Stereoselective synthesis of allyl ethers using α,β-unsaturated acylsilanes

Article abstract of DOI:10.1016/j.tetlet.2017.01.054

The reaction behavior of silylvinylmethanols with acid catalysts was investigated. The starting silylvinylmethanols 2 were prepared by the reaction of the corresponding α,β-unsaturated acylsilanes 1 with organocerium reagents. The reaction of 2 with TsOH

Full text of DOI:10.1016/j.tetlet.2017.01.054

Accepted Manuscript
Stereoselective synthesis of allyl ethers using α,β-unsaturated acylsilanes
Mitsunori Honda, Takehide Takatera, Ryosuke Ui, Ko-Ki Kunimoto, Masahito
Segi
PII:
S0040-4039(17)30077-1
DOI:
http://dx.doi.org/10.1016/j.tetlet.2017.01.054
TETL 48557
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
1 December 2016
10 January 2017
17 January 2017
Please cite this article as: Honda, M., Takatera, T., Ui, R., Kunimoto, K-K., Segi, M., Stereoselective synthesis of
allyl ethers using α,β-unsaturated acylsilanes, Tetrahedron Letters (2017), doi: http://dx.doi.org/10.1016/j.tetlet.
2017.01.054
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Graphical Abstract
To create your abstract, type over the instructions in the template box below.
Fonts or abstract dimensions should not be changed or altered.
Stereoselective synthesis of allyl ethers using
Leave this area blank for abstract info.
,-unsaturated acylsilanes
Mitsunori Honda,* Takehide Takatera, Ryosuke Ui, Ko-Ki Kunimoto, and Masahito Segi

1
Tetrahedron Letters
Stereoselective synthesis of allyl ethers using ,-unsaturated acylsilanes
Mitsunori Honda, Takehide Takatera, Ryosuke Ui, Ko-Ki Kunimoto, and Masahito Segi
Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192,
Japan
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
The reaction behavior of silylvinylmethanols with acid catalysts was investigated. The starting
silylvinylmethanols 2 were prepared by the reaction of the corresponding ,-unsaturated
acylsilanes 1 with organocerium reagents. The reaction of 2 with TsOH in methanol proceeded
to give the corresponding silyl-substituted allyl ether derivatives 3 in high yields with good
stereoselectivity. The silylvinylmethanols 2 having a n-alkyl or phenyl group on the carbinyl
carbon reacted to afford the E-allyl derivatives selectively. On the other hand, the reaction of
silylvinylmethanols possessing a tert-butyl group gave the Z-isomers exclusively. The
following protodesilylation of the resulting allyl derivatives 3 proceeded with retention of
configuration to provide the geometrically constrained allyl ethers 4.
Available online
Keywords:
,-Unsaturated acylsilane
Silylvinylmethanol
Allylic rearrangement
Allyl ether
2009 Elsevier Ltd. All rights reserved.
Protodesilylation
Introduction
Acylsilanes will become useful synthetic intermediates due to
specific properties of sterically congested and electrically
positive silyl group and carbonyl group that is one of the most
reactive organic functional groups.1 We have currently
investigated the newly synthetic methods for functionalized
acylsilanes2 and their synthetic utilities.3 Especially, cyclopropyl
silyl ketones have been conveniently synthesized2 and utilized as
a building block for the stereoselective synthesis of homoallyl
derivatives by applying the specific properties of the silyl group
as a good directing and leaving group (Scheme 1).3a Therefore
our stereoselective synthetic route for Z-homoallyl derivatives is
existing as a complementary method for the preparation of E-
homoallyl derivatives developed by Julia and co-workers
(Scheme 2).4 While this serviceable and useful method has not
been applied to prepare Z-allyl derivatives that are homolog
compounds of Z-homoallyl derivatives, there is a report to
construct allyl alcohol possessing silyl group at the terminal vinyl
carbon derived from -hydroxyalkenylsilane by similar type of
reaction.5 In this letter, stereoselective synthesis of Z-allyl ethers
4 using ,-unsaturated acylsilanes 1 by a sequence of reactions
mentioned above is described (Scheme 3). Our synthetic method
will be very helpful to prepare Z-allyl derivatives that have a
great deal of potential in organic reactions (e.g. Claisen
rearrangement,6 Sharpless epoxidation7) to elaborate naturally
occurring complex compounds.
Results and discussion
The starting materials, ,-unsaturated acylsilanes 1, are
prepared by four routes I-IV as follows depending on the kind of
terminal substituent group R (Scheme 4). The silylation of easily
available ,-unsaturated aldehydes 5 was carried out to obtain
———
 Corresponding author. Tel.: +81-76-234-4789; fax: +81-76-234-4800; e-mail: honda@se.kanazawa-u.ac.jp

2
Tetrahedron
Route I
Protection
Silylation
R
S
S
H
S
S
R
R
Si
O
Deprotection
O
R
H
5
OH
Swern ox.
O
SiLi
Si
R
Si
Si
1
Route IV
Enolization
Route II
retro-Brook
rearrangement
– MeOH
OMe
OMe
Route III
R
MeO
R
O
OSiMe3
R
OH
R
OSi
Silylation
Si
Si
Mukaiyama-
aldol reaction
Scheme 4. Preparation of
, -unsaturated acylsilanes 1.
the corresponding acylsilanes (route I). Since the direct
conversion of aldehyde to silyl ketone is impossible, the
umpolung of carbonyl group was employed by thioacetal
formation.8 The aldehydes 5 were quantitatively converted to
thioacetals 6 by reaction with 1,3-propanedithiol and iodine.9
These results were shown in Table 1. The deprotonation of
cinnamaldehyde did not proceed well. Next, the silyl protection
of allyl alcohol and the continuing retro-Brook rearrangement13
to afford silyl alcohol were performed (route III). A sequence of
reactions beginning with E-2-nonenol gives the corresponding
silyl alcohols 8 in good yields, however 1,2-silyl migration of
cynnamyloxysilane did not proceed (Table 2).12-14 The Swern
oxidation of the resulting 1-silyl-2-nonenols 8 provided the target
acylsilanes 1 (Scheme 6).14a,15 Since it was difficult to synthesize
the compound 1 possessing a methyl group at the terminal
position via routes I–III, this acylsilane was prepared by
Mukaiyama aldol reaction16 using silyl enol ether of acetylsilane
resulting thioacetals
6 with n-butyllithium, followed by
electrophilic reaction with chlorosilanes afforded 2-silylated 1,3-
dithiane derivatives 7 in high yields.10 The deprotection of
silyldithianes 7 with calcium carbonate and iodine provided the
corresponding 1 having a phenyl group at terminal position
(Entries
1
and 2).11 However, similar deprotection of
silyldithianes 7 possessing a terminal alkyl group gave the
complex mixture (Entries 3 and 4). Then the nucleophilic
silylation of ,-unsaturated aldehydes 5 with silyllithium and
the following oxidation of resulting silyl alcohols to prepare the
desired acylsilanes 1 were investigated (Scheme 4, route II). The
nucleophilic reaction of silyllithium, prepared from disilane with
methyllithium, to 5 proceeded to give silyl alcohol 8 with
moderate yield (Scheme 5).12 However the reaction of

3
The preparation of silyl-substituted allyl alcohols 2 by
nucleophilic addition of organocerium reagents19 to the resulting
was examined.17d,e,20 Acylsilanes
were treated with
1
1
organocerium reagents at –78 °C in THF as shown in Table 3.
The reaction proceeded to afford the corresponding silyl alcohols
2 in moderate to high yields, accompanied by the formation of -
silyl ketones 10 as by-product. In these reactions, the selectivity
on the formation of 2 and 10 was affected by the bulkiness of
nucleophilic groups (R’). The reaction using methyl or
phenylcerium reagent as nucleophiles predominantly gave silyl
alcohols 2 independent of the kind of substituent of acylsilanes 1
(Entries 1, 4, 5, 9, 10, 12, and 13). Though the rate of production
of -silyl ketones was increased with increasing of the bulkiness
of nucleophilic groups (Entries 1-3, and 5-8). The plausible
reaction mechanism of nucleophilic addition to acylsilanes is
proposed as shown in Scheme 8.20,21 First, the attack of
nucleophilic group occurs to yield alkoxy anion species A. When
R’ is a small group, the following hydrolysis proceeds to afford
silyl alcohols 2, whereas R’ is a bulky group, the Brook
rearrangement22 also goes to form carbanion B in order to avoid
the steric repulsion between R’ and bulky silyl group on
quaternary carbon. In the case of the intermediate A having a
phenyl group as R’, the phenyl group acts as a small group since
it has a strainless planear structure. After the resonance with the
ally anion C, 1,4-migration of silyl group and the following
hydrolysis of D proceed to give -silyl ketones 10.
(route IV). The acetylsilane was easily enolized with LDA. Then
the resulting enolate was trapped with chlorosilane to afford the
silyl enol ether (Scheme 7).17 The Mukaiyama aldol reaction of
this enol ether with dimethyl acetal gave the corresponding -
methoxyacylsilane in good yield,17,18 and the following -
elimination of methanol provided the desired propenyl silyl
ketone 1.17e

4
Tetrahedron
Then, treatment of silyl-substituted allyl alcohols 2, derived
These results suggest that the stereochemistry of allylic
rearrangement of the silyl-substituted allyl alcohols 2 is
dependent on the steric repulsion between substituents, silyl
group on the carbinyl carbon and the terminal group of alkene
moiety. Thus, the following mechanism for the reaction is
proposed (Scheme 9). The acid protonates at the oxygen atom of
the starting alcohol and allyl cation species E23 is formed. When
Si group is larger than R’ (n-alkyl or phenyl), the formation of
trans-allylic cation F is favored compared to cis-allylic cation G
due to the less strain between R’ group and terminal substituent
R. As a consequence, E-silylalkene is formed selectively. In
contrast, in the case of the reaction using silyl-substituted allyl
alcohols having a s- or t-alkyl group on the carbinyl carbon,
trans-allylic cation F is disfavored by the steric repulsion
between s- or t-alkyl group, that is bulky compared with silyl
from the above nucleophilic reaction, with TsOH in methanol
was carried out.3a The allylic rearrangement proceeded to give
silyl-substituted allyl ethers 3 stereoselectively. The results are
summarized in Table 4. The yields of allyl derivatives 3 were
generally reasonable, irrespective of the substituents on the
terminal or the carbinyl carbon except in the presence of t-butyl
group. It is noteworthy that the stereoselectivity of these
reactions was significantly influenced by the bulkiness of the
substituents on the carbinyl carbon. The reaction of silyl alcohols
2 having a n-alkyl or phenyl group on the carbinyl carbon
afforded the E-isomer selectively (Entries 1, 2, 4, 5, 6, 9, 10, 11,
12, and 13). On the other hand, the alcohols 2 possessing a s- or
t-alkyl group on that reacted to yield the corresponding Z-isomer
with high stereoselectivity (Entries 3, 7, 8, and 14).

5
gave the isomeric mixture of allyl derivatives 4 (Table 7, Entry
1). The reason for this unexpected reaction is not yet understood.
In addition, that of vinylsilane having another phenyl group on
the  carbon afforded vinyl ether 11 preferentially that was
derived by isomerization from allyl derivatives 4 (Entry 2).
group, and terminal group R. Although the Si group is also bulky,
the long Si–C single bond reduces the effective steric
hindrance.24 As a result, the reaction of silyl alcohols possessing
a
s- or t-alkyl group leads to Z-silylalkene with high
stereoselectivity by way of cis-allylic cation G.
Conclusion
It is known that the protodesilylation of vinylsilane proceeds
with complete retention of the configuration.25 Thus,
protodesilylation of the resulting E- and Z-silyl-substituted allyl
derivatives 3 was examined and the results are shown in Tables 5
and 6. Treatment of E- and Z-3 with tetrabutylammonium
fluoride (TBAF) in hexamethylphosphoric triamide at 80 °C gave
the corresponding Z- and E-protodesilylated compounds 4,
respectively. While the reaction of vinylsilane possessing an aryl
group on silicon atom proceeded smoothly, the reactivity of
desilylation of vinyltrialkylsilane was low.25a,b Unfortunately, the
reaction of vinylsilanes having a phenyl group on the  carbon
In conclusion, acid-catalyzed allylic rearrangement of
silylvinylmethanols
2
has
been
described.
The
silylvinylmethanols 2 reacted with TsOH in methanol to afford
the corresponding allyl ethers 3 in high yields with good
stereoselectivity, depended on the substituents on the carbinyl
carbon. The silylvinylmethanols 2 having a n-alkyl or phenyl
group reacted to afford the E-allyl derivatives 3 selectively. On
the other hand, the reaction of silylvinylmethanols possessing a
tert-butyl group gave Z-isomers exclusively. The following
protodesilylation of the resulting allyl derivatives 3 proceeded
with retention of configuration. Thus, it was achieved that the
regioselective formation of Z and E-allyl ethers derivatives 4,
respectively. Further studies are aimed at expanding the scope of
these reactions, and introduction of other functional group
instead of silyl group and the following allylic rearrangement
reaction are now in progress in our laboratory. The results will be
reported in due course.
Acknowledgments
This work was supported by Kanazawa University
SAKIGAKE Project and Japan Society for the Promotion of
Science (JSPS) KAKENHI Grant Number 15K05585, and was
promoted by Center of Innovation (COI) program “Construction
of next-generation infrastructure using innovative materials:
Realization of a safe and secure society that can coexist with the
Earth for centuries” supported by Ministry of Education, Culture,
Sports, Science and Technology (MEXT) and The Japan Science
and Technology Agency (JST).
References and notes
1.
For reviews on synthesis and reaction of acylsilanes, see: (a)
Brook, M. A. Silicon in Organic, Organometallic, and Polymer
Chemistry; Wiley: New York, 2000; (b) Page, P. C. B.; McKenzie,
M. J. Product Subclass 25: Acylsilanes. In Science of Synthesis;
Fleming, I., Ed.; Thieme: Stuttgart, 2001; Vol. 4, pp 513−568; (c)
Bonini, B. F.; Comes-Franchini, M.; Fochi, M.; Mazzanti, G.;
Ricci, A. J. Organometal. Chem. 1998, 567, 181–189; (d) Qi, H.;
Curran, D. P. In Acyl Silicon, Germanium, or Boron Functions.
Comprehensive Organic Functional Group Transformations:
Synthesis: Carbon with Two Attached Heteroatoms with at Least
One Carbon-to-Heteroatom Multiple Link; Katrizky, A. R., Meth-
Cohn, O., Rees, C. W., Moody, C. J., Eds.; Pergamon: Oxford,

6
Tetrahedron
1995; Vol. 5, pp 409–433, Chapter 5.09; (e) Cirillo, P. F.; Panek,
14. (a) Gree, R. Org. Lett. 2013, 15, 1524–1527; (b) Danheiser, R. L.;
Fink, D. M. J. Org. Chem. 1985, 50, 5393–5396.
J. S. Org. Prep. Proced. Int. 1992, 24, 553–582; and references
cited therein.
15. (a) Mancuso, A. J.; Swern, D. Synthesis 1981, 165–185; (b) Lee,
T. V. Oxidation Adjacent to Oxygen of Alcohols by Activated
DMSO Methods. In Comprehensive Organic Synthesis; Trost, B.
M., Ed.; Pergamon Press: Oxford, 1991; Vol. 7, pp 291–304.
16. Matsuo, J.-I.; Murakami, M. Angew. Chem., Int. Ed. Engl. 2013,
52, 9109–9118; and references cited therein.
2.
3.
(a) Honda, M.; Nakae, K.; Nishizawa, T.; Suda, M.; Kunimoto,
K.-K.; Segi, M. Tetrahedron 2011, 67, 9500–9508; (b) Nishizawa,
T.; Nakae, K.; Honda, M.; Kunimoto, K.-K.; Segi, M.
Tetrahedron Lett. 2010, 51, 1294–1297; (c) Nakajima, T.; Tanabe,
M.; Ohno, K.; Segi, M.; Suga, S. Chem. Lett. 1986, 177–180.
(a) Honda, M.; Yamamoto, Y.; Tsuchida, H.; Segi, M. and
Nakajima, T. Tetrahedron Lett. 2005, 46, 6465–6468; (b) Honda,
M.; Nakajima, T.; Okada, M.; Ymaguchi, K.; Suda, M.;
Kunimoto, K.-K.; Segi. M. Tetrahedron Lett. 2011, 52, 3740–
3742; (c) Honda, M.; Iwamoto, R.; Nogami, Y.; Segi, M. Chem.
Lett. 2005, 34, 466–467; (d) Honda, M.; Naitou, T.; Hoshino, H.;
Takagi, S.; Segi, M. and Nakajima, T. Tetrahedron Lett. 2005, 46,
7345–7348.
17. (a) Honda, M.; Oguchi, W.; Segi, M.; Nakajima, T. Tetrahedron
2002, 58, 6815–6823; (b) Honda, M.; Ohkura, N.; Saisyo, S.-I,;
Segi, M.; Nakajima, T. Tetrahedron 2003, 59, 8203–8212; (c)
Honda, M.; Mikami, Y.; Sanjyo, T.; Segi, M.; Nakajima, T. Chem.
Lett. 2005, 34, 1432–1433; (d) Honda, M. and Segi, M. J. Synth.
Org. Chem, Jpn. 2010, 68, 601–613; (e) Honda, M.; Nakamura,
T.; Sumigawa, T.; Kunimoto, K.-K.; Segi. M.; Heteroatom Chem.,
2014, 25. 565–577.
4.
For reports about Julia ring opening of a cyclopropylmethanol,
see: (a) Brimble, M. A.; Prabaharan, H. Tetrahedron 1998, 54,
2113– 2128; (b) McCormick, J. P.; Barton, D. L. J. Org. Chem.
1980, 45, 2566– 2570; (c) Sarel, S.; Yovell, J.; Sarel-Imber, M.
Angew. Chem., Int. Ed. Engl. 1968, 7, 577– 588; (d) Brady, S. F.;
Ilton, M. A.; Johnson, W. S. J. Am. Chem. Soc. 1968, 90, 2882–
2888; (e) Julia, M.; Julia, S.; Gue gan, R. Bull. Soc. Chim. Fr.
1960, 1072– 1079; (f) Julia, M.; Julia, S.; Tchen, S.-Y. Bull. Soc.
18. (a) Sato, T.; Arai, M.; Kuwajima, I. J. Am. Chem. Soc. 1977, 99,
5827–5828; (b) Minami, N.; Abe, T.; Kuwajima, I. J. Organomet.
Chem. 1978. 145, C1–C3; (c) Sato, T.; Abe, T.; Kuwajima, I.
Tetrahedron Lett. 1978, 19, 259–262.
19. Imamoto, T.; Suguira, Y.; Takiyama, N. Tetrahedron Lett. 1984,
25, 4233–4236.
20. Bonini, B. F.; Comes-Franchini, M.; Fochi, M.; Mazzanti, G.;
Ricci, A.; Varchi, G. Synlett 2000, 1688–1690.
21. (a) Enda, J.; Kuwajima, I. J. Am. Chem. Soc. 1985, 107, 5495–
5501; (b) Kato, M.; Mori, A.; Oshino, H.; Enda, J.; Kobayashi, K.;
Kuwajima, I. J. Am. Chem. Soc. 1984, 106, 1773–1778.
22. (a) Brook, A. G. Acc. Chem. Res. 1974, 7, 77–84; (b)Page, P. C.
B.; Klair, S. S.; Rosenthal, S. Chem. Soc. Rev. 1990, 19, 147–195;
(c) Moser, W. H. Tetrahedron 2001, 57, 2065–2084.
23. Several reports regarding the stability of -silyl cation, see: (a)
Sakaguchi, K.; Yamada, T.; Ohfune, Y. Tetrahedron Lett. 2005,
46, 5009–5012. (b) Apeloig, Y.; Stanger, A. J.Am.Chem.Soc.1985,
107, 2806–2807; (c) Soderquist, J. A.; Hassner, A. Tetrahedron
Lett. 1988, 29, 1899–1902; (d) Apeloig, Y.; Biton, R.; Abu-Freih,
A. J. Am. Chem. Soc. 1993, 115, 2522–2523.
24. For a review on steric effects of silyl groups, see: Hwu, R. J.-R.;
Tsay, S.-C.; Cheng, B.-L. In The Chemistry of Organic Silicon
Compounds; Rappoport, Z., Apeloig, Y., Eds.; Wiley: Chichester,
UK, 1998, pp 431–494.
25. (a) Oda, H.; Sato, M.; Morizawa, Y.; Oshima, K.; Nozaki, H.
Tetrahedron Lett., 1983, 24, 2877–2880; (b) Oda, H.; Sato, M.;
Morizawa, Y.; Oshima, K.; Nozaki, H. Tetrahedron, 1985, 41,
3257–3268; (c) Wrobel, J. E. Ganem, B. J. Org. Chem. 1983, 48,
3761–3764; (d) Anderson, J. C.; Flaherty, A. J. Chem. Soc.,
Perkin Trans. 1, 2000, 3025–3027.
Chim. Fr. 1961, 1849– 1853.
Sakaguchi, K.; Higashino, M.; Ohfune, Y. Tetrahedron 2003, 59,
6647–6658.
5.
6.
For reviews on Claisen rearrangement, see: (a) Claisen, L. Ber.
1912, 45, 3157–3166; (b) Rhoads, S. J.; Raulins, N. R. Org. React.
1975, 22, 1-252; (c) Bennett, G. B. Synthesis 1977, 589-606. ꢀ
For reviews on Katsuki-Sharpless epoxidation reaction, see: (a)
Katsuki, T., Sharpless, K. B. J. Am. Chem. Soc. 1980, 102, 5974–
5976; (b) Katsuki, T.; Martin, V. S. Org. React. 1996, 48, 1–300.
(a) Corey, E. J.; Seebach, D. Angew. Chem. Int. Ed. 1965, 4,
1075–1077; (b) Corey, E. J.; Seebach, D. Angew. Chem. Int. Ed.
1965, 4, 1077–1078.
7.
8.
9.
Hazarkhani, H.; Firouzabadi, H.; Iranpoor, N. J. Org. Chem. 2001,
66, 7527–7529.
10. (a) Takeda, T.; Fujiwara, T.; Sawabe, K. Tetrahedron 1997, 53,
8349–8370; (b) Portella, C.; Hammaecher, C.; Bouillon, J.
Tetrahedron 2009, 65, 5527–5534.
11. (a) Portella, C.; Bouillon, J.-P. Eur. J. Org. Chem. 1999, 1571–
1580; (b) Bouillon, J.-P.; Saleur, D.; Portella, C. Synthesis 2000,
843–849.
12. Still, C. W. J. Org. Chem. 1976, 41, 3063–3064.
13. (a) West, R. In Advances in Organometallic Chemistry; Stone, F.
G. A., West, R., Eds.; Academic Press: New York, 1977; Vol. 16,
pp 1–31; (b) Linderman, R. J.; Ghannam, A. J. Am. Chem. Soc.
1990, 112, 2392–2398.

Table 1. Preparation of ,-unsaturated acylsilanes 1 via dithiane route
Entry
R
Yield of 6a (%)
Si
Yield of 7a (%)
Yield of 1b (%)
66
1
SiMe3
>99
>99
91
Ph
>99
2
SiMe2Ph
SiMe2Ph
SiMe2Ph
39
3
n-C6H13
>99
>99
Complex mixture
Complex mixture
4
Me
>99
aCrude yield.
bIsolated yield.
Table 2. Synthesis of silyl alcohol 8 via retro-Brook rearrangement of silyl ehter 9
Entry
R
Si
Yield of 9a (%)
Yield of 8a (%)
1
n-C6H13
n-C6H13
Ph
SiMe3
SiMe2Ph
SiMe3
91
88
2
>99
88
55
3
Complex mixture
aCrude yield.
Table 3. Nucleophilic addition reaction with organocerium reagents
Entry
1
R
Si
R’
Total yielda (%)
2/10b
>99/1
87/13
62/38
>99/1
>99/1
85/15
54c/46
47/53
>99/1
>99/1
87/13
>99/1
>99/1
65/35
Ph
SiMe3
Me
90
50
60
74
55
22
39
35
70
80
47
58
61
39
2
Ph
SiMe3
n-Bu
t-Bu
Ph
3
Ph
SiMe3
4
Ph
SiMe3
5
Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe3
Me
6
Ph
n-Bu
s-Bu
t-Bu
Ph
7
Ph
8
Ph
9
Ph
10
11
12
13
14
Me
Me
Me
n-C6H13
n-C6H13
Me
n-Bu
Ph
Me
SiMe3
t-Bu
Molar ratio; 1/R’CeCl2=1:6.
R’CeCl2 was generated by the reaction of R’Li with CeCl3.
a Isolated yield.
bDetermined by 1H NMR analysis.
cDiastereomer mixture was obtained (51:49).

Table 4. Rearrangement reaction of silyl alcohols 2 with TsOH
Entry
1
R
R’
Si
Temp. (°C)
Time (h)
0.5
Yielda (%)
93
E/Zb
Ph
Me
SiMe3
0
76/24
93/7
2
Ph
n-Bu
t-Bu
Ph
SiMe3
0
0.5
96
3
Ph
SiMe3
r.t.
0
2.0
65
2/98
4
Ph
SiMe3
2.0
75
96/4
5
Ph
Me
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe2Ph
SiMe3
0
0.5
80
91/9
6
Ph
n-Bu
s-Bu
t-Bu
Ph
0
0.5
>99
81
89/11
32/68
4/96
7
Ph
r.t.
r.t.
r.t.
0
1.0
8
Ph
2.0
47
9
Ph
1.0
76
97/3
10
11
12
13
14
Me
Me
Me
n-C6H13
n-C6H13
Me
0.5
77
85/15
64/36
97/3
n-Bu
Ph
0
0.5
77
0
2.0
91
Me
0
0.5
68
78/22
2/98
t-Bu
SiMe3
r.t.
10.0
79
Molar ratio; 2/TsOH/MeOH=1:3:40.
a Isolated yield.
bDetermined by 1H NMR analysis.
Table 5. Protodesilylation of E-vinylsilanes 3 with n-Bu4NF
Entry
R
R’
Si
Time (h)
2.0
Yielda (%)
E/Zb
1
2
3
Ph
Ph
Ph
Me
Me
n-Bu
SiMe3
SiMe2Ph
SiMe2Ph
13
45
62
0/100
0/100
0/100
2.5
4.5
Molar ratio; 3/n-Bu4NF=1:5.
a Isolated yield.
bDetermined by 1H NMR analysis.
Table 6. Protodesilylation of Z-vinylsilanes 3 with n-Bu4NF
Entry
R
R’
Si
Time (h)
4.0
Yielda (%)
E/Zb
1
2
3
4
Ph
t-Bu
s-Bu
t-Bu
t-Bu
SiMe3
SiMe2Ph
SiMe2Ph
SiMe3
27
68
61
77
100/0
100/0
100/0
100/0
Ph
2.5
Ph
2.5
n-C6H13
3.0
Molar ratio; 3/n-Bu4NF=1:5.
a Isolated yield.
bDetermined by 1H NMR analysis.

Table 7. Reaction of vinylsilanes 3 having a phenyl group with n-Bu4NF
Entry
R
Time (h)
1.0
Total yielda (%)
4/11
E/Z ratio of 4b
52/48
1
2
Me
Ph
62
45
100/0
18/82
2.0
100/0
Molar ratio; 3/n-Bu4NF=1:5.
a Isolated yield.
bDetermined by 1H NMR analysis.

7
Highlights
• Geometrically defined allyl ether derivatives have been
synthesized.
• The silyl group acted as a directing group and a good leaving
group.
•
A
number of synthetic method for a,b-unsaturated
acylsilanes were described.