Stereoselective synthesis of highly enantioenriched (E)-allylsilanes by palladium-catalyzed intramolecular bis-silylation: 1,3-chirality transfer and enantioenrichment via dimer formation

Article abstract of DOI:10.1002/chem.200401031

Highly enantioenriched (E)-allylsilanes have been synthesized from optically active allylic alcohols on the basis of Pd-catalyzed intramolecular bis-silylation followed by highly stereo-specific Si-O elimination reactions. The method involves three steps: 1) O-disilanylation of the allylic alcohols with chlorodisilanes, 2) intramolecular bis-silylation in the presence of a 1,1,3,3-tetramethylbutyl isocyanide/[Pd-(acac)2] (acac = acetylacetonate) catalyst at 110°C, and 3) treatment of the reaction mixture with organolithium reagents. The overall transformation proceeds with nearly complete conservation of the enantiopurity of the starting allyl alcohols by transposition of the C=C bond. For instance, (R)-(E)-3-decen-2-ol (99.6-99.7 % ee) produced (S)-(E)-4-(organosilyl)-2-decene of 98.8-99.4% ee for a variety of silyl groups, including Me₃Si, Me₂PhSi, tBu-Me ₂Si, Et₃Si, and iPr₃Si. In the bis-silylation step, the initially formed trans-1,2-oxasiletanes immediately dimerize to stereoselectively give 1,5-dioxa-2,6-disilacyclooctanes, which are isolated in high yield by carrying out the reaction at ₇₀C. The eight-membered ring compounds undergo thermal extrusion of (E)-allylsilanes in high yield at 110°C, along with formation of 1,3- dioxa-2,5-disilacyclohexane derivatives. These in turn undergo a Peterson-type elimination by treatment with nucleophiles such as BuLi and PhLi to give the (E)-allylsilanes. All of the steps involved in the sequence proceed with extremely high stereoselectivity and stereospecificity, leading to almost complete 1,3-chirality transfer through the overall transformation. The dimerization step, which forms diastereomeric intermediates, allows the synthesis of a highly enantioenriched allylsilane (99.4% ee) from an optically active allylic alcohol with lower enantiopurity (79.2% ee) by enrichment of enantiopurity. A general method for the determination of the enantiomeric excesses of (E)-allylsilanes is also described in detail.

Full text of DOI:10.1002/chem.200401031

Stereoselective Synthesis of Highly Enantioenriched (E)-Allylsilanes by
Palladium-Catalyzed Intramolecular Bis-Silylation: 1,3-Chirality Transfer and
Enantioenrichment via Dimer Formation
Michinori Suginome,*[a, b] Taisuke Iwanami,[a] Yutaka Ohmori,[a] Akira Matsumoto,[a] and
Yoshihiko Ito[a]
Abstract: Highly enantioenriched (E)-
allylsilanes have been synthesized from
optically active allylic alcohols on the
basis of Pd-catalyzed intramolecular
bis-silylation followed by highly stereo-
(S)-(E)-4-(organosilyl)-2-decene
of
elimination by treatment with nucleo-
philes such as BuLi and PhLi to give
the (E)-allylsilanes. All of the steps in-
volved in the sequence proceed with
extremely high stereoselectivity and
stereospecificity, leading to almost
complete 1,3-chirality transfer through
the overall transformation. The dimeri-
zation step, which forms diastereomeric
intermediates, allows the synthesis of a
98.8–99.4% ee for a variety of silyl
groups, including Me3Si, Me2PhSi, tBu-
Me2Si, Et3Si, and iPr3Si. In the bis-sily-
lation step, the initially formed trans-
1,2-oxasiletanes immediately dimerize
to stereoselectively give 1,5-dioxa-2,6-
disilacyclooctanes, which are isolated in
high yield by carrying out the reaction
at 708C. The eight-membered ring
compounds undergo thermal extrusion
of (E)-allylsilanes in high yield at
1108C, along with formation of 1,3-
dioxa-2,5-disilacyclohexane derivatives.
These in turn undergo a Peterson-type
À
specific Si O elimination reactions.
The method involves three steps: 1) O-
disilanylation of the allylic alcohols
with chlorodisilanes, 2) intramolecular
bis-silylation in the presence of
a
1,1,3,3-tetramethylbutyl isocyanide/[Pd-
(acac)2] (acac=acetylacetonate) cata-
lyst at 1108C, and 3) treatment of the
reaction mixture with organolithium
reagents. The overall transformation
proceeds with nearly complete conser-
vation of the enantiopurity of the start-
ing allyl alcohols by transposition of
the C=C bond. For instance, (R)-(E)-3-
decen-2-ol (99.6–99.7% ee) produced
highly
enantioenriched
allylsilane
(99.4% ee) from an optically active al-
lylic alcohol with lower enantiopurity
(79.2% ee) by enrichment of enantio-
purity. A general method for the deter-
mination of the enantiomeric excesses
of (E)-allylsilanes is also described in
detail.
Keywords: asymmetric synthesis ·
dimerization · palladium catalyst ·
silicon · silylation
Introduction
Allylsilane is one of the most versatile reagents for stereose-
lective allylation reactions in organic synthesis, which has
been utilized with a variety of electrophiles, such as carbon-
yl compounds activated by Lewis acids.[1] The synthetic use-
fulness of allylsilanes has also been demonstrated by Lewis
acid catalyzed cycloaddition reactions[2] and metal-catalyzed
carbosilylation reactions.[3] The configurational stability,
which is due to the covalent nature of silicon–carbon bonds,
is of major importance.[4] Thus, synthesis and isolation of
regio- and stereochemically defined allylsilanes are readily
achieved without any detectable allylic transposition, which
would lead to nonselective allylations. In general, allylsi-
lanes undergo electrophilic reaction selectively at the g-posi-
tion in an SE2’ fashion. Their synthetically useful features
[a] Prof. Dr. M. Suginome, Dr. T. Iwanami, Y. Ohmori,
Dr. A. Matsumoto, Prof. Dr. Y. Ito+
Kyoto University
Department of Synthetic Chemistry and Biological Chemistry
Graduate School of Engineering
Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)
Fax : (+81)75-383-2722
E-mail: suginome@sbchem.kyoto-u.ac.jp
[b] Prof. Dr. M. Suginome
PRESTO, Japan Science and Technology Corporation
Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)
[+] Current address: Department of Molecular Science and Technology
Faculty of Engineering, Doshisha University, Kyotanabe, Kyoto 610-
0394 (Japan)
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DOI: 10.1002/chem.200401031
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FULL PAPER
have prompted the development of a number of preparative
methods for achiral and racemic allylsilanes.[5]
Results and Discussion
In 1982, Hayashi and Kumada reported the synthesis and
reactions of enantiomerically enriched allylsilanes, demon-
strating the potential usefulness of such allylsilanes in asym-
metric organic synthesis.[6,7] The chirality at the stereogenic
allylic carbon atom bound to the silicon atom was stereose-
lectively transferred to the newly formed g-stereogenic
carbon center by the SE2’ reaction. Since then, methods for
the synthesis of enantioenriched allylsilanes have been re-
ported and utilized successfully for organic synthesis.[8–15]
However, development of new synthetic methodologies for
the preparation of enantiomerically pure allylsilanes are still
desired for highly stereoselective organic synthesis.
Intramolecular bis-silylation of achiral and racemic allylic al-
cohols: Disilanyl ether (E)-3a, which was prepared in high
yield from (E)-2-nonen-1-ol and 1-chloro-1,1,2-triphenyl-2,2-
dimethyldisilane[22] in the presence of triethylamine with a
catalytic amount of 4-dimethylaminopyridine (DMAP), was
allowed to react in the presence of a catalyst generated
from [Pd(acac)2] (2 mol%) and 1,1,3,3-tetramethylbutyl iso-
cyanide (tOcNC, 8 mol%) under reflux in benzene
(Scheme 2). We chose this particular disilanyl group because
We have developed a new stereoselective synthesis of or-
ganosilicon compounds by palladium-catalyzed intramolecu-
lar bis-silylation (IBS).[16,17] In particular, the IBS of homo-
allylic alcohols provided an efficient and stereoselective sili-
con–carbon bond-forming reaction, whose synthetic useful-
ness was demonstrated by the synthesis of stereodefined
polyols.[18] In the course of the program, we became interest-
ed in the application of IBS to the synthesis of stereodefined
allylsilanes, particularly those with high enantiopurity.[19]
Our strategy for the stereoselective synthesis of allyl-
silanes 1 is based on IBS with enantiomerically pure secon-
dary allylic alcohols 2, as outlined in Scheme 1. Introduction
Scheme 2. IBS of disilanyl ethers derived from prim-allylic alcohols.
our previous study showed that the two phenyl groups on
the silicon atom bound to the ether oxygen were crucial to
achieve sufficient reactivity for addition to an internal C=C
bond as well as to attain high stereoselectivity.[18b,d] The
starting (E)-3a was completely consumed after 2 h, and a
1:2 mixture of two isomeric products 4a (R = n-Hex) was
isolated in high total yield (96%) by silica gel column chro-
matography. Although the major isomer was isolated in a di-
astereomerically pure form by washing the diastereomeric
mixture with AcOEt, we could not establish the stereochem-
istry by spectroscopic analyses. Fortunately, we were able to
identify the stereochemistry of 4a’ (R = Et). Thus, the X-
ray analysis of the major product isolated by recrystalliza-
tion showed an eight-membered cyclic structure trans-4a’,
which may be derived by dimerization of the initially
formed oxasiletane 5a’ (Figure 1). By analogy, it was pre-
sumed that trans-4a, which was derived by the dimerization
of oxasiletane 5a of opposite absolute configuration, was
formed as the major isomer in the reaction of (E)-3a. On
the other hand, the minor isomer may be assigned to cis-4a,
which was formed by dimerization of oxasiletane with the
same absolute configuration. The stereochemistry of the
Scheme 1. A synthetic plan for allylsilanes from allyllic alcohols by intra-
molecular bis-silylation and Peterson-type elimination.
of a disilanyl group on the hydroxy group of 2 is followed
À
by palladium-catalyzed IBS, which may create two new Si
C bonds in a regio- and stereoselective manner. Subsequent
Peterson-type elimination[20] from the four-membered oxasi-
letane intermediate is expected to produce allylsilanes with
overall transposition of the starting C=C bond. To achieve a
high level of chirality transfer from allylic alcohol to allyl-
silane, it is crucial to achieve high stereoselectivity and/or
stereospecificity in the IBS as well as in the elimination
step.
We herein describe in detail the IBS-based protocol for
the synthesis of stereodefined allylsilanes with special em-
phasis on those with high enantiopurity.[21]
À
dimers clearly indicates that complete cis addition of the Si
Si bond across the C=C bond takes place during the IBS.
The eight-membered cyclic dioxadisilacyclooctanes were
subjected to Peterson-type elimination using nucleophiles.
Treatment of 4a with a molar equivalent of tBuOK in THF
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M. Suginome et al.
Table 1. One-pot synthesis of sec-allylsilanes from disilanyl ethers of pri-
mary allylic alcohols.
Entry
Disilanyl ether
R
SiR’2R’’
1 (yield [%])[a]
1
2
(E)-3a
(E)-3b
(E)-3c
(Z)-3a
n-Hex
c-Hex
Ph
SiMe2Ph
SiMe2Ph
SiEt3
1a (90)
1b (77)
1c (58)
1a (68)
3
4[b]
n-Hex
SiMe2Ph
[a] Yields of isolated products. [b] PhLi was used for the second step in-
stead of nBuLi.
Figure 1. Crystal structure of trans-4a’. Selected bond lengths [ꢁ] and
À
À
angles [8]: O(2) Si(3) 1.647(3), Si(3) C(4) 1.896(4); C(1)-O(2)-Si(3)
124.7(3), O(2)-Si(3)-C(4) 110.4(2), Si(3)-C(4)-C(1)’ 111.6(3).
substituents (Table 1, entries 2 and 3). Note that disilanyl
allyl ether (Z)-3a, which has a cis-C=C bond, similarly un-
derwent IBS and subsequent elimination to give 1a in mod-
erate yield when subjected to the one-pot procedure
(Table 1, entry 4).
We then examined reactions of sec-allylic alcohols, which
led to the synthesis of allylsilanes with an internal C=C
bond. Our primary concern was diastereofacial selectivity of
the IBS reaction. Disilanyl ether (E)-3d, prepared from rac-
emic (E)-3-decen-2-ol, underwent IBS in the presence of
[Pd(acac)2]/tOcNC under reflux in hexane (ca. 708C) to give
eight-membered ring dimers 4d in quantitative yield as a
mixture of two diastereomers (Scheme 3). This result indi-
at 508C afforded allylsilane 1a in moderate yield [Eq. (1)].
Several attempts at using other nucleophiles such as MeLi
and nBuLi failed to give the desired allylsilane 1a.
In the course of those examinations, we found that ther-
mal ring contraction of the eight-membered ring took place
at 1408C in xylene. The disproportionation reaction cleanly
afforded six-membered disiladioxane 6a and allylsilane 1a
[Eq. (2)]. Furthermore, 6a underwent Peterson-type elimi-
nation with nBuLi/tBuOK to give allylsilane 1a [Eq. (3)].
Scheme 3. IBS of disilanyl ethers derived from racemic sec-allylic alco-
hols.
cated that IBS of (E)-3d proceeded with high stereoselectiv-
ity to produce diastereomerically pure trans-oxasiletane 5d
as a racemate, which then dimerized to give chiral-4d and
achiral-4d in a ratio of 2:3.[23]
The dimers 4d underwent thermal disproportionation
more readily than the corresponding dimer 4a obtained
from the primary allylic alcohol. Thus, heating 4d in reflux-
ing toluene afforded disiladioxane 6d and allylsilane (E)-1d
quantitatively without formation of any stereoisomers of
The combined yield of the allylsilane was greatly im-
proved by carrying out the two steps in one pot. Thus, reac-
tion of (E)-3a in the presence of [Pd(acac)2]/tOcNC under
reflux in xylenes provided a 1:1 mixture of 1a and 6a, which
was then treated with nBuLi/tBuOK after replacement of
the solvent with THF to give allylsilane 1a in 90% yield
(Table 1, entry 1). This one-pot procedure was successfully
applied to the synthesis of allylsilanes bearing other allylic
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Highly Enantioenriched (E)-Allylsilanes
FULL PAPER
each product [Eq. (4)]. This finding may unambiguously
prove that the thermal extrusion of the allylsilane proceeds
with almost complete stereospecificity for the syn-elimina-
tion. Treatment of the six-membered cyclic compound 6d
with nBuLi afforded (E)-1d in 95% yield by Peterson elimi-
nation.
carbon centers in an oxasiletane in a highly diastereoselec-
tive fashion. Since one stereogenic center newly created at
the a-silylalkyl substituent on the four-membered ring is re-
tained in chiral allylsilanes after the elimination steps, highly
stereoselective 1,3-transfer of chirality from the starting al-
lylic alcohols to the produced allylsilanes was expected. We
attempted to use highly enantioenriched allylic alcohols as
starting materials, which were readily available by asymmet-
ric synthesis.
Initially, we examined the IBS reactions of highly enan-
tioenriched disilanyl ethers (R)-(E)-3d (99.7% ee) and (R)-
(Z)-3d (96% ee) to confirm the stereochemical course in
detail. IBS of (R)-(E)-3d in refluxing hexane afforded an
eight-membered ring dimer in high yield [Eq. (7)]. We could
detect only one isomer assignable to enantiopure chiral-4d
in the reaction mixture. Likewise, IBS of (R)-(Z)-3d provid-
ed chiral-ent-4d in high yield, essentially as a single isomer
under the same reaction conditions [Eq. (8)]. The structures
of both eight-membered ring products, chiral-4d and chiral-
ent-4d, were confirmed by single-crystal X-ray analyses
(Figures 2 and 3). It is interesting to note that the transannu-
The one-pot procedure was found to be applicable to the
synthesis of allylsilanes such as 1d with an internal C=C
bond. Thus, IBS of (E)-3d under reflux in toluene, followed
by treatment of the crude reaction mixture with nBuLi in
THF, gave allylsilane (E)-1d in 93% yield [Eq. (5)]. No cis-
allylsilane was detected in the reaction mixture, suggesting
high stereoselectivity of the bis-silylation step as well as
complete stereospecificity of the elimination steps.
À
lar Si O distances (2.86–2.96 ꢁ) in chiral-4d and chiral-ent-
4d are significantly shorter than the sum of the van der
Waals radii (ca. 3.4 ꢁ), which is responsible for the facile
thermal ring contraction. The requirement of a relatively
Reaction of the disilanyl ether 3l of the chiral tert-allylic
alcohol was also examined. IBS under toluene reflux fol-
lowed by treatment with tBuOK afforded allylsilane (E)-1l
and (Z)-1l in 85% yield as a 92:8 mixture of the two stereo-
isomers [Eq. (6)].
Synthesis of enantioenriched (E)-allylsilanes with 1,3-chirali-
ty transfer: It has thus far been established that the IBS of a
chiral allylic alcohol creates two new silyl-bound stereogenic
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M. Suginome et al.
silane was determined to be S, suggesting highly enantioen-
riched allylsilane was produced with nearly complete 1,3-
chirality transfer through the expected stereochemical
course.
Figure 2. Crystal structure of chiral-4d. Selected bond lengths [ꢁ] and
À
À
À
angles [8]: Si(1) O(2) 1.645(4), Si(1) C(8) 1.911(5), Si(5) O(6) 1.655(4),
À
Si(5) C(4) 1.889(5); Si(1)-O(2)-C(3) 134.9(4), O(2)-Si(1)-C(8) 109.1(2),
Si(5)-O(6)-C(7) 126.6(4), C(4)-Si(5)-O(6) 106.5(3).
Application of the one-pot method to the synthesis of the
highly enantioenriched allylsilane was also successful. Thus,
IBS of (R)-(E)-3d in refluxing toluene followed by treat-
ment with nBuLi afforded (S)-1d of 99.1% ee in 90% yield
(Table 2, entry 1). In good agreement with the stereoselec-
tive formation of ent-5d in IBS in refluxing hexane, (R)-
(Z)-3d afforded (R)-1d in good yield with nearly complete
1,3-chirality transfer (Table 2, entry 2). Results of the syn-
thesis of a series of highly enantioenriched allylsilanes by
the one-pot procedure are summarized in Table 2. Allylsi-
lanes with a variety of silyl groups and allyl groups were suc-
cessfully prepared with >99% conservation of enantiopuri-
ty of the starting allylic alcohols. Moreover, except for the
TIPS derivative (Table 2, entry 6), yields were generally
high. These results demonstrate the synthetic usefulness of
the new protocol for the preparation of highly enantioen-
riched allylsilanes.
Figure 3. Crystal structure of chiral-ent-4d. Selected bond lengths [ꢁ]
À
À
À
and angles [8]: Si(1) O(2) 1.647(4), Si(1) C(8) 1.920(6), Si(5) O(6)
À
1.636(5), Si(5) C(4) 1.888(6), Si(1)-O(2)-C(3) 126.8(3), O(2)-Si(1)-C(8)
106.0(3), Si(5)-O(6)-C(7) 133.8(4), O(6)-Si(5)-C(4) 109.5(3).
Stereochemical course: The highly stereoselective 1,3-trans-
fer of chirality from the allylic alcohol to the allylsilane is
primarily attributed to the highly stereoselective IBS, which
exclusively produces trans-oxasiletane 5. As we previously
proposed, the bis-silylation may proceed through a bis-
(silyl)palladium(ii) intermediate, which is formed by oxida-
high temperature in the thermal ring contraction of 4a,
which is derived from the primary allylic alcohol, may be at-
tributed to the slightly deviated conformation of the eight-
À
membered ring, in which the longer transannular Si O dis-
À
tance (3.41 ꢁ) was observed in the X-ray crystal structure
(Figure 1). The two compounds, chiral-4d and chiral-ent-4d,
have the same stereochemistry with respect to the substitu-
ents in the eight-membered ring, but differ in the configura-
tion at the a-silylalkyl substituents. This result undoubtedly
establishes the extremely high diastereofacial selectivity as
tive addition of the Si Si bond to the palladium(0) complex
ligated by tert-alkyl isonitrile. It is presumed that the bis-
(silyl)palladium(ii) intermediate formed from the disilanyl
ether of the allylic alcohol is able to adopt two conforma-
tions in the cyclization step, depicted as A and B in
Scheme 4, in which the R1 group at the stereogenic center is
at the pseudo equatorial or axial position, respectively. The
IBS reaction may exclusively proceed via the intermediate
A, since the cyclization via intermediate B may be unfavora-
ble because of steric repulsion between the R1 group and
the phenyl group on the silicon atom. Accordingly, the trans
four-membered ring product trans-5 is obtained with high
stereoselectivity.
À
well as perfect stereospecificity for cis-addition of the Si Si
bond across the C=C bond, which leads to the formation of
trans-oxasiletanes 5d and ent-5d from the starting (E)- and
(Z)-alkenes, respectively.
Upon heating in refluxing toluene, (R)-(E)-3d afforded
disiladioxane 6d and allylsilane (S)-1d in high total yield
[Eq. (9)]. The six-membered cyclic 6d, which was separated
from (S)-1d and isolated, was subjected to treatment with
nBuLi, affording (S)-1d in high yield. Enantiomeric excesses
of both samples of the allylsilane were determined to be
96.1 and 99.1% ee.[24] The absolute configuration of the allyl-
Subsequent dimerization may be driven by an intermolec-
ular Lewis acid–base interaction between the ether oxygen
atom and the silicon atom in the four-membered ring, of
which the respective basicity and acidity may be enhanced
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Highly Enantioenriched (E)-Allylsilanes
FULL PAPER
Table 2. One-pot synthesis of enantioenriched (E)-allylsilanes[a]
.
the present study showed that
the thermal extrusion of allyl-
silane from dioxadisilacyclo-
octane 4 also proceeded with
highly stereospecific syn-elimi-
nation.
Entry
3 (ee [%])[b]
R’’R’2Si
R1
Rt
Rc
H
1 (yield [%])[c]
ee [%][d]
ce [%][e]
Enrichment of the enantiomeric
excesses through dimerization:
It is commonly accepted that
the ee of the product does not
exceed the ee of the starting
material in asymmetric synthe-
ses involving chirality transfer.
Although crystalline products
with incomplete enantiopurity
may be purified by preferential
recrystallization to produce
enantiopure materials, there is
no way to enrich the enantio-
purity of nonsolid materials.
Indeed, this was true for our
1
(R)-(E)-3d (99.7)
(R)-(Z)-3d (96.0)
(R)-(E)-3e (99.6)
(R)-(E)-3 f (99.6)
(R)-(E)-3g (99.6)
(R)-(E)-3h (99.6)
(S)-(E)-3i (>99.0)
(S)-(E)-3j (99.8)
(R)-(E)-3k (98.2)
PhMe2Si
PhMe2Si
Me3Si
tBuMe2Si
Et3Si
Me
Me
Me
Me
Me
Me
Ph
c-Hex
Me
n-Hex
H
(S)-1d (90)
(R)-1d (84)
(S)-1e (81)
(S)-1 f (82)
(S)-1g (94)
(S)-1h (62)
(S)-1i (99)
(S)-1j (96)
(R)-1k (92)
99.1
95.4
99.1
99.4
99.2
98.8
98.7
99.0
98.1
99.4
99.4
99.4
99.8
99.6
98.8
>98.7
99.3
2[f]
3
n-Hex
H
n-Hex
n-Hex
n-Hex
n-Hex
n-Hex
n-Hex
Ph
4
5
6
7
8
9
H
H
H
H
H
H
iPr3Si
PhMe2Si
PhMe2Si
PhMe2Si
99.9
[a] Unless otherwise noted, the bis-silylations were carried out in the presence of [Pd(acac)2] (2 mol%) and
1,1,3,3-tetramethylbutyl isocyanide (8 mol%) under reflux in toluene. After replacement of the solvent with
THF, nBuLi in hexane was added at 08C. [b] Enantiomeric excesses of the corresponding allylic alcohols de-
termined by HPLC. [c] Yields of isolated products. [d] Enantiomeric excesses determined by hydroboration
method (see main text). [e] Conservation of enantiopurity (ee of 1/ee of 3). [f] PhLi was used instead of nBuLi.
protocol for the one-pot synthesis of enantioenriched allylsi-
lanes. In principle, however, it would still be possible to
enrich enantiopurity through the chirality transfer process, if
it involves the formation of diastereomeric intermediates
that are isolable and purifiable.[26] The present reaction se-
quence involves the formation of isolable diastereomeric in-
termediates, the chiral and achiral eight-membered cyclic
dimers 4. Therefore, isolation of the chiral isomer in a pure
state may lead to the production of allylsilanes with higher
ee values than those of the allyl alcohols used as starting ma-
terials. Indeed, the degree of enrichment of enantiopurity
can be roughly estimated by a simple calculation based on
the assumption that the dimerization of trans-oxasiletane 5
takes place randomly.[27] Using enantioenriched allyl alcohol
containing x% S enantiomer (and (100Àx)% R enantio-
mer), IBS and subsequent dimerization provides two enan-
tiomers, SS-chiral-4 and RR-chiral-4, along with RS-achiral-4
(Scheme 5). The ratio of SS- to RR- and RS-4 is calculated
to be x2:(100Àx)2:2x(100Àx). Removal of the achiral dimer
RS-4 by recrystallization leaves the chiral dimers, which con-
tain the SS- and RR-enantiomers in a ratio of at least x2:-
(100Àx)2. The ratio is maintained in the enantioenriched al-
lylsilanes produced by the subsequent elimination reactions.
For instance, allylsilanes of 99.4%ee and 97.6%ee can be
obtained from enantioenriched allyl alcohols of 90.0%ee (x
= 95.0) and 80.0%ee (x = 90.0), respectively, according to
the calculation.
Scheme 4. Stereochemical course of the sequence from (E)-3 to 1.
Disilanyl ether (S)-(E)-3d was prepared from the corre-
sponding allylic alcohol with 79.2%ee and subjected to IBS
under reflux in hexane. A 76:24 mixture of chiral-4d (SS
and RR) and achiral-4d (RS) was obtained by silica gel
chromatography. Fortunately, chiral-4d could be isolated by
recrystallization from Et2O/EtOH. The pure chiral-4d was
then heated in refluxing toluene and treated with nBuLi as
described above. Consequently, allylsilane (R)-1d of
by the ring strain. This dimerization mechanism involving
À
Si O bond cleavage may be supported by the fact that no
racemization took place during synthesis of the allylsilanes.
Subsequent elimination reactions, such as ring contraction
of 4 and nucleophile-induced reaction of 6, proceed in a per-
fect syn fashion. Although the mechanism for the latter
elimination has been well documented in the literature,[25]
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M. Suginome et al.
Scheme 5. Synthesis of enantiopure allylsilane (R)-1d from (S)-(E)-3d of 79.2%ee by enrichment of enantiopurity (Si = SiMe2Ph).
99.4%ee was isolated in 56% overall yield from (S)-(E)-3d
of 79.2%ee.
This result demonstrates that allylic alcohols with only
moderate ee values are sufficient for the production of
almost enantiopure allylsilanes. The minor enantiomer of
the starting disilanyl ether 3d is accumulated predominantly
in achiral-4d, resulting in the formation of chiral-4d with
nearly perfect enantiomeric excess. Though the observed ee
(99.4%) for the allylsilane prepared from (S)-(E)-3d of
79.2%ee was unexpectedly higher than the calculated value
(97.3%ee), this may be due to preferential crystallization of
the major enantiomer (SS-chiral-4d) during the recrystalli-
zation. These enrichment processes may be especially valua-
ble in cases where optically pure allylic alcohols are not
easily accessible.
Scheme 6. Transformations of enantioenriched allylsilanes for determina-
tion of enantiomeric excesses. Reagents and conditions: a) H2, Pd/C,
AcOEt; b) TsNHNH2, Et3N, dioxane, reflux; c) CF3CO2H, 508C, then
KHF2, KHCO3, MeOH, THF, 508C; d) mCPBA, CH2Cl2, À78~08C, then
AcOH, MeOH; e) 9-BBN, THF, 508C, then H2O2, NaOH aq, 508C.
Determination of enantiomeric excesses: Since chiral HPLC
analysis provides the most reliable determination of enantio-
meric excesses of highly enantioenriched compounds, opti-
cally active allylsilanes obtained by our protocol were sub-
jected to some stereospecific transformations for the pur-
pose of making them amenable to chiral HPLC analysis
(Scheme 6). Allylsilane (S)-1d, which was prepared from
(R)-(E)-3d of 99.7–99.9%ee, was hydrogenated in the pres-
Table 3. Enantiomeric excesses of alcohols 2, 7, and 8 derived from enan-
tioenriched allylsilane (S)-1d by transformations outlined in Scheme 6.
Entry ee of 3d[a] [%] Path[b] Produced Yield[%] ee[%] ce[c] [%]
alcohol
À
ence of Pd/C followed by oxidation of the Si C bond under
the Tamao condition to give 4-decanol (7d).[28] To our sur-
prise, a chiral HPLC analysis of the corresponding 3,5-dini-
trophenylcarbamate showed only 30%ee (Table 3, entry 1).
We suppose that the decrease in ee did not arise from ineffi-
cient 1,3-chirality transfer, but from racemization during the
transformation prior to the analysis. Indeed, hydrogenation
1
2
3
4
99.7
99.9
99.9
99.7
a, c
b, c
d
7d
7d
2d
8d
52
49
50
85
30.4
97.3
96.8
99.1
30.5
97.4
96.9
99.4
e
[a] Enantiomeric excess of (R)-(E)-3d employed for the synthesis of (S)-
1d. [b] The alphabetical designations correspond to those in Scheme 6.
[c] Conservation of enantiopurity.
2960
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Chem. Eur. J. 2005, 11, 2954 – 2965

Highly Enantioenriched (E)-Allylsilanes
FULL PAPER
of the C=C bond with diimide instead of Pd-catalyzed hy-
drogenation led to the formation of 7d with 97.3%ee
(Table 3, entry 2). Reaction of (S)-1d with mCPBA was also
attempted. Although slight racemization may have taken
place during the transformation, allylic alcohol (S)-(E)-2d
(96.8%ee) was obtained in moderate yield (entry 3). The
absolute configuration of (S)-1d was unambiguously estab-
lished by the chiral HPLC analysis of allyl alcohol (E)-2d
obtained by the mCPBA oxidation. Indeed, the analysis of
(E)-2d showed the absolute configuration of (S), which was
opposite to that for the starting (R)-(E)-2d, indicating that
the absolute configuration of (S) of the allylsilane 1d is in
accord with the reported stereochemical course for the
mCPBA reaction of allylsilanes.[29] The highest ee, which
may inevitably be the most accurate value, was attained by
regio- and stereoselective hydroboration of (S)-1d with 9-
BBN,[30] which gave anti-4-silyldecan-2-ol 8d in good yield
on treatment with basic hydrogen peroxide (Table 3,
entry 4). The ee (99.1%ee) measured by the HPLC analysis
showed that the enantiopurity of the starting allylic alcohol
was almost completely conserved in the allylic silane ob-
tained.
The method for ee determination was generally applied to
all enantioenriched allylsilanes 1d–k described thus far. The
hydroboration method generally showed higher, or more ac-
curate, enantiopurity than the other methods examined. The
hydroboration-oxidation sequence is advantageous over
other methods in that essentially no racemization takes
place during the transformation and a wide range of allylsi-
lanes, including those with bulky silyl groups such as tert-bu-
tyldimethylsilyl (TBDMS) and triisopropyl silyl (TIPS), can
be evaluated. The transformation using Tamao oxidation or
mCPBA oxidation was not applicable for the ee determina-
tion of allylsilanes with bulky trialkylsilyl groups such as 1 f
and 1h.
synthetic utility of the method has been demonstrated by
the synthesis of highly enantioenriched, functionalized allyl-
silanes including those supported on a polymer resin.[31,32]
Experimental Section
General: 1H and 13C NMR spectra were recorded on a Varian Gemini-
2000 (7.0 T magnet) or a JEOL JNM 400 (11.7 T magnet) spectrometer
1
at ambient temperature. H NMR data are reported as follows: chemical
shift in ppm downfield from tetramethylsilane (d scale), multiplicity (s =
singlet, d = doublet, t = triplet, q = quartet, m = multiplet), coupling
constant (Hz), and integration. 13C NMR chemical shifts are reported in
ppm downfield from tetramethylsilane (d scale). All 13C NMR spectra
were obtained with complete proton decoupling. IR spectra were ob-
tained on a Hitachi 270–30 spectrometer. High-resolution mass spectra
were recorded on a JEOL JMS HX-110 spectrometer. Optical rotations
were measured on a Perkin–Elmer 243 polarimeter.
Solvents were distilled from the indicated drying agents: benzene
(LiAlH4), toluene (LiAlH4), xylenes (CaH2), hexanes (Na), THF (Na/
benzophenone). [Pd(acac)2] (Mitsuwa), nBuLi (Mitsuwa), tBuOK (Naca-
lai), mCPBA (80%, Nacalai), and 9-BBN (Aldrich) were purchased from
À
commercial sources and used as received. Chlorodisilanes (ClPh2Si
SiR’2R’’) were prepared by the reactions of (Et2N)Ph2SiLi with ClSiR’2R’’
in THF, followed by treatment with AcCl in the same reaction vessel.[22]
(E)-Allylic alcohols were prepared by the reactions of the corresponding
propargylic alcohols with sodium bis(methoxyethoxy)aluminum hydride
(Red-Al) in toluene. (Z)-Allylic alcohols were prepared from the corre-
sponding propargylic alcohols by hydromagnesation using iBuMgCl in
the presence of [Cp2TiCl2] followed by hydrolysis.[33] Highly enantioen-
riched allylic alcohols were obtained with Sharpless kinetic resolution
using [Ti(OiPr)4] with l-(+)-diisopropyl tartrate at À208C.[34] Enantio-
meric excesses of the allylic alcohols were determined by chiral HPLC
analysis. Disilanyl ethers of the allylic alcohols were prepared from the
corresponding chlorodisilanes and the alcohols in the presence of Et3N
(1.5 equiv) and 4-(dimethylamino)pyridine (0.02 equiv) in THF at room
temperature.
IBS of (E)-3a in refluxing benzene (Scheme 2): A mixture of [Pd(acac)2]
(1.3 mg, 4.2ꢂ10À3 mmol) and 1,1,3,3-tetramethylbutyl isocyanide (12ꢂ
10À3 mL, 66ꢂ10À3 mmol) was stirred for 10 min under nitrogen at room
temperature. Benzene (0.4 mL) and (E)-3a (101 mg, 0.22 mmol) were
added to the catalyst mixture. The mixture was stirred for 2 h under
reflux. Evaporation of the solvent followed by silica gel column chroma-
tography (hexane only to hexane/ether = 50:1) afforded a mixture of
cis- and trans-4a (97 mg, 96%). The major isomer, trans-4a, was isolated
in diastereomerically pure form by washing the mixture with EtOAc.
Conclusion
We have established a new synthetic route to highly enan-
tioenriched allylsilanes from allylic alcohols by stereoselec-
tive IBS followed by stereospecific elimination reactions.
For the conversion of allylic alcohols to allylsilanes starting
with the corresponding disilanyl ethers, which are easily pre-
pared from allylic alcohols and disilanyl chloride, the follow-
ing simple operations are carried out in one flask: 1) IBS in
refluxing toluene in the presence of the palladium–isonitrile
catalyst and 2) treatment of the reaction mixture with
nBuLi (or PhLi). Highly enantioenriched (E)-allylsilanes
were thus obtained with nearly complete stereoconservation
of the enantiomeric excess of the starting allylic alcohols.
Moreover, even from allylic alcohols with about 80%ee,
enantioenriched allylsilanes with higher than 99%ee are
available through isolation and recrystallization of the eight-
membered dimeric intermediates. The present method will
open up new possibilities for the application of enantioen-
riched allylsilanes in stereoselective organic synthesis. The
1
trans-4a: H NMR (CDCl3): d = 0.26 (s, 6H), 0.33 (s, 6H), 0.55–1.11 (m,
22H), 0.78 (t, J = 7.2 Hz, 6H), 2.23–2.31 (m, 2H), 3.70–3.82 (m, 4H),
7.16–7.49 ppm (m, 30H); 13C NMR (CDCl3): d = À2.8, À2.4, 13.9, 22.5,
23.2, 27.0, 28.0, 29.5, 30.7, 31.5, 63.2, 127.3, 127.8, 128.8, 129.3, 129.7,
134.0, 134.8, 135.0, 135.8, 136.0, 139.7 ppm. cis-4a: 1H NMR (CDCl3): d
= 0.01 (s, 6H), 0.07 (s, 6H), 0.55–1.38 (m, 22H), 0.75 (t, J = 7.2 Hz,
6H), 1.91–1.98 (m, 2H), 3.90 (dd, J = 6.3, 10.8 Hz, 2H), 4.05 (t, J =
10.8 Hz, 2H), 7.17–7.69 ppm (m, 30H). A mixture of the cis and trans iso-
mers isolated by silica gel column chromatography was subjected to ele-
mental analysis; elemental analysis calcd (%) for C58H76O2Si4: C 75.92, H
8.35; found: C 75.76, H 8.33.
Preparation of trans-4a’ (for an X-ray analysis): According to the same
procedure as that for IBS of (E)-3a to make 4a, the eight-membered
cyclic 4a’ (73% in total, a 7:3 mixture of two stereoisomers) was pre-
pared from (E)-3a’. From the stereoisomeric mixture, trans-4a’ was iso-
1
lated by recrystallization (EtOH/Et2O). trans-4a’: H NMR (CDCl3): d =
0.28 (s, 6H), 0.33 (t, J = 7.4 Hz, 6H), 0.34 (s, 6H), 0.75–1.18 (m, 6H),
2.28 (dd, J = 10.3, 5.2 Hz, 2H), 3.67–3.87 (m, 4H), 7.16–7.58 ppm (m,
30H); 13C NMR (CDCl3): d = À2.9, À2.2, 15.1, 20.7, 25.0, 27.0, 63.0,
127.3, 127.7, 128.8, 129.2, 129.6, 134.0, 134.7, 134.9, 135.7, 135.9,
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M. Suginome et al.
139.5 ppm; elemental analysis calcd (%) for C50H60O2Si4: C 74.57, H 7.51;
found C 74.31, H 7.65.
9.6 Hz, 2H; achiral-4d), 4.11 (dq, J = 9.6, 6.0 Hz, 2H; achiral-4d), 4.54
(dq, J = 11.1, 6.3 Hz, 2H; chiral-4d), 6.88–6.96 (m, 4H; chiral-4d), 7.07–
7.59 (m, 18H; chiral-4d and 26H; achiral-4d), 7.65–7.73 (m, 4H; achiral-
4d), 7.78–7.86 (m, 4H; chiral-4d), 7.92–7.99 ppm (m, 4H; chiral-4d); 13C
NMR (CDCl3): d = À4.2, À2.9, À1.7, À1.3, 14.0, 22.0, 22.5, 23.0, 25.6,
26.2, 27.9, 28.2, 29.4, 29.6, 30.2, 30.4, 31.3, 31.6, 33.7, 36.7, 69.6, 71.3,
127.2, 127.3, 127.46, 127.52, 127.7, 128.2, 128.4, 129.0, 129.4, 129.5, 129.7,
133.7, 133.9, 135.4, 136.0, 136.5, 137.4, 137.9, 140.6, 140.8 ppm; elemental
analysis calcd (%) for C60H80O2Si4: C 76.21, H 8.53; found: C 75.96, H
8.70. See below for spectral data for diastereomerically pure chiral-4d.
Reaction of 4a with tBuOK [Eq. (1)]: Compound 4a (50 mg,
0.055 mmol) was added to a solution of tBuOK (25 mg, 0.22 mmol) in
THF (0.5 mL) at room temperature. The mixture was heated at 508C for
6 h. The reaction mixture was cooled and aqueous NH4Cl (saturated) was
added. Extractive workup followed by silica gel column chromatography
(hexane) afforded 1a (18 mg, 64%).
Thermal ring contraction of 4a [Eq. (2)]: A solution of 4a (a mixture of
the cis and trans isomers, 48 mg, 0.052 mmol) in xylene (0.4 mL) was
heated at 1408C for 3 h. The solvent was stripped off under vacuum. A
1H NMR spectrum of the crude mixture showed clean formation of 6a
and 1a. Silica gel column chromatography afforded 1a (10 mg, 73%) and
6a (29 mg, 84%). 6a: 1H NMR (CDCl3): d = 0.38 (s, 3H), 0.41 (s, 3H),
0.53–1.40 (m, 14H), 2.24 (t, J = 7.2 Hz, 1H), 4.32 (d, J = 7.2 Hz, 2H),
7.21–7.92 ppm (m, 25H); 13C NMR (CDCl3): d = À2.7, À1.7, 14.0, 22.5,
24.5, 29.1, 29.5, 29.8, 30.9, 31.4, 64.6, 127.6, 127.8, 127.9, 128.0, 128.9,
129.9, 130.2, 130.5, 133.4, 133.8, 134.4, 134.5, 134.57, 134.61, 134.9, 135.5,
139.3 ppm; elemental analysis calcd (%) for C41H48O2Si3: C 74.94, H
7.36; found: C 74.71, H 7.34.
Thermal ring contraction of 4d and subsequent Peterson elimination of
6d [Eq. (4)]: Compound 4d (100 mg, 1.06ꢂ10À1 mmol) in toluene
(0.4 mL) was heated under reflux for 1 h. The solvent was stripped off
under vacuum, and the residual oil was dissolved in THF (0.5 mL). The
reaction mixture was cooled (08C), nBuLi (212ꢂ10À3 mL, 1.50m in
hexane, 3.18ꢂ10À1 mmol) was added, and the mixture was stirred for
20 min. Addition of saturated NH4Cl (aq.) to the mixture at 08C was fol-
lowed by extraction with Et2O and subsequent drying over MgSO4. Silica
gel column chromatography (hexane) gave (E)-1d (56 mg, 95%).
IBS of enantioenriched (R)-(E)-3d giving chiral-4d [Eq. (7)]: Hexane
(0.4 mL) and (R)-(E)-3d (99.7%ee, 99 mg, 2.1ꢂ10À1 mmol) were added
to a catalyst mixture prepared from [Pd(acac)2] (1.3 mg, 4.2ꢂ10À3 mmol)
and 1,1,3,3-tetramethylbutyl isocyanide (2.0m in toluene, 8.5ꢂ10À3 mL,
17ꢂ10À3 mmol). The mixture was stirred for 1 h under reflux. After strip-
ping the volatile materials off under vacuum, the residue was subjected
Reaction of 6a with nBuLi/tBuOK [Eq. (3)]: nBuLi (1.5m in hexane,
0.11 mL, 0.17 mmol) was added to
a solution of 6a (51 mg, 7.8ꢂ
10À2 mmol) in THF (0.5 mL) at 08C. The mixture was stirred as it
warmed from 08C to room temperature over 1.5 h. tBuOK (18 mg,
0.16 mmol) and THF (0.2 mL) at room temperature were added to the
mixture, which was stirred at 508C for 15 h. Extractive workup followed
by silica gel column chromatography (hexane) afforded 1a (14 mg,
68%).
to silica gel column chromatography (hexane/ether
= 100:1) to give
chiral-4d (95 mg, 96%). 1H NMR (CDCl3): d = À0.30 (s, 6H), À0.04 (s,
6H), 0.46–1.36 (m, 34H), 1.76 (d, J = 10.8 Hz, 2H), 4.55 (dq, J = 10.8,
6.0 Hz, 2H), 6.89–6.96 (m, 4H), 7.07–7.28 (m, 6H), 7.30–7.50 (m, 12H),
General procedure for one-pot synthesis of allylsilanes 1a–c (Table 1): A
mixture of [Pd(acac)2] (2.7 mg, 8.9ꢂ10À3 mmol) and 1,1,3,3-tetramethyl-
butyl isocyanide (2.3ꢂ10À2 mL, 0.13 mmol) was stirred for 10 min under
nitrogen at room temperature. Xylene (0.7 mL) and disilanyl ether 3a–c
(0.45 mmol) were added to the catalyst mixture. The mixture was stirred
for 10 h under reflux. After stripping the volatile materials off under
vacuum, THF (0.7 mL) was added to the residue. The solution was
cooled to 08C and nBuLi (0.30 mL, 1.50m in hexane, 0.45 mmol) was
added; the mixture was stirred for 1.5 h at room temperature. tBuOK
(51 mg, 0.45 mmol) at room temperature was added to the mixture,
which was then stirred at 508C for 12 h. Addition of aqueous NH4Cl (sa-
turated) to the mixture and extractive workup with ether followed by
column chromatography on silica gel (hexane) afforded (E)-allylsilanes
1a–c.
7.79–7.86 (m, 4H), 7.93–8.01 ppm (m, 4H); 13C NMR (CDCl3): d
=
À4.2, À1.7, 14.0, 22.0, 22.5, 25.5, 27.9, 29.4, 30.2, 31.3, 36.7, 71.3, 127.3,
127.5, 128.1, 129.4, 129.5, 133.6, 136.0, 136.5, 137.3, 137.8, 140.8 ppm; ele-
mental analysis calcd (%) for C60H80O2Si4: C 76.21, H 8.53; found: C
76.00, H 8.77.
IBS of enantioenriched (R)-(Z)-3d giving chiral-ent-4d [Eq. (8)]: Ac-
cording to the same procedure as that for the preparation of chiral-4d,
chiral-ent-4d (92 mg, 92%; eluent for column chromatography: hexane/
ether = 80:1) was synthesized from (R)-(Z)-3d (96.0%ee, 100 mg, 2.1ꢂ
10À1 mmol). 1H NMR (CDCl3): d = À0.23 (s, 6H), À0.20 (s, 6H), 0.46–
1.34 (m, 34H), 1.89 (d, J = 5.4 Hz, 2H), 4.38–4.64 (m, 2H), 6.93 (d, J =
6.6 Hz, 4H), 7.07–7.22 (m, 6H), 7.38–7.56 (m, 12H), 7.86 (d, J = 6.9 Hz,
4H), 7.96–8.03 ppm (m, 4H); 13C NMR (CDCl3): d = À4.3, À1.3, 13.9,
22.5, 24.1, 25.5, 28.8, 29.6, 31.4, 31.6, 39.1, 74.6, 127.3, 127.4, 127.5, 128.2,
129.4, 129.5, 133.6, 136.1, 137.1, 137.5, 138.6, 140.7 ppm; elemental analy-
sis calcd (%) for C60H80O2Si4: C 76.21, H 8.53; found: C 75.92, H 8.65.
3-(Dimethylphenylsilyl)-1-nonene (1a): 1H NMR (CDCl3): d = 0.26 (s,
3H), 0.27 (s, 3H), 0.85 (t, J = 6.6 Hz, 3H), 1.04–1.50 (m, 10H), 1.67–1.81
(m, 1H), 4.75–4.92 (m, 2H), 5.58 (dt, J
= 16.9, 9.8 Hz, 1H), 7.31–
7.57 ppm (m, 5H); 13C NMR (CDCl3): d = À5.2, À4.4, 14.1, 22.7, 28.4,
29.1, 29.2, 31.8, 34.4, 112.4, 127.6, 128.9, 134.0, 137.9, 139.9 ppm; elemen-
tal analysis calcd (%) for C17H28Si: C 78.38, H 10.83; found: C 78.49, H
11.10.
Step-by-step synthesis of (S)-1d from (R)-(E)-3d [Eq. (9)]: Toluene
(0.4 mL) and disilanyl ether (R)-(E)-3d (99.7%ee, 103 mg, 0.22 mmol)
were added to the catalyst mixture of [Pd(acac)2] (1.3 mg, 4.2ꢂ
10À3 mmol) and 1,1,3,3-tetramethylbutyl isocyanide (8.4ꢂ10À3 mL, 1.7ꢂ
10À2 mmol). The mixture was stirred for 3 h under reflux. After stripping
the volatile materials off under vacuum, the residue was subjected to a
short column of Florisil (hexane/ether = 4:1) to give a mixture of 1d
and 6d. These were separated by HPLC (hexane/EtOAc = 10:1) to give
1d (27 mg, 49%) and 6d (62 mg, 46%). Enantiomeric excess of 1d was
determined to be 96.1% ee (absolute configuration of S) after transfor-
mation to 7d by diimide reduction (see below). Compound 6d was dis-
solved in THF (0.5 mL) and treated with nBuLi (1.52m in hexane,
0.20 mL, 0.30 mmol) at 08C for 15 min. Extractive workup followed by
column chromatography on silica gel afforded 1d (24 mg, 94% based on
6d). The ee was determined to be 99.1% (absolute configuration of S)
according to the same determination procedure as above.
3-Cyclohexyl-3-(dimethylphenylsilyl)-1-propene (1b): 1H NMR (CDCl3):
d = 0.28 (s, 3H), 0.30 (s, 3H), 0.91–1.29 (m, 5H), 1.37–1.77 (m, 7H),
4.79 (dd, J = 16.7, 2.2 Hz, 1H), 4.90 (dd, J = 10.3, 2.2 Hz, 1H), 5.71 (dt,
J = 16.7, 10.3 Hz, 1H), 7.30–7.57 ppm (m, 5H); 13C NMR (CDCl3): d =
À3.5, À2.8, 26.2, 26.7, 31.3, 34.1, 38.4, 42.2, 113.7, 127.5, 128.7, 133.9,
137.8, 139.0 ppm; elemental analysis calcd (%) for C17H26Si: C 79.00, H
10.14; found: C 78.80, H 10.10.
IBS of racemic (E)-3d in refluxing hexanes (Scheme 3): [Pd(acac)2]
(6.9 mg, 2.3ꢂ10À2 mmol) was placed in a Schlenk flask and tetramethyl-
butyl isocyanide (15ꢂ10À3 mL, 8.6ꢂ10À2 mmol) was added. The mixture
was stirred for 10 min at room temperature. Hexane (5.0 mL) and (Æ)-
(E)-3d (501 mg, 1.1 mmol) were added to the dark red mixture at room
temperature and it was stirred under reflux for 1 h. The solvent was strip-
ped off under vacuum and the residue was subjected to silica gel column
chromatography (hexane/ether = 100:1) to give 4d (493 mg, 98%) as a
viscous oil. 4d (a mixture of chiral-4d and achiral-4d): 1H NMR
(CDCl3): d = À0.30 (s, 6H; chiral-4d), À0.04 (s, 6H; chiral-4d), 0.19 (s,
6H; achiral-4d), 0.26 (s, 6H; achiral-4d), 0.30–1.40 (m, 34H; chiral-4d
and 34H; achiral-4d), 1.75 (d, J = 11.1 Hz, 2H; chiral-4d), 2.18 (d, J =
General procedure for the one-pot synthesis of enantioenriched allylsi-
lanes 1d–k (Table 2): Toluene (0.4 mL) and disilanyl ether 3d–k
(0.45 mmol) were added to the catalyst mixture of [Pd(acac)2] (1.3 mg,
4.2ꢂ10À3 mmol) and 1,1,3,3-tetramethylbutyl isocyanide (2.9ꢂ10À3 mL,
1.7ꢂ10À2 mmol). The mixture was stirred for 1 h under reflux. After
stripping the volatile materials off under vacuum, THF (0.5 mL) was
added to the residue. nBuLi (1.37m in hexane, 0.24 mL, 0.33 mmol) or
2962
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2005, 11, 2954 – 2965

Highly Enantioenriched (E)-Allylsilanes
FULL PAPER
PhLi (for the reaction of (Z)-3d (entry 2 in Table 3), 1.0m in cyclohex-
ane, 0.33 mL, 0.33 mmol) was added to the solution cooled at 08C; the
mixture was stirred for 15 min at 08C. Addition of aqueous NH4Cl (satu-
rated) to the mixture and extractive workup with ether followed by
column chromatography on silica gel (hexane) afforded (E)-allylsilanes
1d–k.
ture was stirred for 5 h under reflux. After stripping the volatile materials
off under vacuum, THF (0.5 mL) was added to the residue, followed by
tBuOK (19 mg, 0.17 mmol) at room temperature. The mixture was stirred
at room temperature for 6 h. Addition of aqueous NH4Cl (saturated) to
the mixture and extractive workup with ether followed by column chro-
matography on silica gel (hexane) afforded 1l (51 mg, 85%, E/Z
=
(S)-(E)-4-(Dimethylphenylsilyl)-2-decene ((S)-1d): ee>99.1%; [a]D22
=
92:8). The isomers were separated by HPLC (hexane). (E)-1l: 1H NMR
(CDCl3): d = 0.32 (s, 3H), 0.36 (s, 3H), 0.88 (t, J = 6.6 Hz, 3H), 1.09–
1.69 (10H), 1.86 (d, J = 1.3 Hz, 3H), 2.14 (dt, J = 11.2, 3.0 Hz, 1H),
5.60 (dd, J = 11.2, 1.3 Hz, 1H), 7.18–7.44 (m, 8H), 7.50–7.60 ppm (m,
2H); 13C NMR (CDCl3): d = À5.0, À4.3, 14.1, 16.2, 22.7, 29.1, 29.9, 30.1,
30.2, 31.8, 125.4, 126.0, 127.6, 128.1, 128.9, 130.9, 132.6, 134.0, 138.0,
144.5 ppm; elemental analysis calcd (%) for C24H34Si: C 82.22, H 9.77;
found: C 82.34, H 9.93.
+3.8 (c=2.2, benzene); 1H NMR (CDCl3): d = 0.25 (s, 3H), 0.27 (s,
3H), 0.87 (t, J = 6.4 Hz, 3H), 1.03–1.71 (m, 14H), 5.11–5.32 (m, 2H),
7.32–7.41 (m, 3H), 7.45–7.56 ppm (m, 2H); 13C NMR (CDCl3): d
=
À5.1, À4.2, 14.1, 18.1, 22.7, 29.0, 29.1, 29.3, 31.8, 32.5, 123.0, 127.5, 128.7,
132.0, 134.1, 138.4 ppm; elemental analysis calcd (%) for C18H30Si: C
78.75, H 11.02; found: C 78.68, H 11.00.
(S)-(E)-4-(Trimethylsilyl)-2-decene ((S)-1e): ee>99.0%; [a]D22
= +18.6
(c=2.5, benzene); 1H NMR (CDCl3): d = À0.06 (s, 9H), 0.88 (t, J =
6.4 Hz, 3H), 1.03–1.44 (m, 11H), 1.66 (d, J = 4.7 Hz, 3H), 5.09–5.32 ppm
(m, 2H); 13C NMR (CDCl3): d = À3.1, 14.1, 18.1, 22.7, 29.0, 29.3, 29.4,
31.9, 33.0, 122.2, 132.6 ppm; elemental analysis calcd (%) for C13H28Si: C
73.50, H 13.28; found: C 73.22, H 13.15.
Single-crystal X-ray studies: Single crystals were mounted on glass fibers.
Intensity data collections were carried out with a Mac Science MXC3 dif-
fractometer using graphite-monochromated CuKa (l = 1.54178 ꢁ) radia-
tion at 293 K. Intensity data were collected using w/2q scans and correct-
ed for Lorentz-polarization and for absorption by an analytical function.
Details of crystal and data collection parameters are shown in Table 4.
(S)-(E)-4-(tert-Butyldimethylsilyl)-2-decene ((S)-1 f): ee>99.4%; [a]D22
=
À3.2 (c=2.6, benzene); 1H NMR (CDCl3): d = À0.10 (s, 3H), À0.08 (s,
3H), 0.89 (s, 9H), 0.91 (t, J = 8.0 Hz, 3H), 1.03–1.62 (m, 11H), 1.65 (d,
J = 4.6 Hz, 3H), 5.12–5.31 ppm (m, 2H); 13C NMR (CDCl3): d = À7.1,
À7.0, 14.1, 17.6, 18.0, 22.7, 27.3, 29.2, 29.3, 29.8, 31.2, 31.9, 122.4,
133.4 ppm; elemental analysis calcd (%) for C16H34Si: C 75.50, H 13.46;
found: C 75.48, H 13.49.
Table 4. Summary of crystallographic data.
trans-4a’
4d
ent-4d
recryst. solvent
formula
crystal size [mm]
FW
crystal system
space group
a [ꢁ]
b [ꢁ]
c [ꢁ]
a [8]
b [8]
Et2O/EtOH
C50H60O2Si4
CH2Cl2/MeOH
C60H80O2Si4
EtOH/MeOH
C60H80O2Si4
(S)-(E)-4-(Triethylsilyl)-2-decene ((S)-1 g): ee>99.2%; [a]2D2 = À2.4 (c=
2.7, benzene); 1H NMR (CDCl3): d = 0.46–0.59 (m, 6H), 0.83–1.00 (m,
12H), 1.03–1.67 (m, 14H), 5.11–5.32 ppm (m, 2H); 13C NMR (CDCl3): d
= 2.3, 7.6, 14.1, 18.1, 22.7, 29.2, 29.5, 30.3, 31.9, 121.9, 133.0 ppm; elemen-
tal analysis calcd (%) for C16H34Si: C 75.50, H 13.46; found: C 75.44, H
13.50.
(S)-(E)-4-(Triisopropylsilyl)-2-decene ((S)-1h): ee>98.8%; [a]2D2 = À16.3
(c=2.4, benzene); 1H NMR (CDCl3): d = 0.88 (t, J = 6.4 Hz, 3H),
0.98–1.84 (m, 35H), 5.13–5.42 ppm (m, 2H); 13C NMR (CDCl3): d =
11.2, 14.1, 18.0, 19.1, 22.7, 29.2, 29.7, 29.8, 30.0, 31.9, 122.3, 133.6 ppm; el-
emental analysis calcd (%) for C19H40Si: C 76.94, H 13.59; found: C
76.67, H 13.74.
0.25ꢂ0.25ꢂ0.35 0.20ꢂ0.40ꢂ0.40 0.20ꢂ0.30ꢂ0.50
805.40
945.60
945.60
triclinic
P1 (no. 1)
11.381(3)
11.802(5)
12.401(4)
112.01(3)
104.22(2)
100.79(3)
1422.9(8)
1
1.103
125
12.562
4616
4260
triclinic
monoclinic
P21 (no. 4)
19.730(4)
11.524(3)
13.380(3)
¯
P1 (no. 2)
10.120 (3)
13.925 (4)
17.787 (6)
74.32 (3)
76.98 (3)
81.91 (3)
2343 (1)
2
106.86(2)
g [8]
V [ꢁ3]
2911.330078(1)
2
1.078
125
12.279
5012
4651
Z
1calcd [gcmÀ3
2qmax [8]
]
1.14
130
14.530
(S)-(E)-3-(Dimethylphenylsilyl)-1-phenyl-1-nonene ((S)-1i): ee>98.7%;
[a]2D2
=
+23.9 (c=2.6, benzene); 1H NMR (CDCl3): d = 0.32 (s, 3H),
m [cmÀ1
]
0.33 (s, 3H), 0.86 (t, J = 6.6 Hz, 3H), 1.07–1.64 (m, 10H), 1.91 (dt, J =
9.2, 3.7 Hz, 1H), 6.03 (dd, J = 15.8, 9.2 Hz, 1H), 6.19 (d, J = 15.8 Hz,
1H), 7.12–7.58 ppm (m, 10H); 13C NMR (CDCl3): d = À4.9, À4.2, 14.0,
22.6, 29.1, 29.6, 31.7, 34.0, 125.6, 126.2, 127.9, 128.4, 129.0, 132.9, 134.1,
137.8, 138.5 ppm; elemental analysis calcd (%) for C23H32Si: C 82.07, H
9.58; found: C 81.90, H 9.65.
independent refl. 7845
observed refl. 5662
no. of parameters 694
672
672
GOF
R1
wR2
1.22
0.0517
0.0531
0.933
0.056
0.071
0.806
0.056
0.072
(S)-(E)-1-Cyclohexyl-3-(dimethylphenylsilyl)-1-nonene ((S)-1j): ee>
99.0%; [a]2D2 = +4.8 (c=2.7, benzene); 1H NMR (CDCl3): d = 0.25 (s,
3H), 0.26 (s, 3H), 0.87 (t, J = 6.6 Hz, 3H), 0.93–1.48 (m, 15H), 1.55–1.78
(m, 6H), 1.83–2.01 (m, 1H), 5.04–5.25 (m, 2H), 7.30–7.38 (m, 3H), 7.44–
7.53 ppm (m, 2H); 13C NMR (CDCl3): d = À5.0, À4.3, 14.1, 22.6, 26.2,
26.3, 28.9, 29.0, 29.1, 31.8, 32.4, 33.6, 33.7, 41.1, 127.5, 128.3, 128.7, 134.1,
135.1, 138.5 ppm; elemental analysis calcd (%) for C23H38Si: C 80.62, H
11.18; found: C 80.47, H 11.19.
Structure solutions and refinements were carried out with the program
package CrystanG (Mac Science). All non-hydrogen atoms were refined
anisotropically by full-matrix least squares. All hydrogen atoms were in-
cluded in the refinement at the calculated positions (0.96 ꢁ) with isotrop-
ic thermal parameters. CCDC-252165 (trans-4a’), CCDC-252164 (4d),
and CCDC-252163 (ent-4d) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
(R)-(E)-1-(Dimethylphenylsilyl)-1-phenyl-2-butene ((R)-1k): ee>98.1%;
[a]2D2 = À13.7 (c=2.4, benzene); 1H NMR (CDCl3): d = 0.22 (s, 3H),
0.25 (s, 3H), 1.66 (dd, J = 6.3, 1.5 Hz, 3H), 3.06 (d, J = 9.8 Hz, 1H),
5.35 (ddq, J = 15.0, 6.3, 0.9 Hz, 1H), 5.75 (ddq, J = 15.0, 9.8, 1.5 Hz,
1H), 6.88–7.41 ppm (m, 10H); 13C NMR (CDCl3): d = À4.7, À4.3, 18.1,
42.4, 124.0, 124.5, 127.4, 128.1, 129.0, 129.9, 134.3, 137.1, 142.4 ppm; ele-
mental analysis calcd (%) for C18H22Si: C 81.14, H 8.32; found: C 81.38,
H 8.57.
Synthesis of highly enantioenriched (R)-1d from (S)-(E)-3d with lower
enantiopurity (Scheme 5): Hexane (2 mL) and (S)-(E)-3d (79.2%ee,
505 mg, 1.1 mmol) at room temperature were added to the catalyst mix-
ture prepared from [Pd(acac)2] (6.7 mg, 2.2ꢂ10À2 mmol) and 1,1,3,3-tetra-
methylbutyl isocyanide (15ꢂ10À3 mL, 8.6ꢂ10À2 mmol). The reaction mix-
ture was stirred under reflux for 1 h. After evaporation of volatile materi-
als, the resultant residual oil was passed through a short Florisil column
Synthesis of 4-(dimethylphenylsilyl)-2-phenyl-2-decene (1l) [Eq. (6)]: A
mixture of [Pd(acac)2] (1.1 mg, 3.6ꢂ10À3 mmol) and 1,1,3,3-tetramethyl-
butyl isocyanide (7.3ꢂ10À3 mL, 1.5ꢂ10À2 mmol) was stirred for 10 min
under nitrogen at room temperature. Toluene (0.4 mL) and disilanyl
ether 3l (94 mg, 0.17 mmol) were added to the catalyst mixture. The mix-
Chem. Eur. J. 2005, 11, 2954 – 2965
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ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2963

M. Suginome et al.
and purified by recrystallization (Et2O/EtOHꢂ2) to afford 4d (294 mg,
58%). Compound 4d (103 mg, 0.11 mmol) was dissolved in toluene
(0.4 mL) and stirred under reflux for 1 h. After replacement of the sol-
vent with THF (0.5 mL), nBuLi (240ꢂ10À3 mL, 1.37m in hexane,
0.33 mmol) was added to the reaction mixture at 08C. After stirring for
10 min at 08C, saturated NH4Cl (aq.) was added to the mixture at 08C.
Extractive workup with Et2O followed by silica gel column chromatogra-
phy (hexane) gave (R)-1d (99.4%ee, 57 mg, 96%).
7.27–7.39 ppm (m, 5H); 13C NMR (CDCl3): d = À5.6, À4.2, 22.2, 33.8,
67.9, 124.8, 127.7, 127.8, 128.3, 129.2, 134.2, 137.2, 142.3 ppm; HRMS
(FAB) calcd for [MH+ÀH2O] (M: C18H24OSi): 267.1569; found 267.1567.
Attempted transformations for ee determination: Pd/C catalyzed hydro-
genation followed by Tamao oxidation: Allylsilane 1d (26 mg,
0.096 mmol) was added to a suspension of Pd/C (5%, 24 mg) in AcOEt
(0.6 mL) at room temperature under H2. The mixture was stirred at room
temperature for 1 h. The palladium catalyst was filtered off through
Celite. Evaporation of the solvent left almost pure hydrogenation prod-
ucts. The flask containing the crude material was filled with nitrogen. To
this was added trifluoroacetic acid (0.5 mL) at room temperature; the
mixture was stirred at 508C for 1 h. The acid was stripped off under
vacuum and MeOH (0.2 mL), KHF2 (30 mg, 0.38 mmol), TBAF (1m in
THF, 0.20 mL), 30% hydrogen peroxide (0.12 mL), and KHCO3 (81 mg,
0.81 mmol) were added to the residue. The mixture was stirred at 508C
for 30 min and then treated with aqueous sodium thiosulfate. Extraction
with ether followed by silica gel column chromatography (hexane/ether
= 3:1) and subsequent purification with HPLC (hexane/ether = 8:1) af-
forded (S)-decan-4-ol (11 mg, 74%).
General procedure for the determination of enantiomeric excesses: 9-
BBN (242 mg, 2.0 mmol) was added to a solution of 1 (0.19 mmol) in
THF (2 mL); the mixture was stirred at 508C for 2 h. Aqueous NaOH
(3m, 0.34 mL) and 30% hydrogen peroxide (2.0 mL) were then added at
08C. After stirring for 1 h at 508C, excess hydrogen peroxide was
quenched by aqueous sodium thiosulfate at room temperature. Extrac-
tion with ether followed by silica gel column chromatography afforded
the corresponding silylalkanols.
(2S,4S)-4-(Dimethylphenylsilyl)decan-2-ol (8d): 1H NMR (CDCl3): d =
0.26 (s, 3H), 0.27 (s, 3H), 0.78–0.94 (m, 4H), 1.06 (d, J = 6.0 Hz, 3H),
1.12–1.46 (m, 11H), 1.47 (dt, J = 2.1, 6.0 Hz, 2H), 3.70 (sextet, J =
6.0 Hz, 1H), 7.30–7.35 (m, 3H), 7.46–7.51 ppm (m, 2H); 13C NMR
(CDCl3): d = À4.3, À3.9, 14.0, 21.9, 22.6, 23.1, 29.1, 29.6, 30.5, 31.7, 40.0,
67.5, 127.8, 128.9, 133.9, 139.0 ppm; elemental analysis calcd (%) for
C18H32OSi: C 73.90, H 11.03; found: C 73.63, H 10.95.
Diimide reduction followed by Tamao oxidation: A mixture of allylsilane
1 (0.036 mmol), tosyl hydrazide (67 mg, 0.36 mmol), and triethylamine
(0.05 mL, 0.36 mmol) in 1,4-dioxane (0.4 mL) was heated for 8 h under
reflux. The cooled mixture was subjected to preparative TLC to give a
hydrogenated product in high yield. The crude material was subjected to
hydrogen peroxide oxidation by the same procedure as for Pd/C hydroge-
nation. Enantiomeric excesses of the obtained alcohols were determined
by chiral HPLC.
(2S,4S)-4-(Trimethylsilyl)decan-2-ol (8e): 1H NMR (CDCl3): d = À0.04
(s, 9H), 0.52–0.60 (m, 1H), 0.85 (t, J = 6.3 Hz, 3H), 1.14 (d, J = 6.0 Hz,
3H), 1.22–1.52 (m, 12H), 3.83 ppm (sextet, J = 6.0 Hz, 1H); 13C NMR
(CDCl3): d
=
À2.4, 14.0, 22.3, 22.6, 23.2, 29.1, 29.8, 30.4, 31.7, 39.9,
67.7 ppm; HRMS (FAB) calcd for [MH+ÀH2O] (M: C13H30OSi):
Reaction with mCPBA: A solution of mCPBA (80%, 69 mg, 0.32 mmol)
in CH2Cl2 (1.5 mL) was added dropwise to a mixture of (S)-1d (80 mg,
0.29 mmol) and NaHCO3 (24 mg, 0.29 mmol) in CH2Cl2 (1.0 mL) at
À788C. The mixture was stirred at 08C for 1 h. After evaporation of the
solvent, MeOH (1.2 mL) and acetic acid (0.2 mL) were added to the mix-
ture at room temperature. After the mixture had been stirred for 20 min
at room temperature, organic material was extracted with diethyl ether
and washed with aqueous NaOH (5m, three times) and water. The organ-
ic phase was dried over MgSO4. After evaporation, the residual oil was
subjected to silica gel column chromatography (hexane/diethyl ether =
1:1) to give an 86:14 mixture of (S)-(E)-3-decen-2-ol and (R)-(Z)-3-
decen-2-ol (23 mg, 50%).
213.2039; found 213.2036.
(2S,4S)-4-(tert-Butyldimethylsilyl)decan-2-ol (8 f): 1H NMR (CDCl3): d
= 0.06 (s, 6H), 0.67–0.84 (m, 1H), 0.88 (t, J = 7.2 Hz, 3H), 0.90 (s, 9H),
1.18 (d, J
= 9.0 Hz, 3H), 1.20–1.40 (m, 10H), 1.47–1.57 (m, 3H),
3.85 ppm (sextet, J = 9.0 Hz, 1H); 13C NMR (CDCl3): d = À6.5, À6.1,
14.1, 17.6, 20.0, 22.7, 23.0, 27.4, 29.3, 29.9, 30.9, 31.8, 40.5, 67.8 ppm; ele-
mental analysis calcd (%) for C16H36OSi: C 70.51, H 13.31; found; C
70.66, H 13.59.
(2S,4S)-4-(Triethylsilyl)decan-2-ol (8 g): 1H NMR (CDCl3): d = 0.55 (q,
J = 8.0 Hz, 6H), 0.63–0.80 (m, 1H), 0.88 (t, J = 6.7 Hz, 3H), 0.95 (t, J
= 8.0 Hz, 9H), 1.17 (d, J = 6.6 Hz, 3H), 1.20–1.61 (m, 13H), 3.85 ppm
(sextet, J = 6.6 Hz, 1H); 13C NMR (CDCl3): d = 2.7, 7.7, 14.1, 19.6,
22.7, 23.1, 29.8, 29.9, 30.7, 31.8, 40.4, 67.8 ppm; HRMS (FAB) calcd for
[MH+ÀH2O] (M: C16H36OSi): 255.2508; found 255.2506.
(2S,4S)-4-(Triisopropylsilyl)decan-2-ol (8h): 1H NMR (CDCl3):
d =
Acknowledgment
0.80–1.65 (m, 17H), 0.88 (t, J = 8.0 Hz, 3H), 1.09 (s, 18H), 1.20 (d, J =
6.1 Hz, 3H), 3.81–4.01 ppm (m, 1H); 13C NMR (CDCl3): d = 11.3, 14.1,
19.2, 19.3, 19.6, 22.7, 30.1, 31.77, 31.80, 32.0, 42.2, 68.2 ppm; HRMS
(FAB) calcd for [MH+ÀH2O] (M: C19H42OSi): 297.2978; found 297.2974.
This work was supported by Grant-in-Aids from the Ministry of Educa-
tion, Science, Sports and Culture, Japan. T. I. acknowledges fellowship
support of the Japan Society for the Promotion of Science for Japanese
Young Scientists.
(1R,3S)-3-(Dimethylphenylsilyl)-1-phenylnonan-1-ol (8i): 1H NMR
(CDCl3): d = 0.24 (s, 3H), 0.25 (s, 3H), 0.78–0.91 (m, 4H), 1.14–1.39 (m,
9H), 1.44–1.56 (m, 1H), 1.64 (d, J = 3.0 Hz, 1H), 1.79 (t, J = 6.6 Hz,
2H), 4.55 (dt, J = 3.0, 6.6 Hz, 1H), 7.14–7.19 (m, 2H), 7.22–7.39 (m,
6H), 7.40–7.46 ppm (m, 2H); 13C NMR (CDCl3): d = À4.6, À3.7, 14.0,
21.5, 22.6, 29.0, 29.7, 30.4, 31.7, 39.3, 74.0, 126.2, 127.6, 127.8, 128.4, 128.9,
133.9, 139.0, 144.6 ppm; elemental analysis calcd (%) for C23H34OSi: C
77.90, H 9.66; found C 78.09, H 9.86.
[1] A. Hosomi, H. Sakurai, Tetrahedron Lett. 1978, 19, 2589. Reviews: I.
Fleming, J. Dunogues, R. Smithers, Org. React. 1989, 37, 57; J. S.
Panek in Comprehensive Organic Synthesis, Vol. 1 (Ed.: B. M.
Trost), Pergamon, Oxford, 1991, p. 579.
[2] [3+2] cycloadditions: a) H.-J. Knçlker, P. G. Jones, J.-B. Pannek,
Synlett 1990, 429; b) H.-J. Knçlker, R. Graf, Synlett 1994, 131; c) J. S.
Panek, N. F. Jain, J. Org. Chem. 1993, 58, 2345; d) J. S. Panek, R. Be-
resis, J. Org. Chem. 1993, 58, 809; [2+2] cycloadditions: e) G. P.
Brengel, C. Rithner, A. I. Meyers, J. Org. Chem. 1994, 59, 5144; f) T.
Akiyama, M. Kirino, Chem. Lett. 1995, 723. For the closely related
cycloaddition with allenylsilanes, see: g) R. L. Danheiser, D. J.
Carini, J. Org. Chem. 1980, 45, 3927.
[3] a) S. H. Yeon, B. W. Lee, B. R. Yoo, M.-Y. Suk, I. N. Jung, Organo-
metallics 1995, 14, 2361; b) E. Yoshikawa, V. Gevorgyan, N. Asao, Y.
Yamamoto, J. Am. Chem. Soc. 1997, 119, 6781; c) M. Yamaguchi, T.
Sotokawa, M. Hirama, Chem. Commun. 1997, 743; d) K. Imamura,
E. Yoshikawa, V. Gevorgyan, Y. Yamamoto, J. Am. Chem. Soc.
1998, 120, 5339.
(1R,3S)-1-Cyclohexyl-3-(dimethylphenylsilyl)nonan-1-ol (8j): 1H NMR
(CDCl3): d = 0.28 (s, 3H), 0.29 (s, 3H), 0.73–1.77 (m, 25H), 0.86 (t, J =
8.0 Hz, 3H), 3.14–3.28 (m, 1H), 7.30–7.37 (m, 3H), 7.46–7.54 ppm (m,
2H); 13C NMR (CDCl3): d = À4.3, À3.7, 14.0, 21.9, 22.6, 26.1, 26.4, 26.5,
26.8, 29.0, 29.46, 29.54, 30.8, 31.7, 34.6, 43.2, 75.3, 127.8, 128.9, 133.9,
139.4 ppm; elemental analysis calcd (%) for C23H40OSi: C 76.60, H 11.18;
found: C 76.33, H 11.20.
(1S,3R)-4-(Dimethylphenylsilyl)-4-phenylbutan-2-ol (8k): 1H NMR
(CDCl3): d = 0.16 (s, 3H), 0.24 (s, 3H), 1.04 (d, J = 6.0 Hz, 3H), 1.68
(ddd, J = 13.8, 7.8, 3.3 Hz, 1H), 2.10 (dt, J = 7.8, 13.8 Hz, 1H), 2.25
(dd, J = 13.8, 3.3 Hz, 1H), 3.62 (tq, J = 6.0, 7.8 Hz, 1H), 6.94 (d, J =
7.5 Hz, 2H), 7.07 (tt, J = 7.5, 1.5 Hz, 1H), 7.18 (t, J = 7.5 Hz, 2H),
2964
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2005, 11, 2954 – 2965

Highly Enantioenriched (E)-Allylsilanes
FULL PAPER
[4] W. R. Roush in Comprehensive Organic Synthesis, Vol. 2 (Ed.: B. M.
Trost), Pergamon, Oxford, 1991, p. 1.
1996, 37, 8887; f) M. Suginome, H. Nakamura, Y. Ito, Tetrahedron
Lett. 1997, 38, 555.
[5] T. K. Sarkar, Synthesis 1990, 969 and 1101; T. K. Sarkar, Sci. Synth.
2002, 4, 837.
[19] See ref. [18b] for some attempts at IBS of allylic alcohols with termi-
nal C=C bonds.
[6] T. Hayashi, M. Konishi, M. Kumada, J. Am. Chem. Soc. 1982, 104,
4963; T. Hayashi, M. Konishi, M. Kumada, J. Org. Chem. 1983, 48,
281.
[20] D. J. Peterson, J. Org. Chem. 1968, 33, 780.
[21] For preliminary reports of this article, see: M. Suginome, A. Matsu-
moto, Y. Ito, J. Am. Chem. Soc. 1996, 118, 3061; M. Suginome, T.
Iwanami, A. Matsumoto, Y. Ito, Tetrahedron: Asymmetry 1997, 8,
859.
[22] The requisite chlorodisilanes were readily prepared by the reaction
of (diethylamino)diphenylsilyllithium with the corresponding tri-
(organo)chlorosilanes followed by treatment with acetyl chloride.
a) K. Tamao, A. Kawachi, Y. Ito, J. Am. Chem. Soc. 1992, 114,
3989–3990; b) K. Tamao, A. Kawachi, Y. Nakagawa, Y. Ito, J. Orga-
nomet. Chem. 1994, 473, 29–34; Review: c) K. Tamao, A. Kawachi,
Adv. Organomet. Chem. 1995, 38, 1–58.
[7] C. E. Masse, J. S. Panek, Chem. Rev. 1995, 95, 1293.
[8] Asymmetric cross-coupling of a-(silyl)alkyl Grignard reagents to al-
kenyl bromides in the presence of chiral ferrocenylphosphine–palla-
dium complexes: a) T. Hayashi, M. Konishi, H. Ito, M. Kumada, J.
Am. Chem. Soc. 1982, 104, 4962; b) T. Hayashi, M. Konishi, Y. Oka-
moto, K. Kabeta, M. Kumada, J. Org. Chem. 1986, 51, 3772.
[9] Wittig olefination of enantioenriched a-silylaldehydes: V. Bhushan,
B. B. Lohray, D. Enders, Tetrahedron Lett. 1993, 34, 5067.
[10] Regioselective nucleophilic substitution of enantioenriched allylic
esters and carbamates with (organosilyl)cuprates: a) I. Fleming,
A. P. Thomas, J. Chem. Soc. Chem. Commun. 1986, 1456; b) I. Flem-
ing, D. Higgins, N. J. Lawrence, A. P. Thomas, J. Chem. Soc. Perkin
Trans. 1 1992, 3331.
[23] One isomer, chiral-4d, possesses a C2 axis passing through the
center of the eight-membered ring, while achiral-4d has an inversion
center at the center of the ring.
[24] The ee determination was carried out according to the procedure
[11] Claisen rearrangement of enantioenriched allylic alcohols: a) K.
Mikami, T. Maeda, N. Kishi, T. Nakai, Tetrahedron Lett. 1984, 25,
5151; b) M. A. Sparks, J. S. Panek, J. Org. Chem. 1991, 56, 3431.
[12] Asymmetric hydrosilation of 1,3-dienes: a) T. Hayashi, S. Hengras-
mee, Y. Matsumoto, Chem. Lett. 1990, 1377; b) T. Hayashi, Y. Mat-
sumoto, I. Morikawa, Y. Ito, Tetrahedron: Asymmetry 1990, 1, 151,
and references therein.
[13] Asymmetric reduction of allyl carbonates: T. Hayashi, H. Iwamura,
Y. Uozumi, Tetrahedron Lett. 1994, 35, 4813.
[14] Asymmetric silylation of allyl chlorides: T. Hayashi, A. Ohno, S.-j.
Lu, Y. Matsumoto, E. Fukuyo, K. Yanagi, J. Am. Chem. Soc. 1994,
116, 4221.
that includes reduction of the C=C bond with diimide followed by
À
oxidation of the Si C bond as described below.
[25] For discussion of the mechanism of the Peterson elimination, see:
a) T. Kawashima, N. Iwama, R. Okazaki, J. Am. Chem. Soc. 1992,
114, 7598; b) K. Naganuma, T. Kawashima, R. Okazaki, Chem. Lett.
1999, 1139, and references therein.
[26] a) J. P. Vigneron, M. Dhaenens, A. Horeau, Tetrahedron 1973, 29,
1055; b) V. Rautenstrauch, Bull. Soc. Chim. Fr. 1994, 131, 515.
[27] In reality, the dimerization took place with slight preference for the
achiral dimer as shown in Scheme 3.
[28] a) K. Tamao, T. Kakui, M. Akita, T. Iwahara, R. Kanatani, J. Yoshi-
da, M. Kumada, Tetrahedron 1983, 39, 983; b) K. Tamao, N. Ishida,
T. Tanaka, M. Kumada, Organometallics 1983, 2, 1694. Review: c) K.
Tamao, Adv. Silicon Chem. 1996, 3, 1–62.
[15] Other preparation of enantioenriched allylsilanes: M. J. C. Buckle, I.
Fleming, S. Gil, Tetrahedron Lett. 1992, 33, 4479.
[16] a) M. Suginome, Y. Ito, J. Chem. Soc. Dalton Trans. 1998, 1925;
b) M. Suginome, Y. Ito, J. Synth. Org. Chem. Jpn. 1997, 55, 1041;
c) Y. Ito, M. Suginome, M. Murakami, J. Org. Chem. 1991, 56, 1948;
d) M. Murakami, H. Oike, M. Sugawara, M. Suginome, Y. Ito, Tetra-
hedron 1993, 49, 3933; e) M. Murakami, M. Suginome, K. Fujimoto,
Y. Ito, Angew. Chem. 1993, 105, 1542; Angew. Chem. Int. Ed. Engl.
1993, 32, 1473; f) M. Suginome, A. Matsumoto, Y. Ito, J. Org. Chem.
1996, 61, 4884; g) M. Suginome, A. Takama, Y. Ito, J. Am. Chem.
Soc. 1998, 120, 1930.
[29] a) I. Fleming, N. K. Terrett, Tetrahedron Lett. 1983, 24, 4153; b) T.
Hayashi, Y. Okamoto, K. Kabeta, T. Hagihara, M. Kumada, J. Org.
Chem. 1984, 49, 4224.
[30] I. Fleming, N. J. Lawrence, J. Chem. Soc. Perkin Trans. 1 1992, 3309.
[31] M. Suginome, T. Iwanami, Y. Ito, J. Org. Chem. 1998, 63, 6096. M.
Suginome, T. Iwanami, Y. Ito, Chem. Commun. 1999, 2537; M. Sugi-
nome, T. Iwanami, A. Yamamoto, Y. Ito, Synlett 2001, 1042; M. Su-
ginome, Y. Ito, J. Organomet. Chem. 2003, 685, 218.
[32] M. Suginome, T. Iwanami, Y. Ito, J. Am. Chem. Soc. 2001, 123, 4356.
[33] F. Sato, H. Ishikawa, H. Watanabe, T. Miyake, M. Sato, J. Chem.
Soc. Chem. Commun. 1981, 718.
[17] T. K. Sarkar, S. A. Haque, A. Basak, Angew. Chem. 2004, 116, 1441;
Angew. Chem. Int. Ed. 2004, 43, 1417.
[18] a) M. Murakami, P. G. Andersson, M. Suginome, Y. Ito, J. Am.
Chem. Soc. 1991, 113, 3987; b) M. Murakami, M. Suginome, K. Fuji-
moto, H. Nakamura, P. G. Andersson, Y. Ito, J. Am. Chem. Soc.
1993, 115, 6487; c) M. Suginome, Y. Yamamoto, K. Fujii, Y. Ito, J.
Am. Chem. Soc. 1995, 117, 9608; d) M. Suginome, A. Matsumoto, K.
Nagata, Y. Ito, J. Organomet. Chem. 1995, 499, C1; e) M. Suginome,
S. Matsunaga, T. Iwanami, A. Matsumoto, Y. Ito, Tetrahedron Lett.
[34] V. S. Martin, S. S. Woodard, T. Katsuki, Y. Yamada, M. Ikeda, K. B.
Sharpless, J. Am. Chem. Soc. 1981, 103, 6237; Y. Gao, R. M.
Hanson, J. M. Klunder, S. Y. Ko, H. Masamune, K. B. Sharpless, J.
Am. Chem. Soc. 1987, 109, 5765.
Received: October 12, 2004
Published online: March 3, 2005
Chem. Eur. J. 2005, 11, 2954 – 2965
www.chemeurj.org
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2965