A new synthesis and stereocontrolled functionalization of substituted silacyclopent-3-enes

Article abstract of DOI:10.1021/jo026774a

C2-Substituted silacyclopent-3-enes have been prepared in good yields in two steps starting from commercially available diallylsilane 9. Coupling between carbanion of 9 and aldehydes or epoxides followed by ring-closing metathesis of the corresponding sub

Full text of DOI:10.1021/jo026774a

A New Syn th esis a n d Ster eocon tr olled F u n ction a liza tion of
Su bstitu ted Sila cyclop en t-3-en es†
Yannick Landais,*,‡ Ce´drick Mahieux,‡ Kurt Schenk,§ and Sheetal S. Surange‡
Laboratoire de Chimie Organique et Organome´tallique, 351, Cours de la Libe´ration,
33405 Talence Cedex, France, and Institut de cristallographie, Universite´ de Lausanne,
BPS Dorigny, CH-1015, Lausanne, Switzerland
y.landais@lcoo.u-bordeaux1.fr
Received November 27, 2002
C2-Substituted silacyclopent-3-enes have been prepared in good yields in two steps starting from
commercially available diallylsilane 9. Coupling between carbanion of 9 and aldehydes or epoxides
followed by ring-closing metathesis of the corresponding substituted diallylsilanes led to various
silacyclopent-3-enes having a â- or a γ-hydroxysilane moiety. Dihydroxylation and epoxidation of
the sila-cycle then led stereoselectively to polyhydroxylated silacyclopentanes. These processes were
shown to occur with opposite topicity, offering a complementary and stereocontrolled access to
diastereomeric polyols having up to five contiguous stereogenic centers.
SCHEME 1
In tr od u ction
Silacyclopent-3-enes 1, widely used as precursors of
polymers 2,1 are attractive synthons which have rarely
been exploited as building blocks in organic synthesis
(Scheme 1).2 Several practical routes have been described
which led to the title compound as well as functionalized
analogues in moderate to good yields.3 For instance,
silylation of dienes such as 3 with dichlorosilanes in the
presence of magnesium is the most straightforward
method to prepare 1 and analogues. Recently, Rieke4
improved and extended the process using activated
magnesium and showed that (2-butene-1,4-diyl)magne-
sium, generated from dienes 3, reacted with dichlorosi-
lanes to afford various polysubstituted silacyclopentenes
(i.e., 4) in good yields. Functionalization of the parent
silacyclopentene 5 through direct alkylation has also been
studied to access C2-substituted silacyclopent-3-enes.
Unfortunately, the preferential attack of the silicon
center by the base used to deprotonate 5 (generally
t-BuLi) led to nucleophilic ring opening and subsequent
polymerization of silacyclopentenes.1,5 Chan et al.,5 how-
ever, found that the presence of electron-rich substituents
(Ar ) p-(t-Bu)Ph) at the silicon center could prevent the
attack of the lithium base on the heteroatom and thus
limit the formation of polymeric material. Unfortunately,
the addition of electrophiles onto the carbanion led to
inseparable mixtures of R and γ isomers 6a ,b with poor
regiocontrol. Therefore, although these methods offer a
straightforward access to various types of silacyclo-
pentenes, the number and nature of substituents allowed
both on the ring and at the silicon center is rather
limited. More generally, we noticed that there was no
reliable methodology allowing the introduction of func-
tionalized chain (possibly having stereogenic centers) in
the R position (C2) relative to silicon.
* To whom correspondence should be addressed. Tel: + 33 5 57 96
22 89. Fax: +33 5 56 84 62 86.
† This paper is dedicated to Prof. Ian Fleming on the occasion of his
retirement.
‡ Laboratoire de Chimie Organique et Organome´tallique.
§ Universite´ de Lausanne.
(1) Brook, M. A. Silicon in Organic, Organometallic and Polymer
Chemistry; J . Wiley & Sons: New York, 2000.
(2) For
a recent functionalization of the parent unsubstituted
silacyclopent-3-ene 1, see: (a) Liu, D.; Kozmin, S. A. Org. Lett. 2002,
4, 3005-3007. (b) Liu, D.; Kozmin, S. A. Angew. Chem., Int. Ed. 2001,
40, 4757-4759.
(3) For a review, see: (a) Hermanns, J .; Schmidt, B. J . Chem. Soc.,
Perkin Trans. 1 1998, 81-102. (b) Hermanns, J .; Schmidt, B. J . Chem.
Soc., Perkin Trans. 1 1998, 2209-2230. (c) Mignani, S.; Damour, D.;
Bastart, J .-P.; Manuel, G. Synth. Commun. 1995, 25, 3855-3862. (d)
Mignani, S.; Barreau, M.; Damour, D.; Renaudon, A.; Dejean, V.;
Manuel, G. Synth. Commun. 1998, 28, 1163-1174. (e) Matsumoto, K.;
Yokoo, T.; Oshima, K.; Utimoto, K.; Abd. Rahman, N. Bull. Chem. Soc.
J pn. 1994, 67, 1694-1700. (f) Manuel, G.; Mazerolles, P.; Lesbre, M.;
Pradel, J .-P. J . Organomet. Chem. 1973, 61, 147-165. (g) Weyenberg,
D. R.; Toporcer, L. H.; Nelson, L. E. J . Org. Chem. 1968, 33, 1975-
1982. (h) Dunogue`s, J .; Arre´guy, B.; Biran, C.; Calas, R.; Pisciotti, F.
J . Organomet. Chem. 1973, 63, 119-131. (i) Manuel, G.; Mazerolles,
P.; Florence, J . C. J . Organomet. Chem. 1971, 30, 5-19. (j) Sudo, T.;
Asao, N.; Yamamoto, Y. J . Org. Chem. 2000, 65, 8919-8923.
(4) Rieke, R. D.; Xiong, H. J . Org. Chem. 1991, 56, 3109-3118.
(5) Horvath, R. F.; Chan, T. H. J . Org. Chem. 1987, 52, 4489-4494
and references therein.
10.1021/jo026774a CCC: $25.00 © 2003 American Chemical Society
Published on Web 03/01/2003
J . Org. Chem. 2003, 68, 2779-2789
2779

Landais et al.
SCHEME 2
We wish to propose here a concise and practical route
to C2-substituted silacylopent-3-enes as well as their
elaboration into polyfunctionalized silacyclopentanes.6
Our strategy is based on the ring-closing metathesis7 of
simple C2-substituted diallylsilanes such as 8 and 11,
available from the parent diallylsilane 9.8 It was antici-
pated from literature precedent that alkylation of 9 would
not be regioselective (R- vs γ-alkylation).9 Therefore, we
turned our attention to the more reliable hydroxyalky-
lation developed by Reetz and Yamamoto,10 based on the
coupling of allyltitanate species with aldehydes. It was
envisioned that this strategy would offer a stereocon-
trolled access to â-hydroxysilanes 8 having two stereo-
genic centers with defined stereochemistry. Moreover, in
the event of an extension of the strategy to enantiopure
series, an access to optically enriched â-hydroxysilanes
would be at hand by simply using chiral nonracemic
aldehydes. In parallel, silacyclopent-3-enes 10 should be
available through ring-closing metathesis of homologous
γ-hydroxysilanes 11. The latter would be accessible by
coupling of the carbanion generated from 9 with mono-
substituted epoxides.11 This approach is known to provide
good regioselectivity in favor of the R-alkylation. As
above, the method should be applicable in enantiopure
series by using optically active epoxides.
SCHEME 3
Finally, synthons 7 and 10, which are cyclic chiral
allylsilanes, should be valuable intermediates for organic
synthesis, providing that they can be functionalized in a
stereocontrolled manner. Surprisingly, although the ster-
eochemistry of electrophilic reactions onto chiral allylsi-
lanes has been intensively studied in the past,12 nothing
has been reported on the stereochemistry of these pro-
cesses applied to C2-substituted silacyclopentenes such
as 7 or 10 (Scheme 2). The functionalization of these
allylsilanes through dihydroxylation and epoxidation will
be described and the stereochemical outcome of these
reactions discussed.
TABLE 1. P r ep a r a tion of a n ti-â-Hyd r oxysila n es 8a -f
(Sch em e 3)
entry
alcohol
dea (%)
yieldb (%)
1
2
3
4
5
6
8a
8b
8c
8d
8e
8f
>98
>98
>98
>98
>98
>98
83
68
78
50
52
60
Resu lts a n d Discu ssion s
Syn th esis of Alcoh ols 8 a n d 11. â-Hydroxysilanes
8 were easily prepared by metalation of 9, followed by
transmetalation with Ti(O-i-Pr)4 and coupling of the
resulting allyltitanate intermediate with suitable alde-
a
b
Estimated from 250 MHz 1H NMR. Yield after purification.
hydes (Scheme 3).10a-b,13 The deprotonation of 9 having
phenyl substituents on the silicon center was found to
be easy and could be carried out at -78 °C.10b We also
noticed that better yields were obtained when transmeta-
lation with Ti(O-i-Pr)4 was carried out during 2 h at -78
°C. This strategy afforded alcohols 8a -d ,f in good yield
after chromatography and in each case as a unique
diastereomer (Table 1). X-ray structure determination of
an advanced intermediate prepared from 8a (vide infra)
eventually showed that these â-hydroxysilanes had the
anti configuration, in good agreement with earlier reports
by Yamamoto.10b By analogy, we assumed that 8b-d ,f
also have the anti configuration. This may be rationalized
invoking a chairlike transition-state model (Figure 1)
where the aldehyde is coordinated to titanium and bulky
SiPh2allyl and R groups occupy pseudoequatorial posi-
tions. Interestingly, when the one-pot protocol was ap-
(6) For a preliminary account, see: Landais, Y.; Surange, S. S.
Tetrahedron Lett. 2001, 42, 581-584.
(7) For recent reviews on olefin metathesis, see: (a) Grubbs, R. H.;
Chang, S. Tetrahedron 1998, 54, 4413-4450. (b) Armstrong, S. K. J .
Chem. Soc., Perkin Trans. 1 1998, 371-388. (c) Schuster, M.; Blechert,
S. Angew. Chem., Int. Ed. Engl. 1997, 36, 2036-2056.
(8) 9 is commercially available. For a synthesis, see: Nasiak, L. D.;
Post, H. W. J . Org. Chem. 1959, 24, 489-492.
(9) (a) Li, L.-H.; Wang, D.; Chan, T. H. Tetrahedron Lett. 1991, 32,
2879-2882. (b) Chan, T. H.; Labrecque, D. Tetrahedron Lett. 1991,
32, 1149-1152. (c) Muchowski, J . M.; Naef, R.; Maddox, M. L.
Tetrahedron Lett. 1985, 26, 5375-5378. (d) Koumaglo, K.; Chan, T.
H. Tetrahedron Lett. 1984, 25, 717-720.
(10) (a) Reetz, M. T.; Wenderoth, B. Tetrahedron Lett. 1982, 23,
5259-5262. (b) Ikeda, Y.; Yamamoto, H. Bull. Chem. Soc. J pn. 1986,
59, 657-658. (c) Hodgson, D. M.; Wells, C. Tetrahedron Lett. 1992,
33, 4761-4762. (d) Shimizu, N.; Shibata, F.; Tsuno, Y. Bull. Chem.
Soc. J pn. 1984, 57, 3017-3018. (e) Sato, F.; Suzuki, Y.; Sato, M.
Tetrahedron Lett. 1982, 23, 4589-4592. (f) Yamamoto, Y.; Saito, Y.;
Maruyama, K. J . Chem. Soc., Chem. Commun. 1982, 1326-1328.
(11) Schaumann, E.; Kirschning, A. Tetrahedron Lett. 1988, 29,
4281-4284.
(12) (a) Fleming, I.; Barbero, A.; Walter, D. Chem. Rev. 1997, 97,
2063-2192. (b) Fleming, I.; Dunogue`s, J .; Smithers, R. Org. React.
1989, 37, 57-575.
(13) Direct coupling of the allyllithium species with aldehydes led
exclusively to the γ-product.
2780 J . Org. Chem., Vol. 68, No. 7, 2003

Synthesis of Substituted Silacyclopent-3-enes
SCHEME 5
F IGURE 1.
SCHEME 4
TABLE 2. P r ep a r a tion of γ-Hyd r oxysila n es 11 a n d 14
(Sch em e 5)
alcohols
R
ratio 11/14a (%)
yieldb (%)
11a , 14a
11b, 14b
11c, 14c
Ph
Me
CH2Ot-Bu
60:40
68:32
64:36
77
70
70
a
b
Estimated from 250 MHz 1H NMR. Overall yield after
purification.
SCHEME 6
plied to chiral racemic phenylpropionaldehyde, â-hydroxy-
silane 8e (entry 5, Table 1) was formed as a single
diastereomer having three stereogenic centers in a syn-
anti relative configuration. The relative stereochemistry
at C1 and C2, determined by X-ray crystallography on
an advanced intermediate (vide infra), is consistent with
an approach of the allyltitanate toward phenylpropional-
dehyde following a Felkin-Anh transition-state model.10a-b
We also considered the preparation of the complemen-
tary syn-â-hydroxysilane series starting from an allylstan-
nane10f instead of an allyltitanate. These are known to
give syn diastereomers with a high level of stereocontrol.10f
Metalation of 9 with n-BuLi followed by reaction of the
resulting carbanion with Bu3SnCl effectively furnished
the required acid-sensitive allylstannane 12 in good yield
(Scheme 4). Unfortunately, all our attempts to couple 12
with an aldehyde in the presence of Lewis acids such as
BF3-OEt2 or Sc(OTf)3 failed. We also investigated the
double functionalization of 9 in order to get access to C2-
C5-disubstituted silacyclopent-3-enes. In our first ap-
proach, we carried out a bis-lithiation of 9, transmeta-
lation with Ti(O-i-Pr)4, and then reaction with isobutyral-
dehyde. Unfortunately, under these conditions, only the
“mono” â-hydroxysilane 8a was obtained in 38% yield. A
second approach was then tested, involving the prepara-
tion of a bis-allylbromide such as 13 which was expected
to couple with the aldehyde via an allylchromium
intermediate.10c Again, only 8a was formed in low yield,
without traces of the expected bis-â-hydroxysilane.
Alcohols 11a -c and 14a -c were prepared through
metalation of 9 with n-BuLi, followed by coupling of the
resulting carbanion with racemic monosubstituted ep-
oxides (Scheme 5).11 This resulted in the formation of the
expected γ-hydroxysilanes as a separable mixture of
diastereomers 11 and 14 with generally poor stereocon-
trol (Table 2). Under these conditions, regiocontrol of the
alkylation was satisfying, since less than 10% of the
γ-isomer was formed which could easily be discarded by
chromatography. The relative configuration of the major
isomer 11b was obtained from X-ray structure determi-
nation of an advanced intermediate (vide infra) and was
found to be syn. Although we did not establish firmly the
relative configuration for the other alcohols, we assumed
by analogy that in each case the major isomer has the
syn configuration.
Rin g-Closin g Meta th esis of Alcoh ols 8 a n d 11-
14. With our diallylsilanes 8, 11, and 14 in hand, we then
investigated their ring-closing metathesis using Grubbs
first-generation catalyst I (Scheme 6).7 Our preliminary
attempts were carried out on the acetate protected
alcohols 15a ,b14 in benzene under reflux.15 The desired
silacyclopent-3-enes 7a ,b were thus obtained in less than
3 h in good yield after purification by chromatography
on silica gel (entries 1 and 2, Table 3).16 We also observed
that alcohol protection was not required since ring-closing
metathesis of 8a ,b and 8d ,e in the presence of catalyst I
led to the free hydroxy silacyclopent-3-enes 7c-f in
excellent yields and high purity (entries 3-6, Table 3).
However, RCM of 8a -e required slightly longer reaction
times than their protected analogues 15a ,b.
Under the same conditions, diallylsilane 8f led to a
cyclized product in which the crotyl methyl group had
(14) Alcohols 8a , 8c, and 8f were easily acetylated using Ac2O and
4-DMAP in CH2Cl2 for 3-18 h at rt to afford 15a -c in 74%, 79%, and
81% yield, respectively.
(15) Much lower yields were obtained when the reaction was carried
out in CH2Cl2 under reflux.
(16) The synthesis of nonsubstituted 1-silacyclopent-3-enes 1 through
RCM using a tungsten catalyst has been reported. Poor to excellent
results (8-90% yield) were obtained depending on the nature of the
substituents at the silicon center. See: (a) Leconte, M.; Pagano, S.;
Mutch, A.; Lefebvre, F.; Basset, J . M. Bull. Soc. Chim. Fr. 1995, 132,
1069-1071. (b) Ahmad, I.; Falck-Pedersen, M. L.; Undheim, K. J .
Organomet. Chem. 2001, 625, 160-172.
J . Org. Chem, Vol. 68, No. 7, 2003 2781

Landais et al.
TABLE 3. Rin g-Closu r e Meta th esis of 8a -e a n d 15a ,b
(Sch em e 6)
SCHEME 8
entry
diene
product
time (h)
yielda (%)
1
2
3
4
5
6
15a
15b
8a
8b
8d
7a
7b
7c
7d
7e
7f
3
3
6
8
6
8
88
95
93
78
75
74
8e
a
Yield after purification.
SCHEME 7
TABLE 5. Dih yd r oxyla tion of Sila cyclop en ten es 7
(Sch em e 9)
TABLE 4. Rin g-Closin g Meta th esis of γ-Hyd r oxysila n es
11a -c a n d 14a -c (Sch em e 8)
entry
allylsilane
diol
trans/cis ratioa
yieldb (%)
entry
diene
product
time (h)
yielda (%)
1
2
3
4
7c
7d
7f
18a
18b
18c
18d
80:20
84:16
79:21
76:24
84
quantc
63c
1
2
3
4
5
6
7
11a
11b
11c
14a
14b
14c
11a
10a
10b
10c
10d
10e
10f
10a
18
16
36
7
30
7
75
77
66
84
78
72
78b
7b
70
Estimated from 1H NMR of the crude reaction mixture. b Yield
a
after purification of the diols. c Crude yield of the diols.
3
the stereochemical outcome of these processes.12 Surpris-
ingly, nothing has been reported on the stereochemistry
of electrophilic reactions of cyclic allylsilanes such as C2-
substituted silacylopent-3-enes (i.e., 7 and 10). Silacy-
clopent-3-enes react like allylsilanes in the presence of
electrophiles, providing addition and SE2′ products.3i
Therefore, one may expect in these processes a transfer
of the chiral information from the C2-allylic stereogenic
center to the prochiral olefin moiety. It may be antici-
pated that in such rigid systems stereofacial differentia-
tion should be governed by the size and nature of the R
group at the allylic stereogenic center (Figure 2). We thus
investigated the epoxidation and dihydroxylation reac-
tions of precursors 7 and 10, which should lead to highly
functionalized polyols systems, valuable intermediates for
organic synthesis.
a
b
Yield after purification. Grubbs catalyst II (1.5 mol %).
disappeared. Extensive NMR studies (COSY, INAD-
EQUATE) finally showed unambiguously that RCM on
8f and 15c led preferentially to the six-membered sila-
cycles 16 and 17, albeit in moderate yield (Scheme 7).17
The ring-closing metathesis was then extended to
γ-hydroxysilanes 11a -c and 14a -c (Table 4, Scheme 8).
As above, cyclization using Grubbs catalyst I gave the
corresponding silacyclopent-3-enes 10a -f in good yields.
However, the reaction was more sluggish than with
â-hydroxysilanes, requiring longer period of reflux and
larger amount of catalyst (4-10 mol % instead of 2 mol
%). Grubbs catalyst II18 led to a slight improvement
leading to completion of the reaction in less than 4 h
(Table 4, entry 7). The slower rate of cyclization, as
compared with â-hydroxysilane analogues, may indicate
that the free hydroxy group coordinates to the ruthenium
carbene and thus slows down the cyclization.19 Relative
configuration of 10b was obtained from X-ray diffraction
study, which also allowed the assignment of the config-
uration of 11b.
E lect r op h ilic F u n ct ion a liza t ion of C2-Su b st i-
tu ted Sila cyclop en t-3-en es. Functionalization of chiral
allylsilanes using electrophilic reagents has been exten-
sively investigated over the last 20 years, and general
trends have emerged, providing reliable models to predict
F IGURE 2.
Our preliminary studies started with the dihydroxy-
lation of precursors 7b-d ,f using modified Sharpless
conditions,20 i.e., quinuclidine as an achiral ligand. In
each case, a pair of diastereomers was formed in high
yield with reasonable diastereoselectivity (Table 5, Scheme
9). Major diols 18b and 18c were found to be poorly
(17) A five-membered ring structure was first proposed in the
preliminary communication.6
(18) Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. Org. Lett. 1999,
1, 953-956.
(19) Furstner, A.; Langemann, K. J . Am. Chem. Soc. 1997, 119,
9130-9136.
(20) Kolb, H. C.; vanNieuwenhze, M. S.; Sharpless, K. B. Chem. Rev.
1994, 94, 2483-2547.
2782 J . Org. Chem., Vol. 68, No. 7, 2003

Synthesis of Substituted Silacyclopent-3-enes
SCHEME 9
SCHEME 11
We also investigated the possibility to access, from 7,
to diastereomeric diols having the complementary C2-
C3-cis stereochemistry (resulting from a syn dihydroxy-
lation relative to the chain at C2), using a method
recently introduced by Donohoe et al.22 Association of a
strongly coordinating solvent such as TMEDA to OsO4
was reported to generate an osmium complex where the
electron density at oxygen was increased. Such a complex
was shown to lead, through hydrogen bonding, to a
reversal of topicity during dihydroxylation of allylic
alcohols. It was effectively shown that the title reagent
gave high syn diastereocontrol as compared to usual
Upjohn conditions, which are known to provide anti
stereoselectivity. Treatment of 7c with a stoechiometric
amount of OsO4 in the presence of TMEDA (1 equiv) led
after hydrolysis (Na2SO3) to the formation of a mixture
of two compounds, which were not the expected diols. 1H
and 13C NMR showed that TMEDA was present in the
structure, which strongly supported the formation of a
diastereomeric mixture of osmates (Scheme 11). 13C
chemical shift for C3 and C4 carbons in the 93-96 ppm
range instead of the expected 72-75 ppm reinforced this
hypothesis. Fortunately, it turned out that 21a ,b gave,
upon recrystallization, suitable crystals for X-ray struc-
ture determination. The structure is that of the syn-
osmate 21a , but the crude reaction mixture was com-
posed of a 55:45 ratio of both diastereomers 21a ,b (as
SCHEME 10
soluble, so they were characterized as their triacetates
19a ,b. The presence of an acetate on the acyclic chain
(i.e., 7b) instead of a hydroxy group had no effect on the
diastereocontrol (entry 4). Changing quinuclidine for
Sharpless chiral ligands did not improve the stereose-
lectivity. Interestingly, most diastereomers could be
isolated by chromatography and were found to be re-
markably stables. X-ray crystallographic studies on the
major diastereomer 18a , issued from the dihydroxylation
of 7c, not only confirmed the anti relative configuration
for the â-hydroxysilane precursor 8a (Scheme 3), but also
indicated that the osmium reagent approached prefer-
entially anti relative to the chain at C2 to afford majori-
tarely the C2-C3-trans product. We assumed that the
dihydroxylation on closely related analogues 7d , 7f, and
7b occurred with the same stereochemistry.
1
measured from H NMR). Forcing hydrolysis conditions
did not allow us to isolate the diols in good yield (<20%),
due to the sensitivity of our silicon precursors toward
hydrolytic medium. However, we have shown that the
use of Donohoe’s conditions may reverse, at least par-
tially, the sense of stereoinduction, leading to larger
amount of the syn diol. The incomplete reversal of
stereoinduction in our case may be attributed to the
occurrence of an homoallylic instead of an allylic hydroxy
group, which is too far remote form the reacting olefin
to direct efficiently the electrophilic reagent onto the syn
face. Isolation of osmates 21a ,b as well as the X-ray
crystallography of 21a is noteworthy and constitutes one
of the few examples of such structures in the literature.23
A solution to the problem of stereocontrolled access to
C2-C3-cis diastereomer eventually emerged when we
Silacyclopentenes 10b and 10e were dihydroxylated
under the same conditions as above to give the desired
diols 20a and 20b (major isomer shown) in good yield
with a diastereomeric ratio similar to those obtained with
silacyclopentenes 7a -f (Scheme 10). The stereochemistry
of the major isomers of 20a and 20b was not determined
since both compounds could not be isolated pure through
chromatography.21 A C2-C3-trans stereochemistry was,
however, assigned by analogy with that of 18a -d .
(21) All attempts to separate the mixture of diastereomers by
chromatography through silica gel led to decomposition.
(22) (a) Donohoe, T. J .; Moore, P. R.; Waring, M. J .; Newcombe, N.
J . Tetrahedron Lett. 1997, 38, 5027-5030. (b) Donohoe, T. J .; Blades,
K.; Moore, P. R.; Waring, M. J .; Winter, J . J . G.; Helliwell, M.;
Newcombe, N. J .; Stemp, G. J . Org. Chem. 2002, 67, 7946-7956. (c)
Donohoe, T. J . Synlett 2002, 331-333.
(23) (a) Corey E. J .; Sarshar, S.; Azimioara, M. D.; Newbold, R. C.;
Noe, M. C. J . Am. Chem. Soc. 1996, 118, 7851-7852. (b) Donohoe, T.
J .; J ohnson, P. D.; Cowley, A.; Keenan, M. J . Am. Chem. Soc. 2002,
124, 12934-12935.
J . Org. Chem, Vol. 68, No. 7, 2003 2783

Landais et al.
TABLE 6. Ep oxid a tion of Sila cyclop en ten es (Sch em e
12)
entry
Allylsilane
diol
cis/trans ratioa
yieldb (%)
1
2
3
4
5
7c
7d
7f
10b
10e
22a
22b
22c
23a
23b
88:12
93:7
90:10
60:40c
65:35c
69
66
66
78
98
a
Estimated from 1H NMR of the crude reaction mixture. b Yield
after purification. c Stereochemistry not determined.
SCHEME 12
F IGURE 3.
TS-A). The substantial amount of C2-C3-cis diols (up
to 20%), resulting from a syn dihydroxylation of precur-
sors 7, may also be indicative of a competitive directing
effect of the acyclic OH group. OsO4-quinuclidine is not
as good an hydrogen acceptor as OsO4-TMEDA but may,
however, hydrogen bond to a certain extent to the
homoallylic OH group, which would lead to the contra-
steric C2-C3-cis product.22b The reversal of topicity with
m-CPBA may be ascribed to the known tendency of this
reagent to give hydrogen bonds with alcohols. This has
been used many times in the stereocontrolled epoxidation
of chiral allylic alcohols and is also operative, although
less efficiently, with homoallylic alcohols.25 It is likely
that in our case the homoallylic alcohol directs the
peracid to the top face, thus providing high level of syn
stereoselectivity through a cyclic transition state model
(Figure 3, TS-B). The low stereocontrol observed during
epoxidation of 10b and 10e may be rationalized by the
γ-position of the hydroxy group (bishomoallylic), which
is too far remote from the double bond to efficiently direct
the peracid on the top face of the olefin. Finally, when
comparing transition state models TS-A and TS-B
(Figure 3) with those proposed for systems having an
“external” silicon group,12 it appears that in sila-cycles,
the exocyclic chain at C2 mainly controls the stereochem-
istry of electrophilic processes, the silicon group having
no major steric influence. Electron-rich σC-Si bonds are
not “conjugated” with the allylic π-orbital and therefore
are not expected to influence to a major extent the double
bond reactivity during these processes.12,26 In turn, the
perpendicular arrangement between the σC-Si and C-O
bonds contributes to the unusual stability of the epoxi-
dation products 22a -c.24 It is worth noting that epoxi-
dation of closely related cyclopent-2-ene methanol with
m-CPBA led to a 4:1 ratio in favor of the cis product, thus
indicating further that in our system the silicon group
has little influence on the stereochemistry of the epoxi-
dation reaction.27
investigated the epoxidation of silacyclopentenes 7b, 7d ,
and 7f. Epoxidation of these allylsilanes in the presence
of m-CPBA led to the desired epoxides 22a -c (major
isomer shown) in good yields with slightly better dia-
stereocontrol than that observed during dihydroxylation
(Table 6, Scheme 12). Interestingly, the diastereomers
could be separated by chromatography over silica gel and
were found to be much more stable than their acyclic
analogues, which tend to open in the presence of trace of
acid.24 This unusual stability may be explained by the
conformation of the cyclic epoxide in which the C-Si bond
is perpendicular to the epoxide C-O bond and thus is
not properly aligned for the Peterson elimination to occur.
This can be observed on X-ray structure of major epoxide
22c, which also demonstrates that the epoxidation of 7f
has occurred syn relative to the chain at C2 and thus
with reversal of topicity as compared with the dihydroxy-
lation. It also confirmed the syn-anti relative configura-
tion of diallylsilane precursor 8e (Scheme 3). The ster-
eochemistry of other epoxides 22a ,b was assigned by
analogy to 22c. Epoxidation of the homologous γ-hydroxy-
silanes 10b and 10e was also performed and was found
to be slower and much less stereoselective (vide infra).
Tr a n sition -Sta te Mod els for Dih yd r oxyla tion a n d
Ep oxid a tion of Sila cyclop en ten es. As mentioned
above, dihydroxylation and epoxidation of C2-substituted
silacyclopent-3-enes 7 and 10 proceed surprisingly with
reversal of topicity. This may be rationalized by invoking
two transition-state models as drawn in Figure 3 (dihy-
droxylation and epoxidation of 7c). For dihydroxylation,
OsO4 would approach anti relative to the sterically
hindered C2-chain from the less crowded face (Figure 3,
(25) Hoveyda, A. H.; Evans, D. A.; Fu, G. C. Chem. Rev. 1993, 93,
1307-1370.
(26) Theoretical studies have shown that in allylsilanes, ground-
state interactions between alkene π-orbital and the coplanar C-Si bond
raises the HOMO of the allylsilane and thus make it more reactive
towards electrophiles, see: Kahn, S. D.; Pau, C. F.; Chamberlin, A. R.;
Hehre, W. J . J . Am. Chem. Soc. 1987, 109, 650-663.
(24) (a) Roush, W. R.; Grover, P. T.; Lin, X. Tetrahedron Lett. 1990,
31, 7563-7566. (b) Roush, W. R.; Grover, P. T. Tetrahedron Lett. 1990,
31, 7567-7570. (c) Roush, W. R.; Grover, P. T. Tetrahedron 1992, 48,
1981-1998. (d) Landais, Y.; Parra-Rapado, L. Tetrahedron Lett. 1996,
37, 1205-1208.
(27) Morizawa, Y.; Nakayama, T.; Matsumura, Y.; Uchida, K.;
Yasuda, A. Bull. Chem. Soc. J pn. 1993, 66, 2714-2719.
2784 J . Org. Chem., Vol. 68, No. 7, 2003

Synthesis of Substituted Silacyclopent-3-enes
(250 MHz, CDCl3): δ 7.64 (m, 5H), 7.4 (m, 5H), 5.84 (m, 2H),
5.0 (m, 4 H), 3.52 (m, 1H), 2.68 (dd, J ) 10, 4 Hz, 1H), 2.28 (d,
J ) 8 Hz, 2H), 1.72 (m, 1H), 1.48 (d, J ) 5 Hz, 1H), 0.92 (d, J
) 5 Hz, 3H), 0.88 (d, J ) 5 Hz, 3H). 13C NMR (63 MHz, CDCl3):
δ 135.7, 134.3, 134.2, 129.5, 127.8, 127.7, 116.3, 114.8, 77.0,
37.0, 32.8, 20.3, 19.0. MS (EI) m/z: 223, 199 (100), 183.1, 145.
Anal. Calcd for C22H28SiO: C, 78.51; H, 8.39. Found: C, 78.55;
H, 8.72.
Con clu sion
In summary, we reported here a stereoselective access
to polyhydroxylated silacyclopent-3-enes in only three
steps, starting from commercially available diallylsilane
9. A careful choice of oxidants, during the functionaliza-
tion of the allylsilane moiety, may be used to access
complementary sets of diastereomeric polyols. Levels of
stereocontrol are generally good and are of preparative
value since diastereomers can be easily isolated in pure
form by a simple chromatography. The structures of
major diastereomers have been determined unambigu-
ously by X-ray diffraction studies, allowing the drawing
of transition state models TS-A and TS-B for dihydroxy-
lation and epoxidation processes. It is also worth noticing
that the strategy can easily be extended to enantiopure
series by using chiral nonracemic aldehydes and epoxides
in the first step. Tartrate-24a-c,28 and pinane-based29
allylboranes might also be used in this context. Further
elaboration through regioselective Peterson elimination30
and/or C-Si bond oxidation2,31 should lead to polyhy-
droxylated skeletons having up to five stereocontrolled
contiguous stereogenic centers. Work along these lines
is now underway and will be reported in due course.
(1R*,2S*)-2-(Allyld ip h en ylsilyl)-1-p h en ylb u t -3-en -1-
ol (8b). Compound 8b was obtained as a colorless oil (68%).
Rf ) 0.52 (petroleum ether-EtOAc 9:1). IR (CHCl3): νmax 3563,
1
1627, 1602, 1453, 1427 cm-1. H NMR (200 MHz, CDCl3): δ
7.6 (m, 5H), 7.4 (m, 5H), 7.28 (m, 5 H), 5.98 (m, 1H), 5.84-5.6
(m, 1H), 5.08-4.78 (m, 5H), 2.71 (dd, J ) 10, 5 Hz, 1H), 2.0
(d, J ) 8 Hz, 2H). 13C NMR (50 MHz, CDCl3): δ 143.8, 135.8,
135.7, 134.3, 134.0, 133.9, 133.5, 129.6, 129.5, 128.1, 127.8,
127.4, 126.3, 117.6, 114.9, 42.3, 20.3. MS (EI) m/z: 223, 199
(100), 183, 145.
(3S*,4R*)-3-(Allyldiph en ylsilyl)h ept-1-en -4-ol (8c). Com-
pound 8c was obtained as an oil (78%). Rf ) 0.51 (petroleum
ether-EtOAc 9:1). IR (CHCl3): νmax 3582, 1627, 1427, 1215,
1109 cm-1 1H NMR (200 MHz, CDCl3): δ 7.6 (m, 4H), 7.36
.
(m, 6H), 5.97-5.62 (m, 2H), 5.12-4.8 (m, 4H), 3.86 (m, 1H),
2.4 (dd, J ) 11, 4 Hz, 1H), 2.2 (dd, J ) 8, 2 Hz, 2H), 1.3 (m,
5H), 0.8 (t, J ) 7 Hz, 3H). 13C NMR (50 MHz, CDCl3): δ 135.7,
134.5, 134.1, 133.9, 129.5, 129.5, 127.8, 127.7, 116.9, 114.8,
39.4, 39.2, 20.4, 19.1, 13.9. MS (EI) m/z: 223, 199 (100), 183,
145. Anal. Calcd for C22H28OSi: C, 78.51; H, 8.39; Si, 8.35.
Found: C, 78.48; H, 8.40; Si, 8.24.
Exp er im en ta l Section
(3R*,4S*)-4-(Allyld ip h en ylsilyl)h ex-5-en -3-ol (8d ). Com-
pound 8d was obtained as a colorless oil (50%). Rf ) 0.53
(petroleum ether-EtOAc 9:1). IR (CHCl3): νmax 3456, 2964,
Gen er a l Rem a r k s. 1H NMR spectra were measured at 200
or 250 MHz. 13C NMR spectra were measured at 50 and 63
MHz using CDCl3 as an internal reference unless otherwise
stated. Low- and high-resolution mass spectra were recorded
using either electronic impact (EI) with an ionization potential
of 70 eV or LSIMS with ionization potential of 35 keV
(matrix: 3-nitrobenzyl alcohol). Elemental analyses were
performed by the service central d’analyze, Vernaison, CNRS,
France. Silica gel 60 (70-200 µm) was used for column
chromatography. All anhydrous and inert atmosphere reac-
tions were performed with oven-dried glass apparatus under
nitrogen atmosphere. THF, ether, benzene, and petroleum
ether were distilled from sodium and benzophenone. CH2Cl2
was distilled from CaH2.
1
1628, 1428, 1258, 1108 cm-1. H NMR (200 MHz, CDCl3): δ
7.56 (m, 4H), 7.38 (m, 6H), 6.02 (dt, J ) 17.4, 10.4 Hz, 1H),
5.89 (dd, J ) 16.9, 10.1 Hz, 1H), 5.09 (m, 4H), 3.88 (m, 1H),
2.60 (dd, J ) 10.5, 3.7 Hz, 1H), 2.35 (d, J ) 7.9 Hz, 2H), 1.73
(d, J ) 4.3 Hz, 1H), 1.57 (m, 2H), 0.95 (t, J ) 7.3 Hz, 3H). 13C
NMR (50 MHz, CDCl3): δ 135.8, 134.6, 134.4, 134.3, 134.1,
129.7, 129.6, 128.0, 127.9, 117.0, 115.0, 72.8, 39.0, 30.1, 20.6,
10.6. MS (EI) m/z: 223, 199 (100), 183, 145.
(2S*,3R*,4S*)-4-(Allyld ip h en ylsilyl)-2-p h en ylh ex-5-en -
3-ol (8e). Compound 8e was obtained as an oil (52%). Rf )
0.51 (petroleum ether-EtOAc 9:1). IR (CHCl3): νmax 3581,
1
1626, 1493, 1427, 1217 cm-1. H NMR (250 MHz, CDCl3): δ
Gen er a l P r oced u r e for th e P r ep a r a tion of â-Hyd r oxy-
sila n e 8a -f fr om 9. (3R*,4S*)-4-(Allyld ip h en ylsilyl)-2-
m eth ylh ex-5-en -3-ol (8a ). To a stirred solution of diallyl-
diphenylsilane 9 (528 mg, 2.0 mmol) in dry THF (5.0 mL) was
added dropwise at 0 °C a 2.5 M solution of n-BuLi in hexane
(0.8 mL, 2.0 mmol) under a nitrogen atmosphere. The resulting
deep yellow solution was stirred for 1 h at 0 °C and then cooled
to -78 °C. Ti(O-i-Pr)4 (0.59 mL, 2.0 mmol) was added and the
reaction mixture stirred for 1 h at -78 °C. Freshly distilled
isobutyraldehyde (0.18 mL, 2.0 mmol) in dry THF (2.0 mL)
was then added dropwise at -78 °C, and stirring was
continued for 2 h at -78 °C. The reaction mixture was then
quenched with aq NH4Cl and allowed to warm to rt. The
organic layer was decanted and the aqueous layer extracted
with ether. The combined extracts were washed with brine
and dried (MgSO4), and the solvents were concentrated in
vacuo. The crude product was purified by chromatography
through silica gel (petroleum ether-EtOAc 95:5) giving 8a as
an oil (558 mg, 83%). Rf ) 0.46 (petroleum ether-EtOAc 9:1).
7.6 (m, 2H), 7.4 (m, 11H), 7.1 (m, 2H), 6.0 (m, 1H), 5.67 (m,
1H), 5.18 (dd, J ) 8, 2 Hz, 1H), 4.85 (m, 3H), 4.0 (m, 1H), 2.9
(m, 1H), 2.32 (dd, J ) 10.7, 1.6 Hz, 1H), 2.2 (m, 2H), 1.5 (d, J
) 4.9 Hz, 1H, exchangeable with D2O), 1.25 (d, J ) 7 Hz, 3H).
13C NMR (63 MHz, CDCl3): δ 144.7, 135.7, 135.6, 133.9, 133.8,
133.6, 129.7, 129.5, 128.4, 128.0, 127.7, 126.5, 117.5, 114.8,
75.9, 45.0, 36.3, 20.2, 18.7. MS (EI) m/z: 376, 352, 319, 251,
223 (100).
(E)-(3S*,4R*)-3-(Allyld ip h en ylsilyl)h ep t a -1,5-d ien -4-
ol (8f). Compound 8f was obtained as an oil (60%). Rf ) 0.42
(petroleum ether-EtAOc 6:4). IR (CHCl3): νmax 3582, 1627,
1
1589, 1519, 1487, 1428, 1378, 1215 cm-1. H NMR (250 MHz,
CDCl3): δ 7.6 (m, 4H), 7.4 (m, 6H), 6.0-5.65 (m, 2H), 5.48 (m,
2H), 5.18-4.84 (m, 4H), 4.28 (t, J ) 6 Hz, 1H), 2.5 (dd, J )
10, 6 Hz, 1H), 2.21 (d, J ) 8 Hz, 2H), 1.75 (br s, 1H), 1.56 (d,
J ) 5 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 135.7, 135.2,
134.0, 133.5, 129.5, 129.4, 127.7, 127.6, 127.4, 117.4, 114.9,
72.5, 40.9, 20.7, 17.5. MS (EI) m/z: 223, 199 (100), 183, 145.
Anal. Calcd for C22H26OSi: C, 78.99; H, 7.83. Found: C, 78.79;
H, 7.95.
1
IR (CHCl3): νmax 3417, 1625, 1427, 1216, 1109 cm-1. H NMR
Gen er a l P r oced u r e for th e P r ep a r a tion of γ-Hyd r oxy-
sila n es 11a -c a n d 14a -c fr om 9. (1R*,3S*)-3-(Allyld ip h e-
n ylsilyl)-1-p h en ylp en t-4-en -1-ol (11a ) a n d (1R*,3R*)-3-
(Allyld ip h en ylsilyl)-1-p h en ylp en t-4-en -1-ol (14a ). To a
solution of diallydiphenylsilane 9 (2.64 g, 10 mmol) in anhy-
drous THF (30 mL) was added dropwise under stirring at 0
°C a 1.6 M solution of n-BuLi in hexane (7.5 mL, 12 mmol).
The orange solution was maintained at this temperature under
(28) Roush, W. R.; Walts, A. E.; Hoong, L. K. J . Am. Chem. Soc.
1985, 107, 8186-8190.
(29) (a) Ramachandran, P. V. Aldrichim. Acta 2002, 35, 23-35. (b)
Barrett, A. G. M.; Malecha, J . W. J . Org. Chem. 1991, 56, 5243-5245.
(30) Ager, D. J . Org. React. 1990, 38, 1-223.
(31) (a) Fleming, I. Chemtracts: Organic Chemistry 1996, 1-64. (b)
Landais, Y.; J ones, G. Tetrahedron 1996, 52, 7599-7662. (c) Tamao,
K. Advances in Silicon Chemistry; J AI Press, Inc.: Greenwich, CT,
1996; Vol. 3, p 1.
J . Org. Chem, Vol. 68, No. 7, 2003 2785

Landais et al.
rapid stirring during 1 h. The reaction mixture was then cooled
to -78 °C, and styrene oxide (1.32 g, 11 mmol) was added
dropwise. The reaction mixture was allowed to warm to -40
°C, and stirring was continued for 3 h at this temperature.
The reaction mixture was then quenched with an aq NH4Cl
solution, and the organic layer was decanted. The aqueous
layer was extracted with ether, the combined extracts were
washed with brine and dried over MgSO4, and the solvents
were evaporated in vacuo. The crude residue was purified by
flash chromatography through silica gel (petroleum ether-
EtOAc 9:1), affording the corresponding γ-hydroxysilane as a
separable 60:40 mixture of two diastereoisomers 11a (major)
(1.91 g, 50%) and 14a (minor) (1.04 g, 27%) as pale yellow oils.
11a . Rf ) 0.22 (petroleum ether-EtOAc 9:1). IR (CHCl3): νmax
127.7, 115.2, 114.9, 73.1, 70.5, 66.3, 33.4, 29.1, 28.7, 19.9. MS
(LSIMS, Na) m/z: 417 [M + Na]+ (19), 376 [M - H2O]+ (6),
297 (34), 241 (25), 223 [Si(CH2CHdCH2)Ph2]+ (100), 219 (44).
HRMS: calcd for C25H34O2SiNa [M + Na]+ 417.222579, found
417.222716. 14c. Rf ) 0.42 (petroleum ether-EtOAc 9:1). IR
(CHCl3): νmax 3452, 2974, 1628, 1491, 1427, 1248, 1111 cm-1
.
1H NMR (250 MHz, CDCl3): δ 7.63 (m, 4H), 7.42 (m, 6H), 5.79
(m, 2H), 5.01 (m, 2H), 1.20 (s, 9H), 4.88 (m, 2H), 3.80 (m, 1H),
3.17 (dd, J ) 8.6, 3 Hz, 1H), 3.14 (t, J ) 8.6 Hz, 1H), 2.85 (t,
J ) 10.3 Hz, 1H), 2.72 (br s, 1H), 2.18 (d, J ) 7.9 Hz, 2H),
1.78 (m, 1H), 1.40 (m, 1H). 13C NMR (63 MHz, CDCl3): δ 138.3,
135.7, 135.6, 134.3, 133.6, 133.5, 133.4, 129.7, 129.40, 129.38,
127.75, 127.70, 127.67, 114.8, 114.7, 72.9, 68.7, 66.5, 32.1, 27.5,
26.7, 19.7. MS (LSIMS, Na) m/z: 417 [M + Na]+ (11), 376 [M
- H2O]+, 297 (34), 241 (37), 223 [Si(CH2CHdCH2)Ph2]+ (59),
199 [(Ph)2SiOH]+ (100). HRMS: calcd for C25H34O2SiNa [M +
Na]+ 417.222579, found 417.222681.
Gen er a l P r oced u r e for Acetyla tion of â-Hyd r oxysi-
la n es 8a , 8c, a n d 8f. Acetic Acid (1R*,2S*)-2-(Allyld ip h e-
n ylsilyl)-1-isop r op ylbu t-3-en yl Ester (15a ). To a stirred
solution of 8a (400 mg, 1.2 mmol) in dry CH2Cl2 (5.0 mL) were
added acetic anhydride (0.22 mL, 2.4 mmol), NEt3 (0.33 mL,
2.4 mmol), and a catalytic amount of 4-DMAP. The resulting
mixture was then stirred at rt under nitrogen for 18 h and
was treated with saturated aq NaHCO3 solution. The organic
layer was decanted and the aqueous layer extracted with ether.
The combined extracts were washed with brine and dried over
MgSO4, and the solvents were concentrated in vacuo. The
crude product was purified by chromatography through silica
gel (petroleum ether-EtOAc 95:5) affording 15a as a thick oil
(336 mg, 74%). IR (CHCl3): νmax 1722, 1627, 1487, 1428, 1372,
1241, 1216 cm-1. 1H NMR (200 MHz, CDCl3): δ 7.4 (m, 10 H),
6.04-5.6 (m, 2H), 5.6-4.82 (m, 5H), 2.68 (dd, J ) 11, 2 Hz,
1H), 2.19 (m, 2H), 1.84 (m, 1H), 1.36 (s, 3H), 0.86 (d, J ) 6.6
Hz, 3H), 0.75 (d, J ) 6.6 Hz, 3H). 13C NMR (50 MHz, CDCl3):
δ 135.7, 135.5, 134.0, 133.6, 133.41, 129.5, 129.3, 127.7, 127.6,
116.6, 115.1, 76.5, 34.7, 31.7, 20.4, 20.1, 18.8. MS (EI) m/z:
241 (100), 223, 199, 183, 105, 74, 59.
1
3574, 2920, 1628, 1492, 1428, 1260 cm-1. H NMR (250 MHz,
CDCl3): δ 7.58-7.33 (m, 15H), 5.88 (m, 2H), 5.06 (m, 4H), 4.88
(m, 1H), 2.80 (m, 1H), 2.11 (d, J ) 7.8 Hz, 2H), 1.96 (m, 1H),
1.68 (m, 1H). 13C NMR (63 MHz, CDCl3): δ 143.6, 138.7, 135.6,
135.5, 134.1, 133.4, 133.0, 129.6, 128.6, 127.9, 127.7, 126.6,
125.4, 124.4, 114.9, 114.7, 74.6, 37.8, 28.4, 19.4. MS (LSIMS,
Na) m/z: 407 [M + Na]+ (13), 376 (11), 367, 325, 224 (22), 223
[Si(CH2CHdCH2)Ph2]+ (100), 221. HRMS: calcd for C26H28
-
OSiNa [M + Na]+ 407.180714, found 407.179970. 14a . Rf )
0.35 (petroleum ether-EtOAc 9:1). IR (CHCl3): νmax 3444,
1
2971, 1627, 1492, 1454, 1262, 1110 cm-1. H NMR (250 MHz,
CDCl3): δ 7.53-7.25 (m, 15H), 5.75 (m, 2H), 5.06 (m, 4H), 4.72
(m, 1H), 2.80 (m, 1H), 2.11 (d, J ) 7.9 Hz, 2H), 1.96 (m, 1H),
1.68 (m, 1H). 13C NMR (63 MHz, CDCl3): δ 145.1, 138.2, 135.6,
135.5, 134.3, 134.2, 133.5, 129.9, 19.40, 129.37, 128.3, 127.8,
127.6, 127.2, 125.5, 114.9, 114.7, 72.0, 38.1, 27.5, 19.5. MS
(LSIMS, Na) m/z: 407 [M + Na]+ (32), 376, 367 [M - OH.]+,
•
325 [367 - CH2dCHCH2 ]+, 305, 237, 224 (22), 223 [Si(CH2-
CHdCH2)Ph2]+ (100), 221. HRMS: calcd for C26H28OSiNa [M
+ Na]+ 407.180714, found 407.179510. Anal. Calcd for C26H28
-
OSi: C, 81.20; H, 7.34; Si, 7.30. Found: C, 81.11; H, 7.29; Si,
7.00.
(2S*,4S*)-4-(Allyld ip h en ylsilyl)h ex-5-en -2-ol (11b) a n d
(2S*,4R*)-4-(Allyld ip h en ylsilyl)h ex-5-en -2-ol (14b). Com-
pounds 11b (49%), and 14b (21%) were obtained as pale yellow
oils. 11b. Rf ) 0.31 (petroleum ether-EtOAc 9:1). IR (CHCl3):
Gen er a l P r oced u r e for Rin g-Closin g Meta th esis of â-
a n d γ-H yd r oxysila n es. Acet ic Acid (1R*,2S*)-1-(1,1-
Dip h en yl-2,5-d ih yd r o-1H-silol-2-yl)-2-m eth ylp r op yl Es-
ter (7a ). To a stirred solution of acetate 15a (292 mg, 0.77
mmol) in dry benzene (7.0 mL) was added Grubbs catalyst I
(2 mol %, 12.7 mg, 0.015 mmol) under nitrogen. The black
reaction mixture was refluxed until consumption of 15a .
Reaction was found to be complete after 3.0 h under reflux.
After completion, benzene was removed in vacuo, and the
residue was purified by chromatography through silica gel
(petroleum ether-EtOAc 95:5) giving 7a as a colorless oil (240
mg, 88%). Rf ) 0.48 (petroleum ether-EtOAc 9:1). IR
νmax 3582, 2969, 1628, 1428, 1261, 1110 cm-1 1H NMR (250
.
MHz, CDCl3): δ 7.41-7.37 (m, 10H), 5.76 (m, 2H), 4.96 (m,
4H), 3.89 (m, 1H), 2.39 (m, 1H), 2.20 (d, J ) 7.9 Hz, 2H), 1.69
(m, 2H), 1.17 (d, J ) 6.1 Hz, 3H). 13C NMR (63 MHz, CDCl3):
δ 139.4, 139.0, 136.0, 135.9, 135.7, 134.5, 133.9, 133.7, 133.5,
130.01, 130.00, 129.8, 124.2, 115.3, 114.7, 69.1, 38.5, 30.0, 22.7,
19.9, 22.7. MS (LSIMS, Na) m/z: 345 [M + Na]+ (3), 281 [M -
CH2dCHCH2 ]+ (5), 223 [Si(CH2CHdCH2)Ph2]+ (57), 199
•
[(Ph)2SiOH]+ (100), 181 (20), 163 (19), 145 (35). HRMS: calcd
for C21H26OSiNa [M + Na]+ 345.165064, found 345.164245.
14b. Rf ) 0.44 (petroleum ether-EtOAc 9:1). IR (CHCl3): νmax
(CHCl3): νmax 1726, 1611, 1486, 1428, 1370, 1251 cm-1 1H
.
1
3583, 2969, 1628, 1487, 1428, 1262, 1110 cm-1. H NMR (250
NMR (250 MHz, CDCl3): δ 7.65 (m, 2H), 7.53 (m, 2H), 7.4 (m,
6H), 6.15 (m, 1H), 5.86 (m, 1H), 4.9 (dd, J ) 10, 3 Hz, 1H),
2.68 (m, 1H), 2.1-1.98 (m, 1H), 1.94 (s, 3H), 1.88-1.77 (m,
1H), 1.61 (m, 1H), 0.88 (d, J ) 7 Hz, 3H), 0.61 (d, J ) 7 Hz,
3H). 13C NMR (63 MHz, CDCl3): δ 135.3, 134.5, 134.3, 133.0,
132.6, 131.6, 129.9, 129.8, 128.2, 128.1, 78.9, 31.9, 30.5, 20.8,
20.1, 17.3, 16.1. MS (EI) m/z: 290, 241 (100), 199, 181, 105,
43.
MHz, CDCl3): δ 7.53-7.35 (m, 10H), 5.71 (m, 2H), 4.95 (m,
4H), 3.85 (m, 1H), 2.68 (m, 1H), 2.14 (d, J ) 7.9 Hz, 2H), 1.65
(m, 2H), 1.16 (d, J ) 6.1 Hz, 3H). 13C NMR (63 MHz, CDCl3):
δ 139.5, 138.8, 136.0, 135.9, 134.0, 133.9, 133.8, 133.5, 130.0,
129.9, 128.2, 128.1, 115.3, 115.0, 69.2, 38.2, 30.1, 22.7, 20.0.
MS (LSIMS, Na) m/z: 345 [M + Na]+ (6), 281 (7), 239 (5), 224
(12), 223 [SiPh2(CH2CHdCH2)]+ (53), 199 [(Ph)2SiOH]+ (100),
183 (47), 163 (17), 145 (20). HRMS: calcd for C21H26OSiNa
[M + Na]+ 345.165064, found 345.164374.
Acetic Acid (1R*,2S*)-1-(1,1-Dip h en yl-2,5-d ih yd r o-1H-
silol-2-yl)-2-bu tyl Ester (7b). Compound 7b was obtained
as a colorless oil (95%). Rf ) 0.46 (petroleum ether-EtOAc
(2R*,4S*)-4-(Allyld ip h en ylsilyl)-1-ter t-bu toxyh ex-5-en -
2-ol (11c) a n d (2R*,4R*)-4-(Allyld ip h en yl-silyl)-1-ter t-
bu toxyh ex-5-en -2-ol (14c). Compounds 11c (58%) and 14c
(12%) were obtained as pale yellow oils. 11c. Rf ) 0.32
(petroleum ether-EtOAc 9:1). IR (CHCl3): νmax 3449, 2973,
9:1). IR (CHCl3): νmax 1610, 1589, 1428, 1373, 1242, 1215 cm-1
.
1H NMR (250 MHz, CDCl3): δ 7.7-7.35 (m, 10H), 6.17 (m,
1H), 5.91 (m, 1H), 4.97 (td, J ) 9, 4 Hz, 1H), 2.6 (m, 1H), 2.14-
2.0 (m, 1H), 1.94 (s, 3H), 1.91-1.78 (m, 1H), 1.6-0.9 (m, 6H),
0.6 (t, J ) 7 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 170.8,
135.3, 135.0, 134.57, 133.4, 132.6, 131.9, 129.9, 129.9, 128.2,
128.1, 75.5, 36.9, 35.6, 21.1, 18.7, 17.4, 13.4. MS (LSIMS, Na)
m/z: 291, 243, 242, 241 (100), 235, 228. Anal. Calcd for
C22H26O2Si: C, 75.42; H, 7.42; Si, 8.0. Found: C, 75.30; H, 7.49;
Si, 8.30.
1
1957, 1629, 1486, 1428, 1258, 1111 cm-1. H NMR (250 MHz,
CDCl3): δ 7.57 (m, 4H), 7.37 (m, 6H), 5.85 (m, 2H), 5.02 (m,
2H), 4.91 (m, 2H), 3.77 (br s, 1H), 3.41 (dd, J ) 8.6, 3.0 Hz,
1H), 3.27 (m, 1H), 2.37 (m, 1H), 2.18 (d, J ) 7.9 Hz, 2H), 1.65
(m, 2H), 1.22 (s, 9H, CH3). 13C NMR (63 MHz, CDCl3): δ 136.0,
135.7, 134.4, 130.9, 129.8, 128.2, 124.1, 129.7, 129.40, 129.38,
2786 J . Org. Chem., Vol. 68, No. 7, 2003

Synthesis of Substituted Silacyclopent-3-enes
(1R*)-1-((2S*)-1,1-Dip h en yl-2,5-d ih yd r o-1H-silol-2-yl)-
2-m eth ylp r op a n -2-ol (7c). Compound 7c was obtained as a
brown oil (93%). Rf ) 0.41 (petroleum ether-EtOAc 9:1). IR
(CHCl3): νmax 3582, 1606, 1486, 1428, 1386, 1366, 1259, 1216
- OH•]+ (90), 319 (41), 277 (34), 261 (64), 235 (100), 223 [Si-
(CH2-CHdCH2)Ph2]+ (57), 221 (56). HRMS: calcd for C24H24
OSiNa [M + Na]+ 379.149414, found 379.150497.
-
P r ep a r a tion of 10a Usin g Gr u bbs Ca ta lyst II. γ-Hy-
droxysilane 11a (402 mg, 1.1 mmol) was subjected to the
standard ring-closing metathesis conditions described above
(1.5 mol % of Grubbs catalyst II was used) to afford after
purification by column chromatography through silica gel
(petroleum ether-EtOAc 98:2) 10a as a colorless oil (290 mg,
78%). All spectoscopic data were in good agreement with those
of the material obtained during ring-closure metathesis of 11a
with Grubbs catalyst I.
1
cm-1. H NMR (250 MHz, CDCl3): δ 7.6 (m, 4H), 7.4 (m, 6H),
6.3 (m, 1H), 6.1 (m, 1H), 3.35 (t, J ) 5.8 Hz, 1H), 2.59 (m,
1H), 2.1 (m, 1H), 2.1 (m, 1H), 1.7 (m, 2H), 1.33 (br s, 1 H),
0.91 (d, J ) 6.4 Hz, 3H), 0.82 (d, J ) 6.7 Hz, 3H). 13C NMR
(63 MHz, CDCl3): δ 135.5, 134.8, 133.6, 131.9, 129.8, 129.7,
128.1, 128.0, 77.6, 34.9, 33.2, 20.1, 17.7, 16.7. MS (EI) m/z:
279, 263, 245, 199, 181, 158, 139, 105, 77.
(R*)-((2S*)-1,1-Dip h en yl-2,5-d ih yd r o-1H-silol-2-yl)p h e-
n ylm eth a n ol (7d ). Compound 7d was obtained as a brown
oil (78%). Rf ) 0.55 (petroleum ether-EtOAc 8:2). IR (CHCl3):
(2S*,4S*)-1-(1,1-Dip h en yl-2,5-d ih yd r o-1H-silol-2-yl)p r o-
p a n -2-ol (10b). γ-Hydroxysilane 11b (601 mg, 1.86 mmol) was
subjected to the standard ring-closing metathesis conditions
described above (4 mol % of Grubbs catalyst I was used) to
afford after purification by column chromatography through
silica gel (petroleum ether-EtOAc 98:2) 10b as white crystals
(421 mg, 77%). Mp: 143-146 °C (petroleum ether-ether). Rf
) 0.66 (petroleum ether-EtOAc 8:2). IR (CHCl3): νmax 3576,
1
νmax 3440, 1606, 1428, 1397, 1306, 1216, 1114 cm-1. H NMR
(250 MHz, CDCl3): δ 7.36 (m, 13H), 7.06 (m, 2H), 6.32 (m,
1H), 6.2 (m, 1H), 4.76 (d, J ) 10 Hz, 1H), 2.8 (m, 1H), 2.16-
1.8 (m, 3H). 13C NMR (63 MHz, CDCl3): δ 144.5, 135.4, 134.9,
134.4, 133.9, 132.9, 132.8, 129.8, 129.6, 128.2, 127.9, 127.4,
126.3, 74.8, 40.3, 17.2. MS (EI) m/z: 342 [M]+, 288, 236, 199
(100), 181, 158, 128, 105, 77. HRMS: calcd for C23H22OSi
342.143994, found 342.144162. Anal. Calcd for C23H22SiO: C,
80.70; H, 6.43. Found: C, 80.46; H, 6.43.
1
2976, 1609, 1492, 1428, 1262, 1114 cm-1. H NMR (250 MHz,
CDCl3): δ 7.57-7.35 (m, 10H), 5.98 (m, 2H), 3.66 (q, J ) 6.1
Hz, 1H), 2.44 (m, 1H), 1.85 (m, 2H), 1.45 (m, 2H), 1.01 (d, J )
6.1 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 137.3, 136.7, 135.7,
135.5, 130.4, 130.1, 130.0, 128.4, 128.3, 68.2, 40.8, 26.8, 24.2,
17.3. MS (LSIMS, Na) m/z: 317 [M + Na]+ (55), 293 [M -
H•]+ (20), 277 [M - OH•]+ (39), 259 (20), 249 (25), 235 (59),
(1R*)-1-((2S*)-1,1-Dip h en yl-2,5-d ih yd r o-1H-silol-2-yl)-
p r op a n -1-ol (7e). Compound 7e was obtained as a brown oil
(75%). Rf ) 0.41 (petroleum ether-EtOAc 9:1). IR (CDCl3):
1
νmax 3583, 1626, 1428, 1397, 1306, 1216, 1108 cm-1. H NMR
(250 MHz, CDCl3): δ 7.62-7.43 (m, 10H), 6.26 (m, 2H), 3.79
(m, 1H), 2.36 (m, 1H), 2.21 (m, 2H), 1.48 (m, 2H), 1.73 (t, J )
7.3 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 136.3, 135.1, 134.8,
134.7, 132.9, 130.6, 129.7, 129.6, 129.3, 74.2, 33.1, 21.0, 11.0.
MS (LSIMS, Na) m/z: 317 [M + Na]+ (28), 277 [M - OH•]+
(100), 235 [M - CH3CH2CHOH•]+ (39), 215 (20). HRMS: calcd
for C19H22OSiNa 317.133764, found 317.133875.
223 [Si(CH2-CHdCH2)Ph2]+ (100). HRMS: calcd for C19H22
OSiNa [M + Na]+ 317.133764, found 317.133270.
-
(2R*,4S*)-1-ter t-Bu t oxy-3-(1,1-d ip h en yl-2,5-d ih yd r o-
1H-silol-2-yl)p r op a n -2-ol (10c). γ-Hydroxysilane 11c (307
mg, 0.78 mmol) was subjected to the standard ring-closing
metathesis conditions described above (8 mol % of Grubbs
catalyst I was used) to afford after purification by column
chromatography through silica gel (petroleum ether-EtOAc
98:2) 10c as a colorless oil (178 mg, 66%). Rf ) 0.32 (petroleum
ether-EtOAc 9:1). IR (CHCl3): νmax 3413, 2925, 1610, 1489,
(2S*,3R*)-((2S*)-1,1-Dip h en yl-2,5-d ih yd r o-1H -silol-2-
yl)-2-p h en ylp r op a n -1-ol (7f). Compound 7f was obtained as
a brown oil (74%). Rf ) 0.68 (petroleum ether-EtOAc 8:2). IR
(CHCl3): νmax 3405, 1713, 1597, 1493, 1428, 1378, 1217, 1114
1
1428, 1365, 1259, 1114 cm-1. H NMR (250 MHz, CDCl3): δ
1
cm-1. H NMR (250 MHz, CDCl3): δ 7.8 (m, 2H), 7.7 (m, 2H),
7.74 (m, 4H), 7.40 (m, 6H), 6.02 (m, 2H), 3.57 (m, 1H), (m,
1H), 3.02 (dd, J ) 8.6, 3.0 Hz, 1H), 2.97 (t, J ) 8.6 Hz, 1H),
2.53 (m, 2H), 2.53 (br s, 1H), 1.92 (m, 2H), 1.12 (s, 9H). 13C
NMR (63 MHz, CDCl3): δ 137.3, 135.24, 135.19, 134.1, 129.7,
129.6, 129.5, 128.0, 127.7, 73.0, 70.9, 65.7, 34.7, 27.5, 26.2, 17.1.
MS (LSIMS, Na) m/z: 389 [M + Na]+ (93), 319 (58), 259 (39),
241 (45), 233 (75), 223 [Si(CH2CHdCH2)Ph2]+ (100), 219 (47),
215 (61). HRMS: calcd for C23H30O2SiNa [M + Na]+ 389.191279,
found 389.191764.
7.53 (m, 6H), 7.4 (m, 3H), 7.0 (m, 2H), 6.4 (m, 1H), 6.28 (m,
1H), 3.9 (t, J ) 5.8 Hz, 1H), 2.93 (m, 1H), 2.61 (m, 1H), 2.27-
2.15 (m, 1H), 1.98-1.86 (m, 1H), 1.7 (br s, 1H), 1.45 (d, J )
7.4 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 145.1, 135.4, 134.8,
133.8, 133.1, 132.2, 129.9, 129.6, 128.4, 128.2, 128.0, 127.4,
126.2, 76.8, 44.7, 34.4, 16.9, 15.7. MS (EI) m/z: 370 [M]+, 265,
237, 199, 128, 105 (100), 91, 77. HRMS: calcd for C25H26OSi
370.175294, found 370.176618. Anal. Calcd for C25H26OSi: C,
81.08; H, 7.02; Si, 7.56. Found: C, 81.19; H, 6.95; Si, 7.11.
(1R*,3R*)-2-(1,1-Dip h en yl-2,5-d ih yd r o-1H-silol-2-yl)-1-
p h en yleth a n -1-ol (10d ). γ-Hydroxysilane 14a (839 mg, 2.2
mmol) was subjected to the standard ring-closing metathesis
conditions described above (4 mol % of Grubbs catalyst I was
used) to afford after purification by column chromatography
through silica gel (petroleum ether-EtOAc 98:2) 10d as a
colorless oil (661 mg, 84%). Rf ) 0.29 (petroleum ether-EtOAc
9:1). IR (CHCl3): νmax 3575, 2925, 1616, 1493, 1428, 1390, 1262,
1112 cm-1. 1H NMR (250 MHz, CDCl3): δ 7.61-7.18 (m, 15H),
6.06 (m, 2H), 4.67 (dd, J ) 8.85, 4.9 Hz, 1H), 2.42 (m, 1H),
1.89 (d, J ) 7.8 Hz, 2H), 1.66 (m, 2H). 13C NMR (63 MHz,
CDCl3): δ 145.3, 136.6, 135.8, 135.5, 135.4, 134.2, 130.7, 130.1,
130.0, 128.8, 128.3, 127.8, 126.3, 74.5, 41.2, 26.7, 17.3. MS
(LSIMS, Na) m/z: 379 [M + Na]+ (21), 339 [M - OH•]+ (74),
319 (49), 277 (23), 261 (64), 235 (100), 223 [Si(CH2CHdCH2)-
Ph2]+ (38), 221 (48). HRMS: calcd for C24H24OSiNa [M + Na]+
379.149414, found 379.149391.
(2S*,4R*)-1-(1,1-Dip h en yl-2,5-d ih yd r o-1H -silol-2-yl)-
p r op a n -2-ol (10e). γ-Hydroxysilane 14b (640 mg, 1.98 mmol)
was subjected to the standard ring-closing metathesis condi-
tions described above (8 mol % of Grubbs catalyst I was used)
to afford after purification by column chromatography through
silica gel (petroleum ether-EtOAc 98:2) 10e as a colorless oil
(452 mg, 78%). Rf ) 0.56 (petroleum ether-EtOAc 8:2). IR
(CHCl3): νmax 3582, 2921, 1606, 1486, 1428, 1373, 1261, 1113
(2R*,3S*)-1,1-Dip h en yl-2-vin yl-1,2,3,6-tetr a h yd r -silin -
3-ol (16). Compound 16 was obtained as a yellow gum (57%).
Rf ) 0.46 (petroleum ether-EtOAc 9:1). IR (CHCl3): νmax 3383,
1694, 1628, 1590 cm-1 1H NMR (250 MHz, CDCl3): δ 7.8-
.
7.3 (m, 10H), 6.0 (m, 1H), 5.87-5.64 (m, 2H), 5.1 (m, 2H), 4.37
(d, J ) 10.4 Hz, 1H), 2.47 (t, J ) 10.4 Hz, 1H), 1.85 (m, 2H).
13C NMR (63 MHz, CDCl3): δ 136.1, 135.5, 135.0, 134.4, 133.6,
129.9, 128.0, 127.97, 127.86, 127.80, 125.6, 117.0, 70.0, 39.9,
11.3. MS (LSIMS, Na) m/z: 292 [M]+, 291, 275, 259, 222, 215,
213.
(1R*,3S*)-2-(1,1-Dip h en yl-2,5-d ih yd r o-1H-silol-2-yl)-1-
p h en yleth a n -1-ol (10a ). γ-Hydroxysilane 11a (216 mg, 5.62
mmol) was subjected to the standard ring-closing metathesis
conditions described above (10 mol % of Grubbs catalyst I was
used) to afford after purification by column chromatography
through silica gel (petroleum ether-EtOAc 98:2) 10a as a
colorless oil (130 mg, 75%). Rf ) 0.27 (petroleum ether-EtOAc
9:1). IR (CHCl3): νmax 3582, 3396, 2976, 1609, 1492, 1428, 1262,
1114 cm-1. 1H NMR (250 MHz, CDCl3): δ 7.73-7.20 (m, 15H),
6.00 (m, 2H), 4.48 (m, 1H), 2.55 (m, 1H), 2.00 (m, 1H), 1.89 (d,
J ) 7.8 Hz, 2H), 1.66 (m, 1H). 13C NMR (63 MHz, CDCl3): δ
145.1, 137.0, 135.4, 135.3, 134.8, 134.5, 130.1, 129.7, 128.3,
128.1, 128.0, 127.3, 125.3, 74.5, 41.3, 26.6, 17.3. MS (LSIMS,
Na) m/z: 379 [M + Na]+ (35), 352 [379 - OH•]+ (25), 339 [M
J . Org. Chem, Vol. 68, No. 7, 2003 2787

Landais et al.
cm-1. 1H NMR (250 MHz, CDCl3): δ 7.67-7.35 (m, 10H), 6.05
(m, 2H), 3.81 (m, 1H), 2.36 (m, 1H), 1.92 (m, 2H), 1.48 (m,
2H), 1.12 (d, J ) 6.1 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ
136.3, 135.5, 134.6, 130.6, 129.6, 129.0, 128.2, 127.9, 68.0, 41.4,
26.3, 23.2, 17.1. MS (LSIMS, Na) m/z: 317 [M + Na]+ (23),
293 [M - H•]+ (15), 277 [M - OH•]+ (41), 259 (35), 249 (26),
235 (71), 223 [Si(CH2CHdCH2)Ph2]+ (100). Anal. Calcd for
corresponding triols 18b as a 84:16 mixture of two diastere-
omers (Rf ) 0.50 and 0.25, petroleum ether-EtOAc 4:6) (1.36
g, quantitative yield), which were directly acetylated without
further purification. To a stirred solution of the above crude
triol 18b (1.33 g, 3.53 mmol) in dry CH2Cl2 (9.0 mL) were
added acetic anhydride (1.67 mL, 17.65 mmol), Et3N (2.47 mL,
17.6 mmol), and a catalytic amount of 4-DMAP. The resulting
reaction mixture was stirred at rt under nitrogen for 3 h and
then treated with a saturated aq NaHCO3 solution. The
dichloromethane layer was separated, and the aqueous layer
was extracted with ether. The combined extracts were washed
with brine and dried over MgSO4, and the solvents were
concentrated in vacuo to afford the two diastereomers of 19a
as a white solid (1.55 g, 83%). Major triacetate of 19a
crystallized out from EtOH. Mp: 184-186 °C (EtOH). Rf ) 0.50
(petroleum ether-EtOAc 3:7). IR (CHCl3): νmax 1736, 1588,
C
19H22OSi: C, 77.50; H, 7.53; Si, 9.54. Found: C, 77.27; H,
7.54; Si, 9.80.
(2R*,4R*)-1-ter t-Bu t oxy-3-(1,1-d ip h en yl-2,5-d ih yd r o-
1H -silol-2-yl)p r op a n -2-ol (10f). γ-Hydroxysilane 14c (138
mg, 0.35 mmol) was subjected to the standard ring-closing
metathesis conditions described above (4 mol % of Grubbs
catalyst I was used) to afford after purification by column
chromatography through silica gel (petroleum ether-EtOAc
98:2) 10f as a colorless oil (93 mg, 72%). Rf ) 0.36 (petroleum
ether-EtOAc 9:1). IR (CHCl3): νmax 3569, 2973, 1605, 1486,
1
1495, 1428, 1373 cm-1. H NMR (250 MHz, CDCl3): δ 7.52-
1
1428, 1364, 1257, 1114 cm-1. H NMR (250 MHz, CDCl3): δ
7.08 (m, 13H), 6.87 (br d, J ) 7.1 Hz, 2H), 5.94 (d, J ) 9.8 Hz,
1H), 5.68-5.53 (m, 2H), 2.74 (t, J ) 9.8 Hz, 1H), 1.98 (s, 3H),
1.84 (s, 3 H), 1.82 (s, 3H), 1.61 (t, J ) 3.9 Hz, 2H). 13C NMR
(50 MHz, CDCl3): δ 170.1, 169.7, 139.7, 135.4, 134.6, 131.8,
130.2, 129.7, 128.1, 128.0, 127.8, 127.7, 127.1, 77.6, 76.2, 74.9,
34.6, 21.0, 20.9, 20.8, 15.5. MS (EI) m/z: 382, 365, 305, 241
(100), 223, 199, 181, 160. Anal. Calcd for C29H30O6Si: C, 69.30;
H, 6.02; Si, 5.59. Found: C, 69.10; H, 6.04; Si, 5.80.
Acetic Acid (2R*,3S*,4R*)-4-Acetoxy-2-((1R*,2S*)-1-a ce-
toxy-2-ph en ylpr opyl)-1,1-diph en ylsilolan -3-yl Ester (19b).
Following the general protocol, triol 18c was obtained as a 79:
21 mixture of two diastereomers (Rf ) 0.51 and 0.27, petroleum
ether-EtOAc 4:6) (63%), which were directly acetylated to
afford acetate 19b as a white solid (85%). The major triacetate
of 19b crystallized from EtOH. 19b: Rf ) 0.42 (petroleum
ether-EtOAc 7:3). Mp: 157-158 °C (EtOH). IR (CHCl3): νmax
3424, 3019, 1736, 1640, 1428, 1373 cm-1. 1H NMR (CDCl3): δ
7.63-7.36 (m, 10H), 7.18-7.11 (m, 3H), 6.71-6.63 (m, 2H),
5.68-5.61 (m, 1H), 5.41 (dd, J ) 8.8, 2.7 Hz, 1H), 5.26 (dd, J
) 8.2, 4.9 Hz, 1H), 2.9-2.77 (m, 1H), 2.44 (t, J ) 8.5 Hz, 1H),
2.03 (s, 3H), 1.83 (s, 3H), 1.79 (s, 3H), 1.68-1.42 (m, 2H), 1.23
(d, J ) 7.3 Hz, 3H). 13C NMR (50 MHz, CDCl3): δ 170.1, 170.0,
169.7, 143.5, 135.7, 134.7, 131.6, 130.4, 129.9, 128.5, 128.1,
128.0, 127.4, 126.4, 77.8, 76.3, 74.5, 43.0, 30.2, 21.0, 20.8, 20.7,
15.6, 14.6. MS (EI) m/z: 425, 365, 323, 263, 241 (100), 223,
199, 181. Anal. Calcd for C31H34O6Si: C, 70.16; H, 6.46; Si,
5.29. Found: C, 70.01; H, 6.48; Si, 5.60.
7.69 (m, 2H), 7.53 (m, 2H), 7.38 (m, 6H), 6.09 (br s, 2H), 3.80
(m, 1H), 3.27 (dd, J ) 8.6, 3.0 Hz, 1H), 3.07 (t, J ) 8.6 Hz,
1H), 2.58 (m, 2H), 2.50 (br s, 1H), 1.93 (m, 2H), 1.16 (s, 9H).
13C NMR (63 MHz, CDCl3): δ 136.8, 135.8, 135.5, 134.5, 130.5,
130.0, 128.8, 128.4, 128.3, 73.5, 70.5, 66.9, 35.2, 28.0, 25.4, 17.2.
MS (LSIMS, Na) m/z: 389 [M + Na]+ (22), 335 (8), 319 (7),
241 (10), 233 (31), 215 (14), 199 [(Ph)2SiOH]+ (100), 183 (21),
165 (13), 154 (22), 139 (45). HRMS: calcd for C23H30O2SiNa
[M + Na]+ 389.191279, found 389.190882.
Gen er a l P r oced u r e for th e Dih yd r oxyla tion of Sila -
cyclop en t -3-en es. (2R*,3S*,4R*)-2-((1R*)-1-H yd r oxy-2-
m eth ylp r op yl)-1,1-d ip h en ylsilola n e-3,4-d iol (18a ). To the
dihydroxylation mixture prepared by mixing K3Fe(CN)6 (306
mg, 0.93 mmol), K2CO3 (129 mg, 0.93 mmol), quinuclidine (0.32
mg, 0.0029 mmol), and K2OsO4‚2H2O (1.06 mg, 0.0029 mmol)
in a 1:1 solution of t-BuOH and water (2.0 mL) was added after
5 min methanesulfonamide (20.0 mg, 0.21 mmol). The result-
ing orange solution was cooled to 0 °C, and then silacyclopen-
tene 7c (67 mg, 0.21 mmol) in t-BuOH (1.0 mL) was added at
0 °C. Water (1.0 mL) was added to maintain the 1:1 ratio with
t-BuOH, and the reaction mixture was slowly allowed to warm
to rt under stirring. After completion of the reaction (1 h, TLC),
the mixture was cooled to 0 °C, quenched carefully with sodium
sulfite (312 mg), and then stirred for 0.75 h. The aqueous layer
was extracted several times with EtOAc. The combined
extracts were washed by brine and dried over anhydrous
MgSO4, and the solvents were concentrated in vacuo to give a
solid residue. Triol 18a was obtained as a 80:20 mixture of
two diastereomers, which were separated by column chroma-
tography through silica gel (petroleum ether-EtOAc 98:2) (91
mg, 84%). 18a (major). Rf ) 0.54 (petroleum ether-EtOAc 4:6).
Mp: 172-174 °C (CH2Cl2-petroleum ether). IR (CHCl3): νmax
Acetic Acid (1R*)-1-((2S*,3S*,4R*)-3,4-Dih yd r oxy-1,1-
d ih yd r oxy-1,1-d ip h en ylsilola n -2-yl)bu tyl Ester (18d ). Fol-
lowing the general protocol, triol 18d was isolated as a 76:24
mixture of two diastereomers (70%). 18d (major). Rf ) 0.35
(petroleum ether-EtOAc 1:1). Mp: 129-132 °C (EtOH). IR
(CHCl3): νmax 3528, 1729, 1589, 1428, 1374, 1215, 1112 cm-1
.
1
3438, 1601, 1520, 1428, 1215, 1151, 1111 cm-1. H NMR (200
1H NMR (250 MHz, CDCl3): δ 7.7 (m, 2H), 7.4 (m, 8H), 5.15
(m, 1H), 4.45 (m, 1H), 4.2 (m, 1H), 2.62 (d, J ) 3.1 Hz, 1H),
2.46 (br s, 1H), 2.14 (dd, J ) 11.3, 9.5 Hz, 1H), 2.03 (s, 3H),
1.55-0.84 (m, 6H), 0.5 (t, J ) 7.3 Hz, 3H). 13C NMR (CDCl3):
δ 171.0, 135.4, 135.1, 134.0, 133.8, 133.0, 130.1, 129.9, 128.3,
128.2, 79.9, 76.1, 74.2, 37.5, 35.9, 21.5, 18.2, 17.8, 13.1. MS
(EI) m/z: 241, 225, 199 (100), 181. Anal. Calcd for C22H28O4-
Si: C, 68.75; H, 7.29. Found: C, 68.66; H, 7.34. 18d (minor).
Rf ) 0.44 (petroleum ether-EtOAc 1:1). IR (CHCl3): νmax 3462,
MHz, CDCl3): δ 7.7 (m, 2H), 7.4 (m, 8H), 4.48 (m, 1H), 4.36
(br s, 1H), 4.22 (dd, J ) 10, 3 Hz, 1H), 3.74 (d, J ) 12 Hz, 1H),
2.69 (br s, 1H), 2.09 (t, J ) 10 Hz, 1H), 1.6 (m, 1H), 1.4 (m,
2H), 0.75 (d, J ) 7 Hz, 3H), 0.65 (d, J ) 7 Hz, 3H). 13C NMR
(50 MHz, acetone-d6): δ 136.2, 136.1, 130.4, 130.4, 128.8, 128.7,
82.2, 78.4, 74.0, 46.0, 34.3, 21.1, 18.6, 14.8. MS (EI) m/z: 299,
237, 199 (100), 181, 165, 139, 105, 77. Anal. Calcd for C20H26O3-
Si C, 70.17; H, 7.60. Found: C, 70.15; H, 7.63. 18a (minor). Rf
) 0.14 (petroleum ether-EtOAc 4:6). IR (CHCl3): νmax 3331,
1
3018, 1701, 1428, 1260, 1145, 1116 cm-1. H NMR (250 MHz,
1
1428, 1323, 1215 cm-1. H NMR (200 MHz, CDCl3): δ 7.6 (m,
CDCl3): δ 7.7 (m, 4H), 7.5 (m, 3H), 7.4 (m, 3H), 5.06 (m, 1H),
4.26 (br s, 1H), 4.09-3.95 (m, 2H), 2.63 (br s, 1H), 2.11 (s, 3H),
1.83 (dd, J ) 11.3, 2.7 Hz, 1H), 1.75-1.5 (m, 2H), 1.4-0.9 (m,
4H), 0.49 (t, J ) 7 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 135.7,
134.9, 134.1, 133.9, 132.1, 129.7, 129.6, 127.8, 127.7, 74.7, 74.0,
73.9, 39.1, 36.7, 20.8, 19.9, 18.6, 12.5.
Dih yd r oxyla tion of Sila cyclop en ten e 7c w ith OsO4-
TMEDA. Osm a tes 21a ,b. To a solution of 7c (109 mg, 0.35
mmol) and TMEDA (59 µL, 0.39 mmol) in anhydrous CH2Cl2,
precooled at -78 °C, was added a 1.97 M solution of OsO4 (0.19
mL, 0.37 mmol) in anhydrous CH2Cl2. The solution turned
deep red and then black. The solution was stirred until
4H), 7.38 (m, 6H), 4.5 (t, J ) 4 Hz, 1H), 4.1 (m, 1H), 3.8 (dd,
J ) 8, 3 Hz, 1H), 3.23 (br s, 1H), 2.3 (br s, 1H), 1.82 (dd, J )
8, 3 Hz, 1H), 1.6 (m, 3H), 0.85 (d, J ) 8 Hz, 3H), 0.7 (d, J )
6.4 Hz, 3H). 13C NMR (50 MHz, acetone-d6): δ 137.1, 137.0,
136.0, 135.5, 130.5, 130.4, 129.2, 128.6, 77.1, 75.7, 72.7, 39.8,
33.9, 22.0, 20.6. MS (EI) m/z: 299, 237, 225, 199 (100), 181,
139, 105.
Acet ic Acid (2R*,3S*,4R*)-4-Acet oxy-2-((R*)-a cet oxy-
p h en ylm eth yl)-1,1-d ip h en ylsilola n -3-yl Ester (19a ). Fol-
lowing the general protocol reported above for 7c, silacyclo-
pentene 7d (1.27 g, 3.71 mmol) afforded after 48 h the
2788 J . Org. Chem., Vol. 68, No. 7, 2003

Synthesis of Substituted Silacyclopent-3-enes
complete consumption of starting material (1.5 h; TLC analy-
sis). Sodium sulfite (600 mg, 12 equiv) was then added and
the stirring maintained for 0.75 h. The solution was then
filtered and washed with a 10% NaOH solution. The aqueous
layer was extracted with EtOAc, and the combined extracts
were poured into brine, dried over MgSO4, and the solvent
removed under reduced pressure to afford the osmate complex
as a 55:45 mixture of diastereomers 21a and 21b. Rf ) 0.54
(petroleum ether-EtOAc 3:7) for both diastereomers. Mp:
191-193 °C (ether-EtOAc). IR (CDCl3) νmax 3414, 2929, 2253,
(1R*)-1-((2R*,3R*,4S*)-3,3-Diph en yl-6-oxa-3-silabicyclo-
[3.1.0]h ex-2-yl)p h en ylm eth a n ol (22b). Following the gen-
eral epoxidation procedure, 22b was obtained as a 93:7 mixture
of two diastereomers (66%). 22b (major). Rf ) 0.25 (petroleum
ether-EtOAc 8:2). Mp: 156-158 °C (i-PrOH). IR (CHCl3): νmax
3422, 1588, 1491, 1454, 1428 cm-1 1H NMR (250 MHz,
.
CDCl3): δ 7.45-7.1 (m, 10H), 6.88-6.76 (m, 5H), 4.85 (d, J )
10.8 Hz, 1H), 4.0-3.92 (m, 1H), 3.78-3.7 (m, 1H), 2.8 (br s,
1H), 2.43 (dd, J ) 10.8, 1.95 Hz, 1H), 1.93-1.54 (m, 2H). 13C
NMR (50 MHz, CDCl3): δ 143.7, 135.4, 129.7, 129.3, 128.2,
128.0, 127.7, 127.0, 125.4, 72.5, 58.6, 58.3, 35.7, 14.3. MS (EI)
m/z: 278, 251, 224, 198 (100), 183, 138. 22b (minor). Rf ) 0.25
(petroleum ether-EtOAc 8:2). IR (CHCl3): νmax 3430, 3069,
1588, 1427, 1379 cm-1. 1H NMR (CDCl3): δ 7.6-7.2 (m, 15H),
4.9 (d, J ) 4.7 Hz, 1H), 3.72 (br s, 1H), 3.57 (d, J ) 2.7 Hz,
1H), 2.5 (d, J ) 4.7 Hz, 1H), 1.9-1.6 (m, 3H). 13C NMR (50
MHz, CDCl3): δ 143.8, 136.6, 134.6, 133.6, 129.7, 129.6, 129.3,
128.2, 127.9, 127.6, 127.5, 126.8, 73.8, 59.7, 56.9, 39.6, 16.2.
MS (EI) m/z: 314, 237, 225, 199 (100), 183, 165, 13. Anal. Calcd
for C23H22O2Si: C, 77.05; H, 6.19; Si, 7.83. Found: C, 76.98;
H, 6.25; Si, 7.75.
1
1794, 1474, 1428, 1383, 1110 cm-1. 21a . H NMR (250 MHz,
CDCl3): δ 7.75-7.19 (m, 10H), 5.16 (t, J ) 4 Hz, 1H), 4.40
(dd, J ) 10, 4.3 Hz, 1H), 4.30 (br s, 1H), 3.86 (m, 1H), 3.60-
3.35 (m, 4H), 3.30-3.10 (s, 12H), 2.88 (m, 1H), 2.37 (m, 1H),
1.95-1.85 (m, 1H), 1.68-1.52 (m, 1H), 0.79 (d, J ) 6.41 Hz,
3H), 0.65 (d, J ) 6.41 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ
136.6, 135.9, 135.8, 135.4, 135.3, 134.9, 133.9, 131.0, 129.6,
129.4, 129.3, 129.1, 128.1, 127.7, 127.3, 97.6, 96.7, 93.3, 92.1,
77.9, 77.7, 77.1, 76.6, 76.3, 64.8, 64.7, 64.2, 52.1, 51.9, 51.7,
51.5, 51.4, 34.1, 33.9, 33.7, 33.6, 20.9, 20.7, 17.8, 17.1, 16.6,
14.6. 21b. 1H NMR (250 MHz, CDCl3): δ 7.75-7.19 (m, 10H),
5.11 (m, 1H), 4.40 (m, 1H), 3.92 (br s, 1H), 3.60-3.35 (m, 4H),
3.30-3.10 (s, 12H), 2.06 (m, 1H), 1.95-1.85 (m, 1H), 1.68-
1.52 (m, 2H), 0.97 (d, J ) 6.71 Hz, 3H), 0.85 (d, J ) 6.71 Hz,
3H).
(1R*,2S*)-1-((2R*,3R*,4S*)-3,3-Dip h en yl-6-oxa -3-sila -
bicyclo[3.1.0]h ex-2-yl)-2-p h en ylp r op a n -1-ol (22c). Follow-
ing the general epoxidation procedure, 22c was obtained as a
90:10 mixture of two diastereomers (66%). 22c (major). Rf )
0.48 (petroleum ether-EtOAc 8:2). Mp: 158-159 °C (i-PrOH).
Gen er a l P r oced u r e for E p oxid a t ion of Sila cyclo-
p en t en es. (1R*)-1-((2R*,3R*,4S*)-3,3-Dip h en yl-6-oxa -3-
sila bicyclo[3.1.0]h ex-2-yl)-2-m eth ylp r op a n -1-ol (22a ). To
a stirred solution of silacyclopentene 7c (1.54 g, 5.0 mmol) in
dry CH2Cl2 (15.0 mL) under nitrogen was added m-CPBA (2.58
g, 15.0 mmol) at 0 °C. The reaction was slowly allowed to warm
to rt, stirred for 2 h, and treated with saturated aq Na2CO3.
The organic layer was decanted, and the aqueous layers were
extracted with EtOAc. The combined extracts were washed
with brine and dried over MgSO4, and the solvents were
concentrated in vacuo to afford 22a as a 88:12 mixture of two
diastereomers, which were separated by chromatography
through silica gel (petroleum ether-EtOAc 8:2) (1.12 g, 69%).
22a (major). Rf ) 0.32 (petroleum ether-EtOAc 8:2). IR
1
IR (CHCl3): νmax 3425, 3018, 1428, 1215, 1140, 1110 cm-1. H
NMR (250 MHz, CDCl3): δ 7.73-7.58 (m, 4H), 7.51-7.37 (m,
6H), 7.17-7.1 (m, 3H), 6.62-6.54 (m, 2H), 3.99-3.88 (m, 1H),
3.82-3.75 (m, 1H), 3.71-3.64 (m, 1H), 2.83-2.69 (m, 1H), 2.32
(dd, J ) 5.9, 2.2 Hz, 1H), 1.91 (br d, J ) 16 Hz, 1H), 1.71 (d,
J ) 3.95 Hz, 1H), 1.53 (dd, J ) 16, 2.2 Hz, 1H), 1.34 (d, J )
6.9 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 136.5, 134.8, 129.8,
128.2, 128.1, 128.0, 127.2, 126.1, 60.0, 56.7, 43.6, 33.2, 16.6,
12.2. MS (EI) m/z: 281, 263, 237, 225, 199 (100), 181, 155,
143. Anal. Calcd for C25H26O2Si: C, 77.68; H, 6.78; Si, 7.27.
Found: C, 77.48; H, 6.89; Si, 7.45.
Ack n ow led gm en t. This work was supported by the
Ministe`re de la Recherche et de la Technologie through
a PhD grant to C.M. and a postdoctoral fellowship to
S.S.S. Y.L. gratefully acknowledges the Institut Uni-
versitaire de France, CNRS, and Re´gion Aquitaine for
financial support and Dr. F. Robert for helpful sugges-
tions.
(CHCl3): νmax 3448, 2964, 1428, 1383, 1186, 1110 cm-1 1H
.
NMR (250 MHz, CDCl3): δ 7.6 (m, 4H), 7.4 (m, 6H), 3.79-
3.61 (m, 2H), 2.29 (dd, J ) 10.4, 2.1 Hz, 1H), 1.98-1.67 (m,
2H), 1.62-1.44 (m, 2H), 0.91 (d, J ) 7.0 Hz, 3H, CH3), 0.66
(d, J ) 6.7 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 136.2, 135.0,
129.8, 129.7, 128.2, 123.7, 74.9, 59.6, 57.0, 34.4, 32.9, 20.7, 16.6,
14.8. MS (LSIMS, Na) m/z: 347 [M + Na]+ (100), 319, 308,
307, 281, 259, 229, 225. 22a (minor). Rf ) 0.34 (petroleum
ether-EtOAc 8:2). IR (CHCl3): νmax 2965, 1600, 1524, 1472,
Su p p or tin g In for m a tion Ava ila ble: Preparation and
characterization for compounds 12, 13, 15b,c, 17, 20a ,b, and
1
23a ,b. H and 13C NMR spectra for compounds 7a ,c-d , 8a -
1
1428, 1112 cm-1. H NMR (250 MHz, CDCl3): δ 7.6 (m, 4H),
e, 10b,e, 11a -c, 12, 13, 14a -c, 15a ,b, 16, 19b, 20a , 21a , and
22c. X-ray crystallographic data for compounds 10b, 18a , 21a ,
and 22c. This material is available free of charge via the
Internet at http://pubs.acs.org.
7.4 (m, 6H), 3.71 (s, 2H), 3.33 (m, 1H), 2.32 (d, J ) 3.7 Hz,
1H), 1.9-1.66 (m, 3H), 1.3 (br s, 1H), 0.91 (d, J ) 2.4 Hz, 3H),
0.88 (d, J ) 2.15 Hz, 3H). 13C NMR (63 MHz, CDCl3): δ 135.51,
135.46, 129.9, 129.4, 128.2, 127.6, 76.5, 58.5, 32.6, 31.2, 19.7,
18.8, 14.4.
J O026774A
J . Org. Chem, Vol. 68, No. 7, 2003 2789