Rigid rod molecules containing two Si(OMe)3 or SiMe(OMe)2 groups for hybrid materials synthesis

Article abstract of DOI:10.1016/S0022-328X(01)00668-4

The synthesis of new bis(trimethoxysilyl) and bis(dimethoxymethylsilyl)arene compounds containing rigid organic groups such as stilbenyl, diphenylacetylene or diphenylbut-1,3-diyne is reported. The Heck type reaction constituted a convenient route to these compounds, since this coupling reaction appeared compatible with the presence of Si(OR)₃ groups.

Full text of DOI:10.1016/S0022-328X(01)00668-4

Journal of Organometallic Chemistry 626 (2001) 92–99
www.elsevier.nl/locate/jorganchem
Rigid rod molecules containing two Si(OMe)3 or SiMe(OMe)2
groups for hybrid materials synthesis
Genevie`ve Cerveau *, Sabrina Chappellet, Robert J.P. Corriu*, Bertrand Dabiens
Laboratoire de Chimie Mole´culaire et Organisation du Solide, UMR 5637, Uni6ersite´ Montpellier II, Place E. Bataillon,
34095 Montpellier Cedex 5, France
Received 16 November 2000; accepted 22 December 2000
Abstract
The synthesis of new bis(trimethoxysilyl) and bis(dimethoxymethylsilyl)arene compounds containing rigid organic groups such
as stilbenyl, diphenylacetylene or diphenylbut-1,3-diyne is reported. The Heck type reaction constituted a convenient route to
these compounds, since this coupling reaction appeared compatible with the presence of Si(OR)3 groups. © 2001 Elsevier Science
B.V. All rights reserved.
Keywords: Trimethoxysilanes; Methyldimethoxysilanes; Synthesis; Heck reaction
ClSi(OMe)3 also allows the preparation of
trimethoxysilyl derivatives [4,5] via silylation of
organometallic intermediates or via an extension of the
Calas–Dunogue`s silylation reaction [6]. The cross-cou-
pling reaction of the stable (triisopropyloxysilyl)methyl
Grignard reagent with organic bromides [7] affords a
facile access to trifunctional organosilicon compounds.
Other methods of preparation of trifunctional silicon-
containing molecules include silylation with HSiCl3–
NEt3 [8], triethoxysilylation of aromatic iodides [9],
nucleophilic substitution of tetramethoxysilane by an
organometallic precursor [10]. We were also interested
in the synthesis of bis(dimethoxymethysilyl) precursors.
In the same way, very few methods have been described
in literature concerning the methyldialkoxysilylation of
aromatic compounds: (i) nucleophilic substitution of an
aromatic Grignard reagent on methyltrialkoxysilane
[11]; (ii) the methanolysis of methylaryldichlorosilanes
in the presence of pyridine or triethylamine [12], or
catalyzed by PPh3CuH [13]; (iii) the nucleophilic substi-
tution by sodium methoxide on a bulky alkoxysilane
through the elimination of phenolate as the leaving
group [14]; (iv) the methyldiethoxysilylation of 1,4-di-
bromobenzene [15,16].
1. Introduction
Over the past few years, we have focused our interest
on the study of monophasic organic–inorganic hybrid
materials obtained by sol–gel hydrolysis–polyconden-
sation of organically polysubstituted alkoxysilanes [1].
Our interest in the control of the morphology of a
material from the molecular level led us to study solids
with various structural features, obtained from tri-
alkoxysilylated precursors bearing two Si(OR)3 groups
[1]. We were particularly interested by rigid precursors
with organic groups of different size. Whereas a variety
of synthetic methods can be used for the trimethylsily-
lation of organic molecules [2], only a few ways for the
preparation of trihalogenosilyl or trialkoxysilylderiva-
tives RSiX3 (X=Cl, OR…) have been developed. The
trihalogenosilyl or trialkoxysilylderivatives are difficult
intermediates in the synthesis of precursors because of
the high reactivity of the ꢀSiX3 (X=Cl, OR) groups
towards H2O and other nucleophiles which make them
incompatible with many experimental procedures of
synthesis and separation. The hydrosilylation reaction
[3] constitutes a general and selective route to trifunc-
tional silicon compounds from olefins. The reaction of
We report here an extension of the Heck type reac-
tion [17] permitting the synthesis of bis(trimethoxysi-
* Corresponding author. Fax: +33-4-67143852.
E-mail address: gcerveau@crit.univ-montp2-fr (G. Cerveau).
lyl)arene
and
bis(dimethoxymethylsilyl)arene
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00668-4

G. Cer6eau et al. / Journal of Organometallic Chemistry 626 (2001) 92–99
93
coupling reactions of halogenoarenes with styrene
derivatives (Heck reaction) [17] are a convenient route
to obtaining of stilbene derivatives. The extension of
Heck reaction [18,19] is a useful reaction for the synthe-
sis of acetylenic compounds under mild conditions. The
new compounds presented here were synthesized using
this coupling reaction which appeared very convenient
for obtaining reactive trimethoxy and dimethoxysilyl
derivatives.
derivatives containing rigid organic groups, such as
stilbenyl 1a, 1b, diphenylacetylene 2a, 2b or diphenyl-
but-1,3-diyne 3a, 3b (Table 1). The Pd-catalyzed cross-
Table 1
2. Results
2.1. Synthesis of stilbene deri6ati6es 1a and 1b
Compound 4,4%-bis(trimethoxysilyl)stilbene (1a) was
obtained by Pd-catalyzed cross-coupling reaction of
4-(trimethoxysilyl)styrene (8a) [20] with 4-bromo-1-
(trimethoxysilyl)benzene (9a) [21] (Heck reaction) [17].
The reaction was carried out in toluene in the presence
of palladium(II) acetate, triethylamine and tri-ortho-
tolylphosphine (Scheme 1). 4,4%-Bis(trimethoxysi-
lyl)stilbene (1a) was isolated in almost quantitative
yield. Attempts to direct silylation of 4,4%-dibromostil-
bene with chlorotrimethoxysilane in the presence of
magnesium according to the extension of Calas–
Dunogue`s reaction [5] was not complete and led to a
mixture of products.
Compound
4,4%-bis(dimethoxymethylsilyl)stilbene
(1b) was obtained using the same reaction conditions by
coupling 4-(dimethoxymethylsilyl)styrene (8b) and 4-
bromo-1-(dimethoxymethylsilyl)benzene (9b) (Scheme
1). Compound 8b was obtained by silylation reaction of
4-bromostyrene 10 with chlorodiisopropyloxymethylsi-
lane 12b% using the extension of Calas–Dunogue`s reac-
tion [6], which gave 13, and was followed by exchange
of alkoxyde groups (Scheme 2). In a same way, 9b was
obtained starting from 1,4-dibromobenzene (11)
(Scheme 2). Chlorodiisopropyloxymethylsilane 12b% was
prepared by treatment of one equivalent of methyl-
trichlorosilane with 2.2 equivalents of dry isopropanol
in pentane.
2.2. Synthesis of diphenylacetylene compounds 2a and
2b
Compound 4,4%-bis(trimethoxysilyl)diphenylacetylene
(2a) was obtained by coupling reaction of 4-iodo-1-
(trimethoxysilyl)benzene (15a) with the alkyne 4-
(trimethoxysilyl)phenylacetylene (16a) in the presence
Scheme 1.
of
a
catalytic amount of bis(triphenylphos-
phine)palladium dichloride–cuprous iodide in triethyl-
amine [18] (Scheme 3). An almost quantitative yield of
4,4%-bis(trimethoxysilyl)diphenylacetylene (2a) was re-
covered. The direct silylation of 4,4%-dibromodiphenyl-
acetylene with chlorotrimethoxysilane in the presence
Scheme 2.

94
G. Cer6eau et al. / Journal of Organometallic Chemistry 626 (2001) 92–99
was finally obtained from 17a% by exchange reaction of
alkoxyde groups in the presence of a catalytic amount
of p-toluenesulfonic acid in anhydrous methanol
(Scheme 4). Compound 15b was synthesized following
the same route (Scheme 4). [4-(Trimethoxysi-
lyl)phenyl]acetylene (16a) and [4-(dimethoxymethylsi-
Scheme 3.
lyl)phenyl]acetylene
(16b)
were
obtained
by
alkoxysilylation of (4-bromophenyl)acetylene (18) fol-
lowing the extension of Calas–Dunogue`s reaction.
Compound 18 was prepared according to literature
procedure [22]. The trimethylsilyl protecting group [23]
was then easily removed by treatment of 19a and 19b
with K2CO3 in anhydrous methanol [22,24] (Scheme 5).
Scheme 4.
2.3. Synthesis of diphenylbut-1,3-diyne deri6ati6es 3a,
3b and 5
4,4%-Bis(trimethoxysilyl)diphenylbut-1,3-diyne
(3a)
and 4,4%-bis(dimethoxymethylsilyl)diphenylbut-1,3-
diyne (3b) were obtained by homocondensation of 16a
and 16b, respectively, in the presence of tetrakis-
(triphenylphosphine)palladium(0), cuprous iodide and
chloroacetone in triethylamine [25,26] (Scheme 6).
Bis[(triisopropyloxysilylmethyl)dimethylsilyl]but - 1,3-
diyne (5) was prepared from 20 in the same conditions.
The synthesis of 20 has been achieved according to
Scheme 7. Dimethylchlorosilane was treated by the
(triisopropyloxysilyl)methyl Grignard reagent [7] to give
21, which was converted into chloro compound 22 by
reaction with PdCl2 in CCl4 [27]. The addition of the
monoacetylene Grignard reagent to 22 yielded the in-
termediate 20.
Scheme 5.
Scheme 6.
Scheme 7.
Scheme 8.
2.4. Synthesis of
1,4-bis[2-(4-trimethoxysilylphenyl)ethynyl]benzene (4)
The coupling reaction of two equivalents of the
acetylenic compound 16a with one equivalent of 1,4-di-
iodobenzene in the presence of a catalytic amount of
bis(triphenylphosphine)palladium dichloride–cuprous
iodide in triethylamine [18] afforded 4 in almost quanti-
tative yield (Scheme 8).
of magnesium (extension of Calas–Dunogue`s reaction
[5]) was not complete and led to a mixture of products.
Similarly
4,4%-(dimethoxymethylsilyl)diphenylace-
2.5. Synthesis of arene deri6ati6es 6 and 7
tylene (2b) was prepared following the same reaction
starting from 4-iodo-1-(dimethoxymethylsilyl)benzene
(15b) and 4-(dimethoxymethylsilyl)phenylacetylene
(16b) (Scheme 3).
The synthesis of compounds 15a, 15b, 16a, 16b has
been achieved. The 4-iodo-1-(trimethoxysilyl)benzene
(15a) was obtained starting from 4-bromo-1-(triiso-
propyloxysilyl) benzene (14a%) which bears the bulky
isopropyloxysilyl group [21]. The corresponding Grig-
nard reagent was easily prepared [21] and reacted with
iodine to give 17a% in 88% yield. The compound 15a
The synthesis of 1,4-(bis(dimethoxymethylsilyl)-
benzene (6) and 4,4%-bis(dimethoxymethylsilyl)biphenyl
(7) was investigated using a method reported in litera-
ture [16] in the case of the preparation of bis(alkyl-
diethoxysilyl)benzene. This reaction, which consisted
in the dimethoxymethylsilylation of 1,4-dibromoben-
zene or 4,4-dibromobiphenyl in the presence of magne-
sium and methyltrimethoxysilane in THF, was not
selective and afforded a mixture of unreacted dibro-
mide, the product of monosubstitution and the ex-

G. Cer6eau et al. / Journal of Organometallic Chemistry 626 (2001) 92–99
95
pected compound. Compounds 6 and 7 were isolated in
low yields (25 and 10%, respectively) after distillation.
Another route to 7 was developed which consisted in
an extension of the Calas–Dunogue`s reaction [5], using
chlorodiisopropyloxymethylsilane 12b% (Scheme 9). The
intermediate 23 was obtained in 35% yield and was
converted into 7 in 85% yield.
sion was filtered at room temperature (r.t.) under
silanized silica. The solvent was pumped off under
vacuum and a yellow powder was obtained in quantita-
tive yield (2.97 g, 6.7 mmol). 1H-NMR (CDCl3, l): 7.69
(4H, d), 7.58 (4H, d), 7.20 (2H, s), 3.65 (18H, s).
13C-NMR (CDCl3, l): 55.1, 111.9, 114.0, 125.2, 129.6,
139.7. 29Si-NMR (CDCl3, l): −55.4. Anal. Calc. for
C20H28O6Si2: C, 57.12; H, 6.71. Found: C, 57.86; H,
6.48%.
3. Conclusions
4.2. 4,4%-Bis(dimethoxymethylsilyl)stilbene (1b)
The Heck type reaction constitutes a convenient
route to rigid bis(trimethoxy) or bis(dimethoxy) silanes.
Such compounds constitute an interesting class of prod-
ucts since rigid molecules have been reported as precur-
sors to nanostructured hybrid materials, which exhibit
a self organization of the organic units in the solid. This
arrangement has been detected by X-ray at a short
range and by birefringence experiments for mesogenic
properties [5,28,29]. The organization is important for
possible physical and chemical properties. The experi-
mental conditions and the reagents involved in the
synthetic pathway appeared to be compatible with the
presence of Si(OR)3 groups.
A mixture of 4-(dimethoxymethylsilyl)styrene (8b)
(1.52 g, 7.2 mmol) and 4-bromo-1-(diisopropy-
loxymethylsilyl)benzene (9b) (1.9 g, 7.2 mmol) was dis-
solved in toluene (15 ml). Palladium acetate (81 mg,
3.6×10−4 mol), dry triethylamine (4.39 g, 43.2 mmol)
and tri-orthotolylphosphine (TOP) (438 mg, 1.5×10−3
mol) were added all at once successively. The suspen-
sion was heated during 24 h at 120°C. The resulting
suspension was filtered at r.t. over silanized silica. The
solvent was pumped off under vacuum and a yellow
powder was recovered. It was recrystallized in pentane.
4,4%-bis(dimethoxymethylsilyl)stilbene (1b) (1.54 g, 3.96
1
mmol) was obtained (yield 55%). H-NMR (CDCl3, l):
7.65 (4H, d), 7.61 (4H, d),7.19 (2H, s), 3.60 (12H, s),
0.39 (3H, s).
4. Experimental
4.3. 4-(Dimethoxymethylsilyl)styrene (8b)
All reactions were carried out under Ar using a
vacuum line and Schlenk techniques. Solvents were
dried and distilled just before use. Melting points were
determined with a Gallenkamp apparatus and are un-
corrected. IR data were obtained on a Perkin–Elmer
A solution of 4-bromostyrene (10) (10 g, 55 mmol) in
anhydrous THF (40 ml), was added dropwise to a
suspension of magnesium chips (2.07 g, 86.4 mmol) and
chloromethyldiisopropyloxysilane (12b%) (17.03 g, 109
mmol) in anhydrous THF (50 ml) at 0°C. The suspen-
sion was then stirred 24 h at 20°C. The solvent was
pumped off under vacuum (2 mBar), the reaction mix-
ture was then taken up with dry pentane (200 ml). The
suspension was filtered. The filtrate was evaporated
under vacuum (2 mBar) to give an oil which was
distilled. (b.p. 70–75°C, 5×10−2 mBar) (8.23 g, 31
mmol) of 4-(diisopropyloxymethylsilyl)styrene (13) were
obtained as a colorless oil in 56% yield. 1H-NMR
(CDCl3, l): 7.65 (2H, d), 7.44 (2H, d), 6.75 (1H, dd),
5.80 (1H, d), 5.30 (1H, d), 4.22 (2H, hept), 1.22 (12H,
d), 0.39 (3H, s).
1
1600FTIR spectrophotometer. The H- and 13C-NMR
spectra were recorded on a Bruker DPX-200 spectrom-
eter and the 29Si-NMR spectra were recorded on a
Bruker WP-200 SY spectrometer. Chemical shifts are
given relative to tetramethylsilane. Elemental analyses
were carried out by the ‘Service Central de Micro-
Analyse du CNRS’.
4.1. 4,4%-Bis(trimethoxysilyl)stilbene (1a)
A mixture of 4-(trimethoxysilyl)styrene (8a) [20] (1.5
g, 6.7 mmol) and 4-bromo-1-(trimethoxysilyl)benzene
(9a) [21] (1.85 g, 6.7 mmol) was dissolved in dry toluene
(15 ml). Palladium acetate (10 mg, 4.45×10−5 mol),
dry triethylamine (1.35 g, 13.3 mmol) and tri-ortho-
tolylphosphine (TOP) (0.08 g, 2.67×10−5 mol) were
added all at once successively. The brown suspension
was heated during 24 h at 110°C. The yellow suspen-
Compound 4-(diisopropyloxymethylsilyl)styrene (13)
(8.23 g, 31 mmol) was dissolved in dry MeOH (10 ml).
1% M p-toluene sulfonic acid (17 mg) was added all at
once. The yellow suspension was stirred for 4 h. The
organic solvent was pumped off and the corresponding
crude oil was distilled under vacuum (b.p. 70–80°C,
5×10−2 mBar) to afford 4-(dimethoxymethylsi-
lyl)styrene (8b) as a yellow oil (4 g, 20 mmol) in 65%
1
yield. H-NMR (CDCl3, l): 7.64 (2H, d), 7.49 (2H, d),
6.77 (1H, dd), 5.84 (1H, d), 5.33 (1H, d), 3.60 (6H,s),
0.39 (3H, s).
Scheme 9.

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G. Cer6eau et al. / Journal of Organometallic Chemistry 626 (2001) 92–99
4.4. 4-Bromo-1-(diisopropyloxymethylsilyl)benzene
(14b%)
ꢀ20°C. The brown suspension was concentrated under
vacuum and the dark residue was extracted with 50 ml
of dry toluene. The yellow suspension was filtered on
silanized silica and concentrated under vacuum. The
expected product 2a was obtained as a fine yellow
powder (1.88 g, 4.49 mmol) in 97% yield. 1H-NMR
(CDCl3, l): 7.68 (4H, m), 7.59 (4H, d), 3.67 (18H, s).
13C-NMR (CDCl3, l): 135.1, 131.4, 130.2, 125.7, 90.9,
51.3. 29Si-NMR (CDCl3, l): −54.8. Anal. Calc. for
C20H26O6Si2: C, 57.39; H, 6.16; Si, 13.42. Found: C,
57.23; H, 5.85; Si, 13.45%.
A solution of 4-bromophenyl magnesium bromide
(7.82 g, 50 mmol) in THF (100 ml) was added at 0°C to
a solution of chloromethyldiisopropyloxysilane (12b%)
(10 g, 48 mmol). The mixture was stirred at r.t. for 24
h. After evaporation of the solvent, the yellow solid was
extracted by 200 ml of dry pentane and filtered. The
solvent was then pumped off to afford a yellow oil.
Residual 1,4-dibromobenzene (11) was sublimated un-
der vacuum at 80°C to give 4-bromo-1-(diisopropy-
loxymethylsilyl)benzene (14b%) as a colorless oil in 33%
4.8. 1-[4-(Trimethoxysilyl)phenyl]-2-trimethylsilyl-
acetylene (19a)
1
yield (5.1 g, 16 mmol). H-NMR (CDCl3, l): 7.52 (4H,
m), 4.22 (2H, hept), 1.24 (12H, d), 0.39 (3H, s). 13C-
NMR (CDCl3, l): 136.1, 134.5, 131.3, 125.1, 65.8, 26.1,
−2.8. 29Si-NMR (CDCl3, l): −21.8.
A
solution of [1-(4-bromophenyl)-2-trimethylsi-
lyl]acetylene (18) [22] (17 g, 0.067 mol) in dry THF (60
ml) was added dropwise to a suspension of chloro-
trimethoxysilane 12a (16 g, 0.1 mol) and magnesium
chips (2.45 g, 0.1 mol) in dry THF (60 ml) at 10°C. The
mixture was then stirred at r.t. for 1 day. After evapo-
ration of the solvent, the brown mixture was extracted
with 200 ml of dry pentane and filtered. The solvent
was then pumped off and the brown oil was distilled
under vacuum (b.p. 78–81°C, 10−1 mBar) to afford a
colorless oil 19a in 46% yield (9 g, 0.031 mol). 1H-NMR
(CDCl3, l): 7.60 (2H, d), 7.47 (2H, d), 3.65 (9H, s), 0.28
(9H, s). 13C-NMR (CDCl3, l): 134.9, 131.7, 130.8,
125.7, 105.3, 96.0, 51.2; 0.3. 29Si-NMR (CDCl3, l):
−17.32, −54.8. Anal. Calc. for C14H22O3Si2: C, 57.08;
H, 7.52. Found: C, 57.07; H, 7.52%.
4.5. 4-Bromo-1-(dimethoxymethylsilyl)benzene (9b)
Compound
4-bromo-1-(diisopropyloxymethylsi-
lyl)benzene (14b%) (5 g, 16 mmol) was dissolved in dry
MeOH (20 ml). 1% M p-toluene sulfonic acid (30 mg)
was added all at once. The suspension was stirred for 4
h. The organic solvent was pumped off and the corre-
sponding crude oil was 4-bromo-1-(dimethoxymethylsi-
1
lyl)benzene (9b) (2 g, 8 mmol) in 50% yield. H-NMR
(CDCl3, l): 7.56 (4H, m), 3.59 (6H,s), 0.38 (3H, s).
4.6. Chloromethyldiisopropyloxysilane (12b%)
A solution of trichloromethylsilane (29.9 g, 200
mmol) in 200 ml of anhydrous pentane was placed in a
Schlenck tube under an Ar atmosphere at 0°C. A
solution of 2.2 equivalents of dry isopropanol (26.4 g,
440 mmol) was then added dropwise. The evolution of
HCl was trapped by a concentrated solution of NaOH.
At the end of addition, the reaction mixture was al-
lowed to warm to r.t. and then stirred for 24 h. After
this time the colorless solution was evaporated under
vacuum (2 mBar) to give a colorless oil (36 g). It
consisted in a mixture of chloromethyldiisopropyloxysi-
lane (12b%) (ꢀ80%) and methyltriisopropyloxysilane
(ꢀ20%).1H-NMR (CDCl3, l): 4.37 (2H, hept), 1.26
(12H, d), 0.48 (3H, s).
4.9. [4-(Trimethoxysilyl)phenyl]acetylene (16a)
A
solution
of
1-[4-(trimethoxysilyl)phenyl]-2-
trimethylsilylacetylene (19a) (19.80 g, 0.067 mol) in 41.8
ml of dry MeOH was stirred for 4 h with potassium
carbonate (0.84 g, 6.07 mmol) at r.t. The white suspen-
sion was concentrated under vacuum and the residue
was extracted with 50 ml of dry pentane. After filtra-
tion, the solvent was removed under vacuum to give a
crystalline beige powder. This crude solid was crystal-
lized in dry hexane and afforded white crystals of
[4-(trimethoxysilyl)phenyl]acetylene (16a) in 72% yield
1
(10.76 g, 0.048 mol). m.p. 38–39°C. H-NMR (CDCl3,
4.7. 4,4%-Bis(trimethoxysilyl)diphenylacetylene (2a)
l): 7.62 (2H, d), 7.53 (2H, d), 3.65 (9H, s), 3.17 (1H, s).
13C-NMR (CDCl3, l): 135.0, 131.9, 130.8, 124.7, 83.8,
78.8, 51.3. 29Si-NMR (CDCl3, l): −55.03. Anal. Calc.
for C11H14O3Si: C, 59.44; H, 6.34, Si, 12.64. Found: C,
59.85; H, 6.30, Si, 13.30%.
A
solution of 4-(trimethoxysilyl)phenylacetylene
(16a) (1.03 g, 4.62 mmol) in dry triethylamine (13.5 ml)
with a stoichiometric amount of 4-iodo-1-(trimethoxysi-
lyl)benzene (15a) (1.5 g, 4.62 mmol) was stirred for a
few minutes. 3% M CuI (26 mg, 0.138 mmol) and
bis-(triphenylphosphine)palladium chloride(II) (100 mg,
0.138 mmol) were added all at once, and the final
brown suspension was stirred vigorously for 8 h at
4.10. 4,4%-(Dimethoxymethylsilyl)diphenylacetylene (2b)
A
solution of [4-(dimethoxymethylsilyl)phenyl]-
acetylene (16b) (0.96 g, 4.64 mmol) in dry triethylamine

G. Cer6eau et al. / Journal of Organometallic Chemistry 626 (2001) 92–99
97
(15 ml) with a stoichiometric amount of 4-iodo-1-
(dimethoxymethylsilyl)benzene (15b) (1.43 g, 4.64
mmol) was stirred for few minutes. 2.5% M CuI (23
mg, 0.12 mmol) and bis-(triphenylphosphine)palladium
chloride(II) (82 mg, 0.12 mmol) were added all at once,
and the final beige suspension was stirred vigorously for
15 h at ꢀ20°C. The corresponding suspension was
filtered on silanized silica and concentrated under vac-
uum. The expected product 4,4%-(dimethoxymethylsi-
lyl)diphenylacetylene (2b) was obtained as an orange oil
distilled under vacuum (b.p. 80–85°C, 10−2 mBar) to
afford 19b% as a colorless oil in 66% yield (11 g, 33
mmol). H-NMR (CDCl3, l): 7.63 (2H, d), 7.46 (2H,
1
d), 4.21 (2H, hept), 1.20 (12H, m), 0.28 (9H, s).
4.14. 1-[4-(Dimethoxmethylsilyl)phenyl]-
2-trimethylsilylacetylene (19b)
Compound 1-[4-(diisopropoxymethylsilyl)phenyl]-2-
trimethylsilylacetylene (19b%) (5.01 g, 15 mmol) was
dissolved in dry MeOH (4.29 g, 130 mmol). 1% M
p-toluene sulfonic acid (17 mg, 0.1 mmol) was added all
at once. The suspension was stirred for 4 h. The organic
solvent was pumped off and the corresponding crude
orange oil was distilled under vacuum (b.p. 75–80°C,
10−2 mBar) to afford 1-[4-(dimethoxymethylsi-
lyl)phenyl]-2-trimethylsilylacetylene (19b) as a colorless
1
(1.72 g, 4.44 mmol) in 96% yield. H-NMR (CDCl3, l):
7.65 (4H, m), 7.57 (4H, d), 3.60 (12H, s), 0.40 (6H, s).
13C-NMR (CDCl3, l): 134.69, 134.32, 131.35, 112.24,
90.73, 50.98, −4.79. 29Si-NMR (CDCl3, l): −14.46.
4.11. 4-Iodo-1-(diisopropyloxymethylsilyl)benzene (17b%)
1
A solution of 4-bromo-1-(diisopropyloxymethylsilyl)-
benzene (14b%) (13.35 g, 42.1 mmol) in THF (85 ml) was
added slowly dropwise at 0°C to a suspension of mag-
nesium chips (1.53 g, 63.1 mmol) in THF (10 ml). After
1 h, the Grignard reagent of 4-bromo-1-(diisopropy-
loxymethylsilyl)benzene was added dropwise at 0°C to
iodine (13.87 g, 54 mmol) dissolved in 50 ml of dry
THF. After stirring during 4 h, the solvent was pumped
off and the residue was extracted with dry pentane (200
ml) and filtered. The yellow solution was concentrated
to afford 4-iodo-1-(diisopropyloxymethylsilyl)benzene
oil (3.3 g, 11.7 mmol) in 78% yield. H-NMR (CDCl3,
l): 7.58 (4H, m), 3.65 (12H,s), 0.40 (6H, s), 0.27 (9H,
s).
4.15. 4-(Dimethoxymethylsilyl)phenylacetylene (16b)
A solution of 1-[4-(dimethoxymethylsilyl)phenyl]-2-
trimethylsilylacetylene (19b) (5 g, 17.80 mmol) in 25 ml
of dry MeOH was stirred for 2 h with potassium
carbonate (120 mg, 0.80 mmol) at r.t. The dark suspen-
sion was concentrated under vacuum and the residue
was extracted with 60 ml of dry hexane. After filtration,
the solvent was removed under vacuum to give [4-
(dimethoxymethylsilyl)phenyl]acetylene (16b) as a col-
1
(17b%) as a yellow oil in 84% yield. H-NMR (CDCl3,
l): 7.76 (2H, d), 7.42 (2H, d), 4.21 (2H, hept), 1.23
(12H, t), 0.37 (3H, s).
1
orless oil (3.4 g, 16.5 mmol) in 93% yield. H-NMR
4.12. 4-Iodo-1-(dimethoxymethylsilyl)benzene (15b)
(CDCl3, l): 7.59 (2H, d), 7.55 (2H, d), 3.59 (6H, s), 3.16
(1 H, s), 0.39 (3H, s).
Compound
4-iodo-1-(diisopropyloxymethylsilyl)-
benzene (17b%) (11.27 g, 35.5 mmol) was dissolved in
dry MeOH (12.87 g, 400 mmol). 1% M p-toluene
sulfonic acid (53 mg, 0.3 mmol) was added all at once.
The yellow suspension was stirred for 4 h. The organic
solvent was pumped off and the corresponding crude
orange oil was distilled under vacuum (b.p. 59–69°C,
3×10−1 mBar) to afford 4-iodo-1-(dimethoxymethylsi-
lyl)benzene (15b) as a colorless oil (9 g, 30 mmol) in
82% yield. 1H-NMR (CDCl3, l): 7.78 (2H, d), 7.37
(2H, d), 3.58 (6H,s), 0.37 (3H, s).
4.16. 4,4%-Bis-(trimethoxysilyl)diphenylbut-1,3-diyne (3a)
[4-(Trimethoxysilyl)phenyl]acetylene (16a) (2 g, 9
mmol), one equivalent of chloroacetone (0.67 g, 9
mmol), two equivalents of dry triethylamine (2.51 ml),
7.6% M CuI (130 mg, 0.68 mmol) and 3% M tetrakis-
(triphenylphosphine)palladium (312 mg, 27 mmol) were
added all at once. The final black solution was stirred
for 24 h at 20°C. The resulting black suspension was
concentrated under vacuum and the dark residue was
extracted with 50 ml of dry pentane. The residual dark
suspension was filtered on silanized silica and concen-
trated under vacuum. The black crude oil was crystal-
lized twice in dry pentane and afforded the expected
product 3a as a yellow fine powder in 67% yield (1.58 g,
4.13. 1-[4-(Diisopropyloxymethylsilyl)phenyl]-
2-trimethylsilylacetylene (19b%)
A solution of the Grignard reagent prepared from
1-(4-bromophenyl)-2-trimethylsilylacetylene (13.85 g, 50
mmol) in THF (100 ml) was added at 0°C to a solution
of chloromethyldiisopropyloxysilane (12b%) (12 g, 60
mmol). The mixture was stirred at r.t. for 24 h. After
evaporation of the solvent, the gray solid was extracted
by 200 ml of dry pentane and filtered. The solvent was
then pumped off to afford a yellow oil. This oil was
1
3.31 mmol) (m.p. 57–59°C). H-NMR (CDCl3, l): 7.66
(4H, d), 7.56 (4H, d), 3.66 (18H, s). 13C-NMR (CDCl3,
l): 135.1, 132.2, 131.5, 124.2, 82.2, 75.3, 51.3. 29Si-
NMR (CDCl3, l): −55.3. Anal. Calc. for C25H26O6Si2:
C, 62.74; H, 5.40; Si, 11.73. Found: C, 60.05; H, 5.56;
Si, 13.20%.

98
G. Cer6eau et al. / Journal of Organometallic Chemistry 626 (2001) 92–99
4.17. 4,4%-Bis-(dimethoxymethylsilyl)diphenylbut-1,3-
diyne (3b)
ford a crude yellow oil distilled under vacuum (b.p.
120–130°C, 5×10−2 mbar). The expected product 5
was obtained as an oil (0.75 g, 1.25 mmol) (55% yield).
1H-NMR (CDCl3, l): 4.23 (hept, 3H, hept), 1.21 (8H,
d), −0.27 (6H, s), 0,00 (2H, s). 13C-NMR (CDCl3, l):
88.30, 87.39, 65.38, 29.96, 0.60, 0.57. 29Si-NMR
(CDCl3, l): −15.94, −50.13.
In a Schlenk tube under Ar, 1.66 g (8.04 mmol) of
[4-(dimethoxymethylsilyl)phenyl]acetylene (16b), one
equivalent of chloroacetone (0.745 g, 8.04 mmol), two
equivalents of dry ethylamine (2.3 ml), 7.6% M CuI
(116 mg, 0.61 mmol) and tetrakis-(triphenylphosphine)
palladium(0) (280 mg, 0.61 mmol) were added all at
once. The final black solution was stirred for 4.5 h at
ꢀ20°C. The residual dark suspension was filtered on
silanized silica and concentrated under vacuum to af-
ford a crude yellow oil. It was crystallized twice in dry
pentane and afforded 4,4%-bis-(dimethoxymethylsi-
lyl)diphenylbut-1,3-diyne (3b) as a yellow fine powder
(1 g, 2.43 mmol) (m.p. 85–86°C) in 61% yield. 1H-
NMR (CDCl3, l): 7.64 (4H, d), 7.57 (4H, d), 3.60
(12H, s), 0.39 (6H, s). 29Si-NMR (CDCl3, l): −14.80.
4.20. (Triisopropyloxysilylmethyl)dimethylsilane (21)
The Grignard reagent of chloromethyltriisopropyl-
oxysilane (0.045 mol) was added dropwise at 0°C to
chlorodimethylsilane (3.76 g, 0.040 mol) dissolved in
150 ml of THF. The mixture was stirred at 30°C for
about 24 h. After evaporation of THF the residue was
extracted with 400 ml of dry pentane and filtrated.
Pentane was then pumped off to give a yellow oil. The
distillation of this oil (b.p. 74–77°C, 5×10−1 mBar)
afforded 7.04 g (0.027 mol) of (triisopropyloxysilyl-
methyl)dimethylsilane (21) (67% yield). 1H-NMR
(CDCl3,l): 4.24 (3H, hept), 4.05 (1H, hept), 1.23 (18H,
d), 0.16 (6H, d), −0.12 (2H, d). 13C-NMR (l): 65.22,
25.95, −1.47, −2.78. 29Si-NMR (CDCl3,l): 15.57,
−48.46.
4.18. 1,4-Bis-[2-(4-trimethoxysilylphenyl)ethynyl]-
benzene (4)
A
solution of [4-(trimethoxysilyl)phenyl]acetylene
(16a) (1 g, 4.50 mmol) in dry triethylamine (12.5 ml)
with a 0.5 equivalent of 1,4-diodobenzene (0.74 g, 2.25
mmol) was stirred for few minutes. 5% M CuI (21 mg,
0.112 mmol) and bis-(triphenylphosphine)palladium
chloride(II) (80 mg, 0.112 mmol) were added all at
once, the final brown suspension was stirred vigorously
for 8 h at ꢀ20°C. The brown suspension was concen-
trated under vacuum and the dark residue was ex-
tracted with 50 ml of dry toluene. The yellow
suspension was filtered on silanized silica and concen-
trated under vacuum. The expected product was ob-
tained as a fine yellow–orange powder. Crystallization
in hexane–dichloromethane (1:1) gave the expected
product 4 as an orange powder (1.88 g, 4.49 mmol) in
4.21. (Triisopropyloxysilylmethyl)dimethylchlorosilane
(22)
The compound (triisopropyloxysilylmethyl)dimethyl-
silane (21) (10.4 g, 0.037 mol) was added dropwise at
r.t. to a solution of CCl4 (60 ml) containing PdCl2
(66×10−3 g, 74×10−4 mol). The dark mixture was
stirred at 80°C for 24 h. The solvent was then evapo-
rated under vacuo to give a yellow oil. The distillation
of the residue (b.p. 80°C, 2 mBar) afforded 10.01 g
(0.032 mol) of (triisopropyloxysilylmethyl)dimethyl-
chlorosilane (22) (88% yield). 1H-NMR: 4.25 (3H,
hept), 1.23 (18H, d), 0.54 (6H, s), 0.30 (2H, s). 13C-
NMR (CDCl3, l): 65.52, 25.61, 4.28, 1.56.
1
97% yield. m.p. 164–166°C. H-NMR (CDCl3, l): 7.69
(4H, d), 7.59 (4H, d), 7.55 (4H, s), 3.67 (18 H, s).
13C-NMR (CDCl3, l): 135.1, 132.0, 131.4, 130.4, 125.6,
123.5, 91.6, 90.8, 51.3. 29Si-NMR (CDCl3, l): −55.9.
Anal. Calc. for C28H30O6Si2: C, 64.48; H, 5.78; Si,
10.83. Found: C, 63.42; H, 5.73; Si, 11.75%.
4.22. [(Triisopropyloxysilylmethyl)(dimethyl)-
(ethynyl)]silane (20)
4.19. Bis[(triisopropyloxysilylmethyl)dimethylsilyl]-
but-1,3-diyne (5)
A solution of ethynylmagnesiumbromide (0.035 mol)
was added dropwise at 0°C to (triisopropyloxysilyl-
methyl)dimethylchlorosilane (22) (9.26 g, 0.030 mol)
dissolved in 40 ml of THF. The mixture was stirred at
r.t. for about 18 h. After evaporation of THF, the
residue was extracted with 200 ml of dry pentane and
filtrated. The organic solvent was then pumped off to
give an oil. Distillation of the residue (b.p. 73°C, 2
mBar) afforded 7.1 g (0.024 mol, 67% yield) of [(triiso-
In a Schlenk tube under argon, 1.5 g (5 mmol) of
[(triisopropyloxysilylmethyl)(dimethyl)(ethynyl)]silane
(20), one equivalent of chloroacetone (0.46 g, 5 mmol),
two equivalents of dry ethylamine (1.3 ml), 7.6% M CuI
(72 mg, 0.38 mmol) and tetrakis-(triphenylphos-
phine)palladium(0) (173 mg, 0.38 mmol) were added all
at once. The final black solution was stirred for 10 h at
r.t. The residual dark suspension was filtered on
silanized silica and concentrated under vacuum to af-
propyloxysilylmethyl)(dimethyl)(ethynyl)]silane
(20).
1H-NMR (CDCl3, l): 4.24 (3H, hept), 2.41 (1H, s), 1.22
(18H, d), 0.31 (1H, s), 0.03 (1H, s).

G. Cer6eau et al. / Journal of Organometallic Chemistry 626 (2001) 92–99
99
4.23. 1,4-Bis-(dimethoxymethylsilyl)benzene (6)
Chevalier from Dow Corning Ltd. for fruitful
discussions.
A solution of 1,4-dibromobenzene (24.75 g, 105
mmol) in 60 ml of anhydrous THF, was added drop-
wise to a suspension of magnesium (12.60 g, 518 mmol)
and methyltrimethoxysilane (28.60 g, 210 mmol) in 20
ml of anhydrous THF at 0°C. The suspension was then
stirred 24 h at 20°C. The solvent was pumped off under
vacuum (2 mBar), the reaction mixture was then taken
up with 250 ml of dry pentane. The green suspension
was filtered. The filtrate was evaporated under vacuum
(2 mBar) to give a pale yellow oil which was distilled
(b.p. 105–110°C, 5×10−1 mBar). Product 1,4-bis-
(dimethoxymethylsilyl)benzene (6) (7.38 g, 26.5 mmol)
was obtained as a colorless oil which crystallized at r.t.
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1
in 25% yield. H-NMR (CDCl3, l): 7.67 (4H, s), 3.60
(12H, s), 0.39 (6H, s). 29Si-NMR (CDCl3, l): −14.90.
Anal. Calc. for C12H22O4Si2: C, 50.35; H, 7.69; Si,
19.58. Found: C, 50.30; H, 7.64; Si, 20.01%.
4.24. 4,4%-Bis(dimethoxymethylsilyl)biphenyl (7)
Compound
4,4%-bis(diisopropyloxymethylsilyl)-
diphenyl (23) (7.1 g, 15 mmol) was dissolved in dry
MeOH (4.29 g, 130 mmol). 1% M p-toluene sulfonic
acid (17 mg, 0.1 mmol) was added all at once. The
suspension was stirred for 4 h. The organic solvent was
pumped off and the corresponding crude orange oil was
distilled under vacuum (b.p. 110–115°C, 10−2 mBar)
to afford 4,4-bis-(dimethoxymethylsilyl)biphenyl (7) as
a colorless oil (3.83 g, 12.75 mmol) in 85% yield.
1H-NMR (CDCl3, l): 7.72 (4H, d), 7.67 (4H, d), 3.65
(12H, s), 0.44 (6H, s). 29Si-NMR (CDCl3, l): −14.7.
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4.25. 4,4%-Bis(diisopropyloxymethylsilyl)diphenyl (23)
A solution of diGrignard reagent of 4,4%-dibromo-
biphenyl (18.03 g, 50 mmol) in THF (100 ml) was
added at 0°C to a solution of chloromethyldiisopropy-
loxysilane (12b%) (22 g, 110 mmol). The mixture was
stirred at r.t. for 24 h. After evaporation of the solvent,
the gray solid was extracted with 200 ml of dry pentane
and filtered. The solvent was then pumped off to afford
a yellow oil. Residual 4,4%-dibromobiphenyl was subli-
mated under vacuum at 100°C. The resulting oil was
distilled under vacuum (b.p. 120–130°C, 10−1 mbar) to
afford 23 as a colorless oil in 35% yield (8.29 g, 17.5
1
mmol). H-NMR (CDCl3, l): 7.70 (4H, m), 7.67 (4H,
m), 4.25 (4H, hept), 1.26 (12H, m), 0.39 (3H, s).
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Acknowledgements
The authors acknowledge Dow Corning Corporation
for supporting this research and wish to thank Dr P.