Gas-phase elimination reactions of 4-arylideneimino-2-cyanoethyl-1,2,4-triazol-3(2H)-ones, their thione analogues and 2-glucosyl-1,2,4-triazole-3(2H)-thiones: A kinetic and mechanistic study

Article abstract of DOI:10.1002/poc.491

Several 4-arylidenimino-2-cyanoethyl-1,2,4-triazol-3(2H)-ones, their 3(2H)-thiones and 2-glucosyl-1,2,4-triazol-3(2H)-thiones (1-12) were synthesized. Selective pyrolytic deprotection of these derivatives was studied in the gas phase and the kinetics of the reactions were measured for each compound. First-order rate constants measured over a 45 °C temperature range were used to calculate the Arrhenius activation parameters. A comparison of the products and the kinetic behavior of the thermal decomposition of these compounds are discussed. Copyright

Full text of DOI:10.1002/poc.491

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY
J. Phys. Org. Chem. 2002; 15: 324–329
Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/poc.491
Gas-phase elimination reactions of 4-arylideneimino-2-
cyanoethyl-1,2,4-triazol-3(2H)-ones, their thione analogues
and 2-glucosyl-1,2,4-triazole-3(2H)-thiones: a kinetic and
mechanistic study
Nouria A. Al-Awadi,* Yehia A. Ibrahim, Hicham Dib and Kamini Kaul
Chemistry Department, Kuwait University, P.O. Box 5969, 13060 Safat, Kuwait
Received 28 September 2001; revised 15 January 2002; accepted 6 February 2002
ABSTRACT: Several 4-arylidenimino-2-cyanoethyl-1,2,4-triazol-3(2H)-ones, their 3(2H)-thiones and 2-glucosyl-
1,2,4-triazol-3(2H)-thiones (1–12) were synthesized. Selective pyrolytic deprotection of these derivatives was studied
in the gas phase and the kinetics of the reactions were measured for each compound. First-order rate constants
measured over a 45°C temperature range were used to calculate the Arrhenius activation parameters. A comparison of
the products and the kinetic behavior of the thermal decomposition of these compounds are discussed. Copyright
 2002 John Wiley & Sons, Ltd.
KEYWORDS: 4-arylideneimino-2-cyanoethyl-1,2,4-triazol-3(2H)-ones and - thiones; 2-glucosyl-1,2,4-triazole-
3(2H)-thiones; gas-phase elimination
Scheme 1
tedious separation and identification. Therefore, we were
interested in gaining a detailed understanding of the
kinetics and thermal behavior of 2-substituted 1,2,4-
triazol-3(4H)-ones and their thiones as potential starting
material for the protection of N-2 in these triazoles in
order to assist in regioselective substitution at other
nitrogen sites in the ring.
Here we describe the results of kinetic studies and
thermal analysis of the gas-phase pyrolysis of 4-
arylidenimino-2-cyanoethyl-1,2,4-triazol-3(2H)-ones,
their 3(2H)-thiones and 2-glucosyl-1,2,4-triazole-3(2H)-
thiones (1–12) (Scheme 2).
INTRODUCTION
Previously, we have shown that 4-arylideneimino-1,2,4-
triazol-3(2H)-ones and their thio analogues undergo first-
order thermal decomposition in the gas phase. These
reactions proceed via aromatization of the transition state
which ultimately produces hydroxytriazoles or their thio
analogues, which are more stable than the reactant N-
aminotriazoles1 (Scheme 1). Electrophilic substitutions
of asymmetric heterocyclic urea and thiourea derivatives
[represented here by 1,2,4-triazol-3(2H)-ones and their
thione derivatives] are known to give mixtures of
different regioisomeric products.2 This usually leads to
RESULTS AND DISCUSSION
*Correspondence to: N. A. Al-Awadi, Chemistry Department, Kuwait
University, P.O. Box 5969, 13060 Safat, Kuwait.
E-mail: chesc@kuc01.kuniv.edu.kw
The compounds investigated are shown in Scheme 2.
Copyright  2002 John Wiley & Sons, Ltd.
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GAS-PHASE ELIMINATION IN SUBSTITUTED TRIAZOLINES AND ANALOGUES
325
Table 1. continued.
Log[A
Ea
(kJ molÀ1
)
Compound
T (K)
104k (sÀ1
)
(sÀ1)]
4
564.00
574.20
584.35
594.10
604.10
458.85
468.35
478.15
488.35
498.25
449.55
458.45
478.25
488.15
498.35
449.55
459.10
468.70
478.85
489.10
498.90
458.60
468.25
478.40
488.45
498.25
458.35
467.75
478.15
488.15
498.15
449.15
458.75
467.95
478.25
487.45
459.15
468.35
478.55
488.45
498.45
449.65
468.25
478.05
488.05
497.75
2.66
5.25
10.33
18.89
36.12
2.20
13.5 Æ 0.12 184.0 Æ 1.3
13.7 Æ 0.6 152.7 Æ 5.6
12.6 Æ 0.2 145.8 Æ 1.4
15.2 Æ 0.2 16.1 Æ 1.9
5
6
7
4.30
9.52
21.42
52.26
0.43
1.62
4.37
8.82
19.50
0.60
1.67
3.82
10.21
22.86
51.26
2.06
8
13.4 Æ 0.5 150.1 Æ 4.7
13.9 Æ 0.1 154.2 Æ 1.1
13.2 Æ 0.1 150.0 Æ 0.7
15.2 Æ 0.2 166.4 Æ 2.1
13.5 Æ 0.9 151.7 Æ 0.8
4.35
10.04
19.89
49.15
1.98
9
4.60
Scheme 2
10.44
23.45
50.92
0.55
10
11
12
Table 1. Kinetic data for gas-phase pyrolysis of 1±12
1.30
2.80
6.50
13.32
1.68
4.13
9.45
23.14
53.02
0.77
3.78
8.27
18.66
38.67
Log[A
Ea
(kJ molÀ1
)
Compound
T (K)
104k (sÀ1
)
(sÀ1)]
1
554.65
574.25
584.55
594.45
604.25
558.55
567.85
579.25
588.65
597.95
554.65
564.15
574.00
593.80
604.35
2.18
6.83
12.75
19.97
36.66
2.04
3.54
6.62
11.18
17.93
1.51
11.2 Æ 0.34 157.9 Æ 3.8
10.7 Æ 0.10 153.5 Æ 1.1
13.0 Æ 0.27 178.4 Æ 3.1
Kinetics
2
3
Each of the triazoles under investigation gave reprodu-
cible kinetic results, first order to 98% reaction. The
kinetic results (Table 1) gave excellent Arrhenius plots
with no deviant points. This is the most reliable indicator
of the absence of surface-catalysed elimination.3 The rate
constants of the reaction at 500 K for each substrate and
related compounds are recorded in Table 2. The
homogeneous nature of the reaction was confirmed using
established procedures.4
3.11
5.94
19.92
28.25
Copyright  2002 John Wiley & Sons, Ltd.
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326
N. A. AL-AWADI ET AL.
Table 2. Rate constants and relative rates at 500 K for the pyrolysis of 4-arylidenimino-2-cyanoethyl-1,2,4-triazol-3(2H)-ones, 4-
arylidenimino-2-cyanoethyl and 2-glucosyl-1,2,4-triazole-3(2H)-thiones
103k (sÀ1
)
Y
krol (II)/(I)
krol (II)/(III)
H
4-NO2
4-Cl
4-Me
4-OMe
5.08
4.29
1.26
2.29
1.75
5.44
2.14
3.33
5.68
5.13
5.77
3.32
3.94
5.94
4.52
1.07 Â 103
0.49 Â 103
2.68 Â 103
2.48 Â 103
2.93 Â 103
0.94
0.65
0.85
0.96
1.14
noethyl-1,2,4-triazol-3(2H)-one (13) (Scheme 3).
Similarly, pyrolysis of 5, 7 and 8 gave arylnitriles
and
2-cyanoethyl-1,2,4-triazole-3(2H)-thione
(14,
R = CH2CH2CN). Pyrolysis of 9–12 also gave arylnitriles
and 2-glucosyl-1,2,4-triazole-3(2H)-thione (14, R = glu-
cosyl) (Scheme 4). On the other hand, pyrolysis of the
4-nitro derivative 2 gave the expected 13, but no
4-nitrobenzonitrile was detected, 4-aminobenzonitrile
(15) and N,N'-bis(4-cyanophenyl)hydrazine (16) being
detected instead, which most probably resulted from
reduction of 4-nitrobenzonitrile (Scheme 5), in addi-
tion
to
the
oxidation
products
4H,
Scheme 3
4'HÀ[1,1']bi{[1,2,4]triazolyl} À 5,5'-dione (17). Com-
pound 6 is no exception, pyrolysis produced 4-nitroben-
zonitrile and 14 (R = CH2CH2CN), The latter undergo
further elimination reaction of cyanoethylene to produce
14 (R = H), the 4-nitrobenzonitrile produced reacts with
both
the
primary
elimination
product
14
(R = CH2CH2CN) to give 18 and with the secondary
elimination product (14, R = H) to give 19 (Scheme 6)
and reduction products 15 and 16. The proposed pathway
for the formation of 18 was substantiated by reacting each
of 14 (R = H, CH2CH2CN) with 4-nitrobenzonitrile under
the same pyrolytic conditions. Analysis of the product
mixture in both cases revealed the formation of 18 (from
14, R = CH2CH2CN) and 19 (from 14, R = H) in addition
to 15 and 16. We were also able to identify the oxidation
product in this case as the (1,2,4-triazol-3-yl)disulfide 20.
Kinetic data together with the products of pyrolytic
elimination reaction of the substrates 1–12 allow the
following conclusions and comparison to be made:
Scheme 4
Product analysis
Products of pyrolysis were analysed by 1H and 13C NMR
spectroscopy and LC–MS. We investigated the selective
removal of the group at N-4. Pyrolysis of 1, 3 and 4 gave
almost quantitative yields of arylnitriles and 2-cya-
(i) The six-membered TS, mechanism (Scheme 1) adopted
in order to account for the kinetic results and reaction
products involves thermal extrusion of 4-arylbenzoni-
Copyright  2002 John Wiley & Sons, Ltd.
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GAS-PHASE ELIMINATION IN SUBSTITUTED TRIAZOLINES AND ANALOGUES
327
Scheme 5
Scheme 6
Copyright  2002 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2002; 15: 324–329

328
N. A. AL-AWADI ET AL.
trile from the substrates; it is noteworthy that the values
concentrated HCl (5 ml). The precipitate was collected,
dried and recrystallized from ethanol. The following
compounds were thus prepared.
obtained for Arrhenius parameters are typical of polar
homogeneous pyrolytic gas-phase reactions.5
(ii) 4-Arylidenimino-2-cyanoethyl-1,2,4-triazol-3(2H)-
thiones 5–8 are 490–2930 times more reactive than
their oxygen analogues 1–4 (Table 2). This large
difference in molecular reactivity is due to the greater
protophilicity and lability together with the relative
thermodynamic stability and the p-bond energy
difference of the thio and carbonyl bonds. This
contribution from the p-bond to the molecular
reactivity of these substrates together with the almost
negligible electronic effect of the substituent on the
aryl ring indicates that breaking of the p-bond is the
rate-controlling step of the reaction.
4-Benzylidenimino-2-b-cyanoethyl-1,2,4-triazol-
3(2H)-one (1). White crystals, yield 70%, m.p. 132–
‡
133°C. MS: m/z 241 (M ). IR: 3130, 2251, 1706, 761, 727,
693 cmÀ1. H NMR (CDCl3): ꢀ 2.89 (t, 2H, J = 6.9 Hz,
1
CH2CN), 4.17 (t, 2H, J = 6.9 Hz, CH2N), 7.50 (m, 3H,
ArH), 7.80 (m, 2H, ArH), 7.82 (s, 1H, CH
=N triazole),
9.75 (s, 1H, ArCH
=
N). 13C NMR (CDCl3): ꢀ 17.3, 41.1,
116.7, 128.1, 128.9, 131.8, 133.1, 136.6, 149.4, 155.6.
Anal. Calcd for C12H11N5O (241): C, 59.75; H, 4.56; N,
29.05. Found: C, 59.62; H, 4.56, N, 29.10%.
(iii) 4-Nitroarylidenimino-2-cyanoethyl-1,2,4-triazol-
3(2H)-one 2 and its thio analogue 6 were exceptional
in term of the pyrolysis products; the primary thermal
elimination products underwent further reactions.
Thus, p-nitrobenzonitrile produced from 2 is reduced
to the corresponding aniline and hydrazine deriva-
tives 15 and 16. On the other hand, p-nitrobenzoni-
trile reacted with the other pyrolysis products of 6
through aromatic nucleophilic substitution of the
nitro group to give the corresponding 3-p-cyanophe-
nylthio-1,2,4-triazole derivatives 18 and 19.
4-p-Nitrobenzylidenimino-2-b-cyanoethyl-1,2,4-tria-
zol-3(2H)-one (2). Yellow powder, yield 55%, m.p. 166–
‡
168°C. MS: m/z 287 (M ). 1H NMR (DMSO-d6): ꢀ 2.98
(t, 2H, J = 6.9 Hz, CH2CN), 4.04 (t, 2H, J = 6.9 Hz,
CH2N), 8.08 (m, 2H, ArH), 8.36 (m, 2H, ArH), 8.68 (s,
1H, CH=N triazole), 9.55 (s, 1H, ArCH=N). Anal.
Calcd for C12H10N6O3 (286): C, 50.34; H, 3.49; N, 29.47.
Found: C, 50.27; H, 3.53, N, 28.75%.
4-p-Methylbenzylidenimino-2-b-cyanoethyl-1,2,4-
triazol-3(2H)-one (3). White crystals, yield 68%, m.p.
‡
136–137°C. MS: m/z 255 (M ). IR: 3126, 2249, 1706,
813, 756 cmÀ1. H NMR (CDCl3): ꢀ 2.43 (s, 3H, CH3),
1
2.88 (t, 2H, J = 6.9 Hz, CH2CN), 4.16 (t, 2H, J = 6.9 Hz,
EXPERIMENTAL
CH2N), 7.27 (m, 2H, ArH), 7.69 (m, 2H, ArH), 7.81 (s,
Kinetic measurements
1H, CH=N triazole), 9.70 (s, 1H, ArCH=
N). 13C NMR
(CDCl3): ꢀ 17.3, 21.6, 41.1, 116.7, 128.1, 129.7, 130.4,
136.5, 142.4, 149.5, 155.7. Anal. Calcd for C13H13N5O
(255): C, 61.18; H, 5.10; N, 27.45. Found: C, 61.39; H,
5.08, N, 27.12%.
Procedures for the kinetic measurements have been
detailed in an earlier paper.6
Product analysis
4-p-Methoxybenzylidenimino-2-b-cyanoethyl-1,2,4-
triazol-3(2H)-one (4). White plates, yield 65%, m.p.
About 100 mg of the neat substrate was taken in a
custom-made pyrolysis tube and sealed under vacuum
(0.28 mbar). It was placed inside a Eurotherm 093
pyrolysis unit at a temperature and time comparable to
those used in the kinetic investigations. The pyrolysis
tube was jacketed by an insulating aluminium block,
fitted with a platinum resistance thermometer and a
thermocouple connected to a Comark microprocessor
thermometer. After pyrolysis, the tube was allowed to
cool to room temperature and the pyrolysate obtained
was analysed using NMR, IR and LC–MS techniques.
‡
129–130°C. MS: m/z 271 (M ). IR: 3149, 2251, 1703,
832, 723 cmÀ1 1H NMR (CDCl3): ꢀ 2.89 (t, 2H,
.
J = 6.9 Hz, CH2CN), 3.89 (s, 3H, OCH3), 4.17 (t, 2H,
J = 6.9 Hz, CH2N), 6.99 (m, 2H, ArH), 7.78 (m, 2H,
ArH), 7.80 (s, 1H, CH
=N triazole), 9.66 (s, 1H,
ArCH=
N). 13C NMR (CDCl3): ꢀ 17.7, 41.4, 55.8,
114.7, 116.8, 125.7, 129.8, 136.5, 149.5, 155.3, 162.5.
Anal. Calcd for C13H13N5O2 (271): C, 57.56; H, 4.79; N,
25.83. Found: C, 57.10; H, 4.84, N, 25.51%.
Preparation of 4-Arylidenimino-2-b-cyanoethyl-
1,2,4-triazole-3(2H)-thiones. A solution of 4-arylideni-
mino-1,2,4-triazole-3(2H)-thione (5 mmol) in aqueous
pyridine (50%, 10 ml) and acrylonitrile (0.4 ml,
5.7 mmol) was heated under reflux for 18 h. After
cooling, the mixture was poured over crushed ice and
acidified with concentrated HCl (5 ml). The precipitate
was collected, dried and recrystallized from ethanol. The
following compounds were thus synthesized.
Synthesis
Preparation of 4-Arylidenimino-2-b-cyanoethyl-
1,2,4-triazol-3(2H)-ones. A solution of 4-arylidenimi-
no-1,2,4-triazol-3(2H)-one (5 mmol) in aqueous pyridine
(50%, 10 ml) and acrylonitrile (0.4 ml, 5.7 mmol) was
heated under reflux for 18 h. After cooling, the mixture
was poured over crushed ice and acidified with
Copyright  2002 John Wiley & Sons, Ltd.
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GAS-PHASE ELIMINATION IN SUBSTITUTED TRIAZOLINES AND ANALOGUES
329
4-Benzylidenimino-2-b-cyanoethyl-1,2,4-triazole-
4-Benzylideneimino-2-N-tetra-O-acetyl-b-D-glucosyl-
3(2H)-thione (5). Pale buff crystals, yield 89%, m.p. 112–
1,2,4-triazole-3(2H)-thione (9). Yield 50%, m.p. 192–
‡
‡
114°C. MS: m/z 257 (M ). IR: 3098, 2251, 751, 690 cmÀ1
.
193°C (lit.7 m.p. 193°C). MS: m/z 535 (M ‡ 1). IR: 3474,
1H NMR (CDCl3): ꢀ 3.02 (t, 2H, J = 6.9 Hz, CH2CN), 4.54
(t, 2H, J = 6.9 Hz, CH2N), 7.53 (m, 3H, ArH), 7.86 (m, 2H,
3151, 2976, 1751, 1611, 1547, 1427, 1365, 1235 cmÀ1
.
ArH), 8.11 (s, 1H, CH
=
N triazole), 10.40 (s, 1H,
4-p-Nitrobenzylideneimino-2-N-tetra-O-acetyl-b-D-
ArCH=
N). 13C NMR (CDCl3): ꢀ 16.8, 44.8, 117.0,
glucosyl-1,2,4-triazole-3(2H)-thione (10). Yield 55%,
‡
129.2, 129.5, 132.5, 133.1, 140.0, 161.0, 161.9. Anal.
Calcd for C12H11N5S (257): C, 56.03; H, 4.28; N, 27.23;
S, 12.45. Found: C, 56.11; H, 4.28, N, 26.93; S, 12.89%.
m.p. 196–197°C. MS: m/z 580 (M ‡ 1). IR: 3400, 1751,
1593, 1525, 1425, 1365, 1349, 1233 cmÀ1 1H NMR
.
(CDCl3): ꢀ 1.97, 2.06, 2.09, 2.10 (4s, 12H, CH3), 4.02 (dd,
1H, CH-5'), 4.18, 4.25 (2 dd, 2H, CH2-6'), 5.28 (t, 1H, CH-
4'), 5.47 (t, 1H, CH-3'), 5.80 (t, 1H, CH-2'), 6.23 (d, 1H,
4-p-Nitrobenzylidenimino-2-b-cyanoethyl-1,2,4-tria-
zole-3(2H)-thione (6). Pale yellow crystals, yield 85%,
CH-1'), 8.04 (d, 2H, ArH), 8.11 (s, 1H, CH=N triazole),
‡
m.p. 183–186°C. MS: m/z 302 (M ). IR: 3125, 2250,
8.35 (d, 2H, ArH), 10.92 (s, 1H, CH N). Anal. Calcd for
=
1594, 850, 771, 749 cmÀ1. H NMR (CDCl3): ꢀ 3.02 (t,
C23H25N5O11S (579): C, 47.67; H, 4.32; N, 12.09; S,
5.53. Found: C, 47.62; H, 4.16; N, 12.06; S, 5.35.
1
2H, J = 6.9 Hz, CH2CN), 4.55 (t, 2H, J = 6.9 Hz, CH2N),
8.04 (m, 2H, ArH), 8.06 (s, 1H, CH
(m, 2H, ArH), 10.92 (s, 1H, ArCH
=
=
N triazole), 8.35
N). 13C NMR
4-p-Methylbenzylideneimino-2-N-tetra-O-acetyl-b-D-
glucosyl-1,2,4-triazole-3(2H)-thione (11). Yield 50%,
(CDCl3): ꢀ 16.3, 44.2, 116.5, 124.2, 129.3, 138.2, 140.0,
149.9, 155.9, 161.4. Anal. Calcd for C12H10N6O2S (302):
C, 47.68; H, 3.31; N, 27.81; S, 10.59. Found: C, 48.05; H,
3.40, N, 27.41; S, 10.37%.
‡
m.p. 217–218°C. MS: m/z 549 (M ‡ 1). IR: 1751, 1606,
1
1235 cmÀ1. H NMR (CDCl3): ꢀ 1.96, 2.06, 2.08, 2.10
(4s, 12H, CH3), 2.45 (s, 3H, ArCH3), 4.00 (m, 1H, CH-
5'), 4.20, 4.30 (2dd, 2H, CH2-6'), 5.27 (t, 1H, CH-4'), 5.44
(t, 1H, CH-3'), 5.80 (t, 1H, CH-2'), 6.25 (d, 1H, H-1'),
4-p-Methylbenzylidenimino-2-b-cyanoethyl-1,2,4-
triazole-3(2H)-thione (7). Colorless crystals, yield 88%,
7.30 (d, 2H, ArH), 7.75 (d, 2H, ArH), 8.07 (s, 1H, CH
=N
‡
m.p. 150–151°C. MS: m/z 271 (M ). IR: 3083, 2251,
triazole), 10.25 (s, 1H, CH
=
N). 13C NMR(CDCl3): ꢀ
817, 753 cmÀ1. H NMR (CDCl3) ꢀ 2.46 (s, 3H, CH3),
21.0, 21.2, 22.2, 62.0, 68.1, 69.4, 74.0, 75.0, 82.0, 129.2,
129.7, 130.2, 140.3, 144.0, 161.6, 164.5, 169.4, 169.8,
170.6, 171.1. Anal. Calcd for C24H28N4O9S (548): C,
52.55; H, 5.11 N; 10.22; S, 5.84. Found: C, 52.75; H,
4.97; N, 10.31; S, 5.55.
1
3.00 (t, 2H, J = 6.9 Hz, CH2CN), 4.54 (t, 2H, J = 6.9 Hz,
CH2N), 7.35 (m, 2H, ArH), 7.79 (m, 2H, ArH), 8.09 (s,
1H, CH=N triazole), 10.28 (s, 1H, ArCH=
N). 13C NMR
(CDCl3): ꢀ 16.5, 21.8, 44.4, 116.6, 128.8, 129.7, 129.9,
139.4, 143.5, 161.0, 161.5. Anal. Calcd for C13H13N5S
(271): C, 57.56; H, 4.79; N, 25.83; S, 11.81. Found: C,
58.02; H, 4.89, N, 25.93; S, 12.08%.
4-p-Methoxybenzylideneimino-2-N-tetra-O-acetyl-b-
D-glucosyl-1,2,4-triazole-3(2H)-thione (12). Yield 50%,
‡
m.p. 194–195°C (lit.6 m.p. 188°C). MS: m/z 564 (M ).
4-p-Methoxybenzylidenimino-2-b-cyanoethyl-1,2,4-
triazole-3(2H)-thione (8). White crystals, yield 82%,
IR: 3455, 3136, 2964, 2937, 2838, 1750, 1605, 1572,
1547, 1515, 1425, 1256, 1223 cmÀ1
.
‡
m.p. 125–127°C. MS: m/z 287 (M ). IR: 3097, 3038,
2252, 819, 758 cmÀ1. H NMR (CDCl3): ꢀ 3.00 (t, 2H,
1
Acknowledgement
J = 6.9 Hz, CH2CN), 3.89 (s, 3H, OCH3), 4.53 (t, 2H,
J = 6.9 Hz, CH2N), 6.98 (m, 2H, ArH), 7.81 (m, 2H,
The support of the University of Kuwait received through
research grant (SC 03/00) and the facilities of ANALAB
and SAF are gratefully acknowledged.
ArH), 8.06 (s, 1H, CH
=N triazole), 10.11 (s, 1H,
ArCH=
N). 13C NMR (CDCl3): ꢀ 16.4, 44.4, 55.5, 114.5,
116.6, 124.5, 130.7, 139.2, 160.9, 163.3. Anal. Calcd for
C13H13N5OS (287): C, 54.36; H, 4.53; N, 24.39; S, 11.14.
Found: C, 54.17; H, 4.50, N, 24.21; S, 11.20%.
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Copyright  2002 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2002; 15: 324–329