A R T I C L E S
Liu et al.
Table 2. 1H and 13C Chemical Shifts for 3b and 4
3b (THF-d8)
δ ) 148.7, 148.5, 138.7, 137.3, 134.1, 133.4, 129.2, 128.5, 126.8, 126.4,
121.4, 121.3, -1.9. 29Si NMR (99.314 MHz, CDCl3): δ ) -13.4,
-43.3, -46.1. MS (MALDI, anthracene), m/z (%): 686.1 (56) (M+),
613.1 (38) (M+ - SiMe3), 433.1 (100) (M+ - SiMe3 - SiC12H8).
Reaction of 3b with Me3SiCl. An excess of Me3SiCl was added at
0 °C to a THF (150 mL) solution of 3b, obtained from a reaction
mixture of 4 (3.00 g, 12.0 mmol) and K (7.00 g, 179 mmol) in THF
(100 mL). The volatiles were removed under reduced pressure, and
the residue was extracted with toluene (400 mL). The toluene solution
was washed with distilled water, dried with MgSO4, and filtered. Upon
purifying by flash chromatography on silica gel (elution with hexane),
white crystals of bis(trimethylsilyl) derivative 5 were obtained (3.84
g, 98.6%).
4 (THF-d8)
1H (ppm)
8.42 (br, 2H), 7.83 (br, 2H),
6.55 (br, 2H), 6.36 (br, 2H)
7.87 (d, 2H), 7.66 (d, 2H),
7.49 (t, 2H), 7.31 (t, 2H)
146.8 (C), 133.5 (CH),
133.2 (CH), 131.4 (C),
129.4 (CH), 122.1 (CH)
13C (ppm) 167.9 (C), 134.4 (CH),
131.6 (C), 121.1 (CH),
115.6 (CH), 110.5 (CH)
Table 3. 29Si Chemical Shifts for Various Silole Dichlorides, Silole
Anions, and Silole Dianions
Reaction of 3b with EtBr. A THF (100 mL) solution of 3b, obtained
from a reaction mixture of 4 (1.40 g, 5.58 mmol) and K (2.00 g, 51.2
mmol), was cannulated into a flask containing an excess of EtBr at
room temperature. The volatiles were removed under reduced pressure,
and the residue was extracted with toluene (400 mL) and filtered. White
crystals of 1,1-diethyl-1-silafluorene 11 were obtained (1.08 g, 81.4%)
after recrystallization from hexane. Selected data for 11, 1H NMR
(300.133 MHz, C6D6): δ ) 7.71 (d, 2H), 7.52 (d, 2H), 7.27 (t, 2H),
7.16 (t, 2H), 0.91 (q, 6H, CH3), 0.82 (t, 4H, CH2). 13C NMR (75.403
MHz, CDCl3): δ ) 148.5, 137.3, 133.2, 130.1, 127.1, 120.8, 7.5, 3.8.
29Si NMR (99.314 MHz, CDCl3): δ ) -1.1. MS (EI), m/z (%): 238.5
(77) (M+), 209.4 (89) (M+ - Et), 181.3 (100) (M+ - 2Et). High-
resolution MS (EI), calcd for [C16H18Si] 238.1178, found 238.1168.
Reaction of 3b with MeI. A THF (100 mL) solution of 3b, obtained
from a reaction of 4 (2.00 g, 7.97 mmol) and K (2.00 g, 51.2 mmol),
was cannulated into a flask containing an excess of MeI at room
temperature. The volatiles were removed under reduced pressure, and
the residue was extracted with toluene (400 mL) and filtered. After
preparative GPC (toluene elution) separation, three solid products were
isolated in a ratio: 1,1-dimethyl-1-silafluorene 12 (0.71 g, 42%), dimer
13 (0.28 g, 18%), and disiloxane 14 (0.15 g, 9.3%). Selected data for
1
13, H NMR (300.133 MHz, C6D6): δ ) 7.67 (d, 4H), 7.38 (d, 4H),
7.33 (t, 4H), 7.15 (t, 4H), 0.364 (s, 3H). 13C NMR (125.710 MHz,
CDCl3): δ ) 147.0, 135.8, 132.5, 130.8, 127.6, 120.5, -2.3. 29Si NMR
(99.314 MHz, CDCl3): δ ) -2.1. MS (EI), m/z (%): 390.1 (53) (M+),
375.1 (76) (M+ - Me). High-resolution MS (EI), calcd for [C26H22-
Si2] 390.1259, found 390.1252. Selected data for 14:1H NMR (300.133
MHz, C6D6): δ ) 7.78 (d, 4H), 7.67 (d, 4H), 7.45 (t, 4H), 7.29 (t,
4H), 0.587 (s, 3H); 13C NMR (125.710 MHz, CDCl3): δ ) 147.9,
136.4, 133.5, 131.9, 128.6, 121.4, -2.9; 29Si NMR (99.314 MHz,
CDCl3): δ ) -4.8,_1.1; MS (EI), m/z (%): 406.1 (74) (M+), 391.1
(100) (M+ - Me); High-resolution MS (EI), calcd for [C26H22Si2O]
406.1209, found 406.1206.
Reaction of 3b with Benzaldehyde. A THF (100 mL) solution of
3b, obtained from a reaction mixture of 4 (2.00 g, 7.97 mmol) and K
(2.00 g, 51.2 mmol), was cannulated into a Schlenk flask containing a
THF (100 mL) solution of benzaldehyde (1.69 g, 15.9 mmol) at -78
°C. The reaction mixture was stirred at -78 °C for 2 h and then was
stirred at room temperature overnight. Excess methanol (100 mL) was
added to quench the reaction. The solution was neutralized with dilute
aqueous HCl. The volatiles were removed under reduced pressure, and
the residue was extracted with toluene (200 mL). The resulting solution
was washed with distilled water, dried with MgSO4, and filtered. After
preparative GPC column (toluene elution) separation, two major
products were obtained: 1,2-diphenyl-1,2-ethanediol (1.65 g, 96.8%)
and oligosilafluorene (15) (0.81 g, 55.9%). The structure of the 1,2-
diol was confirmed by 1H NMR24 and X-ray crystallography. The ratio
of two diastereomers of 1,2-diol, meso:[R,R]/[S,S], is 5:4 based on 1H
NMR data. Selected data for 15, 1H NMR (300.133 MHz, CDCl3): δ
) 7.54-6.50 (br). 29Si NMR (99.314 MHz, CDCl3): δ ) -12.1 (br).
stirring for 3h at room temperature, the reaction mixture turned red.
Some reaction mixture was cannulated out and trapped with Me3SiCl
to give a mixture of silanes, 5, 9, and 10, which were separated by
preparative GPC (toluene elution) and recrystallized from toluene/
hexane solutions. The remaining solution was then heated to 67 °C
and stirred for 12 h. The color of the solution changed to a dark red.
After removal of THF by vacuum, the residue was extracted with
sodium-dried DME (150 mL), hexane (20 mL), and 18-crown-6 (7.20
g, 27.2 mmol). Red crystals of 3b were obtained from the extracted
solution after cooling at -20 °C. Selected data for 3b, 1H NMR
(300.133 MHz, THF-d8): δ ) 8.42 (br, 2H, CH), 7.82 (br, 2H, CH),
6.54 (br, 2H, CH), 6.35 (br, 2H, CH). 13C NMR (75.403 MHz, THF-
d8): δ )167.9 (C), 134.4 (CH), 131.6 (C), 121.1 (CH), 115.6 (CH),
110.5 (CH). 29Si NMR (99.314 MHz, THF-d8): δ ) 29.0. Selected
1
data for 5, H NMR (300.133 MHz, CDCl3): δ ) 7.91 (d, 2H), 7.63
(d, 2H), 7.41 (t, 2H), 7.25 (t, 2H), 0.107 (s, 18H). 13C NMR (75.403
MHz, CDCl3): δ ) 148.7, 139.5, 133.3, 128.4, 126.5, 121.2, -1.0.
29Si NMR (99.314 MHz, CDCl3): δ ) -15.2, -42.2. MS (EI), m/z
(%): 326.1 (65) (M+), 253.1 (85) (M+ - TMS). High-resolution MS
(EI), calcd for [C16H18Si] 326.1342, found 326.1335. Selected data for
1
9, H NMR (300.133 MHz, CDCl3): δ ) 7.92 (d, 4H), 7.77 (d, 4H),
7.48 (t, 4H), 7.33 (t, 4H), -0.414 (s, 18H). 13C NMR (75.403 MHz,
CDCl3): δ ) 148.8, 139.2, 133.8, 129.0, 126.8, 121.5, -1.8. 29Si NMR
(99.314 MHz, CDCl3): δ ) -13.3, -44.1. MS (EI), m/z (%): 506.2
(100) (M+), 433.2 (95) (M+ - SiMe3), 253.1 (90) (M+/2). Selected
data for 10, 1H NMR (300.133 MHz, CDCl3): δ ) 7.92 (d, 2H), 7.69
(d, 2H), 7.61 (d, 4H), 7.46 (t, 2H), 7.30 (t, 4H), 7.27 (d, 2H), 7.21 (d,
4H), 7.00 (t, 4H), -0.490 (s, 18H). 13C NMR (125.710 MHz, CDCl3):
(24) Pouchert, C. J.; Behnke, J. The Aldrich Library of 13C and 1H FT NMR
Spectra; Aldrich Chemical Co., Inc.: Milwaukee, WI, 1993; Vol. 2, pp
336C, 337A.
9
56 J. AM. CHEM. SOC. VOL. 124, NO. 1, 2002