Synthesis and antitumor activities of 2-(substituted)phenyl-1,2,4- triazolo[1,5-a]pyridines

Article abstract of DOI:10.1002/jhet.5570440428

(Chemical Equation Presented) Twenty-three 2-(substituted)phenyl-1,2,4- triazolo[1,5-a]pyridines have been synthesized by cyclo-additison reaction between N-amino methylpyridinium mesitylenesulfonates and substituted benzonitriles under the presence of po

Full text of DOI:10.1002/jhet.5570440428

Jul-Aug 2007
919
Synthesis and Antitumor Activities of 2-(Substituted)phenyl-
1,2,4-triazolo[1,5-a]pyridines
Guolin Zhang and Yongzhou Hu
Department of Medicinal Chemistry, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou,
310058, P. R. China
Email: guolinzhang@zju.edu.cn
Received April 19, 2006
R1
R2
H3C
H3C
-OSO2
R1
R2
R3
R4
CN
N
N
H3C
CH3
+
R3
N
N
H3C
KOH/EtOH, R. T.
NH2
R4
1a-1w
Twenty-three 2-(substituted)phenyl-1,2,4-triazolo[1,5-a]pyridines have been synthesized by cyclo-
additison reaction between N-amino methylpyridinium mesitylenesulfonates and substituted benzonitriles
under the presence of potassium hydroxide at room temperature. The structures of all products were
1
confirmed by H NMR, MS and elemental analyses. The antitumor activities of these compounds were
evaluated against human ovary cancer cell line (HO-8910) in vitro by MTT method. The preliminary
results showed that compound 1e (IC50 28μM) and compound 1w (IC50 31μM) exhibited stronger antitumor
activities than cisplatin (IC50 35μM) in vitro. Hence, 1e and 1w have potential antitumor activities and are
worth further investigation.
J. Heterocyclic Chem., 44, 919 (2007).
been synthesized and their antitumor activities have been
evaluated. The most promising compounds were 2-(4-
benzyloxyphenyl)-8-methyl-1,2,4-triazolo[1, 5-a]pyridine
1e and 2-(4-benzyloxyphenyl)-5-methyl-1,2,4-triazolo-
[1,5-a]pyridine 1w. To the best of our knowledge, the
antitumor activities of 1,2,4-triazolo[1,5-a]pyridine deriv-
atives have not been yet reported in the literature.
INTRODUCTION
It was well known that many compounds containing
triazolopyridine skeleton have interesting bioactivities [1].
For example, 8-amino-2-aryl-1,2,4-triazolo[1,5-a]pyri-
dine-6-carboxyl amide derivatives were proved to inhibit
the human adenosine 2a (hA2a) receptor [2], the 1,2,4-
triazolo[3,4-a]pyridine was considered as a constrained
template for fibrinogen receptor (GPIIb/IIIa) antagonists
[3]. Recently, 2-aryl-1,2,4-triazolo[1,5-a]pyridines have
been found to have pregnancy interceptive activity [4].
The mechanism of pregnancy interceptive activity was
cell apoptosis to cause luteolysis [5]. Because tumor cells
grow vigorously like embryo cells, we are interested in
whether or not 1,2,4-triazolo[1,5-a]pyridines have anti-
tumor activities. Therefore, twenty-three compounds of 2-
RESULTS AND DISCUSSION
Scheme 1 outlines the synthetic sequences employed in
our laboratories for the preparation of 1a-1w. N-
Amination of methylpyridines 2 with O-mesitylenesul-
fonyl hydroxylamine (MSH) afforded N-amino methyl-
pyridinium mesitylenesulphonates 3. Subsequently, 1,3-
dipolar cycloaddition reaction between 3 and aromatic
nitriles in the presence of potassium hydroxide solution
gave target compounds 1a-1w. Physical properties and
(substituted)phenyl-1,2,4-triazolo[1,5-a]pyridines
have
Scheme 1
R1
R2
H3C
-OSO2
R3
R4
CN
MSH/CH2Cl2
H3C
CH3
+
H3C
N
H3C
R. T.
N
NH2
KOH/EtOH, R. T.
2
3
CH3
CH3
R1
R1
R2
R2
H3C
N
N
N
N
N
N
N
OCH2
R3
R3
N
N
R4
R4
1m-1v
1a-1l
1w

920
G. Zhang and Y. Hu
Vol 44
Table 1
Physical and Analytical Data of Compounds 1ꢀ-1w
Compound
R1
R2
R3
R4
Mp
(°C)
Yield
%
Molecular
Formula
Analysis %
Calcd./Found
H
C
N
1a
1b
1c
1d
1e
1f
H
H
H
H
OMe
OEt
H
H
123-125
128-129
106-108
193-195
116-118
100-101
190-192
154-156
155-157
127-129
123-125
99-101
43
46
42
40
40
44
46
50
46
40
35
41
36
40
46
48
33
38
46
49
46
53
34
C14H13N3O
C15H15N3O
C17H19N3O
C13H10ClN3
C20H17N3O
C13H11N3
70.28
70.25
71.13
71.14
72.57
72.50
64.07
64.05
76.17
76.25
74.62
74.65
71.40
71.42
66.90
66.92
66.40
66.42
64.20
64.21
70.28
72.26
70.28
72.30
70.28
72.30
70.28
72.29
71.13
71.16
72.57
72.62
76.17
76.19
71.40
71.44
66.90
66.93
66.40
66.44
64.20
64.21
74.62
74.65
76.17
76.14
5.48
5.46
5.97
6.00
6.81
6.73
4.14
4.13
5.43
5.39
5.30
5..32
6.39
6.38
5.61
5.59
4.38
4.35
5.72
5.70
5.48
5.47
5.48
5.47
5.48
5.50
5.48
5.50
5.97
6.00
6.81
6.78
5.43
5.42
6.39
6.37
5.61
5.62
4.38
4.37
5.72
5.70
5.30
5.31
5.43
5.42
17.56
17.57
16.59
16.57
14.94
14.86
17.24
17.28
13.32
13.23
20.08
20.05
22.21
22.24
15.60
15.54
16.59
16.61
14.04
14.01
17.56
17.57
17.56
17.54
17.56
17.58
17.56
17.53
16.59
16.60
14.94
14.92
13.32
13.33
22.21
22.22
15.60
15.57
16.59
16.58
14.04
13.99
20.08
20.05
13.32
13.29
H
H
OBu-n
Cl
H
H
H
H
H
H
OBz
H
H
H
H
H
1g
1h
1i
H
H
NMe2
OMe
H
C15H16N4
H
OMe
H
C15H15N3O2
C14H11N3O2
C16H17N3O3
C14H13N3O
C14H13N3O
C14H13N3O
C14H13N3O
C15H15N3O
C17H19N3O
C20H17N3O
C15H16N4
H
OCH2O
H
1j
H
OMe
H
OMe
H
OMe
H
1k
1l
OMe
H
OMe
H
H
H
1m
1n
1o
1p
1q
1r
1s
OMe
H
H
H
96-98
OMe
H
H
H
143-144
145-147
110-112
172-174
>250
H
OEt
OBu-n
OBz
NMe2
OMe
H
H
H
H
H
H
H
H
H
H
H
OMe
H
136-138
196-198
168-170
139-141
124-126
C15H15N3O2
C14H11N3O2
C16H17N3O3
C13H11N3
1t
H
OCH2O
H
1u
1v
1w
H
OMe
OMe
OMe
H
H
H
/
H
/
/
/
C20H17N3O
elemental analyses data of 1a-1w are summarized in
Table 1.
triazolo[1,5-a]pyridine 1e and 2-(4-benzyloxyphenyl)-5-
methyl-1,2,4-triazolo[1,5-a]pyridine 1w. Their IC50 values
were 28μM and 31μM, respectively. They are more
potent than cisplatin (IC50 35μM) and are worth farther
investigation.
The antitumor activities of 1a-1w were evaluated
against human ovary cancer cell line (HO-8910) in vitro
by MTT method [6]. The results are summarized in Table
2. The IC50 value represents the drug concentration (μM)
required to inhibit the cell growth by 50%. The
preliminary results showed that some synthetic
compounds exhibited activities against human ovary
cancer cell line (HO-8910) in vitro. The most promising
compounds were 2-(4-benzyloxyphenyl)-8-methyl-1,2,4-
EXPERIMENTAL
Melting points were recorded on a BUCHI melting point B-
540 apparatus and are uncorrected. 1H NMR spectra were
determined in CDCl3 on a Bruker 400 MHz or 500 MHz

Jul-Aug 2007
Synthesis and Antitumor Activities of 2-(Substituted)phenyl-1,2,4-triazolo[1,5-a]pyridines
921
Table 2
Antitumor Activities of Compounds 1a-1w
Compound
1a
920
1j
1b
*
1k
618
1t
1c
*
1l
1d
*
1m
*
1e
28
1n
1f
1g
*
1p
*
1h
*
1q
*
1i
*
1r
*
IC50 μM
Compound
IC50 μM
*
1o
*
*
*
958
1w
31
Compound
IC50 μM
1s
1400
1u
237
1v
212
cisplatin
35
*
*: The IC50 values were more than 1500 μM.
spectrometer with SiMe4 as the internal standard. J values are
given in Hz. Mass spectral data were obtained by electron
ionization (70 eV) on HP5989B instrument. N-Aminomethyl-
pyridinium mesitylenesulfonates were prepared by the procedure
described in reference [7]. Column chromatography purify-
cations were carried out using silica gel (200-300 mesh) with
hexane-EtOAc.
General Procedure for the Synthesis of 2-(substituted)-
phenyl-1,2,4-triazolo[1,5-a]pyridines (1a-1w). A solution of
3.08 g (10 mmol) N-amino methylpyridinium mesitylene-
sulfonate (3) and 10 mmol substituted benzonitrile dissolved in
15 ml of ethanol was cooled by ice-water then 5.2 ml of 2 M
KOH was added dropwise. After the addition was complete, the
solution was allowed to warm to room temperature and
continued to stir for an additional 24 hours. Most of the ethanol
was evaporated under reduced pressure. The residual was
extracted with CHCl3 (3 x 10 ml). The CHCl3 layer was dried
over anhydrous Na2SO4 and evaporated to dryness under
reduced pressure. The residue was purified by column
chromatography to afford the target compound.
2.69 (s, 3H, 8-CH3), 5.14 (s, 2H, -OCH2), 6.89 (d, 1H, 6-H,
J=6.9Hz), 7.09 (d, 2H, phenyl protons, J=8.6Hz), 7.26 (br s, 1H,
7-H), 7.34 (m, 1H, Ar-H),7.40 (dd, 2H, phenyl protons, J=7.4,
7.6Hz), 7.46 (d, 2H, Ar-H, J=7.4Hz), 8.24 (d, 2H, phenyl protons,
J=8.6Hz), 8.43 (d, 1H, 5-H, J=6.8Hz) ms: m/z 315 (M+).
2-Phenyl-8-methyl-1,2,4-triazolo[1,5-a]pyridine (1f). This
compound was obtained as a white solid. 1H nmr: 2.70 (s, 3H, 8-
CH3), 6.90 (t, 1H, 6-H, J=6.9Hz), 7.27 (br s, 1H, 7-H), 7.51 (m,
3H, phenyl protons), 8.30 (m, 2H, phenyl protons), 8.45 (d, 1H,
5-H, J=6.9Hz). ms: m/z 209 (M+).
2-(4-Dimethylaminophenyl)-8-methyl-1,2,4-triazolo[1,5-a]-
pyridine (1g). This compound was obtained as a yellow solid.
1H nmr: 2.69 (s, 3H, 8-CH3), 3.05 (s, 6H, -N(CH3)2), 6.81 (d, 2H,
phenyl protons, J=8.8Hz), 6.85 (t, 1H, 6-H, J=6.9Hz), 7.23 (d,
1H, 7-H, J=6.9Hz), 8.17 (d, 2H, phenyl protons, J=8.8Hz), 8.43
(d, 1H, 5-H, J=6.9Hz). ms: m/z 252 (M+).
2-(3,4-Dimethoxyphenyl)-8-methyl-1,2,4-triazolo[1,5-a]-
pyridine (1h). This compound was obtained as a white solid. 1H
nmr: 2.69 (s, 3H, 8-CH3), 3.95 (s, 3H, 4-OCH3), 4.03 (s, 3H, 3-
OCH3), 6.87 (t, 1H, 6-H, J=6.9Hz), 6.97 (d, 1H, phenyl proton,
J=8.4Hz), 7.24 (d, 1H, 7-H, J=6.9Hz),7.83 (d, 1H, phenyl
proton, J=1.8Hz), 7.90 (dd, 1H, phenyl proton, J=1.8, 8.4Hz),
8.43 (d, 1H, 5-H, J=6.9Hz). ms: m/z 269 (M+).
2-(3,4-Methylenedioxyphenyl)-8-methyl-1,2,4-triazolo[1,5-
a]pyridine (1i). This compound was obtained as a white solid.
1H nmr: 2.67 (s, 3H, 8-CH3), 6.03 (s, 2H, -CH2-), 6.88 (t, 1H, 6-
H, J=6.9Hz), 6.92 (d, 1H, phenyl proton, J=8.1Hz), 7.25 (m, 1H,
7-H), 7.76 (d, 1H, phenyl proton, J=1.6Hz), 7.86 (dd, 1H, phenyl
proton, J=1.6, 8.1Hz), 8.42 (d, 1H, 5-H, J= 6.9Hz). ms: m/z 253
(M+).
2-(3,4,5-Trimethoxyphenyl)-8-methyl-1,2,4-triazolo[1,5-a]-
pyridine (1j). This compound was obtained as a white solid. 1H
nmr: 2.72 (s, 3H, 8-CH3), 3.92 (s, 3H, 4-OCH3), 4.01 (s, 6H, 3-
OCH3 and 5-OCH3), 6.88 (t, 1H, 6-H, J=6.9Hz), 7.26 (d, 1H, 7-
H, J=6.9Hz), 7.85 (s, 2H, phenyl protons), 8.20 (d, 1H, 5-H,
J=6.9Hz). ms: m/z 299 (M+).
2-(2-Methoxyphenyl)-8-methyl-1,2,4-triazol[1,5-a]pyridine
(1k). This compound was obtained as a white solid. 1H nmr: 2.69
(s, 3H, 8-CH3), 3.96 (s, 3H, 2-OCH3), 6.88 (t, 1H, 6-H, J=6.6Hz),
7.07 (m, 2H, phenyl protons), 7.26 (d, 1H, 7-H, J=6.6Hz), 7.43 (t,
1H, Ar-H, J= 7.2Hz), 8.07 (dd, 1H, phenyl ptoton, J=1.2, 7.2Hz),
8.50 (d, 1H, 5-H, J= 6.6Hz). ms: m/z 239 (M+).
2-(3-Methoxyphenyl)-8-methyl-1,2,4-triazolo[1,5-a]pyri-
dine (1l). This compound was obtained as a white solid. 1H nmr:
2.70 (s, 3H, 8-CH3), 3.93 (s, 3H, 3-OCH3), 6.90 (t, 1H, 6-H,
J=6.9Hz), 7.01 (dd, 1H, phenyl proton, J=2.4, 7.9Hz), 7.26 (dd,
1H, 7-H, J=0.6, J= 6.9Hz), 7.40 (t, 1H, phenyl proton, J=7.9Hz),
7.84 (s, 1H, Ar-H), 7.90 (d, 1H, phenyl proton, J=7.9Hz), 8.45
(d, 1H, 5-H, J=6.9Hz). ms: m/z 239 (M+).
2-(4-Methoxyphenyl)-8-methyl-1,2,4-triazolo[1,5-a]pyri-
1
dine (1a). This compound was obtained as a white solid. H
nmr:2.71 (s, 3H, 8-CH3), 3.90 (s, 3H, 4-OCH3), 6.90 (t, 1H, 6-H,
J=6.9Hz), 7.02 (d, 2H, phenyl protons, J=8.8Hz), 7.27 (d, 1H, 7-
H, J= 6.9Hz), 8.25 (d, 2H, phenyl protons, J=8.8Hz), 8.45 (d,
1H, 5-H, J=6.9Hz); ms: m/z 239 (M+).
2-(4-Ethoxyphenyl)-8-methyl-1,2,4-triazolo[1,5-a]pyridine
(1b). This compound was obtained as a white solid. 1H nmr:1.45
(t, 3H, -CH2CH3, J=7.0Hz), 2.70 (s, 3H, 8-CH3), 4.11 (q, 2H, -
OCH2, J=7.0Hz), 6.89 (t, 1H, 6-H, J=6.9Hz), 7.00 (d, 2H, phenyl
protons, J=8.8Hz), 7.26 (dd, 1H, 7-H, J=0.8, 6.9Hz), 8.23 (d,
2H, phenyl protons, J=8.8Hz), 8.43 (d, 1H, 5-H, J= 6.9Hz); ms:
m/z 253 (M+).
2-(4-Butoxyphenyl)-8-methyl-1,2,4-triazolo[1,5-a]pyridine
(1c). This compound was obtained as a white solid. 1H nmr: 1.02
(t, 3H, CH3, J=7.5Hz), 1.54 (m, 2H, -CH2CH3), 1.82 (m, 2H, -
CH2CH2CH2CH3), 2.71 (s, 3H, 8-CH3), 4.06 (t, 2H, -OCH2CH2-
CH2CH3, J=6.5Hz), 6.89 (t, 1H, 6-H, J=7.0Hz), 7.02 (d, 2H,
phenyl protons, J=8.8Hz), 7.27 (d, 1H, 7-H, J=7.0Hz), 8.24 (d,
2H, phenyl protons, J=8.8Hz), 8.44 (d, 1H, 5-H, J=7.0Hz); ms:
m/z 281 (M+).
2-(4-Chlorophenyl)-8-methyl-1,2,4-triazolo[1,5-a]pyridine
1
(1d). This compound was obtained as a white solid. H nmr:
2.70 (s, 3H, 8-CH3), 6.93 (t, 1H, 6-H, J=6.9Hz), 7.30 (d, 1H, 7-
H, J=6.9Hz), 7.46 (d, 2H, phenyl protons, J=8.6Hz), 8.25 (d, 2H,
phenyl protons, J=8.6Hz), 8.45 (d, 1H, 5-H, J= 6.9Hz); ms: m/z
243 (M+), 245 (M+2)+.
2-(4-Benzyloxyphenyl)-8-methyl-1,2,4-triazolo[1,5-a]pyri-
dine (1e). This compound was obtained as a white solid. 1H nmr:

922
G. Zhang and Y. Hu
Vol 44
2-(2-Methoxyphenyl)-7-methyl-1,2,4-triazolo[1,5-a]pyridine
1
OCH3), 6.81 (dd, 1H, 6-H, J=1.6, 6.9Hz), 6.98 (d, 1H, phenyl
proton, J=8.4Hz), 7.49 (s, 1H, 8-H), 7.79 (d, 1H, phenyl proton,
J=1.9Hz), 7.88 (dd, 1H, phenyl proton, J=1.9, 8.4Hz), 8.44 (d,
1H, 5-H, J=6.9Hz). ms: m/z 269 (M+).
2-(3,4-Methylenedioxyphenyl)-7-methyl-1,2,4-triazolo[1,5-
a]pyridine (1t). This compound was obtained as a white solid.
1H nmr: 2.49 (s, 3H, 7-CH3), 6.04 (s, 2H, -OCH2), 6.81 (dd, 1H,
6-H, J=1.6, 6.9Hz), 6.92 (d, 1H, phenyl proton, J=8.1Hz), 7.48
(s, 1H, 8-H), 7.73 (d, 1H, phenyl proton, J=1.6Hz), 7.82 (dd, 1H,
phenyl proton, J=1.6, 8.1Hz), 8.43 (d, 1H, 5-H, J=6.9Hz). ms:
m/z 253 (M+).
2-(3,4,5-Trimethoxyphenyl)-7-methyl-1,2,4-triazolo[1,5-a]-
pyridine (1u). This compound was obtained as a white solid. 1H
nmr: 2.50 (s, 3H, 7-CH3), 3.88 (s, 3H, 4-OCH3), 4.00 (s, 6H, 3
and 5-OCH3), 6.84 (d, 1H, 6-H, J=6.8Hz), 7.53 (m, 3H, 8-H and
phenyl protons), 8.45 (d, 1H, 5-H, J=6.8Hz). ms: m/z 299 (M+).
2-Phenyl-7-methyl-1,2,4-triazolo[1,5-a]pyridine (1v). This
compound was obtained as a white solid. 1H nmr: 2.49 (s, 3H, 7-
CH3), 6.83 (dd, 1H, 6-H, J=1.6Hz, J=6.9Hz), 7.48 (m, 4H, 8-H
and phenyl protons), 8.27 (m, 2H, phenyl protons), 8.46 (d, 1H,
5-H, J= 6.9Hz). ms: m/z 209 (M+).
(1m). This compound was obtained as a white solid. H nmr:
2.49 (s, 3H, 7-CH3), 3.92 (s, 3H, 2-OCH3), 6.83 (dd, 1H, 6-H,
J=1.4, 6.9Hz), 7.02 (dd, 1H, phenyl proton, J=2.2, 8.0Hz), 7.43
(t, 1H, phenyl proton, J=8.0Hz), 7.51 (s, 1H, 8-H), 7.81 (d, 1H,
phenyl proton, J=2.2Hz), 7.87 (d, 1H, phenyl proton, J=8.0Hz),
8.45 (d, 1H, 5-H, J=6.9Hz). ms: m/z 239 (M+).
2-(3-Methoxyphenyl)-7-methyl-1,2,4-triazolo[1,5-a]pyri-
1
dine (1n). This compound was obtained as a white solid. H
nmr: 2.49 (s, 3H, 7-CH3), 3.92 (s, 3H, 3-OCH3), 6.83 (dd, 1H, 6-
H, J=1.4, 6.9Hz), 7.02 (dd, 1H, phenyl proton, J=2.1, 8.1Hz),
7.40 (t, 1H, phenyl proton, J=8.1Hz), 7.51 (s, 1H, 8-H), 7.81 (d,
1H, phenyl proton, J=2.1Hz), 7.87 (d, 1H, phenyl proton,
J=8.1Hz), 8.45 (d, 1H, 5-H, J=6.9Hz). ms: m/z 239 (M+).
2-(4-Ethoxyphenyl)-7-methyl-1,2,4-triazolo[1,5-a]pyridine
(1o). This compound was obtained as a white solid. 1H nmr: 1.45
(t, 3H, -CH3, J=6.9Hz), 2.48 (s, 3H,7-CH3), 4.10 (q, 2H,
-CH2CH3, J=6.9Hz), 6.79 (dd, 1H, 6-H, J=1.5, 6.9Hz), 6.99 (d,
2H, phenyl protons, J=8.7Hz), 7.47 (d, 1H, 8-H, J=0.7Hz), 8.18
(d, 2H, phenyl protons, J=8.7Hz), 8.43 (d, 1H, 5-H, J=6.9Hz).
ms: m/z 253 (M+).
2-(4-Butoxyphenyl)-7-methyl-1,2,4-triazolo[1,5-a]pyridine
1
(1p). This compound was obtained as a white solid. H nmr: 0.99
2-(4-Benzyloxyphenyl)-5-methyl-1,2,4-triazolo[1,5-a]pyri-
dine (1w). This compound was obtained as a white solid. H
1
(t, 3H, -CH2CH3, J=7.4Hz), 1.52 (m, 2H, -CH2CH3), 1.81 (m, 2H,
-CH2CH2CH3), 2.49 (s, 3H, 7-CH3), 4.03 (t, 2H, -OCH2-, J=6.5Hz),
6.81 (dd, 1H, 6-H, J=1.1, 6.9Hz), 7.00 (d, 2H, phenyl protons,
J=8.8Hz), 7.50 (s, 1H, 8-H), 8.19 (d, 2H, phenyl protons, J=8.8Hz),
8.43 (d, 1H, 5-H, J=6.9Hz). ms: m/z 281 (M+).
nmr: 2.83 (s, 3H, 5-CH3), 5.15 (s, 2H, -CH2), 6.81 (d, 1H, 6-H,
J=7.0Hz), 7.10 (d, 2H, phenyl protons, J=8.8Hz), 7.35 (t, 1H, 7-
H, J=7.0Hz), 7.40-7.44 (m, 3H, phenyl protons), 7.47 (d,
J=7.4Hz, 2H, phenyl protons), 7.62 (d, 1H, 8-H, J=7.0Hz), 8.27
(d, 2H, phenyl protons, J=8.8Hz). ms: m/z 315 (M+).
2-(4-Benzyloxyphenyl)-7-methyl-1,2,4-triazolo[1,5-a]pyri-
1
dine (1q). This compound was obtained as a white solid. H
REFERENCES
nmr: 2.50 (s, 3H, 7-CH3), 5.14 (s, 2H, -CH2), 6.82 (dd, 1H, 6-H,
J=1.3, 6.9Hz), 7.10 (d, 2H, phenyl protons, J=8.8Hz), 7.34-7.50
(m, 6H, 8-H and phenyl protons), , 8.21 (d, 2H, phenyl protons,
J=8.8Hz), 8.44 (d, 1H, 5-H, J=6.9Hz). ms: m/z 315 (M+).
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Tetrahedron Lett., 1972, 40, 4133.
2-(4-Dimethylaminophenyl)-7-methyl-1,2,4-triazolo[1,5-a]-
pyridine (1r). This compound was obtained as a yellow
1
solid. H nmr: 2.46 (s, 3H, 7-CH3), 3.03 (s, 6H, -N(CH3)2),
6.74 (dd, 1H, 6-H, J=1.5, 6.9Hz), 6.80 (d, 2H, phenyl
protons, J=8.9Hz), 7.44 (s, 1H, 8-H), 8.13 (d, 2H, phenyl
protons, J=8.9Hz), 8.40 (d, 1H, 5-H, J=6.9Hz). ms: m/z 252
(M+).
2-(3,4-Dimethoxyphenyl)-7-methyl-1,2,4-triazolo[1,5-a]-
pyridine (1s). This compound was obtained as a white solid. 1H
nmr: 2.49 (s, 3H, 7-CH3), 3.96 (s, 3H, 4-OCH3), 4.02 (s, 3H, 3-