Carbocyclization reaction of malonate derivatives with allylsilane moiety mediated by AICI3-n-BU3N

Article abstract of DOI:10.1246/bcsj.80.972

Allylsilane bearing malonate moiety underwent intramolecular carbocyclization reaction by means of AlCl₃-n-BU₃N to give silyl-substituted cyclopentanes in good yields.

Full text of DOI:10.1246/bcsj.80.972

972 Bull. Chem. Soc. Jpn. Vol. 80, No. 5, 972–978 (2007)
ꢀ 2007 The Chemical Society of Japan
Carbocyclization Reaction of Malonate Derivatives
with Allylsilane Moiety Mediated by AlCl3-n-Bu3N
ꢀ1;2
Shigeaki Imazeki,
Ryohiko Kinoshita,1 and Takahiko Akiyama2
1Chemical Products Research Laboratories, Wako Pure Chemical Industries, Ltd., 1633 Matoba, Kawagoe 350-1101
2Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588
Received November 21, 2006; E-mail: imazeki.shigeaki@wako-chem.co.jp
Allylsilane bearing malonate moiety underwent intramolecular carbocyclization reaction by means of AlCl3-n-
Bu3N to give silyl-substituted cyclopentanes in good yields.
Allylsilane has been extensively employed as an allyl an-
ion equivalent in the Lewis acid mediated addition reaction to-
ward aldehyde, aldimine, and ꢀ,ꢁ-unsaturated carbonyl com-
pounds.1 The high reactivity of the allylsilane as a nucleophile
is ascribed to the propensity of the silyl group to stabilize a ꢁ-
silyl carbocation intermediate.2 Recently, a novel method for
the preparation of carbocycles and heterocycles has been de-
veloped, wherein nucleophilic attack on the carbon center of
the ꢁ-silyl carbocation intermediate3 has been efficiently em-
ployed for the formation of a carbon–carbon bond4,5 as well
as a carbon–hetero atom bond.6,7 We have already reported
that the Brønsted acid promoted cyclization of allylsilane bear-
ing hydroxy and N-tosyl moieties leading to tetrahydrofuran8
and pyrolidine,9 respectively (Scheme 1).10,11
best results in terms of the yield (Entry 3).
Because the combination of AlCl3 and n-Bu3N gave the best
results, we screened the solvents (Table 3).
Among the solvents tested, CH2Cl2 exhibited the best result
(Entry 1), whereas benzene, THF, and hexane were not effec-
tive (Entries 4–6). Finally, allylsilanes bearing different silyl
moieties were examined as a substrate (Table 4).
The relative stereochemistry of the cyclization products 2
was determined by 1H NMR NOE analysis. NOE data for
2a, 2b, and 2d are shown in Scheme 3.
In order to clarify the reaction mechanism, a labeling ex-
periment was performed (Scheme 4). Treatment of 1b-D with
AlCl3-(n-Bu)3N gave cyclization product 2b-D in a good
yield. Deuterium was incorporated in the methyl group. Fur-
thermore, treatment of 1b with n-Bu3N-AlCl3 under the stan-
dard reaction conditions and quenched with D2O gave 2b,
but no deuterium was incorporated (Scheme 5).
On the basis of experimental data, we propose the following
reaction mechanism (Scheme 6). AlCl3 is activated the car-
bonyl group to facilitate the release of the a methine proton.
An ammonium salt then acts as a Brønsted acid to generate
ꢁ-silyl carbocation intermediate, which is attacked by a carbon
nucleophile to give cyclization product 2. The carboalumina-
tion mechanism, shown in Scheme 5, does not seem to be op-
erative.
We expected that use of carbon nucleophile in place of
hetero atom nucleophile would lead to 5-membered carbo-
cycles under the similar reaction conditions and would
provide a novel method for the formation of cyclopentanes
(Scheme 2).
Results and Discussion
Carbocyclization reaction of allylsilane 1 bearing a malo-
nate moiety as a carbon nucleophile was investigated. At the
outset, we studied several Brønsted acid to promote the cycli-
zation reaction (Table 1). p-TsOH, which was effective for the
cyclization leading to tetrahydrofuran and pyrolidine, turned
out to be ineffective to give desilylation product 3 (Entry 1).
We found that the use of AlCl3 gave cyclization product 2a
albeit in a low yield (Entry 5).
Preparation of the Substrates.
Substrates 1 were
readily prepared starting from the corresponding allylsilane
(Scheme 7). Treatment of the carbanion that was generated
from allylsilane with ethylene oxide gave silyl-substituted
bishomoallylic alcohols 4. The malonate moiety was intro-
duced after transformation of the alcohol to iodide 5 to give
1 in good yields.
After screening the reaction conditions, we found that the
addition of a tertiary amine had beneficial effect on the yield
of 2b (Table 2). Among the amines used, n-Bu3N gave the
CH3
SiMe2Ph
p-TsOH (20 mol%)
SiMe2Ph
X=O, NTs
X
X
H
CH2Cl2
R2
R2 R1
R1
Scheme 1.
Published on the web May 14, 2007; doi:10.1246/bcsj.80.972

S. Imazeki et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 5 (2007)
973
Si
CH3
Conclusion
acid catalyst
E
E
We found a novel carbocyclization of malonate moiety in
the allylsilane mediated by the combined use of AlCl3-(n-
Bu)3N. Silyl-substituted cyclopentanes were obtained in good
yields. On the basis of labeling experiments, a reaction mech-
anism was proposed.
E
E
1
2
Scheme 2.
Table 1. Effect of Acid on the CyclizationaÞ
SiMe2Ph
CH3
acid
E
E
+
SiMe2Ph
E
E
CH2Cl2
E
E
1a; E = CO2CH3
2a
3
Entry
Acid
Time
Yield of 2a/%
Yield of 3/%
Recovery of 1a/%
1
2
3
4
5
6
p-TsOH
CF3CO2H
CSA
SnCl4
AlCl3
GaCl3
2 d
2 d
2 d
3 h
4 h
4 h
0
0
0
0
11
0
96
64
57
90
10
0
0
19
33
0
0
0
a) 1.0 equiv of acid was employed at room temperature.
Table 2. Effect of BaseaÞ
Si(i-Pr)2Ph
CH3
CH3
AlCl3
E
E
E
+
Si(i-Pr)2Ph
Si(i-Pr)2Ph
E
CH2Cl2
E
E
1b
2b-trans
2b-cis
Entry
Amine
Yield of 2b-trans/%
Yield of 2b-cis/%
1
2
3
4
5
6bÞ
—
Et3N
n-Bu3N
2,6-Lutidine
Pyridine
TMEDA
21
44
55
39
40
8
20
33
30
30
30
5
a) Compound 1b was treated with 1.0 equiv of amine for 2 h in CH2Cl2 followed by treated
with 2.0 equiv of AlCl3 at room temperature for 15 h. b) Compound 1b was recovered in
71% yield.
Table 3. Influence of SolventaÞ
Si(i-Pr)2Ph
CH3
CH3
AlCl3
n-Bu3N
E
E
E
E
+
Si(i-Pr)2Ph
Si(i-Pr)2Ph
E
E
solvent
1b
2b-trans
2b-cis
Entry
Solvent
Yield of 2b-trans/%
Yield of 2b-cis/%
1
2
3
4
5bÞ
6cÞ
CH2Cl2
CHCl3
ClCH2CH2Cl
Benzene
THF
55
49
41
39
0
30
25
35
37
0
Hexane
15
16
a) Compound 1b was treated with 1.0 equiv of n-Bu3N in the solvent at room temperature
for 2 h followed by treated with 2.0 equiv of AlCl3 at room temperature for 15 h. b) Com-
pound 1b was recovered in 74% yield. c) 3 was obtained in 52% yield.

974 Bull. Chem. Soc. Jpn. Vol. 80, No. 5 (2007)
Carbocyclization Reaction of Allylsilane
Table 4. Effect of Silyl SubstituentsaÞ
Si
CH3
n-Bu3N
AlCl3
CH3
E
E
+
E
Si
Si
E
CH2Cl2
CH2Cl2
E
E
1
2-trams
2-cis
Entry
Starting
material
Si
Yield of 2-trans/%
Yield of 2-cis/%
1
2
3
4
1a
1b
1c
1d
SiMe2Ph
SiPh(i-Pr)2
Si(i-Pr)3
29
55
41
13
3
30
39
57
Si(t-Bu)2Ph
a) Compound 1 was treated with 1.0 equiv of n-Bu3N in the solvent at room temperature for
2 h followed by treated with 2.0 equiv of AlCl3 at room temperature for 6–15 h.
Experimental
H
4.1%
NMR spectra were measured in CDCl3 on 400 MHz spectrom-
E
E
H
H
CH3
H
H
Si
eter (JEOL AL-400) with tetramethylsilane (TMS) as an internal
standard. CDCl3 was used as an internal standard for 13C NMR.
All reagents were commercially available from Wako Pure Chem-
ical Industries Ltd., Japan.
E
H
H
4.6%
H
Si
H
H
5.1%
E
5.0%
H
5.1%
H3C
H
Typical Procedure for the Preparation of 3-(Dimethylphen-
11.1%
ylsilyl)pent-4-en-1-ol (4a).
A hexane solution of n-BuLi
2b-cis
2b-trans
2.1%
(29.1 mL, 45.4 mmol, 1.56 mol Lꢁ1) was added to a solution of
allyldimethylphenylsilane (4.40 mL, 22.7 mmol) and N,N,N0,N0-
tetramethylethylenediamine (4.4 mL, 29.5 mmol) in THF (50 mL)
at ꢁ10 ꢂC. After being stirred for 1 h, the mixture was cooled
down to ꢁ45 ꢂC. Ethylene oxide, generated by the reaction of
2-chloroethanol (3.0 mL, 45.4 mmol) with powder KOH (12.7 g,
226.3 mmol) in another flask, was added to the reaction mixture
to react with allyl anion. After being stirred for another 1 h at
ꢁ45 ꢂC, the reaction mixture was quenched by addition of
1 mol dmꢁ3 HCl solution. The water layer was extracted with
EtOAc. The combined organic layer was washed with sat.
NaHCO3 and brine, dried over anhydrous Na2SO4, and concen-
trated to dryness. Purification of the crude mixture by silica-gel
chromatography (hexane/EtOAc = 7/1, v/v) gave 4a as colorless
H
1.9%
E
H
H
H
CH3
H
Si
E
H
H
Si
5.4%
E
H
5.1%
H
H
E
H
5.1%
H3C
9.5%
H
10.2%
2.0%
11.4%
2a-trans
2d-cis
Scheme 3.
Si(i-Pr)2Ph
CH2D
1) n-Bu3N
2) AlCl3
D
E
E
Si(i-Pr)2Ph
E
E
1b-D
D content 90%
2b-D
D content 46%
Scheme 4.
CH3
E
E
Si(i-Pr)2Ph
Si(i-Pr)2Ph
D2O
1) n-Bu3N
2b(83%)
AlCl2
E
2) AlCl3
CH3
E
1b
E
E
E
E
Si(i-Pr)2Ph
Si(i-Pr)2Ph
2b-D(0%)
Scheme 5.

S. Imazeki et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 5 (2007)
975
Cl
NBu3
Si
H
Si
N(n-Bu)3
H
MeO
MeO
AlCl3
O
O
OMe
OMe
O
O
Cl2Al
Cl
H
CH3
Si
E
E
MeO
Si
O
OMe
O
Cl2Al
Scheme 6.
Si
Si
1)TsCl, Py
1) n-BuLi
Si
HO
I
2) ethylene oxide
2) NaI, acetone
5
4
Si
1) NaH
E
E
2) iodide (5)
E
E
1
Scheme 7.
oil (3.15 g, 14.3 mmol) in 63% yield.
12:2, 5.5, 2.7 Hz), 1.86–1.75 (1H, m), 1.61–1.54 (2H, m), 1.19–
1.06 (21H, m). 13C NMR (100 MHz, CDCl3) ꢂ 140.7, 112.6, 62.9,
32.2, 28.3, 19.1, 19.1, 19.0, 11.2. IR (neat) 3011, 2892, 1624, 1464,
1427, 1236, 1107, 1030, 995, 902, 702, 657 cmꢁ1. MS(EI) m=z
(%) = 233(30), 191(30), 165(80), 137(100), 121(80), 105(50).
Found: C, 69.71; H, 12.32%. Calcd for C14H30OSi: C, 69.35; H,
12.47%.
Colorless oil. Rf ¼ 0:3 (hexane/EtOAc = 7/1). 1H NMR
(400 MHz, CDCl3) ꢂ 7.50–7.45 (2H, m), 7.38–7.31 (3H, m), 5.62
(1H, ddd, J ¼ 17:6, 10.3, 9.7 Hz), 4.92 (1H, dd, J ¼ 10:3, 0.9 Hz),
4.88 (1H, dd, J ¼ 17:6, 0.9 Hz), 3.64 (1H, ddd, J ¼ 10:6, 9.2, 5.1
Hz), 3.50 (1H, ddd, J ¼ 10:6, 7.2, 7.1 Hz), 1.87 (1H, dt, J ¼ 9:7,
2.7 Hz), 1.66 (1H, dddd, J ¼ 11:2, 9.2, 7.2, 2.7 Hz), 1.62–1.53
(2H, m), 0.28 (3H, s), 0.27 (3H, s). 13C NMR (100 MHz, CDCl3)
ꢂ 139.0, 137.2, 133.9, 129.0, 127.6, 113.0, 62.5, 31.4, 31.0, ꢁ4:5,
ꢁ5:4. IR (neat) 3072, 2961, 1732, 1624, 1427, 1250, 1113, 1037,
902, 835, 700 cmꢁ1. MS(EI) m=z (%) = 204(10), 137(100),
119(30), 105(80), 68(80). Found: C, 70.55; H, 9.45%. Calcd for
C13H20OSi: C, 70.85; H, 9.15%.
3-(t-Butyldiphenylsilyl)pent-4-en-1-ol (4d):
Colorless oil.
1
Rf ¼ 0:3 (hexane/EtOAc = 7/1). H NMR (400 MHz, CDCl3) ꢂ
7.67 (2H, dd, J ¼ 6:7, 1.1 Hz), 7.61 (2H, dd, J ¼ 6:7, 1.1 Hz),
7.41–7.32 (6H, m), 5.88 (1H, ddd, J ¼ 17:0, 10.1, 10.1 Hz), 5.01
(1H, dd, J ¼ 17:0, 1.7 Hz), 5.00 (1H, dd, J ¼ 10:1, 1.7 Hz), 3.60
(1H, ddd, J ¼ 10:6, 6.8, 3.9 Hz), 3.55 (1H, ddd, J ¼ 10:6, 8.2,
6.1 Hz), 2.55 (1H, dt, J ¼ 10:1, 2.0 Hz), 1.83 (1H, dddd, J ¼ 12:8,
8.2, 6.8, 2.0 Hz), 1.51–1.40 (2H, m), 1.09 (9H, s). 13C NMR (100
MHz, CDCl3) ꢂ 139.4, 136.5, 136.3, 134.0, 133.4, 129.0, 129.0,
127.4, 127.4, 114.7, 61.9, 32.5, 28.6, 27.8, 19.4. IR (neat) 2963,
2860, 1626, 1427, 1105, 999, 819, 702, 632 cmꢁ1. MS(EI) m=z
(%) = 267(30), 199(100), 181(10), 135(100), 105(80). Found:
C, 77.67; H, 8.88%. Calcd for C21H28OSi: C, 77.72; H, 8.70%.
[1-(2-Iodoethyl)allyl]dimethylphenylsilane (5a). Alcohol 4a
(2.13 g, 9.67 mmol) was added to a solution of tosyl chloride
(2.40 g, 12.57 mmol) in pyridine (10 mL) at 0 ꢂC. After being stir-
red at room temperature overnight, the reaction mixture was
quenched by addition of 1 M HCl solution. The water layer was
extracted with EtOAc. The combined organic layer was succes-
sively washed with 1 mol dmꢁ3 HCl solution, sat. NaHCO3, and
brine. The organic layer was dried over anhydrous Na2SO4 and
concentrated to dryness. Purification of the crude mixture by
silica-gel chromatography gave corresponding tosylate as a color-
less oil (2.99 g, 7.99 mmol, 83%). The tosylate (1.47 g, 3.92 mmol)
3-(Diisopropylphenylsilyl)pent-4-en-1-ol (4b): Colorless oil.
1
Rf ¼ 0:3 (hexane/EtOAc = 7/1). H NMR (400 MHz, CDCl3) ꢂ
7.50–7.48 (2H, m), 7.35–7.33 (3H, m), 5.75 (1H, ddd, J ¼ 17:1,
10.0, 10.0 Hz), 4.96 (1H, dd, J ¼ 17:1, 1.5 Hz), 4.92 (1H, dd,
J ¼ 10:0, 1.5 Hz), 3.66 (1H, ddd, J ¼ 10:5, 7.1, 4.8 Hz), 3.55 (1H,
ddd, J ¼ 10:5, 7.8, 6.3 Hz), 2.31 (1H, dt, J ¼ 10:0, 2.0 Hz), 1.79
(1H, dddd, J ¼ 14:9, 7.1, 6.3, 2.0 Hz), 1.67–1.58 (2H, m), 1.51–
1.39 (2H, m), 1.14–1.06 (12H, m). 13C NMR (100 MHz, CDCl3)
ꢂ 139.6, 135.1, 133.7, 128.7, 127.5, 127.3, 113.1, 62.6, 32.0,
27.6, 18.6, 18.5, 18.4, 18.3, 10.8, 10.6. IR (neat) 2963, 2860,
1626, 1427, 1105, 999, 819, 702, 632 cmꢁ1. MS(EI) m=z (%) =
267(30), 199(100), 181(10), 135(100), 105(80). Found: C, 73.98;
H, 10.63%. Calcd for C17H28OSi: C, 73.85; H, 10.21%.
3-(Triisopropylsilyl)pent-4-en-1-ol (4c): Colorless oil. Rf ¼
1
0:4 (hexane/EtOAc = 10/1). H NMR (400 MHz, CDCl3) ꢂ 5.83
(1H, ddd, J ¼ 17:1, 10.3, 10.1 Hz), 4.94 (1H, d, J ¼ 17:1 Hz),
4.90 (1H, dd, J ¼ 10:1, 1.8 Hz), 3.68 (1H, ddd, J ¼ 12:1, 6.0,
5.7 Hz), 3.58 (1H, ddd, J ¼ 12:1, 7.1, 5.5 Hz), 2.03 (1H, ddd, J ¼

976 Bull. Chem. Soc. Jpn. Vol. 80, No. 5 (2007)
Carbocyclization Reaction of Allylsilane
was added to a solution of sodium iodide (880.5 mg, 5.87 mmol)
in acetone (8 mL) at room temperature, and then, the reaction mix-
ture was refluxed for 5 h, was cooled down, and quenched by 5%
of sodium sulfite solution. The water layer was extracted with
EtOAc. The combined organic layer was washed with brine, dried
over anhydrous Na2SO4, and concentrated to dryness. Purification
of the crude mixture by silica-gel chromatography (hexane/
EtOAc = 30/1, v/v) gave 5a as a colorless oil (1.09 g, 3.29 mmol,
84%).
Colorless oil. Rf ¼ 0:6 (hexane/EtOAc = 30/1). 1H NMR
(400 MHz, CDCl3) ꢂ 7.49–7.46 (2H, m), 7.36–7.32 (3H, m),
5.49 (1H, ddd, J ¼ 16:3, 10.3, 9.0 Hz), 4.96 (1H, dd, J ¼ 10:3
1.7 Hz), 4.89 (1H, dd, J ¼ 16:3, 1.7 Hz), 3.26 (1H, ddd, J ¼ 9:3,
8.4, 3.9 Hz), 2.99 (1H, dt, J ¼ 9:3, 8.4 Hz), 1.96–1.83 (3H, m),
0.28 (3H, s), 0.27 (3H, s). 13C NMR (100 MHz, CDCl3) ꢂ 137.2,
136.7, 133.9, 129.1, 127.7, 127.7, 114.2, 35.9, 32.7, 7.8, ꢁ4:4,
ꢁ5:2. IR (neat) 3854, 2963, 2359, 1558, 1427, 1251, 1114, 904,
835, 814 cmꢁ1. MS(EI) m=z (%) = 315(10), 247(80), 203(30),
185(80), 159(70), 143(100), 121(80) 105(100). Found: C, 47.78;
H, 5.53%. Calcd for C13H19ISi: C, 47.27; H, 5.80%.
50 ꢂC for 30 min, and then, a solution of 5a (1.09 g, 3.30 mmol)
in THF (5 mL) was added to the reaction mixture. The reaction
mixture was refluxed for 4 h and quenched by 1 mol dmꢁ3 HCl so-
lution. The water layer was extracted with EtOAc. The combined
organic layer was successively washed with brine, dried over an-
hydrous Na2SO4, and concentrated to dryness. Purification of the
crude mixture by silica-gel chromatography (hexane/EtOAc =
10/1, v/v) gave 1a as colorless oil (888 mg, 2.65 mmol, 81%).
Colorless oil. Rf ¼ 0:3 (hexane/EtOAc = 10/1). 1H NMR
(400 MHz, CDCl3) ꢂ 7.47–7.45 (2H, m), 7.35–7.32 (3H, m), 5.57
(1H, ddd, J ¼ 17:1, 10.3, 9.5 Hz), 4.92 (1H, dd, J ¼ 10:3, 1.3 Hz),
4.82 (1H, ddd, J ¼ 17:1, 1.3, 1.0 Hz), 3.66 (3H, s), 3.65 (3H, s),
3.29 (1H, dd, J ¼ 8:4, 6.7 Hz), 2.03 (1H, dddd, J ¼ 13:9, 8.3,
5.6, 4.5 Hz), 1.78–1.68 (2H, m), 1.46–1.36 (2H, m), 0.26 (3H, s),
0.25 (3H, s). 13C NMR (100 MHz, CDCl3) ꢂ 169.6, 169.5, 138.6,
137.2, 133.9, 128.9, 127.5, 113.2, 52.3, 51.2, 34.0, 28.5, 26.0,
ꢁ4:5, ꢁ5:4. IR (neat) 2957, 1732, 1626, 1437, 1282, 1250, 1159,
1113, 902, 835, 767, 702 cmꢁ1. MS(EI) m=z (%) = 334(50),
279(100), 221(20), 151(100), 113(80). Found: C, 64.93; H, 7.97%.
Calcd for C18H26O4Si: C, 64.64; H, 7.83%.
[1-(2-Iodoethyl)allyl]diisopropylphenylsilane (5b): Color-
less oil. Rf ¼ 0:6 (hexane/EtOAc = 25/1). 1H NMR (400 MHz,
CDCl3) ꢂ 7.49–7.47 (2H, m), 7.36–7.35 (3H, m), 5.58 (1H, ddd,
J ¼ 17:1, 10.0, 10.0 Hz), 5.01 (1H, dd, J ¼ 17:1, 0.9 Hz), 4.98
(1H, dd, J ¼ 10:0, 0.9 Hz), 3.33 (1H, ddd, J ¼ 10:0, 6.8, 3.7 Hz),
3.07 (1H, dt, J ¼ 10:0, 7.9 Hz), 2.32 (1H, dt, J ¼ 10:0, 9.3 Hz),
2.00 (1H, ddt, J ¼ 11:6, 9.3, 7.9 Hz), 1.86–1.77 (1H, m), 1.50–
1.38 (2H, m), 1.13–1.06 (12H, m). 13C NMR (100 MHz, CDCl3)
ꢂ 137.6, 135.1, 133.4, 128.9, 127.6, 114.5, 32.7, 32.1, 18.6, 18.5,
18.4, 18.3, 10.8, 10.6, 8.5. IR (neat) 2891, 1427, 1107, 997, 883,
781, 702, 655 cmꢁ1. MS(EI) m=z (%) = 343(10), 275(30), 247(50),
233(10), 191(100), 149(80), 135(50), 121(80), 105(80). Found: C,
53.21; H, 7.41%. Calcd for C17H27ISi: C, 52.84; H, 7.04%.
[1-(2-Iodoethyl)allyl]triisopropylsilane (5c): Colorless oil.
Rf ¼ 0:6 (hexane/EtOAc = 30/1). 1H NMR (400 MHz, CDCl3) ꢂ
5.67 (1H, ddd, J ¼ 17:0, 10.1, 9.9 Hz), 4.98 (1H, dd, J ¼ 17:0, 1.8
Hz), 4.96 (1H, dd, J ¼ 10:1, 1.8 Hz), 3.37 (1H, ddd, J ¼ 9:5, 7.5,
3.8 Hz), 3.06 (1H, dt, J ¼ 9:5, 7.3 Hz), 2.26 (1H, ddd, J ¼ 9:9,
6.8, 1.3 Hz), 2.10–1.89 (2H, m), 1.18–0.93 (21H, m). 13C NMR
(100 MHz, CDCl3) ꢂ 138.7, 114.1, 33.0, 32.9, 18.7, 18.6, 11.1,
8.4. IR (neat) 3005, 2891, 1464, 1385, 1255, 1174, 1064, 1016,
904, 646 cmꢁ1. MS(EI) m=z (%) = 352(10), 309(80), 241(70),
213(50), 185(50), 171(50), 157(30) 111(50). Found: C, 47.01;
H, 7.72%. Calcd for C14H29ISi: C, 47.72; H, 8.30%.
t-Butyl[1-(2-iodoethyl)allyl]diphenylsilane (5d): Colorless
oil. Rf ¼ 0:6 (hexane/EtOAc = 25/1). 1H NMR (400 MHz,
CDCl3) ꢂ 7.65–7.59 (4H, m), 7.42–7.34 (6H, m), 5.64 (1H, ddd,
J ¼ 17:1, 10.0, 10.0 Hz), 5.07 (1H, dd, J ¼ 17:1, 0.9 Hz), 5.06
(1H, dd, J ¼ 10:0, 0.9 Hz), 3.28 (1H, ddd, J ¼ 9:8, 6.5, 3.8 Hz),
3.07 (1H, ddd, J ¼ 9:8, 9.5, 6.3 Hz), 2.56 (1H, dt, J ¼ 10:0,
1.8 Hz), 2.06 (1H, dddd, J ¼ 11:6, 9.5, 6.5, 2.6 Hz), 1.59 (1H,
dddd, J ¼ 11:6, 6.3, 3.8, 3.7 Hz), 1.09 (9H, s). 13C NMR (100
MHz, CDCl3) ꢂ 137.5, 136.5, 136.4, 133.5, 133.2, 129.2, 129.1,
127.5, 127.4, 116.0, 32.7, 31.8, 28.6, 19.4, 8.4. IR (neat) 2963,
2860, 1626, 1427, 1105, 999, 909, 820, 700, 632, 607, 517, 486
cmꢁ1. MS(EI) m=z (%) = 377(80), 309(100), 221(10), 183(10),
135(80), 105(30). Found: C, 58.34; H, 6.49%. Calcd for C21H27-
ISi: C, 58.06; H, 6.26%.
Dimethyl 2-[3-(Diisopropylphenylsilyl)pent-4-enyl]malo-
nate (1b):
Colorless oil. Rf ¼ 0:3 (hexane/EtOAc = 10/1).
1H NMR (400 MHz, CDCl3) ꢂ 7.47–7.44 (2H, m), 7.35–7.32
(3H, m), 5.67 (1H, ddd, J ¼ 17:6, 9.8, 9.8 Hz), 4.95 (1H, d, J ¼
17:6 Hz), 4.94 (1H, d, J ¼ 9:8 Hz), 3.69 (3H, s), 3.68 (3H, s),
3.33 (1H, t, J ¼ 7:6 Hz), 2.15–2.06 (2H, m), 1.76 (1H, ddt, J ¼
13:4, 10.0, 6.7 Hz), 1.59–1.36 (3H, m), 1.31–1.23 (1H, m), 1.11–
1.04 (12H, m). 13C NMR (100 MHz, CDCl3) ꢂ 169.7, 169.6,
138.9, 135.1, 133.7, 128.7, 127.5, 113.4, 52.3, 51.2, 30.9, 28.8,
26.6, 18.5, 18.5, 18.3, 18.2, 10.8, 10.5. IR (neat) 2946, 1728,
1626, 1437, 1383, 1282, 1157, 1107, 997, 902, 702, 655 cmꢁ1
.
MS(EI) m=z (%) = 390(10), 347(10), 190(50), 148(100), 135(50),
121(100). Found: C, 67.53; H, 8.90%. Calcd for C22H34O4Si: C,
67.65; H, 8.77%.
Dimethyl 2-[3-(Triisopropylsilyl)pent-4-enyl]malonate (1c):
Colorless oil. Rf ¼ 0:3 (hexane/EtOAc = 10/1). 1H NMR (400
MHz, CDCl3) ꢂ 6.02 (1H, ddd, J ¼ 18:8, 6.3, 6.3 Hz), 5.67 (1H,
dd, J ¼ 6:3, 1.7 Hz), 5.52 (1H, d, J ¼ 18:8 Hz), 3.74 (3H, s), 3.73
(3H, s), 3.40 (1H, t, J ¼ 7:6 Hz), 2.17 (1H, dt, J ¼ 8:1, 6.8 Hz),
2.00 (1H, dt, J ¼ 8:1, 7.3 Hz), 1.44 (1H, ddd, J ¼ 13:2, 7.6, 6.3
Hz), 1.17–1.10 (2H, m), 1.05–1.03 (21H, m). 13C NMR (100 MHz,
CDCl3) ꢂ 169.7, 139.8, 133.0, 52.4, 51.2, 28.5, 26.1, 18.8, 18.7,
16.3, 11.0, 10.8. IR (neat) 2892, 1732, 1460, 1437, 1340, 1280,
1197, 1159, 997, 902, 663 cmꢁ1. MS(EI) m=z (%) = 356(10),
313(20), 281(20), 157(80), 115(100), 87(80). Found: C, 64.21;
H, 10.51%. Calcd for C19H36O4Si: C, 64.00; H, 10.18%.
Dimethyl 2-[3-(t-Butyldiphenylsilyl)pent-4-enyl]malonate
(1d): Colorless oil. Rf ¼ 0:3 (hexane/EtOAc = 10/1). 1H NMR
(400 MHz, CDCl3) ꢂ 7.62 (2H, dd, J ¼ 7:2, 1.2 Hz), 7.55 (2H, dd,
J ¼ 7:2, 1.2 Hz), 7.41–7.32 (6H, m), 5.75 (1H, ddd, J ¼ 17:1,
10.3, 10.0 Hz), 5.00 (1H, d, J ¼ 10:3 Hz), 4.97 (1H, d, J ¼ 17:1
Hz), 3.64 (3H, s), 3.63 (3H, s), 3.25 (1H, t, J ¼ 7:6 Hz), 2.31
(1H, dt, J ¼ 10:0, 0.2 Hz), 2.10–2.00 (1H, m), 1.74 (1H, dddd,
J ¼ 13:2, 7.3, 6.8, 6.8 Hz), 1.61–1.53 (1H, m), 1.33–1.23 (1H, m),
1.07 (9H, s). 13C NMR (100 MHz, CDCl3) ꢂ 169.6, 136.6, 136.29,
134.0, 133.4, 128.8, 128.7, 127.6, 127.1, 115.0, 52.9, 51.7, 31.2,
29.2, 28.1, 27.0, 19.3. IR (neat) 2955, 1732, 1437, 1257, 1105,
906, 720, 702 cmꢁ1. MS(EI) m=z (%) = 438(5), 381(20), 239(20),
197(50), 135(100). Found: C, 71.18; H, 7.99%. Calcd for C26H34-
O4Si: C, 71.19; H, 7.81%.
Dimethyl 2-[3-(Dimethylphenylsilyl)pent-4-enyl]malonate
(1a). Dimethyl malonate (1.1 mL, 9.90 mmol) was added to a
suspension of sodium hydride (237.58 mg, 9.90 mmol) in THF
(10 mL) at 0 ꢂC. The reaction mixture was allowed to stir at
trans-Dimethyl 2-Methyl-3-(dimethylphenylsilyl)cyclopen-
tane-1,1-dicarboxylate (2a-trans). n-Bu3N (24 mL, 0.10 mmol)

S. Imazeki et al.
Bull. Chem. Soc. Jpn. Vol. 80, No. 5 (2007)
977
was added to a solution of 1a (34.0 mg, 0.10 mmol) in CH2Cl2
(0.5 mL) at room temperature. After the mixture was stirred for
2 h, AlCl3 (27.1 mg, 0.20 mmol) was added to the reaction mix-
ture, and the reaction mixture was stirred for 6 h. The reaction
was quenched by 1 mol dmꢁ3 HCl solution and the water layer
was extracted with EtOAc. The combined organic layers were
washed with sat. NaHCO3 and brine, dried over anhydrous
Na2SO4, and concentrated to dryness. Purification of the crude
mixture by silica-gel chromatography (hexane/EtOAc = 10/1,
v/v) gave 2a-trans as a colorless oil (9.7 mg, 0.029 mmol, 29%)
and 2a-cis as a colorless oil (1.0 mg, 0.003 mmol, 3%).
Colorless oil. Rf ¼ 0:3 (hexane/EtOAc = 10/1). 1H NMR
(400 MHz, CDCl3) ꢂ 7.51–7.49 (2H, m), 7.35–7.34 (3H, m),
3.68 (3H, s), 3.68 (3H, s), 2.58 (1H, dq, J ¼ 11:2, 6.8 Hz), 2.33
(1H, dt, J ¼ 13:4, 7.8 Hz), 2.00–1.84 (2H, m), 1.43 (1H, ddt, J ¼
11:8, 11.8, 8.5 Hz), 1.14 (1H, dt, J ¼ 12:7, 8.3 Hz), 0.88 (3H,
d, J ¼ 6:8 Hz), 0.32 (3H, s), 0.29 (3H, s). 13C NMR (100 MHz,
CDCl3) ꢂ 172.6, 171.7, 138.3, 133.6, 128.8, 127.6, 65.3, 52.5,
51.9, 43.2, 35.3, 32.9, 27.3, 17.6, ꢁ4:0, ꢁ4:1 IR(neat) 3071,
2955, 2845, 1726, 1458, 1381, 1251, 1201, 1155, 1111, 1080,
910, 833, 702 cmꢁ1. MS(EI) m=z (%) = 318(5), 278(80), 256(10),
135(100), 113(80). Found: C, 64.83; H, 8.24%. Calcd for C18H26-
O4Si: C, 64.64; H, 7.83%.
cis-Dimethyl 2-Methyl-3-(dimethylphenylsilyl)cyclopen-
tane-1,1-dicarboxylate (2a-cis): Colorless oil. Rf ¼ 0:3 (hex-
ane/EtOAc = 10/1). 1H NMR (400 MHz, CDCl3) ꢂ 7.54–7.51
(2H, m), 7.34–7.32 (3H, m), 3.68 (3H, s), 3.66 (3H, s), 3.02
(1H, dq, J ¼ 7:3, 7.3 Hz), 2.64 (1H, ddd, J ¼ 14:4, 9.0, 5.4 Hz),
2.00–1.84 (2H, m), 1.81–1.74 (1H, m), 1.33–1.24 (1H, m), 0.72
(3H, d, J ¼ 7:3 Hz), 0.34 (3H, s), 0.28 (3H, s). 13C NMR (100
MHz, CDCl3) ꢂ 173.0, 171.7, 138.8, 133.5, 128.7, 127.6, 66.7,
52.5, 52.3, 43.7, 32.4, 32.1, 24.4, 14.9, ꢁ2:3, ꢁ3:1. IR (neat)
3071, 2955, 2845, 1726, 1458, 1381, 1251, 1201, 1155, 1111,
1080, 910, 833, 702 cmꢁ1. MS(EI) m=z (%) = 318(5), 278(80),
256(10), 135(100), 113(80). Found: C, 64.61; H, 8.14%. Calcd
for C18H26O4Si: C, 64.64; H, 7.83%.
trans-Dimethyl 3-Diisopropylphenylsilyl-2-methylcyclopen-
tane-1,1-dicarboxylate (2b-trans): Colorless oil. Rf ¼ 0:3 (hex-
ane/EtOAc = 10/1). 1H NMR (400 MHz, CDCl3) ꢂ 7.51–7.48
(2H, m), 7.34–7.31 (3H, m), 3.71 (3H, s), 3.70 (3H, s), 2.77 (1H,
dq, J ¼ 11:7, 6.8 Hz), 2.65 (1H, ddd, J ¼ 13:9, 9.0, 4.9 Hz), 2.12–
2.03 (2H, m), 1.99–1.91 (1H, m), 1.61–1.56 (1H, m), 1.51–1.38
(2H, m), 1.12–1.04 (12H, m), 1.00 (3H, d, J ¼ 6:8 Hz). 13C NMR
(100 MHz, CDCl3) ꢂ 172.7, 171.9, 135.8, 135.1, 128.6, 127.3,
65.0, 52.4, 52.2, 43.9, 32.0, 29.6, 27.8, 19.0, 19.0, 18.9, 18.9,
17.1, 11.5, 11.4. IR (neat) 3020, 2401, 1726, 1477, 1220, 1045,
930, 750, 671 cmꢁ1. MS(EI) m=z (%) = 390(30), 346(100),
178(30), 151(50), 121(50), 107(20). Found: C, 67.79; H, 9.03%.
Calcd for C22H34O4Si: C, 67.65; H, 8.77%.
trans-Dimethyl 2-Methyl-3-triisopropylsilylcyclopentane-
1,1-dicarboxylate (2c-trans): Colorless oil. Rf ¼ 0:3 (hexane/
EtOAc = 10/1). 1H NMR (400 MHz, CDCl3) ꢂ 3.74 (3H, s), 3.73
(3H, s), 3.10 (1H, dq, J ¼ 6:5, 6.3 Hz), 2.09 (1H, ddd, J ¼ 14:4,
7.3, 7.1 Hz), 2.01–1.98 (1H, m), 1.83–1.74 (2H, m), 1.57 (3H, d,
J ¼ 6:5 Hz), 1.46–1.39 (1H, m), 1.20–1.05 (21H, m). 13C NMR
(100 MHz, CDCl3) ꢂ 169.6, 66.3, 52.3, 42.6, 31.7, 30.1,
26.0, 18.7, 17.7, 16.2, 12.4, 12.3. IR (neat) 3030, 2890, 1726,
1462, 1435, 1271, 1242, 1199, 1159, 1064, 883 cmꢁ1. MS(EI)
m=z (%) = 313(100), 281(30), 145(30), 117(50), 89(30), 75(50),
59(30). Found: C, 64.51; H, 10.38%. Calcd for C19H36O4Si: C,
64.00; H, 10.18%.
cis-Dimethyl 2-Methyl-3-triisopropylsilylcyclopentane-
1,1-dicarboxylate (2c-cis):
Colorless oil. Rf ¼ 0:3 (hexane/
EtOAc = 10/1). 1H NMR (400 MHz, CDCl3) ꢂ 3.70 (3H, s), 3.70
(3H, s), 3.40 (1H, dq, J ¼ 7:3, 3.4 Hz), 2.66 (1H, ddd, J ¼ 14:2,
10.3, 3.9 Hz), 2.30–2.00 (1H, m), 2.18 (1H, dt, J ¼ 7:6, 7.0 Hz),
1.95–1.89 (1H, m), 1.30–1.25 (1H, m), 1.31–1.03 (21H, m), 0.85
(3H, d, J ¼ 7:3 Hz). 13C NMR (100 MHz, CDCl3) ꢂ 173.2, 171.0,
66.3, 51.0, 50.9, 42.6, 28.8, 28.3, 25.6, 19.3, 17.7, 15.1, 10.8. IR
(neat) 3030, 2890, 1726, 1462, 1435, 1271, 1242, 1199, 1159,
1064, 883 cmꢁ1. MS(EI) m=z (%) = 313(100), 281(30), 145(30),
117(50), 89(30), 75(50), 59(30). Found: C, 64.21; H, 10.31%.
Calcd for C19H36O4Si: C, 64.00; H, 10.18%.
trans-Dimethyl 3-t-Butyldiphenylsilyl-2-methylcyclopen-
tane-1,1-dicarboxylate (2d-trans): Colorless oil. Rf ¼ 0:3 (hex-
ane/EtOAc = 10/1). 1H NMR (400 MHz, CDCl3) ꢂ 7.67 (2H, dd,
J ¼ 7:6, 1.5 Hz), 7.59 (2H, dd, J ¼ 7:6, 1.5 Hz), 7.34–7.28 (6H,
m), 3.72 (3H, s), 3.67 (3H, s), 2.69 (1H, dq, J ¼ 6:8, 5.8 Hz),
2.38–2.28 (1H, m), 1.97–1.91 (2H, m), 1.89–1.84 (1H, m), 1.12–
1.05 (1H, m), 1.08 (9H, s), 0.78 (3H, d, J ¼ 6:8 Hz). 13C NMR
(100 MHz, CDCl3) ꢂ 172.2, 171.8, 136.3, 136.2, 134.7, 128.9,
128.8, 127.4, 127.1, 64.7, 52.3, 51.8, 43.9, 35.3, 29.8, 28.8,
28.7, 22.6, 19.1, 17.9. IR (neat) 2955, 1726, 1471, 1242, 1157,
1105, 1078, 702, 607, 503 cmꢁ1. MS(EI) m=z (%) = 438(5),
381(100), 213(80), 183(50), 135(30), 105(20). Found: C, 71.32;
H, 8.04%. Calcd for C26H34O4Si: C, 71.19; H, 7.81%.
cis-Dimethyl 3-t-Butyldiphenylsilyl-2-methylcyclopentane-
1,1-dicarboxylate (2d-cis): Colorless oil. Rf ¼ 0:3 (hexane/
EtOAc = 10/1). 1H NMR (400 MHz, CDCl3) ꢂ 7.71 (2H, dd,
J ¼ 7:4, 1.8 Hz), 7.55 (2H, dd, J ¼ 7:4, 1.8 Hz), 7.40–7.33 (6H,
m), 3.75 (3H, s), 3.61 (3H, s), 3.29 (1H, dq, J ¼ 7:3, 6.0 Hz),
2.61 (1H, ddd, J ¼ 13:9, 10.6, 3.7 Hz), 2.24 (1H, ddd, J ¼ 13:9,
7.1, 5.6 Hz), 2.07 (1H, ddd, J ¼ 13:0, 9.2, 7.8 Hz), 2.02–1.91
(1H, m), 1.33–1.24 (1H, m), 1.09 (9H, s), 0.48 (3H, d, J ¼ 7:3
Hz). 13C NMR (100 MHz, CDCl3) ꢂ 173.2, 170.6, 136.3, 135.0,
128.8, 128.7, 127.4, 127.1, 66.4, 52.5, 52.2, 43.0, 32.0, 28.6,
28.4, 25.8, 18.8, 14.9. IR (neat) 2955, 1726, 1471, 1242, 1157,
1105, 1078, 702, 607, 503 cmꢁ1. MS(EI) m=z (%) = 438(5),
381(100), 213(80), 183(50), 135(30), 105(20). Found: C, 71.45;
H, 8.19%. Calcd for C26H34O4Si: C, 71.19; H, 7.81%.
cis-Dimethyl 3-Diisopropylphenylsilyl-2-methylcyclopen-
tane-1,1-dicarboxylate (2b-cis): Colorless oil. Rf ¼ 0:3 (hex-
ane/EtOAc = 10/1). 1H NMR (400 MHz, CDCl3) ꢂ 7.54–7.52
(2H, m), 7.34–7.31 (3H, m), 3.67 (3H, s), 3.65 (3H, s), 3.13 (1H,
dq, J ¼ 9:2, 7.3 Hz), 2.37 (1H, ddd, J ¼ 13:5, 8.2, 7.1 Hz), 1.99–
1.91 (2H, m), 1.83 (1H, ddd, J ¼ 9:2, 7.4, 5.2 Hz), 1.67–1.56 (1H,
m), 1.33–1.25 (2H, m), 1.20–0.95 (12H, m), 0.61 (3H, d, J ¼ 7:3
Hz). 13C NMR (100 MHz, CDCl3) ꢂ 173.3, 170.9, 135.1, 134.4,
128.5, 127.4, 66.4, 52.2, 51.8, 42.6, 35.4, 28.9, 25.3, 18.6, 18.5,
18.3, 15.2, 12.4, 12.0. IR (neat) 3020, 2401, 1726, 1477, 1220,
1045, 930, 750, 671 cmꢁ1. MS(EI) m=z (%) = 390(30), 346(100),
178(30), 151(50), 121(50), 107(20). Found: C, 67.82; H, 9.01%.
Calcd for C22H34O4Si: C, 67.65; H, 8.77%.
The authors are grateful to Drs. Takumi Tanaka and Kazuo
Shiraki for their helpful discussion. The authors also thank
Drs. Shigeru Kobayashi and Atsunori Sano for their advice
and encouragement.
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