Highly Regio- and Stereoselective Hydrosilylation of Alkynes Catalyzed by Tridentate Cobalt Complexes

Article abstract of DOI:10.1002/asia.201900577

Several cobalt complexes bearing tridentate (NNN) ligands were synthesized and served as precatalysts for alkyne hydrosilylation with Ph₂SiH₂. For terminal alkynes, the catalyst L2 b-CoCl₂ was selected, and resulted in the corresponding α-vinylsilanes with high (Markovnikov) regioselectivity and extensive functional-group tolerance. For internal diaryl alkynes, the catalyst L2 c-CoCl₂ exhibited the best activity, and afforded E-selective vinylsilanes through syn-addition in excellent yield under mild conditions.

Full text of DOI:10.1002/asia.201900577

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Accepted Article
Title: Highly Regio- and Stereo-Selective Hydrosilylation of Alkynes
Catalyzed by Tridentate Cobalt Complexes
Authors: Degong Kong, Bowen Hu, and Dafa Chen
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Highly Regio- and Stereo-Selective Hydrosilylation of Alkynes
Catalyzed by Tridentate Cobalt Complexes
Degong Kong, Bowen Hu, and Dafa Chen*
Abstract: Several cobalt complexes bearing tridentate (NNN)
ligands were synthesized and served as precatalyst for alkyne
2 2 2
hydrosilylation with Ph SiH . For terminal alkynes, L2b-CoCl was
selected as the catalyst, endowing the corresponding α-vinylsilanes
with high (Markovnikov) regioselectivity and extensive functional-
group tolerance. While for internal diaryl alkynes, L2c-CoCl
2
exhibited the best activity, affording E-selective vinylsilanes via syn-
addition in excellent yield under mild conditions.
Introduction
Vinylsilanes are regarded as versatile building blocks in organic
synthesis, in virtue of inherent dense poly-functionalization, high
stability, facile manipulations, and substantial transformations.[1]
Meanwhile, hydrosilylation of alkynes is one of the most
straightforward and atom-economic strategies for the production
of vinylsilanes. However, the hydrosilylation of terminal alkynes
can generate (E)-β-, (Z)-β- and α-vinylsilanes (Scheme 1),
rendering the control of regioselectivity and stereoselectivity
challenging. Furthermore, the side reactions such as
dehydrocoupling of silanes, hydrogenation of alkynes and the
multiaddition of alkynes also complicate the catalytic system.[2]
Today the field of alkyne hydrosilylation depends badly on
noble transition metals, such as Ru,[3] Rh,[4] Ir,[5] Pd[6] and Pt.[7]
Under this circumstance, low-toxic, inexpensive and earth-
abundant base metals (e.g. Fe,[8,9] Ni,[10,11] and Mn ) have been
proven to be promising alternatives. Especially, Co complexes
showing high regioselectivity and stereoselectivity have been
developed rapidly in recent years (Scheme 1).[2b],[13-20] For
instance, Deng and co-workers developed a three-coordinate
cobalt(I) complex catalyzing the hydrosilylation of alkynes to
[12]
Scheme 1. Cobalt complexes for hydrosilylation of alkynes.
synthesize (E)-β-vinylsilanes with
(
a
high regioselectivity
Scheme 1a-I).[13a] Thomas described the complex ( PDI)CoCl
Mes
2
[
8b]
Markovnikov selective (α-selective) hydrosilylation could also
be achieved by Co catalysts. In 2016, Huang’s and Lu’s groups
independently reported NNN-Co complexes with Pybox or
iminopyridine-oxazoline (IPO) ligands for the synthesis of α-
vinylsilanes, almost at the same time (Schemes 1a-VII and
VIII).[17] In addition, they extended their methods to synthesize
silicon-stereogenic vinylhydrosilanes and chiral silanes,
respectively.[18] More recently, Yang’s team raised another α-
selective hydrosilylation Co catalyst with the NNN ligand amine-
for (E)-β-selective hydrosilylation of oct-1-yne (Scheme 1a-II).
Ge’s group found that Co(acac)
2
with a phosphine ligand
dpephos or xantphos could also gave (E)-β-vinylsilanes, and von
Wangelin et al. later reported a similar result (Schemes 1a-III
and IV).[
2b],[14]
With the same metal catalyst Co(OAc)
2
but
different ligand (pyridine-2,6-diimine), the major products were
changed to (Z)-β-vinylsilanes (Scheme 1a-V).[15] A pincer type
PNN-Co complex was also found to be effective for (Z)-β-
selectivity (Scheme 1a-VI).[16]
pyridine-imine (API), exhibiting high activity (Scheme 1a-IX).[
19]
Moreover, Co(OAc)
2
with 4 bipy was also effective (Scheme
-Me
1
a-X).[14] Undoubtedly, the development of new highly efficient
[
a] D. Kong, B. Hu, Prof. Dr. D. Chen*
MIIT Key Laboratory of Critical Materials Technology for New Energy
Conversion and Storage
catalysts with simple and stable ligands for Markovnikov
hydrosilylation is still desirable.
Institution School of Chemical Engineering & Technology
Harbin Institute of Technology
Harbin 150001(china)
Recently, our group developed a series of tridentate NNN-Ru
-relating reactions.[21] Based on
complexes to catalyze
H
2
previous works, herein we report the synthesis and catalytic
E-mail: dafachen@hit.edu.cn
Supporting information for this article is given via a link at the end of the
document.((Please delete this text if not appropriate))
activity for hydrosilylation of terminal and internal alkynes with
C
Ph
2
SiH
2
of several N NN-CoX
2
complexes. With hydroxyl or
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C
[a] Reaction conditions: phenylacetylene (0.6 mmol), silane (0.6 mmol), [Co] (2
2
methoxy as substituent in N NN-CoX , hydrosilylation of alkynes
[
b]
mol%), NaBEt
3
H (6 mol%), THF (2 mL), room temperature, 5 min.
afforded vinylsilanes with high α-selectivity (for terminal alkynes)
and E-selectivity (for internal alkynes) in 5 min at room
temperature, respectively.
[
c]
Determined by GC analysis with n-dodecane as the internal standard.
1
[d]
Isolated yield. Regioselective ratios were determined by H NMR. Without
NaBEt
3
H. [ Reaction for 15 min.
e]
The terpyridyl NNN-Co complex L1a-CoCl
2
showed high
Results and Discussion
conversion (97%) but poor selectivity (3a/3a-E = 42:58) (Table 1,
Entry 1). When a hydroxyl group was introduced to the side
pyridyl ring, a significant decrease in the conversion (76%) and a
slight increase in regioselectivity appeared (3a/3a-E = 39:61)
One known complex L1a-CoCl
shown in Table were synthesized by the reactions of
corresponding NNN ligands with CoX (X = Cl, Br) in THF,
respectively. The molecular structures of L2b-CoCl and L2c-
CoCl are shown in Figure 1. These complexes were then tested
as catalysts for the reaction of phenylacetylene with Ph SiH
and the reactions were carried out in the presence of NaBEt
as the catalyst activator in THF at room temperature for 5 min
Table 1).
2
and six other new complexes
1
2
(
Table 1, Entry 2). Switching the precatalyst to a cobalt complex
2
C
with N NN ligand (L2a-CoCl
2
), (Z)-β-vinylsilane was observed
2
and a slightly improved regioselectivity for α-vinylsilane was
obtained (3a/3a-E/3a-Z = 59:12:29) (Table 1, Entry 3). When
2
2
,
H
3
L2b-CoCl
2
as a precatalyst was used, hydrosilylation of
phenylacetylene proceeded with excellent conversion and
decent selectivity for the Markovnikov regioisomer (3a/3a-E =
(
93:7, 94% conversion), and the relevant (Z)-β-vinylsilane was
not observed (Table 1, Entry 4). When bromide ion substituted
for chloride ion, the conversion and regioselectivity slightly
decreased (3a/3a-E = 90:10, 93% conversion) (Table 1, Entry 5).
The use of 2-methoxypyridyl (L2c-CoCl ) gave a slight increase
2
in the conversion and a slight decrease in regioselectivity to the
corresponding vinylsilane (3a/3a-E = 91:9, 97% conversion)
(
Table 1, Entry 6). When the substitutent was further increased
in size to tert-butoxy group, the yield was significantly decreased,
with a slightly poorer regioselectivity (3a/3a-E = 88:12, 80%
conversion) (Table 1, Entry 7). Using anhydrous CoCl
as the catalyst, only trace product was detected by GC (Table 1,
Entries 8 and 9). In the absence of NaBEt H, no product was
obtained when L2b-CoCl was selected as the catalyst (Table 1,
Entry 10). Phenylsilane was also suitable for hydrosilylation with
a to obtain the corresponding α-vinylsilane in good yield and
regioselectivity (Table 1, Entry 11). While tertiary silanes, such
as PhMe SiH and Et SiH, were inapplicable (Table 1, Entries 12
2 2
or CoBr
2 2
Figure 1. The molecular structures of L2b-CoCl (left) and L2c-CoCl (right).
3
Table 1. Catalyst screening for the hydrosilylation of 1a with silanes.
2
1
2
3
and 13). Other solvents and additives were also tested, and the
details are shown in Table S1 in supporting information.
Under the optimal conditions, the substrate scope of the
Markovnikov selective hydrosilylation was explored with a range
of electronically and sterically differentiated alkynes (Table 2).
Hydrosilylation of phenylacetylene gave the vinylsilane with a
good isolated yield and a 93:7 branched:linear selectivity (3a,
86%). Phenylacetylene derivatives bearing electron-donating
groups such as methoxy and methyl underwent successful
hydrosilylation in excellent yields and regioselectivity (3b-3e, 89-
96%). Fluoro group in the phenyl ring of phenylacetylene did not
influence the results obviously (3f and 3g), while other electron-
withdrawing groups, such as chloro, bromo and trifluoromethyl,
decreased the yields (3h-3l, 66-83%). Especially for ortho-
chlorophenylacetylene, the yield was 66%, much lower than
para-chlorophenylacetylene, probably due to steric effect (3i). 4-
Aminophenylacetylene
also
underwent
successful
hydrosilylation in excellent yield and regioselectivity (3m). Other
heteroaromatic alkynes, such as 2-thienyl and 3-pyridyl alkynes,
could also be delivered to the corresponding α-vinylsilanes in
satisfied yields and high regioselectivity (3n-3o, 64-84%). The
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alkenyl- and alkyl-substituted terminal alkynes gave high yields,
but decreased regioselectivity (3p-3q). Meanwhile, 1-naphthyl
and 2-naphthyl functional groups were tolerated (3r-3s, 64-90%). efficiency for the reaction of diphenylacetylene with Ph
Internal dialkyl alkynes also underwent the hydrosilylation
reaction under optimized conditions to give the products in good
yields and stereoselectivity (3t-3u, 80-86%).
CoCl
in a fast speed (Table 1, Entries 1 and 4), they exhibited lower
SiH
(Table 3, Entries 1 and 2). To our delight, the hydrosilylation of
diphenylacetylene proceeded in excellent yield with high
selectivity for E-stereoisomer when L2c-CoCl was applied as
2
2 2
could convert phenylacetylene and Ph SiH to vinylsilanes
2
2
2
the catalyst, and even with a lower catalyst loading (1 mol%),
the corresponding product could be isolated in 92% yield with a
96:4 E/Z ratio (Table 3, Entries 3 and 4).
Table 2. Scope for hydrosilylation of terminal alkynes and internal alkyl
alkynes.
2 2
Table 3. Catalyst screen for hydrosilylation of 4a with Ph SiH .
[
a]
Reaction conditions: diphenyl acetylene (0.5 mmol), Ph
2
SiH
2
(0.5 mmol),
H (6 mol%), THF (2 mL), room temperature, 5 min. [
b]
[
Co] (2 mol%), NaBEt
3
[
c]
Determined by GC analysis with n-dodecane as the internal standard.
Isolated yield. [ Determined by H NMR. GC yield. with 1 mol% L2c-CoCl
d]
1
[e]
[f]
2
and 3 mol% NaBEt
3
H.
Table 4. Scope for hydrosilylation of diaryl alkynes.
[
a]
Reaction conditions: alkyne (0.6 mmol), Ph
2 2 2
SiH (0.6 mmol), L2b-CoCl (2
mol%), NaBEt H (1.0 M) (6 mol%, 36 uL), THF (2 mL), room temperature, 5
3
min. Isolated yields of
3
along with α/E ratios are shown. Ratios were
determined by H NMR. [b] Reaction for 15 min. Isolated yields, The ratio of
1
[c]
1
E-/Z-vinylsilanes was determined by H NMR.
Compared to terminal alkynes, internal alkynes, especially
diaryl alkynes, are normally more inert in the hydrosilylation
reactions owing to steric hindrance.[14],[17b] For example, von
Wangelin’s system involving hydrosilylation of diphenylacetylene
with PhSiH
vinylsilanes in 31% yield.[14] Lu and co-workers also treated their
catalyst IPO-CoBr for hydrosilylation of diaryl alkynes with
Ph SiH , while only two substrates were reported and the yields
3 2
employing Co(OAc) /xantphos, afforded the desired
2
2
2
were not as high as terminal alkynes (diphenylacetylene: 33%
yield; 2-(phenylethynyl)thiophene: 68% yield).[17b] To further
explore the efficiency of our catalysts for the hydrosilylation of
diaryl alkynes, three NNN-Co complexes were attempted, and
[
a]
Reaction conditions: diaryl alkyne (0.5 mmol), Ph
2
SiH
2
(0.5 mmol), L2c-
the results are shown in Table 3. Although L1a-CoCl
2
and L2b-
CoCl (1 mol%), NaBEt H (1.0 M) (3 mol%, 15 uL), THF (2 mL), room
2
3
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temperature, 5 min. Isolated yields of 5 along with E/Z ratios are shown. r.r. =
metal moiety. The cobalt silyl intermediates B and D play the
regioisomeric ratio. Ratios were determined by 1H NMR. Reaction for 15 min.
[b]
same role, which convert back to A after the attack of Ph
accompanied by the formation of the targeted vinylsilanes 3 and
’, respectively (the anti-addition product 3’ is the minor product
when R is not hydrogen).
2 2
SiH ,
3
With these conditions in hand, the substrate scope for E-
selective hydrosilylation of diaryl alkynes was investigated
1
(
Table 4). Hydrosilylation of diphenylacetylene gave the
corresponding product in high yield with good selectivity (5a,
2%, E/Z = 96:4). The presence of para- or meta- electron
donating groups, such as –CH or –OMe, on the phenyl rings of
9
3
alkynes, were well tolerated, and they provided only syn-additive
vinylsilanes in excellent yields (5b-5d, 93-96%, E/Z = 100:0).
Similarly,
the
electronic
poor
alkyne
(1,2-bis(4-
fluorophenyl)ethyne) provided the desired product in high yield
with satisfied E-selectivity (5e, 96%, E/Z = 96:4), too. para-
Substituted unsymmetrical diaryl alkynes also gave E-
vinylsilanes in high yields, whereas almost no regioselectivity
was exhibited (5f-5i, 93-96%), similar to Petit’s results.[20] When
1,3-dimethyl-2-(phenylethynyl)benzene
was
used,
the
corresponding product 5j was isolated in a reduced yield of 30%
with high regiospecificity (r.r = 100:0), due to the steric effect.
In fact, vinylsilane products can undergo various
transformations. For example, Tamao oxidation afforded aryl
ketones in high yields (6a, 6d and 6s, 81-90%) (Scheme 2) (see
details in the Supporting Information).
Scheme 4. Proposed mechanism for the Co-catalyzed alkyne hydrosilylation.
Conclusions
In summary, we developed several tridentate NNN cobalt
Scheme 2. Tamao oxidation of α-vinylsilanes.
2 2
complexes for the hydrosilylation of alkynes with Ph SiH ,
showing high activity and selectivity. For terminal alkynes, a
variety of electronically and sterically differentiated substituents
2
Besides, vinylsilanes can be hydrogenated with H to give
alkylsilanes,[18b] which are normally synthesized through
were suitable for such transformation when L2b-CoCl
was selected as the catalyst, and almost all the reactions were
achieved in min at room temperature, affording the
corresponding Markovnikov-selective products (α-vinylsilanes).
For internal diaryl alkynes, L2c-CoCl was the most efficient
2
(2 mol%)
hydrosilylation of alkenes, and can be further transformed to
high-value silicon-based materials.[22] An alternative way to
5
synthesize alkylsilanes from vinylsilanes is using a silane as the
reduction reagent.[24] In our study, we found L2b-CoCl
2
can
catalyze the hydrogenation of α-vinylsilane (3a) with PhSiH
3
,
2
catalyst (1 mol%), providing several E-vinylsilanes in satisfied
giving product 7a in 78% yield after 24 hours (Scheme 3). As
previously reported, compound 7a could also be synthesized
yields. The results suggest the proper electron-donating groups
C
(
HO-, and MeO-, but not t-BuO-) in the 2-position of N NN ring
2 2
from styrene with Ph SiH via Markovnikov addition, but the
catalysts are still rare.[
23b,24]
might improve the reaction speed and selectivity. To the best of
our knowledge, L2c-CoCl is the most efficient Co catalyst for
2
hydrosilylation of diaryl alkynes reported up to date. Further
experimental studies are needed for understanding the detailed
mechanisms.
Scheme 3. Hydrogenation of α-vinylsilane.
Experimental Section
In the light of the precedents of hydrosilylation processes, a
proposed mechanism for the Co-catalyzed alkyne hydrosilylation
is shown in Scheme 4.[16],[18],[5b],[25] The cobalt complex reacts
General Considerations
with NaBEt
3
H and Ph
2
SiH
2
, affording a low-valent Co(I) silyl
All manipulations were carried out using standard high vacuum line,
oven-dried standard Schlenk techniques or in an Vigor inert atmosphere
drybox containing an atmosphere of purified nitrogen. All solvents were
species A, which is then inserted by alkyne to generate the
cobalt vinyl species B. The intermediate B undergoes Crabtree-
Ojima-type isomerization to form C and D because of the
significant steric repulsion between the bulky silyl group and the
distilled from the appropriate drying agents under N
reagents were obtained from commercial suppliers and used without
further purification. L2a, L2b, L2c and L1a-CoCl were prepared
2
before use. All
2
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according to the literatures.[21a],[26] Internal diaryl alkynes were prepared
according to the previously reported method.[27] The 1H and 13C NMR
8.34 (d, J = 8 Hz, 1H), 7.98 (t, J = 7.8 Hz, 1H), 7.90 – 7.85 (m, 1H), 7.77
– 7.70 (m, 3H), 7.32 – 7.26 (m, 1H), 6.87 – 6.81 (m, 1H), 1.36 (s, 9H).
spectra were recorded on a Bruker Advance 400 spectrometer. The 1
NMR chemical shifts were referenced to the residual solvent as
H
13C NMR (100 MHz, CDCl
3
, ppm) δ 193.8, 162.6, 155.4, 155.2, 155.1,
149.0, 138.6, 137.2, 136.8, 124.0 (d), 122.8, 121.5, 117.4, 116.9, 80.1,
28.3.
13
1
determined relative to Me
reported in ppm relative to the carbon resonance of CDCl
DMSO (40.0 ppm). Elemental analyses were performed on
4
Si (0 ppm). The C{ H} chemical shifts were
3
(77.0 ppm) or
a
Synthesis of 6-((6-(tert-butoxy)pyridin-2-yl)methyl)-2,2'-bipyridine
PerkinElmer 240C analyzer. High-resolution mass spectra (HR-MS) were
recorded on a Varian 7.0 T FTICR-MS by the ESI technique. For single-
(
L2d): To
yl)methanone (S-2) (1.00 g, 3 mmol) in 16 mL ethylene glycol was added
NaOH (1.3 g) and NH NH (16 mL, 80% in water). The mixture was
a solution of [2,2'-bipyridin]-6-yl(6-(tert-butoxy)pyridin-2-
crystal X-ray diffraction, suitable crystals were placed in a cooled N
2
2
2
stream at 173(2) K on a Bruker D8 Quest X-ray diffractometer. Data
collections were performed using four-circle kappa diffractometers
equipped with CCD detectors. Data were reduced and then corrected for
absorption. Solution, refinement, and geometrical calculations for all
crystal structures were performed by SHELXTL. All GC measurements
were performed on Agilent GC7890A equipment using an Agilent
heated at 100 °C for 5 h. Water (20 mL) was added and the solution was
neutralized by dilute HCl (1.0 M) and extracted with ethyl acetate. The
organic phase was dried over Na
2 4
SO and evaporated under vacuum.
The crude product was purified by column chromatography on silica gel
(
petroleum ether/ethyl acetate to give L2d (0.81 g, 85%). HR-MS (ESI,
+
+
1
m/z): Calcd for C20
NMR (400 MHz, CDCl
H), 8.22 (d, J = 7.6 Hz, 1H), 7.79 (td, J = 7.6, 1.6 Hz, 1H), 7.72 (t, J =
H N
21 3
O
[
M
+
H
]
,
3
2
0
.
1
7
6
3
.
F
o
u
n
d
,
3
2
0
.
1
7
5
4
.
H
19091B-102 (25 m, 220 μm) column.
3
, ppm) δ 8.66 (d, J = 4.8 Hz, 1H), 8.43 (d, J = 8 Hz,
1
Synthesis of 6-methoxy-2,2':6',2''-terpyridine (S-1): A 250 mL Schlenk
flask was charged with Pd(PPh (0.289 g, 0.25 mmol), 6-bromo-6'-
methoxy-2,2'-Bipyridine (1.32 g, 5 mmol), 2-(tributylstannyl)pyridine (2 g,
.5 mmol), LiCl (2.1 g, 50 mmol) and 100 ml toluene under the
7.6 Hz, 1H), 7.44 (t, J = 7.8 Hz, 1H), 7.30 – 7.22 (m, 2H), 6.81 (d, J = 7.2
Hz, 1H), 6.48 (d, J = 8.4 Hz, 1H), 4.29 (s, 2H), 1.49 (s, 9H). 13C NMR
3 4
)
(100 MHz, CDCl
3
, ppm) δ 163.4, 159.4, 156.7, 156.5, 155.5, 149.1, 138.6,
5
137.1, 136.8, 123.7, 123.5, 121.3, 118.5, 115.4, 110.5, 79.4, 47.1, 28.6.
atmosphere of nitrogen. The reaction mixture was stirred at reflux for 24
h, after the starting materials were consumed completely. The mixture
was cooled to room temperature, filtered through a pad of silica gel, and
washed by ethyl acetate. The filtrate was concentrated and purified by
flash column chromatography using petroleum ether/ethyl acetate = 5/1
as the eluent to give the product as a white solid (0.92 g, 70%). Mp:
Synthesis of L1b-CoCl
100 mg, 0.4 mmol), CoCl
atmosphere of nitrogen, the mixture was stirred at room temperature for
2 h. Removing the solvent by filtration afforded a green powder. The
cake was washed with ether and dried in vacuum to give L1b-CoCl (129
mg, 85% yield); Anal. Calcd. For C15 CoN O: C, 47.52; H, 2.92; N,
2
: A 10 mL Schlenk flask was charged with L1b
(
2
(52 mg, 0.4 mmol) and 5 mL THF under the
1
2
o
+
+
9
7.8~99 C. HR-MS (ESI, m/z): Calcd for C16
13 3
H N O [M+H] : 264.1137;
H11Cl
2
3
1
Found: 264.1142. H NMR (CDCl
3
, 400 MHz) δ 8.70 (d, J = 5.6 Hz, 1H),
11.08. Found C, 47.75; H, 2.97; N, 11.01.
8
.63 (d, J = 8.0 Hz, 1H), 8.44 (t, J = 7.0 Hz, 2H), 8.23 (d, J = 7.6 Hz, 1H),
.94 (t, J = 7.8 Hz, 1H), 7.86 (td, J = 7.8 Hz, 1.7 Hz, 1H), 7.74 (t, J = 7.8
7
Synthesis of L2a-CoCl
2
: A 10 mL Schlenk flask was charged with L2a
(52 mg, 0.4 mmol) and 5 mL THF under the
atmosphere of nitrogen, the mixture was stirred at room temperature for
2 h. Removing the solvent by filtration afforded a red powder. The cake
was washed with ether and dried in vacuum to give L2a-CoCl (120 mg,
0% yield); Anal. Calcd. For C16 CoN : C, 50.96; H, 3.47; N, 11.14.
Found C, 51.23; H, 3.55; N, 11.10.
Hz, 1H), 7.36 – 7.31 (m, 1H), 6.8 (d, J = 8 Hz, 1H), 4.07 (s, 3H). 13C NMR
(
99 mg, 0.4 mmol), CoCl
2
(
1
CDCl
3
, 101 MHz) δ 163.6, 156.3, 155.3, 153.6, 149.0, 139.3, 137.8,
37.0, 123.8, 121.2, 120.9, 120.8, 113.8, 111.1, 53.3.
1
2
Synthesis of [2,2':6',2''-terpyridin]-6-ol (L1b): A 50 mL Schlenk flask
was charged with 6-methoxy-2,2':6',2''-terpyridine (S-1) (0.5 g, 1.9 mmol),
6
1
the resulting solution was neutralized by slow addition of a saturated
aqueous solution of NaOH. The resulting off-white precipitate was filtered
and then dried to afford L1b as a off-white solid (0.43 g, 90%). Mp:
2
2
8
1
8
H13Cl
2
3
ml HBr (40% in water) under air. The reaction mixture was stirred at
o
00 C for 12 h. Then the mixture was cooled to room temperature, and
Synthesis of L2b-CoCl
105 mg, 0.4 mmol), CoCl
atmosphere of nitrogen, the mixture was stirred at room temperature for
2 h. Removing the solvent by filtration afforded a red powder. The cake
was washed with ether and dried in vacuum to give L1b-CoCl (135 mg,
6% yield); Crystals of L2b-CoCl suitable for X-ray diffraction were
obtained by diffusing the ether vapor to saturated methanol solution of
L2b-CoCl (CCDC: 1891470). Anal. Calcd. For C16 CoN O: C,
8.88; H, 3.33; N, 10.69. Found C, 48.99; H, 3.36; N, 10.61.
2
: A 10 mL Schlenk flask was charged with L2b
(
2
(52 mg, 0.4 mmol) and 5 mL THF under the
1
02.1~204.3 oC. HR-MS (ESI, m/z): Calcd for C15
H N
11 3
O+ [M+H] +
:
2
1
50.0980; found: 250.0974. H NMR (DMSO, 400 MHz) δ 11.37 (s, 1H),
.83 – 8.65 (m, 2H), 8.49 – 8.39 (d, J = 7.6 Hz, 1H), 8.20 (d, J = 7.6 Hz,
H), 8.10 (t, J = 8.0 Hz, 1H), 8.02 (td, J = 7.8, 1.6 Hz, 1H), 7.66 (t, J = 8.0
8
2
2
H13Cl
2
3
Hz, 1H), 7.51 (dd, J = 7.2, 5.2 Hz, 1H), 7.32 (s, 1H), 6.55 (d, J = 8.9 Hz,
1
1
4
H). 13C NMR (DMSO, 101 MHz) δ 163.0, 155.5, 155.1, 149.7, 141.2,
39.3, 137.9, 125.0, 121.9, 121.6, 121.4.
Synthesis of L2b-CoBr
2
: A 10 mL Schlenk flask was charged with L2b
(87 mg, 0.4 mmol) and 5 mL THF under the
(105 mg, 0.4 mmol), CoBr
2
Synthesis
of
[2,2'-bipyridin]-6-yl(6-(tert-butoxy)pyridin-2-
atmosphere of nitrogen, and the mixture was stirred at room temperature
for 12 h. Removing the solvent by filtration afforded a red powder. The
yl)methanone (S-2): To a solution of n-BuLi (1.92 mL, 2.5 M, 4.8 mmol)
in 10 mL dry tetrahydrofuran was added 2-bromo-6-(tert-butoxy)pyridine
cake was washed with ether and dried in vacuum to afford L2b-CoBr
160 mg, 83% yield); Anal. Calcd. For C16 CoN O: C, 39.87; H,
2
(1.1 g, 4.8 mmol) in 15 mL tetrahydrofuran at −78 °C. After 1 h of stirring
(
H13Br
2
3
at −78 °C, methyl [2,2'-bipyridine]-6-carboxylate (1.03 g, 4.8 mmol) was
added. The reaction mixture was stirred at −20 °C for 3 h and left at room
temperature overnight. After addition of 20 mL of water the reaction
mixture was extracted with dilute HCl. The water phase was neutralized
by NaOH in water and extracted with dichloromethane. The crude
product was purified by column chromatography on silica gel (petroleum
2
.72; N, 8.72. Found C, 39.95; H, 2.74; N, 8.73.
Synthesis of L2c-CoCl
2
: A 10 mL Schlenk flask was charged with L2c
(111 mg, 0.4 mmol), CoCl (52 mg, 0.4 mmol) and 5 mL THF under the
2
atmosphere of nitrogen, and the mixture was stirred at room temperature
for 12 h. Removing the solvent by filtration afforded brown powder. The
ether/ethyl acetate = 8:1, to give S-2 (1.39 g, 87%). HR-MS (ESI, m/z):
cake was washed with ether and dried in vacuum to afford L2c-CoCl
148 mg, 91% yield); Crystals of L2c-CoCl suitable for X-ray diffraction
2
+
[M+H] +, 334.1556. Found, 334.1562. 1H NMR
Calcd for C20H N O
19 3 2
(
2
(400 MHz, CDCl
3
, ppm) 8.69 – 8.63 (m, 1H), 8.60 (dd, J = 8, 0.8 Hz, 1H),
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were obtained by diffusing the ether vapor to saturated methanol solution
eq.) was added in the same pot after the hydrosilylation step was finished,
of L2c-CoCl
2
(CCDC: 1910055). Anal. Calcd. For C17
H15Cl
2 3
CoN O: C,
7a could also isolated in 70% yield (101 mg).
50.15; H, 3.71; N, 10.32. Found C,50.11; H, 3.77; N, 10.25.
Diphenyl(1-phenylvinyl)silane(3a).[17] General Procedure
white solid (148 mg, 86%). Mp.: 58.9 ~ 60.2 °C. H NMR (CDCl
A
give
a
1
Synthesis of L2d-CoCl
2
: A 10 mL Schlenk flask was charged with L2d
(52 mg, 0.4 mmol) and 5 mL THF under the
3
, 400
(128 mg, 0.4 mmol), CoCl
2
MHz) δ 7.59 – 7.54 (m, 4H), 7.42 – 7.32 (m, 8H), 7.26 – 7.17 (m, 3H),
6.28 (dd, J = 2.4, 0.8 Hz, 1H), 5.68 (d, J = 2.4 Hz, 1H), 5.39 (s, J = 0.9 Hz,
1H).
atmosphere of nitrogen, and the mixture was stirred at room temperature
for 12 h. Removing the solvent by filtration afforded dark green powder.
The cake was washed with ether and dried in vacuum to afford L2d-
CoCl
2
(162 mg, 90% yield); Anal. Calcd. For C20
H21Cl
2 3
CoN O: C, 53.47;
Diphenyl(1-(p-tolyl)vinyl)silane (3b).[17] General Procedure A give a
H, 4.71; N, 9.35. Found C,53.41; H, 4.78; N, 9.37.
white solid (162 mg, 90%). Mp.: 64.2 ~ 65.5 oC. 1H NMR (CDCl
3
, 400
MHz) δ 7.65 – 7.56 (m, 4H), 7.48 – 7.36 (m, 6H), 7.33 – 7.26 (m, 2H),
7.11 (d, J = 8 Hz, 2H), 6.33 (dd, J = 2, 0.4 Hz, 1H), 5.69 (d, J = 2.4 Hz,
1H), 5.44 (s, 1H), 2.35 (s, 3H).
General Procedure for Cobalt-Catalyzed Hydrosilylation of Terminal
Alkynes and Internal Alkyl Alkynes (General Procedure A). In a
nitrogen filled glovebox, the cobalt complex L2b-CoCl
Ph SiH (0.6 mmol), and anhydrous THF (2 mL) were added into a 10 mL
Schlenk tube with a magnetic stirring bar. The mixture was injected with
NaBEt H (1.0 M) (36 μL, 0.06 mmol) by dropwise and then the alkyne
0.6 mmol) was added to the reaction mixture. The reaction mixture was
stirred for 5 min at room temperature and then quenched by exposed the
solution to air. The resulting solution was concentrated in vacuum and
the crude product was purified directly by silica gel column
chromatography eluting with petroleum ether and ethyl acetate to afford
the corresponding product.
2
(4.7 mg, 2 mol%),
2
2
[17b]
Diphenyl(1-(m-tolyl)vinyl)silane (3c).
General Procedure A give a
3
, 400 MHz) δ 7.59 – 7.53 (m,
1
colorless oil (161 mg, 89%). H NMR (CDCl
3
4
(
3
H), 7.39 – 7.31 (m, 6H), 7.18 – 7.10 (m, 3H), 7.04 – 6.98(m, 1H), 6.26
dd, J = 2.8, 1.2 Hz, 1H), 5.66 (d, J = 2.8 Hz, 1H), 5.39 (s, 1H), 2.27 (s,
H).
(
(
1-(4-Methoxyphenyl)vinyl)diphenylsilane (3d).[17] General Procedure
A give a white solid (182 mg, 96%). Mp.: 71.3 ~ 72.1 C. H NMR (CDCl ,
3
00 MHz,) δ 7.60 – 7.53 (m, 4H), 7.41 – 7.29 (m, 8H), 6.83 – 6.75 (m,
H), 6.25 (dd, J = 2.4, 0.8 Hz, 1H), 5.61 (d, J = 2.4 Hz, 1H), 5.41 (s, 1H),
o
1
4
2
3
General Procedure for Cobalt-Catalyzed Hydrosilylation of Internal
.75 (s, 3H).
Diaryl Alkynes (General Procedure B). In a nitrogen filled glovebox, the
cobalt complex L2c-CoCl
mL) were added into a 10 mL Schlenk tube with a magnetic stirring bar.
The mixture was injected with NaBEt H (1.0 M) (15 μL, 3 mol%) by
dropwise and then the alkyne (0.5 mmol) and Ph SiH (0.5 mmol) in 1 ml
2
(2.04 mg, 1 mol%), and anhydrous THF (1
(
1-(3-Methoxyphenyl)vinyl)diphenylsilane (3e). General Procedure A
1
give a colorless oil (176 mg, 93%). H NMR (CDCl
7
6
3
, 400 MHz) δ 7.60 –
3
.50 (m, 4H), 7.42 – 7.32 (m, 6H), 7.20 – 7.10 (t, J = 7.92 Hz, 1H), 6.96 –
.89 (m, 1H), 6.87 – 6.83 (t, J = 2.0 Hz, 1H), 6.79 – 6.70 (m, 1H), 6.28
2
2
THF were added to the reaction mixture. The reaction mixture was stirred
for 5 min at room temperature and then quenched by exposing the
solution to air. The resulting solution was concentrated in vacuum and
the crude product was purified directly by silica gel column
chromatography eluting with petroleum ether and ethyl acetate to afford
the corresponding product.
(
3
1
dd, J = 2.4, 0.8 Hz, 1H), 5.69 (d, J = 2.8 Hz, 1H), 5.37 (s, 1H), 3.67 (s,
H). 13C NMR (CDCl
3
, 101 MHz) δ 159.5, 145.9, 144.5, 135.8, 133.1,
32.3, 129.9, 129.4, 128.1, 119.3, 112.9, 112.1, 55.1. HRMS-EI (m/z):
Calcd for [C21
H20OSi+], 316.1283; found: 316.1291.
1-(4-Fluorophenyl)vinyl)diphenylsilane (3f).[
17a]
General Procedure A
, 400 MHz) δ 7.62 –
.57 (m, 4H), 7.46 – 7.37 (m, 6H), 7.35 – 7.30 (m, 2H), 7.01 – 6.94 (m,
(
1
give a colorless oil (166 mg, 91%). H NMR (CDCl
7
2
3
General Procedure for Tamao Oxidation of α-Vinylsilanes (General
Procedure C). A Schlenk tube was charged with KHCO
3
(250 mg, 2.5
H), 6.27 (d, J = 2.4 Hz, 1H), 5.72 (d, J = 2.4 Hz, 1H), 5.42 (s, 1H).
mmol), 3 (0.5 mmol, 1.0 equiv.), THF (8 mL), MeOH (8.0 mL), and then
3
0% H
2
O
2
aq. (567 mg, 5.0 mmol) was added to the tube. The resulting
17a]
(
1-(3-Fluorophenyl)vinyl)diphenylsilane (3g).[
General Procedure A
3
, 400 MHz) δ 7.63 –
o
mixture was stirred at 60 C for 10 h before a saturated aqueous solution
1
give a colorless oil (163 mg, 89%). H NMR (CDCl
.57 (m, 4H), 7.48 – 7.37 (m, 6H), 7.25 – 7.20 (m, 1H), 7.17 – 7.05 (m,
H), 6.98-6.90 (m, 1H), 6.32 (dd, J = 2.4, 0.8 Hz, 1H), 5.76 (d, J = 2.4 Hz,
of Na
ethyl acetate and washed with brine (20 mL), dried over anhydrous
Na SO . After filtration and evaporation of the solvent, the residue was
2 2 3
S O (5 mL) was added. The resulting solution was extracted with
7
2
1
2
4
H), 5.43 (s, 1H).
purified by flash column chromatography to give the product 6.
(
1-(4-Chlorophenyl)vinyl)diphenylsilane (3h).[17a] General Procedure A
General Procedure for Hydrogenation of α-Vinylsilanes (General
Procedure D). In a nitrogen filled glovebox, the cobalt complex L2b-
CoCl (5.9 mg, 3 mol%), PhSiH (108 mg, 1 mmol, 2 eq), 3a (144 mg, 0.5
2
3
mmol, 1 eq) and anhydrous THF (2 mL) were added into a 10 mL
Schlenk tube with a magnetic stirring bar. The mixture was injected with
3
NaBHEt (1.0 M) (45 μL, 0.045 mmol) by dropwise. The reaction mixture
was stirred for 24 hours at room temperature, the resulting solution was
concentrated in vacuum and the crude product was purified directly by
silica gel column chromatography eluting with petroleum ether and ethyl
acetate to afford 7a (113 mg, 78%).
o
1
3
give a white solid (160 mg, 83%). Mp.: 71.9 ~ 73.2 C. H NMR (CDCl ,
4
6
00 MHz) δ 7.58 – 7.49 (m, 4H), 7.41 – 7.32 (m, 6H), 7.28 – 7.15 (m, 4H),
.29 – 6.19 (m, 1H), 5.69 (d, J = 2.4 Hz, 1H), 5.37 (s, 1H).
1-(2-Chlorophenyl)vinyl)diphenylsilane (3i).[
17a]
General Procedure A
, 400 MHz) δ 7.64 –
(
1
give a colorless oil (127 mg, 66%). H NMR (CDCl
7
1
3
.56 (m, 4H), 7.44 – 7.32 (m, 7H), 7.20 – 7.11 (m, 2H), 7.10 – 7.05 (m,
H), 6.10 (dd, J = 2.8, 1.2 Hz, 1H), 5.90 (d, J = 2.4 Hz, 1H), 5.31 (s, 1H).
(
1-(4-Bromophenyl)vinyl)diphenylsilane (3j).[17] General Procedure A
o
1
3
give a white solid (171 mg, 78%). Mp.: 83.7 ~ 84.6 C. H NMR (CDCl ,
4
Alternatively, if 3a was not isolated and purified from the reaction of L2b-
00 MHz) δ 7.64 – 7.55 (m, 4H), 7.49 – 7.36 (m, 8H), 7.27 – 7.18 (m, 2H),
CoCl
2
(5.9 mg, 3 mol%), Ph
2
SiH
2
(92 mg, 0.5 mmol), NaBEt
3
H (9 mol%)
6.35 – 6.24 (m, 1H), 5.76 (d, J = 2.4 Hz, 1H), 5.42 (s, 1H).
and phenylacetylene (51 mg, 0.5 mmol), and PhSiH
3
(108 mg, 1 mmol, 2
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(
1-(3-Bromophenyl)vinyl)diphenylsilane (3k). General Procedure A
7.51 (m, 4H), 7.39 – 7.30 (m, 6H), 5.90 (t, J = 7.0 Hz, 1H), 5.10 (s, 1H),
2.26 – 2.10 (m, 4H), 1.46 – 1.25 (m, 4H), 0.91 (t, J = 7.4 Hz, 3H), 0.82 (t,
J = 7.2 Hz, 3H).
1
give a colorless oil (159 mg, 72%). H NMR (CDCl
7
3
, 400 MHz) δ 7.60 –
.54 (m, 4H), 7.50 (t, J = 1.8 Hz, 1H), 7.47 – 7.32 (m, 7H), 7.25 – 7.20 (m,
H), 7.1 (t, J = 7.8 Hz, 1H), 6.25 (dd, J = 2.4, 0.8 Hz, 1H), 5.73 (d, J = 2.4
, 101 MHz) δ 145.2, 145.0, 135.8,
35.5, 133.3, 132.5, 130.0, 129.9, 129.5, 128.2, 125.7, 122.6. HRMS-EI
m/z): Calcd for [C20 17BrSi+], 364.0283; found: 364.0278.
1
Hz, 1H), 5.39 (s, 1H). 13C NMR (CDCl
3
[17b],[12a]
(
E)-(1,2-diphenylvinyl)diphenylsilane (5a).
General Procedure
, 400 MHz): δ
1
(
1
B give a colorless oil (167 mg, 92% yield). H NMR (CDCl
3
H
7
1
.61 – 7.53 (m, 4H), 7.40 – 7.31 (m, 6H), 7.20 – 6.93 (m, 11H), 5.28 (s,
H).
Diphenyl(1-(4-(trifluoromethyl)phenyl)vinyl)silane (3l).[17a] General
Procedure A give a colorless oil (149 mg, 70%). 1H NMR (CDCl
, 400
MHz) δ 7.66 – 7.49 (m, 6H), 7.49 – 7.32 (m, 8H), 6.33 (d, J = 2 Hz, 1H),
3
(
E)-(1,2-di-p-tolylvinyl)diphenylsilane (5b).[12a] General Procedure B
give a white soild (184 mg, 94%). Mp: 63.2 ~ 64.7 oC. 1H NMR (CDCl
3
,
5.81 (d, J = 2 Hz, 1H), 5.42 (s, 1H).
400 MHz): δ 7.58 – 7.53 (m, 4H), 7.41 – 7.30 (m, 6H), 7.00 (d, J = 8 Hz,
2
H), 6.95 – 6.88 (m, 7H), 5.25 (s, 1H), 2.28 (s, 3H), 2.23 (s, 3H).
4
-(1-(Diphenylsilyl)vinyl)aniline (3m).[17b] General Procedure A give a
yellow solid (154 mg, 85%). Mp.: 80.9 ~ 82.2 oC. 1H NMR (CDCl
3
, 400
(
E)-(1,2-di-m-tolylvinyl)diphenylsilane (5c). General Procedure B give
MHz): δ 7.58 – 7.49 (m, 4H), 7.41 – 7.30 (m, 6H), 7.23 – 7.14 (m, 2H),
1
a colorless oil (182 mg, 93%). H NMR (CDCl
3
, 400 MHz): δ 7.59 – 7.54
6
.61 – 6.53 (m, 2H), 6.21 (dd, J = 2.4, 0.8 Hz, 1H), 5.52 (d, J = 2.4 Hz,
(
6
m, 4H),7.42 – 7.32 (m, 6H), 7.08 (t, J = 7.8 Hz, 1H), 6.98 – 6.90 (m, 4H),
1H), 5.38 (s, 1H), 3.81 (br, 2H).
.85 – 6.76 (m, 4H), 5.26 (s, 1H), 2.19 (s, 3H), 2.15 (s, 3H). 13C NMR
(
3
CDCl , 100 MHz): δ 142.80, 141.63, 140.06, 138.07, 137.46, 136.93,
Diphenyl(1-(thiophen-2-yl)vinyl)silane (3n).[17b] General Procedure A
135.93, 133.24, 130.74, 129.77, 128.65, 128.48, 128.32, 127.99, 127.81,
126.88, 126.59, 125.09, 21.45, 21.33. HRMS-EI (m/z): Calcd for
1
give a colorless oil (151 mg,86 %). H NMR (CDCl
3
, 400 MHz): δ 7.63 –
7
6
5
.56 (m, 4H), 7.33 – 7.45 (m, 6H), 7.12 (dd, J = 5.2, 0.8 Hz, 1H), 6.94 –
.89 (m, 1H), 6.88 – 6.82(m, 1H), 6.33 (s, 1H), 5.50 (d, J = 1.6 Hz, 1H),
.41 (s, 1H).
[C28
H
26Si+], 390.1804; found: 390.1809.
E)-(1,2-bis(4-methoxyphenyl)vinyl)diphenylsilane (5d).[12a] General
(
o
1
Procedure B give a white soild (203 mg, 96%). Mp.: 123 ~ 125.3 C. H
NMR (CDCl , 400 MHz): δ 7.58 – 7.51 (m, 4H), 7.42 – 7.32 (m, 6H), 6.98
– 6.89 (m, 5H), 6.76 (d, J = 8.8 Hz, 2H), 6.64 (d, J = 8.8 Hz, 2H), 5.25 (s,
3
-(1-(Diphenylsilyl)vinyl)pyridine (3o).[17] General Procedure A give a
3
colorless oil (110 mg,64 %). 1H NMR (CDCl
, 400 MHz): δ 8.58 (d, J =
.6 Hz, 1H), 8.44 (dd, J = 4.8, 1.6 Hz, 1H), 7.59 – 7.52 (m, 5H), 7.45 –
.33 (m, 6H), 7.20 – 7.11(m, 1H), 6.30 (dd, J = 2.4, 0.8 Hz, 1H), 5.80 (d,
3
1
7
1H), 3.76 (s, 3H), 3.72 (s, 3H).
J = 2.4 Hz, 1H), 5.38 (s, 1H).
(5e).[12a]
(
E)-(1,2-bis(4-fluorophenyl)vinyl)diphenylsilane
General
Procedure B give a white soild (189 mg, 95%). Mp.: 52.7 ~ 54.5 oC. 1
H
(
1-(Cyclohex-1-en-1-yl)vinyl)diphenylsilane
Procedure A give a colorless oil (159 mg, 91%). 1H NMR (CDCl
MHz): δ 7.61 – 7.50 (m, 4H), 7.46 – 7.30 (m, 6H), 6.00 (s, 1H), 5.98 –
(3p).[17a]
General
NMR (CDCl
3
, 400 MHz): δ 7.57 – 7.52 (m, 4H), 7.43 – 7.33 (m, 6H), 6.99
3
, 400
– 6.86 (m, 7H), 6.79 (t, J = 8.8 Hz, 2H), 5.27 (s, 1H).
5
2
.92(m, 1H), 5.36 (d, J = 2 Hz, 1H), 5.33 (s, 1H), 2.30 – 2.21 (m, 2H),
.15 – 2.00 (m, 2H), 1.77 – 1.67 (m, 2H), 1.62 – 1.49 (m, 2H).
(
E)-(2-(4-methoxyphenyl)-1-phenylvinyl)diphenylsilane and (E)-(1-(4-
methoxyphenyl)-2-phenylvinyl)diphenylsilane (5f). General
Procedure B give a colorless oil (188 mg, 96%). H NMR (CDCl , 400
1
3
Oct-1-en-2-yldiphenylsilane (3q).[13a] General Procedure
colorless oil (162 mg, 92% yield). 1H NMR (CDCl
, 400 MHz): δ 7.58 –
.54 (m, 4H), 7.42 – 7.34 (m, 6H), 5.87 (s, 1H), 5.46 (d, J = 2.8 Hz, 1H),
.09 (s, 1H), 2.25 – 2.15 (m, 2H), 1.45 – 1.36 (m, 2H), 1.28 – 1.15 (m,
H), 0.89 – 0.78 (m, 3H).
A
give
a
MHz): δ 7.59 – 7.53 (m), 7.41 – 7.30 (m), 7.23-7.07 (m), 7.04 – 6.99 (m),
6.98 (s), 6.95 – 6.89 (m), 6.74 (d, J = 8.8 Hz), 6.62 (d, J = 8.8 Hz, 2H),
3
7
5
6
5.28 (s), 5.26 (s, 1H), 3.74 (s), 3.70 (s, 3H). 13C NMR (CDCl
3
, 100 MHz):
δ 159.02, 158.11, 142.91, 142.36, 141.98, 139.61, 137.52, 137.18,
135.91, 133.68, 133.30, 133.24, 131.16, 129.78, 129.68, 129.28, 128.75,
128.18, 128.05, 128.01, 127.48, 126.11, 114.16, 113.40, 55.15. HRMS-
1-(Naphthalen-1-yl)vinyl)diphenylsilane (3r).[17a] General Procedure A
give a white solid. Mp.: 55.3 ~ 57.1 oC. (129 mg, 64% yield). 1H NMR
CDCl , 400 MHz): δ 8.05 (d, J = 8.0 Hz, 1H), 7.82 (d, J = 8.0 Hz, 1H),
.69 (d, J = 8.4 Hz, 1H), 7.57 (d, J = 6.4 Hz, 4H), 7.47 – 7.30 (m, 9H),
.11 (d, J = 6.8 Hz, 1H), 6.15 (d, J = 2.8 Hz, 1H), 6.09 (d, J = 3.2 Hz, 1H),
.28 (s, 1H).
EI (m/z): Calcd for [C27 24OSi+], 392.1596; found: 392.1585.
H
(
(
3
(E)-(2-(2-methoxyphenyl)-1-phenylvinyl)diphenylsilane and (E)-(1-(2-
methoxyphenyl)-2-phenylvinyl)diphenylsilane (5g). General
Procedure B give a colorless oil (183 mg, 93%). H NMR (CDCl , 400
MHz): δ 7.58 (d, J = 7.6 Hz), 7.41 – 7.26 (m), 7.18 – 6.97 (m), 6.94 –
.89 (m, 1H), 6.82 – 6.70 (m), 6.55 (t, J = 7.6 Hz), 5.34 (s), 5.21 (s, 1H),
3.73 (s), 3.42 (s, 3H). , 100 MHz): δ 157.75, 156.23,
13C NMR (CDCl
143.11, 141.90, 139.16, 138.63, 137.46, 136.92, 136.00, 135.82, 134.08,
7
7
5
1
3
6
1-(Naphthalen-2-yl)vinyl)diphenylsilane (3s).[17a] General Procedure A
give a white solid. Mp.: 91.2 ~ 92.6 oC. (182 mg, 90% yield). 1H NMR
CDCl , 400 MHz): δ 7.80 – 7.68 (m, 4H), 7.63 – 7.56 (m, 4H), 7.53 –
.49 (m, 1H), 7.43 – 7.32 (m, 8H), 6.40 (d, J = 2 Hz, 1H), 5.78 (d, J = 3.2
Hz, 1H), 5.50 (s, 1H).
3
(
1
1
1
3
33.54, 130.61, 130.44, 129.75, 129.52, 129.31, 129.19, 128.79, 128.44,
28.42, 128.03, 128.00, 127.83, 127.52, 126.27, 126.05, 120.92, 119.84,
10.79, 110.65, 55.56, 54.95. HRMS-EI (m/z): Calcd for [C27H24OSi+],
92.1596; found: 392.1587.
(
3
7
(
E)-Hex-4-en-4-yldiphenylsilane (3t).[17b] General Procedure A give a
colorless oil (137 mg, 86% yield). 1H NMR (CDCl
, 400 MHz): δ 7.59 –
.52 (m, 4H), 7.42 – 7.30 (m, 6H), 5.90 (t, J = 7.2 Hz, 1H), 5.07 (s, 1H),
(E)-(2-([1,1'-biphenyl]-4-yl)-1-phenylvinyl)diphenylsilane and (E)-(1-
3
(
[1,1'-biphenyl]-4-yl)-2-phenylvinyl)diphenylsilane
(5h).
General
, 400
7
2
1
Procedure B give a colorless oil (208 mg, 95%). H NMR (CDCl
3
.30 – 2.14 (m, 4H), 0.98 (t, J = 7.6 Hz, 3H), 0.89 (t, J = 7.6 Hz, 3H).
MHz): δ 7.62 – 7.55 (m), 7.52 – 7.48 (m, 2H), 7.46 (d, J = 8.4 Hz), 7.42 –
7.33 (m), 7.32 – 7.27 (m), 7.23 – 7.15 (m, 3H), 7.12 – 7.02 (m, 14H), 5.32
(
E)-Oct-4-en-4-yldiphenylsilane (3u).[17b] General Procedure A give a
colorless oil (142 mg, 80% yield). 1H NMR (CDCl
, 400 MHz): δ 7.57 –
(s), 5.30 (s, 1H). 13C NMR (CDCl
3
, 100 MHz): δ 143.15, 142.39, 141.75,
3
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1
1
1
40.75, 140.52, 140.43, 140.18, 139.77, 138.73, 136.98, 135.94, 135.92,
33.04, 130.19, 129.90, 129.87, 129.74, 128.78, 128.59, 128.09, 128.07,
27.66, 127.38, 127.26, 127.18, 126.93, 126.85, 126.63, 126.29. HRMS-
The authors declare no conflict of interest.
Keywords: hydrosilylation • alkynes • Markovnikov
regioselectivity • cobalt complexes • E-selective
EI (m/z): Calcd for [C32
H26Si+], 438.1804; found: 438.1811.
(
E)-(2-(4-fluorophenyl)-1-phenylvinyl)diphenylsilane and (E)-(1-(4-
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fluorophenyl)-2-phenylvinyl)diphenylsilane (5i). General Procedure B
give a colorless oil (183 mg, 96%). H NMR (CDCl
1
3
, 400 MHz): δ 7.58 –
7
3
=
1
1
1
1
.53 (m, 8H), 7.42 – 7.32 (m, 12H), 7.22 – 7.14 (m, 3H), 7.13 – 7.09 (m,
H), 7.02 (s, 1H), 7.00 – 6.92 (m, 9H), 6.88 (t, J = 8.8 Hz, 2H), 6.77 (t, J
8.8 Hz, 2H), 5.28 (s, 2H). 13C NMR(CDCl
, 100 MHz): δ 163.17, 162.75,
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60.72, 160.31, 143.49, 141.57, 141.37, 139.98, 139.15, 137.33, 136.80,
35.87, 133.14, 132.93, 132.79, 131.44, 131.35, 129.95, 129.89, 129.74,
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(
E)-(2-(2,6-dimethylphenyl)-1-phenylvinyl)diphenylsilane
(5j).
o
General Procedure B give a white soild (59 mg, 30%). Mp: 91.9 ~ 92.6 C.
1H NMR (CDCl
6
1
3
, 400 MHz): δ 7.58 (d, J = 6.8 Hz, 4H), 7.43 – 7.31 (m,
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H), 7.14 – 7.01 (m, 5H), 7.00 – 6.90 (m, 4H), 5.15 (s, 1H), 1.96 (s, 6H).
3C NMR (CDCl
3
, 100 MHz): δ 142.02, 140.14, 139.26, 137.65, 135.87,
1
34.43, 133.25, 129.79, 128.56, 128.32, 127.96, 127.86, 126.25, 20.44.
HRMS-EI (m/z): Calcd for [C28H26Si+], 390.1804; found: 390.1820.
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3
, 400 MHz) δ 7.97 – 7.92(m, 2H), 7.55 (t, J =
7
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-(Naphthalen-2-yl)ethan-1-one (6s).[28] General Procedure C give a
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MHz) δ 8.47 (s, 1H), 8.04 (dd, J = 8.8, 1.6 Hz, 1H), 7.55 (d, J = 8 Hz, 1H),
.92 – 7.85(m, 2H), 7.64 – 7.51(m, 2H), 2.73 (s, 3H).
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7
Diphenyl(1-phenylethyl)silane (7a). General Procedure
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D give a
1
3
, 400 MHz): δ (ppm) 7.64 –
1
33, 20712-20715.
7
2
1
.58 (m, 2H), 7.51 – 7.40 (m, 6H), 7.39 – 7.32 (m, 2H), 7.30 – 7.24 (m,
H), 7.21 – 7.14 (m, 1H), 7.10 (d, J = 7.2 Hz, 2H), 4.93 (d, J = 3.2 Hz,
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Highly Regio- and Stereo-Selective
Hydrosilylation of Alkynes Catalyzed
by Tridentate Cobalt Complexes
C
Two N NN-CoCl
2
complexes are highly efficient catalysts for alkyne hydrosilylation,
affording vinylsilanes with α-selectivity (for terminal alkynes) and E-selectivity (for
internal alkynes).
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