High-yield electrosynthesis of furylchlorosilanes, silyl and silanylene furans

Article abstract of DOI:10.1016/S0022-328X(98)00853-5

The intensiostatic sacrificial anode technique proved to be efficient for the silylation of 2-bromo- and 2,5-dibromofurans with trimethylchlorosilane and diorganodichlorosilanes with high selectivity and versatility not accessible by pure chemical routes. Furylsilanes, bromofurylsilanes, bis(furyl)silanes, bis(bromofuryl)silanes, furylchlorosilanes, bis(silyl and chlorosilyl)furans, poly[(silanylene)furylene] oligomers and [1₄]dimethylsila-2,5-furanocalixarene were obtained in good to high yields.

Full text of DOI:10.1016/S0022-328X(98)00853-5

Journal of Organometallic Chemistry 570 (1998) 147–154
High-yield electrosynthesis of furylchlorosilanes, silyl and silanylene
furans
Carole Moreau, Franc¸oise Serein-Spirau, Michel Bordeau *, Claude Biran
Laboratoire de Chimie Organique et Organome´tallique, UMR 5802 CNRS, Uni6ersite´ Bordeaux I, F-33405 Talence, France
Received 2 July 1998
Abstract
The intensiostatic sacrificial anode technique proved to be efficient for the silylation of 2-bromo- and 2,5-dibromofurans with
trimethylchlorosilane and diorganodichlorosilanes with high selectivity and versatility not accessible by pure chemical routes.
Furylsilanes, bromofurylsilanes, bis(furyl)silanes, bis(bromofuryl)silanes, furylchlorosilanes, bis(silyl and chlorosilyl)furans,
poly[(silanylene)furylene] oligomers and [14]dimethylsila-2,5-furanocalixarene were obtained in good to high yields. © 1998
Elsevier Science S.A. All rights reserved.
Keywords: Silicon; Furylsilanes; Furylchlorosilanes; Bromide; Electrochemical synthesis; Sacrificial anode
The electrolysis is carried out at r.t. in an undivided cell
using a cylindrical stainless steel grid as the cathode, a
massive metallic Mg or Al rod as the anode, tetrahy-
1. Introduction
Alkoxysilanes, silylfurans and particularly 2-
trimethylsilylfuran have been shown to be useful in
obtaining high isotactic polypropylene by Ziegler–
drofuran/hexamethylphosphoramide
(THF/HMPA,
70:10 vol) as the solvent and 0.02 M Bu4NBr as the
supporting electrolyte [5,6].
Natta
catalysed
propene
polymerization
[1].
Trimethylsilylated derivatives of furans are generally
obtained in only 50–60% yield from furan either by
metallation with n-butyllithium [2] or by activation of
the 2-C–H bond with calcium [3], followed by reaction
with trimethylchlorosilane.
2. Results and discussion
2.1. Cyclic 6oltammetry study
Here we report how the electrochemical sacrificial
anode technique enables to prepare various organosili-
con derivatives of furan (1) from 2-bromo- (2), and
2,5-dibromofuran (3) not commercially available, but
previously prepared by bromination of furan by Br2 in
dimethylformamide (DMF) [4]. The method used in-
volves cathodic reduction of one or two carbon–
bromine bonds in the substrate in the presence of a
mono- or a dichlorosilane as the electrophile at con-
stant current density (i=0.1 A, j=0.190.05 A dm−2).
A cyclic voltammetry study of the starting furan
bromo derivatives was performed under the usual con-
ditions [6], i.e. THF 0.1 M Bu4NBF4, at a 1 mm
diameter Pt disk (sweep rate, 0.2 V s−1; voltage scan
0/1.0/–2.93/0 V). The measured reduction peak poten-
* Corresponding author. Tel.: +33 556 846281; fax: +33 556
846646.
Scheme 1.
0022-328X/98/$ - see front matter © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00853-5

148
C. Moreau et al. / Journal of Organometallic Chemistry 570 (1998) 147–154
Scheme 2.
tials vs. SCE were: −2.10 and −2.60 V for 2 and
−1.95, −2.1, and −2.60 V for 3. For both com-
pounds the last peak recorded at −2.6 V, present as
well in the voltammogram of 1 can be assigned to the
ring reduction. The first peaks corresponding to reduc-
tion of C–Br bonds are less cathodic than the first
reduction peak of the mono-and dichlorosilanes used in
this work [7]. Thus, furan bromides are expected to be
first reduced in the electrochemical process.
previously formed quantitatively at 2.2 F mol−1, was
partially transformed in 4 at 4.4 F mol−1. This ability
of Cfuryl–Si bonds to be reduced was confirmed by
cyclic voltammetry measurements under the above con-
ditions. Peaks were effectively observed at −2.47 V for
5 and −2.55 V vs. SCE for 6.
Thus, under these conditions, the cleavage of the
Cfuryl–Si bond is favoured relative to the reductive
silylation of the furyl ring that is in agreement with the
good leaving group ability of the furyl anion in nucle-
ophilic substitutions [9]. The reductive cleavage of car-
bon–silicon bonds was yet pointed out in the
electrochemical reduction of 2,5-dibromothiophene in
the presence of dimethyldichlorosilane [10]. Taking into
account that Me3SiH was isolated and characterized
and that protonation can occur from the solvent or the
supporting electrolyte, the proposed mechanism for the
formation of 4 is depicted in Scheme 3.
2.2. Reducti6e electrotrimethylsilylation of bromofurans
2-Trimethylsilylfuran (4) was isolated in 88% yield
after the passage of 2.2 F mol−1 of charge with either
an aluminium or a magnesium anode, using a large
excess (20 equivalents) of trimethylchlorosilane com-
pared to engaged 2 (Scheme 1, [8]a).
Under the same conditions, at 2.2 F mol−1, the
electrotrimethylsilylation of 3 led, after 100% conver-
sion, to three products which distribution depended on
the nature of the anodic metal (Scheme 2).
2.3. Electroreducti6e coupling of bromofurans with
dichlorosilanes
With an aluminium anode, the main product, as
expected for this charge, is 2-bromo-5-trimethylsilyl-
furan (5) (71% isolated) in spite of 15% of protonated
product 4, and 8% of bis(trimethylsilyl)furan (6). With
a magnesium anode, the disilylated product 6 was
mainly obtained (89% isolated), likely due to a chemical
reductive role of the anodically scoured magnesium
revealed by the abnormally high anodic faradaic yield
(140%). Chemical routes only enabled the preparation
of 4 in 57% yield from furan using BuLi/Me3SiCl at
low temperature and the synthesis of 6 from 4 in 31%
yield by the same reaction ([2]b).
The use of dichlorodiorganosilanes as silylating
agents enables the access to furylchlorosilanes and to
compounds containing regularly alternated 2-furylene/
diorganosilylene units.
2.3.1. Electroreducti6e coupling of 2-bromofuran with
diorganodichlorosilanes
After passage of 2.2 F mol−1 of 2, using a magne-
sium anode, the products of the electroreductive cou-
Table 1
Influence of the anode nature on the electrotrimethylsilylation of
2,5-dibromofuran after having passed 4.4 F mol−1
When pursuing the electrolysis of 3 with an Al anode
from 2.2 up to 4.4 F mol−1, 3 was exhausted and the
reduction of the C–Br bond of 5 in the presence of
Me3SiCl in excess was expected to give rise to 6. In fact,
6 was not the final product and the major formation of
4 (Table 1) was assigned to further reduction of one
Cfuryl–Si bond of 6. Similarly, using a Mg anode, 6
Anodes 4 Yield (%)
5 Yield (%)
6 Yield (%)
GC
Isolated
GC
GC
Isolated
Al
Mg
52
48
41
37
20
—
28
52
—
43

C. Moreau et al. / Journal of Organometallic Chemistry 570 (1998) 147–154
149
Scheme 3.
Scheme 4.
Table 2
Electrochemical preparation of bis(2-furyl)silanes and (2-furyl)chlorosilanes
R1R2SiCl2
Substrate/electrophile molar ratio
Product obtained
Yields (%)
GC
Isolated
Me2SiCl2
2:1
1:20
2:1
2:1
1:20
2:1
Bis(2-furyl)dimethylsilane
7a
8a
7b
7c
8b
7d
100
96
100
100
98
98
87
96
94
85
95
(2-Furyl)dimethylchlorosilane
Bis(2-furyl)methylvinylsilane
Bis(2-furyl)methylphenylsilane
(2-Furyl)methylphenylchlorosilane
Bis(2-furyl)methylisobutylsilane
MeViSiCl2
PhMeSiCl2
iBuMeSiCl2
100
pling with dichlorodiorganosilanes were dependent
upon the molar ratio of the engaged reagents.
suitable experimental conditions [11]. 8a was previously
chemically synthetised by the usual method in only 60%
yield [11], while 8b was not yet described.
First, 2:1 substrate/R1R2SiCl2 molar ratio led to the
expected bis(2-furyl)diorganosilanes (7a–d) (Scheme 4,
Eq. 1) with a complete conversion of 2 and an excellent
yield of isolated product (Table 2). Chemical routes
involved addition of dimethyldichlorosilane on furyl-
lithium at −10°C to obtain 45% yield of 7a [2]b. Thus,
under these conditions a variety of bis(2-furyl)silanes
7a–d were prepared in 95–98% yields, including new
compounds.
Second, when dichlorodiorganosilanes were used in
large excess (20 equivalents), 2 underwent solely and
quantitatively a monocoupling reaction leading selec-
tively to the corresponding diorganofurylchlorosilanes
(8a–b) (Scheme 4, Eq. 2), showing that these products
result from the first step of the previous reaction, as
expected. 8a–b were thus isolated in high yield (85–
87%, Table 2). These compounds are particularly
sought after to reach bicyclopropylidene derivatives
which undergo clean intramolecular Diels–Alder reac-
tions with complete endo-diastereoselectivities under
2.3.2. Electroreducti6e coupling of 2,5-dibromofuran
with diorganodichlorosilanes
As electrotrimethylsilylation of 3 led directly to disi-
lylated 6 for only 2.2 F mol−1 of charge using a Mg
anode, we got bis(diorganochlorosilyl)furans (9a–b)
with excellent selectivities and isolated yields under the
same conditions: 2.2 F per mole of 3, diorgano-
dichlorosilanes in large excess (20 equivalents) (Scheme
5 and Table 3). The anodic faradaic yield of 165%
revealed a chemical participation of the anodic metal
inducing reduction of the two C–Br bonds of 3.
These results constitute a real improvement of the
common chemical routes involving two steps and the
use of expensive (Pd catalysts) [24] or dangerous
reagents as benzoyle peroxide [23]. The yields are better
and our electrochemical technique is a good alternative
to prepare these compounds which are key intermedi-
ates in the synthesis of highly conducting poly[2,5-bis-

150
C. Moreau et al. / Journal of Organometallic Chemistry 570 (1998) 147–154
Table 3
Electrochemical reduction of 2,5-dibromofuran in the presence of a large excess of dichlorosilane after having passed 2.2 F mol−1 of substrate
R1R2SiCl2
Product obtained
Yield (%)
GC
Chemical route (%)
Isolated
Me2SiCl2
PhMeSiCl2
2,5-Bis(dimethylchlorosilyl)furan
2,5-Bis(methylphenylchlorosilyl)furan
9a
9b
98
96
76
64
29 [23]
52 [24]
Scheme 5.
Scheme 6.
furyl)]dimethyl silane (10), but the corresponding hy-
drogenated compound 7a in quantitative GC and 75%
isolated yields (Scheme 6).
(dimethylsilyl)]furan and poly[2,5-bis(methylphenylsi-
lyl)]furan films (|=0.057 S cm−1) [24] after treatment
with antimony pentafluoride vapor.
According to previous analog results concerning the
electrochemical coupling of 2,5-dibromothiophene with
Me2SiCl2 under exactly the same experimental condi-
tions ([6]c), the electrochemical coupling of 3 was at-
tempted with an aluminium anode to avoid the
H-ended product 7a, but only 7% of 3 were converted.
Then, despite the loss of the terminal bromine atoms,
the electrochemical reaction involving a sacrificial mag-
nesium anode was studied more precisely by dynamic
gas chromatography throughout the electrolysis. Fig. 1
shows that during the passage of 2.2 F mol−1 of
charge, 10 is effectively formed at the beginning of the
electrolysis up to 63% at 1.0 F mol−1 to finally lead to
7a. From the beginning of the reaction, the formation
of 10 and 7a are competitive. For a charge of 1 F per
mole of 3, the substrate conversion was almost 95% and
the anodic faradaic yield of 140% revealed the chemical
reductive role of the anodically scoured magnesium. At
2.2 F mol−1, the two C–Br bonds of 10 have been
reduced to lead to 7a.
In order to synthesize longer oligomers regularly
alternating furylene and dimethylsilanylene units, the
electrocoupling of 3 with Me2SiCl2 in a substrate/elec-
trophile molar ratio of 2:1 was envisaged. Under the
same other electrolytic conditions, using a magnesium
anode, the sole product was, after 2.2 F mol−1 of
charge passed, not the expected bis[5-(2-bromo-
In order to isolate not yet described 10, the electroly-
sis was stopped at 1 F mol−1 and a yield of 59% in
isolated product was obtained.
The reduction of 10 in DMF using an aluminium
anode and 4.4 F mol−1 of charge gave rise to bis[2-(5-
formylfuryl)]dimethylsilane 11 in 83% isolated yield,
both C–Br bonds being hydroformylated under condi-
tions described elsewhere ([12], Scheme 7). 11 is sought
Fig. 1. Dynamic GC analysis of 2,5-dibromofuran (3) and Me2SiCl2
electrocoupling.

C. Moreau et al. / Journal of Organometallic Chemistry 570 (1998) 147–154
151
Scheme 7.
Scheme 8.
after as an intermediate in the synthesis of macrocycles
3. Conclusion
[13] but chemical routes enable to reach 11 in only 4%
isolated yield.
We have achieved a successful electrochemical alter-
native to the use of lithio derivatives to prepare with
high selectivities and yields several silylated furyl
derivatives. The method also allowed to obtain a vari-
ety of bis(2-furyl)silanes, furyl chlorosilanes, bis[5-(2-
Knowing that at 4.4 F per mol of substrate, with a
substrate /Me2SiCl2 molar ratio=1:1 we succeeded in
the synthesis of [14]dimethylsila-2,5-(1-methyl)pyrrolo-
calixarene [14], the electrochemical reduction of 3 was
envisaged under these operating conditions in order to
attempt the synthesis of the analogous cyclic
[14]dimethylsila-2,5-furanocalixarene (12). 12 was effec-
tively formed in 37% GC yield and isolated in 28%
bromofuryl)]dimethylsilane,
and
longer
linear
alternating silanylene-furylene oligomers and to im-
prove bis[(5-formyl-2-furyl)]dimethylsilane and [14]di-
methylsila-2,5-furanocalixarene synthesis.
from
a mixture of linear interesting alternating
silanylene-furylene unit oligomers which are: 7a (GC
yield 32%), not yet described 2,5-bis[(2%-furyl)-
dimethylsilyl)]furan (13) (GC yield 24%, isolated 17%)
and bis{5-[(2%furyl)dimethylsilyl]2-furylene}dimethylsi-
lane (14) (GC yield 7%) identified by GC/MS analysis
(Scheme 8).
The sacrificial anode method enabled to greatly im-
prove the preparation of 12 previously synthesized in
2% yield by reaction of dilithiofuran with Me2SiCl2 [15]
and optimized only in 16% yield by treatment of 1 with
two equivalents of nBuLi/TMEDA/tBuOK in hexane
followed by slow addition of dimethyldichlorosilane
[16]. Such sila-macrocyclic oligomer, particularly
sought after because of the new binding properties due
to the silicon atoms compared to analogous structures
having only carbon as bridging element, has proved its
efficiency as a receptor for membrane transport of
metal ions: compared to other silicon bridged macrocy-
cles, 12 was the most performant and selective to
extract Hg2+ ions from aqueous solutions [17].
4. Experimental section
4.1. General methods
Gas chromatography was performed with a tempera-
ture-programable Hewlett Packard 5890A apparatus
equipped with a 25 m×0.25 mm CP-Sil 5CB capillary
1
column. H-NMR spectra were recorded in CDCl3 at
250 MHz on a Bruker AC 250 spectrometer, using
residual CHCl3 (l=7.27 ppm) as the internal standard.
13C-NMR spectra were obtained at 62.86 MHz using a
Bruker AC 250 using CDCl3 (l=77.70 ppm) as the
internal standard. 29Si-NMR spectra were recorded in
CDCl3 at 39.73 MHz on a Bruker AC 200 spectrome-
ter. Electron impact mass spectra were measured at 70
eV on a VG Micromass 16F mass spectrometer coupled
with a gas chromatograph equipped with a 25 m×0.25
mm CP-Sil 5CB capillary column. IR spectra were
recorded with a Perkin-Elmer 1420 Spectrophotometer

152
C. Moreau et al. / Journal of Organometallic Chemistry 570 (1998) 147–154
with pure liquid films (NaCl or KBr plates). Elemental
analyses were performed by the Service Central de
Microanalyse du CNRS (France).
4.4. Materials
Bu4NBr (Aldrich) was used without purification.
THF (SDS) and HMPA (Aldrich) were dried by distil-
lation over sodium benzophenone ketyl and CaH2,
respectively, while dichlorosilanes were distilled over
Mg powder just before use. Bromine, furan (Aldrich)
and DMF (SDS) were used without any treatment.
Brominated derivatives of furan 2 and 3 were prelimi-
nary prepared as described in the literature [4].
4.2. Voltammetry
Cyclic voltammetry was carried out under argon in
THF (20 ml) solutions containing the substrate (2 mM)
and 0.1 M Bu4NBF4, using a 1 mm diameter Pt or
glassy carbon disk as the working electrode and an
aqueous saturated calomel reference electrode (Tacussel
XR 110) separated from the medium by a Tacussel AL
120 junction filled with the same electrolytic solution.
For measurements with a Pt disk working electrode,
ferrocene (10−3 M) was used as the internal standard
(Epa=0.63 V, Epc=0.56 V). The solution resistance
was compensated for with a positive feedback device.
The potentiostat used (Sirius) was previously described
([6]a). The sweep rate was 0.2 V s−1, and the voltage
scan 0/1.0/–3/0 V.
4.4.1. 2-Trimethylsilylfuran (4)
RN 1578-33-2; Yield 88%; b.p. 58°C/20 mmHg; H-
1
NMR (CDCl3): l 0.33 (s, 9H, SiMe3), 6.42 (m, 1H,
CHfuryl), 6.67 (d, 1H, 3J=3.2, CHfuryl), 7.68 (d, 1H,
3J=3.2, CHfuryl); 13C-NMR (CDCl3): l −1.6 (SiMe3),
109.4 (T), 119.5 (T), 146.6 (T), 161.9 (Q); 29Si-NMR
(CDCl3): l −10.58; IR (neat KBr): 2965, 2906, 1257,
1203, 1147, 1106, 1005, 899, 845, 748. The spectral data
agree with those reported in the literature [18].
4.4.2. 2-(Trimethylsilyl)-5-bromofuran (5)
4.3. General procedure for electrolysis
RN 119987-27-8; Yield 71%; b.p. 77°C/20 mmHg;
1H-NMR (CDCl3): l 0.28 (s, 9H, SiMe3), 6.28 (d, 1H,
Electrolysis was performed in an undivided cell (100
ml) described elsewhere ([6]a), equipped with a sacrifi-
cial cylindrical aluminium or magnesium bar (1 cm
diameter) as the anode and a concentric stainless steel
grid or carbon (1.090.2 dm2) as the cathode. A con-
stant current (0.1 A, density 0.190.05 A dm−2) was
provided by a Sodilec EDL 36-07 regulated dc power
supply. To the dried cell, containing a magnetic spin
bar, was added Bu4NBr (0.5 g, 1.6 mmol) as the
supporting electrolyte. The cell then was deaerated
twice under vacuum and flushed with dry nitrogen.
THF (70 ml), HMPA (6 ml), and a minimum excess of
trimethylchlorosilane just sufficient for drying the
medium (generally between 1 and 1.5 ml) were intro-
duced through a septum by syringe. The solution was
degassed by bubbling nitrogen for 10 min. The resulting
HCl (from the reaction of Me3SiCl with traces of water)
was removed by pre-electrolyzing the solution (i=0.1
A). The formed Me6Si2O is electrochemically inert.
When evolution of H2 had ceased, the substrate (20
mmol) and the suitable chlorosilane (10 mmol) for the
synthesis of 7, 10, 12, 13, and 14, or 400 mmol for the
synthesis of 4, 5, 6, 8 and 9 were introduced by means
of a syringe. The electrolysis (i=0.1 A) was then
performed until the theoretically required charge had
been passed. The reaction was monitored by gas chro-
matography. After precipitation of the major part of
the salts from the resulting solution by addition of
anhydrous pentane (2×50 ml) and subsequent filtra-
tion, solvents and excess of di- or trichlorosilane were
evaporated. The crude product was analyzed by GC
and then distilled under vacuum or eluted with pentane
on a silica gel column.
3
3J=3.1, CHfuryl), 6.58 (d, 1H, J=3.1, CHfuryl); 13C-
NMR (CDCl3): l −1.7 (SiMe3), 110.9 (T), 119.2 (Q),
122.1 (T), 164.2 (Q); 29Si-NMR (CDCl3): l −9.91; MS
m/z (rel. intensity, %): 220 (38), 218 (37, M), 205 (99),
203 (100, M-CH3), 139 (49), 137 (48), 73 (24), 43 (22);
IR (neat NaCl): 2960, 2899, 1552, 1456, 1408, 1314,
1251, 1186, 1128, 1090, 1008, 925, 842, 782, 757, 699,
631. The spectral data agree with those reported in the
literature [19].
4.4.3. 2,5-Bis(trimethylsilyl)furan (6)
RN 1578-29-6; Yield 89%; b.p. 43°C/1 mmHg; H-
1
NMR (CDCl3): l 0.32 (s, 18H, SiMe3), 6.66 (s, 2H,
3J=3.1, CHfuryl); 13C-NMR (CDCl3): l −1.4 (SiMe3),
119.6 (T), 164.9 (Q); 29Si-NMR (CDCl3): l −10.74;
MS m/z (rel. intensity, %): 212 (41, M), 197 (61,
M-CH3), 147 (100), 73 (23); IR (neat NaCl): 2959, 2899,
1538, 1456, 1407, 1295, 1250, 1172, 1126, 1093, 1011,
926, 840, 791, 757, 698, 632. The spectral data agree
with those reported in the literature [13,18,20,21].
4.4.4. Bis(2-furyl)dimethylsilane (7a)
RN 1578-44-5; Yield 98%; b.p. 107°C/20 mmHg;
1H-NMR (CDCl3): l 0.27 (s, 6H, SiMe2), 6.14 (m, 2H,
CHfuryl), 6.42 (d, 2H, CHfuryl),7.39 (s, 2H, CHfuryl);
13C-NMR (CDCl3):
l
−3.5 (SiMe2), 109.4 (T),
121.1(T), 147.0 (T), 156.5 (Q); 29Si-NMR (CDCl3): l
−23.79; MS m/z (rel. intensity, %): 192 (55, M), 178
(16), 177 (100, M-CH3), 151 (20), 149 (42), 95 (12), 45
(15), 43 (17); IR (neat NaCl): 2939, 1541, 1438, 1345,
1248, 1202, 1145, 1106, 1071, 1004, 895, 854, 827, 805,
768, 742, 671. The spectral data agree with those re-
ported in the literature [9]b, [18].

C. Moreau et al. / Journal of Organometallic Chemistry 570 (1998) 147–154
153
4.4.5. Bis(2-furyl)methyl6inylsilane (7b)
4.4.9. (2-Furyl)methylphenylchlorosilane (8b)
Yield 85%; this compound was directly purified by
RN 10447-98-0; Yield 96%; b.p. 64°C/0.5 mmHg;
1H-NMR (CDCl3): l 0.38 (s, 3H, SiMe), 5.52-5.98 (m,
3H, SiVi), 6.04 (m, 2H, CHfuryl), 6.54 (m, 2H, CHfuryl),
7.38 (m, 2H, CHfuryl); 13C-NMR (CDCl3): l −4.2
(SiMe), 109.4 (T), 124.3 (T), 132.9 (T), 135.5 (S), 147.4
(T), 155.8 (Q); MS m/z (rel. intensity, %): 204 (42, M),
189 (100, M-CH3), 163 (18), 161 (37); IR (neat NaCl)
2945, 1543, 1450, 1409, 1360, 1251, 1203, 1148, 1109,
1069, 1005, 895, 860, 830, 805, 770, 742, 672. The
spectral data agree with those reported in the literature
[22].
silica-gel column chromatography, with pentane as the
1
eluent; H-NMR (CDCl3): l 0.70 (s, 6H, SiMe2), 6.22
3
(m, 1H, CHfuryl), 6.63 (d, 1H, J=3.3, CHfuryl), 7.21
(m, 3H, CHphenyl) 7.45 (m, 2H, CHphenyl), 7.53 (d, 1H,
3J=1.5, CHfuryl); 13C-NMR (CDCl3): l −4.2 (SiMe),
109.9 (T), 123.4 (T), 128.0 (T), 130.2 (T), 133.8 (Q),
134.5 (T), 147.4 (T), 155.1(Q); MS m/z (rel. intensity,
%): 224 (13), 222 (31, M), 209 (39), 207 (100, M-CH3);
IR (neat NaCl): 2930, 1541, 1436, 1342, 1250, 1200,
1140, 1109, 1001, 896, 854, 825, 803, 765, 739. Anal.
Found: C, 59.32; H, 4.83; O, 7.15. C11H11ClOSi. Calc.:
C, 59.45; H, 4.95; O, 7.20%.
4.4.6. Bis(2-furyl)methylphenylsilane (7c)
1
Yield 94%; b.p. 151°C/3 mmHg; H-NMR (CDCl3):
l 0.70 (s, 3H, SiMe), 6.22 (m, 2H, CHfuryl), 6.63 (d, 2H,
3J=3.3, CHfuryl), 7.19 (m, 3H, CHphenyl), 7.47 (m, 2H,
CHphenyl), 7.53 (d, 2H, 3J=1.5, CHfuryl); 13C-NMR
(CDCl3): l −4.4 (SiMe), 109.7 (T), 123.1 (T), 128.0
(T), 130.0 (T), 133.9 (Q), 134.7 (T), 147.8 (T), 155.0 (Q);
29Si-NMR (CDCl3): l −23.79; MS m/z (rel. intensity,
%): 254 (96, M), 239 (100, M-CH3), 213 (16), 211 (12),
178 (11), 165 (12), 115 (12), 105 (25), 55 (11), 45 (14);
IR (neat NaCl): 3100, 3059, 3039, 2950, 1551, 1452,
1431, 1364, 1257, 1209, 1151, 1118, 1011, 900, 887, 791,
750, 730, 703, 691. Anal. Found: C, 69.97; H, 5.46; O,
12.46. C15H14O2Si. Calc.: C, 70.86; H, 5.51; O, 12.59%.
4.4.10. 2,5-Bis(dimethylchlorosilyl)furan (9a)
RN 125490-59-7; Yield 76%; b.p. 85°C/1 mmHg;
1H-NMR (CDCl3): l 0.70 (s, 12H, SiMe2), 6.22 (s, 2H,
CHfuryl); 13C-NMR (CDCl3): l −4.4 (SiMe2), 123.1
(T), 155.0 (Q); 29Si-NMR (CDCl3) l 9.61; MS m/z (rel.
intensity, %): 256 (5), 255 (3), 254 (20), 253 (5), 252 (31,
M), 239 (17), 237 (25, M-CH3); IR (neat NaCl): 2963,
1540, 1454, 1405, 1261, 1175, 1068, 927, 806, 748, 681,
602. The spectral data agree with those reported in the
literature [23].
4.4.11. 2,5-Bis(methylphenylchlorosilyl)furan (9b)
RN 129669-64-3; Yield 64%; b.p. 147°C/0.1 mmHg;
1H-NMR (CDCl3): l 0.90 (s, 6H, (SiMe)2, 6.72 (s, 2H,
CHfuryl), 7.05–7.72 (m, 10H, CHphenyl); 13C-NMR
(CDCl3): l −4.2 (SiMe), 123.1 (T), 128.1 (T), 130.8
(T), 133.1 (T), 133.2 (Q), 155.3 (Q); IR (neat NaCl):
2960, 1539, 1403, 1259, 1175, 1065, 927, 803, 748, 678,
600. The spectral data agree with those reported in the
literature [24].
4.4.7. Bis(2-furyl)isobutylmethylsilane (7d)
1
Yield 95%; b.p. 82°C/1 mmHg; H-NMR (CDCl3): l
0.33 (s, 3H, SiMe), 0.72(d, 6H, (CH3)2), 0.82 (d, 2H,
CH2), 1.70 (m, 1H, CH), 6.11 (m, 2H, CHfuryl), 6.27 (d,
3
3
2H, J=3.3, CHfuryl), 7.39 (d, 2H, J=1.5, CHfuryl);
13C-NMR (CDCl3): l −4.5 (SiMe), 23.9 (S), 24.0 (T),
25.9 (P), 109.4 (T), 121.4 (T), 147.0 (T), 156.2 (Q); MS
m/z (rel. intensity, %) 234 (27, M), 177 (100, M-iBu),
163 (11), 152 (41), 95 (16); IR (neat NaCl): 2948, 1541,
1448, 1407, 1250, 1203, 1146, 1107, 1079, 1004, 892,
860, 827, 805, 767, 741, 671. Anal. Found: C, 66.43; H,
7.52; O, 13.54. C13H18O2Si. Calc.: C, 66.66; H, 7.69; O,
13.67%.
4.4.12. Bis[2-(5-bromofuryl)]dimethylsilane (10)
Yield 59%; this compound was directly purified by
silica-gel column chromatography, with pentane as the
1
eluent; H-NMR (CDCl3): l 0.32 (s, 6H, SiMe2), 6.31
(d, 1H, 3J=3.1, CHfuryl), 6.60 (d, 1H, 3J=3.1, CHfuryl);
13C-NMR (CDCl3): l −3.9 (SiMe2) 119.1 (Q), 110.5
(T), 122.2 (T), 157.8 (Q); MS m/z (rel. intensity, %): 352
(15), 350 (44, M), 348 (14), 337 (43), 335 (100), 333 (36,
M-CH3); IR (neat NaCl): 2958, 1550, 1458, 1315, 1250,
1188, 1124, 1090, 1009, 925, 841, 782, 757, 631. Anal.
Found: C, 34.33; H, 2.97; O, 9.21. C10H10Br2O2Si.
Calc.: C, 34.28; H, 2.85; O, 9.14%.
4.4.8. (2-Furyl)dimethylchlorosilane (8a)
Yield 87%; this compound was directly purified by
silica-gel column chromatography, with pentane as the
1
eluent; H-NMR (CDCl3): l 0.70 (s, 6H, SiMe2), 6.22
3
(m, 1H, CHfuryl), 6.63 (d, 1H, J=3.3, CHfuryl), 7.53 (d,
1H, 3J=1.5, CHfuryl); 13C-NMR (CDCl3): l −4.4
(SiMe2), 109.7 (T), 123.1 (T),147.8 (T), 155.0 (Q); MS
m/z (rel. intensity, %): 162 (8), 160 (24, M), 147 (45),
145 (100, M-CH3); IR (neat NaCl): 2935, 1540, 1435,
1347, 1244, 1200, 1140, 1111, 1070, 1003, 894, 854, 826,
803, 768, 742, 677. Anal. Found: C, 44.89; H, 5.56; O,
9.86. C6H9ClOSi. Calc.: C, 45.0; H, 5.62; O, 10.0%. The
spectral data agree with those reported in the literature
[11].
4.4.13. Bis[2-(5-formylfuryl]dimethylsilane (11)
Yield 83%; this compound was directly purified by
silica-gel column chromatography, with pentane as the
eluent; F. 53°C; 1H-NMR (CDCl3): l 0.55 (s, 6H,
SiMe2), 6.72 (d, 2H, 3J=3.1, CHfuryl), 7.18 (d, 2H,
3J=3.1, CHfuryl), 9.59 (s, 2H, CHO); 13C-NMR
(CDCl3): l −3.5 (SiMe2), 119.9 (T), 123.6 (T), 157.4

154
C. Moreau et al. / Journal of Organometallic Chemistry 570 (1998) 147–154
(Q), 161.8 (Q), 178.0 (T); 29Si-NMR (CDCl3): l −20.5;
MS m/z (rel. intensity, %): 248 (100, M); IR (neat
NaCl): 2943, 1690, 1538, 1438, 1345, 1248, 1200, 1145,
1003, 894, 854, 827, 811, 757, 743. The spectral data
agree with those reported in the literature [13].
[4] M.A. Keegstra, A.J.A. Klomp, L. Brandsma, Synth. Commun.
20 (1990) 3371.
[5] J. Chaussard, J.C. Folest, J.Y. Ne´delec, J. Pe´richon, S. Sibille,
M. Troupel, Synthesis 5 (1990) 369.
[6] (a) D. Deffieux, M. Bordeau, C. Biran, J. Dunogue`s,
Organometallics 13 (1994). 2415. (b) D. Deffieux, D. Bonafou,
M. Bordeau, C. Biran, J. Dunogue´s, Organometallics 15 (1996)
2041. (c) C. Moreau, F. Serein-Spirau, M. Bordeau, C. Biran, J.
Donogue´s, J. Organomet. Chem. 522 (1996) 213.
[7] C. Biran, M. Dordeau, D. Bonafoux, D. Deffieux, C. Duprat, V.
Jouikov, M.P. Le´ger-Lambert, C. Moreau, F. Serein-Spirau, J.
Chim. Phys. 93 (1996) 591.
4.4.14. [14]Dimethylsila-2,5-furanocalixarene (12)
RN 145593-24-4; Yield 37%; F. 115°C; 1H-NMR
(CDCl3): l 0.53 (s, 24H, SiMe2), 6.65 (s, 8H, CHfuryl);
13C-NMR (CDCl3): l −3.2 (SiMe2), 120.4 (T), 161.2
(Q); MS m/z (rel. intensity, %): 496 (100, M); IR (neat
NaCl): 2941, 1540, 1441, 1343, 1250, 1200, 1105, 1001,
895, 824, 802, 768, 742. The spectral data agree with
those reported in the literature [16].
[8] (a) It is well known that 2 F mol−1 is the theoretical charge to
reduce one carbon–halogen bond. See for example: J.M.
Save´ant, Bull. Soc. Chim. Fr. (1998) 225. (b) The anodic faradaic
yield is the amount of metal consumed compared with charge
passed: 100% means a pure faradaic process whereas higher
values are the result of metal overconsumption due to a by-
chemical process.
4.4.15. 2,5-Bis[(2%-furyl)dimethylsilyl]furan (13)
Yield 17%; this compound was directly purified by
[9] (a) G. Stork, Pure Appl. Chem. 61 (1989) 439. (b) V. Gevorgyan,
L. Borisova, E. Lukevics, J. Organomet. Chem. 441 (1992) 381.
(c) D. Labrecque, K.T. Nwe, T.H. Chan, Organometallics 13
(1994) 332. (D) Y. Landais, D. Planchenault, V. Weber, Tetrehe-
dron Lett. 36 (1995) 2987.
silica-gel column chromatography, with pentane as the
1
eluent; H-NMR (CDCl3): l 0.47 (s, 12H, SiMe2), 6.32
(m, 2H, CHfuryl), 6.63 (m, 4H, CHfuryl), 7.60 (m, 2H,
CHfuryl); 13C-NMR (CDCl3): l −3 (SiMe2), 109.7 (T),
119.7 (T), 121.1 (T), 121.3 (T), 146.8 (Q), 147.1 (Q); MS
m/z (rel. intensity, %): 316 (39, M), 301 (100, M-CH3),
45 (25), 43 (33); IR (neat NaCl): 2944, 1539, 1425, 1331,
1245, 1201, 1002, 887, 824, 789, 721. Anal. Found: C,
60.82; H, 6.41; O, 15.23. C16H20O3Si2. Calc.: C, 60.75;
H, 6.32; O, 15.18%.
[10] C. Moreau, F. Serein-Spirau, C. Biran, M. Bordeau, P. Gerval,
Organometallics (1998) in press.
[11] T. Heiner, S.I. Kozhushkov, M. Noltemeyer, T. Haumann, R.
Boese, A. de Meijere, Tetrahedron 52 (1996) 12185.
[12] (a) S. Sibille, J. Pe´richon, J. Chaussard, Synth. Commun. 19
(1989) 2449. (b) C. Saboureau, S. Sibille, M. Troupel, J. Chem.
Soc. Chem. Commun. (1989) 855.
[13] E. Lukevics, N.P. Erchak, I. Castro, S. Rosike, I. Mazika, A.P.
Gaukhman, J. Popelis, Zh. Obshch. Kim. 54 (1984) 1315.
[14] C. Moreau, F. Serein-Spirau, M. Bordeau, C. Biran. Synth
Commun. (1998) in press.
[15] P. Chicart, R.J.P. Corriu, J.J.E. Moreau, F. Garnier, A. Yassar,
Inorganic and Organic Polymers with Special Properties,
Kluwer, Dordrecht, 1992, p. 179.
Acknowledgements
[16] B. Ko¨nig, M. Ro¨del, P. Bubenitschek, P.G. Jones, Angew.
Chem. Int. Ed. Engl. 34 (1995) 661.
[17] B. Ko¨nig, M. Ro¨del, P. Bubenitschek, J. Org. Chem. 60 (1995)
7406.
C.N.R.S., Ministe`re de l’Education Nationale and
Conseil Re´gional d’Aquitaine are warmly acknowl-
edged for their financial support.
[18] F.H. Pinkerton, S.F. Thames, J. Heterocycl. Chem. 7 (1970) 747.
[19] P. Bury, G. Hareau, P. Kocienski, D. Dhanak, Tetrahedron 50
(1994) 8793.
[20] C.S. Carmen, G.F. Koser, J. Org. Chem. 48 (1983) 2534.
[21] E. Lukevicks, V.N. Gevorgyan, Y.S. Golgberg, M.V. Shyman-
ska, J. Organomet. Chem. 294 (1985) 163.
[22] E. Lukevics, L.E. Demicheva, N.P. Yerchak, Y. Popelis, Izv.
Akad. Nauk. Ser. Khim. 10 (1993) 1784.
[23] H.H. Hong, W.P. Weber, Polym. Bull. 22 (1989) 363.
[24] J. Oshita, D. Kanaya, M. Ishikawa, T. Yamanaka, Chem.
Express 5 (1990) 489.
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