Product and Mechanism of Gas-phase Pyrolysis of 2-arylidinehydrazinopyrimidines: Interesting Route to Condensed Heterocycles [1]

Article abstract of DOI:10.1002/jhet.2276

Gas-phase pyrolysis of N-arylidine-N′-pyrimidin-2-yl-hydrazine derivatives 1a, 1b, 1c, 1d, 1e gave the corresponding arylnitriles 2a, 2b, 2c, 2d, 2e, 2-aminopyrimidine 3, 3-phenyl-1,2,4-triazolo[4,3-a]pyrimidines 4, 2-phenyl-1,2,4-triazolo[1,5-a]pyrimidines 5, 2,4,5-triphenyl-1H-imidazole 6, and 2,3-diphenylquinoline 7. The analyses of the reaction products are reported and used to elucidate the mechanism of the pyrolytic process.

Full text of DOI:10.1002/jhet.2276

Month 2014
Product and Mechanism of Gas-phase Pyrolysis of 2-
arylidinehydrazinopyrimidines: Interesting Route to Condensed
Heterocycles[1]
*
Sundus A. Al-Awadi, Maher R. Ibrahim, Osman M. E. El-Dusouqui, and Nouria A. Al-Awadi
Chemistry Department, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait
*
E-mail: n.alawadi@ku.edu.kw
Received December 3, 2013
DOI 10.1002/jhet.2276
Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
Gas-phase pyrolysis of N-arylidine-N′-pyrimidin-2-yl-hydrazine derivatives 1a–e gave the corresponding
arylnitriles 2a–e, 2-aminopyrimidine 3, 3-phenyl-1,2,4-triazolo[4,3-a]pyrimidines 4, 2-phenyl-1,2,4-triazolo
[1,5-a]pyrimidines 5, 2,4,5-triphenyl-1H-imidazole 6, and 2,3-diphenylquinoline 7. The analyses of the re-
action products are reported and used to elucidate the mechanism of the pyrolytic process.
J. Heterocyclic Chem., 00, 00 (2014).
INTRODUCTION
nature of the heterocyclic ring [15–18]. Here, we report
the results of a mechanistic investigation of the FVP and
STP reactions of substituted N-arylidine-N′-pyrimidin-2-
yl-hydrazines 1a–e in which the arylidenediaza substituent
is on a ring carbon atom of the nitrogen heterocycle. This
feature and the nature of the pyrimidine ring account for
the useful condensed heterocyclic compounds obtained in
the elimination process.
Gas-phase pyrolysis provides a useful alternative syn-
thetic strategy for the preparation of novel condensed
heterocycles. Many valuable heterocyclic compounds
of synthetic importance and potential biological,
pharmaceutical, and industrial applications have been
prepared using the two major gas-phase pyrolysis
methodologies: static (sealed-tube) pyrolysis (STP) and
flash vacuum pyrolysis (FVP) [2–8]. Both processes
are conducted at low pressure, while FVP is further
characterized by relatively short (millisecond) substrate
residence time [3,6,9]. We have used both STP and
FVP in the study of the kinetics and mechanism of
gas-phase pyrolysis reactions, and have also provided
extensive data on thermal gas-phase reactivity to furnish
added support for proposed mechanisms and reference
models for theoretical studies [4–6]. It is to be noted
in this respect that no reagents, solvents, or catalysts
are used in these reactions [9–14].
RESULTS AND DISCUSSION
Products and mechanism. Reaction products from the
complete gas-phase pyrolysis of N-arylidine-N′-pyrimidin-
2-yl-hydrazines 1a–e were obtained at optimal STP
reaction conditions of temperature, pressure, and substrate
residence time (~900 s) compatible with ≥98% reaction as
evidenced by HPLC analysis of the pyrolysates. The
products of FVP of 1a–e at 700°C and 0.02Torr (~10 ms
residence time) were separated and directly collected in a
U-shaped trap cooled in liquid nitrogen, and analyzed by
1HNMR spectroscopy and LCMS. The elimination
products from FVP consisted of arylnitriles 2a–e and 2-
aminopyrimidine 3 in yields of ~75% and 80% ( 10%),
respectively (Table 1). A plausible mechanism to explain
the elimination products of FVP is shown (Scheme 1). It
is suggested that the amine tautomer (A) of substrate 1a–e
Earlier, we have used N-substituted cyclic amides,
thioamides, and related nitrogen heterocycles as substrates
in thermal gas-phase elimination reactions to prepare
condensed heterocyclic compounds. These reactions were
found to proceed via a six-membered transition state (TS)
with elimination of arylnitriles, and with rates and products
of reaction being affected by structural factors and by the
© 2014 HeteroCorporation

S. A. Al-Awadi, M. R. Ibrahim, O. M. E. El-Dusouqui, and N. A. Al-Awadi
Vol 000
Table 1
Pyrolysis products and percent (%) yields of FVP of 1a–e and STP of 1a.
Pyrolysis products and % yield
Subs.
X
Cond.
2a–e
3
4
5
6
7
Subs.
1a
H
(i)
78
25
15
76
28
86
27
81
35
78
23
85
28
18
75
32
80
22
83
25
80
26
—
—
15
—
—
—
—
—
—
—
—
—
—
17
—
—
16
—
—
—
—
—
—
—
—
—
—
10
—
45
—
—
38
—
44
—
50
—
54
(ii)
(iii)
(i)
(ii)
(i)
(ii)
(i)
(ii)
(i)
1b
1c
1d
1e
Cl
OCH3
CH3
NO2
(ii)
(i) Flash vacuum pyrolysis (FVP): 700°C, 0.02 Torr; (ii) static pyrolysis (STP): 300°C, 0.02 Torr, 30 min; (iii) STP: 350°C, 0.02 Torr, 60 min.
Scheme 1. Pathway of flash vacuum pyrolysis (FVP) reaction of 2-arylidinehydrazinopyrimidines 1a–e.
pyrolyzes to give the two major elimination fragments via a
six-membered (TS), reported earlier for the FVP of
compatible heterocycles [4]. An alternative pathway
involves the fragmentation at the (N–N) bond of the imine
tautomer (B) to give reactive radical intermediates, which
exchange hydrogen to form the elimination fragments [4–6].
This pathway is evident from analysis of the mechanism
proposed for the STP process and the products of pyrolysis
therefrom (Fig. 1). Formation of radicals during FVP has
been reported in a wide range of reactions [4,7,11,18,19].
The products of complete pyrolysis from the STP reaction
of the substrates under study (Fig. 1) were collected and
separated by column chromatography using silica gel and
ethyl acetate/petroleum ether (60–80) as eluent (5–25% ethyl
acetate). The pyrolysates were analyzed qualitatively and
quantitatively by GC–MS, LCMS, 1H, 13C NMR, and X-ray
crystallography obtained for compound 5a (Fig. 2). Thus,
substrate 1a pyrolyzed to give benzonitrile, 2 (15%),
2-aminopyrimidine, 3 (18%), 3-phenyl-1,2,4-triazolo[4,3-a]
pyrimidine, 4 (15%), 2-phenyl-1,2,4-triazolo[1,5-a]pyrimi-
dine, 5 (17%), 2,4,5-triphenyl-1H-imidazole, 6 (16%), and
2,3-diphenylquinoline, 7 (10%), as shown in Figure 1 and
Table 1. The difference in residence time (ms vs. min) seems
to be crucial as to the qualitative and quantitative nature and
distribution of the products of FVP and STP reactions.
Scheme 2 illustrates plausible mechanistic routes to ex-
plain the formation of the products of pyrolysis 2–7 in the
STP reaction of compound 1a. It has already been shown
Figure 1. STP products of 1a.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Product and Mechanism of Gas-phase Pyrolysis of 2-arylidinehydrazinopyrimidines:
Interesting Route to Condensed Heterocycles
Scheme 3. Oil-bath static pyrolysis of 4a,b: Dimroth rearrangement.
hours to produce 4a,b in 70–75% yield [20]. Heating com-
pounds 4a,b in an oil bath at 220°C for 20min gave 2-aryl-
1,2,4-triazolo[1,5-a]pyrimidines 5a,b through Dimroth
rearrangement, Scheme 3 [22].
According to Scheme 2, the cynoarene 2 arises from colli-
gation of the diradical centers 8, while compound 3 is
obtained when the intermediate 9 captures hydrogen [23].
The structural and electronic effects associated with the six-
membered (TS) and the radical pathway suggested for the
FVP and STP processes have been outlined and discussed
in an earlier report [23].
Figure 2. X-ray crystal structure of 5a. [Color figure can be viewed in the
online issue, which is available at wileyonlinelibrary.com.]
Scheme 2. Mechanism of static pyrolysis (STP) reaction of 1a.
CONCLUSION
The present study offers interesting new routes toward con-
densed heterocyclic compounds. The study also provides
comparison between FVP and STP reactions of 2-
arylidinehydrazinopyrimidine derivatives, which shows that
FVP gave similar products to those obtained from sealed-tube
STP and also different products because of further pyrolysis
arising from the longer residence time in (STP) reactions.
EXPERIMENTAL
General. Melting points were measured using a Gallenkamp
apparatus. IR spectra in KBr were recorded on a Perkin-Elmer
System 2000 FTIR spectrophotometer. 1H and 13C NMR
spectra were recorded on Bruker DPX 400MHz super-conducting
NMR spectrometers. LCMS were measured using an Agilent
1100 series LC/MSD with an API-ES/APCI ionization mode.
Mass spectra were recorded on VG Auto-spec-Q (high resolution,
high performance, tri-sector GC/MS/MS). Microanalyses were
performed on a LECO CH NS-932 Elemental Analyzer.
(Scheme 1) that the imine tautomer (B) of substrates 1a–e
dissociates under the conditions of FVP (700°C, 0.02Torr,
ms residence time) at the (N–N) bond of the substrate to
produce two radical intermediates, which exchange hydro-
gen to give compounds 2 and 3. On the other hand, substrate
pyrolysis under STP reaction conditions (350°C, 0.02 Torr,
60min residence time) results in the formation of compound
4, which either isomerizes to 5 or decomposes into the
diradical intermediates 8 and 9. Radical 9 captures (H2) to
form 2-aminopyrimidine 3, while radical 8 either cyclizes
to produce benzonitrile 2 or captures (H2) molecule to form
an imine 10. Colligation of three units of the imine 10 leads
to the formation of arylimarine 11. The latter has been
reported to yield 2,4,5-triphenyl-1H-imidazole 6 by the
elimination of hydrogen [20]. The intermediate 11 could
alternatively cyclize to give 12, which on loss of (NH3)
would form 2,3-diphenylquinoline 7.
General procedure for the synthesis of compounds 1a–e.
A
mixture of 2-hydrazinopyrimidine [24] (1.1 g, 10 mmol), the
appropriate aromatic aldehyde (12.0 mmol), and sodium acetate
(1.2 g, 15 mmol) in glacial acetic acid (25 mL) was heated under
reflux for 30 min. After cooling, ice water (50 mL) was added to
the reaction mixture; the precipitate so formed as a colorless
solid was collected and crystallized from ethanol to give 1a–e
N-Benzylidene-N′-pyrimidin-2-yl-hydrazine 1a. Yield: 1.5 g
(75%); mp 176–178°C ([25] mp 177°C). MS: m/z (%) = 198
(M+, 25), 95 (100). 1H NMR (CDCl3): δ 8.94 (br, 1H, NH),
8.49 (d, 2H, J = 4.8 Hz), 7.94 (s, 1H), 7.56 (d, 2H, J = 7.8 Hz),
7.36 (m, 3H), 6.78 (t, 1H, J = 4.8 Hz).13C NMR (CDCl3): δ
159.8, 158.6, 143.0, 134.0, 129.7, 128.6, 127.2, 113.4. Anal.
Calcd. for C11H10N4 (198.2): C 66.65; H 5.08; N 28.26.
Found: C 66.51; H 5.11; N 28.13.
N-P-Chlorobenzylidene-N′-pyrimidin-2-yl-hydrazine 1b. Yield:
1.8 g (77%); mp 210–212°C ([26] mp 212–214°C). MS: m/z
In a separate experiment, compounds 1a,b were oxidized
with Br2 by refluxing the mixture in acetic acid for three
1
(%) = 232 (M+, 30), 95 (100). H NMR (CDCl3): δ 8.74 (br, 1H,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

S. A. Al-Awadi, M. R. Ibrahim, O. M. E. El-Dusouqui, and N. A. Al-Awadi
Vol 000
NH), 8.50 (d, 2H, J = 4.8 Hz), 7.89 (s, 1H), 7.69 (d, 2H, J = 8.4 Hz),
7.36 (d, 2H, J = 8.4 Hz), 6.81 (t, 1H, J = 4.8 Hz). 13C NMR (DMSO-
d6) δ 159.6, 158.6, 141.4, 135.4, 132.6, 128.9, 128.3, 113.7. Anal.
Calcd. for C11H9ClN4 (232.7): C 56.78; H 3.90; N 24.08. Found:
C 56.59; H 3.81; N 24.03.
N-P-Methoxybenzylidene-N′-pyrimidin-2-yl-hydrazine 1c. Yield:
1.7 g (74%); mp 138–40. IR: 3441, 3214, 3037, 2921, 1580, 1542,
1447, 1408, 1266, 1129, 922, 786. LCMS: m/z = 229 (M + 1). MS:
m/z (%) = 228 (M+, 75), 133 (100). 1H NMR (CDCl3): δ 8.87 (br,
1H, NH), 8.47 (d, 2H, J = 4.8 Hz), 7.88 (s, 1H), 7.69 (d, 2H,
J = 8.8 Hz), 6.90 (d, 2H, J = 8.8 Hz), 6.75 (t, 1H, J = 4.8 Hz), 3.84
(s, 3H, OCH3). 13C NMR (CDCl3) δ 159.8, 158.6, 142.9, 1302,
128.7, 126.8, 114.0, 113.1, 55.5. Anal. Calcd. for C12H12N4O
(228.3): C 63.15; H 5.30; N 24.55. Found: C 63.09; H 5.21; N
24.43 [26].
HPLC studies. The reaction products were separated by column
chromatography using Merck Al-silica gel 60 F254 with ethyl
acetate/petroleum ether (60–80) to give successively 2, 7, 3, 4, 5,
and 6. The static sealed-tube (STP) pyrolysis was conducted in a
custom-made Chemical Data System pyrolyser consisting of an
aluminum block with a groove to accommodate the Pyrex sealed-
tube reactor, and fitted with a platinum-resistance thermometer
and thermocouple connected to
a Comark microprocessor
thermometer. The block temperature was controlled by
a
Eurothem 093 precision temperature regulator. Aluminum was
chosen for its low temperature gradient and resistance to elevated
temperatures.
Oil-bath Static Pyrolysis of 4a,b: Dimroth Rearrangement. A
sample of the substrate 4a or 4b (1 mmol) was introduced in the
reaction tube (1.5 × 12 cm Pyrex) and placed in an oil bath at 220°C
for 20 min. After cooling, CDCl3 was added and the mixture was
analyzed using 1H-NMR and LCMS, and each mixture was
shown to comprise 5a and 5b, respectively [21].
N-P-Toludine-N′-pyrimidin-2-yl-hydrazine 1d. Yield: 1.7 g
(80%); mp 160–162°C. IR: 3453, 3208, 3035, 2927, 1601, 1541,
1507, 1410, 1300, 1246, 1171, 1025, 831. LCMS: m/z = 213
(M + 1). MS: m/z (%) = 212 (M+, 25), 95 (100). 1H NMR (CDCl3):
δ 8.82 (br, 1H, NH), 8.49 (d, 2H, J= 4.5 Hz), 7.90 (s, 1H), 7.66 (d,
2H, J= 8.4 Hz), 7.19 (d, 2H, J= 8.4 Hz), 6.77 (t, 1H, J=4.5Hz),
2.38 (s, 3H). 13C NMR (CDCl3): δ 159.8, 158.6, 143.2, 139.9,
131.3, 129.3, 127.2, 113.3, 21.5. Anal. Calcd. for C12H12N4
(212.3): C 67.91; H 5.70; N 26.40. Found: C 67.83; H 5.64; N 26.33.
N-P-Nitrobenzylidene-N′-pyrimidin-2-yl-hydrazine 1e. Yield:
2.0 g (82%); mp 250–52°C. IR: 3442, 3187, 3037, 2931, 1575,
1514, 1449, 1408, 1334, 1269, 1143, 1106. LCMS: m/z = 244
Benzonitrile 2a.
spectroscopic data identical to that reported in the literature [28a].
LCMS: m/z = 104 (M+ 1). 1H NMR
p-Chlorobenzonitrile 2b.
LCMS: m/z = 139, 138 (M + 2,
M + 1).1H NMR spectroscopic data identical to that reported in
the literature [29b].
p-Methoxybenzonitrile 2c.
LCMS: m/z = 134 (M + 1). 1H
NMR spectroscopic data identical to that reported in the
literature [29c].
p-Tolunitrile 2d.
LCMS: m/z = 118 (M + 1). 1H NMR
spectroscopic data identical to that reported in the literature [29d].
p-Nitrobenzonitrile 2e. LCMS: m/z = 149 (M + 1). 1H NMR
spectroscopic data identical to that reported in the literature [29e].
2-Aminopyrimidine 3. Yellow solid, mp 123–25°C ([29f] mp
126°C). MS m/z (%) = 95 (M+ 90). 1H NMR (CDCl3): δ 8.29
(d, 2H, J = 5.2 Hz), 6.61 (t, 1H, J = 5.2 Hz). 5.17 (br, 2H, NH2).
13C NMR (CDCl3): δ 163.5, 153.0, 111.0.
1
(M + 1). MS: m/z (%) = 243 (M+, 20), 95 (90). H NMR (CDCl3):
δ 11.67 (br, 1H, NH), 8.52 (d, 2H, J= 4.8 Hz), 8.25 (d, 2H,
J= 8.8 Hz), 8.23 (s, 1H), 7.90 (d, 2H, J= 8.8 Hz), 6.92 (t, 1H,
J=4.8Hz). 13C NMR (CDCl3): δ 160.1, 159.0, 142.2, 139.4,
130.1, 127.5, 124.6, 114.3. Anal. Calcd. for C11H9N5O2 (242.2): C
54.32; H 3.73; N 28.79. Found: C 54.30; H 3.69; N 28.83.
Oxidation of compounds 1a,b with Br2, synthesis of compounds
4a,b. A mixture of each of compounds 1a,b (10 mmol) and Br2
(1 ml, 12 mmol) in acetic acid (30 ml) was heated under reflux for
3–4 h. After cooling, ice water (50 mL) was added to the reaction
mixture; the precipitate so formed was collected and crystallized
from ethanol to give 4a,b.
3-Phenyl-1,2,4-triazolo[4,3-a]pyrimidine 4a.Colorless solid, mp
201–203°C, ([30] mp 182–184°C). MS m/z (%) = 196 (M+, 100),
1
170 (25). H NMR (CDCl3): δ 8.92 (dd, 1H, J= 6.8, 1.6 Hz), 8.85
(dd, 1H, J= 6.8, 1.6 Hz), 8.35 (m, 2H), 7.54–7.50 (m, 3H), 7.18
(dd, 1H, J= 6.8, 1.8 Hz). 13C NMR (CDCl3) δ 156.5, 155.2, 148.4,
135.5, 131.5, 130,2, 128.8, 128.0, 112.1. Anal. Calcd. for C11H8N4
(196.2): C 67.34; H 4.11; N 28.55. Found: C 67.30; H 4.10; N 28.48.
3-p-Chlorophenyl-1,2,4-triazolo[4,3-a]pyrimidine 4b. Colorless
solid, Yield 75%, mp 195–197°C ([31] mp 198–199°C). MS m/z
Pyrolysis product. FVP of Compounds 1a–e. In the FVP
process, the substrate was volatilized from a tube in a Büchi
Kugelrohr oven through a 30× 2.5 cm horizontal fused quartz
tube. This was heated externally by a Carbolite Eurotherm tube
furnace MTF-12/38A to a temperature of 700°C, the temperature
being monitored by a Pt/Pt-13%Rh thermocouple situated at the
center of the furnace. The products were collected in a U-shaped
trap cooled in liquid nitrogen. The whole system was maintained
at a pressure of 0.02 Torr by an Edwards Model E2M5 high
capacity rotary oil pump, the pressure being measured by a Pirani
gauge situated between the cold trap and pump. Under these
conditions, the contact time in the hot zone was estimated to be
~10 ms. The different fractions of the product collected in the U-
shaped trap were analyzed by 1H. 13C NMR spectroscopy and
percent yields were determined from 1H-NMR [28].
1
(%) = 231 (M+1 , 40), 173 (35). H NMR (CDCl3): δ 8.99 (d, 1H,
J= 3.6 Hz), 8.52 (d, 1H, J= 3.6 Hz), 8.30 (d, 2H, J=8.4Hz), 7.50
(d, 2H, J= 8,4 Hz), 7.18 (t, 1H, J=3.6Hz). 13C NMR (CDCl3):
δ 164.2, 155.9, 137.7, 135.8, 129.7, 129.6, 129.1, 111.6.
2-Phenyl-1,2,4-triazolo[1,5-a]pyrimidine 5a. Colorless solid, mp
184–185°C, ([27] mp 184–184.5°C). IR: 3086, 3025, 1617, 1509,
1417, 1346, 1228, 768. MS: m/z (%) = 196 (M+ 100), 170 (25). 1H
NMR (CDCl3): δ 8.87 (dd, 1H, J= 6.8, 2.0 Hz), 8.81 (dd, 1H,
J= 4.0, 2.0 Hz), 8.37–8.33 (m, 2H), 7.54–7.50 (m, 3H), 7.11
(dd, 1H, J=6.8, 1.6Hz). 13C NMR (CDCl3): δ 166.4, 156.2, 154.4,
135.5, 130.8, 130,2, 128.8, 127.6, 109.9. Anal. Calcd. for C11H8N4
(196.2): C 67.34; H 4.11; N 28.55. Found: C 67.27; H 4.01; N 28.43.
2-p-Chlorophenyl-1,2,4-triazolo[1,5-a]pyrimidine 5b.
Colorless
solid from ethanol, mp 248–249°C ([30] mp 243–244.5°C). MS m/z
STP of 1a. A sample of the substrate (0.24 g, 12 mmol) was
introduced in the reaction tube (1.5 × 12 cm Pyrex), cooled in liquid
nitrogen, sealed under vacuum (0.02 Torr), and placed in the
pyrolyzer for 60 min at 350°C, a temperature that is required for
complete pyrolysis of the substrate as indicated by preliminary
1
(%) = 230 (M+ 100), 170 (25). H NMR (CDCl3): δ 9.07 (dd, 1H,
J= 3.8, 1.2 Hz), 8.87 (dd, 1H, J= 3.8, 1.2 Hz), 8.27 (d, 2H, J=8.0Hz),
7.52 (d, 2H, J= 8.0 Hz), 7.15 (dd, 1H, J=6.8, 1.6Hz). 13C NMR
(CDCl3): δ 165.7, 155.6, 154.8, 137.1, 135.6, 129,1, 128.9, 110.3.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Product and Mechanism of Gas-phase Pyrolysis of 2-arylidinehydrazinopyrimidines:
Interesting Route to Condensed Heterocycles
[9] (a) Al-Awadi, N. A.; Kaul, K.; El-Dusouqui, O. M. E. Can J
Chem 1998, 76, 1922; (b) Al-Awadi, N. A.; Elnagdi, M. H.; Ilingovan, S.;
El-Dusouqui, O. M. E. J Phys Org Chem 1999, 12, 654.
[10] Lancaster, M. Green Chemistry; R.S.C: Cambridge, 2002.
[11] Al-Awadi, H.; Ibrahim, M. R.; Al-Awadi, N. A.; Ibrahim, Y. A.
Tetrahedron 2007, 63, 12948.
2,4,5-Triphenyl-1H-imidazole 6. White solid, mp 274–276°C
([20] mp 274–275°C). LCMS: m/z =297 (M+1). MS: m/z (%) = 296
(M+, 100), 190 (10), 165 (85). IR: 3395, 3061, 2928, 1756, 1639,
1
1503, 1435, 1240, 1148, 1034, 736. H NMR (DMSO-d6): δ 12.68
(br, 1H, NH), 8.08 (dd, 2H, J 8.4, 1.2 Hz), 7.55 (dd, 2H, J=8.4,
1.6Hz), 7.50 (dt, 2H, J= 7.4, 1.2 Hz), 7.45 (d, 2H, J=7.8Hz), 7.43
(d, 2H, J= 7.8 Hz), 7.38 (dt, 2H, J= 7.8, 1.2 Hz), 7.30 (t, 2H,
J=7.8Hz), 7.22 (t, 1H, J=7.2Hz). 13C NMR (DMSO-d6): δ 145.9,
137.5, 135.6, 131.5, 130.8, 129.2, 129.1, 128.9, 128.73, 128.71,
128.6, 128.3, 127.5, 126.9, 125.6. Anal. Calcd. for C21H16N2
(296.4): C 85.11; H 5.44; N 9.45. Found: C 85.09; H 5.31; N 9.45.
2,3-Diphenylquinoline 7. Yellow solid, mp 86–88°C ([32] mp
[12] (a) Al-Juwaiser, I. A.; Al-Awadi, N. A.; El-Dusouqui, O. M. E.
Can
J Chem 2002, 80, 499; (b) Al-Awadi, S. A.; Abdallah, M. R.;
Dib, H. H.; Ibrahim, M. R.; Al-Awadi, N. A.; El-Dusouqui, O. M. E.
Tetrahedron 2005, 61, 5769.
[13] (a) Xue, Y.; Lee, K. A.; Kim, C. K. Bull Korean Chem Soc
2003, 24, 853; (b) Zhang, S.-W.; Wang, Y.; Feng, W.-L. J Mol Struct
(Theochem) 1999, 488, 29; (c) Feng, W.-L.; Wang, Y.; Zhang, S.-W.
Int J Quantum Chem 1997, 62, 297.
[14] (a) Perez, I. R.; Lorono, M.; Dominguez, R. M.; Cordova, T.;
Chuchani, G. J Phys Org Chem 2008, 21, 402; (b) Notario, R.; Quijano, J.;
Leon, L. A.; Sanchez, C.; Quijano, J. C.; Alarcon, G.; Chamorro, E.;
Chuchani, G. J Phys Org Chem 2003, 16, 166.
[15] Al-Awadi, N. A.; Ibrahim, Y. A.; Kaul, K.; Dib, H. H. J Phys
Org Chem 2001, 14, 521.
1
88–89°C), MS: m/z (%) = 281 (M+, 100), 252 (15), 139 (20). H
NMR (CDCl3): δ 8.18 (dd, 1H, J= 8.4, 1.2 Hz), 8.10 (s, 1H), 8.06
(d, 1H, J= 8.4 Hz), 7.86 (d, 1H, J= 8.4 Hz), 7.74 (dd, 2H, J=8.2,
1.2 Hz), 7.61 (dt, 1H, J= 7.2, 1.2 Hz), 7.48 (t, 2H, J=7.8Hz),
7.44–7.38 (m, 5H), 7.33 (t, 1H, J=7.8Hz). 13C NMR (CDCl3): δ
158.5, 147.6, 140.9, 139.8, 137.8, 134.5, 130.1, 129.7, 129.4,
129.2, 128.3, 128.0, 127.3, 127.2, 127.1, 126.9, 126.6
(HRMS = 281.1196, requires C21H15N 281.1204).
[16] Al-Etabi, A.; Abdallah, M. R.; Al-Awadi, N. A.; Ibrahim, Y. A.;
Hasan, M. J Phys Org Chem 2004, 17, 49.
[17] Al-Awadi, N. A.; Ibrahim, Y. A.; Dib, H. H.; Kaul, K. J Phys
Org Chem 2002, 15, 324.
[18] George, B. J.; Dib, H. H.; Abdalla, M. R.; Ibrahim, M. R.; Khalil,
N. S.; Ibrahim, Y. A.; Al-Awadi, N. A. Tetrahedron 2006, 62, 1182.
[19] Caogen, G. I.; Hickson, C. L.; McNab, H. Tetrahedron 1986,
42, 2135.
[20] Chou, C.-H.; Chu, L.-S.; Chiu, S.-J.; Lee, C.-F.; She, Y.-T.
Tetrahedron 2004, 60, 6581.
[21] Kovalenko, S. I.; Antypenko, L. M.; Bilyi, A. K.; Kholodnyak, S. V.;
Karpenko, O. V.; Antypenko, O. M.; Mykhaylova, N. S.; Los, T. I.;
Kolomoets, O. S. Sci Pharm 2013, 81, 359.
Acknowledgments. The support of the University of Kuwait received
through research grant # Sc 03/06 and the facilities of ANALAB
and SAF (grants # GS01/01, GS02/01, GS01/04) is gratefully
acknowledged. One of the authors (Sundus, A. Al-awadi)
acknowledges the support of the Collage of Graduate studies.
REFERENCES AND NOTES
[22] Brown, D. J.; Nagamatsu, T. Aust J Chem 1977, 30, 2515.
[23] Ibrahim, M. R.;Al-Azemi, T. F.;Al-Etabi, A.;El-Dusouqui, O. M. E.;
Al-Awadi, N. A. Tetrahedron 2010, 66, 4243.
[24] Kenzo, S.; Shoich, B.; Masahiko, Y. Yakugaku Zasshi 1953,
73, 598.
[1] Crystallographic data have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication # CCDC
934246. Copies of the data can be obtained free of charge, on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, (fax: +44-(0)1223-
336033 or e-mail: deposit@ccdc.cam.ac.Uk.
[25] Thiel, O. R.; Achmatowicz, M. M.; Reichelt, A.; Larsen, R.
Ang Chem Int Ed 2010, 49, 8395.
[2] Brown, R. F. Pyrolytic Methods in Organic Chemistry;
Academic Press: London, 1980.
[26] Alina, A.; Valentin, B.; Rodica, M.; Remus, N. Revista de
Chemie 2005, 56, 418.
[3] Schiess, P. Thermochimica Acta 1987, 112, 31.
[4] Al-Awadi, N. A.; George, B.; Dib, H. H.; Ibrahim, M. R.;
Ibrahim, Y. A.; El-Dusouqui, O. M. E. Tetrahedron 2005, 61, 8257.
[5] El-Dusouqui, O. M. E.; Abdelkhalik, M. M.; Al-Awadi,
N. A.; Dib, H. H.; George, B.; Elnagdi, M. H. J Chem Res 2006,
5, 295.
[6] Al-Bashir, R. F.; Al-Awadi, N. A.; El-Dusouqui, O. M. E.
Arkivoc 2008, 13, 228.
[7] Al-Awadi, H.; Ibrahim, M. R.; Al-Awadi, N. A.; Ibrahim, Y. A.
J Heterocyclic Chem 2008, 45, 723.
[27] Prasad, V. S.; Reddy, K. K. Synth Commun 1990, 20, 2617.
[28] Ibrahim, Y. A.; Al-Awadi, N. A.; Ibrahim, M. R. Tetrahedron
2004, 60, 9121.
[29] (a) FT-NMR Aldrich Catalog: 1993, Vol. II, 1509 A; (b) FT-NMR
Aldrich Catalog: 1993, Vol. II, p 1518 C; (c) FT-NMR Aldrich
Catalog: 1993, II, 1519C; (d) Yamamoto, O.; Hyamizu, K.; Sekine, K.;
Funahhira, S. Anal Chem 1972, 44, 1794; (e) FT-NMR Aldrich Catalog:
1993, Vol. II, p 1522 A; (f) FT-NMR Aldrich Catalog: III, 380 A.
[30] Sujikawa, T.; Tatsuta, M. Chem & Pharm Bull 1977, 25, 3137.
[31] Ciesielski, M.; Pufky, D.; Doring, M. Tetrahedron 2005,
61, 5942.
[8] El-Dusouqui, O. M. E.; Abdelkhalik, M. M.; Al-Awadi, N. A.;
Dib, H. H.; George, B.; Elnagdi, M. H. J Heterocyclic Chem 2008, 45,
1751.
[32] Liu, L.; Wang, Y.; Wang, H.; Peng, C.; Zhao, J.; Zhu, Q.
Tetrahedron Lett 2009, 50, 6715.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet