PAPER
One-Pot Synthesis and Aromatization of 1,4-Dihydropyridines
2383
13C NMR (CDCl3): d = 23.3, 52.5, 123.1, 123.6, 126.5, 129.4, 134.2,
(4) (a) Itoh, T.; Nagata, K.; Okada, M.; Ohsava, A. Tetrahedron
138.1, 143.8, 148.0, 156.4, 167.8.
Lett. 1995, 36, 2269. (b) Itoh, T.; Nagata, K.; Matsuya, Y.;
Miyazaki, M.; Ohsava, A. J. Org. Chem. 1997, 62, 3582.
(c) Zhu, X.-Q.; Zhao, B.-J.; Cheng, J.-P. J. Org. Chem. 2000,
65, 8158.
Compound 6d
IR (KBr): 2926, 1687, 1593, 1533, 1436, 1364, 1262, 1203, 1072,
1025, 952, 927 cm–1.
(5) Ko, K.-Y.; Kim, J.-Y. Tetrahedron Lett. 1999, 40, 3207.
(6) Sausins, A.; Duburs, G. Heterocycles 1988, 27, 291.
(7) Vanden Eynde, J.-J.; Mayence, A.; Maquestiau, A.
Tetrahedron 1992, 48, 463.
1H NMR (CDCl3): d = 2.64 (s, 6 H, CH3), 2.78 (s, 6 H, CH3), 8.24
(s, 1 H, CH).
13C NMR (CDCl3): d = 25.0, 29.4, 130.1, 137.8, 160.3, 199.2.
(8) (a) Zolfigol, M. A.; Shirini, F.; Choghamarani, A. G.;
Mohammadpoor-Baltork, I. Green Chem. 2002, 4, 562.
(b) Zolfigol, M. A.; Kiany-Borazjani, M.; Sadeghi, M. M.;
Mohammadpoor-Baltork, I.; Memarian, H. R. Synth.
Commun. 2000, 30, 3919. (c) Zolfigol, M. A.; Kiany-
Borazjani, M.; Sadeghi, M. M.; Mohammadpoor-Baltork, I.;
Memarian, H. R. Synth. Commun. 2000, 30, 551.
(d) Zolfigol, M. A.; Kiany-Borazjani, M.; Sadeghi, M. M.;
Memarian, H. R.; Mohammadpoor-Baltork, I. Synth.
Commun. 2000, 30, 2945.
Compound 6e
IR (KBr): 2964, 1699, 1560, 1421, 1355, 1262, 1220, 1188, 1075
cm–1.
1H NMR (CDCl3): d = 0.92 (t, J = 7.3 Hz, 3 H, CH3), 1.42–1.55 (m,
2 H, CH2), 2.31–2.37 (m, 2 H, CH2), 2.45 (s, 6 H, CH3), 2.53 (s, 6
H, CH3).
13C NMR (CDCl3): d = 14.6, 22.7, 25.1, 32.6, 33.0, 135.4, 142.8,
152.2, 205.8.
(9) Pfister, J. R. Synthesis 1990, 689.
(10) Maquestiau, A.; Mayence, A.; Vanden Eynde, J.-J.
Tetrahedron Lett. 1991, 32, 3839.
(11) Mashraqui, S. H.; Karnik, M. A. Synthesis 1998, 713.
(12) Varma, R. S.; Kumar, D. Tetrahedron Lett. 1999, 40, 21.
(13) Mashraqui, S. H.; Karnik, M. A. Tetrahedron Lett. 1998, 39,
4895.
Compound 6f
IR (KBr): 2924, 1695, 1536, 1351, 1192, 736, 699 cm–1.
1H NMR (CDCl3): d = 2.02 (s, 6 H, CH3), 2.55 (s, 6 H, CH3), 7.58
(dt, J = 7.7, 1.4 Hz, 1 H, ArH), 7.65 (t, J = 7.9 Hz, 1 H, ArH), 8.13
(t, J = 1.5 Hz, 1 H, ArH), 8.31 (ddd, J = 8.0, 2.1, 1.5 Hz, 1 H, ArH).
(14) Nakamichi, N.; Kawashita, Y.; Hayashi, M. Synthesis 2004,
1015.
(15) Sabitha, G.; Reddy, G. S. K. K.; Reddy, C. S.; Fatima, N.;
Yadav, J. S. Synthesis 2003, 1267.
13C NMR (CDCl3): d = 22.8, 32.3, 124.0, 124.2, 130.2, 134.3, 135.3,
136.9, 139.7, 148.2, 153.5, 204.2.
(16) (a) Li, C. J.; Chang, T. H. Organic Reactions in Aqueous
Media; Wiley: New York, 1997. (b) Li, C. J. Chem. Rev.
1993, 93, 2023.
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32, 966. (b) Wang, G.-W.; Zhang, Z.; Dong, Y.-W. Org.
Process Res. Dev. 2004, 8, 18.
(18) Wang, G.-W.; Xia, J.-J.; Miao, C.-B.; Wu, X.-L., submitted.
(19) Balogh, M.; Hermecz, I.; Mészáros, Z.; Laszlo, P. Helv.
Chim. Acta 1984, 67, 2270.
(20) Khadilkar, B.; Borkar, S. Synth. Commun. 1998, 28, 207.
(21) Wang, B.; Hu, Y.; Hu, H. Synth. Commun. 1999, 29, 4193.
(22) Vanden Eynde, J.-J.; D’Orazio, R.; Haverbeke, Y. V.
Tetrahedron 1994, 50, 2479.
Acknowledgment
We are grateful for the financial support from National Science
Fund for Distinguished Young Scholars (20125205), Fund for Inno-
vative Research Groups of National Science Foundation of China
(20321101) and Anhui Provincial Bureau of Human Resources
(2001Z019).
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Synthesis 2005, No. 14, 2379–2383 © Thieme Stuttgart · New York