Iron-Catalyzed Dihydrosilylation of Alkynes: Efficient Access to Geminal Bis(silanes)

Article abstract of DOI:10.1021/jacs.9b02127

Geminal bis(silanes) are versatile synthetic building blocks owing to their stability and propensity to undergo a variety of transformations. However, the scarcity of catalytic methods for their synthesis limits their structural diversity and thus their utility for further applications. Herein we report a new method for synthesis of geminal bis(silanes) by means of iron-catalyzed dihydrosilylation of alkynes. Iron catalysts were distinctly superior to the other tested catalysts, which clearly demonstrates that novel reactivity can be found by using iron catalysts. This method features 100% atom economy, regiospecificity, mild reaction conditions, and readily available starting materials. Using this method, we prepared a new type of geminal bis(silane) with secondary silane moieties, the Si-H bonds of which can easily undergo various transformations, facilitating the synthetic applications of these compounds. Preliminary mechanistic studies demonstrated that the reaction proceeds via two iron-catalyzed hydrosilylation reactions, the first generating β-(E)-vinylsilanes and the second producing geminal bis(silanes).

Full text of DOI:10.1021/jacs.9b02127

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Communication
Iron-Catalyzed Dihydrosilylation of Alkynes:
Efficient Access to Geminal Bis(silanes)
Meng-Yang Hu, Jie Lian, Wei Sun, Tian-Zhang Qiao, and Shou-Fei Zhu
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.9b02127 • Publication Date (Web): 27 Feb 2019
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Iron-Catalyzed Dihydrosilylation of Alkynes: Efficient Access to Geminal
Bis(silanes)
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Meng-Yang Hu,1 Jie Lian,1 Wei Sun,1 Tian-Zhang Qiao,1 and Shou-Fei Zhu*,1
1 State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin
300071, China
Supporting Information Placeholder
atom economy and produce only geminal bis(silanes) with
quaternary silyl groups, which are difficult to transform
further. Hydrosilylation is a promising method for forming C–
Si bonds owing to its high efficiency and 100% atom economy,7
and in fact hydrosilylation of quaternary vinylsilanes has been
studied by several research groups; however, the
regioselectivity of these reactions is generally poor (Scheme
1c).8 Herein we report a new method of synthesizing geminal
bis(silanes) by means of iron-catalyzed dihydrosilylation of
alkynes. Iron catalysts were distinctly superior to the other
types of catalysts that we tested, a result that clearly
demonstrates that novel reactivities can be found by using iron
catalysts. Our method features 100% atom economy,
regiospecificity, mild reaction conditions, and readily available
starting materials. More important, this method allows the
highly efficient synthesis of previously unreported geminal
bis(silanes) with secondary silyl groups, the Si–H bonds of
which can undergo various transformations, giving this
method great potential synthetic utility.
ABSTRACT: Geminal bis(silanes) are versatile synthetic
building blocks owing to their stability and propensity to
undergo a variety of transformations. However, the scarcity of
catalytic methods for their synthesis limits their structural
diversity and thus their utility for further applications. Herein
we report a new method for synthesis of geminal bis(silanes)
by means of iron-catalyzed dihydrosilylation of alkynes. Iron
catalysts were distinctly superior to the other tested catalysts,
which clearly demonstrates that novel reactivity can be found
by using iron catalysts. This method features 100% atom
economy, regiospecificity, mild reaction conditions, and readily
available starting materials. Using this method, we prepared a
new type of geminal bis(silane) with secondary silane moieties,
the Si–H bonds of which can easily undergo various
transformations, facilitating the synthetic applications of these
compounds. Preliminary mechanistic studies demonstrated
that the reaction proceeds via two iron-catalyzed
hydrosilylation reactions, the first generating β-(E)-
vinylsilanes and the second producing geminal bis(silanes).
a) Palladium-catalyzed insertion of benzylic carbenes into Si-Si bonds
NNHTs
R'
[Pd]
FMe2Si
R
SiMe2F
R'
FMe2Si SiMe2F
+
R
Iron catalysis has attracted considerable attention for two main
reasons: (1) iron is abundant, inexpensive, and biocompatible,
and thus iron catalysts meet the requirements for green and
sustainable chemistry applications, and (2) the unique
electronic structures of iron give it the potential to mediate
transformations that cannot be achieved with other catalysts.
The development of new iron-catalyzed reactions and
elucidation of the mechanisms of iron catalysis are among the
most important topics in this field.1
b) Copper-catalyzed double C(sp3)-Si coupling of geminal dibromides
SiMe2Ph
Br
[Cu]
+
Me2PhSi Bpin
R
SiMe2Ph
R
Br
c) Transition-metal-catalyzed hydrosilylation of vinylsilanes
SiR'3
[M]
R'3Si
+
R'3SiH
+
SiR3
SiR3
Me
SiR3
poor selectivity
Organosilanes are widely used in organic synthesis and
materials science.2 In particular, geminal bis(silanes) are
versatile synthetic building blocks owing to their stability and
propensity to undergo a variety of transformations.3 However,
the scarcity of reliable catalytic methods for their preparation
has limited their structural diversity and thus the development
of new transformations of these compounds. Syntheses based
on stoichiometric reactions generally use tBuLi, sBuLi, or other
bases, which either show poor selectivity or generate large
quantities of waste.4 Geminal bis(silanes) have also been
prepared by means of palladium-catalyzed insertion of
benzylic carbenes into Si–Si bonds (Scheme 1a)5 and by
copper-catalyzed double C(sp3)–Si coupling of geminal
dibromides (Scheme 1b),6 but these two methods have poor
d) Iron-catalyzed dihydrosilylation of alkynes (This work)
SiH2R2
SiH2R2
[Fe]
R1
R2SiH3
R1
+
(2.2 equiv)
85-95% yield
regiospecific
Ph
Si
C7H15
Ph
O
O
SiX2Ph
Ph
Si
Si
Si
O
O
OH
Ph
C7H15
SiX2Ph
C6H13
X = OR3, F
Ph
Ar
C6H13
C6H13
Scheme1. Catalytic Synthesis of Geminal Bis(silanes).
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Page 2 of 6
c
d
internal standard. Isolated yield of 6a is 90%. Benzene as
solvent. e Toluene as solvent.
1
2
Figure 1. Catalysts used in this study.
We started by carrying out hydrosilylation reactions between
pent-4-yn-1-ylbenzene (1a) and PhSiH3 in THF (Table 1). First,
we evaluated iron catalysts with various ligands (Figure 1, C1–
C8). EtMgBr was used to reduce the Fe(II) complexes to the
active low-valent iron species.9 These reactions can generate
many possible products: monohydrosilylated products 3a, 4a,
and 5a (depending on the regioselectivity and
stereoselectivity), desired dihydrodsilylation product 6a, and
hydrogenation product 7a. Controlling the selectivity is the key
to making this reaction useful. Although most of the tested iron
catalysts showed poor activity or selectivity, catalyst C1b,
which has a 2,9-diaryl-1,10-phenanthroline ligand,10 gave
desired geminal bis(silane) 6a in 93% yield by NMR and 90%
isolated yield (Table 1, entries 1–10). It is worth mentioning
that catalysts based on other metals, which have been widely
used in hydrosilylation,7 gave only complex mixtures
containing none of the desired product (entries 11–14).
Replacing the iron in C1b with other metals afforded
complexes that were inactive for the hydrosilylation reaction
(see Table SI for details). In addition to EtMgBr, reductants
such as MeMgCl, NaBHEt3, LiAlH4, and LiCH2TMS also
promoted the hydrosilylation but gave only moderate to poor
selectivity for geminal bis(silanes) (Table 1, entries 15–18).
Hydrosilylation promoted by C1b in the presence of EtMgBr
could also be performed in benzene or toluene with
satisfactory yields (entries 19 and 20).
3
4
5
6
7
8
9
Ar
Ar
Ar
N
Ar
N
N
N
N
N
Me
Me
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Fe
Fe
Fe
Fe
N
N
Ar
Ar
Ar
C2
(Ar = 2,4,6-Et3C6H2)
C1a
C1b
C1c
C3
(Ar = 2,6-iPr2C6H3) (Ar = 2,6-iPr2C6H3)
C4
Ar = 2,4,6-(Me)3C6H2
Ar = 2,4,6-(Et)3C6H2
Ar = 2,4,6-( Pr)3C6H2
i
Me
Ar
10
11
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Ph
Ph
Ph
Ph
PiPr2
Cl
Ph
N
N
N
Cl
Cl
P
P
Cl
Cl
N
N
Cl
Cl
Fe
Fe
Fe
N
Fe
Cl
Ph
Ph
N
Ph
Me
Ar
C5
C8
C6
C7
(Ar = 2,6-iPr2C6H3)
Me
PPh2
Me Si
O
Me Si
Me
Ph3P
Ph3P
Cl

PdCl2
Pt
O
Ni
OMe
H2PtCl6.6H2O
Cl
Si
Me Me
C10
2
C12
C11
C9
(Karstedt's catalyst)
Table 1. Iron-Catalyzed Dihydrosilylation of Pent-4-yn-
1-ylbenzene with PhSiH3: Optimization of Reaction
Conditions.
SiH2Ph
3
Ph
SiH2Ph
3
Ph
SiH2Ph Ph
4a
3
catalyst (5 mol %)
reductant (12 mol %)
3a
5a
Scheme 2. Iron-Catalyzed Dihydrosilylation of Terminal
Alkynes: Substrate Scopea
3
Ph
PhSiH3
+
solvent, 30 oC, 6 h
SiH2Ph
SiH2Ph
2a
1a
3
C1b
Ph
SiH2Ph
(5 mol %)
(2.2 equiv)
3
Ph
SiH2R2
EtMgBr (12 mol %)
R1
7a
6a
R2SiH3
R1
+
SiH2R2
THF, 30 oC, 6 or 12 h
2
entrya catalyst reductant conv. 3a/4a/5a/6a/7ab
1
6
(2.2 equiv)
(%)b
6b
X=H, , 88% yield
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
6c
X=Me, , 87% yield
1
2c
C1a
C1b
C1c
C2
EtMgBr
EtMgBr
EtMgBr
EtMgBr
EtMgBr
EtMgBr
EtMgBr
EtMgBr
EtMgBr
EtMgBr
none
100
100
100
<5
26/0/0/69/0
0/0/0/93/0
51/0/0/30/15
0/0/0/0/0
6d
X=NMe2, , 95% yield
Ph
3
6e
X=F, , 85% yield
X
6a
92% yield
6g
89% yield
6f
X=Cl, , 86% yield
3
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
Me
4
SiH2Ph
Me
3
TMSO
2
Me
5
6h
86% yield
6i
88% yield
6j
6k
91% yield
5
C3
100
30
62/27/0/0/0
18/5/0/0/0
0/0/0/0/0
88% yield (86% yield)c
6
C4
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
Me
O
O
7
C5
<5
2
SiH2Ph
BnO
p-Tol
tBu
4
O
3
Me
Me
6m
87% yield b
6l
6n
93% yield
8
C6
100
100
<5
5/0/43/38/0
45/10/39/0/0
0/0/0/0/0
95% yield
9
C7
SiH2(nC12H25
)
Me SiH2Ph
SiH2Ph
SiH2Ph
SiH2Ph
SiH2(nC12H25
)
10
11
12
13
14
15
16
17
18
19d
20e
C8
Ph
S
Ph
SiH2Ph
SiH2Ph
6o
6p
86% yield
6q
6r
90% yield
C9
100
100
100
100
100
20
22/0/0/0/0
15/0/0/0/0
33/0/0/0/0
27/5/0/0/0
35/0/0/58/0
17/0/0/0/0
68/0/0/25/0
69/0/0/24/0
0/0/0/93/0
0/0/0/88/0
90% yield
86% yield
C10
C11
C12
C1b
C1b
C1b
C1b
C1b
C1b
none
SiHPh2
C3H7
SiH2Ph
none
C3H7
SiHPh2
SiHPh2
Ph
3t 4t
C6H13
none
3u
(
/
= 8.9:1)
3v
64% yield
3s
72% yield
90% yield
92% yield
MeMgCl
NaBHEt3
LiAlH4
a Reaction conditions: 1 (0.35 mmol), R2SiH3 (0.8 mmol), C1b
(0.0175 mmol, 5 mol %), EtMgBr (0.042 mmol, 12 mmol %) in
100
o
b
THF (1 mL) at 30 C. Used 10 mol % C1b and 24 mol %
c
LiCH2TMS 100
EtMgBr. Game-scale experiment: 1j (10 mmol), PhSiH3 (22
mmol), C1b (0.5 mmol, 5 mol %), EtMgBr (1.2 mmol, 12 mmol
EtMgBr
EtMgBr
100
100
%) in THF (25 mL) at 30 oC.
a Reaction conditions: 2a (0.35 mmol), PhSiH3 (0.8 mmol),
catalyst (5 mol %), reductant (12 mol %) in THF (1 mL) at 30
oC. b Determined by 1H NMR using 1,3,5-trimethoxybenzene as
Under the optimal reaction conditions (Table 1, entry 2),
reactions of PhSiH3 with various terminal alkyne substrates
were then evaluated (Scheme 2). All the tested substrates with
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linear alkyl substituents (1a–1o) underwent dihydrosilylation
1
to generate the corresponding geminal bis(silanes) (6a–6o) as
the sole hydrosilylation products in good to high yields. Various
functional groups, including amino (6d), fluoro (6e), chloro
(6f), siloxy (6k), alkoxy (6l and 6m), alkenyl (6m), acetal (6n),
and thioether (6o), were tolerated. Reactions of terminal
alkynes having bulkier, branched alkyl substituents also ran
smoothly under the standard conditions and gave satisfactory
yields of the desired products (6p and 6q). In addition to
phenylsilane, an alkylsilane (n-C12H25SiH3) could also be used
as a silylation reagent to afford 6r. The reaction of PhSiH3 and
substrate 1j was carried out on a gram scale with no loss in
yield, and the ligand of C1b could be recovered in 87% yield
after work-up (see SI for details). The catalyst was sensitive to
the steric hindrance of the substrates: the reactions of PhSiH3
with tert-butylacetylene (1s), 1-arylacetylenes (1t), and
internal alkynes (1u) only afforded mono-hydrosilylation
products 3s, 3t/4t, and 3u, respectively; the reaction of 1-
octyne (1i) with secondary silane (e.g. Ph2SiH2) afforded the
monohydrosilylation product 3v, while the reactions with
tertiary silanes, including (EtO)3SiH and Et3SiH were totally
inactive. The catalyst was sensitive toward functional groups
that can generate free protons or with strong coordinating
ability (e.g. hydroxy, carbonyl, nitro, nitrile, and amide).
To elucidate the mechanism, we monitored the reaction by 1H
NMR (Scheme 3a). Kinetic plots revealed the hydrosilylation of
1a initially gave vinylsilane E-3a (within 10 min),11 which was
then transformed to geminal bis(silane) 6a via a second
hydrosilylation in a regiospecific manner. Interestingly, the
mono-hydrosilylation of 1a with PhSiH3 promoted by the iron
catalyst modified with a tridentate pyridine diamine ligand
(C9) conducted by Tomas and coworkers resulted in Z-3a
instead.9 These results indicate that different ligands might
lead to different mechanisms in iron-catalyzed alkyne
hydrosilylation. Reaction of E-3a with n-dodecylsilane under
standard conditions afforded the geminal bis(silane) 6s in 73%
yield (Scheme 3b). When deuterated silane (PhSiD3) was used
instead of PhSiH3, the corresponding geminal bis(silane) (6g-
d) was obtained without obvious redistribution of the
deuterium between the products (Scheme 3c). These results
clearly indicate that the reaction proceeded via two highly
regioselective iron-catalyzed hydrosilylation reactions to
produce the geminal bis(silane).
Based on the control experiments and by analogue with the
hydrosilylation of unfunctionalized internal alkenes catalyzed
by similar iron catalysts,10 we proposed a catalytic cycle for the
second hydrosilylation (Scheme 4). The process of hydrogen
migration (from Int-1 to Int-2 via TS-1) is the regioselectivity-
determining step. We attribute this selectivity mainly to the α-
silicon effect of vinyl silane intermediate. Because the
electronegativity of Si atom is smaller than that of C atom, the
charge density of β-position of the vinyl silane is significantly
lower than its α-position. Thus, the hydride of iron catalyst
prefers to attacked β-position of the vinyl silane to give geminal
bis(silane) accordingly. The density functional calculation also
suggests that the energy barrier of α-selectivity is 6.9 kcal/mol
lower than that of β-selectivity (see Figure SX for details).
2
3
4
5
6
7
8
9
10
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43
44
45
46
47
48
49
50
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57
58
59
60
Scheme 4. Proposed Mechanism of Second Hydrosilylation
-
+
[Si]
[Si]
Me
N
[Si]
Me
Fe
+
H
-
N
[Si]
Int-1
Me
Ar
Ar
[Si]
Fe
N
[Si]
Fe
N
N
Me
N
=
N
Me
N
[Si]
H
N
N
H
TS-2
TS-1
[Si] = PhH2Si-
[Si]
N
N
[Si]-H
Fe
Me
Int-2
Unlike the known geminal bis(silanes) with quaternary silyl
groups,3–6 the geminal bis(silanes) produced in this study have
secondary silyl groups. The four Si–H bonds of 6 can undergo
various transformations, which makes them synthetically
useful. For instance, the Si–H bonds of 6j could be transformed
to Si–O bonds (7a–7e) or Si–F (7f) bonds with good yields
(Scheme 5a). After the modification of the silyl groups of the
geminal bis(silanes), their C–Si bonds became easy to
functionalize. For instance, pinacol-hmodified compound 7b
could easily be converted to alkene 8 with excellent E-
selectivity in the presence of CsF (Scheme 5b).12 More
interestingly, methoxy-modified compound 7a underwent a
tandem Hayama coupling/oxidation reaction to give 9. In
addition, the two C–Si bonds of 7a could be transformed into a
C–C bond and a C–O bond, respectively (Scheme 5c). Finally,
geminal bis(silane) 6j could be used to synthesize new
Scheme 3. Control Experiments
a) Monitoring the reaction process
Yield (%)
C1b
(5 mol %)
EtMgBr (12 mol %)
6a
SiH2Ph
SiH2Ph
3
Ph
+
PhSiH3
THF, 30 o
C
3
Ph
1a
2a
6a
(2.2 equiv)
3a
3
Ph
SiH2Ph
3a
E-
Time (min)
13
b) Iron-catalyzed hydrosilylation of silyl alkene 3a
C1b
polydentate hybrid organic–inorganic xerogels (10 and 11)
or spherosilicone 1214 through simple condensation with
water or 2,2-bis(hydroxymethyl)propane-1,3-diol in the
presence of a [RuCl2(p-cymene)]2, Pd(dba)2 or NaOH as a
catalyst, respectively (Scheme 5d). The diamantane-like 12
represent a new type spherosilicone. Again, these results
demonstrate that this iron-catalyzed dihydrosilylation of
alkynes affords a new type of geminal bis(silane) and
accordingly opens up the possibilities for other uses of geminal
bis(silanes).
(5 mol %)
SiH2Ph
EtMgBr (12 mol %)
Ph
SiH2Ph
(nC12H25)SiH3
+
3
Ph
SiH2(nC12H25
)
THF, 30 oC, 6 h
3
3a
2b
E-
6s
(1.1 equiv)
73% yield
c) Deuterium labelling experiment
C1b
(5 mol %)
SiD2Ph
SiD2Ph
EtMgBr (12 mol %)
PhSiD3
+
THF, 30 oC, 6 h
D
D
1g
2a-d
6g-d
82% yield
(2.2 equiv)
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Journal of the American Chemical Society
Page 4 of 6
In summary, we have described a protocol for iron-catalyzed
Notes
1
2
3
4
5
6
7
8
dihydrosilylation reactions between aliphatic terminal alkynes
and primary silanes, which produces geminal bis(silanes) with
secondary silyl groups. Because the products contain Si–H
bonds, which permit various previously unreported
The authors declare no competing financial interest.
ACKNOWLEDGMENT
transformations, this protocol not only provides
a
straightforward route to geminal bis(silanes) but also
enhances the utility of these silane reagents. Work on
extending the substrate scope of the reaction and transforming
the geminal bis(silane) products obtained by means of this
protocol is underway in our laboratory and will be reported in
due course.
We thank the National Natural Science Foundation of China
(21625204), the “111” project (B06005) of the Ministry of
Education of China, the National Program for Special Support
of Eminent Professionals, and the Fundamental Research
Funds for the Central Universities for financial support. This
paper is dedicated to the 100th anniversary of Nankai
University.
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58
59
60
Scheme 5. Transformations of the Products.
REFERENCES
a) Transformations of Si-H bonds of 6j
SiF2Ph
Si(OMe)2Ph
(c)
1. For selected recent reviews, see: (a) Bauer, I.; Knölker, H.-J. Iron
Catalysis in Organic Synthesis. Chem. Rev. 2015, 115, 3170. (b)
Greenhalgh, M. D.; Jones, A. S.; Thomas, S. P. Iron-Catalysed
Hydrofunctionalisation of Alkenes and Alkynes. ChemCatChem
2015, 7, 190. (c) Guo, N.; Zhu, S.-F. Iron-Catalyzed Hydrogenation
Reactions. Chin. J. Org. Chem. 2015, 35, 1383. (d) Shang, R.; Ilies,
L.; Nakamura, E. Iron-Catalyzed C–H Bond Activation. Chem. Rev.
2017, 117, 9086. (e) Chen, J.-H.; Lu, Z. Asymmetric
Hydrofunctionalization of Minimally Functionalized Alkenes via
Earth Abundant Transition Metal Catalysis, Org. Chem. Front.
2018, 5, 260.
2. Ojima, I. In The Chemistry of Organic Silicon Compounds, Vol.
1; Patai, S., Rappoport, Z., Eds.; Wiley: Chichester, U.K., 1989;
Chapter 25.
3. For a review, see: (a) Gao, L.; Zhang, Y.; Song, Z. Exploration
of Versatile Geminal Bis(silane) Chemistry Synlett 2013, 24, 139.
For selected examples, see: (b) Corriu, R. J. P.; Granier, M.;
SiH2Ph
C6H13
(a)
C6H13
7a
C6H13
SiF2Ph
, 81% yield
Si(OMe)2Ph
, 91% yield
SiH2Ph
6j
7f
(b)
(a)
R1
R2
(b)
Ph
Si
R3
Me
Me
O
R4
Ph
Si
O
O
Ph
Si
O
C6H13
Si
Si
Ph
O
Ph
C6H13
C6H13
O
O
Ph
O
Si
O
R1
O
O
O
R2
3 R4
R
R1,R2,R3,R4 = Me,
R1,,R3 = Ph, R2,R4
70% yield
7b,
=
Me Me
7d
,
7c
, 68% yield
H
, 68% yield
7e
, 76% yield
b) Olefination of 7b under neutral conditions
Ph
CsF (10 mol %)
Si(Pin)Ph
N
C6H13
C6H13
Ph
62% yield
+
4A MS, DMF, 80 oC, 24 h
Si(Pin)Ph
7b
8
Ph
H
c) Cross coupling and oxidation of 7a
Pd(tBu3P)2 (5 mol%)
tBuOK (3 equiv)
Si(OMe)2Ph
K2CO3/H2O2
Ar
Lanneau
G.
F.
Synthesis
and
Reactivity
of
C6H13
C6H13
ArI
+
dioxane, 80 oC, 16 h
rt, 6 h
Si(OMe)2Ph
OH
Bis(triethoxysilyl)methane, Tris(triethoxysilyl)methane and Some
Derivatives. J. Organometal. Chem. 1998, 562, 79. (c) Williams, D.
R.; Morales-Ramos, A. I.; Williams, C. M. Reactivity Studies of
3,3-Bis(trimethylsilyl)-2-Methyl-1-Propene in Lewis Acid-
Catalyzed Allylation Reactions. Org. Lett. 2006, 8, 4393. (d) Yin,
Z.; Liu, Z.; Huang, Z.; Chu, Y.; Hu, J.; Gao, L.; Song, Z. Synthesis
7a
72% yield
70% yield
58% yield
9a Ar = Ph
9b Ar = 4-OMeC6H4
9c Ar = 4-CF3C6H4
d) Potential Applications in Organic Silicon Materials
Ph
Si
[RhCl2(p-cymene)]2
C7H15
O
O
SiH2Ph
O
NaOH (10 mol%)
Ph
(2 mol%)
C6H13
O
Si
Si
of
Functionalized
γ‑Lactone
via
Sakurai
exo-
THF/H2O, 55 o
C
THF/H2O, 60 o
C
Si
O
O
n
SiH2Ph
6j
Si
O
Ph Ph
C7H15
Ph
Si
Cyclization/Rearrangement of 3,3-Bis(silyl) Enol Ester with a
Tethered Acetal. Org. Lett. 2015, 17, 1553. (e) Li, L.; Chu, Y.; Gao,
L.; Song, Z. Geminal Bis(silane)-Controlled Regio- and
Stereoselective Oxidative Heck Reaction of Enol Ethers with
Terminal Alkenes to Give Push–Pull 1,3-Dienes. Chem. Commun.
2015, 51, 15546. (f) Liu, Z.; Lin, X.; Yang, N.; Su, Z.; Hu, C.; Xiao,
P.; He, Y.; Song, Z. Unique Steric Effect of Geminal bis(silane) to
Control the High exo-Selectivity in Intermolecular Diels-Alder
Reaction. J. Am. Chem. Soc. 2016, 138, 1877. (g) Chu, Z.; Wang,
K.; Gao, L.; Song, Z. Chiral Crotyl Geminal Bis(silane): A Useful
Reagent for Asymmetric Sakurai Allylation by Selective
Desilylation-Enabled Chirality Transfer. Chem. Commun. 2017, 53,
3078. (h) Zhang, Y.; Guo, Q.; Sun, X.; Lu, J.; Cao, Y.; Pu, Q.; Chu,
Z.; Gao, L.; Song, Z. Total Synthesis of Bryostatin 8 Using an
Organosilane-Based Strategy. Angew. Chem. Int. Ed. 2018, 57, 942.
4. Corriu, R. J. P.; Granier, M.; Lanneau, G. Synthesis and
O
C7H15
Ph
12,
HO
HO
OH
Pd(dba)2 (2 mol%)
THF, 60 o
10
, 63% yield
77% yield
C
OH
Ph Ph
O
Ph
O
O
O
Si
Si
O
Si
Si
O
n
O
O
Ph
C7H15
C7H15
11
, 50% yield
(Mn = 4230, Mw/Mn = 1.77)
Reaction conditions: (a) 0.5-2 mol % [RuCl2(p-cymene)]2, diol,
THF/Et2O; (b) 10 mol % NaOH, pinacol, THF, 65 oC; (c) 5 mol %
CuI, 4 equiv CuCl2, 4 equiv CsF, Et2O.
ASSOCIATED CONTENT
Supporting Information
Experimental procedures, spectral data, and computational
study results. The Supporting Information is available free of
charge via the Internet at http://pubs.acs.org.
Reactivity
of
Bis(triethoxysilyl)methane,
Tris(triethoxysilyl)methane and Some Derivatives. J. Organometal.
Chem. 1998, 562, 79.
5. Liu, Z.; Tan, H.; Fu, T.; Xia, Y.; Qiu. D.; Zhang, Y.; Wang, J.
Pd(0)-Catalyzed Carbene Insertion into Si-Si and Sn-Sn Bonds. J.
Am. Chem. Soc. 2015, 137, 12800.
AUTHOR INFORMATION
Corresponding Author
6. Hazrati, H. Oestreich, M. Copper-Catalyzed Double C(sp3)-Si
Coupling of Geminal Dibromides: Ionic-to-Radical Switch in the
Reaction Mechanism. Org. Lett. 2018, 20, 5367.
* sfzhu@nankai.edu.cn
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7. (a) Marciniec, B. (Ed.), Hydrosilylation, A Comprehensive
Complexes and Their Application to Catalytic Hydrogenation and
Hydrosilation. J. Am. Chem. Soc. 2004, 126, 13794. (b) Belger, C.;
Plietker, B. Aryl–Aryl Interactions as Directing Motifs in the
Stereodivergent Iron-Catalyzed Hydrosilylation of Internal
Alkynes. Chem. Commun. 2012, 48, 5419. (c) Challinor, A. J.;
Calin, M.; Nichol, G. S.; Carter, N. B.; Thomas, S. P. Amine-
Activated Iron Catalysis: Air- and Moisture-Stable Alkene and
Alkyne Hydrofunctionalization. Adv. Synth. Catal. 2016, 358, 2404.
(d) Docherty, J. H.; Peng, J.; Dominey, A. P.; Thomas, S. P.
Activation and Discovery of Earth-Abundant Metal Catalysts using
Sodium tert-Butoxide. Nature Chem. 2017, 9, 595.
1
2
3
4
5
6
7
8
Review on Recent Advances, Spring, 2009. (b) Du, X.; Huang, Z.
Advances in Base-Metal-Catalyzed Alkene Hydrosilylation. ACS
Catal. 2017, 7, 1227. (c) Obligacion, J. V.; Chirik, P. J. Earth-
Abundant Transition Metal Catalysts for Alkene Hydrosilylation
and Hydroboration, Nat. Rev. Chem. 2018, 2, 15.
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V. P.; Tolstikov, G. A. Bulletin of the Academy of Sciences of the
USSR, Division of Chemical Science (English Translation) 1982,
31, 806. (b) Grutzmacher, H.; Liedtke, J.; Loss, S.; Widauer C.
Phosphiranes as Ligands for Platinum Catalysed Hydrosilylations.
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Silanes via Regiospecific Hydrosilylation of Vinylsilanes. J. Mol.
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Zaranek, M.; Witomska, S.; Bocian, A.; Stefankiewicz, A. R.;
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Tridentate Schiff-Base Ligand as a Catalyst for Hydrosilylation of
Olefins. Catal. Commun. 2016, 78, 71.
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Chemo-, Regio-, and Stereoselective Hydrosilylation of Alkenes
and Alkynes Using a Bench-Stable Iron(II) Pre-catalyst. Adv. Synth.
Catal. 2014, 356, 548.
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J.; Peng, Q.; Zhu, S.-F. Ligands with 1,10-Phenanthroline Scaffold
for Highly Regioselective Iron-Catalyzed Alkene Hydrosilylation.
Nature Commun. 2018, 9, 221.
9
12. OShea, D. F.; Das M.; Manvar, A. Stereoselective Peterson
Olefinations from Bench-Stable Reagents and n-Phenyl Imines.
Chem. Eur. J. 2015, 21, 8737.
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13
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15
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17
18
19
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21
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23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
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48
49
50
51
52
53
54
55
56
57
58
59
60
13. (a) Loy, D. A.; Shea, K. J. Bridged Polysilsesquioxanes. Highly
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Molecular Chemistry for Sol-gel Processes. Angew. Chem. Int. Ed.
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Organic-Inorganic Silica Materials. ACS Symp. Ser. 1995, 585, 210.
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Commun. 2008, 5625.
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and Electronic Structures of Iron(0) Dinitrogen and Silane
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Graphic for TOC
1
2
3
4
5
6
7
8
9
Ar
[Fe] (5 mol %)
EtMgBr (12 mol %)
SiH2R2
R1
N
R2SiH3
R1
Cl
Cl
+
SiH2R2
THF, 30 o
C
Fe
(2.2 equiv)
N
85-95% yield
regiospecific
Ph
Ar
Si
C7H15
Ph
[Fe]
O
O
Ph
Si
Si
Si
O
O
SiX2Ph
OH
C6H13
Ar
C7H15
Ph
C6H13
C6H13
Ph
SiX2Ph
X = OR3, F
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
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39
40
41
42
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44
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60
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