MOCH CH OM), 6.85 (2H, s, ArH) and 7.37 (2H, s, ArH);
chloric acid, slowly warming to room temp., and stirring for a
further 6 h. Water was added and the aqueous solution
extracted with diethyl ether (2×50 cm3). The organic phase
was washed with water and dried with sodium sulfate. The
solvent was removed under reduced pressure to give a yellowish
waxy solid. Purification was by column chromatography using
dichloromethane as the first eluent to remove a by-product
and then 30% diethyl ether in dichloromethane After the
solvent was removed the product 18 was obtained as a pale
coloured solid (2.5g, 92%) (Found: C, 67.30; H, 9.81.
C H B O requires C, 67.30; H, 10.10%); d (CDCl ) 0.84
2
2
m/z 414 (M+, 100%), 384 (8) and 344 (15).
2,2∞,5,5∞-Tetrahydroxybiphenyl 15
A solution of boron tribromide (13.20 g, 52.8 mmol) in
dichloromethane (40 cm3) was added to a cold (−78 °C) solu-
tion of 2,2∞,5,5∞-tetramethoxybiphenyl 12 (3.60 g, 13.1 mmol) in
dichloromethane (120 cm3). The reaction mixture was stirred
at −78 °C for 5 h and then allowed warm to room temp. The
mixture was poured onto water, the organic layer separated
and the aqueous layer extracted with diethyl ether (3×50 cm3).
Removal of the solvent and drying gave product 15 as a
greyish solid (2.0 g, 70%), mp 231–232 °C (Found: C, 65.80;
36 60 2
8
H
3
(6H, t, J 6.7, MCH ), 0.90 (6H, t, J 6.6, MCH ), 0.95–1.85
3
3
(32H, m, MCH M), 3.90 (4H, t, J 6.5, MOCH M), 4.02 (4H,
2
2
t, J 6.6, MOCH M), 6.34 [4H, br s, MB(OH) ], 6.91 (2H, s,
ArH) and 7.43 (2H, s, ArH, ortho to boron); m/z 638, 610, 570
and 554.
H, 4.60. C H O requires C, 66.05; H, 4.62%);
d
2
2
12 10
4
H
([2H ]acetone) 6.72 (2H, dd, J 8.4 and 2.8, ArH), 6.75 (2H, d,
6
J 2.8, ArH), 6.82 (2H, d, J 8.5, ArH), 7.89 (2H, s, MOH) and
7.99 (2H, s, MOH).
Polymers 22–28
2,2∞,5,5∞-Tetrahexyloxybiphenyl 16
1,3-Dibromo-5-tetradecylbenzene 19 (1.48 g, 3.42 mmol), tetra-
kis(triphenylphosphine)palladium (0.091 g, 7.85×10−5 mmol)
and the trisboronic acid 5 (1.49 g, 2.25 mmol) in dry ethanol
(10 cm3) were added to stirred dry toluene (80 ml) followed,
after 15 min, by aqueous sodium carbonate (20 cm3, 2 ). The
stirred inhomogeneous mixture was slowly heated to reflux
temp. and refluxed under an argon atmosphere for 3 weeks.
After cooling, insoluble black materials were filtered off and
the layers were separated. The organic phase was washed with
dilute hydrochloric acid and water and concentrated to about
15 cm3. Methanol was added to precipitate a grey solid. This
was redissolved in diethyl ether (50 cm3) and the ether was
added to methanol to give the polymer 22 (0.66g, 31%) as a
light grey powder which decomposes at ca. 170 °C. Anal.
Table 1; d (CDCl ) 0.7–1.0 (27H, br m, MCH ), 1.0–1.5
A
mixture of 2,2∞,5,5∞-tetrahydroxybiphenyl 15 (2.0 g,
9.17 mmol), 1-bromohexane (9.1 g, 55 mmol) and powdered
potassium carbonate (11.04 g, 80 mmol) in ethanol (120 cm3)
was refluxed for 15 h. After cooling, insoluble material was
filtered off and the filtrate concentrated, diethyl ether (100 cm3)
was added, and the ether solution washed with dilute aqueous
sodium hydroxide, water and brine, and dried with magnesium
sulfate. Removal of the solvent gave a brownish oily residue.
This was chromatographed on a large silica gel column eluting
with 10% dichloromethane in hexane. The first main fraction
gave an oil which solidified to give 16 as a waxy solid on
cooling (4.05 g, 80%) mp 35–35.5 °C. (Found: C, 78.45; H,
10.45. C H O requires C, 77.93; H, 10.53%); d (CDCl )
36 58
4
H
3
0.84–0.89 (12H, m, MCH ), 1.21–1.43 (24H, m, MCH M),
3
2
H
3
3
1.57 (4H, t, J 6.1, MCH M), 1.75 (4H, t, J 6.5, MCH M), 3.81
(4H, t, J 6.2, MOCH M), 3.90 (4H, t, J 6.4, MOCH M) and
(108H, br m, MCH M), 1.5–1.8 (12H, br s, MOCH CH M),
2
2
2
2
2
2
2.6–2.8 (6H, br s, ArCH M), 3.8–4.0 (12H, br s, MOCH M)
and 6.9–7.7 (27H, br m, ArH).
2
2
2
6.81–6.84 (6H, m, ArH); m/z 555 (17%), 554 (M+, 36), 278
(35) and 110 (100).
In a similar manner 1,3,5-tribromobenzene 20 (0.374 g,
1.19 mmol), tetrakis(triphenylphosphine)palladium (0.041 g,
3.54×10−5 mmol) and a solution of trisboronic acid 8 (1.0g,
1.18 mmol) gave a product which was extracted with dichloro-
methane and reprecipitated with methanol. It was further
extracted with tetrahydrofuran in a Soxhlet apparatus for 24 h.
The resulting solution was allowed to cool to room temp. and
concentrated, and the polymer 23 reprecipitated by adding to
4,4∞-Dibromo-2,2∞,5,5∞-tetrahexyloxybiphenyl 17
A solution of bromine (1.96 g, 12.2 mmol) in chloroform
(20 cm3) was added to a solution of 2,2∞,5,5∞-tetrahexyloxybi-
phenyl 17 (2.90 g, 5.23 mmol) in chloroform (40 cm3) at 0 °C.
The reaction mixture was stirred at 0 °C for 1 h and left at
room temp. for 10 h. The organic layer was washed with water
and dried with magnesium sulfate. Solvent was removed under
reduced pressure to give a light brown oily residue. This was
chromatographed on a short silica gel column eluting with
hexane–dichloromethane (451). Removal of the solvent from
the first fraction gave 17 as a near-white solid (3.10 g, 83%),
methanol, as a grey powder (0.60g, 65%). Anal. Table 1; d
(CDCl ) 0.7–0.9 (12H, br s, MCH ), 1.0–1.4 (42H, br m,
H
3
2
3
2
MCH M), 1.4–1.7 (6H, br s, MOCH CH M), 2.6–2.8 (6H, br
s, ArCH M), 3.6–3.9 (6H, br s, MOCH M) and 6.7–7.5 (12H,
br m, ArH).
2
2
2
In a similar manner 1,3,5-tris(4-bromophenyl)benzene 21
(1.36 g, 2.5 mmol), tetrakis(triphenylphosphine)palladium
(0.087 g, 7.5×10−5 mmol) and trisboronic ester 8 (2.31g,
2.5 mmol) gave the polymer 24 (1.5 g, 58%). Anal. Table 1;
mp 44–44.7 °C, which was used ‘crude’ for the next step. d
H
(CDCl ) 0.85 (6H, t, J 7.1, MCH ), 0.89 (6H, t, J 6.7, MCH ),
3
3
3
1.23–1.82 (32H, m, MCH M), 3.81 (4H, t, J 6.5, MOCH M),
2
2
3.95 (4H, t, J 6.5, MOCH M), 6.85 (2H, s, ArH) and 7.12 (2H,
2
l
(dichloromethane) 363 nm; d (CDCl ) 0.7–0.9 (12H, br
s, ArH); m/z 714 (62%), 712 (M+, 97%), 710 (57), 378 (21),
max
H
3
s, MCH ), 1.0–1.4 (42H, br m, MCH M), 1.4–1.7 (6H, br s,
MOCH CH M), 3.6–3.9 (6H, br s, MOCH M) and 6.7–7.5
(24H, br m, ArH).
376 (39) and 374 (23).
3
2
2
2
2
4,4∞-Bis(dihydroxyboryl)-2,2∞,5,5∞-tetrahexyloxybiphenyl 18
In a simillar manner, tris(3-bromophenyl)amine 11 (0.9 g,
1.87 mmol), tetrakis(triphenylphosphine)palladium (0.0645 g,
5.58×10−5 mmol) and trisboronic acid 8 (1.57 g, 1.86 mmol)
gave a greenish solid which was dissolved in diethyl ether
(20 cm3) and reprecipitated with methanol giving the polymer
n-Butyllithium in hexane (5.93 cm3, 1.6 , 9.5 mmol) was added
over a period of 15 min to a solution of 4,4∞-dibromo-2,2∞,5,5∞-
tetrahexyloxybiphenyl 17 (3.0 g, 4.21 mmol) in dry tetrahydro-
furan (60 cm3) at −78 °C under an argon atmosphere. The
resulting white suspension was stirred at −78 °C under argon
for 2 h. The cold suspension was slowly cannulated into a
solution of triisopropyl borate (10.8 g, 57 mmol) in tetrahydro-
furan (10 cm3) at −78 °C under argon and stirred for 2 h when
a yellowish mixture was formed. This was stirred at room
temp. for about 10 h. The mixture was cooled to −78 °C and
the intermediate ester was hydrolysed by adding 2 hydro-
25 as a greenish powder (0.95g, 53%). Anal. Table 1; l
max
(dichloromethane) 330 nm; d (CDCl ) 0.7–0.9 (12H, br s,
MCH ), 1.0–1.4 (42H, br m, MCH M), 1.4–1.7 (6H, br s,
H
3
3
2
MOCH CH M), 3.6–3.9 (6H, br s, MOCH M) and 6.6–7.7
(21H, br m, ArH).
2
2
2
In a similar manner 1,3,5-tribromobenzene 20 (0.50 g,
1.57 mmol), tetrakis(triphenylphosphine)palladium (0.054 g,
2352
J. Mater. Chem., 1997, 7(12), 2343–2354