Stereochemistry of disilanylene-containing cyclic compounds - Synthesis and palladium-catalyzed reactions of cis- and trans-3,4-benzo-1,2-diisopropyl-1,2- dimethyl-1,2-disilacyclobut-3-ene

Article abstract of DOI:10.1515/znb-2009-11-1243

The synthesis and palladium-catalyzed reactions of cis- and trans-3,4-benzo-1,2-diisopropyl-1,2-dimethyl-1,2-disilacyclobut-3-ene (1a and 1b) are reported. Their reactions with diphenyl-acetylene in the presence of a catalytic amount of tetrakis(triphenyl

Full text of DOI:10.1515/znb-2009-11-1243

Stereochemistry of Disilanylene-containing Cyclic Compounds –
Synthesis and Palladium-catalyzed Reactions of cis- and trans-3,4-
Benzo-1,2-diisopropyl-1,2-dimethyl-1,2-disilacyclobut-3-ene
Akinobu Nakaa, Jun Sakataa, Junnai Ikadaib, Hiroyuki Kawasakia, Joji Ohshitab,
Eigo Miyazakib, Atsutaka Kunaib, Kazunari Yoshizawac, and Mitsuo Ishikawaa
a Department of Life Science, Kurashiki University of Science and the Arts, Nishinoura,
Tsurajima-cho, Kurashiki, Okayama 712-8505, Japan
b Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University,
Higashi-Hiroshima 739-8527, Japan
c Institute for Materials Chemistry and Engineering, Kyusyu University, Fukuoka 812-8581, Japan
Reprint requests to Prof. Akinobu Naka or Prof. Mitsuo Ishikawa.
E-mail: anaka@chem.kusa.ac.jp, ishikawa-m@zeus.eonet.ne.jp
Z. Naturforsch. 2009, 64b, 1580 – 1590; received September 29, 2009
Dedicated to Professor Hubert Schmidbaur on the occasion of his 75th birthday
The synthesis and palladium-catalyzed reactions of cis- and trans-3,4-benzo-1,2-diisopropyl-
1,2-dimethyl-1,2-disilacyclobut-3-ene (1a and 1b) are reported. Their reactions with diphenyl-
acetylene in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium(0) pro-
ceeded with high stereospecificity to give cis- and trans-5,6-benzo-1,4-diisopropyl-1,4-dimethyl-
2,3-diphenyl-1,4-disilacyclohexa-2,5-diene, 2a and 2b, in 95 % and 93 % yield, respectively. Sim-
ilar palladium-catalyzed reactions of 1a and 1b with monosubstituted acetylenes, such as 1-hexyne,
tert-butylacetylene, phenylacetylene, and trimethylsilylacetylene, also proceeded stereospecifically
to afford the respective cis- and trans-5,6-benzo-1,4-disilacyclohexa-2,5-dienes, 3a – 6a and 3b –
6b, in excellent yields and as the sole products. The palladium-catalyzed reaction of 1a with
styrene gave a mixture consisting of two stereoisomers, cis-2- and trans-2-phenyl-substituted 5,6-
benzo-(r-1),cis-4-diisopropyl-1,4-disilacyclohex-5-ene 7a and 8a in a ratio of 5 : 3 in 72 % com-
bined yield, while the reaction of styrene with 1b afforded two stereoisomers, 7b and 8b, in a ra-
tio of 2 : 1 in 80 % combined yield. With 1-hexene, 1a gave two stereoisomers, 5,6-benzo-cis-2-(n-
butyl)-(r-1),cis-4-diisopropyl- and 5,6-benzo-trans-2-(n-butyl)-(r-1),cis-4-diisopropyl-1,4-dimethyl-
1,4-disilacyclohex-5-ene, 9a and 10a, in a ratio of 1 : 1 in 70 % combined yield. A similar reaction
of 1b with 1-hexene produced 5,6-benzo-cis-2-(n-butyl)-(r-1),trans-4-diisopropyl-1,4-dimethyl-1,4-
disilacyclohex-5-ene in 81 % yield and as a single isomer.
Key words: Stereochemistry, Palladium-catalyzed Reaction, Disilanyl Compounds,
Benzodisilacyclobutenes
Introduction
from the insertion of the transition-metal complex into
the silicon-silicon bond in the 1,2-disilacyclobutenes
Four-membered cyclic compounds including a as intermediates [3, 6, 9, 11d]. The methods used for
silicon-silicon bond are interesting because of their the synthesis of these compounds, however, are rather
high strain energy and high reactivity. In fact, limited. They involve the reaction of silylenes with
the 1,2-disilacyclobutene derivatives show unique silacyclopropene or alkynes, or the reaction of dis-
chemical behavior and undergo a wide variety ilenes with alkynes.
of reactions [1 – 9]. For example, the thermoly-
On the other hand, benzodisilacyclobutenes bearing
sis of 1,2-disilacyclobutenes proceeds via the ring- various substituents at the silicon atoms can readily be
opened 1,4-disilabutadienes as the reactive intermedi- prepared in high yields by the sodium condensation re-
ates [4, 6, 11c, d]. The transition metal-catalyzed reac- action of 1,2-bis(dialkylchlorosilyl)benzenes. To date,
tions of 1,2-disilacyclobutenes with various substrates various types of benzodisilacyclobutenes [10– 13] and
afford reactive metal-containing complexes, arising benzobis(disilacyclobutene)s [14] have been synthe-
c
0932–0776 / 09 / 1100–1580 $ 06.00 ꢀ 2009 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
Unauthenticated
Download Date | 10/23/16 9:34 AM

A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
1581
Scheme 1.
sized, and their thermal, photochemical, and transi- carbon tetrachloride solution gave a mixture of meso-
tion metal-catalyzed reactions have been investigated. and D,L-1,2-bis(chloroisopropylmethyl)benzene in a
Theoretical treatments concerning the thermal ring- ratio of 1 : 1 in 92 % yield. The sodium condensation
opening reaction and the platinum-catalyzed reaction reaction of the meso- and D,L-isomer in refluxing
of these disilacyclobutene derivatives have also been toluene gave a mixture of 1a and 1b in a ratio of 1 : 1
reported [15]. However, much less attention has been in 91 % yield. 1a and 1b were separated by fractional
paid to the stereochemistry of the reactions of these distillation with the use of a spinning-band column
compounds.
with 50 theoretical plates and obtained in isomerically
pure form.
We have reported the synthesis and reactions
of cis- and trans-3,4-benzo-1,2-di(tert-butyl)-1,2-di-
methyl-1,2-disilacyclobut-3-eneand demonstrated that
their palladium-catalyzed reactions with various
alkynes proceed with high stereospecificity to give the
1 : 1 adducts [16]. However, on the basis of the results
obtained from our investigations concerning the stere-
ochemistry of the benzodisilacyclobutenes, it is abso-
lutely necessary to use benzodisilacyclobutenes that
are more reactive than the di(tert-butyl)-substituted
derivatives, to be able to elucidate the stereochemistry
in their reactions with various substrates. In this paper
we report the synthesis and palladium-catalyzed reac-
tions of cis- and trans-3,4-benzo-1,2-diisopropyl-1,2-
dimethyl-1,2-disilacyclobut-3-ene with alkynes and
alkenes.
The composition and structures of 1a and 1b were
verified by mass spectrometry and 1H, 13C, and
29Si NMR spectroscopy, as well as by elemental anal-
ysis. Because compounds 1a and 1b are liquid at r. t.,
their configuration can not be confirmed directly by
X-ray crystallography. However, we assigned 1a to
have cis configuration on the basis of the results of an
X-ray crystal structure determination of the adduct de-
rived from the palladium-catalyzed reaction of 1a with
diphenylacetylene.
Determination of cis and trans configuration
Isomer 1a has the higher boiling point of the
two geometric isomers. It was determined to have
the cis configuration on the basis of the follow-
ing results. Treatment of isomer 1a with dipheny-
lacetylene in the presence of a catalytic amount of
tetrakis(triphenylphosphine)palladium(0) in a sealed
glass tube at 80 ◦C for 24 h gave a 1 : 1 adduct
Results and Discussion
Synthesis of benzodisilacyclobutenes 1a and 1b
Cis- and trans-3,4-benzo-1,2-diisopropyl-1,2-di- in 95 % yield as white crystals. No other isomers
methyl-1,2-disilacyclobut-3-ene (1a and 1b) were were detected in the reaction mixture. The structure
of this adduct was verified by X-ray crystallography
to be cis-5,6-benzo-1,4-diisopropyl-1,4-dimethyl-1,4-
prepared by the method used for the synthesis
of cis- and trans-3,4-benzo-1,2-di(tert-butyl)-1,2-
dimethyl-1,2-disilacyclobut-3-ene [16], as shown in disilacyclohexa-2,5-diene (2a; see Experimental Sec-
Scheme 1. Thus, the reaction of o-dibromobenzene tion). A drawing of the molecular structure for 2a is
shown in Fig. 1.
with 2 equiv. of magnesium in the presence of 2 equiv.
of chloroisopropylmethylsilane in THF afforded 1,2-
We have previously reported that the palladium-
bis(isopropylmethylsilyl)benzene, consisting of a mix- catalyzed reactions of cis- and trans-1,2-dimeth-
ture of meso- and D,L-isomer in 77 % yield. Treatment yl-1,2-diphenyl-1,2-disilacyclopentane and 1,2-di-
of 1,2-bis(hydrosilyl)benzene with chlorine gas in a silacyclohexane with alkynes proceed with high
Unauthenticated
Download Date | 10/23/16 9:34 AM

1582
A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
Scheme 2.
Fig. 1. ORTEP diagram of the molecular structure of 2a in the
crystal (displacement ellipsoids at the 50 % level; H atoms
omitted for clarity).
of tetrakis(triphenylphosphine)palladium(0) in a de-
gassed sealed tube at 80 ◦C for 24 h, a sin-
gle isomer, cis-5,6-benzo-2-butyl-1,4-diisopropyl-1,4-
dimethyl-1,4-disilacyclohexa-2,5-diene (3a) was ob-
tained in 91 % isolated yield. No other isomers were
detected in the reaction mixture by spectrometric
analysis. Similar treatment of 1b with 1-hexyne af-
forded trans isomer 3b in 93 % yield. Again, no other
stereoisomers were detected in the reaction mixture.
The reaction of 1a and 1b with tert-butylacetylene un-
der the same conditions also proceeded with high stere-
ospecificity to give the respective adducts 4a and 4b,
in 93 % and 90 % yields, respectively. With pheny-
lacetylene, 1a and 1b produced a single stereoisomer,
cis and trans adducts 5a and 5b, respectively, as the
sole products.
stereospecificity to give the respective adducts,
arising from the insertion of a carbon-carbon triple
bond into a silicon-silicon bond in the five- and
six-membered ring [17, 18]. We have also found
that the reactions of cis- and trans-3,4-benzo-1,2-
di(tert-butyl)-1,2-dimethyl-1,2-disilacyclobut-3-ene
with diphenylacetylene in the presence of the same
palladium catalyst proceed stereospecifically to give
the respective adducts [16]. Therefore, in the present
reaction, it seems reasonable to assume that the
palladium-catalyzed reaction of the benzodisilacyclo-
butene 1a with diphenylacetylene proceeds with
high stereospecificity to give the cis adduct 2a, and
hence 1a must have the cis configuration, and 1b must
be the trans form (Scheme 2).
The palladium-catalyzed reaction of 1b with
diphenylacetylene under the same conditions pro-
duced trans-5,6-benzo-1,4-diisopropyl-1,4-dimethyl-
2,3-diphenyl-1,4-disilacyclohexa-2,5-diene (2b) in
93 % yield and as the sole product. Again, no other iso-
mers were detected in the reaction mixture, indicating
that the reaction proceeded with high stereospecificity.
The structure for 2b was confirmed by spectrometric
and elemental analyses (see Experimental Section).
As reported previously, the palladium-catalyzed
reactions of cis- and trans-3,4-benzo-1,2-di(tert-
butyl)-1,2-dimethyl-1,2-disilacyclobut-3-ene
[16]
and also of 3,4-benzo-1,1,2,2-tetraisopropyl-1,2-
disilacyclobut-3-ene [11d] with monosubstituted
acetylenes bearing a bulky substituent, such as a silyl
group, afford the ring-opened 1,2-bis(silyl)benzene
derivatives. The benzodisilacyclobutenes 1a and 1b,
however, reacted with trimethylsilylacetylene to give
the products with the benzodisilacyclohexa-2,5-diene
structure and not the 1,2-bis(silyl)benzene derivatives.
Thu◦s, treatment of 1a with trimethylsilylacetylene at
80 C for 24 h gave cis-benzodisilacyclohexadiene
(6a) in 50 % yield, while with trimethylsilylacetylene,
1b afforded the trans adduct in 77% yield. In these
reactions no other isomers were detected in the
reaction mixture by spectrometric analysis.
Palladium-catalyzed reactions with alkynes
To clarify the stereochemistry for the transi-
tion metal-catalyzed reactions of 1a and 1b with
unsaturated compounds, we first investigated the
palladium-catalyzed reactions with monosubstituted
acetylenes (Scheme 3). When 1a was treated with palladium-catalyzed reactions may be explained as fol-
1-hexyne in the presence of a catalytic amount lows (Scheme 3): (i) insertion of the palladium species
The formation of the adducts 2a, b – 6a, b in the
Unauthenticated
Download Date | 10/23/16 9:34 AM

A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
1583
Scheme 3.
into a silicon-silicon bond in 1a, producing cis-3,4- by MPLC, and their configurations were confirmed
benzo-1-pallada-2,5-disilacyclopent-3-ene intermedi- by 1H NMR NOE-FID difference experiments
ates (Aa); (ii) coordination of an alkyne molecule at at 300 MHz. For the major product 7a, which seems
a palladium atom in Aa, followed by insertion of a to be the sterically unfavorable isomer, irradiation of
triple bond of the alkyne into a palladium-silicon bond, the signal at 2.84 ppm, attributed to the proton on
to give complexes (Ba); (iii) reductive elimination of the carbon atom attached to the phenyl group in the
the palladium species from the resulting complex Ba. 1,4-disilacyclohexenyl ring, led to an enhancement
With 1a as starting benzodisilacyclobutenethe reaction of the signals at 0.12 and 0.29 ppm, due to two
proceeds with high stereospecificity to give the corre- different kinds of methylsilyl protons, together with
sponding adducts, as shown in Scheme 3.
the signals attributed to the phenyl, phenylene and
methylene protons. These results clearly indicate that
the substituents, two different kinds of methyl groups
at the silicon atoms, and the irradiated hydrogen atom
are located in the cis position. For 8a, saturation of
the signal at 1.75 ppm, attributed to one of the protons
of the methylene unit in the disilacyclohexenyl ring,
resulted in an enhancement of the signals at 0.25,
1.21, and 7.26 ppm, due to the methyl protons, the
other proton of the ring methylene unit, and the phenyl
protons, indicating that the isopropyl group of the
silicon at the 1-position in the six-membered ring and
the phenyl group are located in a cis fashion.
Palladium-catalyzed reactions with alkenes
We investigated the palladium-catalyzed reaction
of 1a with alkenes under the same conditions as de-
scribed above for the reactions with alkynes, however,
a large amount of the starting compound 1a was
recovered unchanged. Treatment of 1a with styrene
◦
at 80 C for 24 h indicated that 1 : 1 adducts as a
mixture of two stereoisomers were produced only in
20 % combined yield, and 80 % of 1a was recovered
unchanged. Therefore, we carried out the reactions
of 1a and 1b with alkenes at higher temperature.
The reaction of trans isomer 1b with styrene
The palladium-catalyzed reaction of 1a with at 110 ◦C produced a mixture consisting of two
◦
styrene at 110 C for 24 h gave two stereoisomers stereoisomers of the adducts, 5,6-benzo-(r-1),trans-
of the adducts, 5,6-benzo-(r-1),cis-4-diisopropyl- 4-diisopropyl-cis-2-phenyl-and 5,6-benzo-(r-1),trans-
cis-2-phenyl- and 5,6-benzo-(r-1),cis-4-diisopropyl- 4-diisopropyl-trans-2-phenyl-1,4-dimethyl-1,4-disila-
trans-2-phenyl-1,4-dimethyl-1,4-disilacyclohex-5-ene cyclohex-5-ene (7b and 8b), in a ratio of 2 : 1 and in
(7a and 8a), in a ratio of 5 : 3 in 72 % combined 80 % combined yield. Again, the sterically unfavor-
yield (Scheme 4). Products 7a and 8a were isolated able compound 7b, but not 8b, was obtained as the
Unauthenticated
Download Date | 10/23/16 9:34 AM

1584
A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
Scheme 4.
Scheme 5.
major product. All attempts to separate 7b and 8b signed it as 5,6-benzo-(r-1),trans-4-diisopropyl-trans-
were unsuccessful, but their structures were verified 2-phenyl-1,4-dimethyl-1,4-disilacyclohex-5-ene.
by spectrometric analysis of the mixture. The con-
figurations for 7b and 8b were confirmed by NOE-
FID difference experiments at 300 MHz. For the mi-
nor product 8b, saturation of the signal at 0.28 ppm,
due to methyl protons, led to an enhancement of the
signals at 1.21 and 7.35 ppm, attributed to the iso-
propyl and phenyl protons, as well as the pheny-
lene protons, indicating that the methyl group at the
ring silicon atom at the 1-position and the phenyl
group at the adjacent carbon atom are located in a
cis fashion. Although we could not obtain clear-cut
results for the configuration of 7b, we tentatively as-
When a mixture of 1a and 1-hexene was heated
◦
in a sealed tube at 110 C for 24 h, two products
in a ratio of 1 : 1 were obtained in 70 % combined
yield. Unfortunately, all attempts to separate these
two products were unsuccessful. However, we could
assign these compounds tentatively as 5,6-benzo-
cis-2-(n-butyl)-(r-1),cis-4-diisopropyl- and 5,6-benzo-
trans-2-(n-butyl)-(r-1),cis-4-diisopropyl-1,4-dimethyl-
1,4-disilacyclohex-5ene (9a and 10a) by MS, and
1H, 13C, and 29Si NMR spectroscopy (see Experi-
mental Section). To our surprise, the rea◦ction of the
trans isomer 1b with 1-hexene at 110 C afforded
Unauthenticated
Download Date | 10/23/16 9:34 AM

A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
1585
5,6-benzo-cis-2-(n-butyl)-(r-1),trans-4-diisopropyl- However, insertion of a carbon-carbon double bond of
1,4-dimethyl-1,4-disilacyclohex-5-ene (9b) as a sin- alkenes into a silicon-palladium bond in the palladium
gle isomer, and in 81 % yield, which seems to be complex Aa does not proceed stereospecifically, with
the sterically unfavorable isomer. No other regio- and one exception of the reaction of 1b with 1-hexene, to
stereoisomers were detected (Scheme 5).
give the two stereoisomers.
The structure of the product 9b was verified by MS
and 1H, 13C, and 29Si NMR spectroscopy, and also by
elemental analysis. For example, the 13C NMR spec-
trum for 9b shows two signals at −5.8 and −4.7 ppm,
a single signal at 11.8 ppm, three signals at 12.9, 14.0,
and 14.1 ppm, and five signals at 17.8, 18.3, 19.0,
19.3, and 21.0 ppm, due to methyl carbons on the ring
silicon atoms, the ring methylene carbon, CH-Si car-
bons, and methyl-C carbons, as well as the signals at-
tributed to the methylene and phenylene carbon atoms.
The 29Si NMR spectrum reveals two signals at −4.0
and −3.9 ppm, due to the different ring silicon atoms.
The configuration of the substituents on the benzodis-
ilacyclohexenyl ring in 9b was confirmed by NOE-
FID difference experiments at 300 MHz. Irradiation
of the signal at 0.19 ppm, due to the methyl protons
on one silicon atom in the 1,4-disilacyclohexenyl ring,
revealed an enhancement of the signals at 0.78, 1.00,
and 7.48– 7.52 ppm, attributed to the methyl protons of
the n-butyl group, isopropyl, and phenylene ring pro-
tons, respectively. Saturation of a signal at 0.25 ppm,
due to the methyl protons attached to the other ring sil-
icon atom resulted in an enhancement of the signals
at 1.06, 1.69– 1.74, and 7.48 – 7.52 ppm, attributable
to the isopropyl protons, the proton on the ring carbon
attached to the butyl group, and the phenylene ring pro-
tons, respectively. These results are consistent with the
structure proposed for 9b.
Experimental Section
General procedure
All palladium-catalyzed reactions were carried out in
a degassed sealed tube (1.0 cm × 15 cm). NMR spectra
were measured on JNM-LA300 and JNM-LA500 spec-
trometers. Infrared spectra were recorded on a Jeol JIR-
Diamond 20 infrared spectrophotometer. Mass spectra
were measured on a Jeol model JMS-700 instrument.
Cis- and trans-3,4-benzo-1,2-diisopropyl-1,2-dimethyl-1,2-
disilacyclobut-3-ene (1a and 1b) were separated by a TSA-
SB2 spinning band-type distillation column (Taika Kogyo).
Melting points were measured with a Yanaco-MP-S3 ap-
paratus. Column chromatography was performed by using
Wakogel C-300 (WAKO). Tetrahydrofuran used as a solvent
was dried over sodium/benzophenone under a nitrogen at-
mosphere, and carbon tetrachloride was dried over P4O10
and distilled prior use. Benzene and toluene were dried over
sodium and distilled prior use.
,
Preparation of 1,2-bis(isopropylmethylsilyl)benzene
In a 2 L three-necked flask fitted with a stirrer, a re-
flux condenser, and a dropping funnel were placed 80.4 g
(3.3 mol) of magnesium and 629.8 g (5.1 mol) of chloroiso-
propylmethylsilane in 1.5 L of dry THF. To this mix-
ture was added dropwise a solution of 352.7 g (1.5 mol)
of o-dibromobenzene in 100 mL of dry THF over a pe-
riod of 14 h at r. t. The mixture was heated to reflux
for 1 d. The resulting magnesium salts were removed by
Although the reason for the production of the unfa-
vorable stereoisomers as major products is unclear at
present, the stereochemistry for the formation of the filtration and washed with ether. The solvents were evapo-
rated, and the residue was distilled under reduced pressure
to give 287.8 g (77 % yield) of a 1 : 1 mixture of meso-
and◦ rac-1,2-bis(isopropylmethylsilyl)benzene. – B. p. 76 –
80 C/1.33 mbar. – IR (film): ν = 3046, 2953, 2890, 2862,
2137, 1461, 1250, 1120, 1004, 881, 824, 733 cm−1. –
1H NMR: (CDCl3): δ = 0.21 – 0.22 (m, 12H, MeSi), 0.89 –
0.95 (m, 24H, Me2CH), 1.02 – 1.12 (m, 4H, HCMe2),
4.28 – 4.37 (m, 4H, HSi), 7.23 – 7.25 (m, 4H, phenylene
ring protons), 7.44 – 7.46 (m, 4H, phenylene ring pro-
tons). – 13C NMR (CDCl3): δ = −6.8, −6.3 (MeSi), 12.7,
12.9 (CHMe2), 17.87, 17.94, 18.8, 18.9 (Me2CH), 128.06,
128.09, 134.9, 135.0, 143.35, 143.44 (phenylene ring car-
bon). – 29Si NMR (CDCl3): δ = −9.2, −8.5. – MS: m/z
= 235 [M–Me]+. – C14H26Si2 (250.5): calcd. C 67.12,
products is considered to be determinated in the steps
involving the coordination of a carbon-carbon double
bond to the palladium atom in A (Scheme 3), and the
insertion of the double bond into a palladium-silicon
bond. Presumably, in these two steps, the formation of
the intermediates leading to the sterically unfavorable
isomers is of greater advantage than that of the others.
In conclusion, the palladium-catalyzed reactions
of cis- and trans-benzodisilacyclobut-3-enes 1a and
1b with alkynes proceeded with high stereospeci-
ficity to give the respective adducts, cis- and trans-
benzodisilacyclohex-2,5-dienes. In the reactions of 1a
and 1b with alkenes, the cis and trans configurations of
the starting compounds were maintained in all adducts. H 10.46; found C 67.14, H 10.41.
Unauthenticated
Download Date | 10/23/16 9:34 AM

1586
A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
Preparation of 1,2-bis(chloroisopropylmethylsilyl)benzene
Me2CH), 1.13 – 1.24 (m, 2H, CHMe2), 7.31 (dd, 2H, pheny-
lene ring protons, J = 5.4 Hz, J = 3.1 Hz), 7.44 (dd,
2H, phenylene ring protons, J = 5.4 Hz, J = 3.1 Hz). –
13C NMR (CDCl3): δ = −5.4 (MeSi), 14.8 (CHMe2), 18.6,
18.8 (Me2CH), 128.9, 131.9, 155.9 (phenylene ring car-
bons). – 29Si NMR (CDCl3): δ = 6.9. – MS: m/z = 248
[M]+. – C14H24Si2 (248.5): calcd. C 67.66, H 9.73; found
C 67.46, H 9.62.
In a 1 L three-necked flask fitted with a stirrer, a re-
flux condenser, and an inlet tube for chlorine gas were
placed 287.1 g (1.2 mol) of 1,2-bis(isopropylmethylsilyl)-
benzene containing two diastereomers in a ratio of 1 : 1,
in 800 mL of dry carbon tetrachloride. Dry chlorine gas
was introduced into the stirred solution with ice cooling un-
til the solution became slightly yellow. At this point, GLC
analysis of the mixture showed that the starting hydrosi-
lane was transformed completely into a 1 : 1 mixture of
meso- and rac-1,2-bis(chloroisopropylmethylsilyl)benzene.
The solvent was distilled off, and the residue was distilled
under reduced pressure to give 340.0 g (92 % yield) of 1,2-
bis(chloroisopropylmethylsilyl)benzene. – B. p. 137 – 140 ◦C
/1.33 mbar. – IR (film): ν = 2958, 2867, 1463, 1257, 1118,
998, 881, 794, 744 cm−1. – 1H NMR (CDCl3): δ = 0.75
(s, 6H, MeSi), 0.77 (s, 6H, MeSi), 1.00 – 1.08 (m, 24H,
Me2CH), 1.50 – 1.60 (m, 4H, HCMe2), 7.43 (dd, 4H, pheny-
lene ring protons, J = 5.5 Hz, J = 3.4 Hz), 7.87 (dd, 4H,
phenylene ring protons, J = 5.5 Hz, J = 3.4 Hz). – 13C NMR
(CDCl3): δ = 1.4, 1.7 (MeSi), 16.4, 16.6 (CHMe2), 16.8,
16.85, 16.91 (2C) (Me2CH), 128.8 (2C), 136.2, 136.3, 140.4,
140.5 (phenylene ring carbons). – 29Si NMR (CDCl3): δ =
25.9, 26.0. – MS: m/z = 303 [M – Me]+. – C14H24Cl2Si2
(319.4): calcd. C 52.64, H 7.57; found C 52.74, H 7.53.
Palladium-catalyzed reactions of 1a with diphenylacetylene
A mixture of 0.140 g (0.56 mmol) of 1a, 0.357 g
(2.00 mmol) of diphenylacetylene, and 0.0321
g
(0.028 mmol) of tetrakis(triphenylphosphine)palladium(0)
in 0.5 mL of benzene was heated in a degassed sealed
tube at 80 ◦C for 24 h. The resulting mixture was chro-
matographed on silica gel eluting with hexane to give 0.229 g
(95 % yield) of 2a. No other stereoisomers were detected by
GLC and spectrometric analyses. ◦
Data for 2a: M. p. 112 – 113 C. – IR (KBr disk): ν =
3060, 2957, 2863, 1484, 1463, 1262, 1119, 1002, 908, 855,
795, 734 cm−1. – 1H NMR (CDCl3): δ = 0.28 (s, 6H, MeSi),
1.00 (d, 6H, MeCH, J = 7.4 Hz), 1.08 (d, 6H, MeCH, J =
7.4 Hz), 1.16 – 1.20 (m, 2H, CMe2), 6.86 (d, 4H, phenyl ring
protons, J = 7.6 Hz), 6.95 – 6.98 (m, 2H, phenyl ring pro-
tons), 7.06 – 7.09 (m, 4H, phenyl ring protons), 7.42 – 7.44
(m, 2H, phenylene ring protons), 7.63 – 7.65 (m, 2H, pheny-
lene ring protons). – 13C NMR (CDCl3): δ = −4.0 (MeSi),
14.0 (CHMe2), 18.2, 18.8 (Me2CH), 124.9, 127.2, 127.8,
128.3, 134.4, 142.9, 143.5, 157.6 (phenyl and phenylene ring
carbons, and olefinic carbons). – 29Si NMR (CDCl3): δ =
−16.7. – MS: m/z = 426 [M]+. – C28H34Si2 (426.7): calcd.
C 78.81, H 8.03; found C 78.59, H 7.98.
Preparation of cis- and trans-3,4-benzo-1,2-diisopropyl-1,2-
dimethyl-1,2- disilacyclobut-3-ene (1a and 1b)
In a 1 L flask fitted with a stirrer, a reflux condenser, and
a dropping funnel were placed 104.2 g (4.5 mol) of sodium
and 700 mL of dry toluene. The mixture was heated to re-
flux, and then a solution of 340.0 g (1.1 mol) of a mixture of
meso- and rac-1,2-bis(chloroisopropylmethylsilyl)benzene
in 100 mL of toluene was added over a period of 7 h. After
the mixture was heated to reflux for 18 h, it was filtered un-
der a nitrogen atmosphere. The solvent toluene was distilled
off, and the residue was distilled under reduced pressure to
give 238.7 g (91 % yield) of a mixture of 1a and 1b. This
mixture was fractionally distilled by using a spinning-band
column with 50 theoretical plates to give pure 1a (41.5 g,
17 % yield) and 1b (70.4 g, 25 % yield).
Palladium-catalyzed reactions of 1b with diphenylacetylene
A mixture of 0.292 g (1.18 mmol) of 1b, 0.591 g
(3.32 mmol) of diphenylacetylene, and 0.0520
g
(0.045 mmol) of tetrakis(triphenylphosphine)palladium(0) in
0.75 mL of dry benzene was heated in a sealed tube at 80 ◦C
for 24 h. The mixture was chromatographed on silica gel
eluting with hexane to give 0.468 g (93 % yield) of 2b.
◦
M. p. 67 – 68 C. – IR (KBr disk): ν = 3050, 2942, 2862,
Data for 1a: B. p. 76 – 77 ◦C/1.33 mbar. – 1H NMR 1483, 1462, 1254, 1120, 1001, 855, 794, 736, 701 cm−1. –
(CDCl3): δ = 0.34 (s, 6H, MeSi), 1.09 (d, 6H, Me2CH, J = 1H NMR (CDCl3): δ = 0.41 (s, 6H, MeSi), 0.72 (d, 6H,
7.4 Hz), 1.14 (d, 6H, Me2CH, J = 7.4 Hz), 1.25 (hept, 2H,
CHMe2, J = 7.4 Hz), 7.31 (dd, 2H, phenylene ring protons,
MeCH, J = 7.0 Hz), 0.81 – 0.90 (m, 2H, HCMe2), 0.93 (d,
6H, MeCH, J = 7.0 Hz), 6.81 (d, 4H, phenyl ring protons, J =
J = 5.4 Hz, J = 3.1 Hz), 7.45 (dd, 2H, phenylene ring pro- 8.3 Hz), 6.92 – 6.95 (m, 2H, phenyl ring protons), 7.02 – 7.05
tons, J = 5.4 Hz, J = 3.1 Hz). – 13C NMR (CDCl3): δ =
(m, 4H, phenyl ring protons), 7.38 (dd, 2H, phenylene ring
−6.5 (MeSi), 14.6 (CHMe2), 18.5, 18.9 (Me2CH), 129.0,
protons, J = 5.5 Hz, J = 3.3 Hz), 7.57 (dd, 2H, phenylene
132.0, 156.0 (phenylene ring carbons). – 29Si NMR (CDCl3): ring protons, J = 5.5 Hz, J = 3.3 Hz). – 13C NMR (CDCl3):
δ = 7.1. – MS: m/z = 248 [M]+. – C14H24Si2 (248.5): calcd.
δ = −3.6 (MeSi), 13.3 (CHMe2), 17.4, 17.6 (Me2CH),
C 67.66, H 9.73; found C 67.36, H 9.70.
125.0, 127.3, 127.9, 128.4, 133.7, 142.7, 143.4, 156.9
Data for 1b: B. p. 73 – 74 ◦C/1.33 mbar. – 1H NMR (phenyl and phenylene ring carbons, and olefinic carbons). –
(CDCl3): δ = 0.39 (s, 6H, MeSi), 1.05 – 1.09 (m, 12H, 29Si NMR (CDCl3): δ = −16.5. – MS: m/z = 426 [M]+. –
Unauthenticated
Download Date | 10/23/16 9:34 AM

A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
1587
C28H34Si2 (426.7): calcd. C 78.81, H 8.03; found C 78.69, yses. – IR (film): ν = 2956, 2863, 1462, 1361, 1258, 1131,
H 7.76.
1115, 999, 881, 858, 833, 799, 788, 740, 710, 703 cm−1. –
1H NMR (CDCl3): δ = 0.22 (s, 3H, MeSi), 0.56 (s, 3H,
MeSi), 0.76 (d, 3H, MeCH, J = 7.3 Hz), 0.93 – 1.15 (m, 11H,
i-Pr protons), 1.17 (s, 9H, t-Bu protons), 6.80 (s, 1H, HC=C),
7.31 – 7.36 (m, 2H, phenylene ring protons), 7.52 – 7.56 (m,
2H, phenylene ring protons). – 13C NMR (CDCl3): δ =
−5.7, −0.7 (MeSi), 15.1, 15.6 (CHMe2), 18.1, 18.3, 18.4,
18.8 (Me2CH), 31.1 (Me3C), 40.1 (CMe3), 127.3, 127.5,
133.7, 134.6, 138.1, 143.6, 143.8, 168.9 (phenylene and
olefinic carbons). – 29Si NMR (CDCl3): δ = −16.0 (2Si). –
MS: m/z = 315 [M – Me]+. – C20H34Si2 (330.7): calcd.
C 72.65, H 10.36; found C 72.54, H 10.26.
Palladium-catalyzed reaction of 1a and 1b with 1-hexyne
A mixture of 0.180 g (0.73 mmol) of 1a, 0.211 g
(2.57 mmol) of 1-hexyne, and 0.028 g (0.024 mmol) of
tetrakis(triphenylphosphine)palladium(0) in 0.5 mL of dry
benzene was heated in a sealed glass tube at 80 ◦C for 24 h.
The mixture was chromatographed on silica gel, using hex-
ane as the eluent, to give 0.219 g (91 % yield) of 3a. No
other isomers were detected by GLC and spectrometric anal-
yses. – IR (film): ν = 2953, 2862, 1464, 1250, 1120, 998,
919, 881, 742, 714 cm−1. – 1H NMR (CDCl3): δ = 0.23
(s, 3H, MeSi), 0.34 (s, 3H, MeSi), 0.89 – 1.02 (m, 17H, n-
Bu and i-Pr protons), 1.33 – 1.37 (m, 2H, n-Bu protons),
1.44 – 1.49 (m, 2H, n-Bu protons), 2.25 – 2.30 (m, 2H, n-
Bu protons), 6.63 (s, 1H, HC=C), 7.33 (dd, 2H, phenylene
protons, J = 5.5 Hz, J = 3.3 Hz), 7.52 (dd, 2H, phenylene
protons, J = 5.5 Hz, J = 3.3 Hz). – 13C NMR (CDCl3):
δ = −5.1, −5.0 (MeSi), 14.9, 15.1 (CHMe2), 18.0, 18.2,
18.3, 18.4 (Me2CH), 14.1, 22.7, 30.9, 39.1 (n-Bu), 127.56,
127.58, 133.8, 134.1, 139.3, 143.5, 143.9, 161.6 (phenylene
and olefinic carbons). – 29Si NMR (CDCl3): δ = −16.8,
−16.3. – MS: m/z = 287 [M – i-Pr]+. – C20H34Si2 (330.7):
calcd. C 72.65; H 10.36; found C 72.59, H 10.16.
Similar treatment of a mixture consisting of 0.241 g
(0.97 mmol) of 1b, 0.231 g (2.81 mmol) of 1-hexyne,
and 0.028 g (0.024 mmol) of tetrakis(triphenylphosphine)-
palladium(0) in 0.5 mL of benzene at 80 ◦C for 24 h afforded
0.299 g (93 % yield) of 3b. – IR (film): ν = 2954, 2862, 1461,
1245, 1120, 998, 881, 848, 823, 786, 735 cm−1. – 1H NMR
(CDCl3): δ = 0.25 (s, 3H, MeSi), 0.36 (s, 3H, MeSi), 0.83 –
1.04 (m, 17H, n-Bu and i-Pr protons), 1.33 – 1.54 (m, 4H, n-
Bu protons), 2.21 – 2.34 (m, 2H, n-Bu protons), 6.60 (s, 1H,
HC=C), 7.33 (dd, 2H, phenylene ring protons, J = 5.5 Hz, J =
3.3 Hz), 7.51 (dd, 2H, phenylene ring protons, J = 5.5 Hz, J =
3.3 Hz). – 13C NMR (CDCl3): δ = −4.8, −3.5 (MeSi), 14.1,
14.3 (CHMe2), 17.8 (2C), 17.9, 18.1, (Me2CH), 14.4, 22.6,
31.0, 39.5 (n-Bu), 127.5, 127.7, 133.1, 133.7, 138.5, 143.4,
143.8, 161.9 (phenylene and olefinic carbons). – 29Si NMR
(CDCl3): δ = −16.8, −16.2. – MS: m/z = 315 [M–Me]+. –
C20H34Si2 (330.7): calcd. C 72.65, H 10.36; found C 72.54,
H 10.35.
Similar treatment of a mixture consisting of 0.137 g
(0.56 mmol) of 1b, 0.211 g (2.56 mmol) of tert-butyl-
acetylene, and 0.032 g (0.028 mmol) of tetrakis(triphen-
◦
ylphosphine)palladium(0) in a sealed tube at 80 C for 24 h
gave 0.166 g (90 % yield) of 4b. – IR (film): ν = 2953,
2863, 1461, 1326, 1256, 1246, 1223, 1132, 1116, 1000, 880,
856, 832, 785, 742 cm−1. – 1H NMR (CDCl3): δ = 0.26
(s, 3H, MeSi), 0.59 (s, 3H, MeSi), 0.68 (d, 3H, MeCH, J =
7.3 Hz), 0.81-0.82 (m, 3H, MeCH), 0.94 (d, 3H, MeCH, J =
7.3 Hz), 0.99 – 1.11 (m, 5H, MeCH and HCMe2), 1.17 (s, 9H,
t-Bu), 6.80 (s, 1H, HC=C), 7.30 – 7.35 (m, 2H, phenylene
ring protons), 7.50 – 7.54 (m, 2H, phenylene ring protons). –
13C NMR (CDCl3): δ = −3.6, −1.2 (MeSi), 14.5, 15.3
(CHMe2), 17.8, 17.9, 18.0, 18.3 (Me2CH), 31.0 (Me3C),
40.2 (CMe3), 127.38, 127.42, 132.7, 134.2, 136.2, 143.3,
143.6, 169.5 (phenylene and olefinic carbons). – 29Si NMR
(CDCl3): δ = −16.1, −15.6. – MS: m/z = 287 [M – i-Pr]+. –
C20H34Si2 (330.7): calcd. C 72.65, H 10.36; found C 72.69,
H 10.32.
Palladium-catalyzed reaction of 1a and 1b with phenylacety-
lene
A mixture of 0.234 g (0.94 mmol) of 1a, 0.333 g
(3.26 mmol) of phenylacetylene, and 0.039 g (0.034 mmol)
of tetrakis(triphenylphosphine)palladium(0◦) in 0.5 mL of
benzene was heated in a sealed tube at 80 C for 24 h. The
mixture was chromatographed on silica gel eluting with hex-
ane to give 0.312 g (94 % yield) of 5a. No other stereoiso-
mers were detected by GLC and spectrometric analyses. –
IR (film): ν = 3057, 2956, 2862, 1488, 1462, 1251, 1117,
998, 880, 815, 789, 768, 714 cm−1. – 1H NMR (CDCl3): δ =
0.31 (s, 3H, MeSi), 0.42 (s, 3H, MeSi), 0.81 (d, 3H, MeCH,
J = 7.1 Hz), 0.96 – 1.09 (m, 11H, i-Pr, MeCH, and CHMe2),
Palladium-catalyzed reactions of 1a and 1b with tert-
butylacetylene
A mixture of 0.138 g (0.56 mmol) of 1a, 0.193 g 6.84 (s, 1H, HC=C), 7.20 – 7.25 (m, 3H, phenyl ring protons),
(2.35 mmol) of tert-butylacetylene, and 0.0330 7.30 – 7.33 (m, 2H, phenyl ring protons), 7.36 – 7.39 (m, 2H,
g
(0.029 mmol) of tetrakis(triphenylphosphine)palladium(0) phenylene ring protons), 7.57 – 7.59 (m, 2H, phenylene ring
◦
in 0.5 mL of benzene in a sealed tube was heated at 80 C protons). – 13C NMR (CDCl3): δ = −5.0, −3.5 (MeSi), 14.9,
for 24 h. The mixture was chromatographed on silica gel 15.0 (CHMe2), 18.0 (2C), 18.25, 18.31 (Me2CH), 126.3,
eluting with hexane to give 0.171 g (93 % yield) of 4a. No 126.6, 127.80, 127.83, 128.1, 133.9, 134.4, 143.0, 143.3,
other isomers were detected by GLC and spectrometric anal- 145.5, 148.4, 161.9 (phenyl, phenylene and olefinic car-
Unauthenticated
Download Date | 10/23/16 9:34 AM

1588
A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
bons). – 29Si NMR (CDCl3): δ = −16.5, −15.8. – MS: m/z (s, 1H, HC=C). – 13C NMR (CDCl3): δ = −4.0, −3.0
= 307 [M – i-Pr]+. – C22H30Si2 (350.6): calcd. C 75.36, (MeSi), 0.0 (Me3Si), 14.2, 14.7 (CHMe2), 17.8, 17.87,
H 8.62; found C 75.66, H 8.63.
17.90, 18.0 (Me2CH), 127.5, 127.6, 133.1, 133.9, 143.4,
143.6, 160.5, 168.9 (phenylene and olefinic carbons). –
29Si NMR (CDCl3): δ = −22.0, −16.7, −4.3. – MS: m/z
= 346 [M]+. – C19H34Si3 (346.7): calcd. C 65.82. H 9.88;
found C 65.52, H 9.94.
Similar treatment of a mixture consisting of 0.194 g
(0.78 mmol) of 1b, 0.338 g (3.31 mmol) of phenylacety-
lene, and 0.0290 g (0.025 mmol) of a palladium catalyst pro-
duced 0.259 g (94 % yield) of 5b. – IR (film): ν = 3057,
2954, 2890, 1488, 1463, 1246, 1120, 998, 880, 867, 818,
Palladium-catalyzed reactions of 1a with styrene
1
788, 736, 700 cm−1. – H NMR (CDCl3): δ = 0.35 (s, 3H,
MeSi), 0.46 (s, 3H, MeSi), 0.73 (d, 3H, MeCH, J = 7.1 Hz),
0.88 – 1.08 (m, 11H, i-Pr, MeCH, and CHMe2), 6.81 (s, 1H,
HC=C), 7.22 – 7.26 (m, 3H, phenyl ring protons), 7.31 – 7.38
(m, 4H, phenyl and phenylene ring protons), 7.56 – 7.57 (m,
2H, phenylene ring protons). – 13C NMR (CDCl3): δ = −3.8,
−3.4 (MeSi), 14.39, 14.40 (CHMe2), 17.6, 17.75, 17.81,
17.9 (Me2CH), 126.3, 126.6, 127.8, 127.9, 128.1, 133.2,
134.0, 143.0, 143.2, 144.6, 148.4, 162.1 (phenyl, phenylene
and olefinic carbons). – 29Si NMR (CDCl3): δ = −16.2,
−15.9. – MS: m/z = 307 [M – i-Pr]+. – C22H30Si2 (350.6):
calcd. C 75.36, H 8.62; found C 75.41, H 8.62.
A mixture of 0.1008 g (0.406 mmol) of 1a, 0.1180 g
(1.13 mmol) of styrene, and 0.0232 g (0.0201 mmol) of
tetrakis(triphenylphosphine)palladium(0) in 0.5 mL of ben-
zene was heated in a degassed sealed tube at 110 ◦C for 24 h.
The resulting mixture was applied to a short silica gel col-
umn to give 0.1030 g (72 % yield) of the mixture consisting
of 7a and 8a. The ratio of 7a and 8a was determined to be
5 : 3 by 1H NMR spectroscopy. Compounds 7a and 8a were
isolated by MPLC.
1
Data for 7a: H NMR (CDCl3): δ = 0.12 (s, 3H, MeSi),
0.29 (s, 3H, MeSi), 0.91 (d, 3H, i-Pr-Me, J = 6.6 Hz), 1.09 –
1.14 (m, 11H, i-Pr-Me, CHSi), 1.39 (dd, 1H, CHSi, J =
14.3 Hz, 3.1 Hz), 1.51 (t, 1H, CHSi, J = 14.3 Hz), 2.84 (dd,
1H, CHPh, J = 14.3 Hz, 3.1 Hz), 7.16 – 7.63 (m, 9H, phenyl
and phenylene ring protons). – 13C NMR (CDCl3): δ =
−6.0, −5.9 (MeSi), 12.6 (CH2Si), 13.0, 14.4 (CHSi), 17.6,
17.7, 18.1, 18.2 (MeCH), 26.0 (CHPh), 124.6, 127.5, 127.8,
128.0, 128.1, 134.2, 134.3, 144.2, 144.7, 147.4 (phenyl and
phenylene ring carbons). – 29Si NMR (CDCl3): δ = −2.33,
−2.27. – MS: m/z = 352 [M]+. – C22H32Si2 (352.7): calcd.
C 74.93, H 9.15; found C 74.64, H 9.11.
Palladium-catalyzed reaction of 1a and 1b with trimethylsi-
lylacetylene
A mixture of 0.160 g (0.64 mmol) of 1a, 0.254 g
(2.59 mmol) of trimethylsilylacetylene, and 0.036
g
(0.031 mmol) of tetrakis(triphenylphosphine)palladium(0)◦in
0.5 mL of benzene was heated in a sealed tube at 80 C
for 24 h. The mixture was chromatographed on silica gel
eluting with hexane to give 0.113 g (50 % yield) of 6a. No
other isomers were detected by GLC and spectrometric anal-
yses. – IR (film): ν = 2953, 2892, 2863, 1462, 1247, 1117,
998, 899, 882, 832, 744, 709 cm−1. – 1H NMR (CDCl3):
δ = 0.14 (s, 9H, Me3Si), 0.25 (s, 3H, MeSi), 0.40 (s, 3H,
MeSi), 0.77 (d, 3H, MeCH, J = 7.3 Hz), 0.94 – 1.05 (m, 11H,
i-Pr, MeCH, and CHMe2), 7.30 – 7.34 (m, 2H, phenylene
ring protons), 7.48 – 7.54 (m, 2H, phenylene ring protons),
7.72 (s, 1H, HC=C). – 13C NMR (CDCl3): δ = −5.9, −2.9
(MeSi), 0.1 (Me3Si), 15.0, 15.2 (CHMe2), 18.1, 18.3 (2C),
18.5 (Me2CH), 127.5, 127.6, 134.0, 134.3, 143.5, 143.7,
162.0, 168.4 (phenylene and olefinic carbons). – 29Si NMR
(CDCl3): δ = −22.3, −16.6, −4.2. – MS: m/z = 346 [M]+. –
C19H34Si3 (346.7): calcd. C 65.82, H 9.88; found C 65.60,
H 9.78.
1
Data for 8a: H NMR (CDCl3): δ = 0.09 (s, 3H, MeSi),
0.25 (s, 3H, MeSi), 0.77 (d, 3H, i-Pr-Me, J = 7.3 Hz), 0.80
(d, 3H, i-Pr-Me, J = 7.3 Hz), 1.01 (d, 3H, i-Pr-Me, J =
6.8 Hz), 1.10 (d, 3H, i-Pr-Me, J = 6.8 Hz), 1.00 – 1.13 (m,
2H, CHMe), 1.21 (dd, 1H, CHSi, J = 14.3 Hz, 2.4 Hz), 1.75
(dd, 1H, ring CHSi, J = 15.3 Hz, 14.3 Hz), 2.63 (dd, 1H,
CHPh, J = 15.3 Hz, 2.4 Hz), 7.14 – 7.55 (m, 9H, phenyl
and phenylene ring protons). – 13C NMR (CDCl3): δ =
−5.7, −4.0 (MeSi), 10.6 (CH2Si), 11.4, 13.6 (CHSi), 17.6,
18.0, 18.8, 19.4 (MeCH), 29.1 (CHPh), 124.5, 127.1, 127.7,
128.0, 128.1, 133.8, 134.7, 144.1, 144.3, 146.5 (phenyl and
phenylene ring carbons). – 29Si NMR (CDCl3): δ = −0.96,
−1.00. – MS: m/z = 352 [M]+. – C22H32Si2 (352.7): calcd.
C 74.93, H 9.15; found C 74.77, H 9.01.
Similar treatment of a mixture consisting of 0.166 g
(0.67 mmol) of 1b, 0.241 g (2.45 mmol) of phenylacety-
lene, and 0.0330 g (0.029 mmol) of a palladium catalyst
produced 0.159 g (77 % yield) of 6b. – IR (film): ν =
Palladium-catalyzed reactions of 1b with styrene
A mixture of 0.1050 g (0.423 mmol) of 1b, 0.1236 g
2952, 2922, 2891, 1463, 1246, 1118, 998, 899, 882, 804, (1.19 mmol) of styrene, and 0.0230 g (0.0199 mmol) of
785, 743, 707 cm−1. – 1H NMR (CDCl3): δ = 0.15 (s, tetrakis(triphenylphosphine)palladium(0) in 0.5 mL of dry
9H, Me3Si), 0.27 (s, 3H, MeSi), 0.43 (s, 3H, MeSi), 0.70 benzene was heated in a sealed tube at 110 ◦C for 24 h. The
(d, 3H, MeCH, J = 7.3 Hz), 0.84 – 1.04 (m, 11H, i-Pr, mixture was purified by chromatography through silica gel
MeCH, and CHMe2), 7.29 – 7.34 (m, 2H, phenylene ring column eluting with hexane to give 0.1192 g (80 % yield) of
protons), 7.48 – 7.54 (m, 2H, phenylene ring protons), 7.69 a mixture consisting of 7b and 8b. The ratio of 7b and 8b was
Unauthenticated
Download Date | 10/23/16 9:34 AM

A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
1589
determined to be 2 : 1 by 1H NMR spectroscopy. – 1H NMR tons). – 13C NMR (CDCl3): δ = −7.4, −6.4, −5.3, −3.8
(CDCl3): δ = 0.28 (s, 3H, MeSi, 8b), 0.41 (s, 3H, MeSi, 7b), (MeSi), 10.3, 11.1 (CH2Si), 12.4, 13.4 (2C), 13.7, 14.1,
0.415 (s, 3H, MeSi, 7b), 0.419 (s, 3H, MeSi, 8b), 0.88 (d, 3H, 14.2, 16.1, 17.55, 17.60, 17.98, 18.01, 18.2, 18.3, 19.1,
i-Pr-Me, J = 7.0 Hz, 7b), 0.90 (d, 3H, i-Pr-Me, J = 7.0 Hz, 19.3, 20.4, 22.67, 22.68, 30.3, 30.6, 33.1, 33.6 (i-Pr, n-Bu,
7b), 0.92 (d, 3H, i-Pr-Me, J = 7.0 Hz, 8b), 1.10 (d, 3H, i- CHSi), 127.48, 127.52, 127.8 (2C), 133.7, 133.9, 134.3,
Pr-Me, J = 7.0 Hz, 8b), 1.13 (d, 3H, i-Pr-Me, J = 7.0 Hz, 134.4, 144.6, 144.7, 144.9, 145.2 (phenylene ring carbons). –
7b), 1.18 (d, 3H, i-Pr-Me, J = 7.0 Hz, 8b), 1.20 (d, 3H, i-Pr- 29Si NMR (CDCl3): δ = −4.0, −3.4, −2.1, −1.9. – MS: m/z
Me, J = 7.0 Hz, 7b), 1.21 (d, 3H, i-Pr-Me, J = 7.0 Hz, 8b), = 332 [M]+. – C20H36Si2 (332.7): calcd. C 72.21, H 10.91;
1.00 – 1.34 (m, 4H, CHMe, 7b and 8b), 1.57 (dd, 2H, ring found C 72.00, H 10.98.
CHSi, J = 15.0 Hz, 3.0 Hz, 7b and 8b), 1.69 (t, 1H, CH, J =
15.0 Hz, 8b), 1.75 (t, 1H, CH, J = 15.0 Hz, 7b), 2.81 (dd,
1H, CHPh, J = 15.0 Hz, 2.5 Hz, 8b), 2.84 (dd, 1H, CHPh,
J = 15.0 Hz, 2.5 Hz, 7b), 7.27 – 7.72 (m, 18H, phenyl and
phenylene ring protons, 7b and 8b). – 13C NMR (CDCl3):
δ = −6.1 (8b), −5.3 (7b), −5.0 (7b), −4.3 (8b) (MeSi), 11.8
(7b), 12.1 (8b) (CH2Si), 12.4 (8b), 12.6 (7b), 13.3 (8b), 13.7
(7b) (CHSi), 17.4 (8b), 17.6 (8b), 17.7 (7b), 17.9 (8b), 18.0
(8b), 18.3 (7b), 18.6 (7b), 19.2 (7b) (MeCH), 25.7 (8b), 29.9
(7b) (CHPh), 124.5 (7b), 124.6 (8b), 127.0 (7b), 127.5 (7b),
127.7 (8b), 127.85 (8b), 127.88 (8b), 127.97 (8b), 128.03
(7b), 128.1 (7b), 133.7 (8b), 133.9 (8b), 134.1 (7b), 134.5
(7b), 143.9 (7b), 144.1 (7b), 144.4 (8b), 144.5 (8b), 146.4
(7b), 147.5 (8b) (phenyl and phenylene ring carbons). –
29Si NMR (CDCl3): δ = −4.2, −2.6, −2.4, −1.2. – MS: m/z
= 352 [M]+. – C22H32Si2 (352.7): calcd. C 74.93, H 9.15;
found C 74.67, H 9.10.
Palladium-catalyzed reactions of 1b with 1-hexene
A mixture of 0.1021 g (0.411 mmol) of 1b, 0.1102 g
(1.33 mmol) of 1-hexene, and 0.0232 g (0.0201 mmol) of
tetrakis(triphenylphosphine)palladium(0) in 0.5 mL of dry
benzene was heated in a sealed tube at 110 ◦C for 24 h. The
mixture was purified by chromatography through silica gel
column eluting with hexane to give 0.1107 g (81 % yield)
of 9b. – 1H NMR (CDCl3): δ = 0.19 (s, 3H, MeSi), 0.25
(s, 3H, MeSi), 0.78 (t, 3H, CH3, J = 14.5 Hz), 0.90 – 1.06
(m, 16H, MeCH, CH2), 1.24 – 1.42 (m, 4H, CHSi, CH2),
1.34 (dd, 1H, CH, J = 15 Hz, 4 Hz), 1.58 – 1.64 (m, 1H,
CH), 1.69 – 1.74 (m, 1H, CH), 7.31 – 7.34 (m, 2H, phenyl
ring protons), 7.48 – 7.52 (m, 2H, phenylene ring protons). –
13C NMR (CDCl3): δ = −5.8, −4.7 (MeSi), 11.8 (CH2Si),
12.9, 14.0, 14.1 (CHSi), 17.8, 18.3, 19.0, 19.3, 21.0 (Me),
22.7, 30.6, 33.6 (CH2), 127.5, 127.6, 133.9, 134.2, 144.6,
144.7 (phenylene ring carbons). – 29Si NMR (CDCl3): δ =
−4.0, −3.9. – MS: m/z = 332 [M]+. – C20H36Si2 (332.7):
calcd. C 72.21, H 10.91; found C 72.11, H 10.76.
Palladium-catalyzed reactions of 1a with 1-hexene
A mixture of 0.1006 g (0.405 mmol) of 1a, 0.1203 g
(1.43 mmol) of 1-hexene, and 0.0232 g (0.0201 mmol)
of tetrakis(triphenylphosphine)palladium(0) in 0.5 mL of
benzene was heated in a degassed sealed tube at 110 ◦C
for 24 h. The resulting mixture was purified by chromatog-
raphy through silica gel column eluting with hexane to
give 0.0943 g (70 % yield) of a mixture consisting of 9a
and 10a. The ratio of 9a and 10a was determined to be 1 : 1
by 1H NMR spectroscopy.
Crystal structure analysis
The structure determination of 2a suffered from a weakly
diffracting crystal and a low completeness of the data set.
As a consequence, a poor data to parameter ratio precludes
a detailled discussion of distances and angles, although the
observed cis configuration could be clearly confirmed [19].
Data for 9a and 10a: 1H NMR (CDCl3): δ = 0.16
(s, 6H, MeSi), 0.19 (s, 3H, MeSi), 0.23 (s, 3H, MeSi),
0.70 – 1.11 (m, 38H, Me,CH2), 1.22 – 1.37 (m, 10H, CHSi,
CH2), 1.54 – 1.74 (m, 4H, CH), 7.29 – 7.33 (m, 4H, pheny-
lene ring protons), 7.46 – 7.50 (m, 4H, phenylene ring pro-
Acknowledgement
We thank Shin-Etsu Co., Ltd., for a gift of organochlorosi-
lanes.
[1] C.-S. Liu, J. L. Margrave, J. C. Thompson, Can. J.
Chem. 1972, 50, 465.
[2] W. H. Atwell, J. G. Uhlmann, J. Organomet. Chem.
[5] D. Seyferth, S. C. Vick, J. Organomet. Chem. 1997,
125, C11.
[6] H. Sakurai, T. Kobayashi, Y. Nakadaira, J. Organomet.
Chem. 1998, 162, C43.
[7] M. Ishikawa, H. Sugisawa, M. Kumada, H Kawakami,
T. Yamabe, Organometallics 1983, 2, 974.
[8] M. J. Fink, J. Deyoung, R. West, J. Michl, J. Am. Chem.
Soc. 1983, 105, 1070.
1973, 52, C21.
[3] C.-S. Liu, C.-W. Cheng, J. Am. Chem. Soc. 1975, 97,
6746.
[4] T. J. Barton, J. A. Kilgour, J. Am. Chem. Soc. 1976, 98,
7746.
Unauthenticated
Download Date | 10/23/16 9:34 AM

1590
A. Naka et al. · Stereochemistry of Disilanylene-containing Cyclic Compounds
[9] C. H. Lin, C. Y. Lee, C. S. Lin, J. Am. Chem. Soc. 1986,
108, 1323.
M. Takeda, T. Matsumoto, H. Matsumoto, J. Chem.
Soc., Chem. Commun. 2001, 2714.
[10] K. Shiina, J. Organomet. Chem. 1986, 310, C57.
[11] a) M. Ishikawa, H. Sakamoto, T. Tabuchi, Organomet-
allics 1991, 10, 3173; b) H. Sakamoto, M. Ishikawa,
Organometallics 1992, 11, 2580; c) A. Naka,
M. Ishikawa, Synlett. 1995, 794, and ref. cited therein;
d) A. Naka, T. Okada, M. Ishikawa, J. Organomet.
Chem. 1996, 521, 163; e) A. Naka, T. Okada, A. Ku-
nai, M. Ishikawa, J. Organomet. Chem. 1997, 547,
149.
[15] a) K. Yoshizawa, S.-Y. Kang, T. Yamabe, A. Naka,
M. Ishikawa, Organometallics 1999, 18, 4637;
b) S.-Y. Kang, T. Yamabe, A. Naka, M. Ishikawa,
K. Yoshizawa, Organometallics 2002, 21, 150.
[16] a) M. Ishikawa, J. Ikadai, A. Naka, J. Ohshita, A. Ku-
nai, K. Yoshizawa, S.-Y. Kang, T. Yamabe, Organomet-
allics 2001, 20, 1059; b) A. Naka, J. Ikadai, J. Sakata,
I. Miyahara, K. Hirotsu, M. Ishikawa, Organometallics
2004, 23, 2397.
[12] a) T. Kusukawa, Y. Kabe, B. Nestler, W. Ando,
Organometallics 1995, 14, 256; b) T. Kusukawa,
S. Shike, W. Ando, Tetrahedron 1996, 52, 4995.
[13] Y. Uchimaru, M. Tanaka, J. Organomet. Chem. 1996,
521, 335.
[14] a) S. Kyushin, R. Kitahara, H. Matsumoto, Chem. Lett.
1998, 27, 471; b) S. Kyushin, T. Kitahara, R. Tanaka,
[17] A. Naka, K. Yoshida, M. Ishikawa, I. Miyahara, K. Hi-
rostsu, S.-H. Cha, K. K. Lee, K. W. Kwak, Organomet-
allics 2001, 20, 1204.
[18] S.-H. Cha, K. K. Lee, Y.-W. Kwak, H.-J. Cho, Y. S.
Park, A. Naka, M. Ishikawa, Organometallics 2001,
20, 3718.
[19] A. Naka, J. Ohshita, M. Ishikawa, unpublished results.
Unauthenticated
Download Date | 10/23/16 9:34 AM