Palladium-catalyzed regioselective silaboration of 1,2-dienes

Article abstract of DOI:10.1016/S0022-328X(00)00472-1

Palladium complexes catalyzed regioselective addition of the Si-B bond of (dimethylphenylsilyl)pinacolborane to allenes in good yields. In the silaboration of terminal allenes having electron-donating substituents such as alkyl and methoxy groups, the Si-

Full text of DOI:10.1016/S0022-328X(00)00472-1

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Journal of Organometallic Chemistry 611 (2000) 403–413
Palladium-catalyzed regioselective silaboration of 1,2-dienes
Michinori Suginome *1, Yutaka Ohmori, Yoshihiko Ito *2
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto Uni6ersity, Sakyo-ku,
Kyoto 606-8501, Japan
Received 7 March 2000; accepted 26 March 2000
Abstract
Palladium complexes catalyzed regioselective addition of the SiꢀB bond of (dimethylphenylsilyl)pinacolborane to allenes in good
yields. In the silaboration of terminal allenes having electron-donating substituents such as alkyl and methoxy groups, the SiꢀB
bond added to the internal CꢁC bond with regioselective BꢀC and SiꢀC bond formation at the central and substituted carbon
atoms of the allene, respectively. In contrast, the silylborane preferably added to the terminal CꢁC bond with exclusive SiꢀC bond
formation at the terminal carbon atom in the silaboration of allenes bearing electron-withdrawing groups such as perfluoroalkyl
group. 1,3-Disubstituted allenes also underwent the silaboration in good yields with varying regio- as well as stereoselectivity. The
silyl and boryl groups of the 2-borylallylsilanes thus prepared were selectively utilized for further synthetic elaboration.
Palladium-catalyzed coupling of the 2-borylallylsilanes with aryl iodides afforded the corresponding 2-arylallylsilanes in fair-to-
good yields. 2-Boryl-p-allylpalladium complexes were successfully prepared by the reaction of the 2-borylallylsilanes with
PdCl2(CH3CN)2. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Silylborane; Silaboration; Allene; Palladium catalyst; Platinum catalyst; Regioselection; Isocyanide; 2-Borylallylsilane; 2-Boryl(p-al-
lyl)palladium complex; Cross-coupling
9]. In these reactions, an otherwise stable SiꢀB bond is
effectively activated by group 10 metal complexes and
exhibits its broader applicability to the reaction with
unsaturated compounds than other silicon-containing
s-bonds such as SiꢀSi and SiꢀSn. In the course of our
exploitation of new reactions, we have centered our
attention on regio- and stereoselectivity of the silabora-
tion reactions. It has been found that high selectivity is
attainable by appropriate choice of the metal as well as
the ligand of the catalysts in the silaboration reactions.
Recently, we reported preliminarily that silaboration
of allenes proceeded in a regio- and stereoselective
fashion in the presence of palladium catalysts [10,11].
Although related transition-metal catalyzed addition
reactions of SiꢀSi [12], SiꢀSn [13], and BꢀB [14] bonds
to allene have been documented [15], the new addition
reaction is unique in that synthetically useful 2-borylal-
lylsilanes are produced regioselectively in good yields.
Herein, we describe a full detail of the silaboration of
allenes, including mechanistic consideration and syn-
thetic application.
1. Introduction
Transition-metal catalyzed additions of silicon-con-
taining inter-element s-bonds to unsaturated organic
molecules have provided an attractive strategy for the
synthesis of organosilicon compounds which are other-
wise inaccessible [1,2]. While the additions of SiꢀSi
bond have been studied most extensively [3], interest
has also been focused on the addition reactions of
silicon–heteroatom bonds such as tin and germanium.
It has been shown that many of the additions of those
inter-element s-bonds proceed regioselectively to lead
to effective synthesis of regio-defined organosilicon
compounds.
We have developed addition reactions of SiꢀB bond
of silylboranes to unsaturated organic compounds [4–
1 *Corresponding author. Fax:
suginome@sbchem.kyoto-u.ac.jp
+81-75-7535668; e-mail:
2 *Corresponding author. E-mail: yoshi@sbchem.kyoto-u.ac.jp
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00472-1

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M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
2. Results and discussion
cyclohexyl-1,2-propadiene (2d) in the presence of
Pd(acac)2 (2 mol%)/t-Oc-NC (8 mol%) (entry 8). Nev-
ertheless, no regioisomer bearing a silyl group at the
central carbon was detected in the reaction mixture.
While the selectivity for the internal addition product
3d was only slightly improved by carrying out the
reaction at room temperature (entry 9), the amount of
t-Oc-NC employed as a ligand on palladium dramati-
cally affected the regioselectivity. In the presence of 30
and 100 mol% of t-Oc-NC with 2 mol% of Pd(acac)2,
the terminal addition product 4d was formed as a major
isomer in ratios of 26:74 and 22:78, respectively (entries
10 and 11). On the other hand, the regioisomeric ratio
also varied with the ligand on palladium. Although
1-adamantyl isocyanide gave slightly lower ratio than
that for t-Oc-NC (entry 15), use of other isonitriles
such as Cy-NC, Xy-NC, and Dip-NC resulted in exclu-
sive formation of internal addition product 3d in good
yields (entries 12–14). Some other palladium complexes
including Pd(PPh3)4 and PdCl2(BINAP) (BINAP: 2,2%-
bis(diphenylphosphino)-1,1%-binaphthyl) similarly af-
forded 3d as a single regioisomer (entries 16 and 17).
However, Pd2(dba)3(CHCl3) resulted in the formation
of 53:47 mixture of 3d and 4d in lower yield (entry 18).
Silaboration of t-butylpropadiene (2e) also afforded
the internal addition product 3e in good yield. While
the use of t-Oc-NC as well as Xy-NC as ligands on
palladium resulted in the formation of a minor amount
of a terminal addition product 4e (entries 19 and 20),
PdCl2(PPh3)4 and Pd(PPh3)4 afforded the internal addi-
tion product 3e exclusively (entries 21 and 22).
We carried out reactions of phenylpropadiene (2f)
under various reaction conditions. As seen from Table
1, the minor formation of the terminal addition product
4f could not be avoided by changing the ligand, solvent,
and reaction temperature. However, the regioselectivity
of the silaboration catalyzed by Pd(acac)2/t-Oc-NC de-
pended upon the reaction temperature: an 84:16 ratio
for 3f and 4f was obtained at 80°C, while ratios of
66:34 and 81:19 were attained at room temperature and
120°C, respectively (entries 23–25). In the presence of
palladium catalysts bearing isonitriles, phosphines, and
phosphite as ligands, regioselectivity ranged from 81:19
to 90:10 (entries 27–38). The highest selectivity was
obtained for the reaction in the presence of a catalyst
generated from cyclopentadienyl(p-allyl)palladium with
P(OEt)3 (entry 38).
2.1. Silaboration of monosubstituted allenes
Reactions of 5-phenylpenta-1,2-diene (2a, 1.5 equiv)
with (dimethylphenylsilyl)pinacolborane 1 were carried
out in octane in the presence of various palladium
catalysts (Scheme 1, Table 1). Initially, we employed a
catalyst A% generated from Pd(acac)2 (2 mol%) with
1,1,3,3-tetramethylbutyl isocyanide (t-Oc-NC, 30
mol%), which was developed for highly effective cata-
lyst for the activation of SiꢀSi [16] as well as SiꢀB
bonds [4]. Catalyst A% afforded silaboration product 3a
in 77% yield at 120°C for 2 h (Table 1; entry 1). It
should be noted that only a single regioisomer, in which
the boryl and the silyl groups were exclusively attached
to 2- and 3-positions of the allene, respectively, was
formed in the reaction. As we previously reported in
the silaboration of alkynes, the silaboration of the
allene was catalyzed by palladium catalysts bearing a
wide range of ligands such as isonitriles and phosphines
[4]. We found that use of 2,6-dimethylphenyl isocyanide
(Xy-NC, 8 mol%) with Pd(acac)2 (2 mol%) (catalyst B)
gave the highest yields (99%) in the reaction of 2a with
1 (entry 2). The use of Xy-NC as the ligand enables to
reduce the amounts of the palladium complex (0.4
mol%) and allene 2a (1.2 equiv) without decrease in
yield and selectivity (entry 3). PdCl2(PPh3)2 also served
as an effective catalyst to afford 3a in 90% yield (entry
4). It may be worth mentioning that use of a platinum
catalyst resulted in the highly selective formation of a
regioisomeric product 4a albeit in low yield (ca. 10%)
without formation of any other regioisomers (Scheme
2). Similar preference for the terminal addition was also
reported in the related platinum-catalyzed additions to
allenes [14,15]. Silaboration of hepta-1,2-diene (2b) was
also catalyzed by the palladium catalyst with Xy-NC as
well as t-Oc-NC to give 2-boryl-3-silylhept-1-en (3b)
exclusively in high yield (entries 5 and 6). Ethyl penta-
3,4-dienoate (2c) also underwent the silaboration with 1
in the presence of the Xy-NC-based catalyst in high
yield and regioselectivity (entry 7).
Unlike the exclusive formation of the internal addi-
tion products (3) in the silaboration of the allenes with
primary alkyl substituents, minor formation of a termi-
nal addition product 4d was observed in the reaction of
Further experiments using p-substituted arylpropadi-
enes indicated that the regioselectivity of the silabora-
Scheme 1.
Scheme 2.

M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
405
Table 1
Palladium-catalyzed silaboration of terminal allenes a
Entry
Allene (R)
Catalyst b
Temp. (°C)
Yield (%) c
Regioselectivity (3:4)
1
2
2a (CH2CH2Ph)
2a
2a
2a
2b (n-Bu)
2b
2c (CH2CO2Et)
2d (Cy)
2d
2d
2d
2d
2d
2d
2d
2d
2d
2d
2e (t-Bu)
2e
2e
2e
2f (Ph)
2f
2f
2f
2f
2f
2f
2f
2f
2f
A%
B
B
F
A
B
120
120
120
120
80
120
120
120
r.t.
120
120
120
120
120
120
120
120
120
120
120
120
120
r.t.
77
99
96
90
98
99
98
(92)
(74)
90 (92)
(82)
76 (92)
(95)
81 (95)
(93)
(92)
78 (84)
(64)
79
88
74
51
(92)
86 (93)
(94)
95
(95)
(95)
73 (84)
(73)
(85)
(96)
(99)
(54)
(89)
(84)
(84)
(91)
76
100:0
100:0
100:0
100:0
100:0
100:0
97:3
82:18
84:16
26:74
22:78
100:0
100:0
100:0
76:24
100:0
100:0
53:47
85:15
94:6
100:0
100:0
66:34
84:16
81:19
86:14
86:14
87:13
84:16
82:18
87:13
85:15
87:13
85:15
86:14
81:19
84:16
90:10
94:6
3 d
4
5
6
7
8
B
A
A
A%
A%%
B
C
D
E
G
O
Q
A
B
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27 e
28 f
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
F
G
A%
A%
A%
B
B
B
F
G
H
I
J
K
L
M
N
P
B
B
80
120
120
120 in EDC
120 in DMF
120
120
120
120
120
120
120
120
120
120
120
120
r.t.
2f
2f
2f
2f
2f
2f
2g (p-MeOC6H4)
2h (p-CF3C6H4)
2i (OMe)
2i
2i
2i
2j (H)
2j
2j
81
36:64
70:30
86:14
99:1
A%
A%
A
B
A
B
(59)
(90)
91 (94)
92 (87)
93
80
80
120
80
120
120
100:0
79
65
F
a Silylborane 1, allenes 2 (1.5 equiv), and palladium catalyst (2 mol%) were used unless otherwise noted. Abbreviations: t-Oc: 1,1,3,3-
tetramethylbutyl; Xy: 2,6-dimethylphenyl; Cy: cyclohexyl; Dip: 2,6-diisopropylphenyl; 1-Adm: 1-adamantyl; dppe: 1,2-bis(diphenylphos-
phino)ethane; dppb: 1,4-bis(diphenylphosphino)butane; binap: 2,2’-bis(diphenylphosphino)-1,1’-binaphthyl; dba: dibenzalacetone.
b A: Pd(acac)2/t-Oc-NC (1/4); A%: Pd(acac)2/t-Oc-NC (1/15); A%%: Pd(acac)2/t-Oc-NC (1/50); B: Pd(acac)2/Xy-NC (1/4); C: Pd(acac)2/Cy-NC
(1/4); D: Pd(acac)2/Dip-NC (1/4); E: Pd(acac)2/1-Adm-NC (1/4); F: PdCl2(PPh3)2; G: Pd(PPh3)4; H: (h5-Cp)(h3-allyl)Pd/PPh3 (1/2); I: (h5-Cp)(h3-
allyl)Pd/PMePh2 (1/2); J: (h5-Cp)(h3-allyl)Pd/PMe2Ph (1/2); K: (h5-Cp)(h3-allyl)Pd/PBu3 (1/2); L: (h5-Cp)(h3-allyl)Pd/PCyPh2 (1/2); M: (h5-
Cp)(h3-allyl)Pd/dppe (1/1); N: (h5-Cp)(h3-allyl)Pd/dppb (1/1); O: PdCl2(binap); P: (h5-Cp)(h3-allyl)Pd/P(OEt)3 (1/2); Q: Pd2(dba)3(CHCl3).
c Isolated yield (GC yield in parentheses).
d 1.2 equiv of allene 2a and 0.4 mol% of Pd(acac)2 were used.
e A reaction in 1,2-dichloroethane.
f A reaction in DMF.

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M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
tion reaction significantly depended on the electronic
nature of the p-substituent. Thus, higher regioselectivity
for the internal addition product 3g was attained in the
reaction of p-methoxyphenylpropadiene (2g) with 1 in
the presence of Pd(acac)2/Xy-NC (1/4) (catalyst B),
whereas terminal addition product 4h was predomi-
nantly formed in the reaction of p-(trifluoromethyl)-
phenylpropadiene (2h) under the same reaction
conditions (entries 26, 39 and 40).
Silaboration of methoxypropadiene (2i) also pro-
ceeded regioselectively to afford internal addition
product 3i. As seen in the reactions of 2f, the regioselec-
tivity of the Pd(acac)2/t-Oc-NC catalyzed reactions de-
pended upon the reaction temperature as well as the
amount of the ligand employed. Thus, the reaction at
80°C in the presence of Pd(acac)2/t-Oc-NC (1/4) pro-
vided better selectivity and yield (entry 43) than those
for the reactions at room temperature (entry 41) or in
the presence of Pd(acac)2/t-Oc-NC (1/15) (entry 42).
The reaction of 2i was best catalyzed by Pd(acac)2/Xy-
NC (1/4) at 120°C to give 3i exclusively in high yield
(entry 44).
Gaseous allene (2j, 1 atm) also underwent the silabo-
ration in the presence of palladium catalyst bearing
isonitrile or phosphine ligands, giving 2-boryl-3-silyl-
propene (3j) in good yields (entries 45–47).
2.2. Silaboration of 1,1-disubstituted allenes
Reaction of 3-methylbuta-1,2-diene (5) with 1 in the
presence of the Pd(acac)2/Xy-NC resulted in the forma-
tion of a complex mixture. On the other hand, internal
addition product 6 was selectively obtained in low yield
by use of Pd(acac)2 with t-Oc-NC as ligand (Scheme 3).
It was found that the PdCl2(PPh3)2 catalyst was most
effective for the silaboration of 5 to give 6 without any
detectable formation of a terminal addition product.
2.3. Silaboration of 1,3-disubstituted allenes
Reaction of nona-4,5-diene (7) with 1 in the presence
of Pd(acac)2/Xy-NC afforded a mixture of E and Z-ad-
dition products (E)-8 and (Z)-8 in a 62:38 ratio in 88%
total yield (Scheme 4). While the reaction of 7 with 1 at
80°C in the presence of Pd(acac)2/t-Oc-NC also afforded
a 62:38 mixture of the E and Z isomers, the ratio was
improved to 89:11 by raising the reaction temperature to
120°C. PdCl2(PPh3)2 also catalyzed the reaction in good
yield, but gave a 66:34 mixture of (E)-8 and (Z)-8.
We also carried out a reaction of unsymmetrical 1,3-
disubstituted allene 9 in the presence of Pd(acac)2/Xy-
NC at 120°C. The reaction afforded all of the four
possible isomers (E)-10, (Z)-10, (E)-11, and (Z)-11 in
88% total yield (Scheme 5). The structure of each isomer
was identified by NMR experiments including NOE
measurements. They showed that the silyl group was
preferentially introduced to the allylic carbon atom
adjacent to the propyl group (10) rather than to that
adjacent to the cyclohexyl group (11) in a 64:36 ratio
with the corresponding (E)-isomers predominating.
Scheme 3.
2.4. Silaboration of perfluoroalkylated allenes
Some comments may be deserved on the remarkable
effect of perfluoroalkyl group on the regioselectivity of
the silaboration reaction. Perfluorohexylallene (12a) was
reacted with 1 in the presence of Pd(acac)2/Xy-NC at
120°C, providing terminal addition product 13a in high
yield as a single isomer with regioselectivity completely
opposite to that for primary-alkyl substituted allenes
(Scheme 6). A similar effect on the regioselectivity was
also found in the reaction of 1-perfluorohexylhexa-1,2-
diene (12b), which afforded a single product 13b bearing
the silyl group at the carbon remote from the perfluoro-
hexyl group. Although the geometry of the CꢁC bond in
13a could not be determined by an NOE experiment,
NOE between allylic and vinylic protons was observed
for 13b, being indicative of (E)-geometry of the CꢁC
bond.
Scheme 4.
Scheme 5.

M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
407
attached to more electron-rich sp2 carbon of the al-
lenes. The same regiochemical outcome for the internal
additions has also been reported for the palladium-
catalyzed bis-silylation and silastannation of terminal
allenes bearing alkyl groups.
Before assuming a plausible catalytic cycle of the
silaboration, we compared relative reactivity of 1,2-hep-
tadiene (2b), 4,5-nonadiene (7), and perfluoroalkyl-
propadiene (12a) by competitive reactions, in which
silylborane 1 was reacted with a mixture of two of the
three allenes (1.5 equiv each) in the presence of
Pd(acac)2/Xy-NC (1/4) at 120°C in octane (Scheme 7).
The competitive reaction revealed much higher reactiv-
ity of 2b than that of 7, indicating the presence of the
terminal CꢁC bond enhanced the reactivity, although
addition of SiꢀB bond took place only at the internal
CꢁC bond. On the other hand, 12a showed higher
reactivity than 2b, indicating the silaboration of CꢁC
bond bearing electron-withdrawing group was acceler-
ated in spite of the fact that the addition took place at
the terminal CꢁC bond of 12b.
Scheme 6.
Taking the results of the competitive reactions into
consideration, we may propose the following catalytic
cycle for the palladium-catalyzed silaboration of allenes
(Scheme 8). A (boryl)(silyl)palladium(II) complex (i)
may be initially formed by oxidative addition of the
SiꢀB bond of 1 onto the palladium(0) complex. The
activation of the SiꢀB bond is followed by the forma-
tion of ii with coordination of allenes. Subsequently,
migratory insertion of more electron-deficient CꢁC
bond may take place. As we have proposed for many
silaboration reactions using group 10 metal complexes,
the CꢁC bond may preferentially be inserted into the
PdꢀB bond rather than the PdꢀSi bond [4–8]. Thus,
selective BꢀC bond formation may proceed at the sp
carbon of allene to give s-allylic palladium intermedi-
ate iii, in which the silyl group and the allylic carbon
are located in a trans fashion. Intermediate iii is rapidly
converted to the corresponding p-allylic palladium in-
termediate iv, which then undergoes facile reductive
elimination of the silicon and the carbon atom located
cis to the silyl group.
Scheme 7.
The proposed mechanism is interestingly compared
with that of Pd(PPh3)4-catalyzed reaction of cinnamyl
acetate with hexamethyldisilane, in which a closely
related (organosilyl)(p-allyl)palladium(II) intermediate
may be involved [17]. The reaction exclusively provides
(E)-1-phenyl-3-trimethylsilyl-1-propene, which arises
from reductive elimination at the terminal allylic car-
bon. The highly contrasted regiochemistry may indicate
that the reductive elimination of the SiꢀC bond is so
facile that the regioselectivity of the SiꢀC bond forma-
tion is determined by the configuration of the primarily
formed (organosilyl)(p-allyl)palladium intermediate
Scheme 8.
2.5. Mechanism
A regiochemical trend of the silaboration reaction of
allenes can be summarized as follows: (1) the boryl
group is generally attached to the central (sp) carbon of
the allenes and (2) the silyl group is preferentially
prior to
a possible cis-trans equilibrium of the
intermediate.

408
M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
Although it is still difficult to explain the formation
phosphite ligands. The reactions generally proceeded
with highly regioselective BꢀC bond formation at the
central sp carbon of the allene. Furthermore, the silabo-
ration of the terminal allenes proceeded with highly
regioselective SiꢀC bond formation either at the termi-
nal or internal carbon atom of the allene. Exclusive
internal addition took place for the terminal allenes
with electrondonating substituents such as methoxy and
alkyl groups, while terminal addition is preferred in the
reactions of the allenes with electronegative groups
such as perfluoroalkyl group. A platinum-catalyst was
also found to catalyze the silaboration of the terminal
allene in much inferior yield than the palladium catalyst
but with opposite regioselectivity, i.e. the terminal
addition.
A mechanism of the silaboration reaction has not
been clarified yet. However, insertion of less substituted
CꢁC bond of the terminal allenes into the BꢀPd of i
may be involved in the catalytic cycle, resulting in the
observed regioselective BꢀC bond formation at the
central carbon of the allene.
As shown in some examples, the 2-borylallylsilanes
prepared by the silaboration of allenes may serve as a
useful building block in synthetic organic chemistry.
of the minor regioisomers in the reactions of the termi-
nal allenes with bulky substituents, they may be formed
through cis-trans isomerization of iii as well as iv
followed by reductive elimination at the less substituted
allylic carbon.
2.6. Synthetic application
The silaboration products, which possess vinylic bo-
ryl as well as allylic silyl moiety, are widely utilized in
organic synthesis for carbon-carbon bond formation. A
series of the silaboration products served as useful
precursors for the synthesis of 2-arylallylsilanes. For
instance, selective replacement of the boryl group by
phenyl group took place, giving dimethylphenyl(2-
phenylallyl)silane (14a) in 75% yield (Scheme 9) [18].
On the other hand, the silaboration products could
also be utilized for the synthesis of 2-boryl p-allylpalla-
dium complexes, which may be otherwise inaccessible.
Treatment of 3a with PdCl2(CH3CN)2 in MeOH at
room temperature gave 2-boryl substituted p-allylpalla-
dium chloride dimer 15a in 97% yield (Scheme 10).
Similar quantitative formations of p-allylpalladium
complexes were also observed in the reactions of 3j and
8 with PdCl2(CH3CN)2 in MeOH, although the corre-
sponding products 15b and 15c could not be purified so
as to give satisfactory elemental analysis.
4. Experimental
1H, 13C, and 19F-NMR spectra were recorded on a
Varian Gemini 2000 spectrometer (7.0 T magnet) at
ambient temperature. 11B NMR spectra were recorded
on a JEOL JNM-GX400 spectrometer (9.3 T magnet)
3. Conclusion
1
at ambient temperature. H-NMR data are reported as
Regioselective additions of the SiꢀB bond of silylbo-
rane to allenes were effectively catalyzed by various
palladium complexes with isonitrile, phosphine, and
follows: chemical shift in ppm downfield from
tetramethylsilane (l scale), multiplicity (sꢁsinglet,
dꢁdoublet, tꢁtriplet, qꢁquartet, and mꢁmultiplet), cou-
pling constant (Hz), and integration. 13C-NMR chemi-
cal shifts are reported in ppm downfield from
tetramethylsilane (l scale). All 13C-NMR spectra were
obtained with complete proton decoupling. 11B-NMR
chemical shifts are reported in ppm downfield from
BF3·OEt2 (l scale). 19F-NMR chemical shifts are re-
ported in ppm downfield from CFCl3 (l scale). IR
spectra were obtained on a Hitachi 270-30 spectrome-
ter. High resolution mass spectra were recorded on a
JEOL JMS-SX102A spectrometer.
Scheme 9.
Solvents were distilled from the indicated drying
agents: octane (CaH2); DME (LiAlH4); DMF (CaH2);
MeOH (MgOMe); 1,2-dichloroethane (CaH2).
2a, 2b, 2d, 2f, 2g, 2h [19], 2c [20], 2e [21], 2I [22], 7,
9[23], 12a, 12b [24], Pd(PPh3)4 [25], PdCl2(PPh3)2 [26],
Cp(allyl)Pd [27], and PdCl2(CH3CN)2 [28] were pre-
pared by the literature methods. Isonitriles were pre-
pared by dehydration of the corresponding formamides
with POCl3 in the presence of triethylamine [29].
1,1,3,3-Tetramethylbutyl isocyanide (Aldrich) and 2,6-
Scheme 10.

M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
409
dimethylphenyl isocyanide (Aldrich) were also obtained
from the indicated commercial source. Triphenylphos-
phine (Wako), dimethylphenylphosphine (Aldrich),
2.60–2.72 (m, 4H), 5.90 (t, J=6.9 Hz, 1H), 7.15–7.42
(m, 8H), 7.46–7.57 (m, 2H); 13C-NMR (CDCl3) l
−3.2, 24.8, 29.6, 32.9, 36.8, 82.8, 125.6, 127.6, 128.2,
128.6, 128.7, 133.9, 139.7, 142.6, 144.6; IR (neat) 2984,
methyldiphenylphosphine
(Aldrich),
cyclohexyldi-
phenylphosphine (Strem), tributylphosphine (Wako),
and triethylphosphite (Nacalai) were purchased and
purified by distillation or recrystallization before use.
1,2-Propadiene (2j, Oakwood Products), 3-methyl-1,2-
butadiene (5, Aldrich), dppe (Kanto), dppb (Kanto)
and Pd(acac)2 (Mitsuwa) were used as received.
All reactions were carried out under an argon or
nitrogen atmosphere.
1624, 1406, 1146 cm−1
.
HRFABMS Calc. for
C25H36BO2Si (M+1): 407.2576. Found: 407.2573. The
geometry was determined by an NOE between protons
at 1 and 3 positions.
4.4. Synthesis of 3-(dimethylphenylsilyl)-
2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-
heptene (3b)
4.1. General procedure for the silaboration of allenes
The title compound was prepared by the general
procedure. H-NMR (CDCl3) l 0.23 (s, 3H), 0.27 (s,
1
A solution of Pd(acac)2 (2.3 mg, 0.0076 mmol) and
2,6-dimethylphenyl isocyanide (4.0 mg, 0.031 mmol) in
octane (0.2 ml) was heated at 120°C for 30 s with
stirring and then cooled to room temperature. To the
red solution were added 1 (100 mg, 0.38 mmol) and
allene (0.58 mmol) at room temperature. The mixture
was heated at the indicated temperature with stirring.
After cooling to room temperature, the mixture was
subjected to bulb-to-bulb distillation to afford silabora-
tion product.
3H), 0.80 (t, J=6.9 Hz, 3H), 0.98–1.82 (m, 4H), 1.19
(s, 12H), 1.20–1.34 (m, 1H), 1.37–1.51 (m, 1H), 2.06
(dd, J=3.6, 11.7 Hz, 1H), 5.36 (d, J=3.0 Hz, 1H),
5.81 (d, J=3.0 Hz, 1H), 7.30–7.41 (m, 3H), 7.49–7.55
(m, 2H); 13C-NMR (CDCl3) l −5.2, −3.9, 13.9, 22.4,
24.6, 28.2, 31.1, 33.4, 83.1, 126.8, 127.5, 128.7, 134.3,
138.8; IR (neat) 2968, 1600, 1308, 1144 cm−1. Anal.
Calc. for C21H35BO2Si: C, 70.38; H, 9.84. Found: C,
70.11; H, 9.71%.
4.5. Synthesis of ethyl 3-(dimethylphenylsilyl)-4-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-
pentenoate (3c)
4.2. Synthesis of 3-(dimethylphenylsilyl)-5-phenyl-2-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-pentene
(3a)
The title compound was prepared by the general
1
The title compound was prepared by the general
procedure. H-NMR (CDCl3) l 0.23 (s, 3H), 0.27 (s,
procedure. H-NMR (CDCl3) l 0.27 (s, 3H), 0.28 (s,
1
3H), 1.16 (t, J=7.2 Hz, 3H), 1.20 (s, 6H), 1.21 (s, 6H),
2.33–2.45 (m, 1H), 2.58–2.70 (m, 2H), 3.91–4.12 (m,
2H), 5.36 (d, J=2.4 Hz, 1H), 5.79 (d, J=2.4 Hz, 1H),
7.28–7.38 (m, 3H), 7.45–7.55 (m, 2H); 13C-NMR
(CDCl3) l −5.5, −4.0, 14.1, 24.6, 24.7, 29.8, 34.4,
60.0, 83.3, 127.2, 127.6, 129.1, 134.3, 137.3, 173.4; IR
(neat) 2988, 1738, 1604, 1142, 702 cm−1. Anal. Calc.
for C21H33BO4Si: C, 64.94; H, 8.56. Found: C, 64.87;
H, 8.80%.
3H), 1.22 (s, 12H), 1.71–1.82 (m, 1H), 1.89–2.06 (m,
1H), 2.14 (dd, J=3.3, 12.0 Hz, 1H), 2.32–2.42 (m,
1H), 2.64–2.74 (m, 1H), 5.45 (d, J=3.0 Hz, 1H), 5.92
(d, J=3.0 Hz, 1H), 7.08–7.35 (m, 8H), 7.46–7.49 (m,
2H); 13C-NMR (CDCl3) l −5.3, −3.9, 24.7, 30.9,
33.4, 35.2, 83.3, 125.5, 127.3, 127.5, 128.2, 128.6, 128.8,
134.3, 138.4, 143.1; 11B-NMR (CDCl3) l 30.0; IR (neat)
3036, 1604, 1310, 1112, 736 cm−1. Anal. Calc. for
C25H35BO2Si: C, 73.88; H, 8.68. Found: C, 73.71; H,
8.88%.
4.6. Synthesis of 3-cyclohexyl-3-(dimethylphenylsilyl)-
2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-
propene (3d)
4.3. Synthesis of (E)-1-(dimethylphenylsilyl)-
5-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)-2-pentene (4a)
The title compound was prepared by the general
1
procedure. H-NMR (CDCl3) l 0.20 (s, 3H), 0.37 (s,
The title compound was prepared by platinum-cata-
lyzed silaboration of 2a (Scheme 2). A mixture of
Pt(CH2ꢁCH2)(PPh3)2 (5.7 mg, 7.6×10−3 mmol), 1 (101
mg, 0.38 mmol), and 2a (85 mg, 0.59 mmol) in octane
(0.1 mL) was heated at 120°C for 3 h with stirring.
After evaporation of volatile materials, resultant
residue was subjected to preparative TLC (hexane/
ether=19/1) to give 4a (16 mg, 10%). 1H-NMR
(CDCl3) l 0.21 (s, 6H), 1.20 (s, 12H), 1.81 (s, 2H),
3H), 0.69–0.88 (m, 2H), 0.95–1.41 (m, 3H), 1.23 (s,
12H), 1.47–1.83 (m, 6H), 1.97 (d, J=10.2 Hz, 1H),
5.43 (d, J=3.3 Hz, 1H), 5.79 (d, J=3.3 Hz, 1H),
7.25–7.40 (m, 3H), 7.45–7.60 (m, 2H); 13C-NMR
(CDCl3) l −3.8, −1.3, 24.5, 24.7, 26.5, 26.6, 33.5,
34.2, 38.9, 41.5, 83.2, 127.4, 127.6, 128.3, 134.1, 140.9;
IR (neat) 2932, 1602, 1308, 1146 cm−1. Anal. Calc. for
C23H37BO2Si: C, 71.86; H, 9.70. Found: C, 71.64; H,
9.63%.

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M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
4.7. Synthesis of (E)-1-cyclohexyl-3-(dimethylphenyl-
silyl)-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-
propene (4d)
2988, 1600, 1374, 1142 cm−1
. Anal. Calc. for
C23H31BO2Si: C, 73.01; H, 8.26. Found: C, 72.89; H,
8.51%. No NOE was observed for the protons at 1 and 3
positions.
The title compound was prepared by use of t-Oc-NC/
Pd(acac)2 (1/15) as a catalyst (Table 1; entry 10) and sep-
arated from 3d by HPLC (silica gel). H-NMR (CDCl3)
4.11. Synthesis of 3-(dimethylphenylsilyl)-3-
(4-methoxyphenyl)-2-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)-1-propene (3g)
1
l 0.24 (s, 6H), 0.87–1.07 (m, 2H), 1.07–1.36 (m, 2H),
1.19 (s, 12H), 1.56–1.72 (m, 6H), 1.78 (s, 2H), 2.60–2.73
(m, 1H), 5.63 (d, J=9.3 Hz, 1H), 7.30–7.35 (m, 3H),
7.48–7.54 (m, 2H); 13C-NMR (CDCl3) l −3.3, 24.3,
24.8, 25.9, 26.0, 34.0, 39.4, 82.7, 127.5, 128.7, 133.9,
The title compound was prepared by the general pro-
1
cedure. H-NMR (CDCl3) l 0.27 (s, 3H), 0.30 (s, 3H),
1.15 (s, 3H), 1.17 (s, 6H), 3.48 (s, 1H), 3.76 (s, 3H), 5.61
(d, J=2.4 Hz, 1H), 5.84 (d, J=2.4 Hz, 1H), 6.69–6.80
(m, 2H), 6.97–7.04 (m, 2H), 7.21–7.35 (m, 3H), 7.38–
7.44 (m, 2H); 13C-NMR (CDCl3) l −3.5, −3.0, 24.6,
24.7, 41.1, 55.1, 83.5, 113.3, 127.4, 128.7, 128.8, 130.1,
134.5, 134.8, 138.4, 157.2; IR (neat) 3076, 1610, 1514,
1250 cm−1. Anal. Calc. for C24H33BO3Si: C, 70.58; H,
8.14. Found: C, 70.34; H, 8.26%.
139.8, 151.7; IR (neat) 2936, 1624, 1146, 836 cm−1
.
Anal. Calc. for C23H37BO2Si: C, 71.86; H, 9.70. Found:
C, 71.85; H, 9.90%. The geometry was determined by an
NOE between protons at 1 and 3 positions.
4.8. Synthesis of 4,4-dimethyl-3-(dimethylphenyl-
silyl)-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-
1-pentene (3e)
4.12. Synthesis of 3-(dimethylphenylsilyl)-2-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)-3-
(4-trifluoromethylphenyl)-1-propene (3h)
The title compound was prepared by the general pro-
1
cedure. H-NMR (CDCl3) l 0.28 (s, 3H), 0.45 (broad s,
3H), 0.89 (s, 9H), 1.20 (s, 12H), 2.15 (broad s, 1H), 5.56
(broad s, 1H), 5.89 (broad s, 1H), 7.26–7.32 (m, 3H),
7.50–7.58 (m, 2H); 13C-NMR (CDCl3) l −0.7, −0.4,
24.5, 31.1, 34.9, 83.3, 127.4, 128.2, 131.0, 134.2, 141.8;
IR (neat) 2980, 1604, 1308, 1136 cm−1. HRMS Calc. for
C21H35BO2Si: 358.2497. Found: 358.2495.
The title compound was prepared by the general pro-
cedure. The regioisomers 3h and 4h were separated by
1
silica gel HPLC. H-NMR (CDCl3) l 0.29 (s, 3H), 0.31
(s, 3H), 1.15 (s, 6H), 1.18 (s, 6H), 3.59 (s, 1H), 5.66 (d,
J=2.4 Hz, 1H), 5.92 (d, J=2.4 Hz, 1H), 7.16 (d, J=8.1
Hz, 2H), 7.25–7.44 (m, 7H); 13C-NMR (CDCl3) l −3.5,
−3.4, 24.57, 24.62, 42.7, 83.7, 124.7 (q, J=3.5 Hz),
127.0 (q, J=32.3 Hz), 127.6, 128.2, 129.05, 129.15,
130.0, 134.4, 137.6, 147.2; IR (neat) 2936, 1620, 1326,
1126 cm−1. Anal. Calc. for C24H30BF3O2Si: C, 64.58; H,
6.77. Found: C, 64.65; H, 6.74%.
4.9. Synthesis of 3-(dimethylphenylsilyl)-3-phenyl-2-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-propene
(3f)
The title compound was prepared by the general pro-
cedure and separated from 4f by HPLC. 1H-NMR
(CDCl3) l 0.27 (s, 3H), 0.31 (s, 3H), 1.15 (s, 6H), 1.17 (s,
6H), 3.55 (s, 1H), 5.66 (d, J=2.7 Hz, 1H), 5.88 (d, J=
2.7 Hz, 1H), 7.04–7.15 (m, 3H), 7.15–7.22 (m, 2H),
7.24–7.39 (m, 3H), 7.39–7.44 (m, 2H); 13C-NMR
(CDCl3) l −3.5, −3.1, 24.56, 24.62, 42.2, 83.5, 124.8,
127.4, 127.9, 128.9, 129.1, 134.5, 138.3, 142.7; IR (neat)
4.13. Synthesis of 3-(dimethylphenylsilyl)-2-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-
(4-trifluoromethylphenyl)-1-propene (4h)
The title compound was prepared by the general pro-
1
cedure. H-NMR (CDCl3) l 0.21 (s, 6H), 1.27 (s, 12H),
2.28 (s, 2H), 7.09 (s, 1H), 7.23–7.34 (m, 5H), 7.38–7.48
(m, 4H); 13C-NMR (CDCl3) l −2.6, 19.7, 24.8, 83.7,
124.3 (q, J=270.9 Hz), 125.0 (q, J=3.5 Hz), 127.7, 128.3
(q, J=32.3 Hz), 129.0, 133.7, 137.5, 138.9, 142.1; IR
(neat) 2988, 1612, 1326, 1126 cm−1. Anal. Calc. for
C24H30BF3O2Si: C, 64.58; H, 6.77. Found: C, 64.33; H,
6.74%. No NOE was observed for the protons at 1 and 3
positions.
2988, 1602, 1252, 704 cm−1
.
Anal. Calc. for
C23H31BO2Si: C, 73.01; H, 8.26. Found: C, 72.85; H,
8.54%.
4.10. Synthesis of 3-(dimethylphenylsilyl)-1-phenyl-2-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-propene
(4f)
The title compound was isolated from a mixture of 3f
and 4f (86:14) by HPLC (Table 1; entry 26). H-NMR
(CDCl3) l 0.19 (s, 6H), 1.24 (s, 12H), 2.31 (s, 2H), 7.12
(s, 1H), 7.12–7.33 (m, 8H), 7.44–7.50 (m, 2H); 13C-
NMR (CDCl3) l −2.5, 19.2, 24.8, 83.5, 126.7, 127.7,
128.1, 128.8, 129.0, 133.8, 138.6, 139.3, 139.5; IR (neat)
4.14. Synthesis of 3-(dimethylphenylsilyl)-3-methoxy-
2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-
propene (3i)
1
The title compound was prepared by the general pro-
cedure. 1H-NMR (CDCl3) l 0.25 (s, 3H), 0.28 (s,

M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
411
3H), 1.15 (s, 6H), 1.17 (s, 6H), 3.25 (s, 3H), 3.97 (t, J=
1.2 Hz, 1H), 5.69 (dd, J=1.2, 3.6 Hz, 1H), 5.88 (dd,
J=1.2, 3.6 Hz, 1H), 7.30–7.37 (m, 3H), 7.54–7.63 (m,
2H); 13C-NMR (CDCl3) l −6.0, −5.1, 24.7, 58.4, 78.3,
83.3, 126.4, 127.6, 129.0, 134.5, 137.5; IR (neat) 2988,
1604, 1314, 1144, 736 cm−1. Anal. Calc. for C18H29-
BO3Si: C, 65.06; H, 8.80. Found: C, 65.23; H, 8.95%.
1H), 1.20–1.40 (m, 4H), 1.21 (s, 6H), 1.22 (s, 6H), 1.72–
2.09 (m, 3H), 2.22 (dd, J=3.3, 12.0 Hz, 1H), 6.22 (t,
J=6.9 Hz, 1H), 7.30–7.36 (m, 3H), 7.48–7.57 (m, 2H);
13C-NMR (CDCl3) l −4.3, −3.3, 13.8, 14.1, 22.3,
22.9, 24.3, 24.9, 29.7, 30.7, 31.1, 82.6, 127.5, 128.5,
134.1, 140.1, 144.8; IR (neat) 2968, 1608, 1376, 1140
cm−1. Anal. Calc. for C23H39BO2Si: C, 71.48; H, 10.17.
Found: C, 71.42; H, 10.25%. No NOE was observed for
the protons at 4 and 6 positions.
4.15. Synthesis of 3-(dimethylphenylsilyl)-2-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)-1-propene (3j)
4.19. Reaction of 9 with 1 (Scheme 5)
The reaction was carried out under an atmosphere of
propadiene (1 atm). H-NMR (CDCl3) l 0.27 (s, 6H),
1
According to the general procedure, 9 (83 mg, 0.50
mmol) was reacted with 1 (98 mg, 0.37 mmol) in the
presence of Pd(acac)2 (2.3 mg, 7.6×10−3 mmol) with
Xy-NC (4.0 mg, 0.031 mmol) in octane. After 2 h, the
mixture was subjected to bulb-to-bulb distillation to
give a mixture of 10 and 11 (141.1 mg, 88%). The re-
gioisomeric ratio of 44:32:20:4 for (E)-10, (E)-11, (Z)-
1.20 (s, 12H), 1.92 (s, 2H), 5.38 (d, J=3.3 Hz, 1H), 5.67
(d, J=3.3 Hz, 1H), 7.31–7.57 (m, 5H); 13C-NMR
(CDCl3) l −3.4, 24.1, 24.7, 83.4, 127.6, 128.8, 133.9,
139.3; IR (neat) 2988, 1608, 1312, 1146 cm−1. Anal.
Calc. for C17H27BO2Si: C, 67.55; H, 9.00. Found: C,
67.31; H, 9.21%.
1
10, and (Z)-11 was determined by H-NMR with the
4.16. Synthesis of 3-(dimethylphenylsilyl)-3-methyl-2-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-butene
(6)
vinylic signals at 5.30 (d, J=9.3 Hz), 5.82 (t, J=7.5
Hz), 6.00 (d, J=9.8 Hz), and 6.17 (t, J=6.0 Hz), re-
spectively. The geometry was assumed by NOE experi-
ments. A mixture of (Z)-10 and (Z)-11 was separated
from a mixture of (E)-10 and (E)-11 by HPLC and sub-
jected to the elemental analysis. Anal. Calc. for
C26H43BO2Si: C, 73.22; H, 10.16. Found: C, 72.92; H,
10.39%.
The title compound was prepared by use of PdCl2-
1
(PPh3)2 as a catalyst (Scheme 3). H-NMR (CDCl3) l
0.28 (s, 6H), 1.12 (s, 6H), 1.20 (s, 12H), 5.29 (d, J=2.4
Hz, 1H), 5.74 (d, J=2.4 Hz, 1H), 7.29–7.51 (m, 5H);
13C NMR (CDCl3) l −5.3, 24.2, 24.6, 28.5, 83.0, 125.9,
127.3, 128.7, 134.9, 138.0; IR (neat) 2936, 1582, 1302,
1146 cm−1. Anal. Calc. for C19H31BO2Si: C, 69.08; H,
9.46. Found: C, 68.80; H, 9.68%.
4.20. Synthesis of 1-(dimethylphenylsilyl)-
4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluoro-2-(4,4,5,5-tetra-
methyl-1,3,2-dioxaborolan-2-yl)-2-nonene (13a)
4.17. Synthesis of (E)-6-(dimethylphenylsilyl)-5-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-nonene
((E)–8)
The title compound was prepared by the general pro-
1
cedure. H-NMR (CDCl3) l 0.31 (s, 6H), 1.19 (s, 12H),
2.27 (t, J=3.6 Hz, 2H), 6.03 (t, J=16.5 Hz, 1H), 7.31–
7.39 (m, 3H), 7.48–7.58 (m, 2H); 13C-NMR (CDCl3) l
−2.8, 21.7, 24.6, 84.4, 122.0 (t, J=21.3 Hz), 127.7,
129.1, 133.8, 138.5; 19F-NMR (CDCl3) l −81.4,
−106.5, −122.2, −123.4, −123.9, −126.7; IR (neat)
2992, 1630, 1240, 1144, 836 cm−1. Anal. Calc. for
C23H26BF13O2Si: C, 44.53; H, 4.23. Found: C, 44.33; H,
4.12%. No NOE was observed for the protons at 1 and 3
positions.
The title compound was prepared by the general pro-
cedure. The stereoisomers (E)-8 and (Z)-8 were sepa-
1
rated by silica gel HPLC. H-NMR (CDCl3) l 0.22 (s,
3H), 0.27 (s, 3H), 0.78 (t, J=7.2 Hz, 3H), 0.86 (t, J=
7.2 Hz, 3H), 1.01–1.21 (m, 2H), 1.21 (s, 12H), 1.23–
1.45 (m, 4H), 1.97 (dd, J=3.3, 11.7 Hz, 1H), 2.29 (q,
J=7.5 Hz, 2H), 5.75 (t, J=7.8 Hz, 1H), 7.30–7.36 (m,
3H), 7.47–7.55 (m, 2H); 13C-NMR (CDCl3) l −4.9,
−3.3, 13.6, 13.7, 21.9, 23.5, 24.7, 24.8, 31.6, 33.2, 33.7,
82.6, 127.4, 128.5, 134.3, 139.7, 144.0; 11B-NMR
(CDCl3) l 30.4; IR (neat) 2968, 1620, 1408, 1144 cm−1
.
4.21. Synthesis of (E)-4-(dimethylphenylsilyl)-7,7,8,8,9,-
9,10,10,11,11,12,12,12-tridecafluoro-5-(4,4,5,5-tetra-
methyl-1,3,2-dioxaborolan-2-yl)-5-dodecene (13b)
Anal. Calc. for C23H39BO2Si: C, 71.48; H, 10.17. Found:
C, 71.49; H, 10.39%. The geometry was determined by
an NOE between protons at 4 and 6 positions.
The title compound was prepared by the general pro-
1
4.18. Synthesis of (Z)–6-(dimethylphenylsilyl)-5-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-nonene
((Z)-8)
cedure. H-NMR (CDCl3) l 0.30 (s, 3H), 0.37 (s, 3H),
0.80 (t, J=6.9 Hz, 3H), 1.03–1.25 (m, 2H), 1.24 (s, 6H),
1.25 (s, 6H), 1.40–1.56 (m, 2H), 2.03–2.10 (m, 1H), 5.49
(t, J=14.4 Hz, 1H), 7.28–7.41 (m, 3H), 7.47–7.57 (m,
2H); 19F-NMR (CDCl3) l −81.4, −106.7, −122.4, −
123.0, −123.4, −126.7; IR (neat) 2968, 1630, 1242,
1H-NMR (CDCl3) l 0.20 (s, 3H), 0.34 (s, 3H), 0.77 (t,
J=6.9 Hz, 3H), 0.85 (t, J=7.2 Hz, 3H), 0.90–1.08 (m,

412
M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
1144 cm−1. Anal. Calc. for C26H32BF13O2Si: C, 47.14;
H, 4.87. Found: C, 47.25; H, 4.92%. The geometry was
determined by an NOE between the protons at 4 and 6
positions.
2.30 (d, J=1.2 Hz, 2H), 2.31 (s, 3H), 4.81 (m, 1H),
5.12 (d, J=1.5 Hz, 1H), 7.03–7.15 (m, 2H), 7.24–7.62
(m, 7H); 13C-NMR (acetone-d6) l 2.7, 21.0, 25.5, 110.4,
127.2, 127.3, 128.6, 129.7, 129.9, 134.5, 139.8, 140.6,
147.0; IR (neat) 2968, 1612, 1252, 1116 cm−1. HRMS
Calc. for C18H22Si: 266.1491. Found: 266.1482.
4.22. Competiti6e silaboration of 2b and 7
A solution of Pd(acac)2 (0.58 mg, 1.9×10−3 mmol)
and 2,6-dimethylphenyl isocyanide (1.0 mg, 7.6×10−3
mmol) in octane (0.1 ml) was heated at 120°C for 30 s
with stirring. To the red solution were added 1 (25 mg,
0.095 mmol), 2b (14 mg, 0.14 mmol), and 7 (18 mg,
0.14 mmol) at room temperature. The mixture was
heated at 120°C for 2 h with stirring. After evaporation
of the solvent, the mixture was analyzed by H-NMR,
which showed the major formation of 3a and a trace
amount of 8 (\50:1).
4.27. Synthesis of 2-(4-cyanophenyl)-3-
(dimethylphenylsilyl)-1-propene (14c)
The title compound was prepared by the general
1
procedure (4.6.1.). H-NMR (CDCl3) l 0.18 (s, 6H),
2.23 (s, 2H), 4.97 (d, J=1.2 Hz, 1H), 5.20 (d, J=1.2
Hz, 1H), 7.25–7.43 (m, 7H), 7.47–7.53 (m, 2H);
13C-NMR (CDCl3) l −3.2, 25.0, 110.7, 113.6, 119.0,
127.0, 127.8, 129.2, 131.9, 133.5, 138.0, 144.7, 147.1; IR
(neat) 2968, 2232, 1608, 1116 cm−1. HRMS Calc. for
C18H19NSi: 277.1287. Found: 277.1290.
1
4.23. Competiti6e silaboration of 2b and 12a
4.28. Synthesis of y-allylpalladium complexes 15
By using Pd(acac)2 (0.58 mg, 1.9×10−3 mmol), 2,6-
dimethylphenyl isocyanide (1.0 mg, 7.6×10−3 mmol),
1 (25 mg, 0.095 mmol), 2b (14 mg, 0.14 mmol), and 12b
(51 mg, 0.14 mmol), the title experiment was carried
out under a condition similar to that for the competi-
tive silaboration of 2a and 7. A 1H-NMR analysis
showed the formation of 3a and 13a in 12:88 ratio.
To a solution of 3a (111 mg, 0.27 mmol) in MeOH (2
ml) was added PdCl2(CH3CN)2 (73 mg, 0.28 mmol)
under nitrogen. The orange suspension was stirred at
room temperature for 12 h. Yellow precipitates were
collected by filtration and washed with MeOH several
times. After drying in vacuo, pale yellow powder (110
1
mg, 97%) was obtained. 15a: H-NMR (CDCl3) l 1.30
4.24. General procedure for the cross-coupling of 3j
with aryl iodide
(s, 24H), 2.04–2.17 (m, 2H), 2.23–2.36 (m, 2H),
2.78–2.92 (m, 6H), 3.82 (dd, J=5.7, 8.4 Hz, 2H), 4.14
(s, 2H), 7.15–7.30 (m, 10H); 13C-NMR (CDCl3) l 24.5,
24.7, 33.6, 35.6, 65.1, 84.3, 90.7, 125.9, 128.3, 128.7,
141.6; 11B-NMR (CDCl3) l 28.7; IR (neat) 3468, 2980,
1602, 1142, 858 cm−1. Anal. Calc. for C34H48B2Cl2-
O4Pd2: C, 49.43; H, 5.86. Found: C, 49.60; H, 5.82%.
Related complexes 15b and 15c were prepared by the
same procedure, although they were identified only by
To a mixture of Pd(PPh3)4 (6.1 mg, 5.0×10−3
mmol) and Ba(OH)2·8H2O (78 mg, 0.25 mmol) in
dimethoxyethane/water (0.9 ml/0.15 ml) under nitrogen
were added aryl iodide (0.25 mmol) and 3j (50 mg, 0.17
mmol) at room temperature. The mixture was heated at
100°C for 3 h with stirring. Extraction with ether
followed by column chromatography on silica gel af-
forded the corresponding allylsilane 14.
1
NMR. 15b: H-NMR (CDCl3) l 1.30 (s, 24H), 3.10 (s,
4H), 4.33 (s, 4H). 15c: 1H-NMR (CDCl3) l 0.89 (t,
J=7.0 Hz, 12H), 1.35 (s, 24H), 1.43–1.75 (m, 16H),
3.69 (t, J=7.0 Hz, 4H); 11B-NMR (CDCl3) l 29.0.
4.25. Synthesis of 2-phenyl-3-(dimethylphenylsilyl)-
1-propene (14a)
The title compound was prepared by the general
procedure (4.6.1.). 1H-NMR (acetone-d6) l 0.13 (s, 6H),
2.31 (s, 2H), 4.86 (d, J=1.8 Hz, 1H), 5.13 (d, J=1.8
Hz, 1H), 7.20–7.65 (m, 10H); 13C-NMR (acetone-d6) l
−2.8, 25.6, 111.2, 127.3, 128.3, 128.6, 129.1, 129.9,
134.5, 134.7, 139.6, 147.2; IR (neat) 2968, 1618, 1252,
1114 cm−1. HRMS Calc. for C17H20Si: 252.1334.
Found: 252.1323.
Acknowledgements
This study was supported by a Grant-in-Aid for
Scientific Research on Priority Areas, ‘The Chemistry
of Inter-element Linkage’ from the Ministry of
Education, Science, Sports, and Culture of Japan.
References
4.26. Synthesis of 2-(4-methylphenyl)-3-(dimethyl-
phenylsilyl)-1-propene (14b)
[1] I. Beletskaya, C. Moberg, Chem. Rev. 99 (1999) 3435.
[2] M. Suginome, Y. Ito, Chem. Rev. 100 (2000) 3221.
[3] (a) K.A. Horn, Chem. Rev. 95 (1995) 1317. (b) H.K. Sharma,
K.H. Pannell, Chem. Rev. 95 (1995) 1351.
The title compound was prepared by the general
procedure (4.6.1.). 1H-NMR (acetone-d6) l 0.14 (s, 6H),

M. Suginome et al. / Journal of Organometallic Chemistry 611 (2000) 403–413
413
[4] (a) M. Suginome, H. Nakamura, Y. Ito, Chem. Commun. (1996)
2777. (b) M. Suginome, T. Matsuda, H. Nakamura, Y. Ito,
Tetrahedron 55 (1999) 8787.
[5] M. Suginome, H. Nakamura, Y. Ito, Angew. Chem. Int. Ed.
Engl. 36 (1997) 2516.
silaboration of allenes appeared. S. Onozawa, Y. Hatanaka, M.
Tanaka, Chem. Commun. (1999) 1863.
[16] M. Suginome, Y. Ito, J. Chem. Soc. Dalton Trans. (1998) 1925.
[17] H. Urata, H. Suzuki, Y. Moro-oka, T. Ikawa, Bull. Chem. Soc.
Jpn. 57 (1984) 607.
[6] M. Suginome, T. Matsuda, T. Yoshimoto, Y. Ito, Org. Lett. 1
(1999) 1567.
[7] M. Suginome, T. Matsuda, Y. Ito, Organometallics 17 (1998)
5233.
[8] M. Suginome, H. Nakamura, T. Matsuda, Y. Ito, J. Am. Chem.
Soc. 120 (1998) 4248.
[9] For non-catalyzed reactions of silylboranes, see (a) J.D. Buynak,
B. Geng, Organometallics 14 (1995) 3112. (b) M. Suginome, T.
Fukuda, H. Nakamura, Y. Ito, Organometallics 19 (2000) 719.
[10] M. Suginome, Y. Ohmori, Y. Ito, The 76th Annual Meeting of
the Chemical Society of Japan, Abstract 1B635, Yokohama,
March 28–31, 1999.
[11] M. Suginome, Y. Ohmori, Y. Ito, Synlett (1999) 1567.
[12] H. Watanabe, M. Saito, N. Sutou, K. Kishimoto, J. Inose, Y.
Nagai, J. Organomet. Chem. 225 (1982) 343.
[13] (a) T.N. Mitchell, H. Killing, R. Dicke, R. Wickenkamp, J.
Chem. Soc., Chem. Commun (1985) 354.(b) T.N. Mitchell, U.
Schneider, J. Organomet. Chem. 407 (1991) 319.
[14] T. Ishiyama, T. Kitano, N. Miyaura, Tetrahedron Lett. 39
(1998) 2357.
[18] N. Miyaura, A. Suzuki, Chem. Rev. 95 (1995) 2457.
[19] J.-L. Moreau, M. Gaudemar, J. Organomet. Chem. 108 (1976)
159.
[20] S. Hoff, L. Brandsma, J.F. Arens, Recl. Trav. Chim. Pays-Bas
87 (1968) 916.
[21] P. Vermeer, J. Meijer, L. Brandsma, Recl. Trav. Chim. Pays-Bas
94 (1975) 112.
[22] T. Endo, K. Takagi, I. Tomita, Tetrahedron 53 (1997) 15187.
[23] S. Tsuboi, T. Masuda, S. Mimura, A. Takeda, Org. Synth. 66
(1987) 22.
[24] (a) M.-H. Hung, Tetrahedron Lett. 31 (1990) 3703. (b) D.J.
Burton, G.A. Hartgraves, J. Hsu, Tetrahedron Lett. 31 (1990)
3699.
[25] D.R. Coulson, Inorg. Synth. 13 (1972) 121.
[26] J.M. Jenkins, B.L. Shaw, J. Chem. Soc. (A) (1966) 770.
[27] Y. Tatsuno, T. Yoshida, S. Otsuka, Inorg. Synth. 19 (1979) 221.
[28] J.R. Doyle, P.E. Slade, H.B. Jonassen, Inorg. Synth. 6 (1960)
218.
[29] I. Ugi, U. Fetzer, U. Eholzer, H. Knupfer, K. Offermann,
Angew. Chem. 77 (1965) 492.
[15] Note that closely related paper that dealt with Pd-catalyzed
.