Preparation of functionalized aryl(diallyl)ethoxysilanes and their palladium-catalyzed coupling reactions giving sol-gel precursors

Article abstract of DOI:10.1016/j.tet.2007.08.011

A series of molecular building blocks containing allylsilyl groups, which can be incorporated into the appropriate sol-gel precursors as fragments, were prepared. The allylsilyl group is retained unchanged over the course of all reactions giving sol-gel precursors and behave as the synthetic equivalent of alkoxysilyl groups toward sol-gel polymerization, but are stable enough to allow purification by silica gel chromatography. These allylsilanes were successfully used as building blocks to construct functional sol-gel precursors via palladium-catalyzed coupling reactions.

Full text of DOI:10.1016/j.tet.2007.08.011

Tetrahedron 63 (2007) 11467–11474
Preparation of functionalized aryl(diallyl)ethoxysilanes and their
palladium-catalyzed coupling reactions giving sol–gel precursors
Yoshifumi Maegawa,a Toyohiro Nagano,a Tatsuya Yabuno,a
Hiroki Nakagawaa and Toyoshi Shimadaa,b,
*
aDepartment of Chemical Engineering, Nara National College of Technology, 22 Yata-cho, Yamatokoriyama, Nara 639-1080, Japan
bCore Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 4-1-8 Honcho,
Kawaguchi, Saitama 332-0012, Japan
Received 19 July 2007; revised 5 August 2007; accepted 6 August 2007
Available online 8 August 2007
Abstract—A series of molecular building blocks containing allylsilyl groups, which can be incorporated into the appropriate sol–gel precur-
sors as fragments, were prepared. The allylsilyl group is retained unchanged over the course of all reactions giving sol–gel precursors and
behave as the synthetic equivalent of alkoxysilyl groups toward sol–gel polymerization, but are stable enough to allow purification by silica
gel chromatography. These allylsilanes were successfully used as building blocks to construct functional sol–gel precursors via palladium-
catalyzed coupling reactions.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
Herein we disclose a novel preparation method for a series of
molecular building blocks containing allylsilyl groups,
which can be incorporated into the appropriate sol–gel
precursors as fragments, and their palladium-catalyzed
coupling reactions giving sol–gel precursors (Scheme 1).
Organic–inorganic hybrid materials integrate the intrinsic
characteristics of organic and inorganic materials. The usual
method of preparation to date has been polymerization of or-
ganotrialkoxysilanes under sol–gel conditions.1 Materials
which incorporate functionalorganomoieties ina silicamatrix
have been prepared by Shea and Loy,2a–c Schubert,2d Corriu
and Cerveau,2e–g Inagaki,2h Ozin,1d Moreau and Dautel,2i
and our group.2j In the pioneer work in this area, Shea and
Loy reported the preparation and sol–gel polymerization of
a variety of bridged trialkoxyarylenesilanes.2a However, the
development of appropriate sol–gel precursors for organic–
inorganic hybrid materials has been rather slow compared to
the progress in the synthesis of chemicals and medicines, be-
cause trialkoxysilyl groups are so reactive toward hydrolysis
that their compounds cannot be handled under hydrolytic con-
ditions and cannot be purified by silica gel chromatography.
Coupling Partners
Si
R
Si
Fg
1 - 3
Sol-Gel Precursors
Molecular building blocks 1: R =Br, I, OTf
Molecular building blocks 2: R =MgX, BR1 , SnR2
Molecular building blocks 3: R =CHO, NH22
3
Si
OEt
Si =
Scheme 1. Coupling reactions with allylsilane building blocks.
2. Results and discussion
2.1. Preparation of molecular building blocks
for allylsilane sol–gel precursors
We recently found that allylsilyl groups behave as the syn-
thetic equivalent of alkoxysilyl groups, but are stable enough
to allow purification by silica gel chromatography.3 For
example, the use of 1,4-bis(triallylsilyl)benzene or 1,4-bis-
(diallylethoxysilyl)benzene in the place of 1,4-bis(triethoxy-
silyl)benzene gave the same organic–inorganic hybrid
materials containing periodic mesostructures with crystal-
like pore walls.3c
The use of a diallylethoxysilyl group as a polymerizable
moiety in allylsilyl sol–gel precursors is not only more effec-
tive for sol–gel polymerization, but also confers stability
under general hydrolysis conditions. We focused on diallyl-
ethoxysilyl sol–gel precursors as promising precursors of
organic–inorganic hybrid materials. Molecular building
blocks for allylsilane sol–gel precursors (MBAS) 1, 2, and
3 contain both a diallylethoxysilyl group to form Si–O–Si
* Corresponding author. Tel./fax: +81 743 55 6154; e-mail: shimada@
chem.nara-k.ac.jp
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2007.08.011

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Y. Maegawa et al. / Tetrahedron 63 (2007) 11467–11474
bonds by polymerization under sol–gel conditions, and
a functional group which is active toward cross-coupling re-
actions to give the desired sol–gel precursors. Bromide 1a
was prepared by rhodium-catalyzed triethoxysilylation4 of
1-bromo-4-iodobenzene with triethoxysilane followed by
the addition of allylmagnesium bromide, with a total yield
of 74%.5 A Grignard-exchange reaction of 1,4-diiodoben-
zene with isopropylmagnesium chloride6 followed by the
addition of tetraethoxysilane and subsequent treatment
with allylmagnesium bromide gave iodide 1b in a total yield
of 60%. Trifluoromethanesulfonylation of 4-(diallylethoxy-
silyl)phenol, prepared from 4-iodophenol, was achieved by
treatment with Comins’ reagent7 to give the triflate 1c in
84% yield (Scheme 2).
Our attempts to transform 1a and 1b to 2 via lithiation with
butyllithium, and the preparation of Grignard reagent 2a
using magnesium metal, were unsuccessful. However, iso-
propylmagnesium chloride was successfully used for
a Grignard-exchange reaction of 1b to give key compound
2a, leading to 2b, 2c, and 3a in 100%, 99%, and 85% yields
for two steps, respectively (Scheme 3). Surprisingly, diallyl-
ethoxysilyl group is compatible with Grignard moiety in 2a
derived from 1b. It is noteworthy that easily prepared aryl-
halides are coupling partners of 2 in palladium-catalyzed
cross-coupling reactions.
Table 1. Reactions of molecular building blocks with coupling partnersa
Br
Br
Br
[Rh(cod)(CH3CN)2]BF4, HSi(OEt)3
coupling
+
Si
R
Si
Fg
MgBr
partners
allylsilane sol-gel
precursors
Et2O
91%
molecular building
blocks
nBu4NI, Et3N, DMF
81%
(EtO)3Si
(EtO)3Si
Si
I
1a
Entry Building
block
Coupling
partner
Product
Yieldb
(%)
I
I
I
MgBr
1) i-PrMgCl, THF, -30 °C
2) Si(OEt)4, rt
61%
H
SiMe3
1
2
87
61
Si
SiMe3
Et2O
98%
Si
I
1b
B(OH)2
Si
1a
OH
OH
OH
MgBr
[Rh(cod)(CH3CN)2]BF4, HSi(OEt)3
nBu4NI, Et3N, DMF
(EtO)3Si
Et2O
78% (2 steps)
3
4
5
6
7
8
Ph2NH
62
100
89
Si
NPh2
I
Si
Cl
Tf
OTf
H
MeO
MeO
OH
Si
OH
N
N
Tf
, i-Pr2NEt
1b
CH2Cl2
84%
Si
B(OH)2 Si
B(OH)2 Si
OMe
OMe
1c
Scheme 2. Preparation of molecular building blocks 1a–1c.
1c
2a
2b
76
O
i
PrO
B
O
O
i-PrMgCl
Si
B
1b
Si
MgCl
-78 °C
THF, -30 °C
O
Br
Si
91
for 1 h, then rt
100%
2a
2b
N
N
N
DMF, rt
85%
Me3SnCl, rt
99%
89
I
OMe
Si
OMe
Si
CHO
Si
SnMe3
Br
Si
9
2c
3a
50
94
3a
2c
N
Pd2(dba)3, HSi(OEt)3,
(o-biphenyl)P(t-Bu)2
10
PPh3Me+Iꢀ
Si
I
NH2
(EtO)3Si
NH2
i-Pr2NEt, NMP
80%
Si
NH
MgBr
11
3b
77
I
Me
Si
NH2
Et2O
96%
Me
3b
a
All the reaction conditions are shown in Section 4.
Isolated yield.
b
Scheme 3. Preparation of molecular building blocks 2 and 3.

Y. Maegawa et al. / Tetrahedron 63 (2007) 11467–11474
11469
Meanwhile, 3b, obtained by palladium-catalyzed silylation8
of 4-iodoaniline followed by allylation with allylmagnesium
bromide, may be used in transition metal-catalyzed amina-
tion (Scheme 3).9
precursors, open the door to a new branch of materials
chemistry.
3. Conclusions
2.2. Cross-coupling reactions of molecular building
blocks with various coupling partners
In summary, we have demonstrated a new method of prepar-
ing many types of sol–gel precursors containing various
MBAS. This method overcomes the limitations associated
with the conventional method using alkoxysilanes, and
thus can be applied as a general synthesis for organic–
inorganic functional hybrid precursors.
Cross-coupling reactions of MBAS were carried out with
various substrates, and the results are summarized in Table
1. The diallylethoxysilyl group was retained unchanged
over the course of all reactions. The molecular building
block 1 smoothly underwent palladium-catalyzed Suzuki–
Miyaura10 and Sonogashira coupling reactions,11 and Buch-
wald–Hartwig amination9 to afford the corresponding
coupling products containing an allylsilyl group (entries
1–6, Table 1).
4. Experimental section
4.1. General procedures
Grignardcross-coupling12 andStillecouplingreaction13 of2a
and 2c with 2-bromopyridine gave 2-(4-diallylethoxysilyl-
phenyl)pyridine in 91% and 50% yields, respectively, and
Suzuki coupling reaction of 2b with 4-iodoanisole gave
thecorrespondingproductin89%yield(entries7–9). Further-
more, Wittig olefination of 3a with methyltriphenylphospho-
nium iodide gave a styrene MBAS, which is useful for the
Mizoroki–Heck reaction, in 94% yield, and amination9 of
4-iodotoluene with 3b proceeded smoothly to give the
corresponding product in 77% yield (entries 10 and 11).
All moisture sensitive manipulations were carried out under
a nitrogen atmosphere. Nitrogen gas was dried by passage
through P2O5. Optical rotations were recorded with a JASCO
DIP-370 polarimeter. NMR spectra were recorded on JEOL
1
JNM LA500 spectrometer (270 MHz for H, 67.5 MHz for
13C, and 109 MHz for 31P). Chemical shifts are reported in
d ppm referenced to an internal SiMe4 standard for 1H
NMR, chloroform-d (d 77.0) for 13C NMR, and an external
85% H3PO4 standard for 31P NMR. High resolution mass
spectra (HRMS) were recorded with JEOL JMS-700
spectrometer.
The reactions of MBAS with various coupling partners also
resulted in the development of a broadly applicable synthesis
for bridged sol–gel precursors. We prepared novel sol–gel
precursors such as BINAP derivative 4a in 71% yield from
the reaction of 5,50-diethynyl-BINAP dioxide14 with 1b, bi-
phenylene amine 4b in 72% yield from the reaction of 4,40-
diiodobiphenyl with 3b, and oligophenylene-ethynylene 4c
in 94% yield from the reaction of 4,40-diethynyltolan15
with 1b (Scheme 4). We are convinced that a synthetic
method using MBAS would, in addition to its wide applica-
tion to easy preparation of functionally bridged sol–gel
4.2. Preparation of molecular building blocks
4.2.1. 1-Bromo-4-(diallylethoxysilyl)benzene 1a. To a so-
lution of 1-bromo-4-iodobenzene (2.60 g, 9.19 mmol), tetra-
butylammonium iodide (3.39 g, 9.18 mmol), triethylamine
(2.56 mL, 18.4 mmol), and [Rh(cod)(CH3CN)2]BF4
(105 mg, 0.277 mmol) in DMF (26 mL) was added dropwise
triethoxysilane (1.87 mL, 10.1 mmol) at 0 ꢁC. The mixture
was stirred at 80 ꢁC for 1 h. The mixture was concentrated
under reduced pressure, treated with Et2O, and filtered
PdCl2(PPh3)2, CuI, Et3N
+
H
H
Si
Si
Si
I
°
PhH, 50
71%
C
1b
PPh2
O
PPh2
O
Ph2P
O
Ph2P
O
Si
4a
Pd2(dba)3, (o-biphenyl)P(t-Bu)2, NaOt-Bu
HN
NH
+
Si
NH2
I
I
PhMe, rt
72%
3b
4b
Si
H
H
PdCl2(PPh3)2, CuI, Et3N
+
Si
Si
°
C
THF, 50
94%
Si
I
4c
1b
Scheme 4. Preparation of functional sol–gel precursors with molecular building blocks.

11470
Y. Maegawa et al. / Tetrahedron 63 (2007) 11467–11474
through a short Celite plug. The crude mixture was purified
by bulb-to-bulb distillation under reduced pressure to
give 2.38 g (81% yield) of 1-bromo-4-(triethoxysilyl)ben-
zene. To the resulting ethoxysilane (4.74 g, 14.8 mmol)
was added allylmagnesium bromide (59.4 mL, 1 M in ether,
59.4 mmol) in Et2O. The reaction mixture was stirred at
room temperature for 10 h and quenched with 10% HCl. It
was then diluted with Et2O and the organic layer was washed
with saturated NaHCO3 solution and brine, dried over anhy-
drous MgSO4, and evaporated under reduced pressure. The
crude mixture was purified by bulb-to-bulb distillation under
reduced pressure to give 4.20 g (91% yield) of 1-bromo-4-
4.2.3. 4-(Diallylethoxysilyl)phenyl triflate 1c. To a mixture
of 4-iodophenol (6 g, 27.3 mmol), [Rh(cod)(CH3CN)2]BF4
(104 mg, 0.27 mmol), and n-Bu4NI (10.0 g, 27.3 mmol)
were added DMF (180 mL), Et3N (11.4 mL, 81.8 mmol),
and (EtO)3SiH (15.1 mL, 81.8 mmol). The reaction mixture
was stirred at 80 ꢁC for 3 h. The mixture was concentrated
under reduced pressure, treated with Et2O, and filtered
through a short Celite plug. The filtrates were concentrated
under reduced pressure. To the residue was added dropwise
a solution of allylmagnesium bromide (1.0 M in Et2O,
136 mL, 136 mmol) at 0 ꢁC. The reaction mixture was
stirred at room temperature for 19 h and quenched with
10% HCl. It was then diluted with Et2O and the organic layer
was washed with saturated NaHCO3 solution and brine,
dried over anhydrous MgSO4, and evaporated under reduced
pressure. The residue was chromatographed on silica gel
(hexane/EtOAc¼5:1 as eluent) to give 4-(diallylethoxysi-
1
(diallylethoxysilyl)benzene (1a): H NMR (CDCl3) d 1.21
(t, J¼6.8 Hz, 3H), 1.91 (ddd, J¼7.8 Hz, 1.4 Hz, 1.1 Hz,
4H), 3.76 (q, J¼6.8 Hz, 2H), 4.92 (ddt, J¼9.7 Hz, 1.6 Hz,
1.1 Hz, 2H), 4.95 (ddt, J¼15.7 Hz, 1.6 Hz, 1.4 Hz, 2H),
5.79 (ddt, J¼15.7 Hz, 9.7 Hz, 7.8 Hz, 2H), 7.43 (d,
J¼8.4 Hz, 2H), 7.52 (d, J¼8.4 Hz, 2H); 13C NMR
(CDCl3) d 18.32, 21.08, 59.27, 114.96, 124.68, 130.90,
132.63, 133.88, 135.50. HRMS (FAB+) [MꢀH]+ calcd for
C14H18OBrSi 309.0310, found 309.0321. Anal. Calcd for
C14H19OBrSi: C, 54.02; H, 6.15. found: C, 53.93; H, 6.23.
1
lyl)phenol (5.30 g, 78%, in two steps): H NMR (CDCl3)
d 1.20 (t, J¼6.8 Hz, 3H), 1.92 (d, J¼7.8 Hz, 4H), 3.75 (q,
J¼6.8 Hz, 2H), 4.92 (ddt, J¼10.3 Hz, 1.4 Hz, 0.8 Hz, 2H),
4.96 (ddt, J¼15.9 Hz, 1.4 Hz, 1.1 Hz, 2H), 5.57 (br, 1H),
5.82 (ddt, J¼15.9 Hz, 10.3 Hz, 7.8 Hz, 2H), 6.85 (d,
J¼8.6 Hz, 2H), 7.46 (d, J¼8.6 Hz, 2H); 13C NMR (CDCl3)
d 18.30, 21.24, 59.29, 114.72, 115.04, 125.85, 133.19,
135.82, 157.18. To a mixture of 4-(diallylethoxysilyl)phenol
(197 mg, 0.79 mmol) and 2-[N,N-bis(trifluoromethylsulfo-
nyl)amino]-5-chloropyridine (343 mg, 0.87 mmol) were
added CH2Cl2 (5 mL) and i-Pr2NEt (553 mL, 3.17 mmol).
The reaction mixture was stirred at room temperature for
19 h. The reaction mixture was then concentrated. The resi-
due was chromatographed on silica gel (hexane/
EtOAc¼10:1 as eluent) to give 4-(diallylethoxysilyl)phenyl
triflate (253 mg, 84%): 1H NMR (CDCl3) d 1.23 (t,
J¼7.0 Hz, 3H), 1.93 (d, J¼7.8 Hz, 4H), 3.79 (q, J¼7.0 Hz,
2H), 4.91–4.99 (m, 4H), 5.79 (ddt, J¼16.2 Hz, 10.3 Hz,
7.8 Hz, 2H), 7.28 (d, J¼8.1 Hz, 2H), 7.67 (d, J¼
8.1 Hz, 2H); 13C NMR (CDCl3) d 18.28, 21.13, 59.43,
115.21, 120.55, 132.40, 136.05, 136.46, 150.87. Anal. Calcd
for C15H19O4F3SSi: C, 47.35; H, 5.03. Found: C, 47.47;
H, 5.05.
4.2.2. 1-Iodo-4-(diallylethoxysilyl)benzene 1b. To a solu-
tion of 1,4-diiodobenzene (15 g, 45.6 mmol) in THF
(114 mL) was added dropwise a solution of i-PrMgCl
(24 mL, 2 M in THF, 48 mmol) at ꢀ30 ꢁC. The reaction
mixture was stirred at ꢀ30 ꢁC for 5.5 h to give 4-iodophe-
nylmagnesium chloride solution. The resulting solution of
4-iodophenylmagnesium chloride was added dropwise
(three drops per second) via cannula at ꢀ30 ꢁC to tetraethyl
orthosilicate (60.6 mL, 272 mmol) in THF (90 mL), which
was cooled to ꢀ30 ꢁC. The reaction mixture was stirred at
ꢀ30 ꢁC for 1 h and then at room temperature for 44 h. To
the reaction mixture was added Et2O (100 mL) and then
washed with H2O. The mixture was extracted with Et2O.
The organic layer was washed with brine, dried over
MgSO4, and concentrated. The crude mixture was purified
by bulb-to-bulb distillation under reduced pressure
(1.5 mmHg, 120 ꢁC) to give 1-iodo-4-(triethoxysilyl)ben-
1
zene (10.2 g, 61%): H NMR (CDCl3) d 1.24 (t, J¼7.3 Hz,
9H), 3.88 (q, J¼7.3 Hz, 6H), 7.39 (dd, J¼7.8 Hz, 1.4 Hz,
2H), 7.73 (dd, J¼7.8 Hz, 1.4 Hz, 2H); 13C NMR (CDCl3)
d 18.36, 21.08, 59.35, 97.08, 115.04, 132.69, 134.49,
135.59, 136.87. HRMS (EI+) M+ calcd for C12H19O3ISi
358.0250, found 358.0243. To 1-iodo-4-(triethoxysilyl)benz-
ene (9.4 g, 25.7 mmol) was added dropwise a solution of
allylmagnesium bromide (77 mL, 1 M in Et2O, 77 mmol) at
0 ꢁC. The reaction mixture was stirred at room temperature
for 10 h and quenched with 10% HCl. It was then diluted
with Et2O and the organic layer was washed with saturated
NaHCO3 solution and brine, dried over anhydrous MgSO4,
and evaporated under reduced pressure. The residue was
chromatographed on silica gel (hexane/EtOAc¼20:1 as elu-
ent) to give 1-iodo-4-(diallylethoxysilyl)benzene (9.0 g,
98%): 1H NMR (CDCl3) d 1.20 (t, J¼6.8 Hz, 3H), 1.91 (d,
J¼8.1 Hz, 4H), 3.75 (q, J¼6.8 Hz, 2H), 4.98–4.89 (m,
4H), 5.87–5.71 (m, 2H), 7.29 (d, J¼8.1 Hz, 2H), 7.72 (d,
J¼8.1 Hz, 2H); 13C NMR (CDCl3) d 18.34, 21.08, 59.35,
97.08, 115.04, 132.69, 134.49, 135.59, 136.87. HRMS
(EI+) M+ calcd for C14H19OISi 358.0250, found 358.0243.
Anal. Calcd for C14H19OISi: C, 46.93; H, 5.35. Found: C,
46.80; H, 5.46.
4.2.4. 4-(Diallylethoxysilyl)phenylmagnesium chloride
2a. To a solution of 4-(diallylethoxysilyl)iodobenzene
(255 mg, 0.71 mmol) in THF (2 mL) was added a solution
of i-PrMgCl (0.71 mL, 2 M in THF, 1.42 mmol) at ꢀ30 ꢁC.
The reaction mixture was stirred at ꢀ30 ꢁC for 1.5 h to
give 4-(diallylethoxysilyl)phenylmagnesium chloride.
4.2.5. Diallyl[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
2-yl)phenyl]ethoxysilane 2b. To a solution of 4-(diallyl-
ethoxysilyl)iodobenzene (2.02 g, 5.64 mmol) in THF
(15 mL) was added a solution of i-PrMgCl (5.9 mL, 2 M
in THF, 11.8 mmol) at ꢀ30 ꢁC. The reaction mixture was
stirred at ꢀ30 ꢁC for 4 h to give 4-(diallylethoxysilyl)phe-
nylmagnesium chloride. To the Grignard reagent solution
was added 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxa-
borolane16 (2.3 mL, 11.3 mmol) at ꢀ78 ꢁC. The reaction
mixture was stirred at ꢀ78 ꢁC for 1 h, and then at room tem-
perature for 19 h. The reaction mixture was quenched with
10% HCl. It was then diluted with Et2O and the organic layer
was washed with saturated NaHCO3 solution and brine,
dried over anhydrous MgSO4, and evaporated under reduced
pressure. The residue was chromatographed on silica gel

Y. Maegawa et al. / Tetrahedron 63 (2007) 11467–11474
11471
(hexane/EtOAc¼3:1 as eluent) to give 1-(diallylethoxy-
silyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)ben-
zene (2.02 g, 100%): 1H NMR (CDCl3) d 1.20 (t, J¼7.0 Hz,
3H), 1.34 (s, 12H), 1.94 (d, J¼7.8 Hz, 4H), 3.75 (q,
J¼7.0 Hz, 2H), 4.89 (ddt, J¼10.3 Hz, 1.6 Hz, 1.1 Hz, 2H),
4.94 (ddt, J¼15.9 Hz, 1.6 Hz, 1.4 Hz, 2H), 5.81 (ddt,
J¼15.9 Hz, 10.3 Hz, 7.8 Hz, 2H), 7.58 (d, J¼8.4 Hz, 2H),
7.81 (d, J¼8.4 Hz, 2H); 13C NMR (CDCl3) d 18.33, 21.05,
24.81, 59.28, 83.76, 114.77, 127.74, 132.94, 133.22,
133.80, 138.49. HRMS (FAB+) [MꢀH]+ calcd for
C20H30O3BSi 357.2057, found 357.2070.
0.36 mmol) were added NMP (24 mL), i-Pr2NEt (3.13 mL,
18 mmol), and (EtO)3SiH (1.66 mL, 9.0 mmol). The reaction
mixturewas stirred at room temperature for 20 h. The reaction
mixture was then concentrated to remove excess of amine and
triethoxysilane.TheresiduewasdilutedwithEt2O, theorganic
layer was washed with H2O, dried over MgSO4, and concen-
trated. The residue was distilled under reduced pressure
(0.1 mmHg, 110 ꢁC) to give 4-(triethoxysilyl)aniline (1.23 g,
80%). To 4-(triethoxysilyl)aniline (1.15 g, 4.5 mmol) was
added dropwise a solution of allylmagnesium bromide
(1.0 M in Et2O, 22.5 mL, 22.5 mmol) at 0 ꢁC. The reaction
mixturewas stirred at room temperature for 13 h. The reaction
was quenched with H2O and the mixture was extracted with
Et2O. The organic layer was washed with saturated NaHCO3
and brine, dried over MgSO4, and concentrated. The residue
was chromatographed on silica gel (hexane/EtOAc¼3:1 as
eluent) to give 4-(diallylethoxysilyl)aniline (1.08 g, 96%):
1H NMR (CDCl3) d 1.48 (t, J¼7.0 Hz, 3H), 1.90 (d,
J¼8.4 Hz, 4H), 3.73 (q, J¼7.0 Hz, 4H containing NH2),
4.86–4.98 (m, 4H), 5.79 (ddt, J¼16.2 Hz, 9.5 Hz, 8.1 Hz,
2H), 6.68 (d, J¼8.1 Hz, 2H), 7.36 (d, J¼8.1 Hz, 2H); 13C
NMR (CDCl3) d 18.36, 21.36, 59.04, 114.37, 122.82,
133.55, 135.42, 136.00, 147.90. HRMS (FAB+) [M+H]+ calcd
for C14H22ONSi 248.1471, found 248.1471.
4.2.6. Diallyl[4-(trimethylstannyl)phenyl]ethoxysilane
2c. To a solution of 4-(diallylethoxysilyl)iodobenzene
(2.02 g, 5.64 mmol) in THF (15 mL) was added a solution
of i-PrMgCl (5.9 mL, 2 M in THF, 11.8 mmol) at ꢀ30 ꢁC.
The reaction mixture was stirred at ꢀ30 ꢁC for 4 h. To the
resulting Grignard solution was added a solution of
Me3SnCl (11.2 mL, 1 M in THF, 11.2 mmol) at ꢀ30 ꢁC.
The reaction mixture was stirred at ꢀ30 ꢁC for 1 h, and at
room temperature for 19 h. The reaction mixture was then
quenched with H2O and extracted with Et2O. The organic
layer was washed with saturated NaHCO3 and brine, dried
over MgSO4, and concentrated under reduced pressure.
The residue was chromatographed on silica gel (hexane/
EtOAc¼3:1 as eluent) to give 4-(diallylethoxysilyl)phenyl-
4.3. Coupling reaction of molecular building blocks
with coupling partners
1
trimethyltin (2.20 g, 99%): H NMR (CDCl3) d 0.29 (t, J
(Sn–CH3)¼54.5 Hz, 9H), 1.21 (t, J¼6.8 Hz, 3H), 1.93 (d,
J¼8.1 Hz, 4H), 3.76 (q, J¼6.8 Hz, 2H), 4.92 (ddt,
J¼16.2 Hz, 1.6 Hz, 1.1 Hz, 2H), 4.96 (ddt, J¼10.3 Hz,
1.6 Hz, 0.5 Hz, 2H), 5.84 (ddt, J¼16.2 Hz, 10.3 Hz, 8.1 Hz,
2H), 7.52 (d, J¼1.62 Hz, 4H); 13C NMR (CDCl3) d ꢀ9.63 (J
4.3.1. Sonogashira coupling reaction of 1a with tri-
methylsilylacetylene giving 1-diallylethoxysilyl-4-(tri-
methylsilylethynyl)benzene (Table 1, entry 1). To a
mixture of Pd2(dba)3 (82 mg, 0.14 mmol), PPh3 (152 mg,
0.58 mmol), and CuI (50 mg, 0.26 mmol) were added a solu-
tion of trimethylsilylacetylene (545 mL, 3.86 mmol) and 1a
(1000 mg, 3.21 mmol) in Et3N (50 mL). The reaction mix-
ture was stirred at 75 ꢁC for 24 h. The reaction mixture
was then diluted with Et2O, washed with H2O and brine,
dried over MgSO4, and concentrated. The residue was chro-
matographed on silica gel (hexane/EtOAc¼5:1 as eluent) to
give 1-diallylethoxysilyl-4-(trimethylsilylethynyl)benzene
(
119Sn–CH3)¼348.6 Hz, J (117Sn–CH3)¼333.0 Hz), 18.40,
21.21, 59.29, 114.72, 133.20, 133.40, 134.76, 135.27,
144.58. HRMS (FAB+) [MꢀH]+ calcd for C17H27OSiSn
395.0853, found 395.0850.
4.2.7. Diallyl(4-formylphenyl)ethoxysilane 3a. To a solu-
tion of 4-(diallylethoxysilyl)iodobenzene (255 mg,
0.71 mmol) in THF (2 mL) was added a solution of
i-PrMgCl (0.71 mL, 2 M in THF, 1.42 mmol) at ꢀ30 ꢁC.
The reaction mixture was stirred at ꢀ30 ꢁC for 1.5 h to
give 4-(diallylethoxysilyl)phenylmagnesium chloride. To
the Grignard reagent solution was added DMF (110 mL,
1.42 mmol) at ꢀ30 ꢁC. The reaction mixture was stirred at
room temperature for 13 h. The reaction mixture was
quenched with 10% HCl and extracted with Et2O. The or-
ganic layer was washed with saturated NaHCO3 and brine,
dried over MgSO4, and concentrated under reduced pres-
sure. The residue was chromatographed on silica gel
(hexane/EtOAc¼20:1 as eluent) to give diallyl(4-formyl-
phenyl)ethoxysilane (158 mg, 85%): 1H NMR (CDCl3)
d 1.24 (t, J¼6.8 Hz, 3H), 1.96 (ddd, J¼8.1 Hz, 1.4 Hz,
0.8 Hz, 4H), 3.81 (q, J¼6.8 Hz, 2H), 4.91–4.99 (m, 4H),
5.80 (ddt, J¼16.2 Hz, 10.3 Hz, 8.1 Hz, 2H), 7.75 (d,
J¼8.4 Hz, 2H), 7.87 (d, J¼8.4 Hz, 2H), 10.0 (s, 1H); 13C
NMR (CDCl3) d 18.35, 21.06, 59.50, 115.24, 128.58,
132.43, 134.53, 137.07, 143.53, 192.55. HRMS (EI+) M+
calcd for C15H20O2Si 260.1233, found 260.1236.
1
(920 mg, 87%): H NMR (CDCl3) d 0.249 (s, 9H), 1.20 (t,
J¼6.8 Hz, 3H), 1.92 (d, J¼8.1 Hz, 4H), 3.78 (q, J¼6.8 Hz,
2H), 4.88–4.99 (m, 4H), 5.79 (ddt, J¼16.2 Hz, 9.5 Hz,
8.1 Hz, 2H), 7.45 (d, J¼8.1 Hz, 2H), 7.51 (d, J¼8.1 Hz, 2H);
13C NMR (CDCl3) d ꢀ0.074, 18.36, 21.10, 59.34, 95.21,
104.97, 114.92, 124.39, 131.05, 132.81, 133.77, 135.78.
HRMS (FAB+) [MꢀH]+ calcd for C19H27OSi2 327.1600,
found 327.1606.
4.3.2. Suzuki coupling reaction of 1a with phenylboronic
acid giving 4-(diallylethoxysilyl)biphenyl (Table 1, entry
2). To a mixture of 1a (152 mg, 0.49 mmol), Pd(PPh3)4
(16.9 mg, 0.015 mmol), K2CO3 (101 mg, 0.73 mmol), and
phenylboronic acid (71.4 mg, 0.59 mmol) was added toluene
(5 mL). The reaction mixture was stirred at 80 ꢁC for 13 h.
The reaction mixture was then diluted with Et2O, which
was filtered through a Celite plug, and the filter cake was
rinsed with Et2O. The combined filtrates were concentrated
under reduced pressure. The residue was chromatographed
on silica gel (hexane/EtOAc¼10:1 as eluent) to give 4-(dia-
llylethoxysilyl)biphenyl (91.2 mg, 61%): 1H NMR (CDCl3)
d 1.23 (t, J¼6.8 Hz, 3H), 1.97 (d, J¼7.8 Hz, 4H), 3.80 (q,
J¼6.8 Hz, 2H), 4.93 (ddt, J¼9.7 Hz, 1.4 Hz, 1.1 Hz, 2H),
4.2.8. Diallyl(4-aminophenyl)ethoxysilane 3b. To a mixture
of 4-iodoaniline (1316 mg, 6.0 mmol), Pd2(dba)3 (82.4 mg,
0.090 mmol),
and
(o-biphenyl)P(t-Bu)2
(107.6 mg,

11472
Y. Maegawa et al. / Tetrahedron 63 (2007) 11467–11474
4.99 (ddt, J¼15.9 Hz, 1.4 Hz, 0.5 Hz, 2H), 5.86 (ddt,
J¼15.9 Hz, 9.7 Hz, 7.8 Hz, 2H), 7.36 (t, J¼7.0 Hz, 1H),
7.45 (t, J¼7.0 Hz, 2H), 7.60–7.68 (m, 6H); 13C NMR
(CDCl3) d 18.38, 21.24, 59.29, 114.78, 126.46, 127.10,
127.45, 128.73, 133.09, 133.75, 134.49, 140.83, 142.43.
HRMS (FAB+) [MꢀH]+ calcd for C20H23OSi 307.1518,
found 307.1526. Anal. Calcd for C20H24OSi: C, 77.87; H,
7.84. Found: C, 77.62; H, 8.03.
(hexane/EtOAc¼10:1 as eluent) to give 4-diallylethoxy-
silyl-40-methoxybiphenyl (157.3 mg, 89%): 1H NMR
(CDCl3) d 1.23 (t, J¼6.8 Hz, 3H), 1.97 (d, J¼8.1 Hz, 4H),
3.79 (q, J¼6.8 Hz, 2H), 3.86 (s, 3H), 4.93 (ddt, J¼9.5 Hz,
1.4 Hz, 0.8 Hz, 2H), 4.98 (ddt, J¼17.3 Hz, 1.4 Hz, 1.1 Hz,
2H), 5.86 (ddt, J¼17.3 Hz, 9.5 Hz, 8.1 Hz, 2H), 6.99 (d,
J¼8.4 Hz, 2H), 7.55 (d, J¼8.4 Hz, 2H), 7.57 (d, J¼7.6 Hz,
2H), 7.63 (d, J¼7.6 Hz, 2H); 13C NMR (CDCl3) d 18.38,
21.24, 55.22, 59.25, 114.17, 114.73, 125.98, 128.09,
132.94, 133.14, 133.28, 134.47, 141.99, 159.27. HRMS
(FAB+) M+ calcd for C21H26O2Si 338.1702, found
338.1707. Anal. Calcd for C21H26O2Si: C, 74.51; H, 7.74.
Found: C, 74.38; H, 7.87.
4.3.3. Buchwald–Hartwig amination of 1a with diphenyl-
amine giving 4-diallylethoxysilyl-N,N-diphenylaniline
(Table 1, entry 3). To a mixture of 1a (486 mg,
1.56 mmol), Pd2(dba)3 (21.5 mg, 0.023 mmol), (o-biphe-
nyl)P(t-Bu)2 (42.0 mg, 0.14 mmol), NaOt-Bu (225 mg,
2.34 mmol), and diphenylamine (317 mg, 1.87 mmol) was
added toluene (15 mL). The reaction mixture was stirred at
80 ꢁC for 19 h. The reaction mixture was then diluted with
Et2O, which was filtered through a Celite plug, and the filter
cake was rinsed with Et2O. The combined filtrates were con-
centrated under reduced pressure. The residue was chroma-
tographed on silica gel (hexane/EtOAc¼5:1 as eluent) to
give 4-diallylethoxysilyl-N,N-diphenylaniline (384 mg,
62%): 1H NMR (CDCl3) d 1.20 (t, J¼7.0 Hz, 3H), 1.92 (d,
J¼8.1 Hz, 4H), 3.77 (q, J¼7.0 Hz, 2H), 4.90–5.00 (m,
4H), 5.77–5.93 (m, 2H), 7.03 (d, J¼8.1 Hz, 2H), 7.02–
7.13 (m, 6H), 7.25 (d, J¼8.1 Hz, 2H), 7.28 (d, J¼8.1 Hz,
2H), 7.41 (d, J¼8.1 Hz, 2H); 13C NMR (CDCl3) d 18.40,
21.34, 59.17, 114.58, 121.69, 123.28, 124.95, 127.30,
129.27, 133.37, 134.95, 147.33, 149.19. HRMS (FAB+)
[M+H]+ calcd for C26H30ONSi 400.2097, found 400.2093.
4.3.6. Suzuki coupling reaction of 1c with 4-methoxyphe-
nylboronic acid giving 4-diallylethoxysilyl-40-methoxybi-
phenyl (Table 1, entry 6). To a mixture of 4-(diallyl-
ethoxysilyl)phenyl triflate (150 mg, 0.39 mmol), Pd(PPh3)4
(13.6 mg, 0.012 mmol), K2CO3 (81.7 mg, 0.59 mmol), and
4-methoxyphenylboronic acid (71.9 mg, 0.47 mmol) was
added toluene (5 mL). The reaction mixture was stirred at
80 ꢁC for 16 h. The reaction mixture was then diluted with
Et2O, which was filtered through a Celite plug, and the filter
cake was rinsed with Et2O. The combined filtrates were
concentrated under vacuum to give a residue. The residue
was chromatographed on silica gel (hexane/EtOAc¼10:1
as eluent) to give 4-diallylethoxysilyl-40-methoxybiphenyl
(101.7 mg, 76%).
4.3.7. Grignard cross-coupling of 2a with 2-bromopyri-
dine giving 2-[4-(diallylethoxysilyl)phenyl]pyridine
(Table 1, entry 7). To a solution of 1b (240 mg,
0.67 mmol) in THF (2 mL) was added a solution of i-PrMgCl
(0.70 mL, 2 M in THF, 1.40 mmol) at ꢀ30 ꢁC. The reaction
mixturewas stirredatꢀ30 ꢁC for2 h to give4-(diallylethoxy-
silyl)phenylmagnesium chloride. To a solution of Pd2(dba)3
(25.6 mg, 0.028 mmol), dppf (15.5 mg, 0.028 mmol), and
2-bromopyridine (54.4 mL, 0.56 mmol) in THF (3 mL) was
added 4-(diallylethoxysilyl)phenylmagnesium chloride at
ꢀ30 ꢁC. The reaction mixture was stirred at ꢀ30 ꢁC for
17 h. The reaction mixture was then quenched with saturated
NH4Cl and extracted with Et2O. The organic layer was dried
over MgSO4 and concentrated. The residue was chromato-
graphed on silica gel (hexane/EtOAc¼3:1 as eluent) to give
2-[4-(diallylethoxysilyl)phenyl]pyridine (158 mg, 91%):
1H NMR (CDCl3) d 1.22 (t, J¼7.0 Hz, 3H), 1.97 (d,
J¼8.4 Hz, 4H), 3.79 (q, J¼7.0 Hz, 2H), 4.92 (ddt,
J¼10.0 Hz, 1.9 Hz, 0.8 Hz, 2H), 4.98 (ddt, J¼16.2 Hz,
1.9 Hz, 1.4 Hz, 2H), 5.84 (ddt, J¼16.2 Hz, 10.0 Hz,
8.4 Hz, 2H), 7.33 (dt, J¼5.1 Hz, 0.5 Hz, 1H), 7.69 (d,
J¼8.4 Hz, 2H), 7.73–7.80 (m, 2H), 8.00 (d, J¼8.4 Hz, 2H),
8.71 (dt, J¼5.1 Hz, 0.8 Hz, 1H); 13C NMR (CDCl3)
d 18.35, 21.16, 59.30, 114.95, 120.62, 122.25, 126.00,
132.96, 134.55, 135.82, 136.69, 140.55, 149.68, 157.20.
HRMS (FAB+) [M+H]+ calcd for C19H24ONSi 310.1627,
found 310.1635. Anal. Calcd for C19H23ONSi: C, 73.74; H,
7.49; N, 4.53. Found: C, 74.19; H, 7.84; N, 4.02.
4.3.4. Sonogashira coupling reaction of 1b with 2-methyl-
3-butyn-2-ol giving 1-diallylethoxysilyl-4-(3-hydroxy-3-
methyl-1-butynyl)benzene (Table 1, entry 4). To a mixture
of 1b (130 mg, 0.36 mmol), PdCl2(PPh3)2 (10.2 mg,
0.015 mmol), and CuI (2.8 mg, 0.015 mmol) were added
THF (3 mL), Et3N (3 mL), and 2-methyl-3-butyn-2-ol
(42 mL, 0.43 mmol). The reaction mixture was stirred at
50 ꢁC for 1.5 h. The reaction mixture was then diluted
with Et2O, washed with H2O and brine, dried over
MgSO4, and concentrated. The residue was chromato-
graphed on silica gel (hexane/EtOAc¼5:1 as eluent) to
give 1-diallylethoxysilyl-4-(3-hydroxy-3-methyl-1-buty-
1
nyl)benzene (114 mg, 100%): H NMR (CDCl3) d 1.20 (t,
J¼7.0 Hz, 3H), 1.62 (s, 6H), 1.92 (d, J¼8.1 Hz, 4H), 2.09
(s, 1H), 3.76 (q, J¼7.0 Hz, 2H), 4.89–4.96 (m, 4H), 5.71–
5.87 (m, 2H), 7.41 (d, J¼8.1 Hz, 2H), 7.51 (d, J¼8.1 Hz,
2H); 13C NMR (CDCl3) d 18.33, 21.08, 31.42, 59.32,
65.57, 82.03, 94.71, 114.91, 124.02, 130.74, 132.79,
133.81, 135.44. HRMS (FAB+) [MꢀH]+ calcd for
C19H25O2Si 313.1624, found 313.1624.
4.3.5. Suzuki coupling reaction of 1b with 4-methoxyphe-
nylboronic acid giving 4-diallylethoxysilyl-40-methoxybi-
phenyl (Table 1, entry 5). To a mixture of 1b (187 mg,
0.52 mmol), Pd(PPh3)4 (18.1 mg, 0.016 mmol), K2CO3
(108 mg, 0.78 mmol), and 4-methoxyphenylboronic acid
(95.2 mg, 0.63 mmol) was added toluene (5 mL). The reac-
tion mixture was stirred at 80 ꢁC for 13 h. The reaction mix-
ture was then diluted with Et2O, which was filtered through
a Celite plug, and the filter cake was rinsed with Et2O. The
combined filtrates were concentrated under vacuum to give
a residue. The residue was chromatographed on silica gel
4.3.8. Suzuki coupling reaction of 2b with 4-iodoanisole
giving 4-diallylethoxysilyl-40-methoxybiphenyl (Table 1,
entry 8). To a mixture of 2b (200 mg, 0.558 mmol), 4-iodo-
anisole (109 mg, 0.465 mmol), silver carbonate (154 mg,
0.558 mmol), and Pd(PPh3)4 (16 mg, 0.014 mmol) was

Y. Maegawa et al. / Tetrahedron 63 (2007) 11467–11474
11473
added 5 mL of THF. The reaction mixture was stirred at
60 ꢁC for 24 h, diluted with ether, and filtered through a Cel-
ite plug. The filter cake was rinsed with ether. The combined
filtrates were concentrated in vacuo and the residue was
chromatographed on silica gel (hexane/ethyl acetate¼3:1)
to give 4-diallylethoxysilyl-40-methoxybiphenyl (134 mg,
89%).
(242 mg, 77%): 1H NMR (CDCl3) d 1.20 (t, J¼6.8 Hz, 3H),
1.91 (d, J¼8.1 Hz, 4H), 2.32 (s, 3H), 3.95 (q, J¼6.8 Hz,
2H), 4.90 (dd, J¼10.0 Hz, 1.1 Hz, 2H), 4.96 (dd,
J¼16.5 Hz, 1.1 Hz, 2H), 5.70 (br, 1H), 5.85 (ddt,
J¼16.5 Hz, 10.0 Hz, 8.1 Hz, 2H), 6.98 (d, J¼8.4 Hz, 2H),
7.04 (d, J¼8.6 Hz, 2H), 7.11 (d, J¼8.6 Hz, 2H), 7.43 (d,
J¼8.4 Hz, 2H); 13C NMR (CDCl3) d 18.40, 20.72, 21.37,
59.11, 114.47, 115.13, 119.95, 124.58, 129.85, 131.71,
133.50, 135.37, 139.21, 145.68. HRMS (EI+) M+ calcd for
C21H27ONSi 337.1862, found 337.1863.
4.3.9. Migita–Kosugi–Stille coupling of 2c with 2-bromo-
pyridine giving 2-[4-(diallylethoxysilyl)phenyl]pyridine
(Table 1, entry 9). A mixture of 74.8 mg (0.473 mmol) of
2-bromopyridine, 205 mg (0.521 mmol) of 2c, 31.9 mg
(0.0276 mmol) of Pd(PPh3)4, 64.6 mg (1.52 mmol) of LiCl,
and toluene (3 mL) was refluxed for 1 h, diluted with diethyl
ether, and treated successively with water. The reaction mix-
ture was extracted with Et2O, washed with water, saturated
aqueous NaHCO3, and aqueous sodium chloride. The or-
ganic layer was dried over MgSO4 and concentrated. The res-
idue was chromatographed on silica gel (hexane/EtOAc¼3:1
as eluent) to give the desired 2-[4-(diallylethoxysilyl)phe-
nyl]pyridine (73.5 mg, 50%) with (diallylethoxysilyl)ben-
zene (7.9 mg, 7%) and 4,40-bis(diallylethoxysilyl)biphenyl
(10.9 mg, 1%) as byproducts.
4.4. Preparation of functional sol–gel precursors with
molecular building blocks
4.4.1. (S)-5,50-Bis[4-(diallylethoxysilyl)phenylethynyl]-
2,20-bis(diphenylphosphinyl)-1,10-binaphthyl 4a. To a
solution of (S)-5,50-bis(trimethylsilylethynyl)-2,20-bis(di-
phenylphosphinyl)-1,10-binaphthyl (301 mg, 0.355 mmol) in
dichloromethane (12 mL) was added tetrabutylammonium
fluoride (0.78 mL, 0.781 mmol) and the mixture was stirred
at room temperature for 2 h. Solvent was removed under
reduced pressure and the residue was chromatographed on
silica gel (hexane/EtOAc¼1:3) to give 218.4 mg (88%) of
(S)-5,50-diethynyl-2,20-bis(diphenylphosphinyl)-1,10-bina-
phthyl: 1H NMR (CDCl3) d 3.46 (s, 2H), 6.74–6.66 (m, 4H),
7.43–7.21 (m, 16H), 7.60–7.49 (m, 4H), 7.74–7.66 (m, 4H),
8.43–8.39 (dd, J¼8.6 Hz, 2.4 Hz, 2H); 31P NMR (CDCl3)
d 28.48. To a solution of 4-(diallylethoxysilyl)iodobenzene
(211.1 mg, 0.589 mmol), PdCl2(PPh3)2 (17.5 mg, 0.025-
mmol), and CuI (4.8 mg, 0.025 mmol) in benzene (1 mL)
was added (S)-5,50-diethynyl-2,20-bis(diphenylphosphinyl)-
1,10-binaphthyl (166.8 mg, 0.237 mmol) in benzene (8 mL)
and the mixture was stirred at 50 ꢁC for 23 h. Solvent was re-
moved under reduced pressure and the residuewas chromato-
graphed on silica gel (hexane/EtOAc¼1:1) to give 201.2 mg
(71%) of (S)-5,50-bis[4-(diallylethoxysilyl)phenylethynyl]-
2,20-bis(diphenylphosphinyl)-1,10-binaphthyl: [a]2D0 ꢀ225
4.3.10. Wittig olefination of 3a with methyltriphenyl-
phosphonium iodide giving 4-(diallylethoxysilyl)styrene
(Table 1, entry 10). To a mixture of PPh3Me+Iꢀ (970 mg,
2.4 mmol) and KOt-Bu (269 mg, 2.4 mmol) was added tolu-
ene (15 mL). The reaction mixture was stirred at 80 ꢁC for
2 h. Tothereactionmixturewasaddeda solutionof4-(diallyl-
ethoxysilyl)benzaldehyde (250 mg, 0.96 mmol) in toluene
(5 mL) at 50 ꢁC. The reaction mixture was stirred at 50 ꢁC
for 12 h. The reaction mixture was then quenched with
H2O and extracted with Et2O. The organic layer was washed
with brine, dried over MgSO4, and concentrated. The residue
was chromatographed on silica gel (hexane/EtOAc¼3:1 as
eluent) to give 4-(diallylethoxysilyl)styrene (233.2 mg,
1
1
94%): H NMR (CDCl3) d 1.20 (t, J¼7.0 Hz, 3H), 1.93
(c 0.60, CHCl3); H NMR (CDCl3) d 1.24 (t, J¼6.8 Hz,
(ddd, J¼8.1 Hz, 1.4 Hz, 1.1 Hz, 4H), 3.76 (q, J¼7.0 Hz,
2H), 4.90 (ddt, J¼10.3 Hz, 1.6 Hz, 1.1 Hz, 2H), 4.96 (ddt,
J¼16.2 Hz, 1.6 Hz, 1.4 Hz, 2H), 5.27 (dd, J¼11.1 Hz,
0.8 Hz, 1H), 5.79 (dd, J¼17.8 Hz, 0.8 Hz, 1H), 5.82 (ddt,
J¼16.2 Hz, 10.3 Hz, 8.1 Hz, 2H), 6.73 (dd, J¼17.8 Hz,
11.1 Hz, 1H), 7.41 (d, J¼8.1 Hz, 2H), 7.54 (d, J¼8.1 Hz,
2H); 13C NMR (CDCl3) d 18.36, 21.21, 59.25, 114.55,
114.75, 125.54, 133.05, 134.27, 134.62, 136.72, 138.81.
HRMS (FAB+) [M+H]+ calcd for C16H23OSi 259.1518,
found 259.1512.
6H), 1.97 (d, J¼8.1 Hz, 8H), 3.80 (q, J¼6.8 Hz, 4H), 4.93–
5.01 (m, 8H), 5.76–5.89 (m, 4H), 6.73 (d, J¼4.3 Hz, 4H),
7.25–7.45 (m, 16H), 7.52–7.62 (m, 12H), 7.70–7.78 (m,
4H), 8.53–8.49 (dd, J¼8.6, 2.4 Hz, 2H); 13C NMR (CDCl3)
d 18.38 (OCH2CH3), 21.11 (CH2–CH]CH2), 59.37
(OCH2CH3), 88.25, 94.57 (ethynyl C); 31P NMR (CDCl3)
d 28.68. HRMS (FAB+) [M+H]+ calcd for C76H69O4Si2P2
1163.4210, found 1163.4209.
4.4.2. N,N0-Bis[4-(diallylethoxysilyl)phenyl]benzidine 4b.
To a mixture of 4-(diallylethoxysilyl)aniline (505 mg,
2.0 mmol) and 4,40-diiodobiphenyl (378 mg, 0.94 mmol),
Pd2(dba)3 (25 mg, 0.027 mmol), (o-biphenyl)P(t-Bu)2
(49.5 mg, 0.17 mmol), and NaOt-Bu (267 mg, 2.8 mmol)
was added toluene (7 mL). The reaction mixture was stirred
at room temperature for 18 h. The reaction mixture was di-
luted with Et2O, which was filtered through a Celite plug,
and the filter cake was rinsed with Et2O. The combined
filtrates were concentrated under reduced pressure. The
residue was chromatographed on silica gel (hexane/
EtOAc¼3:1 as eluent) to give N,N0-bis[4-(diallylethoxy-
4.3.11. Buchwald–Hartwig amination of 3b with 4-iodo-
toluene giving N-[4-(diallylethoxysilyl)phenyl](4-methyl-
phenyl)amine (Table 1, entry 11). To a mixture of
4-(diallylethoxysilyl)aniline (254 mg, 1.0 mmol), Pd2(dba)3
(4.3 mg,
0.0047 mmol),
4-iodotoluene
(204 mg,
0.94 mmol), (o-biphenyl)P(t-Bu)2 (8.4 mg, 0.028 mmol),
and NaOt-Bu (135 mg, 1.4 mmol) was added toluene
(7 mL). The reaction mixturewas stirred at room temperature
for 18 h. The reaction mixture was diluted with Et2O, which
was filtered through a Celite plug, and the filter cake was
rinsed with Et2O. The combined filtrates were concentrated
under vacuum to give a residue. The residue was chromato-
graphed on silica gel (hexane/EtOAc¼3:1 as eluent) to
giveN-[4-(diallylethoxysilyl)phenyl](4-methylphenyl)amine
1
silyl)phenyl]benzidine (430 mg, 72%): H NMR (CDCl3)
d 1.21 (t, J¼7.0 Hz, 6H), 1.93 (d, J¼8.1 Hz, 8H), 3.76 (q,
J¼7.0 Hz, 4H), 4.89–5.00 (m, 8H), 5.78–5.94 (m, 6H),
7.08 (d, J¼8.6 Hz, 4H), 7.17 (d, J¼8.6 Hz, 4H), 7.48 (d,

11474
Y. Maegawa et al. / Tetrahedron 63 (2007) 11467–11474
J¼8.6 Hz, 4H), 7.50 (d, J¼8.6 Hz, 4H); 13C NMR (CDCl3)
d 18.41, 21.37, 59.17, 114.57, 116.0, 119.11, 125.54, 127.38,
133.43, 134.16, 135.42, 140.93, 144.77. HRMS (FAB+) M+
calcd for C40H48O2N2Si2 644.3254, found 644.3246.
2. (a) Shea, K. J.; Loy, D. A.; Webster, O. W. Chem. Mater. 1989,
1, 572–574; (b) Shea, K. J.; Loy, D. A.; Webster, O. W. J. Am.
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Cerveau, G.; Chappellet, S.; Corriu, R. J. P.; Dabiens, B.;
Bideau, J. L. Organometallics 2002, 21, 1560–1564; (g)
Nathalie, B.; Frederic, L.; Benoit, P.; Genevieve, C.; Corriu,
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Guan, S.; Ohsuna, T.; Terasaki, O. Nature 2002, 416, 304–
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4.4.3. Bis[4-[4-(diallylethoxysilyl)phenylethynyl]phenyl]-
acetylene 4c. To a mixture of 1b (75.7 mg, 0.21 mmol),
PdCl2(PPh3)2 (2.97 mg, 0.0042 mmol), CuI (0.8 mg,
0.0042 mmol),
and
4,40-(diethynylphenyl)acetylene
(34.5 mg, 0.15 mmol) were added THF (5 mL) and Et3N
(1 mL). The reaction mixture was stirred at 50 ꢁC for 15 h.
The reaction mixture was diluted with Et2O and then the or-
ganic layer was washed with brine, dried over MgSO4, and
concentrated under reduced pressure. The residue was chro-
matographed on silica gel (hexane/EtOAc¼10:1 as eluent)
to give bis[4-[4-(diallylethoxysilyl)phenylethynyl]phenyl]-
acetylene (68.1 mg, 94%): 1H NMR (CDCl3) d 1.23 (t,
J¼7.0 Hz, 6H), 1.95 (d, J¼8.1 Hz, 8H), 3.79 (q, J¼7.0 Hz,
4H), 4.91–4.99 (m, 8H), 5.82 (ddt, J¼16.2 Hz, 9.7 Hz,
8.1 Hz, 4H), 7.52 (s, 8H), 7.53 (d, J¼8.1 Hz, 4H), 7.58 (d,
J¼8.1 Hz, 4H); 13C NMR (CDCl3) d 18.38, 21.11, 59.37,
89.96, 90.98, 91.33, 114.96, 122.89, 123.19, 124.27,
130.72, 131.54, 131.59, 132.81, 133.94, 135.85. HRMS
(FAB+) [M+H]+ calcd for C46H47O2Si2 687.3115, found
687.3105. Anal. Calcd for C46H46O2Si2: C, 80.42; H, 6.75.
Found: C, 80.02; H, 6.31.
4. Murata, M.; Ishikura, M.; Nagata, M.; Watanabe, S.; Masuda,
Y. Org. Lett. 2002, 4, 1843–1845.
Acknowledgements
5. Transformation of the triethoxysilyl group to the allylsilyl
group using allylmagnesium bromide gave the corresponding
diallylethoxysilyl compounds with no observed formation of
triallylsilyl compounds.
6. Knochel, P.; Dohle, W.; Gommermann, N.; Kneisel, F. F.;
Kopp, F.; Korn, T.; Sapountzis, I.; Vu, V. A. Angew. Chem.,
Int. Ed. 2003, 42, 4302–4320.
This work was supported by a Grant-in-Aid for Scientific
Research from the Ministry of Education, Culture, Sports,
Science, and Technology of Japan, and CREST, Japan
Science and Technology Agency (JST), Japan. We thank
Dr. Shinji Inagaki and Prof. Kiyomi Kakiuchi for the gener-
ous support.
7. Comins, D. L.; Dehghani, A. D.; Foti, C. J.; Joseph, S. P. Org.
Synth. 1997, 74, 77–80.
8. Manoso, A. S.; DeShong, P. J. Org. Chem. 2001, 66, 7449–
7455.
Supplementary data
9. Wolfe, J. P.; Tomori, H.; Sadighi, J. P.; Yin, J.; Buchwald, S. L.
J. Org. Chem. 2000, 65, 1158–1174.
Supplementary data associated with this article can be found
in the online version, at doi:10.1016/j.tet.2007.08.011.
10. Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457–2483.
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