Synthesis of New [1,2,4]Triazolo[1,5-a]pyrimidine Derivatives: Reactivity of 3-Amino[1,2,4]triazole towards Enaminonitriles and Enaminones

Article abstract of DOI:10.1002/jhet.3222

A diversity of new 7-substituted[1,2,4]triazolo[1,5-a]pyrimidine and 6-substituted[1,2,4]triazolo[1,5-a]pyrimidine-7-amine derivatives has been synthesized via reaction of 3-amino-[1,2,4]triazole with enaminonitriles and enaminones. The regio orientation and the structure of the products were confirmed by spectral and analytical data and synthesis via an alternative route. The procedure proved to be simple, efficient, and high yielding, and diversities of [1,2,4]triazolo[1,5-a]pyrimidines were obtained.

Full text of DOI:10.1002/jhet.3222

Month 2018 Synthesis of New [1,2,4]Triazolo[1,5-a]pyrimidine Derivatives: Reactivity
of 3-Amino[1,2,4]triazole towards Enaminonitriles and Enaminones
Abdulaziz Alnajjar,a Mervat Mohammed Abdelkhalik,a Mohamed Abdelmonem Raslan,b Solwan Maher Ibraheem,b and
c
*
Kamal Usef Sadek
aApplied Science Department, College of Technological Studies, Public Authority for Applied Education and Training,
P. O. Box 42325, Safat 70654, Kuwait
bChemistry Department, Faculty of Science, Aswan University, Aswan 81528, Egypt
cChemistry Department, Faculty of Science, Minia University, Minia, 61519, Egypt
*
E-mail: kusadek@yahoo.com
Received March 27, 2018
DOI 10.1002/jhet.3222
Published online 00 Month 2018 in Wiley Online Library (wileyonlinelibrary.com).
A diversity of new 7-substituted[1,2,4]triazolo[1,5-a]pyrimidine and 6-substituted[1,2,4]triazolo[1,5-a]
pyrimidine-7-amine derivatives has been synthesized via reaction of 3-amino-[1,2,4]triazole with
enaminonitriles and enaminones. The regio orientation and the structure of the products were confirmed
by spectral and analytical data and synthesis via an alternative route. The procedure proved to be simple, ef-
ficient, and high yielding, and diversities of [1,2,4]triazolo[1,5-a]pyrimidines were obtained.
J. Heterocyclic Chem., 00, 00 (2018).
INTRODUCTION
ketones, enaminones, and chalcones in refluxing
acetic acid, acetonitrile, or pyridine/HCl [9,10], or via
oxidation of aminopyrimidine Schiff bases utilizing iron
chloride [11]. Condensation of diamino-substituted
pyrimidines can also be used with ortho-esters or with
cyanohydrides [12].
Recently, some [1,2,4]triazolo[1,5-a]pyrimidines-7-
amines were found to have marked anticancer activity.
These scaffolds have been reported to be synthesized via
a lengthy multistep procedure utilizing 8-butyrolactone as
a starting material [13,14] or introducing the isomeric
[1,2,4]triazolo[4,3-a]pyrimidines into a formal Dimorth
rearrangement with diamines under heating in basic
medium [15].
3(5)-Amino-1,2,4-triaoles have two nucleophilic
reaction centers which can lead to the formation of
different cyclic reaction products. Most of the reported
literature has confirmed that cyclocondensation of 3(5)-
amino-1,2,4-triaoles with electrophiles starts with the
interaction of exocyclic amino function with electrophiles,
followed by cyclization with N-2 ring nitrogen. However,
it has been recently reported [16] that the regioselectivity
in such a reaction was controlled by the type of solvent
utilized, whether it is a proton or a non-proton donor.
In continuation of our efforts aimed at developing new
routes for the synthesis of polyfunctional substituted
Essramycin is the first reported antibiotic with a [1,2,4]
triazolo[1,5-a]pyrimidines scaffold [1]. The biological
importance of [1,2,4]triazolo[1,5-a]pyrimidines, as purine
analogues, is well documented. Over the years, various
substituted derivatives of these scaffolds have shown to
act as antifungal [2], antitubercular [3], and antibacterial
[4] agents. They have proven as well to be excellent
herbicidal and plant growth regulators [5]; polycyclic
systems
containing
[1,2,4]triazolo[1,5-a]-pyrimidine
moiety are reported as corticotropin-releasing factor 1
receptor antagonists [6] or calcium channel modulators
[7]. They were also reported to possess promising
anticancer activities, particularly those with C-5, C-6, or
C-7 substituents [8].
The synthetic approaches of [1,2,4]triazolo[1,5-a]
pyrimidines mainly involve two main groups. Either via
cyclocondensation of 3(5)-amino[1,2,4]triazole with 1,2-
dielectrophiles, such as dicarbonyl substituted vinyl
© 2018 Wiley Periodicals, Inc.

A. Alnajjar, M. M. Abdelkhalik, M. A. Raslan, S. M. Ibraheem, and K. U. Sadek
Vol 000
heterocycles [17–20], we report, herein, the results of our
investigation for the reactivity of 3(5)-amino-[1,2,4]
triazole with enaminonitriles and enaminones. A variety
of new functionally 5-substituted [1,2,4]triazolo[1,5-a]
pyrimidines and 6-substituted [1,2,4]triazolo[1,5-a]
pyrimidines-7-amine was obtained in excellent yields.
The structure proposed for the reaction products was
established based on analytical and spectral data and
alternative synthetic routes.
cyanoacetate and benzyl cyanide. Compound 1 also
reacted with 3-(dimethylamino)acrylonitrile 2d to afford
the parent [1,2,4]triazolo[1,5-a]pyrimidin-7-amine 8d.
Mass spectrum of the reaction product revealed ion peak
at 135.1 (100%) m/z. IR spectrum of the reaction product
reveals the absence of cyano group and the presence of
1
NH2 function at λmax = 3336 cmꢀ1. H NMR showed
absorption bands at δ = 6.29, 8.10, 8.24, and 8.43 ppm
assigned for H-6, NH2, H-5, and H-2 protons,
respectively. 13C NMR revealed absorption bands for C-6
and C-7 carbons at δ = 90.65 and 149.16 ppm,
respectively. If the reaction product was 5d, it will reveal
such peaks at downfield shifts (≈105 and 163 ppm). This
synthetic approach extended to the synthesis of
unsubstituted [1,2,4]triazolo[1,5-a]pyrimidine 8e through
the reaction of 1 with 2e. The structure proposed for 8e
was established based on analytical and spectral data. To
the best of our knowledge, the synthesis of 8e has not
been extensively reported, and it was marketed in a very
high price.
The reaction of 1 with benzylidene malononitrile 10
in refluxing DMF/K2CO3 afforded the corresponding
triazolo[1,5-a]dihydropyrimine derivative 12 formed via
initial addition of exocyclic amino group to the activated
double bond system of 10 forming the acyclic adduct 11
which was cyclized to final product 12 via addition
of ring nitrogen to the cyano function. The structure of
12 could be established in bases of analytical and
spectral data. Compound 12 showed a molecular ion peak
m/z = 238.2 (17%). 1H NMR spectrum showed two
proton singlets at δ = 5.32 and 8.61 ppm assigned for NH
and H-5 protons in addition to H-2 proton signal at
δ = 8.78 as well as aromatic protons. 13C NMR was in
agreement of the proposed structure. Heating under reflux
12 in MeCN in the presence of 3 eq. 2,3-dichloro-5,6-
dicyano-1,4-benzoquinone afforded the corresponding
triazolopyrimidine 13 (Scheme 1).
RESULTS AND DISCUSSION
We began this study by reacting 3(5)-amino[1,2,4]triaole
1 and 2-[(dimethylamino)methylene] malononitrile 2a
utilizing several solvents such as ethanol, acetic acid, or
methanol/HCl. No significant reaction was observed, even
for long reaction period times. However, we were
delighted to find that heating under reflux the reaction
mixture in dimethylformamide (DMF) with catalytic
amount of anhydrous potassium carbonate afforded a
solid product in 85% yield. This may be formulated as the
5-amino-[1,2,4]triazolo[1,5-a]pyrimidine-6-carbonitrile 5a
or isomeric 7-amino derivative 8a. Product 8a was
established based on analytical and spectral data. The
mass spectrum of the reaction product showed a
molecular ion peak m/z = 160.2 (100%). IR spectrum
revealed the presence of an amino and cyano groups at
λmax = 3126 and 2225 cmꢀ1, respectively. 1H NMR
spectrum showed two broad singlets at δ = 9.29 and
6.79 ppm assigned for NH2 protons. The downlow field
shift of amino protons could be rationalized for the
anisotropic effect of N-7a. If the reaction product was 5a,
these protons will appear at a higher field δ ≈ 7.4 ppm. In
addition, 13C NMR chemical shift of enamine carbon C-6
appears at a higher field δ = 77.36 ppm, as the cyano
substituent shifts the δ value of this carbon to higher field.
The structure of 8a was further confirmed through the
reaction of N,N-dimethyl-N0-(4H)-([1,2,4]triazol-3-yl)-
formamidine 9 with malononitrile under the same reaction
conditions, affording an authentic sample of 8a.
The cyclocondensation of 1 with β-enaminones 14a–c in
acetic acid under reflux has been recently reported to afford
the corresponding 5-substituted [1,2,4]-triazolo[1,5-a]
pyrimidines. We examined the cyclocondensation of an
equimolecular amount of β-enaminones 14a with 1 in
DMF/K2CO3 under reflux for 2 h. Two supposed
products 15a and 16 were isolated in 1:1 ratio. Both
products showed a molecular ion peak m/z = 196.0
(100%). 7-Phenyl derivatives 15a mp. 141–143°C
(Litmp. 146°C) [21] showed 1H NMR signals at δ
Subsequently, we investigated the scope of this reaction
by extending the synthesis to other [1,2,4]triazolo[1,5-a]
pyrimidine derivatives under the same reaction conditions.
Thus, reacting 1 with ethyl 2-cyano-3-(dimethylamino)
acrylate 2b for 2 h afforded the corresponding ethyl
7-amino[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate 8b
in 85% yield. Similarly, the reaction of
1
with
ppm = 7.63–7.58 (m, 3H, Ar–H), 7.98 (d, 1H,
3-(dimethylamino)-2-phenylacrylonitrile 2c yielded the
corresponding 7-amino derivative 8c. Compound 8c
showed proton shifts at δ =7.96, 8.30, and 8.53 ppm for
amino protons, H-2 and H-5, respectively, in addition to
aromatic protons. Compounds 8b,c could also be
alternatively synthesized via reacting 9 with ethyl
J = 4.8 Hz, H-6), 8.28–8.32 (m, 2H, Ar–H), 8.68 (s, 1H,
H-2), 9.45 (d, 1H, J = 5.0 Hz H-5). Additionally, 13C
NMR spectra established the proposed structure. 5-
Phenyl derivative 16 mp. 182–184°C, Lit. mp. 186°C
[22], revealed 1H NMR absorption bands at
δ
ppm
= 7.54–7.60 (m, 3H, Ar–H), 7.95 (d, 1H,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2018
1,2,4-Triazolo[1,5-a]pyrimidines
Scheme 1
CONCLUSION
In conclusion, a simple, efficient, and high yielding
process could be developed that provides access
to [1,2,4]triazolo[1,5-a]pytimidin-7-amine derivatives.
Furthermore, this methodology is tolerant to various
unsubstituted and 7-aryl substituted [1,2,4]triazolo[1,5-a]
pyrimidine derivatives. We can reveal that the reaction of
3(5)-1,2,4-triazole with enaminonitriles and enaminones
proceeds with an initial attack of exocyclic amino
function followed by cyclization. Although the initial ring
nitrogen attack can be proposed, here, steric factors
hinder such an attack, and the reaction exclusively occurs
at the exocycli amino.
EXPERIMENTAL
Melting points were determined on a Shimadzu-Gallenkamp
apparatus (Gemini BV Laboratory, DG Apeldoorn,
Netherlands) and are uncorrected. Elemental analysis was
obtained by means of
a LECO CHNS-932 Elemental
Analyzer (LECO Corporation, St. Joseph, MI). NMR spectra
were measured using a Bruker DPX 400 MHz superconducting
spectrometer (Bruker Corporation, Billerica, MA), and FT-IR
measurements were obtained from a Perkin Elmer 2000 FT-IR
system (MasSpec Consulting Inc., Oakville, ON, Canada). Mass
spectrometric analysis was carried out on a VG-Autospec-Q
high performance tri-sector GC/MS/MS.
General
Polysubstituted[1,2,4]triazolo[1,5-a]pyrimidines 8a–e, 12,13,
and 14,15. Method A. To a mixture of 3(5)-aminotriazole
Procedure
for
the
Synthesis
of
J = 7.2 Hz, H-6), 8.28 (t, 2H, J = 4.0 Hz, Ar–H), 8.67
(s, 1H, H-2), 8.92 (d, 1H, J = 7.3 Hz H-7). Compounds
15a and 16 resulted from the initial condensation of both
exocyclic amino group and ring nitrogen. Comparison of
the coupling constants values of the 7-substituted isomer
15a and 5-substituted isomer 16 enabled us to
differentiate between them. The coupling constant value
of compound 15a is consistent with that of previously
reported isomer synthesized from the reaction of vinyl
iminium salt with 3-amino-1,2,4-triazole [21]. However,
the reaction of 1 with 14b,c resulted in the formation of
7-aryl-substituted derivatives 15b,c as the sole isolable
products. We do believe that in going from 14a to the
strong electron donating furyl or thienyl substituents, the
reaction became more regioselective and condensation
initially proceeds with the less basic exocyclic amino
function (cf. Scheme 2).
(1 mmol), enaminonitriles 2a–c, benzylidene malononitrile 10,
or enaminones 14a–c (1 mmol) in DMF (10 mL) was added
catalytic amount of K2CO3 (10 mol %), and the reaction
mixture was heated under reflux for 2 h. After cooling to room
temperature, the solid product formed was collected by filtration
and recrystallized from the proper solvent to afford analytically
pure sample. The reaction product of 1 with enaminone 14a
was isolated by column chromatography using acetone-n-
hexane (1:3) as eluent that affords analytically pure samples of
15a and 16.
Method B for the Synthesis of 8a–c. To a mixture of N,N-
dimethyl-N0-(4H-[1,2,4]triazol-1-yl)formamidine
9 (1 mmol),
malononitrile, ethyl cyanoacetate, or benzyl cyanide (1 mmol)
in DMF (10 mL) was added catalytic amount of K2CO3 (10 mol
%). The reaction mixture was heated under reflux for 2 h. After
cooling to room temperature, the solid product formed was
collected by filtration and crystallized from the proper solvent to
afford analytically pure samples of 8a–c.
7-Amino-[1,2,4]triazolo[1,5-a]pyrimidine-6-carbonitrile
(8a).
Golden yellow crystals from ethanol, mp. 283–285°C.
Yield 88% (1.40 g); ESI-Ms: m/z: 160.2 [M+]. IR
λ
max/cmꢀ1: 3126 (NH2), 2225 (CN). 1H NMR (DMSO-d6) δ
ppm: 9.29 (br s, 1H, NH), 8.63 (s, 1H, H-2), 8.59 (s, 1H, H-
5), 6.79 (br s, 1H, NH), 13C NMR (DMSO-d6) δ ppm: 77.36,
115.61, 151.13, 155.91, 157.35 and 162. Anal. Calcd. for
C6H4N6 (160.14): C 45.0, H 2.52, N 52.48. Found: C 45.12,
H 2.51, N 52.35.
Scheme 2
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

A. Alnajjar, M. M. Abdelkhalik, M. A. Raslan, S. M. Ibraheem, and K. U. Sadek
Vol 000
Ethyl 7-amino-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate
(8b). Brown crystals from methanol, mp. 223–224°C. Yield
131.63, 135.80, 137.49, 147.21, 156.41 and 160.82. Anal.
Calcd. for C11H8N4 (196.21): C 67.34, H 4.11, N 28.55. Found:
C 67.36, H 4.15, N 28.58.
85% (1.74 g); ESI-MS: m/z = 207.0 (M+); IR λ max/cmꢀ1
:
3362(NH2), 1694 (CO). 1H NMR (DMSO-d6) δ ppm: 9.18 (s,
1H, hydrogen bonded, NH of NH2), 8.86 (s, 1H, H-2), 8.62 (br
s, 1H, NH), 8.59 (s, 1H, H-5), 4.33–4.38 (q, 2H, J = 7.2 Hz,
CH2), 1.34 (t, 3H, J = 7.2 Hz, CH3). 13C NMR (DMSO-d6) δ
ppm: 14.63, 61.28, 93.57, 150.17, 156.03, 156.57 and 165.75.
Anal. Calcd. for C8H9N5O2 (207.19): C 46.38, H 4.38, N 33.80.
Found: C 46.26, H 4.49, N 33.79.
7-(Furan-2-yl)-[1,2,4]triazolo[1,5-a]pyrimidine (13b).
Brown crystals from ethanol, mp 193–149°C. Yield 75%
(1.4 g); ESI.MS: m/z = 186.2 (M+). 1H NMR (DMSO-d6) δ
ppm: 8.88 (d, 1H, J = 4 Hz, H-5), 8.80 (s, 1H, H-2), 8.20 (d,
1H, J = 5 Hz, furan-H), 8.05 (d, 1H, J = 5 Hz, furan-H, 7.62 (d,
1H, J = 4 Hz, H-6), 6.91–7.60 (m, 1H, furan-H). 13C NMR
(DMSO-d6) δ ppm: 104.9, 114.11, 120.78, 136.81, 142.88,
148.54, 154.91, 155.74 and 156.29. Anal. Calcd. for C9H6N4O
(186.17): C 58.06, H 3.25, N 30.09. Found: C 58.16, H 3.34, N
30.15.
7-(Thien-2-yl)-[1,2,4]triazolo[1,5-a]pyrimidine (13b).
Brown crystals from ethanol, mp 172–173°C. Yield 82%
(1.65 g); ESI.MS: m/z = 202.2 (M+). 1H NMR (DMSO-d6) δ
ppm: 8.87 (d, 1H, J = 5 Hz, H-5), 8.81 (s, 1H, H-2), 8.53 (d,
1H, J = 3 Hz, thienyl-H), 8.16 (d, 1H, J = 5 Hz, thienyl-H),
7.94 (d, 1H, J = 5 Hz, CH-6), 7.37–7.39 (m, 1H, thienyl-H).
13C NMR (DMSO-d6) δ ppm: 106.45, 128.72, 130.16, 133.51,
135.87, 141.44, 154.64, 155.84 and 155.89.
6-Phenyl-[1,2,4]triazolo[1,5-a]pyrimidin-7-amine (8c).
Brown crystals from dioxane, mp. 291–292°C. Yield 83%
(1.75 g); ESI-MS: m/z = 211.0 (M+); IR λ max/cmꢀ1: 3414
1
(NH2). H NMR (DMSO-d6) δ ppm: 8.53 (s, 1H, H-2), 8.30 (s,
1H, H-5), 7.96 (s, 2H, NH2), 7.42–7.54 (m, 5H, Ar–H). 13C
NMR (DMSO-d6) δ ppm: 102.21, 105.32, 128.17, 129.86,
132.07, 133.68, 144.59, 146.96, 154.46, 155.29 and 153.39.
Anal. Calcd. for C11H9N5 (211.23): C 62.55, H 4.29, N 33.16.
Found: C 62.45, H 4.44, N 33.01.
[1,2,4]Triazolo[1,5-a]pyrimidin-7-amine (8d). Pale yellow
crystals from ethanol, mp. 288–290°C. Yield 78% (1.05 g);
ESI-MS: m/z = 135 (M+); IR λ max/cmꢀ1: 3336 (NH2).1H
NMR (DMSO-d6) δ ppm: 8.43 (s, 1H, H-2), 8.24 (d, 1H,
J = 2.8 Hz. H-5), 8.10 (brs, 2H, NH2), 6.29 (d, 1H, J = 3.6 Hz.
H-6), 13C NMR (DMSO-d6) δ ppm: 90.65, 149.16, 153.40,
154.31 and 155.83. Anal. Calcd. for C5H5N5 (135.13): C 44.44,
H 3.73, N 51.83. Found: C 44.42, H 3.73, N 51.72.
Anal. Calcd. for C9H6N4S (202.23): C 53.45, H 2.99, N 27.70,
S 15.85. Found: C 53.40, H 2.94, N 27.75.
Oxidation of Compound 12.
Compound 12 (0.238 g,
0.5 mmol) was treated with 2,3-dichloro-5,6-dicyano-1,4-
benzoquinone (0.27 g) in acetonitrile (5 mL) and heated at 55°C
for 4 h. The product was then separated by filtration and
washed with ethanol to afford 13.
7-Amino-5-phenyl-[1,2,4]triazolo[1,5-a]pyrimidine-6-
carbonitrile (11). Colorless crystals from dioxane, mp. 235°C.
[1,2,4]Triazolo[1,5-a]pyrimidine (8e).
Colorless crystals
from benzene, mp. 144–146°C, Lit. mp Sigma Aldrich 142–
145°C. Yield 82% (0.96 g); ESI-MS: m/z = 120 (M+); IR λ
1
max/cmꢀ1: 3083 (C–H), 1661 (C¼N). H NMR (DMSO-d6) δ
Yield 80% (0.19 g); ESI-MS: m/z = 236 (M+); IR λ max/cmꢀ1
:
3345(NH2), 2226 (CN). 1H NMR (DMSO-d6) δ ppm: 8.61 (s,
1H, H-2), 7.56–7.96 (m, 5H, Ph–H), 7.38 (s, 2H, NH2). 13C
NMR (DMSO-d6) δ ppm: 81.53, 116.57, 127.8, 128.54, 129.24,
130.39, 134.26, 132.19, 134.26, 150.46, 161.48 and 162.69.
Anal. Calcd. for C12H8N6 (236.24): C 61.01, H 3.41, N 35.57.
Found: C 60.68, H 3.46, N 35.25.
ppm: 9.41–9.43 (m, 1H, H-5), 8.90–8.89 (m, 1H, H-7), 8.62 (s,
1H, H-2), 7.31–7.34 (m, 1H, H-6). 13C NMR (DMSO-d6) δ
ppm: 110.87, 137.36, 154.61, 155.47 and 155.79. Anal. Calcd.
for C5H4N4 (120.11): C 50.00, H 3.36, N 46.64. Found: C
50.23, H 3.49, N 46.71.
7-Amino-5-phenyl-4,5-dihydro-[1,2,4]-triazolo[1,5-a]
pyrimidine (12).
Colorless crystals from dioxane, mp. 133–
135°C. Yield 82% (1.93 g). ESI-MS: m/z = 238.2. 1H NMR
(DMSO-d6) δ ppm: 8.791 (s, 1H, H-2), 8.62 (s, 1H, H-5), 7.71–
7.28 (m, 5H, Ar–H), 7.22 (s, 2H, NH2). 13C NMR (DMSO-d6)
δ ppm: 155.89, 153.91, 151.82, 146.92, 143.14, 136.94, 130.48,
128.63, 125.97, 118.91, 56.01, and 53.98. Anal. Calcd. for
C12H10N6 (238.25): C 60.50, H, 4.23, N 35.27. Found: C 60.38,
H 4.22, N 35.24.
Acknowledgments. This research was done by the financial
support of Public Authority for Applied Education and Training
(Transform Grant TS-15-02) of Kuwait. We are grateful to the
University of Kuwait, general facility projects in the chemistry
department for the analytical and spectral measurements.
7-Phenyl-[1,2,4]triazolo[1,5-a]pyrimidine (13a).
Yellow
crystals, mp. 141–143°C. Yield 44% (0.86 g); ESI-MS:
m/z = 196.0 (M+); IR λ max/cmꢀ1: 3100 (C–H) and 1620
(C¼N). 1H NMR (DMSO-d6) δ ppm: 7.63–7.58 (m, 3H, Ar–
H), 7.98 (d, 1H, J = 7.2 Hz, H-6), 8.32–8.28 (m, 2H, Ar–H),
8.68 (s, 1H, H-2), 9.45 (d, 1H, J = 8.8 Hz, H-5); 13C NMR
(DMSO-d6) δ ppm: 107.87, 127.67, 129.10, 131.44, 135.85,
137.56, 154.74, 156.44 and 160.87. Anal. Calcd. for C11H8N4
(196.21): C 67.34, H 4.11, N 28.55. Found: C 67.36, H 4.13,
N 28.42.
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5-Phenyl-[1,2,4]triazolo[1,5-a]pyrimidine
(14).
Pale
yellow crystals, mp. 182–184°C. Yield 40% (0.78 g); ESI-MS:
m/z = 196.0 (M+). 1H NMR (DMSO-d6) δ ppm: 8.92 (d, 1H,
J = 7.3 Hz, H-7), 8.67 (s, 1H, H-2), 8.28 (t, 2H, J = 4 Hz, Ar–
H), 7.95 (d, 1H, J = 7.2 Hz, H-6), 7.54–7.60(m, 3H, Ar–H). 13C
NMR (DMSO-d6) δ ppm: 107.83, 109.62, 127.62, 129.48,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2018
1,2,4-Triazolo[1,5-a]pyrimidines
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet