5374
B. Das et al. / Tetrahedron Letters 48 (2007) 5371–5374
(1 mmol) and HClO4ÆSiO2 (50 mg) in CH3CN (5 mL), 1,2-
Acknowledgement
diamine (1.25 mmol) was added slowly and the mixture
was stirred at room temperature. The reaction was
monitored by TLC. After completion, the reaction mix-
ture was filtered. The catalyst was washed with CHCl3
(2 · 5 mL), EtOH (2 · 5 mL) and Et2O (2 · 5 mL) and
subsequently dried at 80 ꢁC for reuse. The filtrate was
concentrated and the residue was subjected to column
chromatography (silica gel, hexane–EtOAc) to obtain pure
quinoxaline or dihydropyrazine.
The recovered catalyst was reused three times with only a
little variation in the yields of the products. For example,
in the synthesis of quinoxaline 3a (reaction time: 15 min in
each case) the catalyst was used in four consecutive runs to
furnish 3a in yields of 94%, 94%, 91% and 90%.
The authors thank CSIR and UGC, New Delhi, for
financial assistance.
References and notes
1. (a) Jaso, A.; Zarranz, B.; Aldana, I.; Monge, A. J. Med.
Chem. 2005, 48, 2019; (b) Carta, A.; Paglietti, G.;
Nikookar, M. E. R.; Sanna, P.; Sechi, L.; Zanetti, S.
Eur. J. Med. Chem. 2002, 37, 355.
2. Seitz, L. E.; Suling, W. J.; Reynolds, R. C. J. Med. Chem.
2002, 45, 5604.
3. (a) Zaragoza, F.; Stephensen, H. J. Org. Chem. 1999, 64,
2555; (b) Wu, Z.; Ede, N. J. Tetrahedron Lett. 2001, 42,
8115.
4. (a) Katoh, A.; Yoshida, T.; Ohkanda, J. Heterocycles
2000, 52, 911; (b) Thomas, K. R. J.; Velusamy, M.; Lin, J.
T.; Chuen, C.-H.; Tao, Y.-T. Chem. Mater. 2005, 17, 1860;
(c) Dailey, S.; Feast, W. J.; Peace, R. J.; Sage, I. C.; Till,
S.; Wood, E. L. J. Mater. Chem. 2001, 11, 2238; (d)
Conversion of 6 into 5a: A suspension of 6 (1 mmol) and
HClO4ÆSiO2 (30 mg) in CH3CN (5 mL) was stirred at
room temperature. The conversion was followed by TLC.
After completion (10 min), the reaction mixture was
filtered. The filtrate was concentrated and the viscous
mass was purified by column chromatography (silica gel,
hexane–EtOAc, 4:1) to furnish 5a (yield 95%).
Spectral (1H NMR and MS) and elemental analysis data
for new products are given below.
Sascha, O.; Rudiger, F. Synlett 2004, 1509; (e) Sessler, J.
¨
L.; Maeda, H.; Mizuno, T.; Lynch, V. M.; Furuta, H. J.
Am. Chem. Soc. 2002, 124, 13474; (f) Crossley, M. J.;
Johnston, L. A. Chem. Commun. 2002, 1122.
1
Compound 3b: H NMR (200 MHz, CDCl3): d 9.27 (1H,
s), 8.18 (2H, d, J = 8.0 Hz), 8.13–8.03 (2H, m), 7.82–7.67
(2H, m), 7.51 (2H, d, J = 8.0 Hz); EIMS: m/z 240, 242
(M+Å); Anal. Calcd for C14H9ClN2: C, 69.85; H, 3.74; N,
11.64. Found: C, 69.91; H, 3.68; N, 11.72.
5. (a) Yamaguchi, T.; Matsumoto, S.; Watanabe, K. Tetra-
hedron Lett. 1998, 39, 8311; (b) Takeda, O.; Takechi, S.;
Katoh, T.; Yamaguchi, T. Biol. Pharm. Bull. 2005, 28,
1161; (c) Singh, S. K.; Saibaba, V.; Ravikumar, V.;
Rudrawar, S. V.; Daga, P.; Rao, C. S.; Akhila, V.; Hegde,
P.; Rao, Y. K. Bioorg. Med. Chem. 2004, 12, 1881.
6. (a) Brown, D. J. Quinoxalines Supplements II. In The
Chemistry of Heterocyclic Compounds; Taylor, E. C.,
Wipf, P., Eds.; John Wiley & Sons: New Jersey, 2004; (b)
Bhosale, R. S.; Sarda, S. R.; Andhapure, S. S.; Jadhav, W.
N.; Bhusare, S. R.; Pawar, R. P. Tetrahedron Lett. 2005,
46, 7183; (c) More, S. V.; Sastry, M. N. V.; Yao, C.-F.
Green Chem. 2006, 8, 91.
1
Compound 5b: H NMR (200 MHz, CDCl3): d 8.25 (1H,
d, J = 2.4 Hz), 7.81 (2H, d, J = 8.0 Hz), 7.40 (2H, d,
J = 8.0 Hz), 2.89–2.58 (2H, m), 2.51–2.32 (2H, m), 2.02–
1.76 (2H, m), 1.71–1.29 (4H, m); EIMS: m/z 246, 248
(M+Å); Anal. Calcd for C14H15ClN2: C, 68.15; H, 6.08; N,
11.36. Found: C, 68.10; H, 6.01; N, 11.45.
1
Compound 5c: H NMR (200 MHz, CDCl3): d 8.31 (1H,
br s), 7.74 (2H, d, J = 8.0 Hz), 7.19 (2H, d, J = 8.0 Hz),
2.90–2.57 (2H, m), 2.52–2.17 (5H, m), 2.08–1.72 (2H, m),
1.64–1.09 (4H, m); EIMS: m/z 226 (M+Å); Anal. Calcd for
C15H18N2: C, 79.65; H, 7.96; N, 12.39. Found: C, 79.73;
H, 7.88; N,12.28.
7. Aparicio, D.; Attanasi, O. A.; Filippone, P.; Ignacio, R.;
Lillini, S.; Mantellini, F.; Palacios, F.; de los Santos, J. M.
J. Org. Chem. 2006, 71, 5897.
1
Compound 5e: H NMR (200 MHz, CDCl3): d 8.32 (1H,
br s), 7.78 (2H, d, J = 8.0 Hz), 7.40 (2H, d, J = 8.0 Hz),
3.72–3.63 (2H, m), 3.61–2.99 (2H, m); EIMS: m/z 192, 194
(M+Å); Anal. Calcd for C10H9ClN2: C, 62.34; H, 4.67; N,
14.54. Found: C, 62.27; H, 4.72; N, 14.47.
8. (a) Raw, S. A.; Wilfred, C. D.; Taylor, R. J. K. Org.
Biomol. Chem. 2004, 2, 788; (b) Kim, S. Y.; Park, K. H.;
Chung, Y. K. Chem. Commun. 2005, 1321; (c) Robinson,
R. S.; Taylor, R. J. K. Synlett 2005, 1003.
9. Singh, S. K.; Gupta, P.; Duggineni, S.; Kundu, B. Synlett
2003, 2147.
1
Compound 6: H NMR (200 MHz, CDCl3): d 7.91 (2H,
dd, J = 8.0, 2.0 Hz), 7.45–7.29 (3H, m), 6.69 (1H, br s),
3.28–3.11 (2H, m), 2.54–2.33 (1H, m), 2.10–1.79 (3H, m),
1.59–1.17 (6H, m); EIMS: m/z 214 (M+Å); Anal. Calcd for
C14H18N2: C, 78.50; H, 8.41; N, 13.08. Found: C, 78.60;
H, 8.36; N, 12.96.
10. Antoniotti, S.; Dunach, E. Tetrahedron Lett. 2002, 43, 3971.
˜
11. (a) Das, B.; Majhi, A.; Banerjee, J. Tetrahedron Lett. 2006,
47, 7619; (b) Das, B.; Venkateswarlu, K.; Krishnaiah, M.;
Holla, H. Tetrahedron Lett. 2006, 47, 8693.
13. Chakraborti, A. K.; Gulhane, R. Chem. Commun. 2003,
1896.
12. General procedure for the preparation of quinoxalines or
dihydropyrazines: To a suspension of a a-bromoketone