Cobalt-catalyzed isomerization of 1-alkenes to (E)-2-alkenes with dimethylphenylsilylmethylmagnesium chloride and its application to the stereoselective synthesis of (E)-alkenylsilane

Article abstract of DOI:10.1002/asia.200900111

Treatment of 1-alkenes with dimethylphenylsilylmethylmagnesium chloride in the presence of a cobalt-NHC complex in dioxane at 50°C or higher provides the corresponding (E)-2-alkenes selectively. The isomerization is applicable to the stereoselective synth

Full text of DOI:10.1002/asia.200900111

FULL PAPERS
DOI: 10.1002/asia.200900111
Cobalt-Catalyzed Isomerization of 1-Alkenes to (E)-2-Alkenes with
Dimethylphenylsilylmethylmagnesium Chloride and Its Application to the
Stereoselective Synthesis of (E)-Alkenylsilanes
Tsuneyuki Kobayashi, Hideki Yorimitsu,* and Koichiro Oshima*[a]
Abstract: Treatment of 1-alkenes with dimethylphenylsilylmethylmagnesium chlo-
ride in the presence of a cobalt-NHC complex in dioxane at 508C or higher pro-
vides the corresponding (E)-2-alkenes selectively. The isomerization is applicable
to the stereoselective synthesis of (E)-crotylsilanes and (E)-1-propenylsilanes from
the corresponding homoallylsilanes and allylsilanes, respectively.
Keywords: alkenes · alkenylsilanes ·
cobalt · Grignard reagents · isomer-
ization
Introduction
Transition-metal-catalyzed isomerization of alkenes is a
simple and well-studied transformation in organic chemis-
try.[1] However, highly selective isomerization of 1-alkenes
to (E)-2-alkenes is still difficult[2] because additional isomer-
ization reactions into 3-alkenes and other possible isomers
are often problematic. Most of the isomerization reactions
suffer from lack of E/Z selectivity and narrow substrate
Scheme 1. Previous results.
scope.
During the course of our studies on cobalt-catalyzed reac-
tions,[3,4] we recently reported cobalt-catalyzed dehydrohalo-
genation of 2-haloalkanes which yields 1-alkenes
(Scheme 1).[5] In this report, we disclosed that (E)-2-dode-
cene [(E)-2a] was selectively obtained when the elimination
reaction of 2-bromododecane was performed at 508C for
6 h. Apparently, the reaction initially afforded 1a within
45 min, and prolonged heating induced cobalt-catalyzed
gradual isomerization to (E)-2a. It is worth noting that fur-
ther isomerization to 3-dodecene and other internal dode-
cenes was negligible, probably because of the sufficient
bulkiness of the cobalt catalyst. In light of the importance of
the isomerization of terminal alkenes, we report herein de-
tailed studies on the cobalt-catalyzed selective isomerization
of 1-alkenes to (E)-2-alkenes.[6]
Results and Discussion
On the basis of the previous observation in Scheme 1, treat-
ment of 1-tetradecene (1b) with Me2PhSiCH2MgCl
(0.50 equiv) in the presence of CoCl2 and IMes·HCl (both
5 mol%) in dioxane at 508C for 6 h afforded (E)-2-tetrade-
cene [(E)-2b] with high selectivity (Table 1, entry 1). Trace
amounts of (Z)-2-tetradecene [(Z)-2b] and 3-tetradecene
(3b) were observed.
The choice of the Grignard reagent is quite important.
The use of the smaller Me3SiCH2MgCl yielded the larger
amount of 3b (Table 1, entry 2). Simple Grignard reagents
such as butyl-, methyl-, phenyl-, and allylmagnesium bro-
mide promoted isomerization with lower regio- and stereo-
selectivities (Table 1, entries 3–6).
[a] T. Kobayashi, Prof. Dr. H. Yorimitsu, Prof. Dr. K. Oshima
Department of Material Chemistry
Graduate School of Engineering
Kyoto University
Kyoto-daigaku Katsura, Nishikyo, Kyoto 615-8510 (Japan)
Fax : (+81)75-383-2438
E-mail: yori@orgrxn.mbox.media.kyoto-u.ac.jp
oshima@orgrxn.mbox.media.kyoto-u.ac.jp
The use of an N-heterocyclic carbene (NHC) ligand[7] is
essential to achieve the selective isomerization. The reaction
by using IPr·HCl provided (E)-2b stereoselectively, albeit
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.200900111.
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Chem. Asian J. 2009, 4, 1078 – 1083

Table 1. Isomerization of 1-tetradecene.[a]
tive (Table 1, entries 15–19). No reaction took place without
a cobalt salt (Table 1, entry 20).
Several terminal olefins were treated under the cobalt cat-
alysis (Table 2). The isomerization of tert-butyldimethylsilyl
Table 2. Cobalt-catalyzed isomerization of terminal olefins.
Entry
1
Deviation from
standard conditions
1b
recov.
[%]
(E)-2b
[%]
(Z)-2b
[%]
3b
[%][b]
none
3
79
2
2
Entry
R
Temp. [8C], (E)-2,
(Z)-2,
[%]
(E)-3,
[%]
Grignard reagent
Me3SiCH2MgCl
nBuMgBr
MeMgBr
PhMgBr
time [h]
[%]
2
3
4
5
6
3
0
0
0
0
88
62
67
64
76
1
19
14
8
8
2
19
28
19
1
A
50,
6
50,
6
100,
6
(E)-2c, (Z)-2c, (E)-3c,
81
(E)-2d, (Z)-2d, (E)-3d,
85 15
(E)-2e, (Z)-2e, (E)-3e,
65 18
(E)-2 f, (Z)-2 f, (E)-3 f
80
(E)-2g, (Z)-2g, (E)-3g,
61
N
2
5
2
N
R
0
CH2 =CHCH2MgCl
3
3
N
G
0
ACHTUNGTRENNUNG(Pre)Ligand
4[a]
5[a]
ACHTUGNTRENUN(NG CH2)7OC(=O)Mes 100,
N
7
8
9
10
11
12
13
14
IPr·HCl[c]
Mes·HASPO[c]
Ph3P
2
2
10
0
78
48
32
43
55
52
27
40
4
18
27
16
22
21
11
15
16
3
8
16
12
6
8
100,
8
0
4
A
0
0
tBu3P
(cC6H11)3P
Ph2PCH2CH2PPh2
Me2NCH2CH2NMe2
absence of ligand
0
[a] CoCl2 (10 mol%), IMes·HCl (10 mol%), and Me2PhSiCH2MgCl
(1.0 equiv) were used.
11
43
1
6
19
10-undecenyl ether (1c) proceeded smoothly to yield the
corresponding (E)-9-undecenyl ether (E)-2c with good se-
lectivity (Table 2, entry 1). However, protection of 10-unde-
cen-1-ol by a benzyl or tetrahydropyranyl (THP) group led
to lower regioselectivity (Table 2, entries 2 and 3). THP
ether 1e did not react at 508C, requiring a higher tempera-
ture. Protection of the hydroxy group by a bulky mesitylcar-
bonyl group was suitable, and the reaction of 1 f proceeded
with high selectivity without decomposition of the ester
bond (Table 2, entry 4). The less bulky benzoyl protection
was not compatible. Tosylamide 1g participated in the selec-
tive isomerization in boiling dioxane (Table 2, entry 5). The
curious effect of the functional groups in the substrates is
not clear.
The isomerization reaction was sensitive to the steric envi-
ronment around the double bond. The reaction of 4-methyl-
1-tetradecene (1h) in the presence of the cobalt catalyst
(5 mol%) and Me2PhSiCH2MgCl (0.50 equiv) at 508C failed
to proceed to completion within a reasonable reaction time.
A temperature as high as 1008C and one equivalent of the
Grignard reagent were essential to attain acceptable conver-
sion of 1h [Eq. (1)]. The isomerization of alkene 1i having a
quaternary carbon atom in proximity to the double bond
was sluggish, affording (E)-2i in 51% yield with remaining
1i (4%) and unidentified by-products [Eq. (2)].
Metal salt
PdCl2
NiCl2
CuCl2
MnCl2
15
16
17
18
19
20
80
85
89
91
80
97
4
2
0
0
8
0
3
2
0
0
0
0
0
0
0
0
0
0
FeCl3
no transition metal
1
[a] Yields were determined by H NMR analysis. [b] The E/Z ratios could
not be determined. [c]
with lower regioselectivity (Table 1, entry 7). Mes·HASPO[8]
as well as phosphine ligands were inferior to NHC ligands
(Table 1, entries 8–11). Bidentate ligands failed to serve well
(Table 1, entries 12 and 13), and no selectivity was observed
in the absence of ligand (entry 14).
Only a cobalt salt could catalyze the isomerization. Other
transition-metal salts such as NiCl2 and FeCl3 were ineffec-
Abstract in Japanese:
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1079

T. Kobayashi, H. Yorimitsu, and K. Oshima
FULL PAPERS
tive elimination to afford 2-alkene 2. We presume that one
(or two) dimethylphenylsilylmethyl group(s) would be locat-
ed on the cobalt atom since the size of the triorganosilyl
group has an influence on the selectivity (Table 1, entries 1
and 2). Degrees of steric repulsion in the transition states of
the b-hydride elimination account for the stereoselective for-
mation of (E)-2-alkenes. The b-hydride elimination should
proceed via a syn periplanar conformation 5a or 5b.[11] The
former is more preferable, minimizing the total steric repul-
sion.
To gain information about the reaction mechanism of the
isomerization, two deuterated alkenes [D2]-1j(T) and [D2]-
1a(I) were prepared and subjected to the isomerization
(Scheme 2). Terminally deuterated [D2]-1j(T) was isomer-
Stereoselective synthesis of (E)-crotylsilanes has been at-
tracting much attention.[12] The cobalt-catalyzed isomeriza-
tion is applicable to the synthesis of (E)-crotylsilanes from
homoallylsilanes (Table 3).[13] Exceptionally, the silyl group
Table 3. Isomerization of homoallylsilanes into (E)-2-crotylsilanes.
Entry
Si
7
7 recov. [%]
(E)-8, [%][a]
1
2
3
SiMe2Ph
SiMe2C6F5
SiMe2C6H4-m-CF3
7a
7b
7c
7d
7e
6
0
0
5
0
(E)-8a, 74
(E)-8b, 63[b]
(E)-8c, 77[c]
(E)-8d, 70
8e[e], 51
Scheme 2. Isomerization of deuterated 1-alkenes.
4
Si
ACHTUNGTRNE(NUNG SiMe3)3
ized into the corresponding (E)-2-alkene, leaving the deute-
rium atoms untouched. In addition, internally deuterated
[D2]-1a(I) was isomerized with deuterium transposition to
yield (E)-1,3-dideuterio-2-dodecene.
5[d]
SiMePh2
[a] E/Z ratios are greater than 99:1 unless otherwise noted. [b] CoCl2
(10 mol%), IPr·HCl (10 mol%), and Me3SiCH2MgCl (1.0 equiv) were
used. [c] Stereoisomer (Z)-8c and the corresponding (E)-1-butenylsilane
were obtained in 1% and 3% yields, respectively. [d] Catalyst
(10 mol%), Grignard reagent (1.0 equiv), 1008C, 6 h. [e] E/Z=75:25.
Contaminated with the corresponding (E)-1-butenylsilane (4% yield).
We tentatively propose the reaction mechanism as follows
(Figure 1). Low-valent cobalt 4 would be generated from
cobalt chloride, IMes·HCl, and Me2PhSiCH2MgCl. Terminal
olefin 1 would then coordinate to 4 to yield cobaltacyclopro-
pane 5.[9] Complex 5 would undergo b-hydride elimination
of homoallylsilane 7e is so bulky that 7e failed to undergo
highly selective isomerization (Table 3, entry 5). Whereas
the reaction of 7e at 508C resulted in recovery of 7e, the re-
action at 1008C yielded a mixture of isomers. Disiloxane 7 f
underwent the isomerization to (E)-8 f with exclusive E se-
to yield cobaltACHTUNGTRENNUNG
(allyl)hydride 6,[10] which is followed by reduc-
À
lectivity without affecting the Si O bonds [Eq. (3)].
Allylsilanes were successfully converted into the corre-
sponding (E)-1-propenylsilanes (Table 4). Each reaction
showed high E selectivity. It is worth noting that all the re-
actions did not proceed to completion, leaving small
amounts of the starting allylsilanes. Neither prolonged reac-
tion time nor higher loadings of the catalyst and/or the
Grignard reagent could improve conversion. We confirmed
by the following experiment [Eq. (4)] that the reaction
reached equilibrium between allylsilane and 1-propenylsi-
lane under the reaction conditions. Treatment of 10b (E/Z=
42:58) under the isomerization conditions afforded a mix-
ture of 10b (74%, E/Z=94:6) and allylsilane 9b (13%).
Figure 1. Plausible reaction mechanism.
1080
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Cobalt-Catalyzed Isomerization of 1-Alkenes to (E)-2-Alkenes
Table 4. Isomerization of allylsilanes into (E)-1-propenylsilanes.
Typical procedure for cobalt-catalyzed isomerization of 1-alkenes to (E)-
2-alkenes: The reaction of 1-tetradecene is representative (Table 1,
entry 1). Under argon atmosphere, cobalt(II) chloride (6.5 mg,
0.05 mmol), 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride (17.0 mg,
0.05 mmol), and dioxane (1.0 mL) were placed in a 20 mL reaction flask.
Dimethylphenylsilylmethylmagnesium chloride (1.0m THF solution,
0.5 mL, 0.5 mmol) was added to the suspension at 258C. After the result-
ing mixture was stirred for 2 min, 1-tetradecene (0.20 g, 1.0 mmol) in di-
oxane (1.0 mL) was added. After the mixture was heated at 508C for 6 h,
ammonium chloride solution was added. The products were extracted
with hexane three times. The combined organic layer was dried over an-
hydrous sodium sulfate and concentrated in vacuo. Silica gel column pu-
rification provided a mixture of 1-tetradecene, (E)-2-tetradecene, (Z)-2-
tetradecene, and (E)-3-tetradecene in 86% combined yield (172.0 mg,
0.86 mmol) in a ratio of 4:92:2:2.
Entry Si
9
Temp. [8C] 10, [%] E/Z 9 recov. [%]
1[a]
2
SiMePh2
SiMe2Ph
9a 50
9b 100
10a, 74 99:1
10b, 55 95:5
10c, 71 96:4 13
10d, 85 95:5 15
3
9
3[b]
4
SiMe2C6H4-m-CF3 9c 100
SiMe2A(OnC7H15) 9d 50
CHTUNGTRENNUNG
[a] IPr·HCl and Me3SiCH2MgCl were used instead of IMes·HCl and
Me2PhSiCH2MgCl. [b] CoCl2, IMes·HCl (10 mol% each), and
Me2PhSiCH2MgCl (1.0 equiv) were used.
Characterization data of new starting material: Compounds 1a, 1b, and
1j are commercially available. Compounds 1c,[14] 1d,[15] 1e,[15] 1g,[5] 7a,[16]
7 f,[17] 9a,[18] and 9b[18] were prepared and showed the spectra identical
with those shown in the literature.
The isomer distribution is essentially the same as that of
entry 2 in Table 4.
10-Undecenyl 2,4,6-trimethylbenzoate (1 f): Oil. IR (neat): n˜ =2927,
2855, 1726, 1612, 1436, 1265 cmÀ1 1H NMR (CDCl3): d=1.25–1.45 (m,
;
12H), 1.73 (dt, J=17.0, 7.0 Hz, 2H), 2.00–2.08 (m, 2H), 2.29 (s, 9H), 4.30
(t, J=7.0 Hz, 2H), 4.93 (d, J=10.0 Hz, 1H), 4.99 (d, J=17.0 Hz, 1H),
5.81 (ddt, J=10.0, 17.0, 7.0 Hz, 1H), 6.85 ppm (s, 2H); 13C NMR
(CDCl3): d=19.9, 21.3, 26.2, 28.9, 29.1, 29.3, 29.4, 29.6 (two signals
merge), 34.0, 65.2, 114.3, 128.5, 131.5, 135.1, 139.3, 139.3, 170.4 ppm;
HRMS (DI-EI+): m/z: observed: 316.2408 (D=+1.8 ppm), calcd for
C21H32O2 [M+]: 316.2402.
Conclusions
4-Methyl-1-tetradecene (1h): Oil. IR (neat): n˜ =3077, 2855, 1641, 1456,
910 cmÀ1 1H NMR (CDCl3): d=0.86 (d, J=7.0 Hz, 3H), 0.88 (t, J=
;
Cobalt-catalyzed Me2PhSiCH2MgCl-mediated isomerization
of 1-alkenes has emerged as a method for the selective syn-
thesis of (E)-2-alkenes. The bulky Grignard reagent and
NHC ligand realize high regio- and stereoselectivities. The
isomerization reaction is applicable to the stereoselective
synthesis of (E)-crotyl- and (E)-1-propenylsilanes.
In some cases, conversions of 1-alkenes were not perfect,
which would render isolation of the desired (E)-2-alkenes
difficult. However, further transformation of the alkene
moieties such as epoxidation should allow for selective for-
mation or separation of the desired final products.
7.0 Hz, 3H), 1.03–1.17 (m, 1H), 1.20–1.34 (m, 17H), 1.42–1.53 (m, 1H),
1.87 (dddq, J=7.0, 7.0, 14.3, 3.0 Hz, 1H), 2.06 (dddq, J=7.0, 7.0, 14.3,
3.0 Hz, 1H), 4.95–5.02 (m, 2H), 5.78 ppm (ddt, J=10.0, 17.0, 7.0 Hz,
1H); 13C NMR (CDCl3): d=14.3, 19.7, 22.9, 27.3, 29.6, 29.9 (three signals
merge), 30.2, 32.2, 33.0, 36.8, 41.7, 115.5, 138.0 ppm. Elemental analysis
(%) found: C 85.63, H 14.37; calcd for C15H30: C 85.67, H 14.58.
4,4-Dimethyl-1-decene (1i): Oil. IR (neat): n˜ =3076, 2930, 1639, 1469,
1366, 912 cmÀ1 1H NMR (CDCl3): d=0.84 (s, 6H), 0.88 (t, J=7.0 Hz,
;
3H), 1.10–1.35 (m, 10H), 1.93 (d, J=7.5 Hz, 2H), 4.94–5.04 (m, 2H),
5.80 ppm (ddt, J=9.0, 17.5, 7.5 Hz, 1H); 13C NMR (CDCl3): d=14.3,
23.0, 24.2, 27.2, 30.5, 32.2, 33.3, 42.2, 46.7, 116.6, 136.2 ppm. Elemental
analysis (%) found: C 85.82, H 14.67; calcd for C12H24: C 85.63, H 14.37.
(3-Butenyl)dimethyl(pentafluorophenyl)silane (7b): Oil. IR (neat): n˜ =
2916, 1642, 1517, 1458, 1285, 1087 cmÀ1 1H NMR (CDCl3): d=0.41 (dd,
;
J=2.0, 2.0 Hz, 6H), 0.98 (t, J=8.5 Hz, 2H), 2.05–2.12 (m, 2H), 4.90 (ddt,
J=1.5, 10.0, 1.5 Hz, 1H), 4.99 (ddt, J=1.5, 17.0, 1.5 Hz, 1H), 5.84 ppm
(ddt, J=10.0, 17.0, 6.0 Hz, 1H); 13C NMR (CDCl3) d=À1.5, 15.2, 27.8,
110.2, 113.7, 137.4 (dm), 140.7, 142.1 (dm), 149.2 ppm (dm); HRMS (DI-
EI+): m/z: observed: 280.0702 (D=À1.6 ppm), calcd for C12H13F5Si [M+
]: 280.0707.
Experimental Section
General: 1H NMR (500 MHz) and 13C NMR (125.7 MHz) spectra were
taken on a Varian UNITY INOVA 500 spectrometer and were obtained
in CDCl3 with tetramethylsilane as an internal standard. IR spectra were
taken 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 a 0.25 mm layer of Merck
silica gel 60F254. Silica gel (Wakogel 200 mesh) was used for column chro-
matography. Elemental analyses were carried out at the Elemental Anal-
ysis Center of Kyoto University.
(3-Butenyl)dimethyl(3-trifluoromethylphenyl)silane (7c): Oil. IR (neat):
1
n˜ =2959, 1640, 1410, 1320, 1126, 1074 cmÀ1; H NMR (CDCl3): d=0.31 (s,
6H), 0.88 (t, J=8.5 Hz, 2H), 2.02–2.11 (m, 2H), 4.90 (ddt, J=1.5, 10.0,
1.5 Hz, 1H), 4.98 (ddt, J=1.5, 17.0, 1.5 Hz, 1H), 5.86 (ddt, J=10.0, 17.0,
7.5 Hz, 1H), 7.47 (t, J=7.0 Hz, 1H), 7.60 (d, J=7.0 Hz, 1H), 7.68 (d, J=
7.0 Hz, 1H), 7.72 ppm (s, 1H); 13C NMR (CDCl3): d=À3.0, 14.8, 28.0,
113.3, 124.6 (q, J=271 Hz), 125.8 (q, J=3.8 Hz), 128.2, 130.1 (q, J=
3.8 Hz), 130.1 (q, J=31.5 Hz), 137.1, 140.9, 141.3 ppm; HRMS (DI-EI+):
m/z: observed: 258.1051 (D=À0.1 ppm), calcd for C13H17F3Si [M+]:
258.1052.
Unless otherwise noted, materials obtained from commercial suppliers
were used without further purification. Anhydrous CoCl2 was purchased
from Wako Pure Chemicals and was used after removal of water. Specifi-
cally, in each experiment, CoCl2 was dried in a reaction flask carefully
under reduced pressure (0.5 torr) by heating with a hair dryer for 2 min
immediately before use. Imidazolium salts, IMes·HCl was purchased
from Strem Chemicals. Dimethylphenylsilylmethylmagnesium chloride
was prepared from magnesium metal and the corresponding (chlorome-
thyl)dimethylphenylsilane in THF. Dioxane was dried over slices of
sodium. All reactions were carried out under argon atmosphere.
(3-Butenyl)tris(trimethylsilyl)silane (7d): Solid. IR (nujol): n˜ =2949,
1640, 1442, 1245, 834 cmÀ1; 1H NMR (CDCl3): d=0.17 (s, 27H), 0.81–0.89
(m, 2H), 2.08–2.15 (m, 2H), 4.89 (dt, J=10.0, 1.5 Hz, 1H), 4.98 (dt, J=
17.0, 1.5 Hz, 1H), 5.88 ppm (ddt, J=10.0, 17.0, 7.5 Hz, 1H); 13C NMR
(CDCl3): d=1.4, 7.4, 33.3, 112.9, 142.1 ppm; HRMS (DI-EI+): m/z: ob-
served: 302.1735 (D=À1.0 ppm), calcd for C13H34Si4 [M+]: 302.1738.
M.p. 57–608C.
Chem. Asian J. 2009, 4, 1078 – 1083
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1081

T. Kobayashi, H. Yorimitsu, and K. Oshima
FULL PAPERS
(3-Butenyl)diphenylmethylsilane (7e): Oil. IR (neat): n˜ =3069, 3049,
127.8, 128.4, 128.7, 129.8, 136.6, 137.3, 143.3 ppm; HRMS (DI-EI+): m/z:
observed: 329.1452 (D=+0.7 ppm), calcd for C19H23NO2S [M+]:
329.1449.
1428, 1252, 1113, 699 cmÀ1 1H NMR (CDCl3): d=0.71 (s, 3H), 1.29–1.37
;
(m, 2H), 2.22–2.32 (m, 2H), 5.04 (dd, J=1.5, 10.0 Hz, 1H), 5.14 (dd, J=
1.5, 17.0 Hz, 1H), 5.97–6.09 (m, 1H), 7.44–7.53 (m, 6H), 7.63–7.70 ppm
(m, 4H); 13C NMR (CDCl3): d=À4.2, 13.4, 28.0, 113.2, 128.0, 129.4,
134.6, 137.2, 141.4 ppm; HRMS (DI-EI+): m/z: observed: 252.1339 (D=
+1.8 ppm), calcd for C17H20Si [M+]: 252.1334.
4-Methyl-2-tetradecene (2h, E/Z=96:4): Oil. IR (neat): n˜ =2924, 2855,
1454, 1378, 966 cmÀ1 1H NMR (CDCl3): d=0.88 (t, J=7.0 Hz, 3H), 0.94
;
(d, J=7.0 Hz, 3H), 1.18–1.33 (m, 18H), 1.60 (dd, J=1.8, 6.8 Hz, 0.04ꢁ
3H), 1.64 (dd, J=1.8, 6.8 Hz, 0.96ꢁ3H), 1.92–2.09 (m, 1H), 5.28 (ddq,
J=6.0, 15.0, 1.5 Hz, 1H), 5.36 ppm (dq, J=15.0, 6.0 Hz, 1H); 13C NMR
(CDCl3) for E isomer, d=14.3, 18.2, 21.0, 22.9, 27.6, 29.6, 29.8, 29.9 (two
signals merge), 30.0, 32.2, 36.9, 37.4, 122.8, 138.0 ppm; HRMS (DI-EI+):
m/z: observed: 210.2344 (D=À1.9 ppm), calcd for C15H30 [M+]: 210.2348.
Dimethyl(2-propenyl)(3-trifluoromethylphenyl)silane (9c): Oil. IR
(neat): n˜ =3093, 2961, 1631, 1600, 1321 cmÀ1 1H NMR (CDCl3): d=0.32
;
(s, 6H), 1.77 (ddd, J=1.3, 1.3, 8.0 Hz, 2H), 4.84–4.87 (m, 1H), 4.87–4.90
(m, 1H), 5.74 (ddt, J=9.5, 18.0, 8.0 Hz, 1H), 7.47 (t, J=7.5 Hz, 1H), 7.61
(d, J=7.5 Hz, 1H), 7.68 (d, J=7.5 Hz, 1H), 7.73 ppm (s, 1H); 13C NMR
(CDCl3): d=À3.4, 23.6, 114.2, 124.6 (q, J=271 Hz), 125.9 (q, J=3.9 Hz),
128.2, 130.2 (q, J=31.5 Hz), 130.2 (q, J=3.8 Hz), 134.1, 137.2, 140.3 ppm;
HRMS (DI-EI+): m/z: observed: 244.0895 (D=0.0 ppm), calcd for
C12H15F3Si [M+]: 244.0895.
(E)-4,4-Dimethyl-2-decene (2i): Oil. IR (neat): n˜ =3025, 2859, 1455,
1362, 971, 911 cmÀ1 1H NMR (CDCl3): d=0.88 (t, J=7.0 Hz, 3H), 0.93
;
(s, 6H), 1.10–1.35 (m, 10H), 1.66 (dd, J=1.0, 6.0 Hz, 3H), 5.28 (dq, J=
15.5, 6.0 Hz, 1H), 5.37 ppm (dq, J=15.5, 1.0 Hz, 1H); 13C NMR (CDCl3):
d=14.3, 18.3, 22.9, 24.8, 27.6, 30.4, 32.2, 35.8, 43.6, 120.3, 141.8 ppm;
HRMS (DI-EI+): m/z: observed: 168.1878 (D=À0.2 ppm), calcd for
C12H24 [M+]: 168.1878.
Dimethylheptyloxy(2-propenyl)silane (9d): Oil. IR (neat): n˜ =2929, 2858,
1632, 1255, 1098 cmÀ1 1H NMR (CDCl3): d=0.11 (s, 6H), 0.88 (t, J=
;
7.0 Hz, 3H), 1.21–1.34 (m, 8H), 1.47–1.56 (m, 2H), 1.62 (ddd, J=1.0, 1.0,
8.0 Hz, 2H), 3.58 (t, J=7.0 Hz, 2H), 4.83–4.92 (m, 2H), 5.79 ppm (ddt,
J=15.0, 17.0, 8.0 Hz, 1H); 13C NMR (CDCl3): d=À2.3, 14.3, 22.8, 24.6,
26.0, 29.3, 32.0, 32.9, 63.2, 113.7, 134.3 ppm; HRMS (DI-EI+): m/z: ob-
served: 213.1684 (D=+4.5 ppm), calcd for C12H26OSi [(MÀH)+]:
213.1675.
Characterization data of products: Compounds (E)-2b,[19] (E)-8a,[20]
10a,[21] and 10b[22] showed the spectra identical with those shown in the
literature. The assignment of E/Z geometry was performed by focusing
on either the coupling constants of the vinylic protons or the chemical
shifts of the terminal allylic methyl groups.[19]
[(E)-2-Butenyl]dimethyl(pentafluorophenyl)silane ((E)-8b): Oil. IR
1
(neat): n˜ =2962, 1642, 1517, 1458, 1256, 1087 cmÀ1; H NMR (CDCl3): d=
0.38 (t, J=1.5 Hz, 6H), 1.62 (d, J=4.5 Hz, 3H), 1.76 (d, J=6.0 Hz, 2H),
5.26–5.39 ppm (m, 2H); 13C NMR (CDCl3): d=À2.0, 18.2, 21.7, 110.0,
124.9, 125.6, 137.4 (dm), 142.1 (dm), 149.2 ppm (dm); HRMS (DI-EI+):
m/z: observed: 280.0702 (D=À1.8 ppm), calcd for C12H13F5Si [M+]:
280.0707.
[(E)-2-Butenyl]dimethyl(3-trifluoromethylphenyl)silane ((E)-8c): Oil. IR
(neat): n˜ =2960, 1327, 1320, 1166, 1126, 841 cmÀ1 1H NMR (CDCl3): d=
;
0.32 (s, 6H), 1.66 (d, J=6.5 Hz, 3H), 1.69 (d, J=8.0 Hz, 2H), 5.26–5.35
(m, 1H), 5.35–5.46 (m, 1H), 7.48 (t, J=7.5 Hz, 1H), 7.62 (d, J=7.5 Hz,
1H), 7.70 (d, J=7.5 Hz, 1H), 7.77 ppm (s, 1H); 13C NMR (CDCl3): d=
À3.3, 18.2, 21.5, 124.7 (q, J=271 Hz), 124.8, 125.8 (q, J=3.8 Hz), 125.9,
128.1, 130.0 (q, J=31.5 Hz), 130.3 (q, J=3.8 Hz), 137.2, 140.6 ppm;
HRMS (DI-EI+): m/z: observed: 258.1053 (D=+0.6 ppm), calcd for
C13H17F3Si [M+]: 258.1052.
tert-Butyldimethylsilyl (E)-9-undecenyl ether ((E)-2c): Oil. IR (neat):
n˜ =2928, 2856, 1463, 1256, 1100, 965 cmÀ1 1H NMR (CDCl3): d=0.04 (s,
;
6H), 0.89 (s, 9H), 1.23–1.36 (m, 10H), 1.46–1.55 (m, 2H), 1.64 (d, J=
5.0 Hz, 3H), 1.91–2.06 (m, 2H), 3.59 (t, J=6.5 Hz, 2H), 5.36–5.46 ppm
(m, 2H); 13C NMR (CDCl3): d=À5.1, 18.1, 18.6, 26.0, 26.2, 29.3, 29.6,
29.7, 29.8, 32.8, 33.1, 65.5, 124.7, 131.9 ppm; HRMS (DI-EI+): m/z: ob-
served: 284.2545 (D=+3.2 ppm), calcd for C17H36OSi [M+]: 284.2535.
[(E)-2-Butenyl]tris(trimethylsilyl)silane ((E)-8d): Solid. IR (nujol): n˜ =
2331, 837, 404 cmÀ1 1H NMR (CDCl3): d=0.15 (s, 27H), 1.60 (ddt, J=
;
2.0, 6.0, 2.0 Hz, 3H), 1.66 (ddq, J=2.0, 8.0, 2.0 Hz, 2H), 5.21–5.30 (m,
1H), 5.38–5.48 ppm (m, 1H); 13C NMR (CDCl3): d=1.2, 13.0, 18.1, 122.0,
130.8 ppm; HRMS (DI-EI+): m/z: observed: 302.1740 (D=+0.7 ppm),
calcd for C13H34Si4 [M+]: 302.1738. M.p. 58–608C.
Benzyl (E)-9-undecenyl ether ((E)-2d): Oil. IR (neat): n˜ =2927, 2855,
1
1454, 1102, 965, 733 cmÀ1; H NMR (CDCl3): d=1.25–1.42 (m, 10H), 1.61
(dt, J=1.0, 7.5 Hz, 2H), 1.64 (dd, J=1.0, 3.5 Hz, 3H), 1.94–2.08 (m, 2H),
3.48 (t, J=6.5 Hz, 2H), 4.52 (s, 2H), 5.34–5.49 (m, 2H), 7.27–7.32 (m,
1H), 7.32–7.39 ppm (m, 4H); 13C NMR (CDCl3): d=18.1, 26.4, 29.3, 29.6,
29.7, 29.8, 30.0, 32.8, 70.7, 73.0, 124.7, 127.6, 127.8, 128.5, 131.8,
138.9 ppm; HRMS (DI-EI+): m/z: observed: 260.2141 (D=+0.5 ppm),
calcd for C18H28O [M+]: 260.2140.
(2-Butenyl)diphenylmethylsilane (8e, E/Z=75:25): Oil. IR (neat): n˜ =
3069, 2916, 1428, 1250, 1113, 699 cmÀ1 1H NMR (CDCl3): d=0.54 (s,
;
3H), 1.48 (d, J=6.5 Hz, 0.25ꢁ3H), 1.61 (d, J=6.5 Hz, 0.75ꢁ3H), 1.98
(d, J=8.0 Hz, 0.75ꢁ2H), 2.04 (d, J=8.0 Hz, 0.25ꢁ2H), 5.28–5.50 (m,
2H), 7.32–7.41 (m, 6H), 7.46–7.56 ppm (m, 4H); 13C NMR (CDCl3) for
E isomer, d=À4.5, 18.2, 20.3, 125.0, 127.9, 129.4, 134.7, 135.0, 137.1 ppm;
HRMS (DI-EI+): m/z: observed: 252.1325 (D=À3.5 ppm), calcd for
C17H20Si [M+]: 252.1334.
2-Oxacyclohexyl (E)-9-undecenyl ether ((E)-2e): Oil. IR (neat): n˜ =2927,
1454, 1353, 1201, 1184, 966 cmÀ1 1H NMR (CDCl3): d=1.22–1.38 (m,
;
10H), 1.48–1.62 (m, 6H), 1.64 (dd, J=1.0, 4.0 Hz, 3H), 1.68–1.75 (m,
1H), 1.78–1.88 (m, 1H), 1.92–2.07 (m, 2H), 3.33–3.39 (m, 1H), 3.48 (t,
J=7.0 Hz, 1H), 3.68–3.74 (m, 1H), 3.85 (t, J=10.5 Hz, 1H), 4.55 (s, 1H),
5.26–5.45 ppm (m, 2H); 13C NMR (CDCl3): d=19.9, 25.7, 26.4, 29.3, 29.5,
29.6, 29.7, 29.9, 30.9, 32.7, 32.8, 62.5, 67.8, 99.0, 124.7, 131.8 ppm; HRMS
(DI-EI+): m/z: observed: 254.2245 (D==À0.1 ppm), calcd for
C16H30O2[M+]: 254.2246.
1,1,3,3-Tetramethyl-1,3-bis[(E)-2-butenyl]disiloxane ((E)-8 f): Oil. IR
(neat): n˜ =3015, 2857, 1306, 1253, 1041, 798 cmÀ1 1H NMR (CDCl3): d=
;
0.05 (s, 12H), 1.43 (d, J=8.0 Hz, 4H), 1.65 (dd, J=1.5, 6.0 Hz, 6H),
5.23–5.32 (m, 2H), 5.34–5.43 ppm (m, 2H); 13C NMR (CDCl3): d=0.2,
18.3, 24.5, 123.9, 126.5 ppm; HRMS (DI-EI+): m/z: observed: 241.1442
(D=À0.9 ppm), calcd for C12H26OSi2 [(MÀH)+]: 241.1444.
(E)-9-Undecenyl 2,4,6-trimethylbenzoate ((E)-2 f): Oil. IR (neat): n˜ =
2927, 2855, 1725, 1612, 1435, 1266 cmÀ1 1H NMR (CDCl3): d=1.22–1.46
;
Dimethyl(1-propenyl)(3-trifluoromethylphenyl)silane (10c, E/Z=96:4):
Oil. IR (neat): n˜ =2929, 2855, 1620, 1319, 841 cmÀ1 1H NMR (CDCl3):
;
(m, 10H), 1.65 (dd, J=1.0, 3.0 Hz, 3H), 1.74 (dt, J=7.0, 15.0 Hz, 2H),
1.94–2.04 (m, 2H), 2.30 (s, 9H), 4.31 (t, J=6.5 Hz, 2H), 5.37–5.47 (m,
2H), 6.85 ppm (s, 2H); 13C NMR (CDCl3): d=18.1, 19.9, 21.3, 26.2, 28.8,
29.2, 29.4, 29.5, 29.7, 32.7, 65.2, 124.8, 128.5, 131.4, 131.7, 135.1, 139.3,
170.5 ppm; HRMS (DI-EI+): m/z: observed: 316.2407 (D=+1.5 ppm),
calcd for C21H32O2 [M+]: 316.2402.
d=0.35 (s, 6H), 1.72 (dd, J=1.5, 6.0 Hz, 0.04ꢁ3H), 1.87 (dd, J=1.5,
6.0 Hz, 0.96ꢁ3H), 5.66 (dq, J=14.0, 1.5 Hz, 0.04ꢁ1H), 5.78 (dq, J=18.0,
1.5 Hz, 0.96ꢁ1H), 6.17 (dq, J=18.0, 6.0 Hz, 0.96ꢁ1H), 6.58 (dq, J=14.0,
6.0 Hz, 0.04ꢁ1H), 7.46 (t, J=7.5 Hz, 1H), 7.60 (d, J=7.5 Hz, 1H), 7.70
(d, J=7.5 Hz, 1H), 7.75 ppm (s, 1H); 13C NMR (CDCl3) for E isomer,
d=À2.5, 22.9, 124.6 (q, J=271 Hz), 125.7 (q, J=3.8 Hz), 128.1, 128.4,
130.0 (q, J=31.5 Hz), 130.3 (q, J=3.8 Hz), 137.4, 140.9, 145.2 ppm;
HRMS (DI-EI+): m/z: observed: 244.0899 (D=+1.7 ppm), calcd for
C12H15F3Si [M+]: 244.0895.
N-Benzyl-N-(E)-3-pentenyl-p-toluenesulfonamide ((E)-2g): Oil. IR
(neat): n˜ =2920, 1455, 1339, 1161, 1092, 656 cmÀ1 1H NMR (CDCl3): d=
;
1.54 (dd, J=1.5, 6.5 Hz, 3H), 1.96–2.03 (m, 2H), 2.44 (s, 3H), 3.10 (t, J=
7.5 Hz, 2H), 4.33 (s, 2H), 5.10 (dtq, J=15.0, 7.0, 1.5 Hz, 1H), 5.27 (dtq,
J=15.0, 6.5, 1.0 Hz, 1H), 7.25–7.34 (m, 7H), 7.71–7.76 ppm (m, 2H);
13C NMR (CDCl3): d=18.1, 21.6, 31.6, 47.9, 52.0, 127.2, 127.3, 127.6,
Dimethylheptyloxy[(E)-1-propenyl]silane ((E)-10d): Oil. IR (neat): n˜ =
2930, 1621, 1445, 1251, 1097, 838 cmÀ1
;
1H NMR (CDCl3): d=0.14 (s,
1082
www.chemasianj.org
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2009, 4, 1078 – 1083

Cobalt-Catalyzed Isomerization of 1-Alkenes to (E)-2-Alkenes
6H), 0.87 (t, J=8.0 Hz, 3H), 1.21–1.34 (m, 8H), 1.46–1.56 (m, 2H), 1.82
(dd, J=2.0, 6.0 Hz, 3H), 3.55 (t, J=7.0 Hz, 2H), 5.65 (dq, J=18.5,
2.0 Hz, 1H), 6.18 ppm (dq, J=18.5, 6.0 Hz, 1H); 13C NMR (CDCl3): d=
À1.7, 14.3, 22.7, 22.8, 26.0, 29.3, 32.1, 32.9, 63.1, 129.4, 144.6 ppm; HRMS
(DI-EI+): m/z: observed: 213.1685 (D=+4.7 ppm), calcd for C12H26OSi
[(MÀH)+]: 213.1675.
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Acknowledgements
This work was supported by Grants-in-Aid for Scientific Research and
Global COE Research from JSPS.
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Received: March 23, 2009
Published online: May 28, 2009
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Chem. Asian J. 2009, 4, 1078 – 1083
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