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1H-NMR (400 MHz, CDCl3) d 11.48 (1H, s), 10.25 (2H, s), 7.99
(2H, s), 1.36 (9H, s).
Acknowledgements
13C-NMR (100 MHz, CDCl3) d 192.44, 161.70, 143.14, 134.67,
122.67, 34.32, 31.10.
The work was supported by a grant from the Research
Committee of Hong Kong Baptist University (FRG2/11-12/121).
(E)-3-(((2-Aminophenyl)imino)methyl)-5-(tert-butyl)-2-hydro-
xybenzaldehyde (3). The mixture 2 (0.31 g, 1.5 mmol) and 1,2-
diaminobenzene (0.17 g, 1.6 mmol) in absolute EtOH (20 mL)
was heated to 50 uC for 6 h. After cooling, the solid was filtered
and washed with small portions of EtOH to give a yellow solid
3 (0.31 g, yield: 70%); m.p.: 264–265 uC.
Notes and references
1 J. Lakowicz, Principles of Fluorescence Spectroscopy, 2nd edn,
Kluwer Academic/Plenum Publishers, New York, 1999, pp.
531–572.
1H-NMR (400 MHz, CDCl3) d 13.56 (1H, s), 8.63 (1H, s), 7.42
(1H, d, J = 2.3 Hz), 7.34 (1H, d, J = 2.3 Hz), 7.2827.24 (m, 1H),
7.06 (1H, dd, J = 7.7 Hz, J = 1.4 Hz), 6.97 (1H, d, J = 8.1 Hz), 6.79
(1H, dt, J = 7.6 Hz, J = 1.1 Hz), 6.32 (1H, t, J = 5.6 Hz), 4.46 (2H,
d, J = 5.8 Hz), 1.33 (9H, s).
2 J.-P. Desvergne and A. W. Czarnik, Fluorescent
Chemosensors for Ion and Molecule Recognition, Kluwer
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3 R. P. Haugland, Molecular Probes Handbook, A Guide to
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Molecular Probes Inc., Eugene, OR, 2005, pp. 935–947.
4 B. Valeur, Molecular Fluorescence: Principles and
Applications, Wiley-VCH, Weinheim, Germany, 2002.
5 R. P. Haugland and M. T. Z. Spence, Handbook of
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13C-NMR (100 MHz, CDCl3) d 162.17, 157.25, 143.47, 141.83,
136.18, 130.90, 128.23, 128.06, 124.98, 119.16, 118.03, 117.46,
111.77, 47.28, 34.07, 31.44.
3-(1H-Benzo[d]imidazol-2-yl)-5-(tert-butyl)-2-hydroxybenzal-
dehyde (4). To a suspension of 3 (0.16 g, 0.5 mmol) in DCM (20
mL) was added DDQ (0.24 g, 1.0 mmol) and the reaction
mixture was stirred at room temperature for 2 h. After removal
of the solvent, the residue was purified by column chromato-
graphy on silica gel (PE : EA = 20 : 1) to afford 4 as a yellow
solid (90 mg, 56% yield); m.p.: 249–251 uC.
1H-NMR (400 MHz, MeOD) d 10.42 (1H, s), 8.41 (1H, d, J =
2.5 Hz), 7.90 (1H, d, J = 2.5 Hz), 7.65–7.63 (2H, m), 7.31–7.28
(2H, m), 1.42 (9H, s).
13C-NMR (100 MHz, MeOD) d 193.54, 160.38, 151.79, 143.61,
138.78, 131.79, 129.16, 124.28, 116.22, 115.87, 35.41, 31.70.
ESI-MS: m/z calcd for C18H18N2O2 [M + H+] 295.14, found,
295.3.
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8-(1H-Benzo[d]imidazol-2-yl)-6-(tert-butyl)-19,39,39-trimethyl-
spiro[chromene-2,29-indoline] (1). A mixture of 4 (40 mg, 0.14
mmol) and 1,2,3,3-tetramethyl-3H-indol-1-ium iodide (42 mg,
0.14 mmol) in absolute EtOH (10 mL) was heated to reflux
under N2 atmosphere. A solution of morpholine (24 mg, 0.28
mmol) in absolute EtOH (10 mL) was added in a dropwise
manner. After addition, the reaction mixture was refluxed for 2
h. Then the solvent was evaporated under reduced pressure
and the residue was purified by column chromatography on
silica gel (PE : EA = 50 : 1) to afford 1 as a pink solid (19 mg,
30% yield).
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1H-NMR (400 MHz, CDCl3) d 9.79 (1H, s), 8.41 (1H, d, J = 2.4
Hz), 7.74 (1H, d, J = 8.1 Hz), 7.39 (1H, dt, J = 7.7 Hz, J = 1.3 Hz),
7.25 (1H, dd, J = 7.3 Hz, J = 0.8 Hz), 7.21–7.16 (2H, m), 7.12 (dt,
J = 7.4 Hz, J = 0.9 Hz), 7.01 (1H, d, J = 10.4 Hz), 6.69 (2H, m),
5.90 (1H, d, J = 10.4 Hz), 2.77 (3H, s), 1.39 (9H, s), 1.34 (3H, s),
1.30 (3H, s).
13C-NMR (100 MHz, CDCl3) d 149.62, 149.51, 148.18, 143.96,
142.58, 136.79, 133.46, 131.09, 128.27, 126.49, 125.97, 122.45,
122.18, 122.03, 120.32, 119.08, 118.97, 117.93, 114.82, 110.94,
108.28, 107.40, 51.90, 34.42, 31.48, 29.55, 24.64, 19.69.
HRMS (MALDI-TOF): m/z calcd for C39H39N5O4 [M + H+]
450.2540, found, 450.2561.
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RSC Adv., 2013, 3, 15762–15768 | 15767