Stereocontrolled synthesis of (E)- and (Z)-poly(p-phenylenevinylene)s via ruthenium-catalyzed hydrosilylation of p-diethynylbenzene

Article abstract of DOI:10.1016/S0022-328X(03)00266-3

Stereocontrolled synthesis of poly(phenylenevinylene)s (PPVs) with (E)- and (Z)-vinylene units has been examined. Ruthenium complex-catalyzed hydrosilylation of p-diethynylbenzene with HSiMe₂Ar (Ar=2-thienyl (Th),3,5-(CF₃)₂C₆H₃) proceeds readily in CH₂Cl₂ at room temperature to give (E,E)- or (Z,Z)-bis(2-silylethenyl)benzenes (3a, 3b) in 89-40% yields. The geometries of 3a and 3b are clearly dependent on ruthenium catalysts employed. Thus, RuHCl(CO)(PPh₃)₃ forms (E,E)-isomers in over 99% selectivities, whereas RuCl₂(CO) (PPrⁱ₃)₂ affords (Z,Z)-3a and 3b with 92 and 91% geometrical purities, respectively. The (E,E)- and (Z,Z)-isomers of 3a and 3b undergo polycondensation with 2,5-dioctyloxy-1,4-diiodobenzene in THF in the presence of a palladium catalyst ([PdCl(η³-allyl)]₂, Pd(dba)₂) and tetrabutylammonium fluoride hydrate, giving (E)-rich and (Z)-rich PPVs in high yields.

Full text of DOI:10.1016/S0022-328X(03)00266-3

Journal of Organometallic Chemistry 676 (2003) 49Á54
/
www.elsevier.com/locate/jorganchem
Stereocontrolled synthesis of (E)- and (Z)-poly(p-phenylenevinylene)s
via ruthenium-catalyzed hydrosilylation of p-diethynylbenzene
Hiroyuki Katayama *, Masato Nagao, Rie Moriguchi, Fumiyuki Ozawa *
Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
Received 24 January 2003; received in revised form 10 April 2003; accepted 10 April 2003
Abstract
Stereocontrolled synthesis of poly(phenylenevinylene)s (PPVs) with (E)- and (Z)-vinylene units has been examined. Ruthenium
complex-catalyzed hydrosilylation of p-diethynylbenzene with HSiMe
2
Ar (Arꢀ
/
2-thienyl (Th), 3,5-(CF
40% yields. The geometries of 3a
forms (E,E)-isomers in over 99%
affords (Z,Z)-3a and 3b with 92 and 91% geometrical purities, respectively. The (E,E)- and
Z,Z)-isomers of 3a and 3b undergo polycondensation with 2,5-dioctyloxy-1,4-diiodobenzene in THF in the presence of a palladium
3 2 6 3
) C H ) proceeds readily in
CH Cl at room temperature to give (E,E)- or (Z,Z)-bis(2-silylethenyl)benzenes (3a, 3b) in 89Á
/
2
2
3 3
and 3b are clearly dependent on ruthenium catalysts employed. Thus, RuHCl(CO)(PPh )
i
2 3 2
selectivities, whereas RuCl (CO)(PPr )
(
3
catalyst ([PdCl(h -allyl)] , Pd(dba) ) and tetrabutylammonium fluoride hydrate, giving (E)-rich and (Z)-rich PPVs in high yields.
2
2
#
2003 Elsevier Science B.V. All rights reserved.
Keywords: Hydrosilylation; Alkyne; Polycondensation; Stereocontrolled synthesis; Poly(phenylenevinylene)
1
. Introduction
Having the highly selective catalysts giving (E)- and
Z)-alkenylsilanes in hand, we examined in this study
(
Alkenylsilanes are versatile starting materials in
organic synthesis [1]. We recently demonstrated that
E)- and (Z)-isomers of alkenylsilanes may be indepen-
stereocontrolled synthesis of poly(p-phenylenevinylene)s
(PPVs, 5) having (E)- and (Z)-vinylene units (Scheme
1). While p-conjugated polymers of this type are highly
expected electrooptical materials and their optical
properties are known to be dependent on stereoregular-
ity of the polymer backbone [5], stereocontrolled synth-
esis of both geometrical isomers of PPVs has so far been
extremely limited [6].
(
dently synthesized from the same starting materials,
simply by the choice of ruthenium catalysts for hydro-
silylation of terminal alkynes [2,3]. Thus, the treatment
of RCÅ
/
CH (Rꢀ
/
Ph, p-tolyl, Cy, n-hexyl) with HSi-
Me Ar (Arꢀ
/Ph, 3,5-(CF ) C H , 4-CF C H , 4-
4
2
3 2
6
3
3
6
MeOC H ) in CH Cl
in the presence of
CHSi-
Me Ar in over 99% selectivities. On the other hand, the
6
4
2
2
RuHCl(CO)(PPh ) catalyst (1) forms (E)-RCHÄ
/
3
3
2. Results and discussion
2
same starting materials are converted into (Z)-RCHÄ
CHSiMe Ar in 91Á99% selectivities using Ru(Si-
Me Ph)Cl(CO)(PPr ) (2) instead of 1 as the catalyst.
/
2.1. Hydrosilylation of p-diethynylbenzene
/
2
i
2
3 2
Our synthetic route to PPVs consists of two catalytic
reactions. One is ruthenium-catalyzed hydrosilylation of
Both reactions proceed readily at room temperature in
almost quantitative yields. We also reported mechanistic
details of the (E)- and (Z)-selective catalytic processes
p-diethynylbenzene to give bis(2-silylethenyl)benzene
(
3). The other is palladium-catalyzed polycondensation
[
2,4].
of 3 with 2,5-dioctyloxy-1,4-diiodobenzene (4), which is
based on the Hiyama cross-coupling reaction [7]. Since
polycondensation proceeds via a number of repetitions
of a catalytic reaction, the parent catalysis should be as
efficient as possible. Although the palladium-catalyzed
*
978.
Corresponding authors. Tel.: ꢁ
/
82-6-6605-2885; fax: ꢁ
/
82-6-6605-
(H.
2
E-mail
Katayama).
address:
katayama@a-chem.eng.osaka-cu.ac.jp
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00266-3

50
H. Katayama et al. / Journal of Organometallic Chemistry 676 (2003) 49Á54
/
ducts H CÄ
/
CHC H CHÄ
/CHSiMe Ar were formed in
2
2
6
4
addition to 3.
We next examined (Z)-selective hydrosilylation. As
already reported [2], silylruthenium complex 2 exhibits
extremely high catalytic activity. However, this complex
is rather difficult to prepare. While the ruthenium
i
hydrides RuHCl(CO)L (Lꢀ
/
PPr , PCy ) coordinated
3
2
3
with bulky phosphine ligands have been known to serve
as precursors of (Z)-selective catalysts [2,10], we found
i
RuCl (CO)(PPr ) (6) as a better alternative. Thus,
2
3 2
complex 6 is synthesized easily in high yield [11] and
exhibits the stereoselectivity, comparable to 2 and
slightly higher than RuHCl(CO)L [12].
2
Treatment of p-diethynylbenzene with 2 molar quan-
tity of HSiMe Th in CH Cl in the presence of 10 mol%
of 6 at room temperature for 5 h afforded (Z,Z)-3a in
2
2
2
9
2% geometrical purity [i.e. (Z,Z)/(E,Z)ꢀ
/92/8] and
59% isolated yield. While the single hydrosilylation
product (11%) was also formed in the reaction system,
this could be removed by column chromatography.
Similarly, (Z,Z)-3b [(Z,Z)/(E,Z)ꢀ
in 40% isolated yield.
,4-bis(2-Silylethenyl)benzenes thus obtained were
/
91/9] was prepared
1
1
characterized by elemental analysis and H- and
1
C{ H}-NMR spectroscopy. The H-NMR spectra of
E,E)-3a and (E,E)-3b exhibited olefinic proton signals
3
1
1
(
Scheme 1.
3
at d 6.95 and 6.57 ( JHHꢀ
/
19.1 Hz) and d 6.97 and 6.54
19.1 Hz), respectively. On the other hand, the
3
(
corresponding signals of (Z,Z)-isomers appeared with a
JHH
ꢀ
/
3
cross-coupling using organosilicon reagents often re-
quires a heated condition, alkenylsilanes with a silacy-
clobutane structure [8] and those with 2-thienyl (Th) [9]
and 3,5-(CF ) C H [2] substituents have recently been
smaller HÁ
Hz); 3b: d 7.47 and 5.93 ( JHHꢀ
/
H coupling [3a: d 7.43 and 5.99 ( JHHꢀ
/14.8
3
/
15.0 Hz)]. The four
aromatic protons of the central benzene ring exhibited
only one singlet for all compounds, showing the
symmetrically substituted structures of 3.
3
2
6
3
shown to be sufficiently reactive at room temperature
7]. Furthermore, since the ruthenium-catalyzed hydro-
silylation of terminal alkynes successfully proceeds with
[
2.2. Palladium-catalyzed polycondensation
the hydrosilanes of the type HSiMe Ar [2], we chose
2
Table 1 lists the results of polycondensation between
HSiMe Th and HSiMe [C H -3,5-(CF ) ] as hydrosily-
3 2
2
2
6
3
equimolar amounts of 3 and 2,5-dioctyloxy-1,4-diiodo-
benzene (4). Except for run 9, the reactions were carried
out at room temperature in THF in the presence of
palladium catalyst and 2 molar quantity of tetrabuty-
lation reagents.
The reaction of p-diethynylbenzene with 5 molar
quantity of HSiMe Th in CH Cl in the presence of 10
2
2
2
mol% of 1 was completed in 1 h at room temperature,
giving (E,E)-3a in almost perfect selectivity as con-
1
firmed by H-NMR analysis of the crude product. The
lammonium fluoride hydrate (TBAF×
added as an activator of 3 [7,13]. The (E,E)-isomers of
a and 3b were polymerized without notable loss of the
/
3H O), which was
2
3
analytically pure (E,E)-3a [(E,E)/(E,Z)ꢀ99/1] was
/
geometrical purity of vinylene unit, giving (E)-rich
poly[(1,4-phenylenevinylene)-alt-(2,5-dioctyloxy-1,4-
phenylenevinylene)] (5) in almost quantitative yields
obtained in 75% yield by silica-gel column chromato-
graphy. Similarly, hydrosilylation of p-diethynylbenzene
with HSiMe [C H -3,5-(CF ) ] gave (E,E)-3b in 89%
3
2
6
3
3 2
(
runs 1, 2). The catalyst precursors [PdCl(h -allyl)] ,
2
isolated yield [(E,E)/(E,Z)ꢀ99/1]. The use of hydro-
/
Pd(dba) , and Pd(OAc) gave comparable results with
each other for the reactions of (E,E)-3a (runs 1,3,4),
while for (E,E)-3b only [PdCl(h -allyl)] exhibited the
catalytic activity. Phosphine-coordinated complexes
such as Pd(PPh ) were much less reactive (run 5).
2
2
silanes in excess to p-diethynylbenzene is of particular
importance for obtaining the doubly hydrosilylated
products in high yields; otherwise, the reactions were
not completed in 24 h at room temperature, and
considerable amounts of single hydrosilylation products
3
2
3
4
Polycondensation of (Z,Z)-isomers was similarly
3
HCÅ
/
CC H CHÄ
/CHSiMe Ar and their reduction pro-
2
examined (runs 6Á9). Using [PdCl(h -allyl)] as an
/
6
4
2

H. Katayama et al. / Journal of Organometallic Chemistry 676 (2003) 49Á
/54
51
Table 1
Palladium-catalyzed polycondensation between 3 and 4
a
b
c
d
Run
3
Catalyst
Yield (%) of 5
M
n
(M /M
w
n
)
(E):(Z)
3
1
2
3
4
5
6
7
8
(E,E)-3a
(E,E)-3b
(E,E)-3a
(E,E)-3a
(E,E)-3a
(Z,Z)-3a
(Z,Z)-3b
(Z,Z)-3a
(Z,Z)-3a
[PdCl(h -allyl)]
2
ꢀ
ꢀ/
/
99
99
95
99
0
5700 (1.62)
6300 (2.30)
5000 (1.39)
5700 (1.64)
ꢀ
/
99:B
/
1
99:1
3
[PdCl(h -allyl)]
2
Pd(dba)
Pd(OAc)
Pd(PPh
2
ꢀ
/
99:B
/
1
1
2
ꢀ/
ꢀ/
99:B
/
3
3
)
4
Á/
Á
/
[PdCl(h -allyl)]
2
97
98
97
83
1600 (1.20)
3100 (1.27)
3700 (1.37)
1900 (1.27)
45:55
46:54
34:66
38:62
3
[PdCl(h -allyl)]
2
Pd(dba)
2
e
9
Pd(dba)
2
All reactions were run in THF in the presence of palladium catalyst and TBAF×
/
3H
2
O at room temperature for 24 h, except for run 9. Initial
3H O] 0.20 M.
3
concentration: [3]
a
0
ꢀ
/
[4]
0
ꢀ
/0.10 M, [catalyst]
0
ꢀ
/
5 (for [PdCl(h -allyl)]
2
) or 10 mol% (for other complexes), [TBAF×
/
2
0
ꢀ/
Geometrical purity: (E,E)-3a (ꢀ
/
99%), (E,E)-3b (99%), (Z,Z)-3a (92%), (Z,Z)-3b (91%). The minor isomer has (E,Z) geometry in all cases.
b
c
Isolated yield.
Determined by GPC based on polystyrene standards.
d
e
1
Determined by H-NMR spectroscopy.
The reaction was carried out at 0 8C for 4 h.
catalyst precursor, moderately (Z)-rich 5 was obtained
in high yields both from (Z,Z)-3a and 3b (runs 6, 7).
The (Z) content of vinylene unit was somewhat
4. Experimental
3
improved by using Pd(dba) in place of [PdCl(h -allyl)]
4.1. General considerations
2
2
(
run 8), but no further improvement was observed even
at lower reaction temperature (run 9). Since the isolated
polymer was thermally stable [14], the (Z) to (E)
isomerization of vinylene unit is considered to take
place during the polymerization.
All manipulations were conducted under a nitrogen
atmosphere using conventional Schlenk techniques.
Nitrogen gas was purified by passing successively
through the columns of an activated copper catalyst
(E)- and (Z)-rich 5 were isolated as an orange powder
or a gummy paste, respectively, which were highly
(BASF, R3-11) and P O (Merck, SICAPENT). IR
2 5
spectra were recorded on a JASCO FT/IR-410 instru-
ment. NMR spectra were recorded on a Varian Mercury
soluble in THF, toluene, and CHCl , and insoluble in
3
1
MeOH and hexane. Fig. 1 shows the H-NMR spectra.
1
13
300 spectrometer ( H-NMR, 300.11 MHz; C-NMR,
5.46 MHz). Chemical shifts are reported in d (ppm),
7
The ratio of (E)- and (Z)-vinylene units was determined
by peak integration of the signals at around d 4.0 and
1
13
referred to H (of residual protons) and C signals of
deuterated solvents. Mass spectra were measured with a
Shimadzu QP-5000 GC-mass spectrometer (EI, 70 eV).
Flash column chromatography was performed with
3
.5, which are assignable to OCH protons of octyloxy
2
groups, adjacent to (E)- and (Z)-vinylene units, respec-
tively [6a,b].
Merck silica gel 60 (230Á400 mesh). Gel permeation
/
chromatography was carried out on a JASCO GPC
system equipped with an RI detector and three GPC
columns (Shodex KF-801, KF-803L, KF-805L). Melt-
ing points were measured on a Yanaco MP-S3 instru-
ment. Elemental analyses were carried out with a
Perkin-Elmer 2400II CHN analyzer.
3
. Conclusion
We have described that hydrosilylation of p-diethy-
nylbenzene catalyzed by RuHCl(CO)(PPh ) (1) and
3
3
Dichloromethane and THF were dried over CaH and
2
i
RuCl (CO)(PPr ) (6) leads to almost geometrically
2
3 2
sodium benzophenone ketyl, respectively. These solvents
were distilled and stored over activated molecular sieves
pure (E,E)- and (Z,Z)-bis(2-silylethenyl)benzenes (3),
respectively. The products could be utilized as mono-
mers for palladium-catalyzed polycondensation with
(MS4A) under a nitrogen atmosphere. The following
compounds were synthesized according to literatures:
i
2
,5-dioctyloxy-1,4-diiodobenzene (4) in the presence of
RuHCl(CO)(PPh ) (1) [15], RuCl (CO)(PPr ) (6) [11],
3
3
2
3 2
TBAF×3H O, giving (E)- and (Z)-rich PPVs (5).
/
p-diethynylbenzene [16], dimethyl(2-thienyl)silane [9],
dimethyl[3,5-bis(trifluoromethyl)phenyl]silane [17], 2,5-
2
Although the (Z)-regularity still has an ample space to
be improved, this study represents a new stereocon-
trolled way of synthesizing PPVs.
dioctyloxy-1,4-diiodobenzene (4) [18], Pd(dba) [19],
2
3
[PdCl(h -allyl)] [19]. All other chemicals were obtained
2

52
H. Katayama et al. / Journal of Organometallic Chemistry 676 (2003) 49Á54
/
1
Fig. 1. H-NMR spectra of (CDCl
3
, 300.11 MHz) of (E)-rich (top) and (Z)-rich 5 (bottom), isolated from the reaction systems of runs 3 and 8 in
and water, respectively.
Table 1, respectively. The starred signals at d 7.26 and 1.60 are due to residual CHCl
3
from commercial suppliers and used without further
purification.
removed by pumping. The resulting orange solid was
purified by flash column chromatography (SiO2,
hexaneÁ
/
CH Cl ꢀ
/
9/1) to give analytically pure (E,E)-
99/1] as a white solid (455 mg, 75%
2
2
3a [(E,E)/(E,Z)ꢀ
/
4
.2. Catalytic hydrosilylation of p-diethynylbenzene
yield). Similarly, (E,E)-3b containing 1% of (E,Z)-
isomer was obtained in 89% yield, using HSi-
A typical procedure for (E,E)-selective reaction is as
follows. Solid RuHCl(CO)(PPh3)3 (1) (144 mg, 151
Me
(Z,Z)-Selective reactions were carried out in CH
at r.t. for 5 h using p-diethynylbenzene, hydrosilanes (2
[C H -3,5-(CF ) ] in place of HSiMe Th.
2 6 3 3 2 2
mmol) was added to a solution of p-diethynylbenzene
2
Cl
2
(
in CH Cl (5.4 ml) at room temperature (r.t.). The
186 mg, 1.47 mmol) and HSiMe Th (1.15 g, 8.08 mmol)
2
i
molar quantity), and RuCl
(Z,Z)-3a [(Z,Z)/(E,Z)ꢀ92/8] and 3b [(Z,Z)/(E,Z)ꢀ
91/9] were obtained in 59 and 40% yields, respectively.
(CO)(PPr ) (6, 10 mol%).
2
2
2 3 2
mixture instantly changed into a red solution. After
stirring the solution for 1 h, volatile materials were
/
/

H. Katayama et al. / Journal of Organometallic Chemistry 676 (2003) 49Á
/54
53
1
No trace of (E,E)-isomer was detected by H-NMR
spectroscopy.
4.3. Palladium-catalyzed polycondensation
A typical procedure (run 3 in Table 1) is as follows.
Solid Pd(dba) (10.3 mg, 0.0199 mmol) and a solution of
4
.2.1. (E,E)-3a
M.p.: 86 8C. H-NMR (CDCl ): d 7.64 (dd, Jꢀ
.9 Hz, 2H, Th), 7.41 (s, 4H, C H ), 7.32 (dd, Jꢀ
.9 Hz, 2H, Th), 7.22 (dd, Jꢀ
2
1
/
4.6,
TBAF in THF (1.0 M containing 5 wt% water, Aldrich)
were added successively to a solution of (E,E)-3a (82.2
mg, 0.200 mmol) and 2,5-dioctyloxy-1,4-diiodobenzene
(4) (117 mg, 0.200 mmol) in THF (1.6 ml). The mixture
was stirred at r.t. for 24 h. The resulting deep red sticky
suspension was poured into vigorously stirred MeOH
3
0
0
/3.6,
6
4
/
4.6, 3.6 Hz, 2H, Th), 6.95
(
d, Jꢀ
/
19.1 Hz, 2H, C H CHꢀ
/
), 6.57 (d, Jꢀ19.1 Hz,
/
6
4
1
3
1
2
H, Ä
/
CHSi), 0.48 (s, 12H, SiMe2). C{ H}-NMR
), 137.9, 134.8, 131.0,
CHSi), ꢂ
(
CDCl ): d 144.9 (s, C H CHÄ
/
3
6
4
1
1
3
28.2, 126.9, (each s, C H and Th), 126.8 (s, Ä
/
/
(50 ml). The orangeÁbrown solid of polymer (5) thus
/
6
4
ꢁ
.3 (s, SiMe ). MS, m/z (rel. intensity, %): 410 [M , 26],
95 (2), 326 (9), 311 (11), 227 (16), 190 (15), 169 (15), 141
precipitated was collected by filtration and washed with
MeOH (88 mg, 95% yield). (E)-Content of vinylene unit
2
1
99%) was determined by H-NMR analysis. The
(100), 127 (28), 115 (9), 101 (14), 75 (12). Anal. Calc. for
C H S Si : C, 64.33; H, 6.38. Found: C, 63.92; H,
(ꢀ
/
molecular weight data (M ꢀ
/
5000, M /M ꢀ
/1.39) were
2
2
26
2
2
n
n
w
6
.35%.
collected by GPC analysis using polystyrene standards
ꢂ1
(
THF, flow rate 1.0 ml min ).
4
.2.2. (Z,Z)-3a
1
M.p.: 49 8C. H-NMR (CDCl ): d 7.61 (dd, Jꢀ
/
4.8,
14.8 Hz, 2H, C H CH Ä),
4.8, 3.3
14.8 Hz,
3
4.3.1. (E)-rich 5 [(E)/(Z)ꢀ
M.p.: ꢀ380 8C (dec). IR (KBr): 3048, 2926, 2855,
597, 1510, 1495, 1468, 1421, 1379, 1279, 1260, 1205,
/
ꢀ
/
99/1]
0
7
.8 Hz, 2H, Th), 7.43 (d, Jꢀ
/
/
6
4
/
.28 (dd, Jꢀ3.3, 0.8 Hz, 2H, Th), 7.18 (dd, Jꢀ
/
/
1
ꢂ1
1
Hz, 2H, Th), 7.16 (s, 4H, C H ), 5.99 (d, Jꢀ
/
6
4
1136, 1043, 964, 849, 805 cm . H-NMR (CDCl ): d
3
1
3
1
2
(
1
H, Ä
/
CHSi), 0.32 (s, 12H, SiMe2).
C{ H}-NMR
), 139.1, 138.9, 134.6,
30.8, 130.0, 128.2 (each s, C H and Th), 127.9 (s, Ä
CHSi), 0.1 (s, SiMe ). MS, m/z (rel. intensity, %): 410
M , 25], 326 (10), 311 (12), 270 (9), 227 (21), 190 (12),
7.56Á
Ar and CHÄ
(br, 4H, CH ), 1.48Á
/
7.42 (m, 6H, Ar and CHÄ
CH), 4.08Á3.92 (br, 4H, OCH ), 1.94Á
1.20 (br, 20H, CH ), 0.94Á
/
CH), 7.18Á7.05 (m, 4H,
/
CDCl ): d 147.8 (s, C H CHÄ
/
3
6
4
/
/
/1.72
2
/
6
4
/
/0.82 (br,
2
2
2
6H, CH3).
ꢁ
[
1
7
71 (23), 141 (100), 127 (30), 115 (12), 101 (15), 84 (15),
5 (17). Anal. Calc. for C H S Si : C, 64.33; H, 6.38.
4
.3.2. (Z)-rich 5 [(E)/(Z)ꢀ
IR (KBr): 3046, 2925, 2855, 1603, 1495, 1469, 1422,
/
34/66]
2
2
26
2
2
Found: C, 64.08; H, 6.39%.
ꢂ1 1
1
379, 1278, 1205, 1137, 1045, 964, 850 cm . H-NMR
7.03 (m, 6H, Ar and CHÄCH), 6.78Á
.48 (m, 4H, Ar and CHÄCH), 4.02Á3.86 (br, 1.36H,
3.48 (br, 2.64H,
OCH2 in (Z)-olefin fragment), 1.80Á1.16 (br, 24H,
CH ), 0.91Á0.79 (br, 6H, CH3).
(CDCl ): d 7.54Á
/
/
/
3
4
.2.3. (E,E)-3b
6
/
/
1
M.p.: 109 8C. H-NMR (CDCl ): d 7.95 (br s, 4H,
3
OCH in (E)-olefin fragment), 3.62Á
/
2
C H -3,5-(CF ) ), 7.87 (br s, 2H, C H -3,5-(CF ) ), 7.45
(
6
3
3 2
6
3
3 2
/
s, 4H, C H ), 6.97 (d, Jꢀ
/
19.1 Hz, 2H, C H CH Ä
/
),
6
4
6
4
/
2
6
.54 (d, Jꢀ
/
19.1 Hz, 2H, Ä
/
CHSi), 0.51 (s, 12H, SiMe ).
C{ H}-NMR (CDCl ): d 146.2 (s, C H CHÄ
2
1
3
1
/
), 142.2
s, C H ), 137.8, 133.5 (each s, C H -3,5-(CF ) ), 130.8
3
6
4
(
(
6
4
6
3
3 2
Acknowledgements
2
q, JFC
ꢀ33 Hz, C H -3,5-(CF ) ), 127.0 (s, C H ),
/
6 3 3 2 6 4
1
1
(
25.1 (s, Ä
/
CHSi), 123.6 (q, JFCꢀ
septet, JFCꢀ4 Hz, C H -3,5-(CF ) ), ꢂ
Anal. Calc. for C H F Si : C, 53.72; H, 3.91. Found:
/
273 Hz, CF ), 122.9
3
This work was supported by grant-in-aid for scientific
research from the Ministry of Education, Culture,
Sports, Science and Technology, Japan.
3
/
/2.8 (s, SiMe2).
6
3
3 2
3
0
26 12
2
C, 53.56; H, 3.83%.
4
.2.4. (Z,Z)-3b
M.p.: 47 8C. H-NMR (CDCl ): d 7.82 (br s, 4H,
1
References
3
C H -3,5-(CF ) ), 7.77 (br s, 2H, C H -3,5-(CF ) ), 7.47
(
6
3
3 2
6
3
3 2
[
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d, Jꢀ
/
15.0 Hz, 2H, C H CH Ä
/
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6 4
6
4
5
.93 (d, Jꢀ
/
15.0 Hz, 2H, Ä
/
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6
4
(
(
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(
27.6 (s, Ä
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Anal. Calc. for C H F Si : C, 53.72; H, 3.91. Found:
/
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3
3
/
/
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(
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[
[
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2
/
99% yield, E/Zꢀ
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(
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/
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/
2/98), RuHCl(CO)(PPr
3
)
2
(2 h,
9
/3/97), RuHCl(CO)(PCy
3 2
) (2 h, 97% yield, E/
(
Zꢀ
/
9
[
[
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(
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(
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0 8C for 24 h.
[
[
[
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(
(
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(
(
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