4
Tetrahedron Letters
5.
a) Du, Z.;Ng, H.; Zhang, K.;Zeng, H.; Wang, J.; Org. Biomol.
disappearing of starting material and formation of new spot) was
observed by TLC of Ethyl acetate and hexane (15: 85%). After
the formation of the product, the crude reaction mixture was
extracted with EtOAc (2 × 10 mL), the combined organic layers
were washed with H2O (10 mL), and dried (Na2SO4). The solvent
was removed in vacuo and the residue was chromatographed on
silica gel (60–120 mesh) to afford the pure products in 65-90%
yields (Table 2 and 3).
Chem. 2011, 9, 6930. (b) Sun, Y.; Liu, G.; Huang, H.; Yu, P.
Phytochemistry. 2012, 75, 169.
a) Coppola, G. M.; Dodsworth, R.W.; synthesis, 1981. 523. b)
Shcherbakov, K.V.; Burgart, Y.V.; Saloutin, V.L.; Russ. J. Org.
Chem, 2013, 49, 719. c) Hormi, O. E. O.; Moisio, M. R.; Sund,
B. C. J. Org. Chem. 1987, 52, 5272.
6.
7.
8.
9.
Wang, N.; Cai, S.; Zhou, C.; Lu, P.; Wang, Y. Tetrahedron.
2013, 69, 647
Ethyl 2-(4-chlorophenyl)-4-oxo-4H-chromene-3-carboxylate
(4aa):
Costa, A.M. B. S. R. C. S.; Dean, F. M.; Jones, M. A.; Varma, R.
S. J. Chem. Soc., Perkin Trans. 1; 1985, 799
Zanwar, M. R.;Raihan, M. J.; Gawande, S. D.;Kavala, V.;
Janreddy, D.; Kuo, C-W.;Ambre, R.; Yao, C-F. J. Org. Chem.
2012, 77, 6495.
Orange semi solid (0.262g, 80%),
IR (KBr): 1731, 1645, 1575, 1466, 1381, 1090, 1015, 761cm-1.
1H NMR (400 MHz, CDCl3): 8.22 (d, J = 8.0 Hz, 1H), 7.69 (d, J
= 6.8 Hz, 3H), 7.50-7.43 (m, 4H), 4.25 (q, J = 6.0 Hz, 2H), 1.19 (t,
J = 6.8 Hz, 3H) ppm.
10. Yoshida, M; Saito, K; Fujino, Y; Doi, T. Tetrahedron, 2014, 70,
3452
11. Hsu, J-P; Wong, J-J; Ind. Eng. Chem. Res. 2006, 45, 2672
12. Ragnarsson, U.; Grehn, L. Acc. Chem. Res. 1998, 31, 494
13. Ko, K.; Nakano, K.; Watanabe, S.; Ichikawa, Y.; Kotsuki, H.
Tetrahedron Lett. 2009, 50, 4025
13C NMR (100 MHz, CDCl3): 174.7, 164.8, 161.4, 155.5, 137.8,
134.4, 130.2, 129.3, 129.0, 125.8, 125.7, 122.8, 118.3, 118.0, 61.9,
13.8 ppm.
MS (ESI): [M+ H+], Calcd. For: C18H14ClO4 (329.0575); Found:
329.0579.
14. Zhao, G.-L.; Huang, J. W.; Shi, M. Org. Lett. 2003, 24, 4737
15. Khan, A. T.; Lal, M; Ali, S.; Khan; M. M.; Tetrahedron Lett.
2011, 52, 5327.
16. (a)Shang, Y.; Wang, C.; He, X.; Ju, K.; Zhang, M.; Yu, S.; Wu, J.
Tetrahedron. 2010, 66, 9629. (b) Dadwal, M.; Mobin, S. M.;
Namboothiri, I. N. N. Org. Biomol. Chem. 2006, 4, 2525. (c)
Meng, L.-G.; Li, C.-T.; Zhang, J.-F.; Xiao, G.-Y.; Wang, L. RSC
Adv. 2014, 4, 7109.
17. General procedure for the formation of 3-substituted flavone
derivatives (4aa-4am and 4ba-4bd): 4-hydroxycumarin (1
mmol), different derivatives of β-nitrostyrene (1 mmol), various
alcohols or amines (4 mmol) and DMAP (1 mmol) were taken in
a round bottom flask. The reaction mixtures were refluxed at 70-
80C. The completion of the reaction (directed by the
Ethyl 4-oxo-2-phenyl-4H-chromene-3-carboxylate (4ab):
Yellow solid (0.249 g, 85%), mp 80-810C.
IR (KBr): 1729, 1638, 1567, 1436, 1396, 1089, 760 cm1.
1H NMR (400 MHz, CDCl3): 8.23 (d, J= 7.2 Hz, 1H), 7.73 (d, J =
7.2 Hz, 2H), 7.68 (d, J = 7.2 Hz, 1H), 7.56-7.45 (m, 4H), 7.42 (t,
J= 6.8 Hz, 1H), 4.25 (q, J = 6.8 Hz, 2H), 1.14(t, J = 7.2 Hz, 3H)
ppm.
13C NMR (100 MHz, CDCl3): 175.1, 165.1, 163.1, 155.8, 134.4,
131.9, 131.7, 128.8, 128.1, 126.1, 125.7, 123.2, 118.1, 61.9, 13.9
ppm.
MS (ESI): [M+ H+], Calcd. For: C18H15O4 (295.0965); Found:
295.0970
.