Ruthenium-catalyzed hydrosilylation of terminal alkynes: Stereodivergent synthesis of (E)- and (Z)-alkenylsilanes

Article abstract of DOI:10.1016/S0022-328X(01)01319-5

Stereodivergent hydrosilylation of terminal alkynes (RC≡CH; R = Ph, p-tolyl, Cy, n-hexyl) with hydrosilanes (HSiMe₂Ar; Ar=Ph, 3,5-(CF₃)₂C₆H₃, 4-CF₃C₆H₄, 4-MeOC₆H₄) has been examined using ruthenium catalysts. (E)-selective reactions giving (E)-RCH=CHSiMe₂Ar proceed in over 99% selectivity in the presence of a catalytic amount of RuHCl(CO)(PPh₃)₃. On the other hand, (Z)-selective reactions are successfully conducted in 91-99% selectivity by using Ru(SiMe₂Ph)Cl(CO)(PPrⁱ₃)₂ as the catalyst. All reactions readily proceed at room temperature in high yields. (E)- and (Z)-styrylsilanes having a SiMe₂ [C₆H₃-3,5-(CF₃)₂] group serve as good cross-coupling reagents with p-iodotoluene in the presence of tetrabutylammonium fluoride and [Pd(η³-allyl) Cl]₂ catalyst.

Full text of DOI:10.1016/S0022-328X(01)01319-5

Journal of Organometallic Chemistry 645 (2002) 192–200
www.elsevier.com/locate/jorganchem
Ruthenium-catalyzed hydrosilylation of terminal alkynes:
stereodivergent synthesis of (E)- and (Z)-alkenylsilanes
Hiroyuki Katayama, Ken Taniguchi, Masayuki Kobayashi, Takashi Sagawa,
Tatsuya Minami, Fumiyuki Ozawa *
Department of Applied Chemistry, Graduate School of Engineering, Osaka City Uni6ersity, Sumiyoshi-ku, Osaka 558-8585, Japan
Received 15 August 2001; received in revised form 18 September 2001; accepted 23 September 2001
Abstract
Stereodivergent hydrosilylation of terminal alkynes (RCꢀCH; R=Ph, p-tolyl, Cy, n-hexyl) with hydrosilanes (HSiMe2Ar;
ArꢁPh, 3,5-(CF3)2C6H3, 4-CF3C6H4, 4-MeOC6H4) has been examined using ruthenium catalysts. (E)-selective reactions giving
(E)-RCHꢁCHSiMe2Ar proceed in over 99% selectivity in the presence of a catalytic amount of RuHCl(CO)(PPh3)3. On the other
hand, (Z)-selective reactions are successfully conducted in 91–99% selectivity by using Ru(SiMe2Ph)Cl(CO)(PPri3)2 as the catalyst.
All reactions readily proceed at room temperature in high yields. (E)- and (Z)-styrylsilanes having a SiMe2[C6H3ꢂ3,5-(CF3)2]
group serve as good cross-coupling reagents with p-iodotoluene in the presence of tetrabutylammonium fluoride and [Pd(h3-al-
lyl)Cl]2 catalyst. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: Hydrosilylation; Alkynes; Ruthenium catalysts; Stereodivergent synthesis; Alkenylsilanes
1. Introduction
Transition metal-catalyzed hydrosilylation of termi-
nal alkynes is one of the simplest and efficient ways of
synthesizing alkenylsilanes [1]. While the reaction gen-
erally adopts a syn-addition process to afford (E)-
alkenylsilanes, anti-addition giving (Z)-alkenylsilanes
has also been documented [2]. Considering great utility
of alkenylsilanes in organic synthesis [3], it is desirable
to establish the catalytic systems which enable to pre-
pare both stereoisomers independently. Such stereodi-
vergent hydrosilylation of terminal alkynes has been
documented with rhodium catalysts [4,5]. However,
since the mechanistic reasons for variation of stereose-
lectivity dependent on reaction conditions have not
been well-understood, exact control of the stereochem-
istry of catalytic hydrosilylation is still a difficult task in
most cases. We herein report that both (E)- and (Z)-
isomers of alkenylsilane can be prepared in high selec-
tivity by proper choice of ruthenium catalysts (Eq. (1)).
(1)
The present study has been conducted on the basis of
recent our mechanistic findings [6,7]. We have suc-
ceeded in identifying almost complete array of elemen-
tary processes that are responsible for ruthenium-
catalyzed hydrosilylation of 1-trimethylsilyl-1-buten-3-
yne [6]. The essence of the results can be illustrated as
shown in Scheme 1 using terminal alkyne (1) as a
substrate. The mechanism consists of two catalytic cy-
cles A and B, which are connected with each other by
processes (v) and (vi), respectively. Cycle A starting
from alkyne-insertion into a ruthenium hydride (4)
forms (E)-alkenylsilane (2), whereas cycle B involving a
silylruthenium intermediate (5) affords (Z)-alkenylsi-
lane (3). The latter cycle invokes essentially the same
* Corresponding author. Fax: +81-6-6052978.
E-mail address: ozawa@a-chem.eng.osaka-cu.ac.jp (F. Ozawa).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01319-5

H. Katayama et al. / Journal of Organometallic Chemistry 645 (2002) 192–200
193
Scheme 1. Mechanisms of (E)- and (Z)-selective hydrosilylation of terminal alkynes catalyzed by ruthenium complexes [6].
elementary processes as previously proposed for
rhodium- and iridium-catalyzed systems [8] and later
for ruthenium-catalyzed reactions [9,10]. Thus the reac-
tion of 5 with alkyne forms a formal trans-insertion
complex 7, and this has been shown to proceed via a
common cis-insertion process, followed by cis to trans
isomerization of the resulting b-silylalkenyl ligand (Eq.
(2)) [8,10]. Reflecting the geometry of alkenyl ligand in
2. Results and discussion
2.1. (E)-Selecti6e hydrosilylation catalyzed by
RuHCl(CO)(PPh3)3 (4a)
Of the elementary processes in cycle A, insertion of
terminal alkyne into 4 (process (i)) is known to proceed
rapidly at room temperature, giving 1-alkenyl complex
6, exclusively [12]. On the other hand, the subsequent
reaction of 6 with hydrosilane follows two courses [6,7].
When CꢂSi bond formation giving (E)-alkenylsilane 2
is operative (process (ii)), the resulting 4 resumes cycle
A. On the other hand, when CꢂH bond formation of
process (v) takes place, the catalytic cycle shifts from A
7, the hydrosilylation product
configuration.
3
has the (Z)-
(2)
Thus far most of the rhodium- and ruthenium-cata-
lyzed reactions have been discussed only on the basis of
the mechanism corresponding to cycle B, where the (E)-
and (Z)-alkenylsilanes are afforded by the reactions of
cis- and trans-b-silylalkenyl complexes (e.g. 10 and 7 in
Eq. (2)) with hydrosilane, respectively [8–10]. On the
other hand, Scheme 1 clearly shows the possibility of
(E)-selective reaction according to cycle A. Therefore,
we have considered that (E)- and (Z)-selective hydrosi-
lylation reactions may be accomplished by selective
operation of cycle A and B, respectively. Since the
ruthenium-catalyzed hydrosilylation of terminal alkynes
so far reported is entirely (Z)-selective [9–11], we first
examined if the (E)-selective cycle A is revolved
selectively.
Scheme 2. Two types of processes for the reaction of alkenylruthe-
nium 6 with hydrosilane [7].

194
H. Katayama et al. / Journal of Organometallic Chemistry 645 (2002) 192–200
Table 1
(E)-Selective hydrosilylation of terminal alkynes catalyzed by RuHCl(CO)(PPh3)3 (4a) a
Run
RCꢀCH (1)
HSiR3%
Time (h)
(E)-2/(Z)-3 ratio b
Yield (%) b (2+3)
1
2 c
3
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
p-TolCꢀCH
CyCꢀCH
n-HexCꢀCH
HSiMe2Ph
HSiMe2Ph
HSiMe2[C6H3ꢂ3,5-(CF3)2]
HSiMe2(C6H4ꢂ4-CF3)
HSiMe2(C6H4ꢂ4-OMe)
HSiFPh2
10
1
1
2
1
0.5
4
1
2
2
99/1
\99/1
\99/1
\99/1
99/1
99/1
95/5
\99/1
99/1
99/1
94
100
98
98
97
4
5c
6
97
96
7 c
8
HSi(OEt)3
HSiMe2[C6H3ꢂ3,5-(CF3)2]
HSiMe2[C6H3ꢂ3,5-(CF3)2]
HSiMe2Ph
100
94
9
10 c
80 d
a All reactions were run at room temperature in CH2Cl2. Unless otherwise noted, initial concentration of the components are as follows:
[4a]0=10 mM, [RCꢀCH]0=0.20 M, [HSiR%3]0=0.20 M.
b Determined by GLC using anisole as an internal standard. Yield is based on the amount of alkyne employed.
c The reaction was performed with a 5-fold excess amount of hydrosilane ([HSiR3% ]0=1.0 M) relative to alkyne.
d The regioisomer n-Hex(PhMe2Si)CꢁCH2 was also obtained in 14% yield.
3–6). There is a tendency that the more electron-with-
drawing substituent on silicon leads to the higher reac-
tivity and selectivity. HSiMe2[C6H3ꢂ3,5-(CF3)2] was
particularly efficient. Thus the reaction was completed
within 1 h in almost perfect selectivity, using an equi-
molar amount of the hydrosilane (run 3). Similarly,
p-tolylacetylene and cyclohexylacetylene were hydrosi-
lylated in over 99% (E)-selectivity (runs 8, 9). The
reaction of 1-octyne with HSiMe2Ph was also highly
stereoselective (run 10), though the regioisomer n-Hex-
(PhMe2Si)CꢁCH2 (14%) was formed as a by-product.
to B. Accordingly, selective operation of cycle A may
be achieved by course-control of the reaction of 6 with
hydrosilane.
We have recently found that PPh3-coordinated 6,
Ru(CHꢁCHR)Cl(CO)(PPh3)2 (R=Ph, But, CHꢁ
CHSiMe3) reacts with HSiMe2Ph mainly by process (ii)
[7]. It has been also confirmed by kinetic examinations
that process (ii) and the competing process (v) adopt
completely different mechanisms from each other
(Scheme 2). Thus, process (ii) proceeds via direct associ-
ation of 6 with hydrosilane without dissociation of
phosphine ligand (L). In contrast, process (v) involves
prior dissociation of L, which is followed by the se-
quence of oxidative addition of hydrosilane and reduc-
tive elimination of CꢂH coupling product 8. Therefore,
we chose RuHCl(CO)(PPh3)3 (4a) having three PPh3
ligands as the catalyst. We have anticipated that free
PPh3, which is released upon the alkyne-insertion into
4a (process (i)), may effectively suppress process (v) to
cause highly selective cycle A.
Table 1 lists the results. All reactions were examined
in CH2Cl2 at room temperature using 5 mol% of 4a.
The reaction of phenylacetylene with an equimolar
amount of HSiMe2Ph was completed in 10 h to give
(E)- and (Z)-PhCHꢁCHSiMe2Ph in 93 and 1% yield
(GLC), respectively (run 1). Also detected in the cata-
lytic solution were PhCHꢁCH2 (4%) and PhCꢀCSiMe2-
Ph (2%), which correspond to 8 and 9 in Scheme 1,
respectively. The reaction was significantly accelerated
by the use of HSiMe2Ph in excess to phenylacetylene
(run 2). Moreover, the by-production of styrene and
silylacetylene was effectively suppressed under this con-
dition. Consequently, (E)-PhCHꢁCHSiMe2Ph was ob-
tained in almost quantitative yield.
2.2. (Z)-Selecti6e hydrosilylation catalyzed by
silylruthenium complexes
We next examined (Z)-selective hydrosilylation ac-
cording to cycle B (Table 2). Since the key intermediate
in this cycle is silyl complex 5, Ru(SiMe2Ph)Cl(CO)-
(PPh3)2 (5a) was isolated and employed in the catalytic
hydrosilylation of phenylacetylene with HSiMe2Ph. The
reaction smoothly proceeded at room temperature to
give (Z)-PhCHꢁCHSiMe2Ph in 84% selectivity (run 1).
The selectivity rose to 91% in the presence of an excess
amount of phenylacetylene to HSiMe2Ph (run 2) [13],
while considerable amounts of PhCHꢁCH2 (6%) and
PhCꢀCSiMe2Ph (6%) were formed in addition to
styrylsilanes.
A further improvement in the product selectivity was
achieved by using Ru(SiMe2Ph)Cl(CO)(PPri3)2 (5b) in-
stead of 5a. This complex exhibited extremely high
catalytic activity. Thus the reaction of phenylacetylene
with HSiMe2Ph was completed within a few minutes at
room temperature to produce 98% purity of (Z)-
PhCHꢁCHSiMe2Ph (run 3). In this run, the amounts of
styrene and silylacetylene were negligible (each B1%).
Under similar conditions, (Z)-selective hydrosilyla-
tion could be successfully performed with a range of
(E)-Selective hydrosilylation of phenylacetylene was
also successful with various hydrosilanes, giving the
corresponding (E)-styrylsilanes in high selectivity (runs

H. Katayama et al. / Journal of Organometallic Chemistry 645 (2002) 192–200
195
hydrosilanes and terminal alkynes in high selectivity
(\91%) (runs 4–6 and 8–11). The only exception of
hydrosilanes tested was HSiFPh2, which afforded (Z)-
styrylsilane in 82% selectivity (run 7).
lacetylene [9]. We next examined the difference between
these hydride catalysts.
Table 3 lists the results of catalytic hydrosilylation of
phenylacetylene using 4b or RuHCl(CO)(PCy3)2 (4c) as
a catalyst precursor. All reactions were run at room
temperature. In agreement with the previous report [9],
4b afforded (Z)-styrylsilane in high selectivity (run 1),
while the catalytic activity was much lower than that of
the silyl complex 5b. The PCy3 complex 4c provided a
comparable result (run 2). The remaining part of
product was styrene in both systems. The (Z)-selective
reaction was also successful with HSiMe2[C6H3ꢂ3,5-
(CF3)2] and HSiMe2(C6H4ꢂ4-CF3) instead of HSiMe2Ph
The catalytic performance of 5b is clearly much
higher than the other ruthenium catalysts so far re-
ported [9,11]. The highly reactive nature of 5b was
further confirmed by stoichiometric reactions. Thus the
treatment of 5b with five molar amounts of pheny-
lacetylene in CDCl3 at room temperature instantly gave
a b-silylalkenyl complex Ru[C(Ph)((CHSiMe2Ph]Cl-
(CO)(PPri3)2 (7b). Addition of HSiMe2Ph to this solu-
tion led to rapid formation of PhCHꢁCHSiMe2Ph ((E)/
(Z)=6/94) in 87% yield.
(runs
3
and 4), whereas the reaction with
HSiMe2(C6H4ꢂ4-OMe) was less selective (run 5).
2.3. (Z)-Selecti6e hydrosilylation using
hydridoruthenium precursors
Similarly to 4a, complex 4b is known to undergo
rapid insertion of phenylacetylene at room temperature
[12c]. It has been also reported that the resulting
Ru(CHꢁCHPh)Cl(CO)(PPri3)2 (6b) reacts with HSiEt3
to give (E)-PhCHꢁCHSiEt3 and 4b [9]. These reactions
correspond to the elementary process (i) and (ii) of
cycle A, respectively. However, despite our repeated
trials using several kinds of hydrosilanes, the latter
reaction could not take place, at least under the present
We have described in Section 2.1 that the (E)-selec-
tive cycle A in Scheme 1 can be conducted in high
selectivity by using 4a coordinated with PPh3 as the
catalyst. On the other hand, it has been previously
reported that RuHCl(CO)(PPri3)2 (4b) having PPr3i lig-
ands causes (Z)-selective hydrosilylation of pheny-
Table 2
(Z)-selective hydrosilylation of terminal alkynes catalyzed by silylruthenium complexes a
b
Run
1 d
Catalyst
RCꢀCH (1)
HSiR3%
Time (h)
(E)-2/(Z)-3 ratio c
Yield (%) c (2+3)
5a
5a
5b
5b
5b
5b
5b
5b
5b
5b
5b
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
PhCꢀCH
p-TolCꢀCH
CyCꢀCH
n-HexCꢀCH
HSiMe2Ph
HSiMe2Ph
HSiMe2Ph
HSiMe2[C6H3ꢂ3,5-(CF3)2]
HSiMe2(C6H4ꢂ4-CF3)
HSiMe2(C6H4ꢂ4-OMe)
HSiFPh2
HSi(OEt)3
HSiMe2Ph
1
8
16/84
9/91
2/98
2/98
2/98
3/97
18/82
4/96
1/99
5/95
9/91
93
88
98
98
98
99
98
88
93
80
98
2
3
4
5
6
7
8
9
10
11
Rapid
Rapid
Rapid
Rapid
Rapid
3
Rapid
0.5
Rapid
HSiMe2Ph
HSiMe2Ph
a All reactions were run at room temperature in CH2Cl2. Unless otherwise noted, initial concentration of the components are as follows:
[catalyst]0=10 mM, [RCꢀCH]0=1.0 M, [HSiR%3]0=0.20 M.
b 5a: Ru(SiMe2Ph)Cl(CO)(PPh3)2; 5b: Ru(SiMe2Ph)Cl(CO)(PPr3i )2.
c Determined by GLC using anisole as an internal standard.
d Initial concentration: [catalyst]0=10 mM, [RCꢀCH]0=[HSiR%3]0=0.20 M.
Table 3
(Z)-Selective hydrosilylation of phenylacetylene catalyzed by hydridoruthenium complexes a
b
Run
Catalyst
HSiR3%
Time (h)
(E)-2/(Z)-3 ratio c
Yield (%) c (2+3)
1
2
3
4
5
4b
4c
4c
4c
4c
HSiMe2Ph
HSiMe2Ph
HSiMe2[C6H3ꢂ3,5-(CF3)2]
HSiMe2(C6H4ꢂ4-CF3)
HSiMe2(C6H4ꢂ4-OMe)
2
2
2
2
3
3/97
4/96
3/97
4/96
12/88
98
97
99
96
96
a All reactions were run at room temperature in CH2Cl2. Initial concentration: [catalyst]0=10 mM, [PhCꢀCH]0=0.20 M, [HSiR%3]0=0.20 M.
b 4b: RuHCl(CO)(PPr3i )2; 4c: RuHCl(CO)(PCy3)2.
c Determined by GLC using anisole as an internal standard.

196
H. Katayama et al. / Journal of Organometallic Chemistry 645 (2002) 192–200
Table 4
(3)
Palladium-catalyzed cross-coupling between styrylsilanes and p-iodo-
toluene a
The results are listed in Table 4. Although the
present hydrosilylation reactions preferably proceed
with aryl-substituted hydrosilanes, the alkenylsilanes
originally employed in the cross-coupling reactions are
those without aryl-substituents on silicon, so as to
avoid a side reaction giving aryl–aryl coupling prod-
ucts. Actually, the reaction of (E)-PhCHꢁCHSiFPh2
afforded 16% yield of 4-methylbiphenyl in addition to
desired (E)-4-methylstilbene ((E)-11) (run 1). On the
other hand, introduction of CF3 group(s) into the
phenyl group on silicon was found to effectively sup-
press the aryl–aryl coupling (runs 2–4). Especially, the
styrylsilane synthesized with HSiMe2[C6H3ꢂ3,5-(CF3)2]
gave only desired product ((E)- or (Z)-11) in high yield
with retention of the starting geometry (runs 3 and 4).
a All reactions were carried out using 2.5 mol% of [(h3-allyl)PdCl]2
in THF at room temperature for 1 h. Initial concentration: [p-iodo-
toluene]0=0.20 M, [styrylsilane]0=0.24 M, [TBAF]0=0.24 M.
b Isolated yield.
c Determined by 1H-NMR spectroscopy.
3. Conclusion
We have demonstrated in this paper that (E)- and
(Z)-selective hydrosilylation of terminal alkynes can be
precisely performed by following cycle A and B in
Scheme 1, respectively. Cycle A is operative in almost
perfect selectivity using RuHCl(CO)(PPh3)3 (4a) as the
catalyst, whereas cycle B proceeds very rapidly in the
presence of a catalytic amount of Ru(SiMe2Ph)Cl-
(CO)(PPri3)2 (5b). The (E)- and (Z)-styrylsilanes thus
prepared using HSiMe2[C6H3ꢂ3,5-(CF3)2] can be uti-
lized as good reagents for the palladium-catalyzed
cross-coupling with p-iodotoluene in the presence of
tetrabutylammonium fluoride. Further application of
these highly efficient hydrosilylation systems will be
reported in due course.
catalytic condition (i.e. at room temperature) [14]. For
example, treatment of 6b with HSiMe2Ph (20 molar) in
CD2Cl2 at room temperature afforded no trace of
styrylsilane as confirmed by 1H-NMR spectroscopy and
GC–MS, but resulted in gradual formation of a small
amount of styrene (B10%) over several days instead.
We have recently shown that the reaction of
Ru(CHꢁCHPh)Cl(CO)(PPh3)2 (6a) with hydrosilane
giving (E)-styrylsilane (process (ii)) proceeds via direct
association of hydrosilane with 6a (see Scheme 2) [7].
Reflecting this mechanistic feature, the reactivity is
highly sensitive to steric factors. For example,
HSiMe2Ph is about 17 times more reactive than
HSiMePh2, and HSiPh3 is much less reactive than these
two hydrosilanes. Therefore, it seems reasonable that
the extremely poor reactivity of 6b towards (E)-styrylsi-
lane formation (process (ii) in Scheme 1) is mainly due
to steric congestion around the ruthenium center, which
is protected by two bulky PPri3 ligands [15,16].
4. Experimental
4.1. General remarks
Clearly, 6b is nonproductive in the (E)-selective cycle
A, whereas 6a is sufficiently reactive in this cycle. Thus
the strikingly different property of 4a and 4b in the
catalytic hydrosilylation is attributed principally to the
different reactivity of these alkenyl species towards
CꢂSi bond formation (process (ii)).
All manipulations were performed under a nitrogen
atmosphere using conventional Schlenk techniques. Ni-
trogen gas was purified by passing through a column of
P2O5 (Merck, SICAPENT). NMR spectra were
recorded on a Varian Mercury 300 (1H-NMR, 300.11
MHz; 13C-NMR, 75.46 MHz; 31P-NMR, 121.49 MHz)
spectrometer. Chemical shifts are reported in l (ppm),
referenced to the 1H (of residual protons) and 13C
signals of deuterated solvents or to the 31P signal of
external 85% H3PO4. Mass spectra were measured with
a Shimadzu QP-5000 GC-mass spectrometer (EI, 70
eV). GLC analysis was performed on a Shimadzu GC-
14B instrument equipped with a FID detector and a
2.4. Application to cross-coupling reaction
Finally, (E)- and (Z)-styrylsilanes thus prepared were
subjected to the palladium-catalyzed cross-coupling re-
action with p-iodotoluene in the presence of tetrabuty-
lammonium fluoride (TBAF) (Eq. (3)) [17].

H. Katayama et al. / Journal of Organometallic Chemistry 645 (2002) 192–200
197
capillary column CBP-1 (25 m×0.25 mm). Analytical
TLC was carried out on Merck TLC aluminum sheets
precoated with silica gel 60 F254. Flash column chro-
matography was performed using Merck silica gel 60
(230–400 mesh).
CH2Cl2 was dried over CaH2. THF was dried over
sodium benzophenone ketyl. These solvents were dis-
tilled and stored over activated molecular sieves
(MS4A) under a nitrogen atmosphere. Liquid alkynes
and hydrosilanes were degassed by freeze–pump–thaw
cycles prior to use. RuHCl(CO)(PPh3)3 (4a) [18], RuH-
Cl(CO)(PPri3)2 (4b) [19], RuHCl(CO)(PCy3)2 (4c) [20],
Ru(SiMe2Ph)Cl(CO)(PPh3)2 (5a) [6], and RuCl2(CO)-
(PPri3)2 [21] were synthesized according to the litera-
tures. All other chemicals were obtained from commer-
cial sources and used without further purification.
orange residue was purified by flash column chro-
matography (SiO2, hexane) to give a colorless oil, which
was analytically pure (68 mg, 91% yield).
The (Z)-selective reaction (run 4 in Table 2) was
similarly conducted using Ru(SiMe2Ph)Cl(CO)(PPri3)2
(5b) in place of 4a. (Z)-PhCHꢁCHSiMe2[C6H3ꢂ3,5-
(CF3)2] was formed in 96% yield (GLC; 87% isolated),
along with (E)-isomer (2%), styrene (B1%), and
PhCꢀCSiMe2[C6H3ꢂ3,5-(CF3)2] (B1%).
Identification data of alkenylsilanes prepared in this
study are as follows.
4.3.1. (E)-PhCHꢁCHSiMe2Ph
1H-NMR (CDCl3): l 7.59–7.21 (m, 10H, Ph), 6.94
(d, J=19.0 Hz, 1H, PhCHꢁ), 6.59 (d, J=19.0 Hz, 1H,
ꢁCHSi), 0.44 (s, 6H, SiMe2). 13C{1H}-NMR (CDCl3): l
145.2, 138.5, 138.1, 133.9, 129.0, 128.5, 128.1, 127.8,
127.1, 126.5, −2.5. MS, m/z (relative intensity, %):
238[M+, 25], 223 (45), 146 (16), 145 (100), 135 (10), 121
(35), 105 (20), 59 (12), 53 (16), 51 (10), 43 (52). Anal.
Calc. for C16H18Si: C, 80.61; H, 7.61. Found: C, 80.73;
H, 7.39%.
4.2. Preparation of Ru(SiMe2Ph)Cl(CO)(PPri3)2 (5b)
To a solution of RuCl2(CO)(PPri3)2 (100 mg, 0.192
mmol) in THF (3.2 ml) was added dropwise a 1.0 M
solution of Me2PhSiLi in THF [22] (0.19 ml, 0.19
mmol) at 0 °C. The resulting orange suspension was
concentrated to dryness by pumping to give an orange
oily material, which was extracted repeatedly with pen-
tane (5×2 ml). The combined extracts were concen-
trated to ca. 2 ml and allowed to stand at −70 °C
overnight, giving an orange crystalline solid, which was
collected by filtration, washed with cold pentane, and
4.3.2. (E)-PhCHꢁCHSiMe2[C6H3ꢂ3,5-(CF3)2]
1H-NMR (CDCl3): l 7.95 (br, 2H, Ar), 7.86 (br, 1H,
Ar), 7.48–7.45 (m, 2H, Ar), 7.39–7.27 (m, 3H, Ar),
6.99 (d, J=19.2 Hz, PhCHꢁ), 6.52 (d, J=19.2 Hz,
ꢁCHSi), 0.51 (s, 6H, SiMe2). 13C{1H}-NMR (CDCl3): l
146.9, 142.4, 137.6, 133.6, 130.8 (q, JFC=33 Hz), 128.7,
128.7, 126.6, 124.4, 123.6 (q, JFC=273 Hz), 122.9
(septet, JFC=3 Hz), −2.8. MS, m/z (relative intensity,
%): 374 [M+, 10], 279 (13), 278 (77), 277 (14), 257 (23),
227 (12), 209 (24), 195 (16), 145 (100), 81 (17), 77 (82),
59 (17), 51 (18), 47 (15), 43 (28). Anal. Calc. for
C18H16F6Si: C, 57.75; H, 4.31. Found: C, 57.83; H,
4.28%.
1
dried under vacuum (50 mg, 43%). H-NMR (toluene-
d8): l 7.90–7.87 (m, 2H, Ph), 7.21–7.08 (m, 3H, Ph),
2.57–2.42 (m, 6H, PCH), 1.21 (virtual triplet of dou-
blet, J=7.0 and 5.7 Hz, 18H, PCHCH3), 1.12 (virtual
triplet of doublet, J=7.0 and 5.7 Hz, 18H, PCHCH3),
0.95 (s, 6H, SiMe2). 13C{1H}-NMR (toluene-d8): l
2
201.6 (t, JPC=13 Hz, CO), 149.3, 137.5, 134.9, 127.4,
24.5 (virtual triplet, J=9 Hz, PCHCH3), 20.7 (s,
PCHCH3), 10.3 (s, SiMe2). 31P{1H}-NMR (toluene-d8):
l 38.4 (s). Anal. Calc. for C27H53ClOP2RuSi: C, 52.28;
H, 8.61. Found: C, 52.07; H, 8.58%.
4.3.3. (E)-PhCHꢁCHSiMe2(C6H4ꢂ4-CF3)
1H-NMR (CDCl3): l 7.70–7.59 (m, 4H, Ar), 7.47–
7.26 (m, 5H, Ar), 6.96 (d, J=19.2 Hz, 1H, PhCHꢁ),
6.55 (d, J=19.2 Hz, 1H, ꢁCHSi), 0.46 (s, 6H, SiMe2).
13C{1H}-NMR (CDCl3): l 146.0, 143.7, 137.8, 134.2,
131.0 (q, JFC=32 Hz), 128.6, 128.4, 126.5, 125.8, 124.2
(q, JFC=272 Hz), 124.3 (q, JFC=4 Hz), −2.7. MS,
m/z (relative intensity, %): 306 [M+, 30], 292 (11), 291
(47), 229 (30), 213 (25), 210 (22), 209 (14), 189 (39), 151
(12), 146 (19), 145 (100), 127 (39), 121 (11), 77 (34), 63
(13), 59 (17), 53 (11), 51 (18), 47 (14), 43 (35). Anal.
Calc. for C17H17F3Si: C, 66.64; H, 5.59. Found: C,
66.66; H, 5.65%.
4.3. Catalytic hydrosilylation
A typical procedure for (E)-selective reaction (run 3
in Table 1) is as follows. To a Schlenk tube containing
RuHCl(CO)(PPh3)3 (4a) (9.4 mg, 9.9 mmol) was added
a
solution of PhCꢀCH (20.3 mg, 0.199 mmol),
HSiMe2[C6H3ꢂ3,5-(CF3)2] (54.4 mg, 0.200 mmol), and
anisole (7.6 mg, 0.070 mmol; internal standard for GLC
analysis) in CH2Cl2 (1.0 ml) under a nitrogen atmo-
sphere. The mixture was stirred at room temperature
(r.t.) for 1 h. GLC analysis revealed the formation of
(E)-PhCHꢁCHSiMe2[C6H3ꢂ3,5-(CF3)2] in 98% yield,
along with small amounts of (Z)-isomer (B1%), sty-
rene (2%), and PhCꢀCSiMe2[C6H3ꢂ3,5-(CF3)2] (B1%).
The solvent was removed by pumping, and the resulting
4.3.4. (E)-PhCHꢁCHSiMe2(C6H4ꢂ4-OMe)
1H-NMR (CDCl3): l 7.52–7.42 (m, 4H, Ar), 7.36–
7.23 (m, 3H, Ar), 6.94–6.91 (m, 2H, Ar), 6.92 (d,
J=19.1 Hz, 1H, PhCHꢁ), 6.58 (d, J=19.1 Hz,
ꢁCHSi), 3.82 (s, 3H, OMe), 0.41 (s, 6H, SiMe2).

198
H. Katayama et al. / Journal of Organometallic Chemistry 645 (2002) 192–200
13C{1H}-NMR (CDCl3): l 160.4, 145.0, 138.2, 135.4,
129.3, 128.5, 128.1, 127.5, 126.5, 113.6, 55.0, −2.3.
MS, m/z (relative intensity, %): 268 [M+, 53], 254 (18),
253 (78), 175 (34), 165 (14), 152 (11), 146 (20), 145
(100), 135 (15), 121 (15), 119 (11), 105 (12), 59 (37), 53
(11), 43 (41). Anal. Calc. for C17H20OSi: C, 76.07; H,
7.51. Found: C, 75.86, H, 7.36%.
380 [M+, 4], 271 (100), 257 (20), 108 (76), 93 (14), 79
(28), 77 (18), 67 (20), 55 (18), 41 (35). Anal. Calc. for
C18H22F6Si: C, 56.83; H, 5.83. Found: C, 56.91; H,
5.76%.
4.3.9. (E)-n-C6H13CHꢁCHSiMe2Ph
1H-NMR (CDCl3): l 7.56–7.47 (m, 2H, Ph), 7.38–
7.31 (m, 3H, Ph), 6.12 (dt, J=18.5 and 6.3 Hz, 1H,
CHꢁ), 5.75 (dt, J=18.5 and 1.5 Hz, 1H, ꢁCHSi), 2.14
(dt, J=6.3 and 1.5 Hz, 2H, CH2), 1.34–1.15 (m, 8H,
CH2), 0.88 (t, J=7.0 Hz, 3H, Me), 0.31 (s, 6H, SiMe2).
MS, m/z (relative intensity, %): 246 [M+, 3], 231 (18),
136 (19), 135 (100), 121 (60), 162 (15), 161 (17), 107
(11), 105 (15), 59 (24). Anal. Calc. for C16H26Si: C,
77.97; H, 10.63. Found: C, 77.92; H, 10.67%.
4.3.5. (E)-PhCHꢁCHSiFPh2
1H-NMR (CDCl3): l 7.74–7.68 (m, 4H, Ph), 7.54–
7.30 (m, 11H, Ph), 7.18 (d, J=19.2 Hz, 1H, PhCHꢁ),
3
6.74 (dd, J=19.2 Hz, JFH=3.5 Hz, ꢁCHSi). 13C{1H}-
NMR (CDCl3): l 150.4 (d, JFC=4 Hz), 137.2 (s), 134.7
(d, JFC=1 Hz), 132.7 (d, JFC=17 Hz), 130.8, 129.1,
128.6, 128.1, 127.0, 120.3 (d, JFC=17 Hz). MS, m/z
(relative intensity, %): 304 [M+, 9], 226 (38), 201 (12),
199 (11), 181 (17), 180 (80), 179 (38), 178 (20), 165 (14),
149 (25), 125 (10), 77 (12), 51 (22), 47 (100). Anal. Calc.
for C20H17FSi: C, 78.91; H, 5.63. Found: C, 80.44; H,
5.47%.
4.3.10. (Z)-PhCHꢁCHSiMe2Ph
1H-NMR (CDCl3): l 7.56–7.53 (m, 2H, Ph), 7.49 (d,
J=15.2 Hz, 1H, PhCHꢁ), 7.36–7.32 (m, 3H, Ph), 7.21
(br, 5H, Ph), 6.00 (d, J=15.2 Hz, 1H, ꢁCHSi), 0.26 (s,
6H, SiMe2). 13C{1H}-NMR (CDCl3): l 148.0, 139.6,
139.6, 133.7, 130.2, 128.8, 128.2, 127.8, 127.4, −1.1.
MS, m/z (relative intensity, %): 238 [M+, 34], 224 (15),
223 (68), 146 (24), 145 (100), 135 (16), 121 (43), 119
(13), 105 (30), 59 (16), 53 (23), 51 (13), 43 (57). Anal.
Calc. for C16H18Si: C, 80.61; H, 7.61. Found: C, 80.63;
H, 7.47%.
4.3.6. (E)-PhCHꢁCHSi(OEt)3
1H-NMR (CDCl3): l 7.50–7.26 (m, 5H, Ph), 7.22 (d,
J=19.2 Hz, 1H, PhCHꢁ), 6.18 (d, J=19.2 Hz, 1H,
ꢁCHSi), 3.89 (q, J=7.0 Hz, 6H, OCH2CH3), 1.27 (t,
J=7.0 Hz, 9H, OCH2CH3). 13C{1H}-NMR (CDCl3): l
149.1, 137.6, 128.7, 128.5, 126.8, 117.6, 58.6, 18.3. MS,
m/z (relative intensity, %): 266 [M+, 6], 251 (40), 223
(17), 222 (73), 221 (17), 193 (41), 176 (63), 149 (82), 147
(92), 131 (45), 103 (47), 79 (56), 77 (28), 63 (68), 45
(100). Anal. Calc. for C14H22O3Si: C, 63.12; H, 8.32.
Found: C, 62.99; H, 8.18%.
4.3.11. (Z)-PhCHꢁCHSiMe2[C6H3ꢂ3,5-(CF3)2]
1H-NMR (CDCl3): l 7.81 (br, 2H, Ar), 7.76 (br, 1H,
Ar), 7.58 (d, J=15.0 Hz, PhCHꢁ), 7.18–7.13 (m, 3H,
Ar), 7.10–7.05 (m, 2H, Ar), 5.95 (d, J=15.0 Hz,
ꢁCHSi), 0.36 (s, 6H, SiMe2). 13C{1H}-NMR (CDCl3): l
149.9, 142.9, 139.2, 133.4, 130.5 (q, JFC=33 Hz), 128.2,
127.9, 127.9, 127.8, 123.6 (q, JFC=273 Hz), 122.5
(septet, JFC=4 Hz), −1.2. MS, m/z (relative intensity,
%): 374 [M+, 5], 279 (12), 278 (70), 277 (13), 257 (20),
227 (13), 209 (24), 195 (17), 145 (100), 81 (19), 77 (85),
59 (19), 51 (23), 47 (17), 43 (32). Anal. Calc. for
C18H16F6Si: C, 57.75; H, 4.31. Found: C, 57.90; H,
4.23%.
4.3.7. (E)-p-CH3C6H4CHꢁCHSiMe2[C6H3ꢂ3,5-(CF3)2]
1H-NMR (CDCl3): l 7.95 (br, 2H, Ar), 7.86 (br, 1H,
Ar), 7.36 (d, J=8.1 Hz, 2H, Ar), 7.16 (d, J=8.1 Hz,
2H, Ar), 6.96 (d, J=19.2 Hz, 1H, ArCHꢁ), 6.45 (d,
J=19.2 Hz, 1H, ꢁCHSi), 2.36 (s, 3H, Me), 0.49 (s, 6H,
SiMe2). 13C{1H}-NMR (CDCl3): l 146.8, 142.6, 138.7,
134.9, 133.6, 130.7 (q, JFC=33 Hz), 129.3, 126.6, 123.6
3
(q, JFC=273 Hz), 123.0, 122.8 (septet, JFC=4 Hz),
21.3, −2.8. MS, m/z (relative intensity, %): 388 [M+,
18], 292 (52), 277 (28), 257 (21), 241 (14), 195 (13), 159
(100), 115 (13), 77 (67), 43 (22). Anal. Calc. for
C19H18F6Si: C, 58.75; H, 4.67. Found: C, 58.73; H,
4.72%.
4.3.12. (Z)-PhCHꢁCHSiMe2(C6H4ꢂ4-CF3)
1H-NMR (CDCl3): l 7.63–7.51 (m, 4H, Ar), 7.53 (d,
J=15.0 Hz, 1H, PhCHꢁ), 7.26–7.16 (m, 5H, Ar), 5.97
(d, J=15.0 Hz, 1H, ꢁCHSi), 0.29 (s, 6H, SiMe2).
13C{1H}-NMR (CDCl3): l 148.9, 144.6, 139.4, 133.9,
130.7 (q, JFC=32 Hz), 129.0, 128.1, 127.9, 127.7, 124.3
(q, JFC=3 Hz), 124.2 (q, JFC=272 Hz), −1.2. MS,
m/z (relative intensity, %): 306 [M+, 23], 291 (42), 229
(28), 213 (23), 210 (22), 209 (13), 189 (33), 151 (12), 146
(19), 145 (100), 127 (42), 121 (11), 81 (10), 77 (35), 63
(14), 59 (17), 53 (12), 51 (21), 47 (15), 43 (37). Anal.
Calc. for C17H17F3Si: C, 66.64; H, 5.59. Found: C,
66.68; H, 5.69%.
4.3.8. (E)-cyclo-C6H11CHꢁCHSiMe2[C6H3ꢂ3,5-(CF3)2]
1H-NMR (CDCl3): l 7.90 (br s, 2H, Ar), 7.83 (s, br,
1H, Ar), 6.13 (dd, J=18.9 and 6.0 Hz, 1H, CyCHꢁ),
5.67 (dd, J=18.9 and 1.5 Hz, 1H, ꢁCHSi), 2.12–1.98
(m, 1H, Cy), 1.80–1.60 (m, 5H, Cy), 1.36–1.02 (m, 5H,
Cy), 0.37 (s, 6H, SiMe2). 13C{1H}-NMR (CDCl3): l
156.8, 143.3, 133.6, 130.5 (q, JFC=33 Hz), 123.7 (q,
3
J
FC=273 Hz), 122.6 (septet, JFC=4 Hz), 121.9, 44.1,
32.2, 26.1, 25.9, −2.7. MS, m/z (relative intensity, %):

H. Katayama et al. / Journal of Organometallic Chemistry 645 (2002) 192–200
199
4.3.13. (Z)-PhCHꢁCHSiMe2(C6H4ꢂ4-OMe)
(relative intensity, %): 246 [M+, 3], 231 (29), 135 (59),
121 (100), 162 (27), 161 (33), 147 (14), 145 (20), 105
(19), 59 (48). Anal. Calc. for C16H26Si: C, 77.97; H,
10.63. Found: C, 77.84; H, 10.32%.
1H-NMR (CDCl3): l 7.50–7.44 (m, 3H, Ar), 7.47 (d,
J=15.2 Hz, 1H, PhCHꢁ), 7.33–7.18 (m, 4H, Ar),
6.98–6.87 (m, 2H, Ar), 5.99 (d, J=15.2 Hz, ꢁCHSi),
3.81 (s, 3H, OMe), 0.24 (s, 6H, SiMe2). 13C{1H}-NMR
(CDCl3): l 160.2, 147.8, 139.6, 135.1, 130.5, 130.4,
128.3, 127.8, 127.4, 113.6, 55.0, −0.9. MS, m/z (relative
intensity, %): 268 [M+, 32], 254 (11), 253 (48), 175 (21),
165 (11), 151 (32), 146 (16), 145 (100), 135 (10), 105 (9),
59 (26), 43 (29). Anal. Calc. for C17H20OSi: C, 76.07; H,
7.51. Found: C, 74.83; H, 7.50%.
4.4. Reaction of Ru(SiMe2Ph)Cl(CO)(PPri3)2 (5b) with
phenylacetylene and HSiMe2Ph
An NMR sample tube was charged with 5b (8.6 mg,
0.014 mmol) and capped with a rubber septum. The
system was replaced with nitrogen gas. CDCl3 (0.70 ml)
and PhCꢀCH (7.1 mg, 0.070 mmol) were added at r.t.
NMR analysis after several minutes revealed complete
conversion of 5b into Ru[C(Ph)(CHSiMe2Ph]-
4.3.14. (Z)-PhCHꢁCHSiFPh2
1H-NMR (CDCl3): l 7.63–7.57 (m, 4H, Ph), 7.42–
7.30 (m, 9H, Ph and PhCHꢁ), 7.20–7.12 (m, 3H, Ph),
6.10 (dd, J=15.0 Hz, 3JFH=8.7 Hz, 1H, ꢁCHSi).
13C{1H}-NMR (CDCl3): l 152.6 (d, JFC=2 Hz), 138.1,
134.4 (d, JFC=2 Hz), 133.4 (d, JFC=18 Hz), 130.5,
128.4, 128.3, 128.0, 122.7 (d, JFC=17 Hz). MS, m/z
(relative intensity, %): 304 [M+, 20], 226 (38), 201 (20),
180 (100), 179 (64), 165 (26), 149 (43), 125 (15), 77 (13),
47 (79). Anal. Calc. for C20H17FSi: C, 78.91; H, 5.63.
Found: C, 79.88; H, 5.51%.
1
Cl(CO)(PPri3)2 (7b). H-NMR (CDCl3, 20 °C): l 7.49–
4
7.02 (m, 10H, Ph), 6.14 (t, JPH=2.0 Hz, 1H, ꢁCH),
2.80–2.68 (m, 6H, PCH), 1.21 (doublet of virtual
triplets, J=7.0 and 6.3 Hz, 18H, PCHCH3), 1.17 (dou-
blet of virtual triplets, J=7.0 and 6.3 Hz, 18H,
PCHCH3), −0.15 (s, SiMe2). 13C{1H}-NMR (toluene-
d8, 0 °C): l 207.6 (t, 2JPC=14 Hz, CO), 179.0 (t,
2JPC=9 Hz, RuCPhꢁ), 151.8 (s, Ph), 142.6 (s, Ph),
134.0 (s, CPh=CSi), 128.5 (s, Ph), 127.9 (s, Ph), 127.5
(s, Ph), 126.9 (s, Ph), 24.4 (virtual triplet, Japp=9 Hz,
PCHCH3), 20.3 (s, PCHCH3), 19.9 (s, PCHCH3),
−0.8 (s, SiMe2). 31P{1H}-NMR (CDCl3, 20 °C): l
33.7 (s).
4.3.15. (Z)-p-CH3C6H4CHꢁCHSiMe2Ph
1H-NMR (CDCl3): l 7.60–7.52 (m, 2H, Ar), 7.43 (d,
J=15.3 Hz, 1H, ArCHꢁ), 7.38–7.32 (m, 3H, Ar), 7.13
(d, J=8.1 Hz, 2H, Ar), 7.03 (d, J=8.1 Hz, 2H, Ar),
6.94 (d, J=15.0 Hz, 1H, ꢁCHSi), 2.30 (s, 3H, Me), 0.28
(s, 6H, SiMe2). 13C{1H}-NMR (CDCl3): l 148.0, 139.8,
137.3, 136.7, 133.7, 129.0, 128.8, 128.5, 128.2, 127.8,
21.2, −1.1. MS, m/z (relative intensity, %): 252 [M+,
27], 237 (50), 159 (100), 145 (34), 135 (13), 121 (24), 105
(15), 59 (13), 53 (14), 43 (55). Anal. Calc. for C17H20Si:
C, 80.89; H, 7.99. Found: C, 80.76; H, 7.88%.
After the sample solution was allowed to stand at r.t.
for 3 days, two singlet signals at l 33.7 and 37.0, which
are assignable to 7b and Ru(CH(CHPh)Cl(CO)(PPri3)2
(6b), respectively, were observed in a 2:1 ratio by
31P{1H}-NMR spectroscopy.
A solution of 7b in CDCl3 was similarly prepared,
and HSiMe2Ph (1.9 mg, 0.014 mmol) and anisole (1.0
1
ml, 9.2 mmol; an internal standard for H-NMR and
1
GLC analysis) were added at r.t. The H-NMR spec-
4.3.16. (Z)-cyclo-C6H11CHꢁCHSiMe2Ph
trum measured after a few minutes showed the forma-
tion of (Z)- and (E)-PhCHꢁCHSiMe2Ph in 82 and 5%
yield, respectively.
1H-NMR (CDCl3): l 7.58–7.52 (m, 2H, Ph), 7.38–
7.32 (m, 3H, Ph), 6.22 (dd, J=13.8 and 9.9 Hz, 1H,
CyCHꢁ), 5.51 (d, J=13.8 Hz, 1H, ꢁCHSi), 2.12–1.96
(m, 1H, Cy), 1.68–1.44 (m, 5H, Cy), 1.16–0.96 (m, 5H,
Cy), 0.37 (s, 6H, SiMe2). 13C{1H}-NMR (CDCl3): l
156.5, 139.9, 133.7, 128.7, 127.7, 124.3, 42.7, 32.7, 25.8,
25.6, −0.7. MS, m/z (relative intensity, %): 244 [M+,
2], 229 (11), 185 (11), 166 (40), 151 (21), 135 (100), 121
(65), 105 (17), 59 (31), 43 (69). Anal. Calc. for C16H24Si:
C, 78.61; H, 9.90. Found: C, 78.73; H, 9.83%.
4.5. Palladium-catalyzed coupling of styrylsilanes with
p-iodotoluene
A typical procedure (run 3 in Table 4) is as follows.
PhCHꢁCHSiMe2[C6H3ꢂ3,5-(CF3)2] (93.6 mg, 0.25
mmol, (E)/(Z)=99/1) and p-iodotoluene (43.6 mg,
0.20 mmol) were dissolved in THF (1 ml), and added to
a Schlenk tube containing [PdCl(p3-allyl)]2 (1.8 mg, 4.9
4.3.17. (Z)-n-C6H13CHꢁCHSiMe2Ph
1H-NMR (CDCl3): l 7.59–7.49 (m, 2H, Ph), 7.39–
7.31 (m, 3H, Ph), 6.43 (dt, J=13.9 and 7.5 Hz, 1H,
CHꢁ), 5.62 (dt, J=13.9 and 1.3 Hz, 1H, ꢁCHSi), 2.03
(dt, J=7.5 and 1.3 Hz, 2H, CH2), 1.38–1.12 (m, 8H,
CH2), 0.86 (t, J=7.2 Hz, 3H, Me), 0.37 (s, 6H, SiMe2).
13C{1H}-NMR: l 151.0, 139.8, 133.7, 128.7, 127.7,
126.4, 33.8, 31.7, 29.5, 28.9, 22.6, 14.1, −0.8. MS, m/z
mmol).
A THF solution of tetrabutylammonium
fluoride (1.0 M, 0.25 ml) was added, and the mixture
was stirred at r.t. for 1 h. GLC analysis revealed 100%
conversion of p-iodotoluene. The solvent was removed
by pumping and the residue was subjected to flash
column chromatography (SiO2, hexane), giving 4-
methylstilbene (11) in 83% yield (32.3 mg, (E)/(Z)=99/

200
H. Katayama et al. / Journal of Organometallic Chemistry 645 (2002) 192–200
(b) A. Mori, E. Takahashi, H. Kajiro, Y. Nishihara, T. Hiyama,
Polyhedron 19 (2000) 567;
(c) A. Mori, E. Takahisa, H. Kajiro, Y. Nishihara, T. Hiyama,
Macromolecules 33 (2000) 1115.
1). The reaction of run 4 in Table 4 was similarly
performed.
4.5.1. (E)-11
[6] Y. Maruyama, K. Yamamura, I. Nakayama, K. Yoshiuchi, F.
Ozawa, J. Am. Chem. Soc. 120 (1998) 1421.
[7] (a) Y. Maruyama, K. Yamamura, T. Sagawa, H. Katayama, F.
Ozawa, Organometallics 19 (2000) 1308;
1H-NMR (CDCl3): l 7.51 (d, J=7.5 Hz, 2H, Ar),
7.43 (d, J=8.1 Hz, 2H, Ar), 7.34 (t, J=8.1 Hz, 2H,
Ar), 7.29–7.22 (m, 1H, Ar), 7.18 (d, J=8.4 Hz, 2H,
Ar), 7.09 (s, 2H, HCꢁ), 2.37 (s, 3H, Me).
(b) Y. Maruyama, K. Yamamura, F. Ozawa, Chem. Lett. (1998)
905.
[8] (a) I. Ojima, N. Clos, R.J. Donovan, P. Ingellina, Organometal-
lics 9 (1990) 3127;
4.5.2. (Z)-11
1H-NMR (CDCl3): l 7.30–7.12 (m, 7H, Ar), 7.03 (d,
J=8.4 Hz, 2H, Ar), 6.56 (s, 2H, HCꢁ), 2.31 (s, 3H,
Me).
(b) R.S. Tanke, R.H. Crabtree, J. Am. Chem. Soc. 112 (1990)
7984;
(c) C.-H. Jun, R.H. Crabtree, J. Organomet. Chem. 447 (1993)
177 and references cited therein.
The assignment of (E)- and (Z)-isomers was based
on comparison of the chemical shifts of vinylic protons
with those of (E)- and (Z)-stilbenes (l 7.12 and 6.60,
respectively).
[9] M.A. Esteruelas, J. Herrero, L.A. Oro, Organometallics 12
(1993) 2377.
[10] S.M. Maddock, C.E.F. Rickard, W.R. Roper, L.J. Wright,
Organometallics 15 (1996) 1793.
[11] Y. Na, S. Chang, Org. Lett. 2 (2000) 1887.
[12] (a) M.R. Torres, A. Vegas, A. Santos, J. Organomet. Chem. 309
(1986) 169;
Acknowledgements
(b) M.R. Torres, A. Vegas, A. Santos, J. Ros, J. Organomet.
Chem. 326 (1987) 413;
(c) H. Werner, M.A. Esteruelas, H. Otto, Organometallics 5
(1986) 2295.
[13] An excess amount of alkyne is known to improve the stereoselec-
tivity by suppressing isomerization of (Z)-alkenylsilane to ther-
modynamically more stable (E)-isomer [8a].
This work was supported by a Grant-in-Aid for
Scientific Research from the Ministry of Education,
Science, Sports and Culture, Japan.
[14] Since no details of reaction conditions have been reported [9], we
are uncertain the reported reaction to be checked precisely.
[15] The formation of styrene from 6b and HSiMe2Ph may proceed
via process (v) which involves prior dissociation of phosphine
ligand (Scheme 2), while the detail of reaction could not be
confirmed owing to the extremely low reactivity of 6b.
[16] Note that the present discussion never excludes the direct forma-
tion path of 5b from 4b and hydrosilane [9].
[17] (a) Y. Hatanaka, T. Hiyama, Synlett (1991) 845;
(b) K. Tamao, K. Kobayashi, Y. Ito, Tetrahedron Lett. 30
(1989) 6051;
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