Hydrosilylation of aromatic aldehydes and ketones catalyzed by mono- and tri-nuclear platinum(0) complexes

Article abstract of DOI:10.1246/bcsj.20170397

Hydrosilylation of aromatic aldehydes and acetophenone with H2SiPh2 was studied by using Pt complexes as the catalyst. Reaction of aromatic aldehydes, such as PhCHO, 4-FC6H4CHO, 4-MeC6H4CHO and 4-CF3C6H4CHO with H2SiPh2 in the presence of [Pt(PPh3)3] cata

Full text of DOI:10.1246/bcsj.20170397

Advance Publication Cover Page
Hydrosilylation of Aromatic Aldehydes and Ketones Catalyzed by Mono- and Tri-nuclear
Platinum(0) Complexes
Yoshitaka Tsuchido, Ryota Abe, Megumi Kamono, Kimiya Tanaka, Makoto Tanabe, and Kohtaro Osakada*
Advance Publication on the web March 1, 2018
doi:10.1246/bcsj.20170397
© 2018 The Chemical Society of Japan
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Revised
Hydrosilylation of Aromatic Aldehydes and Ketones Catalyzed by Mono- and
Tri-nuclear Platinum(0) Complexes
Yoshitaka Tsuchido, Ryota Abe, Megumi Kamono, Kimiya Tanaka, Makoto Tanabe, and Kohtaro Osakada*
Laboratory for Chemistry and Life Science, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
E-mail: kosakada@res.titech.ac.jp
Kohtaro Osakada
Kohtaro Osakada received Ph.D. degree from The University of Tokyo in 1982. He was a research associate in 1982, an
associate professor in 1989, and has been a full professor since 1999, at Tokyo Institute of Technology. His current
research interest is organotransition metal chemistry.
Abstract
Hydrosilylation of aromatic aldehydes and acetophenone
catalyzed by [Pt(PPh3)3] complexes and comparison of the
results with those using the Pt3 complex as the catalyst.
with H2SiPh2 were studied by using Pt complexes as the
catalyst. Reaction of aromatic aldehydes, such as PhCHO,
4-FC6H4CHO, 4-MeC6H4CHO and 4-CF3C6H4CHO with
H2SiPh2 in the presence of [Pt(PPh3)3] catalyst proceeds
smoothly at room temperature with similar reaction rates. The
hydrosilylation of PhCHO with H2Si(C6H4-4-Me)2 proceeds
faster than that with H2SiPh2. Comparison of the reactions of
PhCHO with H2SiPh2 and with D2SiPh2 demonstrated a large
kinetic isotope effect (3.1). The hydrosilylation of the
aldehydes catalyzed by [Pt(PMe3)(μ-SiPh2)]3, reported in our
previous paper, shows large dependence of the reaction rate on
the aryl group of the substrate, in the order, 4-MeC6H4CHO >>
PhCHO = 4-FC6H4CHO > 4-CF3C6H4CHO. Hydrosilylation of
(3-vinyl)benzaldehyde and 10-undecenal in the presence of
[Pt(PPh3)3] catalyst occurs at the carbonyl group selectively to
form the corresponding alkoxysilanes. The hydrosilylation of
acetophenone with H2SiPh2 catalyzed by [Pt(PPh3)3] forms
1-phenylethyl(diphenylsilyl)ether, while the reaction using the
Pt3 catalyst is accompanied by dehydrosilylation to yield a
mixture of the saturated and unsaturated silyl ethers.
2. Results and Discussion
Hydrosilylation of PhCHO with H2SiPh2 was conducted
in the presence of a catalytic amount of [Pt(PPh3)3] ([PhCHO] :
[H2SiPh2] : [Pt] = 1.0 : 3.0 : 0.15) at 25 oC (Eq. 1).
1. Introduction
Hydrosilylation of carbonyl compounds such as
aldehydes and ketones provide silyl ethers, which are regarded
as synthetic equivalents of alcohols. Complexes of various late
transition metals such as Rh,1) Cu,2) Fe,3) and Ni,4) catalyze the
reaction. There have been only a limited number of reports on
the hydrosilylation of carbonyl compounds using Pt catalyst,
although molecular Pt complexes and Pt salts are known as the
efficient catalyst for hydrosilylation of olefins.5) Pt complex
catalyzes hydrosilylation of α,β-unsaturated aldehydes and
ketones, and accompanying isomerization to produce the silyl
enol ether.6) The hydrosilylation of aryl or aliphatic ketons
catalyzed by Pt complexes were reported by Kumada,7a),7b)
Trotter,7c) Vekki,7d) and Ruhland.7e)
Recently, we reported a triplatinum complex having
Figure 1. Reaction profile of (a) hydrosilylation of 4-XC6H4CHO
(X = -H, -CH3, -F, -CF3) with H2SiPh2 catalyzed by [Pt(PPh3)3]
(Inset, Arrhenius plot, X = H). Conditions: arylaldehyde (0.15
mmol), H2SiPh2 (0.44 mmol), [Pt(PPh3)3] (0.022 mmol), C6D6, 25
bridging
diarylsilylene
ligands,
form
[Pt3(PMe3)3(μ-SiPh2)2(μ-SiHPh2)2] reversibly. The equilibrated
mixture catalyzes hydrosilylation of PhCHO with H2SiPh2 to
yield the corresponding benzyl silyl ether.8) The hydrosilylation
of carbonyl compounds catalyzed by the platinum complexes is
still rare, which prompted us to investigate the hydrosilylation
of aldehydes catalyzed by common mononuclear Pt complexes.
This paper presents the hydrosilylation of aromatic aldehydes
oC;
(b)
hydrosilylation
of
PhCHO
with
H2SiPh2,
H2Si(C6H4-4-Me)2, and D2SiPh2 catalyzed by [Pt(PPh3)3].
Conditions: PhCHO (0.050 mmol), diarylsilane (0.25 mmol),
o
[Pt(PPh3)3] (0.0075 mmol), C6D6, 45 C. The yields were obtained
by 1H NMR signal intensity using dibenzyl as an internal standard.
The observed rate constants were described in experimental
section.

1
The H NMR spectra of the reaction mixture showed decrease
in the signals of SiH hydrogen of H2SiPh2 and aldehyde (5.08
and 9.65 ppm) and growth of new signals at 5.71 and 4.73 ppm,
which are assigned to PhCH2OSiHPh2 via hydrosilylation of the
aldehyde group. The reaction is almost completed within 46 h,
and forms the product quantitatively. Arylaldehydes with
para-substituents (X = -Me, -F, -CF3) also undergo the
hydrosilylation with H2SiPh2.
reaction (24 h), the signals of [Pt(PMe3)(μ-SiPh2)]3 (-26.6 ppm)
and minor uncharacterized complex (-18.4 and -68.4 ppm)
were observed. Thus, the reaction was catalyzed by the
trinuclear Pt complex rather than by its decomposition product.
The reaction rate clearly depends on the Pt complexes.
[Pt{O(SiMe2CH=CH2)}2] (Karstedt’s catalyst) completes the
hydrosilylation of PhCHO with H2SiPh2 within 15 min at 25 oC.
The reaction catalyzed by [Pt(PPh3)3] and [Pt(PMe3)4] requires
Figure 1a shows profiles of the reaction using the four
arylaldehydes as well as the curves obtained by assuming the
first-order reaction rates. The kinetic parameters of the reaction
of PhCHO were calculated from temperature dependence of the
rate constants, to be Ea = 24.0 kcal mol-1, ΔH‡ = 23.6 kcal mol-1,
ΔS‡ = -1.2 cal K-1 mol-1, and ΔG‡ = 23.9 kcal mol-1, respectively,
o
at 25 C. These kinetic parameters suggest that the catalysis
involves an intramolecular reaction, such as migratory insertion
of the coordinated carbonyl compound into the M-H or M-Si
bond, as the rate-determining step. The reaction rates of the
arylaldehydes decrease in the order of the substituents, -H ≥
-Me ≥ -CF3 ≥ -F, although their difference is small.
ca. 24
h
for completion, and that catalyzed by
[Pt(PMe3)(μ-SiPh2)]3 is completed after 72 h.
(3-Vinyl)benzaldehyde and 10-undecenal contain both
vinyl and formyl groups and reacts with H2SiPh2 in the
presence
of
[Pt(PPh3)3]
catalyst
to
yield
The hydrosilylation of PhCHO with H2Si(C6H4-4-Me)2 is
faster than that with H2SiPh2 in the presence of [Pt(PPh3)3]
catalyst. It suggests that aryl groups on the Si atom affected the
reaction rate of the hydrosilylation (Figure 1b). The reaction of
PhCHO with D2SiPh2 occurs more slowly (kD = 0.58 × 10-4 s-1)
than that with H2SiPh2 (kH = 1.79 × 10-4 s-1). The large kinetic
isotope effect (KIE = 3.1) is in the range of primary isotope
effect. It implies that the cleavage of Si-H/D bond is included
in the rate-determining step of this catalytic reaction.
H2C=CHC6H4CH2OSiHPh2 and H2C=CH(CH2)9OSiHPh2,
respectively, as the hydrosilylation products in a NMR scale
(Eq. 3, 4). The reaction mixture does not contain a product via
hydrosilylation of the vinyl group nor the double
hydrosilylation product. The former silyl ether was treated
In contrast, the hydrosilylation catalyzed by the trinuclear
complex, [Pt(PMe3)(μ-SiPh2)]3, differs in the reaction rate,
depending on the substituents in the order of 4-MeC6H4CHO
>> PhCHO = 4-FC6H4CHO > 4-CF3C6H4CHO (Figure 2).
The 31P{1H} NMR spectrum of the reaction of 4-MeC6H4CHO
with H2SiPh2 using the [Pt(PMe3)(μ-SiPh2)]3 as the catalyst
contains only the signals of [Pt3(PMe3)3(μ-SiPh2)2(μ-SiHPh2)2]
(-20.0 and -22.3 ppm) after 15 min. After completion of the
1
Figure 3. H NMR spectra (400 MHz, C6D6, 298 K) of the reaction
mixture of the hydrosilylation of PhCOCH3 (0.25 mmol for Pt1, 0.16
mmol for Pt3) with H2SiPh2 (0.25 mmol for Pt1, 0.17 mmol for Pt3) in
Figure 2. Reaction profile of hydrosilylation of 4-XC6H4CHO (X =
-H, -CH3, -F, -CF3) with H2SiPh2 catalyzed by Pt3 complex.
Conditions: arylaldehyde (0.13 mmol), H2SiPh2 (0.18 mmol),
o
catalyzed by (a) [Pt(PPh3)3] (0.022 mmol) at 60 C for 24 h and (b)
[Pt(PMe3)(μ-SiPh2)]3 (0.0074 mmol) at 60 oC for 54 h. The yields
were obtained by 1H NMR signal intensity using dibenzyl as an
internal standard.
o
[Pt(PMe3)(μ-SiPh2)]3 (0.0074 mmol), C6D6, 25 C. The yields were
1
obtained by H NMR signal intensity using dibenzyl as an internal
standard.

with NBu4F to afford H2C=CHC6H4CH2OH. The isolated
yield of the alcohol based on (3-vinyl)benzaldehyde) was 70%.
Isolation of the product of hydrosilylation of 10-undecenal as
well as its corresponding alcohol was not feasible. The
reactions of (3-vinyl)benzaldehyde with H2SiPh2 catalyzed by
[Pt(PMe3)(μ-SiPh2)]3 and by Karstedt’s catalyst also caused
selective hydrosilylation of the carbonyl group.9) The
hydrosilylation of styrene with H2SiPh2 was catalyzed by
Karstedt’s catalyst, while [Pt(PPh3)3] and [Pt(PMe3)(μ-SiPh2)]3
do not catalyze the reaction.
The reaction of PhCOCH3 with H2SiPh2 in the presence
of [Pt(PPh3)3] and [Pt(PMe3)(μ-SiPh2)]3 catalysts gave three
products, Ph(CH3)CHOSiHPh2 (A) via hydrosilylation,
Ph(CH2=)COSiHPh2
Ph(CH3)CHOSiPh2CH2CH(Ph)OSiHPh2 (C) via formal
dimerization of the above products, as shown in Eq. 5. Relative
yields of the products, determined by H NMR spectra of the
reaction mixture, differ largely depending on the catalysts
(Figure 3). The catalytic reaction by [Pt(PPh3)3] formed
compound A (4.95 and 5.67 ppm) as the major product (85%)
and small amounts of compound B (4.65, 4.89, 5.89 ppm) (2%)
and C (5.89 ppm) (7%). It is in contrast to the reaction
catalyzed by [Pt(PMe3)(μ-SiPh2)]3, which produces B as the
major product (45%).
(B)
via dehydrosilylation, and
Scheme 2. Mechanism involving insertion of C=O group into M-H
bond. 12) 13)
1
formation of the hydride(silyl)metal intermediate and
subsequent insertion of carbonyl group into the M-H bond, is
less common in the hydrosilylation of carbonyl compounds.13,
14)
Co(I) complex with a Cp* ligand undergoes oxidative
addition of diorgano(vinyl)silane to form Co(III) intermediate,
having hydride and silyl ligands and π-coordinated ketone
molecule. Insertion of C=O bond into the Co-H bond, forms
the intermediate having the silyl and alkoxide ligands, and
causes coupling of these ligands. The reaction is accompanied
by intramolecular hydrogen transfer of the product.
Two major mechanisms were proposed for hydrosilylation
of olefins catalyzed by Pt complexes.
The
hydride(silyl)platinum(II) complex, formed by oxidative
addition of silanes to a Pt(0) precursor, undergoes insertion of
olefin into the Pt-H bond (Chalk-Harrod mechanism).10)
Ensuing coupling of the silyl and alkyl ligands forms the
alkylsilane products. In the modified-Chalk-Harrod mechanism,
insertion of olefin occurs into the Pt-Si bond preferentially, and
induces reductive elimination of the product via coupling of the
2-silylethyl and hydride ligands.
More numbers of mechanisms were proposed for
hydrosilylation of carbonyl compounds catalyzed by late
transition metal complexes. Ojima et al achieved asymmetric
hydrosilylation of unsymmetrical ketones with secondary
silanes using Rh complex having bidentate chiral phosphines as
the catalyst. They compared the mechanism caused by insertion
of carbonyl group into the Rh-H bond (Chalk-Harrod-type) and
that involving insertion of C=O bond into the Rh-Si bond
(modified-Chalk-Harrod-type, Scheme 1), and chose the latter
because of better consistency with the results of asymmetric
induction.11) Prock and Giering also proposed the
modified-Chalk-Harrod-type mechanism and intermediacy of
the complex having a 1-phenyl(1-siloxy)ethyl ligand.11)
Mechanism that involves insertion of the C=O bond into
the metal hydride ligand was proposed for the hydrosilylation
of carbonyl compounds catalyzed by Cu(I)-H complexes as
well as Ni(II) and Fe(II) complexes having pincer-type ligands.
The catalyst precursor contains a hydride ligand and no
Si-ligands, and undergoes insertion of the carbonyl group into
the M-H bond to generate the intermediate having an alkoxo
ligand bonded to the metal. Further addition of organosilane
results in formation of the alkoxysilane product and regenerates
the hydride complex, as shown in Scheme 2.14)
Zheng and Chan reported hydrosilyl5tion reactions of
enones using [RhH(PPh3)4] catalyst, and proposed a new kind
of mechanism that involves coordination of carbonyl oxygen to
Si atom of the hydride(silyl)rhodium intermediate, forming an
intermediate having hypervalent Si center.16) (Scheme 3a)
Tridentate and tetradentate ligands occupy multiple
coordination sites, and the catalysis using the complexes of late
transition metal often prefers the intermediate, formed via the
reaction of uncoordinated carbonyl compounds with the
Si-ligand.
Cationic Ir(III) complex with a pincer-type P-C-P ligand
Chalk-Harrod-type mechanism that should involve
16)
Scheme 3. (a) Mechanism by Chan (catalyst, RhH(PPh3)4).
Scheme 1. Modified-Chalk-Harrod-type mechanism of
hydrosilylation of ketone. 11)
(b)
Mechanism
by
Brookhart
(catalyst,
[Ir(H)(acetone){(tBu2PO)2C6H3}][B(C6F5)4]). 17)

μ-η2-SiHPh2 ligands, which is probably the active species of
the catalysis. The complex contains two Si ligands that bridges
two Pt centers via silylene coordination mode with a terminal
hydride or μ-η2-SiHPh2 fashion. A possible pathway is shown
in Scheme 5a, in which the carbonyl oxygen is associated with
the Si atom and then undergoes Si-O bond formation. Coupling
of a hydride ligand and the siloxymethyl ligand releases the
product. The Pt centers are sterically congested, and external
attack of the carbonyl group to the silylene (or η2-silyl) ligand
is favored to form the new Si-O bond. In the reaction of
acetophenone, β-hydrogen abstraction yields the alkenyl silyl
ether. The reaction rate is influenced largely by substituents of
the aromatic aldehyde, and the rate-determining step of the
catalysis exists in the latter part of the catalytic cycle, C-H
bond formation.
For the reaction catalyzed by [Pt(PPh3)3], it is not easy to
assign the mechanism, unambiguously. A large KIE for the
reactions using H2SiPh2 and D2SiPh2, suggests that the
rete-determining step of the reaction resides in oxidative
addition of H2SiPh2 (or D2SiPh2) to Pt(0) complex, giving the
Pt(II) intermediate with hydride and silyl ligands or in insertion
of C=O group into the Pt-H bond in Chalk-Harrod-type
mechanism in Scheme 5b. Small influence of the aromatic
group of the aldehyde to the rate constants may be consistent
with the former.
Scheme 4. Mechanism via silylene intermediates
(catalyst, [Rh(nbd){(tBuC3H3NO)(C6H2Me3)(C3H2N)}]). 18)
catalyzes the hydrosilylation of ketones and esters.17) It
involves a reaction of uncoordinated carbonyl compounds with
a η1-silane ligand bonded to Ir as the Si-O bond-forming step.
The resulted cationic silylated ketone (or ester) abstracts
hydride from the complex to generate the silyl ether. The bond
forming reactions in the catalysis resemble to the
hydrosilylation of carbonyl compounds catalyzed by Lewis
acids such as B(C6F5)3 (Scheme 3b).
The hydrosilylation catalyzed by Rh complex having a
chelating NHC ligand was proposed to involve the intermediate
having a silylene ligand bonded to the metal center. The
silyl-metal intermediate undergoes α-hydrogen abstraction of
the silyl ligand, generating a silylene ligand, which reacts with
ketone to form a O-Si=M bond. A DFT study of the reaction
pathway indicated two intermediates, the complex with η2-silyl
ligand bonded via a Si-H bond (A) and the complex having
alkoxy-stabilized silylene ligand rather than those having a bare
silylene ligand (B) (Scheme 4).18) The reaction mechanism
based on the silylene intermediates was discussed in the
catalysis using Rh complex with a bis-NHC ligand.19, 20)
3. Conclusion
Both [Pt(PPh3)3] and [Pt(PMe3)(μ-SiPh2)]3 catalyze
hydrosilylation of aromatic aldehydes with H2SiPh2, although
there have been only a few number of the reaction catalyzed by
a Pt complex. Detailed studies of the reaction catalyzed by the
Pt1 and Pt3 complexes revealed quite different reaction results
depending on the catalysts. The rate of the reaction using the
former catalyst is influenced by the aromatic group of the
aldehyde less significantly than the latter. Hydrosilylation of
acetophenone with H2SiPh2 provided different products
depending on the catalysts; the reaction catalyzed by
[Pt(PMe3)(μ-SiPh2)]3 is accompanied by dehydrosilylation of
the substrate. A number of reaction mechanisms were proposed
for the hydrosilylation of carbonyl compounds catalyzed by
transition metal complexes. [Pt(PMe3)(μ-SiPh2)]3 catalysis
probably involves O-Si bond formation at the initial stage of
the reaction, followed by C-H bond formation, and the
[Pt(PPh3)3] catalysis is considered to proceed via insertion of
C=O bond into the Pt-H bond. Recently, Wei and Zhu found
Suzuki-Miyaura reaction catalyzed by triangular Pd3 complex,
Rh complexes with a N,Si,N-tridentated ligand, forming a
facial structure, also catalyzes hydrosilylation of carbonyl
compounds.
It
involves
initial
formation
of
hydrido(silyl)rhodium intermediate, and further reaction of the
carbonyl group of free ketone with the hydride ligand, to form
a mixture of the vinyl silyl ether and alkyl silyl ether.21)
The hydrosilylation reactions of aldehydes and ketone
catalyzed by [Pt(PPh3)3] in this study, and by
[Pt(PMe3)(μ-SiPh2)]3 also proceed smoothly. The Pt3 complex
reacts with H2SiPh2 to produce the Pt3Si4 complex having two
and revealed
a new reaction mechanism based on the
experimental and theoretical studies.22) The catalysis using
Scheme 5. Proposed mechanisms of hydrosilylation catalyzed by (a) [Pt(PMe3)(μ-SiPh2)]3 and (b) [Pt(PPh3)3].

multinuclear transition metal complexes will attract more
attention than before because of their unique pathways and
performance.
H2Si(C6H4-4-Me)2, and D2SiPh2 catalyzed by [Pt(PPh3)3]. To
a C6D6 solution (0.5 mL) of PhCHO (0.05 mmol) in a J. Young
NMR tube were added diarylsilane (0.25 mmol), [Pt(PPh3)3]
(7.4 mg, 7.5 μmol), and dibenzyl (2.3 mg, 0.013 mmol). The
reaction was performed at 45 oC, which monitored by 1H NMR,
4. Experimental
All manipulations were carried out in a nitrogen-filled
glovebox (Miwa MFG). The 1H and 31P{1H} NMR spectra
were recorded on Bruker Biospin Avance III 400 MHz and
Avance III H`D 500 MHz NMR spectrometers. The chemical
shifts in 1H NMR spectra were referenced to the residual peaks
of the solvent used. The peak positions of the 31P{1H} NMR
spectra were referenced to external 85% H3PO4 (δ 0) in
deuterated solvents. Benzaldehyde was purchased from TCI
and used after distillation. Karstedt’s catalyst (Aldrich),
H2SiPh2 (Aldrich), D2SiPh2 (Aldrich), (4-methyl)benzaldehyde
(TCI), 10-undecenal (TCI), and methyl(phenyl)ketone (TCI)
were purchased and used without further purification.
to
afford
hydrosilylated
product,
PhCH2OSiHPh2,
PhCH2OSiH(C6H4-4-Me)2, PhCHDOSiDPh2, respectively.
H2SiPh2: 90% NMR yield (k
=
1.79
×
10-4 s-1),
H2Si(C6H4-4-Me)2: 99% NMR yield (k = 5.15 × 10-4 s-1). H
NMR (400 MHz, C6D6, 298 K): δ 7.67 (d, 4H, C6H4, J = 7.6
Hz), 7.32 (d, 2H, C6H5, J = 7.3 Hz), 7.07-6.89 (m, 7H, C6H4
and C6H5, signals are overlapped with unreacted silane and
catalyst), 5.79 (s, 1H, SiH), 4.81 (s, 2H, CH2), 2.19 (s, 3H,
CH3). D2SiPh2: 49% NMR yield (k = 0.58 × 10-4 s-1). 1H NMR
(400 MHz, C6D6, 298 K): δ 7.68-7.67 (m, 4H, C6H5), 7.28 (d,
2H, C6H5, J = 7.4 Hz), 7.21-7.15 (m, 7H, C6H5), 7.08 (d, 2H,
C6H4, J = 7.5 Hz), 4.73 (s, 1H, CH).
1
8b)
23)
[Pt(PMe3)(μ-SiPh2)]3
and (3-vinyl)benzaldehyde
were
Hydrosilylation of (3-vinyl)benzaldehyde with H2SiPh2
catalyzed by [Pt(PPh3)3], [Pt(PMe3)(μ-SiPh2)]3, and
Karstedt’s catalyst. To
(3-vinyl)benzaldehyde (33 mg, 0.25 mmol) in a J. Young NMR
tube were added H2SiPh2 (46 mg, 0.025 mmol), Pt catalyst (39
μmol for [Pt(PPh3)3] and Karstedt’s catalyst, 13 μmol for
[Pt(PMe3)(μ-SiPh2)]3). The reaction was performed at 25 oC for
prepared according to the literature. [Pt(PPh3)3] was obtained
from the reaction of K2PtCl4 with PPh3 in the presence of KOH.
H2Si(C6H4-4-Me)2 was obtained via LiAlH4 reduction of
Cl2Si(C6H4-4-Me)2.
a C6D6 solution (0.5 mL) of
Hydrosilylation of 4-XC6H4CHO (H, -Me, -F, -CF3) with
H2SiPh2 catalyzed by [Pt(PPh3)3] and [Pt(PMe3)(μ-SiPh2)]3.
(a) Catalyst = [Pt(PPh3)3]: To a C6D6 solution (0.6 mL) of
4-XC6H4CHO (0.15 mmol) in a J. Young NMR tube were
added H2SiPh2 (82 mg, 0.44 mmol), [Pt(PPh3)3] (22 mg, 22
μmol), and dibenzyl (7 mg, 38 mmol). (b) Catalyst =
[Pt(PMe3)(μ-SiPh2)]3: In a NMR tube with a septum cap to a
C6D6 solution (0.6 mL) of [Pt(PMe3)(μ-SiPh2)]3 (10 mg, 7.1
μmol) were added H2SiPh2 (36 mg, 0.16 mmol) and
4-XC6H4CHO (0.13 mmol). These reactions were performed at
1
18 h to afford H2C=CHC6H4CH2OSiHPh2 in all catalysts. H
NMR (400 MHz, C6D6, r.t.): δ 7.67-7.66 (m, 4H, C6H4), 7.33 (s,
1H, C6H4), 7.20-7.14 (m, 8H, C6H4 and C6H5), 7.10 (q, 1H,
C6H4, J = 7.6, 15.1 Hz), 6.57 (q, 1H, C2H3, J = 10.9, 17.6 Hz),
5.72 (s, 1H, SiH), 5.60 (d, 1H, C2H3, J = 17.6 Hz), 5.69 (q, 1H,
C2H3, J = 10.9 Hz), 4.73 (s, 2H, CH2).
Synthesis of (3-vinyl)benzyl alcohol via hydrosilylation
of (3-vinyl)benzaldehyde with H2SiPh2 catalyzed by
[Pt(PPh3)3]. To
(3-vinyl)benzaldehyde (26 mg, 0.20 mmol) were added
H2SiPh2 (37 mg, 0.20 mmol) and [Pt(PPh3)3] (30 mg, 30 μmol).
The reaction mixture was stirred at 25 oC for 24 h.
Tetra-n-butylammonium fluoride (1.0 M THF solution, 0.4 mL,
0.4 mmol) was added to the mixture and stirred additional 1 h
at 25 oC. The solvent was removed under vacuum and the crude
product was purified by silica gel column chromatography
(Hexane/AcOEt = 7:3) to afford (3-vinyl)benzyl alcohol (19
mg, 0.14 mmol, 70%) as a pale yellow oil. 1H NMR (500 MHz,
CDCl3, r.t.): δ 7.35-7.32 (m, 4H, C6H3), 6.73 (q, 1H, C2H3, J =
10.9, 17.6 Hz), 5.77 (d, 1H, C2H3, J = 17.6 Hz), 5.27 (d, 1H,
C2H3, J = 10.9 Hz), 4.70 (d, 1H, CH2, J = 4.6 Hz), 1.63 (t, 1H,
o
1
25 C for 46 h, which was monitored by H NMR, to afford
(4-X-C6H4)CH2OSiHPh2 as the product. X = -H: 100% (k =
3.70 × 10-5 s-1) for [Pt(PPh3)3], 93% for [Pt(PMe3)(μ-SiPh2)]3,
a
toluene solution (5 mL) of
1
by NMR. H NMR (400 MHz, C6D6, 298 K): δ 7.67-7.65 (d,
4H, C6H5, J = 7.6 Hz), 7.26 (d, 2H, C6H5, J = 7.4 Hz), 7.17–
7.13 (m, 7H, C6H5), 6.98 (d, 2H, C6H5, J = 7.4 Hz), 5.71 (s, 1H,
SiH), 4.73 (s, 2H, CH2). X = -F: 93% (k = 1.72 × 10-5 s-1) for
[Pt(PPh3)3], 89% for [Pt(PMe3)(μ-SiPh2)]3 , by NMR. 1H NMR
(400 MHz, C6D6, 298 K): δ 7.63-7.61 (d, 4H, C6H5), 7.20-7.12
(m, 8H, C6H5 and C6H4), 6.75 (t, 2H, C6H4, J = 8.7 Hz), 5.65 (s,
1H, SiH), 4.57 (s, 2H, CH2). X = -CH3: 100% (k = 3.75 × 10-5
s-1) for [Pt(PPh3)3], 100% for [Pt(PMe3)(μ-SiPh2)]3, by NMR.
1H NMR (400 MHz, C6D6, 298 K): δ 7.67 (d, 4H, C6H5, J = 7.6
Hz), 7.21 (d, 2H, C6H4, J = 7.6 Hz), 7.15-7.06 (m, 6H, C6H5),
6.98 (d, 2H, C6H4, J = 7.6 Hz), 5.71 (s, 1H, SiH), 4.75 (s, 2H,
CH2), 2.08 (s, 3H, CH3). X = -CF3: 98% (k = 2.38 × 10-5 s-1)
for [Pt(PPh3)3], 43% for [Pt(PMe3)(μ-SiPh2)]3, by NMR. 1H
NMR (400 MHz, C6D6, 298 K): δ 7.60 (m, 4H, C6H4), 7.29 (d,
2H, C6H4, J = 8.0 Hz), 7.2-6.9 (m, 8H, C6H4), 5.64 (s, 1H, SiH),
4.55 (s, 2H, CH2).
1
OH, J = 5.2 Hz). H NMR data was matched with the reported
literature.24)
Hydrosilylation of 10-undecenal with H2SiPh2 catalyzed
by [Pt(PPh3)3]. To a C6D6 solution (0.5 mL) of 10-undecenal
(16 mg, 0.15 mmol) in a J. Young NMR tube were added
H2SiPh2 (82 mg, 0.44 mmol), [Pt(PPh3)3] (4.8 mg, 13 μmol).
The reaction was performed at 25 oC for 24 h to afford
H2C=CH(CH2)9OSiHPh2. 1H NMR (400 MHz, C6D6, r.t.): δ
5.86-5.76 (m, 1H, C2H3), 5.73 (s, 1H, SiH), 5.04-4.99 (m, 2H,
C2H3), 3.77 (t, 2H, CH2, J = 8.1 Hz), 2.03-1.98 (m, 2H, CH2),
1.63-1.56 (m, 2H, CH2), 1.38-1.15 (br, 12H, CH2).
Variable-temperature hydrosilylation of PhCHO with
H2SiPh2 catalyzed by [Pt(PPh3)3]. To a C6D6 solution (0.5
mL) of PhCHO (5.3 mg, 0.050 mmol) in a J. Young NMR tube
were added H2SiPh2 (46 mg, 0.25 mmol), [Pt(PPh3)3] (7.4 mg,
7.5 μmol), and dibenzyl (2.3 mg, 0.13 mmol). The reaction was
performed at 30 oC, 35 oC, 40 oC, and 45 oC, which were
Hydrosilylation of PhCOCH3 with H2SiPh2 catalyzed by
[Pt(PPh3)3] and [Pt(PMe3)(μ-SiPh2)]3. (a) Catalyst
=
1
monitored by H NMR. The rate constant (k) was determined
[Pt(PPh3)3]: To a C6D6 solution (0.5 mL) of [Pt(PPh3)3] (37 mg,
37 μmol) in a J. Young NMR tube were added H2SiPh2 (46 mg,
0.25 mmol), PhCOCH3 (30 mg, 0.25 mmol) and dibenzyl (2.3
mg, 13 mmol). The reaction was performed at 60 °C for 30 h.
(b) Catalyst = [Pt(PMe3)(μ-SiPh2)]3: In a NMR tube with a
septum cap to
[Pt(PMe3)(μ-SiPh2)]3 (10 mg, 7.4 μmol) were added H2SiPh2
(31 mg, 0.17 mmol), PhCOCH3 (19 mg, 0.16 mmol) and
by pseudo-first-order plot based on NMR yield. 30 oC: k = 2.51
o
o
× 10-4 s-1, 35 C: k = 4.20 × 10-4 s-1, 40 C: k = 1.22 × 10-3 s-1,
45 oC: k = 1.49 × 10-3 s-1. The kinetic parameters were
calculated from these rate constants; Ea = 24.0 kcal mol-1 by the
Arrhenius plot, ΔH‡ = 23.6 kcal mol-1, ΔS‡ = -1.2 cal K-1 mol-1,
ΔG‡ = 23.9 kcal mol-1, by the Eyring.
a
C6D6 solution (0.6 mL) of
Hydrosilylation
of
PhCHO
with
H2SiPh2,

dibenzyl (7 mg, 38 mmol). The reaction was performed at
60 °C for 54 h. These reaction mixtures contained
hydrosilylated product A, dehydrosilylated product B, and
dimer C. The NMR yields of these products were summarized
in Eq. 4. 1H NMR for A (400 MHz, C6D6, 298 K): δ 5.67 (s, 1H,
SiH), 4.95 (q, 1H, CH, J = 6.4 Hz), 1.42 (d, 3H, CH3, J = 6.4
36, 2902-2913.
(4) F. G. Fontaine, R.-V. Nguyen, D. Zargarian, Can. J. Chem.
2003, 81, 1299-1306.
(5) (a) J. L. Speier, J. A. Webster, G. H. Barnes, J. Am. Chem.
Soc. 1957, 79, 974-979. (b) I. E. Markó, S. Stérin, O. Buisine,
G. Mignani, P. Branlard, B. Tinant, J. P. Declercq, Science 2002,
298, 204-206. (c) Y. Nishihara, M. Itazaki, K. Osakada, K.
Tetrahedron Lett. 2002, 43, 2059-2061. (d) M. Itazaki, Y.
Nishihara, K. Osakada, K. J. Org. Chem. 2002, 67, 6889-6895.
(e) D. Troegel, J. Stohrer, Coord. Chem. Rev. 2011, 255,
1440-1459. (f) Y. Nakajima, S. Shimada, RSC Adv. 2015, 5,
20603-20616. (g) T. Iimura, N. Akasaka, T. Iwamoto,
Organometallics 2016, 35, 4071-4076.
(6) (a) A. D. Petrov, S. I. Sadykh-Zade, Doklady Akad. Nauk S.
S. S. R. 1958, 121, 119–122; Chem. Abstr. 1959, 53, 1207b.
(b) S. I. Sadykh-Zade, A. D. Petrov, Zhur. Obschei Khim. 1959,
29, 3194–3198; Chem. Abstr. 1960, 54, 12978e. (c) A. P.
Barlow, N. M. Boag, F. G. A. Stone, J. Organomet. Chem. 1980,
191, 39-47. (d) H. Yamashita, N. P. Reddy, M. Tanaka,
Organometallics 1997, 16, 5223-5233.
1
Hz). H NMR for B (400 MHz, C6D6, 298 K): δ 5.89 (s, 1H,
SiH), 4.89 (d, 1H, = CH2, J = 2.4 Hz), 4.65 (d, 1H, = CH2, J =
2.4 Hz). 1H NMR for C (400 MHz, C6D6, 298 K): δ 5.89 (s, 1H,
SiH). These data were consistent with the literature.
Acknowledgement
This work was financially supported by Grants-in-Aid for
Scientific Research (B) (No. 17H03029), (C) (No. 25410061),
and Challenging Exploratory Research (26620040) from Japan
Society for Promotion of Science, and by Dynamic Alliance for
Open Innovation Bridging. We thank our colleagues in the
Suzukakedai Materials Analysis Division, Technical
Department, Tokyo Institute of Technology.
References
(7) (a) K. Yamamoto, T. Hayashi, M. Kumada, J. Organomet.
Chem. 1972, 46, C65-C67. (b) T. Hayashi, K. Yamamoto, M.
Kumada, J. Organomet. Chem. 1976, 112, 253-262. (c) W. R.
Cullen, S. V. Evans, N. -F. Han, J. Trotter, Inorg. Chem. 1987,
26, 514-519. (d) V. V. Zuev, D. A. de Vekki, Phosphorus, Sulfur,
and Silicon, 2005, 180, 2071-2083. (e) M. R. Buchner, B.
Bechlars, K. Ruhland, J. Organomet. Chem. 2013, 60-67. See
also, M. R. Buchner, B. Bechlars, B. Wahl, K. Ruhland,
Organometallics 2013, 32, 1643-1653.
(8) (a) M. Tanabe, M. Kamono, K. Tanaka, K. Osakada,
Organometallics 2017, 36, 1929-1935. (b) K. Tanaka, M.
Kamono, M. Tanabe, K. Osakada, Organometallics 2015, 34,
2985-2990.
(9) The hydrosilylation products in this study tend to
decompose slowly under air and moisture, which rendered their
isolation difficult. We treated the hydrosilylation product with
NBu4F, and isolated the resulting (3-vinyl)benzyl alcohol after
purification by silica gel chromatography (Hexane/AcOEt =
7:3) in 70%. The hydrosilylation of 10-undecenal with H2SiPh2
in an NMR-scale formed H2C=CH(CH2)9OSiHPh2 with high
selectivity, but isolation of the product nor its desilylated
alcohol was not feasible.
(1) (a) I. Ojima, M. Nihonyanagi, Y. Nagai, J. Chem. Soc.,
Chem. Commun. 1972, 938. (b) I. Ojima, T. Kogure, Y. Nagai,
Tetrahedron Lett. 1974, 15, 1889-1892. (c) Ojima, I.; Kogure,
T.; Nagai, Y. Chem. Lett. 1975, 4, 985-988. (d) W.-L. Duan, M.
Shi, G. B. Rong, Chem. Commun. 2003, 2916-2917. (e) T.
Hayashi, K. Yamamoto, M. Kumada, Tetrahedron Lett. 1975,
16, 3-6. (f) T. Hayashi, C. Hayashi, Y. Uozumi, Tetrahedron
Asymm. 1995, 6, 2503-2506. (g) H. Brunner, R. Riepl, Angew.
Chem., Int. Ed. Engl. 1982, 21, 377-378. (h) H. Brunner, G.
Riepl, H. Weitzer, Angew. Chem., Int. Ed. Engl. 1983, 22,
331-332. (i) H. Brunner, R. Ströriko, B. Nuber, Tetrahedron
Asym. 1998, 9, 407-422. (j) M. Sawamura, R. Kuwano, Y. Ito,
Angew. Chem., Int. Ed. Engl. 1994, 33, 111-113. (k) G.
Hamasaka, A. Ochida, K. Hara, M. Sawamura, Angew. Chem.,
Int. Ed. 2007, 46, 5381-5383. (l) L. H. Gade, V. César, S.
Bellemin-Laponnaz, Angew. Chem., Int. Ed. 2004, 43,
1014-1017. (m) V. César, S. Bellemin-Laponnaz, H. Wadepohl,
L. H. Gade, Chem. Eur. J. 2005, 11, 2862-2873.
(2) (a) B. H. Lipshutz, K. Noson, W. Chrisman, J. Am. Chem.
Soc. 2001, 123, 12917-12918. (b) B. H. Lipshutz, A, Lower,K.
Noson, Org. Lett. 2002, 4, 4045-4048. (c) B. H. Lipshutz, K.
Noson, W. Chrisman, A. Lower, J. Am. Chem. Soc. 2003, 125,
8779-8789. (d) D.-W. Lee, J. Yun, Tetrahedron Lett. 2004, 45,
5415-5417. (e) B. H. Lipshutz, B. A. Frieman, Angew. Chem.
Int. Ed. 2005, 44, 6345-6348. (f) J. Yun, D. Kim, H. Yun,
Chem. Commun. 2005, 5181-5183.
(10) S. Sakaki. N. Mizoe, M. Sugimoto, Organometallics 1998,
17, 2510-2523.
(11) I. Ojima, T. Kogure, M. Kumagai, S. Horiuchi, T. Sato, J.
Organomet. Chem. 1976, 122, 83-97.
(12) C. Reyes, A. Prock, W. P. Giering, Organometallics 2002,
21, 546-554.
(3) (a) H. Brunner, K. Fisch, J. Organomet. Chem. 1991, 412,
C11-C13. (b) P. Buchgraber, L. Toupet, V. Guerchais,
Organometallics 2003, 22, 5144-5147. (c) H, Nishiyama, A.
Furuta, Chem. Commun. 2007, 760-762. (d) S. Hosokawa, J. Ito,
H. Nishiyama, Organometallics 2010, 29, 5773-5775. (e) N. S.
Shaikh, K. Junge, M. Beller, Org. Lett. 2007, 9, 5429-5432. (f)
N. S. Shaikh, S. Enthaler, K. Junge, M. Beller, Angew. Chem.
Int. Ed. 2008, 47, 2497-2501. (g) A. M. Tondreau, E.
Lobkovsky, P. J. Chirik, Org. Lett. 2008, 10, 2789-2792. (h) A.
M. Tondreau, J. M. Darmon, B. M. Wile, S. K. Floyd, E.
Lobkovsky, P. J. Chirik, Organometallics 2009, 28, 3928-3940.
(i) B. K. Langlotz, H. Wadepohl, L. H. Gade, Angew. Chem. Int.
Ed. 2008, 47, 4670-4674. (j) J. Yang, T. Don Tilley, Angew.
Chem. Int. Ed. 2010, 49, 1-4. (k) F. Jiang, D. Bézier, J. B.
Sortais, C. Darcel, Adv. Synth. Catal. 2011, 353, 239-244. (l)
K. Muller, A. Schubert, T. Jozak, A. Ahrens-Botzong, V.
Schünemann, W. R. Thiel, ChemCatChem 2011, 3, 887-892.
(m) T. Bleith, L. H. Gade, J. Am. Chem. Soc. 2016, 138,
4972-4983. (n) C. Johnson, M. Alrecht, Organometallics 2017,
(13) T. W. Lyons, M. Brookhart, Chem. Eur. J. 2013, 19,
10124-10127.
(14) T. K. Mukhopadhyay, C. Ghosh, M. Flores, T. L. Groy, R.
J. Trovitch, Organometallics 2017, 36, 3477-3483.
(15) (a) S. C. Chakraborty, J. A. Krause, H. Guan, H.
Organometallics 2009, 28, 582-586. (b) H. Kaur, F. K. Zinn, E.
D. Stevens, S. P. Nolan, Organometallics 2004, 23, 1157-1160.
(c) S. Díez-González, S. P. Nolan, Acc. Chem. Res. 2008, 41,
349-358. (d) T. Bleith, L. H. Gade, J. Am. Chem. Soc. 2016,
138, 4972-4983.
(16) G. Z. Zheng, T. H. Chan, Organometallics 1995, 14,
70-79.
(17) (a) S. Park, M. Brookhart, Organometallics 2010, 29,
6057-6064. (b) C. Cheng, M. Brookhart, Angew Chem. Int. Ed.
2012, 51. 9422-9424. (c) W. Wang, P. Gu, Y. Wang, H. Wei,
Organometallics 2014, 33, 847-857. (d) T. T. Metsänen, P.
Hrobárik, H. F. T. Klare, M. Kaupp, M. Oestreich, J. Am. Chem.
Soc. 2014, 136, 6912-6915.

(18) N. Schneider, M. Finger, C. Haferkemper, S.
Bellemin-Laponnaz, P. Hofmann, L. H. Gade, Angew. Chem.
Int. Ed. 2009, 48, 1609-1613.
(19) P. Gigler, B. Bechlars, W. A. Herrmann, F. E. Kühn, J. Am.
Chem. Soc. 2011, 133, 1589-1596.
(20) K. Riener, M. P. Högerl, P. Gigler, F. E. Kühn, ACS Catal.
2012, 2, 613-621.
(21) K. Garcés, R. Lalrempuia, V. Polo, F. J.
Fernández-Alvarez, P. García-Orduňa, F. J. Lahoz, J. J.
Pérez-Torrente, L. A. Oro, Chem. Eur. J. 2016, 22,
14717-14729
(22) F. Fu, J. Xiang, H. Cheng, L. Cheng, H. Chong, S. Wang, P.
Li, S. Wei, M. Zhu, Y. Li, ACS Catal. 2017, 7, 1860-1867.
(23) B. Yan, J. Cramen, R. McDonald, N. L. Frank Chem
Commun. 2011, 47, 3201-3203.
(24) S. E. Denmark and Z. Wang Synthesis 2000, 7, 999-1003.