Reactions of gem-dibromo compounds with trialkylmagnesate reagents to yield alkylated organomagnesium compounds

Article abstract of DOI:10.1002/1521-3765(20020402)8:7<1730::AID-CHEM1730>3.0.CO;2-6

The reaction of gem-dibromocyclopropanes 5 with nBu₃MgLi affords butylated cyclopropylmagnesium species that can be trapped with various electrophiles. The reaction of dibromomethylsilanes 12 requires the addition of a catalytic amount of CuCN · 2 LiCl for smooth migration of the alkyl groups. The resultant α-silylpentylmagnesium compounds 16 react with electrophiles, such as acyl chlorides or α, β-unsaturated ketones to afford α- or γ-silyl ketones, respectively. Treatment of dibromodisilylmethanes with Me₃MgLi yields 1-bromo- 1,1-disilylethanes 25 that can be converted into 1,1-disilylethenes 29 by dehydrobromination.

Full text of DOI:10.1002/1521-3765(20020402)8:7<1730::AID-CHEM1730>3.0.CO;2-6

FULL PAPER
Reactions of gem-Dibromo Compounds with Trialkylmagnesate Reagents to
Yield Alkylated Organomagnesium Compounds**
[a]
Atsushi Inoue,Junichi Kondo,Hiroshi Shinokubo,and Koichiro Oshima*
Abstract: The reaction of gem-dibromocyclopropanes 5 with nBu3MgLi affords
butylated cyclopropylmagnesium species that can be trapped with various electro-
philes. The reaction of dibromomethylsilanes 12 requires the addition of a catalytic
amount of CuCN ¥2LiCl for smooth migration of the alkyl groups. The resultant a-
silylpentylmagnesium compounds 16 react with electrophiles, such as acyl chlorides
or a,b-unsaturated ketones to afford a- or g-silyl ketones, respectively. Treatment of
dibromodisilylmethanes with Me3MgLi yields 1-bromo-1,1-disilylethanes 25 that can
be converted into 1,1-disilylethenes 29 by dehydrobromination.
Keywords:
carbenoids ¥ Grignard reagents ¥
magnesium ¥ migrations
ate complexes
¥
undergo 1,2-migration of the alkyl group on magnesium to the
adjacent carbon to form new organomagnesium reagents.
We started this research with the reaction of 1,1-dibro-
moalkane. Treatment of 1,1-dibromohexane (1) with nBu3-
MgLi followed by the addition of allyl bromide as an
electrophile yielded 4-butyl-1-nonene (3, 44%) as well as
5-bromodecane (4, 20%) and decenes (Scheme 2). This result
Introduction
The utility of organometallic ate complexes in organic syn-
thesis is well recognized, and numerous reports have been
published on the reaction which makes use of various ate
complexes that contain boron, copper, aluminum, zinc,
manganese, zirconium, and other metals as the key atoms.
Among reactions with ate complexes, the 1,2-migration of a
ligand on a metal is a representative reaction pattern of ate-
type carbenoids (Scheme 1).[1, 2] Organometallic ate com-
nC5H11
nBu
Br
nC5H11
nBu
nBu3MgLi
nC5H11CHBr2
MgnBu
1
2
3
44%
1
R1
R2
R3
M
R2
R3
R1
1,2-Migration
nC5H11
nBu
Decenes
–HBr
Br
20%
X
M
4
Scheme 1. 1,2-Migration of ate-type carbenoids.
Scheme 2. Reaction of 1,1-dibromohexane with nBu3MgLi.
indicates that bromine magnesium exchange and subsequent
1,2-migration of the butyl group affords the secondary
alkylmagnesium species 2. The coupling reaction of 2 with
allyl bromide provides 3. The magnesium compound 2 also
abstracts bromine from dibromoalkane to afford 4.
To eliminate the possibility of these side reactions, we chose
gem-dibromocyclopropanes and dibromomethylsilanes as
substrates and investigated their reactions with magnesate
reagents.
plexes also induce halogen metal exchange reactions.[3] The
combination of these two reactions enables a variety of
transformations starting from gem-dihalo compounds.[4, 5]
We have already reported the halogen magnesium ex-
8]
change reaction with magnesium ate complexes.[6 The
reaction proceeds at low temperatures of around À788C,
and hence the exchange reaction of gem-dibromoalkanes is
expected to provide ate-type carbenoid species that would
[a] Prof. Dr. K. Oshima, A. Inoue, J. Kondo, Dr. H. Shinokubo
Department of Material Chemistry
Results and Discussion
Graduate School of Engineering, Kyoto University
Kyoto 606-8501 (Japan)
Reaction of gem-dibromocyclopropanes: Cyclopropane de-
rivatives are versatile synthetic intermediates in organic
synthesis. Double alkylation of gem-dihalocyclopropanes,
Fax : (‡81)75-753-4863
E-mail: oshima@fm1.kuic.kyoto-u.ac.jp
[**] Preliminary accounts have already been published: Ref. [22].
1730
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Chem. Eur. J. 2002, 8, No. 7

1730 1740
Table 2. Reaction of bicyclic gem-dibromocyclopropanes with nBu3MgLi.
which can be readily prepared by the addition of dihalocar-
benes to olefins, provided an expeditious route to a variety of
functionalized cyclopropane derivatives. The reaction of gem-
dibromocyclopropanes with dialkylcuprates,[5a,b] alkyllith-
iums,[5c,d] trialkylzincates,[5e,f] or trialkylmanganates[5g,h] have
been reported to afford alkylated cyclopropylmetals, which
could undergo further reactions with various electrophiles,
such as alkyl halides and carbonyl compounds, to furnish
double-alkylated cyclopropane derivatives. We have found
that a magnesium ate complex (trialkylmagnesate) also
effects this type of alkylative metalation.
Treatment of various gem-dibromocyclopropanes 5 with
nBu3MgLi at low temperatures followed by the addition of
electrophiles afforded the expected products as diastereo-
meric mixtures (6 and 7). The results are summarized in
Tables 1 and 2.
Br
E
nBu
nBu3MgLi
E+
Br
nBu
E
+
THF, –78 °C → –30 °C
n
n
n
5e (n = 1)
5f (n = 3)
6
7
Entry Substrate Electrophile
Product Yield[%] Ratio 6:7
‡
1
2
3
4
5
6
7
8
9
5e
H3O
D2O
I2
6l/7l
6m/7m 82
81
63/37
63/37
61/39
73/27
88/12
27/73
58/42
64/36
6/94
6n/7n
6o/7o
6p/7p
6q/7q
6r/7r
6s/7s
6t/7t
91
89
88
42[d]
97
86
35[e]
43[f]
[a]
ˆ
CH2 CHCH2Br
PhCOCl[b]
PhCHO
‡
5 f
H3O
I2
PhCHO
PhCHO[c]
10
6t/7t
94/6
Several characteristics of this reaction are noteworthy:
1) The reaction should be performed at À788C to À308C.
Treatment of 5a with nBu3MgLi at 08C gave the desired
product in modest yield together with a significant amount
[a] In the presence of CuCN ¥2LiCl (30 mol%). [b] In the presence of
CuCN ¥2LiCl (3.0 equiv). [c] In the presence of CuCN ¥2LiCl (3.0 equiv)
and BF3 ¥OEt 2 (3.0 equiv). [d] The product 6l was also obtained in 47%
yield. [e] The product 6r was also obtained in 65%. [f] The products 6r and
7r were also obtained in 47% yield (45/55).
Table 1. Reaction of gem-dibromocyclopropanes with nBu3MgLi.
R
Br
R
E
R
nBu
nBu3MgLi
E+
+
Br
nBu
E
THF, –78 °C → –30 °C
of 1,2-nonadiene. On the other hand, 1,2-migration of a
butyl group did not go to completion at À788C. Quenching
of the reaction mixture at À788C provided 1-bromo-2-
hexylcyclopropane as a major product in addition to the
butylated product.
5
6
7
nC6H13
Br PhCH2OCH2
Br
Br
Ph
Br
Br
Br
Br
Br
5a
5b
5c
5d
Entry Substrate Electrophile
Product Yield[%] Ratio 6/7
2) A variety of electrophiles, such as iodine, allyl bromide,
methyl iodide, benzaldehyde, and benzoyl chloride, can be
employed. The use of allyl bromide as the electrophile
required the coexistence of CuCN ¥2LiCl. Without the
assistance of a copper salt, the intermediary tertiary
cyclopropylmagnesium failed to react with allyl bromide
because of steric hindrance.[9]
3) Stereoselectivities are somewhat lower than those ob-
served in the reactions mediated by cuprates, zincates, or
manganates. Interestingly, the reaction of 5e or 5 f with
nBu3MgLi followed by the addition of benzaldehyde
exhibited relatively high exo selectivity, although the yield
was not satisfactory (vide infra).
‡
1
2
3
5a
H3O
D2O
I2
6a/7a
6b/7b
6c/7c
6d/7d
6e/7e
6 f/7 f
6g/7g
6h/7h
6i/7i
6j
97
97
80
65
74
78
91
86
82
91
73
57/43
56/44
62/38
51/49
45/55
44/56
48/52
81/19
80/20
ˆ
4
5
CH2 CHCH2Br
MeI
6
7
8
PhCHO
‡
5b
5c
H3O
‡
H3O
[a]
[a]
ˆ
9
10
11
CH2 CHCH2Br
I2
5d
ˆ
CH2 CHCH2Br
6k
[a] In the presence of CuCN ¥2LiCl (30 mol%).
The use of 2,3-dialkyl-1,1-dibromocyclopropanes afforded
disappointing results (Scheme 3). Steric hindrance of alkyl
H3O+
R
R
Br
Br
R
R
H
nBu3MgLi
R
+
+
R
R
nBu
THF, –78 °C → –30 °C
R = nC5H11
5g
5h
6u/7u
60% (71/29)
8
34%
H3O+
R
Br
Br
R
nBu
nBu3MgLi
R
H
THF, –78 °C → –30 °C
R = nC5H11
R
R
6v
8
77%
6%
R
Br
H
+
R
9
11%
Scheme 3. Reaction of 2,3-dialkyl-1,1-dibromocyclopropanes.
Chem. Eur. J. 2002, 8, No. 7
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1731

K. Oshima et al.
FULL PAPER
substituents on the cyclopropane ring retards 1,2-migration of
the butyl group. In the reaction of 5g or 5h, migration of the
butyl moiety competed with the formation of allene 8.
We propose a similar reaction mechanism to the reactions
with cuprates, zincates, and manganates (Scheme 4). Firstly,
bromine magnesium exchange occurs predominantly at the
less hindered bromine atom to afford 10. Next, the butyl
We then investigated the reaction of dibromomethylsilanes
with trialkylmagnesate. The reaction promised to be a facile
method for the preparation of a-silylalkylmagnesium species,
which are highly useful reagents in organic synthesis.[11]
Treatment of dibromomethylsilane 12 with nBu3MgLi
induced clean bromine magnesium exchange[6] to provide
bromomethylsilane 15 upon quenching with methanol at
À788C (Scheme 7). Warming the reaction mixture to room
R
Br
Br
R
Br
R
MgnBu
nBu
R
E
E+
R3Si
MgnBu2Li
R3Si
H
MeOH
nBu3MgLi
nBu3MgLi
R3SiCHBr2
MgnBuLi
nBu
–78 °C
10 min
–78 °C
Br
Br
15b 89%
12b
nBu
CuCN•2LiCl
(30 mol%)
–78 °C → 0 °C
5
10
11
6
R3Si = Ph2MeSi
Scheme 4. Proposed mechanism of the reaction of gem-dibromocyclopro-
panes with nBu3MgLi.
R3Si
MgnBu
R3Si
H
MeOH
nBu
nBu
17b 75%
16b
group on magnesium migrates to the adjacent carbon atom
with concomitant elimination of the bromide ion and
inversion of the configuration on the cyclopropane carbon.
The resultant butylated cyclopropylmagnesium species 11 is
eventually trapped by an electrophile with retention of
configuration. The inverse stereoselectivity and the low yield
in trapping with benzaldehyde are attributed to the low
reactivity of the major diastereomer 11-endo (Scheme 5). The
Scheme 7. Bromine magnesium exchange and the subsequent migration
of an alkyl group.
temperature before quenching resulted in the migration of the
butyl group to yield a-silylpentylmagnesium 16.[12] A copper
salt proved to facilitate this migration.[1a] The addition of
CuCN ¥2LiCl (30 mol%) to the reaction mixture induced
smooth migration of the butyl group at lower temperatures
(À308C for 12a and 08C for 12b) to afford 16 in good yield.
Butyllithium or nBuMgBr instead of tributylmagnesate also
induced metalation and the subsequent butylation. Under
these conditions, however, the yields of the desired products
were quite low.
Ph
OH
MgnBu
nBu
PhCHO
PhCHO
nBu
11e-endo
nBu
6q
nBu
The a-silylpentylmagnesium 16 could be trapped with allyl
bromide to give 18 in good yield (Scheme 8). The reaction
with propargyl bromide furnished exclusively the allenylated
product 19.
Ph
OH
MgnBu
11e-exo
7q
Scheme 5. Difference in the reaction between PhCHO and the endo or exo
isomers of 11e.
Br
Br
R3Si
R3Si
MgnBu
R3Si
nBu
19
nBu
16
nBu
18
magnesium species 11-endo fails to react with benzaldehyde
and gives 6l or 6r after protonation. On the other hand, the
other isomer, 11-exo, is trapped with benzaldehyde to provide
the cyclopropylbenzyl alcohol derivative.
R3Si= tBuMe2Si
Ph2MeSi
18a : 67%
18b: 79%
18c : 61%
R3Si = tBuMe2Si 19a : 66%
PhMe2Si
Me
Si
18d: 80%
Copper(i)-catalyzed reaction of dibromomethylsilanes: We
have previously reported synthesis of 1-alkenylsilanes 14 from
dibromomethylsilanes 12[10] via manganese carbenoids
(Scheme 6).[5i,j] In this reaction, a-silylalkylmanganese 13
cannot be coupled with electrophiles because of its rapid
conversion to alkenylsilane 14 by b-hydride elimination.
2
Scheme 8. Reaction of a-silylalkylmagnesium compounds 16 with allyl or
propargyl bromide.
a-Silyl ketones are quite useful intermediates in organic
synthesis.[13] Therefore, we undertook the preparation of a-
silyl ketones with this new methodology.[14] The reaction of a-
silylalkylmagnesium comopunds 16 with various acyl chlo-
rides was examined.[15] The results are summarized in Table 3.
The addition of acyl chlorides to the resulting solution of 16
furnished the corresponding a-silyl ketones 20 in good yields.
1,3-Dimethyl-2-imidazolidinone (DMI) proved to be an
effective additive for the formation of a-silyl ketones. Without
the use of DMI, the yield of product decreased (entry 7).
R3Si
MnnBu2Li
nBu3MnLi
R3SiCHBr2
Br
12
R3Si
nBu
β-elimination
nBuMnH
R3Si
nPr
MnnBu
14
13
Scheme 6. Reaction of dibromomethylsilanes 12 with tributylmanganate.
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Alkylated Organomagnesium Compounds
1730 1740
Table 3. Synthesis of a-silyl ketones from dibromomethylsilanes.[a]
1) CuCN•2LiCl
(20 mol%)
R3Si
MgsBu
R3Si
E
sBu3MgLi
O
R3SiCHBr2
R3Si
MgR1
R3Si
1) R13MgLi
R2COCl
DMI
2) Electrophile
R2
sBu
16
sBu
R3SiCHBr2
12b
24
2) cat. CuCN•2LiCl
R1
16
R1
20
R3Si = Ph2MeSi
12
Br
Electrophile =
24a : 75% cPrCOCl 24d : 74%
Entry Substrate R3Si
R1 R2
Product Yield[%]
PhCOCl
nPrCOCl 24b : 72%
iPrCOCl 24c : 65%
24e : 71%
1
2
3
4
5
12a
12b
tBuMe2Si nBu CH3
20a
20b
20c
60
56
66
53
51
63
49
74
63
69
77
cPr
Ph
Scheme 10. Reaction of dibromomethylsilanes 12 with sBu3MgLi.
ˆ
(E)-CH3CH CH- 20d
(E)-PhCH CH- 20e
ˆ
Reaction of dibromomethylsilanes with Me3MgLi: The reac-
tion of dibromomethylsilane 12b with Me3MgLi gave a
different result from the reaction of nBu3MgLi. One of the
two bromine atoms was substituted by the methyl group. This
monomethylation reaction was successfully applied to dibro-
modisilylmethanes.[17] The results are summarized in Table 4.
6
7
Ph2MeSi nBu CH3
20 f
20g
20g
20h
20i
20j
85
nPr
nPr
iPr
cPr
Ph
8[b]
9[b]
10[b]
11[b]
12[b, c]
13[c]
nC6H13
nPr 20k
Ph
20l
70
Table 4. Monomethylation of dibromodisilylmethanes with Me3MgLi.[a]
[a] Reaction conditions: Magnesate was prepared from butyllithium
(2.0 mmol) and butylmagnesium bromide (1.0 mmol) in THF (5 mL) at
08C. Dibromomethylsilanes (1.0 mmol) in THF (2 mL) were introduced at
À788C. CuCN ¥2LiCl (0.3 mL, 1.0 m solution in THF, 0.3 mmol) was
added. [b] DMI (2.0 mmol) was added before introduction of acyl
chlorides. [c] Magnesate was prepared from hexyllithium (3.0 mmol) and
MgBr2 (1.0 mmol) in THF (5 mL) at 08C.
R1
Br Br
12
R2
R1
R2
Me3MgLi (1.0 equiv)
THF, –78 °C, 0.5 h
Me Br
25
Entry
Substrate
R1
R2
Product
Yield[%]
1
2
3
4
5
6
7
8
9
12a
12e
12 f
12g
12h
12i
12j
12k
12l
Ph2MeSi
Ph2MeSi
Ph2MeSi
Et3Si
tBuMe2Si
Me3Si
PhMe2Si
Ph2MeSi
Ph2MeSi
H
Me
Me3Si
Et3Si
Me3Si
Me3Si
PhMe2Si
Ph2MeSi
Et3Ge
25a
25e
25 f
25g
25h
25i
25j
25k
25l
98
89
93
90
82
89
80
90
93
We also explored the conjugate addition of 16 to a,b-
unsaturated ketones (Scheme 9). Addition of methyl vinyl
ketone to the solution of 16 provided 5-silyl-2-nonanones 21a
and 21b in good yields in the presence of Me3SiCl.[16] The
[a] The substrate 12 (10 mmol) was treated with Me3MgLi, prepared by
mixing MeMgBr (THF solution, 10 mmol) and MeLi (Et2O solution,
20 mmol), for 0.5 h in THF at À788C.
O
O
R3Si
MgnBu
R3Si
1) nBu3MgLi
R3SiCHBr2
Substrates such as dibromomethylsilane (entry 1), 1,1-
dibromoethylsilane (entry 2), and dibromodisilylmethanes
(entries 3 8) could be converted into the corresponding
monomethylated compounds 25 in good yields, regardless of
the bulkiness of silyl substituents. Methylation of germylsil-
yldibromomethane also proceeded in good yield (entry 9).
We propose the following mechanism[18] that involves the
formation of the ate-type carbenoid species 26 through a
bromine magnesium exchange reaction (Scheme 11).[5, 6]
Me3SiCl
2) cat. CuCN•2LiCl
nBu
16
nBu
R3Si = tBuMe2Si 21a : 67%
Ph2MeSi
12
21b: 79%
O
O
Me3SiCl
O
Me3SiCl
O
tBuMe2Si
tBuMe2Si
nBu
23 54% (67/33)
nBu
R1
Br Br
12
R2
R2
R1
R2
Me3MgLi
22 59% (86/14)
–MeBr
Br MgMe2Li
LiBr
R2
Scheme 9. 1,4-Addition of a-silylalkylmagnesium compounds 16 toward
26
enones.
R1
R1
Me Br
25
addition of 16 to cyclohexenone or cyclopentenone also
furnished the desired silylketones.
Me MgMe
27
R1
R2
In the case of tri(sec-butyl)magnesate, which was prepared
from sBuLi (3.0 equiv) and MgBr2 (1.0 equiv), the migration
of the secondary butyl group afforded the corresponding a-
silylalkylmagnesium 16 smoothly without the assistance of a
copper catalyst (Scheme 10). However, the addition of
CuCN ¥2LiCl was beneficial for the acylation or allylation
step to provide the coupling products 24 in good yields.
Br Br
Me3MgLi
12
R1
R2
Me MgMe2Li
Me2Mg
28
Scheme 11. Plausible mechanism of monomethylation.
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1733

K. Oshima et al.
FULL PAPER
Synthesis of gem-dibromocyclopropanes 5: Aqueous sodium hydroxide
(10 mL, 50 w/w%) was added dropwise to a mixture of an alkene
(20 mmol), bromoform (2.6 mL, 30 mmol), benzyltriethylammonium chlo-
ride (0.1 g), dichloromethane (2 mL), and ethanol (0.08 mL) at 08C. After
stirring for 24 h, water was added (50 mL). The mixture was extracted with
hexane and the organic layers were dried over anhydrous Na2SO4 and
concentrated in vacuo. Purification by chromatography on a silica gel
column gave provided gem-dibromocyclopropanes 5.
The 1,2-migration of one of the methyl groups on magnesium
provides 27 with concomitant elimination of the bromide
anion. One of methyl groups in Me3MgLi is transferred to 27
to form the ate complex 28, which is more reactive than
Me3MgLi for the bromine magnesium exchange reaction.
The complex 28 abstracts the bromine atom from 12 to yield
the monobromo compound 25 and the carbenoid 26.
1,1-Dibromo-2-hexylcyclopropane (5a): Rf ˆ 0.71 (hexane); IR (neat): nÄ ˆ
2922, 2852, 1111, 1042, 677 cmÀ1; 1H NMR (CDCl3): d ˆ 0.89 (t, J ˆ 6.9 Hz,
3H), 1.18 (dd, J ˆ 6.9, 7.2 Hz, 1H), 1.23 1.67 (m, 11H), 1.73 (dd, J ˆ 6.9,
9.9 Hz, 1H); 13C NMR (CDCl3): d ˆ 14.1, 22.6, 28.3, 28.5, 29.0, 29.7, 31.5,
31.7, 32.6; elemental analysis calcd (%) for C9H16Br2: C 38.06, H 5.68;
found: C 37.77, H 5.44.
The resultant monomethylated products were converted
into the corresponding 1,1-disilylethenes by dehydrobromi-
nation.[19, 20] Treatment of 25 with two equivalents of 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU) in DMF at 908C for
eight hours provided 1,1-disilylethenes 29 (Table 5). In each
case, the desired product was obtained in good yield.
2-(Benzyloxymethyl)-1,1-dibromocyclopropane (5b): Rf ˆ 0.42 (hexane/
ethyl acetate 10:1); IR (neat): nÄ ˆ 3026, 2856, 1496, 1454, 1372, 1155,
1094, 1029, 735, 696, 680 cmÀ1
;
1H NMR (CDCl3): d ˆ 1.37 (dd, J ˆ 7.2,
7.5 Hz, 1H), 1.80 (dd, J ˆ 7.2, 10.5 Hz, 1H), 1.89 2.01 (m, 1H), 3.58 (dd,
J ˆ 7.2, 10.8 Hz, 1H), 3.63 (dd, J ˆ 5.7, 10.8 Hz, 1H), 4.57 (d, J ˆ 12.0 Hz,
1H), 4.61 (d, J ˆ 12.0 Hz, 1H), 7.26 7.40 (m, 5H); 13C NMR (CDCl3): d ˆ
26.0, 26.6, 30.2, 71.5, 73.0, 127.9, 127.9, 128.5, 138.1; elemental analysis calcd
(%) for C11H12Br2O: C 41.28, H 3.78; found: C 41.11, H 3.71.
Table 5. Dehydrobromination of 25 with DBU.[a]
R1
Me Br
25
R2
R1
R2
DBU (2.0 equiv)
DMF, 90 °C, 8 h
1,1-Dibromo-2-phenylcyclopropane (5c): Rf ˆ 0.41 (hexane); IR (neat):
29
nÄ ˆ 1605, 1498, 1452, 1425, 1108, 1040, 766, 734, 696, 679 cmÀ1
;
1H NMR
Entry
Substrate
R1
R2
Product
Yield[%]
(CDCl3): d ˆ 2.02 (dd, J ˆ 7.8, 8.4 Hz, 1H), 2.14 (dd, J ˆ 7.8, 10.5 Hz, 1H),
2.97 (dd, J ˆ 8.4, 10.5 Hz, 1H), 7.22 7.30 (m, 2H), 7.30 7.40 (m, 3H);
13C NMR (CDCl3): d ˆ 27.2, 28.3, 35.9, 127.7, 128.4, 129.0, 136.1; elemental
analysis calcd (%) for C9H8Br2: C 39.17, H 2.92; found: C 39.02, H 3.03.
1
2
3
4
5
6
7
25 f
25g
25h
25i
25j
25k
25l
Ph2MeSi
Et3Si
tBuMe2Si
Me3Si
PhMe2Si
Ph2MeSi
Ph2MeSi
Me3Si
Et3Si
Me3Si
Me3Si
PhMe2Si
Ph2MeSi
Et3Ge
29 f
29g
29h
29i
29j
29k
29l
98
98
85
83
97
89
85
1,1-Dibromo-2,2,3,3-tetramethylcyclopropane (5d): IR (Nujol): nÄ ˆ 1105,
1031, 994, 952, 863, 792, 774 cmÀ1
;
1H NMR (CDCl3): d ˆ 1.25 (s, 12H);
13C NMR (CDCl3) d ˆ 21.7, 29.7, 58.9. We were not able to perform an
analysis on this compound because of its sublimation.
7,7-Dibromobicyclo[4.1.0]heptane (5e): Rf ˆ 0.72 (hexane); IR (neat): nÄ ˆ
[a] A solution of 25 (9.0 mmol) and DBU (18.0 mmol) in DMF (30 mL) was
stirred for 8 h at 908C.
1
2936, 2852, 1462, 1444, 1334, 1165, 1020, 729 cmÀ1; H NMR (CDCl3): d ˆ
1.00 1.25 (m, 2H), 1.30 1.43 (m, 2H), 1.50 1.62 (m, 2H), 1.76 1.90 (m,
2H), 1.92 2.07 (m, 2H); 13C NMR (CDCl3): d ˆ 20.1, 20.6, 27.0, 40.7;
elemental analysis calcd (%) for C7H10Br2: C 33.11, H 3.97; found: C 33.20,
H 3.95.
Conclusion
9,9-Dibromobicyclo[6.1.0]nonane (5 f): Rf ˆ 0.69 (hexane); IR (neat): nÄ ˆ
2920, 2848, 1467, 1164, 1060, 858, 815, 760, 710 cmÀ1; 1H NMR (CDCl3): d ˆ
1.07 1.25 (m, 2H), 1.30 1.70 (m, 10H), 2.00 2.10 (m, 2H); 13C NMR
(CDCl3): d ˆ 25.3, 26.3, 27.8, 33.2, 37.0; elemental analysis calcd (%) for
C9H14Br2: C 38.33, H 5.00; found: C 38.28, H 4.83.
We have investigated the reactions of gem-dibromo com-
pounds with trialkylmagnesate reagents (R3MgLi). The
halogen magnesium exchange reaction and subsequent 1,2-
migration of the alkyl group on magnesium affords the
alkylated organomagnesium species in the presence or
absence of a copper catalyst. The resultant organomagnesium
species can be trapped with a variety of electrophiles.
Trimethylmagnesate (Me3MgLi) shows a different reactivity.
The reagent induces monomethylation of dibromomethylsi-
lanes or dibromodisilylmethanes.
cis-1,1-Dibromo-2,3-dipentylcyclopropane (5g): Rf ˆ 0.80 (hexane); IR
1
(neat): nÄ ˆ 2952, 2922, 2854, 1466, 1379, 716 cmÀ1; H NMR (CDCl3): d ˆ
0.90 (t, J ˆ 6.9 Hz, 6H), 1.24 1.59 (m, 18H); 13C NMR (CDCl3): d ˆ 13.9,
22.5, 26.9, 28.1, 31.6, 33.8, 38.3; elemental analysis calcd (%) for C13H24Br2:
C 45.91, H 7.11; found: C 46.02, H 6.99.
trans-1,1-Dibromo-2,3-dipentylcyclopropane (5h): Rf ˆ 0.83 (hexane); IR
(neat): nÄ ˆ 2952, 2924, 2854, 1466, 1379, 1137, 1046, 722 cmÀ1
;
1H NMR
(CDCl3): d ˆ 0.90 (t, J ˆ 6.9 Hz, 6H), 1.01 1.11 (m, 2H), 1.24 1.52 (m,
14H), 1.52 1.68 (m, 2H); 13C NMR (CDCl3): d ˆ 13.9, 22.5, 27.9, 31.4, 32.6,
37.0, 39.4; elemental analysis calcd (%) for C13H24Br2: C 45.91, H 7.11;
found: C 46.01, H 6.84.
General procedure for the reaction of gem-dibromocyclopropanes 5 with
nBu3MgLi: Butyllithium (1.5 mL, 1.6m solution in hexane, 2.4 mmol) was
added to a solution of butylmagnesium bromide (1.2 mL, 1.0m solution in
THF, 1.2 mmol) in THF (5 mL) at 08C, and the mixture was stirred for
10 min. The resulting solution was cooled to À788C, and a solution of the
corresponding 5 (1.0 mmol) in THF (2 mL) was added dropwise. After the
reaction mixture was gradually warmed to À308C over a period of 2 h, the
corresponding electrophile (3.0 mmol) was added. After stirring for 1 h at
08C, the reaction was quenched with saturated aqueous NH4Cl. The
mixture was extracted with ethyl acetate, and the organic layers were dried
over anhydrous Na2SO4 and concentrated in vacuo. Purification by
chromatography on a silica gel column provided 6 and 7 as diastereomeric
mixtures.
Experimental Section
General: 1H NMR (300 MHz) and 13C NMR (75.3 MHz) spectra were
recorded on a Varian GEMINI300 spectrometer in CDCl3 as a solvent, and
chemical shifts were given in d with tetramethylsilane as an internal
standard. IR spectra were determined on a JASCO IR-810 spectrometer.
TLC analyses were performed on commercial glass plates bearing 0.25 mm
layer of Merck silica gel 60F254. Column chromatography was performed on
silica gel (Wakogel 200 mesh). The analyses were carried out at the
Elemental Analysis Center of Kyoto University. Tetrahydrofuran (THF)
was freshly distilled from sodium/benzophenone before use. Grignard
reagents were prepared from the corresponding alkyl halide and Mg
turnings (Nacalai tesque, INC). Unless otherwise noted, materials obtained
from commercial suppliers were used without further purification.
Aldehydes were distilled and stored under argon.
Spectral data for 6a, 7a, 6e, 7e, 6h, 7h,[4b] 6 f, 7 f, 6g, 7g, 6l, 7l,[4e] 6c, 7c, 6d,
7d, 6i, 7i, 6o, 7o, 6t, 7t,[4g] 6r, and 7r[21] were identical with those reported
1734
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0807-1734 $ 20.00+.50/0
Chem. Eur. J. 2002, 8, No. 7

Alkylated Organomagnesium Compounds
1730 1740
in the literature. Alcohols (6 f, 7 f, 6q, 7q, 6t, and 7t) were converted into
the corresponding ketones by Jones oxidation for data collection.
28.4, 29.3, 29.9, 31.7, 31.8, 32.5, 34.5; elemental analysis calcd (%) for
C17H34: C 85.63, H 14.37; found: C 85.68, H 14.62.
Synthesis of dibromomethylsilanes 12: The solution of LDA (lithium
diisopropylamide) was prepared by the slow addition of butyllithium
(39 mL, 1.6m solution in hexane, 62 mmol) to a solution of diisopropyl-
amine (8.8 mL, 63 mmol) in THF (40 mL) at 08C. The resulting solution
was added to a solution of dibromomethane (4.2 mL, 60 mmol) and
trialkylchlorosilane (60 mmol) in THF (50 mL) dropwise at À788C. After
stirring for 0.5 h at À788C, the resulting mixture was poured into 1m HCl
and extracted with hexane. The combined organic layers were dried over
anhydrous Na2SO4 and concentrated in vacuo. Purification by silica-gel
column chromatography provided 12a d. Spectral data for 12a,[9b] 12b,
and 12d[4i] were identical with those reported in the literature.
1-Butyl-1-iodo-2,2,3,3-tetramethylcyclopropane (6j): Rf ˆ 0.83 (hexane);
1
IR (neat): nÄ ˆ 2942, 2864, 1460, 1378, 1105, 1005, 935, 828 cmÀ1; H NMR
(CDCl3): d ˆ 0.92 (t, J ˆ 7.2 Hz, 3H), 1.05 (s, 6H), 1.23 (s, 6H), 1.32 (tq, J ˆ
7.5, 7.2 Hz, 2H), 1.47 1.60 (m, 2H), 1.74 1.81 (m, 2H); 13C NMR (CDCl3):
d ˆ 14.1, 16.7, 22.4, 25.8, 28.6, 33.4, 39.0, 49.9. This compound is very
sensitive to light or a trace of acid, and we were not able to perform an
analysis or mass spectrometry.
1-Allyl-1-butyl-2,2,3,3-tetramethylcyclopropane (6k): Rf ˆ 0.89 (hexane);
IR (neat): nÄ ˆ 2996, 2924, 2870, 1640, 1468, 1379, 1110, 994, 909 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.87 (t, J ˆ 6.9 Hz, 3H), 0.98 (s, 6H), 0.99 (s, 6H),
1.15 1.36 (m, 6H), 2.13 (d, J ˆ 6.6 Hz, 2H), 4.98 (d, J ˆ 10.2 Hz, 1H), 5.00
(d, J ˆ 17.1 Hz, 1H), 5.71 (ddt, J ˆ 10.2, 17.1, 6.6 Hz, 1H); 13C NMR
(CDCl3): d ˆ 14.1, 18.6, 18.7, 22.9, 23.3, 27.5, 28.7, 29.1, 32.4, 115.2, 138.4;
elemental analysis calcd (%) for C14H26: C 86.52, H 13.48; found: C 86.50,
H 13.78.
(Dibromomethyl)dimethylphenylsilane (12c): Rf ˆ 0.40 (hexane/ethyl ace-
tate 80:1); IR (neat): nÄ ˆ 2968, 1427, 1252, 1117, 820, 787, 735, 698, 644,
617 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.57 (s, 6H), 5.25 (s, 1H), 7.35 7.50 (m,
3H), 7.60 7.65 (m, 2H); 13C NMR (CDCl3): d ˆ À5.0, 35.2, 128.0, 130.3,
133.9, 134.6; elemental analysis calcd (%) for C9H12Br2Si: C 35.09, H 3.93;
found: C 35.32, H 3.74.
endo-7-Butyl-7-iodobicyclo[4.1.0]heptane (6n): Rf ˆ 0.80 (hexane); IR
(neat): nÄ ˆ 2924, 2852, 1461, 1444, 1378, 1170, 1124, 819 cmÀ1
;
1H NMR
General procedure for the preparation of 1-silylpentylmagnesium species
and its reaction with electrophiles: Butyllithium (1.2 mL, 1.6m solution in
hexane, 2.0 mmol) was added to a solution of butylmagnesium bromide
(1.0 mL, 1.0m solution in THF, 1.0 mmol) in THF (5 mL) at 08C, and the
mixture was stirred for 10 min. The resulting solution was cooled to À788C,
and a solution of 12 (1.0 mmol) in THF (2 mL) was added dropwise. After
the mixture was stirred for 10 min, CuCN ¥2LiCl (0.3 mL, 1.0 m solution in
THF, 0.3 mmol) was added, and the mixture was allowed to gradually warm
to À308C over a period of 2 h. Allyl bromide (0.26 mL, 3.0 mmol) was
added at À308C. After stirring for 1 h at 08C, the reaction was quenched
with saturated aqueous NH4Cl. The mixture was extracted with hexane,
and the organic layers were dried over anhydrous Na2SO4 and concen-
trated in vacuo. Purification by silica-gel column chromatography provided
18.
(CDCl3): d ˆ 0.66 0.77 (m, 2H), 0.90 (t, J ˆ 7.2 Hz, 3H), 1.12 1.40 (m,
6H), 1.40 1.59 (m, 4H), 1.59 1.67 (m, 2H), 2.02 2.16 (m, 2H); 13C NMR
(CDCl3): d ˆ 14.1, 20.7, 21.2, 21.9, 23.9, 31.7, 39.3, 47.8; elemental analysis
calcd (%) for C11H19I: C 47.49, H 6.88; found: C 47.27, H 6.90.
exo-7-Butyl-7-iodobicyclo[4.1.0]heptane (7n): Rf ˆ 0.74 (hexane); IR
(neat): nÄ ˆ 2918, 2854, 1467, 1450, 1378, 1209, 1168, 1112, 1049, 926,
748 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.94 (t, J ˆ 7.2 Hz, 3H), 1.08 1.42 (m,
6H), 1.42 1.60 (m, 8H), 1.76 1.92 (m, 2H); 13C NMR (CDCl3): d ˆ 14.1,
18.6, 21.7, 22.3, 24.5, 28.8, 32.4, 35.2; elemental analysis calcd (%) for
C11H19I: C 47.49, H 6.88; found: C 47.20, H 6.86.
endo-7-Benzoyl-7-butylbicyclo[4.1.0]heptane (6p): Rf ˆ 0.61 (hexane/ethyl
acetate 10:1); IR (neat): nÄ ˆ 2928, 2854, 1674, 1598, 1449, 1354, 1215, 1174,
935, 713, 690 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.78 (t, J ˆ 6.9 Hz, 3H), 0.84
1.00 (m, 2H), 1.06 1.32 (m, 8H), 1.53 1.62 (m, 2H), 1.74 1.94 (m, 4H),
7.41 7.51 (m, 2H), 7.51 7.58 (m, 1H), 8.02 8.08 (m, 2H); 13C NMR
(CDCl3): d ˆ 13.8, 20.7, 21.3, 21.3, 22.4, 29.4, 35.0, 40.5, 128.5, 129.6, 132.7,
137.1, 201.1; elemental analysis calcd (%) for C18H24O: C 84.32, H 9.44;
found: C 84.56, H 9.64.
(Bromomethyl)methyldiphenylsilane (15b): Rf ˆ 0.37 (hexane/ethyl acetate
40:1); IR (neat): nÄ ˆ 2928, 1428, 1385, 1254, 1115, 999, 804, 765, 733,
696 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.75 (s, 3H), 2.93 (s, 2H), 7.36 7.48 (m,
6H), 7.55 7.60 (m, 4H); 13C NMR (CDCl3): d ˆ À5.2, 14.7, 128.1, 130.0,
134.5, 134.7; elemental analysis calcd (%) for C14H15BrSi: C 57.73, H 5.19;
found: C 57.72, H 5.18.
exo-7-Benzoyl-7-butylbicyclo[4.1.0]heptane (7p): Rf ˆ 0.54 (hexane/ethyl
acetate 10:1); IR (neat): nÄ ˆ 2926, 2856, 1673, 1448, 1270, 1212, 1020,
Methylpentyldiphenylsilane (17b): Rf ˆ 0.49 (hexane/ethyl acetate 80:1);
IR (neat): nÄ ˆ 2918, 1428, 1251, 784, 729, 697 cmÀ1; 1H NMR (CDCl3): d ˆ
0.55 (s, 3H), 0.85 (t, J ˆ 6.9 Hz, 3H), 1.07 (t, J ˆ 8.0 Hz, 2H), 1.20 1.38 (m,
6H), 7.31 7.40 (m, 6H), 7.49 7.56 (m, 4H); 13C NMR (CDCl3): d ˆ À4.6,
13.9, 14.0, 22.1, 23.4, 35.8, 127.8, 129.1, 134.6, 137.7; elemental analysis calcd
(%) for C18H24Si: C 80.53, H 9.01; found: C 80.44, H 8.85.
710 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.73 (t, J ˆ 6.9 Hz, 3H), 1.08 1.22 (m,
4H), 1.24 1.46 (m, 4H), 1.50 1.64 (m, 4H), 1.71 1.80 (m, 2H), 1.96 2.12
(m, 2H), 7.42 (dd, J ˆ 6.6, 7.2 Hz, 2H), 7.50 (t, J ˆ 7.2 Hz, 1H), 7.78 (d, J ˆ
6.6 Hz, 2H); 13C NMR (CDCl3): d ˆ 13.7, 18.4, 18.6, 22.0, 22.8, 26.5, 29.4,
37.2, 128.3, 128.4, 131.8, 137.6, 204.5; elemental analysis calcd (%) for
C18H24O: C 84.32, H 9.44; found: C 84.59, H 9.66.
4-(tert-Butyldimethylsilyl)-1-octene (18a): Rf ˆ 0.87 (hexane); IR (neat):
nÄ ˆ 2924, 2854, 1465, 1254, 908, 825, 806, 761 cmÀ1; 1H NMR (CDCl3): d ˆ
À0.06 (s, 3H), À0.05 (s, 3H), 0.75 0.90 (m, 1H), 0.87 (t, J ˆ 6.9 Hz, 3H),
0.89 (s, 9H), 1.14 1.38 (m, 5H), 1.38 1.52 (m, 1H), 1.97 2.10 (m, 1H),
2.22 2.34 (m, 1H), 4.94 (d, J ˆ 9.9 Hz, 1H), 4.98 (d, J ˆ 16.8 Hz, 1H), 5.78
(ddt, J ˆ 9.9, 16.8, 6.9 Hz, 1H); 13C NMR (CDCl3): d ˆ À6.4, À6.3, 14.0,
17.4, 22.3, 22.9, 27.2, 29.1, 31.1, 34.4, 114.8, 139.5; elemental analysis calcd
(%) for C14H30Si: C 74.25, H 13.35; found: C 74.00, H 13.11.
endo-9-Butyl-9-iodobicyclo[6.1.0]nonane (6s): Rf ˆ 0.86 (hexane); IR
1
(neat): nÄ ˆ 2906, 2852, 1466, 1173, 1111, 943, 741 cmÀ1; H NMR (CDCl3):
d ˆ 0.18 0.29 (m, 2H), 0.90 (t, J ˆ 7.5 Hz, 3H), 1.10 1.71 (m, 16H), 1.79
(dd, J ˆ 2.1, 13.8 Hz, 2H); 13C NMR (CDCl3): d ˆ 14.1, 21.8, 26.7, 27.3, 29.1,
30.0, 31.5, 34.0, 46.9; elemental analysis calcd (%) for C13H23I: C 50.99, H
7.57; found: C 51.28, H 7.63.
exo-9-Butyl-9-iodobicyclo[6.1.0]nonane (7s): Rf ˆ 0.82 (hexane); IR (neat):
1
nÄ ˆ 2920, 2852, 1466, 1178, 1113, 741 cmÀ1; H NMR (CDCl3): d ˆ 0.92 (t,
4-(Methyldiphenylsilyl)-1-octene (18b): Rf ˆ 0.55 (hexane); IR (neat): nÄ ˆ
J ˆ 6.9 Hz, 3H), 1.00 1.17 (m, 2H), 1.24 1.64 (m, 16H), 2.06 (dd, J ˆ 1.8,
13.8 Hz, 2H); 13C NMR (CDCl3): d ˆ 14.0, 19.1, 21.7, 22.3, 26.0, 28.6, 31.8,
32.7, 34.8; elemental analysis calcd (%) for C13H23I: C 50.99, H 7.57; found:
C 51.02, H 7.39.
3064, 2920, 2854, 1638, 1428, 1252, 1110, 998, 908, 785, 732, 698 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.59 (s, 3H), 0.80 (t, J ˆ 7.2 Hz, 3H), 1.10 1.62 (m,
7H), 2.01 2.15 (m, 1H), 2.28 2.40 (m, 1H), 4.90 (d, J ˆ 10.2 Hz, 1H), 4.92
(d, J ˆ 17.4 Hz, 1H), 5.75 (ddt, J ˆ 10.2, 17.4, 7.2 Hz, 1H), 7.30 7.40 (m,
6H), 7.48 7.59 (m, 4H); 13C NMR (CDCl3): d ˆ À5.3, 13.8, 22.7, 23.5, 28.9,
31.4, 34.2, 115.0, 127.8, 129.1, 134.6, 137.1, 139.2; elemental analysis calcd
(%) for C21H28Si: C 81.75, H 9.15; found: C 81.74, H 9.20.
1-Butyl-2,3-dipentylcyclopropane (2,3-cis, 6u/7u ˆ 71/29): Rf ˆ 0.85 (hex-
ane); IR (neat): nÄ ˆ 2954, 2920, 2852, 1467, 1378, 725 cmÀ1
;
1H NMR
(CDCl3): d ˆ 0.02 (tt, J ˆ 5.1, 6.3 Hz, 1H), 0.31 0.43 (m, 2H), 0.79 0.98
(m, 9H), 1.00 1.44 (m, 22H); 13C NMR (CDCl3): d ˆ 14.0, 14.1, 17.7, 17.8,
22.5, 22.6, 22.8, 23.1, 23.4, 25.3, 28.1, 28.4, 29.9, 30.0, 31.8, 31.9, 32.1, 32.5,
32.6, 34.2; elemental analysis calcd (%) for C17H34: C 85.63, H 14.37; found:
C 85.64, H 14.61.
4-(Dimethylphenylsilyl)-1-octene (18c): Rf ˆ 0.64 (hexane); IR (neat): nÄ ˆ
2920, 2854, 1639, 1428, 1112, 995, 908, 814, 766, 731, 698 cmÀ1 1H NMR
;
(CDCl3): d ˆ 0.28 (s, 6H), 0.82 (t, J ˆ 6.9 Hz, 3H), 0.90 0.95 (m, 1H),
1.08 1.48 (m, 6H), 1.96 2.09 (m, 1H), 2.17 2.28 (m, 1H), 4.88 4.98 (m,
2H), 5.73 (ddt, J ˆ 10.2, 17.4, 7.2 Hz, 1H), 7.31 7.38 (m, 3H), 7.47 7.54 (m,
2H); 13C NMR (CDCl3): d ˆ À3.8, À3.8, 13.9, 22.8, 25.0, 28.7, 31.1, 34.0,
114.9, 127.7, 128.8, 137.0, 139.2, 139.3; elemental analysis calcd (%) for
C16H26Si: C 77.97, H 10.63; found: C 77.68, H 10.37.
r-1-Butyl-2-c,3-t-dipentylcyclopropane (6v): Rf ˆ 0.94 (hexane); IR (neat):
1
nÄ ˆ 2954, 2918, 2850, 1467, 1378, 723 cmÀ1; H NMR (CDCl3): d ˆ 0.03 (tt,
J ˆ 4.8, 6.6 Hz, 1H), 0.30 0.43 (m, 2H), 0.84 0.94 (m, 9H), 1.02 1.42 (m,
22H); 13C NMR (CDCl3): d ˆ 14.0, 14.1, 22.6, 22.6, 23.3, 23.4, 25.4, 28.1,
Chem. Eur. J. 2002, 8, No. 7
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0807-1735 $ 20.00+.50/0
1735

K. Oshima et al.
FULL PAPER
4-(Dicyclohexylmethylsilyl)-1-octene (18d): Rf ˆ 0.82 (hexane); IR (neat):
44.6, 127.8, 128.3, 129.0, 130.2, 135.0, 140.7, 202.2; elemental analysis calcd
(%) for C20H32SiO: C 75.88, H 10.19; found: C 76.17, H 9.90.
nÄ ˆ 2925, 2848, 1638, 1446, 1249, 1098, 997, 907, 889, 846, 770, 738 cmÀ1
;
1H NMR (CDCl3): d ˆ À0.13 (s, 3H), 0.72 0.90 (m, 3H), 0.88 (t, J ˆ
6.9 Hz, 3H), 1.06 1.52 (m, 16H), 1.58 1.84 (m, 10H), 1.95 2.07 (m,
1H), 2.21 2.32 (m, 1H), 4.89 8.02 (m, 2H), 5.79 (ddt, J ˆ 9.9, 16.8, 6.9 Hz,
1H); 13C NMR (CDCl3): d ˆ À8.7, 14.0, 22.3, 22.6, 22.9, 23.9, 24.0, 27.1, 28.4,
28.4, 28.4, 28.5, 29.8, 31.5, 32.1, 35.0, 114.3, 140.3; elemental analysis calcd
(%) for C21H40Si: C 78.67, H 12.57; found: C 78.52, H 12.73.
3-(Methyldiphenylsilyl)-2-heptanone (20 f): Rf ˆ 0.43 (hexane/ethyl acetate
10:1); IR (neat): nÄ ˆ 2924, 1687, 1428, 1353, 1255, 1167, 1111, 790, 735,
699 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.64 (s, 3H), 0.81 (t, J ˆ 6.9 Hz, 3H),
1.05 1.34 (m, 4H), 1.34 1.48 (m, 1H), 1.71 (s, 3H), 1.96 2.11 (m, 1H),
2.98 (dd, J ˆ 2.1, 11.4 Hz, 1H), 7.31 7.45 (m, 6H), 7.47 7.53 (m, 2H), 7.55
7.60 (m, 2H); 13C NMR (CDCl3): d ˆ À6.4, 13.7, 22.3, 27.3, 32.5, 32.9, 47.7,
128.1, 128.2, 129.8, 129.9, 134.4, 134.8 (2C), 134.9, 210.6; elemental analysis
calcd (%) for C20H26SiO: C 77.36, H 8.44; found: C 77.59, H 8.51.
4-(tert-Butyldimethylsilyl)-1,2-octadiene (19a): Rf ˆ 0.80 (hexane); IR
(neat): nÄ ˆ 2952, 2924, 2854, 1951, 1466, 1362, 1250, 834 cmÀ1
;
1H NMR
(CDCl3): d ˆ À0.06 (s, 3H), À0.06 (s, 3H), 0.88 (t, J ˆ 7.2 Hz, 3H), 0.90 (s,
9H), 1.12 1.58 (m, 7H), 4.63 (d, J ˆ 6.9 Hz, 1H), 4.64 (d, J ˆ 6.6 Hz, 1H),
4.98 (ddd, J ˆ 6.6, 6.9, 9.3 Hz, 1H); 13C NMR (CDCl3): d ˆ À7.3, À7.2, 14.0,
17.4, 22.3, 25.9, 27.2, 29.3, 31.6, 74.6, 92.4, 208.7; HRMS (m/z) calcd for
C14H28Si: 224.1960; found: 224.1955.
5-(Methyldiphenylsilyl)-4-nonanone (20g): Rf ˆ 0.53 (hexane/ethyl acetate
10:1); IR (neat): nÄ ˆ 2954, 1691, 1429, 1254, 1112, 789 cmÀ1
;
1H NMR
(CDCl3): d ˆ 0.64 (s, 3H), 0.64 (t, J ˆ 7.4 Hz, 3H), 0.81 (t, J ˆ 6.9 Hz, 3H),
1.05 1.32 (m, 5H), 1.32 1.52 (m, 2H), 1.80 (ddd, J ˆ 6.0, 8.7, 16.8 Hz, 1H),
1.98 (ddd, J ˆ 6.0, 8.7, 16.8 Hz, 1H), 2.00 2.14 (m, 1H), 2.94 (dd, J ˆ 2.1,
11.7 Hz, 1H), 7.30 7.45 (m, 6H), 7.46 7.53 (m, 2H), 7.55 7.61 (m, 2H);
13C NMR (CDCl3): d ˆ À6.5, 13.5, 13.7, 16.8, 22.4, 27.4, 32.9, 46.5, 47.4,
128.0, 128.1, 129.8, 129.8, 134.7, 134.7, 134.8, 135.1, 212.6; elemental analysis
calcd (%) for C22H30SiO: C 78.05, H 8.93; found: C 78.07, H 9.12.
Procedure for the synthesis of a-silylketones 20a l with acyl halide as the
electrophile: Butyllithium (1.2 mL, 1.6m solution in hexane, 2.0 mmol) was
added to a solution of butylmagnesium bromide (1.0 mL, 1.0m solution in
THF, 1.0 mmol) in THF (5 mL) at 08C, and the mixture was stirred for
10 min. The resulting solution was cooled to À788C, and a solution of 12
(1.0 mmol) in THF (2 mL) was added dropwise. The mixture was stirred for
10 min, CuCN ¥2LiCl (0.3 mL, 1.0 m solution in THF, 0.3 mmol) was added,
and the mixture was allowed to warm gradually to 08C over a period of 3 h.
DMI (0.22 mL, 2.0 mmol) and the corresponding acyl chloride (2.5 mmol)
were successively added. After stirring for 1 h at 08C, the reaction was
quenched with saturated aqueous NH4Cl. The mixture was extracted with
ethyl acetate and the organic layers were dried over anhydrous Na2SO4 and
concentrated in vacuo. Purification by silica-gel column chromatography
gave 20.
2-Methyl-4-(methyldiphenylsilyl)-3-octanone (20h): Rf ˆ 0.49 (hexane/eth-
yl acetate 10:1); IR (neat): nÄ ˆ 2956, 2924, 1689, 1466, 1428, 1112, 1057, 788,
736, 697 cmÀ1; 1H NMR (CDCl3): d ˆ 0.58 (d, J ˆ 6.9 Hz, 3H), 0.64 (s, 3H),
0.80 (t, J ˆ 7.2 Hz, 3H), 0.96 (d, J ˆ 6.9 Hz, 3H), 1.00 1.42 (m, 5H), 1.97
(sept, J ˆ 6.9 Hz, 1H), 2.00 2.15 (m, 1H), 3.14 (dd, J ˆ 2.4, 11.7 Hz, 1H),
7.29 7.44 (m, 6H), 7.46 7.52 (m, 2H), 7.54 7.61 (m, 2H); 13C NMR
(CDCl3): d ˆ À6.5, 13.8, 16.1, 19.0, 22.5, 27.6, 33.1, 42.1, 45.3, 128.0, 128.1,
129.8 (2C), 134.7, 134.8, 134.8, 135.2, 215.9; elemental analysis calcd (%) for
C22H30SiO: C 78.05, H 8.93; found: C 77.86, H 9.19.
1-Cyclopropyl-2-(methyldiphenylsilyl)-1-hexanone (20i): Rf ˆ 0.50 (hex-
ane/ethyl acetate 10:1); IR (neat): nÄ ˆ 2926, 2854, 1675, 1429, 1378, 1254,
1112, 792, 736, 721, 697 cmÀ1; 1H NMR (CDCl3): d ˆ 0.30 (dddd, J ˆ 2.7, 6.6,
7.5, 9.0 Hz, 1H), 0.57 0.68 (m, 1H), 0.64 (s, 3H), 0.71 0.93 (m, 2H), 0.81
(t, J ˆ 7.2 Hz, 3H), 1.08 1.35 (m, 4H), 1.36 1.49 (m, 2H), 1.99 2.14 (m,
1H), 3.13 (dd, J ˆ 2.4, 11.4 Hz, 1H), 7.30 7.45 (m, 6H), 7.50 7.56 (m, 2H),
7.56 7.61 (m, 2H); 13C NMR (CDCl3): d ˆ 5.9, 10.5, 11.1, 13.8, 22.3, 22.5,
27.0, 32.9, 48.3, 127.9, 128.0, 129.6, 129.7, 134.8, 134.9, 134.9, 135.2, 211.6;
elemental analysis calcd (%) for C22H28SiO: C 78.52, H 8.39; found: C
78.23, H 8.49.
3-(tert-Butyldimethylsilyl)-2-heptanone (20a): Rf ˆ 0.54 (hexane/ethyl ace-
tate 10:1); IR (neat): nÄ ˆ 2926, 2856, 1692, 1467, 1353, 1252, 1167, 836,
772 cmÀ1
;
1H NMR (CDCl3): d ˆ À0.02 (s, 3H), 0.03 (s, 3H), 0.85 (t, J ˆ
7.1 Hz, 3H), 0.92 (s, 9H), 1.04 1.34 (m, 4H), 1.34 1.48 (m, 1H), 1.96 2.03
(m, 1H), 2.07 (s, 3H), 2.47 (dd, J ˆ 1.8, 11.9 Hz, 1H); 13C NMR (CDCl3):
d ˆ À7.2, À5.2, 13.8, 17.7, 22.4, 26.7, 28.0, 32.0, 33.1, 46.1, 211.2; elemental
analysis calcd (%) for C13H28SiO: C 68.35, H 12.35; found: C 68.17, H 12.55.
2-(tert-Butyldimethylsilyl)-1-cyclopropyl-1-hexanone (20b): Rf ˆ 0.54 (hex-
ane/ethyl acetate 10:1); IR (neat): nÄ ˆ 2928, 2856, 1676, 1466, 1378, 1252,
1140, 1071, 836 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.02 (s, 3H), 0.04 (s, 3H),
2-(Methyldiphenylsilyl)-1-phenyl-1-hexanone (20j): Rf ˆ 0.53 (hexane/eth-
yl acetate 10:1); IR (neat): nÄ ˆ 2922, 2854, 1659, 1447, 1429, 1344, 1255,
0.77 0.84 (m, 2H), 0.86 (t, J ˆ 7.2 Hz, 3H), 0.94 (s, 9H), 0.94 1.00 (m,
1H), 1.00 1.08 (m, 1H), 1.08 1.20 (m, 1H), 1.20 1.36 (m, 3H), 1.36 1.49
(m, 1H), 1.82 (tt, J ˆ 4.5, 7.8 Hz, 1H), 1.94 2.09 (m, 1H), 2.62 (dd, J ˆ 2.1,
11.7 Hz, 1H); 13C NMR (CDCl3): d ˆ À7.1, À6.0, 10.4, 11.1, 13.8, 17.7, 22.0,
22.4, 26.8, 27.7, 33.1, 46.6, 212.5; elemental analysis calcd (%) for C15H30SiO:
C 70.80, H 11.88; found: C 70.66, H 12.14.
1228, 1112, 1002, 790, 732, 697 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.57 (s, 3H),
0.80 (t, J ˆ 7.2 Hz, 3H), 1.16 1.42 (m, 4H), 1.55 1.68 (m, 1H), 2.20 2.36
(m, 1H), 3.86 (dd, J ˆ 2.4, 11.4 Hz, 1H), 7.13 7.20 (m, 2H), 7.20 7.28 (m,
3H), 7.33 7.42 (m, 6H), 7.54 7.60 (m, 2H), 7.64 7.70 (m, 2H); 13C NMR
(CDCl3): d ˆ À5.7, 13.8, 22.4, 28.2, 33.0, 41.0, 127.7, 128.0, 128.0, 128.1, 129.5,
129.7, 132.0, 134.4, 134.7, 134.8, 134.9, 139.7, 203.3; elemental analysis calcd
(%) for C25H28SiO: C 80.59, H 7.57; found: C 80.40, H 7.47.
2-(tert-Butyldimethylsilyl)-1-phenyl-1-hexanone (20c): Rf ˆ 0.54 (hexane/
ethyl acetate 10:1); IR (neat): nÄ ˆ 2928, 2854, 1654, 1597, 1580, 1466, 1447,
1252, 1227, 1003, 833, 731, 688 cmÀ1; 1H NMR (CDCl3): d ˆ À0.26 (s, 3H),
0.03 (s, 3H), 0.84 (t, J ˆ 6.9 Hz, 3H), 0.91 (s, 9H), 1.12 1.40 (m, 4H), 1.50
1.65 (m, 1H), 2.16 2.32 (m, 1H), 3.42 (dd, J ˆ 2.1, 11.7 Hz, 1H), 7.44 (dd,
J ˆ 6.6, 7.2 Hz, 2H), 7.52 (t, J ˆ 7.2 Hz, 1H), 7.90 (d, J ˆ 6.6 Hz, 2H);
13C NMR (CDCl3): d ˆ À7.4, À5.8, 13.8, 18.1, 25.6, 26.9, 28.7, 33.3, 39.2,
128.1, 128.5, 132.4, 140.0, 203.9; elemental analysis calcd (%) for
C18H30SiO: C 74.42, H 10.41; found: C 74.68, H 10.52.
5-(Methyldiphenylsilyl)-4-undecanone (20k): Rf ˆ 0.52 (hexane/ethyl ace-
tate 10:1); IR (neat): nÄ ˆ 2928, 2856, 1690, 1464, 1429, 1254, 1111, 791, 737,
700 cmÀ1; 1H NMR (CDCl3): d ˆ 0.64 (s, 3H), 0.64 (t, J ˆ 7.5 Hz, 3H), 0.83
(t, J ˆ 6.9 Hz, 3H), 1.08 1.32 (m, 9H), 1.32 1.49 (m, 2H), 1.80 (ddd, J ˆ
6.0, 8.7, 16.8 Hz, 1H), 1.97 (ddd, J ˆ 6.0, 8.7, 16.8 Hz, 1H), 2.03 2.15 (m,
1H), 2.94 (dd, J ˆ 2.4, 11.4 Hz, 1H), 7.30 7.44 (m, 6H), 7.46 7.51 (m, 2H) ,
7.55 7.59 (m, 2H); 13C NMR (CDCl3): d ˆ À6.4, 13.5, 13.9, 16.8, 22.5, 27.7,
29.0, 30.7, 31.5, 46.5, 47.4, 128.0, 128.1, 129.8, 129.8, 129.8, 134.7, 134.7, 134.8,
135.1; HRMS (m/z) calcd for C24H34OSi 366.2379; found: 366.2362.
(E)-5-(tert-Butyldimethylsilyl)-2-nonen-4-one (20d): Rf ˆ 0.48 (hexane/eth-
yl acetate 10:1); IR (neat): nÄ ˆ 2928, 2854, 1679, 1657, 1628, 1466, 1256,
1143, 1065, 969, 822, 770 cmÀ1; 1H NMR (CDCl3): d ˆ À0.08 (s, 3H), 0.03 (s,
3H), 0.84 (t, J ˆ 7.2 Hz, 3H), 0.92 (s, 9H), 1.03 1.35 (m, 4H), 1.38 1.51 (m,
1H), 1.87 (dd, J ˆ 1.8, 6.9 Hz, 3H), 1.96 2.11 (m, 1H), 2.61 (dd, J ˆ 2.1,
11.7 Hz, 1H), 6.12 (dq, J ˆ 15.6, 1.8 Hz, 1H), 6.77 (dq, J ˆ 15.6, 6.9 Hz, 1H);
13C NMR (CDCl3): d ˆ À7.2, À6.0, 13.8, 17.9, 17.9, 22.5, 26.8, 27.8, 33.0, 43.1,
133.5, 140.4, 202.5; elemental analysis calcd (%) for C15H30SiO: C 70.80, H
11.88; found: C 71.00, H 11.61.
2-(Methyldiphenylsilyl)-1-phenyl-1-octanone (20l): Rf ˆ 0.49 (hexane/ethyl
acetate 10:1); IR (neat): nÄ ˆ 2926, 2855, 1661, 1429, 1342, 1256, 1217, 1113,
1
791, 733, 698 cmÀ1; H NMR (CDCl3): d ˆ 0.55 (s, 3H), 0.80 (t, J ˆ 6.9 Hz,
3H), 1.08 1.40 (m, 8H), 1.52 1.64 (m, 1H), 2.18 2.32 (m, 1H), 3.84 (dd,
J ˆ 2.4, 11.4 Hz, 1H), 7.12 7.25 (m, 5H), 7.32 7.42 (m, 6H), 7.53 7.60 (m,
2H) , 7.62 7.69 (m, 2H); 13C NMR (CDCl3): d ˆ À5.7, 13.9, 22.4, 28.5, 29.0,
30.8, 31.5, 41.1, 127.7, 128.0, 128.0, 128.1, 129.5, 129.7, 132.0, 134.5, 134.8,
134.9, 139.8, 203.3; elemental analysis calcd (%) for C27H32OSi: C 80.95, H
8.05; found: C 80.70, H 8.16.
(E)-4-(tert-Butyldimethylsilyl)-1-phenyl-1-octen-3-one (20e): Rf ˆ 0.44
(hexane/ethyl acetate 10:1); IR (neat): nÄ ˆ 2926, 2854, 1673, 1642, 1609,
1466, 1450, 1252, 1138, 1070, 835, 688 cmÀ1; 1H NMR (CDCl3): d ˆ À0.22 (s,
3H), 0.08 (s, 3H), 0.85 (t, J ˆ 6.9 Hz, 3H), 0.95 (s, 9H), 1.10 1.39 (m, 4H),
1.49 1.58 (m, 1H), 2.05 2.20 (m, 1H), 2.75 (dd, J ˆ 2.4, 12.0 Hz, 1H), 6.73
(d, J ˆ 15.9 Hz, 1H), 7.36 7.42 (m, 3H), 7.52 (d, J ˆ 15.9 Hz, 1H), 7.52 7.58
(m, 2H); 13C NMR (CDCl3): d ˆ À7.0, À5.9, 13.8, 18.0, 22.5, 26.9, 27.9, 33.1,
Procedure for the conjugate addition of a-silylpentylmagnesium to enones:
Butyllithium (1.2 mL, 1.6m solution in hexane, 2.0 mmol) was added to a
solution of butylmagnesium bromide (1.0 mL, 1.0m solution in THF,
1.0 mmol) in THF (5 mL) at 08C, and the mixture was stirred for 10 min.
The resulting solution was cooled to À788C, and a solution of 12
1736
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0807-1736 $ 20.00+.50/0
Chem. Eur. J. 2002, 8, No. 7

Alkylated Organomagnesium Compounds
1730 1740
(1.0 mmol) in THF (2 mL) was added dropwise. The mixture was stirred for
10 min, CuCN ¥2LiCl (0.3 mL, 1.0 m solution in THF, 0.3 mmol) was added,
and the mixture was allowed to warm gradually to 08C over a period of 3 h.
Then the mixture was cooled to À788C and a mixture of the corresponding
enone (4.0 mmol) and chlorotrimethylsilane (0.51 mL, 4.0 mmol) in THF
(2 mL) was added. The reaction mixture was gradually warmed to 08C and
then poured into saturated aqueous NH4Cl and extracted with ethyl
acetate. The organic layers were dried over anhydrous Na2SO4 and
concentrated in vacuo. Purification by silica-gel column chromatography
provided 21, 22, or 23.
2874, 1690, 1464, 1429, 1254, 1111, 1038, 793, 737, 700 cmÀ1 1H NMR
;
(CDCl3): d ˆ 0.57 (t, J ˆ 7.5 Hz, 1.5H), 0.60 (t, J ˆ 7.5 Hz, 1.5H), 0.70 (t, J ˆ
7.5 Hz, 1.5H), 0.72 (s, 1.5H), 0.73 (d, J ˆ 6.3 Hz, 1.5H), 0.75 (s, 1.5H), 0.79
(t, J ˆ 7.5 Hz, 1.5H), 0.88 (d, J ˆ 6.3 Hz, 1.5H), 0.85 1.15 (m, 2H), 1.22
1.44 (m, 2H), 1.69 (ddd, J ˆ 5.7, 9.0, 17.4 Hz, 0.5H), 1.75 (ddd, J ˆ 5.7, 9.0,
17.4 Hz, 0.5H), 1.90 2.03 (m, 1H), 2.04 2.16 (m, 0.5H), 2.18 2.31 (m,
0.5H), 2.85 (d, J ˆ 10.8 Hz, 0.5H), 2.87 (d, J ˆ 9.9 Hz, 0.5H), 7.26 7.35 (m,
3H), 7.35 7.41 (m, 3H), 7.47 7.53 (m, 2H), 7.55 7.61 (m, 2H); 13C NMR
(CDCl3): d ˆ À5.4, À5.2, 10.8, 11.4, 13.4, 13.4, 16.1, 16.2, 18.8, 19.1, 29.2,
29.8, 30.0, 35.4, 48.7, 48.9, 52.4, 52.6, 127.9, 128.0, 129.5, 129.5, 129.5, 134.6,
134.7, 135.1, 135.1, 135.5, 135.6, 135.8, 136.0, 213.4, 213.6; elemental analysis
calcd (%) for C22H30OSi: C 78.05, H 8.93; found: C 78.30, H 8.94.
5-(tert-Butyldimethylsilyl)-2-nonanone (21a): Rf ˆ 0.51 (hexane/ethyl ace-
tate 10:1); IR (neat): nÄ ˆ 2926, 2854, 1720, 1467, 1362, 1252, 1155, 828, 805,
763 cmÀ1; 1H NMR (CDCl3): d ˆ À0.06 (s, 6H), 0.65 0.75 (m, 1H), 0.88 (t,
J ˆ 7.1 Hz, 3H), 0.89 (s, 9H), 1.15 1.38 (m, 5H), 1.40 1.60 (m, 2H), 1.72
1.86 (m, 1H), 2.13 (s, 3H), 2.40 (ddd, J ˆ 6.0, 10.5, 16.5 Hz, 1H), 2.44 (ddd,
J ˆ 6.0, 10.5, 16.5 Hz, 1H); 13C NMR (CDCl3): d ˆ À6.5, À6.4, 13.9, 17.3,
22.0, 23.0, 24.1, 27.2, 29.3, 29.8, 31.2, 43.3, 209.6; elemental analysis calcd
(%) for C15H32SiO: C 70.24, H 12.57; found: C 70.30, H 12.42.
2,5-Dimethyl-4-(methyldiphenylsilyl)-3-heptanone (24c, ꢀ 1:1 mixture of
two diastereomers): Rf ˆ 0.56 (hexane/ethyl acetate 10:1); IR (neat): nÄ ˆ
2966, 1688, 1454, 1429, 1381, 1254, 1109, 1042, 791, 700 cmÀ1 1H NMR
;
(CDCl3): d ˆ 0.36 (d, J ˆ 6.6 Hz, 1.5H), 0.38 (d, J ˆ 6.6 Hz, 1.5H), 0.46
0.75 (m, 0.5H), 0.70 (t, J ˆ 7.5 Hz, 1.5H), 0.73 (s, 1.5H), 0.76 (s, 1.5H), 0.76
(d, J ˆ 6.6 Hz, 1.5H), 0.81 (t, J ˆ 7.5 Hz, 1.5H), 0.87 (d, J ˆ 6.6 Hz, 1.5H),
0.96 (d, J ˆ 7.5 Hz, 1.5H), 0.98 (d, J ˆ 7.5 Hz, 1.5H), 1.00 1.26 (m, 0.5H),
1.33 1.53 (m, 1H), 1.84 2.06 (m, 1H), 2.06 2.29 (m, 1H), 3.05 (d, J ˆ
10.5 Hz, 0.5H), 3.08 (d, J ˆ 10.2 Hz, 0.5H), 7.26 7.42 (m, 6H), 7.47 7.53
(m, 2H), 7.57 7.62 (m, 2H); 13C NMR (CDCl3): d ˆ À5.2, À5.0, 11.4, 11.5,
15.9, 18.6, 18.7, 18.7, 19.4, 29.1, 30.1, 35.1, 35.2, 43.0, 43.1, 51.1, 51.9, 127.9,
128.0, 129.5, 129.5, 129.5, 134.7, 134.7, 135.3, 135.3, 135.5, 136.0, 136.2, 216.2,
216.5; elemental analysis calcd (%) for C22H30OSi: C 78.05, H 8.93; found:
C 78.16, H 9.16.
5-(Methyldiphenylsilyl)-2-nonanone (21b): Rf ˆ 0.60 (hexane/ethyl acetate
5:1); IR (neat): nÄ ˆ 2920, 2854, 1714, 1428, 1358, 1253, 1109, 785, 735, 719,
699 cmÀ1; 1H NMR (CDCl3): d ˆ 0.58 (s, 3H), 0.79 (t, J ˆ 7.2 Hz, 3H), 1.08
1.40 (m, 6H), 1.46 1.90 (m, 3H), 1.95 (s, 3H), 2.24 (ddd, J ˆ 6.0, 9.6,
16.5 Hz, 1H), 2.35 (ddd, J ˆ 6.0, 9.6, 16.5 Hz, 1H), 7.30 7.39 (m, 6H), 7.50
7.56 (m, 4H); 13C NMR (CDCl3): d ˆ À5.7, 13.8, 22.7, 23.1, 23.9, 29.4, 29.6,
31.4, 43.3, 127.9, 127.9, 129.2, 129.2, 134.8, 136.9, 136.9, 209.4; elemental
analysis calcd (%) for C22H30SiO: C 78.05, H 8.93; found: C 77.90, H 8.80.
1-Cyclopropyl-3-methyl-2-(methyldiphenylsilyl)-1-pentanone (24d, ꢀ 1:1
mixture of two diastereomers): Rf ˆ 0.44 (hexane/ethyl acetate 10:1); IR
3-[1-(tert-Butyldimethylsilyl)pentyl]-1-cyclohexanone (22, 86:14 mixture of
diastereomers): Rf ˆ 0.49 (hexane/ethyl acetate 10:1); IR (neat): nÄ ˆ 2928,
2850, 1711, 1462, 1254, 823, 805, 764 cmÀ1; 1H NMR (CDCl3): d ˆ À0.03 (s,
2.58H), À0.03 (s, 0.42H), 0.01 (s, 0.42H), 0.02 (s, 2.58H), 0.65 0.72 (m,
0.14H), 0.77 0.84 (m, 0.86H), 0.84 0.93 (m, 1.68H), 0.88 (s, 7.74H), 0.89
(t, J ˆ 6.9 Hz, 2.58H), 1.18 1.45 (m, 6H), 1.48 1.78 (m, 3H), 1.94 2.10
(m, 2H), 2.14 2.42 (m, 4H); 13C NMR (CDCl3) (major isomer): d ˆ À5.8,
À5.1, 14.0, 17.3, 23.1, 25.8, 26.7, 27.1, 28.6, 31.7, 34.1, 40.9, 41.2, 46.6, 212.7;
elemental analysis calcd (%) for C17H34SiO: C 72.27, H 12.13; found: C
72.16, H 12.16.
(neat): nÄ ˆ 2963, 2930, 1674, 1429, 1377, 1254, 1111, 1063, 797, 737, 700 cmÀ1
1H NMR (CDCl3): d ˆ 0.16 0.26(m, 0.5H), 0.24 0.35 (m, 0.5H), 0.50
;
0.67 (m, 2H), 0.67 0.83 (m, 1H), 0.71 (s, 1.5H), 0.72 (t, J ˆ 7.5 Hz, 1.5H),
0.73 (s, 1.5H), 0.78 (d, J ˆ 6.9 Hz, 1.5H), 0.81 (t, J ˆ 7.5 Hz, 1.5H), 0.92 (d,
J ˆ 6.6 Hz, 1.5H), 0.91 1.07 (m, 0.5H), 1.07 1.24 (m, 0.5H), 1.35 1.58 (m,
2H), 1.95 2.15 (m, 0.5H), 2.15 2.32 (m, 0.5H), 3.09 (d, J ˆ 10.8 Hz, 0.5H),
3.11 (d, J ˆ 9.6 Hz, 0.5H), 7.26 7.40 (m, 6H), 7.52 7.58 (m, 2H), 7.58 7.64
(m, 2H); 13C NMR (CDCl3): d ˆ À4.7, À4.4, 10.1, 10.3, 10.6, 11.2, 11.3, 11.4,
18.9, 19.3, 23.4, 23.4, 29.3, 29.9, 34.8, 35.2, 54.3, 54.7, 127.8, 128.0, 129.4,
129.4, 129.5, 134.8, 134.8, 135.1, 135.2, 135.6, 135.8, 136.0, 212.8, 213.0;
elemental analysis calcd (%) for C22H28OSi: C 78.52, H 8.39; found: C
78.34, H 8.51.
3-[1-(tert-Butyldimethylsilyl)pentyl]-1-cyclopentanone (23, 67:33 mixture of
diastereomers): Rf ˆ 0.53 (hexane/ethyl acetate 5:1); IR (neat): nÄ ˆ 2924,
2854, 1744, 1466, 1252, 1155, 825, 763 cmÀ1; 1H NMR (CDCl3): d ˆ À0.03 (s,
4.02H), À0.01 (s, 0.99H), 0.00 (s, 0.99H), 0.78 0.96 (m, 4H), 0.91 (s, 9H),
1.16 1.52 (m, 6H), 1.60 2.48 (m, 7H); 13C NMR (CDCl3): d ˆ À5.8, À5.5,
À5.4, À5.0, 13.9, 17.4, 17.5, 23.1, 23.2, 26.4, 26.7, 27.0, 27.2, 27.2, 28.0, 29.6,
33.9, 34.1, 38.9, 38.9, 39.1, 39.1, 43.0, 45.3, 220.1; elemental analysis calcd
(%) for C16H32SiO: C 71.57, H 12.01; found: C 71.31, H 12.28.
3-Methyl-2-(methyldiphenylsilyl)-1-phenyl-1-pentanone (24e, ꢀ 1:1 mix-
ture of two diastereomers): Rf ˆ 0.42 (hexane/ethyl acetate 10:1); IR (neat):
nÄ ˆ 2963, 2930, 1659, 1429, 1263, 1204, 1111, 789, 735, 718, 698 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.67 (s, 1.5H), 0.71 (s, 1.5H), 0.71 (t, J ˆ 7.4 Hz,
1.5H), 0.78 (t, J ˆ 7.7 Hz, 1.5H), 0.86 (d, J ˆ 6.9 Hz, 1.5H), 0.94 (d, J ˆ
6.6 Hz, 1.5H), 0.98 1.12 (m, 0.5H), 1.12 1.28 (m, 0.5H), 1.41 1.58 (m,
1H), 2.22 2.36 (m, 0.5H), 2.36 2.51 (m, 0.5H), 3.81 (d, J ˆ 10.5 Hz,
0.5H), 3.83 (d, J ˆ 9.9 Hz, 0.5H), 7.12 7.23 (m, 5H), 7.24 7.40 (m, 6H),
7.40 7.48 (m, 2H) , 7.52 7.60 (m, 2H); 13C NMR (CDCl3): d ˆ À4.6, À4.4,
11.0, 11.5, 19.0, 19.5, 29.4, 30.2, 35.8, 36.1, 46.9, 47.1, 127.6, 127.6, 127.9, 128.0,
128.1, 128.1, 129.2, 129.4, 129.4, 131.9, 131.9, 134.7, 134.8, 135.1, 135.1, 135.2,
135.6, 135.8, 140.0, 140.3; HRMS (m/z) calcd for C25H28OSi 372.1909;
found: 372.1912.
Procedure for the introduction of a sec-butyl group: sec-Butyllithium
(2.0 mL, 1.0m solution in hexane-cyclohexane, 2.0 mmol) was added to a
solution of sec-butylmagnesium bromide (1.0 mL, 1.0m solution in THF,
1.0 mmol) in THF (5 mL) at 08C, and the mixture was stirred for 10 min.
The resulting solution was cooled to À788C and a solution of (dibromo-
methyl)methyldiphenylsilane (12b, 370 mg, 1.0 mmol) in THF (2 mL) was
added dropwise. The mixture was allowed to warm to ambient temperature
gradually. CuCN ¥2LiCl (0.2 mL, 1.0 m solution in THF, 0.2 mmol) and the
corresponding electrophile (3.0 mmol) were successively added at 08C.
After stirring for 1 h at 08C, the reaction was quenched with saturated
aqueous NH4Cl. The mixture was extracted with hexane and the organic
layers were dried over anhydrous Na2SO4 and concentrated in vacuo.
Purification by silica-gel column chromatography provided 24.
Preparation of dibromodisilylmethanes
Method A: Butyllithium (2.6 mL, 1.6m solution in hexane, 4.2 mmol) was
added dropwise to a solution of diisopropylamine (0.63 mL, 4.5 mmol) in
THF (4 mL) at 08C, and the mixture was stirred for 0.5 h. The resulting
solution of LDA was cooled to À788C, and a solution of a dibromo-
methylsilane (4.0 mmol) in THF (8 mL) was added dropwise at À788C.
The mixture was stirred for 0.5 h, and the corresponding trialkylchlorosi-
lane or iodomethane (5.0 mmol) was added. After stirring for 0.5 h at
À788C, the mixture was poured into 1m HCl and extracted with hexane.
The combined organic layers were dried over anhydrous Na2SO4 and
concentrated in vacuo. Purification by silica-gel column chromatography
provided the corresponding dibromodisilylmethane.
5-Methyl-4-(methyldiphenylsilyl)-1-heptene (24a): Rf ˆ 0.46 (hexane/ethyl
acetate 80:1); IR (neat): nÄ ˆ 3071, 2959, 1638, 1460, 1427, 1252, 1109, 997,
908, 787, 737, 700 cmÀ1; 1H NMR (CDCl3): d ˆ 0.64 (s, 1.5H), 0.65 (s, 1.5H),
0.76 (t, J ˆ 7.5 Hz, 1.5H), 0.79 (d, J ˆ 6.6 Hz, 1.5H), 0.82 (t, J ˆ 7.2 Hz,
1.5H), 0.90 (d, J ˆ 7.2 Hz, 1.5H), 1.15 1.33 (m, 2H), 1.51 1.62 (m, 1H),
1.62 1.76 (m, 1H), 2.19 2.36 (m, 2H), 4.83 4.94 (m, 2H), 5.71 5.79 (m,
1H), 7.34 7.38 (m, 6H), 7.50 7.59 (m, 4H); 13C NMR (CDCl3): d ˆ À4.3,
À3.7, 12.3, 12.5, 17.7, 19.2, 28.3, 29.1, 29.8, 30.5, 30.7, 32.3, 35.1, 35.4, 114.4,
114.7, 127.8, 127.8, 127.9, 129.0, 129.3, 134.3, 134.8, 134.9, 134.9, 137.6, 137.8,
138.2, 140.2, 140.7; HRMS (m/z) calcd for C21H28Si: 308.1960; found:
308.1945.
Method B: The solution of LDA (lithium diisopropylamide) was prepared
by the slow addition of butyllithium (39 mL, 1.6m solution in hexane,
62 mmol) to a solution of diisopropylamine (8.8 mL, 63 mmol) in THF
(40 mL) at 08C. The resulting solution was added to a solution of
dibromomethane (4.2 mL, 30 mmol) and trialkylchlorosilane (65 mmol) in
6-Methyl-5-(methyldiphenylsilyl)-4-octanone (24b, ꢀ 1:1 mixture of two
diastereomers): Rf ˆ 0.49 (hexane/ethyl acetate 10:1); IR (neat): nÄ ˆ 2961,
Chem. Eur. J. 2002, 8, No. 7
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0807-1737 $ 20.00+.50/0
1737

K. Oshima et al.
FULL PAPER
THF dropwise at À788C. After stirring for 2 h at room temperature, the
resulting mixture was poured into 1m HCl and extracted with hexane. The
combined organic layers were dried over anhydrous Na2SO4 and concen-
trated in vacuo. Purification by silica-gel column chromatography or
recrystallization provided the corresponding dibromodisilylmethane.
7.66 (m, 2H); 13C NMR (CDCl3): d ˆ À6.3, 20.9, 33.9, 128.0, 128.0, 129.9
(2C), 134.2, 134.3, 135.1, 135.1; elemental analysis calcd (%) for C15H17BrSi:
C 59.01, H 5.61; found: C 59.07, H 5.60.
2-Bromo-2-(methyldiphenylsilyl)propane (25e): Rf ˆ 0.36 (hexane/ethyl
acetate 40:1); IR (neat): nÄ ˆ 3071, 2951, 1427, 1254, 1111, 1088, 893, 791,
1
727, 700 cmÀ1; H NMR (CDCl3): d ˆ 0.78 (s, 3H), 1.86 (s, 6H), 7.35 7.48
Method C: Butyllithium (25 mL, 1.6m solution in hexane, 40 mmol) was
(m, 6H), 7.71 7.77 (m, 4H); 13C NMR (CDCl3): d ˆ À5.1, 31.3, 53.7, 127.9,
129.8, 134.1, 135.7; elemental analysis calcd (%) for C16H19BrSi: C 60.18, H
6.00; found: C 60.23, H 5.96.
slowly added to
a solution of (chloro)methyldiphenylsilane (8.4 mL,
40 mmol) and carbon tetrabromide (6.63 g, 20 mmol) in THF (50 mL) at
À788C under an argon atmosphere. The cooling bath was removed and the
mixture was stirred for 2 h at room temperature. Then, 1m HCl was added
to the reaction mixture and the whole mixture was extracted with
chloroform. The organic layers were dried over anhydrous Na2SO4 and
concentrated in vacuo. Recrystallization from hexane/ethyl acetate afford-
ed 12k.
Spectral data for 12 f[18c] (prepared by method A from 12b and chloro-
trimethylsilane), and 12i[18a] (prepared by method B), were identical with
those reported in the literature.
1-Bromo-1-(methyldiphenylsilyl)-1-(trimethylsilyl)ethane (25 f): Rf ˆ 0.44
(hexane/ethyl acetate 40:1); IR (neat): nÄ ˆ 2955, 1427, 1252, 1109, 964,
841, 802, 736, 721, 700 cmÀ1; 1H NMR (CDCl3): d ˆ À0.10 (s, 9H), 0.79 (s,
3H), 1.92 (s, 3H), 7.30 7.48 (m, 6H), 7.72 (dd, J ˆ 1.8, 7.8 Hz, 2H), 7.86 (dd,
J ˆ 1.8, 7.8 Hz, 2H); 13C NMR (CDCl3): d ˆ À2.2, À1.8, 23.7, 43.9, 127.5,
127.8, 129.5, 129.6, 135.0, 135.3, 135.8, 136.0; elemental analysis calcd (%)
for C18H25BrSi2: C 57.28, H 6.68; found: C 57.53, H 6.67.
1-Bromo-1,1-bis(triethylsilyl)ethane (25g): Rf ˆ 0.84 (hexane); IR (neat):
nÄ ˆ 2955, 2878, 1462, 1416, 1379, 1242, 1007, 970, 777, 735 cmÀ1
;
1H NMR
1,1-Dibromo-1-(methyldiphenylsilyl)ethane (12e, prepared by method A
from 12b and iodomethane): Rf ˆ 0.31 (hexane/ethyl acetate 40:1); IR
(CDCl3): d ˆ 0.76 (q, J ˆ 8.4 Hz, 6H), 0.78 (q, J ˆ 7.8 Hz, 6H), 1.04 (t, J ˆ
7.8 Hz, 9H), 1.04 (t, J ˆ 8.4 Hz, 9H), 1.82 (s, 3H); 13C NMR (CDCl3): d ˆ
4.0, 8.3, 25.0, 47.2; elemental analysis calcd (%) for C14H33BrSi2: C 49.82, H
9.86; found: C 49.80, H 9.56.
(neat): nÄ ˆ 1427, 1256, 1113, 1049, 999, 793, 733, 698 cmÀ1
;
1H NMR
(CDCl3): d ˆ 0.90 (s, 3H), 2.59 (s, 3H), 7.36 7.51 (m, 6H), 7.78 7.84 (m,
4H); 13C NMR (CDCl3): d ˆ À4.6, 37.0, 58.4, 127.9, 130.3, 132.6, 136.0;
elemental analysis calcd (%) for C15H16Br2Si: C 46.90, H 4.20; found: C
47.09, H 4.21.
1-Bromo-1-(tert-butyldimethylsilyl)-1-(trimethylsilyl)ethane (25h): Rf ˆ
0.77 (hexane); IR (neat): nÄ ˆ 2956, 2854, 1467, 1252, 966, 840, 822,
766 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.11 (s, 3H), 0.17 (s, 3H), 0.15 (s, 9H),
Dibromobis(triethylsilyl)methane (12g, prepared by method A from (di-
bromomethyl)triethylsilane and chlorotriethylsilane): Rf ˆ 0.74 (hexane);
1.02 (s, 9H), 1.85 (s, 3H); 13C NMR (CDCl3): d ˆ À4.3, À4.1, À1.2, 20.1,
24.3, 28.3, 45.9; elemental analysis calcd (%) for C11H27BrSi2: C 44.72, H
9.21; found: C 44.42, H 9.42.
IR (neat): nÄ ˆ 2955, 2878, 1462, 1414, 1379, 1242, 1009, 818, 743, 679 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.90 (q, J ˆ 7.8 Hz, 12H), 1.10 (t, J ˆ 7.8 Hz, 18H);
13C NMR (CDCl3): d ˆ 4.8, 8.3, 58.2; elemental analysis calcd (%) for
C13H30Br2Si2: C 38.81, H 7.52; found: C 38.63, H 7.62.
1-Bromo-1,1-bis(trimethylsilyl)ethane (25i): Rf ˆ 0.72 (hexane); IR (neat):
nÄ ˆ 2955, 1252, 966, 841, 760, 691 cmÀ1; 1H NMR (CDCl3): d ˆ 0.14 (s, 18H),
1.71 (s, 3H); 13C NMR (CDCl3): d ˆ À1.6, 23.0, 45.0; elemental analysis
calcd (%) for C8H21BrSi2: C 37.93, H 8.36; found: C 37.78, H 8.49.
Dibromo(tert-butyldimethylsilyl)(trimethylsilyl)methane (12h, prepared by
method A from 12a and chlorotrimethylsilane): Rf ˆ 0.77 (hexane); IR
(neat): nÄ ˆ 2932, 2860, 1464, 1252, 847, 772, 691 cmÀ1
;
1H NMR (CDCl3):
1-Bromo-1,1-bis(dimethylphenylsilyl)ethane (25j): Rf ˆ 0.46 (hexane/ethyl
acetate 40:1); m.p. 738C; IR (Nujol): nÄ ˆ 1587, 1427, 1258, 1111, 966, 827,
d ˆ 0.26 (s, 6H), 0.33 (s, 9H), 1.11 (s, 9H); 13C NMR (CDCl3): d ˆ À3.55,
À0.58, 20.64, 57.30; elemental analysis calcd (%) for C10H24Br2Si2: C 33.34,
H 6.71; found: C 33.30, H 6.83.
1
783, 739, 702, 671 cmÀ1; H NMR (CDCl3): d ˆ 0.25 (s, 6H), 0.26 (s, 6H),
1.82 (s, 3H), 7.32 7.44 (m, 6H), 7.59 (dd, J ˆ 1.8, 7.8 Hz, 4H); 13C NMR
(CDCl3): d ˆ À3.9, À3.4, 23.5, 44.1, 127.6, 129.5, 135.1, 136.7; elemental
analysis calcd (%) for C18H25BrSi2: C 57.28, H 6.68; found: C 57.39, H 6.71.
Dibromobis(dimethylphenylsilyl)methane (12j, prepared by method B):
Rf ˆ 0.61 (hexane/ethyl acetate 30:1); m.p. 638C; IR (Nujol): nÄ ˆ 1427, 1252,
1117, 839, 785, 735, 700, 640 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.33 (s, 12H),
1-Bromo-1,1-bis(methyldiphenylsilyl)ethane (25k): m.p. 1268C; IR (Nu-
7.32 7.46 (m, 6H), 7.67 (dd, J ˆ 1.5, 7.8 Hz, 4H); 13C NMR (CDCl3): d ˆ
À3.1, 56.0, 127.6, 130.1, 135.2, 135.6; elemental analysis calcd (%) for
C17H22Br2Si2: C 46.16, H 5.01; found: C 46.08, H 4.94.
1
jol): nÄ ˆ 1429, 1254, 1103, 999, 964, 797, 735, 698 cmÀ1; H NMR (CDCl3):
d ˆ 0.23 (s, 6H), 2.12 (s, 3H), 7.26 7.43 (m, 12H), 7.58 (dd, J ˆ 1.2, 7.8 Hz,
4H), 7.76 (dd, J ˆ 1.2, 7.8 Hz, 4H); 13C NMR (CDCl3): d ˆ À3.4, 24.5, 42.3,
127.6, 127.7, 129.6, 134.8, 135.3, 136.0, 136.3; elemental analysis calcd (%)
for C28H29BrSi2: C 67.05, H 5.63; found: C 66.86, H 5.87.
Dibromobis(methyldiphenylsilyl)methane (12k, prepared by method C):
m.p. 1748C; IR (Nujol): nÄ ˆ 1429, 1252, 1103, 814, 789, 719, 700 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.27 (s, 6H), 7.35 (dd, J ˆ 7.2, 8.1 Hz, 8H), 7.44 (t, J ˆ
7.2 Hz, 4H), 7.79 (d, J ˆ 8.1 Hz, 8H); 13C NMR (CDCl3): d ˆ À2.7, 50.2,
127.6, 130.1, 134.1, 136.5; elemental analysis calcd (%) for C27H26Br2Si2: C
57.25, H 4.63; found: C 56.98, H 4.53.
1-Bromo-1-(methyldiphenylsilyl)-1-(triethylgermyl)ethane (25l): Rf ˆ 0.51
(hexane/ethyl acetate 40:1); IR (neat): nÄ ˆ 2948, 2868, 1458, 1428, 1253,
1109, 1014, 791, 734, 698 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.75 (t, J ˆ 7.5 Hz,
6H), 0.79 (s, 3H), 0.96 (t, J ˆ 7.5 Hz, 9H), 2.03 (s, 3H), 7.30 7.45 (m, 6H),
7.72 (dd, J ˆ 1.5, 7.8 Hz, 2H), 7.85 (dd, J ˆ 1.5, 7.8 Hz, 2H); 13C NMR
(CDCl3): d ˆ À2.6, 5.0, 6.5, 9.4, 25.9, 127.5, 127.7, 129.4, 129.6, 135.1, 135.3,
135.7, 136.0; elemental analysis calcd (%) for C21H31BrGeSi: C 54.35, H
6.73; found: C 54.58, H 6.67.
Dibromo(methyldiphenylsilyl)(triethylgermyl)methane (12l, prepared by
method A from 12a and chlorotriethylgermane): Rf ˆ 0.47 (hexane/ethyl
acetate 40:1); IR (neat): nÄ ˆ 2950, 2870, 1460, 1427, 1252, 1111, 1014, 813,
696 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.82 0.92 (m, 6H), 0.87 (s, 3H), 0.96
1.04 (m, 9H), 7.37 7.47 (m, 6H), 7.86 7.92 (m, 4H); 13C NMR (CDCl3):
d ˆ À2.1, 6.4, 9.2, 53.3, 127.7, 130.0, 134.3, 136.3; elemental analysis calcd
(%) for C20H28Br2GeSi: C 45.42, H 5.34; found: C 45.14, H 5.22.
Procedure for the synthesis of 1,1-disilylethenes 29 by dehydrobromination
of 1-bromo-1,1-disilylethanes 25: A solution of 25 (9.0 mmol) and DBU
(2.7 mL, 18.0 mmol) in DMF (40 mL) was stirred for 8 h at 908C. The
mixture was carefully poured into 1m HCl and extracted with AcOEt. The
combined organic layers were dried over anhydrous Na2SO4 and concen-
trated in vacuo. Purification by silica-gel column chromatography or
recrystallization provided 29. Spectral data for 29i were identical with
those reported in the literature.[19a]
Procedure for the monomethylation of dibromodisilylmethanes 12 with
Me3MgLi: A solution of lithium trimethylmagnesate, [prepared by mixing
methylmagnesium bromide (10.8 mL, 0.93m solution in THF, 10 mmol) and
methyllithium (17.5 mL, 1.14m solution in Et2O, 20 mmol) in THF (15 mL)]
was added to a solution of 12 (10 mmol) in THF (50 mL) at À788C under
an argon atmosphere. After stirring for 0.5 h at À788C, the mixture was
carefully poured into 1m HCl and extracted with AcOEt. The combined
organic layers were dried over anhydrous Na2SO4 and concentrated in
vacuo. Purification by silica-gel column chromatography or recrystalliza-
tion provided 25.
1-(Methyldiphenylsilyl)-1-(trimethylsilyl)ethene (29 f): Rf ˆ 0.52 (hexane/
ethyl acetate 40:1); IR (neat): nÄ ˆ 2957, 1427, 1250, 1113, 972, 839, 789, 737,
1
723, 700 cmÀ1; H NMR (CDCl3): d ˆ À0.04 (s, 9H), 0.68 (s, 3H), 6.24 (d,
J ˆ 5.1 Hz, 1H), 6.55 (d, J ˆ 5.1 Hz, 1H), 7.30 7.40 (m, 6H), 7.48 (dd, J ˆ
2.1, 7.5 Hz, 4H); 13C NMR (CDCl3): d ˆ À2.7, À0.4, 127.7, 129.2, 135.3,
136.8, 144.9, 150.8; elemental analysis calcd (%) for C18H24Si2: C 72.90, H
8.16; found: C 72.86, H 8.06.
(1-Bromoethyl)methyldiphenylsilane (25a): Rf ˆ 0.36 (hexane/ethyl acetate
40:1); IR (neat): nÄ ˆ 2956, 1428, 1254, 1114, 1006, 790, 731, 697 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.73 (d, J ˆ 0.6 Hz, 3H), 1.74 (dd, J ˆ 0.6, 7.5 Hz,
1,1-Bis(triethylsilyl)ethene (29g): Rf ˆ 0.85 (hexane); IR (neat): nÄ ˆ 2955,
1
3H), 3.86 (q, J ˆ 7.5 Hz, 1H), 7.34 7.47 (m, 6H), 7.55 7.60 (m, 2H), 7.60
1462, 1416, 1236, 1005, 966, 814, 733 cmÀ1; H NMR (CDCl3): d ˆ 0.61 (q,
1738
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0807-1738 $ 20.00+.50/0
Chem. Eur. J. 2002, 8, No. 7

Alkylated Organomagnesium Compounds
1730 1740
J ˆ 7.8 Hz, 12H), 0.90 (t, J ˆ 7.8 Hz, 18H), 6.37 (s, 2H); 13C NMR (CDCl3):
d ˆ 3.5, 7.2, 143.3, 147.4; HRMS (m/z) calcd for C14H32Si2 256.2043; found:
256.2034.
Kitatani, H. Yamamoto, T. Hiyama, H. Nozaki, Bull. Chem. Soc. Jpn.
1977, 50, 2158; d) R. H‰ssig, H. Siegel, D. Seebach, Chem. Ber. 1982,
115, 1990; e) T. Harada, K. Hattori, T. Katsuhira, A. Oku, Tetrahedron
Lett. 1989, 30, 6035; f) T. Harada, T. Katsuhira, K. Hattori, A. Oku, J.
Org. Chem. 1993, 58, 2958; g) R. Inoue, H. Shinokubo, K. Oshima,
Tetrahedron Lett. 1996, 37, 5377; h) H. Kakiya, R. Inoue, H.
Shinokubo, K. Oshima, Tetrahedron 2000, 56, 2131; for the reaction
of dibromomethylsilanes, see: i) H. Kakiya, R. Inoue, H. Shinokubo,
K. Oshima, Tetrahedron Lett. 1997, 38, 3275; j) H. Kakiya, H.
Shinokubo, K. Oshima, Bull. Chem. Soc. Jpn. 2000, 73, 2139.
[6] a) K. Kitagawa, A. Inoue, H. Shinokubo, K. Oshima, Angew. Chem.
2000, 112, 2594; Angew. Chem. Int. Ed. 2000, 39, 2481; b) A. Inoue, K.
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1-(tert-Butyldimethylsilyl)-1-(trimethylsilyl)ethene (29h): Rf ˆ 0.81 (hex-
ane); IR (neat): nÄ ˆ 2957, 1472, 1408, 1362, 1248, 1148, 966, 837, 770,
675 cmÀ1; 1H NMR (CDCl3): d ˆ 0.08 (s, 6H), 0.09 (s, 9H), 0.85 (s, 9H), 6.34
(d, J ˆ 4.8 Hz, 1H), 6.43 (d, J ˆ 4.8 Hz, 1H); 13C NMR (CDCl3): d ˆ À4.4,
0.1, 17.1, 26.9, 142.9, 152.0; elemental analysis calcd (%) for C11H26Si2: C
61.60, H 12.22; found: C 61.39, H 12.48.
1,1-Bis(dimethylphenylsilyl)ethene (29j): Rf ˆ 0.53 (hexane/ethyl acetate
80:1); IR (neat): nÄ ˆ 1564, 1427, 1248, 1111, 968, 841, 781, 729, 700, 640 cmÀ1
1H NMR (CDCl3): d ˆ 0.25 (s, 12H), 6.41 (s, 2H), 7.25 7.36 (m, 6H), 7.38
;
7.44 (m, 4H); 13C NMR (CDCl3): d ˆ À2.0, 127.7, 128.9, 134.2, 139.0, 144.0,
151.0; elemental analysis calcd (%) for C18H24Si2: C 72.90, H 8.16; found: C
73.02, H 8.31.
1,1-Bis(methyldiphenylsilyl)ethene (29k): m.p. 1238C; IR (Nujol): nÄ ˆ 1427,
1261, 1113, 980, 829, 789, 739, 700 cmÀ1; 1H NMR (CDCl3): d ˆ 0.34 (s, 6H),
6.41 (s, 2H), 7.18 7.32 (m, 12H), 7.35 (d, J ˆ 7.5 Hz, 8H); 13C NMR
(CDCl3): d ˆ À2.8, 127.6, 129.1, 135.1, 136.4, 146.7, 149.6; elemental analysis
calcd (%) for C28H28Si2: C 79.94, H 6.71; found: C 79.83, H 6.80.
1-(Methyldiphenylsilyl)-1-(triethylgermyl)ethene (29l): Rf ˆ 0.49 (hexane);
IR (neat): nÄ ˆ 2948, 1428, 1251, 1111, 1015, 965, 808, 788, 735, 718, 697 cmÀ1
;
1H NMR (CDCl3): d ˆ 0.66 (s, 3H), 0.69 (q, J ˆ 7.8 Hz, 6H), 0.91 (t, J ˆ
7.8 Hz, 9H), 6.29 (d, J ˆ 4.5 Hz, 1H), 6.41 (d, J ˆ 4.5 Hz, 1H), 7.30 7.42 (m,
6H), 7.45 7.54 (m, 4H); 13C NMR (CDCl3): d ˆ À3.0, 4.6, 8.7, 127.7, 129.2,
135.2, 136.8, 143.8, 149.1; elemental analysis calcd (%) for C21H30GeSi: C
65.83, H 7.89; found: C 65.67, H 7.81.
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Acknowledgement
This work was supported by Grant-in-Aid for Scientific Research
(Nos. 10208208 and 12305058) from the Ministry of Education, Culture,
Sports, Science and Technology, Government of Japan. A.I. acknowledges
the Research Fellowships of the Japan Society for the Promotion of Science
for Young Scientists for financial support.
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X
R3Si
Mg
O
R3Si
+
'R
OH
nPr
nPr
H
R'
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¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0807-1739 $ 20.00+.50/0
1739

K. Oshima et al.
FULL PAPER
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Received: October 1, 2001 [F3581]
1740
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0947-6539/02/0807-1740 $ 20.00+.50/0
Chem. Eur. J. 2002, 8, No. 7