24.62 (–CH2–CH2–CH2–CO–), 36.99 (–CH2–CH2–CH2–
CO–), 64.54 (–CH–N), 119.21 (–HC–C–CO–), 122.87 (Ar–C), 127.86 (Ar–C),
128.19 (Ar–C), 129.02 (Ar–C), 131.98 (Ar–C), 133.80 (Ar–C), 134.76 (Ar–C),
135.55 (–N–C–CH2–), 152.68 (Ar–C), 154.47 (–N–CO–), 156.13 (–N–CO–),
192.56 (–CO–); HRMS m/z calcd for C21H15BrN2O3 [M?] 422.0266, found
422.0268.
13-(3-Methylphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-
1
trione (14) Yellow powder, mp: 222–225 °C; H NMR (400 MHz, CDCl3) d
(ppm) 2.25–2.21 (m, 2H, –CH2–CH2–CH2–CO–), 2.30 (s, 3H, –CH3), 2.46–2.41 (t,
J = 8 Hz, 2H, –CH2–CH2–CH2–CO–), 3.32–3.51 (m, 2H, –CH2–CH2–CH2–CO–),
6.38 (s, 1H, –CH–N), 7.06 (s, 1H, Ar–H), 7.20 (t, J = 12 Hz, 3H, Ar–H), 7.80 (t,
J = 12 Hz, 2H, Ar–H), 8.23 (t, J = 8 Hz, 1H, Ar–H), 8.31 (d, J = 8 Hz, 1H, Ar–
H); 13C NMR (CDCl3, 100 MHz) d (ppm) 21.52 (–CH3), 22.30 (–CH2–CH2–CH2–
CO–), 24.50 (–CH2–CH2–CH2–CO–), 36.95 (–CH2–CH2–CH2–CO–), 65.00 (–CH–
N), 119.82 (–HC–C–CO–), 124.18 (Ar–C), 127.70 (Ar–C), 127.88 (Ar–C), 127.92
(Ar–C), 128.54 (Ar–C), 128.98 (Ar–C), 129.13 (Ar–C), 129.55 (Ar–C), 133.48 (Ar–
C), 134.49 (Ar–C), 136.34 (-N–C-CH2-), 138.26 (Ar–C), 152.18 (Ar–C), 154.18
(–N–CO–), 156.02 (–N–CO–), 192.47 (–CO–); HRMS m/z calcd for C22H18N2O3
[M?] 358.1317, found 358.1319.
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13-(3,4,5-Methoxyphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,
1
13H)-trione (15) Yellow powder, mp: 249–250 °C; H NMR (400 MHz, CDCl3)
d (ppm) 2.27–2.23 (m, 2H, –CH2–CH2–CH2–CO–), 2.53–2.45 (m, 2H, –CH2–CH2–
CH2–CO–), 3.32–3.55 (m, 2H, –CH2–CH2–CH2–CO–) 3.81 (d, J = 12 Hz, 9H,
–OCH3), 6.39 (s, 1H, –CH–N), 6.63 (s, 2H, Ar–H), 7.86 (t, J = 8 Hz, 2H, Ar–H),
8.36–8.28 (m, 2H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 22.32 (–CH2–
CH2–CH2–CO–), 24.52 (–CH2–CH2–CH2–CO–), 36.96 (–CH2–CH2–CH2–CO–),
56.26 (–OCH3), 60.68 (–OCH3), 64.97 (–CH–N), 104.61 (Ar–C), 119.42 (–HC–C–
CO–), 127.73 (Ar–C), 128.03 (Ar–C), 128.93 (Ar–C), 129.03 (Ar–C), 131.79 (Ar–
C), 133.62 (Ar–C), 134.62 (–N–C–CH2–), 152.23 (Ar–C), 153.34 (Ar–C), 154.48
(–N–CO–), 156.11 (-N-CO-), 192.54 (-CO-); HRMS m/z calcd for C24H22N2O6
[M?] 434.1478, found 434.1480.
13-(2-Methoxyphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-
trione (16) Yellow powder, mp: 276–277 °C; 1H NMR (400 MHz, CDCl3) d
(ppm) 2.24–2.20 (m, 2H, –CH2–CH2–CH2–CO–), 2.43–2.39 (m, 2H, –CH2–CH2–
CH2–CO–), 3.37–3.49 (m, 2H, –CH2–CH2–CH2–CO–), 3.72 (s, 3H, –OCH3), 6.59
(s, 1H, –CH–N), 6.97–6.83 (m, 2H, Ar–H), 7.45–7.24 (m, 2H, Ar–H), 7.82 (d,
J = 4 Hz, 2H, Ar–H), 8.50 (d, J = 8 Hz, 2H, Ar–H); 13C NMR (CDCl3, 100 MHz)
d (ppm) 22.54 (–CH2–CH2–CH2–CO–), 24.64 (–CH2–CH2–CH2–CO–), 37.12
(–CH2–CH2–CH2–CO–), 56.01 (–OCH3), 62.83 (–CH–N), 111.67 (Ar–C), 118.89
(–HC–C–CO–), 121.10 (Ar–C), 123.90 (Ar–C), 127.76 (Ar–C), 127.96 (Ar–C),
129.25 (Ar–C), 130.05 (Ar–C), 130.21 (Ar–C), 133.41 (Ar–C), 134.42 (–N–C–
CH2–), 152.72 (Ar–C), 154.11 (–N–CO–), 156.32 (Ar–C), 157.48 (–N–CO–),
192.66 (–CO–); HRMS m/z calcd for C22H18N2O4 [M?] 374.1267, found 374.1269.
13-(2-Methylphenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-tri-
1
one (17) Yellow powder, mp: 267–268 °C; H NMR (400 MHz, CDCl3) d (ppm)
2.26–2.20 (m, 2H, –CH2–CH2–CH2–CO–), 2.44–2.41 (m, 2H, –CH2–CH2–CH2–
CO–), 2.72 (s, 3H, –CH3), 3.36–3.52 (m, 2H, –CH2–CH2–CH2–CO–), 6.60 (s, 1H,
–CH–N), 7.16–7.01 (m, 4H, Ar–H), 7.83–7.81 (m, 2H, Ar–H), 8.23–8.20 (m, 1H,
Ar–H), 8.36–8.33 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 19.30
(–CH3), 22.34 (–CH2–CH2–CH2–CO–), 24.46 (–CH2–CH2–CH2–CO–), 36.88
(–CH2–CH2–CH2–CO–), 61.53 (–CH–N), 120.91 (–HC–C–CO–), 125.24 (Ar–C),
126.41 (Ar–C), 127.61 (Ar–C), 127.97 (Ar–C), 128.42 (Ar–C), 128.98 (Ar–C),
129.07 (Ar–C), 130.70 (Ar–C), 133.44 (Ar–C), 134.47 (Ar–C), 135.02 (–N–C–
CH2–), 137.10 (Ar–C), 151.98 (Ar–C), 153.93 (–N–CO–), 156.04 (–N–CO–),
192.39 (–CO–); HRMS m/z calcd for C22H18N2O3 [M?] 358.1317, found 358.1315.
13-(2-Bromophenyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-
1
trione (18) Yellow powder, mp: 261–262 °C; H NMR (400 MHz, CDCl3) d
(ppm) 2.29–2.22 (m, 2H, –CH2–CH2–CH2–CO–), 2.46–2.42 (m, 2H, –CH2–CH2–
CH2–CO–), 3.40–3.47 (m, 2H, –CH2–CH2–CH2–CO–), 6.68 (s, 1H, –CH–N),
7.16–7.7.12 (m, 1H, Ar–H), 7.30 (t, J = 12 Hz, 1H, Ar–H), 7.43–7.39 (m, 1H, Ar–
H), 7.51 (d, J = 8 Hz, 1H, Ar–H), 7.86–7.83 (m, 2H, Ar–H), 8.24–8.22 (m, 1H, Ar–
H), 8.36–8.34 (m, 1H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm), 22.36 (–CH2–
CH2–CH2–CO–), 24.61 (–CH2–CH2–CH2–CO–), 36.97 (–CH2–CH2–CH2–CO–),
123

b-Cyclodextrine-SO3H: the most efficient catalyst for…
65.95 (–CH–N), 115.12 (–HC–C–CO–), 127.01 (Ar–C), 127.78 (Ar–C), 127.88
(Ar–C), 128.13 (Ar–C), 128.86 (Ar–C), 129.14 (Ar–C), 130.16 (Ar–C), 133.69 (Ar–
C), 133.93 (Ar–C), 134.63 (–N–C–CH2–), 154.34 (Ar–C), 156.28 (–N–CO–),
164.49 (–N–CO–), 192.42 (–CO–); HRMS m/z calcd for C21H15BrN2O3 [M?]
422.0266, found 422.0268.
13-Ethyl-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-trione (19)
1
Yellow powder, mp: 196–198 °C; H NMR (400 MHz, CDCl3) d (ppm) 0.59 (t,
J = 12 Hz, 3H, –CH2–CH3), 1.97–1.92 (m, 1H, –CH2–CH3), 2.15–2.10 (m, 2H,
–CH2–CH2–CH2–CO–), 2.46–2.31 (m, 3H, –CH2–CH3–CH2–CH2–CH2–CO–),
3.15–3.29 (m, 2H, –CH2–CH2–CH2–CO–), 5.52 (s, 1H, –CH–N), 7.78–7.70 (m,
2H, Ar–H), 8.17 (t, J = 12 Hz, 2H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm)
7.10 (–CH2–CH3), 22.05 (–CH2–CH2–CH2–CO–), 22.33 (–CH2–CH3), 24.46
(–CH2–CH2–CH2–CO–), 36.90 (–CH2–CH2–CH2–CO–), 63.40 (–CH–N), 117.63
(–HC–C–CO–), 127.38 (Ar–C), 127.76 (Ar–C), 128.83 (Ar–C), 128.95 (Ar–C),
133.32 (Ar–C), 134.36 (–N–C–CH2–), 153.20 (Ar–C), 154.49 (–N–CO–), 155.90
(–N–CO–), 193.22 (–CO–); HRMS m/z calcd for C17H16N2O3 [M?] 296.1161,
found 296.1163.
13-Propyl-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-trione (20) Yel-
low powder, mp: 172–174 °C; 1H NMR (400 MHz, CDCl3) d (ppm) 0.86 (t,
J = 12 Hz, 3H, –CH2–CH2–CH3), 1.21–1.10 (m, 2H, –CH2–CH2–CH3), 2.07–2.01
(m, 1H, –CH2–CH2–CH3), 2.26–20 (m, 2H, –CH2–CH2–CH2–CO–), 2.59–2.34 (m,
3H, –CH2–CH2–CH3, –CH2–CH2–CH2–CO–), 3.28–3.42 (m, 2H, –CH2–CH2–CH2–
CO–), 5.68 (d, J = 4 Hz, 1H, –CH–N), 7.92–7.83 (m, 2H, Ar–H), 8.36–8.31 (m,
2H, Ar–H); 13C NMR (CDCl3, 100 MHz) d (ppm) 13.74 (–CH2–CH2–CH3), 16.58
(–CH2–CH2–CH3), 22.31 (–CH2–CH2–CH2–CO–), 24.46 (–CH2–CH2–CH2–CO–),
31.52 (–CH2–CH2–CH3), 36.92 (–CH2–CH2–CH2–CO–), 62.79 (–CH–N), 118.33
(–HC–C–CO–), 127.44 (Ar–C), 127.81 (Ar–C), 128.84 (Ar–C), 128.99 (Ar–C),
133.36 (Ar–C), 134.41 (–N–C–CH2–), 152.98 (Ar–C), 154.98 (–N–CO–), 155.97
(–N–CO–), 193.31 (–CO–); HRMS m/z calcd for C18H18N2O3 [M?] 310.1317,
found 310.1319.
13-Isopropyl-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-trione
1
(21) Yellow powder, mp: 141–143 °C; H NMR (400 MHz, CDCl3) d (ppm)
0.97–0.88 (m, 6H, –CH(CH3)2), 2.19 (s, 2H, –CH2–CH2–CH2–CO–), 2.63–2.37 (m,
3H, –CH(CH3)2, –CH2–CH2–CH2–CO–), 3.14–3.48 (m, 2H, –CH2–CH2–CH2–CO–),
5.58 (s, 1H, –CH–N), 7.88–7.81 (m, 2H, Ar–H), 8.32–8.28 (m, 2H, Ar–H); 13C NMR
(CDCl3, 100 MHz) d (ppm) 17.97 (–CH(CH3)2), 18.29 (–CH(CH3)2), 22.15 (–CH2–
CH2–CH2–CO–), 24.60 (–CH2–CH2–CH2–CO–), 31.22 (–CH(CH3)2), 37.11 (–CH2–
CH2–CH2–CO–), 67.00 (–CH–N), 118.10 (–HC–C–CO–), 127.62 (Ar–C), 127.88
(Ar–C), 128.81 (Ar–C), 129.10 (Ar–C), 133.40 (Ar–C), 134.52 (–N–C–CH2–), 153.79
(Ar–C), 155.20 (–N–CO–), 156.11 (–N–CO–), 193.24 (–CO–); HRMS m/z calcd for
C18H18N2O3 [M?] 310.1317, found 310.1319.
Acknowledgments This research work was supported by the BK 21 plus program.
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