Studies with enamines: Route to aminoazolopyrimidines and arylazoazolopyrimidines

Article abstract of DOI:10.5560/ZNB.2013-2252

An easy preparation of enaminonitrile derivatives and their transformation into new substituted azolopyrimidines is described. The one-step transformation was carried out under microwave irradiation and by classical heating methods. The use of microwave i

Full text of DOI:10.5560/ZNB.2013-2252

Studies with Enamines: Route to Aminoazolopyrimidines and
Arylazoazolopyrimidines
Abdellatif M. Salaheldin and Khalid S. Khairou
Department of Chemistry, College of Applied Sciences, Umm AlQura University, P. O. Box
13401, Makkah 21955, Saudi Arabia
Reprint requests to Dr. A. M. Salaheldin. E-mail: amsalaheldin@yahoo.com.
Z. Naturforsch. 2013, 68b, 175 – 181 / DOI: 10.5560/ZNB.2013-2252
Received September 5, 2012
An easy preparation of enaminonitrile derivatives and their transformation into new substituted
azolopyrimidines is described. The one-step transformation was carried out under microwave irradi-
ation and by classical heating methods. The use of microwave irradiation led to high conversion and
shorter reaction times.
Key words: Azolopyrimidines, Enamines, Azoloazines, Microwave Irradiation
Introduction
The chemistry of azolopyrimidines has in the past
Result and Discussions
The enamine 1a could be prepared either via heat-
received considerable interest [1 – 5] and is still an ing cyanoacetic acid, piperidine and triethyl ortho-
area of major interest [6, 7]. Recently azoloazines have formate in a microwave oven or, as has been de-
been shown to be of antimicrobial, antioxidant [8] and scribed recently [6, 7], via heating a mixture of tri-
agrochemical importance. Moreover they are a promis- ethyl orthoformate, piperidine and cyanoacetic acid
ing new class of dyes for D2T2 printing and hair under reflux for two hours. A synthesis of 1a via heat-
dyes [9, 10].
ing 3-ethoxyacrylonitrile (2) and piperidine in a mi-
Microwave heating has been employed as a fre- crowave oven for five minutes was also achieved. This
quent resource for the improvement of classical reac- reaction required 12 hours reflux for completion [7]
tions. The major benefits of performing reactions un- (Scheme 1).
der microwave conditions are significant rate enhance-
The enaminonitrile 1b could be easily obtained
ments and higher product yields as compared to reac- via reacting p-nitrobenzylcyanide (3a) and dimethyl-
tions which are run under conventional heating. Key formamide dimethylacetal (DMF-DMA) in refluxing
advantages of modern, scientific microwave appara- dioxane. Trials to condense benzyl cyanide (3b) with
tus are their ability to control reaction conditions pre- DMF-DMA failed. Compounds 1c, d could be read-
cisely by monitoring temperature/pressure and reac- ily obtained by refluxing a mixture of 3a, b, triethyl
tion times and ease of isolation of the products after orthoformate and piperidine in DMF solution for 72 h
work-up [11, 12].
to produce 1c or 24 h to isolate 1d. We believe that
In conjunction to our interest in the chemistry of the in situ-generated amidoacetal 1-(diethoxymethyl)
enaminonitriles [13 – 16], we report here results of our piperidine (A) is initially formed, and then this re-
work aimed at developing efficient environmentally acts with 3a, b to yield the enaminonitriles 1c,
friendly syntheses for several targeted azoloazines uti- d [13]. This condensation could be effected by mi-
lizing enamines 1a – d as starting materials. In our crowave heating, and the products were found iden-
chemical reactivity studies described here, we princi- tical in all details (melting point and TLC analy-
pally employed the intermediates 1d due to their easy sis, NMR) to the compounds obtained by the other
preparation and good yields of reactions.
method.
© 2013 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com

176
A. M. Salaheldin – K. S. Khairou · Studies with Enamines
H2C CO2H
CN
CN
Ar
CN
N
CN
piperidine
N
EtO
2
(EtO)3CH
piperidine
1a
1c
, Ar = C6H5
O2N
2 h
1d, Ar = 4-NO2-C6H4
MW
CN
X
DMF-DMA
EtO
OEt
(EtO)3CH
piperidine
DMF, 72 h
or MW
CN
3a, X = NO2
3a, b
X = NO2
N
N
DMF-DMA
X = H
1b
b, X = H
no reaction
A
Scheme 1. DMF-DMA: dimethylformamide dimethylacetal.
Ph
Ph
N N
HN
N N
CN
Ph
N
NH
H2N
H2N
N
N
N
6
N N
NH2
NH
NH2
7
1a
H2N
PhN=N Cl
N
5
Ph
Ph
N N
N N
NH2
N
N
CN
NH2NH2 H2O
CN
H2N
N
N
H2N
N
N
8
N
Ph
NH2
NC
10
N
Ph
NH
Ph
4
N N
N
NH2
H2N
N
N
9
Scheme 2.
The yellow 4-(phenylazo)pyrazole-3,5-diamine (5)
Compound 5 condensed with 1a via piperidine
was prepared by heating 2-(phenylazo)mesoxalonitrile elimination upon reflux in pyridine solution or upon
(4) and hydrazine hydrate in dioxane in a microwave heating in a microwave oven to yield products that
oven or by conventional heating [17].
may be formulated as 6 – 9 (Scheme 2). Thus ini-

A. M. Salaheldin – K. S. Khairou · Studies with Enamines
177
NO2
NH2
N
N
NH
1d
N
N
N
R = H
R
NH2
N
11a, R = H
b
, R = CH3
13
1a
R = CH3
NH2
N
N
N
H3C
N
12
Scheme 3.
Scheme 4. EAA: ethyl acetoacetate.
tial condensation with the exocyclic amino func- readily ruled out based on the absence of a CN
tion would afford 6 which can then cyclizes into 7. band in the IR spectrum and the presence of two
Alternately, 8 may be initially formed which then amino functions according to the 1H NMR spec-
cyclizes into 9. Acyclic structures 6 and 8 were trum.

178
A. M. Salaheldin – K. S. Khairou · Studies with Enamines
Structure 7 is preferred over 9 based on the ap- The 1H NMR (300 MHz) and 13C NMR (75.4 MHz) spectra
were recorded on a Varian Mercury 300 MHz spectrometer
in [D6]DMSO as solvent and with TMS as internal standard;
pearance of an NH2 singlet at δ = 8.0 ppm. Isomeric
9 should show this function at higher field [18, 19].
chemical shifts are reported in δ units (ppm). Mass spec-
tra were measured at 70 eV using a Shimadzu GCMS-QP-
1000 EX mass spectrometer. Microanalyses were performed
on a Leco CHN-932 instrument by the Microanalysis Unit of
Cairo University. Microwave experiments were conducted in
a CEM MARS oven. Compounds 1a and 5 were provided by
Prof. Elnagdi, while compounds 14b and 18 were prepared
as previously reported by us [20, 21].
Compound 7 could be coupled with benzenediazonium
chloride to yield 10 (cf. Scheme 2).
Similarly, aminotriazoles 11b reacted with 1a to
yield 12. Compound 12 could not be coupled fur-
ther with aromatic diazonium salts (Scheme 3). It is of
value to report that reaction of 11a with the enamine
1d yields 13. Structure 13 was established based on the
1H NMR spectrum which revealed the triazolopyrimi-
dine CH signal at almost the same chemical shift as for
11a, and an amino signal that appeared at δ = 8.2 ppm.
Compound 1c failed to condense with 11a or 11b.
Enamine 1d was readily converted into aminopy-
razole 14a on reflux with hydrazine hydrate in DMF
solution or on heating in a microwave oven, also in
DMF. However, 1c did not react under similar condi-
tions. On the other hand, under microwave irradiation
and in the presence of acetic acid the aminopyrazole
14b was formed (Scheme 4) [20].
Compounds 14a, b reacted with sodium nitrite to af-
ford a diazonium salt that coupled with ethyl acetoac-
etate to yield 16a, b, while the reaction of 14a with
DMF-DMA followed by ethyl acetoacetate (EAA)
yielded 17. Reaction of 14a with enamine 18 [21] and
enaminonitrile 1a afforded pyrazolopyrimidine 19 and
20, respectively, (Scheme 4). The structures of these
compounds were established based on their elemen-
tal analysis and spectral data (cf. Experimental Sec-
tion).
3-Dimethylamino-2-(4-nitrophenyl)acrylonitrile (1b)
A mixture of 3a (0.01 mol, 1.62 g) and DMF-DMA
(0.012 mol) in dioxane (15 mL) was refluxed for three h
and then cooled and poured onto water. The green solid
product formed was collected by filtration and crystallized
from ethanol to give 1b. Yield 70%; m. p. 178 – 180 ◦C. –
IR (KBr): ν = 2222 (CN), 1610 (C=C) cm−1. – 1H NMR
(300 MHz,): δ = 3.27 (s, 3 H, CH3), 3.33 (s, 3 H, CH3), 7.50
(d, 2 H, J = 9 Hz, Ar-H), 7.80 (s, 1 H, olefinic-H), 8.12 (d, 2
H, J = 9 Hz, Ar-H). – 13C NMR (75.4 MHz,): δ = 43.64 (2
CH3), 97.27 (C=CH), 122.54 (CN), 123.36, 132.40, 144.45,
145.75, 150.50 (C=CH). – MS (EI, 70 eV): m/z (%) = 217
(100) [M]+. – C11H11N3O2 (217.22): calcd. C 60.82, H 5.10,
N 19.34; found C 60.85, H 5.03, N 19.30.
General procedure for the preparation of compounds 1c, d
Method A. To a mixture of 4-nitrobenzyl cyanide
3a or benzyl cyanide 3b (0.3 mol), triethyl orthoformate
(0.32 mol), and piperidine (0.3 mol) DMF (40 mL) was
added, and the solution was refluxed for 72 h. The reaction
mixture was then cooled and poured onto water. The solid
product formed was collected by filtration and crystallized
from ethanol (1c 70%; 1d 65%).
Conclusion
In conclusion, in situ generation of less volatile
amide acetals from piperidine diethylacetal enables to
apply drastic reaction conditions in the condensation
of amide acetals with active methylene compounds,
so that less reactive compounds can be applied for
condensation reactions. This method implies the use
of less expensive chemicals. The conversion of the
methylene compounds to enamines enhances the re-
activity toward electrophiles. Shorter reaction times
and higher yields were obtained by microwave irradia-
tion.
Method B. Under microwave irradiation. Into a round
bottom flask of 250 mL equipped with a condenser, 4-
nitrobenzyl cyanide 3a or benzyl cyanide 3b (0.3 mol), tri-
ethyl orthoformate (0.32 mol), piperidine (0.3 mol) and DMF
(40 mL) were added, and the mixture was heated at reflux
during 20 min (for 1c) and 10 min (for 1d) under microwave
irradiation (at a constant power of 400 W). After cooling
to r. t., the reaction mixture was poured onto water to give
a solid, which was identical in all respects with that obtained
from the above reactions (TLC, m. p., NMR), (1c 85%; 1d
77%).
2-Phenyl-3-(piperidin-1-yl)acrylonitrile (1c)
Experimental Section
All melting points are uncorrected. IR spectra were
Yield: 85%; m. p. 116 – 117 ◦C. – IR (KBr): ν = 2190
recorded in KBr with a Bruker Vector 22 spectrophotometer. (CN), 1616 (C=C) cm−1. – 1H NMR (300 MHz,): δ = 1.60

A. M. Salaheldin – K. S. Khairou · Studies with Enamines
179
(s, 6 H, 3 CH2), 3.63 (s, 4 H, 2 CH2), 7.16 (s, 1 H, olefinic- – 1H NMR (300 MHz): δ = 7.35 (s, 1 H, 5-H), 7.51 (t, 6 H,
H), 7.26 – 7.45 (m, 5 H, Ar-H). – 13C NMR (75.4 MHz,): J = 9 Hz, Ar-H), 7.61 (s, 2 H, NH2), 7.83 (d, 4 H, J = 9 Hz,
δ = 24.36, 26.41, 51.96, 75.41 (C=CH), 121.59 (CN), Ar-H), 12.60 (s, 2 H, NH2). – MS (EI, 70 eV): m/z (%) = 357
124.48, 125.51, 129.14, 137.27, 149.29 (C=CH). – MS (EI, (44) [M]+. – C18H15N9 (357.37): calcd. C 60.50, H 4.23, N
70 eV): m/z (%) = 212 (42) [M]+. – C14H16N2 (212.29): 35.27; found C 60.60, H, 4.30, N 35.30.
calcd. C 79.21, H 7.60, N 13.20; found C 79.29, H 7.67, N
13.17.
2-Methyl-[1,2,4]triazolo[1,5-a]pyrimidin-7-amine (12)
2-(4-Nitrophenyl)-3-(piperidin-1-yl)acrylonitrile (1d)
Method A. A mixture of 11b (0.01 mol, 0.98 g) and enam-
inonitrile 1a (0.01 mol, 1.36 g) in pyridine (25 mL) was re-
Yield: 77%; m. p. 130 – 132 ◦C. – IR (KBr): ν = 2206, fluxed for 3 h. The reaction mixture was left to cool to room
(CN), 1618 (C=C), 1595, 1330 (NO2) cm−1. – 1H NMR temperature, and the solid formed was collected by filtration
(300 MHz,): δ = 1.75 (m, 6 H, 3 CH2); 3.70 (m, 4 H, 2 CH2); and crystallized from ethanol to afford 12 (yield 60%).
7.10 (s, 1 H, olefinic-H); 7.45 (d, 2 H, J = 10 Hz, Ar-H), 8.08
Method B. A mixture of aminotriazole 11b (0.01 mol,
(d, 2 H, J = 10 Hz, Ar-H). – MS (EI, 70 eV): m/z (%) = 257 0.98 g) and enaminonitrile 1a (0.01 mol, 1.36 g) was heated
(42) [M]+. – C14H15N3O2 (257.29): calcd. C 65.35, H 5.88, in a microwave oven for 5 min. The resulting product was
N 16.33; found C 65.15, H 5.70, N 16.44.
triturated with ethanol, and the formed solid was collected by
filtration, crystallized from ethanol and identified as 12 (m.
p. mixed m. p. and TLC). Yield 86%; m. p. 222 – 224 ◦C.
– IR (KBr): ν = 3340 (NH2) cm−1. – 1H NMR (300 MHz):
δ = 2.25 (s, 3 H, CH3), 6.55 (d, 1 H, J = 7 Hz, 6-H), 7.90
(s, 2 H, N H2), 8.15 (d, 1 H, J = 7 Hz, H-5). – 13C NMR
(75.4 MHz): δ = 14.8 (CH3), 95.90 (C-6), 145.7 (C-7), 150.3
(C-5), 153.2 (C-3a), 155.7 (C-2). – MS (EI, 70 eV): m/z
(%) = 149 (44) [M]+. – C6H7N5 (149.15): calcd. C 48.32;
H 4.73; N 46.95; found C 48.30, H 4.80, N 46.80.
3-(2-Phenyldiazenyl)pyrazolo[1,5-a]pyrimidine-2,7-
diamine (7)
Method A. A mixture of 5 (0.01 mol, 2.02 g) and enam-
inonitrile 1a (0.01 mol, 1.36 g) in pyridine (25 mL) was re-
fluxed for 3 h. The reaction mixture was then acidified with
concentrated hydrochloric acid, refluxed for 10 min and then
poured onto water. The solid formed was collected by filtra-
tion and crystallized from ethanol (yield 65%).
6-(4-Nitrophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-
amine (13)
Method B. A mixture of 5 (0.01 mol, 2.02 g) and 1a
(0.01 mol, 1.36 g) in DMF (10 mL) was heated in a mi-
crowave oven for 5 min and then left to cool. The solid
formed was collected and identified as 7 (m. p, mixed m.
Method A. A mixture of 11a (0.01 mol, 0.84 g) and enam-
p. and TLC). Yield 80%; m. p. 185 – 187 ◦C. – IR (KBr): inonitrile 1d (0.01 mol, 2.57 g) in pyridine (25 mL) was re-
ν = 3340 (NH2), cm−1. – 1H NMR (300 MHz): δ = 6.65 (d, fluxed for 3 h. The reaction mixture was left to cool to
1 H, J = 8 Hz, 6-H), 7.20 – 7.35 (m, 5 H, Ar-H), 8.0 (s, 2 room temperature, and the solid so formed was collected by
H, NH2), 8.10 (d, 1 H, J = 8 Hz, H-5), 11.81 (s, 2 H, NH2). filtration and crystallized from ethanol to afford 13 (yield
– MS (EI, 70 eV): m/z (%) = 253 (56) [M]+. – C12H11N7 67%).
(253.26): calcd. C 56.91; H 4.38; N 38.71; found C 56.80, H
4.42, N 38.77.
Method B. A mixture of aminotriazole 11a (0.01 mol,
0.84 g) and enaminonitrile 1d (0.01 mol, 2.57 g) was heated
in a microwave oven for 6 min. The same work up pro-
cedure as mentioned above was used. Yield; 88%; m. p.
185 – 187 ◦C. – IR (KBr): ν = 3340 (NH2), 1578, 1366
(NO2) cm−1. – 1H NMR (300 MHz): δ = 6.60 (s, 2 H, NH2),
7.45 (d, 2 H, J = 10 Hz, Ar-H), 7.75 (d, 2 H, J = 10 Hz, Ar-
H), 7.89 (s, 1 H, 2-H), 8.68 (s, 1 H, 5-H). – MS (EI, 70 eV):
m/z (%) = 256 (74) [M]+. – C11H8N6O2 (256.22): calcd. C
51.56, H 3.15, N 32.80; found C 51.60, H, 3.00, N 32.95.
3,6-Di(2-phenyldiazenyl)pyrazolo[1,5-a]pyrimidine-2,7-
diamine (10)
A cold solution of benzenediazonium chloride (0.01 mol)
was prepared by adding a solution of sodium nitrite (0.01 mol
in 2 mL of H2O) to a cold solution of the aniline in con-
centrated hydrochloric acid with stirring. The resulting solu-
tion of the benzenediazonium chloride was added to a cold
solution of 7 in ethanol (50 mL) containing sodium acetate
(5 g). The reaction mixture was stirred at room temperature
for 30 min. The solid product formed was collected by filtra-
4-(4-Nitrophenyl)-1H-pyrazol-3-amine (14a)
Method A. A mixture of 1d (0.01 mol, 2.57 g) and
tion, washed with water and crystallized from ethanol. Yield hydrazine hydrate (0.01 mol) in DMF (15 mL) was re-
81%; m. p. 162 – 163 ◦C. – IR (KBr): ν = 3360 (NH2) cm−1
.
fluxed for 3 h. The reaction mixture was left to cool to

180
A. M. Salaheldin – K. S. Khairou · Studies with Enamines
room temperature, and the solid formed was collected Ethyl 7-methyl-3-(4-nitrophenyl)pyrazolo[1,5-a]pyrimidine-
by filtration and crystallized from ethanol yield (yield 6-carboxylate (17)
60%).
A
mixture of 14a (0.01 mol, 2.04 g), DMF-DMA
Method B. A mixture of enaminonitrile 1d (0.01 mol,
2.57 g) and hydrazine hydrate (0.01 mol) in DMF (10 mL)
was heated in a microwave oven for 5 min and the prod-
uct worked up as mentioned above. Yield 85%; m. p.
184 – 186 ◦C. – IR (KBr): ν = 3340 (NH2), 3280 (NH),
1565, 1360 (NO2) cm−1. – 1H NMR (300 MHz): δ = 7.69
(d, 2 H, J = 9 Hz, Ar-H), 7.82 (s, 2 H, NH2), 8.15 (s, 1 H,
NH), 8.22 (d, 2 H, J = 9 Hz, Ar-H), 8.32 (s, 1 H, pyrazole-H).
– MS (EI, 70 eV): m/z (%) = 204 (55) [M]+. – C9H8N4O2
(204.19): calcd. C 52.94, H 3.95, N 27.44; found C 52.90, H
4.05, N 27.40.
(0.01 mol) and ethyl acetoaceate (0.01 mol) in pyridine
(25 mL) was refluxed for 3 h. The reaction mixture was left to
cool to room temperature, and the solid formed was collected
by filtration and crystallized from ethanol. Yield 69%; m. p.
218 – 220 ◦C. – IR (KBr): ν = 1708 (CO), 1570, 1355 (NO2)
cm−1. – H NMR (300 MHz): δ = 1.12 (t, 3 H, J = 7.5 Hz,
1
CH3), 2.32 (s, 3 H, CH3), 4.18 (q, 2 H, J = 7.5 Hz, CH2),
7.45 (d, 2 H, J = 9 Hz, Ar-H), 7.92 (d, 2 H, J = 9 Hz, Ar-
H), 8.22 (s, 1 H, 2-H), 8.52 (s, 1 H, 5-H). – MS (EI, 70 eV):
m/z (%) = 326 (64) [M]+. – C16H14N4O4 (326.32): calcd. C
58.89, H 4.32, N 17.17; found C 58.80, H 4.35, N 17.25.
Ethyl 4-methyl-8-substituted
pyrazolo[5,1-c][1,2,4]-triazine-3-carboxylates (16a, b)
3-(4-Nitrophenyl)-7-thiophen-2-yl-pyrazolo[1,5-
a]pyrimidine (19)
A mixture of 14a (0.01 mol, 2.04 g) and enaminone 18
(0.01 mol, 1.81 g) in pyridine (25 mL) was refluxed for 3 h.
The reaction mixture was left to cool to room tempera-
ture, and the solid formed was collected by filtration and
crystallized from ethanol to afford 19. Yield 62%; m. p.
250 – 251 ◦C. – IR (KBr): ν = 2985 (CH Ar), 1565, 1370
(NO2), cm−1. – 1H NMR (300 MHz): δ = 7.0 – 7.31 (m, 3
H, thiophene-H), 7.45 (d, 2 H, J = 9 Hz, Ar-H), 7.55 (d, 1
H, J = 7 Hz, 6-H), 8.23 (d, 2 H, J = 9 Hz, Ar-H), 8.66 (s,
1 H, 2-H), 8.80 (d, 1 H, J = 7 Hz, 5-H). – MS (EI, 70 eV):
m/z (%) = 322 (74) [M]+. – C16H10N4O2S (322.24): calcd.
C 59.62, H 3.13, N 17.38, S 9.95; found C 59.50, H 3.20, N
17.35, S 10.0.
A cold solution of pyrazolediazonium chloride (0.01 mol)
was prepared by adding a solution of sodium nitrite (0.01 mol
in 2 mL of H2O) to a cold solution of the aminopyrazole
14a in concentrated hydrochloric acid with stirring. The
resulting solution of the pyrazolediazonium chloride was
added to a cold solution of ethyl acetoacetate in ethanol
(50 mL) containing sodium acetate (5 g). The reaction
mixture was stirred at room temperature for 30 min. The
solid product formed was collected by filtration, washed
with water and crystallized from ethanol to afford 16a,
b.
Ethyl 4-methyl-8-(4-nitrophenyl)pyrazolo[5,1-c]-
[1,2,4]triazine-3-carboxylate (16a)
3-(4-Nitrophenyl)-pyrazolo[1,5-a]pyrimidin-7-ylamine (20)
Yield 68%; m. p. 223 – 225 ◦C. – IR (KBr): ν = 1705
(CO) 1560, 1367 (NO2) cm−1. – 1H NMR (300 MHz):
δ = 1.18 (t, 3 H, J = 7.5 Hz, CH3), 2.32 (s, 3 H, CH3), 4.20
(q, 2 H, J = 7.5 Hz, CH2), 7.20 (d, 2 H, J = 10 Hz, Ar-H),
8.18 (d, 2 H, J = 10 Hz, Ar-H), 8.32 (s, 1 H, H-7). – MS (EI,
70 eV): m/z (%) = 327 (90) [M]+. – C15H13N5O4 (327.29):
calcd. C 55.05, H 4.00, N 21.40; found C 54.95, H 4.10, N
21.20.
A mixture of 14a (0.01 mol, 2.04 g) and enaminonitrile
1a (0.01 mol, 1.36 g) in pyridine (25 mL) was refluxed for
3 h. The reaction mixture was left to cool to room temper-
ature, and the solid formed was collected by filtration and
crystallized from ethanol to afford 20. Yield 77%; m. p.
160 – 162 ◦C. – IR (KBr): ν = 3350 (NH2) 1560, 1365 (NO2)
cm−1. – 1H NMR (300 MHz): δ = 6.59 (d, 1 H, J = 7 Hz,
6-H), 7.15 (s, 2 H, NH2), 7.55 (d, 2 H, J = 10 Hz, Ar-H),
8.16 (d, 2 H, J = 10 Hz, Ar-H), 8.33 (d, 1 H, J = 7 Hz, 5-
H), 8.49 (s, 1 H, 2-H). – 13C NMR (75.4 MHz): δ = 95.9
(C-6), 102.2 (C-3), 122.36 (C-30,50),132.30 (C-20,60), 134.10
(C-3a), 135.20 (C-10), 137.8 (C-2), 146.10 (C-40), 148.7 (C-
7), 155.5 (C-5). – MS (EI, 70 eV): m/z (%) = 255 (80) [M]+.
– C12H9N5O2 (255.23): calcd. C 56.47, H 3.55, N 27.44;
found C 56.40, H 3.50, N, 27.55.
Ethyl 4-methyl-8-phenyl
pyrazolo[5,1-c][1,2,4]triazine-3-carboxylate (16b)
Yield 78%; m. p. 202 – 203 ◦C. – IR (KBr): ν = 1690
(CO) cm−1. – 1H NMR (300 MHz): δ = 1.15 (t, 3 H,
J = 7.5 Hz, CH3), 2.30 (s, 3 H, CH3), 4.10 (q, 2 H,
J = 7.5 Hz, CH2), 7.20 – 7.45 (m, 5 H, Ar-H), 8.25 (s, 1
H, H-7). – MS (EI, 70 eV): m/z (%) = 282 (98) [M]+. –
C15H14N4O2 (282.30): calcd. C 63.82, H 5.00, N 19.85;
found C 63.70, H 4.90, N 19.90.
Acknowledgement
We are grateful to Prof. M. H. Elnagdi for continuous help
and critical comments on research progress.

A. M. Salaheldin – K. S. Khairou · Studies with Enamines
181
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