November 2009
Facile, Efficient, and Eco-Friendly Synthesis of Benzo[b]pyran-2-imines
over MgO and Transformation to the Coumarin Derivatives
1395
C10H6N2O2: C, 64.52; H, 2.25; N, 15.05. Found: C, 64.58; H,
2.19; N, 15.11.
Acknowledgment. The authors thank the office of the Research
Vice Chancellor of Azerbaijan University of Tarbiat-Moallem.
Hydrolysis of the freshly prepared benzo[b]pyran-2-
imines under acidic conditions afforded to related coumar-
ins.
REFERENCES AND NOTES
6-Hydroxy-2-oxo-2H-chromene-3-carbonitrile (4a). IR (KBr,
kmax ¼ cmꢀ1: 3415 (broad, OH), 2229 (CN), 1712 (C¼¼O),
1604 (C¼¼C); 1H NMR: d 8.28 (s, 1H), 7.70 (dd, 1H, J ¼
7.88, 1.28 Hz), 7.39 (d, 1H, J ¼ 7.85 Hz), 7.32 (d, 1H, J ¼
1.28 Hz); 13C NMR: d 159.5, 154.0, 136.5, 130.8, 126.5,
118.5, 118.3, 117.9, 115.2, 103.8; Anal. Calcd. for C10H6NO3:
C, 64.18; H, 2.69; N, 7.48. Found: C, 64.28; H, 2.66; N, 7.39.
8-Hydroxy-2-oxo-2H-chromene-3-carbonitrile (4b). IR (KBr,
kmax ¼ cmꢀ1: 3371 (broad, OH), 2223 (CN), 1708 (C¼¼O),
1610 (C¼¼C); 1H NMR: d 8.24 (s, 1H), 7.68 (dd, 1H, J ¼
8.15, 8.10 Hz), 7.49 (dd, 1H, J ¼ 8.15, 1.75 Hz), 7.41 (dd,
1H, J ¼ 8.10, 1.70 Hz); 13C NMR: d 160.1, 151.4, 139.7,
132.1, 125.1, 119.0, 117.2, 115.4, 114.02, 101.1; Anal. Calcd.
for C10H6NO3: C, 64.18; H, 2.69; N, 7.48. Found: C, 64.28;
H, 2.66; N, 7.39.
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2-Oxo-2H-chromene-3-carbonitrile (4c). IR (KBr, kmax
¼
cmꢀ1: 2229 (CN), 1711 (C¼¼O), 1608 (C¼¼C); 1H NMR: d
8.19 (s, 1H), 7.65 (dd, 1H, J ¼ 7.89, 1.22 Hz), 7.49 (m, 2H),
7.44 (dd, 1H, J ¼ 8.10, 1.34 Hz); 13C NMR: d 162.5, 154.0,
136.5, 130.8, 126.5, 118.5, 118.3, 117.9, 115.2, 103.8; Anal.
Calcd. for C10H5NO2: C, 70.18; H, 2.94; N, 8.18. Found: C,
70.23; H, 2.91; N, 8.21.
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Ethyl 6-Hydroxy-2-oxo-2H-chromene-3-carboxylate (4d). IR
kmax ¼ cmꢀ1: 3313 (broad, OH), 3030, 2989, 1739 (C¼¼O),
1
1672 (C¼¼O), 1612 (C¼¼C); H NMR (300 MHz, DMSO-d6) d
8.52 (s, 1H), 7.61 (dd, 1H, J ¼ 8.13, 1.30 Hz), 7.30 (d, 1H, J
¼ 1.32 Hz), 7.32 (d, 1H, J ¼ 8.09 Hz), 4.20 (q, 2H, J ¼ 7.21
Hz), 1.29 (t, 3H, J ¼ 7.21 Hz); 13C NMR (75MHz, DMSO-
d6) d 164.3, 152.2, 146.0, 142.6, 137.8, 119.53, 118.6, 116.1,
115.5, 115.1, 63.0, 18.6.
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M. L.; Sreedhar, B. J Am Chem Soc 2005, 127, 13167. (b) Choudary,
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uid as reagent and reaction medium for the one-pot Horner-Wadswor-
th-Emmons type reaction under microwave irradiation. Synth.
Commun, to appear.
Ethyl 8-Hydroxy-2-oxo-2H-chromene-3-carboxylate (4e). IR
kmax ¼ cmꢀ1: 3313 (broad, OH), 3030, 2989, 1739 (C¼¼O),
1
1672 (C¼¼O), 1672 (C¼¼O); H NMR (300 MHz, DMSO-d6) d
8.01 (s, 1H), 7.60 (t, 1H, J ¼ 7.91 Hz), 7.38 (dd, 1H, J ¼
7.91, 1.95 Hz), 7.32 (dd, 1H, J ¼ 7.91, 1.95Hz), 4.15 (q, 2H,
J ¼ 7.18 Hz), 1.21 (t, 3H, J ¼ 7.18 Hz); 13C NMR (75MHz,
DMSO-d6) d 165.9, 156.4, 148.4, 145.9, 141.2, 123.4, 121.1,
121.0, 118.5, 117.3, 61.9, 18.4.
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Wiley-VCH: Weinheim, Germany, 2003.
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102, 3667.
7-Hydroxy-2-oxo-2H-chromene-3-carbonitrile (4f). IR (KBr,
kmax ¼ cmꢀ1: 3370 (broad, OH), 2220 (CN), 1709 (C¼¼O),
1
[18] Wilkes, J. S. Green Chem 2002, 4, 73.
[19] Shi, D. -Q.; Yang, F.; Ni, S. -N. J Heterocycl Chem 2009,
46, 469.
1613 (C¼¼C); H NMR(300 MHz, DMSO-d6): d 8.19 (s, 1H),
8.07 (s, 1H), 7.69 (dd, 1H, J ¼ 7.81, 1.29 Hz), 7.43 (d, 1H, J
¼ 7.81 Hz), 7.29 (d, 1H, J ¼ 1.29 Hz); 13C NMR: d 160.1,
156.5, 143.8, 136.6, 129.1, 123.1, 120.5, 119.8, 118.3, 108.8;
Anal. Calcd. for C10H6NO3: C, 64.18; H, 2.69; N, 7.48. Found:
C, 64.30; H, 2.61; N, 7.50.
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Chem 2007, 44, 867.
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J Heterocycl Chem 2009, 46, 74.
5-Hydroxy-2-oxo-2H-chromene-3-carbonitrile (4g). IR (KBr,
kmax ¼ cmꢀ1: 3383 (broad, OH), 2223 (CN), 1719 (C¼¼O),
[22] Wang, R.; Twamley, B.; Shreeve, J. M. J Org Chem 2006,
71, 426.
1
1611 (C¼¼C); H NMR(300 MHz, DMSO-d6): d 8.14 (s, 1H),
[23] Li, S.; Lin, Y.; Xie, H.; Zhang, S.; XuJ. Org Lett 2006, 8,
391.
7.61 (dd, 1H, J ¼ 8.11, 1.31 Hz ), 7.31 (dd, 1H, J ¼ 7.98,
1.31 Hz), 7.29 (dd, 1H, J ¼ 7.98, 8.11 Hz); 13C NMR: d
165.0, 156.7, 143.2, 136.8, 130.8, 124.4, 120.2, 119.4, 118.5,
109.1; Anal. Calcd. for C10H6NO3: C, 64.18; H, 2.69; N, 7.48.
Found: C, 64.27; H, 2.64; N, 7.52.
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893.
[25] Branco, L. C.; Serbanovic, A.; Ponte, M. N.; Afonso, C. A.
M. Chem Commun 2005, 107.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet