Cobalt- and rhodium-catalyzed cross-coupling reaction of allylic ethers and halides with organometallic reagents

Article abstract of DOI:10.1016/j.tet.2005.11.032

Reactions of 2-alkenyl methyl ether with phenyl, trimethylsilylmethyl, and allyl Grignard reagents in the presence of cobalt(II) complexes are discussed. The success of the reactions heavily depends on the combination of the substrate, ligand, and Grignard reagent. In the reaction of cinnamyl methyl ether, the formation of the linear coupling products predominates over that of the relevant branched products. In the cobalt-catalyzed allylation of allylic ethers, addition of a diphosphine ligand can change the regioselectivity, mainly providing the corresponding branched products. Rhodium complexes catalyze the reactions of allylic ethers and halides with allylmagnesium chloride and allylzinc bromide, respectively, in which the branched coupling product is the major product.

Full text of DOI:10.1016/j.tet.2005.11.032

Tetrahedron 62 (2006) 1410–1415
Cobalt- and rhodium-catalyzed cross-coupling reaction of allylic
ethers and halides with organometallic reagents
Hiroto Yasui, Keiya Mizutani, Hideki Yorimitsu and Koichiro Oshima
* *
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku,
Kyoto 615-8510, Japan
Received 7 October 2005; revised 14 November 2005; accepted 15 November 2005
Available online 7 December 2005
Abstract—Reactions of 2-alkenyl methyl ether with phenyl, trimethylsilylmethyl, and allyl Grignard reagents in the presence of cobalt(II)
complexes are discussed. The success of the reactions heavily depends on the combination of the substrate, ligand, and Grignard reagent. In
the reaction of cinnamyl methyl ether, the formation of the linear coupling products predominates over that of the relevant branched products.
In the cobalt-catalyzed allylation of allylic ethers, addition of a diphosphine ligand can change the regioselectivity, mainly providing the
corresponding branched products. Rhodium complexes catalyze the reactions of allylic ethers and halides with allylmagnesium chloride and
allylzinc bromide, respectively, in which the branched coupling product is the major product.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
the only byproduct in each experiment, along with
untouched 1. The reaction of branched ether 3 with
Palladium-, nickel-, and copper-catalyzed cross-coupling
reactions of allylic substrates with organometallic reagents
are recognized as one of the most useful reactions catalyzed
phenylmagnesium reagent under CoCl (dpppen) catalysis
2
provided linear 2 selectively in good yield (Eq. 1). The
regioselectivity of the phenylations suggests that the
reactions proceed via a p-allylcobalt intermediate. The
phenylation reaction of 1 at 25 8C decreased the yield of 2.
The choice of the solvent was essential to obtain 2 in
satisfactory yield. A similar reaction in THF resulted in very
low conversion of 1.
1
by transition metals. On the other hand, cobalt-catalyzed
cross-coupling reactions of allylic substrates are quite rare.
2
We have been interested in cobalt-catalyzed cross-coupling
reactions. Here we report the reactions of allylic ethers with
3
phenyl, trimethylsilylmethyl, and allyl Grignard reagents in
the presence of cobalt complexes. Rhodium-catalyzed
coupling reactions are also disclosed herein.
4
5
Table 1. Cobalt-catalyzed reaction of cinnamyl methyl ether (1) with
phenylmagnesium bromide
2
. Results and discussions
CoCl (ligand) (5 mol%)
2
2.1. Cobalt-catalyzed phenylation reaction of allylic
ethers
PhMgBr (2.0 eq.)
Ph
OMe
Ph
Ph
ether, reflux, 16 h
1
2
The coupling reaction of cinnamyl methyl ether (1) with
phenylmagnesium bromide was first performed (Table 1). A
number of ligands were screened, and 1,5-bis(diphenyl-
phosphino)pentane (DPPPEN) proved to be most effective
for the phenylation reaction. 3,3-Diphenyl-1-propene was
not detected at all. A small amount of b-methylstyrene was
Entry
Ligand
None
Yield (%)
1
2
3
4
5
6
7
8
29
30
24
15
27
50
72
58
3
PPh (10 mol%)
DPPM
DPPE
DPPP
DPPB
DPPPEN
DPPH
Keywords: Cross-coupling reaction; Cobalt; Grignard reagent; Rhodium;
Allylzinc reagent.
*
Corresponding authors. Tel.: C81 75 383 2441; fax: C81 75 383 2438;
e-mail addresses: yori@orgrxn.mbox.media.kyoto-u.ac.jp;
oshima@orgrxn.mbox.media.kyoto-u.ac.jp
Ligands DPPM–DPPH represent Ph
DPPE; nZ3: DPPP; nZ4: DPPB; nZ5: DPPPEN; nZ6: DPPH.
2 2 n 2
P(CH ) PPh , nZ1: DPPM; nZ2:
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.11.032

H. Yasui et al. / Tetrahedron 62 (2006) 1410–1415
1411
Table 2. Cobalt-catalyzed phenylation reaction of trans-2-octenyl methyl
ether (4)
Co catalyst (5 mol%)
Me SiCH MgCl (2.0 eq.)
3
2
1
or 3
Ph
n
CoCl (5 mol%)
ligand
PhMgBr (2.0 eq.)
C H
Ph
Ph
5
6
SiMe3
2
5
11
11
ether, 20°C, 14 h
9
n
n
C H
OMe
C H
99% from 1 with CoCl2(dpph)
92% from 1 with CoCl2
98% from 1 with CoCl2(dppb)
93% from 3 with CoCl2(dpph)
5
11
5
ether, reflux, 16 h
4
Ph
7
n
nC5H11
SiMe3
C H
5
11
CoCl (dpph) (5 mol%)
2
10
Me SiCH MgCl (2.0 eq.)
Entry
Ligand (amount)
Combined
yield (%)
5/6/7
3
2
4
or 8
+
SiMe3
ether, reflux, 16 h
1
2
3
4
5
DPPPEN (5 mol%)
None
DPPE (5 mol%)
12
47
32
78
39
Not determined
58:10:32
10:53:37
36:7:57
66:!1:33
n
59% (10/11 = 63:37) from 4
92% (10/11 = 82:18) from 8
C H
5
11
11
PPh
3
(10 mol%)
6
P(2-MeC H
4
)
3
Scheme 1.
(10 mol%)
P(4-MeC
6
7
8
6
H
4
)
3
49
42:6:52
linear product 9 in 99% yield. Whereas the choice of the
ligand was crucial to establish the phenylation, ligandless
CoCl and CoCl (dppb) also effected the allylation to afford
(
10 mol%)
P[3,5-(CF
10 mol%)
P(4-MeOC
10 mol%)
3
)
2
C
6
H
3
]
3
Trace
41
Not determined
31:16:53
(
2
2
6 4 3
H )
9
3
in 92 and 98% yields, respectively. Reactions of branched
with Me SiCH MgCl afforded 9 in excellent yield. On the
(
3
2
other hand, alkyl-substituted allylic ethers 4 and 8 were
converted into mixtures of regioisomers 10 and 11. The
reaction required a higher temperature to complete the
reaction within a satisfactory reaction time. Trimethyl-
silylmethylation of branched ether 8 afforded a higher yield
of 10 and 11 than that of 4.
It is worth noting that treatment of cinnamyl bromide under
similar conditions furnished a mixture of dimeric
compounds such as 1,6-diphenyl-1,5-hexadiene and 3,4-
diphenyl-1,5-hexadiene, in addition to a trace of 2. The
formation of the dimeric products implies that single
electron transfer from a cobalt complex would yield
2
a,c,d
cinnamyl radical that is destined to dimerize.
2.3. Cobalt-catalyzed reaction of a,b-unsaturated
aldehyde dialkyl acetal
CoCl (dpppen) (5 mol%)
2
OMe
PhMgBr (2.0 eq.)
2
(1)
Treatment of acrolein diethyl acetal (12) with phenyl-
magnesium bromide in the presence of CoCl (PPh )
Ph
ether, reflux, 16 h, 60%
2
3 2
3
afforded a mixture of 2 and vinyl ether 13 (Scheme 2)
Formation of doubly phenylated 2 would indicate a reaction
path via the intermediate 14. Monophenylation of acetals 15
and 17 having substituents at the terminal olefinic positions
was successful under CoCl (dpppen) catalysis. The
2
dimethyl and phenyl groups of 16 and 18 would interfere
with further phenylation.
The cobalt-catalyzed phenylation reaction of trans-2-
octenyl methyl ether (4) required triphenylphosphine as a
ligand (Table 2, entry 4). A mixture of the corresponding
coupling products 5, 6, and 7 was obtained. Under the
reaction conditions, a part of 5 was transformed into 6. In
contrast to the reaction of 1, the use of CoCl (dpppen) led to
2
very poor conversion (entry 1). Without any phosphine
ligand, coupling products were obtained in moderate
combined yield (entry 2). Other monodentate phosphine
ligands were inferior to triphenylphosphine (entries 5–8).
Under CoCl (PPh ) catalysis, branched ether 8 was also
Ph
OEt
CoCl (PPh ) (5 mol%)
13 45% (E/Z = 1:1)
2
3 2
OEt
OEt
PhMgBr (3.0 eq.)
+
2
3 2
converted into 5 and 7 (Eq. 2), in which no isomerization
from 5 to 6 was observed.
Ph
via
Ph
ether, 20°C, 16 h
12
2
40%
OEt
CoCl (PPh ) (5 mol%)
2
3 2
OMe
PhMgBr (2.0 eq.)
Ph
5
+
7
14
n
C H
ether, reflux, 16 h
5
11
7
4% (50:50)
CoCl (dpppen) (5 mol%)
8
2
OEt
OEt
PhMgBr (3.0 eq.)
OEt
Ph
(2)
ether, reflux, 35 h
15
16 90%
2.2. Cobalt-catalyzed trimethylsilylmethylation reaction
of allylic ethers
CoCl (dpppen) (5 mol%)
2
OMe
OMe
PhMgBr (3.0 eq.)
OMe
Cross-coupling reaction with Me SiCH MgCl proceeded
2
3
Ph
ether, reflux, 35 h
Ph
Ph
much more smoothly than that with PhMgBr (Scheme 1).
Treatment of 1 with Me SiCH MgCl in the presence of
1
7
18 62%
3
2
CoCl (dpph) for 14 h at 20 8C afforded the corresponding
2
Scheme 2.

1412
H. Yasui et al. / Tetrahedron 62 (2006) 1410–1415
In contrast to the reaction with phenylmagnesium bromide,
bis(trimethylsilylmethylation) occurred in the reaction of 15
with 3 equimolar amounts of Me SiCH MgCl in refluxing
2.4. Cobalt-catalyzed cross-coupling reaction of
cinnamyl methyl ether with allyl Grignard reagent
3
2
dibutyl ether (Scheme 3). Intriguingly, in the reaction of 17,
we could completely control the distribution of the product
by changing the amount of the Grignard reagent and
reaction time. The reaction with 1.5 equimolar amounts of
Me SiCH MgCl at ambient temperature for 35 h afforded
To extend the scope of the cobalt-catalyzed cross-coupling
reactions, the allylation reaction of cinnamyl methyl ether
was examined. The regioselectivity of the title reaction
heavily depended on the ligand used (Table 3). Cobalt(II)
chloride by itself catalyzed the cross-coupling to yield linear
3
2
2
3 exclusively (entry 1). Addition of amines as a ligand did
monosubstituted product 20 exclusively in 85% yield. On
the other hand, treatment of 17 with 3 equimolar amounts of
the Grignard reagent in refluxing ether for 48 h furnished
doubly substituted product 21 in 94% yield.
not influence the regioselectivity (entries 2 and 3).
Phosphine ligands allowed us to obtain significant amounts
of branched 22. Among them, DPPP exhibited the highest
2
2/23 selectivity, 70:30.
CoCl (dpph) (5 mol%)
2
SiMe3
Judging from the results of Table 1, Scheme 1, and Table 3,
trimethylsilylmethylmagnesium reagent proved to be the
most reactive, and phenyl- and allylmagnesium reagents
have similar reactivity. The low reactivity of allylmagne-
sium reagent may be due to the formation of p-allylcobalt
that has less vacant coordination sites than phenyl- or
trimethylsilylmethylcobalt has and that hence interacts
weakly with the substrates at the initial oxidative addition
stage.
Me SiCH MgCl (3.0 eq.)
3
2
15
17
17
SiMe3
SiMe3
dibutyl ether, reflux, 66 h
1
9 53%
CoCl (dpph) (5 mol%)
2
Me SiCH MgCl (1.5 eq.)
OMe
3
2
ether, 20°C, 35 h
Ph
Ph
2
0 85%
CoCl (dpph) (5 mol%)
2
SiMe3
SiMe3
Me SiCH MgCl (3.0 eq.)
3
2
The reactions of 1 and 3 with other Grignard reagents
including vinylmagnesium bromide, methylmagnesium
iodide, and alkynylmagnesium bromide failed to yield
satisfactory amounts of the cross-coupling products.
ether, reflux, 48 h
2
1 94%
Scheme 3.
2.5. Rhodium-catalyzed cross-coupling reaction of allylic
ethers with allylmagnesium reagents
Table 3. Cobalt-catalyzed coupling reaction of 1 with allylmagnesium
bromide
Ph
Although the catalytic activity of rhodium is lower than that
of cobalt, rhodium complexes also catalyzed allylation of 1
(Scheme 4). Treatment of 1 with allylmagnesium chloride in
the presence of [RhCl(nbd)]2 (NBDZnorbornadiene) in
refluxing THF yielded the corresponding dienes in 47%
combined yield. The branched form 22 was mainly
obtained, and the selectivity is opposite to that of cobalt-
CoCl (5 mol%), Ligand
2
22
CH =CHCH MgBr (2.0 eq.)
2
2
Ph
OMe
+
ether, reflux, 18 h
Ph
23
1
Entry
Ligand
None
NBu
TMEDA
DPPE
DPPP
Yield (%)
22/23
1
2
3
4
5
6
7
78
79
75
57
70
54
32
!1:99
!1:99
!1:99
51:49
70:30
19:81
54:46
catalyzed allylation. The use of [RhCl(cod)] (CODZ1,5-
2
3
cyclooctadiene) instead of [RhCl(nbd)] slightly improved
2
the efficiency and selectivity of the reaction. Other rhodium
complexes such as Wilkinson’s catalyst and rhodium(III)
acetylacetonate as well as an iridium complex [IrCl(cod)]2
exhibited no catalytic activity. Branched ether 3 yielded 22
and 23 in good yield in a similar ratio under the
DPPB
DPPF
0
0
TMEDA and DPPF denote N,N,N ,N -tetramethylethylenediamine and
0
1
,1 -bis(diphenylphosphino)ferrocene, respectively.
[RhCl(cod)] catalysis.
2
Ph
Rh cat. (5 mol%)
2
2
CH =CHCH MgCl (2.0 eq.)
2
2
Ph
OMe
+
THF, reflux
Ph
23
1
[
RhCl(nbd)]2, 6 h, 47%, 22/23 = 77:23
[RhCl(cod)] , 12 h, 59%, 22/23 = 89:11
2
[
RhCl(cod)] (3 mol%)
2
OMe
CH =CHCH MgCl (2.0 eq.)
2
2
2
2
+
23
Ph
THF, reflux, 3 h
5
9%, 22/23 = 87:13
3
Scheme 4.

H. Yasui et al. / Tetrahedron 62 (2006) 1410–1415
1413
Table 4. Rhodium-catalyzed coupling reaction of cinnamyl chloride with allylzinc chloride
Ph
[
RhCl(cod)] (5 mol%)
2
Ligand
2
2
CH =CHCH ZnBr (2.0 eq.)
2
2
Ph
Cl
+
THF
Ph
23
Entry
Ligand
Temperature (8C)
Time (h)
Yield (%)
22/23
1
2
3
4
5
6
7
8
9
None
None
DPPB (10 mol%)
K80
K40
K40
K40
K40
K40
K40
K20
K20
K20
K20
K20
K20
2
0.5
2
3
2
3.5
6.5
1.5
1.5
1.5
1
No reaction
75
Trace
57
70
54
53
87
—
77:23
—
86:14
83:17
81:19
85:15
83:17
—
87:13
84:16
84:16
!1:99
PBu
NEt
NBu
3
(20 mol%)
(20 mol%)
(20 mol%)
3
3
TMEDA (10 mol%)
TMEDA (10 mol%)
TMEDA (2.0 equiv to substrate)
No reaction
10
11
12
13
Me
Me
2
NCH
N(CH
2
NMe
NMe
2
2
(10 mol%)
(10 mol%)
73
62
68
66
2
0
2
)
3
2,2 -Bipyridyl (10 mol%)
None, CoCl
1
3
2
2.6. Rhodium-catalyzed cross-coupling reaction
of cinnamyl chloride with allylzinc reagents
mechanism or the inner-sphere mechanism. The exact
mechanism is not clear at this stage.
Rhodium complexes also mediated the reaction of cinnamyl
chloride with allylzinc bromide (Table 4). The reaction at
K40 8C in the presence of [RhCl(cod)]2 for 30 min
furnished 22 and 23 in 75% yield in a ratio of 77:33
4. Experimental
4.1. Instrumental
(
entry 2). We screened many ligands to find that TMEDA is
1
13
the best ligand with respect to the regioselectivity as well as
the efficiency (entry 8). It is worth noting that a catalytic
amount of diphosphine ligands such as DPPB (entry 3) and a
stoichiometric amount of TMEDA (entry 9) completely
inhibited the reaction. Interestingly, ligandless CoCl2
effected the allylation to yield linear 23 exclusively (entry
H NMR (500 MHz) and C NMR (125.7 MHz) spectra
were taken on Varian UNITY INOVA 500 spectrometers
unless otherwise noted. H and C NMR spectra were
1
13
obtained in CDCl with tetramethylsilane as an internal
3
standard. Chemical shifts (d) are in parts per million relative
to tetramethylsilane at 0.00 ppm for H and relative to
1
1
CDCl at 77.2 ppm for C unless otherwise noted. IR
3
1
activity.
3). An iridium complex [IrCl(cod)] exhibited no catalytic
2
3
spectra were determined on a SHIMADZU FTIR-8200PC
spectrometer. Mass spectra were determined on a JEOL
Mstation 700 spectrometer. TLC analyses were performed
on commercial glass plates bearing 0.25-mm layer of Merck
Silica gel 60F254. Silica gel (Wakogel 200 mesh) was used
for column chromatography. The analyses were carried out
at the Elemental Analysis Center of Kyoto University.
3. Conclusion
The cobalt-catalyzed cross-coupling reaction with phenyl
Grignard reagent proved to be a function of a substrate as
well as of solvent and ligand. To attain high yields in the
phenylation reaction, intensive tunings of variants are
needed. In contrast, introduction of trimethylsilylmethyl
group was facile and clean under cobalt catalysis. The
reactions of cinnamyl methyl ether with both phenyl and
trimethylsilylmethyl Grignard reagents yielded the corre-
sponding linear products, irrespective of reaction con-
ditions. The cross-coupling reactions of allylic ethers with
allyl Grignard reagent with the aid of ligandless cobalt(II)
chloride afforded the corresponding linear dienes. Interest-
ingly, addition of DPPP could reverse the regioselectivity,
leading to predominant formation of the branched dienes.
Rhodium complexes catalyzed the reactions of allylic ethers
and halides with allylmagnesium chloride and allylzinc
bromide, respectively. Under rhodium catalysis, the
branched coupling product was primarily formed. In both
cobalt- and rhodium-catalyzed systems, p-allylmetal inter-
mediates would be the key intermediates. The regio-
selectivity would depend on the ways how the carbon–
carbon bonds are formed, that is, via the outer-sphere
4.2. Material
Unless otherwise noted, materials obtained from commer-
cial suppliers were used without further purification. THF
and ether were purchased from Kanto Chemical Co., stored
under nitrogen, and used as they are. The starting materials
1, 3, 4, and 8 are prepared by the conventional Williamson
ether synthesis.
4.3. General procedure for the cross-coupling reactions
with Grignard reagents
The reaction of 1a with trimethylsilylmethyl Grignard
reagent is representative. Anhydrous CoCl2 (7 mg,
0.05 mmol) was placed in a 50-mL two-necked flask and
heated with a hair dryer in vacuo for 3 min. DPPH (27 mg,
0.06 mmol) and ether (1 mL) were sequentially added under
argon. After the mixture was stirred for 30 min to obtain
blue suspension, cinnamyl methyl ether (1a, 0.15 g,

1414
H. Yasui et al. / Tetrahedron 62 (2006) 1410–1415
1
.0 mmol) and Me SiCH MgCl (1.0 M in ether, 2.0 mL,
3
1.95–2.02 (m, 0.82!4H), 1.23–1.37 (m, 0.82!6HC
0.18!8H), 0.88 (t, JZ7.0 Hz, 3H), 0.55–0.59 (m, 2H),
2
2.0 mmol) were successively added to the reaction mixture
at 0 8C. After being stirred for 14 h at 20 8C, the reaction
1
K0.01 (s, 9H); C NMR (CDCl ). For major isomer, d
3
3
mixture was poured into saturated NH Cl solution. The
4
113.03, 128.87, 32.48, 31.44, 29.35, 26.85, 22.57, 16.58,
14.08, K1.58. For minor isomer, d 145.53, 112.56, 40.38,
38.55, 31.93, 23.26, 22.69, 14.12, K0.58. One of the
products were extracted with ethyl acetate (20 mL!3) and
the combined organic layer was dried over sodium sulfate
and concentrated. Silica gel column purification of the crude
product provided 9 (0.20 g, 0.99 mmol) in 99% yield as
colorless oil.
3
sp -hybridized carbons of 11 could not been observed,
probably due to overlapping. Found: C, 72.34; H, 12.94%.
Calcd for C H Si: C, 72.69; H, 13.21%.
1
2 26
4.4. Rhodium-catalyzed cross-coupling reactions of
cinnamyl chloride with allylzinc bromide
4.5.3. 1-Ethoxy-3-methyl-1-phenyl-2-butene (16). IR
K1
1
(neat) 2974, 2930, 1425, 1086, 756, 698 cm ; H NMR
CDCl ) d 7.31–7.35 (m, 4H), 7.26–7.23 (m, 1H), 5.35 (d,
(
3
Zinc powder (2.94 g, 45 mmol) was placed in a 50-mL
reaction flask under argon. THF (3.4 mL) was added.
Chlorotrimethylsilane (0.1 mL, 0.8 mmol) and dibromo-
ethane (0.1 mL, 2 mmol) were sequentially added at
ambient temperature to activate zinc. After the mixture
was stirred for 5 min, allyl bromide (2.6 mL, 30 mmol) in
THF (24 mL) was added dropwise to the suspension with
vigorous stirring over 15 min at 0 8C. The mixture was
stirred for an additional 1 h at 25 8C. The gray supernatant
liquid obtained was transferred to another flask filled with
argon. The concentration of allylzinc bromide was
determined by quantitative allylation reaction of an excess
of benzaldehyde with allylzinc bromide prepared. The
concentration was 0.87 M. [RhCl(cod)]2 (25 mg,
JZ9.0 Hz, 1H), 5.01 (d, JZ9.0 Hz, 1H), 3.45–3.51 (m, 1H),
3.35–3.42 (m, 1H), 1.79 (s, 3H), 1.74 (s, 3H), 1.22 (t,
1
3
JZ6.8 Hz, 3H); C NMR (CDCl ) d 142.81, 134.99,
3
128.40, 127.19, 126.59, 126.43, 78.13, 63.39, 25.91, 18.40,
15.36. Found: C, 81.84; H, 9.54%. Calcd for C H O: C,
82.06; H, 9.54%.
1
3 18
4
methyl)-2-pentene (19). IR (neat) 2953, 2909, 1248, 837,
.5.4.
2-Methyl-5-trimethylsilyl-4-(trimethylsilyl-
K1
1
6
2
92 cm ; H NMR (CDCl ) d 4.86 (d, JZ10.0 Hz, 1H),
3
.51–2.58 (m, 1H), 1.62 (s, 3H), 1.59 (s, 3H), 0.67 (dd,
JZ14.7, 5.3 Hz, 2H), 0.57 (dd, JZ14.7, 8.5 Hz, 2H),
1
K0.17 to 0.07 (m, 18H); C NMR (CDCl ) d 134.73,
3
3
126.19, 30.41, 28.54, 25.63, 18.19, K0.72. Found: C, 64.59;
H, 12.24%. Calcd for C H Si : C, 64.38; H, 12.47%.
0
.05 mmol) was placed in another 50-mL two-necked
flask under argon. THF (5 mL) and TMEDA (15 mL,
.10 mmol) were successively added. The resulting solution
was stirred for 5 min. Cinnamyl chloride (153 mg,
.0 mmol, dissolved in 5 mL of THF) was added. The
solution was cooled at K20 8C, and allylzinc bromide
0.87 M in THF, 2.3 mL, 2.0 mmol) was added. After being
1
3
30
2
0
4
.5.5. (E)-3-Methoxy-4-trimethylsilyl-1-phenyl-1-butene
1
(20). H NMR (300 MHz, CDCl ) d 7.30–7.41 (m, 4H),
3
1
7
.22–7.25 (m, 1H), 6.48 (d, JZ15.9 Hz, 1H), 6.01 (dd,
JZ15.9, 8.4 Hz, 1H), 3.81 (q, JZ7.8 Hz, 1H), 3.27 (s, 3H),
(
1
1
1
.14 (dd, JZ14.3, 6.8 Hz, 1H), 0.94 (dd, JZ14.3, 7.7 Hz,
13
stirred for 1.5 h at K20 8C, the reaction mixture was poured
into 1 M hydrochloric acid. The product was extracted with
ethyl acetate (2!20 mL). The combined organic phase
was dried over sodium sulfate. Evaporation followed by
silica gel column purification afforded a mixture of 22
and 23 (137 mg, 0.87 mmol, 87% combined yield) in a ratio
of 83:17.
H), 0.03 (s, 9H); C NMR (75 MHz, CDCl ) d 132.04,
31.15, 128.49, 127.51, 126.34, 106.68, 80.60, 55.72, 25.05,
3
K0.62. Found: C, 71.79; H, 9.45%. Calcd for C H OSi:
1
4 22
C, 71.73; H, 9.46%.
4.5.6. (E)-1-Phenyl-4-trimethylsilyl-3-(trimethylsilyl-
methyl)-1-butene (21). H NMR (300 MHz, CDCl ) d
1
3
7
1
0
.28–7.33 (m, 4H), 7.15–7.21 (m, 1H), 6.27 (d, JZ15.6 Hz,
H), 5.98 (dd, JZ15.6, 9.0 Hz, 1H), 2.47–2.59 (m, 1H),
.70–0.84 (m, 4H), K0.02 (s, 18H); C NMR (75 MHz,
4
.5. Characterization data
1
3
6
6
7
8
9
The spectral data of the products 5, 6, 7, 13, 18, 22,
10
CDCl ) d 139.22, 128.37, 126.61, 126.54, 125.82, 106.68,
3
36.42, 28.13, K0.41. Found: C, 70.21; H, 10.28%. Calcd for
C H Si : C, 70.26; H, 10.41%.
1
and 23 are found in the literature.
0
1
7
30
2
4
(
.5.1. (E)-4-Trimethylsilyl-1-phenyl-1-butene (9). IR
neat) 3061, 2953, 2903, 1497, 1248, 962, 862, 837,
K1
1
6
7
92 cm
;
H NMR (CDCl ) d 7.27–7.35 (m, 4H),
3
Acknowledgements
.17–7.20 (m, 1H), 6.37 (d, JZ16.0 Hz, 1H), 6.27 (dt,
JZ16.0, 6.5 Hz, 1H), 2.23 (ddt, JZ10.0, 1.0, 6.5 Hz, 2H),
0
1
.68–0.71 (m, 2H), K0.10 to 0.16 (m, 9H); C NMR
3
This work is supported by Grants-in-Aid for Scientific
Research, Young Scientists, and COE Research from the
Ministry of Education, Culture, Sports, Science, and
Technology, Japan.
(
CDCl ) d 137.98, 133.83, 128.45, 128.26, 126.66, 125.87,
3
2
7.39, 16.27, K1.59. Found: C, 76.27; H, 9.73%. Calcd for
C H Si: C, 76.40; H, 9.86%.
1
3 20
4
.5.2. (E)-1-(Trimethylsilyl)-3-nonene/3-(trimethylsilyl-
methyl)-1-octene (10/11Z82:18). IR (neat) 2955, 2926,
K1
1
1
460, 1248, 968, 862, 835, 756, 691 cm
;
H NMR
CDCl ) d 5.52–5.59 (m, 0.18!1H), 5.35–5.46 (m, 0.82!
References and notes
(
3
2
H), 4.91 (ddd, JZ17.0, 2.0, 0.5 Hz, 0.18!1H), 4.87 (ddd,
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