A new class of pyrazolo[5,1-c][1,2,4]triazines as γ-aminobutyric type A (GABAA) receptor subtype ligand: synthesis and pharmacological evaluation

Article abstract of DOI:10.1016/j.bmc.2018.04.011

A comparison between compounds with pyrazolo[1,5-a]pyrimidine structure (series 4–6) and pyrazolo[5,1-c][1,2,4]triazine core (series 9) as ligands at GABA_A-receptor subtype, was evaluated. Moreover, for pyrazolotriazine derivatives having binding recognition, the interaction on recombinant rat α(1–3,5) GABA_A receptor subtypes, was performed. Among these latter, emerge compounds 9c, 9k, 9l, 9m and 9n as α1-selective and 9h as α2-selective ligands.

Full text of DOI:10.1016/j.bmc.2018.04.011

Accepted Manuscript
A new class of pyrazolo[5,1-c][1,2,4]triazines as γ-aminobutyric type A (GA-
BAA) receptor subtype ligand: synthesis and pharmacological evaluation
Gabriella Guerrini, Giovanna Ciciani, Simona Daniele, Claudia Martini,
Camilla Costagli, Chiara Guarino, Silvia Selleri
PII:
S0968-0896(18)30161-5
https://doi.org/10.1016/j.bmc.2018.04.011
BMC 14294
DOI:
Reference:
Bioorganic & Medicinal Chemistry
To appear in:
Received Date:
Revised Date:
Accepted Date:
15 February 2018
23 March 2018
3 April 2018
Please cite this article as: Guerrini, G., Ciciani, G., Daniele, S., Martini, C., Costagli, C., Guarino, C., Selleri, S., A
new class of pyrazolo[5,1-c][1,2,4]triazines as γ-aminobutyric type A (GABAA) receptor subtype ligand: synthesis
and pharmacological evaluation, Bioorganic & Medicinal Chemistry (2018), doi: https://doi.org/10.1016/j.bmc.
2018.04.011
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A new class of pyrazolo[5,1-c][1,2,4]triazines as -aminobutyric type A (GABAA) receptor
subtype ligand: synthesis and pharmacological evaluation
Gabriella Guerrini,a* Giovanna Ciciani,a Simona Daniele,b Claudia Martini,b Camilla Costagli,a
Chiara Guarino,a Silvia Selleria
aDipartimento NEUROFARBA, sezione Farmaceutica e Nutraceutica, Università degli Studi di
Firenze, Italy
bDipartimento FARMACIA, Università degli Studi di Pisa, Italy
*Corresponding author: Guerrini Gabriella, Dipartimento NEUROFARBA, sezione Farmaceutica e
Nutraceutica, Università degli Studi di Firenze, Italy, Via Ugo Schiff, 6, Sesto Fiorentino Firenze,
50019; tel. +390554573766; e-mail: gabriella.guerrini@unifi.it

Abstract
A comparison between compounds with pyrazolo[1,5-a]pyrimidine structure (series 4-6) and
pyrazolo[5,1-c][1,2,4]triazine core (series 9) as ligands at GABAA-receptor subtype, was evaluated.
Moreover, for pyrazolotriazines derivatives having binding recognition, the interaction on
recombinant rat(1-3,5) GABAA receptor subtypes, was performed. Among these latter, emerge
compounds 9c, 9k, 9l, 9m and 9n as 1-selective and 9h as 2-selective ligands.
1. Introduction
The -aminobutyric acid type A receptors (GABAA-Rs) are ligand-gated chlorine channels
belonging to cys-loop receptors superfamily which also includes the nicotinic acetylcholine
receptor, the 5HT3 and glycine receptors. The GABAA-Rs are involved in neurological disorders
and are interesting target for a variety of drugs for the treatment of insomnia, anxiety, epilepsy,
pain, cognitive impairments, some forms of depression and schizophrenia. 1
The GABAA-R is a heteropentameric channel formed by subunits belonging to 8 families (1-6,
1-3, 1-3, , , ,  and 1-3) and the subtypes mostly expressed in CNS are composed of three
subunit (, , ) in stoichiometric ratio 2:21, and ---- arranged (if read counter clock-
wise when view from extracellular domain). It is known that the two orthosteric GABA binding
sites lie at the +/- interfaces in the extracellular domain, while an allosteric binding pocket,
already known as ‘benzodiazepine receptor site’ and currently named ‘GABAA-R subtype’, exists at
the +/- interface.2 The -subunit type (1-3 and 5) constituting the pentamer expresses the
benzodiazepine pharmacology and, from mouse subunit knock-in approach was evidenced that 1 it
is responsible of sedation, 2/3 of anxiolityc-like, antihiperalgesic and miorelaxant activity and,
finally, the 5 subunit is implicated in learning and memory.3 In the last decade the identification of
separable key functions of GABAA receptor subtypes, suggests not only the overcoming limitations
of classical benzodiazepines but also the opening of a fascinating scenario for new therapeutic
indications in schizophrenia, chronic pain, cognitive diseases.4

Our research group has extensively investigated fused heterocyclic systems containing variable
nitrogen atoms as potential GABAA-R subtype ligands and very interesting results have stand out:
opportunely substituted pyrazolo[5,1-c][1,2,4]benzotriazines (PBT), pyrazolo[1,5-a]quinazolines
(PQ) and pyrazolo[1,5-a]pyrimidines (PP), exhibit high affinity to GABAA-R subtype. Some
compounds afforded in vivo interesting results, having promnemonic and/or dual activity
(anxiolytic-like and antihyperalgesic), 5–8 Chart 1.
Chart 1
PBT
PQ
PP
PT

Deeping our study on bicycle systems, we have again taken up compounds with 6-(1H-pyrazol-3-
yl)pyrazolo[1,5-a]pyrimidin-4-one (PP) scaffold and new substituents/ moieties at 3-/6-position
were inserted. At the same time we performed the synthesis of a new series of pyrazolo[5,1-
c][1,2,4]triazine (PT), as 5-azaisomers of PP. The affinity to GABAA-R subtype of the two series of
bicycles (PP and PT) was evaluated as well as subtype selectivity of PTs by using recombinant rat
1-3,5)GABAA-R subtypes.
2. Chemistry
Chemical data of new derivatives here described are reported in SI and listed in Tables S1-S5.
The 3-aminopyrazoles differently substituted at position 4, are used as starting material for the
synthesis of both pyrazolopyrimidines (schemes 1, 2) and pirazolotriazines (schemes 3, 4).
Compounds 6-(1H-pyrazol-3-yl)pyrazolo[1,5-a]pyrimidin-7(4H)-ones) 3-aryl/heteroaryl substituted
4b-g, were obtained following a previously described procedure 9–11 and depicted in Scheme 1. The
3(5)-aminopyrazoles 4-substituted (1a-f) were reacted with ethyl 2-acetyl-3-ethoxyacrylate and the
intermediates ethyl 7-methylpyrazolo[1,5-a]pyrimidine-6-carboxylate 3-substituted 2a-f were
obtained. The 3-nitro derivative 2a was reduced to the corresponding 3-aminoderivative (2a’)
which was reacted with 2,5-dimethoxytetrahydrofurane to give the 3-(pyrrol-1-yl)-derivative 2g.
Therefore compounds 2b-g were first treated with DMF-DMA (affording 3b-g) and then with
hydrazine hydrate to yield compounds 4b-g (Scheme 1).
The introduction at position 6 of the pyrazolo[1,5-a]pyrimidine core of a pyrazol-1-yl or imidazole-
1-yl ring, was carried out through a one-step reaction between the ethyl 3-oxo-2-(1H-pyrazol-1-
yl)propanoate A or ethyl 2-(1H-imidazol-1-yl)-3-oxopropanoate B and 3(5)-amino-4-(thien-2-
yl)pyrazolo (1h) or 3(5)-amino-4-phenylpyrazolo (1i) in dyglime9,11–15 obtaining the final
compounds 5a, b and 6a, b (Scheme 2). Reagents A and B were in turn prepared by a formylation
reaction, starting from the corresponding ethyl (pyrazol-1-yl)- and (imidazole-1-yl)acetate.16
The synthesis of final pyrazolo[5,1-c][1,2,4] triazin-4-(1H)-one derivatives type 9, were obtained in
a convenient manner as reported in Scheme 3.

Scheme 1
N
N
H3C
N
NH2.HCl
H3C
iii
N
N
N
N
EtOOC
EtOOC
OCH
3
H CO
3
O
2a’
2g
iv
ii
2a
CH3CO
EtOOC
CH3
H3C
N
OEt
N
N
N
HN
H3C
N
N
R
R
R
NH2
N
N
i
iv
EtOOC
EtOOC
1a-f
2a-f
3b-g
v
1-4
a
R
NO2
N
Benzyl
b
N
O
R
3-Py
c
NH
2-Py
d
e
f
1-Naphtyl
2-Naphtyl
Pyrrol-1-yl
N
N
H
4b-g
g
Reagents and conditions: i) ethyl ethoxymethylacetoacetate/EtOH; ii) 10% Pd/C, H2 40 psi, EtOH,
HCl; iii) Dimethoxytetrahydrofurane/dioxane; iv) DMF-DMA, toluene, piperidine cat.; v) hydrazine
hydrate 60%; acetic acid, sodium acetate.

Scheme 2
N
N
O
R
COOEt
CHO
NH
N
N
N
N
A
5a, b
N
HN
R
i
NH2
N
COOEt
CHO
1h, i
N
O
R
N
NH
N
N
B
N
6a, b
R
Compds
2-Thienyl
Ph
1h, 5a, 6a
1i, 5b, 6b
Reagents and conditions: i) dyglime reflux

Scheme 3.
O
O
N
H C
OEt
3
N
HN
H3C
O
N
HN
HN
R
R
Cl-
N
R
EtO
+
ii
N
i
N2
NH2
O
1c-f, 1h-p
CH3
N
H3C
N
N
N
O
N
R
H3C
N
N
R
R
NH
N
N
N
iv
iii
N
N
H
N
EtOOC
N
EtOOC
9c-f, 9h-p
7c-f, 7h-p
8c-f, 8h-p
R
1, 7-9
3-Py
c
d
e
f
2-Py
1-Naphtyl
2-Naphtyl
2-Thienyl
Ph
h
i
3-FPh
j
4-FPh
k
l
3-ClPh
3-BrPh
3-CF3Ph
4-OCH3Ph
4-CH3Ph
m
n
o
p
Reagents and conditions: i) HCl, NaNO2/H2O; ii) sodium acetate, ethyl acetoacetate iii) DMF-
DMA, toluene, piperidine cat.; iv) hydrazine hydrate 60%; acetic acid, sodium acetate.

Scheme 4
1
f
R
2-Naphtyl
3-Thienyl 9
3-OCH3Ph9
q
r
O
O
N
H C
OEt
i
3
N
N
N
R
H3C
HN
HN
N
R
R
+
N
EtOOC
N
H2N
2 Cl-
1f, q, r
N
N
N
HN
HN
OCH3
HN
N+
N+
N+
1
S
2
6
N
N
N
N
N
N
N
HN
HN
HN
OCH3
N
N
N
S
N
N
10 (20%)
11
12
N
N
O
NH
N
N
N
H
9f (80%)
Reagents and conditions: i) HCl, NaNO2/H2O;

The suitable 3(5)-aminopyrazoles 4-substituted (1c-f, 1h-p) were diazotized and then cyclized with
ethyl acetoacetate to ethyl 4-methylpyrazolo[5,1-c][1,2,4]triazines 3-carboxylate 8-substituted,
compound of type 7. Since the methyl group at position 4 shows acid features, as evidenced by the
relatively high value of its chemical shift (about 3.25 ppm), it can be easily transformed into a
dimethylaminovinyl moiety with dimethylformamide-dimethylacetal (DMF-DMA) according to the
Brederek reaction.17 The obtained intermediate 4-dimethylaminovinyles (compounds of type 8)
showed two geometrical isomers as evidenced by TLC and 1H-NMR spectra. The high reactivity of
the dimethylaminovinyl derivatives towards hydrazine hydrate easily leads to final compounds 9c-f,
9h-p in a reaction manner already investigated in the reported for pyrazolo[1,5-a]pyrimidines.9
A special case is highlighted when at position 4 of the 3(5)-aminopyrazole a 2-naphtalene ring (1f),
3-thiofene9 (1q) or 3-methoxyphenyl9 (1r) are present; in fact, the corresponding highly reactive
diazonium salts prefer the electrophilic intramolecular attack to 4-hetero/aryl ring electron rich
position of the aminopyrazole, instead of the coupling reaction with ethyl acetoacetate. (Scheme 4)
In particular the positions 1, 2 and 6 of the naphthalene, thiofene and methoxyphenyl ring
respectively, were attacked by diazo group affording the tricyclic derivatives 10-12, whose
structures were confirmed by crystallographic analysis (data not shown). Starting from 3-(thien-3-
yl)- and 3-(3-methoxyphenyl)pyrazole, exclusively led to 3H-pyrazolo[3,4-c]thieno[3,2-
e]pyridazine 11 and 8-methoxy-3H-pyrazolo[3,4-c]cinnoline 12, respectively, while starting from
3-(2-naphtyl)pyrazole 1f, preferentially is obtained the pyrazoletriazine 9f in good yield (80%) and
the tetracyclic compound, 1H-benzo[h]pyrazolo[3,4-c]cinnoline 10, only as by-product (20%).
Biological results and discussion
The Bz site/GABAA-R binding affinity of newly synthesized compounds was evaluated by their
ability to displace [3H]flumazenil (Ro15-1788) from its specific binding in bovine brain membrane
and was expressed as Ki value limited to those compounds inhibiting radioligand binding by more
than 80% at 10M. The binding data of the new pyrazolo[1,5-a]pyrimidines (4b-g, 5a, b and 6a, b)
and of reference compounds I and II,9,10 are reported in Table 1.

N
N
O
R
NH
Z
Y
X
Table 1. Binding data for pyrazolo[1,5-a]pyrimidine derivatives 4b-g, 5a, b and 6a,b.
I% - Ki (nM)a
N°
4b
4c
4d
4e
4f
R
X
Y
Z
C
C
C
C
C
C
N
N
N
N
C
C
CH2Ph
3-Py
NH
NH
NH
NH
NH
NH
CH
CH
N
N
854±23
37.3±0.3
14.2±1.6
599±22
20%
N
2-Py
N
1-Naphtyl
2-Naphtyl
1-Pyrrolyl
2-Thienyl
Ph
N
N
N
2670±25
13.9%
4g
5a
5b
6a
6b
I
N
N
59.5%
2-Thienyl
Ph
CH
CH
N
14.7%
N
2%
2-Thienyl
Ph
NH
NH
533±27b
326.3±37c
N
II
a Percent inhibition values of specific [3H]Ro15-1788 binding at 10 M concentration and Ki values
are means ±SEM of five determinations; bsee ref 9; csee ref 10
Among the new synthesized compounds (4b-4g), the most promising are 4c and 4d both bearing a
pyridine ring at position 3; looking at Ki value (37 nM and 14.2 nM respectively) it can reasonably
be said that the 2- or 3-position of nitrogen atom is irrelevant. All other compounds show poor
affinity (4b, e) or no affinity (4f, g). When in the lead compounds I and II the pyrazole nucleus at
position 6 was differently connected, as in the new compounds 5a, b or replaced by imidazole ring

(6a, b), the binding affinity dramatically falls down, thus indicating that the presence of NH group
on 6-substitutent is required for receptor binding, Table 1.
As concerning pyrazolo[5,1-c][1,2,4]triazine derivatives (9c-f, 9h-p) designed and synthesized as 5-
aza isomers of the pyrazolo[1,5-a]pyrimidines, the receptor affinity (Table 2) is generally fair (Ki
range 38-329 nM), with exception of compounds 9f, 9o and 9p which show very poor or no
affinity. Among the compounds belonging to the 9 series, emerged 9d and 9n bearing at position 3
a 2-pyridyl and 3-trifluoromethylphenyl ring respectively, they exhibit affinity values in the
nanomolar range (9d, Ki = 10.5 nM; 9n Ki = 7.2 nM).
N
N
O
R
NH
N
N
N
H
Table 2. Binding data for pyrazolo[5,1-c][1,2,4]triazines derivatives 9c-f and 9h-p
cortex
I% - Ki (nM)a
73.6±2
10.5±1.0
77
alpha1
alpha2
alpha3
alpha5
N°
R
I% - Ki (nM)a I% - Ki (nM)a I% - Ki (nM)a I% - Ki (nM)a
3-Py
2-Py
5000
12.0±10
-
502
1236±26
32%
9c
9d
9e
9f
51
9.1±0.9
150
-
-
1-Naphtyl
2-Naphtyl
2-Thienyl
Ph
159
2298±96
236.9±18.5
329±30
152±11
88.3±8
74±6
-
-
-
-
284.8±25.
420±33
100±7
77.3
28%
2086
1080
894
660
570
501±22
-
662±60
408±33
23%
9h
9i
41.2±0.4
3000±25
632±60
2420±20
990±13
50%
3-FPh
9j
4-FPh
1111±37
40%
9k
9l
3-ClPh
3-BrPh
3-CF3Ph
4-OCH3Ph
4-CH3Ph
65.6
38.0±8
7.2
1117±8
144±16
-
9m
9n
9o
9p
21
>5000
-
6.5±0.6
-
1609
32%
-
-
-
-
a Percent inhibition values of specific [3H]Ro15-1788 binding at 10 M concentration and Ki values are means ±SEM of five determinations.

For those compounds showing binding recognition, the investigation continued in the evaluation of
their n subtypes selectivity (1, 2, 3, 5). While compound 9d showed a comparable affinity
value on 1 and 2 in nanomolar range (Ki = 9.1±0.9 nM and 12.0±10 nM respectively) and shows
no affinity for 5, it is noteworthy that compounds 9c, 9k-n bind preferentially the alpha1 subtype,
which generally reflected the binding on cortex. In particular compounds 9m and 9n display a
marked 1 subtype selectivity with respect to 2 subtype and a lower selectivity with respect to the
other 3- and 5-subtypes. Finally, compound 9h, although showed 2 binding affinity value (Ki)
of 41.2 nM, possessed moderate 1 and 5 subtypes selectivity, of about 7-folds and 16-folds
respectively (Ki 1 = 284.8 nM, Ki 5 = 662.6 nM).
The affinity values of PP and PT derivatives were tabulated in Table 3, 4c-e, A-D in column 2 and
compounds 9c-e, k-n in column 3, in order to highlight which could be the best pharmacophore.
The type of substituent (aryl or heteroaryl ring) on the byciclic system (position 3 for pyrazolo[1,5-
a]pyrimidines and the position 8 for pyrazolo[5,1-c][1,2,4]triazines), seems to have the same
influence on the binding of the two series of compounds, as demonstrated by similar affinity values.
The only exception is represented by compounds 4e and 9e bearing the 1-naphtyl group at position
3 or 8 respectively; the affinity values differ of about 8-folds, being the pyrazolotriazine 9e more
affine than 4e, (Ki= 77 nM vs Ki=599 nM). This difference of affinity could be ascribed to the extra
nitrogen atom as in compound 9e, which could result cooperative to binding with receptor protein
also considering that the presence of rigid and bulky substituent at position 3 or 8 of the two
scaffolds could shift the whole molecule in the receptor pocket.
Finally, the comparison between the PT (9k-n) and the previously published PP (A-D) bearing at
position 8 and 3 respectively a substituted phenyl reing, clearly demonstrated that there is no
difference in binding affinity, being the Ki values in the same order of magnitude (range A-D: 19.4-
95.4 nM and 9k-9n: 7.2-88.3 nM).

N
N
O
R
NH
X
N
N
H
Table 3. Comparison between 6-(pyrazol-3-yl)pyrazolo[1,5-a]pyrimidine (PP) and corresponding
3-(pyrazol-3-yl)-pyrazolo[5,1-c][1,2,4]triazines (PT)
R
Comp
4c
X
Ki (nM) cortexa
Comp
9c
X
Ki (nM) cortexa
3-Py
CH
37.3
N
73.6±2
2-Py
1-Naphtyl
4-FPh
CH
CH
CH
CH
CH
CH
14.2±1.6
599±2.5
68.3±2.1b
95.4±6c
54.5±0.8b
19.4b
N
N
N
N
N
N
10.5±1.0
77
4d
4e
A
9d
9e
88.3±8
74±6
38.0±8
7.2
9k
9l
3-ClPh
3-BrPh
3-CF3Ph
B
C
9m
9n
D
a Percent inhibition values of specific [3H]Ro15-1788 binding at 10 M concentration and Ki values are
c
means ±SEM of five determinations. bsee ref 11. see ref 9
3. Conclusions
In this research we synthesized a series of PT as aza-analogues of potent PP9,11,18 and, at the same
time, we complete this latter series; as evidenced by the binding study the substitution of CH with N
does not induce any affinity improvement.
Thus, the direct involvement to receptor interaction, by the nitrogen atom at position 2 of
pyrazolotriazine core (position 5 of pyrazolopyrimidine core) is negligible, suggesting that this
atom is not directly involved in the receptor protein anchoring in contrast with NH and the CO that

could act as ‘dual hydrogen bond point’ towards hydrogen bond donor (H1) and/or H2/A3
(hydrogen bond acceptor) site on receptor protein, already hypothesized. (Silvia Selleri et al. 1999)
Moreover the presence at position 6 of pyrazolepyrimidine scaffold of the 1H-3-pyrazole ring
results important for the interaction with receptor protein, as confirmed by the complete loss of
affinity evidenced in compound bearing the 1-imidazole or 1-pyrazole ring.
4. Experimental section
Melting points were determined in open capillary tubes on a Büchi apparatus and were uncorrected.
IR spectra were recorded (in KBr pellets in nujol mulls) on Perkin-Elmer 1420 spectrophotometer.
1H-NMR spectra were recorded with an Advance 400 Instrument (Bruker BiospinVersion 002 with
SGU, Bruker AXS Inc., Madison, WI USA). Chemical shifts are reported in  ppm using the
solvent as internal standard. Extracted were dried over Na2SO4 and the solvent were removed under
reduced pressure. Merk F-254 commercial plates (Merk-Gruppe, Darmstadt, Germany) were used
for analytical thin layer chromatography (TLC) to follow the reaction course. Silica gel 60 (Merk
70-230 mesh) was used for column chromatography. Microanalyses were performed with a Perkin-
Elmer elemental analyzer (Perkin-Elmer, Waltham, MA USA) for C, H, and N. Results within
±0.4% of the theoretical materials were commercially available. Experimental data of more
representative compounds are reported.
5.1 General procedure for the synthesis of compounds 2a-f
A mixture of ethyl-2-acetyl-3-ethoxyacrylate (55 mmoles) and (3)5-aminopyrazoles 4-substituted
(1a-f) (50 mmoles) in ethanol (100 mL) was refluxed under magnetic stirring until the starting
material disappeared in TLC. After cooling a precipitate was separated and filtered.
5.1.1 Ethyl 7-methyl-3-nitropyrazolo[1,5-a]pyrimidin-6-carboxylate, 2a
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (DMSO-d6)9.08 (s,
1H, H5); 8.80 (s, 1H, H-2); 4.36 (q, J = 7.2 Hz, 2H, CH2); 3.25 (s, 3H, CH3); 1.45 (t, J = 7.2, 3H,
CH3). Anal C, H, N.
5.1.2 Ethyl 3-amino-7-methylpyrazolo[1,5-a]pyrimidin-6-carboxylate hydrochloride, 2a’

The 3-nitroderivative 2a (1.5 g, 6.0 mmoles) was hydrogenated with H2 and 5% Pd/C. At the end of
the reaction after the filtration of catalyst the ethanol solution was added of HCl to obtain the
corresponding 3-amino hydrochloride. Yellow crystals; TLC eluent: dichloromethane /methanol
1
10:1 v/v; H-NMR (DMSO-d6) (bs, 2h, NH2 exch.); 8.91 (s, 1H, H5); 8.44 (s, 1H, H-2);
4.36 (q, J = 7.2 Hz, 2H, CH2); 3.25 (s, 3H, CH3); 1.45 (t, J = 7.2, 3H, CH3). Anal C, H, N.
5.1.3 Ethyl 3-benzyl-7-methylpyrazolo[1,5-a]pyrimidin-6-carboxylate, 2b
1
Yellowish waxy solid; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3) 8.94
(s, 1H, H-5); 8.05 (s, 1H, H-2); 7.30 (m, 5H, benzyl); 4.47 (q, J = 7.0 Hz, 2H, CH2); 4.18 (s, 2H,
CH2); 3.18 (s, 3H, CH3); 1.48 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.1.4 Ethyl 3-(pyridin-3-yl)-7-methylpyrazolo[1,5-a]pyrimidin-6-carboxylate, 2c
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)9.41 (m,
1H, Py); 9.08 (s, 1H, H-5); 8.77-8.52 (m, 3H, H-2 and Py); 7.68-7.61 (m, 1H, Py); 4.47 (q, J = 7.2
Hz, 2H, CH2); 3.27 (s, 3H, CH3); 1.48 (t, J = 7.2 Hz, 3H, CH3). Anal C, H, N.
5.1.5 Ethyl 3-(pyridin-2-yl)-7-methylpyrazolo[1,5-a]pyrimidin-6-carboxylate, 2d
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (CDCl3)9.08 (s, 1H,
H5); 8.96 (s, 1H, H-2); 8.64 (m, 1H, Py); 7.81-7.70 (m, 2H, Py); 7.18 (m, 1H, Py); 4.47 (q, J = 7.0
Hz, 2H, CH2); 3.25 (s, 3H, CH3); 1.45 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.1.6 Ethyl 3-(napht-1-yl)-7-methylpyrazolo[1,5-a]pyrimidin-6-carboxylate, 2e
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (CDCl3) 9.02 (s, 1H,
H-5); 8.05 (s, 1H, H-2); 8.01-7.88 (m, 3H, naphtalene); 7.50-7.41 (m, 4H, naphthalene); 4.45 (q, J =
7.0 Hz, 2H, CH2); 3.32 (s, 3H, CH3); 1.45 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.1.7 Ethyl 3-(napht-2-yl)-7-methylpyrazolo[1,5-a]pyrimidin-6-carboxylate, 2f
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (CDCl3) 9.09 (s, 1H,
H-5); 8.67 (s, 1H, H-2); 8.58-8.51 (m, 1H, naphtalene); 8.20 (m, 1H, naphthalene); 7.95-7.82 (m,

3H, naphthalene); 7.51-7.46 (m, 2H, naphthalene); 4.45 (q, J = 6.9 Hz, 2H, CH2); 3.25 (s, 3H, CH3);
1.45 (t, J = 6.9 Hz, 3H, CH3). Anal C, H, N.
5.1.8 Ethyl 3-(pyrrol-1-yl)-7-methylpyrazolo[1,5-a]pyrimidin-6-carboxylate, 2g
A suspension of 2a’ (10 mmoles) was suspended in dioxane (40 mL) and 1.5 mL of 2,5-
dimethoxytetrahydrofurane was added. The suspension was heated at 70 °C and after 1 hour the
reaction was complete. The addition of water and sodium acetate to neutralize the final solution, the
extraction with chloroform (25 mL x 2) and the usual work up gave a yellow solid, recrystallized
1
from ethanol. TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)8.95 (m, 1H,
(s, 1H, H-5); 8.35 (s, 1H, H-2); 7.35 (dd, J = 2.6, 2.1 Hz, 2H, pyrrole); 6.38 (dd, J = 3.5, 2.6 Hz, 2H,
pyrrole); 4.45 (q, J = 7.0 Hz, 2H, CH2); 3.21 (s, 3H, CH3); 1.45 (t, J = 7.0 Hz, 3H, CH3). Anal C, H,
N.
5.2 General procedure for the synthesis of compounds 3b-g.
Compounds 2b-g (10 mmoles) in toluene (50 mL) containing dimethylformamide-dimethyl acetale
(DMF-DMA) (20 mmoles) and catalytic amount of piperidine (1 mL) were warmed at 90 °C under
magnetic stirring. The reaction was monitored by TLC and the final solution was evaporated to
dryness obtained a solid residue that was recrystallized by suitable solvent.
5.2.1 Ethyl 3-benzyl-7-(2-dimethylaminovinyl)pyrazolo[1,5-a]pyrimidin-6-carboxylate, 3b
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)9.16 (d, J =
12.82 Hz, 1H, CH=CH); 8.91 (s, 1H, H5); 7.88 (s, 1H, H-2); 7.20 (m, 5H, benzyl); 7.01 (d, J =
12.82 Hz 1H, CH=CH); 4.35 (q, J = 6.9 Hz, 2H, CH2); 4.16 (s, 2H, CH2); 3.22 (bs, 3H, N(CH3)2);
3.06 (bs, 3H, N(CH3)2); 1.40 (t, J = 6.9 Hz, 3H, CH3). Anal C, H, N.
5.2.2
Ethyl
7-(2-dimethylaminovinyl)-3-(pyridin-3-yl)-pyrazolo[1,5-a]pyrimidin-6-
carboxylate, 3c
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (CDCl3)9.70 (d, J =
12.70 Hz, 1H, CH=CH); 9.16 (s, 1H, Py); 8.98 (s, 1H, H5); 8.50-8.41 (m, 3H, H-2 and Py); 7.40-

7.31 (m, 1H, Py); 7.08 (d, J = 12.70 Hz, 1H, CH=CH); 4.37 (q, J = 7.0 Hz, 2H, CH2); 3.30 (bs, 3H,
N(CH3)2); 3.08 (bs, 3H, N(CH3)2); 1.40 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.2.3
Ethyl
7-(2-dimethylaminovinyl)-3-(pyridin-2-yl)-pyrazolo[1,5-a]pyrimidin-6-
carboxylate, 3d
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)9.75 (d, J =
12.74 Hz, 1H, CH=CH); 9.01 (s, 1H, H5); 8.81 (s, 1H, H-2); 8.63-8.52 (m, 2H, Py); 7.79-7.71 (m,
1H, Py); 7.15 (m, 1H, Py); 7.11 (d, J = 12.74 Hz, 1H, CH=CH); 4.39 (q, J = 7.0 Hz, 2H, CH2); 3.31
(bs, 3H, N(CH3)2); 3.09 (bs, 3H, N(CH3)2); 1.42 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.2.4 Ethyl 7-(2-dimethylaminovinyl)-3-(napht-1-yl)-pyrazolo[1,5-a]pyrimidin-6-carboxylate,
3e
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)9.80 (d, J =
12.65 Hz, 1H, CH=CH,); 8.94 (s, 1H, H5); 8.34 (s, 1H, H-2); 8.04 (m, 1H, naphtalene); 7.93-7.84
(m, 2H, naphtalene); 7.70 (m, 1H, naphthalene); 7.61-7.40 (m, 3H, naphthalene); 7.12 (d, J = 12.65
Hz 1H, CH=CH,); 4.39 (q, J = 7.0 Hz, 2H, CH2); 3.32 (bs, 3H, N(CH3)2); 3.13 (bs, 3H, N(CH3)2);
1.41 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.2.5 Ethyl 7-(2-dimethylaminovinyl)-3-(napht-2-yl)-pyrazolo[1,5-a]pyrimidin-6-carboxylate,
3f
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)10.02 (d, J
= 12.74 Hz, 1H, CH=CH,); 9.04 (s, 1H, H5); 8.53 (m, 2H, H-2 and naphtalene); 8.20 (m, 1H,
naphtalene); 7.93-7.84 (m, 3H, naphtalene); 7.50-7.45 (m, 2H, naphthalene); 7.05 (d, J = 12.74 Hz,
1H, CH=CH,); 4.45 (q, J = 7.0 Hz, 2H, CH2); 3.31 (bs, 3H, N(CH3)2); 3.11 (bs, 3H, N(CH3)2); 1.46
(t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.2.6 Ethyl 7-(2-dimethylaminovinyl)-3-(pyrrol-1-yl)-pyrazolo[1,5-a]pyrimidin-6-carboxylate,
3g
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)9.71 (d, J =
12.70 Hz, 1H, CH=CH,); 8.89 (s, 1H, H5); 8.17 (m, 1H, H-2); 7.29 (dd, J = 2.6, 2.1 Hz, 2H,

pyrrole); 7.22 (d, J = 12.70 Hz, 1H, CH=CH,); 6.35 (dd, J = 3.5, 2.6 Hz, 2H, pyrrole); 4.36 (q, 2H,
CH2); 3.29 (bs, 3H, N(CH3)2); 3.09 (bs, 3H, N(CH3)2); 1.40 (t, 3H, CH3). Anal C, H, N.
5.3 General procedure for the synthesis of compounds 4b-g.
Hydrazine hydrate (10 mmoles) was added to a solution of ethyl 7-(2-dimethylaminovinyl)pyrazolo
[1,5-a]pyrimidine-6-carboxylate 3-substituted (3b-g) (10 mmoles) and sodium acetate (24 mmoles)
in acetic acid (50 mL). The mixture was refluxed under magnetic stirring monitoring by TLC, and
until the solution became from yellow to colorless. After cooling or by addition of water a
precipitate was recovered and filtered.
5.3.1 3-Benzyl-4,7-dihydro-6-(1’H-pyrazolo-3’-yl)pyrazolo[1,5-a]pyrimidin-7-one, 4b
White crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (DMSO-d6)12.62 (bs,
1H, NH, exchange); 8.38 (s, 1H, H-5); 7.75 (s, 1H, H-2); 7.67-7.16 (m, 6H, benzyl and H-5’
pyrazole); 6.78 (m, 1H, H-4’ pyrazole); 3.97 (s, 2H, CH2). LC-MS: 291.9 [M+H]+. Anal C, H, N.
5.3.2 4,7-dihydro-6-(1’H-pyrazolo-3’-yl)-3-(pyridin-3-yl)pyrazolo[1,5-a]pyrimidin-7-one, 4c
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (DMSO-d6)12.85
(bs, 1H, NH, exchange); 8.91 (m, 1H, Py); 8.54 (m, 1H, Py); 8.40 (s, 1H, H-5); 8.38 (s, 1H, H-2);
8.11-8.07 (m, 1H, Py); 7.73 (m, 1H, H-5’ pyrazole); 7.58-7.49 (m, 1H, Py); 6.92 (m, 1H, H-4’
pyrazole). LC-MS: 278.8 [M+H]+. Anal C, H, N.
5.3.3 4,7-dihydro-6-(1’H-pyrazolo-3’-yl)-3-(pyridin-2-yl)pyrazolo[1,5-a]pyrimidin-7-one, 4d
1
Yellowish crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (DMSO-d6)12.75
(bs, 1H, NH, exchange); 12.35 (bs, 1H, NH exchange); 8.66 (m, 2H, H-2 and H-5); 8.54-8.49 (m,
1H, Py); 7.88 (m, 2H, Py); 7.74 (m, 1H, H-5’ pyrazole); 7.25 (m, 1H, Py); 6.91 (m, 1H, H-4’
pyrazole). LC-MS: 278.7 [M+H]+. Anal C, H, N.
5.3.4
4,7-dihydro-3-(napht-1-yl)-6-(1’H-pyrazolo-3’-yl)pyrazolo[1,5-a]pyrimidin-7-one, 4e
White crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (DMSO-d6)12.85 (bs,
1H, NH, exchange); 12.60 (bs, 1H, NH, exchange); 8.28 (s, 1H, H-5); 8.19 (s, 1H, H-2); 8.10-7.52

(m, 8H, naphtalene and H-5’ pyrazole); 6.91 (m, 1H, H-4’ pyrazole). LC-MS: 328.0 [M+H]+. Anal
C, H, N.
5.3.5 4,7-dihydro-3-(napht-2-yl)-6-(1’H-pyrazolo-3’-yl)pyrazolo[1,5-a]pyrimidin-7-one, 4f
White crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (DMSO-d6)12.72 (bs,
1H, NH, exchange); 8.43 (s, 1H, H-5); 8.38 (s, 1H, H-2); 8.17 (d, J = 0.81 Hz, 1H, H-5’pyrazole);
8.06-7.52 (m, 7H, naphtalene); 6.92 (d, J = 0.81 Hz, 1H, H-4’pyrazole). LC-MS: 327.9 [M+H]+.
Anal C, H, N.
5.3.6 4,7-dihydro-6-(1’H-pyrazolo-3’-yl)-3-(pyrrol-1-yl)pyrazolo[1,5-a]pyrimidin-7-one, 4g
White crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (DMSO-d6)12.82 (bs,
1H, NH, exchange); 8.31 (s, 1H, H-5); 8.20 (s, 1H, H-2); 7.71 (d, J = 1.59 Hz, 1H, H-5’ pyrazole);
7.08 (m, 2H, pyrrole); 6.89 (d, J = 1.59 Hz, 1H, H-4’ pyrazole); 6.30 (m, 2H, pyrrole). LC-MS:
268.3 [M+H]+. Anal C, H, N.
5.4 General procedure for the synthesis of compounds A and B.
A suspension of 50% sodium hydride in mineral oil was added to anhydrous toluene (200 mL) in 1 l
round bottomed flask. After addition of t-amyl alcohol the mixture was heated at 70 °C and a
solution of the ethyl pyrazol-1-yl acetate or ethyl imidazole-1-yl acetate (162 mmoles, 25g) and
ethyl formate (180 mmoles, 15 mL) in anhydrous toluene (50 mL) was added dropwise during an
hours. After 6 hours of stirring and heating at 70-80 °C the resulting solid was left to stand
overnight. The mixture was then treated with ice-water (400 mL) and the aqueous phase was
separated and washed with diethyl ether. Acidification with HCl conc. causes the separation of oil
which was extracted with diethyl ether. The extracted were dried over anhydrous sodium sulphate
and evaporated to dryness, obtaining a solid.
5.4.1 Ethyl 2-(pyrazol-1’-yl)-2-formylacetate A
White crystals from cyclohexane; mp 78-79 °C; yield, 62%; TLC eluent: dichloromethane
/methanol 10:1 v/v; 1H-NMR (DMSO-d6) 8.54 (d, J = 2.5 Hz, 1H, H-5); 7.76 (s, 1H, CH); 7.60

(d, J= 1.8 Hz, 1H, H-3); 6.38 (dd, J = 2.4, 1.8 Hz, 1H, H-4); 4.30 (q, J = 7.0 Hz, 2H, CH2); 1.34 (t, J
= 7.0 Hz, 3H, CH3). Anal C, H, N.
5.4.2 Ethyl 2-(imidazol-1’-yl)-2-formylacetate B
White crystals from ethanol; mp 160-161 °C; yield, 78%; TLC eluent: dichloromethane/methanol
1
10:1 v/v; H-NMR (DMSO-d6) 8.73 (s, 1H, CH); 8.21 (s, 1H, H-2); 7.10-7.06 (m, 2H, H-4 and
H-5); 3.80 (q, J = 7.0 Hz, 2H, CH2); 0.90 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.5 General synthesis of compounds 5a, b, 6a, b.
11,13
A suspension of 3(5)-amino-4-(thien-2-yl)pyrazole (1h) or 3(5)-amino-4-phenylpyrazole (1i)
(10 mmoles) and ethyl 2-(pyrazol-1’-yl)-2-formylacetate (A) or ethyl 2-(imidazol-1’-yl)-2-
formylacetate (B) (10 mmoles) in dyglime (20 mL) was refluxed under magnetic stirring until the
starting material disappeared. The precipitate was collected by filtration from the reaction mixture
and recrystallized by suitable solvent, obtaining compounds 5a, 5b, 6a and 6b respectively.
5.5.1 4,7-dihydro-6-(pyrazol-1-yl)-3-(thien-2-yl)-pyrazolo[1,5-a]pyrimidin-7-one, 5a
White crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (DMSO-d6)bs,
1H, NH, exchange); 8.97 (s, 1H, H-5); 8.43 (d, J = 2.73 Hz, 1H, H-5’ pyrazole); 8.31 (s, 1H, H-2);
7.91 (m, 1H, thienyl); 7.78 (d, J = 1.46 Hz, 1H, H-3’ pyrazole); 7.65 (m, 1H, thienyl); 7.56 (m, 1H,
thienyl); 6.54 (m, 1H, H-4’pyrazole). Anal C, H, N.
5.5.2 4,7-dihydro-3-phenyl-6-(pyrazol-1-yl)pyrazolo[1,5-a]pyrimidin-7-one, 5b
White crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (DMSO-
d6)bs, 1H, NH, exchange);8.37 (s, 1H, H-5); 8.32 (s, 1H, H-2); 8.28 (d, J = 2.36 Hz, 1H,
H-5’pyrazole); 7.72 (d, J = 1.75 Hz, 1H, H-3’ pyrazole); 7.67 (m, 2H, Ph); 7.55-7.47 (m, 2H, Ph);
7.37 (m, 1H, Ph); 6.52 (m, 1H, H-4’ pyrazole). Anal C, H, N.
5.5.3 4,7-dihydro-6-(imidazol-1-yl)-3-(thien-2-yl)-pyrazolo[1,5-a]pyrimidin-7-one, 6a
Yellowish crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (DMSO-
d6)bs, 1H, NH, exchange);  8.74 (s, 1H, H-2’imidazole); 8.27 (s, 1H, H-5); 8.21 (s, 1H,

H-2); 7.85 (m, 1H, thienyl); 7.72 (d, J = 1.56 Hz, 1H, H-5’imidazole); 7.69 (m, 1H, thienyl); 7.56
(m, 1H, thienyl); 7.48 (d, J = 1.56 Hz, 1H, H-4’ imidazole). Anal C, H, N.
5.5.4 4,7-dihydro-3-phenyl-6-(imidazol-1-yl)pyrazolo[1,5-a]pyrimidin-7-one, 6b
White crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (DMSO-
d6)bs, 1H, NH, exchange); 8.98 (s, 1H, H-2’imidazole); 8.35 (s, 1H, H-5); 8.26 (s, 1H,
H-2); 7.99 (m, 2H, Ph); 7.83 (d, J = 1.42 Hz, 1H, H-5’ imidazole); 7.60 (d, J = 1.42 Hz, 1H, H-4’
imidazole); 7.44-7.36 (m, 2H, Ph); 7.15 (m, 1H, Ph). Anal C, H, N.
5.6 General procedure for the synthesis of compounds 7c-f, 7h-p.
The suitable 4-substituted-5-aminopyrazoles (1c-f, 1h-p) (20 mmoles) were diazotized as usual and
the solution of diazonium salt was treated with of sodium acetate (24 mmoles) at room temperature
and stirred until to complete dissolution. At this solution was then added ethyl acetoacetate (20.0
mmoles) in ethanol and stirred for 1 hour at room temperature. The final compounds were
recovered by filtration after addition of water or by extraction if a precipitate was not formed.
Starting from 1f, in this reaction condition, a byproduct is formed and identified as 1H-
Benzo[h]pyrazolo[3,4-c]cinnoline, 10. The unambiguous synthesis of this latter was obtained as
described below.
5.6.1 Ethyl 4-methyl-8-(pyridin-3-yl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7c
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)9.41 (d, J =
2.0 Hz, 1H, Py); 8.77 (s, 1H, H-2); 8.70 (dd, J = 7.8, 1.7 Hz, 1H, Py); 8.22 (dd, J = 4.9, 1.7 1H, Py);
7.49 (dd, J = 7.8, 4.9, 1H, Py); 4.60 (q, J = 7.0 Hz, 2H, CH2); 3.27 (s, 3H, CH3); 1.60 (t, J = 7.0 Hz,
3H, CH3). Anal C, H, N.
5.6.2 Ethyl 4-methyl-8-(pyridin-2-yl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7d
1
Yellow crystals; TLC eluent: toluene/ethyl acetate/acetic acid 8:2:1 v/v/v; H-NMR (DMSO-d6)
9.16 (s, 1H, H-2); 8.71 (d, J = 5.0 Hz, 1H, Py); 8.64 (d, J = 8.0 Hz, 1H, Py); 8.02 (dd, J = 8.0, 7.7
Hz, 1H, Py); 7.40 (dd, J = 7.7, 5.0 Hz, 1H, Py); 4.51 (q, J = 7.0 Hz, 2H, CH2); 3.13 (s, 3H, CH3);
1.42 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.

5.6.3 Ethyl 4-methyl-8-(napht-1-yl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7e
1
Yellow crystals; TLC eluent: toluene/ethyl acetate 8:2 v/v; H-NMR (CDCl3) 8.68 (s, 1H, H-2);
8.08 (d, J = 7.5 Hz, 1H, naphthalene); 7.98 (d, J = 7.5 Hz, 2H, naphthalene); 7.88 (d, J = 7.5 Hz,
1H, naphthalene); 7.68-7.46 (m, 3H, naphthalene); 4.62 (q, J = 7.0 Hz, 2H, CH2); 3.26 (s, 3H, CH3);
1.58 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.4 Ethyl 4-methyl-8-(napht-2-yl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7f
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; 1H-NMR (CDCl3) 8.85 (s, 1H,
naphthalene); 8.80 (s, 1H, H-2); 8.30 (d, J = 7.5 Hz, 1H, naphthalene); 8.00-7.90 (m, 3H,
naphthalene); 7.55-7.48 (m, 2H, naphthalene); 4.60 (q, J = 7.0 Hz, 2H, CH2); 3.25 (s, 3H, CH3);
1.55 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.5 Ethyl 4-methyl-8-(thien-2-yl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7h
1
Orange crystals; TLC eluent: toluene/ethyl acetate 8:2 v/v; H-NMR (DMSOd6) 9.06 (s, 1H, H-
2); 7.85 (d, J = 2.8 Hz, 1H, thienyl); 7.66 (d, J = 4.8 Hz, 1H, thienyl); 7.24 (m, 1H, thienyl); 4.48 (q,
J = 7.0 Hz, 2H, CH2); 3.08 (s, 3H, CH3); 1.41 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.6 Ethyl 4-methyl-8-phenylpyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7i
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; ) 9.09 (s, 1H, H-2); 8.24 (m,
2H, phenyl); 7.49 (m, 2H, phenyl); 7.34 (m, 1H, phenyl); 4.43 (q, J = 7.0 Hz, 2H, CH2); 3.08 (s, 3H,
CH3); 1.41 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.7 Ethyl 4-methyl-8-(3-fluorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7j
1
Dark yellow crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; H-NMR (DMSO-d6) 9.20 (s,
1H, H-2); 8.19 (m, 2H, H-2’ and H-4’ Ph); 7.60 (m, 1H, H-5’ Ph); 7.21 (m, 1H, H-6’ Ph); 4.50 (q, J
= 7.0 Hz, 2H, CH2); 3.10 (s, 3H, CH3); 1.41 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.8 Ethyl 4-methyl-8-(4-fluorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7k

1
Dark yellow crystals; TLC eluent: dichloromethane/methanol 10:2 v/v; H-NMR (DMSO-d6)
9.15 (s, 1H, H-2); 8.35 (m, 2H, H-3’ and H-5’ Ph); 7.40 (m, 2H, H-2’ and H-6’ Ph); 4.50 (q, J = 7.0
Hz, 2H, CH2); 3.10 (s, 3H, CH3); 1.41 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.9 Ethyl 4-methyl-8-(3-chlorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7l
Yellow crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; 1H-NMR (DMSO-d6) 9.20 (s, 1H, H-
2); 8.40 (d, J = 1.5 Hz, 1H, H-2’ Ph); 8.28 (dd, J = 7.0, 1.5 Hz, 1H, H-4’ Ph); 7.58 (t, J = 7.0 Hz,
1H, H-5’ Ph); 7.45 (dd, J = 7.0, 1.5 Hz, 1H, H-6’ Ph); 4.50 (q, J = 7.0 Hz, 2H, CH2); 3.10 (s, 3H,
CH3); 1.41 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.10 Ethyl 4-methyl-8-(3-bromophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7m
1
Yellow crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3) 8.70 (s, 1H, H-2);
8.45 (d, J = 1.5 Hz, 1H, H-2’ Ph); 8.20 (dd, J = 8.0, 1.5 Hz, 1H, H-4’ Ph); 7.52 (dd, J = 8.0, 1.5 Hz,
1H, H-6’ Ph); 7.40 (t, J = 8.0 Hz, 1H, H-5’ Ph); 4.60 (q, J = 7.0 Hz, 2H, CH2); 3.25 (s, 3H, CH3);
1.53 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.11 Ethyl 4-methyl-8-(3-trifluoromethylphenyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate,
7n
1
Red crystals; TLC eluent: toluene/ethyl acetate/acetic acid 8:2:1 v/v/v; H-NMR (CDCl3) 8.75
(s, 1H, H-2); 8.55 (m, 1H, H-2’ Ph); 8.48 (m, 1H, H-5’ Ph); 7.68 (m, 2H, H-4’ and H-6’ Ph); 4.65
(q, J = 7.0 Hz, 2H, CH2); 3.28 (s, 3H, CH3); 1.55 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.12 Ethyl 4-methyl-8-(4-methoxyphenyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7o
1
Yellow crystals; TLC eluent toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3) 8.50 (s, 1H, H-2);
8.08 (d, J = 8.0 Hz, 2H, H-2’ and H-6’ Ph); 7.28 (m, 2H, H-3’ and H-5’ Ph); 4.50 (q, J = 7.0 Hz,
2H, CH2); 3.80 (s, 3H, 4’-OCH3Ph); 3.15 (s, 3H, CH3); 1.45 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.6.13 Ethyl -4-methyl-8-(4-methylphenyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 7p
1
Dark yellow crystals; TLC eluent toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3) 8.55 (s, 1H,
H-2); 8.08 (d, J = 8.0 Hz, 2H, H-2’ and H-6’ Ph); 7.28 (m, 2H, H-3’ and H-5’ Ph); 4.50 (q, J = 7.0

Hz, 2H, CH2); 3.15 (s, 3H, CH3); 2.35 (s, 3H, 4’-CH3Ph); 1.45 (t, J = 7.0 Hz, 3H, CH3). Anal C, H,
N.
5.7 General procedure for the synthesis of compounds 8c-f, 8h-p.
Compounds 7c-f, 7h-p (10 mmoles) in toluene (50 mL) containing dimethylformamide-dimethyl
acetale (DMF-DMA) (20 mmoles) and catalytic amount of piperidine (1 mL) were warmed at 90 °C
under magnetic stirring. The reaction was monitored by TLC and the final solution was evaporated
to dryness obtaining a solid residue or the precipitate was filtered and recrystallized by suitable
solvent.
5.7.1
Ethyl
4-(2-dimethylaminovinyl)-8-(pyridin-3-yl)pyrazolo[5,1-c][1,2,4]triazin-3-
carboxylate, 8c
Yellow crystals; TLC eluent: choloform/methanol 10:1 v/v; 1H-NMR (CDCl3) 9.75 (d, J = 12.74
Hz, 1H, CH=CH,); 9.30 (s, 1H, H-2); 8.75 (dd, J = 7.8, 1.7 Hz, 1H, Py); 8.50 (m, 2H, Py); 7.45 (dd,
J = 7.8, 4.9, 1H, Py); 7.00 (d, J= 12.74 Hz, 1H, CH=CH,); 4.54 (q, J = 7.0 Hz, 2H, CH2); 3.35 (s,
3H, N(CH3)2); 3.15 (s, 3H, N(CH3)2); 1.51 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.7.2
Ethyl
4-(2-dimethylaminovinyl)-8-(pyridin-2-yl)pyrazolo[5,1-c][1,2,4]triazin-3-
carboxylate, 8d
1
Yellow crystals; TLC eluent: choloform/methanol 10:1 v/v; H-NMR (CDCl3) 10.99 (s, 1H, H-
2); 9.91 (dd, J = 5.0 Hz, 1H, Py); 8.46 (d, 1H, CH=CH, Jtrans = 12.74 Hz); 8.39 (dd, 1H, Py); 8.31
(dd, 1H, Py); 7.58 (dd, 1H, Py); 6.80 (d, 1H, CH=CH, Jtrans = 12.74 Hz); 4.54 (q, 2H, CH2); 3.72 (s,
3H, N(CH3)2); 3.46 (s, 3H, N(CH3)2); 1.51 (t, 3H, CH3). Anal C, H, N.
5.7.3
Ethyl
4-(2-dimethylaminovinyl)-8-(napht-1-yl)pyrazolo[5,1-c][1,2,4]triazin-3-
carboxylate, 8e
1
Dark yellow crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3) 9.85 (d, J =
12.74 Hz, 1H, CH=CH); 8.45 (s, 1H, H-2); 8.15 (d, J = 7.5 Hz, 1H, naphthalene); 7.98-7.85 (m, 3H,
naphthalene); 7.68-7.46 (m, 3H, naphthalene); 6.81 (d, J = 12.74 Hz, 1H, CH=CH,); 4.25 (q, J =

7.0 Hz, 2H, CH2); 3.40 (s, 3H, N(CH3)2); 3.20 (s, 3H, N(CH3)2); 1.37 (t, J = 7.0 Hz, 3H, CH3). Anal
C, H, N.
5.7.4
Ethyl
4-(2-dimethylaminovinyl)-8-(napht-2-yl)pyrazolo[5,1-c][1,2,4]triazin-3-
carboxylate, 8f
1
Brown crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3) 9.80 (d, J= 12.74
Hz, 1H, CH=CH); 8.90 (s, 1H, naphthalene); 8.58 (s, 1H, H-2); 8.30 (d, J = 7.5 Hz, 1H,
naphthalene); 7.98-7.85 (m, 3H, naphthalene); 7.50 (m, 2H, naphthalene); 6.95 (d, J = 12.74 Hz,
1H, CH=CH); 4.55 (q, J = 7.0 Hz, 2H, CH2); 3.40 (s, 3H, N(CH3)2); 3.15 (s, 3H, N(CH3)2); 1.50 (t,
J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.7.5 Ethyl 4-(2-dimethylaminovinyl)-8-(thien-2-yl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate,
8h
Dark yellow crystals; TLC eluent: toluene/ethyl acetate/acetic acid 8:2:1 v/v/v; 1H-NMR (CDCl3)
9.68 (d, J = 12.74 Hz, 1H, CH=CH); 8.76 (s, 1H, H-2); 7.75 (d, J = 2.8 Hz, 1H, thienyl); 7.55 (d, J =
4.8 Hz,1H, thienyl); 7.18 (m, 1H, thienyl); 6.81 (d, J = 12.74 Hz, 1H, CH=CH); 4.38 (q, J = 7.0 Hz,
2H, CH2); 3.65 (m, 6H, N(CH3)2); 1.37 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.7.6 Ethyl 4-(2-dimethylaminovinyl)-8-phenylpyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 8i
1
Yellow crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (CDCl3)9.75 (d J=
12.74 Hz, 1H, CH=CH); 8.45 (s, 1H, H-2); 8.20 (d, J = 7.2 Hz, 2H, Ph); 7.45 (t, J = 7.2 Hz, 2H,
Ph); 7.28 (t, J = 7.2 Hz, 1H, Ph); 6.85 (d, J = 12.74 Hz, 1H, CH=CH); 4.60 (q, J = 7.0 Hz, 2H,
CH2); 3.31 (bs, 3H, N(CH3)2); 3.09 (bs, 3H, N(CH3)2); 1.42 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.7.7
Ethyl
4-(2-dimethylaminovinyl)-8-(3-fluorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-
carboxylate, 8j
1
Yellow crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3)  9.80 (d, J = 12.74
Hz, 1H, CH=CH); 8.45 (s, 1H, H-2); 8.09 (m, 2H, H-2’ and H-4’ Ph); 7.45 (m, 1H, H-5’ Ph); 7.12
(d, J = 12.74 Hz, 1H, CH=CH,); 7.00 (m, 1H, H-6’ Ph); 4.50 (q, J = 7.0 Hz, 2H, CH2); 3.60 (m, 6H,
N(CH3)2; 1.50 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.

5.7.8
Ethyl
4-(2-dimethylaminovinyl)-8-(4-fluorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-
carboxylate, 8k
1
Dark yellow crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3)  9.78 (d, J =
12.74 Hz, 1H, CH=CH,); 8.39 (s, 1H, H-2); 8.24 (m, 2H, H-3’ and H-5’ Ph); 7.20-705 (m, 3H, H-2’
and H-6’ Ph, CH=CH); 4.51 (q, J = 7.0 Hz, 2H, CH2); 3.36 (s, 3H, N(CH3)2); 3.14 (s, 3H, N(CH3)2);
1.50 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.7.9
Ethyl
8-(3-chlorophenyl)-4-(2-dimethylaminovinyl)pyrazolo[5,1-c][1,2,4]triazin-3-
carboxylate, 8l
Yellow crystals; TLC eluent: chloroform/methanol 10:1 v/v; 1H-NMR (CDCl3)  9.80 (d, J = 12.74
Hz, 1H, CH=CH,); 8.45 (d, J = 1.5 Hz, 1H, H-2’ Ph); 8.30 (s, 1H, H-2); 8.15 (dd, J = 7.0, 1.5 Hz,
1H, H-4’ Ph); 7.50 (t, J = 7.0 Hz, 1H, H-5’ Ph); 7.25 (dd, J = 7.0, 1.5 Hz, 1H, H-6’ Ph); 7.12 (d, J
= 12.74 Hz, 1H, CH=CH,); 4.51 (q, J = 7.0 Hz, 2H, CH2); 3.36 (s, 3H, N(CH3)2); 3.14 (s, 3H,
N(CH3)2); 1.50 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.
5.7.10 Ethyl 8-(3-bromophenyl)-4-(2-dimethylaminovinyl)pyrazolo[5,1-c][1,2,4]triazin-
3carboxylate, 8m
Yellow crystals; TLC eluent: chloroform/methanol 10:1 v/v; 1H-NMR (CDCl3)  9.65 (d, J = 12.74
Hz, 1H, CH=CH,); 8.47 (d, J = 1.5 Hz, 1H, H-2’ Ph); 8.38 (s, 1H, H-2); 8.15 (dd, J = 8.0, 1.5 Hz,
1H, H-4’ Ph); 7.39-7.31 (m, 2H, H-5’ and H-6’ Ph); 6.85 (d, J = 12.74 Hz, 1H, CH=CH,); 4.51 (q,
J = 7.0 Hz, 2H, CH2); 3.34 (s, 3H, N(CH3)2); 3.10 (s, 3H, N(CH3)2); 1.50 (t, J = 7.0 Hz, 3H, CH3).
Anal C, H, N.
5.7.11 Ethyl 4-(2-dimethylaminovinyl)-8-(3-trifluoromethylphenyl)pyrazolo[5,1-
c][1,2,4]triazin-3-carboxylate, 8n
1
Yellow crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3) 9.70 (d, J = 12.74
Hz, 1H, CH=CH,); 8.50 (m, 3H, H-2, H-2’ and H-4’ Ph); 7.70 (m, 2H, H-5’ and H-6’ Ph); 7.10 (d, J
= 12.74 Hz, 1H, CH=CH,); 4.50 (q, J = 7.0 Hz, 2H, CH2); 3.38 (s, 3H, N(CH3)2); 3.18 (s, 3H,
N(CH3)2); 1.50 (t, J = 7.0 Hz, 3H, CH3). Anal C, H, N.

5.7.12 Ethyl 4-(2-dimethylaminovinyl)-8-(4-methoxyphenyl)pyrazolo[5,1-c][1,2,4]triazin-3-
carboxylate, 8o
Red crystals; TLC eluent: toluene/ethyl acetate 8:3 v/v; 1H-NMR (CDCl3) 9.70 (d, J = 12.74 Hz,
1H, CH=CH); 8.40 (s, 1H, H-2); 8.20 (d, J = 7.5 Hz, 2H, H-2’ and H-6’ Ph); 7.00 (d, J = 7.5 Hz,
2H, H-3’ and H-5’ Ph); 6.80 (d, J = 12.74 Hz, 1H, CH=CH); 4.50 (q, J = 7.0 Hz, 2H, CH2); 3.80 (s,
3H,OCH3); 3.38 (s, 3H, N(CH3)2); 3.18 (s, 3H, N(CH3)2); 1.50 (t, J = 7.0 Hz, 3H, CH3). Anal C, H,
N.
5.7.13 Ethyl 4-methyl-8-(4-methylphenyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate, 8p
1
Dark yellow crystals; TLC eluent toluene/ethyl acetate 8:3 v/v; H-NMR (CDCl3) 9.70 (d, J =
12.74 Hz, 1H, CH=CH); 8.55 (s, 1H, H-2); 8.08 (d, J = 8.0 Hz, 2H, H-2’ and H-6’ Ph); 7.28 (m, 2H,
H-3’ and H-5’ Ph); 6.80 (d, J = 12.74 Hz, 1H, CH=CH); 4.50 (q, J = 7.0 Hz, 2H, CH2); 3.38 (s, 3H,
N(CH3)2); 3.18 (s, 3H, N(CH3)2); 2.35 (s, 3H, 4’-CH3Ph); 1.50 (t, J = 7.0 Hz, 3H, CH3). Anal C, H,
N.
5.8 General procedure for the synthesis of compounds 9c-f, 9h-p.
A solution of ethyl 4-(2-dimethylaminovinyl)pyrazolo[5,1-c][1,2,4]triazin-3-carboxylate 8-
substituted (7c-f, 7h-p) (10 mmoles) in acetic acid (50 mL) was added of sodium acetate (24
mmoles) and hydrazine hydrate (10 mmoles) The mixture was refluxed under magnetic stirring
monitoring by TLC until the disappeared of starting material. After cooling or by addition of water
a precipitate was recovered and filtered.
5.8.1 1,4-dihydro-3-(1’H-pyrazolo-3-yl)-8-(pyridin-3-yl)pyrazolo[5,1-c][1,2,4]triazin-4-one, 9c
1
Yellow crystals; TLC eluent: chloroform/methanol 10:1 v/v; H-NMR (DMSO-d6) 9.00 (s,1H,
Py); 8.48 (m, 2H, H-2 and Py); 8.22 (m, 1H, Py); 7.70( m, 1H, H-5’ pyz); 7.52 (m, 1H, Py); 6.90
(m, 1H, H-4’). LC-MS: 279.9 [M+H]+. Anal C, H, N.
5.8.2 1,4-dihydro-3-(1’H-pyrazolo-3-yl)-8-(pyridin-2-yl)pyrazolo[5,1-c][1,2,4]triazin-4-one, 9d
1
Yellow crystals; TLC eluent: ethyl acetate/methanol 10:2 v/v; H-NMR (DMSO-d6) 9.06 (s, 1H,
H-2); 8.72-8.68 (m, 2H, Py); 8.35 (d, J = 7.2 Hz, 1H, H-5’ pyz); 8.02 (m, 1H, Py); 7.41 (m, 1H, Py);

7.12 (d, J = 7.2 Hz, 1H, H-4’ pyz); 6.39 (s, 2H, NH exchange). LC-MS: 279.8 [M+H]+. Anal C, H,
N.
5.8.3 1,4-dihydro-8-(napht-1-yl)-3-(1’H-pyrazolo-3-yl)pyrazolo[5,1-c][1,2,4]triazin-4-one, 9e
Brown crystals; TLC eluent: chloroform/methanol 10:1 v/v; 1H-NMR (DMSO-d6) 14.10 (bs 1H,
NH, exchange); 13.20 (bs, 1H, NH, exchange); 8.28 (s, 1H, H-2); 8.02-7.89 (m, 3H, naphthalene);
7.63-7.52 (m, 5H, naphthalene and H-5’); 7.02 (m, 1H, H-4’). LC-MS: 328.9 [M+H]+. Anal C, H,
N.
5.8.4 1,4-dihydro-8-(napht-2-yl)-3-(1’H-pyrazolo-3-yl)pyrazolo[5,1-c][1,2,4]triazin-4-one, 9f
1
Yellow-brown crystals; TLC eluent: chloroform/methanol 10:1 v/v; H-NMR (DMSO-d6) 8.56
(s, 1H, H-2); 8.26 (s, 1H, naphthalene); 8.02-7.86 (m, 4H, naphthalene); 7.73 (m, 1H, H-5’); 7.02
(m, 1H, H-4’). LC-MS: 329.0 [M+H]+. Anal C, H, N.
5.8.5 1,4-dihydro-3-(1’H-pyrazolo-3-yl)-8-(thien-2-yl)pyrazolo[5,1-c][1,2,4]triazin-4-one, 9h
Brown crystals; TLC eluent: chloroform/methanol 10:1 v/v; 1H-NMR (DMSO-d6)12.50 (bs, 1H,
NH, exchange); 8.23 (s, 1H, H-2); 7.54 (m, 2H, H-5’ and thienyl); 7.36 (m, 1H, thienyl); 7.07 (m,
1H, thienyl); 6.89 (m, 1H, H-4’). LC-MS: 284.9 [M+H]+. Anal C, H, N.
5.8.6 1,4-dihydro-3-(1’H-pyrazolo-3’-yl)-8-phenylpyrazolo[5,1-c][1,2,4]triazin-4-one, 9i
1
Yellowish crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (DMSO-d6)12.85
(bs, 1H, NH, exchange); 8.38 (s, 1H, H-2); 8.25 (m, 2H, H2’ and H-6’ Ph); 7.50 (bs, 1H, H-5’ pyz);
7.38 (m, 2H, H3’ and H-5’ Ph); 7.25 (m, 1H, H-4’ Ph); 6.88 (bs 1H, H-4’ pyz). LC-MS: 278.8
[M+H]+. Anal C, H, N.
5.8.7 1,4-dihydro-8-(3-fluorophenyl)-3-(1’H-pyrazolo-3-yl)pyrazolo[5,1-c][1,2,4]triazin-4-one,
9j
1
Red-brown crystals; TLC eluent: chloroform/methanol 10:0.5 v/v; H-NMR (DMSO-d6) 12.85
(bs, 1H, NH, exchange); 8.44 (s, 1H, H-2); 8.15 (m, 1H, H-2’ Ph); 8.00 (m, 1H, H-4’ Ph); 7.45 (bs,
1H, H-5’ pyz); 7.38 (m, 1H, H-5’ Ph); 6.91 (m, 1H, H-4’ Ph); 6.88 (bs 1H, H-4’pyz). LC-MS: 296.9
[M+H]+. Anal C, H, N.

5.8.8 1,4-dihydro-8-(4-fluorophenyl)-3-(1’H-pyrazolo-3-yl)pyrazolo[5,1-c][1,2,4]triazin-4-one,
9k
1
Orange crystals; TLC eluent: chloroform/methanol/acetic acid 10:2:1 v/v/v; H-NMR (DMSO-
d6) 12.85 (bs, 1H, NH, exchange); 8.44 (s, 1H, H-2); 7.80-7.65 (m, 3H, H-3’ and H-5’ Ph and H-
5’ pyz); 7.35 (m, 2H, H-2’ and H-6’ Ph); 6.90 (bs 1H, H-4’pyz). LC-MS: 296.8 [M+H]+. Anal C, H,
N.
5.8.9 8-(3-chlorophenyl)-1,4-dihydro-3-(1’H-pyrazolo-3-yl)pyrazolo[5,1-c][1,2,4]triazin-4-one,
9l
1
Yellow crystals; TLC eluent: chloroform/methanol 10:1.5 v/v; H-NMR (DMSO-d6) 12.85 (bs,
1H, NH, exchange); 8.40 (m, 2H, H-2 and H-2’ Ph); 8.05 (m, 1H, H-4’ Ph); 7.50 (bs, 1H, H-5’
pyz); 7.38 (m, 1H, H-5’ Ph); 7.18 (m, 1H, H-6’ Ph); 6.89 (bs 1H, H-4’pyz). LC-MS: 313.3 [M+H]+.
Anal C, H, N.
5.8.10
8-(3-bromophenyl)-1,4-dihydro-3-(1’H-pyrazolo-3-yl)pyrazolo[5,1-c][1,2,4]triazin-4-
one, 9m
1
Yellow crystals; TLC eluent: chloroform/methanol 10:1.5 v/v; H-NMR (DMSO-d6) 11.70 (bs,
1H, NH, exchange); 8.55 (m, 1H, H-2’ Ph); 8.42 (s, 1H, H-2); 8.08 (m, 1H, H-4’ Ph); 7.52 (bs, 1H,
H-5’ pyz); 7.35-7.28 (m, 2H, H-5’ and H-6’ Ph); 6.89 (bs 1H, H-4’pyz). LC-MS: 357.8 [M+H]+.
Anal C, H, N.
5.8.11 1,4-dihydro-3-(1’H-pyrazolo-3-yl)-8-(3-trifluoromethyl)pyrazolo[5,1-c][1,2,4]triazin-4-
one, 9n
1
Orange crystals; TLC eluent: dichloromethane/methanol 10:1 v/v; H-NMR (DMSO-d6) 8.50 (s,
1H, H-2); 8.34 (d, 1H, H-2’ Ph); 8.19 (m, 1H, H-4’ Ph); 7.69-7.54 (m, 3H, H-5’, H-6’ Ph and H-5’
pyz); 6.98 (bs 1H, H-4’pyz). LC-MS: 346.8 [M+H]+. Anal C, H, N.
5.8.12 1,4-dihydro-8-(4-methoxyphenyl)-3-(1’H-pyrazolo-3-yl)pyrazolo[5,1-c][1,2,4]triazin-4-
one, 9o