New straightforward route for the synthesis of some 1-oxa-2- silacyclopentane derivatives

Article abstract of DOI:10.1002/jhet.5570450215

(Chemical Equation Presented) Tris(dimethylsilyl)methyl lithium, (HSiMe₂)₃CLi, reacts with allyl, phenyl, benzyl, n-propyl and n-butyl glycidyl ethers in THF at -5°C to give 1-oxa-2-silacyclopentane derivatives. It seems that ring cl

Full text of DOI:10.1002/jhet.5570450215

Mar-Apr 2008
389
New straightforward Route for the Synthesis of Some 1-Oxa-2-
Silacyclopentane Derivatives
Kazem D. Safa*, Mohammad Shahrivar, Shahin Tofangdarzadeh, Akbar Hassanpour
Organosilicon Research Laboratory, Faculty of Chemistry, Tabriz University, 51664 Tabriz, Iran
*Corresponding author. Tel: +98 –411-3393124; fax: +98- 411– 3340191 E –Mail: dsafa@tabrizu.ac.ir
Received May 20, 2007
O
SiMe2H
Mg
R
LDA
(HSiMe2)3C-CH2-CHR-OH
+
HSiMe2Cl
CHBr3
(HSiMe2)3CH
HMe2Si
Li
THF
SiMe2H
(8)
O
R
HMe2Si
HMe2Si
Me
Si
R
O
Me
(7)
Tris(dimethylsilyl)methyl lithium, (HSiMe2)3CLi, reacts with allyl, phenyl, benzyl, n-propyl and n-butyl
glycidyl ethers in THF at -5 °C to give 1-oxa-2-silacyclopentane derivatives. It seems that ring closure is
facilitated by conversion of the Si-H bond into an Si-O bond. Glycidyl methacrylate (GM) random
copolymers with 4-methyl- and 4-methoxy styrene, synthesized by solution free radical polymerization at
70 (±1) °C with α,α-azobis(isobutyronitrile) (AIBN) as initiator, contained pendant epoxide functions.
Treatment of these with (HSiMe2)3CLi did not lead to intramolecular nucleophilic attack as found for
simple epoxides.
J. Heterocyclic Chem., 45, 389 (2008).
intramolecular bis-silylation [15] of alkenes promoted by
palladium isocyanide catalyst. Treatment of
INTRODUCTION
a
Silicon-substituted alkyllithium compounds, in partic-
ular (Me3Si)3CLi have been used to synthesis organic
compounds containing very bulky substituents, many of
which possess unique structures and display novel
reactivity [1-3]. It is also known that [(HSiMe2)3-
CLi].2THF is formed in excellent yield from the reaction
of (HSiMe2)3CH with (Me2CH)2NLi in THF [4].
Attachment of tris(trimethylsilyl)methyl groups to
macromolecular chains leads to important modifications
of polymer properties such as potential membrane
materials in separation processes and an increase in glass
transition temperature [5-6].
(HSiMe2)3CLi with some simple epoxides gave 3,3-bis-
(dimethylsilyl)-1-oxa-2-silacyclopentanes in an unusual
but straightforward process [17]. To seek more evidence
for the proposed mechanism we studied the reaction of
[(HSiMe2)3CLi].2THF with some other epoxides and
polymers containing epoxy groups on the side chain.
Scheme 1
H2PtCl6
Me2HSiOCMe2CH=CH2
Me2HSi(CH2)3OH
O
O
Me2SiCl2
n-
Bu2Sn
Si
1-Oxa-2-silacyclopentanes are powerful intermediates
in organic synthesis, since they can be readily converted
into diols after oxidation of the carbon-silicon bond [7].
These useful intermediates can be prepared by dehydro-
genation [8], intramolecular hydrosilylation [9], extrusion
of isocyanates [10], elimination of dibutyltin chloride
from the 2-oxastannacyclopentane by reaction with
dimethyldichlorosilane [11], cyclization of (ω-ethoxy-
silylalkoxy)trimethylsilanes [12] (Scheme 1), insertion of
carbonyl groups to oxasilacyclopropane [13,14], and
O
-Me3SiOEt3
O
(Et)nMe3-nSi(CH2)mOSiMe3
n= 1- 3; m= 3, 4
Si
N
Me
RESULTS AND DISCUSSION
It was shown previously that the reaction of
(Me3Si)3CLi with ethylene oxide gave the alcohol 2,

390
K. D. Safa, M. Shahrivar, S. Tofangdarzadeh, A. Hassanpour
Vol 45
which reacted with sodium hydride in THF to yield the
silyl ether 4 and hence, by hydrolysis, the alcohol 5,
which has one fewer silyl group. The silicon transfer 3 →
4 → 5 takes ca. 90 min at room temperature. Potassium t-
butoxide in THF worked comparably well, but the lithium
and magnesium alkoxides did not react [16] (Scheme 2).
in THF but the products were 1-oxa-2-silacyclopentane
derivatives rather than the expected compounds
(HMe2Si)3CCH2CHROH (8). For example, when the
solution of (HMe2Si)3CLi was quenched with allyl
glycidyl ether at -5 °C in THF the color of the solution
changed gradually from deep-red to yellow during the
addition of the epoxide. In this reaction, because of the
existence of the Si-H bond, an intramolecular
alkoxylation takes place (Scheme 3).
Scheme 2
-
O Na
+
The IR spectra of 7a showed no peak above 3300
cm-1 as expected if an alcohol had been formed. A
typical H NMR spectrum (Figure 1) for this product
Me3Si
OH
SiMe3
OSiMe3
NaH
THF
-
Me3Si
1
Me3Si
Me3Si
SiMe3
showed three separate signals; a multiplet at 0.11-0.17
ppm for 12 protons (a) and two singlets at 0.18, 0.30
ppm for 6 protons (b, c). There was no broad peak
corresponding to the OH group. Integration of the area
peak at 4.04-4.14 corresponding to the Si-H bond
showed two protons for the Si-H bond instead of three
protons which clearly indicate liberation of a hydride
ion. In the 13C NMR spectrum, the resonance signals
(b1, b2) at -0.7 and 0.2 ppm were due to the (CH3)2SiO
and four resonance signals at -4.2, -3.9, -3.7 and -3.4
ppm (a1), (a2), (a3) and (a4) related to four different
CH3 of two SiMe2H groups respectively (Figure 1). All
these results clearly show that the ring opening
reaction led to cyclic compound 7a instead of the
expected related alcohol.
SiMe3
(3)
SiMe3
(4)
(2)
O
THF 0 °C
30 min
THF
Me3Si
Me3Si
OH
SiMe3
Li
Me3Si
SiMe3
(5)
(1)
The compound (HSiMe2)3CH was made by treatment
of CHBr3 with HMe2SiCl in the presence of magnesium
[18]. The deep-red solution of the nucleophilic reagent
(HSiMe2)3CLi [4] was prepared from the reaction of
(HMe2Si)3CH
with
a
solution
of
lithium
diisopropylamide (LDA) in THF for 6 h at room
temperature. The solvated organolithium reacted with
allyl, phenyl, benzyl, propyl, and butyl glycidyl ethers
Scheme 3
O
SiMe2H
Li
LDA
R
Mg
THF
HMe2Si
+
CHBr3
HSiMe2Cl
(HSiMe2)3CH
(HSiMe2)3C-CH2-CHR-OH
SiMe2H
(8)
O
R= CH2OCH2CH=CH2, CH2OPh,
CH2OCH2Ph, CH2OPr, CH2OBu
R
HMe2Si
HMe2Si
HMe2Si
HMe2Si
H
Me
a = CH2OCH2CH=CH2
b = CH2OPh
c = CH2OCH2Ph
H
Si
Me
H
-LiH
Si
R
O
R
O
-
Me
(7)
Me
d = CH2OPr
e = CH2OBu

Mar-Apr 2008 New straightforward Route for the Synthesis of Some 1-Oxa-2-Silacyclopentane Derivatives
391
Figure 1. 1H and 13C NMR of the compound 7a in CDCl3 without tetramethylsilane.
Scheme 4
CH2 CH
CH3
CH2
C
AIBN, toluene
70 °C
+
COCH
2CH CH2
O
O
CH3
X
(
)
CH2
)
m
CH2
C
C
CH
(
CH3
n
OH
(HSiMe ) CLi
2 3
1)
O
)
(
CH2
CH
)
m
(
C
CH2
n
THF
2) MeOH
-5 °C
CHCHCH2O
Me
C
O
H2C
CHCH2O
Me
O
H
Si
Si
H
X
Si
H
Me
Me
Me
Me
X
I X= Me
II X=OMe
II-SiH X=OMe
I-SiH X=Me
functional polymers. The interest in these polymers is
largely due to the presence of the reactive epoxide ring,
Poly glycidyl methacrylate (PGM) and its copolymers
have been widely used as precursors for the synthesis of

392
K. D. Safa, M. Shahrivar, S. Tofangdarzadeh, A. Hassanpour
Vol 45
which can enter into wide range of chemical reactions. To
examine the possibility of the formation of oxasilacyclo-
pentane ring on the side chain of polymers, GM monomer
was copolymerized with 4-methyl and 4-methoxy styrene
at 70(±1) °C using AIBN as the radical initiator
(Scheme 4). The composition, molecular weight, mole
fraction of GM in the copolymers (obtained by 1H NMR),
and yield of the copolymers (I, II) are listed in Table 1.
The resulting polymers are white solids and soluble in
chloroform, dichloromethane, benzene, toluene, xylene,
THF, N,N-dimethyl formamide and dimethyl sulfoxide
and insoluble in n-hexane, methanol, ethanol and water.
After standing for a long period of time even at room
temperature, the GM copolymers become insoluble in
organic solvents, probably due to intramolecular cross
linking between epoxy units.
Poly glycidyl methacrylate (PGM) and its copolymers
have been widely used as precursors for the synthesis of
functional polymers. The interest in these polymers is
largely due to the presence of the reactive epoxide ring,
which can enter into wide range of chemical reactions. To
examine the possibility of the formation of oxasilacyclo-
pentane ring on the side chain of polymers, GM monomer
was copolymerized with 4-methyl and 4-methoxy styrene
at 70(±1) °C using AIBN as the radical initiator
(Scheme 4). The composition, molecular weight, mole
fraction of GM in the copolymers (obtained by 1H NMR),
and yield of the copolymers (I, II) are listed in Table 1.
Table 1
Compositions, molecular weights and yields of copolymers (I, II).
b
b
Copolymer
Mn
×103
Mw
×103
Mw/Mn
Mol% GM a
Weight
(g)
Yield
(%)
Poly(GM-co-MSt)1:1(I)
29.5
19.1
53.8
38.8
1.80
2.03
50
41
3.77
3.93
83
80
Poly(GM-co-OMeSt)1:1(II)
a Mol% of both monomers were obtained via 1H NMR; b Molecular weight was obtained by GPC analysis.
Figure 2. 1H-NMR spectra: (A) I and (B) I-SiH in CDCl3 without tetramethylsilane.

Mar-Apr 2008 New straightforward Route for the Synthesis of Some 1-Oxa-2-Silacyclopentane Derivatives
393
The resulting polymers are white solids and soluble in
chloroform, dichloromethane, benzene, toluene, xylene,
THF, N,N-dimethyl formamide and dimethyl sulfoxide
and insoluble in n-hexane, methanol, ethanol and water.
After standing for a long period of time even at room
temperature, the GM copolymers become insoluble in
organic solvents, probably due to intramolecular cross
linking between epoxy units.
The copolymers (I, II) were treated with (HSiMe2)3CLi
with the expectation that 1-oxa-2-silacyclopentane side
chain copolymers would be formed, but FT-IR spectra of
the resulting copolymers showed the broad band
characteristic of hydroxyl groups at wave number 3500
cm-1, a sign of hydroxyl formation following the breaking
of the epoxy ring. 1H NMR spectra indicated a singlet for
18 protons of the (HSiMe2)3C- group (Figure 2). It seems
possible that the high rigidity of the copolymers in
comparison to simple monomer inhibits intramolecular
reaction.
EXPERIMENTAL
Solvents and reagents. The reactions involving
organolithium reagents were carried out under dry argon
atmosphere. Solvents were dried by standard methods. Glycidyl
methacrylate (GM) (Merck) and 4-methyl- and 4-methoxy
styrene (Merck) were distillated under reduced pressure to
remove inhibitors before use and AIBN (Merck) was purified by
crystallization from methanol.
Spectra. The H NMR and 13C NMR were recorded with a
1
NMR Bruker FT-400 MHz spectrometer at room temperature
with CDCl3 as a solvent. The mass spectra were obtained with
Finnigan-Mat model 8400, operating at 70 eV. The IR spectra
were recorded on a FT-IR, Bruker-Tensor 270 spectrometer.
Elemental analyses were carried out with Heareus CHN-RAPID
instrument. The molecular weights (Mw and Mn) were
determined using a waters 501 gel permeation chromatograph
fitted with 102 and 103 nm Waters Styragel columns. THF was
used as an elution solvent at a flow rate of 1 ml/min and
polystyrene standards were employed for calibration.
Copolymerization of glycidyl methacrylate (GM) with 4-
methyl styrene and 4-methoxy styrene copolymer (I, II). A
mixture of GM (2.84 g, 20 mmol), AIBN (0.06 g, 0.4 mmol), 4-
methyl styrene (2.36 g, 20 mmol) or 4-methoxy styrene (2.68 g,
20 mmol) was dissolved in toluene (15 ml) in a glass ampoule.
The solution was degassed, and the ampoule sealed under
vacuum and shaken at 70(±1) °C. The viscous solution was
poured from the ampoule into 150 ml of cooled methanol. The
precipitate was collected and washed with cooled acidic
methanol several times and dried under vacuum at room
temperature. For copolymer I: νmax/cm-1 3018 (Ar-H), 2922, 2850
(R-H), 1730 (C=O), 1650, 1488 (C=C), 1110 (C-O), 907, 846
(C-O epoxide); δH (400 MHz, CDCl3) 0.58-2.24 (CH2-CH,α-
Me), 2.3 (Ar-CH3) 2.5-3.4 (epoxide),3.5(OH), 3.7 (COOCH2),
6.6-7.2 (Ar). For copolymer II: νmax/cm-1 3025 (Ar-H), 2994,
2840 (R-H), 1727 (C=O), 1613, 1456 (C=C), 1180, 1032 (C-O),
907, 784 (C-O epoxide); δH (400 MHz, CDCl3) 0.6-1.7 (CH2-
CH,α-Me) 2.5-3.3 (epoxide), 3.6 (OMe), 3.8 (COOCH2), 7.1-7.2
(Ar).
CONCLUSION
The reaction of epoxides with trisilylmethyllithium
reagents bearing hydride groups on silicon gives oxasil-
acyclopentane products, which presumably by cyclization
of the intermediate lithium alkoxide onto silicon with loss
of a hydride leaving group. These transformations are
quite different from those observed with the trimethylsilyl
analogues. It is likely that the initial step of (HSiMe2)3CLi
reaction with epoxides proceeds via nucleophilic attack at
the uncrowded carbon of the epoxides yielding 6 as
intermediate. The intramolecular reaction between the Si-
H and OLi groups of 6 results in ring closure and the
formation of cyclic product 7 (Scheme 5). In contrast, the
reactions of tris(trimethylsilyl)methyl group with
epoxides lead only to alcohols. It is probable that the ease
of ring closure of epoxide with tris(dimethylsilyl)methyl
group is due to the existence of the Si-H bond and the
enhancement of reactivity of the Si-H bond towards
nucleophiles. It also seemed that the high rigidity of the
copolymers makes them unfavorable towards intra-
molecular nucleophilic attack.
The ring opening reaction between the epoxy groups of
Poly (GM-co-4-MeSt) and Poly (GM-co-4-MeOSt) with
(HSiMe2)3CLi (ISi-H, IISi-H). A solution of copolymer I (0.5
g, with 1.92 mmol of epoxy-containing monomer units) or
copolymer II (0.5 g, with 1.5 mmol of epoxy-containing
monomer units) in THF (30 ml) was transferred into dropping
funnel under an argon atmosphere and added dropwise to a
stirred solution of a (HSiMe2)3CLi (2 g, 10.5 mmol) at -5 °C.
Scheme 5
H
Me
Me
HMe2Si
HMe2Si
HMe2Si
HMe2Si
Me
Me
Si
O
+
Li
H
H
Si
Me
H
Me
H
Si
Si
R
Si
H
R
Me
Me
R
O
O
-
Me
Me
(6)
(7)

394
K. D. Safa, M. Shahrivar, S. Tofangdarzadeh, A. Hassanpour
Vol 45
57 % yield from benzyl glycidyl ether (5.1 g, 31.6 mmol) and
(HSiMe2)3CLi (15.8 mmol) during 3 h at -5 °C as a colorless
liquid purified by preparative TLC (silica gel, 1: 1 n-hexane:
CH2Cl2, Rf = 0.60). νmax/cm-1 2108 (Si-H), 1251, 837 (Si-CH3),
1043 (Si-O-C), 1595, 1532 (C=C); δH (400 MHz, CDCl3) 0.12-
0.24 (m, 12H, HSi(CH3)2), 0.26, 0.39 (2s, 2×3H, OSi(CH3)2),
1.85, 2.25 (2×d-d, 2×1H, J= 12.3, 10.4, CCH2CH), 3.93-4.00 (m,
2H, Si-H), 4.34-4.41 (m, 1H, CH2CHO), 4.20 (d, 2H, J= 4.1 Hz,
CH2OCH2Ph), 4.57 (s, 2H, OCH2Ph), 7.27-7.32 (m, 5H, OCH2Ph);
δC (CDCl3) -4.1, -3.7, -3.6, -3.4 (HSi(CH3)2), -0.8, 0.2 (OSi(CH3)2),
4.0 (CCH2CH), 33.3 (CCH2CH), 72.6 (CH2OCH2Ph), 73.8
(OCH2Ph), 80.9 (CH2CHO), 114.51, 114.54, 118.8, 119.3,
131.2, 136.1 (Ph); m/z (EI) 353 (4%, [M]+), 338 (19%, [M-
Me]+), 294 (43%, [M-(HSiMe2)]+). Anal. Cal. for C17H32Si3O2:
C, 57.9; H, 9.1. Found: C, 57.6; H, 9.1%.
The reaction was quenched by addition of a small amount of
acidic methanol after 3 h, and the reaction mixture was poured
into cooled acidic methanol to precipitate the polymer. For
copolymer I-SiH: νmax/cm-1 3443 (OH), 3066 (Ar-H), 2956 (R-
H), 2110 (Si-H), 1728 (C=O), 1257, 850 (C-Si), 1034 (C-O); δH
(400 MHz, CDCl3) δ -0.2(Si-Me), 0.56-2.0 (CH2-CH,α-Me), 2.3
(Ar-CH3), 3.7 (COOCH2), 4.0(Si-H), 6.6-7.2 (Ar). For
copolymer II-SiH: νmax/cm-1 3443 (OH), 3066 (Ar-H), 2956 (R-
H), 2110 (Si-H), 1728 (C=O), 1257, 850 (C-Si), 1034 (C-O); δH
(400 MHz, CDCl3) δ 0.1(Si-Me), 0.6-1.7 (CH2-CH, α-Me) , 3.4
(OH), 3.6 (OMe), 4 (Si-H), 7.0-7.2 (Ar).
General procedure for reactions of tris(dimethylsilyl)-
methyllithium with epoxides. Epoxides were added dropwise to
a solution of tris(dimethylsilyl)methyllithium (15.8 mmol) at -5
°C and the mixtures kept for 1 h at this temperature, then the
mixtures were poured into ice-cold solution. The organic layer
was separated and the aqueous layer was extracted twice with
100 ml ether. The organic layers were combined and washed
twice with 50 ml 2 N aqueous hydrochloric acid, twice with 50
ml distilled water and once with 50 ml saturated aqueous sodium
chloride solution. The clear yellow organic layer was dried over
anhydrous sodium sulfate and filtered. The solvent was
evaporated and the product obtained by preparative TLC (Silica
gel).
Preparation of 3,3-bis(dimethylsilyl)-2,2-dimethyl-5-allyl-
oxymethyl-1-oxa-2-sila-cyclopentane (7a). The reaction of
allyl glycidyl ether (3.6 g, 31.6 mmol) with (HSiMe2)3CLi (15.8
mmol) for 3 h at -5 °C gave 7a. A colorless liquid (Yield 61%)
was obtained by preparative TLC (silica gel, 1: 1 n-hexane:
CH2Cl2, Rf = 0.70). νmax/cm-1 2105 (Si-H), 1255, 829 (Si-CH3),
1070 (Si-O-C), 1496, 1633 (C=C); δH (400 MHz, CDCl3) 0.12-
0.17 (m, 12H, HSi(CH3)2, 0.18, 0.30 (2s, 2×3H, OSi(CH3)2),
1.76, 2.08 (2×d-d, 2×1H, J= 12.2, 10.1 Hz, CCH2), 3.40 (d, 2H,
J= 4.3, CH2OCH2CH=CH2), 3.92-3.98 (m, 1H, CH2CHOSiMe2),
4.04-4.14 (m, 2H, Si-H), 5.13, 5.22 (2×d-d, 2×1H, J= 6.0, 6.0
Hz, CH=CH2), 5.26 (d, 2H, J= 15.5, CH2CH=CH2), 5.84-5.93
(m, 1H, CH=CH2); δC (CDCl3) -4.2, -3.9, -3.7, -3.4 (HSi(CH3)2),
-0.7, 0.2 (OSi(CH3)2), 3.9 (CCH2CH), 33.4 (CCH2CH), 71.4
(CH2CHO), 73.8 (CH2OCH2CH=CH2), 74.5 (CH2CH=CH2),
115.9 (CH=CH2), 133.7 (CH=CH2); m/z (EI) 302 (6%, [M]+),
287 (21%, [M-Me]+), 243 (48%, [M-(HSiMe2)]+). Anal. Cal. for
C13H30Si3O2: C, 51.6; H, 9.9. Found: C, 51.4; H, 10.0%.
Preparation of 3, 3-bis(dimethylsilyl)-2, 2 -dimethyl-5-phen-
oxymethyl-1-oxa-2-sila-cyclopentane (7b). Similarly 7b was
obtained in 52% yield from phenyl glycidyl ether (4.7 g, 31.6
mmol) and (HSiMe2)3CLi (15.8 mmol) during 3 h at -5 °C and
isolated as a colorless liquid by preparative TLC (silica gel, 1: 1
n-hexane: CH2Cl2, Rf = 0.60). νmax/cm-1 2109 (Si-H), 1255, 833
(Si-CH3), 1054 (Si-O-C), 1628, 1542 (C=C); δH (400 MHz,
CDCl3) 0.14-0.25 (m, 12H, HSi(CH3)2), 0.27, 0.40 (2s, 2×3H,
OSi(CH3)2), 1.98, 2.25 (2×d-d, 2×1H, J=12.0, 10.1 Hz,
CCH2CH), 3.93-4.01 (m, 2H, Si-H), 4.19 (d, 2H, J= 4.2,
CH2OPh), 4.34-4.41 (m, 1H, CH2CHO), 6.91-7.00 (m, 3H, Ph),
7.26-7.32 (m, 2H, Ph); δC (CDCl3) -4.2, -3.8, -3.7, -3.4
(HSi(CH3)2), -0.6, 0.2 (OSi(CH3)2), 4.0 (CCH2CH), 33.4
(CCH2CH), 71.2 (CH2CHO), 73.8 (CH2OPh), 113.50, 113.53,
119.7, 120.1, 128.3, 158.4 (Ph); m/z (EI) 339 (4%, [M]+), 324
(19%, [M-Me]+), 280 (47%, [M-(HSiMe2)]+). Anal. Cal. for
C16H30Si3O2: C, 56.7; H, 8.9. Found: C, 56.6; H, 8.9%.
Preparation of 3, 3-bis(dimethylsilyl)-2, 2-dimethyl-5-propyl-
oxymethyl-1-oxa-2- sila-cyclopentane (7d). n-Propyl glycidyl
ether (3.6 g, 31.6 mmol) was treated with (HSiMe2)3CLi (15.8
mmol) at -5 °C for 2 h to give 7d in 58% yield and the colorless
liquid was purified by preparative TLC (silica gel, 1: 1 n-
hexane: CH2Cl2, Rf = 0.75). νmax/cm-1 2106 (Si-H), 1261, 834 (Si-
CH3), 1076 (Si-O-C); δH (400 MHz, CDCl3) 0.11-0.18 (m, 12H,
HSi(CH3)2), 0.20, 0.29 (2s, 2×3H, OSi(CH3)2), 0.86 (t, 3H, J=
12.2 Hz, CH2CH3), 1.24-1.31 (m, 2H, CH2CH3), 1.66, 2.10 (2×d-
d, 2×1H, J= 12.1, 8.0 Hz, CCH2CH), 3.50 (t, 2H, J= 12.0 Hz,
OCH2CH2), 3.77 (d, 2H, J= 8.0 Hz, CH2OPr), 3.86-3.94 (m, 1H,
CH2CHO), 4.04-4.13 (m, 2H, Si-H); δC (CDCl3) -4.5, -4.1, -3.9,
-3.6 (HSi(CH3)2), -0.9, 0.5 (OSi(CH3)2), 4.2 (CCH2CH), 12.1
(CH3), 24.3 (CH2CH3), 36.1 (CCH2CH), 73.3 (CH2CH2CH3),
83.3 (CH2CHO), 87.1 (CH2OPr); m/z (EI) 304 (6%, [M]+), 289
(20%, [M-Me]+), 245 (46%, [M-(HSiMe2)]+). Anal. Cal. for
C13H32Si3O2: C, 51.2; H, 10.5. Found: C, 51.4; H, 10.1%.
Preparation of 3, 3-bis(dimethylsilyl)-2,2-dimethyl-5-butyl-
oxymethyl-1-oxa-2- sila-cyclopentane (7e). n-Butyl glycidyl
ether (4.1 g, 31.6 mmol) was treated with (HSiMe2)3CLi (15.8
mmol) at -5 °C for 2 h to give 7e in 56% yield, and purified by
preparative TLC (silica gel, 1: 1 n-hexane: CH2Cl2, Rf = 0.80). A
pure colorless liquid was obtained. νmax/cm-1 2104 (Si-H), 1258,
833 (Si-CH3), 1073 (Si-O-C); δH (400 MHz, CDCl3) 0.10-0.18
(m, 12H, HSi(CH3)2), 0.19, 0.28 (2s, 2×3H, OSi(CH3)2), 0.85 (t,
3H, J= 12.1 Hz, CH2CH3), 1.28-1.37 (m, 2H, CH2CH3), 1.38-
1.43 (m, 2H, CH2CH2CH3), 1.67, 2.12 (2×d-d, 2×1H, J= 12.2,
8.1 Hz, CCH2CH), 3.54 (t, 2H, J= 12.4 Hz, OCH2CH2CH2), 3.75
(d, 2H, J= 8 Hz, CH2OCH2CH2), 3.87-3.92 (m, 1H, CH2CHO),
4.04-4.14 (m, 2H, Si-H); δC (CDCl3) -4.4, -4.0, -3.8, -3.5
(HSi(CH3)2), -0.8, 0.4 (OSi(CH3)2), 4.1 (CCH2CH), 14.1
(CH2CH3), 20.4 (CH2CH3), 33.0 (CH2CH2CH3), 36.1 (CCH2CH),
66.3 (CH2CH2CH2), 74.1 (CH2CHO), 76.9 (CH2OCH2CH2); m/z
(EI) 318 (8%, [M]+), 303 (25%, [M-Me]+), 259 (44%, [M-
(HSiMe2)]+). Anal. Cal. for C14H34Si3O2: C, 52.7; H, 10.7.
Found: C, 51.4; H, 10.9%.
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