Mar-Apr 2007
Fluorescence of 2-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)imidazo[1,2-a]pyridine
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purification was performed by recrystallization from hexane-
acetone to give white crytals of 1: mp 262-263 °C; FT/IR (KBr):
ν 3173, 3152, 1638, 1517, 1483, 1430, 1366, 1083, 991, 860,
755, 739 cm-1; UV-vis (toluene): λmax (log ε/L mol-1 cm-1) 313
(sh, 4.03), 326 (4.12), 340 nm (3.97); 1H nmr (400 MHz,
CDCl3): δ 6.95 (dd, 1H, J = 6.8, 7.2 Hz), 7.34 (dd, 1H, J = 9.2,
6.8 Hz), 7.63 (d, 1H, J = 9.2 Hz), 8.03 (d, 1H, J = 4.0 Hz), 8.22
(d, 1H, J = 7.2 Hz), 13.97 (s, 1H); 19F nmr (376 MHz, CDCl3): δ
–96.6 (td, 1F, J = 20.3, 5.6 Hz), -87.9 (ddd, 1F, J = 20.3, 7.8, 5.6
Hz), -81.6 (td, 1F, J = 20.3, 2.3 Hz). –66.3 (dddd, 1F, J = 20.3,
7.8, 4.0, 2.3 Hz). Anal. Calcd for C13H6F4N2O: C, 55.33; H,
2.14; N, 9.93. Found: C, 55.21; H, 2.04; N, 9.84.
“High-Tech Research Center” Project for Private Universities:
matching fund subsidy from the Japanese Ministry of Education,
Culture, Sports, Science and Technology. We thank Dr. T.
Tsukuda and Professor T. Tsubomura for the measurements of
X-ray crystallography data and for their helpful discussions.
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Compound 4 from 2 and Al(ClO4)3·9H2O. A mixture of 2
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cooled mixture of acetone and hexane (1/3) several times, giving
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1
(CH3CN): λmax (log ε/L mol-1 cm-1) 284 nm (4.37); H nmr (400
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MHz, CD3CN): δ 7.54 (td, 1H, J = 6.4, 1.2 Hz), 8.00 (d, 1H, J =
9.2 Hz), 8.04 (ddd, 1H, J = 9.2, 6.4, 1.2 Hz), 8.46 (s, 1H), 8.67
(dt, 1H, J = 6.4, 1.2 Hz); 19F nmr (376 MHz, CD3CN): δ -85.1
(m, 2F), -74.4 (tt, 1F, J = 20.7, 4.0 Hz), -63.6 (m, 2F). Anal.
Calcd for C13H6ClF5N2O4: C, 40.59; H, 1.57; N, 7.28. Found:
C, 40.78; H, 1.56; N, 7.30.
Crystal data for 4: C26H12Cl2F10N4O8,
M = 769.29,
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monoclinic, space group P 1 21/c 1, a = 5.2084(11), b =
º
27.495(6), c = 139.252(4) Å, α = 90 , β = 91.0712(9), γ = 90, V
= 2756.5(10) Å , T = 123.1 K, Z = 4, Dc = 1.854 g cm-3, λ =
0.7107 Å, 5905 reflections measured, 16800 unique (Rint
0.028). R1 = 0.055 and Rw = 0.139.
=
Acknowledgments. This research was supported by a Grant-
in-Aid for Scientific Research (No. 14550811) and partially by
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