A Concise [3?+?3] Heteroaromatization Synthetic Strategy Afford Dicarboxamide Functionalized Novel Pyrazolo[1,5-a]Pyrimidines

Article abstract of DOI:10.1002/jhet.2860

A concise and effective approach to dicarboxamide functionalized novel pyrazolo[1,5-a]pyrimidine has been developed. The method involves [3?+?3] hetroaromatization of oxoketene dithioacetals (16a–x) with 5-amino-N-cyclohexyl-3-(methylthio)-1H-pyrazole-4-c

Full text of DOI:10.1002/jhet.2860

Month 2017
A Concise [3 + 3] Heteroaromatization Synthetic Strategy Afford
Dicarboxamide Functionalized Novel Pyrazolo[1,5-a]Pyrimidines
a
a
b
*
*
Anilkumar S. Patel, Naval P. Kapuriya, and Yogesh T. Naliapara
aDepartment of Chemistry, Shree Manibhai Virani & Smt. Navalben Virani Science College (Autonomous), Rajkot,
Gujarat, India
bDepartment of Chemistry, Saurashtra University, Rajkot 360005, Gujarat, India
*
E-mail: patelanil32@gmail.com; naliaparachem@yahoo.co.in
Additional Supporting Information may be found in the online version of this article.
Received May 30, 2016
DOI 10.1002/jhet.2860
Published online 00 Month 2017 in Wiley Online Library (wileyonlinelibrary.com).
A concise and effective approach to dicarboxamide functionalized novel pyrazolo[1,5-a]pyrimidine has
been developed. The method involves [3 + 3] hetroaromatization of oxoketene dithioacetals (16a–x) with
5-amino-N-cyclohexyl-3-(methylthio)-1H-pyrazole-4-carboxamide (12) in the presence of K2CO3. This
method has advantages of excellent yields, operational simplicity, and avoidance of hazardous base like
piperidine.
J. Heterocyclic Chem., 00, 00 (2017).
INTRODUCTION
pyrimidines has been reported from oxoketene
dithioacetals and 3-aminopyrazoles via [3 3]
+
Pyrazolo[1,5-a]pyrimidines have attracted considerable
interest because of their significant biological activities
such as antimetabolites [1], anticancer [2], antiviral [3],
selective cyclooxygenase-2 (COX-2) inhibitors [4], 3-
heteroaromatization strategy using bifuctional catalyst
such as piperidine in acetic acid [22]. Further, Mizar
et al. [22] have reported KF-alumina catalyzed three-
component condensation strategy of oxoketene
dihioacetals, pyrazolones, and alkyl amides for the
construction of pyrazolo[1,5-a]pyrimidines. However,
these methods have several drawbacks such substrate
specificity, use of stoichiometric reagents, moderate to
poor yields. Hence, the development of novel
dicarboxamide functionalized pyrazolo[1,5-a]pyrimidines
with simple and efficient synthetic methodology is
highly essential.
Recently, we have reported the synthesis of
trisubstituted pyrazoles/isooxazoles and functionalized
pyrimidines using oxoketene dithioacetals [23]. To
explore further the utility of oxoketene dithioacetals in
the synthesis of novel heterocyclic compounds, herein,
we describe versatile and efficient synthetic methods for
dicarboxamide functionalized pyrazolo[1,5-a]pyrimidines
(17a–x) (Fig. 2).
hydroxy-3-methylglutaryl-coenzyme-A
(HMG-CoA)
reductase inhibitors [5], selective phosphodiesterase-4
(PDE-4) inhibitors [6], corticotropin-releasing hormone
receptor-1 (CRF1) antagonists [7], 5-hydroxytryptamine
receptor (5-HT(6)) antagonists [8], antibacterial [9],
hypnotics [10], and antimicrobial and antioxidant
activities [11]. Furthermore, the pyrazolo[1,5-a]
pyrimidines structural motif is also found in several
clinically used drug candidates exhibiting diverse range
of physiological activities such as sedative-hypnotic
and anxiolytic drugs like zaleplon (1, hypnotic) [12],
indiplon (2, hypnotic) [13], lorediplon (3, hypnotic)
[14], and ocinaplon (4, anxiolytic) [15]. Recently,
several
new
pyrazolo[1,5-a]pyrimidines
bearing
dicarboxamide substitutions have been reported having
potential pharmacological activities such as protein
kinase modulators (5) [16], Jenus (JAK) kinase
inhibitor (6) [17], and metalloprotese inhibitor (7) [18]
(Fig. 1).
RESULT AND DISCUSSION
In the literature, oxoketene dithioacetals were shown
as an attractive synthon for the preparation of diversely
substituted fused five- and six-membered heterocycles
[19–21]. Particularly, synthesis of pyrazolo[1,5-a]
To prepare the targeted dicarboxamide functionalized
pyrazolo[1,5-a]pyrimidines, we initially synthesized
requisite intermediate 5-amino-N-cyclohexyl-3-(methylthio)-
© 2017 Wiley Periodicals, Inc.

A. S. Patel, N. P. Kapuriya, and Y. T. Naliapara
Vol 000
Figure 1. Pharmacologically active pyrazolo[1,5-a]pyrmidines.
Figure 2. [3 + 3] heteroaromatization strategy.
1H-pyrazole-4-carboxamide (12) by the following literature
method as shown in Scheme 1. Reaction of
ethylcynoacetate (8) with cyclohexylamines (9) in
refluxing toluene afforded 2-cyano-N-cyclohexylacetamide
[24] (10) in 90% yield. This product underwent
condensation reaction with carbon disulfide in the presence
of base in DMF followed by S-methylation
to afford corresponding 2-cyano-3,3-bis(methylthio)-N-
phenylacrylamide [25] (11). Cyclization reaction of 11
with hydrazine hydrate yielded 5-amino-N-cyclohexyl-3-
(methylthio)-1H-pyrazole-4-carboxamide
[26]
(12)
(Scheme 1).
Synthesis
of
second
intermediate oxoketene
Scheme 1. Synthesis of 5-amino-N-cyclohexyl-3-(methylthio)-1H–
dithioacetals was achieved by our previously reported
method with modification [23] (Scheme 2). Reaction of
substituted aniline (14a–h) with various β-ketoesters
(13a–c) in the presence of catalytic amount of KOH in
refluxing toluene generated acetoacetanilide derivatives
[27] (15a–x) in excellent yield. Further treatment of
15a–x with carbon disulfide in the presence of K2CO3
followed by the S-methylation using methyl iodide
furnished oxoketene dithioacetals [23] (16a–x) in high
yields.
pyrazole-4-carboxamide [12].
Having requisite derivatives in hand, oxoketene
dithioacetal (16a) was reacted with 5-amino-N-cyclohexyl-
3-(methylthio)-1H-pyrazole-4-carboxamide (12) in the
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
A Concise [3 + 3] Heteroaromatization Synthetic Strategy Afford Dicarboxamide
Functionalized Novel Pyrazolo[1,5-a]Pyrimidines
Scheme 2. Synthesis of functionalized oxoketenedithioacetals (16a–x).
presence of piperidine in acetic acid as described in the
literature [22]. However, this transformation was not
efficient giving only 30% yield of the desired
dicarboxamide pyrazolo[1,5-a]pyrimidine derivative 17a
(Entry 1, Table 1) after 20 h.
[3 + 3] heteroaromatization giving rise to the excellent
yields (77–95%) of the targeted derivatives 17a–x within
7–10 h. This finding demonstrated the general utility of
our protocol for the synthesis of dicarboxamide
substituted pyrazolo[1,5-a]pyrimidines.
To find suitable reaction condition for this substrate,
screening of various bases and solvents has been carried
out, and the results are displayed in Table 1. As evident,
cyclization of 12 with 16a was facile in the presence of
K2CO3 in refluxing isopropyl alcohol (i-PrOH) providing
dicarboxamide functionalized pyrazolo[1,5-a]pyrimidine
(17a) in 94% yield (Entry 14).
Having established the optimal reaction condition, we
next examined the substrate scope (16a–x) of this method
for the construction of a library of 3,6-dicarboxamide
functionalized pyrazolo[1,5-a]pyrimidines. The results are
summarized in Table 2. As shown, no significant effect
of functional groups (R1 and R2) was observed for
The structures of newly prepared derivatives 17a–x were
1
established on the basis of their spectral data (MS, IR, H
NMR, and 13C NMR) and elemental analysis. A plausible
mechanism for the synthesis of dicarboxamide
functionalized pyrazolo[1,5-a]pyrimidnes is shown in
Scheme 3.
As depicted, nucleophilic attack of exocyclic-NH2
group of compound 12 on the double bond of
oxoketene dithioacetals (16a–x) may yield adduct A,
which further eliminates –SCH3 group to generate
intermediate B. The intramolecular cyclizes of B via
dehydration may afforded the desired pyrazolo[1,5-a]
pyrimidines 17a–x.
Table 1
Optimization of the synthesis of dicarboxamidepyrazolo[1,5-a]pyrimidine(17a).
Entry
Solvent
Base
Time (h)
Yield (%)a
1
2
3
4
5
6
7
8
AcOH
MeOH
EtOH
i-PrOH
Dioxane
DMF
MeOH
EtOH
i-PrOH
Dioxane
DMF
MeOH
EtOH
i-PrOH
Dioxane
DMF
Piperidine
NaHCO3
NaHCO3
NaHCO3
NaHCO3
NaHCO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
Na2CO3
K2CO3
20
20
20
20
20
20
14
14
14
14
14
10
10
8
30
35
48
50
40
32
60
62
68
55
48
75
80
94
82
78
9
10
11
12
13
14
15
16
K2CO3
K2CO3
K2CO3
K2CO3
10
10
a = Isolated yield, reaction condition: compounds 12 (1.0 mmol), 16a (1.0 mmol), and Base (2.0 mmol) in refluxing condition with given solvent.
Bold data represent optimized reaction condition.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

A. S. Patel, N. P. Kapuriya, and Y. T. Naliapara
Vol 000
Table 2
Synthesis of dicarboxamide functionalized pyrazolo[1,5-a]pyrimidines(17a–x).
Entry
R1
CH3
CH3
CH3
CH3
CH3
CH3
CH3
R2
Yield (%)a
17a
17b
17c
17d
17e
17f
17g
17 h
17i
4-CH3
3-Cl
3-Cl, 4-F
4-Cl
94
92
90
88
92
95
90
89
93
77
95
94
92
87
94
90
88
82
87
90
93
95
90
87
4-F
4-NO2
4-OCH3
2,5diCH3
4-CH3
3-Cl
3-Cl, 4-F
4-Cl
4-F
4-NO2
4-OCH3
2,5diCH3
4-CH3
3-Cl
3-Cl, 4-F
4-Cl
4-F
CH3
(CH3)2CH
(CH3)2CH
(CH3)2CH
(CH3)2CH
(CH3)2CH
(CH3)2CH
(CH3)2CH
(CH3)2CH
(CH2)2CH
(CH2)2CH
(CH2)2CH
(CH2)2CH
(CH2)2CH
(CH2)2CH
(CH2)2CH
(CH2)2CH
17j
17k
17l
17m
17n
17o
17p
17q
17r
17s
17 t
17u
17v
17w
17x
4-NO2
4-OCH3
2,5diCH3
a = Isolated yield, reactioncondition:compounds 12(3.0mmol), 16a (3.0mmol), andK2 CO3 (6.0mmol) in refluxingconditionin i-PrOH (10 mL)for 7–10 h.
Scheme 3. Plausible mechanism for the formation pyrazolo[1,5-a]pyrimidines.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
A Concise [3 + 3] Heteroaromatization Synthetic Strategy Afford Dicarboxamide
Functionalized Novel Pyrazolo[1,5-a]Pyrimidines
CONCLUSION
164.90; IR (KBr): 3409, 3254, 3016, 2925, 1671, 1473,
831, 807, 758 cmÀ1; MS (m/z): 484 (M+); Anal. Calcd
for C24H29N5O2S2: C, 59.60; H, 6.04; N, 14.48; Found:
C, 59.46; H, 6.10; N, 14.39.
A library of 24 novel dicarboxamide functionalized
pyrazolo[1,5-a]pyrimidines has been prepared from
oxoketene dithoacetals and 5-amino-N-cyclohexyl-3-
N6-(3-chlorophenyl)-N3-cyclohexyl-7-methyl-2,5-bis(methylthio)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17b).
Creamish
(methylthio)-1H-pyrazole-4-carboxamide.
We
have
solid; mp >320°C; Rf = 0.40 (chloroform–methanol,
demonstrated that [3 3] heteroaromatization of
+
1
9:1); H NMR (300 MHz, DMSO): δ = 1.35–1.81 (m,
oxoketene dithoacetals is efficient in the presence of
K2CO3 and i-PrOH as solvent furnishing dicarboxamie
pyrazolo[1,5-a]pyrimidines in excellent yields (77–95%)
within 7–10 h.
10H, 5 × CH2), 2.45 (s, 6H, 2 × SCH3), 2.70 (s, 3H,
CH3), 3.79 (m, 1H, CH), 7.05 (s, 1H, Ar―H), 7.31–
7.35 (m, 2H, Ar―H), 8.02 (s, 1H, Ar―H), 8.54–8.56
(d, 1H, CONH), 12.56 (s, 1H, CONH); 13C NMR
(75 MHz, DMSO): δ = 12.40, 23.86, 25.34, 27.54,
30.54, 32.55, 45.86, 98.23, 98.89, 117.29, 118.69,
121.70, 129.88, 133.31, 141.26, 148.07, 154.00, 158.20,
161.85, 163.79, 165.67; IR (KBr): 3417, 3024, 2902,
1673, 1516, 1483, 1332, 845, 800, 756, 695 cmÀ1; MS
(m/z): 503 (M+); Anal. Calcd for C23H26ClN5O2S2: C,
54.80; H, 5.20; N, 13.89; Found: C, 54.71; H, 5.14; N,
EXPERIMENTAL
General.
All chemicals were obtained from
commercially available sources and used without further
purification (Aldrich, Fluka, Enamine Ltd.). Thin-layer
chromatography was accomplished on 0.2-mm precoated
plates of silica gel G60 F254 (Merck). Visualization was
made with UV light (254 and 365 nm) or with an iodine
vapor. Infrared spectra were recorded on a FTIR-8400
13.69.
N6-(3-chloro-4-fluorophenyl)-N3-cyclohexyl-7-methyl-2,5-
bis(methylthio)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
(17c). White solid; mp >320°C; Rf = 0.48 (chloroform–
1
spectrophotometer using DRS prob. H (300 MHz) and
1
methanol, 9:1); H NMR (300 MHz, DMSO): δ = 1.24–
13C (75 MHz) NMR spectra were recorded on a Bruker
AVANCE II spectrometer in CDCl3 and DMSO.
Chemical shifts are expressed in δ ppm downfield from
TMS as an internal standard. Mass spectra were
determined using direct inlet probe on a GCMS-QP 2010
mass spectrometer (Shimadzu). Solvents were evaporated
with a BUCHI rotary evaporator. Melting points were
measured in open capillaries and are uncorrected.
1.79 (m, 10H, 5 × CH2), 2.47 (s, 6H, 2 × SCH3), 2.70 (s,
3H, CH3), 3.77 (m, 1H, CH), 7.12–7.19 (m, 2H, Ar―H),
7.42–7.49 (m, 1H, Ar―H), 8.03 (s, 1H, CONH), 12.22
(s, 1H, CONH); 13C NMR (75 MHz, DMSO): δ = 12.41,
23.77, 25.30, 27.41, 30.33, 32.70, 45.81, 98.27, 98.91,
116.28, 117.94, 121.25, 129.88, 132.11, 142.50, 148.77,
154.23, 159.22, 162.35, 163.80, 165.75; IR (KBr): 3423,
3026, 2908, 2856, 1674, 1630, 1563, 1473, 1246, 927,
843, 798, 732 cmÀ1; MS (m/z): 522 (M+); Anal. Calcd
for C23H25ClFN5O2S2: C, 52.91; H, 4.83; N, 13.41;
General procedure for synthesis of dicarboxamide
functionalized pyrazolo[1,5-a]pyrimidines 17a–x.
A
mixture of 5-amino-N-cyclohexyl-3-(methylthio)-1H–
pyrazole-4-carboxamide (12, 3.0 mmol), potassium
carbonate (6.0 mmol), and ketene dithioacetals (16a–x,
3.0 mmol) in i-PrOH (10 mL) was heated to reflux for
7–10 h. The progress of reaction mixture was monitored
by TLC. After completion of reaction, the mixture was
cooled to room temperature; the solid separated product
was filtered and washed with of i-PrOH followed by
50 mL of water. The product was recrystallized from
MeOH to give 17a–x in 77–95% yield.
Found: C, 52.86; H, 4.71; N, 13.56.
N6-(4-chlorophenyl)-N3-cyclohexyl-7-methyl-2,5-bis(methylthio)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17d).
Creamish
solid; mp >320°C; Rf = 0.35 (chloroform–methanol, 9:1);
1H NMR (300 MHz, DMSO): δ = 1.29–1.74 (m, 10H,
5 × CH2), 2.42 (s, 6H, 2 × SCH3), 2.78 (s, 3H, CH3),
3.69 (m, 1H, CH), 7.18–7.21 (d, 2H, J = 8.4 Hz,
Ar―H), 7.42–7.45 (d, 2H, J = 8.2 Hz, Ar―H), 8.78–
8.80 (d, 1H, CONH), 12.41 (s, 1H, CONH); 13C NMR
(75 MHz, DMSO): δ = 12.42, 23.52, 25.44, 27.51, 30.83,
32.59, 45.70, 98.10, 98.69, 117.21, 118.23, 121.78,
129.84, 133.23, 141.40, 148.21, 154.08, 158.23, 161.63,
163.80, 165.78; IR (KBr) 3410, 3024, 2902, 1668, 1516,
1483, 1332, 1166, 954, 852, 822, 748, 709 cmÀ1; MS
(m/z): 503 (M+); Anal. Calcd for C23H26ClN5O2S2: C,
54.80; H, 5.20; N, 13.89; Found: C, 54.66; H, 5.08; N,
N3-cyclohexyl-7-methyl-2,5-bis(methylthio)-N6-p-tolylpyrazolo
[1,5-a]pyrimidine-3,6-dicarboxamide (17a).
White solid;
1
mp >320°C; Rf = 0.31 (chloroform–methanol, 9:1); H
NMR (300 MHz, DMSO): δ = 1.23–1.78 (m, 10H,
5 × CH2), 2.44 (s, 6H, 2 × SCH3), 2.67 (s, 3H, CH3),
3.70 (m, 1H, CH), 6.92–6.95 (d, 2H, J = 8.4 Hz,
Ar―H), 7.58–7.61 (d, 2H, J = 8.3 Hz, Ar―H), 8.32 (s,
1H, CONH), 11.23 (s, 1H, CONH); 13C NMR (75 MHz,
DMSO): δ = 12.47, 21.60, 23.81, 25.33, 27.50, 30.22,
32.70, 45.80, 98.18, 98.78, 113.22, 116.56, 120.89,
130.46, 136.88, 148.24, 153.34, 158.28, 160.95, 163.49,
13.94.
N3-cyclohexyl-N6-(4-fluorophenyl)-7-methyl-2,5-bis(methylthio)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17e).
White
solid; mp >320°C; Rf = 0.28 (chloroform–methanol,
1
9:1); H NMR (300 MHz, DMSO): δ = 1.21–1.77 (m,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

A. S. Patel, N. P. Kapuriya, and Y. T. Naliapara
10H, 5 × CH2), 2.42 (s, 6H, 2 × SCH3), 2.64 (s, 3H,
Vol 000
1516, 1483, 1232, 1166, 954, 883, 780, 743, 698 cmÀ1
;
CH3), 3.66 (m, 1H, CH), 7.02–7.10 (m, 2H, Ar―H),
7.54–7.59 (m, 2H, Ar―H), 8.67–8.69 (d, 1H, CONH),
12.22 (s, 1H, CONH); 13C NMR (75 MHz, DMSO):
δ = 12.38, 23.79, 24.96, 27.52, 30.25, 32.61, 45.80,
98.45, 98.99, 116.23, 117.27, 121.78, 123.43, 131.09,
141.18, 148.52, 154.66, 160.11, 162.26, 163.70,
166.15; IR (KBr): 3430, 3133, 3051, 2922, 1665, 1516,
1483, 1232, 1166, 954, 883, 780, 743, 698 cmÀ1; MS
(m/z): 487 (M+); Anal. Calcd for C23H26FN5O2S2: C,
56.65; H, 5.37; N, 14.36; Found: C, 56.41; H, 5.18; N,
MS (m/z): 497 (M+); Anal. Calcd for C25H31N5O2S2: C,
60.33; H, 6.28; N, 14.07; Found: C, 60.21; H, 6.18; N,
14.43.
N3-cyclohexyl-7-isopropyl-2,5-bis(methylthio)-N6-p-tolylpyrazolo
[1,5-a]pyrimidine-3,6-dicarboxamide (17i).
White solid; mp
1
>320°C; Rf = 0.35 (chloroform–methanol, 9:1); H NMR
(300 MHz, DMSO): δ = 1.17–1.21 (d, 6H, 2 × CH3),
1.27–1.89 (m, 10H, 5 × CH2), 2.48 (s, 6H, 2 × SCH3),
2.54 (s, 3H, CH3), 3.79 (m, 1H, CH), 4.10–4.18 (m, 1H,
CH), 7.09–7.19 (m, 1H, Ar―H), 7.53–7.56 (d, 2H,
J = 8.1 Hz, Ar―H), 8.21–8.23 (d, 1H, CONH), 11.94 (s,
1H, CONH); 13C NMR (75 MHz, DMSO): δ = 11.67,
12.28, 13.90, 23.21, 25.48, 46.21, 98.13, 99.85, 113.85,
115.23, 120.80, 121.23, 135.85, 146.23, 155.89, 157.47,
158.75, 162.88, 166.13, 167.75; IR (KBr): 3279, 3254,
3016, 2928, 2850, 1730, 1681, 1566, 1313, 1246, 835,
810, 748, 667 cmÀ1; MS (m/z): 512 (M+); Anal. Calcd
for C26H33N5O2S2: C, 61.03; H, 6.50; N, 13.69; Found:
14.48.
N3-cyclohexyl-7-methyl-2,5-bis(methylthio)-N6-(4-nitrophenyl)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17f). Yellow
solid; mp >320°C; Rf = 0.29 (chloroform–methanol, 9:1);
1H NMR (300 MHz, DMSO): δ = 1.27–1.91 (m, 10H,
5 × CH2), 2.48 (s, 6H, 2 × SCH3), 2.75 (s, 3H, CH3),
3.83 (m, 1H, CH), 7.89–7.94 (m, 2H, Ar―H), 8.18–8.23
(m, 2H, Ar―H), 8.91–8.93 (d, 1H, CONH), 12.42 (s,
1H, CONH); 13C NMR (75 MHz, DMSO): δ = 12.45,
23.91, 25.01, 27.88, 30.61, 32.66, 45.91, 98.55, 99.23,
116.70, 118.11, 121.42, 124.12, 131.51, 144.28, 150.51,
158.23, 160.11 162.55, 164.23, 166.78; IR (KBr): 3421,
3122, 3088, 2922, 1661, 1516, 1483, 1232, 1166, 954,
883, 780, 743, 698 cmÀ1; MS (m/z): 514 (M+); Anal.
Calcd for C23H26N6O4S2: C, 53.68; H, 5.09; N, 16.33;
C, 61.05; H, 6.53; N, 13.66.
N6-(3-chlorophenyl)-N3-cyclohexyl-7-isopropyl-2,5-bis(methylthio)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17j).
White
solid; mp >320°C; Rf = 0.44 (chloroform–methanol, 9:1);
1H NMR (300 MHz, DMSO): δ = 1.16–1.19 (d, 6H,
2 × CH3), 1.31–1.78 (m, 10H, 5 × CH2), 2.47 (s, 6H,
2 × SCH3), 3.67 (m, 1H, CH), 4.22–4.25 (m, 1H, CH),
7.19 (s, 1H, Ar―H), 7.43–7.46 (m, 2H, Ar―H), 8.41–
8.43 (d, 1H, CONH), 11.68 (s, 1H, CONH); 13C NMR
(75 MHz, DMSO): δ = 11.70, 12.35, 13.71, 23.41, 25.60,
98.20, 99.46, 115.21, 116.42, 120.56, 128.21, 133.78,
143.12, 156.25, 157.47, 159.60, 162.92, 164.99, 165.73;
IR (KBr): 3198, 3157, 3042, 2942, 2832, 1734, 1668,
1654, 1257, 832, 806, 742 cmÀ1; MS (m/z): 532 (M+);
Anal. Calcd for C25H30ClN5O2S2: C, 56.43; H, 5.68; N,
Found: C, 53.50; H, 5.18; N, 16.52.
N3-cyclohexyl-N6-(4-methoxyphenyl)-7-methyl-2,5-bis(methylthio)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17 g).
Creamish
solid; mp >320°C; R = 0.36 (chloroform–methanol,
1
9:1); H NMR (300 MHz, DMSO): δ = 1.30–1.83 (m,
10H, 5 × CH2), 2.47 (s, 6H, 2 × SCH3), 2.65 (s, 3H,
CH3), 3.68 (m, 1H, CH), 3.83 (s, 3H, OCH3), 7.11–
7.18 (m, 2H, Ar―H), 7.78–7.84 (m, 2H, Ar―H),
8.59–8.61 (d, 1H, CONH), 11.59 (s, 1H, CONH); 13C
NMR (75 MHz, DMSO): δ = 12.30, 23.87, 24.88,
27.51, 30.19, 32.63, 45.71, 56.23, 98.15, 98.77, 114.21,
116.66, 121.23, 123.41, 131.10, 143.11, 159.66,
162.21, 163.57, 164.85; IR (KBr): 3422, 3127, 3085,
13.16; Found: C, 56.45; H, 5.67; N, 13.16.
N6-(3-chloro-4-fluorophenyl)-N3-cyclohexyl-7-isopropyl-2,5-
bis(methylthio)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
(17 k).
Creamish solid; mp >320°C; Rf = 0.41
(chloroform–methanol, 9:1); 1H NMR (300 MHz,
DMSO): δ = 1.24–1.54 (m, 12H, 2 × CH3 and 3 × CH2),
1.69–1.89 (m, 4H, 2 × CH2), 2.49 (s, 6H, 2 × SCH3),
3.74 (m, 1H, CH), 4.10–4.18 (m, 1H, CH), 7.31–7.37
(m, 1H, Ar―H), 7.43–7.46 (m, 1H, Ar―H), 8.10–8.12
(m, 1H, Ar―H), 8.54–8.57 (d, 1H, CONH), 12.02 (s,
1H, CONH); 13C NMR (75 MHz, DMSO): δ = 11.18,
12.37, 13.94, 24.36, 25.28, 30.54, 33.13, 98.52, 98.94,
118.64, 124.80, 141.29, 146.22, 148.24, 154.22, 157.96,
161.84, 166.28, 167.89; IR (KBr): 3398, 3227, 3150,
2902, 2865, 1651, 1516, 1452, 1326, 880, 750,
697 cmÀ1; MS (m/z): 550 (M+); Anal. Calcd for
C25H29ClFN5O2S2: C, 54.58; H, 5.31; N, 12.73; Found:
2942, 1678, 1483, 1237, 1158, 883, 780, 743 cmÀ1
;
MS (m/z): 499 (M+); Anal. Calcd for C24H29N5O3S2:
C, 57.69; H, 5.85; N, 14.02; Found: C, 57.48; H, 5.67;
N, 14.26.
N3-cyclohexyl-7-methyl-N6-(2,5-dimethylphenyl)-2,5-bis
(methylthio)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
(17 h).
Creamish solid; mp >320°C; Rf = 0.41
(chloroform–methanol, 9:1); 1H NMR (300 MHz,
DMSO): δ = 1.21–1.91 (m, 16H, 5 × CH2 and 2 × CH3),
2.48 (s, 6H, 2 × SCH3), 2.72 (s, 3H, CH3), 3.71 (m, 1H,
CH), 7.01–7.08 (m, 2H, Ar―H), 7.42 (s, 1H, Ar―H),
8.91–8.93 (d, 1H, CONH), 11.23 (s, 1H, CONH); 13C
NMR (75 MHz, DMSO): δ = 12.41, 21.42, 22.10, 23.81,
24.66, 27.48, 30.11, 32.58, 45.40, 98.10, 98.87, 115.22,
117.46, 122.21, 125.41, 133.10, 141.11, 160.55, 163.08,
163.89, 164.12; IR (KBr): 3430, 3133, 3051, 2922, 1671,
C, 54.40; H, 5.23; N, 12.50.
N6-(4-chlorophenyl)-N3-cyclohexyl-7-isopropyl-2,5-bis(methylthio)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17 l).
solid; mp >320°C; Rf = 0.38 (chloroform–methanol, 9:1);
White
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
A Concise [3 + 3] Heteroaromatization Synthetic Strategy Afford Dicarboxamide
Functionalized Novel Pyrazolo[1,5-a]Pyrimidines
1H NMR (300 MHz, DMSO): δ = 1.17–1.19 (d, 6H,
2 × CH3), 1.27–1.38 (m, 4H, 2 × CH2), 1.66–1.89 (m,
6H, 3 × CH2), 2.48 (s, 6H, 2 × SCH3), 3.79 (m, 1H,
CH), 4.10–4.18 (m, 1H, CH), 7.32–7.35 (d, 2H,
J = 8.1 Hz, Ar―H), 7.67–7.70 (d, 1H, J = 8.4 Hz,
Ar―H), 8.53–8.57 (d, 1H, CONH), 11.96 (s, 1H,
CONH); 13C NMR (75 MHz, DMSO): δ = 11.73, 12.21,
13.60, 23.42, 25.70, 98.13, 99.44, 115.44, 118.12,
123.20, 127.44, 131.88, 142.80, 151.20, 156.41, 159.21,
161.56, 164.23, 165.67; IR (KBr): 3425, 3258, 3124,
2998, 2847, 1661, 1532, 1425, 1318, 867, 817, 753,
689 cmÀ1; MS (m/z): 532 (M+); Anal. Calcd for
C25H30ClN5O2S2: C, 56.43; H, 5.68; N, 13.16; Found: C,
OCH3), 4.02–4.08 (m, 1H, CH), 7.02–7.05 (d, 2H,
J = 8.0 Hz, Ar―H), 7.66–7.69 (d, 2H, J = 8.1 Hz,
Ar―H), 8.21–8.23 (d, 1H, CONH), 11.94 (s, 1H,
CONH); 13C NMR (100 MHz, DMSO): δ = 11.70,
12.30, 13.88, 23.45, 25.40, 45.22, 56.48, 98.66, 99.23,
114.23, 116.66, 121.24, 122.73, 134.37, 146.64, 155.29,
159.65, 163.99, 165.84, 166.23; IR (KBr): 3483, 3242,
3162, 3068, 2902, 1675, 1584, 1425, 1332, 1066, 954,
820, 750 cmÀ1; MS (m/z): 528 (M+); Anal. Calcd for
C26H33N5O3S2: C, 59.18; H, 6.30; N, 13.27; Found: C,
59.19; H, 6.17; N, 13.42.
N3-cyclohexyl-7-isopropyl-N6-(2,5-dimethylphenyl)-2,5-
bis(methylthio)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
(17p). White solid; mp >320°C; Rf = 0.22 (chloroform–
56.28; H, 5.51; N, 13.02.
1
N3-cyclohexyl-N6-(4-fluorophenyl)-7-isopropyl-2,5-bis(methylthio)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17 m). Creamish
methanol, 9:1); H NMR (300 MHz, DMSO): δ = 1.12–
1.17 (d, 6H, 2 × CH3), 1.30–1.39 (m, 4H, 2 × CH2),
1.56–1.92 (m, 12H, 3 × CH2 and 2 × CH3), 2.47 (s,
6H, 2 × SCH3), 3.71 (m, 1H, CH), 4.12–4.18 (m, 1H,
CH), 6.99–7.03 (m, 2H, Ar―H), 7.44 (s, 2H, Ar―H),
8.66–8.68 (d, 1H, CONH), 12.21(s, 1H, CONH); 13C
NMR (75 MHz, DMSO): δ = 11.71, 12.31, 13.78,
23.40, 25.33, 45.70, 98.18, 98.99, 115.18, 116.16,
120.34, 122.68, 134.30, 146.15, 156.10, 156.62, 160.24,
164.16, 165.70; IR (KBr): 3503, 3450, 3206, 3068,
solid; mp >320°C; Rf = 0.45 (chloroform–methanol, 9:1);
1H NMR (300 MHz, DMSO): δ = 1.12–1.16 (d, 6H,
2 × CH3), 1.32–1.40 (m, 4H, 2 × CH2), 1.62–1.78 (m,
6H, 3 × CH2), 2.44 (s, 6H, 2 × SCH3), 3.71 (m, 1H,
CH), 4.08–4.12 (m, 1H, CH), 7.12–7.15 (d, 2H,
J = 8.2 Hz, Ar―H), 7.60–7.63 (d, 1H, J = 8.4 Hz,
Ar―H,), 8.87–8.92 (d, 1H, CONH), 12.21 (s, 1H,
CONH); 13C NMR (75 MHz, DMSO): δ = 11.70, 12.32,
13.71, 23.40, 25.75, 98.15, 99.56, 114.89, 115.17,
122.88, 127.40, 133.80, 140.65, 151.28, 156.44, 159.56,
161.53, 164.88, 165.47; IR (KBr): 3454, 3260, 3142,
2978, 2850, 1645, 1542, 1425, 1318, 867, 750 cmÀ1; MS
(m/z): 515 (M+); Anal. Calcd for C25H30FN5O2S2: C,
58.23; H, 5.86; N, 13.58; Found: C, 58.13; H, 5.45; N,
2908, 1628, 1548, 1420, 1342, 1066, 825, 754 cmÀ1
;
MS (m/z): 525 (M+); Anal. Calcd for C27H35N5O3S2: C,
61.68; H, 6.71; N, 13.32; Found: C, 61.67; H, 6.72; N,
13.36.
N3-cyclohexyl-7-cyclopropyl-2,5-bis(methylthio)-N6-p-tolylpyrazolo
[1,5-a]pyrimi-dine-3,6-dicarboxamide (17q).
Creamish
solid; mp >320°C; Rf = 0.35 (chloroform–methanol, 9:1);
1H NMR (300 MHz, DMSO): δ = 0.98–1.01 (m, 4H,
2 × CH2), 1.16–1.37 (m, 4H, 2 × CH2), 1.55–1.89 (m,
6H, 3 × CH2), 2.25–2.27 (s, 3H, CH3), 2.45 (s, 6H,
2 × SCH3), 3.64–3.71 (m, 2H, 2 × CH), 7.09–7.19 (dd,
2H, J = 7.8 Hz, Ar―H), 7.67–7.70 (d, 1H, J = 8.1 Hz,
Ar―H), 8.21–8.23 (d, 1H, CONH), 11.96 (s, 1H,
CONH); 13C NMR (75 MHz, DMSO): δ = 10.86, 12.30,
13.66, 23.41, 25.30, 45.80, 98.27, 99.49, 115.03, 115.46,
121.08, 122.88, 136.23, 147.20, 154.74, 155.22, 158.67,
162.02, 164.33, 165.62; IR (KBr): 3460, 3226, 3047,
2938, 1615, 1539, 1422, 1336, 1066, 834, 757 cmÀ1; MS
(m/z): 509 (M+); Anal. Calcd for C26H31N5O2S2: C,
61.27; H, 6.13; N, 13.74; Found: C, 61.19; H, 6.00; N,
13.76.
N3-cyclohexyl-7-isopropyl-2,5-bis(methylthio)-N6-(4-nitrophenyl)
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide (17n).
Creamish
solid; mp >320°C; Rf = 0.34 (chloroform–methanol, 9:1);
1H NMR (300 MHz, DMSO): δ = 1.17–1.23 (d, 6H,
2 × CH3), 1.38–1.42 (m, 4H, 2 × CH2), 1.66–1.92 (m,
6H, 3 × CH2), 2.52 (s, 6H, 2 × SCH3), 3.83 (m, 1H,
CH), 4.23–4.26 (m, 1H, CH), 7.88–7.91 (d, 2H,
J = 8.1 Hz, Ar―H), 8.10–8.13 (d, 1H, J = 8.0 Hz,
Ar―H), 9.02–9.07 (d, 1H, CONH), 12.48 (s, 1H,
CONH); 13C NMR (75 MHz, DMSO): δ = 11.70, 12.42,
13.78, 23.44, 26.22, 98.78, 99.89, 115.23, 116.89,
121.83, 128.28, 136.81, 142.18, 151.45, 157.84, 159.42,
162.02, 164.66, 166.21; IR (KBr): 3460, 3367, 3242,
2956, 2845, 1647, 1538, 1420, 1318, 867, 750,
700 cmÀ1; MS (m/z): 542 (M+); Anal. Calcd for
C25H30N6O4S2: C, 55.33; H, 5.57; N, 15.49; Found: C,
13.91.
N6-(3-chlorophenyl)-N3-cyclohexyl-7-cyclopropyl-2,5-bis
(methylthio)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
(17r). White solid; mp >320°C; Rf = 0.43 (chloroform–
55.12; H, 5.49; N, 15.78.
1
N3-cyclohexyl-7-isopropyl-N6-(4-methoxyphenyl)-2,5-bis
(methylthio)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
methanol, 9:1); H NMR (300 MHz, DMSO): δ = 0.93–
0.98 (m, 4H, 2 × CH2), 1.22–1.31 (m, 4H, 2 × CH2),
1.51–1.73 (m, 6H, 3 × CH2), 2.47 (s, 6H, 2 × SCH3),
3.70–377 (m, 2H, 2 × CH), 7.19 (s, 1H, Ar―H), 7.55–
7.59 (m, 2H, Ar―H), 7.88–7.91 (m, 1H, Ar―H), 8.64–
8.66 (d, 1H, CONH), 12.20 (s, 1H, CONH); 13C NMR
(75 MHz, DMSO): δ = 10.91, 12.22, 13.70, 23.51,
(17o).
White solid; mp >320°C; Rf
=
0.23
(chloroform–methanol, 9:1); 1H NMR (300 MHz,
DMSO): δ = 1.12–1.17 (d, 6H, 2 × CH3), 1.27–1.32
(m, 4H, 2 × CH2), 1.54–1.83 (m, 6H, 3 × CH2), 2.44
(s, 6H, 2 × SCH3), 3.66 (m, 1H, CH), 3.82 (s, 3H,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

A. S. Patel, N. P. Kapuriya, and Y. T. Naliapara
Vol 000
25.25, 45.79, 98.17, 99.88, 114.23, 115.46, 120.98,
122.25, 135.93, 148.10, 153.44, 156.21, 158.60, 161.69,
165.31, 165.69; IR (KBr): 3457, 3345, 3147, 3038,
1556, 1481, 1354, 1251, 1058, 893, 833, 792, 750,
711 cmÀ1; MS (m/z): 513 (M+); Anal. Calcd for
C25H28FN5O2S2: C, 58.46; H, 5.49; N, 13.63; Found:
2952, 1615, 1539, 1422, 1336, 1076, 828, 745 cmÀ1
;
C, 58.49; H, 5.47; N, 13.64.
N3-cyclohexyl-7-cyclopropyl-2,5-bis(methylthio)-N6-(4-
nitrophenyl)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
MS (m/z): 530 (M+); Anal. Calcd for C25H28ClN5O2S2:
C, 56.64; H, 5.32; N, 13.21; Found: C, 56.46; H, 5.19;
N, 13.44.
(17v).
Creamish solid; mp >320°C; Rf = 0.52
(chloroform–methanol, 9:1); 1H NMR (300 MHz,
DMSO): δ = 1.01–1.07 (m, 4H, 2 × CH2), 1.31–1.43 (m,
4H, 2 × CH2), 1.58–1.91 (m, 6H, 3 × CH2), 2.52 (s, 6H,
2 × SCH3), 3.77–3.82 (m, 2H, 2 × CH), 7.88–7.92 (d,
2H, J = 8.8 Hz, Ar―H), 8.18–8.22 (d, 2H, J = 8.8 Hz,
Ar―H), 9.03–9.06 (d, 1H, CONH), 12.42 (s, 1H,
CONH); 13C NMR (75 MHz, DMSO): δ = 11.18, 12.37,
13.94, 24.36, 25.28, 30.54, 33.13, 46.32, 98.52, 98.94,
118.64, 124.80, 141.29, 146.22, 148.24, 154.22, 157.96,
161.84, 166.28, 167.89; IR (KBr): 3422, 3205, 3169,
2964, 2856, 1658, 1522, 1425, 1084, 838, 736 cmÀ1; MS
(m/z): 540 (M+); Anal. Calcd for C25H28N6O4S2: C,
55.54; H, 5.22; N, 15.54; Found: C, 55.25; H, 5.01; N,
15.76.
N6-(3-chloro-4-fluorophenyl)-N3-cyclohexyl-7-cyclopropyl-2,5-
bis(methylthio)
(17 s).
pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
Creamish solid; mp >320°C; Rf = 0.40
(chloroform–methanol, 9:1); 1H NMR (300 MHz,
DMSO): δ = 0.98–1.03 (m, 4H, 2 × CH2), 1.18–1.33
(m, 4H, 2 × CH2), 1.57–1.93 (m, 6H, 3 × CH2), 2.44
(s, 6H, 2 × SCH3), 3.65–3.73 (m, 2H, 2 × CH), 7.22–
7.27 (m, 2H, Ar―H), 7.69 (s, 1H, Ar―H), 8.44–8.47
(d, 1H, CONH), 12.05 (s, 1H, CONH); 13C NMR
(75 MHz, DMSO): δ = 10.88, 12.24, 13.78, 23.52,
25.18, 45.70, 98.48, 99.18, 113.43, 114.56, 121.25,
126.21, 135.78, 148.23, 153.34, 157.67, 158.16, 162.46,
164.33, 164.23; IR (KBr): 3448, 3250, 3130, 2948,
2902, 1651, 1516, 1483, 1332, 1166, 850, 772,
705 cmÀ1; MS (m/z): 548 (M+); Anal. Calcd for
C25H27ClFN5O2S2: C, 54.78; H, 4.97; N, 12.78; Found:
N3-cyclohexyl-7-cyclopropyl-N6-(4-methoxyphenyl)-2,5-bis
(methylthio)pyrazolo
(17w).
[1,5-a]pyrimidine-3,6-dicarboxamide
Creamish solid; mp >320°C; Rf
= 0.48
C, 54.26; H, 4.74; N, 12.98.
(chloroform–methanol, 9:1); 1H NMR (300 MHz,
DMSO): δ = 0.98–1.02 (m, 4H, 2 × CH2), 1.11–1.23 (m,
4H, 2 × CH2), 1.43–1.79 (m, 6H, 3 × CH2), 2.45 (s, 6H,
2 × SCH3), 3.60–3.66 (m, 2H, 2 × CH), 3.88 (s, 3H,
OCH3), 6.91–6.94 (dd, 2H, J = 7.8 Hz, Ar―H), 7.51–
7.54 (d, 1H, J = 8.0 Hz, Ar―H), 8.02–8.03 (d, 1H,
CONH), 11.66 (s, 1H, CONH); 13C NMR (75 MHz,
DMSO): δ = 10.81, 12.32, 13.45, 23.40, 25.61, 45.67,
98.10, 98.92, 112.13, 117.46, 129.08, 136.13, 141.20,
156.67, 160.02, 162.28, 164.61; IR (KBr): 3445, 3247,
3038, 2952, 1628, 1539, 1422, 1336, 1257, 838,
745 cmÀ1; MS (m/z): 525 (M+); Anal. Calcd for
C26H31N5O3S2: C, 59.40; H, 5.94; N, 13.32; Found: C,
N6-(4-chlorophenyl)-N3-cyclohexyl-7-cyclopropyl-2,5-bis
(methylthio)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
(17 t).
Creamish solid; mp >320°C; Rf = 0.46
(chloroform–methanol, 9:1); 1H NMR (300 MHz,
DMSO): δ = 0.97–1.02 (m, 4H, 2 × CH2), 1.28–1.34
(m, 4H, 2 × CH2), 1.56–1.81 (m, 6H, 3 × CH2), 2.47
(s, 6H, 2 × SCH3), 3.71–3.76 (m, 2H, 2 × CH), 7.32–
7.35 (d, 2H, J = 8.4 Hz, Ar―H), 7.55–7.58 (d, 2H,
J = 8.8 Hz, Ar―H), 8.23–8.26 (d, 1H, CONH), 11.90
(s, 1H, CONH); 13C NMR (75 MHz, DMSO):
δ = 10.87, 12.21, 13.77, 23.22, 25.63, 45.50, 98.29,
99.46, 113.22, 118.26, 121.73, 122.05, 136.13, 142.11,
157.64, 158.11, 163.28, 165.55, 166.10; IR (KBr):
3428, 3248, 3057, 2964, 2926, 1651, 1516, 1483, 1328,
1158, 850, 772 cmÀ1; MS (m/z): 530 (M+); Anal. Calcd
for C25H28ClN5O2S2: C, 56.64; H, 5.32; N, 13.21;
59.11; H, 5.62; N, 13.74.
N3-cyclohexyl-7-cyclopropyl-N6-(2,5-dimethylphenyl)-2,5-
bis(methylthio) pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
(17×).
Creamish solid; mp >320°C; Rf = 0.49
Found: C, 56.22; H, 5.28; N, 13.38.
(chloroform–methanol, 9:1); 1H NMR (300 MHz,
DMSO): δ = 0.98–1.02 (m, 4H, 2 × CH2), 1.08–1.17
(m, 4H, 2 × CH2), 1.46–1.88 (m, 12H, 3 × CH2 and
2 × CH3), 2.44 (s, 6H, 2 × SCH3), 3.71–3.78 (m, 2H,
2 × CH), 6.91–6.94 (m, 2H, Ar―H), 7.38 (s, 2H,
Ar―H), 8.26–8.28 (d, 1H, CONH), 11.62 (s, 1H,
CONH); 13C NMR (75 MHz, DMSO): δ = 10.71,
12.31, 13.78, 23.44, 25.52, 45.71, 98.38, 99.18, 113.18,
114.16, 120.62, 134.30, 146.15, 156.62, 160.24,
164.23, 165.67; IR (KBr): 3258, 3158, 3038, 2948,
N3-cyclohexyl-7-cyclopropyl-N6-(4-fluorophenyl)-2,5-bis
(methylthio)pyrazolo[1,5-a]pyrimidine-3,6-dicarboxamide
(17u). White solid; mp >320°C; Rf = 0.23 (chloroform–
1
methanol, 9:1); H NMR (300 MHz, DMSO): δ = 0.93–
1.03 (m, 4H, 2 × CH2), 1.17–1.38 (m, 6H, 3 × CH2),
1.71–1.74 (m, 2H, CH2), 1.89–1.92 (m, 2H, CH2), 2.48
(s, 6H, 2 × SCH3), 3.66–3.74 (m, 2H, 2 × CH), 7.06–
7.11 (m, 2H, Ar―H), 7.67–7.70 (dd, 2H, J = 7.4 Hz,
Ar―H), 8.24–8.26 (d, 1H, CONH), 12.11 (s, 1H,
CONH); 13C NMR (75 MHz, DMSO): δ = 10.96,
12.35, 13.76, 24.32, 25.29, 33.14, 46.23, 98.07, 99.87,
114.93, 115.14, 120.80, 120.88, 136.19, 148.46, 153.74,
156.37, 157.47, 158.75, 161.92, 165.71, 166.89; IR
(KBr): 3408, 3340, 3277, 3070, 2928, 2852, 1672,
1645, 1558, 1426, 1358, 1216, 835, 745, 708 cmÀ1
;
MS (m/z): 523 (M+); Anal. Calcd for C27H33N5O2S2:
C, 61.92; H, 6.35; N, 13.37; Found: C, 61.65; H, 6.11;
N, 13.62.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
A Concise [3 + 3] Heteroaromatization Synthetic Strategy Afford Dicarboxamide
Functionalized Novel Pyrazolo[1,5-a]Pyrimidines
Acknowledgments. We are thankful to the Department of
Chemistry, Saurashtra University and School of Science, RK
University, for providing necessary research and literature
search facilities. The authors are also thankful to “National
Facility for Drug Discovery through NCE’s Development and
Instrumentation Support to Small Manufacturing Pharma
Enterprises” (NFDD) program under DPRS jointly funded by
the Department of Science and Technology (DST) for spectral
analysis.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet