1
432
P. Kumar
Vol 47
General procedure for oxidative aromatization of 1,4-
C
5.49; N, 7.33.
19
H
20
N
2
O
6
: C, 61.29; H, 5.41; N, 7.53. Found: C, 61.15; H,
dihydropyridines with iodosobenzene and KBr. In a typical
experimental procedure, the iodosobenzene (1.1 mmol) and
KBr (0.1 mmol) were added to aqueous acetonitrile (15%, 20
mL), and mixture was stirred at room temperature for 5 min.
To this reaction mixture an appropriate 1,4-dihydropyridine
Diethyl-4-(2-nitrophenyl)-2,6-dimethylpyridine-3,5-dicar-
boxylate (2f). IR (KBr): 3005, 2983, 1725, 1605, 1548, 1512,
ꢁ
1 1
1358, 1278, 1191, 762, 700 cm . H NMR (CDCl
(t, J ¼ 7.11 Hz, 6H, CH ), 2.70 (s, 6H, CH ), 4.28 (q, J ¼
7.11 Hz, 4H, OCH ), 7.48 – 8.25 (m, 4H). Anal. Calcd. for
: C, 61.29; H, 5.41; N, 7.53. Found: C, 61.08; H,
): d 1.19
3
3
3
(
1.0 mmol) was added and stirred at room temperature for
2
time as indicated in Table 1. The progress of reaction was
monitored by TLC. After completion of the reaction and the
solvent was removed under vacuum to obtain the crude prod-
uct, which was purified by column chromatography (ethyl ace-
tate-hexane ¼ 1:5).
19 20 2 6
C H N O
5
.22; N, 7.63.
Diethyl-4-(4-methoxyphenyl)-2,6-dimethylpyridine-3,5-dicar-
boxylate (2g). IR (KBr): 3030, 2973, 1729, 1614, 1557, 1291,
ꢁ
1 1
1
7
6
107, 857, 835, 779 cm . H NMR (CDCl ): d 1.20 (t, J ¼
3
.12 Hz, 6H, CH ), 4.25 (q, J ¼ 7.12 Hz, 4H, OCH ), 2.66 (s,
General procedure for oxidative aromatization of 4-iso-
3
2
H, CH
3
), 3.82 (s, 3H, OCH
3
), 6.89 (d, J ¼ 8.6 Hz, 2H), 7.10
propyl/4-benzyl-1,4-dihydropyridines. The iodosobenzene
(1.1 mmol) and KBr (1.1 mmol) were added to aqueous aceto-
(d, J ¼ 8.6 Hz, 2H). Anal. Calcd. for C20
H, 6.49; N, 3.92. Found: C, 67.05; H, 6.40; N, 3.88.
Diethyl-4-(4-methylphenyl)-2,6-dimethylpyridine-3,5-dicar-
boxylate (2i). IR (KBr): 3013, 2983, 1727, 1571, 1446, 1239,
5
H23NO : C, 67.21;
nitrile (15%, 20 mL), and mixture was stirred at room temper-
ature for 5 min. Then 4-isopropyl/4-benzyl-1,4-dihydropyri-
dines (1.0 mmol) was added and reaction mixture was stirred
at room temperature for time indicated in Table 1. The pro-
gress of reaction was monitored by TLC. After completion of
the reaction, added acetic acid (1 mL) and the solvent was
removed under vacuum to obtain the crude product, which was
purified by column chromatography (ethyl acetate-hexane ¼
ꢁ
1 1
1
033, 821, 856, 775 cm . H NMR (CDCl ): d 1.23 (t, J ¼
3
7
.12 Hz, 6H, CH ), 2.37 (s, 3H, CH ), 2.64 (s, 6H, CH ), 4.29
3 3 3
(
q, J ¼ 7.12 Hz, 4H, OCH
J ¼ 6.8 Hz, 2H). Anal. Calcd. for C20
.79; N, 4.10. Found: C, 70.23; H, 6.56; N, 4.33.
Diethyl-4-phenyl-2,6-dimethylpyridine-3,5-dicarboxylate (2j). IR
KBr): 3014, 2986, 1723, 1591, 1498, 1302, 1250, 1170, 791,
2
), 7.11(d, J ¼ 6.8 Hz, 2H), 7.21 (d,
H
23NO
4
: C, 70.36; H,
6
1
:7).
1
All compounds were fully characterized by mp, IR, and H
(
7
6
ꢁ
1
1
60 cm
.
H NMR (CDCl
3
): d 1.23 (t, J ¼ 7.12 Hz,
2
NMR. These data are in full agreement with those previously
reported in literature [32].
H, CH ), 4.26 (q, J ¼ 7.12 Hz, 4H, OCH ), 2.65 (s, 6H,
3
CH ), 7.18(m, 2H), 7.30 (m, 3H). Anal. Calcd. for
3
Diethyl
2a). IR (KBr): 2981, 2870, 1726, 1568, 1446, 1285, 1220,
2,6-dimethyl-4-methylpyridine-3,5-dicarboxylate
C H NO : C, 69.71; H, 6.47; N, 4.28. Found: C, 69.83; H,
19 21
(
1
4
ꢁ
1 1
6
.38; N, 4.32.
Diethyl-4-(4-chlorophenyl)-2,6-dimethylpyridine-3,5-dicar-
106, 1045, 871, 777 cm . H NMR (CDCl
7.10 Hz, 6H, CH ), 2.19 (s, 3H, CH ), 2.51 (s, 6H, CH
.25 (q, J ¼ 7.10 Hz, 4H, OCH ). Anal. Calcd. for
3
): d ¼ 1.23 (t, J
¼
3
3
3
),
boxylate (2k). IR (KBr): 3025, 2984, 1729, 1580, 1231, 1104,
ꢁ
4
2
1 1
1
044, 858, 658 cm . H NMR (CDCl ): d 1.24 (t, J ¼ 7.12
C H NO : C, 63.38; H, 7.22; N, 5.28. Found: C, 63.23; H,
3
14
19
4
Hz, 6H, CH
CH
), 7.13(d, J ¼ 9.01 Hz, 2H), 7.32 (d, J ¼ 9.01 Hz, 2H).
Anal. Calcd. for C19 20ClNO : C, 63.07; H, 5.57; N, 3.87.
Found: C, 62.97; H, 5.44; N, 4.03.
3
), 4.27 (q, J ¼ 7.12 Hz, 4H, OCH
2
), 2.69 (s, 6H,
7
.32; N, 5.01.
Diethyl
2,6-dimethyl-4-ethylpyridine-3,5-dicarboxylate
2b). IR (KBr): 2992, 2879, 1731, 1576, 1438, 1286, 1112,
3
H
4
(
1
ꢁ
1 1
045, 923, 847, 751 cm . H NMR (CDCl
3
): d ¼ 1.08 (t, J
3
Diethyl-4-(2,
dicarboxylate (2l). IR (KBr): 3008, 2986, 1730, 1560, 1480,
4-dichlorophenyl)-2,6-dimethylpyridine-3,5-
¼
7.5 Hz, 3H, CH ), 1.25 (t, J ¼ 7.11 Hz, 6H, CH ), 2.49 (s,
3
6
H, CH ), 2.78(q, J ¼ 7.5 Hz, 2H, CH ), 4.25 (q, J ¼ 7.11
2 4
3
2
ꢁ
1 1
1
280, 1228, 1108, 856, 775, 700 cm . H NMR (CDCl ): d
Hz, 4H, OCH
.58; N, 5.01. Found: C, 64.78; H, 7.78; N, 4.94.
Diethyl 2,6-dimethyl-4-n-hexylpyridine-3,5-dicarboxylate
2c). IR (KBr): 2976, 2865, 1737, 1576, 1428, 1286, 1117,
). Anal. Calcd. for C15
H
21NO
: C, 64.50; H,
3
1
.23 (t, J ¼ 7.13 Hz, 6H, CH ), 4.33 (q, J ¼ 7.13 Hz, 4H,
7
3
OCH
for C19
7.77; H, 5.00; N, 3.49.
Diethyl-4-(3-bromophenyl)-2,6-dimethylpyridine-3,5-dicar-
boxylate (2m). IR (KBr): 3026, 2986, 1726, 1561, 1278, 1230,
2 3
), 2.67 (s, 6H, CH ), 7.15–7.42 (m, 3H). Anal. Calcd.
H
2 4
19Cl NO : C, 57.59; H, 4.83; N, 3.53. Found: C,
(
1
ꢁ
1 1
5
033, 926, 842, 755 cm . H NMR (CDCl
6.9 Hz, 3H, CH ), 1.26 (t, J ¼ 7.10 Hz, 6H, CH ), 1.33 –
3
): d ¼ 1.06 (t, J
3
¼
3
1
.43 (m, 8H), 2.49 (s, 6H, CH ), 2.54 (t, J ¼ 6.9Hz, 2H,
2 2
3
ꢁ
1 1
1
108, 1035, 865, 787, 698 cm . H NMR (CDCl ): d 1.22 (t,
3
CH
), 4.25 (q, J ¼ 7.11 Hz, 4H, OCH
: C, 68.03; H, 8.71; N, 4.18. Found: C, 67.98; H,
.78; N, 4.27.
Diethyl-4-(4-nitrophenyl)-2,6-dimethylpyridine-3,5-dicar-
boxylate (2d). IR (KBr): 3012, 2977, 1723, 1557, 1518, 1349,
). Anal. Calcd. for
J ¼ 7.11 Hz, 6H, CH ), 4.31 (q, J ¼ 7.11 Hz, 4H, OCH ),
C
8
19
H
29NO
4
3
2
2
.66 (s, 6H, CH
20BrNO C, 56.17; H, 4.96; N, 3.45. Found: C, 56.30; H,
.10; N, 3.27.
Diethyl 2,6-dimethylpyridine-3,5-dicarboxylate (3). IR
KBr): 2974, 1721, 1588, 1555, 1298, 1254, 1123, 1022, 777
3
), 7.20 – 7.44 (m, 4H). Anal. Calcd. for
C
5
19
H
4
ꢁ
1 1
1
7
4
2
116, 865, 843, 745 cm . H NMR (CDCl
.10 Hz, 6H, CH ), 2.69 (s, 6H, CH ), 4.27 (q, J ¼ 7.10 Hz,
3
): d 1.20 (t, J ¼
(
3
3
ꢁ
1 1
cm . H NMR (CDCl ): d ¼ 1.35 (t, J ¼ 7.11 Hz, 6H, CH ),
H, OCH ), 7.41(d, J ¼ 8.2 Hz, 2H), 8.22 (d, J ¼ 8.2 Hz,
3
3
2
2
.74 (s, 6H, CH
Calcd. for C13H17NO : C, 62.14; H, 6.82; N, 5.57. Found: C,
4
3
), 4.28 (q, J ¼ 7.11 Hz, 4H, OCH
2
). Anal.
20 2 6
H). Anal. Calcd. for C19H N O : C, 61.29; H, 5.41; N, 7.53.
Found: C, 61.31; H, 5.36; N, 7.50.
Diethyl-4-(3-nitrophenyl)-2,6-dimethylpyridine-3,5-dicar-
61.92; H, 7.02; N, 5.44.
boxylate (2e). IR (KBr): 3015, 2980, 1716, 1590, 1555, 1520,
ꢁ
1 1
1
358, 1280, 1183, 870, 785, 715 cm . H NMR (CDCl ): d
Acknowledgments. The author wishes to express his gratitude
to the authorities of Guru Nanak Khalsa College, Yamuna Nagar
for providing research facilities to complete this project.
3
1
.21 (t, J ¼ 7.11 Hz, 6H, CH
3 3
), 2.70 (s, 6H, CH ), 4.25 (q, J
¼
7.11 Hz, 4H, OCH ), 7.58 – 8.28 (m, 4H). Anal. Calcd. for
2
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet