A facile synthesis of 1,1-bis(silyl)ethenes

Article abstract of DOI:10.1021/jo048784c

(Chemical Equation Presented). Symmetrical 1,1-bis(silyl)ethenes have been easily prepared via ruthenium complex-catalyzed silylative coupling cyclization of 1,2-bis(dimethylvinylsiloxy)ethane to give 2,2,4,4-tetramethyl-3-methylene-1, 5-dioxa-2,4-disilac

Full text of DOI:10.1021/jo048784c

A Facile Synthesis of 1,1-Bis(silyl)ethenes†
3a
compounds with the use of LiC(SiMe
3
)
3
and reaction of
3c
esters with phenyldimethylsilyllithium, have also been
investigated. Oshima and co-workers reported the syn-
thesis of 1,1-bis(silyl)ethenes via lithium trimethylmag-
nesate-induced monomethylation of dibromodisilyl-
methanes followed by dehydrobromination of the resulting
1-bromo-1,1-disilylethanes with DBU.3h Chromium(II)
chloride-mediated reaction of aldehydes with dibromo-
disilylmethane reported by Hodgson and co-workers
Piotr Pawluc, Bogdan Marciniec,* Grzegorz Hreczycho,
Beata Gaczewska, and Yujiro Itami
Department of Organometallic Chemistry,
Faculty of Chemistry, Adam Mickiewicz University,
Grunwaldzka 6, 60-780 Poznan, Poland
marcinb@amu.edu.pl
Received July 16, 2004
2
c
provides an alternative route to vinylbis(silanes). 1,1-
Bis(silyl)alkenes can be also prepared from 1-alkynyl-
silanes by hydroalumination-halogenolysis followed by
replacement of the halide atom in the resulting 1-halo-
3
e,g
vinylsilane by a silyl group using alkyllithium.
In the last 15 years, we have developed the silylative
coupling reaction of vinylsilane derivatives in the pres-
ence of ruthenium, rhodium, cobalt, and iridium com-
plexes containing or generating M-H and M-Si bonds
(
(
e.g., [RuHCl(CO)(PPh
3
)
3
], [RuCl
2 3 2
(CO) ] , or [Rh(µ-Cl)-
4
cod)]
2
). The silylative coupling reaction of monovinyl
organosilicon compounds proceeds through cleavage of
the dC-Si bond of the vinyl-substituted silicon com-
pound and the activation of the dC-H bond of the second
Symmetrical 1,1-bis(silyl)ethenes have been easily prepared
via ruthenium complex-catalyzed silylative coupling cycliza-
tion of 1,2-bis(dimethylvinylsiloxy)ethane to give 2,2,4,4-
tetramethyl-3-methylene-1,5-dioxa-2,4-disilacycloheptane with
excellent selectivity and good yield, followed by its reaction
with Grignard reagents. The cyclic product can also be
effectivelytransformedintocycliccarbosiloxane,2,2,4,4,6,6,8,8-
octamethyl-3,7-dimethylene-1,5-dioxa-2,4,6,8-tetrasilacy-
clooctane.
4
vinylsilane molecule. The mechanism of this reaction
involving â-silyl elimination and insertion of a CdC
double bond into the resulting M-Si bond has been
proved by insertion of ethylene and vinylsilane into M-Si
(where M ) Ru, Rh, Co) bonds as well as by a series of
elaborate mass-spectrometric studies with deuterated
styrene and vinylsilanes (Scheme 1).5
In this reaction divinyl-substituted silanes, siloxanes
and silazanes undergo efficient silylative coupling con-
densation to yield a mixture of linear oligomers and cyclic
dimers and trimers containing exo-cyclic methylene bonds
Alkenylsilanes, especially vinyl- and allylsilanes are
well established in regio- and stereoselective organic
synthesis. The properties of 1,1-bis(silyl)alkenes are
1
similar to those of vinylsilanes, and the former com-
pounds have recently been shown to be interesting
intermediates in organic and organosilicon synthesis.2
Although it is already known to be possible to apply 1,1-
bis(silyl)alkenes as synthetic tools, their synthesis is
(
Scheme 2). The unique feature of this silylative coupling
reaction, distinguishing this reaction from cross-metath-
esis, is the formation of 1,1-bis(silyl)ethene fragment in
given conditions.6
Herein we disclose a new facile and rapid synthetic
protocol for synthesis of 1,1-bis(silyl)ethenes using alkyl-
3
complicated. 1,1-Bis(silyl)alkenes have been mostly pre-
pared by multistep reactions involving commercially
unavailable dihalodisilylmethanes; however, several in-
dependent methods, e.g., Peterson olefination of carbonyl
(
aryl) or alkenyl Grignard reagents and 2,2,4,4-tetra-
methyl-3-methylene-1,5-dioxa-2,4-disilacycloheptane se-
lectively obtained via ruthenium-catalyzed silylative
coupling cyclization.
†
Dedicated to Professor Mieczysław M a¸ kosza on the occasion of his
7
0th birthday in recognition of his significant contribution to organic
chemistry.
The starting 1,2-bis(dimethylvinylsiloxy)ethane 1 could
be easily prepared by the reaction of commercially
(
1) (a) Colvin, E. W. Silicon Reagents in Organic Synthesis Academic
Press: London, 1988. (b) Patai, S., Rappoport, Z., Eds. The Chemistry
of Organosilicon Compounds; Wiley: Chichester, 1988; Chapter 3.
(4) For reviews see: (a) Marciniec, B.; Pietraszuk, C. Curr. Org.
Chem. 2003, 7, 691-735. (b) Marciniec, B.; Pietraszuk, C. In Handbook
of Metathesis; Grubbs, R. H. Ed.; Wiley-VCH: Weinheim, 2003; Vol 2;
Chapter 13. (c) Marciniec, B. Appl. Organomet. Chem. 2000, 14, 527-
538. (d) Marciniec, B. Mol. Cryst. Liq. Cryst. 2000, 353, 173-182.
(5) (a) Wakatsuki, Y.; Yamazaki, H.; Nakano, N.; Yamamoto, 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. (d) Marciniec, B.;
Lewandowski, M.; Bijpost, E.; Małecka, E.; Kubicki, M.; Walczuk-
Gu s´ ciora, E. Organometallics 1999, 20, 3968.
(6) (a) Marciniec, B.; Lewandowski, M. Tetrahedron Lett. 1997, 38,
3777. (b) Marciniec, B.; Małecka, E. Macromol. Rapid Commun. 1999,
20, 475. (c) Majchrzak, M.; Itami, Y.; Marciniec, M.; Pawlu c´ , P.
Tetrahedron Lett. 2000, 41, 10303. (d) Marciniec, B.; Małecka, E.;
SÄ cibiorek, M. Macromolecules 2003, 36, 5545. (e) Mise, T.; Takaguchi,
Y.; Umemiya, T.; Shimizu, S.; Wakatsuki, Y. Chem. Commun. 1998,
699.
(2) (a) Inoue, A.; Kondo, J.; Shinokubo, H.; Oshima, K. Chem.
Commun. 2002, 114. (b) Inoue, A.; Kondo, J.; Shinokubo, H.; Oshima,
K. J. Am. Chem. Soc. 2001, 123, 11109. (c) Hodgson, D. M.; Comina,
P. J.; Drew, M. G. B. J. Chem. Soc, Perkin Trans. 1 1997, 2279. (d)
Hodgson, D. M.; Comina, P. J. Chem. Commun. 1996, 755. (e)
Jankowski, P.; Ple s´ niak, K.; Wicha, J. Org. Lett. 2003, 5 (16), 2789.
(3) (a) Gr o¨ bel, B. Th.; Seebach, D. Chem. Ber. 1977, 110, 852. (b)
Fleming, I.; Floyd, C. D. J. Chem. Soc., Perkin Trans. 1 1981, 969. (c)
Fleming, I.; Ghosh, U. J. Chem. Soc., Perkin Trans. 1 1994, 257. (d)
Narasaka, K.; Saito, N.; Hayashi, Y.; Ichida, H. Chem. Lett. 1990, 1411.
(
e) Negishi, E.; Boardman, L. D.; Sawada, H.; Bagheri, V.; Stoll, A. T.;
Tour, J. M.; Rand, C. L. J. Am. Chem. Soc. 1988, 110, 5383. (f) Flann,
C.; Malone, T. C.; Overman, L. E. J. Am. Chem. Soc. 1987, 109, 6097.
(
g) Blumenkopf T. A.; Overman, L. E. Chem. Rev. 1986, 86, 857. (h)
Inoue, A.; Kondo, J.; Shinokubo, H.; Oshima, K. Chem. Lett. 2001, 956.
i) Kondo, J.; Inoue, A.; Shinokubo, H.; Oshima, K. Tetrahedron Lett.
002, 43, 2399.
(
2
10.1021/jo048784c CCC: $30.25 © 2005 American Chemical Society
370
J. Org. Chem. 2005, 70, 370-372
Published on Web 12/02/2004

SCHEME 1. Silylative Coupling Reaction
Mechanism
SCHEME 4. Synthesis of 2,2,4,4-Tetramethyl-3-
methylene-1,5-dioxa-2,4-disilacycloheptane
TABLE 1. Synthesis of 1,1-Bis(dimethylsilyl)ethenesa
entry
R
X
time (h)
yield (%)c
I
Me
Et
I
24
24
24
24
76
73
88
62
68
55
II
Br
Br
Br
Br
Br
III
IV
V
Ph
SCHEME 2. Silylative Coupling Reaction of
Divinyl-Substituted Organosilicon Compounds
-CHdCH2
-CH2CHdCH2
-(CH2)2CHdCH2
b
48
VI
72
a
Reaction conditions: THF, 65 °C. b Diethyl ether, 40 °C.
c
Isolated yields of chromatographically pure products
SCHEME 5. Synthesis of 2,2,4,4,6,6,8,8-
Octamethyl-3,7-dimethylene-1,5-dioxa-2,4,6,8-
tetrasilacyclooctane
SCHEME 3. Synthesis of
1,2-Bis(dimethylvinylsiloxy)ethane
At the next stage, we investigated the reaction of
2,2,4,4-tetramethyl-3-methylene-1,5-dioxa-2,4-disilacyclo-
heptane with Grignard reagents. After preliminary at-
tempts, we found that the treatment of the silylative
coupling cyclization product 2 with 2.5 equiv of the
corresponding Grignard reagent in THF or diethyl ether
(
0.5 M concentration of the solvent) at reflux under an
available chlorodimethylvinylsilane and ethylene glycol
in the presence of triethylamine in high yield (90%) as
outlined in Scheme 3.
Silylative coupling cyclization of 1,2-bis(dimethyl-
vinylsiloxy)ethane was effectively catalyzed by [RuHCl-
Ar atmosphere provided substituted 1,1-bis(silyl)ethenes
in moderate to good yields. In all cases, excellent regi-
oselectivity was attained; however, when the allyl- and
3
-butenylmagnesium bromide were used, the reaction
mixture had to be refluxed for a longer time and an
increased amount of the Grignard reagents (from 2.5 to
3 3
(CO)(PPh ) ] (1 mol %), and the divinyl compound was
completely consumed within 1 h at 80 °C. The reaction
occurred even at a lower catalyst loading (0.2 mol %),
but in a longer time (24 h).
The cyclization reaction successfully proceeded without
the solvent under air, but toluene or benzene could also
be employed without affecting either the activity of the
catalyst or the selectivity of this process. Application of
this catalytic system for silylative coupling cyclization of
3
equiv) did not appreciably affect the rate of this
reaction. Table 1 summarizes the results of this reaction.
1
3
Results of the spectroscopic analyses ( C NMR and
DEPT) of the products obtained in the above-mentioned
reaction have confirmed the occurrence of the quaternary
carbon atoms and methylene groups.
Compound 2 was also found to be a good starting
material for synthesis of cyclic tetrasilacarbosiloxane 3
containing two exo-methylene bonds between silicon
atoms in the molecule (Scheme 5). This compound has
been obtained previously via silylative coupling cycliza-
tion of 1,3-divinyltetramethyldisiloxane in the presence
1
,2-bis(dimethylvinylsiloxy)ethane gives exclusively a
disilacyclic product containing exo-methylene bond be-
tween two silicon atoms in the molecule with perfect
regioselectivity and high yield (85%) (Scheme 4). It is
worth adding that the cyclic product was easily isolated
only by the “bulb to bulb” distillation from the reaction
flask.
of [RhX(cod)]
has been determined by the X-ray method.
2
3
(where X ) Cl, OSiMe ), and its structure
5d,6a
However,
The existence of the exo-methylene unit in the product
the cyclization was accompanied by linear polyconden-
sation of 1,3-divinyltetramethyldisiloxane and the iso-
lated yield of the cyclic product was rather low (30%). In
was unambiguously determined on the basis of the 13
NMR and NMR DEPT spectra.
C
J. Org. Chem, Vol. 70, No. 1, 2005 371

contrast to the above-mentioned synthetic method, the
hydrolysis of compound 2 in the presence of catalytic
amount of HCl proceeded directly to afford exclusively
bubbling tube, and thermostated heating oil bath) was evacuated
and flushed with argon. Compound 2 and the solvent were added
to the reactor. At room-temperature, Grignard reagent (molar
ratio of compound 2:Grignard reagent was 1:2.5) was added
dropwise. The reaction mixture was stirred under the conditions
shown in Table 1. After the reaction was completed, the excess
amount of the Grignard reagent was quenched by adding MeOH
and pentane; the suspended salt was filtered off, and the
volatiles were evaporated in vacuo. After evaporation, the crude
product was chromatographed on silica gel and distilled under
reduced pressure to afford the analytically pure product.
2
2
,2,4,4,6,6,8,8-octamethyl-3,7-dimethylene-1,5-dioxa-
,4,6,8-tetrasilacyclooctane in 88% yield.
In conclusion, we have shown that through ruthenium-
catalyzed selective exo-cyclization of 1,2-bis(dimethylvi-
nylsiloxy)ethane and subsequent coupling of the cyclic
product with varying the structure of the Grignard
compounds, a wide range of alkyl-, aryl-, or alkenyl-
substituted 1,1-bis(silyl)ethenes should be available. Our
current investigation focuses on the application of the
resulting alkyl- and alkenyl-substituted 1,1-bis(silyl)-
ethenes in the synthesis of new unsaturated silacyclic
and silamacrocyclic compounds as well as unsaturated
organic derivatives.
Synthesis and Characterization of Compound 3. Com-
pound 2 (3.0 g, 0.015 mol) in 10 mL of THF was placed in a
two-necked, 50 mL flask equipped with a magnetic stirring bar
and a reflux condenser. Then, 0.29 mL (0.016 mol) of water and
several drops of aqueous solution of HCl were added. The
reaction mixture was refluxed for 4 h with stirring. The solvent
was evaporated in vacuo, and the cyclic product was isolated by
distillation under reduced pressure (68 °C/0.5 mmHg) to give
1
2
0
.06 g of 3 in 88% yield. H NMR, (CDCl
3
, 300 MHz) δ (ppm):
) δ (ppm): 1.6, 139.9,
28 2 4
H O Si : C, 45.60; H, 8.86. Found:
Experimental Section
1
3
.28 (s, 24H), 6.19 (s, 4H). C NMR, (CDCl
3
Synthesis and Characterization of Compound 2. RuHCl-
156.6. Anal. Calcd for C12
C, 45.56; H, 8.81.
-
4
(
CO)(PPh
3
)
3
(0.828 g, 8.7 × 10 mol) and 20.0 g (0.087 mol) of
1
,2-bis(dimethylvinylsiloxy)ethane were placed in a two-necked,
0 mL flask equipped with a magnetic stirring bar and a reflux
5
Acknowledgment. Financial support from the State
condenser. The reaction mixture was heated for 1 h at 80 °C
with stirring. The cyclic product was isolated by “bulb to bulb”
Committee for Scientific Research (Poland), Grant
3
T09A 145 26, is gratefully acknowledged.
distillation to give 14.93 g of 2 (0.074 mol) in 85% yield as a
1
colorless liquid. H NMR (CDCl
1
6
3
, 300 MHz) δ (ppm): 0.25 (s,
) δ (ppm): -1.5,
: C, 47.47; H, 8.96.
2H), 3.65 (s, 4H), 6.20 (s, 2H). 13C NMR (CDCl
6.6, 139.7, 157.7. Anal. Calcd for C Si
Found: C, 47.51; H, 9.14.
3
Supporting Information Available: Detailed experi-
8 18
H
O
2
2
mental procedures and characterization data of all compounds
prepared in this study. This material is available free of charge
via the Internet at http://pubs.acs.org.
General Procedure for Synthesis of 1,1-Bis(silyl)ethenes.
The glass reactor (100 mL, two-necked, round-bottomed flask
equipped with a magnetic stirring bar, reflux condenser, argon
JO048784C
372 J. Org. Chem., Vol. 70, No. 1, 2005