An efficient synthesis of unsymmetrical 1,1-bis (silyl)ethenes

Article abstract of DOI:10.1055/s-2006-926406

A new convenient and effective method for the synthesis of unsymmetrical 1,1-bis(silyl)ethenes is described. The synthetic methodology involves selective silylative coupling cyclization of N-methyl-N-(dimethylvinylsilyl)-2- (dimethylvinylsilyloxy)ethanamine catalyzed by a ruthenium hydride complex and subsequent one-pot reaction of the cyclic bis(silyl)derivative with Grignard reagents followed by alcoholysis. As a result, a variety of 1,1-bis(silyl) ethenes containing different substituents at the silicon atoms were produced in regiocontrolled manner with considerably high efficiency. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2006-926406

1370
PAPER
An Efficient Synthesis of Unsymmetrical 1,1-Bis(silyl)ethenes
Synthesisof
U
nsym
r
metrica
z
l
1,1-Bis(
s
e
ilyl)ethenesgorz Hreczycho, Piotr Pawluć, Bogdan Marciniec*
Department of Organometallic Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland
Fax +48(61)8291508; E-mail: marcinb@amu.edu.pl
Received 17 October 2005; revised 8 December 2005
second vinylsilane (or other olefin) molecule. The mech-
Abstract: A new convenient and effective method for the synthesis
anism of this reaction (Scheme 1) involving b-silyl elimi-
of unsymmetrical 1,1-bis(silyl)ethenes is described. The synthetic
methodology involves selective silylative coupling cyclization of
N-methyl-N-(dimethylvinylsilyl)-2-(dimethylvinylsilyloxy)ethan-
nation and insertion of a C=C double bond into the
resulting M–Si bond has been proved by insertion of eth-
amine catalyzed by a ruthenium hydride complex and subsequent ylene and vinylsilane into M–Si (where M = Ru, Rh, Co)
one-pot reaction of the cyclic bis(silyl)derivative with Grignard re-
bonds as well as by a series of elaborate mass spectromet-
ric studies with deuterated styrene and vinylsilanes.6
agents followed by alcoholysis. As a result, a variety of 1,1-bis(si-
lyl)ethenes containing different substituents at the silicon atoms
were produced in regiocontrolled manner with considerably high
efficiency.
SiR3
SiR3
SiR3
[Ru] H
+
SiR3
R3Si
Key words: vinylsilanes, silylative coupling, amino alcohol, Grig-
nard reactions, organometallic reagents
H H
H
H
R3Si
[Ru]
H
SiR3
H SiR3
SiR3
[Ru]
H
SiR3
Vinylsilanes are important synthetic intermediates in ste-
reocontrolled organic synthesis.1 Due to similar properties
of 1,1-bis(silyl)alkenes to those of vinylsilanes, they have
gained significant attention as potential intermediates in
the organic and organosilicon syntheses.2 The potential
use of the 1,1-bis(silyl)alkenes as precursors for the prep-
aration of ketones and isoxazoline derivatives as well as a
variety of important organosilicon intermediates such as
acylsilanes, epoxysilanes, silanols, etc., has greatly stimu-
lated their synthetic advancements.3
[Ru]
H
H H
SiR3
[Ru]
SiR3
[Ru] = RuHCl(CO)(PR3)n
Scheme 1 Silylative coupling reaction mechanism
To date however, the complexity of 1,1-bis(silyl)alkene
synthesis has been limiting their use as synthetic precur-
sors. Unsymmetrical 1,1-bis(silyl)ethenes have been pre-
viously prepared by multistep reactions involving
commercially unavailable substrates, e.g. dihalodisilyl-
methanes or 1-halo-1-silylethenes.4 Application of these
methods are limited not only by complicated synthetic
procedures involving the use of harmful starting materials
and very reactive organolithium compounds, but also by
only moderate yields of the obtained products.3c,4 There-
fore, in view of the growing interest in 1,1-bis(si-
lyl)ethenes, the development of more efficient and
straightforward synthetic methods is of great significance.
The notable peculiarity of silylative coupling reaction,
distinguishing it from cross-metathesis, which starts with
the same substrates, is the formation of 1,1-bis(si-
lyl)ethene fragment under the given conditions.6b Previ-
ous reports have shown that silylative coupling reactions
of divinyl-substituted organosilicon monomers catalyzed
by ruthenium and rhodium complexes under optimum
conditions yielded silacyclic compounds containing exo-
methylene bond between silicon atoms.7
We have recently reported a new facile and efficient pro-
tocol for the synthesis of alkyl-, aryl-, alkenyl- or alkoxy-
substituted symmetrical 1,1-bis(silyl)ethenes using cyclic
silyl ether or cyclic silyl amine selectively obtained via ru-
thenium-catalyzed silylative coupling cyclization of divi-
nyl-substituted monomers, followed by their reaction with
Grignard reagents or alcohols (Scheme 2).8
In the last two decades in the series of our studies we have
developed the silylative coupling reaction of vinylsilane
derivatives in the presence of transition-metal complexes
(e.g. ruthenium and rhodium) initially containing or gen-
erating M–H and M–Si bonds.5 The silylative coupling re-
action of monovinyl organosilicon compounds occurs by
cleavage of the =C–Si bond of the vinyl-substituted sili-
con compound and the activation of the =C–H bond of the
While this reaction sequence leads to a wide range of 1,1-
bis(silyl)ethenes with moderate and high yields, this par-
ticular method cannot be applied to the synthesis of un-
symmetrical bis(silyl) derivatives, which also seem to be
desirable reagents in the organic and organosilicon syn-
theses.
SYNTHESIS 2006, No. 8, pp 1370–1374
x
x
.
x
x
.2
0
0
6
Herein we present the results of our synthetic studies of
unsymmetrical 1,1-bis(silyl)ethenes. The products de-
Advanced online publication: 27.03.2006
DOI: 10.1055/s-2006-926406; Art ID: T14505SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of Unsymmetrical 1,1-Bis(silyl)ethenes
1371
Me
Me
Me
Me
Si
Si
RMgX
ROH
R
R
Me
Me
Me
Me
RuHCl(CO)(PR'3)n
85–92%
Si
Si
X
Me
Me
Me
Me
Si Si
55–88%
X
X
X
Me
Me
Me
Me
X = O, NMe
Si
Si
OR
RO
81–95%
Scheme 2 Synthesis of symmetrical 1,1-bis(silyl)ethenes
sired were obtained via ruthenium complex catalyzed si- vent under argon (glass ampoule), and divinyl-substituted
lylative coupling cyclization of N-methyl-N- compound was exclusively transformed into cyclic prod-
(dimethylvinylsilyl)-2-(dimethylvinylsilyloxy)ethanamine
uct 2 (Equation 2) in 18 hours at 120 °C. The reaction oc-
(1) to give 1-aza-1,2,2,4,4-pentamethyl-3-methylene-5- curred efficiently also in toluene, in the open system,
oxa-2,4-disilacycloheptane (2), followed by the treatment without affecting either the activity of the catalyst or the
of the resulting cyclic product 2 with Grignard reagent, in- selectivity of this process, however, it required a longer
troduction of the alkoxy group via alcoholysis and reac- time (48 h). It is worth noting that the process described
tion with another Grignard reagent.
gives regioselectively cyclic product 2 with no linear oli-
gomeric products observed.
The starting N-methyl-N-(dimethylvinylsilyl)-2-(dimeth-
ylvinylsilyloxy)ethanamine (1) has been conveniently
prepared by the reaction of commercially available and
relatively inexpensive chlorodimethylvinylsilane and 2-
(methylamino)ethanol in the presence of triethylamine in
high yield (94%) as outlined in Equation 1.
Me
Me
Me
Me
Si N
RuH(Cl)(CO)(PCy3)2 (1 mol%)
Si
Si
Me
O Si
Me
Me
Me
Me
N
O
120 °C, 18 h
95%
Me
2
1
Equation 2 Synthesis of 1-aza-1,2,2,4,4-pentamethyl-3-methyl-
ene-5-oxa-2,4-disilacycloheptane
OH
Me
Et3N
+
2
SiMe2Cl
Si N
O Si
Me
Me
Me
Me
pentane, r.t., 2 h
94%
NH
Me
The cyclic product, 1-aza-1,2,2,4,4-pentamethyl-3-meth-
ylene-5-oxa-2,4-disilacycloheptane (2), was easily isolat-
ed by ‘bulb-to-bulb’ distillation from the reaction flask in
95% yield. Results of the spectroscopic analyses (13C
NMR, DEPT) of 2 unambiguously confirmed the exist-
ence of quaternary carbon atom (the signal observed at
157.7 ppm), i.e. 1,1-bis(silyl)ethene fragment in the mol-
ecule.
Inspired by recently reported8 successful transformations
of cyclic products containing exo-methylene bond and ei-
ther SiOR or SiN(Me)R functionalities into symmetrical
1,1-bis(silyl)ethenes, as well as by the difference in the re-
activity of Si–O and Si–N bonds, we envisioned com-
pound 2 as a good substrate candidate for the synthesis of
unsymmetrical 1,1-bis(silyl)ethenes containing both
alkoxy and alkyl (aryl) functionalities.
1
Equation 1 Synthesis of N-methyl-N-(dimethylvinylsilyl)-2-(di-
methylvinylsilyloxy)ethanamine
Two
ruthenium-hydride
complexes,
[Ru-
HCl(CO)(PCy3)2] and [RuHCl(CO)(PPh3)3], have been
recently reported as effective catalysts for selective silyla-
tive coupling cyclization of 1,2-bis(dimethylvinylsily-
loxy)ethane
and
N,N¢-dimethyl-N,N¢-bis(dimethyl-
vinylsilyl)ethane-1,2-diamine.8 Considering the structural
similarity of 1 to earlier reported substrates, one can ex-
pect compound 1 to undergo also the silylative coupling
cyclization catalyzed by ruthenium hydride complexes to
give cyclic bis(silyl) product. The conditions for an effec-
tive transformation of N-methyl-N-(dimethylvinylsilyl)-
2-(dimethylvinylsilyloxy)ethanamine (1) into the 1-aza-
1,2,2,4,4-pentamethyl-3-methylene-5-oxa-2,4-disilacyclo-
heptane (2) in the presence of ruthenium catalysts have
been optimized via catalytic screenings of the substrate
conversion and yield of cyclic product using GC and GC-
MS methods. At 1 mol% catalyst loading the catalysis of
the pentacoordinated ruthenium hydride complex contain-
ing tricyclohexylphosphine, [RuHCl(CO)(PCy3)2], was
found to be more efficient than the catalysis of [Ru-
HCl(CO)(PPh3)3].
To test this hypothesis, we synthesized a series of 1-
(ethoxydimethylsilyl)-1-(organyldimethylsilyl)ethenes.
We found that the treatment of the cyclic compound 2
with 1.2 equivalents of the corresponding Grignard re-
agent in THF at 65 °C for 24 hours and subsequent alco-
holysis with ethanol, yielded unsymmetrical 1,1-
bis(silyl)ethenes containing both alkoxy and alkyl (aryl)
substituents at the silicon atoms (Equation 3) as expected.
Using this procedure we synthesized two new organosili-
con
compounds:
1-(ethoxydimethylsilyl)-1-(bu-
These catalytic results provide a basis for the synthesis of
desired cyclic product from divinyl-substituted monomer
1. Silylative coupling cyclization of 1 was effectively cat-
alyzed by [RuHCl(CO)(PCy3)2] (1 mol%), without sol-
tyldimethylsilyl)ethene (3) (isolated yield 78%) and
1-(ethoxydimethylsilyl)-1-(dimethylphenylsilyl)ethene (4)
(isolated yield 84%).
Synthesis 2006, No. 8, 1370–1374 © Thieme Stuttgart · New York

1372
G. Hreczycho et al.
PAPER
DEPT spectrum analysis. A detailed GC-MS analysis of
the by-products of the reaction discussed revealed the
presence of a small amount (less than 5%) of symmetrical
organosilicon derivatives: (R1Me2Si)2C=CH2 and
(R2Me2Si)2C=CH2, which can be easily separated by col-
umn chromatography.
1) RMgBr,THF, 65 °C, 24 h
2) EtOH, r.t., 1 h
Me
Me
EtO
3 R = nBu (78%)
4 R = Ph (84%)
Me
Me
Me
Me
Si
Si
Si
Si
Me
R
Me
N
O
Me
2
Equation
3
Synthesis of 1-(ethoxydimethylsilyl)-1-(organyldi-
methylsilyl)ethenes.
In conclusion, we have described a novel regioselective
and efficient method for the synthesis of unsymmetrical
1,1-bis(silyl)ethenes from easily available starting materi-
als. Otherwise difficult to synthesize compounds of the
general formula (R1Me2Si)(R2Me2Si)C=CH2 were ob-
tained as predominant products via selective silylative
coupling cyclization of N-methyl-N-(dimethyl-vinylsi-
lyl)-2-(dimethylvinylsilyloxy)ethanamine catalyzed by
ruthenium-hydride complex and subsequent treatment of
the resulted cyclic bis(silyl) derivative with various Grig-
nard reagents.
The structures of these products were confirmed by
DEPT spectrum analysis. Surprisingly, a detailed GC-MS
analysis of the reaction by-products revealed the presence
of small amounts (about 5%) of 1,1-bis(ethoxydimethyl-
silyl)ethene, which can be easily removed by distillation
under reduced pressure.
Consequently we turned our attention towards the one-pot
synthesis of unsymmetrical 1,1-bis(silyl)ethenes contain-
ing alkyl-, alkenyl- or aryl substituents at the silicon at-
oms. These unsymmetrical compounds were formed in
the reaction of 2 with the first Grignard reagent, followed
by alcoholysis and reaction with the second Grignard re-
agent without isolation of the alkoxy-substituted organo-
silicon intermediate (Equation 4). Treatment of 2 with 1.2
equivalents of Grignard reagent R1MgBr in THF at 65 °C
for 24 hours under argon, followed by addition of 1.5
1H NMR (300 MHz) and 13C NMR (75 MHz) spectra were recorded
on a Varian XL 300 spectrometer using CDCl3 as a solvent and
TMS as reference. GC analyses were performed on a Varian 3400
with a Megabore column (30 m) and TCD. Mass spectra of the
products were determined by GC-MS analysis on a Varian Saturn
2100T, equipped with a BD-5 capillary column (30 m) and a Finni-
gan Mat 800 ion trap detector. All reactions were performed under
equivalents of ethanol and subsequent reaction with 2 an atmosphere of deoxygenated and dried argon. Et3N and pentane
equivalents of the second Grignard compound (R2MgBr,)
were dried over CaH2, distilled under argon and stored over molec-
ular sieves type 4A. THF and toluene were dried over sodium and
at 65 °C for 24 hours resulted in the desired 1,1-bis(si-
benzophenone and freshly distilled prior to use. Grignard reagents
lyl)ethenes 5–10 in moderate to good yields (Table 1). To
were synthesized via well-known procedures described in the liter-
obtain the methyl substituted product methylmagnesium
ature. [RuHCl(CO)(PCy3)2] was prepared by adaptation of a proce-
dure described in literature.9
iodide was used. In all cases excellent regioselectivities
were attained.
N-Methyl-N-(dimethylvinylsilyl)-2-(dimethylvinylsilyl-
oxy)ethanamine (1)
1) R1MgBr, THF, 65 °C, 24 h
Me
Me
Me
A solution of anhyd Et3N (28.6 mL, 0.205 mol) in anhyd pentane
(200 mL) was introduced into a flame-dried three-necked, 500-mL
round-bottomed flask equipped with a magnetic stirring bar, rubber
septum cap and argon bubbling tube. To the resulting solution was
added 2-(methylamino)ethanol (7.44 mL, 0.093 mol). Chlorodime-
thylvinylsilane (25.3 mL, 0.186 mol) was subsequently added over
1 h and the mixture was stirred under the flow of argon for 2 h at r.t.
After the substrate disappearance was confirmed by GC, the result-
ing salt was filtered off and the volatiles were removed in a rotary
evaporator. Distillation under reduced pressure afforded compound
1; yield: 21.3 g (94%); colorless liquid; bp 55–57 °C/0.5 mm Hg.
2) EtOH, r.t.,1 h
Me
Me
Me
Me
Si
Si
3) R2MgBr, THF, 65 °C, 24 h
Me
Si
R2
5–10
Si
N
O
R1
Me
2
Equation 4 Synthesis of 1,1-bis(organyldimethylsilyl)ethenes
Table 1 Synthesis of Unsymmetrical 1,1-Bis(organyldimethyl-
silyl)ethenes
Product
R1
R2
Yield (%)a
1H NMR (CDCl3): d = 0.16 (s, 6 H), 0.18 (s, 6 H) 2.43 (s, 3 H), 2.87–
2.92 (t, J = 6.0 Hz, 2 H), 3.51–3.55 (t, J = 6.0 Hz, 2 H), 5.68–5.80
(m, 2 H), 5.91–5.97 (dd, J = 4.4, 14.8 Hz, 2 H), 6.09–6.19 (m 2 H).
13C NMR (CDCl3): d = –2.0, –1.9, 35.3, 53.3, 61.4, 131.9, 133.9,
138.0, 139.7.
MS (EI): m/z (%) = 243 (M+, 3), 228 (5), 159 (5), 143 (5), 128 (100),
117 (7), 85 (45), 73 (5), 59 (20).
HRMS: m/z calcd for C11H25NOSi2 [M+]: 243.14748; found:
243.14759.
5
6
Ph
Me
68
71
63
58
69
63
Ph
Et
7
Ph
n-Bu
Me
8
n-Bu
n-Bu
Ph
9
Et
10
CH=CH2
a Isolated yields of chromatographically pure products.
1-Aza-1,2,2,4,4-pentamethyl-3-methylene-5-oxa-2,4-disila-
cycloheptane (2)
Compound 1 (10.0 g, 0.041 mol) and [RuHCl(CO)(PCy3)2] (0.283
g, 4 × 10–4 mol) were placed in a glass ampoule, which was sealed
under argon and heated for 18 h at 120 °C. After the substrate dis-
appearance was confirmed by GC, the cyclic product was isolated
All products were isolated and spectroscopically charac-
terized. The presence of a quaternary carbon and
(R1Me2Si)(R2Me2Si)C=CH2 structure was elucidated by
Synthesis 2006, No. 8, 1370–1374 © Thieme Stuttgart · New York

PAPER
Synthesis of Unsymmetrical 1,1-Bis(silyl)ethenes
1373
by ‘bulb-to-bulb’ distillation to give compound 2; yield: 8.4 g
(95%); colorless liquid; bp 45 °C/0.5 mm Hg.
1H NMR (CDCl3): d = 0.11 (s, 6 H), 0.13 (s, 6 H), 2.42 (s, 3 H),
2.89–2.92 (t, J = 4.1 Hz, 2 H), 3.68–3.71 (t, J = 4.1 Hz, 2 H), 6.13
(s, 2 H).
13C NMR (CDCl3): d = –2.7, –1.7, 34.9, 54.4, 61.7, 138.8, 132.9,
157.7.
MS (EI): m/z (%) = 215 (M+, 10), 200 (100), 172 (25), 143 (45), 132
(40), 116 (15), 85 (10), 73 (20), 58 (20).
(12 mL) was added dropwise and the mixture was heated at 65 °C
for 24 h. The excess amount of Grignard reagent was quenched by
adding MeOH–Et2O and after adding H2O, the mixture was extract-
ed with Et2O. The ethereal phase was dried (MgSO4) and filtered,
the volatiles removed in a rotary evaporator and the mixture was
passed through a silica gel column (eluent: hexane). After evapora-
tion, the crude product was distilled under reduced pressure to af-
ford the analytically pure product.
1-(Dimethylphenylsilyl)-1-(trimethylsilyl)ethene (5)
Colorless liquid; yield: 68%; bp 92–94 °C/0.5 mm Hg.
1H NMR (CDCl3): d = 0.15 (s, 9 H), 0.54 (s, 6 H), 6.45–6.48 (d,
J = 4.9 Hz, 1 H), 6.54–6.60 (d, J = 4.9 Hz, 1 H), 7.44–7.47 (m, 3 H),
7.62–7.64 (m, 2 H).
13C NMR (CDCl3): d = –1.5, –0.1, 127.5, 128.7, 134.0, 138.9, 141.8,
152.6.
HRMS: m/z calcd for C9H21NOSi2 [M+]: 215.11617; found:
215.11678.
1-(Ethoxydimethylsilyl)-1-(organyldimethylsilyl)ethenes 3 and
4; General Procedure
The glass reactor (50-mL, two-necked, round-bottomed flask
equipped with a magnetic stirring bar, reflux condenser and argon
bubbling tube) was evacuated and flushed with argon. 1-Aza-
1,2,2,4,4-pentamethyl-3-methylene-5-oxa-2,4-disilacycloheptane
(2; 1 equiv) and THF (10 mL) were added to the reactor. Then n-
butylmagnesium (1.2 equiv, 1.3 M in THF) or phenylmagnesium
bromide (1.2 equiv, 2.5 M in THF) was added dropwise. The mix-
ture was refluxed under argon for 24 h. Then at r.t., EtOH (1.5
equiv) was added dropwise. The mixture was stirred under argon for
1 h. After the reaction was complete, the excess of alcohol and the
solvent were evaporated in vacuo. The crude product was distilled
under reduced pressure to afford the analytically pure product.
MS (EI): m/z (%) = 220 (100), 206 (25), 146 (20), 136 (80), 122
(10), 74 (30), 60 (30).
Anal. Calcd for C13H22Si2: C, 66.59; H, 9.46. Found: C, 66.53; H,
9.76.
1-(Ethyldimethylsilyl)-1-(dimethylphenylsilyl)ethene (6)
Colorless liquid; yield: 71%; bp 110 °C/0.5 mm Hg.
1H NMR (CDCl3): d = 0.03 (s, 6 H), 0.44 (s, 6 H), 0.52–0.57 (q,
J = 7.7 Hz, 2 H), 0.89–0.92 (t, J = 7.1 Hz, 3 H), 6.42 (d, J = 5.2 Hz,
1 H), 6.46 (d, J = 5.2 Hz, 1 H), 7.37–7.39 (m, 3 H), 7.53–7.56 (m, 2
H).
13C NMR (CDCl3): d = –2.5, –1.6, 7.5, 7.8, 127.5, 128.7, 133.9,
138.9, 142.3, 151.4.
MS (EI): m/z (%) = 248 (M+, 3), 234 (30), 220 (100), 172 (10), 146
(15), 136 (74), 122 (10), 106 (15), 74 (15), 60 (30).
1-(Butyldimethylsilyl)-1-(ethoxydimethylsilyl)ethene (3)
Colorless liquid; yield: 78%; bp 70–72 °C/0.5 mm Hg.
1H NMR (CDCl3): d = 0.02 (s, 6 H), 0.18 (s, 6 H), 0.42–0.48 (t,
J = 3.3 Hz, 2 H), 0.84–0.89 (t, J = 7.1 Hz, 3 H), 1.06–1.12 (t, J = 6.9
Hz, 3 H), 1.14–1.26 (m, 4 H), 3.52–3.62 (q, J = 6.9 Hz, 2 H), 6.44
(d, J = 5.4 Hz, 1 H), 6.48 (d, J = 5.4 Hz, 1 H).
Anal. Calcd for C14H24Si2: C, 67.66; H, 9.73. Found: C, 67.73; H,
9.95.
13C NMR (CDCl3): d = –2.2, –1.4, 13.7, 15.7, 18.4, 26.1, 26.5, 58.2,
142.0, 151.6.
1-(Butyldimethylsilyl)-1-(dimethylphenylsilyl)ethene (7)
Colorless liquid; yield: 63%; bp 125–127 °C/0.5 mm Hg.
1H NMR (CDCl3): d = 0.01 (s, 6 H), 0.41 (s, 6 H), 0.50–0.52 (t,
J = 3.4 Hz, 2 H), 0.84–0.88 (t, J = 7.1 Hz, 3 H), 1.15–1.30 (m, 4 H),
6.36–6.38 (d, J = 4.9 Hz, 1 H), 6.42–6.43 (d, J = 4.9 Hz, 1 H), 7.35–
7.37 (m, 3 H), 7.50–7.53 (m, 2 H).
13C NMR (CDCl3): d = –2.2, –1.7, 13.8, 15.7, 26.1, 26.5, 127.6,
128.8, 134.0, 139.1, 142.3, 151.8.
MS (EI): m/z (%): 276 (M+, 1), 219 (100), 205 (30), 135 (80), 74
(30), 60 (30).
MS (EI): m/z (%) = 229 (30), 187 (75), 159 (100), 145 (40), 74 (50),
60 (70), 54 (20).
Anal. Calcd for C12H28OSi2: C, 58.94; H, 11.54. Found: C, 58.72;
H, 11.29.
1-(Ethoxydimethylsilyl)-1-(dimethylphenylsilyl)ethene (4)
Colorless liquid; yield: 84%; bp 118 °C/0.5 mm Hg.
1H NMR (CDCl3): d = 0.20 (s, 6 H), 0.46 (s, 6 H) 1.08–1.14 (t,
J = 6.8 Hz, 3 H), 3.56–3.64 (q, J = 7.1 Hz, 2 H), 6.40 (d, J = 5.2 Hz,
1 H), 6.48 (d, J = 5.2 Hz, 1 H), 7.41–7.62 (m, 5 H).
13C NMR (CDCl3): d = –2.6, –1.3, 18.3, 56.2, 127.9, 128.4, 134.7,
137.8, 143.1, 151.6.
Anal. Calcd for C16H28Si2: C, 69.49; H, 10.20. Found: C, 69.42; H,
10.43.
MS (EI): m/z (%) = 250 (45), 235 (15), 219 (20), 188 (30), 144
(100), 136 (90), 103 (40), 76 (30), 46 (35).
1-(Butyldimethylsilyl)-1-(trimethylsilyl)ethene (8)
Colorless liquid; yield: 58%; bp 190–192 °C/760 mm Hg.
Anal. Calcd for C14H24OSi2: C, 63.57; H, 9.15. Found: C, 63.42; H,
9.44.
1H NMR (CDCl3): d = 0.02 (s, 9 H), 0.06 (s, 6 H), 0.42–0.46 (t,
J = 3.6 Hz, 2 H), 0.72–0.77 (t, J = 7.3 Hz, 3 H), 1.05–1.10 (m, 4 H),
6.32–6.35 (d, J = 5.4 Hz, 1 H), 6.44–6.47 (d, J = 5.4 Hz, 1 H).
1,1-Bis(organyldimethylsilyl)ethenes 5–10; General Procedure
The glass reactor (50-mL, two-necked, round-bottomed flask
equipped with a magnetic stirring bar, reflux condenser and argon
bubbling tube) was evacuated and flushed with argon. 1-Aza-
1,2,2,4,4-pentamethyl-3-methylene-5-oxa-2,4-disilacycloheptane
(2; 2g, 1 equiv) and THF (10 mL) were added to the reactor. Then
the corresponding organylmagnesium bromide (R1MgBr, 1.2
equiv) in anhyd THF (7.5 mL) was added dropwise. The mixture
was refluxed under argon for 24 h. After cooling to r.t., EtOH (1.5
equiv) was added dropwise. The mixture was stirred under argon at
r.t. for 1 h. After that time, a solution of R2MgBr (2 equiv) in THF
13C NMR (CDCl3): d = –1.7, –1.5, 13.8, 14.4, 25.9, 26.0, 139.1,
152.0.
MS (EI): m/z (%): 215 (M+, 15), 142 (35), 128 (20), 86 (10), 74
(100), 60 (30), 46 (30).
Anal. Calcd for C11H26Si2: C, 61.59; H, 12.22. Found: C, 61.89; H,
11.96.
1-(Butyldimethylsilyl)-1-(ethyldimethylsilyl)ethene (9)
Colorless liquid; yield: 69%; bp 66–68 °C/0.5 mm Hg.
Synthesis 2006, No. 8, 1370–1374 © Thieme Stuttgart · New York

1374
G. Hreczycho et al.
PAPER
1H NMR (CDCl3): d = 0.06 (s, 6 H), 0.08 (s, 6 H), 0.42–0.46 (q,
J = 7.2 Hz, 2 H), 0.56–0.59 (t, J = 3.4 Hz, 2 H), 0.78–0.83 (t, J = 7.1
Hz, 3 H), 0.90–0.94 (t, J = 6.9 Hz, 3 H), 1.10–1.15 (m, 4 H), 6.38–
6.42 (d, J = 5.4 Hz, 1 H), 6.47–6.49 (d, J = 5.4 Hz, 1 H).
13C NMR (CDCl3): d = –1.9, –1.4, 7.4, 8.1, 14.1, 15.2, 26.1, 27.0,
138.0, 151.4.
(3) (a) Narasaka, K.; Saito, N.; Hayashi, Y.; Ichida, H. Chem.
Lett. 1990, 1411. (b) Fleming, I.; Ghosh, U. J. Chem. Soc.,
Perkin Trans. 1 1994, 257. (c) Inoue, A.; Kondo, J.;
Shinokubo, H.; Oshima, K. Chem. Lett. 2001, 956.
(d) Kondo, J.; Inoue, A.; Shinokubo, H.; Oshima, K.
Tetrahedron Lett. 2002, 43, 2399.
(4) (a) Kondo, J.; Inoue, A.; Shinokubo, H.; Oshima, K. Chem.
Eur. J. 2002, 8, 1730. (b) Jones, P. R.; Bates, T. F. J. Am.
Chem. Soc. 1987, 109, 913. (c) Miura, K.; Hondo, T.;
Okajima, S.; Nakagawa, T.; Takahashi, T.; Hosomi, A. J.
Org. Chem. 2002, 67, 6082. (d) Ohmiya, H.; Yorimitsu, H.;
Oshima, K. Angew. Chem. Int. Ed. 2005, 44, 3488.
(5) For reviews, see: (a) Marciniec, B.; Pietraszuk, C.;
Kownacki, I.; Zaidlewicz, M. Vinyl and Aryl Silicon,
Germanium, and Boron Compounds, In Comprehensive
Organic Functional Group Transformations II, Vol. 2;
Katritzky, A. R.; Taylor, R. J. K., Eds.; Elsevier: Oxford,
2005, 941–1023. (b) Marciniec, B.; Pietraszuk, C. Curr.
Org. Chem. 2003, 7, 691. (c) Marciniec, B.; Pietraszuk, C.
In Topics in Organometallic Chemistry. Synthesis of Silicon
Derivatives with Ruthenium Catalysts; Dixneuf, P., Ed.;
Springer: Berlin, 2004, 197–248.
MS (EI): m/z (%) = 199 (2), 172 (25), 157 (40), 143 (100), 129 (10),
87 (35), 73 (65), 60 (75), 46 (20).
Anal. Calcd for C12H28Si2: C, 63.07; H, 12.35. Found: C, 63.37; H,
12.19.
1-(Dimethylphenylsilyl)-1-(dimethylvinylsilyl)ethene (10)
Colorless liquid; yield: 63%; bp 114–116 °C/0.5 mm Hg.
1H NMR (CDCl3): d = 0.19 (s, 6 H), 0.38 (s, 6 H), 5.62–5.70 (d,
J = 4.0, 20.2 Hz, 1 H), 5.90–5.98 (d, J = 4.0, 14.4 Hz, 1 H), 6.10–
6.22 (d, J = 14.4, 20.0 Hz, 1 H), 6.32–6.34 (d,, J = 4.8 Hz, 1 H),
6.46–6.48 (d, J = 4.8 Hz, 1 H), 7.28–7.32 (m, 3 H), 7.48–7.52 (m, 2
H).
13C NMR (CDCl3): d = –2.2, –1.9, 127.6, 128.8, 131.0, 134.0, 139.2,
142.3, 152.1.
(6) (a) Wakatsuki, Y.; Yamazaki, H.; Nakano, N.; Yamamoto,
MS (EI): m/z (%) = 246 (M+, 10), 232 (15), 219 (15), 192 (15), 145
(25), 135 (100), 105 (25), 85 (20), 74 (25), 60 (70), 46 (15).
Y. J. Chem. Soc., Chem. Commun. 1991, 703.
(b) Marciniec, B.; Pietraszuk, C. J. Chem. Soc., Chem.
Commun. 1995, 2003. (c) Marciniec, B.; Pietraszuk, C.
Organometallics 1997, 16, 4320.
Anal. Calcd for C14H22Si2: C, 68.22; H, 9.00. Found: C, 63.41; H,
9.22.
(7) (a) Marciniec, B.; Lewandowski, M. Tetrahedron Lett.
1997, 38, 3777. (b) Mise, T.; Takaguchi, Y.; Umemiya, T.;
Shimizu, S.; Wakatsuki, Y. Chem. Commun. 1998, 699.
(c) Marciniec, B.; Lewandowski, M.; Bijpost, E.; Małecka,
E.; Kubicki, M.; Walczuk-Guściora, E. Organometallics
1999, 20, 3968. (d) Marciniec, B.; Małecka, E. Macromol.
Symp. 2001, 174, 137. (e) Majchrzak, M.; Marciniec, B.;
Kubicki, M.; Pawelczyk, A. Organometallics 2005, 24,
3731.
(8) (a) Pawluć, P.; Marciniec, B.; Hreczycho, G.; Gaczewska,
B.; Itami, Y. J. Org. Chem. 2005, 70, 370. (b) Pawluć, P.;
Hreczycho, G.; Marciniec, B. Synlett 2005, 1105.
(9) Yi, C. S.; Lee, D. W.; Chen, Y. Organometallics 1999, 18,
2043.
Acknowledgment
This work was supported by The State Committee for Scientific Re-
search, Projects No. 3 TO9A 009 29 and 3 T09A 145 26.
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Synthesis 2006, No. 8, 1370–1374 © Thieme Stuttgart · New York