Month 2013
Coumarins: Facile and Expeditious Synthesis via Keggin‐Type
Heteropolycompounds Under Solvent‐Free Condition
7,4‐Dimethylcoumarin (Table 4, entry 4). mp 134–135°C;
IR: 3030–2970 (C═H), 1705 C─O), 1071 (C═O) cm−1
;
1H‐NMR (CDCl3): δ 2.61 (s, 3H, Me), 2.84 (s, 3H, Me),
6.38 (s, 1H, C─CH), 7.08–7.64 (m, 3H).
7,8‐Dihydroxy‐4‐methylcoumarin (Table 4, entry 5). mp
233–235°C; IR: 3235–3101 (C═H), 1650 (C─O), 1061 (C═O) cm−1;
1H‐NMR (CDCl3): δ 2.43 (s, 3H, Me), 6.20 (s, 1H, C─CH),
6.93–7.29 (m, 2H), OH was not observed.
5‐Hydroxy‐4,7‐dimethylcoumarin (Table 4, entry 6). mp
261–262°C; IR: 3155–3091 (C═H), 1661 (C─O), 1072 (C═O) cm−1;
1H‐NMR (CDCl3): δ 2.32 (s, 3H, Me), 2.58 (s, 3H, Me), 6.02 (s, 1H,
C─CH), 6.61 (s, 1H), 6.70 (s, 1H), 10.55 (s, 1H, OH).
4‐Methylcoumarin (Table 4, entry 7). mp 81–83°C; IR:
1
3110–2998 (C═H), 1666 (C─O), 1058 (C═O) cm−1; H‐NMR
Figure 2. Synthesis of 7‐hydroxy‐4‐methyl coumarin with reused cata-
lysts after 17, 11, and 20 min for PW/ SiO2, PW/ TiO2, and PW/C,
respectively.
(CDCl3): δ 2.63 (s, 3H, Me), 6.51 (s, 1H, C─CH), 7.28–7.61
(m, 4H).
8‐Nitro‐4‐methylcoumarin (Table 4, entry 8). mp 184–185°C;
1
IR: 3011–2981 (C═H), 1625 (C─O), 1052 (C═O) cm−1; H‐NMR
(CDCl3): δ 2.41 (s, 3H, Me), 6.19 (s, 1H, C─CH), 7.37 (m, 1H),
7.73 (m, 1H), 7.94 (m, 1H).
K5CoW12O40 and K7PTi2W10O40 catalysts were prepared and
7‐Amino‐4‐methylcoumarin (Table 4, entry 9). mp 223–225°C;
IR: 3079–2881 (C═H), 1665 (C─O), 10565 (C═O) cm−1; 1H‐NMR
(CDCl3): δ 2.01 (s, 3H, Me), 4.53 (s, 2H, NH2), 6.33 (s, 1H,
C─CH), 6.72 (m, 1H), 7.68 (m, 1H), 7.89 (m, 1H).
purified by literature procedures [52], [53].
PW/support catalysts were prepared by impregnation method.
The solution of PW was used to impregnate activated carbon, sil-
ica, alumina, titania, KSF, and K10 montmorillonite as supports,
followed by drying as described in our previously published arti-
cles [45], [46].
4‐Methylnaphtho‐(1,2‐b)‐pyran‐2‐one (Table 4, entry 11).
mp 151–154°C; IR: 3061–3019 (C═H), 1720 (C─O), 1090
(C═O) cm−1 1H‐NMR (CDCl3): δ 2.60 (s, 3H, Me), 6.43 (s,
;
General procedure for preparation of coumarins. The
Pechmann reaction was carried out under solvent and solvent‐
free conditions. (a) solvent: a mixture of methylacetoacetate and
resorcinol with molar ratio of 1:1 and solvent (4 mL) was
stirred at room temperature in the presence of appropriate
amount of the solid catalysts (0.5–2 mol %). Progress of the
reaction was monitored by TLC. The catalyst was separated by
filtration and washed with CH3CN. The crude of the reaction
was washed with a solution of 5% NaOH (3 × 5 mL) and then
with water. The organic solution was dried over anhydrous
Na2SO4, filtered, and the solvent was evaporated and
subsequently the residue was recrystallized to obtain
corresponding coumarins. (b) solvent free: 1 mmol phenolic
1H, C─CH), 7.67 (m, 2H), 7.82 (m, 2H), 8.02 (m, 1H), 8.51
(m, 1H).
Acknowledgments. The authors thank the Razi University Research
Council and Kermanshah Oil Refining Company for support of this
work.
REFERENCES AND NOTES
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[2] OKennedy, R.; Thornes, R. D. Coumarins, Biology,
Applications and Mode of Action; Wiley: Chichester, 1997.
[3] Zahradnik, M. The Production and Application of Fluorescent
Brightening Agent; Wiley: Chichester, 1992.
[4] Maeda, M. Laser Day; Academic Press: New York, 1994.
[5] Wang, C. J.; Hsieh, Y. J.; Chu, C. Y.; Lin, Y. L.; Tseng, T. H.
Cancer Lett 2002, 183, 163.
[6] Lin, C. M.; Huang, S. T.; Lee, F. W.; Kuo, H. S.; Lin, M. H.
Bioorg Med Chem 2006, 14, 4402.
[7] Curini, M.; Epifano, F.; Maltese, F.; Marcotullio, M. C.;
Gonzales, S. P.; Rodriguez, J. C. Aust J Chem 2003, 56, 59.
[8] Huang, L.; Yuan, X.; Yu, D.; Lee, K. H.; Chen, H. C. Virology
2005, 332, 623.
substrate and
1 mmol β‐ketoester were mixed and an
appropriate amount of the catalyst (0.5–2 mol %) was added.
The reaction mixture was crushed at room temperature or at 60°
C. Progress of the reaction was monitored by TLC. After
completion of the reaction, the mixture was extracted with hot
toluene (3 × 15 mL). The solvent was evaporated and crude
product was recrystallized from a mixture of water and ethanol.
All products were identified by comparing of their spectral data
with those of the authentic samples [54–59].
7‐Hydroxy‐4‐methylcoumarin (Table 4, entry 1). mp 183–184°
C; IR: 3086–3012 (C═H), 1676 (C─O), 1063 (C═O) cm−1
;
1H‐NMR (CDCl3): δ 2.42 (s, 3H, Me), 6.41 (s, 1H, C─CH), 7.76
(m, 1H), 7.83 (q, 1H), 8.01 (m, 1H), OH was not observed.
8‐Hydroxy‐4‐methylcoumarin (Table 4, entry 2). mp 168–171°C;
[9] Bhat, M. A.; Siddiqui, N.; Khan, S. A. Indian J Pharm Sci
2006, 68, 120.
[10] Singer, L. A.; Kong, N. P. J Am Chem Soc 1966, 88, 5213.
[11] Tyagi, A. K.; Raj, H. G.; Vohra, P.; Gupta, G.; Kumari, R.;
Kumar, P.; Gupta, R. K. Eur J Med Chem 2003, 40, 413.
[12] Modrana, J. N.; Nawrot, E.; Graczyk, J. Eur J Med Chem
2006, 41, 1301.
[13] Sardari, S.; Mori, Y.; Horita, K.; Micetich, R. G.; Nishibe, S.;
Daneshtalab, M. Bioorg Med Chem 1999, 7, 1933.
[14] Elinos‐Baez, C. M.; Leon, F.; Santos, E. Cell Biol Int 2005,
29, 703.
IR: 3271–3085 (C═H), 1690 (C─O), 1060 (C═O) cm−1
;
1H‐NMR (CDCl3): δ 2.41 (s, 3H, Me), 6.23 (s, 1H, C─CH), 6.98
(m, 1H), 7.33 (m, 1H), 7.37 (m, 1H), OH was not observed.
6‐Hydroxy‐4‐methylcoumarin (Table 4, entry 3). mp 240–242°
C; IR: 3275–3080 (C═H), 1690 (C─O), 1065 (C═O) cm−1
;
1H‐NMR (CDCl3): δ 2.52 (s, 3H, Me), 6.29 (s, 1H, C─CH),
6.32 (m, 1H), 7.00 (m, 1H), 7.10 (m, 1H), OH was not observed.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet