One-pot synthesis of internal conjugated (Z)-enynyltrimethylsilanes possessing aryl, cycloalkenyl, (E)- or (Z)-alk-l-enyl moieties on the sp carbon atom via two types of cross-coupling reaction

Article abstract of DOI:10.1055/s-0028-1083201

Described herein is an operationally simple and mild method for the stereospecific synthesis of internal conjugated (Z)-enynyltrimethylsilanes whose conjugation is extended away from the distal alkynyl carbon atom. This protocol involves two types of cross-coupling reaction, a Suzuki-type reaction and a sila-Sonogashira reaction, and the desired synthesis can be performed in a one-pot manner. Thus, the copper-mediated cross-coupling reaction of dicyclohexyl[(Z)-1-(trimethylsilyl)alk-l-enyl]boranes with (trimethylsilyl) ethynyl bromide is carried out in the presence of aqueous lithium hydroxide at -15 °C to room temperature, resulting in the stereospecific formation of (Z)-1,3-bis(trimethylsilyl)alk-3-en-1-ynes. Subsequent reaction is allowed to proceed without isolation of the enynes. Thus, palladium/copper-catalyzed cross-coupling reactions with aryl iodides, cycloalk-1-enyl triflates, and (E)- and (Z)-alk-1-enyl iodides can be accomplished in the presence of either 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or tetrabutylammonium fluoride (TBAF) at ambient temperature to provide the corresponding internal conjugated (Z)-enynyltrimethylsilanes possessing one more sp-sp² carbon bond. Georg Thieme Verlag Stuttgart · New York.

Full text of DOI:10.1055/s-0028-1083201

PAPER
3591
One-Pot Synthesis of Internal Conjugated (Z)-Enynyltrimethylsilanes
Possessing Aryl, Cycloalkenyl, (E)- or (Z)-Alk-1-enyl Moieties on the sp
Carbon Atom via Two Types of Cross-Coupling Reaction
One-Pot Synthesis of
I
a
nternal Con
s
jugate
d
(
Z
a
)
-Enynyltri
y
methylsilane
u
s
ki Hoshi,* Tomohiko Iizawa, Mitsuhiro Okimoto, Kazuya Shirakawa
Department of Biotechnology and Environmental Chemistry, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507,
Japan
Fax +81(157)247719; E-mail: hoshi-m@chem.kitami-it.ac.jp
Received 14 July 2008; revised 12 August 2008
groups is located on the internal alkenyl carbon atom,
Abstract: Described herein is an operationally simple and mild
have been synthesized by cross-coupling of dicyclohex-
method for the stereospecific synthesis of internal conjugated (Z)-
enynyltrimethylsilanes whose conjugation is extended away from
the distal alkynyl carbon atom. This protocol involves two types of
yl[(Z)-1-(trimethylsilyl)alk-1-enyl]boranes 1 with (tri-
methylsilyl)ethynyl bromide, as reported by our group.6
cross-coupling reaction, a Suzuki-type reaction and a sila-Sono- The cross-coupling reaction proceeded in the presence of a
gashira reaction, and the desired synthesis can be performed in a
catalytic amount of copper(I) iodide and a stoichiometric
one-pot manner. Thus, the copper-mediated cross-coupling reaction
amount of aqueous sodium hydroxide under very mild
of dicyclohexyl[(Z)-1-(trimethylsilyl)alk-1-enyl]boranes with (tri-
conditions, giving products 2 stereospecifically in good to
methylsilyl)ethynyl bromide is carried out in the presence of aque-
high yield. Compound 2 has two trimethylsilyl groups,
ous lithium hydroxide at –15 °C to room temperature, resulting in
the stereospecific formation of (Z)-1,3-bis(trimethylsilyl)alk-3-en-
one on an sp2 carbon atom and the other on an sp carbon
atom, the latter, in particular, can be utilized for C–C bond
formation. Thus, it is feasible to assemble p-extended
conjugation taking advantage of the desilylative Sono-
gashira–Hagihara reaction (sila-Sonogashira reaction)7–9
(Scheme 1). Herein, we report a one-pot synthesis of in-
ternal conjugated (Z)-enynyltrimethylsilanes, in which ar-
yl, cycloalkenyl, (E)- or (Z)-alk-1-enyl moieties are
installed on the distal alkynyl carbon atom, via a Suzuki-
type reaction/sila-Sonogashira reaction sequence.
1-ynes. Subsequent reaction is allowed to proceed without isolation
of the enynes. Thus, palladium/copper-catalyzed cross-coupling re-
actions with aryl iodides, cycloalk-1-enyl triflates, and (E)- and (Z)-
alk-1-enyl iodides can be accomplished in the presence of either
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or tetrabutylammonium
fluoride (TBAF) at ambient temperature to provide the correspond-
ing internal conjugated (Z)-enynyltrimethylsilanes possessing one
more sp–sp2 carbon bond.
Key words: (Z)-enynyltrimethylsilane, (trimethylsilyl)ethynyl bro-
mide, (Z)-1,3-bis(trimethylsilyl)alk-3-en-1-yne, Suzuki-type reac-
tion, sila-Sonogashira reaction
Initially, the sila-Sonogashira reaction with an aryl iodide
was explored. (Z)-1,3-Bis(trimethylsilyl)oct-3-en-1-yne
(2a) and iodobenzene were selected as substrates to opti-
Alkenylsilanes are significant intermediates for a variety mize the reaction conditions. Thus, the cross-coupling
of synthetic processes including electrophilic reaction of dicyclohexyl[(Z)-1-(trimethylsilyl)hex-1-
substitutions1 and palladium-catalyzed cross-couplings.2 enyl]borane (1a) (1 mmol) with (trimethylsilyl)ethynyl
1,4-Disilylbut-1-en-3-ynes are regarded as alkenylsilanes bromide (0.67 mmol) was conducted in the presence of
possessing a conjugated C≡C bond and useful building copper(I) iodide (0.1 mmol) and 1 M sodium hydroxide
blocks for a conjugated four-carbon homologation. The (0.75 mmol) at –15 °C to room temperature overnight to
synthesis of 1,4-bis(trimethylsilyl)but-1-en-3-yne and generate compound 2a (ca. 0.6 mmol).10 On the basis of
substituted derivatives thereof has been performed by car- the conditions reported by Brisbois and Grieco,8e com-
bometalation of 1,4-bis(trimethylsilyl)butadiyne with tri- pound 2a was subjected to reaction with iodobenzene (0.5
methylaluminum,3 titanation of 1,4-bis(trimethyl- mmol) in a one-pot manner at room temperature over-
silyl)butadiyne,4 and nickel-catalyzed dimerization of night.11 The typical results are shown in Table 1. Use of
silylethyne.5 On the other hand, (Z)-1,3-bis(trimethylsi- 1,8-diazabicyclo[5.4.0]undec-7-ene (6 mmol) and dichlo-
lyl)alk-3-en-1-ynes 2, in which one of the trimethylsilyl robis(triphenylphosphine)palladium (0.02 mmol) gave
CBr
CuI, Me3SiC
1 M NaOH
2B
R1
R1
Me3Si
_15 °C to r.t.
R1
1
Me3Si
SiMe3
SiMe3
2
Scheme 1
SYNTHESIS 2008, No. 22, pp 3591–3600
x
x.
x
x
.
2
0
0
8
Advanced online publication: 23.10.2008
DOI: 10.1055/s-0028-1083201; Art ID: F16208SS
© Georg Thieme Verlag Stuttgart · New York

3592
M. Hoshi et al.
PAPER
the desired product, (Z)-1-phenyl-3-(trimethylsilyl)oct-3- aryl iodides to afford products 3 in moderate to good
en-1-yne (3aa), albeit in moderate yield (Table 1, entry 1). yields. This sila-Sonogashira reaction was successfully
We previously observed that the Sonogashira reaction of applied to compound 2 with a structurally and electroni-
terminal conjugated enynes was occasionally promoted cally diverse substituent (R1) (Table 2, entries 1–4). Elec-
by the addition of a lithium salt.12 This prompted us to ex- tron-donating as well as electron-withdrawing aryl
amine the reaction with iodobenzene in the presence of iodides could be used as coupling partners (Table 2, en-
lithium chloride (0.75 mmol), but otherwise under identi- tries 5–9). In the reaction with sterically hindered 2-iodo-
cal conditions. To our delight, the yield of product 3aa im- toluene, the desired product 3ad was obtained in good
proved considerably (Table 1, entry 2). This observation yield (Table 2, entry 7). Interestingly, the reactions with
would give us some insight into modification of the pro- 1-chloro- and 1-bromo-4-iodobenzene provided products
cess. Reducing the loading of dichlorobis(triphenylphos- 3ae and 3af, leaving the chloro and bromo moieties un-
phine)palladium, by contrast, gave a lower yield (Table 1, touched under the reaction conditions (Table 2, entries 8
entry 3). Considering the mechanism of the Suzuki– and 9). It should be noted that heteroaromatic iodides such
Miyaura reaction, the metal cation of an inorganic base, as 2-iodothiophene and 3-iodopyridine were also good
such as sodium hydroxide, is held by a halide anion liber- substrates for this sila-Sonogashira reaction (Table 2, en-
ated from organic halide.13 In the cross-coupling reaction tries 10 and 11).
with (trimethylsilyl)ethynyl bromide, changing the base
from sodium hydroxide to lithium hydroxide will lead to
Next we investigated the one-pot synthesis of both
(1Z,5E)-2-(trimethylsilyl)alka-1,5-dien-3-ynes
4
and
the formation of lithium bromide, and hence the addition
of a lithium salt will not be necessary for the sila-Sono-
gashira coupling step. We thus examined a sequence of
reactions using lithium hydroxide monohydrate instead of
1 M sodium hydroxide solution. The use of lithium hy-
droxide monohydrate (0.75 mmol) and water (0.375 mL)
gave an unsatisfactory result (Table 1, entry 4); however,
on increasing the amount of water (0.75 mL), the yield of
product 3aa improved dramatically (Table 1, entry 5). In
the cross-coupling reaction of 1a with (trimethylsi-
lyl)ethynyl bromide using aqueous lithium hydroxide, the
yield of compound 2a was nearly constant regardless of
the amount of water.14 Thus it is clear that the sila-Sono-
gashira reaction is affected by water, but the reason is un-
clear at present.
(1Z,5Z)-2-(trimethylsilyl)alka-1,5-dien-3-ynes 5 via a
sila-Sonogashira reaction with (E)- and (Z)-alk-1-enyl io-
dides. The cross-coupling reaction of 2a, generated by the
reaction between 1a and (trimethylsilyl)ethynyl bromide,
with (E)-1-iodohex-1-ene, the selected substrate, was car-
ried out under several conditions based on the optimal
conditions for the synthesis of 3 mentioned above. It was
found that only the amount of 1,8-diazabicyclo[5.4.0]un-
dec-7-ene was reduced to half to give the best result. Thus,
the reaction with (E)-1-iodohex-1-ene (2 mmol) was run
in the presence of dichlorobis(triphenylphosphine)palla-
dium (0.08 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-
ene (12 mmol) at room temperature under argon. Table 3
summarizes the results of the synthesis of 4 and 5 using
representative substrates. Most of the reactions proceeded
Having established the optimal conditions for the sequen- under the conditions described above to furnish the de-
tial coupling reaction, we explored the scope of the one- sired cross-coupling products 4 and 5 with retention of
pot synthesis of (Z)-1-aryl-3-(trimethylsilyl)alk-3-en-1- configuration at both double bonds in moderate to good
ynes 3. The results are summarized in Table 2. Typically yields. Phenylvinyl group as well as hex-1-enyl group
compounds 2 underwent smooth coupling with various participated in the sila-Sonogashira reaction, although the
Table 1 Optimization of Reaction Conditions for the (Z)-1-Aryl-3-(trimethylsilyl)alk-3-en-1-yne Synthesisa
PdCl2(PPh3)2, LiCl
CuI, Me3SiC
base/H2O
CBr
2B
I, DBU
n-Bu
n-Bu
Me3Si
_15 °C to r.t.
n-Bu
r.t.
Me3Si
SiMe3
1a
SiMe3
3aa
2a
Entry
Base
H2O (mL)
LiCl (mmol)
PdCl2(PPh3)2 (mmol) Yieldb (%) of 3aa
1
2
3
4
5
1 M NaOH
1 M NaOH
1 M NaOH
LiOH·H2O
LiOH·H2O
0
0
0.02
0.02
0.01
0.02
0.02
55
72
54
48
84
0
0.75
0.75
0
0
0.375
0.75
0
a Reagents and conditions: (1) 1a (1 mmol), Me3SiC≡CBr (0.67 mmol), CuI (0.1 mmol), base (0.75 mmol), –15 °C to r.t., overnight; (2) PhI
(0.5 mmol), PdCl2(PPh3)2, DBU (6 mmol), r.t., overnight.
b Yields were estimated by GC and based on the amount of PhI employed.
Synthesis 2008, No. 22, 3591–3600 © Thieme Stuttgart · New York

PAPER
One-Pot Synthesis of Internal Conjugated (Z)-Enynyltrimethylsilanes
3593
Table 2 Synthesis of (Z)-1-Aryl-3-(trimethylsilyl)alk-3-en-1-ynesa
PdCl2(PPh3)2
ArI, DBU
CuI, Me3SiC CBr
aq LiOH
2B
R1
R1
Me3Si
Ar
_15 °C to r.t.
r.t.
R1
Me3Si
1
SiMe3
SiMe3
2
3
2a R1 = n-Bu
2b R1 = t-Bu
2c R1 = cyclohex-1-enyl
2d R1 = Ph
Entry
R1
Ar
Product
3aa
3ba
3ca
Yieldb (%)
1
2
n-Bu
Ph
80
86
80
59
72
74
84
61
54
80
74
t-Bu
Ph
3
cyclohex-1-enyl
Ph
Ph
4
Ph
3da
3ab
3ac
5
n-Bu
4-Tol
6
n-Bu
4-MeOC6H4
2-Tol
7
n-Bu
3ad
3ae
8
n-Bu
4-ClC6H4
4-BrC6H4
2-thienyl
3-pyridyl
9
n-Bu
3af
10
11
n-Bu
3ag
3ah
n-Bu
a Reagents and conditions: (1) 1 (4 mmol), Me3SiC≡CBr (2.68 mmol), CuI (0.4 mmol), LiOH·H2O (3 mmol), H2O (3 mL), –15 °C to r.t., over-
night; (2) ArI (2 mmol), PdCl2(PPh3)2 (0.08 mmol), DBU (24 mmol), r.t., overnight.
b Isolated yields based on the amount of ArI employed.
yields of products incorporating the phenylvinyl group clo[5.4.0]undec-7-ene. Thus, the reaction with 4-tert-
were lower than those incorporating hex-1-enyl group butylcyclohex-1-enyl triflate (0.5 mmol) was conducted
(Table 3, entries 2, 4, and 6 vs entries 1, 3, 5, and 7). In the in the presence of dichlorobis(triphenylphosphine)palla-
cross-coupling reaction of 2a with (Z)-1-iodo-2-phe- dium and tetrabutylammonium fluoride (1 M solution in
nylethene, reducing the amount of 1,8-diazabicy- THF) at room temperature for four hours under argon.
clo[5.4.0]undec-7-ene gave a better result (Table 3, entry Table 4 shows the results of the reaction varying the
6). Unfortunately, the reaction of (Z)-2,4-bis(trimethylsi- amounts of dichlorobis(triphenylphosphine)palladium
lyl)-1-phenylbut-1-en-3-yne (2d) with (Z)-1-iodo-2-phe- and tetrabutylammonium fluoride. When increasing the
nylethene failed to provide the desired product. It is amount of tetrabutylammonium fluoride in the presence
noteworthy that this protocol can stereospecifically install of a fixed amount of dichlorobis(triphenylphosphine)pal-
the alk-1-enyl moiety in the distal sp carbon atom of 2.
ladium (0.02 mmol), the yield of product 6aa improved
considerably (Table 4, entries 1 and 2). Further increasing
the amount of tetrabutylammonium fluoride led to no im-
provement in the yield (Table 4, entry 3). On the other
hand, reducing the amount of dichlorobis(triphenylphos-
phine)palladium to half, the yield increased slightly
(Table 4, entry 4). Further reducing the amount of dichlo-
robis(triphenylphosphine)palladium caused a decrease in
the yield (Table 4, entry 5). Thus it is appropriate to em-
ploy 2 mol% of dichlorobis(triphenylphosphine)palladi-
um (0.01 mmol) and three equivalents of tetra-
butylammonium fluoride (1.5 mmol).
Continuing with the investigation, the scope of the reac-
tion with regard to alk-1-enyl triflate was examined. 4-
tert-Butylcyclohex-1-enyl triflate was chosen as a model
substrate, and the cross-coupling reaction with 2a, derived
from 1a, was carried out under the same conditions as
those described for the reaction with aryl iodide. After
stirring for four hours at room temperature, 4-tert-butyl-
cyclohex-1-enyl triflate was consumed, whereas the de-
sired product, 1-(4-tert-butylcyclohex-1-enyl)-3-(tri-
methylsilyl)oct-3-en-1-yne (6aa), was formed in only
moderate yield. Pale and co-workers have reported that
tetrabutylammonium fluoride promotes the sila-Sono- The one-pot synthesis of (Z)-1-(cycloalk-1-enyl)-3-(tri-
gashira reaction with alkenyl triflates.9b,c The report led us methylsilyl)alk-3-en-1-ynes 6 was conducted under the
to examine the cross-coupling reaction using tetrabutyl- optimized conditions, and the results are summarized in
ammonium fluoride in place of 1,8-diazabicy- Table 5. Representative compounds 2 underwent cou-
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3594
M. Hoshi et al.
PAPER
Table 3 Synthesis of (1Z,5E)-2-(Trimethylsilyl)alka-1,5-dien-3-ynes 4 and (1Z,5Z)-2-(Trimethylsilyl)alka-1,5-dien-3-ynes 5a
I
R2
2B
CBr
CuI, Me3SiC
aq LiOH
R1
PdCl2(PPh3)2, DBU
Me3Si
R1
Me3Si
_15 °C to r.t.
r.t.
1
SiMe3
2
R2
2a R1 = n-Bu
2d R1 = Ph
R2
R1
R1
or
SiMe3
SiMe3
4
5
Entry
Alk-1-enyl iodide
(E)-BuCH=CHI
(E)-PhCH=CHI
(E)-BuCH=CHI
(E)-PhCH=CHI
(Z)-BuCH=CHI
(Z)-PhCH=CHI
(Z)-BuCH=CHI
(Z)-PhCH=CHI
R1
R2
Product
4aa
Yieldb (%)
1
2
3
4
5
6
7
8
n-Bu
n-Bu
Ph
n-Bu
Ph
70
4ab
58
n-Bu
Ph
4da
60
Ph
4db
5aa
44
n-Bu
n-Bu
Ph
n-Bu
Ph
74
5ab
38 (44)c
72
n-Bu
Ph
5da
d
Ph
5db
–
a Reagents and conditions: 1 (4 mmol), Me3SiC≡CBr (2.68 mmol), CuI (0.4 mmol), LiOH·H2O (3 mmol), H2O (3 mL), –15 °C to r.t., overnight;
(2) R2CH=CHI (2 mmol), PdCl2(PPh3)2 (0.08 mmol), DBU (12 mmol), r.t., overnight, unless otherwise stated.
b Isolated yields based on the amount of R2CH=CHI employed.
c A reduced amount of DBU (8 mmol) was used.
d No 5db could be isolated due to a co-eluting impurity.
Table 4 Optimization of Reaction Conditions for the (Z)-1-(Cycloalk-1-enyl)-3-(trimethylsilyl)alk-3-en-1-yne Synthesisa
PdCl2(PPh3)2, 1 M TBAF
CBr
CuI, Me3SiC
aq LiOH
2B
t-Bu
OTf
n-Bu
n-Bu
Me3Si
t-Bu
_15 °C to r.t.
n-Bu
Me3Si
r.t.
1a
SiMe3
SiMe3
2a
6aa
Entry
PdCl2(PPh3)2 (mmol)
TBAF (mmol)
Yieldb (%) of 6aa
1
2
3
4
5
0.02
0.02
0.02
0.01
0.005
1.0
1.5
2.0
1.5
1.5
48
71
69
76
68
a Reagents and conditions: 1a (1 mmol), Me3SiC≡CBr (0.67 mmol), CuI (0.1 mmol), LiOH·H2O (0.75 mmol), H2O (0.75 mL), –15 °C to r.t.,
overnight; (2) 4-tert-butylcyclohex-1-enyl triflate (0.5 mmol), PdCl2(PPh3)2, 1 M TBAF, r.t., for 4 h.
b Yields were estimated by GC and based on the amount of 4-tert-butylcyclohex-1-enyl triflate employed.
pling with some different types of cycloalk-1-enyl triflate cloalkenyl triflate derived from a-tetralone underwent
to afford products 6 in moderate to good yields. Sterically smooth coupling with 2a (Table 5, entry 3), while the re-
hindered 6-methylcyclohex-1-enyl triflate reacted with 2a action with 2d gave a low yield of product 6dc (Table 5,
and 2d smoothly in analogy with 4-tert-butylcyclohex-1- entry 7). The cyclooct-1-enyl group took part in the sila-
enyl triflate (Table 5, entries 2 and 6). Conjugated cy-
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One-Pot Synthesis of Internal Conjugated (Z)-Enynyltrimethylsilanes
3595
Sonogashira reaction without any difficulties (Table 5, lyl)alk-3-en-1-ynes 2 serves as a useful precursor for con-
entries 4 and 8).
structing internal conjugated (Z)-enynyltrimethylsilanes.
Some features, such as simple operation, mild reaction
conditions, overall stereospecificity, and good functional
compatibility, make this strategy a useful and environ-
mentally benign process for the construction of various in-
ternal conjugated (Z)-enynyltrimethylsilanes.
To our knowledge, there is only one report on stereoselec-
tive synthesis of (Z)-1,3-enynyltrimethylsilanes via titani-
um-catalyzed hydromagnesiation of 1-(trimethylsilyl)alk-
1-yne followed by palladium-catalyzed cross-coupling
with 1-iodoalk-1-yne.15 The present protocol has the ad-
vantage of introducing a variety of unsaturated substitu-
ents into the distal sp carbon atom.
NMR spectra were recorded on a Jeol JNM-A-500 spectrometer
with CHCl3 (d = 7.26 and 77.0) or CH2Cl2 (d = 5.32 and 53.1) as in-
ternal standard. IR spectra were recorded on a Shimadzu FT-IR
8300 spectrophotometer, and only the strongest/structurally most
important absorption peaks are listed. MS were performed on a Jeol
JMS-SX102A spectrometer (EI, 70 eV). GC analyses were per-
formed with a Shimadzu GC-14B gas chromatograph equipped
with a glass column (5% FFAP on Uniport B, 1 m or 5% SE-30 on
Uniport B, 1 m), a flame ionization detector, and a Shimadzu C-
R8A digital integrator-recorder. TLC analyses were carried out us-
ing glass plates pre-coated aluminum oxide 60 F254 purchased from
Merck. Product purification was performed by column chromatog-
In summary, we have developed a one-pot procedure for
the synthesis of internal conjugated (Z)-enynyltrimethyl-
silanes such as (Z)-1-aryl-3-(trimethylsilyl)alk-3-en-1-
ynes 3, (1Z,5E)-2-(trimethylsilyl)alka-1,5-dien-3-ynes 4,
(1Z,5Z)-2-(trimethylsilyl)alka-1,5-dien-3-ynes 5, and (Z)-
1-(cycloalk-1-enyl)-3-(trimethylsilyl)alk-3-en-1-ynes
6
from easily available starting materials via a Suzuki-type
reaction/sila-Sonogashira reaction sequence. The present
method has demonstrated that (Z)-1,3-bis(trimethylsi-
Table 5 Synthesis of (Z)-1-(Cycloalk-1-enyl)-3-(trimethylsilyl)alk-3-en-1-ynes 6a
2B
CBr
PdCl2(PPh3)2,
1 M TBAF
CuI, Me3SiC
aq LiOH
OTf
R1
R1
Me3Si
R1
_15 °C to r.t.
Me3Si
r.t.
1
SiMe3
SiMe3
2
6
2a R1 = n-Bu
2d R1 = Ph
Entry
1
R1
Cycloalk-1-enyl triflate
Product
Yieldb (%)
70
Bu
Bu
6aa
6ab
t-Bu
OTf
Me
2
3
74
65
OTf
OTf
Bu
6ac
4
5
Bu
Ph
6ad
6da
62
70
OTf
t-Bu
OTf
Me
6
Ph
6db
75
OTf
OTf
7
8
Ph
Ph
6dc
6dd
40
70
OTf
a Reagents and conditions: (1) 1 (4 mmol), Me3SiC≡CBr (2.68 mmol), CuI (0.4 mmol), LiOH·H2O (3 mmol), H2O (3 mL), –15 °C to r.t., over-
night; (2) cycloalk-1-enyl triflate (2 mmol), PdCl2(PPh3)2 (0.04 mmol), 1 M TBAF(6 mmol), r.t., 4 h.
b Isolated yields based on the amount of cycloalk-1-enyl triflate employed.
Synthesis 2008, No. 22, 3591–3600 © Thieme Stuttgart · New York

3596
M. Hoshi et al.
PAPER
raphy using Merck aluminum oxide (aluminum oxide 60 active ba-
sic, 70–230 mm). All reactions were carried out under an argon
atmosphere. Unless otherwise noted, commercially available mate-
rials were used without any purification. Cyclohexene was used af-
ter distillation over CaH2 under argon. THF was distilled from Na
benzophenone ketyl under argon before use. 1-(Trimethylsilyl)hex-
1-ene and 1-phenyl-2-(trimethylsilyl)ethyne were purchased from
Aldrich and distilled under argon. (Trimethylsilyl)ethynyl bro-
mide,16 1-(trimethylsilyl)alk-1-yne [from 3,3-dimethylbut-1-yne
and (cyclohex-1-enyl)ethyne],17 (E)-alk-1-enyl iodide,18 (Z)-alk-1-
enyl iodide,19 cycloalk-1-enyl triflate20 and a solution of BH3 in
THF21 were prepared according to the literature procedures.
HRMS (EI): m/z [M]+ calcd for C17H24Si: 256.1647; found:
256.1686.
(Z)-5,5-Dimethyl-1-phenyl-3-(trimethylsilyl)hex-3-en-1-yne
(3ba)
Eluent: pentane.
IR (neat): 2956, 2925, 2860, 1560, 1489, 1363, 1249, 842, 760, 690
cm–1.
1H NMR (500 MHz, CDCl3): d = 0.29 (s, 9 H), 1.12 (s, 9 H), 6.93
(s, 1 H), 7.27–7.33 (m, 3 H), 7.41–7.45 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = 1.9 (3 CH3), 30.6 (3 CH3), 35.0
(C), 90.0 (≡C), 93.0 (≡C), 122.8 (=C), 124.4 (=C), 127.4 (=CH),
128.2 (2 =CH), 131.3 (2 =CH), 154.5 (=CH).
HRMS (EI): m/z [M]+ calcd for C17H24Si: 256.1647; found:
256.1667.
(Z)-1-Aryl-3-(trimethylsilyl)alk-3-en-1-ynes 3, (1Z,5E)-2-(Tri-
methylsilyl)alka-1,5-dien-3-ynes 4, and (1Z,5Z)-2-(Trimethyl-
silyl)alka-1,5-dien-3-ynes 5; General Procedure
To a 0.33 M soln of BH3 in THF (4 mmol) was added cyclohexene
(0.66 g, 8 mmol) dropwise at 0 °C under argon, and the mixture was
stirred for 2 h at this temperature to form a white suspension of di-
cyclohexylborane in THF. To this suspension was added 1-(tri-
methylsilyl)alk-1-yne (4 mmol) dropwise at 0 °C and the mixture
was stirred for 2 h at this temperature. The soln of dicyclohexyl[(Z)-
1-(trimethylsilyl)alk-1-enyl]borane 1, thus prepared, was cooled to
–15 °C, and CuI (0.076 g, 0.4 mmol) and LiOH·H2O (0.126 g, 3
mmol) were added under a flow of argon, followed by dropwise ad-
dition of Me3SiC≡CBr (0.474 g, 2.68 mmol) and H2O (3 mL). The
resulting mixture was allowed to warm gradually to r.t. and stirred
overnight. The mixture was then cooled to 0 °C, PdCl2(PPh3)2
(0.056 g, 0.08 mmol) was added to the cooled mixture under a flow
of argon followed by dropwise addition of DBU [3.65 g, 24 mmol
for the synthesis of 3, 1.83 g, 12 mmol for the synthesis of 4 and 5
except 5ab (1.22 g, 8 mmol)] and aryl or alk-1-enyl iodide (2
mmol), and the resultant mixture was stirred at r.t. overnight. The
mixture was treated by bubbling air through the soln with tube
pump at r.t. for 2 h to oxidize the residual organoboron compound.
The resulting mixture was extracted with pentane, washed with
H2O, dried (K2CO3), and filtered. The solvent was evaporated under
reduced pressure and the residue was purified by column chroma-
tography (aluminum oxide, basic) to provide product 3, 4 or 5.
(Z)-1-(Cyclohex-1-enyl)-4-phenyl-2-(trimethylsilyl)but-1-en-3-
yne (3ca)
Eluent: pentane.
IR (neat): 2933, 2858, 2831, 2185, 1596, 1490, 1442, 1434, 1245,
925, 842, 754, 690 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.30 (s, 9 H), 1.61–1.72 (m, 4 H),
2.04–2.18 (m, 4 H), 5.72–5.75 (m, 1 H), 7.08 (br s, 1 H), 7.28–7.36
(m, 3 H), 7.44–7.47 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = 0.4 (3 CH3), 21.8 (CH2), 22.4
(CH2), 25.4 (CH2), 28.1 (CH2), 91.1 (≡C), 93.7 (≡C), 122.7 (=C),
124.3 (=C), 126.8 (=CH), 127.4 (=CH), 128.1 (2 =CH), 131.2
(2 =CH), 137.3 (=C), 154.4 (=CH).
HRMS (EI): m/z [M]+ calcd for C19H24Si: 280.1647; found:
280.1630.
(Z)-1,4-Diphenyl-2-(trimethylsilyl)but-1-en-3-yne (3da)
Eluent: pentane–CH2Cl2 (9:1).
IR (neat): 3078, 3055, 3024, 2956, 2896, 1596, 1488, 1442, 1247,
866, 840, 752, 690 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.22 (s, 9 H), 7.32–7.42 (m, 8 H),
7.51–7.54 (m, 2 H), 7.85 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 0.1 (3 CH3), 92.4 (≡C), 93.6
(≡C), 124.1 (=C), 126.6 (=C), 127.7 (=CH), 127.8 (=CH), 127.9
(2 =CH), 128.2 (2 =CH), 128.4 (2 =CH), 131.3 (2 =CH), 138.7
(=C), 151.2 (=CH).
HRMS (EI): m/z [M]+ calcd for C19H20Si: 276.1334; found:
276.1364.
(Z)-1-(Cycloalk-1-enyl)-3-(trimethylsilyl)alk-3-en-1-ynes 6;
General Procedure
The cross-coupling reaction of dicyclohexyl[(Z)-1-(trimethylsi-
lyl)alk-1-enyl]borane (4 mmol) in THF (12 mL) with Me3SiC≡CBr
(0.474 g, 2.68 mmol) was carried out as described in the general
procedure for the synthesis of 3, 4, and 5. To the mixture containing
(Z)-1,3-bis(trimethylsilyl)alk-3-en-1-yne was added PdCl2(PPh3)2
(0.028 g, 0.04 mmol) under a flow of argon, followed by dropwise
addition of cycloalkenyl triflate (2 mmol) and 1 M TBAF (6 mL, 6
mmol) at 0 °C; the mixture was stirred at r.t. for 4 h. The workup
procedure was the same as described in the general procedure for
the synthesis of 3, 4, and 5, except for extracting with Et2O and
washing with brine.
(Z)-1-(4-Methylphenyl)-3-(trimethylsilyl)oct-3-en-1-yne (3ab)
Eluent: pentane.
IR (neat): 2956, 2925, 2871, 2858, 2187, 1577, 1508, 1456, 1247,
840, 815, 758 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.29 (s, 9 H), 0.93 (t, J = 7.0 Hz,
3 H), 1.34–1.46 (m, 4 H), 2.23–2.28 (m, 2 H), 2.34 (s, 3 H), 6.72 (t,
J = 7.8 Hz, 1 H), 7.08–7.12 (m, 2 H), 7.29–7.32 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 21.4
(CH3), 22.4 (CH2), 31.6 (CH2), 32.3 (CH2), 89.9 (≡C), 92.2 (≡C),
121.3 (=C), 122.9 (=C), 128.9 (2 =CH), 131.1 (2 =CH), 137.3 (=C),
154.3 (=CH).
(Z)-1-Phenyl-3-(trimethylsilyl)oct-3-en-1-yne (3aa)
Eluent: pentane.
IR (neat): 2956, 2927, 2871, 2858, 2187, 1577, 1488, 1249, 840,
754, 690 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.33 (s, 9 H), 0.97 (t, J = 7.0 Hz,
3 H), 1.37–1.50 (m, 4 H), 2.26–2.33 (m, 2 H), 6.78 (t, J = 7.7 Hz, 1
H), 7.26–7.36 (m, 3 H), 7.42–7.48 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 31.6 (CH2), 32.3 (CH2), 89.7 (≡C), 93.0 (≡C), 122.8 (=C),
124.4 (=C), 127.3 (=CH), 128.1 (2 =CH), 131.2 (2 =CH), 154.7
(=CH).
HRMS (EI): m/z [M]+ calcd for C18H26Si: 270.1804; found:
270.1790.
(Z)-1-(4-Methoxyphenyl)-3-(trimethylsilyl)oct-3-en-1-yne (3ac)
Eluent: pentane–CH2Cl2 (8:2).
Synthesis 2008, No. 22, 3591–3600 © Thieme Stuttgart · New York

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One-Pot Synthesis of Internal Conjugated (Z)-Enynyltrimethylsilanes
3597
IR (neat): 2956, 2929, 2871, 2856, 2835, 1606, 1508, 1463, 1440,
1290, 1247, 1170, 1031, 839, 806, 758 cm–1.
H), 6.98 (dd, J = 5.4, 3.4 Hz, 1 H), 7.14 (dd, J = 3.4, 1.0 Hz, 1 H),
7.22 (dd, J = 5.4, 1.0 Hz, 1 H).
1H NMR (500 MHz, CDCl3): d = 0.32 (s, 9 H), 0.96 (t, J = 7.0 Hz,
3 H), 1.37–1.49 (m, 4 H), 2.26–2.31 (m, 2 H), 3.83 (s, 3 H), 6.73 (t,
J = 7.8 Hz, 1 H), 6.84–6.89 (m, 2 H), 7.36–7.41 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 31.5 (CH2), 32.4 (CH2), 82.8 (≡C), 96.8 (≡C), 122.6 (=C),
124.7 (=C), 126.1 (=CH), 126.9 (=CH), 130.5 (=CH), 154.7 (=CH).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 31.6 (CH2), 32.3 (CH2), 55.1 (CH3), 89.6 (≡C), 91.5 (≡C),
113.8 (2 =CH), 116.6 (=C), 122.9 (=C), 132.5 (2 =CH), 153.9
(=CH), 158.9 (=C).
HRMS (EI): m/z [M]+ calcd for C15H22SSi: 262.1212; found:
262.1214.
(Z)-1-(3-Pyridyl)-3-(trimethylsilyl)oct-3-en-1-yne (3ah)
Eluent: pentane–Et2O (1:1).
HRMS (EI): m/z [M]+ calcd for C18H26OSi: 286.1753; found:
286.1747.
IR (neat): 2956, 2927, 2871, 2858, 2189, 1587, 1573, 1558, 1475,
1406, 1249, 1020, 840, 802, 758, 704 cm–1.
(Z)-1-(2-Methylphenyl)-3-(trimethylsilyl)oct-3-en-1-yne (3ad)
Eluent: pentane.
1H NMR (500 MHz, CDCl3): d = 0.32 (s, 9 H), 0.96 (t, J = 7.0 Hz,
3 H), 1.37–1.50 (m, 4 H), 2.27–2.33 (m, 2 H), 6.81 (t, J = 7.8 Hz, 1
H), 7.26 (ddd, J = 7.8, 4.9, 1.0 Hz, 1 H), 7.71 (dt, J = 7.8, 2.0 Hz, 1
H), 8.50 (dd, J = 4.9, 1.5 Hz, 1 H), 8.66 (d, J = 1.5 Hz, 1 H).
IR (neat): 3058, 3020, 2956, 2925, 2871, 2858, 2183, 1577, 1485,
1458, 1377, 1247, 840, 754, 715, 692 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.30 (s, 9 H), 0.94 (t, J = 7.0 Hz,
3 H), 1.34–1.47 (m, 4 H), 2.25–2.30 (m, 2 H), 2.45 (s, 3 H), 6.75 (t,
J = 7.8 Hz, 1 H), 7.10–7.20 (m, 3 H), 7.38–7.41 (m, 1 H).
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 13.9 (CH3), 20.9
(CH3), 22.4 (CH2), 31.6 (CH2), 32.3 (CH2), 88.3 (≡C), 96.9 (≡C),
123.0 (=C), 124.2 (=C), 125.3 (=CH), 127.3 (=CH), 129.2 (=CH),
131.8 (=CH), 139.4 (=C), 154.7 (=CH).
13C NMR (125 MHz, CDCl3): d = –0.1 (3 CH3), 13.9 (CH3), 22.3
(CH2), 31.4 (CH2), 32.4 (CH2), 86.0 (≡C), 96.5 (≡C), 121.6 (=C),
122.3 (=C), 122.9 (=CH), 138.1 (=CH), 147.3 (=CH), 151.6 (=CH),
156.1 (=CH).
HRMS (EI): m/z [M]+ calcd for C16H23NSi: 257.1600; found:
257.1590.
(5Z,9E)-6-(Trimethylsilyl)tetradeca-5,9-dien-7-yne (4aa)22
Eluent: pentane.
IR (neat): 2956, 2927, 2871, 2858, 1465, 1249, 952, 840, 758 cm–1.
HRMS (EI): m/z [M]+ calcd for C18H26Si: 270.1804; found:
270.1835.
(Z)-1-(4-Chlorophenyl)-3-(trimethylsilyl)oct-3-en-1-yne (3ae)
Eluent: pentane–CH2Cl2 (95:5).
1H NMR (500 MHz, CDCl3): d = 0.21 (s, 9 H), 0.87 (t, J = 7.0 Hz,
3 H), 0.88 (t, J = 7.0 Hz, 3 H), 1.26–1.40 (m, 8 H), 2.06–2.12 (m, 2
H), 2.16–2.22 (m, 2 H), 5.60 (d, J = 15.6 Hz, 1 H), 6.03 (dt,
J = 15.6, 7.3 Hz, 1 H), 6.58 (t, J = 7.8 Hz, 1 H).
IR (neat): 2956, 2927, 2871, 2860, 2188, 1488, 1249, 1091, 1014,
840, 827, 758, 694 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.32 (s, 9 H), 0.96 (t, J = 7.0 Hz,
3 H), 1.37–1.50 (m, 4 H), 2.26–2.33 (m, 2 H), 6.79 (t, J = 7.8 Hz, 1
H), 7.24–7.28 (m, 2 H), 7.31–7.35 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = –0.1 (3 CH3), 14.0 (CH3), 22.4
(CH2), 31.6 (CH2), 32.4 (CH2), 88.7 (≡C), 94.0 (≡C), 122.6 (=C),
123.0 (=C), 128.4 (2 =CH), 132.4 (2 =CH), 133.6 (=C), 155.2
(=CH).
13C NMR (125 MHz, CDCl3): d = –0.1 (3 CH3), 13.8 (CH3), 13.9
(CH3), 22.1 (CH2), 22.3 (CH2), 31.0 (CH2), 31.6 (CH2), 32.2 (CH2),
32.7 (CH2), 88.6 (≡C), 91.3 (≡C), 110.2 (=CH), 123.0 (=C), 142.9
(=CH), 153.8 (=CH).
HRMS (EI): m/z [M]+ calcd for C17H30Si: 262.2117; found:
262.2105.
(1E,5Z)-1-Phenyl-5-(trimethylsilyl)deca-1,5-dien-3-yne (4ab)
Eluent: pentane–CH2Cl2 (95:5).
HRMS (EI): m/z [M]+ calcd for C17H23ClSi: 290.1258; found:
290.1272.
IR (neat): 3060, 3026, 2956, 2925, 2871, 2856, 2167, 1596, 1569,
1492, 1465, 1448, 1247, 948, 840, 758, 746, 690 cm–1.
(Z)-1-(4-Bromophenyl)-3-(trimethylsilyl)oct-3-en-1-yne (3af)
Eluent: pentane–CH2Cl2 (95:5).
1H NMR (500 MHz, CDCl3): d = 0.30 (s, 9 H), 0.96 (t, J = 7.0 Hz,
3 H), 1.36–1.48 (m, 4 H), 2.25–2.30 (m, 2 H), 6.38 (d, J = 16.1 Hz,
1 H), 6.72 (t, J = 7.8 Hz, 1 H), 6.89 (d, J = 16.1 Hz, 1 H), 7.27–7.31
(m, 1 H), 7.33–7.37 (m, 2 H), 7.40–7.43 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 31.6 (CH2), 32.3 (CH2), 89.2 (≡C), 95.7 (≡C), 109.2 (=CH),
123.0 (=C), 126.0 (2 =CH), 128.1 (=CH), 128.6 (2 =CH), 136.7
(=C), 139.4 (=CH), 154.8 (=CH).
IR (neat): 2956, 2927, 2871, 2858, 2187, 1589, 1575, 1485, 1465,
1392, 1249, 1070, 1010, 840, 823, 758, 694 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.32 (s, 9 H), 0.96 (t, J = 7.0 Hz,
3 H), 1.37–1.50 (m, 4 H), 2.27–2.32 (m, 2 H), 6.78 (t, J = 7.8 Hz, 1
H), 7.28–7.31 (m, 2 H), 7.44–7.47 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 31.5 (CH2), 32.4 (CH2), 88.6 (≡C), 94.2 (≡C), 121.3 (=C),
122.6 (=C), 123.4 (=C), 131.3 (2 =CH), 132.6 (2 =CH), 155.3
(=CH).
HRMS (EI): m/z [M]+ calcd for C19H26Si: 282.1804; found:
282.1791.
HRMS (EI): m/z [M]+ calcd for C17H23BrSi: 334.0753; found:
334.0764.
(1Z,5E)-1-Phenyl-2-(trimethylsilyl)deca-1,5-dien-3-yne (4da)
Eluent: pentane–CH2Cl2 (95:5).
(Z)-1-(2-Thienyl)-3-(trimethylsilyl)oct-3-en-1-yne (3ag)
Eluent: pentane.
IR (neat): 2956, 2925, 2871, 2854, 1488, 1444, 1247, 952, 840, 752,
698 cm–1.
IR (neat): 2956, 2927, 2871, 2858, 2185, 1579, 1465, 1425, 1249,
1197, 840, 758, 694 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.31 (s, 9 H), 0.96 (t, J = 7.0 Hz,
3 H), 1.37–1.49 (m, 4 H), 2.27–2.32 (m, 2 H), 6.75 (t, J = 7.8 Hz, 1
1H NMR (500 MHz, CDCl3): d = 0.13 (s, 9 H), 0.96 (t, J = 7.3 Hz,
3 H), 1.34–1.48 (m, 4 H), 2.16–2.22 (m, 2 H), 5.76 (br d, J = 15.6
Hz, 1 H), 6.17 (dt, J = 15.6, 7.3 Hz, 1 H), 7.25–7.38 (m, 5 H), 7.69
(s, 1 H).
Synthesis 2008, No. 22, 3591–3600 © Thieme Stuttgart · New York

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M. Hoshi et al.
PAPER
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 13.8 (CH3), 22.1
(CH2), 30.9 (CH2), 32.8 (CH2), 91.4 (≡C), 92.0 (≡C), 110.1 (=CH),
127.0 (=C), 127.6 (=CH), 127.8 (2 =CH), 128.3 (2 =CH), 138.8
(=C), 144.0 (=CH), 150.5 (=CH).
HRMS (EI): m/z [M]+ calcd for C19H26Si: 282.1804; found:
282.1805.
HRMS (EI): m/z [M]+ calcd for C19H26Si: 282.1804; found:
282.1789.
(Z)-1-(4-tert-Butylcyclohex-1-enyl)-3-(trimethylsilyl)oct-3-en-1-
yne (6aa)22
Eluent: pentane.
IR (neat): 2956, 2871, 1465, 1365, 1249, 840, 759 cm–1.
(1Z,5E)-1,6-Diphenyl-2-(trimethylsilyl)hexa-1,5-dien-3-yne
(4db)
Eluent: pentane–CH2Cl2 (9:1).
IR (neat): 3024, 2954, 1490, 1446, 1247, 948, 840, 750, 690 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.21 (s, 9 H), 0.86 (s, 9 H), 0.89
(t, J = 7.0 Hz, 3 H), 1.17–1.29 (m, 2 H), 1.29–1.31 (m, 4 H), 1.78–
1.90 (m, 2 H), 2.08–2.25 (m, 5 H), 5.99–6.03 (m, 1 H), 6.58 (t,
J = 7.8 Hz, 1 H).
1H NMR (500 MHz, CDCl3): d = 0.19 (s, 9 H), 6.46 (d, J = 16.1 Hz,
1 H), 6.98 (d, J = 16.1 Hz, 1 H), 7.28–7.50 (m, 10 H), 7.77 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 91.9 (≡C), 96.2
(≡C), 108.9 (=CH), 126.1 (2 =CH), 126.9 (=C), 127.8 (=CH), 127.9
(2 =CH), 128.3 (=CH), 128.4 (2 =CH), 128.6 (2 =CH), 136.5 (=C),
138.7 (=C), 140.1 (=CH), 151.1 (=CH).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 23.8 (CH2), 27.1 (3 CH3), 27.4 (CH2), 31.0 (CH2), 31.6
(CH2), 32.1 (C), 32.2 (CH2), 43.2 (CH), 90.5 (≡C), 91.4 (≡C), 121.2
(=C), 123.0 (=C), 133.3 (=CH), 153.4 (=CH).
HRMS (EI): m/z [M]+ calcd for C21H36Si: 316.2586; found:
316.2620.
HRMS (EI): m/z [M]+ calcd for C21H22Si: 302.1491; found:
302.1479.
(Z)-1-(6-Methylcyclohex-1-enyl)-3-(trimethylsilyl)oct-3-en-1-
yne (6ab)22
Eluent: pentane.
IR (neat): 2954, 2923, 2854, 1456, 1377, 1247, 840, 758 cm–1.
(5Z,9Z)-6-(Trimethylsilyl)tetradeca-5,9-dien-7-yne (5aa)22
Eluent: pentane.
IR (neat): 2956, 2927, 2871, 2858, 1465, 1249, 840, 758 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.23 (s, 9 H), 0.90 (t, J = 7.0 Hz,
3 H), 1.14 (d, J = 7.3 Hz, 3 H), 1.28–1.41 (m, 5 H), 1.48–1.56 (m, 1
H), 1.62–1.70 (m, 1 H), 1.75–1.82 (m, 1 H), 2.05–2.10 (m, 2 H),
2.17–2.28 (m, 3 H), 6.02 (dt, J = 3.9, 1.9 Hz, 1 H), 6.60 (t, J = 7.8
Hz, 1 H).
13C NMR (125 MHz, CDCl3): d = 0 (3 CH3), 13.9 (CH3), 19.6
(CH2), 20.5 (CH3), 22.4 (CH2), 26.0 (CH2), 30.7 (CH2), 31.7 (CH2),
32.2 (CH2), 32.8 (CH), 90.7 (≡C), 91.1 (≡C), 123.0 (=C), 126.9
(=C), 133.4 (=CH), 153.6 (=CH).
1H NMR (500 MHz, CDCl3): d = 0.23 (s, 9 H), 0.90 (t, J = 7.3 Hz,
3 H), 0.91 (t, J = 7.3 Hz, 3 H), 1.30–1.43 (m, 8 H), 2.18–2.24 (m, 2
H), 2.28–2.34 (m, 2 H), 5.60 (d, J = 10.7 Hz, 1 H), 5.79 (dt,
J = 10.7, 7.3 Hz, 1 H), 6.62 (t, J = 7.8 Hz, 1 H).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 13.9
(CH3), 22.3 (CH2), 22.4 (CH2), 30.0 (CH2), 31.1 (CH2), 31.6 (CH2),
32.2 (CH2), 86.5 (≡C), 97.0 (≡C), 109.6 (=CH), 123.1 (=C), 142.1
(=CH), 154.2 (=CH).
HRMS (EI): m/z [M]+ calcd for C18H30Si: 274.2117; found:
274.2135.
HRMS (EI): m/z [M]+ calcd for C17H30Si: 262.2117; found:
262.2107.
(Z)-1-(3,4-Dihydro-1-naphthyl)-3-(trimethylsilyl)oct-3-en-1-
yne (6ac)
Eluent: pentane–CH2Cl2 (95:5).
(1Z,5Z)-1-Phenyl-5-(trimethylsilyl)deca-1,5-dien-3-yne (5ab)
Eluent: pentane–CH2Cl2 (95:5).
IR (neat): 2956, 2927, 2871, 2856, 2167, 1448, 1249, 840, 785, 758,
690 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.30 (s, 9 H), 0.97 (t, J = 7.0 Hz,
3 H), 1.36–1.49 (m, 4 H), 2.27–2.33 (m, 2 H), 5.91 (d, J = 11.7 Hz,
1 H), 6.58 (d, J = 11.7 Hz, 1 H), 6.75 (t, J = 7.8 Hz, 1 H), 7.28–7.33
(m, 1 H), 7.36–7.41 (m, 2 H), 7.90–7.93 (m, 2 H).
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 31.6 (CH2), 32.4 (CH2), 88.0 (≡C), 100.2 (≡C), 108.4 (=CH),
123.2 (=C), 127.9 (=CH), 128.1 (2 =CH), 128.6 (2 =CH), 136.3
(=CH), 136.8 (=C), 155.4 (=CH).
IR (neat): 2956, 2929, 2871, 2858, 2829, 1577, 1487, 1450, 1425,
1247, 840, 763, 734 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.33 (s, 9 H), 0.97 (t, J = 7.3 Hz,
3 H), 1.37–1.50 (m, 4 H), 2.28–2.33 (m, 2 H), 2.43 (dt, J = 8.0, 4.9
Hz, 2 H), 2.84 (t, J = 8.0 Hz, 2 H), 6.43 (t, J = 4.9 Hz, 1 H), 6.78 (t,
J = 7.8 Hz, 1 H), 7.14 (br d, J = 6.8 Hz, 1 H), 7.20 (dt, J = 7.3, 1.5
Hz, 1 H), 7.25–7.30 (m, 1 H), 7.63 (br d, J = 7.3 Hz, 1 H).
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 23.7 (CH2), 27.2 (CH2), 31.6 (CH2), 32.3 (CH2), 87.2 (≡C),
93.8 (≡C), 122.4 (=C), 122.8 (=C), 125.1 (=CH), 126.4 (=CH),
127.2 (=CH), 127.3 (=CH), 133.1 (=C), 133.9 (=CH), 135.1 (=C),
154.7 (=CH).
HRMS (EI): m/z [M]+ calcd for C19H26Si: 282.1804; found:
282.1795.
HRMS (EI): m/z [M]+ calcd for C21H28Si: 308.1960; found:
308.1938.
(1Z,5Z)-1-Phenyl-2-(trimethylsilyl)deca-1,5-dien-3-yne (5da)
Eluent: pentane–CH2Cl2 (95:5).
(Z)-1-(Cyclooct-1-enyl)-3-(trimethylsilyl)oct-3-en-1-yne (6ad)22
Eluent: pentane.
IR (neat): 3020, 2956, 2925, 2871, 2854, 1488, 1444, 1247, 840,
752, 698 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.14 (s, 9 H), 0.97 (t, J = 7.0 Hz,
3 H), 1.38–1.51 (m, 4 H), 2.38–2.43 (m, 2 H), 5.71 (br d, J = 10.7
Hz, 1 H), 5.92 (dt, J = 10.7, 7.3 Hz, 1 H), 7.26–7.37 (m, 5 H), 7.72
(s, 1 H).
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 13.9 (CH3), 22.3
(CH2), 30.1 (CH2), 31.1 (CH2), 89.2 (≡C), 97.5 (≡C), 109.5 (=CH),
127.1 (=C), 127.7 (=CH), 127.8 (2 =CH), 128.4 (2 =CH), 138.8
(=C), 142.9 (=CH), 150.7 (=CH).
IR (neat): 2954, 2925, 2852, 1575, 1465, 1448, 1247, 840, 758, 692
cm–1.
1H NMR (500 MHz, CDCl3): d = 0.22 (s, 9 H), 0.90 (t, J = 7.3 Hz,
3 H), 1.29–1.41 (m, 4 H), 1.45–1.55 (m, 6 H), 1.55–1.65 (m, 2 H),
2.13–2.23 (m, 4 H), 2.27–2.33 (m, 2 H), 6.00 (t, J = 8.3 Hz, 1 H),
6.58 (t, J = 7.8 Hz, 1 H).
13C NMR (125 MHz, CDCl3): d = –0.0 (3 CH3), 13.9 (CH3), 22.4
(CH2), 25.8 (CH2), 26.4 (CH2), 27.0 (CH2), 28.4 (CH2), 29.8 (CH2),
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One-Pot Synthesis of Internal Conjugated (Z)-Enynyltrimethylsilanes
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30.2 (CH2), 31.6 (CH2), 32.2 (CH2), 89.8 (≡C), 92.5 (≡C), 123.1
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 25.8 (CH2), 26.4
(CH2), 27.1 (CH2), 28.5 (CH2), 29.8 (CH2), 30.1 (CH2), 90.5 (≡C),
95.3 (≡C), 124.4 (=C), 127.1 (=C), 127.5 (=CH), 127.8 (2 =CH),
128.3 (2 =CH), 136.9 (=CH), 138.9 (=C), 150.0 (=CH).
(=C), 124.5 (=C), 136.0 (=CH), 153.3 (=CH).
HRMS (EI): m/z [M]+ calcd for C19H32Si: 288.2273; found:
288.2303.
HRMS (EI): m/z [M]+ calcd for C21H28Si: 308.1960; found:
(Z)-4-(4-tert-Butylcyclohex-1-enyl)-1-phenyl-2-(trimethyl-
silyl)but-1-en-3-yne (6da)
308.1935.
Eluent: pentane.
References
IR (neat): 2958, 2922, 2898, 2868, 2841, 1488, 1477, 1365, 1247,
916, 858, 840, 752, 698 cm–1.
(1) For example, see: (a) Fleming, I.; Dunogues, J.; Smithers, R.
Org. React. 1989, 37, 57. (b) Blumenkopf, T. A.; Overman,
L. E. Chem. Rev. 1986, 86, 857. (c) Babudri, F.;
Fiandanese, V.; Marchese, G.; Punzi, A. Synlett 1995, 817;
and references therein.
(2) For example, see: (a) Denmark, S. E.; Sweis, R. F. In Metal-
Catalyzed Cross-Coupling Reactions, Vol. 1; de Meijere,
A.; Diederich, F., Eds.; Wiley-VCH: Weinheim, 2004, 163.
(b) Denmark, S. E.; Tymonko, S. A. J. Am. Chem. Soc. 2005,
127, 8004. (c) Itami, K.; Yoshida, J. Synlett 2006, 157.
(3) Kusumoto, T.; Nishida, K.; Hiyama, T. Bull. Chem. Soc.
Jpn. 1990, 63, 1947.
1H NMR (500 MHz, CDCl3): d = 0.13 (s, 9 H), 0.92 (s, 9 H), 1.21–
1.37 (m, 2 H), 1.86–1.99 (m, 2 H), 2.17–2.36 (m, 3 H), 6.14–6.17
(m, 1 H), 7.25–7.37 (m, 5 H), 7.69 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 23.8 (CH2), 27.1
(3 CH3), 27.5 (CH2), 30.9 (CH2), 32.1 (C), 43.2 (CH), 91.1 (≡C),
94.2 (≡C), 121.1 (=C), 127.0 (=C), 127.6 (=CH), 127.8 (2 =CH),
128.3 (2 =CH), 134.3 (=CH), 138.9 (=C), 150.1 (=CH).
HRMS (EI): m/z [M]+ calcd for C23H32Si: 336.2273; found:
336.2279.
(4) Delas, C.; Urabe, H.; Sato, F. Chem. Commun. 2002, 272.
(5) Ogoshi, S.; Ueta, M.; Oka, M.; Kurosawa, H. Chem.
Commun. 2004, 2732.
(6) Hoshi, M.; Kawamura, N.; Shirakawa, K. Synthesis 2006,
1961.
(7) (a) Hatanaka, Y.; Hiyama, T. J. Org. Chem. 1988, 53, 918.
(b) Hatanaka, Y.; Matsui, K.; Hiyama, T. Tetrahedron Lett.
1989, 30, 2403.
(8) (a) Nishihara, Y.; Ikegashira, K.; Mori, A.; Hiyama, T.
Chem. Lett. 1997, 1233. (b) Nishihara, Y.; Ikegashira, K.;
Hirabayashi, K.; Ando, J.; Mori, A.; Hiyama, T. J. Org.
Chem. 2000, 65, 1780. (c) Nishihara, Y.; Ando, J.; Kato, T.;
Mori, A.; Hiyama, T. Macromolecules 2000, 33, 2779.
(d) Yang, C.; Nalan, S. P. Organometallics 2002, 21, 1020.
(e) Mio, M. J.; Kopel, L. C.; Braun, J. B.; Gadzikwa, T. L.;
Hull, K. L.; Brisbois, R. G.; Markworth, C. J.; Grieco, P. A.
Org. Lett. 2002, 4, 3199.
(Z)-4-(6-Methylcyclohex-1-enyl)-1-phenyl-2-(trimethyl-
silyl)but-1-en-3-yne (6db)
Eluent: pentane.
IR (neat): 3022, 2956, 2929, 2868, 2829, 1488, 1454, 1442, 1338,
1247, 862, 840, 752, 698 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.14 (s, 9 H), 1.24 (d, J = 6.8 Hz,
3 H), 1.38–1.45 (m, 1 H), 1.55–1.64 (m, 1 H), 1.69–1.77 (m, 1 H),
1.82–1.89 (m, 1 H), 2.12–2.18 (m, 2 H), 2.31–2.39 (m, 1 H), 6.15
(dt, J = 3.9, 1.9 Hz, 1 H), 7.26–7.37 (m, 5 H), 7.70 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 0.0 (3 CH3), 19.6 (CH2), 20.5
(CH3), 26.1 (CH2), 30.7 (CH2), 32.7 (CH), 91.8 (≡C), 93.6 (≡C),
126.9 (=C), 127.1 (=C), 127.5 (=CH), 127.8 (2 =CH), 128.3
(2 =CH), 134.2 (=CH), 138.9 (=C), 150.1 (=CH).
HRMS (EI): m/z [M]+ calcd for C20H26Si: 294.1804; found:
294.1799.
(9) (a) Mori, A.; Kondo, T.; Kato, Y.; Nishihara, Y. Chem. Lett.
2001, 286. (b) Bertus, P.; Halbes, U.; Pale, P. Eur. J. Org.
Chem. 2001, 4391. (c) Halbes, U.; Bertus, P.; Pale, P.
Tetrahedron Lett. 2001, 42, 8641. (d) Halbes, U.; Pale, P.
Tetrahedron Lett. 2002, 43, 2039.
(10) Compound 2a was formed in about 90% GC yield based on
Me3SiC≡CBr employed; see ref. 6.
(11) Addition of CuI was not necessary because CuI had already
been used for the cross-coupling reaction of 1a with
Me3SiC≡CBr.
(12) Hoshi, M.; Nakayabu, H.; Shirakawa, K. Synthesis 2005,
1991.
(13) (a) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457.
(b) Suzuki, A. In Metal-Catalyzed Cross-Coupling
Reactions; Diederich, F.; Stang, P. J., Eds.; Wiley-VCH:
Weinheim, 1998, 49. (c) Miyaura, N. In Metal-Catalyzed
Cross-Coupling Reactions, Vol. 1; de Meijere, A.;
Diederich, F., Eds.; Wiley-VCH: Weinheim, 2004, 41.
(14) Compound 2a was formed in 82% (0.375 mL of H2O) or
84% GC yield (0.75 mL of H2O), based on Me3SiC≡CBr
employed.
(15) Cai, M.; Hao, W.; Zhao, H.; Song, C. J. Chem. Res., Synop.
2003, 485.
(16) Hofmeister, H.; Annen, K.; Laurent, H.; Wiechert, R.
Angew. Chem., Int. Ed. Engl. 1984, 23, 727.
(Z)-4-(3,4-Dihydro-1-naphthyl)-1-phenyl-2-(trimethylsilyl)but-
1-en-3-yne (6dc)
Eluent: pentane–CH2Cl2 (95:5).
IR (neat): 3053, 2952, 2933, 2895, 2829, 1487, 1450, 1357, 1334,
1247, 993, 918, 840, 763, 752, 734, 698 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.21 (s, 9 H), 2.48 (dt, J = 8.0, 4.9
Hz, 2 H), 2.88 (t, J = 8.0 Hz, 2 H), 6.53 (t, J = 4.9, Hz, 1 H), 7.18
(br d, J = 7.3 Hz, 1 H), 7.24 (dt, J = 7.3, 1.5 Hz, 1 H), 7.28–7.42 (m,
6 H), 7.71 (br d, J = 7.3 Hz, 1 H), 7.86 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 0.1 (3 CH3), 23.7 (CH2), 27.2
(CH2), 90.0 (≡C), 94.4 (≡C), 122.4 (=C), 125.1 (=CH), 126.5
(=CH), 126.8 (=C), 127.3 (=CH), 127.5 (=CH), 127.7 (=CH), 127.9
(2 =CH), 128.4 (2 =CH), 132.9 (=C), 134.7 (=CH), 135.1 (=C),
138.7 (=C), 151.1 (=CH).
HRMS (EI): m/z [M]+ calcd for C23H24Si: 328.1647; found:
328.1629.
(Z)-4-(Cyclooct-1-enyl)-1-phenyl-2-(trimethylsilyl)but-1-en-3-
yne (6dd)
Eluent: pentane.
IR (neat): 2925, 2850, 1488, 1465, 1444, 1247, 840, 752, 696 cm–1.
1H NMR (500 MHz, CDCl3): d = 0.14 (s, 9 H), 1.52–1.64 (m, 6 H),
1.64–1.74 (m, 2 H), 2.21–2.28 (m, 2 H), 2.38–2.43 (m, 2 H), 6.15 (t,
J = 8.3 Hz, 1 H), 7.26–7.38 (m, 5 H), 7.70 (s, 1 H).
(17) Zweifel, G.; Backlund, S. J. J. Am. Chem. Soc. 1977, 99,
3184.
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M. Hoshi et al.
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(21) (a) Zweifel, G.; Brown, H. C. Org. React. 1963, 13, 1.
(18) (a) Zweifel, G.; Whitney, C. C. J. Am. Chem. Soc. 1967, 89,
2753. (b) Hoshi, M.; Shirakawa, K. Chem. Commun. 2002,
2146.
(b) Brown, H. C. Organic Syntheses via Boranes; Wiley-
Interscience: New York, 1975.
(19) Hoshi, M.; Arase, A. Synth. Commun. 1997, 27, 567.
(20) (a) McMurry, J. E.; Scott, W. J. Tetrahedron Lett. 1983, 24,
979. (b) Ritter, K. Synthesis 1993, 735.
(22) After column chromatography, the product in eluates should
be stored in the refrigerator to avoid decomposition.
Synthesis 2008, No. 22, 3591–3600 © Thieme Stuttgart · New York