Copper(I)-catalyzed highly regio- and stereoselective hydrosilylation of terminal alkynes with boryldisiloxane

Article abstract of DOI:10.1002/cctc.201402405

By employing 1,1,3,3-tetramethyl-1,3-(pinacolboryl)disiloxane as a novel silicon source, the N-heterocyclic carbene copper complex catalyzed hydrosilylation of terminal alkynes was developed to prepare vinyldisiloxanes in a highly regio- and stereoselective manner. A number of functional groups, including ether, ester, cyano, nitro, halo, hydroxyl, cyclopropyl, and aryl groups, were tolerated under the optimized conditions. A mechanistic investigation was undertaken by using density functional theory calculations. This approach allows facile entry to unsymmetrical disubstituted (E)-alkenes by Pd-catalyzed cross-coupling reactions.

Full text of DOI:10.1002/cctc.201402405

CHEMCATCHEM
COMMUNICATIONS
DOI: 10.1002/cctc.201402405
Copper(I)-Catalyzed Highly Regio- and Stereoselective
Hydrosilylation of Terminal Alkynes with Boryldisiloxane
Hui Zhou* and Yan-Bo Wang[a]
By employing 1,1,3,3-tetramethyl-1,3-(pinacolboryl)disiloxane
as a novel silicon source, the N-heterocyclic carbene copper
complex catalyzed hydrosilylation of terminal alkynes was de-
veloped to prepare vinyldisiloxanes in a highly regio- and ste-
reoselective manner. A number of functional groups, including
ether, ester, cyano, nitro, halo, hydroxyl, cyclopropyl, and aryl
groups, were tolerated under the optimized conditions. A
mechanistic investigation was undertaken by using density
functional theory calculations. This approach allows facile entry
to unsymmetrical disubstituted (E)-alkenes by Pd-catalyzed
cross-coupling reactions.
icon source, CuCl bearing a phosphine ligand catalyzed the hy-
drosilylation of terminal alkynes to selectively form a-vinylsi-
lanes, in which the hydrogen atom was provided by added al-
cohols. Unfortunately, the regioselectivity was decreased with
the use of electron-deficient substrates. Very recently, N-heter-
ocyclic carbene (NHC)–copper(I) complexes were found to be
more efficient catalytic systems for the above reaction, and
they afforded b-(E)-vinylsilanes with high regio- and stereose-
lectivity (>98% E and b).[12] During the preparation of this
manuscript, Calderone and Santos[13] and Lipshutz[14] succes-
sively reported the copper-catalyzed hydrosilylation of elec-
tron-deficient internal alkynes by using Me2PhSiB(pin) in water
at room temperature to selectively afford b-silyl-a,b-unsaturat-
ed carbonyl compounds.
Vinylsilanes are versatile building blocks in organic synthesis[1]
because of their extensive applications in protodesilylations,[2]
Tamao–Fleming oxidations,[3] Hiyama–Denmark cross-coupling
reactions,[4] and other transformations.[5] Although numerous
successful catalytic processes, such as the hydrosilylation of al-
kynes with SiÀH reagents,[6] have been described to access
these types of compounds, efforts to increase the catalytic ac-
tivity and to control reaction selectivity with high substrate tol-
erance continue.
Silylcupration[7] of carbon–carbon triple bonds followed by
protonation is one of the most attractive routes to generate vi-
nylsilanes with complete syn stereoselectivity. However, stoi-
chiometric amounts of Fleming’s silyl cuprate reagents (CuÀSi)
by employing silyl–lithium (SiÀLi)[8] or silyl–stannane (SiÀSn)[9]
reagents as the silicon sources are needed for this transforma-
tion. Recently, much attention has been directed toward the
catalytic formation of functionalized vinylsilanes under copper
catalysis, in which the key CuÀSi species arise from activation
of disilane (SiÀSi)[10] or silylborane (SiÀB) reagents[11–14]
(Scheme 1).
However, thus far only Me2PhSiB(pin) has been used in all re-
ported transformations, and the scant number of SiÀB re-
agents available has limited broader application of copper-cat-
alyzed hydrosilylation reactions. Considering that vinylsilanes
bearing oxygen substituents at silicon have higher reactivity
and more diversity of reactions than their dimethylphenyl
counterparts,[3b,4] we sought to establish the CuI-catalyzed hy-
drosilylation of terminal alkynes by employing a novel boryldi-
siloxane reagent to selectively provide b-(E)-vinyldisiloxanes
under mild conditions.
We initiated our studies by using the known MeOMe2SiB(pin)
reagent[16] as the oxygen-substituted silicon source for the hy-
drosilylation of phenylacetylene (Scheme 2). The reaction pro-
ceeded smoothly in a cis manner in the presence of CuCl
(1 mol%), PPh3 (1.2 mol%), and NaOtBu (1.2 mol%) in THF at
room temperature for 1h to give the constitutional isomer
The first copper(I)-catalyzed system for the hydrosilylation of
alkynes conjugated to carbonyl groups was reported by Mo-
lander’s group, who used diphenyltetramethyldisilane to
obtain b-silyl-a,b-unsaturated carbonyl mixtures with different
E/Z ratios in moderate yields.[10] Me2PhSiB(pin) (pin=pinacola-
to), an important silylborane (SiÀB) reagent owing to its versa-
tile synthetic transformations, has been widely researched to
effectively synthesize silicon- and/or boron-functionalized syn-
thons.[15] Loh[11] reported that by using Me2PhSiB(pin) as the sil-
[a] Dr. H. Zhou, Dr. Y.-B. Wang
State Key of Laboratory of Fine Chemicals
Dalian University of Technology
Dalian 116024 (P.R. China)
E-mail: zhouhui@dlut.edu.cn
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201402405.
Scheme 1. Cu reagents involved in the hydrosilylation of alkynes by using
different silicon sources.
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 0000, 00, 1 – 5
&
1
&
ÞÞ
These are not the final page numbers!

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
ligand (Table 1, entry 1). The use of monodentate
phosphines, such as PPh3 and PCy3 (Cy=cyclohexyl),
generated sole product (b,b)-(E)-3a in 54 and 72%
yield, respectively, with high selectivity (Table 1, en-
tries 2 and 3), whereas a small amount of the (a,b)-(E)
regioisomer was formed with PEt3 (Table 1, entry 4).
Formation of the (a,a)-(E) regioisomer became more
Scheme 2. MeOMe2SiB(pin) reagent involved in the hydrosilylation catalyzed by a CuI
complex.
preferable
with
the
use
of
PtBu3
and
P(tBu)2(biphenyl-2-yl), which indicates that sterically
demanding phosphines are able to control the regio-
selectivity of the reaction (Table 1, entries 5 and 6).
having the silyl group at the terminal position as the sole
product in 52% yield (b/a>99:1; E/Z>99:1). No other isomers
were detected in a solution of the crude reaction mixture by
400 MHz 1H NMR spectroscopy. Because MeOMe2SiB(pin) is
sensitive to air and moisture, strict Schlenk operations were
needed for the whole reaction process.
Similar ligand-controlled hydrosilylation of terminal alkynes
was reported by Loh and co-workers[11] by employing
Me2PhSiB(pin) to afford a-(E)-vinylsilanes as the major re-
gioisomers. CuCl bearing NHC ligands showed more reactivity
to synthesize 3a with complete regio- and stereoselectivity,
and the less bulky 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-yli-
dene (IMes) ligand provided a higher yield than 1,3-bis(2,6-dii-
sopropylphenyl)imidazol-2-ylidene (IPr) (Table 1, entries 7 and
8). Further research showed that isolated (IMes)CuCl was also
highly active for this transformation (Table 1, entry 9).
Novel, stable SiÀB reagents with high hydrosilylation activity
were further developed by introducing the SiÀOÀSi moiety,
which generally exists in stable silicates and SiO2 materials.
1,1,3,3-Tetramethyl-1,3-(pinacolboryl)disiloxane (1) was success-
fully obtained as the oxygen-functionalized SiÀB reagent by re-
action of ClMe2SiB(pin)[16] with H2O in THF at room tempera-
ture for 24 h, as shown in Scheme 3, on the basis of our knowl-
We next evaluated the scope of the copper-catalyzed hydro-
silylation of terminal alkynes with boryldisiloxane 1. With the
optimized procedure and by using (IMes)CuCl as the catalyst,
a variety of terminal alkynes bearing various functional groups
and substitution patterns were tested in the selective synthesis
of the corresponding (b,b)-(E)-vinyldisiloxanes, and the results
are summarized in Table 2.
Scheme 3. Synthesis of 1,1,3,3-tetramethyl-1,3-(pinacolboryl)disiloxane (1).
Table 1. Copper(I)-catalyzed hydrosilylation of phenylacetylene with
boryldisiloxane 1.[a]
edge of silylboration[17] and hydrosilylation[18] of 1,3-enynes. By
SiO2 column chromatography with the use of I2 as a chromo-
genic agent, white solid 1 was easily isolated in 83% yield. The
1H NMR spectrum showed two singlets at d=0.18 and
1.22 ppm, which were attributed to the methyl groups on the
silicon atom and pinacolborane, respectively.
In contrast to the previously reported SiÀB reagents,[15,16]
boryldisiloxane 1 is air and moisture stable owing to the effect
of the SiÀOÀSi structure. Single crystals were obtained from n-
Entry
Ligand
Yield [%][b]
(b,b)/(a,b/(a,a)[c]
pentane solution, and the molecular structure was confirmed
by X-ray crystallography (see Figure S1 in the Supporting Infor-
mation). The two SiÀB bonds [2.032(2) and 2.027(2) ꢁ] are
close to those of the tri- and tetrasilylborates [(Me3Si3)BR]Li
(R=Me, SiMe3, ꢀ2.017–2.034 ꢁ).[19] The SiÀOÀSi angle of 1 is
143.46(9)8, which shows a similar structural motif in silica
gel.[20]
1
2
3
4
5
6
7[d]
8[d]
9[e]
–
PPh3
PCy3
PEt3
PtBu3
PtBu2(biphenylyl)
IPr·HCl
IMes·HCl
–
–
54
72
75
45
25
80
85
88
–
>99:1:<1
>99:1:<1
96:4:<1
29:28:43
2:27:71
>99:1:<1
>99:1:<1
>99:1:<1
We first performed the hydrosilylation reaction of phenylace-
tylene (2a, 0.3 mmol) with boryldisiloxane 1 (0.125 mmol) and
methanol (4.0 equiv.) in the presence of CuCl (1 mol%) bearing
monodentate ligands (1.2 mol%) and NaOtBu (1.2 mol%) as
a catalyst in THF at room temperature for 2 h (Table 1). Three
isomeric vinyldisiloxanes products, (a,a)-(E)/(a,b)-(E)/(b,b)-(E),
can be provided by cis addition. The results demonstrate that
the ligands clearly affected the activity and selectivity of the
hydrosilylation. No reaction occurred in the absence of the
[a] Reaction conditions: SiÀB reagent 1 (0.125 mmol), 2a (0.3 mmol), [Cu]
(1 mol%), NaOtBu (1.2 mol%), MeOH (0.5 mmol), THF (1 mL), RT, 2 h,
unless otherwise noted. [b] Yield of isolated product. [c] Determined by
analysis of the crude mixture by 1H NMR spectroscopy. [d] NaOtBu
(2.4 mol%). [e] (IMes)CuCl as catalyst.
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 0000, 00, 1 – 5
&
2
&
ÞÞ
These are not the final page numbers!

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
Table 2. Copper(I)-catalyzed hydrosilylation of various terminal alkynes
with boryldisiloxane 1.[a]
Entry
1
Product
Yield[%][b]
86
3b
2
3
4
3c
3d
3e
81
80
78
Scheme 4. A plausible mechanism for the hydrosilylation of terminal alkynes
with boryldisiloxane 1.
5
6
3 f
92
90
In the absence of MeOH, the hydrosilylation of propargyl al-
cohol 2m with boryldisiloxane 1 also proceeded smoothly
under the optimized conditions. A proton was effectively pro-
vided by 2m itself, and after hydrolysis[21] desired product 3m
was conveniently isolated by SiO2 flash chromatography in
90% yield.
3g
7
3h
70
8
9
3i
3j
85
92
A possible catalytic cycle for the hydrosilylation of terminal
alkynes is proposed, as shown in Scheme 4. Initially, the reac-
tion of the NHC–CuICl complex with NaOtBu smoothly pro-
ceeds to form CuOtBu complex A.[22] This is followed by s-
bond metathesis with boryldisiloxane,[23] from which silylcop-
per complex B is generated. Subsequent insertion of the termi-
nal alkyne into the CuÀSi bond of B selectively affords b-silylvi-
nylcopper complex C in a cis manner.[13] Next, protonation[12,13]
of C with MeOH provides desired hydrosilylation product D
and the NHC–CuOMe complex to complete the catalytic cycle.
According to the reaction mechanism, the regioselectivity is
effectively controlled by the insertion process. To further ex-
plain this experimental behavior, two geometries of the transi-
tion states in the insertion step of the IMesCu–SiOSiB(pin) in-
termediate to phenylacetylene (2a) were optimized with DFT
at the B3LYP/6-31G(d) level (Figure 1). The calculated results
show that the insertion step proceeds with an activation
energy barrier of 8.2 kcalmolÀ1 from TS1 in comparison to an
activation energy barrier of 13.4 kcalmolÀ1 from TS2, which
means that the IMesCuI catalytic system tends to form inter-
mediate C rather than another regioisomer, and therefore,
(b,b)-(E)-vinyldisiloxane D is selectively generated as the sole
isomer.
10
3k
3l
71
85
11
12
13
3m 92
3n
90
[a] Reaction conditions: SiÀB reagent 1 (0.125 mmol), alkyne 2 (0.3 mmol),
(IMes)CuCl (1 mol%), NaOtBu (1.2 mol%), MeOH (0.5 mmol), THF (1 mL),
RT, 2 h, unless otherwise noted. [b] Yield of isolated product; (b,b)/
(a,b)/(a,a)>99:1:<1, as determined by analysis of the crude mixture by
1H NMR spectroscopy.
The reactivity was slightly affected by both electron-donat-
ing (e.g., ÀMe and ÀOMe) and electron-withdrawing (e.g., ÀBr
and ÀNO2) groups on the aryl ring (Table 2, entries 1–4). Sub-
strates with a variety of functional groups, such as cyclopropyl,
hydroxyl, ether, ester, and cyano, were tolerated in these reac-
tions (Table 2, entries 7, 9–12) and gave products in excellent
yields with excellent selectivity. Even the sterically crowded
tert-butylethyne showed (Table 2, entry 13) high reactivity and
selectivity [90% yield, (b,b)/(a,b)/(a,a)>99:1:<1].
Vinyldisiloxane reagents, as the possible intermediates gen-
erated from organosilanol-based cross-coupling reactions[24]
catalyzed by palladium complexes in the presence of a strong
base, are useful synthetic building blocks to afford alkene de-
rivatives with a high degree of stereochemical retention.[25] As
expected, cross-coupling reactions of vinyldisiloxanes with 1-
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 0000, 00, 1 – 5
&
3
&
ÞÞ
These are not the final page numbers!

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
silylation. Further chemical transformation by Pd-catalyzed
cross-coupling reactions is an efficient approach to synthesize
unsymmetrical 1,2-disubstituted (E)-alkenes. Extension of this
method to other unsaturated substrates and their further
chemical applications are in progress.
Experimental Section
Synthesis of 1,1,3,3-tetramethyl-1,3-(pinacolboryl)disiloxane:
Under a N2 atmosphere, H2O (36 mg, 2.0 mmol) and pyridine
(160 mg, 2.0 mmol) were sequentially added by syringe to a solu-
tion of ClMe2SiB(pin) (220 mg, 1.0 mmol) in THF (10 mL) at 08C.
The mixture was stirred at room temperature for 24 h. Then, the
solvent was removed under reduced pressure, and the crude prod-
uct was purified by silica gel column chromatography (hexane/
EtOAc=20:1) to give the desired disiloxane (160 mg, 83% yield) as
a white solid. No 1,1,3,3-tetramethylpinacolborylsilanol was ob-
1
1
served by H NMR spectroscopy. H NMR (400 MHz, CDCl3): d=1.22
[s, 24H; ÀC(CH3)2], 0.18 ppm [s, 12H; ÀSi(CH3)2]; 13C NMR (100 MHz,
CDCl3): d=83.4, 25.3, 2.3 ppm; IR (film): n˜ =2981, 2933, 2897, 1376,
1247, 1146, 1034, 837, 781 cmÀ1
; HRMS (EI): m/z: calcd for
C10H24BO3Si: 259.1355 [MÀB(pin)]+; found: 259.1357.
Single crystals were obtained from n-pentane solution at À358C.
Diffraction data were collected at 77 K with a Bruker SMART-CCD
diffractometer by using graphite-monochromated MoKa radiation
(l=0.71073 ꢁ). The structures were solved by direct methods[26]
and refined by full-matrix least squares on F2. All non-hydrogen
atoms were refined anisotropically, and the hydrogen atoms were
included in idealized positions. All calculations were performed by
using the SHELXTL[27] crystallographic software packages. CCDC-
977410 contains supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
Figure 1. Transition state in the insertion step of the CuÀSi intermediate to
phenylacetylene (2a). C: gray, Cu: orange, Si: green, B: pink, O: red, and N:
blue.
iodonaphthalene and 1-chloro-4-iodobenzene catalyzed by
Pd2(dba)3/nBu4NF (dba=dibenzylideneacetone) were success-
fully realized in THF at room temperature to provide (E)-1,2-dis-
ubstituted unsymmetrical alkynes 4a and 4b in 95 and 92%
yields, respectively, without the formation of any other isomers
or protodesilylated products (Scheme 5).
Hydrosilylation of alkynes catalyzed by IMesCuCl catalyst: Inside
an Ar-filled glove box, a vial was charged with (IMes)CuCl (4.0 mg,
1 mol%), NaOtBu (1.2 mg, 1.2 mol%), and THF (2 mL). After 30 min
stirring at room temperature, phenylacetylene (2a, 1.0 mmol),
1,1,3,3-tetramethyl-1,3-(pinacolboryl)disiloxane (0.5 mmol), and
MeOH (4.0 mmol, 4.0 equiv.) were sequentially added to the solu-
tion. The resulting mixture was stirred at room temperature for
2 h. After removal of the solvents under reduced pressure, the
crude product was purified by silica gel column chromatography
(hexane) to afford 3a as a colorless liquid (88% yield). 1H NMR
(400 MHz, CDCl3): d=7.51 (d, J=7.4 Hz, 4H; PhH), 7.39 (t, J=
7.4 Hz, 4H; PhH), 7.33 (t, J=7.4 Hz, 2H; PhH), 7.05 (d, J=19.2 Hz,
2H; PhCH=), 6.54 (d, J=19.2 Hz, 2H; PhCH=CHÀ), 0.36 ppm [s,
12H, ÀSi(CH3)2]; 13C NMR (100 MHz, CDCl3): d=144.7, 138.4, 128.8,
128.5, 126.9, 1.2 ppm; IR (film): n=3082, 3020, 2959, 1617, 1575,
1499, 1253, 1048, 989, 848, 784, 689 cmÀ1; HRMS (EI): m/
In summary, we developed an efficient procedure for the hy-
drosilylation of various terminal alkynes by using a novel boryl-
disiloxane reagent as the silicon source and an inexpensive
copper complex catalyst. The products, (b,b)-(E)-vinyldisilox-
anes, were obtained as the sole detectable isomers with per-
fect regio- and stereoselectivity. Theoretical evidence from cal-
culations combined with experimental evidence explain the re-
markable selectivity of the NHC–CuI complex catalyzed hydro-
z: calcd for C20H26OSi2: 338.1522; found: 338.1532 (re-
ported in Ref. [25a]).
Cross-coupling reaction of vinyldisiloxanes: Pd2(dba)3
(5 mg, 5 mol%), 1-iodonaphthalene (51 mg, 0.2 mmol),
and nBu4NF (52 mg, 2.0 equiv.) were added to a solution
of disiloxane 3a (33 mg, 0.1 mmol) in THF (2.0 mL). The
resulting mixture was stirred at RT for 30 min. After re-
moval of the solvents, the residue was purified by
column chromatography (hexane) to afford (E)-1-styryl-
naphthalene (44 mg, 95% yield) as a colorless liquid.
1H NMR (400 MHz, CDCl3): d=8.23 (d, J=8.0 Hz, 1H),
Scheme 5. Application of vinyldisiloxane for the Pd-catalyzed Hiyama cross-coupling
reaction.
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 0000, 00, 1 – 5
&
4
&
ÞÞ
These are not the final page numbers!

CHEMCATCHEM
COMMUNICATIONS
www.chemcatchem.org
Trans. 1 1984, 1805–1808; d) H.-M. Chen, J. P. Oliver, J. Organomet.
Chem. 1986, 316, 255–260.
[9] B. H. Lipshutz, D. C. Reuter, E. L. Ellsworth, J. Org. Chem. 1989, 54, 4975–
4977.
[10] L. Iannazzo, G. A. Molander, Eur. J. Org. Chem. 2012, 4923–4926.
[11] P. Wang, X.-L. Yeo, T.-P. Loh, J. Am. Chem. Soc. 2011, 133, 1254–1256.
[12] F. Meng, H. Jang, A. H. Hoveyda, Chem. Eur. J. 2013, 19, 3204–3214.
[13] J. A. Calderone, W. L. Santos, Angew. Chem. Int. Ed. 2014, 53, 4154–
4158; Angew. Chem. 2014, 126, 4238–4242.
7.84–7.90 (m, 2H), 7.79 (d, J=8.2 Hz, 1H), 7.74 (d, J=7.2 Hz, 1H),
7.61 (d, J=8.2 Hz, 2H), 7.48–7.53 (m, 3H), 7.39 (t, J=7.8 Hz, 2H),
7.29 (dt, J=1.2, 7.4 Hz, 1 H), 7.14 ppm (d, J=16.0 Hz, 1H) (reported
in Ref. [28]).
Acknowledgements
[14] R. T. H. Linstadt, C. A. Peterson. D. J. Lippincott, C. I. Jette, B. H. Lipshutz,
Angew. Chem. Int. Ed. 2014, 53, 4159–4163; Angew. Chem. 2014, 126,
4243–4247.
[15] a) I. Beletskaya, C. Moberg, Chem. Rev. 1999, 99, 3435–3461; b) I. Belet-
skaya, C. Moberg, Chem. Rev. 2006, 106, 2320–2354; c) T. Ohmura, M.
Suginome, Bull. Chem. Soc. Jpn. 2009, 82, 29–49; d) M. Oestreich, E.
Hartmann, M. Mewald, Chem. Rev. 2013, 113, 402–441.
[16] Synthetic method of MeOMe2SiB(pin)and ClMe2SiB(pin), see: a) M. Sugi-
nome, T. Matsuda, Y. Ito, Organometallics 2000, 19, 4647–4649; b) T.
Ohmura, K. Masuda, H. Furukawa, M. Suginome, Organometallics 2007,
26, 1291–1294.
Gratitude is expressed to the Start-Up Foundation of Dalian Uni-
versity of Technology (grant 1004–852010). We are also grateful
to Prof. Xiao-Bing Lu (Dalian University of Technology) and Prof.
Christina Moberg (KTH, Royal Institute of Technology) for fruitful
discussions and Prof. Cheng He (Dalian University of Technology)
for recording the X-ray diffractograms.
Keywords: boranes · copper · cross-coupling · hydrosilylation ·
silanes
[17] H. Zhou, C. Moberg, J. Am. Chem. Soc. 2012, 134, 15992–15999.
[18] H. Zhou, C. Moberg, Org. Lett. 2013, 15, 1444–1447.
[19] Q. Jiang, P. J. Carroll, D. H. Berry, Organometallics 1993, 12, 177–183.
[20] E. Dupree, R. F. Pettifer, Nature 1984, 308, 523–525.
[21] a) C. Kleeberg, E. Feldmann, E. Hartmann, D. J. Vyas, M. Oestreich, Chem.
Eur. J. 2011, 17, 13538–13543; b) V. Cirriez, C. Rasson, T. Hermant, J. Pet-
rignet, J. D. Alvarez, K. Robeyns, O. Riant, Angew. Chem. Int. Ed. 2013,
52, 1785–1788; Angew. Chem. 2013, 125, 1829–1832.
[22] a) N. P. Mankad, D. S. Laitar, J. P. Sadighi, Organometallics 2004, 23,
3369–3371; b) L. Zhang, Z. Hou, Pure Appl. Chem. 2012, 84, 1705–
1712; c) L. Zhang, Z. Hou, Chem. Sci. 2013, 4, 3395–3403.
[23] a) E. Hartmann, D. J. Vyas, M. Oestreich, Chem. Commun. 2011, 47,
7917–7932; b) T. Fujihara, Y. Tani, K. Semba, J. Terao, Y. Tsuji, Angew.
Chem. Int. Ed. 2012, 51, 11487–11490; Angew. Chem. 2012, 124, 11655–
11658.
[1] a) E. Langkopf, D. Schinzer, Chem. Rev. 1995, 95, 1375–1408; b) I. Flem-
ing, A. Barbero, D. Walter, Chem. Rev. 1997, 97, 2063–2192; c) I. Ojima,
Z. Li, J. Zhu in The Chemistry of Organosilicon Compounds, Vol. 2 (Eds.: Z.
Rappoport, Y. Apeloig), WILEY, New York, 1998.
[2] a) P. F. Hudrlik, P. Gebreselassie, L. Tafesse, A. M. Hudrlik, Tetrahedron
Lett. 2003, 44, 3409–3412; b) S. K. Ghosh, R. Singh, G. C. Singh, Eur. J.
Org. Chem. 2004, 4141–4147; c) C. L. Heitzman, W. T. Lambert, E. Mertz,
J. B. Shotwell, J. M. Tinsley, P. Va, W. R. Roush, Org. Lett. 2005, 7, 2405–
2408; d) S. E. Denmark, J. D. Baird, Tetrahedron 2009, 65, 3120–3129.
[3] a) K. Tamao, K. Maeda, Tetrahedron Lett. 1986, 27, 65–68; b) G. R. Jones,
Y. Landais, Tetrahedron 1996, 52, 7599–7662.
[4] a) Y. Hatanaka, T. Hiyama, Synlett 1991, 12, 845–853; b) T. Hiyama, J. Or-
ganomet. Chem. 2002, 653, 58–61; c) S. E. Denmark, R. F. Sweis, Acc.
Chem. Res. 2002, 35, 835–846; d) S. E. Denmark, C. S. Regens, Acc.
Chem. Res. 2008, 41, 1486–1499; e) Y. Nakao, T. Hiyama, Chem. Soc. Rev.
2011, 40, 4893–4901; f) W.-T. T. Chang, R. C. Smith, C. S. Regens, A. D.
Bailey, N. S. Werner, S. E. Denmark, Org. React. 2011, 75, 213–746;
g) H. F. Sore, W. R. J. D. Galloway, D. R. Spring, Chem. Soc. Rev. 2012, 41,
1845–1866.
[24] S. E. Denmark, R. F. Sweis, D. Wehrli, J. Am. Chem. Soc. 2004, 126, 4865–
4875.
[25] a) H. F. Sore, C. M. Boehner, S. J. F. MacDonald, D. Norton, D. J. Foxd,
D. R. Spring, Org. Biomol. Chem. 2009, 7, 1068–1071; b) S. E. Denmark,
Z. Wang, Org. Lett. 2001, 3, 1073–1076; c) S. E. Denmark, T. Pan, Org.
Lett. 2003, 5, 1119–1122; d) Y. Sumida, T. Kato, S. Yoshida, T. Hosoya,
Org. Lett. 2012, 14, 1552–1555; e) E. C. Frye, C. J. O’Connor, D. G. Twigg,
B. Elbert, L. Laraia, D. G. Hulcoop, A. R. Venkitaraman, D. R. Spring,
Chem. Eur. J. 2012, 18, 8774–8779.
[26] SHELXTL PC; Siemens Analytical X-ray Instruments, Madison, WI, 1993.
[27] G. M. Sheldrick, SHELXTL Structure Determination Programs, version 5.0,
PC; Siemens Analytical Systems, Madison, WI, 1994.
[5] a) R. B. Miller, M. I. Al-Hassan, J. Org. Chem. 1985, 50, 2121–2123; b) T. A.
Blumenkopf, L. E. Overman, Chem. Rev. 1986, 86, 857–873.
[6] a) B. M. Trost, Z. T. Ball, J. Am. Chem. Soc. 2005, 127, 17644–17655;
b) B. M. Trost, Z. T. Ball, Synthesis 2005, 6, 853–887; c) A. K. Roy, Adv. Or-
ganomet. Chem. 2007, 55, 1–59; <lit d>Y. Fukumoto, M. Hagihara, F.
Kinashi, N. Chatani, J. Am. Chem. Soc. 2011, 133, 10014–10017; e) D. S.
Lim, E. A. Anderson, Synthesis 2012, 44, 983–1010.
[7] A. Barbero, F. J. Pulido, Acc. Chem. Res. 2004, 37, 817–825.
[8] a) I. Fleming, F. Roessler, J. Chem. Soc. Chem. Commun. 1980, 276–277;
b) I. Fleming, T. W. Newton, F. Roessler, J. Chem. Soc. Perkin Trans.
1 1981, 2527–2532; c) I. Fleming, T. W. Newton, J. Chem. Soc. Perkin
[28] Y. Li, G. Liu, C. Cao, S. Wang, Y. Li, G. Pang, Y. Shi, Tetrahedron 2013, 69,
6241–6250.
Received: June 3, 2014
Published online on && &&, 0000
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 0000, 00, 1 – 5
&
5
&
ÞÞ
These are not the final page numbers!

COMMUNICATIONS
H. Zhou,* Y.-B. Wang
&& – &&
Copper(I)-Catalyzed Highly Regio- and
Stereoselective Hydrosilylation of
Terminal Alkynes with Boryldisiloxane
Put a pin in it: The highly regio- and
stereoselective hydrosilylation of termi-
nal alkynes with 1,1,3,3-tetramethyl-1,3-
(pinacolboryl)disiloxane as a novel sili-
con source with the use of a copper
catalyst gives functionalized (b,b)-
(E)-vinyldisiloxanes in good yields. Fur-
ther chemical transformation through
Pd-catalyzed cross-coupling results in
the synthesis of unsymmetrical 1,2-
disubstituted (E)-alkenes.
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 0000, 00, 1 – 5
&
6
&
ÞÞ
These are not the final page numbers!