New parts for a construction set of bifunctional oligo(het)arylene building blocks for modular chemistry

Article abstract of DOI:10.1055/s-2000-6344

The 100 mg to 5 g scale synthesis of a variety of arylene (6, 11, 13) and hetarylene building blocks (15, 17, 18) by and for Suzuki/Stille type cross-coupling reactions is reported. These building blocks carry solubilizing hexyloxymethyl substituents as well as boronic acid ester and Br/I functionalities. This considerably widens the already existing construction set for the modular chemistry approach to shape persistent and functional compounds on the nanometer scale.

Full text of DOI:10.1055/s-2000-6344

442
PAPER
New Parts for a Construction Set of Bifunctional Oligo(het)arylene Building
Blocks for Modular Chemistry
Govindaswamy Manickam, A. Dieter Schlüter*
Freie Universität Berlin, Institut für Chemie/Organische Chemie, Takustr. 3, D-14195 Berlin, Germany
Fax +49(30)83853357; E-mail: adschlue@chemie.fu-berlin.de
Received 22 November 1999
two features may be illustrated by the following example.
Abstract: The 100 mg to 5 g scale synthesis of a variety of arylene
Compound 10 with its "hidden" iodo function couples
(6, 11, 13) and hetarylene building blocks (15, 17, 18) by and for
with bromoiodobenzene 4 exclusively to 12 from which
the bromoiodo analogue can be easily generated which in
Suzuki/Stille type cross-coupling reactions is reported. These build-
ing blocks carry solubilizing hexyloxymethyl substituents as well as
boronic acid ester and Br/I functionalities. This considerably wid- turn reacts again exclusively at iodo.
ens the already existing construction set for the modular chemistry
approach to shape persistent and functional compounds on the na-
nometer scale.
The synthetic routes are organized according to the target-
ed building blocks 5,6 (Scheme 1), 10,11 (Scheme 2), 15
(first route; Scheme 3), 15 (second route; Scheme 4), and
18 (Scheme 5). Compound 2 was obtained by treating di-
bromide 1 with butyllithium, followed by the addition of
TMS chloride. For the conversion of 2 to 3, the solvent
and temperature turned out to be critical. If an ether/THF
mixture (1:1) was used yields reached 55-60%, whereas
when ether or THF were used as single solvents only trac-
es of product were obtained. For achieving optimum
yields of 3 it was important to allow BuLi and 2 to react
for approximately 2 h at 0 °C before the resulting anion
was quenched with boron triisopropoxide at low tempera-
ture. Compound 6 was then obtained by SCC of 3 and 4,
and subsequent iododesilylation of 5 with iodochloride at
ambient temperature in excellent yield.
Key words: Suzuki cross coupling, Stille cross coupling, supramo-
lecular chemistry, pyridines, modular chemistry
Shape persistent oligophenylene macrocycles with up to
24 phenylene rings are available through transition metal
catalyzed cross-coupling chemistry of appropriately func-
tionalized building blocks from a building set for modular
constructions.1,2 Recently this repetitive approach has
been expanded to hexagons carrying bipyridine (bipy) and
terpyridine donor moieties in the sides.3 These cycles are
interesting candidates for supramolecular applications.
During this work it became apparent that more building
blocks with pyridine units (from which bipys can be easily
synthesized) are required in order to ensure maximum
flexibility with regard to achievable ring size, substitution
pattern and sequence efficiency. We here report a variety
of novel arylene (6, 11, 13) and hetarylene building blocks
(15, 17, 18) for Suzuki type4 and related cross-coupling
chemistry directed towards cycle formation.
OC6H13
OC6H13
BuLi, Cl-SiMe3
Br
X
82 %
Br
Br
2
X = SiMe3
The building blocks reported here are linear and kinked
and carry not only the functional groups required for re-
petitive growth, but also hexyloxymethyl chains at posi-
tions which in the targeted cycles will be the corners.
These chains serve two purposes: they mediate solubility
during cycle construction and allow modifying the periph-
ery of the macrocycles once formed through ether cleav-
age and subsequent functionalization. The synthesis of the
bifunctional building blocks reported here required selec-
tive couplings which were accounted for mainly by two
features: (a) the use of the trimethylsilyl (TMS) group
serving as place holder for the iodo function and (b) the
large difference in coupling rate of iodo versus bromo
function in Suzuki cross-coupling (SCC) reaction.5 The
former feature is attractive because TMS can be virtually
quantitatively replaced by iodo under mild conditions
through reaction with iodo chloride,1,6 and the latter is im-
portant because the rate difference normally leads to a
specificity of the reaction course for the iodated carbon as
long as the coupling partner is not used in excess. These
1
OC6H13
1. BuLi, B(OiPr)3
2. Pinacol, Dioxane
I
Br
O
4
B
X
Pd(PPh3)4
55-60 %
O
1M Na2CO3
Toluene
82 %
3
X = SiMe3
OC6H13
X
Br
5
6
X = SiMe3
ICl, CH2Cl2
92 %
X = I
Scheme 1
Synthesis 2000, No. 3, 442–446 ISSN 0039-7881 © Thieme Stuttgart · New York

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New Parts for a Construction Set of Bifunctional Oligo(het)arylene Building Blocks
443
OC6H13
Compound 9 was obtained by converting one bromo func-
tion of 1 into a boronic ester to give 7, followed by SCC
of 7 with 8. The conversion of 9 into 10 turned out to be a
difficult step. Best, but still not satisfying yields of 10-
20% were obtained when the reaction was done in a dieth-
yl ether/THF mixture. The results were worse when dieth-
yl ether, THF or toluene were employed as single
solvents. In all these cases lithiation at the benzylic carbon
competed effectively (NMR) and could not be avoided.
Despite the limitations encountered in this step, com-
pound 10 could be obtained on the 1 g scale. Subsequent
conversion of 10 to 11 went smoothly without affecting
the boronic ester function.
Pd(PPh3)4
1M Na2CO3
10
+
4
Toluene
76 %
Br
X
12 X = SiMe3
13 X = I
ICl, CH2Cl2
94 %
OC6H13
Me3Sn
N
Br
14
OC6H13
I
SiMe3
Pd(PPh3)4
Toluene
Br
1. BuLi, B(OMe)3
8
N
Br
16 %
15
1
O
Br
B
2. Pinacol, Dioxane
68 %
Pd(PPh3)4
1M Na2CO3
Toluene
86 %
O
an investigation of the self-aggregation of pyridine deriv-
atives with boranes, see ref. 8.
7
Scheme 3
OC6H13
1. BuLi, B(OiPr)3
2. Pinacol, Dioxane
O
14
+
B
I
Br
Pd(PPh3)4
Toluene
52-58 %
O
10-20 %
X
OC6H13
16
9
X = SiMe3
O
B
O
O
6
B
N
Br
17
15
O
Pd(PPh3)4
1M Na2CO3
X
Toluene, 63 %
10 X = SiMe3
ICl, CH2Cl2
96 %
Scheme 4
11 X = I
Scheme 2
OC6H13
Pd(PPh3)4
Toluene
Compound 15 was synthesized by two different approach-
es. In the first (Scheme 3), SCC between 10 and 4 gave 12
which was converted into 13 by iododesilylation. Because
the subsequent Stille7 coupling with 14 gave compound
15 in moderate yield only, another approach was tried
which avoided this step. Stille reaction of 14 and 16 gave
17 in good yield, whose coupling with 6 also gave 15
(Scheme 4). Considering the overall synthetic effect asso-
ciated with both routes, the latter approach is clearly more
convenient than the former one. Whereas the first gave 15
on the 100 mg scale, the latter gave it on the 4-5 g scale.
Finally, compound 18 was prepared by the coupling of 11
with 14 (Scheme 5). Compounds 17 and 18 are sensitive
to silica gel. If exposed to silica gel for more than approx-
imately 3 hours partial decomposition was observed. For
11
+
14
O
23 %
B
O
N
Br
18
Scheme 5
Reagents were purchased from Fluka, Aldrich or Acros and used
without further purification. Solvents were purchased from Fluka,
Aldrich or Acros and purified and dried by standard methods. Start-
ing materials 1,3b 2,9 7,9 8,9 143b and 169 were prepared according to
literature procedures. All the reactions were carried out under N2
atm. 1H NMR (270 MHz) and 13C NMR (67.9 MHz) spectra were
recorded on a Bruker AM 270 spectrometer using CDCl3 as solvent
Synthesis 2000, No. 3, 442–446 ISSN 0039-7881 © Thieme Stuttgart · New York

444
G. Manickam, A. D. Schlüter
PAPER
with TMS as internal standard unless otherwise stated. Mass spectra
were recorded with a Varian MAT 711 spectrometer. Mps were de-
termined using Büchi 510 (open capillaries, uncorrected values).
Column chromatography was run with Merck flash silica gel (230-
400 mesh). Analytical TLC with aluminum sheets, silica gel Si 60
F254 (Merck), detection -UV absorption. Elemental analysis was
done using a Perkin-Elmer EA 240 instrument.
Anal. Calcd for C22H31BrOSi (419.47): C, 62.99; H, 7.45. Found: C,
62.10; H, 7.16.
4’-Bromo-3-hexyloxymethyl-5-iodobiphenyl (6)
To a stirred solution of 5 (6.2 g, 14.78 mmol) in CH2Cl2 (100 mL),
a solution of iodochloride (3.6 g, 22.17 mmol) in CH2Cl2 (50 mL)
was added dropwise over a period of 30 min at -10 °C and the re-
sulting mixture stirred at this temperature for 30 min. Then sat.
Na2S2O5 (50 mL) was added. The layers were separated and the
aqueous one was extracted with CH2Cl2 (2 x 50 mL). The combined
organic phases were dried (MgSO4) and concentrated. The crude
product was chromatographed through flash silica gel with hexane/
EtOAc (19:1) as eluent to give 6 (6.41 g, 92 %) as a colourless oil
which slowly crystallized, mp 56-57 °C.
2-(3-Hexyloxymethyl-5-trimethylsilanylphenyl)-4,4,5,5-tetra-
methyl-[1,3,2]-dioxaborolane (3)
To a stirred solution of 1-bromo-3-hexyloxymethyl-5-trimethylsila-
nyl benzene (2) (9.8 g, 28.5 mmol) in dry Et2O/THF (1:1 ratio, 200
mL), n-BuLi (2.74 g, 42.8 mmol, 26.8 mL, 1.6 M) in hexane was
added dropwise at -78 °C over 30 min. Stirring was continued at
this temperature for 2 h and then at 0 °C for an additional 3 h. The
mixture was recooled to -78 °C and a solution of triisopropyl bo-
rate (10.73 g, 57.1 mmol) in Et2O (20 mL) was added. Then the
mixture was allowed to warm to r.t. H2O was added, the layers were
separated, and the aqueous one was extracted with Et2O (2 x 100
mL). The combined organic phases were dried (MgSO4) and subse-
quent removal of the solvent under reduced pressure gave crude bo-
ronic acid as a viscous oil, which was used for the esterification
without further purification. The crude boronic acid (8.50 g, 27.57
mmol) and 2,3-dimethylbutane-2,3-diol (4.89 g, 41.35 mmol) were
dissolved in 1,4-dioxane (200 mL) and the mixture warmed to
60 °C for 2 h. The solvent was removed under reduced pressure and
the residue chromatographed through flash silica gel using hexane/
EtOAc (9:1) as eluent to give 3 (6.12-6.68 g, 55-60 % with refer-
ence to 2) as a colourless oil. The microanalytical data were not sat-
isfactory despite several attempts.
Rf = 0.84 (Hexane/EtOAc, 9:1).
1H NMR (CDCl3): d = 0.87 (t, 3H, J = 6.7 Hz, CH3), 1.25-1.39 (m,
6H, g-, d-, e-CH2), 1.58 (quintet, 2H, J = 6.7 Hz, b-CH2), 3.47 (t,
2H, J = 6.7 Hz, a-CH2), 4.47 (s, 2H, benzyl-CH2), 7.36-7.55 (m,
5H, phenyl-H), 7.66 (s, 1H, phenyl-H), 7.77 (t, 1H, J = 1.3 Hz, phe-
nyl-H).
13C NMR (CDCl3): d = 14.04, 22.60, 25.84, 29.64, 31.64, 70.90,
71.78, 94.85, 122.15, 125.29, 128.63, 131.92, 134.87, 135.45,
138.39, 141.57, 142.05.
MS: m/z (%) = 472 (M+, 11), 388 (29), 372 (20), 318 (26), 308 (33),
294 (21), 218 (100), 152 (29).
Anal. Calcd for C19H22BrIO (473.19): C, 48.23; H, 4.69. Found: C,
48.20; H 4.61.
5-Bromo-3-hexyloxymethyl-4’-trimethylsilylbiphenyl (9)
The synthesis and workup was similar to compound 5: Boronic es-
ter 7 (8.01 g, 20.14 mmol), 1-iodo-4-trimethylsilylbenzene (8) (6.67
g, 24.15 mmol), toluene (200 mL), 1 M aq Na2CO3 (200 mL),
(PPh3)4Pd (338 mg, 0.29 mmol), reflux 48 h, flash silica gel with
hexane/EtOAc (20:1) as eluent. Compound 9 (7.27 g, 86 %) was ob-
tained as a colourless oil.
Rf = 0.6 (Hexane/EtOAc, 9:1).
1H NMR (CDCl3): d = 0.29 (s, 9H, TMS), 0.89 (t, 3H, J = 6.6 Hz,
CH3), 1.17-1.43 (m, 6H, -CH2), 1.35 (s, 12H, (CH3)2C-C(CH3)2),
1.62 (quintet, 2H, J = 6.6 Hz, -CH2), 3.47 (t, 2H, J = 6.6 Hz, -CH2),
4.51 (s, 2H, benzyl-CH2), 7.63 (s, 1H, phenyl-H), 7.76 (s, 1H, phe-
nyl-H), 7.89 (s, 1H, phenyl-H).
13C NMR (CDCl3): d = -1.06, 13.99, 22.58, 24.81, 25.88, 29.70,
31.66, 70.48, 72.98, 83.63, 134.85, 135.61, 136.87, 138.89, 139.61.
MS: m/z (%) = 390 (M+, 10), 375 (M-CH3, 38), 304 (16), 289 (100),
190 (46), 179 (21), 129 (9), 73 (16).
HRMS: m/z calcd for C22H39BO3Si (M+) 390.27616. Found:
Rf : 0.94 (hexane/EtOAc, 9:1).
1H NMR (CDCl3): d = 0.32 (s, 9H, TMS), 0.92 (t, 3H, J = 6.6 Hz,
CH3), 1.29-1.44 (m, 6H, g-, d-, e-CH2), 1.66 (quintet, 2H, J = 6.6
Hz, b-CH2), 3.51 (t, 2H, J = 6.6 Hz, a-CH2), 4.47 (s, 2H, benzyl-
CH2), 7.50 (s, 2H, phenyl-H), 7.51-7.67 (m, 5H, phenyl-H).
390.26985.
13C NMR (CDCl3): d = -1.15, 14.05, 22.62, 25.86, 29.68, 31.66,
70.81, 72.01, 118.51, 122.86, 124.78, 126.37, 129.11, 133.85,
139.92, 140.05, 141.39, 143.18.
MS: m/z (%) = 420 (M+, 37), 405 (100), 320 (81), 304 (24), 239
(24), 165 (6), 73 (8).
4’-Bromo-3-hexyloxymethyl-5-trimethylsilylbiphenyl (5)
Boronic ester 3 (7.52 g, 19.36 mmol) and 1-bromo-4-iodobenzene
(4) (5.99 g, 21.20 mmol) were dissolved in a mixture of toluene
(190 mL) and aq 1 M Na2CO3 (190 mL). The mixture was degassed,
then (PPh3)4Pd (302 mg, 0.26 mmol) was added and the system was
degassed again. After the mixture was refluxed for 48 h, the layers
were separated and the aqueous one was extracted with toluene (2 x
50 mL). The combined organic phases were dried (MgSO4) and
evaporated under reduced pressure. The crude product was chro-
matographed through flash silica gel with hexane/EtOAc (25:1) as
eluent to give 5 (6.63 g, 82 %) as a colourless oil.
Anal. Calcd for C22H31BrOSi (419.47): C, 62.99; H, 7.45. Found: C,
61.93; H, 7.29.
2-(5-Hexyloxymethyl-4’-trimethylsilanylbiphenyl-3-yl)-4,4,5,5-
tetramethyl-[1,3,2]-dioxaborolane (10)
To a stirred solution of 9 (5.02 g, 11.97 mmol) in anhyd Et2O/THF
(1:1 v/v, 200 mL) butyl lithium (0.92 g, 14.36 mmol, 9 mL 1.6 M)
in hexane was added dropwise at -78 °C over a period of 30 min.
The mixture was then stirred at this temperature for 6 h and a solu-
tion of triisopropyl borate (4.50 g, 23.92 mmol) in Et2O (20 mL)
added. The mixture was allowed to warm to r.t. overnight. Then
H2O was added, the layers were separated, and the aqueous one was
extracted with Et2O (2 x 100 mL). The combined organic phases
were dried (MgSO4) and evaporated under reduced pressure. The
residue was chromatographed through silica gel first with EtOAc/
hexane (9:1) as eluent to remove the impurities and then with
EtOAc/hexane (1:1) to wash the product off the column to give 1.39
Rf = 0.94 (Hexane/EtOAc, 9:1).
1H NMR (CDCl3): d = 0.42 (s, 9H, TMS), 0.88 (t, 3H, J = 6.7 Hz,
CH3), 1.27-1.50 (m, 6H, g-, d-, e-CH2), 1.57 (quintet, 2H, J = 6.7
Hz, b-CH2), 3.56 (t, 2H, J = 6.7 Hz, a-CH2), 4.58 (s, 2H, benzyl-
CH2), 7.50-7.68 (m, 7H, phenyl-H).
13C NMR (CDCl3): d = -1.09, 14.04, 22.62, 25.92, 29.72, 31.68,
70.69, 72.86, 121.43, 126.87, 128.86, 131.04, 131.75, 131.83,
138.50, 139.42, 140.37, 141.37.
MS: m/z (%) = 420 (M+, 17), 405 (13), 319 (20), 303 (10), 239 (10),
223 (7), 165 (10), 73 (100).
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New Parts for a Construction Set of Bifunctional Oligo(het)arylene Building Blocks
445
g of crude boronic acid, which was used for the esterification with-
out further purification.
mmol), reflux for 48 h, flash silica gel with hexane/EtOAc (20:1) as
eluent. Yield: 12 (500 mg, 76 %), colourless oil.
Rf = 0.82 (Hexane/EtOAc, 9:1).
1H NMR (CDCl3): d = 0.39 (s, 9H, TMS), 0.92 (t, 3H, J = 6.6 Hz,
CH3), 1.32-1.49 (m, 6H, g-, d-, e-CH2), 1.74 (quintet, 2H, J = 6.6
Hz, b-CH2), 3.63 (t, 2H, J = 6.6 Hz, a-CH2), 4.74 (s, 2H, benzyl-
CH2), 7.62-7.78 (m, 4H, phenyl-H), 7.89 (s, 1H, phenyl-H), 8.22 (s,
1H, phenyl-H), 8.45 (s, 1H, phenyl-H).
1H NMR (CDCl3): d = 0.32 (s, 9H, TMS), 0.89 (t, 3H, J = 6.7 Hz,
CH3), 1.32-1.53 (m, 6H, g-, d-, e-CH2), 1.56-1.72 (m, 2H, b-CH2),
3.52 (t, 2H, J = 6.6 Hz, a-CH2), 4.62 (s, 2H, benzyl-CH2), 7.49-
7.73 (m, 11H, phenyl-H).
13C NMR (CDCl3): d = -1.08, 14.01, 22.59, 25.90, 29.77, 31.68,
70.73, 72.81, 120.09, 126.71, 131.69, 133.61, 133.85, 138.89,
139.39, 141.04, 141.46.
13C NMR (CDCl3): d = -1.11, 14.04, 22.62, 25.92, 29.74, 31.69,
70.80, 72.73, 121.67, 125.05, 125.14, 125.72, 126.57, 127.25,
128.82, 131.85, 139.61, 131.99, 133.83, 140.64, 141.22, 142.02.
MS: m/z (%) for trimer C66H93B3O6Si3 = 1099 (M+, 16), 999 (11),
MS: m/z (%) = 496 (M+, 43), 481 (42), 396 (100), 380 (17), 315
813 (16), 739 (31), 451 (33), 351 (63), 325 (100).
(23), 73 (14).
Anal. Calcd for C66H93B3O6Si3 (1099.14): C, 72.12; H, 8.53. Found:
C, 71.57; H, 8.34.
HRMS: m/z calcd for (C28H35BrOSi) 494.164056. Found:
494.16287.
The crude boronic acid (1.39 g, 3.62 mmol) and 2,3-dimethylbu-
tane-2,3-diol (0.64 g, 5.41 mmol) were dissolved in 1,4-dioxane (20
mL) and the mixture warmed to 60 °C for 2 h. The solvent was then
removed under reduced pressure and the residue chromatographed
through flash silica gel using hexane/EtOAc (9:1) as eluent to give
10 (0.56-1.1 g, 10-20% with reference to 9) as a colourless oil.
4’’-Bromo-5’-hexyloxymethyl-4-iodo-[1,1’;3’,1’’]-terphenyl (13)
Synthesis and workup was similar to that of compound 6. Com-
pound 12 (500 mg, 1.01 mmol), CH2Cl2 (25 mL), and iodochloride
(200 mg, 1.23 mmol) in CH2Cl2 (10 mL) were used. Compound 13
(520 mg, 94%) was obtained as a colourless oil, which slowly crys-
tallized, mp 55-57 °C.
Rf = 0.77 (Hexane/EtOAc, 9:1).
Rf = 0.75 (Hexane/EtOAc, 9:1).
1H NMR (CDCl3): d = 0.30 (s, 9H, TMS), 0.89 (t, 3H, J = 6.6 Hz,
CH3), 1.29-1.39 (m, 6H, g-, d-, e-CH2), 1.35 (s, 12H, (CH3)2C-
C(CH3)2), 1.72 (quintet, 2H, J = 6.6 Hz, b-CH2), 3.48 (t, 2H, J = 6.6
Hz, a-CH2), 4.56 (s, 2H, benzyl-H), 7.51-7.64 (m, 4H, phenyl-H),
7.70 (s, 1H, phenyl-H), 7.73 (s, 1H, phenyl-H), 7.96 (s, 1H, phenyl-
H).
13C NMR (CDCl3): d = -1.10, 14.02, 22.61, 24.86, 25.89, 29.74,
31.69, 70.61, 72.80, 83.84, 126.59, 129.37, 132.81, 133.09, 133.65,
138.51, 139.07, 140.66, 141.41.
1H NMR (CDCl3): d = 0.88 (t, 3H, J = 6.6 Hz, CH3), 1.26-1.44 (m,
6H, g-, d-, e-CH2), 1.65 (quintet, 2H, J = 6.6 Hz, b-CH2), 3.53 (t,
2H, J = 6.6 Hz, a-CH2), 4.60 (s, 2H, benzyl-CH2), 7.33-7.38 (m,
2H, phenyl-H), 7.46 (s, 1H, phenyl-H), 7.49-7.51 (m, 3H, phenyl-
H), 7.56 (s, 1H, phenyl-H), 7.58-7.60 (m, 2H, phenyl-H), 7.76 (d,
2H, J = 7.8 Hz, phenyl-H).
13C NMR (CDCl3): d = 14.02, 22.62, 25.90, 29.72, 31.67, 70.88,
72.61, 93.34, 118.71, 121.79, 124.70, 124.98, 127.23, 128.80,
129.03, 131.88, 139.73, 140.22, 140.31, 140.81, 140.87.
MS: m/z (%) = 466 (M+, 87), 451 (62), 366 (100), 351 (98), 266 (9),
73 (7).
MS: m/z (%) = 548 (M+, 34), 448 (100), 370 (23), 242 (59), 165 (7).
Anal. Calcd for C25H26BrIO (549.29): C, 54.67; H, 4.77. Found: C,
54.96; H 4.94.
Anal. Calcd for C28H43BO3Si (466.54): C, 72.09; H, 9.29. Found: C,
71.53; H, 9.20.
2-Bromo-5-(4’’-bromo-5’-hexyloxymethyl-[1,1’;3’,1’’]-terphe-
nyl-4-yl)pyridine (15)
Method A:
2-(5-Hexyloxymethyl-4’-iodobiphenyl-3-yl)-4,4,5,5-tetrameth-
yl-[1,3,2]-dioxaborolane (11)
Synthesis and workup similar to compound 6: compound 10 (1.12
g, 2.40 mmol), CH2Cl2 (25 mL), iodochloride (0.47 g, 2.89 mmol),
CH2Cl2 (10 mL), flash silica gel with hexane/EtOAc (19:1) as elu-
ent. Compound 11 (1.20g, 96 %) was obtained as a colourless oil,
which slowly crystallized, mp 54-56 °C.
Iodo compound 13 (510 mg, 0.93 mmol) and 2-bromo-5-(trimeth-
ylstannyl)pyridine (14) (357 mg, 1.11 mmol) were dissolved in tol-
uene (15 mL). The mixture was degassed, then (PPh3)4Pd (21 mg,
0.018 mmol) added and the system degassed again. This mixture
was refluxed for 48 h then cooled to r.t. and extracted with sat. KF
(10 mL). The crude product was chromatographed through flash sil-
ica gel with hexane/EtOAc (4:1) as eluent to give 15 (90 mg, 16 %)
as a colourless viscous oil.
Rf = 0.68 (Hexane/EtOAC, 9:1).
1H NMR (CDCl3): d = 0.87 (t, 3H, J = 6.7 Hz, CH3), 1.26-1.45 (m,
6H, g-, d-, e-CH2), 1.34 (s, 12H, (CH3)2C-C(CH3)2), 1.56-1.63 (m,
2H, b-CH2), 3.47 (t, 2H, J = 6.7 Hz, a-CH2), 4.54 (s, 2H, benzyl-
CH2), 7.36 (d, 2H, J = 7.3 Hz,), 7.63 (s, 1H, phenyl-H), 7.71-7.75
(m, 3H, phenyl-H), 7.92 (s, 1H, phenyl-H).
13C NMR (CDCl3): d = 13.99, 22.58, 24.83, 25.85, 29.68, 31.64,
70.67, 72.64, 83.89, 94.55, 128.97, 129.07, 132.36, 133.39, 134.06,
137.65, 138.72, 139.49, 140.50.
Method B:
Synthesis and workup similar to compound 5: Boronic ester 17
(4.12 g, 11.44 mmol), iodo compound 6 (5.41 g, 11.44 mmol), tol-
uene (115 mL), aq Na2CO3 (1 M, 115 mL), (PPh3)4Pd (198 mg, 0.17
mmol), reflux for 48 h, flash silica gel, hexane/EtOAc (4:1). Com-
pound 15 (4.18 g, 63 %) was obtained as a colourless viscous oil.
HRMS: m/z calcd for C25H34BIO3 (M+) 520.16457. Found:
520.16296.
Rf = 0.44 (Hexane/EtOAc, 9:1).
1H NMR (CDCl3): d = 0.88 (t, 3H, J = 6.6 Hz, CH3), 1.24-1.43 (m,
6H, g-, d-, e-CH2), 1.66 (quintet, 2H, J = 6.6 Hz, b-CH2), 3.55 (t,
2H, J = 6.6 Hz, a-CH2), 4.61 (s, 2H, benzyl-CH2), 7.47-7.62 (m,
8H, phenyl-H), 7.68-7.76 (m, 5H, phenyl- and pyrid-H), 8.61 (d,
1H, J = 2.2 Hz, pyrid-H).
13C NMR (CDCl3): d = 13.98, 22.56, 25.86, 29.68, 31.62, 70.85,
72.59, 121.75, 124.76, 125.42, 127.27, 127.93, 128.73, 131.83,
135.30, 135.44, 136.62, 140.22, 139.71, 140.73, 140.93, 148.22.
Anal. Calcd for C25H34BrIO3 (520.25): C, 57.72; H, 6.59. Found: C,
57.83; H, 6.40.
4’’-Bromo-5’-hexyloxymethyl-4-trimethylsilyl-[1,1’;3’,1’’]-ter-
phenyl (12)
Synthesis and workup similar to compound 5: Boronic ester 10 (620
mg, 1.33 mmol), 1-bromo-4-iodobenzene (4) (410 mg, 1.45 mmol),
toluene (15 mL), aq Na2CO3 (1 M, 15 mL), (PPh3)4Pd (30 mg, 0.026
Synthesis 2000, No. 3, 442–446 ISSN 0039-7881 © Thieme Stuttgart · New York

446
G. Manickam, A. D. Schlüter
PAPER
MS: m/z (%) = 579 (M+2, 47), 398 (26), 385 (5).
Anal. Calcd for C30H37BBrNO3 (550.34): C, 65.47; H, 6.78; N, 2.55.
Found: C, 65.56; H, 6.64; N, 2.41.
HRMS: m/z calcd for C30H29Br2NO 577.06178. Found: 577.06634.
Anal. Calcd for C30H29Br2NO (579.37): C, 62.19; H, 5.04; N, 2.42.
Found: C, 60.74; H, 5.06; N, 2.14.
Acknowledgement
We thank the Deutsche Forschungsgemeinschaft (Sonderfor-
schungsbereich 448, TP A1) and the Fonds der Chemischen Indu-
strie for financial support. C. Grave, O. Henze, and U. Lehmann are
thanked for helpful discussions, and P. Dewi for help with some of
the experiments.
2-Bromo-5-[4-(4,4,5,5-tetramethyl-(1,3,2)dioxaborolan-2-yl)-
phenyl]pyridine (17)
Boronic ester 16 (20.10 g, 60.91 mmol) and 2-bromo-5-(trimethyl-
stannyl)pyridine (14) (20.52 g, 63.96 mmol) were dissolved in tol-
uene (700 mL). The mixture was degassed, then (PPh3)4Pd (2.2 g,
1.90 mmol) was added and the system degassed again. The resulting
mixture was refluxed for 48 h then cooled to r.t. and extracted with
sat. KF (300 mL) The crude product was chromatographed through
flash silica gel with hexane/EtOAc (4:1) as eluent to give 17
(11.41-12.72 g, 52-58%) as a white crystalline solid, mp 157-
158 °C.
References
(1) Schlüter, A. D.; Hensel, V.; Liess, P.; Lützow, K. Towards
Oligophenylene Cycles and Related Structures: A Repetitive
Approach in Modular Chemistry, Vol. 499; Michl, J., Ed.;
Nato ASI Series C, Kluwer: Dordrecht, 1997, p 241.
Hensel, V. Schlüter, A. D. Chem. Eur. J. 1999, 5, 421.
Hensel, V.; Schlüter, A. D. Eur. J. Org. Chem. 1999, 451.
(2) For related work on phenylacetylene cycles, see: Moore, J. S.;
Zhang, J. Angew. Chem., Int. Ed. Engl. 1992, 31, 922.
Höger, S.; Enkelmann, V. Angew. Chem., Int. Ed. Engl. 1995,
34, 2917.
Rf = 0.67 (Hexane/EtOAc, 4:1).
1H NMR (CDCl3): d = 1.33 (s, 12H, (CH3)2C-C(CH3)2), 7.49-7.53
(m, 3H, phenyl-H), 7.72 (1H, dd, J = 2.3 and 7.9 Hz, pyrid-H),
7.82-7.91 (m, 2H, J = 7.9 Hz, phenyl- and pyrid-H), 8.56 (d, 1H,
J = 2.3 Hz, pyrid-H).
13C NMR (CDCl3): d = 24.81, 83.93, 126.15, 127.95, 135.55,
135.73, 136.91, 138.93, 141.09, 148.43.
Höger, S.; Meckenstock, A. -D.; Pellen, H. J. Org. Chem.
1997, 62, 4556.
(3) (a) Lehmann, U.; Henze, O.; Schlüter, A. D. Chem. Eur. J.
1999, 5, 854.
MS: m/z (%) = 359 (M+, 100), 343 (27), 275 (43), 260 (57), 180
(52), 153 (18).
Anal. Calcd for C17H19BBrNO2 (360.05): C, 56.71; H, 5.32; N, 3.89.
Found: C, 56.78; H, 5.32; N, 3.70.
(b) Lehmann, U.; Henze, O.; Schlüter, A. D. Am. Chem. Soc.
Polym. Mater. Sci. Eng. 1999, 80, 165, 233.
(c) Henze, O.; Lehmann, U.; Schlüter, A. D. Synthesis 1999,
683.
(d) Henze, O.; Lehmann, U.; Schlüter, A. D. Am. Chem. Soc.
Polym. Mater. Sci. Eng. 1999, 80, 231.
(e) For a recent application of bipys in molecular grids see:
Garcia, A. M.; Romero-Salguero, F. J.; Bassani, D. M.; Lehn,
J. M.; Baum, G.; Fenske, D. Chem. Eur. J. 1999, 5, 1803.
Schubert, U. S.; Weidl, C. H.; Eschbaumer, C. Am. Chem. Soc.
Polym. Mater. Sci. Eng. 1999, 80, 22.
2-Bromo-5-{3’-hexyloxymethyl-5’-[4,4,5,5-tetramethyl-(1,3,2)-
dioxaborolan-2-yl]biphenyl-4-yl}pyridine (18)
Synthesis and work-up similar to compound 17: Boronic ester 11
(2.12 g, 4.07 mmol), 2-bromo-5-(trimethylstannyl)pyridine (14)
(1.57 g, 4.89 mmol), toluene (100 mL), (PPh3)4Pd (53 mg, 0.046
mmol), reflux for 48 h, aq KF (50 mL). Yield: 18 (545 mg, 23 %),
white crystalline solid, mp 146-148 °C.
Rf = 0.28 (Hexane/EtOAc, 9:1).
(4) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457.
(5) Gray, G. W., Hird, M.; Lacey, D.; Toyne, K. J. J. Chem. Soc.,
Perkin Trans. 2 1989, 2041.
(6) Harris, B. C.; Hovakeenian, G. H.; Lai, Y. -H.; Mestdagh, H.;
Vollhardt, K. P. C. J. Am. Chem. Soc. 1985, 107, 5670.
(7) Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508.
(8) Wakabayashi, S.; Sugihara, Y.; Takakura, K.; Murata, S.;
Tomioka, H.; Ohnishi, S.; Tatsumi, K. J. Org. Chem. 1999,
64, 6999.
1H NMR (CDCl3): d = 0.86 (t, 3H, J = 6.7 Hz, CH3), 1.24-1.35 (m,
6H, g-, d-, e-CH2), 1.30 (s, 12H, (CH3)2C-C(CH3)2), 1.61 (quintet,
2H, J = 6.7 Hz, b-CH2), 3.49 (t, 2H, J = 6.7 Hz,a-CH2), 4.56 (s, 2H,
benzyl-CH2), 7.51-7.60 (m, 3H, phenyl-H), 7.72-7.75 (m, 5H,
phenyl- and pyrid-H), 7.99 (s, 1H, phenyl-H), 8.60 (d, 1H, J = 2.2
Hz, pyrid-H).
13C NMR (CDCl3): d = 14.01, 22.59, 24.85, 25.87, 29.70, 31.66,
70.71, 72.06, 83.92, 126.98, 127.63, 128.02, 129.16, 132.58,
133.44, 135.16, 135.56, 136.73, 138.75, 139.66, 140.82, 141.26,
148.32.
(9) Lehmann, U. Ph. D. Thesis, Freie Universität, Berlin, 1999.
MS: m/z (%) = 549 (M+, 11), 451 (32), 420 (57), 312 (100), 294
(67), 231 (64).
Article Identifier:
1437-210X,E;2000,0,03,0442,0446,ftx,en;H09199SS.pdf
Synthesis 2000, No. 3, 442–446 ISSN 0039-7881 © Thieme Stuttgart · New York