978
HETEROCYCLES, Vol. 95, No. 2, 2017
To a mixture of indole-3-carboxaldehyde (0.16 g, 1.1 mmol) and 2’-hydroxyacetophenone (0.12 mL, 1.0
mmol) in EtOH (1.0 mL) was added piperidine (0.10 mL, 1.0 mmol). The solution was stirred for 5 h at
80 °C and the solvent was removed under reduced pressure. The residue was purified by silica gel
column chromatography [eluent: EtOAc / hexane (1:2)]. The solid was recrystallized from EtOH for
1
two times to give the compound 4 (30.4 mg, 12%) as a yellow needle crystal; H NMR(400 MHz,
CDCl
3
): δ = 13.20 (s, 1H, OH), 8.61 (br, 1H), 8.22 (d, J = 15.3 Hz, 1H), 8.03 (dd, J = 6.2 Hz, 4.1 Hz, 1H),
7
7
1
.98 (dd, J = 8.0 Hz, 1.6 Hz, 1H), 7.71 (d, J = 15.3 Hz, 1H), 7.66 (d, J = 2.7 Hz, 1H), 7.50-7.56 (m, 1H),
.47-7.49 (m, 2H), 7.47-7.45 (m, 1H), 7.03 (dd, J = 8.4 Hz, 0.95 Hz, 1H), 6.97 (ddd, J = 8.0 Hz, 7.1 Hz,
.2 Hz, 1H).
MEASUREMENTS
Absorption and fluorescence spectra were measured on a Shimadzu UV-1600 and on a Hitachi F-4500
fluorescence spectrometer, respectively. All solvents of spectral grade for spectroscopy were purchased
and used without further purification. All measurements were carried out at 298 K under Ar. The
concentration of solution for spectroscopy was adjusted so that the absorption maximum at the excitation
wavelength was less than 0.1 for each sample. Fluorescence quantum yields were determined relative to
anthracene ()
f
= 0.27 in ethanol). 1H NMR spectra in CDCl
with TMS as an internal standard were
3
measured on 270 MHz or 400 MHz NMR spectrometer.
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