Nanometer-Sized Tripod-Shaped Oligophenylenes
gave 8a (8.5 g, 79%) as a colorless liquid. 1H NMR (CDCl3,
300 MHz): 1.83-1.86 (m, 6H), 4.88-4.95 (m, 6H), 5.69-5.84
combined organic fractions were dried over MgSO4. The solvent
was removed in a vacuum to give a pale yellow liquid. Flash
chromatography (silica gel/hexane) gave 11 as a colorless liquid
(6.85 g, 64% yield). 1H NMR (CDCl3, 300 MHz): 1.82-1.86
(m, 6H), 4.88-4.96 (m, 6H), 5.70-5.84 (m, 3H), 7.24 (d, 2H, J
) 8.4 Hz), 7.72 (d, 2H, J ) 8.4 Hz). 13C NMR (CDCl3, 75
MHz): 136.8, 135.8, 134.6, 133.4, 114.6, 96.5, 19.3. MS (EI,
m/z): calcd for C15H39ISi (M+) 354.0, found 354.0. Anal.
Calcd: C, 50.85; H, 5.41. Found: C, 50.83; H, 5.37.
(m, 3H), 7.37 (d, 2H, J ) 8.4 Hz), 7.70 (d, 2H, J ) 8.4 Hz). 13
C
NMR (CDCl3, 75 MHz): 135.8, 134.0, 133.4, 130.9, 124.3, 114.6,
19.4. MS (EI, m/z): calcd for C15H39BrSi (M+) 306.0, found
306.0. Anal. Calcd: C, 58.63; H, 6.23. Found: C, 58.55; H, 6.17.
4-Tr ia llylp h en ylbor on ic Acid (8b). To a solution of 8a
(4.50 g, 14.61 mmol) in ether (50 mL) at -78 °C was added
n-BuLi in hexane (2.45 N, 6.14 mL, 14.61 mmol). After the
addition, the solution was stirred for 2 h at room temperature,
transferred into an additional funnel under N2, and added
dropwise into a solution of triisopropylboronate (5.50 g, 29.2
mmol) in ether (200 mL) at -78 °C. After the addition, the
white suspension was stirred overnight at room temperature
and hydrolyzed with aqueous HCl (2 M, 45 mL). The organic
layer was separated, and the aqueous solution was extracted
twice with ether. The combined organic fractions were dried
over anhydrous MgSO4. Flash chromatography (silica gel,
hexane/ether 1:1) gave 8b as a white solid (2.66 g, 67% yield).
Mp ) 59-62 °C. 1H NMR (CDCl3, 300 MHz): 1.93 (d, 6H, J )
7.8 Hz), 4.91-4.99 (m, 6H), 5.75-5.90 (m, 3H), 7.67 (d, 2H, J
) 7.8 Hz), 8.21 (d, 2H, J ) 7.8 Hz). 13C NMR (CDCl3, 75
MHz): 140.9, 134.6, 133.8, 133.6, 114.5, 19.4.
6-Mer Bor on a te (9). A flask was charged with 6b (97.1
mg, 0.10 mmol), 8b (28.0 mg, dehydrated, 0.11 mmol), and Pd-
(PPh3)4 (1.1 mg, 0.95 µmol). A degassed solution of toluene (0.6
mL) and aqueous Na2CO3 (1 M, 0.30 mL) was added. The
mixture was stirred at 80 °C overnight. The mixture was
diluted with toluene, washed with water, and dried over
anhydrous MgSO4. Flash chromatography (hexane/AcOEt 40:
1) gave 9 as a colorless viscous liquid (105 mg, 98%). 1H NMR
(CDCl3, 300 MHz): 0.80-0.84 (m, 9H), 0.87-0.92 (m, 3H),
1.19-1.33 (m, 24H), 1.37 (s, 12H), 1.48-1.56 (m, 8H), 1.93 (d,
6H, J ) 8.1 Hz), 2.56-2.66 (m, 6H), 2.88 (t, 2H, J ) 8.1 Hz),
4.91-5.00 (m, 6H), 5.79-5.90 (m, 3H), 7.09 (s, 1H), 7.17 (s,
1H), 7.19 (s, 1H), 7.38 (d, 2H, J ) 8.4 Hz), 7.41 (d, 2H, J ) 8.1
Hz), 7.47 (d, 2H, J ) 7.8 Hz), 7.58 (d, 2H, J ) 8.4 Hz), 7.70 (d,
2H, J ) 7.8 Hz), 7.70 (s, 1H), 7.73 (d, 2H, J ) 8.1 Hz), 7.78 (s,
4H). 13C NMR (CDCl3, 75 MHz): 147.5, 143.6, 142.9, 141.3,
141.0, 140.6, 140.4, 139.8, 139.7, 138.9, 137.6, 137.5, 136.8,
133.9, 133.2, 130.9, 130.8, 129.8, 129.6, 128.7, 127.4, 126.6,
126.5, 114.3, 83.3, 35.5, 33.5, 32.64, 32.59, 31.8, 31.7, 31.5,
31.45, 31.38, 31.3, 29.7, 29.5, 29.3, 29.24, 29.20, 29.1, 24.9, 22.7,
Op tim ized Rea ction Con d ition s for Su zu k i Cou p lin g
of 6a a n d 11 to 12. A flask was charged with 11 (35.4 mg,
0.10 mmol), 6a (48.6 mg, 0.05 mmol), Pd(PPh3)4 (1.7 mg, 0.0015
mmol), KOH (28 mg, 0.50 mmol), and n-Bu4NBr (2.8 mg,
0.0087 mmol). A degassed solution of toluene (0.5 mL) and
water (0.2 mL) was then added. The mixture was stirred at
90 °C overnight. The organic layer was separated, extracted
with toluene, washed with water, and dried over anhydrous
MgSO4. Flash chromatography (silica gel, hexane/EtOAc 40:
1
1) gave 12 as a white solid (52 mg, 88%). Mp ) 86-88 °C. H
NMR (CDCl3, 300 MHz): 0.85 (t, 12H, J ) 6.4 Hz), 1.14-1.31
(m, 24H), 1.46-1.61 (m, 8H), 1.96 (d, 12H, J ) 8.4 Hz), 2.60-
2.70 (m, 8H), 4.94-5.02 (m, 12H), 5.80-5.96 (m, 6H), 7.19 (s,
2H), 7.22 (s, 2H), 7.40 (d, 4H, J ) 8.1 Hz), 7.50 (d, 4H, J ) 8.4
Hz), 7.61 (d, 4H, J ) 8.4 Hz), 7.76 (d, 4H, J ) 8.1 Hz), 7.81 (s,
4H). 13C NMR (CDCl3, 75 MHz): 143.0, 141.1, 140.7, 140.4,
139.8, 139.0, 137.6, 134.0, 133.3, 131.0, 130.9, 129.8, 128.7,
127.4, 126.6, 114.3, 32.7, 31.6, 31.54, 31.46, 29.3, 29.2, 22.5,
19.7, 14.0. Calcd for C84H106Si2 (M+) 1170.8, found 1171.0. Anal.
Calcd: C, 86.09; H, 9.12. Found: C, 85.64; H, 9.03.
Tr ip od Com p ou n d (1a ). A flask was charged with 10 (31.8
mg, 0.04 mmol), 9 (132.8 mg, 0.124 mmol), Pd(PPh3)4 (2.0 mg,
0.0018 mmol), KOH (33.6 mg, 0.60 mmol), and n-Bu4NBr (3.3
mg, 0.010 mmol). A degassed solution of toluene (0.5 mL) and
water (0.2 mL) was added. The mixture was stirred at 85 °C
overnight. The mixture was diluted with toluene, washed with
water, and dried over MgSO4. Preparative TLC (silica gel,
repeatedly eluted with hexane/toluene 3:1) gave 1a as a
colorless solid (101 mg, 78%). 1H NMR (CDCl3, 300 MHz):
0.80-0.92 (m, 36H), 1.19-1.38 (m, 72H), 1.50-1.68 (m, 24H),
1.99 (d, 18H, J ) 8.1 Hz), 2.56-2.80 (m, 24H), 4.95-5.08 (m,
18H), 5.84-6.01 (m, 9H), 7.24-7.94 (m, 76H). 13C NMR
(CDCl3, 75 MHz): 143.8, 143.2, 141.3, 140.8, 140.7, 140.5,
139.9, 139.1, 138.1, 137.9, 137.6, 136.2, 134.0, 133.5, 132.0,
131.3, 131.06, 130.99, 130.95, 129.9, 129.1, 128.8, 127.5, 126.6,
124.9, 114.4, 32.8, 31.59, 31.55, 31.46, 31.38, 29.2, 22.5, 19.9,
14.0. MALDI-TOF MS (dithranol as matrix) (m/z): calcd for
22.52, 22.49, 19.7, 14.1, 14.0. MS (EI, m/z): calcd for C75H99
-
BO2Si (M+) 1070.8, found 1070.6. Anal. Calcd: C, 84.07; H,
9.31. Found: C, 83.76; H, 9.39.
C
245H287BrO3Si4 [M + Matrix - Br]+ 3389, found 3388.
Attem p ted Syn th esis of 1b a n d 1c. A Schlenk flask was
(4-Br om op h en yl)-tr is(4-iod op h en yl)sila n e (10). To a
suspension of 1,4-diiodobenzene (1.32 g, 4.0 mmol) in anhy-
drous ether (25 mL) at -78 °C was added n-BuLi in hexane
(2.45 N, 1.27 mL, 3.1 mmol). The solution was stirred for at
-78 °C for 1 h and treated with 7 (0.291 g, 1.0 mmol). The
white suspension was stirred overnight at room temperature
and treated with water (10 mL). The organic layer was
separated, and the aqueous solution was extracted twice with
ether. The combined organic fractions were dried over anhy-
drous MgSO4. The solvent was removed in a vacuum to give a
crystalline white solid. Flash chromatography (silica gel,
hexane/tolulene 20:1) gave 10 as a white solid (230 mg, 32%).
charged with 1a (50 mg, 0.0154 mmol), THF (0.5 mL), HSiCl3-
(56 mg, 0.554 mmol), and a drop of H2PtCl6 in i-PrOH (0.1
M). The reaction mixture was stirred at room temperature
1
overnight. The reaction was monitored by H NMR until the
disappearance of the allyl groups. The solvents were removed
under high vacuum to give an oil. Dry THF (1.0 mL) was added
to dissolve the residue under Ar. Allylmagnesium bromide (1.0
M in ether, 0.28 mL, 0.28 mmol) was added dropwise. The
mixture was refluxed overnight, hydrolyzed with aqueous HCl
(1 M), diluted with toluene, washed with water, and dried over
MgSO4. Preparative TLC (silica gel, repeatedly eluted with
hexane/toluene 3:1) gave a white solid (28 mg). 13C NMR
(CDCl3, 75 MHz): showed the absence of the C-Br signal at
124.9 ppm.
1
Mp ) 298-301 °C. H NMR (CDCl3, 300 MHz): 7.19 (d, 6H,
J ) 8.7 Hz), 7.33 (d, 2H, J ) 8.1 Hz), 7.53 (d, 2H, J ) 8.1 Hz),
7.74 (d, 6H, J ) 8.7 Hz). 13C NMR (CDCl3, 75 MHz): 137.8,
137.6, 137.5, 132.1, 131.5, 128.3, 125.5, 97.7. MS (EI, m/z):
calcd for C24H16BrI3Si (M+) 791.7, found 791.6. Anal. Calcd:
C, 36.35; H, 2.03. Found: C, 36.29; H, 1.86.
Ack n ow led gm en t. We thank the financial support
of this work by the Texas Advanced Research Program
under Project 003652-0365-1999 and the Robert A.
Welch Foundation.
4-Iod op h en yltr ia llylsila n e (11). To a suspension of 1,4-
diiodobenzene (9.90 g, 30.0 mmol) in ether (200 mL) at -78
°C was added n-BuLi in hexane (2.45 N, 12.3 mL, 30.0 mmol).
After the addition, the solution was stirred for 1 h and treated
with chlorotriallylsilane (5.90 g, 30.0 mmol). The white
suspension was stirred overnight at room temperature and
quenched with H2O (30 mL). The organic layer was separated,
and the aqueous solution was extracted twice with ether. The
Su p p or tin g In for m a tion Ava ila ble: NMR spectra of 8b,
1a , and the products of hydrosilylation and Grignard reaction
of 1a ; MALDI-TOF MS and GPC of 1a . This material is
J O0257750
J . Org. Chem, Vol. 67, No. 15, 2002 5283