An efficient synthesis of cyclopropyl silyl ketones

Article abstract of DOI:10.1016/j.tet.2011.10.013

The reaction of silylcyclopropyl bromides with dichloromethyl methyl ether in the presence of n-butyllithium is investigated. Under basic reaction conditions, the corresponding cyclopropylidene derivatives are exclusively obtained. The resulting cyclopropylidene compounds are subjected to protonolysis or trapping with electrophiles in a one-pot to give the cyclopropyl silyl ketone derivatives in good yields. Acidic treatment of derived cyclopropyl silyl ketone allows isomerization to give the thermodynamically favorable trans form exclusively.

Full text of DOI:10.1016/j.tet.2011.10.013

Tetrahedron 67 (2011) 9500e9508
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
An efficient synthesis of cyclopropyl silyl ketones
*
Mitsunori Honda , Kenta Nakae, Toshiaki Nishizawa, Mitsuhiro Suda, Ko-Ki Kunimoto, Masahito Segi
Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 31 August 2011
Received in revised form 3 October 2011
Accepted 5 October 2011
Available online 12 October 2011
The reaction of silylcyclopropyl bromides with dichloromethyl methyl ether in the presence of n-bu-
tyllithium is investigated. Under basic reaction conditions, the corresponding cyclopropylidene de-
rivatives are exclusively obtained. The resulting cyclopropylidene compounds are subjected to
protonolysis or trapping with electrophiles in a one-pot to give the cyclopropyl silyl ketone derivatives in
good yields. Acidic treatment of derived cyclopropyl silyl ketone allows isomerization to give the ther-
modynamically favorable trans form exclusively.
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
Furthermore, we aimed to apply our procedure to synthesis of 1-
substituted cyclopropyl silyl ketones. In a preceding letter we de-
Acylsilanes have received considerable attention due to their
unusual spectroscopic properties, novel chemical reactivity, and
their utility as useful synthons in organic synthesis.1,2 In particular
cyclopropyl silyl ketones have attracted attention as useful syn-
thetic intermediates, because three specific reaction sites, cyclo-
propyl group, silyl group, and carbonyl group are present in one
molecule.3 Therefore we have become interested in exploring the
chemistry of cyclopropyl silyl ketones. For example, we have pre-
viously described a route to cyclopropyl silyl ketones 2 via three
steps beginning with simple alkenes,4 and then reported that the
efficient synthesis of silyl-substituted dihydrofurans,5 silyl enol
scribed the preliminary results that are improvement of reaction
conditions to allow the significant increase of yield of desired
cyclopropyl silyl ketones and the formation of cyclopropylidene
derivatives, which are precursors of cyclopropyl silyl ketones.9
Herein, we wish to describe the preparation of silylcyclopropyl
bromide having various substituents as starting materials, further
attempt to improve the yield of cyclopropyl silyl ketones, the ste-
reochemistry of cyclopropylidene derivatives and cyclopropyl silyl
ketones that has not been assigned, and new detailed evidence that
ethers or
b
-ketosilanes6 and the stereoselective synthesis of Z-
homoallyl derivatives7 using specific reaction sites of cyclopropyl
silyl ketones (Scheme 1). Our synthetic method is convenient and
gives many kinds of cyclopropyl silyl ketones having various sub-
stituents on 2- or 3-position of cyclopropane ring, therefore that
procedure has been extensively used.2a,3b However, the low yield
was a huge drawback for our procedure. The isolated yield of
cyclopropyl silyl ketones 2 was less than 30%8 and more than an
equivalent amount of the protonated compounds 3 was obtained as
a by-product (Scheme 1). To make things worse, our route is not
applicable to the synthesis of cyclopropyl silyl ketones possessing
a substituent on the 1-position of cyclopropane ring. There have
already been just a few reports on the preparation of cyclopropyl
silyl ketones,3 the synthesis of 1-substituted cyclopropyl silyl ke-
tones in particular is less well-known. For these reason, we decided
to investigate the reaction conditions to enhance the yield of
cyclopropyl silyl ketones and to clarify the mechanism, even
though an ambiguous pathway has been previously proposed.4
Scheme 1. Synthesis and reactions of cyclopropyl silyl ketones.
* Corresponding author. E-mail address: honda@se.kanazawa-u.ac.jp (M. Honda).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.10.013

M. Honda et al. / Tetrahedron 67 (2011) 9500e9508
9501
supports our mechanistic consideration. Additionally, the isomer-
ization of cyclopropyl silyl ketone 2, that makes possible the ster-
eoselective synthesis of 2, was clarified. As a result reasonable
yields of cyclopropyl silyl ketones 2 possessing various substituents
on cyclopropane ring that contains 1-substituted derivatives were
achieved.
reactions under the various conditions were carried out. Then the
reaction using 3 equiv of n-butyllithium was examined. Neverthe-
less the reaction mixture became quite complex and the trace
amount of 4a was obtained (entry 2). The reaction quenched with
methanol at ambient temperature also gives the complex mixture
(entry 3). It is noteworthy that the quenching of the reaction with
water afforded 4a in moderate yield. This result suggests that the
methoxy group of 4a was derived from DCME and not from
methanol. On the other hand, the reaction using tert-butyllithium
as a base instead of n-butyllithium gave the desired cyclo-
propylidene derivatives 4a in low yield (entry 4). The reactions with
different order of addition of reagents, for instance the addition of
n-butyllithium to the THF solution of silylcyclopropyl bromide 1a
and DCME, did not afford 4a at all. In these cases the corresponding
silylcyclopropane 3a was often yielded exclusively. Stereochemical
assignment of the cyclopropylidene product 4a was confirmed by
the NOE measurements. When 4a was formed, complete E-selec-
tivity was observed. The structures of E and Z isomers of 4a were
optimized at the DFT-B3LYP level with a 6-31Gþ basis set from the
Gaussian 09 suite,12 as a result, it became clear that E isomer was
23.3 kcal/mol stable than Z isomer.
2. Results and discussion
2.1. Preparation of silylcyclopropyl bromides
The preparation of silylcyclopropyl bromides was accomplished
as follows. The treatment of simple alkenes with dibromocarbene
generated from the reaction of bromoform with t-BuOK gave the
corresponding dibromocyclopropanes.10 The resulting dibromocy-
clopropane derivatives were treated with n-butyllithium and the
subsequent reaction with chlorosilanes gave the desired silylcy-
clopropyl bromides 1 (Table 1).11 Although the products 1aec, 1g,
and 1h were yielded as a diastereomeric mixture in each case, these
mixtures were used as starting materials without separation of the
diastereomers.
Table 1
Preparation of silylcyclopropyl bromides
Entry
1
SiCI
Products
Yielda (%)
73
Entry
5
SiCI
Products
Yielda (%)
80
Me3SiCl
Me3SiCI
2
3
Me2PhSiCI
Et3SiCI
52
87
6
7
Me2PhSiCI
Me3SiCI
74
60
4
Me3SiCI
85
8
Me3SiCI
80
a
Isolated yield.
2.2. Optimization of reaction conditions for synthesis of
cyclopropyl silyl ketones
The reaction of other 1-silylcyclopropyl bromides 1 having dif-
ferent groups on the cyclopropane ring or silicon atom was carried
out. These results are shown in Table 3. These reactions also pro-
ceeded smoothly to furnish the corresponding cyclopropylidene
derivatives 4 in good yields, regardless of the kind of the sub-
stituents. As previously indicated, of the two possible di-
astereomeric products, E-isomers were selectively obtained
(entries 1e3 and 8). The reaction of 1a with butyl dichloromethyl
ether instead of DCME afforded the corresponding cyclo-
propylidene derivative 4i in moderate yield (entry 8). This result
also provided the evidence that the methoxy groups in 4aeh were
derived from DCME and not from methanol as a quenching reagent.
When an equimolar mixture of 1f and 1h were treated with n-
buthyllithium and DCME, the corresponding cyclopropylidene de-
rivatives 4f and 4h were obtained with no crossover products
(Scheme 2). Thus the reaction involves the intramolecular 1,2-silyl
migration from carbon to carbon.
The treatment of 2-phenyl-1-trimethylsilylcyclopropyl bromide
1a with base gave the corresponding carbanion. The following re-
action with dichloromethyl methyl ether (DCME) was carried out
and quenched with methanol or hydrous THF. The reaction pro-
ceeded to afford the corresponding cyclopropylidene derivative 4a
and in all cases cyclopropyl silyl ketone 2a and silylcyclopropane 3a
as mentioned above were not yielded at all. The results are sum-
marized in Table 2. In accordance with the previous study,9
2.5 equiv of n-butyllithium was used to lithiate the cyclopropyl
bromide at ꢀ90 ꢁC and then 1.2 equiv of DCME was added to the
reaction mixture and quenched with methanol at that temperature
(entry 1). In this case, the cyclopropylidene derivative 4a was
afforded in good yield. 4a is synthetic equivalent to desired cyclo-
propyl silyl ketone 2a.9 Therefore, to improve the yield of 4a, the

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M. Honda et al. / Tetrahedron 67 (2011) 9500e9508
Table 2
Optimization of reaction conditions
Entry
n-BuLib
Quenching reagent
Temp (ꢁC)
Yielda (%)
1
2
3
4
5
n-BuLi (2.5)
n-BuLi (3.0)
n-BuLi (2.5)
n-BuLi (2.5)
t-BuLi (2.5)
MeOH
MeOH
MeOH
H2O/THF
MeOH
ꢀ90
ꢀ90
rt
81
Trace
32
ꢀ90
62
ꢀ90
18c
a
Isolated yield.
b
The equiv values are given in parentheses.
c
Determined by 1H NMR analysis.
Table 3
Effect of substituents on cyclopropane ring and silicon atom
Entry
1
Substrate
Products
Yielda (%)
Entry
5
Substrate
Products
Yielda (%)
1b
74 (>99/1)b
1f
69
2
3
1c
64 (>99/1)b
74 (>99/1)b
6
7
1g
1h
72
76
1d
4
1e
70
8c
1a
43 (>99/1)b
Molar ratio, 1/n-BuLi/DCME¼1:2.5:1.2.
a
Isolated yield.
b
The E/Z ratios of the compounds are given in parentheses.
Butyl dichloromethyl ether was used instead of DCME.
c
excess amounts of n-butyllithium is present, n-butyllithium also
acts as a base and formally eliminates HCl from DCME to give the
chloromethoxycarbene.13 The following reaction of the resulting
chloromethoxycarbene with the cyclopropyllithium provides lith-
ium carbenoid intermediate A.14 The loss of lithium chloride from A
gives cyclopropylmethoxycarbene B. The intramolecular 1,2-
migration of the silyl group on the adjacent carbon to this car-
bene center affords the cyclopropylidene derivative 4.15 In this
migration process, the thermodynamically favored E-isomer is ex-
clusively produced. The quenching reagents only deactivate the
excessive base and disassociate from the formation of 4.
These cyclopropylidene derivatives 4 were not very stable and
hydrolyzed slowly during attempted chromatography on silica gel
to give the cyclopropyl silyl ketones in the purification of crude
products. Thus triethylamine (2.5%) was added to an eluent. On the
contrary, the protonolysis of the resulting cyclopropylidene de-
rivative 4a with sulfuric acid in methanol gave the corresponding
cyclopropyl silyl ketone 2a in good yield. In this reaction, trans
isomer of the two possible diastereomeric isomers was preferen-
tially formed (Scheme 4). The stereoisomers were characterized by
NOESY experiment, and confirmed by the 1H NMR spectra. It was
Scheme 2. Crossover experiment of 1,2-silyl migration.
The results mentioned above suggest the following mechanism
for the reaction (Scheme 3). The bromineelithium exchange be-
tween n-butyllithium and cyclopropyl bromides 1 affords the cor-
responding cyclopropyllithium. In the reaction using 1 equiv of n-
buthyllithium, resulting cyclopropyllithium behaves as a base and
abstracts a proton from DCME to afford appreciable amounts of
silylcyclopropane 3.4 On the other hand, however, in the case that

M. Honda et al. / Tetrahedron 67 (2011) 9500e9508
9503
Scheme 3. Plausible reaction mechanism.
also found that cis isomer was easily transformed to the thermo-
dynamically favorable trans form by treatment with sulfuric acid in
THF as an aprotic solvent for 2 h at rt in excellent yield. On the other
hand, the reaction under THF reflux for 9 h proceeded to give
cyclobutanone derivative (Scheme 4).
shown in Table 4. The moderate yields were observed in the re-
action of 1 possessing 2,2-dimethylcyclopropyl and trans-2,3-
dimethylcyclopropyl group, however, the desired cyclopropyl silyl
ketones 2 were generally provided with much higher isolated
yields than that reported in Ref. 4 in all reactions.
2.3. Synthesis of 1-substituted cyclopropyl silyl ketones
Only few synthetic routes to cyclopropyl silyl ketones have
been recorded until now, particularly the preparation of 1-
substituted cyclopropyl silyl ketones has not been well-
known.3b,d So then, trapping of cyclopropylidene derivatives 4
with some electrophiles instead of protic acid in a one-pot pro-
cedure was carried out to obtain the cyclopropyl silyl ketones
possessing different substituents at 1-position of cyclopropane
ring. The results are summarized in Table 5. The reaction with NCS,
NBS, PhSCl and PhSeCl as an electrophile proceeded to afford the
corresponding cyclopropyl silyl ketones 5 having different sub-
stituents on the 1-position of cyclopropane ring in moderate
yields. However, it was impossible to introduce an alkyl group into
the 1-position of cyclopropane ring by use of alkyl halide as
electrophile (entry 5). In these reactions, trans isomer of the two
possible diastereomeric isomers was preferentially formed (trans
refers to the relationship between the substituents R2 or R3 and
the introduced functional group E on the cyclopropane ring). The
stereoisomers were characterized by NOESY experiment. These
results suggest that the approach of electrophile to cyclo-
propylidene moiety proceeds from the opposite direction of sub-
Scheme 4. Isomerization and ring-expanding of 2a with sulfuric acid.
It appears that these reactions proceeded as follows (Scheme 5).
The oxygen atom of starting acylsilane cis-2a was protonated by
sulfuric acid and carbocation species C is formed. The cation C
transforms thermodynamically favored cation E via homoallyl
cation D derived by opening of cyclopropane ring.7,16,17 On the other
hand, under reflux condition, cyclobutonium cation F is formed by
the ring enlargement of C and E,17 because of the dissolution of ring
strain of three-membered ring and the stabilization of the resulting
carbocation with
b
-effect of silyl group.18 The following Brook
rearrangement19 and hydrolysis gives the cyclobutanone
derivative.
Scheme 5. Plausible reaction pathway.
Then the one-pot synthesis of cyclopropyl silyl ketones 2 having
different groups on the cyclopropane ring or silicon atom from
silylcyclopropyl bromides 1 was investigated. The reaction of
cyclopropyllithium derived from 1 with DCME and the following
treatment of sulfuric acid at low temperature after the addition of
methanol to reaction mixture gave the intended 2. These results are
stituent on cyclopropane ring to avoid the steric repulsion
between them (Scheme 6). Thus, higher diastereoselectivity was
observed in the reaction of silylcyclopropyl bromides having cis-
2,3-disubsutituted cyclopropyl group (Table 5, entries 8 and 9)
than that of monosubstituted cyclopropyl group (Table 5, entries
1e4). Similarly, when protic acid was used as an electrophile

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M. Honda et al. / Tetrahedron 67 (2011) 9500e9508
Table 4
One-pot synthesis of cyclopropyl silyl ketones
Entry
1
Substrate
Products
Yielda (%)
Entry
5
Substrate
Products
Yielda (%)
66
1a
73 (64/36)b
1e
2
3
1b
1c
67 (74/26)b
60 (66/34)b
6
7
1f
62
1g
47 (77/23)b
4
1d
48
8
1h
68 (85/15)b
Molar ratio, 1/n-BuLi/DCME¼1:2.5:1.2.
a
Isolated yield.
b
The trans/cis ratios of the compounds are given in parentheses.
(Table 4), cis isomer might be preferentially formed by the ap-
proach of the proton to cyclopropylidene moiety from the oppo-
site direction of substituent on cyclopropane ring (in this case, cis
refers to the relationship between the substituents R2 or R3 and
the carbonyl group on the cyclopropane ring). However, the fol-
lowing isomerization under acidic conditions mentioned above
would occur. As a consequence, trans isomer was preferentially
furnished.
s¼singlet; d¼doublet; t¼triplet; q¼quartet; quin¼quintet;
sext¼sextet; br¼broad; m¼multiplet. Mass spectra were recorded
on JEOL JMS-700 or JMS-SX102A mass spectrometer. Melting points
were measured on a Yanaco MP-J3 and were uncorrected. Analyt-
ical thin layer chromatography (TLC) was performed on precoated
glass plates (Merck Kieselgel 60 F254, layer thickness 0.25 mm).
Visualization was accomplished with UV light (254 nm) and
molybdophosphoric acid. Flash column chromatography was car-
ried out using Kanto Chemical silica gel 60 N (40e50 mm). Pre-
parative HPLC was performed on JAI LC-908 and LC-918
chromatograph equipped with JAIGEL-1H and -2H and JAIGEL-SIL.
GC analysis was performed on a Shimadzu GC-14B equipped with
3. Conclusion
In conclusion, the reaction of DCME with 1-silylcyclopropyl
anions in the presence of n-butyllithium was investigated. Under
basic conditions the reaction proceeded smoothly to afford the
corresponding cyclopropylidene derivatives. The resulting cyclo-
propylidene compounds were subjected to protonolysis, which
gave the cyclopropyl silyl ketones in good yields. The cis isomer of
cyclopropyl silyl ketone was easily transformed to the trans form by
treatment with sulfuric acid. On the other hand, cyclopropyl silyl
ketones possessing various substituents at 1-position of cyclopro-
pane ring are conveniently prepared in a one-pot reaction of 1-
silylcyclopropyl anions with DCME followed by the electrophilic
reaction in good yields.
a
CBP1-M25-O20 column (Shimadzu, 25 mꢂ0.22 mm, detec-
tor¼FID) with a helium gas as a carrier. Unless otherwise noted,
commercially available reagents were used without purification. All
the solvents were distilled and stored over a drying agent. n-
Butyllithium (1.6 M solution in hexane) was purchased from Kanto
Chemical Co., Inc. All reactions were carried out under an argon
atmosphere in dried glassware.
4.2. General procedure for the reaction of silylcyclopropyl
bromides and dichloromethyl methyl ether with n-BuLi
4. Experimental section
4.1. General
To a stirred solution of silylcyclopropyl bromide (1 mmol) in THF
(20 mL) at ꢀ90 ꢁC was added slowly a 1.6 M solution of n-BuLi
(1.5 mL, 2.5 mmol) in hexane. The resulting reaction mixture was
stirred at ꢀ90 ꢁC for 0.3 h, and then dichloromethyl methyl ether
(138 mg,1.2 mmol) in THF (2 mL) was added. After stirring for 0.5 h,
methanol (1 mL) was added and the reaction mixture was allowed
to warm to ambient temperature and then poured into saturated
NaHCO3 aq. The aqueous layer was extracted with diethyl ether for
three times. The combined organic layers were washed with brine,
dried over anhydrous Na2SO4, and concentrated in vacuo. The
residue was purified by column chromatography on a silica gel
using 40:1 hexane/triethylamine as eluent to give methox-
ycyclopropylidenemethylsilane derivatives.
IR spectra were recorded on Horiba FTIR-720 or Shimadzu FTIR-
8300 infrared spectrometer. 1H and 13C NMR spectra were recorded
on JEOL JNM EX-270, LA-400 or ECA-500 spectrometer. Chemical
shifts of 1H NMR were expressed in parts per million downfield
from tetramethylsilane (TMS) with reference to internal residual
CHCl3 (
d
¼7.26) in CDCl3. Chemical shifts of 13C NMR were expressed
in parts per million downfield from CDCl3
(d
¼77.0) as an internal
standard. Coupling constants (J) were reported in hertz (Hz). Fol-
lowing abbreviations were used to designate the multiplicities:

M. Honda et al. / Tetrahedron 67 (2011) 9500e9508
9505
Table 5
One-pot synthesis of 1-substituted cyclopropyl silyl ketones
Entry
1
Substrate
Electrophile
NCS
Products
Yielda (%)
1a
64 (76/24)b
56 (75/25)b
48 (86/14)b
59 (71/29)b
2
3
4
1a
1a
1a
NBS
PhSCI
PhSeCI
5
6
1a
1d
Mel
53 (66/34)b
17
PhSeCI
7
8
1e
1g
PhSeCI
PhSeCI
63
28 (>99/1)b
9
1h
PhSeCI
50 (>99/1)b
Molar ratio, 1/n-BuLi/DCME¼1:2.5:1.2.
a
Isolated yield.
b
The trans/cis ratios of the compounds are given in parentheses.
3H), 2.55 (dd, J¼4.6, 7.8 Hz, 1H), 2.05 (t, J¼7.8 Hz, 1H), 1.42 (dd,
J¼4.4, 7.6 Hz, 1H), 0.53 (s, 3H), 0.50 (s, 3H). HRMS calcd for
C
19H22OSi (Mþ) 294.1440, found 294.1439.
4.2.3. (Methoxy-2-phenylcyclopropylidenemethyl)triethylsilane
(4c). IR (neat) 3033, 2942, 1711, 1604, 1456, 1250, 845 cmꢀ1 1H
NMR (270 MHz, CDCl3): 7.56e7.02 (m, 5H), 3.83 (s, 3H), 2.60e2.55
(m, 1H), 2.03 (t, J¼7.4 Hz, 1H), 1.420e1.39 (m, 1H), 1.07e1.99 (m,
9H), 0.88e0.78 (m, 6H). HRMS calcd for C17H26OSi (Mþ) 274.1753,
found 274.1749.
.
d
Scheme 6. Stereoselective electrophilic attack to 4.
4.2.1. (Methoxy-2-phenylcyclopropylidenemethyl)trimethylsilane
(4a). IR (neat) 3028, 2958, 1720, 1604, 1496, 1452, 1248, 1203, 1147,
839 cmꢀ1. 1H NMR (400 MHz, CDCl3):
d 7.25e7.08 (m, 5H), 3.82 (s,
4.2.4. (2,2-Dimethylcyclopropylidenemethoxymethyl)trimethylsilane
(4d). IR (neat) 2957, 1724, 1458, 1442, 1248, 1200, 1144, 843 cmꢀ1
.
3H), 2.52 (dd, J¼4.2, 7.8 Hz, 1H), 2.01 (t, J¼7.6 Hz, 1H), 1.43 (dd,
1H NMR (400 MHz, CDCl3):
3H), 1.19 (s, 3H), 0.09 (s, 9H). 13C NMR (100 MHz, CDCl3):
d
3.29 (s, 3H), 1.47e1.22 (m, 2H), 1.20 (s,
144.8,
J¼4.2, 7.6 Hz, 1H), ꢀ0.01 (s, 9H). 13C NMR (100 MHz, CDCl3):
d 153.5,
d
143.9, 128.2, 125.8, 125.5, 107.8, 56.0, 18.4,18.3, ꢀ2.1. HRMS calcd for
C14H20OSi (Mþ) 232.1283, found 232.1280.
117.89, 57.6, 35.7, 30.2, 24.9, 24.0, 2.1. HRMS calcd for C10H20OSi
(Mþ) 184.1283, found 184.1285.
4.2.2. (Methoxy-2-phenylcyclopropylidenemethyl)dimethyllpheny-
4.2.5. (trans-2,3-Dimethylcyclopropylidenemethoxymethyl)trime-
thylsilane (4e). IR (neat) 2956, 1726, 1461, 1446, 1247, 1201, 1150,
lsilane (4b). IR (neat) 3052, 2957, 1715, 1614, 1486, 1251, 1132,
843 cmꢀ1. 1H NMR (270 MHz, CDCl3):
d 7.86e7.01 (m, 10H), 3.83 (s,

9506
M. Honda et al. / Tetrahedron 67 (2011) 9500e9508
841 cmꢀ1
.
1H NMR (400 MHz, CDCl3):
d
3.69 (s, 3H), 1.20 (d,
4.5. General procedure for the one-pot synthesis of
J¼6.0 Hz, 3H), 1.14 (d, J¼6.0 Hz, 3H), 1.03e0.97 (m, 1H), 0.93e0.88
cyclopropyl silyl ketones
(m, 1H), 0.14 (s, 9H). 13C NMR (100 MHz, CDCl3):
d 164.8, 116.4, 56.0,
20.1, 19.9, 19.0, 16.2, ꢀ1.7. HRMS calcd for C10H20OSi (Mþ) 184.1283,
To a stirred solution of silylcyclopropyl bromide (1 mmol) in THF
(20 mL) at ꢀ90 ꢁC was added slowly a 1.6 M solution of n-BuLi
(1.5 mL, 2.5 mmol) in hexane. The resulting reaction mixture was
stirred at ꢀ90 ꢁC for 0.3 h, and then dichloromethyl methyl ether
(138 mg,1.2 mmol) in THF (2 mL) was added. After stirring for 0.5 h,
methanol (1 mL) and sulfuric acid (1 mmol) was sequentially
added. The reaction mixture was stirred for 0.1 h and allowed to
warm to ambient temperature and then poured into saturated
NaHCO3 aq. The aqueous layer was extracted with diethyl ether for
three times. The combined organic layers were washed with brine,
dried over anhydrous Na2SO4, and concentrated in vacuo. The
residue was purified by column chromatography on a silica gel
using 20:1 hexane/ethyl acetate as eluent to give cyclopropyl silyl
ketone derivatives.
found 184.1283.
4.2.6. (trans-2,3-Dimethylcyclopropylidenemethoxymethyl)dime-
thylphenylsilane (4f). IR (neat) 3065, 2955, 1723, 1455, 1253, 1143,
838 cmꢀ1. 1H NMR (270 MHz, CDCl3):
d 7.52e7.10 (m, 5H), 3.71 (s,
3H), 1.28 (d, J¼6.0 Hz, 3H), 1.17 (d, J¼6.0 Hz, 3H), 1.08e0.99 (m, 1H),
0.95e0.90 (m, 1H), 0.47 (s, 3H), 0.45 (s, 3H). HRMS calcd for
C15H22OSi (Mþ) 246.1440, found 246.1441.
4.2.7. (cis-2,3-Dimethylcyclopropylidenemethoxymethyl)trimethylsi-
lane (4g). IR (neat) 2963, 1718, 1453, 1255, 1148, 846 cmꢀ1. 1H NMR
(270 MHz, CDCl3):
d
3.67 (s, 3H), 1.19 (d, J¼5.9 Hz, 3H), 1.14 (d,
J¼5.9 Hz, 3H), 1.22e1.12 (m, 2H), 0.15 (s, 9H). HRMS calcd for
C10H20OSi (Mþ) 184.1283, found 184.1289.
4.5.1. 2-Phenylcyclopropyl dimethylphenylsilyl ketone (2b). IR (neat)
4.2.8. (Bicyclo[4.1.0]heptan-7-ylidenemethoxymethyl)trimethylsilane
3086, 3063, 3030, 2959, 2900, 1705, 1640, 1496, 1250, 846 cmꢀ1. 1H
(4h). IR (neat) 2930,1711,1460,1448,1246,1201,1140, 840 cmꢀ1. 1H
NMR (400 MHz, CDCl3):
d
7.56e6.98 (m, 10H), 2.70 (ddd, J¼3.4, 4.6,
NMR (400 MHz, CDCl3):
(m, 1H), 1.73e1.66 (m, 1H), 1.64e1.54 (m, 2H), 1.38e1.28 (m, 2H),
1.28e1.15 (m, 2H), 0.15 (s, 9H). 13C NMR (100 MHz, CDCl3):
151.4,
d
3.65 (s, 3H), 1.95e1.85 (m, 2H), 1.82e1.76
8.6 Hz, 1H), 2.48 (ddd, J¼3.1, 5.9, 9.6 Hz, 1H), 1.74e1.69 (m, 1H), 1.29
(ddd, J¼2.6, 5.3, 9.3 Hz,1H), 0.52 (s, 3H), 0.51 (s, 3H). HRMS calcd for
C18H20OSi (Mþ) 280.1283, found 280.1284.
d
113.1, 56.1, 25.3, 24.6, 21.5, 21.1, 15.6, 11.4, ꢀ1.7. HRMS calcd for
C12H22OSi (Mþ) 210.1440, found 210.1441.
4.5.2. 2-Phenylcyclopropyl triethylsilyl ketone (2c). IR (neat) 3040,
2955, 1621, 1456, 1239, 1017, 735 cmꢀ1. 1H NMR (400 MHz, CDCl3):
4.2.9. (Butoxy-2-phenylcyclopropylidenemethyl)trimethylsilane
(4i). Butyl dichloromethyl ether was used instead of dichlor-
omethyl methyl ether to yield 4i. IR (neat) 3033, 2956, 1718, 1601,
1493, 1451, 1252, 1201, 1151, 843 cmꢀ1. 1H NMR (400 MHz, CDCl3):
d
7.90e7.30 (m, 5H), 2.74e2.70 (m, 1H), 2.54e2.49 (m, 1H),
1.75e1.70 (m, 1H), 1.35e1.30 (m, 1H), 1.02e1.96 (m, 9H), 0.80e0.74
(m, 6H). 13C NMR (100 MHz, CDCl3):
d 244.6, 140.7, 128.4, 126.3,
126.1, 38.2, 29.5, 18.8, 7.3, 2.0. HRMS calcd for C16H24OSi (Mþ)
260.1596, found 260.1593.
d
7.25e7.08 (m, 5H), 4.13e4.02 (m, 2H), 2.54 (dd, J¼4.0, 8.0 Hz, 1H),
1.95 (t, J¼7.6 Hz, 1H), 1.66 (dt, J¼6.6, 15.0 Hz, 2H), 1.45 (ddd, J¼5.6,
7.6, 15.0 Hz, 2H), 1.35 (dd, J¼4.0, 7.4 Hz, 1H), 0.96 (t, J¼7.4 Hz, 3H),
4.5.3. 2,2-Dimethylcyclopropyl trimethylsilyl ketone (2d). IR (neat)
ꢀ0.02 (s, 9H). 13C NMR (100 MHz, CDCl3):
d
152.7, 144.2, 128.3,
2952, 1728, 1621, 1379, 1250, 1103, 842 cmꢀ1 1H NMR (400 MHz,
.
125.9, 125.5, 107.8, 67.8, 31.9, 19.5, 18.9, 18.5, 14.1, ꢀ2.0. HRMS calcd
CDCl3):
d
2.42 (dd, J¼5.9, 7.3 Hz, 1H), 1.44 (dd, J¼3.9, 5.6 Hz, 1H),
for C17H26OSi (Mþ) 274.1753, found 274.1750.
1.24 (s, 3H), 0.96 (s, 3H), 0.74 (dd, J¼3.7, 7.3 Hz, 1H), 0.20 (s, 9H). 13C
NMR (100 MHz, CDCl3):
d
245.8, 40.6, 28.4, 27.3, 22.3, 18.3, ꢀ3.6.
HRMS calcd for C9H18OSi (Mþ) 170.1127, found 170.1131.
4.3. Protonolysis of (methoxy-2-
phenylcyclopropylidenemethyl)trimethylsilane 4a
4.5.4. trans-2,3-Dimethylcyclopropyl trimethylsilyl ketone (2e). IR
(neat) 2955, 1716, 1618, 1456, 1249, 1069, 842 cmꢀ1 1H NMR
.
4.3.1. 2-Phenylcyclopropyl trimethylsilyl ketone (2a). IR (neat) 3036,
2958, 1617, 1510, 1461, 1241, 1041, 834 cmꢀ1. HRMS calcd for
C13H18OSi (Mþ) 218.1127, found 218.1123. trans-2a: 1H NMR
(400 MHz, CDCl3):
d
2.33 (dd, J¼5.2, 8.6 Hz, 1H), 1.54 (dd, J¼6.0,
11.2 Hz, 1H), 1.34e1.30 (m, 1H), 1.05 (d, J¼5.7 Hz, 3H), 0.97 (d,
J¼5.7 Hz, 3H), 0.19 (s, 9H). 13C NMR (100 MHz, CDCl3):
d 246.6, 40.3,
(500 MHz, CDCl3):
d
7.28e7.10 (m, 5H), 3.00 (ddd, J¼5.7, 6.9, 9.2 Hz,
30.5, 23.5, 18.1, 11.6, ꢀ3.5. HRMS calcd for C9H18OSi (Mþ) 170.1127,
1H), 2.77 (dd, J¼8.6, 8.6 Hz, 1H), 2.01 (ddd, J¼5.2, 6.3, 7.4 Hz, 1H),
found 170.1119.
1.22 (ddd, J¼4.6, 7.4, 8.6 Hz, 1H), 0.05 (s, 9H). 13C NMR (125 MHz,
CDCl3):
d
242.8, 135.8, 128.8, 127.6, 126.2, 34.4, 29.8, 10.6, ꢀ3.7. cis-
4.5.5. trans-2,3-Dimethylcyclopropyl dimethylphenylsilyl ketone
2a: 1H NMR (500 MHz, CDCl3):
d
7.32e7.10 (m, 5H), 2.51 (ddd, J¼4.0,
(2f). IR (neat) 3070, 2952, 1713, 1618, 1428, 1249, 1111, 834 cmꢀ1. 1H
6.3, 9.2 Hz, 1H), 1.34 (ddd, J¼4.0, 6.9, 8.0 Hz, 1H), 1.70 (ddd, J¼4.0,
NMR (400 MHz, CDCl3):
d
7.58e7.36 (m, 5H), 2.30 (dd, J¼4.9, 8.8 Hz,
5.1, 8.6 Hz, 1H), 0.24 (s, 9H). 13C NMR (125 MHz, CDCl3):
d
244.4,
1H), 1.57e1.51 (m, 1H), 1.32e1.22 (m, 1H), 0.99 (d, J¼6.1 Hz, 3H),
0.92 (d, J¼6.1 Hz, 3H), 0.49 (s, 3H), 0.46 (s, 3H). HRMS calcd for
C14H20OSi (Mþ) 232.1284, found 232.1283.
140.5, 128.8, 128.3, 126.0, 36.9, 29.5, 19.0, ꢀ3.4.
4.4. Isomerization of cis-2a with sulfuric acid into trans-2a
4.5.6. cis-2,3-Dimethylcyclopropyl trimethylsilyl ketone (2g). IR
(neat) 2958, 1644, 1618, 1410, 1249, 1076, 845 cmꢀ1 1H NMR
.
To a stirred solution of mixture of cis and trans-2a (36:64,
1 mmol) in THF (10 mL) at 20 ꢁC was added slowly a sulfuric acid
(1 mmol). After stirring for 2 h, the reaction mixture was poured
into saturated NaHCO3 aq. The aqueous layer was extracted with
diethyl ether for three times. The combined organic layers were
washed with brine, dried over anhydrous Na2SO4, and concentrated
in vacuo. The residue was purified by column chromatography on
a silica gel using 20:1 hexane/ethyl acetate as eluent to give trans-
2a in 97% yield.
(400 MHz, CDCl3):
d
1.90 (t, J¼4.3 Hz,1H),1.63e1.58 (m, 2H),1.09 (d,
J¼5.7 Hz, 6H), 0.20 (s, 9H). 13C NMR (100 MHz, CDCl3):
d 246.1, 43.6,
26.1, 12.1, ꢀ3.3. HRMS calcd for C9H18OSi (Mþ) 170.1127, found
170.1124.
4.5.7. Bicyclo[4.1.0]hept-7-yl trimethylsilyl ketone (2h). IR (neat)
2930, 2860, 1616, 1402, 1248, 1099, 846 cmꢀ1. 1H NMR (400 MHz,
CDCl3):
d
2.30 (t, J¼4.1 Hz, 1H), 1.90e1.85 (m, 2H), 1.75e1.71 (m,
2H), 1.69e1.66 (m, 1H), 1.64e1.62 (m, 1H), 1.35e1.22 (m, 4H), 0.22

M. Honda et al. / Tetrahedron 67 (2011) 9500e9508
9507
(s, 9H). HRMS calcd for C11H20OSi (Mþ) 196.1284, found
196.1282.
1H NMR (400 MHz, CDCl3):
d
7.32e7.17 (m, 5H), 1.98 (dq, J¼5.9,
6.3 Hz, 1H), 1.46 (dq, J¼5.9, 6.3 Hz, 1H), 1.26 (d, J¼6.3 Hz, 3H), 1.08
(d, J¼6.3 Hz, 3H), 0.23 (s, 9H). 13C NMR (100 MHz, CDCl3):
d 240.9,
4.6. General procedure for the one-pot synthesis of 1-
substituted cyclopropyl silyl ketones
132.0, 129.0, 128.3, 125.7, 49.0, 31.5, 22.5, 15.8, 13.3, ꢀ1.8. HRMS
calcd for C15H22OSeSi (Mþ) 326.0605, found 326.0604.
To a stirred solution of silylcyclopropyl bromide (1 mmol) in THF
(20 mL) at ꢀ90 ꢁC was added slowly a 1.6 M solution of n-BuLi
(1.5 mL, 2.5 mmol) in hexane. The resulting reaction mixture was
stirred at ꢀ90 ꢁC for 0.3 h, and then dichloromethyl methyl ether
(138 mg,1.2 mmol) in THF (2 mL) was added. After stirring for 0.5 h,
electrophilic reagent (1.5 mmol) in THF (2 mL) was added and
stirred for 0.5 h. The reaction mixture allowed to warm to ambient
temperature and then poured into saturated NaHCO3 aq. The
aqueous layer was extracted with diethyl ether for three times. The
combined organic layers were washed with brine, dried over an-
hydrous Na2SO4, and concentrated in vacuo. The residue was pu-
rified by column chromatography on a silica gel using 20:1 hexane/
ethyl acetate as eluent to give cyclopropyl silyl ketone derivatives.
4.6.7. cis-2,3-Dimethyl-1-phenylselenocyclopropyl trimethylsilyl ke-
tone (5g). IR (neat) 3033, 2955, 1618, 1580, 1479, 1439, 1246,
845 cmꢀ1. 1H NMR (400 MHz, CDCl3):
d 7.25e7.09 (m, 5H), 1.78 (m,
2H), 1.17 (d, J¼6.4 Hz, 6H), 0.18 (s, 9H). 13C NMR (100 MHz, CDCl3):
d
239.7, 130.9, 129.0, 128.5, 125.7, 50.5, 23.4, 23.4, 10.2, 10.2, ꢀ1.4.
HRMS calcd for C15H22OSeSi (Mþ) 326.0605, found 326.0603.
4.6.8. 7-Phenylselenobicyclo[4.1.0]hept-7-yl trimethylsilyl ketone
(5h). IR (neat) 3032, 2937, 1618, 1577, 1479, 1460, 1439, 1246,
842 cmꢀ1
.
1H NMR (400 MHz, CDCl3):
d
7.21e7.14 (m, 5H),
2.02e1.94 (m, 2H), 1.94e1.90 (m, 2H), 1.60e1.48 (m, 4H), 1.32e1.23
(m, 2H), 0.17 (s, 9H). 13C NMR (100 MHz, CDCl3):
238.4, 130.6,
d
129.1, 128.4, 125.7, 50.6, 22.4, 21.5, 20.9, ꢀ1.3. HRMS calcd for
C17H24OSeSi (Mþ) 352.0762, found 352.0759.
4.6.1. 1-Chloro-2-phenylcyclopropyl trimethylsilyl ketone (5a). IR
(neat) 3042, 2961, 1621, 1514, 1453, 1254, 1046, 872 cmꢀ1. 1H NMR
Acknowledgements
(400 MHz, CDCl3):
d
7.21e6.80 (m, 5H), 2.79 (dd, J¼8.4, 10.0 Hz, 1H),
2.19 (dd, J¼6.4, 8.4 Hz, 1H), 1.37 (dd, J¼6.4, 10.0 Hz, 1H), ꢀ0.14 (s,
This work was partially supported by a Grant-in-Aid for Scien-
tific Research from the Ministry of Education, Culture, Sports, Sci-
ence, and Technology (MEXT), Japan.
9H). 13C NMR (100 MHz, CDCl3):
d 235.2, 133.6, 128.5, 128.1, 127.1,
57.0, 38.7, 18.8, ꢀ2.4. HRMS calcd for C13H17ClOSi (Mþ) 252.0737,
found 252.0730.
References and notes
4.6.2. 1-Bromo-2-phenylcyclopropyl trimethylsilyl ketone (5b). IR
(neat) 3039, 2959, 1617, 1521, 1452, 1255, 1170, 1052, 846 cmꢀ1. 1H
1. For recent reviews on synthesis and reaction of acylsilanes, see: (a) Brook, M. A.
Silicon in Organic, Organometallic, and Polymer Chemistry; Wiley: New York, NY,
2000; (b) Bonini, B. F.; Comes-Franchini, M.; Fochi, M.; Mazzanti, G.; Ricci, A. J.
Organomet. Chem. 1998, 567, 181e189; (c) Qi, H.; Curran, D. P. In Acyl Silicon,
Germanium, or Boron Functions; Katrizky, A. R., Meth-Cohn, O., Rees, C. W.,
Moody, C. J., Eds.; Comprehensive Organic Functional Group Transformations:
Synthesis: Carbon with Two Attached Heteroatoms with at Least One Carbon-
to-Heteroatom Multiple Link; Pergamon: Oxford, 1995; Vol. 5; Chapter 5.09,
pp 409e433; (d) Cirillo, P. F.; Panek, J. S. Org. Prep. Proced. Int. 1992, 24,
553e582.
2. (a) Page, P. C. B.; Klair, S. S.; Rosenthal, S. Chem. Soc. Rev. 1990, 19, 147e195; (b)
Ricci, A.; Degl’Innocenti, A. Synthesis 1989, 647e660; (c) Fleming, I.; Barbero, A.;
Walter, D. Chem. Rev. 1997, 97, 2063e2192; (d) Hau, C. S.; Jarvis, A. N.; Sweeney,
J. B. Contemp. Org. Synth. 1996, 3, 65e91.
3. For reports about synthesis and reaction of cyclopropyl silyl ketones, see: (a)
Danheiser, R. L.; Fink, D. M. Tetrahedron Lett. 1985, 26, 2513e2516; (b) Scheller,
M. E.; Frei, B. Helv. Chim. Acta 1986, 69, 44e52; (c) Kang, J.; Lee, J. H.; Kim, K. S.;
Jeong, J. U.; Ryun, C. Tetrahedron Lett. 1987, 28, 3261e3262; (d) Nowick, J. S.;
Danheiser, R. L. Tetrahedron 1988, 44, 4113e4134; (e) Clayden, J.; Watson, D. W.;
Chambers, M. Tetrahedron 2005, 61, 3195e3203.
4. Nakajima, T.; Tanabe, M.; Ohno, K.; Segi, M.; Suga, S. Chem. Lett. 1986, 177e180.
5. Honda, M.; Yamamoto, Y.; Tsuchida, H.; Segi, M.; Nakajima, T. Tetrahedron Lett.
2005, 46, 6465e6468.
6. Nakajima, T.; Segi, M.; Sugimoto, F.; Hioki, R.; Yokota, S.; Miyashita, K. Tetra-
hedron 1993, 49, 8343e8358.
7. Honda, M.; Naitou, T.; Hoshino, H.; Takagi, S.; Segi, M.; Nakajima, T. Tetrahedron
Lett. 2005, 46, 7345e7348.
8. The moderate yields denoted in Ref. 4 are determined by G.C. The attempt to
isolate the cyclopropyl silyl ketones 2 actually affords lower yields.
9. Nishizawa, T.; Nakae, K.; Honda, M.; Kunimoto, K.-K.; Segi, M. Tetrahedron Lett.
2010, 51, 1294e1297.
10. Skell, P. S.; Garner, A. Y. J. Am. Chem. Soc. 1956, 78, 3409e3411.
11. Kitatani, K.; Hiyama, T.; Nozaki, H. J. Am. Chem. Soc. 1975, 97, 949e951.
12. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman,
J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Car-
icato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg,
J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Naka-
jima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J.
E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.;
Keith, T.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.;
Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.;
Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.;
Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.;
Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Dapprich, S.; Daniels, A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.;
Fox, D. J. Gaussian 09 Revision B.01; Gaussian: Wallingford, CT, 2010.
13. Hine, J.; Rosscup, R. J.; Duffey, D. C. J. Am. Chem. Soc. 1960, 82, 6120e6123.
14. Closs, G. L. J. Am. Chem. Soc. 1962, 84, 809e813.
NMR (400 MHz, CDCl3):
d
7.21e6.74 (m, 5H), 2.74 (dd, J¼8.4,
10.0 Hz, 1H), 2.15 (dd, J¼7.2, 8.4 Hz, 1H), 1.31 (dd, J¼6.8, 9.7 Hz, 1H),
ꢀ0.24 (s, 9H). 13C NMR (100 MHz, CDCl3):
d 234.2, 133.8, 128.2,
128.1,127.0, 46.8, 36.7,17.5, ꢀ2.2. C13H17BrOSi (Mþ) 296.0232, found
296.0240.
4.6.3. 2-Phenyl-1-phenylthiocyclopropyl
(5c). IR (neat) 3051, 2952, 1622, 1582, 1498, 1479, 1456, 1439, 1244,
843 cmꢀ1 1H NMR (400 MHz, CDCl3):
7.23e7.06 (m, 10H), 2.99
trimethylsilyl
ketone
.
d
(dd, J¼8.0, 8.5 Hz, 1H), 2.67 (dd, J¼5.6, 7.6 Hz, 1H), 1.45 (dd, J¼5.6,
9.0 Hz, 1H), ꢀ0.11 (s, 9H). 13C NMR (100 MHz, CDCl3):
d 238.0, 136.5,
134.0, 128.9, 128.4, 128.0, 127.0, 126.4, 125.5, 46.9, 37.0, 17.6, ꢀ2.5.
HRMS calcd for C19H22OSSi (Mþ) 326.1161, found 326.1165.
4.6.4. 2-Phenyl-1-phenylselenocyclopropyl trimethylsilyl ketone
(5d). IR (neat) 3059, 2957, 1616, 1580, 1497, 1479, 1452, 1439, 1248,
843 cmꢀ1. HRMS calcd for C19H22OSeSi (Mþ) 374.0605, found
374.0606. cis-5d: 1H NMR (400 MHz, CDCl3):
d
7.30e7.10 (m, 10H),
2.69 (dd, J¼7.6, 9.0 Hz,1H), 2.51 (dd, J¼5.1, 9.3 Hz,1H),1.64 (dd, J¼5.1,
7.3 Hz, 1H), 0.26 (s, 9H). 13C NMR (100 MHz, CDCl3):
239.2, 136.3,
130.6, 129.4, 129.1, 129.0, 127.8, 127.1, 126.1, 45.6, 33.6, 19.8, ꢀ1.3.
trans-5d: 1H NMR (400 MHz, CDCl3):
7.30e7.10 (m, 10H), 2.99 (dd,
d
d
J¼7.3, 8.8 Hz, 1H), 2.54 (dd, J¼5.8, 7.1 Hz, 1H), 1.49 (dd, J¼6.1, 8.8 Hz,
1H), ꢀ0.10 (s, 9H). 13C NMR (100 MHz, CDCl3):
d 236.5, 135.1, 131.3,
129.2, 128.1, 128.0, 126.9, 126.8, 126.1, 44.4, 34.6, 16.9, ꢀ0.1.
4.6.5. 2,2-Dimethyl-1-phenylselenocyclopropyl trimethylsilyl ketone
(5e). IR (neat) 3033, 2951, 1618, 1578, 1477, 1439, 1248, 843 cmꢀ1
.
1H NMR (400 MHz, CDCl3):
d
7.29e7.13 (m, 5H), 1.93 (d, J¼5.1 Hz,
1H), 1.52 (s, 3H), 1.03 (s, 3H), 0.86 (d, J¼5.1 Hz, 1H), 0.23 (s, 9H). 13C
NMR (100 MHz, CDCl3): d 237.7, 130.7, 130.2, 129.0, 126.4, 49.8, 27.8,
24.9, 24.1, 21.3, ꢀ1.9. HRMS calcd for C15H22OSeSi (Mþ) 326.0605,
found 326.0607.
4.6.6. trans-2,3-Dimethyl-1-phenylselenocyclopropyl trimethylsilyl
ketone (5f). IR (neat) 3059, 2957, 1617, 1479, 1247, 1077, 844 cmꢀ1
.

9508
M. Honda et al. / Tetrahedron 67 (2011) 9500e9508
15. (a) Creary, X.; Wang, Y.-X. Tetrahedron Lett. 1989, 30, 2493e2496; (b) Creary, X.;
Butchko, M. A. J. Org. Chem. 2001, 66, 1115e1121; (c) Creary, X.; Butchko, M. A. J.
Org. Chem. 2002, 67, 112e118.
17. For review, see: Wiberg, K. B.; Hess, B. A., Jr.; Ashe, A. J., III. In Carbonium Ions;
Olah, G. A., Schleyer, P. v. R., Eds.; Wiley: New York, NY, 1972; Vol. 3,
pp 1295e1345.
16. The reaction of 2a with HCl proceeded to afford the corresponding 4-chloro-4-
phenyl-1-trimethylsilylbutanone. This result suggests that the product gener-
ates via homoallyl cation D; Nakajima, T.; Miyaji, H.; Segi, M.; Suga, S. Chem.
Lett. 1986, 181e182.
18. (a) Wierschke, S. G.; Chandrasekhar, J.; Jorgensen, W. L. J. Am. Chem. Soc. 1985,
107, 1496e1500; (b) Lambert, J. B.; Wang, G.-T.; Finzel, R. B.; Teramura, D. H. J.
Am. Chem. Soc. 1987, 109, 7838e7845.
19. Brook, A. G. Acc. Chem. Res. 1974, 7, 77e84.