Silica-supported tungstic acid (STA): A recyclable catalyst for the synthesis of 1H-indazolo [1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives under solvent-free condition

Article abstract of DOI:10.1080/10426507.2019.1661414

An efficient one-pot synthesis of 1 H-indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives via three-component condensation reaction of phthalhydrazide or 4-phenylurazole, aldehydes or isatins and dimedone in the presen

Full text of DOI:10.1080/10426507.2019.1661414

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: https://www.tandfonline.com/loi/gpss20
Silica-supported tungstic acid (STA): A
recyclable catalyst for the synthesis of 1H-
indazolo [1,2-b]phthalazine-trione and spiro-
triazolo[1,2-a]indazole-tetraone derivatives under
solvent-free condition
Amol Maruti Jadhav, Sandip Gangadhar Balwe & Yeon Tae Jeong
To cite this article: Amol Maruti Jadhav, Sandip Gangadhar Balwe & Yeon Tae Jeong
(2019): Silica-supported tungstic acid (STA): A recyclable catalyst for the synthesis of 1H-
indazolo [1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives under
solvent-free condition, Phosphorus, Sulfur, and Silicon and the Related Elements, DOI:
10.1080/10426507.2019.1661414
To link to this article: https://doi.org/10.1080/10426507.2019.1661414
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PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
https://doi.org/10.1080/10426507.2019.1661414
Silica-supported tungstic acid (STA): A recyclable catalyst for the synthesis of
1H-indazolo [1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone
derivatives under solvent-free condition
Amol Maruti Jadhav, Sandip Gangadhar Balwe, and Yeon Tae Jeong
Department of Image Science and Engineering, Pukyong National University, Busan, Republic of Korea
ABSTRACT
ARTICLE HISTORY
Received 2 July 2019
Accepted 26 August 2019
An efficient one-pot synthesis of 1 H-indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]inda-
zole-tetraone derivatives via three-component condensation reaction of phthalhydrazide or 4-phe-
nylurazole, aldehydes or isatins and dimedone in the presence of a catalytic amount of silica-
supported tungstic acid (STA), as a heterogeneous solid acid catalyst under solvent-free conditions
is presented. This ecofriendly protocol offers several advantages such as a cost-effective procedure
with excellent yields, short reaction time, simple workup, recovery and reusability of catalyst with
broad scope of usable substrates. This has made the protocol sustainable and economic.
KEYWORDS
Multicomponent reaction;
heterogeneous catalyst;
1H-indazolo[1,2-b]phthala-
zine-trione and one-pot
synthesis
GRAPHICAL ABSTRACT
Introduction
analgesic and anti-inflammatory,[17] and anti-HIV activ-
ities.[18] Nitrogen-containing heterocycles are widely found in
nature, fine chemicals, biologically and pharmaceutically active
compounds.[19] Amongst them, 4-phenylurazole derivatives
are utilized as anti-cancer and hypolipidemic agents.[20] These
compounds are also used for the preparation of herbicides,[21]
pesticides,[22] and polymeric materials with unique properties
such as heat-resistant coatings,[23] and high grip ability for
rubber tires and melamine resins. Similarly, some biologically
active 4-phenylurazole and spiro-triazolo[1,2-a]indazole-tet-
raone derivatives[24] (Figure 1).
Therefore, a literature a view showed that, only a few
methods have been developed for the synthesis of this skel-
eton.[25] However, it should be pointed out that, reported
methods using complex metals catalysts and supported metal
nanoparticles suffered with drawbacks such as difficulties in
the catalyst preparation and separation from reaction mix-
tures, high cost, toxicity etc. Thus, there is a need to develop
The development of highly efficient chemical reaction
sequences is a major challenge in modern drug discovery.
Multicomponent reactions (MCRs), defined as one pot reac-
tions in which at least three starting materials react to form
a product, have been steadily gaining importance in syn-
thetic organic chemistry.[1–3] MCRs have their inherent
advantages such as short reaction times, high atom economy
and simple purification processes. MCR protocols can be
used for fragment based drug design[4,5] and diversity-ori-
ented synthesis of heterocyclic compounds because of their
simplicity, efficiency, and high selectivity.[6]
Spiro-heterocycle synthesis presents an interesting chal-
lenge to organic chemists due to its structural rigidity and
complexity.[7,8] Notably, nitrogen containing spiro-hetero-
cycles exhibit remarkable biological properties[9] and many
synthetic analogs containing a spiro-centre also exhibit anti-
parasitic,[10] AChE inhibitor,[11] anti-mycobacterial,[12] anti-
bacterial,[13] antitubercular,[14] antimicrobial,[15] anticancer,[16] a simple and cost-effective method for the synthesis of
CONTACT Yeon Tae Jeong
ytjeong@pknu.ac.kr
Department of Image Science and Engineering, Pukyong National University, Busan, 608-737, Republic
of Korea.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/gpss.
Supplemental data for this article is available online at https://doi.org/10.1080/10426507.2019.1661414.
ß 2019 Taylor & Francis Group, LLC

2
A. M. JADHAV ET AL.
O
H
N
N
O
O
N
O
O
O
N
CH3
H2N
N
O
N
N
H
O
CH3
OH
N
O
N
H
O
N
H
MeO
(b)
(a)
(c)
Figure 1. Biologically active molecules containing 4-phenylurazole and spiro-triazolo[1,2-a]indazole-tetraone derivatives.
1H-indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2- of these experiments are summarized in Table 1 (entries 3-
a]indazole-tetraone derivatives. Recently, heterogeneous 8). Among all the screened catalysts, STA was found super-
solid catalysts have gained much interest because of their ior with respect to reaction time and product yield (Table 1,
cost-effectiveness by reusability and ecological benefits.[26,27]
entry 8). Then, we investigated the influence of various
In particularly silica-supported acid catalysts have estab-
lished numerous applications in modern organic synthesis as
they may be easily recovered and reused.[26] In this connec-
tion, silica-supported tungstic acid (STA) has attracted tre-
mendous attention as a green and solid acid catalyst to
construct carbon–carbon and carbon–heteroatom bonds in
various organic trans-formations.[27] It has received signifi-
cant notice due to its low cost, non-toxicity, air and water
compatibility, ease of handling, greater selectivity, recyclabil-
ity, enhanced reaction rates, experimental simplicity and
ease of preparation.[27]
Our literature investigation revealed that there are no
reports on the synthesis of 1H-indazolo[1,2-b]phthalazine-
trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives
catalyzed by silica-supported tungstic acid (STA) under solv-
ent-free conditions. As part of our interest in developing
more efficient and environmentally benign methodolo-
gies,[28] we described a method for the synthesis of 1 H-
indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-
a]indazole-tetraone by one-pot, multi-compound condensa-
tion of phthalhydrazide or 4-phenylurazole, aldehydes or isa-
tins and dimedone in the presence of catalytic amount
silica-supported tungstic acid (STA) as a catalyst under solv-
ent-free at 80 ꢀC (Scheme 1).
organic solvents such as EtOH, CHCl3, Toluene, CH3CN,
THF, and DMF in the presence of 10 mol % of STA at vari-
ous temperatures (Table 1, entries 8-13). In our observation
at most of the solvent, conditions found that the rate of
reaction was lower and desired product was obtained in
moderate yield. Next, we studied the scope of this reaction
using solvent-free reaction conditions. Interestingly, the
yields of the reaction under solvent-free conditions were
higher and the reaction times were shorter than under solv-
ent conditions (Table 1, entry 14).
The advantage of solvent-free conditions can be explained
by the fact that a uniform distribution of the mixture of
reactants was in closer proximity, allowing more effective
reactions and almost complete conversion of the reactants.
To our delight, under solvent-free reaction conditions we
observed excellent yields (94%) in shorter reaction time
(Table 1, entry 14). Furthermore, we investigated the catalyst
loading for this one-pot reaction using our model reaction.
When 5 mol % of catalyst was used, the product 4a was
obtained only in 73% yield (Table 1, entry 16). Notably, no
improvement in the product yield was observed by increas-
ing the catalyst loading up to 20 mol% (Table 1, entry 15).
Moreover, increase in the reaction temperature, no improve-
ment in the yield was observed (Table 1, entry 17).
Therefore, 10 mol% of STA was sufficient and optimal quan-
tity for the completion of the reaction.
Result and discussion
The scope of this three-component reaction under the
optimized reaction conditions were studied using phthalhy-
drazide and 4-phenylurazole, various aldehydes or isatins
and dimedone and results are summarized in (Table 2).
Initially, we investigated the scope of phthalhydrazide with
various aldehydes and dimedone. We found that, various
aromatic aldehydes take part in this one-pot cascade and
provided the corresponding products with good to excellent
yields (Table 2, entries 4a–4q). A variety of functional
groups substituted at the aromatic ring of the aldehyde sub-
strate, including electron-withdrawing such as, chloro,
For our initial investigation the reaction of phthalhydrazide
(1a, 1 mmol), 4-chlorobenzaldehyde (2a, 1 mmol) and dime-
done (3a, 1 mmol) was carried out in ethanol at 80 ꢀC in the
absence of any catalyst for 18 h. In this case, the desired
product was not observed, as the starting materials were
unreactive (Table 1, entry 1). Next, the same set of reactants
was tested using 10 mol% of nickel(II) chloride (NiCl2) at
80 ꢀC, and all the reactants were consumed within 10 h and
afforded desired product 4a in 44% yield (Table 1, entry 2).
1
The structure of 4a was confirmed by H NMR, 13C NMR,
and HRMS data. Encouraged by this result, we attempted to bromo, fluoro and nitro (Table 2, entries 4a, 4b, 4d, 4f, 4i,
optimize the yield of the reaction by screening the same set 4k, 4n, and 4q) and electron-donating such as, methoxy,
of reaction with various acid catalysts such as, InBr3, AcOH, methyl and isopropyl (Table 2, entries 4c, 4e, 4g, 4h, 4l, 4m,
TFA, p-TSA, InCl3 and STA, were examined, and the results 4o, and 4p) groups, were well tolerated. Interestingly, we

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
3
O
O
O
R
O
R
H
N
N
2a
O
O
O
O
(4a-4q)
STA (10 mol %)
NH
NH
Solvent-free, 80 °C
30-50 min
O
O
O
R
O
3a
N
1a or 1b
N
N
H
2b
R
O
O
(4r-4w)
Scheme 1. Synthesis of 1H-indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives catalyzed by STA under solvent-free condition.
Table 1. Optimization of reaction conditions for the synthesis of 1H-indazolo[1,2-b]phthalazine-trione (4a).a
Cl
O
O
O
CHO
O
O
Temperature
Catalyst,
O
NH
NH
N
N
Solvent or
Solvent-free
O
Cl
1a
3a
2a
4a
Entry
Catalyst (mol %)
Solvent
Temp (ꢀC)
Time
Yield (%)b
1
2
3
4
5
6
7
8
–
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
CHCl3
Toluene
CH3CN
THF
80
80
80
80
80
80
80
80
reflux
reflux
reflux
reflux
100
80
80
80
100
18
10
10
8
8
6
6
4
6
6
–
NiCl2 (10%)
InBr3 (10%)
AcOH (10%)
TFA (10 %)
p-TSA (10 %)
InCl3 (10%)
STA (10%)
STA (10%)
STA (10%)
STA (10%)
STA (10%)
STA (10%)
STA (10%)
STA (20%)
STA (5%)
44
52
58
54
72
68
85
52
56
62
46
40
94
93
73
94
9
10
11
12
13
14
15
16
17
6
8
8
DMF
Solvent-free
Solvent-free
Solvent-free
Solvent-free
30 min
30 min
50 min
30 min
STA (10%)
aReaction of phthalhydrazide (1a, 1 mmol), 4-chlorobenzaldehyde (2a, 1mmol) and dimedone (3a, 1 mmol) catalyzed by (10 mol%) STA under solvent-free conditions.
bIsolated yield.
found that 4-phenylurazole or phthalhydrazide amines with
The reusability of catalysts is an important factor for com-
dimedone and various substituted isatin derivatives such as, mercial uses. We investigated the reusability of the catalyst in
chloro, fluoro and methyl afforded the desired products in the synthesis of 1H-indazolo[1,2-b]phthalazine-trione and
good to excellent yields (Table 2, entries 4r-4w). In general, spiro-triazolo[1,2-a]indazole-tetraone derivatives. The catalyst
the reactions were clean and no side products were detected. was easily recovered after each run from the reaction medium,
In all cases, the reactions proceeded efficiently at 80 ꢀC under washed with dichloromethane, dried under vacuum at 100 ꢀC
solvent free conditions using 10 mol % of the STA catalyst, and tested for its activity in subsequent runs. It was found that
and the pure products can be obtained just by recrystallization the catalyst could be reused four times without loss of activity
of the crude products from ethanol by avoiding tedious work- (Table S1, entry 1–4, Supplemental Materials).
up and column-chromatographic separation. Therefore, the
A plausible reaction mechanism for the synthesis of 1H-
present protocol has general applicability and accommodates a indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]inda-
variety of substitution patterns. All the structure of synthesized zole-tetraone derivatives (4a-4w) should be postulated as
1
compounds (4a–4w) have been ascertained on the basis of H shown in (Scheme 2).[25a] The first step is the Knoevenagel
NMR, 13C NMR and HRMS data.
condensation between aldehyde 2 and dimedone 3 in the

4
A. M. JADHAV ET AL.
Table 2. Substrate scope.a,b
O
O
O
O
R
STA (10 mol %)
O
O
O
O
NH
NH
N
N
R
H
Solvent-free, 80 °C
30-50 min
1a or 1b
2a
4a-4w
3a
Br
Cl
OMe
O
F
O
O
O
O
O
O
O
O
N
N
O
O
N
N
N
N
N
N
O
(4a), 94%, 30 min
(4c), 91%, 42 min
(4d), 90%, 38 min
(4b), 92%, 34 min
Me
H3C
Br
CH3
O
O
O
Me
O
O
O
O
N
N
N
N
O
O
O
N
N
N
N
O
O
(4f), 93%, 30 min
(4g), 90%, 36 min
(4e), 89%, 48 min
(4h), 91%, 33 min
OMe
Cl
MeO
O
OMe
O
O
Br
O
O
O
O
N
N
N
N
N
N
O
N
N
O
O
O
O
(4j), 94%, 30 min
(4i), 94%, 34 min
(4k), 92%, 34 min
(4l), 91%, 39 min
OMe
F
OMe
O
O
O
OMe
O
O
O
O
O
N
N
N
N
N
N
OMe
O
N
N
O
O
O
(4o), 88%, 38 min
(4m), 88%, 46 min
(4n), 89%, 44 min
(4p), 87%, 36 min
(continued)

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
5
Table 2. Continued.
O
O
O
R
STA (10 mol %)
O
O
O
O
N
NH
NH
R
H
N
Solvent-free, 80 °C
30-50 min
O
1a or 1b
2a
4a-4w
3a
NO2
O
O
O
O
O
O
O
N
N
N
N
N
N
O
Ph N
Ph N
Ph N
Cl
F
N
N
O
O
O
O
O
O
N
N
N
H
H
H
O
(4r), 92%, 32 min
(4t), 91%, 38 min
(4s), 94%, 30 min
(4q), 89%, 50 min
O
O
O
O
O
O
N
N
N
N
N
N
Ph N
Me
Me
O O
N
O
O O
N
O
N
H
H
H
(4v), 94%, 32 min
(4w), 92%, 36 min
(4u), 90%, 40 min
aReactions were performed with phthalhydrazide or 4-phenylurazole (1 mmol), aldehydes or isatin (1 mmol) and dimedone (1 mmol), in the presence of 10 mol %
STA under solvent-free conditions at 80 ꢀC.
bIsolated yields.
presence of STA afforded intermediate 5, which acts as General procedure for the synthesis of 13-(4-chlorophenyl)-
Michael acceptor. The adduct 5 immediately undergoes 3,3-dimethyl-2,3,4,13-tetrahydro-1H-indazolo[1,2-
b]phthalazine-1,6,11-trione (4a)
Michael type addition with phthalhydrazide 1 to afford the
intermediate 6. The intermediate 6 underwent intramolecular
cyclization and provided the intermediate 7, which upon elim-
ination of water, afforded the desired product 4.
A mixture of phthalhydrazide (1, 1 mmol), 4-chlorobenzal-
dehydes (2, 1 mmol), dimedone (3, 1 mmol) and silica-sup-
ported tungstic acid (STA 10 mol%) was stirred at 80 ꢀC
under solvent-free conditions. The progress of the reaction
was monitored by TLC. After completion of the reaction,
the reaction mixture was washed with ethanol. The residue
dissolved in DCM, and the insoluble STA was separated by
simple filtration and washed with DCM. The solvent was
evaporated under reduced pressure and the obtained crude
was recrystallized from ethanol to afford the pure yellow
product 4a. The recovered catalyst was washed with ethanol
and acetone, dried and reused. Compounds 4a-4w were also
synthesized by adopting this procedure.
Experimental
Material and methods
Chemicals were purchased from Sigma-Aldrich and Alfa
Aesar Chemical Companies and used without further purifi-
cation. NMR spectra were recorded in parts per million
(ppm) in CDCl3 or DMSO-d6 on a Jeol JNM ECP 600 or
Jeol JNM ECP 400 NMR instrument using TMS as internal
standard. Standard abbreviations were used to denote signal
multiplicities (s ¼ singlet, d ¼ doublet, t ¼ triplet, q ¼ quartet
and m ¼ multiplet) and the coupling constants are given in
hertz (Hz). Mass spectra were recorded on a Jeol JMS-700
mass spectrometer. All melting points were determined
using open capillaries on an Electrothermal-9100 (Japan)
Spectral characterization
13-(4-chlorophenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
zolo[1,2-b]phthalazine-1,6,11-trione (4a) Yield 94%; yellow
1
solid; Mp: 263-265 ꢀC; H NMR (600 MHz, CDCl3) d 8.36 –
8.33 (m, 1 H), 8.27 – 8.24 (m, 1 H), 7.86 – 7.83 (m, 2 H),
7.36 – 7.34 (m, 2 H), 7.31 – 7.28 (m, 2 H), 6.40 (s, 1 H), 3.39
instrument and are uncorrected. The Supplemental
1
Materials contains sample H and 13C NMR spectra of the (dd, J ¼ 19.0, 1.3 Hz, 1 H), 3.23 (dd, J ¼ 19.1, 2.3 Hz, 1 H),
products 4a-w (Figures S1–S46).
2.33 (d, J ¼ 0.9 Hz, 2 H), 1.20 (d, J ¼ 3.8 Hz, 6 H), 13C NMR

6
A. M. JADHAV ET AL.
STA
STA
R
O
O
O
O
O
O
O
Knovengel
condensation
-H2O
NH
NH
R
H
2
3
1
5
O
R
O
O
R
N
Micheal addition
O
Cyclization
N
N
NH
O
O
HO
O
STA
6
7
O
R
O
O
OH
N
N
O
Si
STA=
SiO2
W
O
O
O
-H2O
O
O
4
Scheme 2. Possible reaction mechanism for the synthesis of 1H-indazolo[1,2-b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tetraone derivatives.
(151 MHz, CDCl3) d 192.21, 156.10, 154.48, 151.22, 135.07, 13-(4-fluorophenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
134.68, 133.78, 129.20, 128.73, 128.64, 128.16, 127.83, zolo[1,2-b]phthalazine-1,6,11-trione (4d) Yield 90%; yellow
1
118.15, 64.43, 51.00, 38.14, 34.78, 28.80, 28.54; HRMS (ESI, solid; Mp: 214-216 ꢀC; H NMR (600 MHz, CDCl3) d 8.34
m/z): calcd for C23H19ClN2O3 (M þ Hþ) 406.1084, (dd, J ¼ 5.9, 3.3 Hz, 1 H), 8.27 – 8.22 (m, 1 H), 7.86 – 7.82
found: 406.1084.
(m, 2 H), 7.41 – 7.37 (m, 2 H), 7.03 – 6.97 (m, 2 H), 6.42 (s,
1 H), 3.40 (dd, J ¼ 19.0, 1.3 Hz, 1 H), 3.23 (dd, J ¼ 19.1,
13-(4-bromophenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda- 2.3 Hz, 1 H), 2.33 (s, 2 H), 1.20 (s, 6 H), 13C NMR
zolo[1,2-b]phthalazine-1,6,11-trione (4 b) Yield 92%; yellow (151 MHz, CDCl3) d 192.25, 163.63, 161.99, 156.12, 154.49,
1
solid; Mp: 261-263 ꢀC; H NMR (600 MHz, CDCl3) d 8.36 151.12, 134.69, 133.73, 132.36, 129.09, 128.13, 127.81,
– 8.33 (m, 1 H), 8.27 – 8.23 (m, 1 H), 7.86 – 7.83 (m, 2 H), 118.32, 115.89, 115.75, 64.39, 51.03, 38.15, 34.76, 28.79,
7.45 (d, J ¼ 8.5 Hz, 2 H), 7.29 (d, J ¼ 8.5 Hz, 2 H), 6.39 (s, 28.57; HRMS (ESI, m/z): calcd for C23H19FN2O3 (M þ Hþ)
1 H), 3.39 (dd, J ¼ 19.0, 1.2 Hz, 1 H), 3.23 (dd, J ¼ 19.0, 390.1380, found: 390.1382.
2.3 Hz, 1 H), 2.32 (d, J ¼ 1.1 Hz, 2 H), 1.19 (d, J ¼ 4.6 Hz,
6 H), 13C NMR (151 MHz, CDCl3) d 192.19, 156.12, 154.51, 3,3-dimethyl-13-(p-tolyl)-2,3,4,13-tetrahydro-1H-indazolo[1,2-
151.25, 135.62, 134.74, 133.80, 132.03, 129.49, 128.82, 128.18, b]phthalazine-1,6,11-trione (4e) Yield 89%; yellow solid; Mp:
1
127.85, 122.89, 118.12, 64.52, 51.02, 38.16, 34.79, 28.81, 221-223 ꢀC; H NMR (600 MHz, CDCl3) d 8.36 – 8.31 (m,
28.55; HRMS (ESI, m/z): calcd for C23H19BrN2O3 (M þ Hþ) 1 H), 8.27 – 8.22 (m, 1 H), 7.85 – 7.80 (m, 2 H), 7.30 (d,
450.0579, found: 450.0581.
J ¼ 8.4 Hz, 2 H), 7.13 (d, J ¼ 8.6 Hz, 2 H), 6.41 (s, 1 H), 3.41
(dd, J ¼ 19.1, 1.6 Hz, 1 H), 3.23 (dd, J ¼ 19.1, 2.6 Hz, 1 H),
13-(4-methoxyphenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda- 2.32 (s, 2 H), 2.28 (s, 3 H), 1.20 (d, J ¼ 2.5 Hz, 6 H), 13C
zolo[1,2-b]phthalazine-1,6,11-trione (4c) Yield 91%; yellow NMR (151 MHz, CDCl3) d 192.25, 156.14, 154.34, 150.85,
solid; Mp: 224-226 ꢀC; 1H NMR (600 MHz, CDCl3) d 8.34 138.58, 134.55, 133.54, 129.55, 129.27, 129.09, 128.02,
– 8.31 (m, 1 H), 8.27 – 8.23 (m, 1 H), 7.84 – 7.80 (m, 2 H), 127.82, 127.17, 118.79, 100.02, 64.95, 51.08, 38.16, 34.74,
7.33 (d, J ¼ 8.8 Hz, 2 H), 6.85 (d, J¼ 8.8 Hz, 2 H), 6.41 (s, 28.81, 28.56, 21.32; HRMS (ESI, m/z): calcd for C24H22N2O3
1 H), 3.75 (s, 3 H), 3.41 (dd, J¼ 19.0, 1.3 Hz, 1 H), 3.23 (dd, (M þ Hþ) 386.1630, found: 386.1632.
J ¼ 19.0, 2.3 Hz, 1 H), 2.33 (s, 2 H), 1.21 (d, J¼ 8.0 Hz, 6 H),
13C NMR (151 MHz, CDCl3) d 192.32, 159.86, 156.17, 154.39, 13-(3-bromophenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
150.85, 134.57, 133.57, 129.30, 129.09, 128.55, 128.04, 127.81, zolo[1,2-b]phthalazine-1,6,11-trione (4f) Yield 93%; yellow
1
118.69, 114.26, 64.70, 55.32, 51.10, 38.18, 34.75, 28.82, 28.61; solid; Mp: 255-257 ꢀC; H NMR (600 MHz, CDCl3) d 8.41
HRMS (ESI, m/z): calcd for C24H22N2O4 (M þ Hþ) 402.1580, – 8.30 (m, 1 H), 8.29 – 8.17 (m, 1 H), 7.89 – 7.79 (m, 2 H),
found: 402.1582.
7.47 (t, J ¼ 2.1 Hz, 1 H), 7.43 – 7.27 (m, 2 H), 7.23 – 7.16

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
7
(m, 1 H), 6.37 (s, 1 H), 3.39 (dd, J ¼ 19.1, 1.7 Hz, 1 H), 3.23 128.83, 128.10, 127.87, 127.26, 118.75, 65.10, 51.10, 38.19,
(dd, J ¼ 19.1, 2.6 Hz, 1 H), 2.33 (d, J ¼ 2.4 Hz, 2 H), 1.20 (d,
34.79, 28.82, 28.60; HRMS (ESI, m/z): calcd for C23H20N2O3
(M þ Hþ) 372.1474, found: 372.1476.
J ¼ 5.0 Hz, 6 H), 13C NMR (151 MHz, CDCl3) d 192.12,
156.11, 154.52, 151.30, 138.79, 134.73, 133.80, 131.95,
130.33, 129.91, 129.06, 128.19, 127.86, 126.45, 122.88,
118.02, 100.02, 64.36, 51.01, 38.13, 34.80, 28.74, 28.61;
HRMS (ESI, m/z): calcd for C23H19BrN2O3 (M þ Hþ)
450.0579, found: 450.0581.
13-(2-bromophenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
zolo[1,2-b]phthalazine-1,6,11-trione (4k) Yield 92%; yellow
1
solid; Mp: 254-256 ꢀC; H NMR (600 MHz, CDCl3) d 8.37
(dd, J ¼ 6.0, 3.0 Hz, 1 H), 8.26 (dd, J ¼ 5.9, 2.9 Hz, 1 H), 7.86
– 7.83 (m, 2 H), 7.53 (d, J ¼ 7.7 Hz, 1 H), 7.43 (s, 1 H), 7.32
(t, J ¼ 6.7 Hz, 1 H), 7.15 (t, J ¼ 7.6 Hz, 1 H), 6.71 (s, 1 H),
3.39 (d, J ¼ 19.0 Hz, 1 H), 3.25 (dd, J ¼ 19.0, 1.9 Hz, 1 H),
2.32 (s, 2 H), 1.21 (d, J ¼ 2.1 Hz, 6 H), 13C NMR (151 MHz,
CDCl3) d 192.21, 156.38, 154.42, 146.55, 134.69, 134.04,
133.74, 130.25, 129.21, 128.19, 127.91, 117.20, 105.32,
103.90, 100.07, 63.43, 51.03, 38.19, 34.76, 28.86, 28.70;
HRMS (ESI, m/z): calcd for C23H19BrN2O3 (M þ Hþ)
450.0579, found: 450.0579.
3,3-dimethyl-13-(o-tolyl)-2,3,4,13-tetrahydro-1H-indazolo[1,2-
b]phthalazine-1,6,11-trione (4 g) Yield 90%; yellow solid;
1
Mp: 217-219 ꢀC; H NMR (600 MHz, CDCl3) d 8.37 – 8.32
(m, 1 H), 8.25 – 8.20 (m, 1 H), 7.82 (dd, J ¼ 5.2, 3.5 Hz,
2 H), 7.19 – 7.11 (m, 2 H), 7.07 (t, J ¼ 7.3 Hz, 1 H), 7.01 (d,
J ¼ 7.6 Hz, 1 H), 6.62 (s, 1 H), 3.42 (d, J ¼ 19.0 Hz, 1 H), 3.24
(d, J ¼ 18.8 Hz, 1 H), 2.73 (s, 3 H), 2.30 (d, J ¼ 4.9 Hz, 2 H),
1.20 (d, J ¼ 10.2 Hz, 6 H), 13C NMR (151 MHz, CDCl3) d
192.32, 156.19, 154.40, 150.91, 149.24, 134.57, 133.63,
129.31, 129.12, 128.05, 127.83, 127.21, 126.95, 118.83,
100.04, 64.85, 51.13, 38.18, 34.77, 33.89, 28.74, 23.92; HRMS
(ESI, m/z): calcd for C24H22N2O3 (M þ Hþ) 386.1630,
found: 386.1632.
3,3-dimethyl-13-(3,4,5-trimethoxyphenyl)-2,3,4,13-tetrahydro-1H-
indazolo[1,2-b]phthalazine-1,6,11-trione (4 l) Yield 91%; yellow
1
solid; Mp: 226-228 ꢀC; H NMR (600 MHz, CDCl3) d 8.35
(dd, J ¼ 6.1, 2.9 Hz, 1 H), 8.29 (dd, J ¼ 6.0, 2.8 Hz, 1 H), 7.88
– 7.83 (m, 2 H), 6.62 (s, 2 H), 6.38 (s, 1 H), 3.80 (d,
J ¼ 15.8 Hz, 9 H), 3.44 (d, J ¼ 19.0 Hz, 1 H), 3.20 (dd,
J ¼ 19.0, 1.9 Hz, 1 H), 2.35 (s, 2 H), 1.22 (d, J ¼ 8.5 Hz, 6 H),
13C NMR (151 MHz, CDCl3) d 192.28, 156.27, 154.67,
153.51, 151.00, 134.74, 133.74, 131.93, 129.15, 128.15,
127.88, 118.46, 104.80, 100.06, 65.13, 60.83, 56.33, 51.11,
38.22, 34.76, 29.08, 28.29; HRMS (ESI, m/z): calcd for
C26H26N2O6 (M þ Hþ) 462.1791, found: 462.1793.
13-(4-isopropylphenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
zolo[1,2-b]phthalazine-1,6,11-trione (4 h) Yield 91%; yellow
1
solid; Mp: 215-217 ꢀC; H NMR (600 MHz, CDCl3) d 8.36
– 8.32 (m, 1 H), 8.28 – 8.24 (m, 1 H), 7.86 – 7.80 (m, 2 H),
7.32 (d, J ¼ 8.0 Hz, 2 H), 7.17 (d, J ¼ 8.0 Hz, 2 H), 6.43 (s,
1 H), 3.41 (d, J ¼ 19.0 Hz, 1 H), 3.23 (dd, J ¼ 19.0, 1.6 Hz,
1 H), 2.84 (m, 1 H), 2.33 (s, 2 H), 1.22 (s, 3 H), 1.20 (d,
J ¼ 3.4 Hz, 6 H), 1.18 (s, 3 H), 13C NMR (151 MHz, CDCl3)
d 192.32, 156.19, 154.40, 150.91, 149.24, 134.57, 133.63,
129.31, 129.12, 128.05, 127.83, 127.21, 126.95, 118.83,
100.04, 64.85, 51.13, 38.18, 34.77, 33.89, 28.74, 23.93, 23.91;
HRMS (ESI, m/z): calcd for C26H26N2O3 (M þ Hþ)
414.1943, found: 414.1945.
13-(3-methoxyphenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
zolo[1,2-b]phthalazine-1,6,11-trione (4 m) Yield 88%; yellow
1
solid; Mp: 215-217 ꢀC; H NMR (600 MHz, CDCl3) d 8.33
(dd, J ¼ 6.0, 3.2 Hz, 1 H), 8.25 (dd, J ¼ 5.9, 3.2 Hz, 1 H), 7.82
(dd, J ¼ 4.5, 2.4 Hz, 2 H), 7.23 (dd, J ¼ 14.9, 7.0 Hz, 1 H),
6.98 (d, J ¼ 7.7 Hz, 1 H), 6.93 (s, 1 H), 6.79 (dd, J ¼ 8.2,
2.3 Hz, 1 H), 6.39 (s, 1 H), 3.76 (s, 3 H), 3.38 (d, J ¼ 18.9 Hz,
1 H), 3.21 (dd, J ¼ 19.0, 2.2 Hz, 1 H), 2.31 (s, 2 H), 1.19 (d,
J ¼ 2.6 Hz, 6 H), 13C NMR (151 MHz, CDCl3) d 192.20,
159.86, 156.14, 154.41, 150.93, 138.13, 134.61, 133.63,
129.82, 129.17, 128.09, 127.85, 119.54, 118.68, 113.96,
113.27, 100.04, 64.91, 55.33, 51.09, 38.16, 34.76, 28.79, 28.60;
HRMS (ESI, m/z): calcd for C24H22N2O4 (M þ Hþ)
402.1580, found: 402.1582.
13-(3-chlorophenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
zolo[1,2-b]phthalazine-1,6,11-trione (4i) Yield 94%; yellow
1
solid; Mp: 255-257 ꢀC; H NMR (600 MHz, CDCl3) d 8.38
– 8.32 (m, 1 H), 8.28 – 8.20 (m, 1 H), 7.89 – 7.82 (m, 2 H),
7.37 – 7.29 (m, 2 H), 7.28 – 7.21 (m, 2 H), 6.38 (s, 1 H), 3.38
(d, J ¼ 19.0 Hz, 1 H), 3.23 (dd, J ¼ 19.1, 1.7 Hz, 1 H), 2.32 (s,
2 H), 1.19 (d, J ¼ 3.9 Hz, 6 H), 13C NMR (151 MHz, CDCl3)
d 192.10, 156.09, 154.49, 151.25, 138.53, 134.71, 133.76,
130.03, 129.04, 128.17, 127.85, 127.02, 125.89, 118.03, 64.39,
50.99, 38.10, 34.77, 28.64; HRMS (ESI, m/z): calcd for
C23H19ClN2O3 (M þ Hþ) 406.1084, found: 406.1084.
13-(3-fluorophenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
zolo[1,2-b]phthalazine-1,6,11-trione (4n) Yield 89%; yellow
1
solid; Mp: 210-212 ꢀC; H NMR (600 MHz, CDCl3) d 8.35
3,3-dimethyl-13-phenyl-2,3,4,13-tetrahydro-1H-indazolo[1,2-
b]phthalazine-1,6,11-trione (4j) Yield 94%; yellow solid;
Mp: 202-204 ꢀC; 1H NMR (600 MHz, CDCl3) d 8.34 (dd,
J ¼ 6.0, 3.1 Hz, 1 H), 8.25 (dd, J ¼ 6.0, 3.0 Hz, 1 H), 7.82 (dd,
J ¼ 5.5, 3.6 Hz, 2 H), 7.40 (d, J ¼ 7.4 Hz, 2 H), 7.31 (t,
J ¼ 7.5 Hz, 2 H), 7.26 (d, J ¼ 14.6 Hz, 1 H), 6.43 (s, 1 H), 3.40
(d, J ¼ 19.0 Hz, 1 H), 3.23 (dd, J ¼ 19.0, 1.9 Hz, 1 H), 2.32 (s,
2 H), 1.19 (s, 6 H), 13C NMR (151 MHz, CDCl3) d 192.21,
(dd, J ¼ 6.0, 3.1 Hz, 1 H), 8.26 (dd, J ¼ 6.0, 3.1 Hz, 1 H), 7.89
– 7.82 (m, 2 H), 7.32 – 7.28 (m, 1 H), 7.23 (d, J ¼ 7.7 Hz,
1 H), 7.08 (d, J ¼ 9.4 Hz, 1 H), 6.97 (m, 1 H), 6.42 (s, 1 H),
3.39 (d, J ¼ 19.0 Hz, 1 H), 3.24 (dd, J ¼ 19.1, 2.0 Hz, 1 H),
2.33 (s, 2 H), 1.20 (s, 6 H), 13C NMR (151 MHz, CDCl3) d
192.11, 163.79, 162.15, 156.08, 154.48, 151.20, 139.00,
134.69, 133.75, 130.32, 129.04, 128.16, 127.83, 123.10,
156.18, 154.42, 150.96, 136.54, 134.62, 133.64, 129.19, 118.12, 115.85, 115.71, 114.20, 114.05, 64.40, 51.00, 38.11,

8
A. M. JADHAV ET AL.
34.74, 28.72, 28.56; HRMS (ESI, m/z): calcd for (4s) Yield 94%; yellow solid; Mp: 314-316 ꢀC; 1H NMR
C23H19FN2O3 (M þ Hþ) 390.1380, found: 390.1982.
(600 MHz, CDCl3) d 8.51 (s, 1 H), 7.51 – 7.39 (m, 5 H), 7.23
(d, J ¼ 2.0 Hz, 1 H), 7.18 (dd, J ¼ 8.4, 2.1 Hz, 1 H), 6.68
(d, J ¼ 8.3 Hz, 1 H), 3.05 (d, J ¼ 18.5 Hz, 1 H), 2.90 (d,
J ¼ 18.5 Hz, 1 H), 2.31 (dd, J ¼ 0.9 Hz, 2 H), 1.20 (d,
J ¼ 23.3 Hz, 6 H), 13C NMR (151 MHz, CDCl3) d 191.45,
170.59, 152.82, 150.48, 148.26, 140.25, 131.07, 130.49,
129.53, 129.25, 128.78, 126.78, 126.10, 124.76, 118.67,
112.53, 100.06, 71.01, 51.16, 35.73, 35.30, 28.93, 28.01;
HRMS (ESI, m/z): calcd for C24H19ClN4O4 (M þ Hþ)
462.1095, found: 462.1097.
13-(2-methoxyphenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-inda-
zolo[1,2-b]phthalazine-1,6,11-trione (4o) Yield 88%; yellow
1
solid; Mp: 214-216 ꢀC; H NMR (600 MHz, CDCl3) d 8.38
– 8.33 (m, 1 H), 8.25 (dd, J ¼ 5.9, 3.1 Hz, 1 H), 7.85 – 7.80
(m, 2 H), 7.44 (dd, J ¼ 7.5, 1.1 Hz, 1 H), 7.26 – 7.22 (m,
1 H), 6.96 (t, J ¼ 7.4 Hz, 1 H), 6.82 (d, J ¼ 8.2 Hz, 1 H), 6.57
(s, 1 H), 3.70 (s, 3 H), 3.43 (d, J ¼ 18.9 Hz, 1 H), 3.18 (dd,
J ¼ 18.9, 2.1 Hz, 1 H), 2.29 (s, 2 H), 1.18 (d, J ¼ 25.7 Hz, 6 H),
13C NMR (151 MHz, CDCl3) d 192.34, 157.31, 156.32,
154.14, 151.45, 134.41, 133.40, 130.39, 130.08, 129.18, 5-fluoro-7’,7’-dimethyl-2’-phenyl-7’,8’-dihydro-1’H-spiro[indo-
127.94, 127.74, 123.71, 121.08, 117.62, 111.38, 62.97, 55.82, line-3,9’-[1,2,4]triazolo[1,2-a]indazole]-1’,2,3’,5’(2’H,6’H)-tet-
51.09, 38.21, 34.74, 29.09, 28.04; HRMS (ESI, m/z): calcd for raone (4t) Yield 91%; yellow solid; Mp: 310-312 ꢀC; 1H
C24H22N2O4 (M þ Hþ) 402.1580, found: 402.1580.
NMR (600 MHz, CDCl3) d 7.94 (s, 1 H), 7.50 – 7.39 (m,
5 H), 7.02 – 6.96 (m, 2 H), 6.78 (dd, J ¼ 8.5, 4.0 Hz, 1 H),
3.05 (d, J ¼ 18.5 Hz, 1 H), 2.91 (d, J ¼ 18.5 Hz, 1 H), 2.31 (q,
13-(2,4-dimethoxyphenyl)-3,3-dimethyl-2,3,4,13-tetrahydro-1H-
indazolo[1,2-b]phthalazine-1,6,11-trione (4p) Yield 87%; yel- J ¼ 8.4 Hz, 2 H), 1.23 (s, 3 H), 1.20 (s, 3 H), 13C NMR
low solid; Mp: 218-220 ꢀC; 1H NMR (600 MHz, CDCl3) d (151 MHz, CDCl3) d 191.28, 170.81, 152.70, 150.53, 148.34,
8.36 (s, 1 H), 8.25 (s, 1 H), 7.83 (s, 2 H), 6.95 (s, 1 H), 6.77 130.56, 129.51, 129.21, 126.07, 118.74, 117.65, 117.38,
(s, 2 H), 6.55 (s, 1 H), 3.76 (s, 3 H), 3.68 (s, 3 H), 3.42 (d, 117.27, 112.23, 71.28, 51.20, 35.78, 35.32, 28.86, 28.08;
J ¼ 18.9 Hz, 1 H), 3.18 (d, J ¼ 18.8 Hz, 1 H), 2.30 (m, 2 H), HRMS (ESI, m/z): calcd for C24H19FN4O4 (M þ Hþ)
1.18 (d, J ¼ 20.7 Hz, 6 H), 13C NMR (151 MHz, CDCl3) d 446.1390, found: 446.1392.
192.35, 156.32, 151.68, 151.56, 134.46, 133.46, 129.19,
128.00, 127.88, 117.68, 115.77, 114.62, 112.69, 100.07, 63.39, 5,7’,7’-trimethyl-2’-phenyl-7’,8’-dihydro-1’H-spiro[indoline-3,9’-
56.58, 55.79, 51.12, 38.22, 34.77, 29.02, 28.17; HRMS (ESI, [1,2,4]triazolo[1,2-a]indazole]-1’,2,3’,5’(2’H,6’H)-tetraone (4 u)
m/z): calcd for C25H24N2O5 (M þ Hþ) 432.1685, Yield 90%; yellow solid; Mp: 318-320 ꢀC; 1H NMR
found: 432.1687.
(600 MHz, CDCl3) d 8.15 (s, 1 H), 7.48 – 7.37 (m, 5 H), 7.07
– 7.04 (m, 2 H), 6.74 – 6.71 (m, 1 H), 3.05 (d, J ¼ 18.5 Hz,
3,3-dimethyl-13-(4-nitrophenyl)-2,3,4,13-tetrahydro-1H-inda- 1 H), 2.91 (d, J ¼ 18.5 Hz, 1 H), 2.31 (s, 1 H), 2.30 (s, 1 H),
zolo[1,2-b]phthalazine-1,6,11-trione (4q) Yield 89%; yellow 2.29 (s, 3 H), 1.21 (d, J ¼ 14.6 Hz, 6 H), 13C NMR (151 MHz,
1
solid; Mp: 224-226 ꢀC; H NMR (600 MHz, CDCl3) d 8.38 CDCl3) d 191.44, 171.02, 152.31, 150.34, 148.40, 139.18,
(dd, J ¼ 6.1, 3.0 Hz, 1 H), 8.26 (dd, J ¼ 5.6, 3.0 Hz, 1 H), 8.21 133.19, 131.63, 130.74, 129.53, 129.15, 126.14, 125.19,
(d, J ¼ 8.5 Hz, 2 H), 7.91 – 7.86 (m, 2 H), 7.60 (d, J ¼ 8.5 Hz, 125.05, 119.24, 111.27, 71.41, 51.31, 35.81, 35.34, 28.93,
2 H), 6.51 (s, 1 H), 3.40 (d, J ¼ 19.1 Hz, 1 H), 3.26 (d, 28.23, 21.33; HRMS (ESI, m/z): calcd for C25H22N4O4
J ¼ 18.9 Hz, 1 H), 2.17 (s, 2 H), 1.20 (d, J ¼ 16.1 Hz, 6 H), (M þ Hþ) 442.1641, found: 442.1643.
13C NMR (151 MHz, CDCl3) d 192.19, 156.13, 151.80,
148.08, 143.57, 134.98, 134.12, 130.63, 129.10, 128.40, 2,2-dimethyl-2,3-dihydrospiro[indazolo[1,2-b]phthalazine-13,3’-
indoline]-2’,4,6,11(1H)-tetraone (4v) Yield 94%; yellow solid;
128.21, 127.95, 124.47, 124.23, 117.48, 64.32, 50.97, 38.20,
34.90, 28.84, 28.54; HRMS (ESI, m/z): calcd for C23H19N2O5
(M þ Hþ) 417.1325, found: 417.1327.
1
Mp: 282-284 ꢀC; H NMR (400 MHz, CDCl3) d 8.38 – 8.35
(m, 1 H), 8.25 (s, 1 H), 8.23 – 8.20 (m, 1 H), 7.87 – 7.84 (m,
2 H), 7.29 – 7.24 (m, 1 H), 7.09 – 7.06 (m, 1 H), 7.00 – 6.96
7’,7’-dimethyl-2’-phenyl-7’,8’-dihydro-1’H-spiro[indoline-3,9’- (m, 1 H), 6.90 (d, J ¼ 7.8 Hz, 1 H), 3.35 (dd, J ¼ 18.5, Hz,
[1,2,4]triazolo[1,2-a]indazole]-1’,2,3’,5’(2’H,6’H)-tetraone (4r) 2 H), 2.33 (q, J ¼ 8.4 Hz, 2 H), 1.23 (s, 3 H), 1.21 (s, 3 H),
Yield 92%; yellow solid; Mp: 297-299 ꢀC; 1H NMR 13C NMR (101 MHz, CDCl3) d 191.33, 171.09, 156.07,
(600 MHz, CDCl3) d 8.36 (s, 1 H), 7.51 – 7.46 (m, 5 H), 7.26 153.89, 152.97, 141.91, 134.83, 134.06, 130.77, 129.10,
(m, 2 H), 7.07 (m, 1 H), 6.80 (dd, J ¼ 7.2, 1.3 Hz, 1 H), 3.08 128.75, 128.36, 128.24, 124.38, 123.12, 116.99, 111.09, 71.91,
(d, J ¼ 18.5 Hz, 1 H), 2.95 (d, J ¼ 18.5 Hz, 1 H), 2.33 (d, 50.86, 38.29, 35.06, 28.68, 28.41; HRMS (ESI, m/z): calcd for
J ¼ 1.5 Hz, 2 H), 1.24 (s, 3 H), 1.23 (s, 3 H), 13C NMR C24H19N3O4 (M þ Hþ) 413.1376, found: 413.1376.
(151 MHz, CDCl3) d 191.34, 170.80, 152.30, 150.23, 148.31,
2,2,5’-trimethyl-2,3-dihydrospiro[indazolo[1,2-b]phthalazine-
141.63, 131.07, 130.59, 129.44, 129.08, 126.05, 125.06,
124.18, 123.41, 119.10, 111.53, 71.18, 51.16, 35.70, 35.26, 13,3’-indoline]-2’,4,6,11(1H)-tetraone (4w) Yield 92%; yel-
low solid; Mp: 294-296 ꢀC; 1H NMR (600 MHz, CDCl3) d
28.68, 28.19; HRMS (ESI, m/z): calcd for C24H20N4O4
8.38 – 8.35 (m, 1 H), 8.27 (s, 1 H), 8.24 – 8.21 (m, 1 H), 7.87
(M þ Hþ) 428.1485, found: 428.1486.
– 7.83 (m, 2 H), 7.07 – 7.03 (m, 1 H), 6.87 (s, 1 H), 6.79 (d,
5-chloro-7’,7’-dimethyl-2’-phenyl-7’,8’-dihydro-1’H-spiro[indo- J ¼ 8.0 Hz, 1 H), 3.36 (m, 2 H), 2.34 (q, J ¼ 16.3 Hz, 2 H),
line-3,9’-[1,2,4]triazolo[1,2-a]indazole]-1’,2,3’,5’(2’H,6’H)-tetraone 2.22 (s, 3 H), 1.22 (d, J ¼ 4.8 Hz, 6 H), 13C NMR (151 MHz,

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
9
Easily Available Oxindole-derived a,b-unsaturated Imines.
Tetrahedron, 2014, 70, 2838–2846. DOI: 10.1016/j.tet.2014.02.052.
[8] (a) Jiang, B.; Cao, L. J.; Tu, S. J.; Zheng W. R.; Yu, H. Z.
CDCl3) d 191.34, 171.11, 156.06, 153.86, 152.85, 139.56,
134.78, 133.99, 132.62, 131.22, 129.12, 128.82, 128.30,
128.15, 124.29, 123.76, 117.13, 110.80, 100.04, 72.09, 50.91,
38.29, 35.04, 28.56, 21.23; HRMS (ESI, m/z): calcd for
C25H21N3O4 (M þ Hþ) 427.1532, found: 427.1534.
Highly
Diastereoselective
Domino
Synthesis
of
6-
Spirosubstituted Pyrido[2,3-d]pyrimidine Derivatives in Water.
J. Comb. Chem. 2009, 11, 612–616. DOI: 10.1021/cc900038g.
(b) Jadhav, A. M.; Balwe, S. G.; Lim, K. T.; Jeong, Y. T. A
Novel Three-Component Method for the Synthesis of
Spiro[chromeno [40,30:4,5] pyrimido[1,2-b] indazole-7,30-indo-
line]-20,6(9H)-dione. Tetrahedron 2017, 73, 2806–2813. DOI:
10.1016/j.tet.2017.03.084.
Conclusion
In summary, a mild, efficient, and expeditious method has
been developed for the synthesis of 1 H-indazolo[1,2-
b]phthalazine-trione and spiro-triazolo[1,2-a]indazole-tet-
raone derivatives via a three-component reaction between
phthalhydrazide or 4-phenylurazole, aldehydes or isatins and
dimedone using Silica supported tungstic acid (STA), as het-
erogeneous catalyst under solvent-free conditions. This
method offers several advantages, including high yields,
short reaction times, simple work-up, easy recovery of cata-
lyst, broad substrate scope and pure products can be isolated
without the use of column chromatography. We believe
that, this method can provide rapid access to the com-
pounds that can be highly useful in medicinal chemistry and
material science.
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Disclosure statement
Hybrid Heterocycles. Eur. J. Med. Chem. 2013, 65, 240–248.
DOI: 10.1016/j.ejmech.2013.04.050.
No potential conflict of interest was reported by the authors.
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ORCID
Yeon Tae Jeong
http://orcid.org/0000-0002-2943-6954
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