[Rh(Cod)Cl]2/Pph3?catalyzed dehydrogenative silylation of styrene derivatives with NBE as a hydrogen acceptor

Article abstract of DOI:10.1021/acs.organomet.0c00242

Direct synthesis of arylalkenylsilanes by [Rh(COD)Cl]₂/ PPh₃-catalyzed dehydrogenative silylation of styrene derivatives with R₃SiH (R = alkyl, alkoxy, aryl) was realized, in which norbornene (NBE) and PPh₃ play a key role in achieving excellent selectivity in the formation of dehydrogenative silylation products. Moreover, this high-yielding transformation exhibits a broad substrate scope and good functional group tolerance.

Full text of DOI:10.1021/acs.organomet.0c00242

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[Rh(COD)Cl]2/PPh3‑Catalyzed Dehydrogenative Silylation of Styrene
Derivatives with NBE as a Hydrogen Acceptor
Wenkui Lu, Chengyang Li, Xiaoyu Wu, Xiaomin Xie,* and Zhaoguo Zhang*
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ABSTRACT: Direct synthesis of arylalkenylsilanes by [Rh(COD)Cl]2/
PPh3-catalyzed dehydrogenative silylation of styrene derivatives with
R3SiH (R = alkyl, alkoxy, aryl) was realized, in which norbornene (NBE)
and PPh3 play a key role in achieving excellent selectivity in the
formation of dehydrogenative silylation products. Moreover, this high-
yielding transformation exhibits a broad substrate scope and good
functional group tolerance.
precious metals such as rhodium, iridium, ruthenium,
platinum, and palladium.5 For example, Falck and Hartwig
reported the Z-selective dehydrogenative silylation of terminal
aliphatic alkenes catalyzed by iridium complexes and nitrogen
ligands, respectively.5c,d Examples with earth-abundant metal
catalysts including iron, cobalt, nickel, copper, and manganese
catalytic systems also have been reported recently.6 Chirik and
co-workers developed a bis(imino)pyridine cobalt-catalyzed
dehydrogenative silylation of alkyl alkenes to generate
allylsilanes.6d Xu and co-workers developed a synergistic
combination of photoredox, hydrogen atom transfer, and
cobalt catalysis to synthesize allylsilanes from methacrylic acid
derivatives.6e In spite of the significant progress in the direct
dehydrogenative silylation of alkenes, there have only been a
few reports on the highly selective dehydrogenative silylation
of arylalkenes. Jeon demonstrated the dehydrogenative
silylation of vinylarenes catalyzed by ruthenium alkylidenes
with the addition of cyclooctadiene as the sacrificial hydrogen
acceptor (Scheme 1b).5f Wang and co-workers achieved
Mn2(CO)10-catalyzed dehydrogenative silylation of aryl olefins
with special hydrosilanes (Scheme 1c).6j Lu and co-workers
reported a imidazoline iminopyridine cobalt complex catalyzed
dehydrogenative silylation of vinylarenes.6f
INTRODUCTION
■
Alkenylsilanes are versatile synthetic intermediates and
building blocks in numerous materials science/polymer
applications.1,2 Diverse transformations of alkenylsilanes were
also achieved to give various useful building blocks, including
allylic alcohols, allylic amines, and alkenyl halides.2e Accord-
ingly, effective approaches for preparing alkenylsilanes are
highly desirable. A variety of procedures are extant for the
preparation of alkenylsilanes, including the silyl-Heck reac-
tion,3 alkyne hydrosilylation,4 and dehydrogenative silylation
of alkenes (Scheme 1a). Direct dehydrogenative silylation of
alkenes is a more favorable access because alkenes are
inexpensive and readily available (Scheme 1a).5,6 Most
catalysts for the dehydrogenative silylation of alkenes rely on
Scheme 1. Common Approaches to Vinylsilanes
Although there have been some reports on rhodium/PPh3-
catalyzed dehydrogenative silylation of alkenes since the early
1980s, only a few catalytic systems have shown high selectivity.
Takeuchi and co-workers reported a [Rh(COD)2]BF4/PPh3-
catalyzed highly selective dehydrogenative silylation of styrene
with tertiary hydrosilanes, but the selectivity was strongly
Received: April 5, 2020
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a
dependent on the reaction temperature, the molar ratio of
styrene to hydrosilane, and the steric bulkiness of the
hydrosilane (Scheme 1d).7a In the dehydrogenative silylation
reactions of alkenes with hydrosilanes, the generation of
alkenylsilanes is always accompanied by the formation of metal
hydrogen species which may result in side reactions, such as
isomerization and reduction of alkenes and further reduction of
dehydrogenative silylation products.8,9 Therefore, the prompt
consumption of the hydrogen species is crucial for achieving
dehydrogenative silylation product in good yield and
selectivity. The hydrogen species may be transferred to H2
which escapes from the reaction system6e or be absorbed by
large excess of the alkene substrates as sacrificial hydrogen
acceptors.7a In addition, adding extra hydrogen acceptors is an
important approach to consume the hydrogen species, which
may suppress the reduction of alkenes and improve the
selectivity for the dehydrogenative silylation.5f Herein, we
report a rhodium/PPh3-catalyzed dehydrogenative silylation of
styrene derivatives with NBE as a hydrogen acceptor to give
alkenylsilanes in an effective and highly selective way.
Table 1. Optimization of Reaction Conditions
b
yield (%)
entry
ligand (x (mol %))
additive (equiv)
3aa
4aa
5a
c
1
15
23
27
78
67
30
73
22
18
40
0
2
3
PPh3 (4)
c
NBE
4
5
6
7
8
9
PPh3 (4)
PPh3 (4)
PPh3 (4)
PPh3 (4)
PPh3 (4)
NBE
NBD
cyclohexene
COD
dicyclopentadiene
NBE
0
36
55
8
58
32
34
92
93
95
96
96
95
88
70
51
3
28
68
66
6
4
3
3
3
3
8
0
0
0
1
2
2
1
1
2
4
0
6
0
10
11
12
13
14
15
16
17
18
19
20
21
PPh3 (2)
PPh3 (6)
PPh3 (8)
PPh3 (10)
PPh3 (12)
PPh3 (15)
PPh3 (20)
P(p-tol)3 (10)
P(o-tol)3 (10)
P(4-MeOPh)3 (10)
P(C6F5)Ph2 (10)
Dppp (5)
NBE
NBE
NBE
NBE
NBE
NBE
NBE
NBE
NBE
NBE
NBE
NBE
NBE
NBE
RESULTS AND DISCUSSION
■
The Wilkinson catalyst showed good reactivity and selectivity
for the dehydrogenative silylation of the terminal alkenes of
1,5-dienes.7b,10 Therefore, we examined the dehydrogenative
silylation of styrene 1a and 2 equiv of Et3SiH (2a) with
RhCl(PPh3)3 or [Rh(COD)Cl]2/PPh3 as the catalyst. The
reaction catalyzed by the Wilkinson catalyst gave the
hydrosilylation product 4aa as the main product in 67%
yield, the dehydrogenative silylation product 3aa in only 15%
yield, and the reduction product 5a in 18% yield (Table 1,
entry 1). When [Rh(COD)Cl]2 was used as the precatalyst
and 4 equiv of PPh3 was used as the ligand, the ratio of
products obviously changed. The yield of the hydrosilylation
product 4aa decreased, but the yield of the reduction product
5a increased (Table 1, entry 2). We attempted to add the extra
hydrogen acceptor in the dehydrogenative silylation to inhibit
the formation of the saturated (reduction) products 4aa and
5a. Norbornene (NBE), which coordinates easily with late
transition metals and is not prone to react with hydrosilanes in
the presence of terminal alkenes, was used first as the sacrificial
hydrogen acceptor. The reduction of styrene (1a) was
inhibited completely in both RhCl(PPh3)3 and [Rh(COD)-
Cl]2/PPh3 catalytic systems (Table 1, entries 3 and 4). In the
[Rh(COD)Cl]2/PPh3 catalytic system, the selectivity of
dehydrogenative silylation over hydrosilylation was obviously
improved and the catalytic system showed high regioselectivity
to generate (E)-alkenylsilanes (Table 1, entries 2 and 4). In the
case where dicyclopentadiene with a ring strain similar to that
of NBE was tested as the hydrogen acceptor, the yield of 3aa
was increased to 58% (Table 1, entry 8). When cyclohexene
without a similar ring strain was used, the yield of 3aa was
hardly increased (Table 1, entry 6). The addition of
cyclodienes, for example, cis-1,5-cyclooctadiene (cod) and
2,5-norbornadiene (NBD), led to no conversion of styrene
(Table 1, entries 5 and 7), indicating that a more stable
competitive coordination of cyclodienes with the catalyst
suppressed the coordination of styrene. Therefore, NBE, a
cycloalkene with ring strain, was the best sacrificial hydrogen
acceptor in the dehydrogenative silylation of styrene. Then the
effect of ligands in the dehydrogenative silylation of styrene
with NBE as the hydrogen acceptor was explored. Reducing
the loading of PPh3 resulted in a decrease in the selectivity of
30
10
4
d
22
e
PPh3 (10)
PPh3 (10)
95
96
3
3
2
1
23
a
Reaction conditions unless stated otherwise: [Rh(COD)Cl]2 (4.9
mg, 1 mol %), ligand, additive (2 equiv), 1a (104.2 mg, 1 mmol), 2a
b
(232.6 mg, 2 mmol), dioxane (4 mL), 60 °C, 4 h. Conversion,
1
selectivity, and yields were determined by H NMR or GC analysis
c
(1,2,4,5-tetramethylbenzene as an internal standard). RhCl(PPh3)3
d
e
(18.5 mg, 2 mol %). THF (4 mL), 60 °C, 4 h. THF (4 mL), 100
°C, 1 h.
dehydrogenative silylation over hydrosilylation. The reaction
with 2 mol % of PPh3 gave the hydrosilylation product 4aa as
the main product (Table 1, entry 10). Gratifyingly, when the
loading of PPh3 was increased, the selectivity of dehydrogen-
ative silylation improved significantly (Table 1, entries 11−16).
When 10 mol % of PPh3 was used in the catalytic system, a
95% yield of 3aa was obtained within 4 h (Table 1, entry 13).
Moreover, when the loading of PPh3 was increased to 20
mol %, the activity and selectivity of the reaction were well
maintained (Table 1, entry 16).7a The electronic nature and
steric hindrance of ligands affected the activity and selectivity
of the catalytic system significantly. When phosphine ligands
with electron-donating groups, P(p-tolyl)3 and (4-
MeOC6H4)3P, were used, the selectivity of dehydrogenative
silylation and the activity decreacsed (Table 1, entries 17 and
19). Using a ligand with steric hindrance also led to a
decreased selectivity of dehydrogenative silylation (Table 1,
entry 17 vs 18). PPh2(C6F5) and diphosphine ligands were
inferior for the dehydrogenative silylation (Table 1, entries 20
and 21).
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We next screened the solvents and reaction temperature of
the dehydrogenative silylation, and the results are shown in
Table S1. Ethereal solvents, such as dioxane (Table 1, entry
13) and THF (Table 1, entry 22), were crucial for high activity
and selectivity. DCE and CH3CN (Table S1, entries 3 and 4)
were poor solvents, while toluene and DMF (Table S1, entries
1 and 5) slightly reduced the selectivity. Decreasing the
reaction temperature resulted in a lower activity (Table S1,
entries 8 and 9). When the reaction temperature was increased
to 100 °C, the activity was increased and the high selectivity
was maintained (Table S1, entries 10−12). The conversion of
styrene was complete within 1 h at 100 °C, and the yield of 3aa
was 96% (Table 1, entry 23). Moreover, reducing the amount
of Et3SiH resulted in a decreased conversion of styrene, and
reducing the amount of NBE led to a slightly increased yield of
the reduction product 5a. Therefore, the optimized reaction
conditions for the dehydrogenative silylation of alkenylarenes
were 1 mol % of [Rh(COD)Cl]2 as precatalyst, 10 mol % of
PPh3 as ligand, 2.0 equiv of silane, 2.0 equiv of NBE as
additive, THF as solvent, and 100 °C. In the dehydrogenative
silylation reaction of styrene and Et3SiH, our catalytic system
([Rh(COD)Cl]2/PPh3/NBE) displayed comparable selectivity
and higher activity (>99% yield, 3aa:4aa:5a = 96:3:1, within 1
h) in comparison to the reported [Rh(COD)2]BF4/PPh3
catalytic system (72% yield, 3aa:4aa = 97:3, within 18 h)7a
and better selectivity and activity in comparison to those of the
reported ruthenium alkylidene catalysts (77% conversion,
3aa:4aa:5a = 1:6:4, within 8 h).5f
Table 2. Substrate Scope for Dehydrogenative Silylation of
Alkenylarenes with Tertiary Silanes
a
The scope of Rh/PPh3/NBE-catalyzed selective dehydro-
genative silylation of styrene derivatives 1 with tertiary silanes
2 was further examined (Table 2). Dehydrogenative silylation
with the catalytic system led to the efficient formation of a
number of (E)-vinylsilanes 3 in good yields with good to
excellent selectivities. The nature of the substituents displayed
an obvious effect on the reactive activity of vinylarenes, and the
results are shown in Figure S2a,b. The reactive rate of p-
methoxystyrene (1e) decreased slightly, and complete
conversion was achieved within 1 h to give the corresponding
alkenylsilane 3ea in 86% yield and good selectivity (3ea:4ea =
95:5). However, the reactive rate of vinylarenes with an
electron-withdrawing group, for example, p-(trifluoromethyl)-
styrene (1f), obviously decreased. The conversion of 1f was
accomplished within 2 h to give the corresponding
alkenylsilane 3fa in 86% yield with good selectivity (3fa:4fa
= 94:6). The decreased reactive activity may be ascribed to the
fact that the electron-withdrawing groups reduce the
coordination ability of vinylarenes with the active catalyst.
The alkyl-substituted styryl silanes 3ba and 3ca were generated
in 82−91% yields with excellent selectivities. For bulkier
vinylarenes, an increase in the loading of PPh3 and a prolonged
reaction time were needed to achieve full conversion to give
the corresponding alkenylsilanes in good yield and selectivity.
For example, the reaction of o-methylstyrene (1g) with 20 mol
% of PPh3 gave the alkenylsilane 3ga in a ratio of 95:5
(3ga:4ga) and 84% yield in 10 h. For an even bulkier substrate,
α-methylstyrene, the reaction did not occur at all. The catalytic
system tolerated diverse functional groups, including halogen,
ester, amide, and aromatic heterocycles. The reactions of 4-
vinylphenyl acetate (1k) and N,N-dimethyl-4-vinylbenzamide
(1l) proceeded smoothly to give the corresponding alkenylsi-
lanes 3ka and 3la in 81% yield (97:3 selectivity) and 86% yield
(96:4 selectivity), respectively. However, the reaction of 4-
acetylstyrene (1n) and an alkenylarene with an estrone
a
Reaction conditions unless stated otherwise: [Rh(COD)Cl]2 (4.9
mg, 1 mol %), PPh3 (26.2 mg, 10 mol %), 1 (1.0 mmol), 2 (2.0
mmol), NBE (188.3 mg, 2 mmol), THF (4 mL), 100 °C, 2 h. Isolated
yields are given, and the ratios of the products 3 and 4 are given in
parentheses; the ratio of 3 and 4 was determined by 1H NMR
b
c
spectroscopy or GC. 1a (1041.5 mg, 10 mmol), 100 °C. 10 h.
d
e
PPh3 (52.5 mg, 20 mol %). 4 h.
skeleton, 1m, gave the corresponding alkenylsilanes in
moderate yields, because the carbonyl group was partially
reduced in the dehydrogenative silylation. 2-Vinylnaphthalene
(1d) reacted well to generate the alkenylsilane 3da in 87%
yield and with a 3da:4da ratio of 96:4 in 10 h. However, in the
case of 4-vinylpyridine 1o as the substrate, a decreased
selectivity of dehydrogenative silylation was observed, even
when the loading of PPh3 was increased to 20 mol %.
The selectivity of dehydrogenative silylation was also
affected by the structure of the hydrosilanes. The reactions
of styrene (1a) with dimethylethylsilane (2d) also gave good
yields and high selectivities for the dehydrogenative silylation.
However, when triphenylsilane 2e was used, the selectivity of
dehydrogenative silylation over hydrosilylation was decreased
to 40:60. The bulky alkoxysilane 2c was reacted with styrene to
give the dehydrogenative silylation product 3ac as the main
product; however, decreasing the steric hindrance of
alkoxysilanes led to the hydrosilylated species as the major
products (3ab:4ab = 29:71). Unfortunately, the catalytic
system was incompatible with alkenylarenes possessing amino,
hydroxyl, formyl, nitro, cyano, and bromo groups or aliphatic
alkenes. When allylbenzene was used as the reaction substrate,
we could only get the olefin isomerization product 1q′ instead
of the dehydrogenative silylation product (see the Supporting
Information).
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Furthermore, the reaction was easily scaled up to a 10 mmol
scale of 1a under the optimized conditions ([Rh(COD)Cl]2 (1
mol %), PPh3 (10 mol %), 1a (10 mmol), 2a (20 mmol), NBE
(20 mmol), THF (40 mL), 100 °C). The conversion of
styrene (1a) was accomplished within 2 h, and the
dehydrogenative silylation product 3aa was isolated in 90%
yield. Alkenylsilanes, the dehydrogenative silylation products,
are powerful synthetic intermediates for organic syntheses
(Scheme 2). The palladium-catalyzed homocoupling reaction
Scheme 2. Synthetic Applications
Figure 1. Profiles for the reactions of styrene (1a) with triethylsilane
(2a) catalyzed by Rh/PPh3 systems. Reaction conditions: (a)
[Rh(COD)Cl]2 (4.9 mg, 1 mol %), PPh3 (10.5 mg, 4 mol %), 1a
(104.2 mg, 1.0 mmol), 2a (232.6 mg, 2.0 mmol), THF (4 mL), 60
°C, in six sealed tubes; (b) [Rh(COD)Cl]2 (4.9 mg, 1 mol %), PPh3
(10.5 mg, 4 mol %), 1a (104.2 mg, 1.0 mmol), 2a (232.6 mg, 2.0
mmol) and NBE (188.3 mg, 2.0 mmol), THF (4 mL), 60 °C, in six
sealed tubes; (c) [Rh(COD)Cl]2 (4.9 mg, 1 mol %), PPh3 (26.2 mg,
10 mol %), 1a (104.2 mg, 1.0 mmol), 2a (232.6 mg, 2.0 mmol) and
NBE (188.3 mg, 2.0 mmol), THF (4 mL), 60 °C, in six sealed tubes.
of alkenylsilanes 3aa afforded the conjugated diene 6 in 68%
yield (Scheme 2a).11a With AlCl3 as the catalyst, the acylation
of the styryl silane 3aa with benzoyl chloride (7) occurred
selectively at the carbon−carbon double bonds to generate
chalcone 8 in 85% yield (Scheme 2b).11b Moreover, fluorine-
containing compounds may show unique bioactive features.
The alkenylsilanes 3aa can be converted to difluoromethyl-
substituted amides 9 in moderate yield using Selectfluor (1-
chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis-
(tetrafluoroborate)) in CH3CN (Scheme 2c).11c
To further understand the role of PPh3 and NBE in the
catalytic system, the profiles for the reactions of styrene 1a
with triethylsilane (2a) catalyzed by Rh/PPh3 systems in THF
were monitored by GC at 60 °C (Figure 1) and 100 °C
(Figure S1). When a combination of 1 mol % of [Rh(COD)-
Cll2 and 4 mol % of PPh3 was used as the catalytic system at 60
°C (Figure 1a), the dehydrogenative silylation product 3aa was
observed accompanied by the hydrosilylation product 4aa and
the reduction byproduct 5a as the major byproducts. The
conversion of styrene 1a was accomplished within 4 h to give
the product 3aa in 68% yield with the generation of 4aa in 7%
yield and 5a in 25% yield, and then the decay of 3aa occurred.
After 8 h, the yield of 3aa decreased to 57%, and the yield of
4aa increased to 18%. When the reaction was carried out at
100 °C (Figure S1a), the conversion of styrene (1a) was
accomplished within 30 min, but the yield of hydrosilylation
product 4aa increased to 26%. Similarly, a decreased yield of
3aa was observed after 30 min. These results indicated that the
Rh/PPh3 catalytic system cannot completely inhibit the
formation of the reduction product 5a and hydrosilylation
product 4aa and the dehydrogenative silylation product 3aa
may be reduced to 4aa in the catalytic system.
also observed after 4 h. These results demonstrated that NBE
was more active than styrene and 3aa in the reactions with the
generated rhodium hydride complex. Moreover, the selectivity
of the dehydrogenative silylation obviously improved to give
3aa in 88% yield. When the reaction temperature was
improved, the conversion of styrene 1a was accomplished
within 30 min, and a similar variation tendency was observed
(Figure S1b). Therefore, in the Rh/PPh3/NBE catalytic
system, the increased selectivity of 3aa may result from the
coordination of NBE with the catalyst or the higher reactivity
of NBE in the reaction with the generated rhodium hydride
complex which promoted the dehydrogenative silylation.12
Furthermore, when the loading of PPh3 was increased to 10
mol % in the Rh/PPh3/NBE catalytic system (Figure 1c), the
activity of the catalytic system was retained; moreover, the
selectivity of dehydrogenative silylation over hydrosilylation
was obviously improved. Styrene 1a was selectively converted
to (E)-triethyl(styryl)silane (3aa) in 95% yield within 4 h, and
no decrease in the yield of 3aa was observed after 4 h. The
reduction of dehydrogenative silylation product 3aa was
substantially inhibited. Even when the reaction was carried
out at 100 °C, the high selectivity was retained and the
reduction of dehydrogenative silylation product 3aa was not
observed (Figure S1c and entries 11−13 in Table S1). These
results suggested that free PPh3 could compete with the
product 3 and hydrosilane 2 to coordinate with the catalyst to
suppress the reduction of 3 and hydrosilylation of styrene.
On the basis of our experimental results, a plausible
mechanism of Rh/PPh3/NBE-catalyzed dehydrogenative
silylation of styrene derivatives and tertiary silanes is shown
in Scheme 3.13a [RhCl(COD)]2 was dissociated by PPh3 to
form the intermediate A, and then oxidative addition of A and
hydrosilane 2 gave the rhodium hydride complex B.13b The
presence of rhodium hydride species was detected in our
When norbornene was added as the sacrificial hydrogen
acceptor in the catalytic system of 1 mol % of [Rh(COD)Cll2
and 4 mol % of PPh3 (Figure 1b), the conversion of styrene
was complete within 4 h, and the reduction of styrene (1a) was
suppressed significantly, but the reduction of 3aa to 4aa was
D
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NMR spectra were recorded on a 100 MHz or a 125 MHz
instrument. Chemical shifts are reported in ppm referenced to the
center line of a triplet at 77.0 ppm of chloroform-d or a heptet at 39.5
ppm of dimethyl sulfoxide-d6. Coupling constants (J) are reported in
Hz and refer to apparent peak multiplications. HRMS were obtained
on an ESI (or EI)-TOF mass spectrometer.
Scheme 3. Proposed Mechanism
N,N-Dimethyl-4-vinylbenzamide (1l).14 4-Vinylbenzoic acid
(1.48 g, 10 mmol, 1.0 equiv) was added at 0 °C to thionyl chloride
(2.38 g, 20 mmol, 2 equiv) in small portions in 40 mL of CH2Cl2. The
reaction mixture was warmed to room temperature and stirred for 2 h.
The remaining thionyl chloride was removed in vacuo, and the
residue was transferred to a solution of N,N-dimethylamine (2 M in
THF, 25 mL, 50 mmol, 5 equiv) in Et2O (25 mL) at 0 °C. The
reaction mixture was stirred at room temperature for 2 h, before water
(20 mL) was added. Organic components were extracted with DCM
(3 × 20 mL) and dried over MgSO4. The combined organic layers
were dried over MgSO4, and the solvent was removed in vacuo. The
product was isolated after purification by column chromatography
(petroleum ether/ethyl acetate 1/1) as a colorless solid (1.29 g, 74%).
1H NMR (500 MHz, CDCl3): δ 7.42 (d, J = 8.5 Hz, 2H), 7.38 (d, J =
catalytic system by 1H NMR spectroscopy (see the Supporting
Information for details). Then NBE was inserted preferentially
into the rhodium hydride A to give alkyl rhodium complex C
8.5 Hz, 2H), 6.71 (dd, J = 17.5, 11.0 Hz, 1H), 5.79 (d, J = 18.0 Hz,
1H), 5.30 (d, J = 11.0 Hz, 1H), 3.09 (s, 3H), 2.98 (s, 3H). 13C NMR
(125 MHz, CDCl3): δ 171.2, 138.6, 135.9, 135.3, 127.3, 125.9, 115.0,
39.4, 35.2.
1
(the structure was also detected in the reaction by H NMR
spectroscopy; see the Supporting Information for details),
because NBE with ring strain is in comparison with styrene
derivative 1 or the dehydrogenated silylation products 3 more
easily coordinates with the metal catalyst (path a).13c The
reaction of alkyl rhodium complex C with hydrosilane 2 to
generate the key intermediate E and norbornane was observed
by GC-MS. Next, the insertion of styrene derivative 1 into the
rhodium silane species E formed another alkyl rhodium
complex F, which either underwent β-H elimination to afford
the dehydrogenated silylation product 3 and regenerate the
rhodium hydride complex B, or reacted with hydrosilane 2 to
generate the intermediate D′, which underwent reductive
elimination to afford hydrosilylation product 4 and rhodium
silane species E (path b).
( 8 R , 9 S , 1 3 S , 1 4 S ) - 1 3 - M e t h y l - 3 - v i n y l -
6,7,8,9,11,12,13,14,15,16-decahydro-17H-cyclopenta[a]-
phenanthren-17-one (1m).15 A 100 mL flask was flame-dried and
charged with estrone (1.35 g, 5 mmol, 1.0 equiv), CH2Cl2 (20 mL),
and Et3N (1.01 g, 10 mmol, 2.0 equiv). The mixture was cooled in a 0
°C ice−water bath, and Tf2O (1.55 g, 5.5 mmol, 1.1 equiv) was added
over 10 min. The mixture was warmed to room temperature and
stirred at room temperature under nitrogen for 3 h. The resulting
brown mixture was diluted with CH2Cl2 and washed with saturated
NH4Cl, and the aqueous layer was extracted with CH2Cl2. The
combined organic layers were dried over MgSO4, and the filtrate was
concentrated. A threaded tube was charged with the above product,
potassium vinyltrifluoroborate (0.74 g, 5.5 mmol, 1.1 equiv), and
PdCl2 (17.7 mg, 0.1 mmol, 0.02 equiv), and the tube was brought into
a N2-filled glovebox. PPh3 (78.6 mg, 0.3 mmol, 0.06 equiv), Cs2CO3
(4.89 g, 15 mmol, 3.0 equiv), and THF (18 mL) were added, and the
tube was sealed and removed from the glovebox. A 2 mL portion of
H2O was added, and the mixture was stirred at 85 °C for 19 h. The
resulting dark brown mixture was cooled to room temperature,
diluted with CH2Cl2, and washed with H2O. The aqueous layer was
extracted with CH2Cl2. The combined organic layers were dried over
MgSO4, and the filtrate was concentrated. The crude product was
purified by column chromatography (petroleum ether/ethyl acetate
CONCLUSIONS
■
In summary, we have disclosed a rhodium-catalyzed
regioselective dehydrogenative silylation of styrene derivatives
with tertiary silanes using readily available PPh3 as the ligand
and NBE as the additive. The reactions of various
alkenylarenes with tertiary silanes selectively provided (E)-
alkenylsilanes in good to excellent selectivity and yields. This
catalytic protocol showed good functional group tolerance of
halogens, aromatic heterocycles, amides, and esters. Further
functionalization of the alkenylsilanes renders the useful
building blocks under mild conditions.
1
10/1) to afford 1.05 g of a white solid (75% yield). H NMR (400
MHz, CDCl3): δ 7.27−7.25 (m, 1H), 7.23−7.20 (m, 1H), 7.14 (s,
1H), 6.67 (dd, J = 17.6, 10.8 Hz, 1H), 5.70 (d, J = 17.6 Hz, 1H), 5.19
(d, J = 10.8 Hz, 1H), 2.94−2.90 (m, 2H), 2.51 (dd, J = 19.2, 8.8 Hz,
1H), 2.46−2.41 (m, 1H), 2.34−2.27 (m, 1H), 2.19−2.16 (m, 1H),
2.10−2.01 (m, 2H), 1.98−1.95 (m, 1H), 1.68−1.59 (m, 2H), 1.57−
1.40 (m, 4H), 0.91 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 220.8,
139.5, 136.5, 135.1, 126.8, 125.5, 123.5, 113.1, 50.5, 47.9, 44.4, 38.1,
35.8, 31.5, 29.3, 26.5, 25.7, 21.5, 13.8.
General Procedures for Dehydrogenative Silylation of
Alkenylarenes. In an oven-dried 25 mL sealed tube containing a
stirring bar were placed [Rh(COD)Cl]2 (4.9 mg, 1 mol %), PPh3
(26.2 mg, 10 mol %), NBE (188.3 mg, 2.0 mmol), and THF (4 mL).
The solution was stirred at room temperature for 10 min. Then, the
olefin (1 mmol) and R3SiH (2.0 mmol) were added to the above
mixture. The initial color of the mixture pf [Rh(COD)Cl]2, PPh3, and
NBE in THF was pale yellow, and there was no color change observed
following the addition of olefin, R3SiH, and NBE. The Schlenk tube
was sealed and heated to 100 °C for 2−10 h; after the reaction, the
resulting red-brown mixture was cooled to room temperature and
then the solvent was concentrated. The crude product was purified by
column chromatography with petroleum ether as eluent to afford the
products 3 and 4.
EXPERIMENTAL SECTION
■
General Information. Commercial reagents were purchased from
commercial sources unless otherwise noted, and all solvents were
dried and distilled before use according to the standard methods.
Unless otherwise noted, all reactions were performed using standard
Schlenk techniques under an atmosphere of nitrogen. Analytical thin-
layer chromatography (TLC) was performed on precoated silica gel
60 F254 plates. Visualization on TLC was achieved with UV light
1
(254 nm) and potassium permanganate as visualization methods. H
NMR spectra were recorded on a 400 MHz or a 500 MHz
instrument. Chemical shifts are quoted in parts per million (ppm)
referenced to the appropriate solvent peak or 0.0 ppm for
1
tetramethylsilane. Data for H NMR spectra are reported as follows:
chemical shift (δ shift), multiplicity (s = singlet, d = doublet, t =
triplet, q = quartet, m = multiplet, dd = double of doublets, ddd =
doublet of doublets of doublets, dt = doublet of triplets, td = triplet of
doublets), integration, coupling constant (Hz), and assignment. 13C
E
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Organometallics XXXX, XXX, XXX−XXX

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Article
(E)-Triethyl(styryl)silane (3aa).6h Purified by column chromatog-
raphy on silica gel with petroleum ether. Colorless oil (3aa:4aa =
97:3). Yield: 192 mg, 88%. 1H NMR (400 MHz, CDCl3): δ 7.44 (d, J
= 7.2 Hz, 2H), 7.32 (t, J = 7.2 Hz, 2H), 7.26−7.21 (m, 1H), 6.89 (d, J
= 19.2 Hz, 1H), 6.42 (d, J = 19.2 Hz, 1H), 0.99 (t, J = 8.0 Hz, 9H),
0.66 (q, J = 8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3): δ 144.9,
138.5, 128.4, 127.8, 126.3, 125.7, 7.4, 3.6.
139.6−141.1 °C. 1H NMR (400 MHz, CDCl3): δ 7.47 (d, J = 8.4 Hz,
2H), 7.40 (d, J = 8.8 Hz, 2H), 7.17 (br, 1H), 6.84 (d, J = 19.2 Hz,
1H), 6.34 (d, J = 19.2 Hz, 1H), 2.18 (s, 3H), 0.98 (t, J = 8.0 Hz, 9H),
0.65 (q, J = 8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3): δ 168.2,
143.9, 137.5, 134.7, 126.9, 125.0, 119.6, 24.6, 7.4, 3.5. HRMS-ESI
(m/z): calculated for C16H26NOSi (M + H)+ 276.1784, found
276.1790.
(E)-Triethyl(4-methylstyryl)silane (3ba).6h Purified by column
chromatography on silica gel with petroleum ether. Colorless oil
(3ba:4ba = 97:3). Yield: 190 mg, 82%. 1H NMR (400 MHz, CDCl3):
δ 7.40 (d, J = 7.2 Hz, 2H), 7.19 (d, J = 7.2 Hz, 2H), 6.94 (d, J = 19.2
Hz, 1H), 6.42 (d, J = 19.2 Hz, 1H), 2.40 (s, 3H), 1.06 (t, J = 8.0 Hz,
9H), 0.72 (q, J = 8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3): δ 144.7,
137.7, 135.9, 129.2, 126.2, 124.5, 21.2, 7.4, 3.6.
(E)-4-(2-(Triethylsilyl)vinyl)phenyl Acetate (3ka).6h Purified by
column chromatography on silica gel with 10/1 petroleum ether/ethyl
acetate. Colorless oil (3ka:4ka = 97:3). Yield: 224 mg, yield 81%. 1H
NMR (400 MHz, CDCl3): δ 7.44 (d, J = 8.8 Hz, 2H), 7.05 (d, J = 8.8
Hz, 2H), 6.86 (d, J = 19.2 Hz, 1H), 6.37 (d, J = 19.2 Hz, 1H), 2.28 (s,
3H), 0.98 (t, J = 8.0 Hz, 9H), 0.65 (q, J = 8.0 Hz, 6H). 13C NMR
(100 MHz, CDCl3): δ 169.3, 150.2, 143.7, 136.3, 127.2, 126.2, 121.5,
21.0, 7.3, 3.4.
(E)-(4-(tert-Butyl)styryl)triethylsilane (3ca).6h Purified by column
chromatography on silica gel with petroleum ether. Colorless oil
(3ca:4ca = 96:4). Yield: 249 mg, 91%. 1H NMR (400 MHz, CDCl3):
δ 7.40−7.34 (m, 4H), 6.87 (d, J = 19.6 Hz, 1H), 6.37 (d, J = 19.2 Hz,
1H), 1.32 (s, 9H), 0.98 (t, J = 8.0 Hz, 9H), 0.65 (q, J = 8.0 Hz, 6H).
13C NMR (100 MHz, CDCl3): δ 151.0, 144.7, 135.9, 126.1, 125.4,
124.7, 34.5, 31.3, 7.4, 3.6.
(E)-N,N-Dimethyl-4-(2-(triethylsilyl)vinyl)benzamide (3la). Puri-
fied by column chromatography on silica gel with 2/1 petroleum
ether/ethyl acetate. Colorless oil (3la:4la = 96:4). Yield: 249 mg, 86%
1H NMR (400 MHz, CDCl3): δ 7.46 (d, J = 8.2 Hz, 2H), 7.39 (d, J =
8.2 Hz, 2H), 6.89 (d, J = 19.2 Hz, 1H), 6.49 (d, J = 19.2 Hz, 1H),
3.05 (s, s, 6H), 0.99 (t, J = 8.0 Hz, 9H), 0.67 (q, J = 8.0 Hz, 6H). 13
C
(E)-Triethyl(2-(naphthalen-2-yl)vinyl)silane (3da).16 Purified by
column chromatography on silica gel with petroleum ether. Colorless
NMR (100 MHz, CDCl3): δ 171.3, 143.8, 139.6, 135.4, 127.8, 127.4,
126.1, 39.5, 35.3, 7.3, 3.4. HRMS-ESI (m/z): calculated for
C17H28NOSi (M + H)+ 290.1940, found 290.1942.
1
oil (3da:4da = 96:4). Yield: 233 mg, 87%. H NMR (400 MHz,
CDCl3): δ 7.82−7.77 (m, 4H), 7.70−7.68 (m, 1H), 7.47−7.41 (m,
2H), 7.06 (d, J = 19.2 Hz, 1H), 6.55 (d, J = 19.2 Hz, 1H), 1.01 (t, J =
8.0 Hz, 9H), 0.70 (q, J = 8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3):
δ 144.9, 135.9, 133.6, 133.3, 128.11, 128.06, 127.6, 126.5, 126.4,
126.1, 125.9, 123.3, 7.4, 3.6.
(8R,9S,13S,14S)-13-Methyl-3-((E)-2-(triethylsilyl)vinyl)-
7,8,9,11,12,13,15,16-octahydro-6H-cyclopenta[a]phenanthren-17-
(14H)-one (3ma). Purified by column chromatography on silica gel
with 10/1 petroleum ether/ethyl acetate. Colorless solid (3ma:4ma =
1
97:3). Yield: 181 mg, 46%. Mp: 87.3−89.5 °C. H NMR (400 MHz,
(E)-Triethyl(4-methoxystyryl)silane (3ea).6h Purified by column
chromatography on silica gel with petroleum ether. Colorless oil
(3ea:4ea = 95:5). Yield: 213 mg, 86%. 1H NMR (400 MHz, CDCl3):
δ 7.39−7.37 (m, 2H), 6.87−6.81 (m, 3H), 6.25 (d, J = 19.2 Hz, 1H),
3.80 (s, 3H), 0.98 (t, J = 8.0 Hz, 9H), 0.65 (q, J = 8.0 Hz, 6H). 13C
NMR (100 MHz, CDCl3): δ 159.5, 144.2, 131.6, 127.5, 123.0, 113.8,
55.3, 7.4, 3.6.
CDCl3): δ 7.27−7.23 (m, 2H), 7.18 (s, 1H), 6.84 (d, J = 19.2 Hz,
1H), 6.37 (d, J = 19.6 Hz, 1H), 2.94−2.91 (m, 2H), 2.50 (dd, J =
18.8, 8.4 Hz, 1H), 2.47−2.40 (m, 1H), 2.33−2.27 (m, 1H), 2.19−
2.10 (m, 1H), 2.09−1.94 (m, 3H), 1.68−1.58 (m, 2H), 1.56−1.41
(m, 4H), 0.97 (t, J = 8.0 Hz, 9H), 0.91 (s, 3H), 0.65 (q, J = 8.0 Hz,
6H). 13C NMR (100 MHz, CDCl3): δ 220.8, 144.5, 139.6, 136.5,
136.2, 126.9, 125.5, 125.0, 123.7, 50.5, 48.0, 44.4, 38.2, 35.8, 31.6,
29.4, 26.5, 25.7, 21.6, 13.8, 7.4, 3.5. HRMS-ESI (m/z): calculated for
C26H39OSi (M + H)+ 395.2770, found 395.2768.
(E)-Triethyl(4-(trifluoromethyl)styryl)silane (3fa).17 Purified by
column chromatography on silica gel with petroleum ether. Colorless
oil (3fa:4fa = 94:6). Yield: 226 mg, 79%. 1H NMR (400 MHz,
CDCl3): δ 7.58 (d, J = 8.4 Hz, 2H), 7.52 (d, J = 8.0 Hz, 2H), 6.91 (d,
J = 19.2 Hz, 1H), 6.55 (d, J = 19.2 Hz, 1H), 0.99 (t, J = 8.0 Hz, 9H),
0.68 (q, J = 8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3): δ 143.3,
141.7 (d, J = 1.1 Hz), 129.7, 129.6 (q, J = 32.1 Hz), 125.4 (q, J = 3.8
Hz), 124.2 (q, J = 270.2 Hz), 7.3, 3.4. 19F NMR (376 MHz, CDCl3):
δ −62.5.
(E)-1-(4-(2(Triethylsilyl)vinyl)phenyl)ethanone (3na).19 Purified
by column chromatography on silica gel with 20/1 petroleum
ether/ethyl acetate. Colorless oil (3na:4na = 97:3). Yield: 135 mg,
1
52%. H NMR (400 MHz, CDCl3): δ 7.93 (d, J = 8.4 Hz, 2H), 7.51
(d, J = 8.4 Hz, 2H), 6.93 (d, J = 19.6 Hz, 1H), 6.59 (d, J = 19.2 Hz,
1H), 2.60 (s, 3H), 0.99 (t, J = 8.0 Hz, 9H), 0.68 (q, J = 8.0 Hz, 6H).
13C NMR (100 MHz, CDCl3): δ 197.5, 143.5, 142.7, 136.2, 130.1,
128.6, 126.3, 26.5, 7.3, 3.4.
(E)-Triethyl(2-methylstyryl)silane (3ga).18 Purified by column
chromatography on silica gel with petroleum ether. Colorless oil
(3ga:4ga = 95:5). Yield: 195 mg, 84%. 1H NMR (400 MHz, CDCl3):
δ 7.52−7.50 (m, 1H), 7.20−7.12 (m, 4H), 6.30 (d, J = 19.2 Hz, 1H),
2.37 (s, 3H), 1.00 (t, J = 8.0 Hz, 9H), 0.66 (q, J = 8.0 Hz, 6H). 13C
NMR (100 MHz, CDCl3): δ 142.8, 138.0, 135.1, 130.2, 127.8, 127.6,
126.1, 125.3, 19.6, 7.4, 3.6.
(E)-4-(2-(Triethylsilyl)vinyl)pyridine (3oa).19 Purified by column
chromatography on silica gel with 5/1 petroleum ether/ethyl acetate.
1
Colorless oil (3oa:4oa = 60:40). Yield: 201 mg, 92%. H NMR (400
MHz, CDCl3): δ 8.56 (d, J = 6.0 Hz, 2H), 7.29 (d, J = 6.0 Hz, 2H),
6.83 (d, J = 19.2 Hz, 1H), 6.70 (d, J = 19.6 Hz, 1H), 0.99 (t, J = 8.0
Hz, 9H), 0.68 (q, J = 8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3): δ
150.1, 145.3, 142.3, 132.6, 120.7, 7.3, 3.3.
(E)-Triethyl(4-fluorostyryl)silane (3ha).6h Purified by column
chromatography on silica gel with petroleum ether. Colorless oil
(3ha:4ha = 97:3). Yield: 189 mg, 80%. 1H NMR (400 MHz, CDCl3):
δ 7.43−7.38 (m, 2H), 7.04−6.98 (m, 2H), 6.84 (d, J = 19.2 Hz, 1H),
6.32 (d, J = 19.2 Hz, 1H), 0.98 (t, J = 8.0 Hz, 9H), 0.65 (q, J = 8.0 Hz,
6H). 13C NMR (100 MHz, CDCl3): δ 163.8, 161.3, 143.5, 134.7 (d, J
= 3.3 Hz), 127.8 (d, J = 8.0 Hz), 125.6 (d, J = 2.2 Hz), 115.3 (d, J =
21.5 Hz), 7.4, 3.5. 19F NMR (376 MHz, CDCl3): δ −114.3.
(E)-(4-Chlorostyryl)triethylsilane (3ia).6h Purified by column
chromatography on silica gel with petroleum ether. Colorless oil
(3ia:4ia = 97:3). Yield: 214 mg, 85%. 1H NMR (400 MHz, CDCl3): δ
7.37−7.34 (m, 2H), 7.30−7.27 (m, 2H), 6.83 (d, J = 19.2 Hz, 1H),
6.40 (d, J = 19.2 Hz, 1H), 0.98 (t, J = 8.0 Hz, 9H), 0.66 (q, J = 8.0 Hz,
6H). 13C NMR (100 MHz, CDCl3): δ 143.4, 137.0, 133.5, 128.6,
127.5, 126.9, 7.4, 3.5.
(E)-1-Tosyl-5-(2-(triethylsilyl)vinyl)-1H-indole (3pa). Purified by
column chromatography on silica gel with 20/1 petroleum ether/ethyl
acetate. Pale blue oil (3pa:4pa = 96:4). Yield: 325 mg, 79%. 1H NMR
(400 MHz, CDCl3): δ 7.93 (d, J = 8.8 Hz, 1H), 7.74 (d, J = 8.0 Hz,
2H), 7.56 (s, 1H), 7.53 (d, J = 3.6 Hz, 1H), 7.44 (d, J = 8.8 Hz, 1H),
7.19 (d, J = 8.4 Hz, 2H), 6.93 (d, J = 19.2 Hz, 1H), 6.63 (d, J = 3.2
Hz, 1H), 6.38 (d, J = 19.2 Hz, 1H), 2.32 (s, 3H), 0.97 (t, J = 8.0 Hz,
9H), 0.65 (q, J = 8.0 Hz, 6H). 13C NMR (100 MHz, CDCl3): δ 144.9,
144.6, 135.2, 134.6, 134.2, 131.1, 129.8, 126.9, 126.7, 125.1, 123.0,
119.3, 113.5, 109.3, 21.5, 7.4, 3.5. HRMS-ESI (m/z): calculated for
C23H30NO2Si (M + H)+ 412.1767, found 412.1762.
(E)-Prop-1-en-1-ylbenzene (1q′),.20 The reaction of allylbenzene
with a conversion of 100% gave the olefin isomerization product as a
1
colorless oil. Yield: 108.7 mg, 92%. H NMR (400 MHz, CDCl3): δ
(E)-N-(4-(2-(Triethylsilyl)vinyl)phenyl)acetamide (3ja). Purified by
column chromatography on silica gel with 5/1 petroleum ether/ethyl
acetate. Colorless solid (3ja:4ja = 96:4). Yield: 206 mg, 75%. Mp:
7.33−7.26 (m, 4H), 7.20−7.16 (m, 1H), 6.40 (d, J = 15.8 Hz, 1H),
6.28−6.19 (m, 1H), 1.88 (d, J = 6.8 Hz, 3H). 13C NMR (100 MHz,
CDCl3): δ 137.9, 131.0, 128.4, 126.7, 125.8, 125.7, 18.5.
F
https://dx.doi.org/10.1021/acs.organomet.0c00242
Organometallics XXXX, XXX, XXX−XXX

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Article
(E)-Ethyldimethyl(styryl)silane (3ab).21 Purified by column
chromatography on silica gel with petroleum ether. Colorless oil
(3ab:4ab = 29:71). Yield: 208 mg, 88%. 1H NMR (400 MHz,
CDCl3): δ 7.47−7.45 (m, 2H), 7.36−7.22 (m, 3H), 6.89 (d, J = 19.2
Hz, 1H), 6.31 (d, J = 19.6 Hz, 1H), 3.83 (q, J = 6.8 Hz, 4H), 1.26 (t, J
= 6.8 Hz, 6H), 0.28 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 147.4,
137.8, 128.52, 128.50, 126.7, 122.4, 58.4, 18.4, −4.2.
People’s Republic of China; State Key Laboratory of
Organometallic Chemistry, Shanghai Institute of Organic
Chemistry, Shanghai 200032, People’s Republic of China;
orcid.org/0000-0003-3270-6617; Email: zhaoguo@
sjtu.edu.cn
Authors
(E)-1,1,1,3,5,5,5-Heptamethyl-3-styryltrisiloxane (3ac).5f Purified
by column chromatography on silica gel with petroleum ether.
Wenkui Lu − School of Chemistry and Chemical Engineering,
Shanghai Jiao Tong University, Shanghai 200240, People’s
Republic of China
Chengyang Li − School of Chemistry and Chemical Engineering,
Shanghai Jiao Tong University, Shanghai 200240, People’s
Republic of China
Xiaoyu Wu − School of Chemistry and Chemical Engineering,
Shanghai Jiao Tong University, Shanghai 200240, People’s
Republic of China
1
Colorless oil (3ac:4ac = 86:14). Yield: 308 mg, 95%. H NMR (500
MHz, CDCl3): δ 7.44 (d, J = 7.5 Hz, 2H), 7.33 (t, J = 7.5 Hz, 2H),
7.28−7.25 (m, 1H) 6.96 (d, J = 19.0 Hz, 1H), 6.26 (d, J = 19.5 Hz,
1H), 0.18 (s, 3H), 0.13 (s, 18H). 13C NMR (125 MHz, CDCl3): δ
145.0, 138.2, 128.5, 128.2, 126.63, 126.57, 1.9, 0.01.
(E)-Ethyldimethyl(styryl)silane (3ad). Purified by column chroma-
tography on silica gel with petroleum ether. Colorless oil (3ad:4ad =
87:13). Yield: 162 mg, 85%. 1H NMR (400 MHz, CDCl3): δ 7.45 (d,
J = 7.6 Hz, 2H), 7.34 (t, J = 7.6 Hz, 2H), 7.28−7.26 (m, 1H), 6.89 (d,
J = 19.2 Hz, 1H), 6.48 (d, J = 19.2 Hz, 1H), 0.99 (t, J = 8.0 Hz, 3H),
0.63 (q, J = 8.0 Hz, 2H), 0.15 (s, 6H). 13C NMR (100 MHz, CDCl3):
δ 144.0, 138.4, 128.5, 128.3, 127.9, 126.3, 7.4, 3.6. HRMS-EI (m/z):
calculated for [C12H18Si]+ 190.1178, found 190.1175.
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.organomet.0c00242
Notes
(E)-Triphenyl(styryl)silane (3ae).22 Purified by column chromatog-
raphy on silica gel with petroleum ether. Colorless solid (3ae:4ae =
The authors declare no competing financial interest.
1
40:60). Yield: 337 mg, 93%. H NMR (400 MHz, CDCl3): δ 7.59−
7.50 (m, 6H), 7.49−7.47 (m, 2H), 7.45−7.41 (m, 3H), 7.40−7.38
(m, 6H), 7.34−7.26 (m, 3H), 6.98 (s, 2H). 13C NMR (100 MHz,
CDCl3): δ 148.8, 138.0, 136.0, 135.6, 134.4, 129.6, 128.5, 127.9,
126.7, 122.9.
ACKNOWLEDGMENTS
■
We thank the National Natural Science Foundation of China
for financial support. This paper is dedicated to Prof. Pierre H.
Dixneuf for his outstanding contribution to organometallic
chemistry and catalysis.
(1E,3E)-1,4-Diphenylbta-1,3-diene (6).11a Purified by column
chromatography on silica gel with petroleum ether. Colorless oil.
1
Yield: 140 mg, 68%. H NMR (400 MHz, CDCl3): δ 7.45−7.43 (m,
4H), 7.35−7.31 (m, 4H), 7.25−7.21 (m, 2H), 6.99−6.92 (m, 2H),
6.71−6.64 (m, 2H). 13C NMR (100 MHz, CDCl3): δ 137.3, 132.8,
129.2, 128.6, 127.5, 126.4.
REFERENCES
■
(1) (a) Marciniec, B.; Maciejewski, H.; Pietraszuk, C.; Pawluc, P.
Hydrosilylation: A Comprehensive Review On Recent Advances;
Marciniec, B., Ed.; Springer: Berlin, 2009; Vol. 1, pp 3−51.
(E)-Chalcone (8).23 Purified by column chromatography on silica
gel with petroleum ether and ethyl acetate. Pale yellow solid. Yield:
1
́
(b) Min, G. K.; Hernandez, D.; Skrydstrup, T. Efficient Routes to
177 mg, 85%. Mp: 56.6−58.1 °C. H NMR (400 MHz, CDCl3): δ
Carbon−Silicon Bond Formation for the Synthesis of Silicon-
8.03−8.01 (m, 2H), 7.81 (d, J = 12.8 Hz, 1H), 7.65−7.63 (m, 2H),
7.60−7.49 (m, 4H), 7.43−7.40 (m, 3H), 7.34−7.26 (m, 3H), 6.98 (s,
2H). 13C NMR (100 MHz, CDCl3): δ 190.5, 144.8, 134.8, 132.7,
130.5, 128.9, 128.6, 128.5, 128.4, 122.0.
Containing Peptides and Azasilaheterocycles. Acc. Chem. Res. 2013,
́
46, 457−470. (c) Hofmann, R. J.; Vlatkovic, M.; Wiesbrock, F. Fifty
Years of Hydrosilylation in Polymer Science: A Review of Current
Trends of Low-Cost Transition-Metal and Metal-Free Catalysts, Non-
Thermally Triggered Hydrosilylation Reactions, and Industrial
Applications. Polymers 2017, 9, 534−571.
N-(2,2-Difluoro-1-phenylethyl)acetamide (9).24 Purified by col-
umn chromatography on silica gel with petroleum ether and ethyl
acetate. Colorless solid. Yield: 143 mg, 72%. Mp: 104.5−105.8 °C. 1H
NMR (400 MHz, CDCl3): δ 7.42−7.34 (m, 5H), 6.18−5.89 (m, 2H),
5.47−5.36 (m, 1H), 2.09 (s, 3H). 13C NMR (150 MHz, CDCl3): δ
169.8, 133.9 (d, J = 4.4 Hz), 128.9, 128.8, 127.8, 116.2, 114.6 (t, J =
244.9 Hz), 113.0, 54.7 (t, J = 21.8 Hz), 23.2. 19F NMR (376 MHz,
CDCl3): δ −125.4 (d, J = 280.9 Hz, 1F), −127.3 (d, J = 280.5 Hz,
1F).
(2) (a) Hartwig, J. F. Borylation and Silylation of C−H Bonds: A
Platform for Diverse C−H Bond Functionalizations. Acc. Chem. Res.
2012, 45, 864−873. (b) Mkhalid, I. A. I.; Barnard, J. H.; Marder, T.
B.; Murphy, J. M.; Hartwig, J. F. C−H Activation for the Construction
of C−B Bonds. Chem. Rev. 2010, 110, 890−931. (c) Kakiuchi, F.;
Chatani, N. Catalytic Methods for C−H Bond Functionalization:
Application in Organic Synthesis. Adv. Synth. Catal. 2003, 345, 1077−
1101. (d) Hartwig, J. F. Regioselectivity of the Borylation of Alkanes
and Arenes. Chem. Soc. Rev. 2011, 40, 1992−2002. (e) Fleming, I.;
Barbero, A.; Walter, D. Stereochemical Control in Organic Synthesis
Using Silicon-Containing Compounds. Chem. Rev. 1997, 97, 2063−
2192.
(3) (a) McAtee, J. R.; Martin, S. E. S.; Ahneman, D. T.; Johnson, K.
A.; Watson, D. A. Preparation of Allyl and Vinyl Silanes by the
Palladium-Catalyzed Silylation of Terminal Olefins: A Silyl-Heck
Reaction. Angew. Chem., Int. Ed. 2012, 51, 3663−3667. (b) Martin, S.
E. S.; Watson, D. A. Preparation of Vinyl Silyl Ethers and Disiloxanes
via the Silyl-Heck Reaction of Silyl Ditriflates. J. Am. Chem. Soc. 2013,
135, 13330−13333. (c) McAtee, J. R.; Martin, S. E. S.; Cinderella, A.
P.; Reid, W. B.; Johnson, K. A.; Watson, D. A. The First Example of
Nickel-Catalyzed Silyl-Heck Reactions: Direct Activation of Silyl
Triflates without Iodide Additives. Tetrahedron 2014, 70, 4250−4256.
(d) Matsumoto, K.; Huang, J.; Naganawa, Y.; Guo, H.; Beppu, T.;
Sato, K.; Shimada, S.; Nakajima, Y. Direct Silyl-Heck Reaction of
Chlorosilanes. Org. Lett. 2018, 20, 2481−2484.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.organomet.0c00242.
■
sı
1H, 13C, and 19F NMR spectra of all isolated
alkenylarenes (PDF)
AUTHOR INFORMATION
Corresponding Authors
■
Xiaomin Xie − School of Chemistry and Chemical Engineering,
Shanghai Jiao Tong University, Shanghai 200240, People’s
Republic of China; orcid.org/0000-0002-5798-291X;
Email: xiaominxie@sjtu.edu.cn
Zhaoguo Zhang − School of Chemistry and Chemical
Engineering, Shanghai Jiao Tong University, Shanghai 200240,
G
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Article
(4) (a) Blumenkopf, T. A.; Overman, L. E. Vinylsilane- and
Alkynylsilane-Terminated Cyclization Reactions. Chem. Rev. 1986, 86,
857−873. (b) Langkopf, E.; Schinzer, D. Uses of Silicon-Containing
Compounds in the Synthesis of Natural Products. Chem. Rev. 1995,
95, 1375−1408. (c) Clarson, S. J. Hydrosilylation: A Comprehensive
Review on Recent Advances. Silicon 2009, 1, 57−58. (d) Bracegirdle,
S.; Anderson, E. A. Recent Advances in the use of Temporary Silicon
Tethers in Metal-Mediated Reactions. Chem. Soc. Rev. 2010, 39,
6095. Cu: (h) Gu, J.; Cai, C. Stereoselective Synthesis of Vinylsilanes
via Copper-Catalyzed Silylation of Alkenes with Silanes. Chem.
Commun. 2016, 52, 10779−10782. (i) Zhang, L.; Hang, Z.; Liu, Z.-Q.
A Free-Radical-Promoted Stereospecific Decarboxylative Silylation of
α,β-Unsaturated Acids with Silanes. Angew. Chem., Int. Ed. 2016, 55,
236−239. Mn: (j) Yang, X.; Wang, C. Diverse Fates of β-Silyl Radical
under Manganese Catalysis: Hydrosilylation and Dehydrogenative
Silylation of Alkenes. Chin. J. Chem. 2018, 36, 1047−1051.
(7) (a) Takeuchi, R.; Yasue, H. Cationic Rhodium Complex-
Catalyzed Highly Selective Dehydrogenative Silylation of Styrene.
Organometallics 1996, 15, 2098−2102. (b) Kakiuchi, F.; Nogami, K.;
Chatani, N.; Seki, Y.; Murai, S. Dehydrogenative Silylation of 1,5-
Dienes with Hydrosilanes Catalyzed by RhCl(PPh3)3. Organometallics
1993, 12, 4748−4750. (c) Marciniec, B. Catalysis by Transition Metal
Complexes of Alkene Silylation - Recent Progress and Mechanistic
Implications. Coord. Chem. Rev. 2005, 249, 2374−2390.
́
4114−4129. (e) Remond, E.; Martin, C.; Martinez, J.; Cavelier, F.
Silicon-Containing Amino Acids: Synthetic Aspects, Conformational
Studies, and Applications to Bioactive Peptides. Chem. Rev. 2016, 116,
́
́
11654−11684. (f) Perez-Torrente, J. J.; Nguyen, D. H.; Jimenez, M.
́
V.; Modrego, F. J.; Puerta-Oteo, R.; Gomez-Bautista, D.; Iglesias, M.;
Oro, L. A. Hydrosilylation of Terminal Alkynes Catalyzed by a ONO-
Pincer Iridium(III) Hydride Compound: Mechanistic Insights into
the Hydrosilylation and Dehydrogenative Silylation Catalysis. Organo-
metallics 2016, 35, 2410−2422.
(8) (a) Chalk, A. J. Section of Organometallic Chemistry: Olefin
Hydrosilation Catalyzed by Group VIII Metal Complexs. Trans. N. Y.
Acad. Sci. 1970, 32, 481−488. (b) Nakajima, Y.; Shimada, S.
Hydrosilylation Reaction of Olefins: Recent Advances and Perspec-
tives. RSC Adv. 2015, 5, 20603−20616. (c) Du, X.; Huang, Z.
Advances in Base-Metal-Catalyzed Alkene Hydrosilylation. ACS Catal.
2017, 7, 1227−1243. (d) Sun, J.; Deng, L. Cobalt Complex-Catalyzed
Hydrosilylation of Alkenes and Alkynes. ACS Catal. 2016, 6, 290−
(5) For examples of precious-metal-catalyzed dehydrogenative
silylation, see the following. Rh: (a) Cipot, J.; McDonald, R.;
Ferguson, M. J.; Schatte, G.; Stradiotto, M. Cationic and Formally
Zwitterionic Rhodium(I) and Iridium(I) Derivatives of a P,N-
Substituted Indene: A Comparative Synthetic, Structural, and
Catalytic Investigation. Organometallics 2007, 26, 594−608. (b) Trus-
cott, B. J.; Slawin, A. M. Z.; Nolan, S. P. Well-defined NHC-Rhodium
Hydroxide Complexes as Alkene Hydrosilylation and Dehydrogen-
ative Silylation Catalysts. Dalton Trans. 2013, 42, 270−276. Ir:
(c) Lu, B.; Falck, J. R. Iridium-Catalyzed (Z)-Trialkylsilylation of
Terminal Olefins. J. Org. Chem. 2010, 75, 1701−1705. (d) Cheng, C.;
Simmons, E. M.; Hartwig, J. F. Iridium-Catalyzed, Diastereoselective
Dehydrogenative Silylation of Terminal Alkenes with
(TMSO)2MeSiH. Angew. Chem., Int. Ed. 2013, 52, 8984−8989.
Ru: (e) Christ, M. L.; Sabo-Etienne, S.; Chaudret, B. Highly Selective
Dehydrogenative Silylation of Ethylene Using the Bis(dihydrogen)-
Complex RuH2(H2)2(PCy3)2 as Catalyst Precursor. Organometallics
1995, 14, 1082−1084. (f) Bokka, A.; Jeon, J. Regio- and Stereo-
selective Dehydrogenative Silylation and Hydrosilylation of Vinyl-
arenes Catalyzed by Ruthenium Alkylidenes. Org. Lett. 2016, 18,
5324−5327. Pt: (g) Sprengers, J. W.; Greef, M.; Duin, M. A.;
Elsevier, C. J. Stable Platinum(0) Catalysts for Catalytic Hydro-
silylation of Styrene and Synthesis of [Pt(Ar-Bian)(η2-alkene)]
Complexes. Eur. J. Inorg. Chem. 2003, 2003, 3811−3819. Pd:
(h) LaPointe, A. M.; Rix, F. C.; Brookhart, M. Mechanistic Studies of
Palladium(II)-Catalyzed Hydrosilation and Dehydrogenative Silation
Reactions. J. Am. Chem. Soc. 1997, 119, 906−917.
(6) For examples of earth-abundant-metal-catalyzed dehydrogen-
ative silylation, see the following. Fe: (a) Kakiuchi, F.; Tanaka, Y.;
Chatani, N.; Murai, S. Completely Selective Synthesis of (E)-β-
(triethylsilyl) Styrenes by Fe3(CO)12-Catalyzed Reaction of Styrenes
with Triethylsilane. J. Organomet. Chem. 1993, 456, 45−47.
(b) Naumov, R. N.; Itazaki, M.; Kamitani, M.; Nakazawa, H.
Selective Dehydrogenative Silylation-Hydrogenation Reaction of
Divinyldisiloxane with Hydrosilane Catalyzed by an Iron Complex.
J. Am. Chem. Soc. 2012, 134, 804−807. Co: (c) Takeshita, K.; Seki,
Y.; Kawamoto, K.; Murai, S.; Sonoda, N. The Catalyzed Reaction of
α,β-Unsaturated Esters with Various Hydrosilanes. J. Org. Chem.
1987, 52, 4864−4868. (d) Atienza, C. C. H.; Diao, T.; Weller, K. J.;
Nye, S. A.; Lewis, K. M.; Delis, J. G.; Boyer, J. L.; Roy, A. K.; Chirik,
P. J. Bis(imino)pyridine Cobalt-Catalyzed Dehydrogenative Silylation
of Alkenes: Scope, Mechanism, and Origins of Selective Allylsilane
Formation. J. Am. Chem. Soc. 2014, 136, 12108−12118. (e) Yu, W.-L.;
Luo, Y.-C.; Yan, L.; Liu, D.; Wang, Z.-Y.; Xu, P.-F. Dehydrogenative
Silylation of Alkenes for the Synthesis of Substituted Allylsilanes by
Photoredox, Hydrogen-Atom Transfer, and Cobalt Catalysis. Angew.
Chem., Int. Ed. 2019, 58, 10941−10945. (f) Cheng, B.; Lu, P.; Zhao,
J.; Lu, Z. Cobalt-Catalyzed Dehydrogenative Silylation of Vinylarenes.
Youji Huaxue 2019, 39, 1704−1710. Ni: (g) Hirano, K.; Yorimitsu,
H.; Oshima, K. Nickel-Catalyzed Regio- and Stereoselective Silylation
of Terminal Alkenes with Silacyclobutanes: Facile Access to
Vinylsilanes from Alkenes. J. Am. Chem. Soc. 2007, 129, 6094−
́
300. (e) Zaranek, M.; Marciniec, B.; Pawluc, P. Ruthenium-Catalyzed
Hydrosilylation of Carbon−Carbon Multiple Bonds. Org. Chem.
Front. 2016, 3, 1337−1344. (f) Yang, X.; Wang, C. Manganese-
Catalyzed Hydrosilylation Reactions. Chem. - Asian J. 2018, 13,
́
2307−2315. (g) Zaranek, M.; Pawluc, P. Markovnikov Hydro-
silylation of Alkenes: How an Oddity Becomes the Goal. ACS Catal.
2018, 8, 9865−9876. (h) Obligacion, J. V.; Chirik, P. J. Earth-
abundant Transition Metal Catalysts for Alkene Hydrosilylation and
Hydroboration. Nature Rev. Chem. 2018, 2, 15−34.
(9) For examples of rhodium-catalyzed hydrosilylation, see:
̌
̌
(a) Svoboda, P.; Capka, M.; Hetflejs, J. Catalysis by Metal Complexes
VII. Hydrosilylation Catalyzed by Tetrakis(ethylene)-
dichlorodirhodium(I). Collect. Czech. Chem. Commun. 1972, 37,
́
́
3059−3062. (b) Kuncova, G.; Chvalovsky, V. Steric Effects in
Hydrosilylation of Styrene. Collect. Czech. Chem. Commun. 1980, 45,
2085−2099. (c) Chance, J. M.; Nile, T. A. Rhodium Phosphite
Clusters as Hydrosilylation Catalysts. J. Mol. Catal. 1987, 42, 91−97.
(d) Duckett, S. B.; Perutz, R. N. Mechanism of Homogeneous
Hydrosilation of Alkenes by (η5-Cyclopentadienyl)rhodium. Organo-
metallics 1992, 11, 90−98. (e) Li, J.; Peng, J.; Bai, Y.; Zhang, G.; Lai,
G.; Li, X. Phosphines with 2-Imidazolium Ligands Enhance the
Catalytic Activity and Selectivity of Rhodium Complexes for
Hydrosilylation Reactions. J. Organomet. Chem. 2010, 695, 431−
436. (f) Zhu, C.; Yukimura, N.; Yamane, M. Synthesis of Oxygen- and
Sulfur-Bridged Dirhodium Complexes and Their Use as Catalysts in
the Chemoselective Hydrogenation of Alkenes. Organometallics 2010,
29, 2098−2103. (g) Busetto, L.; Cassani, M. C.; Femoni, C.;
Mancinelli, M.; Mazzanti, A.; Mazzoni, R.; Solinas, G. N-Heterocyclic
Carbene-Amide Rhodium(I) Complexes: Structures, Dynamics, and
Catalysis. Organometallics 2011, 30, 5258−5272. (h) Xue, M.; Li, J.;
Peng, J.; Bai, Y.; Zhang, G.; Xiao, W.; Lai, G. Effect of
Triarylphosphane Ligands on the Rhodium-Catalyzed Hydrosilylation
of Alkene. Appl. Organomet. Chem. 2014, 28, 120−126. (i) Azpeitia,
S.; Garralda, M. A.; Huertos, M. A. Rhodium(III) Catalyzed Solvent-
Free Tandem Isomerization-Hydrosilylation From Internal Alkenes to
Linear Silanes. ChemCatChem 2017, 9, 1901−1905. (j) Li, J.; Yang,
C.; Bai, Y.; Yang, X.; Liu, Y.; Peng, J. The Effect of an Acylphosphine
Ligand on the Rhodium-Catalyzed Hydrosilylation of Alkenes. J.
Organomet. Chem. 2018, 855, 7−11.
(10) (a) Osborn, J. A.; Jardine, F. H.; Young, J. F.; Wilkinson, G. J.
Chem. Soc. A 1966, 1711−1732. (b) Duckett, S. B.; Newell, C. L.;
Eisenberg, R. Observation of New Intermediates in Hydrogenation
Catalyzed by Wilkinson’s Catalyst, RhCl(PPh3)3, Using Para-
hydrogenInduced Polarization. J. Am. Chem. Soc. 1994, 116,
10548−10556.
H
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Organometallics XXXX, XXX, XXX−XXX

Organometallics
pubs.acs.org/Organometallics
Article
(11) (a) Zhang, H.-P.; Dai, Y.-Z.; Zhou, X.; Yu, H. Efficient
Pyrimidone-Promoted Palladium-Catalyzed Suzuki−Miyaura Cross-
Coupling Reaction. Synlett 2012, 23, 1221−1224. (b) Fleming, I.;
(24) Liu, J.; Ni, C.; Li, Y.; Zhang, L.; Wang, G.; Hu, J. Facile
Preparation of Difluoromethyl and Monofluoromethyl-Containing
Amides via Ritter Reaction. Tetrahedron Lett. 2006, 47, 6753−6756.
̀
Dunogues, J.; Smithers, R. The Electrophilic Substitution of
Allylsilanes and Vinylsilanes. Org. React. 1989, 37, 57−575.
(c) Greedy, B.; Gouverneur, V. Fluorodesilylation of Alkenyltrime-
thylsilanes: A New Route to Fluoroalkenes and Difluoromethyl-
Substituted Amides, Alcohols or Ethers. Chem. Commun. 2001, 66,
233−234.
(12) (a) Doyle, M. P.; Devora, G. A.; Nefedov, A. O.; High, K. G.
Addition/Elimination in the Rhodium(II) Perfluorobutyrate Cata-
lyzed Hydrosilylation of 1-Alkenes. Rhodium Hydride Promoted
Isomerization and Hydrogenation. Organometallics 1992, 11, 549−
555. (b) Itazaki, M.; Ueda, K.; Nakazawa, H. Iron-Catalyzed
Dehydrogenative Coupling of Tertiary Silanes. Angew. Chem., Int.
Ed. 2009, 48, 3313−3316. (c) Zhao, L.; Nakatani, N.; Sunada, Y.;
Nagashima, H.; Hasegawa, J.-Y. Theoretical Study on the Rhodium-
Catalyzed Hydrosilylation of C = C and C = O Double Bonds with
Tertiary Silane. J. Org. Chem. 2019, 84, 8552−8561.
(13) (a) Lee, T.; Hartwig, J. F. Mechanistic Studies on Rhodium-
Catalyzed Enantioselective Silylation of Aryl C−H Bonds. J. Am.
Chem. Soc. 2017, 139, 4879−4886. (b) Muraoka, T.; Matsuda, I.;
Itoh, K. Rhodium-Catalyzed Silylative Cyclization of 1,6-Heptadiyne
Derivatives: A Versatile Route for the Synthesis of a 1,2-
Dialkylidenecyclopentane Skeleton. Organometallics 2002, 21,
3650−3660. (c) Karmel, C.; Li, B.; Hartwig, J. F. Rhodium-Catalyzed
Regioselective Silylation of Alkyl C−H Bonds for the Synthesis of 1,4-
Diols. J. Am. Chem. Soc. 2018, 140, 1460−1470.
̈
(14) Masing, F.; Mardyukov, A.; Doerenkamp, C.; Eckert, H.;
Malkus, U.; Nusse, H.; Klingauf, J.; Studer, A. Controlled Light-
̈
Mediated Preparation of Gold Nanoparticles by a Norrish Type I
Reaction of Photoactive Polymers. Angew. Chem., Int. Ed. 2015, 54,
12612−12617.
(15) Huang, C.-Y.; Doyle, A. G. Nickel-Catalyzed Negishi
Alkylations of Styrenyl Aziridines. J. Am. Chem. Soc. 2012, 134,
9541−9544.
(16) Seki, Y.; Takeshita, K.; Kawamoto, K.; Murai, S.; Sonoda, N.
Single-Operation Synthesis of Vinylsilanes from Alkenes and Hydro-
silanes with the Aid of Ru3(CO)12. J. Org. Chem. 1986, 51, 3890−
3895.
(17) Sato, A.; Kinoshita, H.; Shinokubo, H.; Oshima, K. Hydro-
silylation of Alkynes with a Cationic Rhodium Species Formed in an
Anionic Micellar System. Org. Lett. 2004, 6, 2217−2220.
(18) Kita, Y.; Tobisu, M.; Chatani, N. Rhodium-Catalyzed
Alkenylation of Nitriles via Silicon-Assisted C−CN Bond Cleavage.
Org. Lett. 2010, 12, 1864−1867.
(19) Battace, A.; Zair, T.; Doucet, H.; Santelli, M. Selective
Synthesis of (E)-Triethyl(2-arylethenyl)silane Derivatives by Reaction
of Aryl Bromides with Triethyl Vinylsilane Catalyzed by a Palladium−
Tetraphosphine Complex. J. Organomet. Chem. 2005, 690, 3790−
3802.
(20) Hirabe, T.; Nojima, M.; Kusabayashi, S. Lithium Aluminum
Hydride Reduction of Allylic Substrates. Notable Leaving Group
Effects on the Product Regiochemistry. J. Org. Chem. 1984, 49, 4084−
4086.
(21) Wang, Q.; Tinnermann, H.; Tan, S.; Young, R. D. Late-Stage
Generation of Bidentate η3-Benzophosphorine−Phosphino Ligands
from a Rhodium PCcarbeneP Pincer Complex and Their Use in the
Catalytic Hydrosilylation of Alkynes. Organometallics 2019, 38, 3512−
3520.
(22) Lin, Y.-M.; Lu, G.-P.; Wang, R.-K.; Yi, W.-B. Stereoselective
Synthesis of Alkenyl Silanes, Sulfones, Phosphine Oxides, and
Nitroolefins by Radical C−S Bond Cleavage of Arylalkenyl Sulfides.
Org. Lett. 2017, 19, 1100−1103.
(23) Pennell, M. N.; Unthank, M. G.; Turner, P.; Sheppard, T. D. A
General Procedure for the Synthesis of Enones via Gold-Catalyzed
Meyer−Schuster Rearrangement of Propargylic Alcohols at Room
Temperature. J. Org. Chem. 2011, 76, 1479−1482.
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