A new solvent-free reaction for the preparation of alkoxysilane from cyclic ethers, alcohols, or carbonyl compounds

Article abstract of DOI:10.1002/ejoc.201100489

The 1, 1, 3, 3-tetramethyldisiloxane/Pd/C system is reported here as a new method to accomplish the ring-opening of ethers and epoxides to give protected alcohols. The approach can also be used for the protection of primary or secondary alcohols and for the reduction of aldehydes and ketones to obtain alkoxysilanes.

Full text of DOI:10.1002/ejoc.201100489

FULL PAPER
DOI: 10.1002/ejoc.201100489
A New Solvent-Free Reaction for the Preparation of Alkoxysilane from Cyclic
Ethers, Alcohols, or Carbonyl Compounds
Leyla Pehlivan,[a] Estelle Métay,[a] Olivier Boyron,[b] Patrice Demonchaux,[c]
Gérard Mignani,[d] and Marc Lemaire*[a]
Keywords: Reduction / Protecting groups / Palladium / Ethers / Heterogeneous catalysis / Silanes
The 1,1,3,3-tetramethyldisiloxane/Pd/C system is reported
here as a new method to accomplish the ring-opening of
ethers and epoxides to give protected alcohols. The approach
can also be used for the protection of primary or secondary
alcohols and for the reduction of aldehydes and ketones to
obtain alkoxysilanes.
In the family of cyclic ethers, epoxides are easily prepared
from alkenes, which are present in a large variety of natural
products. The ring-opening of epoxides can be realized by
the use of boron and aluminum hydrides (KBH4, NaBH4,
ZnBH4, chloroalanes, etc.) either with or without the assist-
ance of a metal.[3–10] However, drawbacks associated with
their use are well-documented, particularly in respect to
their high reactivity with water, the use of hydrosoluble sol-
vent, and the toxicity of the formed salts. The regioselectiv-
ity of the reaction depends on the nature of the reducing
agent or the substrate.[3] Hydrogenation with Pd catalysts
can also be used for the same application with good selec-
tivities, indeed, only one product was obtained in several
cases.[11–13] When siloxanes such as PMHS and palladium
complexes were employed in the presence of allylic ether,
the corresponding alcohol was formed.[14] Based on a litera-
ture survey, reductions performed with PMHS and Pd on
charcoal in ethanol can be compared to a low-pressure hy-
drogenation.[15] These conditions allowed the reduction of
nitro to amines,[16] dehalogenation of aromatic com-
pounds,[17] reduction of aromatic acid chlorides to alde-
hydes,[18] isoxazolines, and indoles,[19] and reduction of al-
dehydes and double bonds to alkanes.[15]
Introduction
The Si–O bond is widely found in organic and inorganic
chemistry in a large variety of applications. Alkoxysilanes
can be used, for example, for the preparation of rubber and
varnish. Renewable materials for organic synthesis are often
polyoxygenated products. Unlike classical chemistry, valori-
zation of vegetal raw material requires selective deoxygen-
ation. Silanes are known to be suitable for this type of
transformation. Corriu et al. described the alcoholysis of
dihydro- and trihydrosilanes[1] with potassium carbonate,
and Yamamoto et al. reported the reduction of carbonyl
groups to a methyl group by using triethylsilane and
B(C6F5)3.[2] Although silane derivatives give rise to harm-
less silica as the ultimate by-product, trichlorosilane, tri-
alkylsilane, methoxysilane are expensive, toxic, and difficult
to use. The use of polymethylhydrosiloxane (PMHS) and
1,1,3,3-tetramethyldisiloxane (TMDS), which are relatively
nontoxic hydride donors, appears to be a good alternative
for the reduction of several functions. Moreover TMDS of-
fers the advantage of being easier to handle and of giving
a linear polymer as a by-product. In terms of biomass valo-
rization, the modification of tetrahydrofuran derivatives to
protected alcohols is interesting.
In our laboratory, we demonstrated that TMDS can be
used to efficiently reduce a range of functions, such as phos-
phane oxides,[20] nitriles,[21] amides,[22] and nitro[23] groups,
depending on the metal catalyst. Recently, Martin et al.[24]
described a useful application of TMDS in the presence of
nickel complexes that allowed the cleavage of anisole deriv-
atives.
[a] Laboratoire de Catalyse et Synthèse Organique,
Institut de Chimie et Biochimie Moléculaires et
Supramoléculaires (ICBMS), CNRS, UMR 5246,
Université Lyon 1,
43 boulevard du 11 novembre 1918, bat. CPE,
69622 Villeurbanne, France
Fax: +33-4-72431408
E-mail: marc.lemaire@univ-lyon1.fr
[b] Laboratoire de Chimie, Catalyse, Polymères et Procédés C2P2,
CNRS, UMR 5265, Bât. F308,
Results and Discussion
B. P. 2077, 43 Bd du 11 Nov. 1918, 69616 Villeurbanne cedex,
France
The ring-opening of a range of epoxides was tested at
room temperature with 1.2% Pd/C as catalyst and TMDS
as the hydride source (Table 1). The ring-opening of styrene
oxide under these conditions was selective because only iso-
[c] Minakem SAS,
145 Chemin des Lilas, 59310 Beuvry la Foret, France
[d] Rhodia, Lyon Research center,
85 Avenue des Frères Perret, B. P. 62, 69192 Saint-Fons Cedex,
France
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M. Lemaire et al.
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mer 1b was observed, with complete conversion and a good reaction was not selective because a 31:20:49 ratio was ob-
yield after 20 h of reaction (Table 1, Entry 1). This isomer served corresponding to compounds 5b, 5c and 5d, respec-
was also obtained as the major product when a mixture of tively.
sodium borohydride, moist alumina, and PdCl2 was used
Table 2. Ring-opening of tetrahydrofuran derivatives.[a]
for the ring-opening of the styrene oxide,[8] or by hydrogen-
ation using Pd(OAc)2,[13] whereas 1-phenylethanol was ob-
tained as the major product when sodium aluminum hy-
dride[25] or lithium aluminum hydride N-methylpyrrol-
idine[26] are used. Because these methods require the use of
hydrides, which react violently with air and water, the use
of Pd/C and TMDS is a good alternative. With 1,2-epoxy-
hexane, the reaction was complete and the yield quantita-
tive, however, no particular selectivity was observed. NMR
and GC–MS analyses revealed that a mixture of three prod-
ucts was obtained with a ratio of 20:20:60 for 2b, 2c, and 2d,
respectively. The observed ratio was close to the expected
statistical ratio. In the literature, the hydrogenation of an
alkyl epoxide with Pd was describe to give the branched
alcohol as the major product,[11] and the same results were
observed through the association of NaBH4 and PdCl2,[8]
whereas the use of ZnBH4 associated with zeolite gave the
linear product.[9]
Table 1. Ring-opening of epoxides.[a]
[a] Reagents and conditions: substrate (17 mmol), Pd/C (1.2 mol-
%), TMDS (8.5 mmol), r.t. [b] Conversions were determined by 1H
NMR spectroscopy and GC–MS analysis. [c] Yield obtained after
evaporation of the starting material.
The ring-opening was then tested on 3-methyltetra-
hydrofuran (6a). Surprisingly, in this case, both the conver-
sion and the yield were excellent (Table 2, Entry 3). NMR
analysis showed that three products were obtained, how-
ever, because they are branched, they were not resolved by
GC–MS analysis.
Tetrahydrofurfuryl alcohol (7a) was then studied, but the
ring-opening did not occur in this case. Instead, the forma-
tion of the protected alcohol was observed (Scheme 1).
[a] Reagents and conditions: substrate (17 mmol), Pd/C (1.2%),
TMDS (8.5 mmol), r.t. [b] Conversions were determined by 1H
NMR spectroscopy and GC–MS analysis. [c] Yield of cyclooctanol
after deprotection by TBAF followed by flash chromatography
(3bЈ).
The ring-opening of the cyclooctene oxide gave the de-
sired product with 75% conversion. To test whether the
product could be deprotected, compound 3b was treated
with 1 m tetrabutylammonium fluoride (TBAF) in tetra-
hydrofuran (THF) overnight. Under these conditions, cy-
clooctanol was isolated with good yield after flash
chromatography (Table 1, Entry 3).
Tetrahydrofuran (4a) was converted into 4b with 70%
conversion and 56% yield (Table 2, Entry 1). With 2-meth-
yltetrahydrofuran (5a), the conversion was lower and a mix-
ture of three products was obtained (Table 2, Entry 2). The Scheme 1. Attempted ring-opening of 7a.
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Solvent-Free Preparation of Alkoxysilane
Use of an excess amount of TMDS did not allow the Table 3. Reduction of aldehydes and ketones.[a]
ring-opening of the tetrahydrofurfuryl moiety from either
7a or 7b. To confirm that the ring-opening did not proceed
due to degradation of the catalyst, compound 7b was pre-
pared and added to 1.2 mol-% palladium in the presence of
TMDS. NMR analysis of the crude reaction mixture re-
vealed that conversion was very low after 20 h, however,
deprotection with TBAF was undertaken to determine a
possible selectivity. Unfortunately, no selectivity was ob-
served toward either 1,5- or 1,2-pentanediol.
These conditions were applied to other cyclic and linear
ethers, such as tetrahydropyrane, 1,3-benzodioxole, phenyl
benzyl ether, and glyme, but no reaction occurred.
To verify whether the TMDS/Pd/C system could be used
for the reduction of other functional groups, such as alde-
hydes or ketones, benzaldehyde was used as the test reagent.
[a] Reagents and conditions: substrate (10 mmol), Pd/C (1.2 mol-
%), TMDS (5 mmol), r.t. [b] Conversions were determined by 1H
NMR spectroscopy and GC–MS analysis.
In the literature, the use of Pd for the hydrogenation of
benzaldehyde in scCO2 under pressure and heat has already
been reported,[27] but different products, including the
alcohol, were obtained. Moreover, this system was inef-
ficient for aliphatic substrates. Another method using Pd/C
and potassium formate[28] gave alcohols, but low conver-
sions were observed with aliphatic aldehydes and aromatic
ketones. Sodium hypophosphite was also used with potas-
sium carbonate and Pd/C, and similar observations were
noticed.[29] Associated with silanes, other metals have been
tested. Indeed, the PdCl2/Et3SiH system was used to reduce
benzaldehyde to toluene and a small amount of alcohol was
observed,[30] whereas Et3SiH and trifluoroacetic acid[31] or
room temperature. After one hour, the formation of a jelly-
like product was observed; after treatment, analyses re-
vealed that polymer 12b was formed (Mn = 9476, Mw =
17400) (Scheme 3).
[32]
B(C6F5)3 systems were found to be efficient ways to ob-
Scheme 3. Formation of polymer 12b from 12a.
tain alcohols. Oxorhenium salen[33] catalyst and fluoride
salts[34] were also described as having a moderate to good
efficiency for the transformation of benzaldehyde.
Kiskan et al.[35] described the synthesis of poly(β-ala-tet-
In our case, after 20 h of reaction at room temperature, ramethyldisiloxane) from an allylic amine by Pt-catalyzed
NMR analysis showed that benzaldehyde was reduced to hydrosilylation in toluene at 90 °C with TMDS. Another
benzyl alcohol with 92% conversion, and GC–MS revealed method, described by Wang et al.,[36] consists of initial
that the protected benzyl alcohol 8b was formed silylation of carboxylic acids, followed by polymerization
(Scheme 2).
with a platinum catalyst of the hydrosilyl ester and a ter-
minal unsaturated carbon–carbon bond. To the best of our
knowledge, Pd/C associated with TMDS has not been used
for the reduction followed by polymerization of carbonyl
groups.
Following these results, the protection of alcohols under
the same conditions was studied. Organosilicon chemistry
has been widely used for the protection of alcohols with
chlorosilanes[37] in the presence of HCl acceptor and, in the
Scheme 2. Formation of protected benzyl alcohol 8b.
This result led us to try other aromatic and aliphatic sub- presence of silanes and Lewis acid, alcohols can be pro-
strates under the reaction conditions. The reaction with tected or reduced to alkanes. Under the same conditions,
acetophenone gave the expected mixture of diastereoiso- ethers have been cleaved to give the protected alcohols.[38–44]
mers 9b with 80% conversion (Table 3, Entry 1); no side
As detailed in Scheme 1, use of the TMDS/Pd/C system
allows the formation of alkoxysilanes. This observation was
product, such as phenylethane, was observed.
The reduction of 3-phenylpropionaldehyde (10a) gave recently described in a patent[45] in which the reaction was
good conversion (89%) (Table 3, Entry 2), and 2-octanone shown to occur at 50 °C.
(11a) was converted into the desired product 11b with a
conversion of 74% (Table 3, Entry 3).
Several examples were realized for the protection of
alcohols. The conditions described above were applied to
The reduction was also tested on a substrate containing butan-1-ol (13a) giving protected derivative 13b with a com-
two aldehyde functions. Solid terephthalaldehyde (12a) was plete conversion (Table 4, Entry 1). The protection of
diluted in toluene and treated with Pd/C and TMDS at alcohol 14a gave compound 14b with 93% conversion
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M. Lemaire et al.
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(Table 4, Entry 2). The protection could also be applied to molecular weight (Mn) and the weight-average molecular
secondary alcohols as shown by the protection of octan-2- weight (Mw) to be determined (1348 and 1825, respec-
ol, which was converted into compound 15b in 89% yield tively).
(Table 4, Entry 3).
Table 4. Protection of alcohols.[a]
Conclusions
We have demonstrated an effective use of the versatile
TMDS/Pd/C system to access alkoxysilanes. Besides the
ring-opening of epoxides and cyclic ethers, this system al-
lows the protection of alcohols and the formation of new
polymers from diols or dialdehydes, with low ecological im-
pact. Depending on the substrates, this methodology can
also be selective for the ring-opening of styrene oxide.
Experimental Section
General Information: All reagents were obtained from commercial
sources. Tetramethyldisiloxane (TMDS, 97%) was purchased from
Acros, and Pd/C (5%) from Strem Chemicals. All reagents and re-
actants were used without further purification. All reactions were
performed under an inert atmosphere (argon) in a round-bottomed
flask. All compounds were characterized by their spectroscopic
data. NMR spectra were recorded with a Bruker ALS or DRX
300 spectrometer (1H: 300 MHz, 13C: 75 MHz), chemical shifts are
expressed in ppm, J values are given in Hz. CDCl3 was used as
solvent. GC–MS were measured with focus DSQ electronic ioniza-
tion with a DBS phase. Column dimension: 30 m, 0.25 mm. Initial
temperature: 70 °C (except for 4a and 5a for which 40 °C was used),
initial time: 2 min, rate: 15 deg/min. Average molecular weights for
compound 17b were determined with a size exclusion chromatog-
[a] Reagents and conditions: substrate (10 mmol), Pd/C (1.2 mol-
raphy (SEC) system (Waters) equipped with an isocratic pump
%), TMDS (5 mmol), 20 h, r.t. [b] Conversions were determined by
(Waters 515) operated at a flow rate of 1 mL/min with THF (Ald-
1H NMR spectroscopy and GC–MS analyses. [c] After 1 h reac-
rich), an autosampler (Waters 717 Plus), a column oven, and a
tion.
refractive index detector (Waters 410) with integrated temperature
controller maintained at 30 °C. Data collection and processing were
The application of an alkene-containing substrate was
performed with the software Empower Pro version 5.0 from Waters
then studied. 1,2,3,6-Tetrahydrobenzyl alcohol (16a;
Corporation. For molecular mass separation, a guard column
Table 4, Entry 4) was engaged in the reaction at room tem-
perature and at 50 °C. After one hour of reaction, three
(PL gel 5 μm), three polymer Laboratory columns [2ϫPLgel
5 µm Mixed C (300ϫ7.5 mm), and 1ϫ PLgel 5 µm 500 A
products were observed: At room temperature a 29:52:19
ratio of 16b, 16c and 16d was observed, whereas at 50 °C,
the ratio was 16:21:63. After 18 h of reaction, the ratio
changed at room temperature to 18:55:27 and at 50 °C only
product 16d was observed. Thus, the double bond was com-
pletely reduced when heating, whereas, at room tempera-
ture, compound 16c was obtained as the major product.
Conducting the reaction with phenol afforded the desired
product 17b with moderate conversion (Table 4, Entry 5).
Because phenol is solid, palladium then TMDS were intro-
duced at 50 °C.
(300ϫ7.5 mm)] (Shropshire, UK) were used in series at 30 °C. Cali-
bration was carried out using narrow-distributed polystyrene stan-
dards. The mobile phase was THF (HPLC grade) from Acros Or-
ganics. Polymer samples were dissolved in THF to form a homo-
geneous solution. Chromatography was carried out after sample
filtration through a 0.45 µm cellulose membrane filter. Absolute
molecular weights of copolymer 11b were determined with a Waters
Size Exclusion Chromatography system coupled to an RI detector
(Waters 410) with integrated temperature controller maintained at
30 °C, and a triple-angle light scattering (LS) detector (MiniDAWN
Tristar; Wyatt Technology, Santa Barbara, CA, USA). The two sig-
nals were measured simultaneously because of the online multian-
gle laser light scattering/refractive index (SEC-MALLS/RI) ar-
rangement; so the absolute molecular weight of the copolymers
could be deduced. Data collection and processing were performed
using two software packages; ASTRA (version 4.5) from Wyatt
Technology and Empower Pro (version 5.0) from Waters Corpora-
tion.
To polymerize 1,3-propanediol, the substrate was treated
with Pd/C and TMDS to afford polymer 18b (Scheme 4)
with complete conversion. GC analysis allowed the number
General Procedure for the Ring-Opening of Epoxides and Ethers and
Protection of Alcohols: To a round-bottomed flask, under inert at-
mosphere, containing the substrate (17 mmol) were added with
caution Pd/C (1.2%, 217 mg) and TMDS (8.5 mmol, 1.5 mL) at
Scheme 4. Polymerization of diol 18a.
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Solvent-Free Preparation of Alkoxysilane
room temperature (the reaction is exothermic). After 20 h the reac-
tion mixture was diluted with ethyl ether and filtered through a
plug of Celite by flushing with ethyl ether. The filtrate was concen-
trated to afford the desired product as a colorless oil. The products
were identified by NMR and GC–MS analyses.
84–1] (6c), and 1,3-Bis(isopentyloxy)-1,1,3,3-tetramethyldisiloxane
(6d): Colorless oil. H NMR (500 MHz, CDCl3): δ = 0.07- 0.1 [m,
1
36 H, Si(CH3)2], 0.86–0.91 (t, J = 7.2, 9 H, CH3 and d, J = 7.2 Hz,
27 H, CH3), 1.10–1.18 (quint, J = 6.2 Hz, 6 H, CH2), 1.39–1.50 (q,
J = 7.7 Hz, 6 H, CH2), 1.53–1.60 (m, 3 H, CH), 1.65–1.75 (m, 3
H, CH), 3.41 and 3.51 (2ϫ dd, J = 6.5 and 9.8 Hz, J = 6.0 and
10.0 Hz, 6 H, CH2), 3.7 (t, J = 7.2, 6 H, CH2). 13C NMR
(100 MHz, CDCl3): δ = –0.8, 11.7, 16.5, 22.9, 25.0, 26.2, 37.5, 41.9,
61.0, 67.6, 68.2 ppm. GC–MS: tR = 8.36 min.
Reduction of Aldehydes/Ketones: To a round-bottomed flask, under
inert atmosphere, containing the substrate (10 mmol) were added
with caution Pd/C (1.2%, 127 mg) and TMDS (5 mmol, 0.88 mL)
at room temperature. The reaction is exothermic. After 20 h, the
reaction mixture was diluted in ethyl ether and filtered through a
plug of Celite by flushing with ethyl ether. The filtrate was concen-
trated to afford the desired product as a colorless oil. The products
were identified by NMR and GC–MS analyses.
1,1,3,3-Tetramethyl-1,3-bis[(tetrahydrofuran-2-yl)methoxy]di-
siloxane (7b): Colorless oil. 1H NMR (300 MHz, CDCl3): δ = 0.10–
0.12 [m, 12 H, 2ϫ Si(CH3)2], 1.61–1.70 (m, 2 H, CH2), 1.82–1.97
(m, 6 H, CH2), 3.63 (d, J = 6.0 Hz, 4 H, CH2), 3.74–3.79 (m, 2 H,
CH2), 3.82–3.89 (m, 2 H, CH2), 3.96–4.00 (m, 2 H, 2 CH) ppm.
GC–MS: tR = 11.61 min.
Preparation of Polymers: To a round-bottomed flask, under inert
atmosphere, containing the substrate (10 mmol) were added with
caution Pd/C (1.2%, 127 mg) and TMDS (5 mmol, 0.88 mL) at
room temperature (the reaction is exothermic). After 1 h, the reac-
tion mixture was diluted with either diethyl ether (for 16b) or
dichloromethane (for 11b). The products were then filtered through
a plug of Celite and filtrates were evaporated under vacuum. Poly-
mers were obtained as a viscous colorless oil. The products were
identified by NMR and GPC analyses.
1,3-Bis(benzyloxy)-1,1,3,3-tetramethyldisiloxane (8b): Colorless oil.
1H NMR (300 MHz, CDCl3): δ = 0.07–0.12 [m, 12 H, 2ϫ Si(CH3)
2], 4.72 (s, 2 H, CH2), 7.19–7.32 (m, 10 H, C6H5) ppm. 13C NMR
(100 MHz, CDCl3): δ = –0.7, 64.4, 126.7, 126.8, 128.5, 140.8 ppm.
GC–MS: tR = 13.10 min.
1,1,3,3-Tetramethyl-1,3-bis(1-phenylethoxy)disiloxane (9b): Color-
1
less oil. H NMR (300 MHz, CDCl3): δ = 0.05–0.17 [m, 12 H, 2ϫ
1,1,3,3-Tetramethyl-1,3-diphenethoxydisiloxane (1b): Pale-yellow
Si(CH3)2], 1.43–1.45 (d, J = 5.3 Hz, 6 H, CH3), 4.94 (q, J = 6.2 Hz,
oil. 1H NMR (300 MHz, CDCl3): δ = 0.07–0.17 [m, 12 H, 2ϫ 2 H, CH), 7.19–7.35 (m, 10 H, C6H5) ppm. 13C NMR (100 MHz,
Si(CH3)2], 2.91 (t, J = 7.2 Hz, 2 H, CH2), 3.91 (t, J = 7.2 Hz, 2 H, CDCl3): δ = –0.4, 27.1, 70.5, 125.6, 127.1, 128.4, 146.5 ppm. GC–
CH2), 7.23–7.33 (m, 5 H, C6H5) ppm. 13C NMR (100 MHz, MS: tR = 12.89 min.
CDCl3): δ = –0.8, 39.6, 67.3, 126.5, 128.5, 129.3 ppm. GC–MS: tR
1,1,3,3-Tetramethyl-1,3-bis(3-phenylpropoxy)disiloxane (10b): Col-
= 14.14 min.
orless oil. 1H NMR (300 MHz, CDCl3): δ = 0.05–0.15 [m, 12 H,
1,5-Dihexyl-2,2,4,4-tetramethyldisiloxane [564453–35–6] (2b), 1,3-
2ϫ Si(CH3)2], 1.84–1.90 (m, 4 H, CH2), 2.67 (t, J = 6.6 Hz, 6 H,
Bis(hexan-2-yloxy)-1,1,3,3-tetramethyldisiloxane (2c), and 1-Hexan- CH2), 3.69 (t, J = 6.6 Hz, 6 H, CH2), 7.17–7.27 (m, 10 H,
2-yloxy-3-(hexyloxy)-1,1,3,3-tetramethyldisiloxane (2d): Colorless
C6H5) ppm. 13C NMR (100 MHz, CDCl3): δ = –0.8, 0.6, 1.3, 32.3,
oil. 1H NMR (300 MHz, CDCl3): δ = 0.07–0.17 [m, 12 H, 2ϫ 34.3, 62.2, 65.2, 126.1, 128.7 ppm. GC–MS: tR = 15.34 min.
Si(CH3)2], 0.88–0.90 (t, J = 6.8 Hz, 18 H, CH3), 1.16 (d, J = 6.2 Hz,
9 H, CH3), 1.25–1.39 (m, 28 H, CH2), 1.53–1.58 (m, 10 H, CH,
1,1,3,3-Tetramethyl-1,3-bis(octan-2-yloxy)disiloxane (11b): Color-
less oil. H NMR (300 MHz, CDCl3): δ = 0.07–0.17 [m, 12 H, 2ϫ
1
CH2) ppm. 13C NMR (100 MHz, CDCl3): δ = –0.8, 0.0, 1.3, 14.4,
Si(CH3)2], 0.88 (m, 6 H, CH3), 1.16 (d, J = 6.0 Hz, 6 H, CH3),
23.0, 24.0, 25.8, 28.4, 32.0, 32.9, 39.6, 62.7, 68.7 ppm. GC–MS: tR
1.22–1.37 (m, 2 H, CH2=CH), 1.45–1.67 (m, 2 H, CH2), 3.85–3.95
= 8.2 (2c), 8.59 (2d), 9.04 min (2b).
(m, 1 H, CH) ppm.
1
Cyclooctanol [696–71–9] (3bЈ): Colorless oil. H NMR (300 MHz,
Poly(4-{[(1,1,3,3-Tetramethyldisiloxanyl)oxy]methyl}phenyl)-
CDCl3): δ = 1.39–1.57 (m, 9 H, CH2), 1.62–1.79 (m, 4 H, CH2),
methanol (12b): Colorless oil. 1H NMR (300 MHz, CDCl3): δ =
1.81–1.83 (m, 2 H, CH2), 3.82–3.89 (m, 1 H, CH) ppm. 13C NMR
0.20–0.28 [m, 12 H, 2ϫ Si(CH3)2], 4.88 (s, 4 H, CH2), 7.39–7.41 (s,
(75 MHz, CDCl3): δ = 22.9, 25.4, 27.6, 34.8, 72.2 ppm. GC–MS:
4 H, C6H4) ppm. 13C NMR (100 MHz, CDCl3): δ = –0.6, 1.3, 64.3,
tR = 6.26 min.
126.8, 139.9 ppm. GPC (SEC-multiangle laser light scattering/
1,3-Dibutoxy-1,1,3,3-tetramethyldisiloxane [18043–98–6] (4b): Col-
orless oil. 1H NMR (300 MHz, CDCl3): δ = 0.1 [m, 12 H, 2ϫ
Si(CH3)2], 0.90 (t, J = 7.3 Hz, 6 H, CH3), 1.30–1.38 (sext, J =
7.1 Hz, 4 H, CH2), 1.47–1.56 (quint, J = 6.7 Hz, 4 H, CH2), 3.65
(t, J = 6.6 Hz, 4 H, CH2) ppm. 13C NMR (100 MHz, CDCl3): δ =
–0.8, 1.93, 14.1, 19.3, 35.0, 62.3 ppm. GC–MS: tR = 9.54 min.
refractive index): Mn = 9476, Mw = 17400, IP = 1.83.
1,1,3,3-Tetramethyl-1,3-bis(octan-2-yloxy)disiloxane (15b): Color-
1
less oil. H NMR (300 MHz, CDCl3): δ = 0.07–0.16 [m, 12 H, 2ϫ
Si(CH3)2], 0.88 (t, J = 7.0 Hz, 6 H, CH3), 1.16 (d, J = 6.2 Hz, 6 H,
CH3), 1.22–1.35 (m, 20 H, CH2), 1.83–1.97 (sext., J = 6.0 Hz, 2 H,
CH), 1.95–2.00 (m, 4 H, CH2), 3.70 (t, J = 7.4 Hz, 4 H, CH2), 5.08
(t, J = 7.4 Hz, 2 H, CH2=CH) ppm. 13C NMR (100 MHz, CDCl3):
2,2,4,4-Tetramethyl-1,5-dipentyldisiloxane [191108–98–2] (5b),
1,1,3,3-tetramethyl-1,3-bis(pentan-2-yloxy)disiloxane
(5c),
and δ = –0.1, 0.03, 1.0, 1.3, 14.3, 22.9, 23.7, 26.2, 29.7, 32.2, 39.8,
1,1,3,3-Tetramethyl-1-(pentan-2-yloxy)-3-(pentyloxy)disiloxane (5d):
Colorless oil. 1H NMR (300 MHz, CDCl3): δ = 0.1 [m, 36 H,
Si(CH3)2], 0.90 (t, J = 6.8 Hz, 18 H, CH3), 1.16 (d, J = 6.2 Hz, 9
H, CH3), 1.28–1.38 (m, 24 H, CH2), 1.53–1.58 (m, 8 H, CH2), 3.66
(t, J = 6.8 Hz, 6 H, CH2), 3.89–3.93 (m, 3 H, CH) ppm. 13C NMR
(100 MHz, CDCl3): δ = –0.8, 14.3, 23.0, 24.0, 25.8, 28.3, 32.0, 32.9,
39.6, 62.6, 68.7 ppm. GC–MS: tR = 8.12 (5c), 8.59 (5d), 9.04 min
(5b).
68.7 ppm. GC–MS: tR = 12.14 min.
1,3-Bis(cyclohex-3-en-1-ylmethoxy)-1,1,3,3-tetramethyldisil-
oxane (16b), 1-(Cyclohex-3-en-1-ylmethoxy)-3-(cyclohexylmethoxy)-
1,1,3,3-tetramethyldisiloxane (16c), and 1,3-Bis(cyclohexylmethoxy)-
1,1,3,3-tetramethyldisiloxane (16d): Reaction performed at room
1
temperature for 1 h. Colorless oil. H NMR (300 MHz, CDCl3): δ
= 0.09–0.16 [m, 36 H, Si(CH3)2], 1.19–1.28, 1.65–1.82, 2.01–2.15
(m, 36 H, CH2 and CH), 3.44 and 3.52–3.55 (d and m, J = 6.6 Hz,
12 H, CH2) ppm. GC–MS: tR = 12.54 (16d), 12.65 (16c), 12.75 min
(16b).
1-(Isopentyloxy)-1,1,3,3-tetramethyl-3-(2-methylbutoxy)disiloxane
(6b), 2,2,4,4-Tetramethyl-1,5-bis(3-methylbutyl)disiloxane [131357–
Eur. J. Org. Chem. 2011, 4687–4692
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4691

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FULL PAPER
[18]
[19]
1,3-Bis(cyclohexylmethoxy)-1,1,3,3-tetramethyldisiloxane (16d): Re-
action performed at 50 °C for 18 h. Colorless oil. 1H NMR
(300 MHz, CDCl3): δ = 0.09–0.15 [m, 12 H, Si(CH3)2], 1.16–1.25,
1.46–1.48, 1.68–1.73 (m, 11 H, CH2 and CH), 3.44 (d, J = 6.6 Hz,
4 H, CH2) ppm. 13C NMR (100 MHz, CDCl3): δ = –0.8, 1.3, 26.2,
27.0, 29.9, 40.5, 68.3 ppm. GC–MS: tR = 12.75 min (16b).
[20]
1,3-Bis(cyclohexylmethoxy)-1,1,3,3-tetramethyldisiloxane (16d): Re-
action performed at 50 °C for 18 h. Colorless oil. 1H NMR
(300 MHz, CDCl3): δ = 0.09–0.15 [m, 12 H, Si(CH3)2], 1.16–1.25,
1.60–1.73 (m, 4 H, CH2 and CH), 3.44 (d, J = 6.6 Hz, 4 H,
CH2) ppm. 13C NMR (100 MHz, CDCl3): δ = –0.8, 0.6, 1.3, 26.2,
27.0, 30.0, 68.3 ppm. GC–MS: tR = 12.54 min (16d).
[21]
[22]
[23]
1,1,3,3-Tetramethyl-1,3-diphenoxydisiloxane [116401–29–7] (17b):
Colorless oil. 1H NMR (300 MHz, CDCl3): δ = 0.07–0.38 [m, 12
H, 2ϫ Si(CH3)2], 6.83 (d, J = 6.4 Hz, 4 H, CH), 6.91 (t, J = 7.3 Hz,
2 H, CH), 7.20–7.27 (m, 4 H, CH) ppm. 13C NMR (100 MHz,
CDCl3): δ = –0.3, 1.2, 115.7, 120.9, 129.9, 155.8 ppm. GC–MS: tR
= 11.67 min.
3-[(1,1,3,3-Tetramethyldisiloxanyl)oxy]propan-1-ol (18b): Colorless
oil. 1H NMR (300 MHz, CDCl3): δ = 0.08–0.13 [m, 12 H, 2ϫ
Si(CH3)2], 1.77 (quint, J = 6.2 Hz, 2 H, CH2), 3.79 (t, J = 6.2 Hz,
4 H, CH2) ppm. 13C NMR (100 MHz, CDCl3): δ = –0.9, 1.0, 34.4,
61.2 ppm. GPC (polystyrene equivalent): Mn = 1348, Mw = 1825,
IP = 1.35.
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Received: April 6, 2011
Published Online: June 28, 2011
4692
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 4687–4692