3
in water (10 mL) was added dropwise. After stirring for 1 h, 8 mL
of HBF4 (50 wt% water solution) was added. The slurry
precipitate formed was decanted and dissolved in acetone (5 mL).
After pouring into methyl tert-butyl ether (100 mL), the white
precipitate was filtered and purified by additional precipitation
from nitromethane with methyl tert-butyl ether, yielding 6
(10.1 g, 82%) as white crystals. The product was used in subse-
quent reactions without characterization.
3J ¼ 6.26 Hz), 6.37 (2H, d, J ¼ 8.99 Hz), 7.30–7.60 (30H, m),
3
4
7.68–7.74 (3H, m), 8.20 (1H, dd, J ¼ 8.99, J ¼ 2.34 Hz) 8.58
4
(1H, d, J ¼ 2.34 Hz). Elemental analysis (C, H, N): (calc. for
C52H45BrN4O4Si2: C, 67.45, H, 4.90, N, 6.05. Found: C, 67.94,
H, 5.03, N, 5.77%). MS (ESI+) m/z: 927.2 (M+, requires 927.0).
4-((2-Chloro-4-tritylphenyl)diazenyl)-N,N-bis(2-(trityloxy)
ethyl)aniline (A-4). Prepared according to general procedure A
described above. Purification by column chromatography over
silica gel using DCM/petroleum ether (2 : 1) as eluent gave A-4 as
a yellow powder (0.46 g, 49% over 2 steps). 1H NMR (d, CDCl3,
300 MHz): 3.26 (4H, t, 3J ¼ 5.84 Hz), 3.60 (4H, t, 3J ¼ 5.84 Hz),
6.51 (2H, d, 3J ¼ 9.23 Hz), 7.07 (1H, dd, 3J ¼ 8.66 Hz, 4J ¼ 2.07
4-((4-Nitrophenyl)diazenyl)-N,N-bis(2-(trityloxy)ethyl)aniline
(A-1)
General procedure A. To a solution of N-phenyldiethanol-
amine (1.00 g, 5.0 mmol) in DMF (5 mL) at 0 ꢀC diazonium salt
3a (1.56 g, 6.6 mmol) in DMF (2 mL) was added dropwise. After
2 h of stirring the mixture was poured into water (50 mL) and the
resulting red precipitate was filtered, washed with additional
amount of water, dried in air and crystallized from isopropanol.
Without further purification the technical product 7 (1.44 g,
4.3 mmol) was dissolved in dry pyridine (5 mL) after which
triethylamine (2.38 mL, 17.0 mmol) and tritylchloride (4.84 g,
17.0 mmol) were added. The mixture was stirred at 60 ꢀC for 2 h
and then poured into isopropanol (50 mL). The resulting red
precipitate was filtered, washed with methanol (3 ꢁ 15 mL) and
dried in air. Purification was accomplished by column chroma-
tography over silica gel using DCM/petroleum ether (3 : 1) as
eluent. The resulting red substance was dissolved in DCM (5 mL)
and ethanol (50 mL) was added. After removal of DCM under
reduced pressure and filtration of the formed precipitate, A-1 was
obtained as a red powder (3.04 g, 67% over 2 steps). 1H NMR (d,
4
Hz), 7.10–7.32 (45H, m), 7.36 (1H, d, J ¼ 2.07 Hz), 7.70 (2H,
d, 3J ¼ 9.23 Hz). Elemental analysis (C, H, N): (calc. for
C73H61N3O2: C, 83.76, H, 5.78, N, 4.01. Found: C, 83.23, H,
5.72, N, 3.93%). MS (ESI+) m/z: 1046.5 (M+, requires 1046.7).
4-((2-Chloro-4-tritylphenyl)diazenyl)-N,N-bis(2-(triphenylsily-
loxy)ethyl)aniline (A-5). Prepared according to general procedure
A described above. Purification by column chromatography over
silica gel using DCM/petroleum ether (2 : 1) as eluent gave A-5 as
a yellow powder (0.66 g, 39% over 2 steps). 1H NMR (d, CDCl3,
300 MHz): 3.43 (4H, t, 3J ¼ 5.84 Hz), 3.83 (4H, t, 3J ¼ 5.84 Hz),
6.24 (2H, d, 3J ¼ 9.04 Hz), 7.07 (1H, dd, 3J ¼ 8.47 Hz, 4J ¼ 2.26
3
Hz), 7.12–7.39 (34H, m), 7.45 (1H, d, J ¼ 8.47 Hz), 7.49–7.53
3
(12H, m), 7.57 (2H, d, J ¼ 9.04 Hz). Elemental analysis (C, H,
N): (calc. for C71H61N3O2Si2: C, 79.04, H, 5.61, N, 3.89. Found:
C, 78.89, H, 5.58, N, 3.78%). MS (ESI+) m/z: 1078.5 (M+,
requires 1078.8).
3
3
CDCl3, 400 MHz): 3.31 (4H, t, J ¼ 5.50 Hz), 3.60 (4H, t, J ¼
3
5.63 Hz), 6.56 (2H, d, J ¼ 9.27 Hz), 7.14–7.30 (30H, m), 7.73
(2H, d, 3J ¼ 9.14 Hz), 7.86 (2H, d, 3J ¼ 9.06 Hz), 8.26 (2H, d, 3J ¼
9.11 Hz). Elemental analysis (C, H, N): (calc. for C54H46N4O4: C,
82.84, H, 5.92, N, 7.16. Found: C, 79.39, H, 5.59, N, 6.83%).
2-(4-(Bis(2-(trityloxy)ethyl)amino)benzylidene)-1H-indene-
1,3(2H)-dione (I-1). Aldehyde 1028 (2.0 g, 9.6 mmol) was dis-
solved in ethanol (120 mL) after which indane-1,3-dione29 and 3
drops of piperidine were added. The dark orange solution was
stirred at room temperature for 3 h and refluxed for an additional
1 h. After cooling, the resulting precipitate was filtered and
recrystallized from isopropanol, yielding 11 as orange crystals
(2.1 g, 65%). Compound 11 (0.74 g, 2.2 mmol) was then dissolved
in dry pyridine (5 mL) after which triethylamine (0.85 mL,
5.0 mmol) and tritylchloride (1.4 g, 5.0 mmol) were added. The
4-((4-Nitrophenyl)diazenyl)-N,N-bis(2-(triphenylsilyloxy)ethyl)
aniline (A-2)
General procedure B. Compound 7 (0.52 g, 1.6 mmol), obtained
following the procedure described above, was dissolved in dry
pyridine (3 mL) after which triethylamine (0.5 mL, 3.69 mmol) and
triphenylsilyl chloride (1.16 g, 3.69 mmol) were added. After stir-
ring at room temperature for 2 h, pyridine was removed under
reduced pressure and the resulting wet precipitate was washed with
ethanol (50 mL). Purification by column chromatography over
silica gel using DCM/petroleum ether (3 : 1) as eluent gave A-2 as
an orange powder (0.47 g, 21% over 2 steps). 1H NMR (d, CDCl3,
400 MHz): 3.53 (4H, t, 3J ¼ 5.84 Hz), 3.92 (4H, t, 3J ¼ 5.84 Hz),
6.35 (2H, d, 3J ¼ 9.04 Hz), 7.30–7.60 (30H, m), 7.68–7.76 (3H, m),
8.19 (1H, dd, 3J ¼ 8.84 Hz, 4J ¼ 2.24 Hz), 8.58 (1H, d, 4J ¼ 2.24
Hz). Elemental analysis (C, H, N): (calc. for C52H46N4O4Si2: C,
73.73, H, 5.47, N, 6.61. Found: C, 73.81, H, 5.48, N, 6.59%). MS
(ESI+) m/z: 847.6 (M+, requires 847.1).
ꢀ
mixture was stirred at 60 C for 2 h and then poured into iso-
propanol (50 mL). The resulting yellow precipitate was filtered,
washed with methanol (3 ꢁ 15 mL) and dried in air. Purification
by column chromatography over silica gel using DCM/petro-
leum ether (2 : 1) as eluent gave I-1 as a yellow powder (1.60 g,
88%). 1H NMR (d, CDCl3, 300 MHz): 3.40 (4H, t, 3J ¼ 6.03 Hz),
3.72 (4H, t, 3J ¼ 6.03 Hz), 6.63 (2H, d, 3J ¼ 9.04 Hz), 7.16–7.37
(m, 30H), 7.74 (m, 2H), 7.78 (s, 1H) 7.95 (m, 2H), 8.44 (2H, d,
3J ¼ 8.85 Hz). Elemental analysis (C, H, N): (calc. for
C58H47NO4: C, 84.75, H, 5.76, N, 1.70. Found: C, 83.82, H, 5.68,
N, 1.45%). MS (ESI+) m/z: 822.6 (M+, requires 822.0).
4-((2-Bromo-4-nitrophenyl)diazenyl)-N,N-bis(2-(triphenylsily-
loxy)ethyl)aniline (A-3). Prepared according to general procedure
B described above. Purification by column chromatography over
silica gel using DCM/petroleum ether (3 : 1) as eluent gave A-3 as
a dark red powder (0.97 g, 42% over 2 steps). 1H NMR
2-(4-(Bis(2-(triphenylsilyloxy)ethyl)amino)benzylidene)-1H-
indene-1,3(2H)-dione (I-2). Prepared from compound 11
according to general procedure B described above. Purification
by column chromatography over silica gel using DCM/petro-
leum ether (2 : 1) as eluent gave I-2 as yellow powder (0.84 g,
76%). 1H NMR (d, CDCl3, 300 MHz): 3.46 (4H, t, 3J ¼ 6.03 Hz),
3
(d, CDCl3, 400 MHz): 3.53 (4H, t, J ¼ 6.26 Hz), 3.92 (4H, t,
11270 | J. Mater. Chem., 2012, 22, 11268–11276
This journal is ª The Royal Society of Chemistry 2012