S. Mondal et al. / Tetrahedron Letters 51 (2010) 6111–6115
6115
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room temperature. The reaction mixture was diluted by adding methanol
(50 mL) and subsequently it was passed through Amberlite IR 120. The solvent
was evaporated under reduced pressure and the residue was washed with
diethyl ether, and dried under high vacuum to get compound 3 as a white solid
(0.7 g, yield 72%). Rf = 0.5 (30% methanol in dichloromethane).
Mp = decomposition occurs at >185 °C; ½a D25
¼ ꢀ65 (c 0.5, methanol); ESI-
ꢂ
10. Synthesis of (pyridine–Trp–Trp–OMe)2: pyridine dicarboxylic acid (0.15 g,
0.89 mmol) and 1-hydroxybenzotriazole (0.302 g, 1.97 mmol) was dissolved
in dichloromethane (10 mL) and dimethylformamide (5 mL) and the reaction
mixture was cooled to 0 °C under N2 atmosphere which was followed by the
addition of dicyclohexylcarbodiimide (0.426 g, 2.06 mmol) dissolved in
dichloromethane (20 mL). The reaction mixture was stirred at 0 °C for 1 h,
and then tryptophanyl tryptophan methyl ester hydrochloride (0.791 g,
1.79 mmol) was added to the reaction mixture which was followed by the
addition of triethylamine (0.62 mL, 4.48 mmol). The reaction mixture was
stirred for 12 h at room temperature. The precipitated dicyclohexylurea was
filtered off and the residue was washed with dichloromethane twice
(2 ꢁ 5 mL). The combined organic layer was evaporated under reduced
pressure and the residue was dissolved in dichloromethane. The organic
layer was washed with 10% NaHCO3 (2 ꢁ 10 mL) and brine solution
(2 ꢁ 10 mL), followed by the drying of the organic layer over anhydrous
sodium sulfate. Dichloromethane was evaporated and the crude solid product
was purified by silica gel column chromatography (pure compound was eluted
with 1.5% methanol in dichloromethane) to yield Py(WWOMe)2 as a white
solid (0.471 g, yield 56%). Rf = 0.5 (10% methanol in dichloromethane).
HRMS: [M+H]+, calcd (C51H46N9O8) = 912.3469; found = 912.3463; 1H NMR
(500 MHz, CD3OD, TMS, d ppm):3.14–3.24 (m, 4H); 3.30–3.38 (m, 4H, merged
with CD3OD signal); 4.64–4.68 (m, 2H); 4.76–4.79 (m, 2H); 6.79–6.96 (m, 8H);
6.97–7.05 (m, 3H); 7.13–7.15 (d, 2H, J = 8.4 Hz); 7.18–7.20 (d, 2H, J = 8.4 Hz);
7.26–7.30 (t, 1H, J = 8.0 Hz, 8.0 Hz); 7.41–7.43 (d, 2H, J = 8.0 Hz); 7.53–7.54 (d,
2H, J = 7.6 Hz); 7.96–8.00 (t, 1H, J = 8.4 Hz, 8.6 Hz); 8.06–8.09 (m, 2H); 8.42–
8.44 (br s, 4H). 13C NMR (125 MHz; CD3OD, TMS, d ppm): 26.98, 54.73, 64.99,
110.20, 111.39, 118.18, 118.49, 120.69, 123.58, 124.62, 127.23, 127.63, 136.07,
139.35, 148.82, 163.22, 171.08, 173.80.
11. Corbeil, M.-C.; Beauchamp, A. L. Can. J. Chem. 1988, 66, 2458–2464.
12. Lakowicz, J. R. In Principles of Fluorescence Spectroscopy; Plenum Press: New
York, 1983; pp 257–271.
13. Che, Y.; Yang, X.; Zang, L. Chem. Commun. 2008, 1413–1415.
14. (a) Ghosh, S.; Reches, M.; Gazit, E.; Verma, S. Angew. Chem., Int. Ed. 2007, 46,
2002–2004; (b) Joshi, K. B.; Verma, S. Angew. Chem., Int. Ed. 2008, 47, 2860–
2863; (c) Gour, N.; Purohit, C. S.; Verma, S.; Puri, R.; Ganesh, S. Biochem.
Biophys. Res. Commun. 2009, 378, 503–506.
15. Richard, A.; Marchi-Artzner, V.; Lalloz, M.-N.; Brienne, M.-J.; Artzner, F.; Gulik-
Krzywicki, T.; Guedeau-Boudeville, M.-A.; Lehn, J.-M. Proc. Natl. Acad. Sci. U.S.A.
2004, 101, 15279–15284.
16. Ghosh, S.; Singh, P.; Verma, S. Tetrahedron 2008, 64, 1250–1256.
17. (a) Guzzi, G.; La Porta, C. A. M. Toxicology 2008, 244, 1–12; (b) Sanfeliu, C.;
Sebastià, J.; Cristòfol, R.; Rodríguez-Farré, E. Neurotoxicol. Res. 2003, 5, 283–305.
18. (a) Landrigan, P. J. Curr. Opin. Pediatr. 2010, 22, 219–225; (b) Bernard, S.;
Enayati, A.; Redwood, L.; Roger, H.; Binstock, T. Med. Hypotheses 2001, 56, 462–
471.
Mp = 160–162 °C; ½a D25
ꢂ
¼ ꢀ43 (c 0.5, methanol); ESI-HRMS: [M+H]+, calcd
(C53H50N9O8) = 940.3782, found = 940.3782; 1H NMR (500 MHz, CDCl3, TMS, d
ppm): 3.22–3.34 (m, 6H); 3.42–3.49 (m, 2H); 3.73 (s, 6H); 4.95–4.98 (dd, 2H,
J = 5.5 Hz, 6.4 Hz); 5.16–5.21 (dd, 2H, J = 6.5 Hz, 7.1 Hz); 6.64–6.66 (d, 4H,
J = 5.5 Hz); 6.90–6.96 (m, 6H); 6.99–7.02 (t, 2H, J = 7.2 Hz, 7.3 Hz); 7.06–7.09 (t,
2H, J = 7.2 Hz, 7.2 Hz); 7.14–7.22 (m, 4H); 7.25–7.26 (2H, merged with CDCl3
signal); 7.36–7.38 (d, 2H, J = 6.5 Hz); 7.55–7.58 (t, 1H, J = 7.5 Hz, 7.7 Hz); 7.61–
7.63 (d, 2H, J = 7.6 Hz); 7.98–8.02 (m, 2H); 8.92 (br s, 2H). 13C NMR (125 MHz;
CDCl3, TMS, d ppm): 27.61, 28.47, 52.45, 52.70, 53.26, 109.29, 111.24, 111.67,
118.23, 119.48, 122.10, 122.33, 123.43, 124.21, 125.27, 127.24, 135.99, 136.42,
147.74, 163.33, 172.18, 172.40.
19. (a) Branch, D. R. Exp. Toxicol. Pathol. 2009, 61, 133–136; (b) Mutter, J.;
Naumann, J.; Schneider, R.; Walach, H.; Haley, B. Neuroendocrinol. Lett. 2005,
26, 439–446.
20. Viehweg, J. A.; Stamps, S. M.; Dertinger, J. J.; Green, R. L.; Harris, K. E.; Butcher,
R. J.; Andriole, E. J.; Poutsma, J. C.; Berry, S. M.; Bebout, D. C. Dalton Trans. 2010,
39, 3174–3176. and references cited therein.
Py(WWOMe)2 (0.1 mg, 0.106 mmol) was dissolved in methanol (5 mL)and 1 N
NaOH in water (0.26 mL) was added. The reaction mixture was stirred for 4 h at