Stereodivergent Synthesis of β-Heteroatom-Substituted Vinyl-silanes by Sequential Silylzincation-Copper(I)-Mediated Electrophilic- Substitution

Article abstract of DOI:10.1055/s-0036-1588106

Sulfur-, oxygen-, and phosphorus-substituted terminal alkynes undergo regio- and stereoselective silylzincation by reaction with (Me₂PhSi)₂Zn, (Me₃Si)₃SiH/Et₂Zn or [(Me₃Si)₃Si]₂Zn/Et₂Zn. The addition across the C-C triple bond always occurs with β-regioselectivity but the stereoselectivity is tunable: (Me₂PhSi)₂Zn for cis and (Me₃Si)₃SiH/-Et₂Zn or [(Me₃Si)₃Si]₂Zn/Et₂Zn for trans. The procedures making use of the zinc reagents (Me₂PhSi)₂Zn and [(Me₃Si)₃Si]₂Zn can be combined in one-pot with a subsequent stereoretentive copper(I)-mediated electrophilic substitution of the intermediate C(sp²)-Zn bond. These stereodivergent protocols offer a regio- and stereoselective access to trisubstituted vinylsilanes decorated with sulfur-, oxygen-, and phosphorus substituents with either double-bond geometry.

Full text of DOI:10.1055/s-0036-1588106

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2016, 48, A–L
feature
A
C. Fopp et al.
Feature
Synthesis
Stereodivergent Synthesis of β-Heteroatom-Substituted Vinyl-
silanes by Sequential Silylzincation–Copper(I)-Mediated
Electrophilic Substitution
Carolin Foppa
Kevin Isaacb
Elise Romainb
Fabrice Chemlab
Franck Ferreirab
Olivier Jackowskib
Martin Oestreich*a
Alejandro Perez-Luna*b
(Me2PhSi)2Zn
cis-silylzincation
CuCN•2LiCl
E–X
Het
Het
[Zn]
E
Het = [S], [P]
Me2PhSi
Me2PhSi
E/Z > 98:2
59–93% yield
Het
Het = [S], [O], [P]
Het
Het
Het = [S], [O], [P]
(Me3Si)3Si
(Me3Si)3Si
[(Me3Si)3Si]2Zn/Et2Zn
trans-silylzincation
[Zn]
CuCN•2LiCl
E–X
E
Z/E up to > 98:2
44–86% yield
a Institut für Chemie, Technische Universität Berlin, Strasse des
17. Juni 115, 10623 Berlin, Germany
martin.oestreich@tu-berlin.de
b Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 8232,
Institut Parisien de Chimie Moléculaire (IPCM), Case 229,
4 place Jussieu, 75005 Paris, France
alejandro.perez_luna@upmc.fr
Received: 31.10.2016
Accepted after revision: 04.11.2016
Published online: 17.11.2016
Also, in a conceptually related approach, the domino silyl-
metalation–allylation of ynoates,8a as well as the silylmeta-
lation–arylation of internal alkynes,8b was reported using a
dual Cu(I)/Pd(0) catalytic system and Si–B interelement
compounds as the silicon source.8
DOI: 10.1055/s-0036-1588106; Art ID: st-2016-z0762-fa
Abstract Sulfur-, oxygen-, and phosphorus-substituted terminal
alkynes undergo regio- and stereoselective silylzincation by reaction
with (Me2PhSi)2Zn, (Me3Si)3SiH/Et2Zn or [(Me3Si)3Si]2Zn/Et2Zn. The ad-
dition across the C–C triple bond always occurs with β-regioselectivity
but the stereoselectivity is tunable: (Me2PhSi)2Zn for cis and
(Me3Si)3SiH/Et2Zn or [(Me3Si)3Si]2Zn/Et2Zn for trans. The procedures
making use of the zinc reagents (Me2PhSi)2Zn and [(Me3Si)3Si]2Zn can
be combined in one-pot with a subsequent stereoretentive copper(I)-
mediated electrophilic substitution of the intermediate C(sp2)–Zn
bond. These stereodivergent protocols offer a regio- and stereoselec-
tive access to trisubstituted vinylsilanes decorated with sulfur-, oxygen-,
and phosphorus substituents with either double-bond geometry.
Similarly, silylmetalation–electrophilic substitution se-
quences involving α-heteroatom-substituted alkynes offer
a direct access to heteroatom-substituted vinylsilanes.
However, while the related carbometalation–electrophilic
substitution chemistry of this substrate class is well estab-
lished,9 that interesting prospect did not receive much at-
tention in the past. Only scant reports on the synthesis of
vinylsilanes with nitrogen or phosphorus substituents
through silylcupration of internal ynamines,10 ynamides,11
and alkynylphosphine oxides12 were disclosed. Hence, im-
plementation of such an approach currently relies on the
palladium-catalyzed addition of silylstannanes13–15 or silyl-
boronic esters.16,17 These processes are all cis-selective, and
subsequent transformation of the C(sp2)–Sn or the C(sp2)–B
bonds requires an additional synthetic step orthogonal to
the existing C(sp2)–Si bond.
In this context, we recently reported the regio- and ste-
reoselective silylzincation of terminal ynamides. Reaction
with the bis(organosilyl)zinc reagent (Me2PhSi)2Zn (Method
A)18 occurs with β regioselectivity and cis stereoselectivity
(Scheme 1, left), whereas reaction with a combination of ei-
ther (Me3Si)3SiH (Method B)19 or [(Me3Si)3Si]2Zn (Method
C)18 and Et2Zn takes places with the same β regioselectivity
but with opposite trans stereoselectivity (Scheme 1, right).
The different stereochemical outcomes of these procedures
is likely the result of completely different mechanisms:
Method A relies on the polar transfer of a silicon anion and
proceeds through a conventional 1,2-addition mecha-
Key words copper, silylmetalation, silylzinc reagents, vinylsilanes, zinc
The constant demand for silicon-containing building
blocks also perpetuates interest in the regio- and stereo-
controlled preparation of vinylsilanes.1 For this, the silyl-
metalation of alkynes, i.e., the addition of a silicon–metal
bond across a C–C triple bond, is particularly useful because
it establishes a C(sp2)–Si bond and a C(sp2)–metal bond in a
single synthetic operation. The newly formed reactive bond
allows for further functionalization by reaction with suit-
able electrophiles. A range of protocols has been developed
for this sequential silylmetalation–electrophilic substitu-
tion of aryl- and alkyl-substituted alkynes. These include
reactions involving direct silylcupration,2 Pt(II)- or Cu(I)-
catalyzed silylmagnesiation,3 as well as direct4 and Cu(I)-
catalyzed5 silylzincation. Furthermore, silylmetalation fol-
lowed by reductive elimination with C–Si coupling was re-
ported with manganese-6 and zinc-based7 silicon reagents.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

B
C. Fopp et al.
Feature
Synthesis
Biographical Sketches
Carolin Fopp was born in 1989 in Es-
Ulrich Reißig (2011) and her mas-
ter’s degree with Martin Oestreich at
the Technische Universität Berlin
(2013). Staying in the same labora-
tory, she is currently pursuing gradu-
ate research. As part of her project,
she spent three months in the group
of Alejandro Perez-Luna at Université
Pierre et Marie Curie in France.
slingen, Germany. She was trained in
chemistry at the Freie Universität
Berlin (2008–2013). She obtained
her bachelor’s degree with Hans-
Kévin Isaac obtained his M.Sc. de-
gree with Alejandro Perez-Luna (Uni-
versité Pierre et Marie Curie, Paris,
2011). He then went to the Institut
de Chimie des Substances Naturelles
(Gif-sur-Yvette, France) and received
his Ph.D. degree with Jean-François
Betzer and Dr. Angela Marinetti from
Université Paris 11 (Orsay, 2014). In
2015, he joined Université Pierre et
Marie Curie as a postdoctoral associ-
ate working with Alejandro Perez-
Luna.
Elise Romain was born in Les Lilas,
France, in 1990. She studied chemis-
try at the Ecole Nationale Supérieure
de Chimie de Rennes (Rennes, 2009–
2012) where she received an engi-
neer diploma. She obtained her
M.Sc. degree with Bertrand Carboni
(Rennes, 2012), and then joined
Fabrice Chemla’s group at Université
Pierre et Marie Curie where she ob-
tained her Ph.D. under the guidance
of Alejandro Perez-Luna (2015). In
2016, she joined Huntsman Corpo-
ration (Duisburg, Germany) where
she is currently working in the field
of pigments and additives.
Fabrice Chemla was born in 1963 in
Paris, France. He is a full Professor of
Chemistry at Université Pierre et
Marie Curie. After receiving his diplo-
ma degree from the Ecole
Supérieure de Physique et Chimie In-
dustrielles de Paris, he received his
doctoral degree with Marc Julia (ENS
Paris, 1992). After a one-year post-
doctoral stay with Reinhard W.
Hoffmann (Marburg, Germany), he
took an Assistant Professor position
in Jean Normant’s group at Universi-
té Pierre et Marie Curie. He was ap-
pointed as
a full Professor in the
same university in 2001 and has
been Vice-Rector since 2012.
Franck Ferreira was born in 1968
near Paris, France. He is a full Profes-
sor of Chemistry at Université Pierre
et Marie Curie. He received his doc-
toral degree with Jean-Pierre Genêt
(Paris, 1996). After a one-year post-
doctoral
stay
with
Jean-Yves
(1998–2015). He then joined Fabrice
Chemla’s group (2002) and was ap-
pointed full Professor of Chemistry
at Université Pierre et Marie Curie in
2015.
Lallemand (Ecole Polytechnique,
France, 1997), he took up a perma-
nent position as an Assistant Profes-
sor in Jean Normant’s group at
Université Pierre et Marie Curie
Olivier Jackowski was born in 1980
in Ris–Orangis, France. He began his
research career working in the field
of carbohydrate chemistry: he re-
ceived his doctoral degree with Yves
Chapleur (Nancy, 2008) and then
stayed as a postdoctoral researcher
with Jean-Luc Décout (Grenoble,
2009). He then shifted to the area of
organometallic chemistry and joined
successively the groups of Alexandre
Alexakis (Geneva), Laurent Micouin
(Paris) and Virginie Vidal (Paris) as a
postdoctoral associate. In 2012, he
was appointed Assistant Professor at
Université Pierre et Marie Curie in
Fabrice Chemla’s group.
Martin Oestreich was born in 1971
in Pforzheim, Germany. He is Profes-
sor of Organic Chemistry at the
Technische Universität Berlin. He re-
ceived his diploma degree with Paul
Knochel (Marburg, 1996) and his
doctoral degree with Dieter Hoppe
(Münster, 1999). After a two-year
postdoctoral stint with Larry E.
Overman (Irvine, 1999–2001), he
completed his habilitation with
Reinhard Brückner (Freiburg, 2001–
2005) and was appointed as Profes-
sor of Organic Chemistry at the
Westfälische Wilhelms-Universität
Münster (2006–2011). He also held
visiting positions at Cardiff Universi-
ty in Wales (2005) and at The Austra-
lian National University in Canberra
(2010).
Alejandro Perez-Luna was born in
1977 in London, UK. He studied
chemistry at the Ecole Nationale
Supérieure de Chimie de Paris (Paris,
1997–2000) and received an engi-
neer diploma. He obtained his M.Sc.
degree with Franck Lebideau and Elie
Stephan (Paris, 2000), and then
a CNRS researcher position to work
in Fabrice Chemla’s group at Univer-
sité Pierre et Marie Curie. He re-
ceived his habilitation degree from
this university in 2012 and was pro-
moted to CNRS Research Director
(DR 2) in 2015.
joined
Henri-Philippe
Husson’s
group at Université Paris Descartes
where he obtained a Ph.D. degree
with Laurent Micouin (Paris, 2003).
After a postdoctoral stay with Peter
Kündig (Geneva, 2004), he obtained
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

C
C. Fopp et al.
Feature
Synthesis
nism,20 and Methods B and C proceed through an unusual
radical-chain mechanism involving the transfer of a silicon-
centered radical.21 As part of this work, we demonstrated
that the C(sp2)–Zn bond formed in these processes engages
in a subsequent stereoretentive bond-forming reaction by
one-pot Cu(I)-mediated electrophilic substitution. On the
whole, these protocols offer a stereoselective access to both
E- and Z-trisubstituted vinylsilanes having a nitrogen sub-
stituent β to the silicon group.
Method B, i.e., the reaction with (Me3Si)3SiH in n-hex-
ane at 0 °C in the presence of Et2Zn, was then applied to the
same set of substrates. The reaction outcome was now de-
pendent on the sulfur group. Arylsulfide 1a provided the
corresponding Z-vinylsilane in high yield and with excellent
β regioselectivity and trans stereoselectivity (Table 1, entry
2). The same regio- and stereoselectivity was observed for
arylsulfoxide 1b but, in this case, the silylzincation process
was hampered by competing carbozincation (Table 1, entry
5). Nevertheless, this side reaction could be limited either
by increasing the amount of (Me3Si)3SiH (Table 1, entry 6)
or by lowering the reaction temperature to –30 °C (Table 1,
entry 7). Adduct 3b was thus obtained in 50–57% isolated
yield as a single Z-stereoisomer. By contrast, Method B
could not be applied satisfactorily to arylsulfone 1c be-
cause, even though the regioselectivity was excellent and
the yield good, lack of stereocontrol was observed (Table 1,
entry 10).
R1
polar pathway
radical pathway
α
N
R2
β
(Me3Si)3SiH
Et2Zn
O
Method B
or
[(Me3Si)3Si]2Zn
Et2Zn
(Me2PhSi)2Zn
Method A
Method C
R2
R2
R1
R1
N
O
N
O
Table 1 Silylzincation of α-Heteroatom-Substituted Acetylenes Using
Methods A–C
[Zn]
(Me3Si)3Si
[Zn]
Me2PhSi
β-selective
β-selective
trans-selective
Method
A, B or C
Het
cis-selective
α
Het
Het
β
+
CuCN•2LiCl
E–X
CuCN•2LiCl
E–X
H
Si
then
NH4Cl/NH3
H
Si
(E)
(Z)
R2
R2
1a–h
2a–h : Si = SiMe2Ph
3a–h : Si = Si(SiMe3)3
R1
R1
N
O
N
O
Method A:
Method B:
Method C:
[(Me3Si)3Si]2Zn
(1.1 equiv)
Et2Zn
(1.1 equiv)
E
(Me3Si)3Si
E
(Me3Si)3SiH
(1.3 equiv)
Et2Zn
(3.0 equiv)
n-hexane, 0 °C
(Me2PhSi)2Zn
(1.6 equiv)
Et2O, 0 °C
Me2PhSi
E-vinylsilanes
Z-vinylsilanes
Scheme 1 Stereodivergent syntheses of E- and Z-trisubstituted vinyl-
silanes by sequential silylzincation–Cu(I)-mediated electrophilic substi-
tution of terminal ynamides
n-hexane, –30 °C
Entry Substrate
Method
Product E/Za
Yield (%)b
1c
2
A
B
C
2a
3a
3a
>98:2
<2:98
<2:98
74
85
84
S
In an earlier investigation,18 we established that Meth-
ods A and C were also suitable for the silylzincation of other
α-heteroatom-substituted alkynes. We have now found
that such is also the case for Method B. We provide here a
comparative study of the silylzincation of terminal sulfur-,
oxygen-, and phosphorus-substituted alkynes using these
three protocols and we demonstrate their potential for the
preparation of stereodefined trisubstituted vinylsilanes
through subsequent Cu(I)-mediated electrophilic substitu-
tion.
3c
1a
1b
4c
5
A
2b
3b
3b
3b
3b
>98:2
<2:98
<2:98
<2:98
5:95
61
O
S
B
39d
50f
57f
84
6
Be
Bg
C
7
8c
The study commenced with the silylzincation of acety-
lenes substituted with sulfur in different oxidation states.
Implementation of Method A, i.e., the reaction with
(Me2PhSi)2Zn in Et2O at 0 °C, was smooth. Regardless of the
nature of the sulfur group (Table 1, entries 1, 4, and 9), si-
lylzincation proceeded with excellent β regioselectivity and
cis stereoselectivity. After hydrolysis, E-configured 1,2-
disubstituted vinylsilanes with arylsulfide (2a), arylsulfox-
ide (2b), and arylsulfone (2c) groups were obtained in 45–
74% yield.
9c
A
B
2c
3c
>98:2
50:50
45
60
O2
S
10
11c
C
3c
66:34
67
1c
Br
12
C
3d
3:97
62h
S
1d
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

D
C. Fopp et al.
Feature
Synthesis
Table 1 (continued)
Entry Substrate
silylzincation and afforded E-vinylsilane 2g as a single ste-
reoisomer in 75% yield (Table 1, entry 18). At –78 °C, an
even better 82% yield was obtained (Table 1, entry 19).
The silylzincation of carbamate 1f following Method B
occurred with excellent regio- and stereoselectivity, albeit
sluggishly (Table 1, entry 16). Conversion was incomplete
(30% of starting material was recovered), and adduct 3f was
formed in a modest 46% yield. In turn, Method C proved su-
perior since both 1f and 1g underwent β-regioselective si-
lylzincation with exquisite trans stereoselectivity and pro-
vided Z-1,2-disubstituted vinylsilanes 3f and 3g in 75% iso-
lated yields (Table 1, entries 17 and 20).
Method
C
Product E/Za
Yield (%)b
51
Se
13
3e
<2:98
1e
14
A
Ai
B
2f
2f
3f
3f
72:28
86:14
<2:98
<2:98
75
81
46j
75
O
N(iPr)2
15c
16
O
1f
17c
C
18c
19
A
2g
2g
>98:2
>98:2
75
82
The last substrate class of our survey was α-phospho-
nyl-substituted alkynes. The silylcupration of internal
alkynes with a phosphonate moiety on the alkyne terminus
was reported to proceed with β regioselectivity and with cis
stereoselectivity.12 However, no example involving a termi-
nal alkyne was disclosed. We found that α-phosphonate-
substituted acetylene 1h reacted readily with β regioselec-
tivity following Method A and provided E-configured vinyl-
silane 2h in an excellent 89% yield (Table 1, entry 21). Im-
plementation of Methods B and C to access the correspond-
ing Z-configured isomer was less successful (Table 1, entries
22 and 23). Following Method B, not only was the reaction
sluggish as in the case of carbamate 1f, but also poorly ste-
reoselective. Method C was superior to Method B, and 1h
underwent the silylzincation in 68% yield to give vinylsilane
3h with a Z/E = 83:17 ratio. The stereoselectivity was not
perfect but separation of the diastereoisomers by flash col-
umn chromatography was straightforward, and 3h could
nonetheless be isolated as a single Z-isomer in 55% yield.
After having established that Methods A–C offer a ste-
reodivergent access to 1,2-disubstituted vinylsilanes with
an array of heteroatom substituents β to the silicon atom,
we investigated the possibility to use this chemistry to ac-
cess 1,2,2-trisubstituted vinylsilanes stereoselectively. To
this end, we carried out deuterium-labeling experiments
(Table 2): the reaction mixtures of the most efficient proto-
cols were quenched with ND4Cl/D2O. In most cases, the ex-
pected labeled vinylsilanes [2H]-2 or [2H]-3 were obtained
with excellent deuteration grades (>89%) and deuterium in-
corporation with perfect stereochemical fidelity. However,
these experiments were not successful for α-oxygen-sub-
stituted substrates 1f and 1g with Method A because com-
pounds 2f and 2g proved unstable in non-buffered aqueous
media (Table 2, entries 11 and 13). Product [2H]-2f was iso-
lated in low yield as a mixture of Z and E diastereomers,
whereas the only product detected when starting from 1g
was 4-methoxyphenol (even if only D2O was used).
O
O
Ai
OMe
20
C
3g
<2:98
75
1g
1h
21c
22
A
B
C
2h
3h
3h
>98:2
31:69
17:83
89
52k
68
P(OEt)2
23c
a Determined by 1H NMR spectroscopy prior to purification.
b Combined yield of isolated diastereomers unless otherwise noted.
c See ref 18.
d 23% of carbozincation observed.
e (Me3Si)3SiH (4 equiv).
f 17% of carbozincation observed.
g Reaction at –30 °C with Et2Zn (5 equiv).
h Reaction time = 22 h; 18% of dibenzothiophene formed.
i Reaction at –78 °C.
j Yield determined by 1H NMR spectroscopy using butadiene sulfone as an
internal standard; 30% of 1f detected prior to purification.
k Reaction time = 18 h; 30% of 1h detected prior to purification.
Finally, Method C, i.e. the reaction of [(Me3Si)3Si]2Zn in
n-hexane at –30 °C in the presence of Et2Zn, was evaluated.
Excellent regiocontrol and good yields were observed for all
the substrates, but yet again the sulfur group on the alkyne
terminus had an impact on the stereochemical outcome.
Arylsulfides and arylsulfoxides afforded superb trans ste-
reoselectivity (dr > 95:5) (Table 1, entries 3 and 8) but not
arylsulfones (Table 1, entry 11). Arylsulfide 1d with a 2′-
bromo-1,1′-biphenyl-2-yl moiety on the sulfur atom22 also
reacted smoothly under Method C (Table 1, entry 12). We
note here that α-phenylselenyl-substituted acetylene 1e, as
for arylthio-substituted substrates, underwent trans silyl-
zincation using Method C with excellent regio- and stereo-
selectivity (Table 1, entry 13).
We then focused on the silylzincation of oxygen-substi-
tuted acetylenes. The silylzincation of ynol carbamate 1f by
reaction with (Me2PhSi)2Zn according to Method A proceed-
ed in 75% yield and with perfect β regioselectivity but low
diastereoselectivity (E/Z = 72:28) (Table 1, entry 14). Per-
forming the reaction at –78 °C improved the diastereoselec-
tivity (E/Z = 86:14), but full stereocontrol was still not
achieved (Table 1, entry 15). Conversely, even at 0 °C, phe-
noxy-substituted acetylene 1g underwent β-regioselective
With evidence that the C(sp2)–Zn bond created during
the silylzincation event remains available at the end of the
reaction, subsequent stereoretentive functionalization by
Cu(I)-mediated electrophilic substitution was considered.
For this, we used the THF-soluble salt CuCN·2LiCl as we had
previously in the case of ynamides.18,19
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

E
C. Fopp et al.
Feature
Synthesis
Table 2 Deuterium-Labeling Experiments
S(On)Ar
α
(Me2PhSi)2Zn (1.6 equiv)
S(On)Ar
β
Het
then
Het
Me2PhSi
ND4Cl
CuCN⋅2LiCl (3.1 equiv)
allyl bromide (7.9 equiv)
Et2O, 0 °C
1a–c
6–8
β/α > 98:2 and
E/Z > 98:2
[Zn]
D
Method A
Me2PhSi
Me2PhSi
[2H]-2a–h
α
4a–h
Het
β
1a–h
O
S
S
•
O2S
Method
B or C
Het
Het
ND4Cl
•
•
•
(Me3Si)3Si
5a–h
(Me3Si)3Si
[2H]-3a–h
•
•
[Zn]
D
Me2PhSi
Me2PhSi
Me2PhSi
8: 59%
6: 60% (at –78 °C)
7: 93% (at –78 °C)
Scheme 2 Sequential silylzincation–Cu(I)-mediated allylation of sulfur-
substituted terminal alkynes following Method A
Entry
Substrate Method Product
E/Z
Yield (%)a
64
1
1a
1a
1a
1b
1b
1b
1c
1c
1d
1e
1f
A
B
C
A
B
C
A
B
C
C
A
C
A
C
A
C
[2H]-2a
[2H]-3a
[2H]-3a
[2H]-2b
[2H]-3b
[2H]-3b
[2H]-2c
[2H]-3c
[2H]-3d
[2H]-3e
[2H]-2f
[2H]-3f
[2H]-2g
[2H]-3g
[2H]-2h
[2H]-3h
>98(94%b):2
<2:98(90%b)
<2:98(92%b)
>98(92%b):2
<2:98(89%b)
5:95(89%b)
c
2
–
der these conditions (Scheme 3). For 1a, allylated 9 was
formed as a single Z-isomer in 48% yield. However, the
transformation was not synthetically useful as compound 9
could not be separated from protodemetalated 3a that was
formed in 19% yield. For 1c, even though the allylation of in-
termediate 5c was more efficient (less than 5% of non-al-
lylated 3c detected), the yield of the desired compound 10
was only modest (48%). Furthermore, since allylation oc-
curred with retention of configuration, and the silylzinca-
tion of 3c was not stereoselective, 10 was produced as a
Z/E = 50:50 mixture of isomers.
3
63
39
4
c
5
–
6
56
47
63
42
7
>98(98%d):2
40(88%b):60(96%b)
<2:98(>95%b)
<2:98(91%b)
65(97%d):35(nce)
<2:98(94%b)
–
8
9
c
10
11
12
13
14
15
16
–
46
72
1f
Et2Zn (3.0 equiv)
(Me3Si)3SiH (1.3 equiv)
S(On)Ar
α
S(On)Ar
f
β
1g
1g
1h
1h
–
(Me3Si)3Si
then
<2:98(>95%b)
>98(97%b):2
18(90%b):82(94%b)
74
46
CuCN⋅2LiCl (3.0 equiv)
allyl bromide (6.9 equiv)
n-hexane, 0 °C
1a and 1c
9 and 10
β/α > 98:2
c
–
a Combined yield of isolated diastereomers unless otherwise noted.
b Deuteration grade estimated by 1H NMR spectroscopy.
c Deuteration-grade analysis without purification.
d Deuteration grade measured by mass spectrometry.
e Not calculated.
S
O2S
•
•
(Me3Si)3Si
(Me3Si)3Si
•
•
9: 48% (Z/E > 98:2)
(+ 19% 3a)
10: 48% (Z/E = 50:50)
f Only 4-methoxyphenol isolated.
Scheme 3 Sequential silylzincation–Cu(I)-mediated allylation of sulfur-
substituted terminal alkynes following Method B
Allylation of the Z-configured β-silyl α-sulfur vinylzinc
intermediates 4a–c (from 1a–c by Method A) was success-
fully achieved using allyl bromide as the electrophile
(Scheme 2). The E-configured trisubstituted vinylsilanes
with arylsulfide (6), arylsulfoxide (7), and arylsulfone (8)
substituents β to the silicon atom were prepared in syn-
thetically useful 59–93% yields. Note however that, to ob-
tain 6 and 7 in decent yields, the allylation had to be per-
formed at –78 °C. Hence, it was more convenient to also
carry out the silylzincation step at –78 °C. Other electro-
philes such as n-Bu3SnCl failed to react both at 0 °C and
–78 °C, only leading to unidentified degradation products.
Electrophilic substitution of E-configured β-silyl α-sul-
fur vinylzinc intermediates 5a–d was then studied to access
the corresponding Z-configured trisubstituted vinylsilanes
(Schemes 3 and 4). The good yields obtained for the silyl-
zincation of arylsulfide 1a and arylsulfone 1c with Method
B prompted us to examine sequential in situ allylation un-
As a consequence of these initial results, we decided to
focus on the procedures involving Method C (Scheme 4).
Under these conditions, α-phenylthio vinylzinc 5a (from
1a) reacted cleanly with allyl bromide and n-Bu3SnCl in the
presence of Cu(I), and the expected vinylsilanes 9 (not
shown) and 11 were formed as single diastereomers. Nei-
ther 9 nor 11 could be isolated pure due to their low polari-
ty that prevented separation from the silicon-containing
side products by flash column chromatography on silica gel.
For 11, the reaction was nevertheless useful because, on ox-
idation of the crude mixture, sulfone 12 was obtained and,
being more polar, could be isolated in 69% yield (two steps
from 1a). Hence, this sequence offers an access to β-arylsul-
fone-substituted Z-vinylsilanes and overcomes, in part, the
limitation associated with the lack of stereoselectivity of
the trans-silylzincation of α-arylsulfone acetylenes. Purifi-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

F
C. Fopp et al.
Feature
Synthesis
cation was not a problem in the case of allylated vinylsilane
13 having a 2′-bromo-1,1′-biphenyl-2-yl substituent on the
sulfur atom, and it was prepared from intermediate 5d as a
single Z-isomer in 44% yield.
degradation was observed starting from aryloxy-substitut-
ed alkyne 1g, and 19 and 4-methoxyphenol were the only
identified side products.
N(i-Pr)2
Domino trans-silylzincation–Cu(I)-mediated electro-
philic substitution employing Method C was most efficient
in the case of arylsulfoxide 1b. As illustrated with the
preparation of trisubstituted Z-vinylsilanes 14–17 in 59–
75% yield, organozinc intermediate 5b reacted readily not
only with allyl bromides in C–C bond-forming reactions,
but also with non-carbon electrophiles such as n-Bu3SnCl
and PhSeCl (Scheme 4).
(Me2PhSi)2Zn
(1.6 equiv)
α
O
•
O
[O]
β
+
then
•
Si
CuCN⋅2LiCl
(3.1 equiv)
allyl bromide
(8.0 equiv)
Et2O, –78 °C
1f
Si
18: 42% (E/Z > 98:2)
Si = SiMe2Ph
19: 29%
Scheme 5 Sequential silylzincation–Cu(I)-mediated allylation of ynol
carbamate 1f following Method A
[(Me3Si)3Si]2Zn (1.1 equiv)
S(On)Ar
E
α
Et2Zn (1.1 equiv)
S(On)Ar
β
(Me3Si)3Si
Conversely, electrophilic substitution following zinc-to-
copper transmetalation was possible for both intermediates
5f and 5g, prepared by Method C (Scheme 6). For α-carba-
moyl vinylzinc 5f, allylation under the previously optimized
conditions (–30 °C to r.t.) was sluggish and yielded a mix-
ture of allylated 20 and protodemetalated 3f in a 25:75 ra-
tio and 62% overall yield (not shown). A slight improvement
was achieved in THF at reflux since 20 was formed predom-
inantly in 34% yield; yet, it could not be separated from 3f
formed in 14% yield. By contrast, trapping of α-aryloxy vi-
nylzinc 5g was much easier and could be performed even at
low temperature with both allyl bromide and n-Bu3SnCl.
Thus, trisubstituted Z-vinylsilanes 21 and 22 having oxy-
gen-substituents were readily prepared as single isomers in
51–57% yield.
then
CuCN⋅2LiCl (2.2 equiv)
E–X (5.5 equiv)
n-hexane, –30 °C to r.t.
1a, 1b and 1d
11 and 13–17
β/α > 98:2
Br
OnS
•
S
(Me3Si)3Si
SnBu3
•
•
(Me3Si)3Si
(X = Cl)
•
(X = Br)
11 (n = 0)
12 (n = 2): 69% (E/Z > 98:2)
m-CPBA
13: 44% (Z/E > 98:2)
O
S
O
S
•
(Me3Si)3Si
•
•
(Me3Si)3Si
•
CO2t-Bu
(X = Br)
(X = Br)
14: 68% (Z/E > 98:2)
15: 75% (Z/E > 98:2)
[(Me3Si)3Si]2Zn (1.1 equiv)
Et2Zn (1.1 equiv)
[O]
α
[O]
(Me3Si)3Si
β
E
then
O
S
O
S
CuCN⋅2LiCl (2.2 equiv)
E–X (5.5 equiv)
n-hexane, –30 °C
1f and 1g
20–22
β/α > 98:2
•
•
(Me3Si)3Si
(Me3Si)3Si
SnBu3
SePh
•
•
(X = Cl)
N(i-Pr)2
(X = Cl)
16: 59% (E/Z > 98:2)
17: 66% (E/Z > 98:2)
O
•
O
Scheme 4 Sequential silylzincation–Cu(I)-mediated electrophilic sub-
stitution of sulfur-substituted terminal alkynes following Method C
•
(Me3Si)3Si
(X = Br)
20: 34% (Z/E > 98:2) (at 60 °C) (+ 14% 3f)
Our next efforts were then driven toward the prepara-
tion of trisubstituted vinylsilanes with oxygen substituents
β to the silicon atom. Application of Method A in the se-
quential cis-silylzincation–Cu(I)-mediated allylation to
alkynes 1f and 1g was unsuccessful. Silylzincation at –78 °C
of ynol carbamate 1f followed by the addition of CuCN·2LiCl
and allyl bromide at the same temperature did allow us to
isolate 18 as a single E-isomer in 42% yield (Scheme 5);23
compound 1924 was also obtained in 29% yield. However,
the outcome of this reaction was highly dependent on the
temperature as well as the order and rate of addition of the
Cu(I) salt and the electrophile. Despite extensive experi-
mentation, later attempts to reproduce this result led to
degradation among which only 19 was identified. Similarly,
OMe
OMe
O
•
O
•
•
(Me3Si)3Si
(Me3Si)3Si
SnBu3
(X = Cl)
22: 51% (E/Z > 98:2)
•
(X = Br)
21: 57% (Z/E > 98:2)
Scheme 6 Sequential silylzincation–Cu(I)-mediated electrophilic sub-
stitution of oxygen-substituted terminal alkynes following Method C
It is interesting to note that for the oxygen-substituted
substrates, similarly to the sulfur-substituted congeners,
there was also a striking difference of stability between Z-
configured (obtained from 4f and 4g) and E-configured vi-
nylcopper intermediates (obtained from 5f and 5g). Indeed,
failure of the Cu(I)-mediated electrophilic substitution of E-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

G
C. Fopp et al.
Feature
Synthesis
configured 5f and 5g led to the recovery of the protode-
metalated product, i.e., 3f from 5f. In turn, for Z-configured
4f and 4g, mostly degradation was observed. The formation
of 19 from 4f and 4g was helpful as it led us to rationalize
this stability difference as a consequence of retro cis-silyl-
cupration, a process that would only occur from the Z rela-
tionship of the copper and silicon groups.25 Silylcupration
of 1f and 1g could be reversible, and isomerization of β into
α regioisomers could occur (β-24 to α-24) (Scheme 7).26 Re-
gioisomer α-24 would undergo trans β-elimination9,27 to af-
ford alkyne 23. In the presence of allyl bromide and base,
alkyne 23 would then give 19.
verted into desired 27; a mixture of 27 and protodemetalat-
ed 3h in a 56:44 ratio was obtained. The stereochemical
outcome was also completely different than for the allyla-
tion reaction. β-Stannyl vinylsilane 27 was formed as a sin-
gle E-isomer, and protodemetalated 3h was recovered as a
mixture of isomers in a Z/E = 75:25 ratio (slightly different
from the Z/E = 83:17 ratio of vinylzinc 5h). These results are
consistent with a rationale where the E-isomer of 5h was
converted into (E)-27 stereoselectively (yet not totally),
while the Z-isomer of 5h remained intact to afford (E)-3h
after aqueous work-up. This behavior, in line with other
previous observations, indicates that there is a significant
difference in reactivity toward electrophilic substitution
between Z- and E-configured β-silyl vinylzinc reagents. This
difference can be ascribed to the steric hindrance intro-
duced by the silyl group when the metal and the silicon
group are on the same side of the double bond. This is cer-
tainly one of the main reasons that explain the difficulties
encountered in the functionalization of several adducts ob-
tained by cis-selective Method A.
OR
SiMe2Ph
19
Zn
Me2PhSi
4f and 4g
CuCN•2LiCl
OR
Cu
23
– CuOR
α
OR
β
OR
1f and 1g
SiMe2Ph
+
[(Me3Si)3Si]2Zn (1.1 equiv)
Me2PhSi
β-24
Cu
O
O
Me2PhSi Cu
Et2Zn (1.1 equiv)
P(OEt)2
E
α
α-24
P(OEt)2
β
then
(Me3Si)3Si
26–27
CuCN⋅2LiCl (2.0–3.0 equiv)
E–X (5.0–7.0 equiv)
n-hexane, –30 °C
Scheme 7 Degradation pathway of E-configured α-oxygen-substituted
vinylcopper reagents; ligands on copper and zinc are not shown
1h
β/α > 98:2
O
O
P(OEt)2
•
•
P(OEt)2
Finally, we considered the preparation of trisubstituted
vinylsilanes with a phosphonate moiety β to the silicon at-
om. The Z-configured α-phosphonyl vinylzinc 4h (from 1h
by Method A) underwent the Cu(I)-mediated allylation
readily, and E-configured vinylsilane 25 was obtained in
85% yield as a single isomer (Scheme 8). Electrophilic sub-
stitution of 4h was again narrow in scope since other elec-
trophiles such as n-Bu3SnCl failed to react.
•
(Me3Si)3Si
(Me3Si)3Si
SnBu3
•
(X = Cl)
(X = Br)
27: 50% (E/Z > 98:2)
[+ 40% 3h (Z/E = 75:25)]
26: 86% (Z/E = 84:16)
Scheme 9 Sequential silylzincation–Cu(I)-mediated electrophilic sub-
stitution of alkynyl phosphonate 1h following Method C
In conclusion, the highly regio- and stereoselective si-
lylzincation of sulfur-, oxygen-, and phosphorus-substitut-
ed terminal alkynes can be achieved by reaction with
(Me2PhSi)2Zn, (Me3Si)3SiH/Et2Zn or [(Me3Si)3Si]2Zn/Et2Zn.
The three protocols yield exclusively β-isomers but the ste-
reoselectivity depends on the reagent used: addition of
(Me2PhSi)2Zn across the C–C triple bond occurs cis-selec-
tively whereas trans stereoselectivity is generally observed
with (Me3Si)3SiH/Et2Zn and [(Me3Si)3Si]2Zn/Et2Zn.
O
O
P(OEt)2
α
(Me2PhSi)2Zn (1.6 equiv)
P(OEt)2
•
β
•
then
Me2PhSi
CuCN⋅2LiCl (3.1 equiv)
allyl bromide (8.0 equiv)
Et2O, 0 °C
1h
25: 85% (E/Z > 98:2)
Scheme 8 Sequential silylzincation–Cu(I)-mediated allylation of
alkynyl phosphonate 1h following Method A
As for the previous substrate classes, E-configured vi-
nylzinc 5h (from 1h as a Z/E = 83:17 mixture by Method C)
reacted with both allyl bromide and n-Bu3SnCl in the pres-
ence of CuCN·2LiCl at –30 °C (Scheme 9). Allylation fur-
nished trisubstituted 26 in an excellent 86% yield as a mix-
ture of isomers in the same ratio as the intermediate vinyl-
zinc; pure (Z)-26 was obtained by purification by flash
column chromatography. Importantly, the Z configuration
was confirmed by X-ray crystallographic analysis,28 also
confirming that the Cu(I)-mediated electrophilic substitu-
tion occurred with perfect retention of the configuration.
Stannylation was less clean, and 5h could not be fully con-
The protocols involving the zinc reagents (Me2PhSi)2Zn
and [(Me3Si)3Si]2Zn are the most efficient and can be com-
bined in one-pot with a subsequent Cu(I)-mediated electro-
philic substitution that occurs with retention of configura-
tion. These sequences offer a regio- and stereoselective ac-
cess to trisubstituted vinylsilanes decorated with sulfur-,
oxygen-, and phosphorus substituents β to the silicon atom
with either double-bond geometry. An unforeseen feature
of this chemistry is that functionalization of the C(sp2)–Zn
bond of the E-configured vinylzinc intermediates is much
broader in scope than that of those with Z-configuration. In
the latter case, electrophilic substitution is likely hampered
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

H
C. Fopp et al.
Feature
Synthesis
by the steric congestion introduced by the vicinal silyl
group, and yields are diminished by decomposition of the
intermediate Z-vinylcopper reagent through retro cis-silyl-
cupration.
ture was stirred at this temperature for 3 h. CuCN·2LiCl (0.75 mL, 1.0
M in THF, 0.75 mmol, 3.0 equiv) was then added at the same tempera-
ture, followed by allyl bromide (0.15 mL, 1.73 mmol, 6.9 equiv). The
reaction mixture was maintained at r.t. for 16 h, diluted with CH2Cl2
(15 mL), and quenched with NH4Cl/NH3 (2:1) (2 mL). The layers were
separated, and the aqueous layer was extracted with CH2Cl2 (2 × 15
mL). The combined organic phases were washed with brine (2 × 5
mL), dried over Na2SO4, filtered, and concentrated under reduced
pressure to afford the crude compound.
Experiments involving organometallic compounds were carried out
in dried glassware under a positive pressure of dry argon or nitrogen
using Schlenk techniques. THF was dried over Na or K/benzophenone
and distilled prior to use. Et2O was distilled to remove stabilizers and
dried with a Solvent Purification System or dried over K/benzophe-
none and distilled prior to use. n-Hexane (AnalaR NORMAPUR – VWR
or dried over K/benzophenone followed by distillation), Et2Zn (Sigma-
Aldrich), tris(trimethylsilyl)silane (Alfa Aesar or Sigma-Aldrich),
chloro(dimethyl)phenylsilane (Sigma-Aldrich or ABCR), and all other
reagents were of commercial quality and were used without purifica-
tion. Flash column chromatography was performed using the indicat-
ed solvents on Merck silica gel 60 (15–40 μm or 40–63 μm particle
size) or on an automatic Biotage Flash Purification System (KP-Sil Car-
tridge or ISOLUTE Flash Si II Cartridge). Optical rotations were mea-
sured on a JASCO P-2000 polarimeter or on a Schmidt & Haensch
Polatronic H532 polarimeter with [α]D values reported in 10–1
(°∙cm2∙g–1); concentration c is in g/100 mL. Infrared (IR) spectra were
recorded on an Agilent Technologies Cary 630 FT-IR spectrometer or a
Bruker Tensor 27 ATR diamond spectrophotometer equipped with an
ATR unit and are reported in wavenumbers (cm–1). 1H NMR and 13C
NMR spectra were recorded with Bruker AV 300, AV 400 or AV 500
spectrometers. Chemical shifts are reported in parts per million
(ppm) downfield from tetramethylsilane and are referenced to the re-
sidual solvent resonance as the internal standard (CHCl3: δ = 7.26,
C6H6: δ = 7.16 for 1H NMR; CDCl3: δ = 77.16, C6D6: δ = 128.62 for 13C
NMR). Data are reported as follows: chemical shift, multiplicity (s =
singlet, d = doublet, t = triplet, q = quartet, m = multiplet), coupling
constant(s) (Hz) and integration. High-resolution mass spectra
(HRMS) were obtained from the Analytical Facilities at the Institut für
Chemie, Technische Universität Berlin or at the Institut Parisien de
Chimie Moléculaire (IPCM), UPMC Univ Paris 06. The melting point
was determined with a Wagner&Munz Leica Galen III apparatus and
is not corrected.
Silylzincation via Method C followed by Cu(I)-Mediated Electro-
philic Substitution; General Procedure 3
An n-hexane (2 mL) solution of [(Me3Si)3Si]2Zn30 (0.15 g, 0.28 mmol,
1.1 equiv) was added at –30 °C to the appropriate α-heteroatom-sub-
stituted alkyne 1 (0.25 mmol, 1.0 equiv). Et2Zn (0.28 mL, 1.0 M in
hexanes, 0.28 mmol, 1.1 equiv) was added, and the mixture was
stirred at the same temperature for 3 h. CuCN·2LiCl (0.55 mL, 1.0 M in
THF, 0.55 mmol, 2.2 equiv) was then added at the same temperature,
followed (after 5 min) by the appropriate electrophile (1.4 mmol, 5.5
equiv). The reaction mixture was maintained at r.t. for 16 h, diluted
with CH2Cl2 (5 mL), and quenched with NH4Cl/NH3 (2:1) (3 mL). The
layers were separated, and the aqueous layer was extracted with
CH2Cl2 (2 × 5 mL). The combined organic phases were washed with
brine (3 mL), dried over MgSO4, filtered, and concentrated under re-
duced pressure to afford the crude compound.
The preparation according to Method A and full characterization of
compounds 2a, 2b, 2c, 2f, 2g, and 2h was previously reported.18
The preparation according to Method C and full characterization of
compounds 3a, 3b, 3c, 3f, 3g, and 3h was previously reported.18
(Z)-2-{2-[(2′-Bromo-1,1′-biphenyl-2-yl)thio]vinyl}-1,1,1,3,3,3-
hexamethyl-2-(trimethylsilyl)trisilane (3d)
Prepared according to Method C18 (reaction time of 22 h) from (2′-
bromo-1,1′-biphenyl-2-yl)(ethynyl)sulfide (1d) (72 mg, 0.25 mmol).
Purification of the crude product (Z/E = 97:3) by flash column chro-
matography on silica gel (n-pentane) afforded analytically pure 3d
(83 mg, 62% yield) as a colorless oil.
IR (neat): 2947, 2891, 1517, 1483, 1242, 1028, 1003, 828, 747, 686,
620 cm–1
.
1H NMR (300 MHz, C6D6): δ = 7.48 (dd, J = 8.0, 1.2 Hz, 1 H), 7.35–7.32
(m, 1 H), 7.12 (d, J = 12.0 Hz, 1 H), 7.10–7.03 (m, 3 H), 7.00–6.94 (m, 2
H), 6.82–6.76 (m, 1 H), 5.93 (d, J = 12.0 Hz, 1 H), 0.28 (s, 27 H).
13C NMR (100 MHz, C6D6): δ = 141.8, 141.7, 141.5, 136.6, 133.0, 131.7,
130.4, 129.5, 129.0, 128.6, 127.3, 126.3, 124.5, 124.0, 1.5.
Silylzincation via Method A Followed by Cu(I)-Mediated Allylation;
General Procedure 1
To an Et2O (3 mL) solution of the appropriate α-heteroatom-substitut-
ed alkyne 1 (0.27 mmol, 1.0 equiv) cooled to 0 °C or –78 °C was added
(Me2PhSi)2Zn29 (2.0–3.0 mL, 0.15–0.25 M in Et2O, 1.6 equiv). The re-
sulting mixture was stirred at the same temperature for 1 h. The cool-
ing bath was removed, allyl bromide (0.20 mL, 2.3 mmol) and
CuCN·2LiCl (0.90 mL, 1.0 M in THF, 0.90 mmol) were added, and the
suspension was maintained at r.t. for 16 h. The reaction mixture was
diluted with CH2Cl2 (3 mL), quenched with NH4Cl/NH3 (2:1) (2 mL),
and stirred for 1 h. The phases were separated, and the aqueous layer
was extracted with CH2Cl2 (2 × 5 mL). The combined organic extracts
were washed with brine (3 mL), dried over MgSO4, filtered, and con-
centrated under reduced pressure to afford the crude compound.
HRMS (ESI): m/z [M + Na]+ calcd for C23H37BrNaSSi4: 559.0769; found:
559.0782.
(Z)-1,1,1,3,3,3-Hexamethyl-2-[2-(phenylselenyl)vinyl]-2-(trimeth-
ylsilyl)trisilane (3e)
Prepared according to Method C18 from ethynyl(phenyl)selenide (1e)
(45 mg, 0.25 mmol). Purification of the crude product (Z/E >98:2) by
flash chromatography on silica gel (n-pentane) afforded analytically
pure 3e (54 mg, 51% yield) as a colorless oil.
IR (neat): 2960, 2893, 2360, 1536, 1477, 1438, 1244, 833, 736, 689,
Silylzincation via Method B Followed by Cu(I)-Mediated Allylation;
General Procedure 2
622 cm–1
.
1H NMR (300 MHz, C6D6): δ = 7.45 (d, J = 11.7 Hz, 1 H), 7.40–7.37 (m,
2 H), 6.97–6.94 (m, 3 H), 6.43 (d, J = 11.7 Hz, 1 H), 0.36 (s, 27 H).
13C NMR (75 MHz, C6D6): δ = 140.4, 132.3, 132.1, 129.5, 128.2, 127.2,
To a stirred solution of the appropriate α-heteroatom-substituted
alkyne 1 (0.25 mmol, 1.0 equiv) in n-hexane (2 mL) was added
(Me3Si)3SiH (0.10 mL, 0.32 mmol, 1.3 equiv) at r.t. Et2Zn (0.75 mL, 1.0
M in hexanes, 0.75 mmol, 3.0 equiv) was added at 0 °C, and the mix-
1.6.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

I
C. Fopp et al.
Feature
Synthesis
HRMS (ESI): m/z [M + K]+ calcd for C17H34KSeSi4: 469.0522; found:
(Z)-1,1,1,3,3,3-Hexamethyl-2-[2-(phenylthio)penta-1,4-dien-1-yl]-
469.0534.
2-(trimethylsilyl)trisilane (9)
Prepared according to General Procedure 2 from ethynyl(phenyl)sul-
fide (1a) (34 mg, 0.25 mmol). Purification of the crude product by
flash chromatography on silica gel (n-pentane) afforded product 9
contaminated with 3a (69 mg, 9/3a = 72:28, 48% calculated yield of
9).
1H NMR (400 MHz, CDCl3): δ = 7.31–7.15 (m, 5 H), 5.92 (s, 1 H), 5.73
(ddt, J = 16.8, 10.1, 6.7 Hz, 1 H), 4.99–4.94 (m, 1 H), 4.91–4.85 (m, 1
H), 2.93 (d, J = 6.6 Hz, 2 H), 0.18 (s, 27 H).
(E)-Dimethyl(phenyl)[2-(phenylthio)penta-1,4-dien-1-yl]silane
(6)
Prepared according to General Procedure
1
(–78 °C) from
ethynyl(phenyl)sulfide (1a) (36 mg, 0.27 mmol). Purification of the
crude product (E/Z >98:2) by flash chromatography on silica gel (n-
pentane) afforded analytically pure 6 (49 mg, 60%) as a yellow oil.
IR (neat): 3076, 2960, 1638, 1566, 1474, 1247, 1112, 988, 912, 829,
778, 728, 689 cm–1
.
HRMS (APCI): m/z [M + H]+ calcd for C20H39SSi4: 423.1844; found:
1H NMR (500 MHz, CDCl3): δ = 7.52–7.48 (m, 4 H), 7.41–7.34 (m, 6 H),
5.77 (ddt, J = 16.8, 10.2, 6.5 Hz, 1 H), 5.45 (s, 1 H), 5.07–5.00 (m, 2 H),
3.06 (dt, J = 6.4, 1.5 Hz, 2 H), 0.36 (s, 6 H).
423.1838.
1,1,1,3,3,3-Hexamethyl-2-(2-tosylpenta-1,4-dien-1-yl)-2-
(trimethylsilyl)trisilane (10)
13C NMR (125 MHz, CDCl3): δ = 153.7, 139.3, 135.3, 134.9, 133.9,
Prepared according to General Procedure 2 from ethynyl(p-tolyl)sul-
fone (1c) (45 mg, 0.25 mmol). Purification of the crude product
(Z/E = 50:50) by flash chromatography on silica gel (cyclohexane/EtOAc,
100:0 then 98:2) afforded two fractions containing, respectively, ana-
lytically pure (Z)-10 (30 mg, 26%, Z/E >98:2) and analytically pure (E)-
10 (26 mg, 22%, E/Z >98:2).
132.7, 129.4, 129.1, 128.6, 127.9, 121.9, 117.0, 40.7, –0.6.
HRMS (APCI): m/z [M + H]+ calcd for C19H23SSi: 311.1284; found:
311.1281.
(R,E)-Dimethyl(phenyl)[2-(p-tolylsulfinyl)penta-1,4-dien-1-yl]si-
lane (7)
Prepared according to General Procedure
1 (–78 °C) from (R)-
(Z)-10
ethynyl(p-tolyl)sulfoxide (1b) (48 mg, 0.29 mmol). Purification of the
crude product (E/Z >98:2) by flash column chromatography on silica
gel (n-pentane/Et2O = 80:20) afforded analytically pure 7 (93 mg,
93%) as a pale yellow solid.
IR (neat): 2947, 2893, 1301, 1242, 1143, 825, 672, 607 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.78–7.71 (m, 2 H), 7.37–7.30 (m, 2 H),
6.51 (t, J = 1.1 Hz, 1 H), 5.57 (ddt, J = 16.9, 10.0, 6.8 Hz, 1 H), 5.10–5.02
(m, 1 H), 4.99–4.89 (m, 1 H), 2.88–2.82 (m, 2 H), 2.43 (s, 3 H), 0.26 (s,
27 H).
13C NMR (75 MHz, CDCl3): δ = 151.6, 144.2, 139.6, 136.7, 134.1, 129.8,
128.3, 118.3, 38.1, 21.7, 1.7.
Mp 43 °C; [α]D20 +173.10 (c 1.0, CH2Cl2).
IR (neat): 3069, 3019, 2957, 1608, 1492, 1427, 1305, 1427, 1305,
1247, 1112, 1080, 1045, 987, 930, 900, 868, 819, 772, 742, 702 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 7.52–7.48 (m, 4 H), 7.36–7.32 (m, 3 H),
7.25 (d, J = 8.1 Hz, 2 H), 6.98 (s, 1 H), 5.50–5.42 (m, 1 H), 4.93–4.91 (m,
1 H), 4.85–4.81 (m, 1 H), 3.00–2.95 (m, 1 H), 2.56–2.51 (m, 1 H), 2.39
(s, 3 H), 0.48 (s, 3 H), 0.47 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 158.4, 142.1, 139.7, 137.6, 133.82,
133.76, 130.0, 129.5, 128.0, 127.2, 126.4, 117.4, 33.6, 21.5, –1.3, –1.4.
HRMS (ESI): m/z [M + Na]+ calcd for C21H40NaO2SSi4: 491.1718; found:
491.1737.
(E)-10
IR (neat): 2950, 2896, 1247, 1146, 828, 690 cm–1
.
1H NMR (300 MHz, CDCl3): δ = 7.71–7.65 (m, 2 H), 7.33–7.25 (m, 2 H),
7.18 (s, 1 H), 5.57 (ddt, J = 16.2, 10.1, 6.1 Hz, 1 H), 5.05–4.91 (m, 2 H),
3.16 (dt, J = 6.1, 1.7 Hz, 2 H), 2.42 (s, 3 H), 0.19 (s, 27 H).
HRMS (APCI): m/z [M + H]+ calcd for C20H25OSSi: 341.1390; found:
341.1394.
13C NMR (75 MHz, CDCl3): δ = 152.4, 144.0, 138.9, 137.6, 134.1, 129.6,
128.5, 117.5, 36.2, 21.7, 1.3.
HRMS (ESI): m/z [M + Na]+ calcd for C21H40NaO2SSi4: 491.1718; found:
491.1713.
(E)-Dimethyl(phenyl)(2-tosylpenta-1,4-dien-1-yl)silane (8)
Prepared according to General Procedure 1 (0 °C) from ethynyl(p-
tolyl)sulfone (1c) (51 mg, 0.28 mmol). Purification of the crude prod-
uct (E/Z >98:2) by flash column chromatography on silica gel
(cyclohexane/EtOAc = 80:20) afforded analytically pure 8 (61 mg,
59%) as a colorless oil.
(E)-1,1,1,3,3,3-Hexamethyl-2-[2-(phenylsulfonyl)-2-(tributylstan-
nyl)vinyl]-2-(trimethylsilyl)trisilane (12)
IR (neat): 3068, 2955, 1595, 1427, 1299, 1250, 1143, 1084, 988, 914,
811, 715 cm–1
.
Prepared according to General Procedure 3 from ethynyl(phenyl)sul-
fide (1a) (34 mg, 0.25 mmol) and n-Bu3SnCl (0.37 mL, 1.4 mmol, 5.4
equiv) as the electrophile. The crude compound (E/Z >98:2) was dis-
solved in CH2Cl2 (3 mL) and NaHCO3 (21 mg, 0.25 mmol, 1 equiv) fol-
lowed by m-CPBA (≤77% assay, 108 mg, 0.48 mmol, 1.9 equiv) were
added. The mixture was stirred at r.t. for 2 h and 5 min at 40 °C. Upon
cooling, silica gel was added and the mixture was purified by flash
chromatography on silica gel (cyclohexane/EtOAc = 99:1) to afford
analytically pure 12 (121 mg, 69%, E/Z >98:2) as a colorless oil.
1H NMR (500 MHz, CDCl3): δ = 7.69–7.68 (m, 2 H), 7.47–7.45 (m, 2 H),
7.40–7.31 (m, 3 H), 7.37 (s, 1 H), 7.28–7.27 (m, 2 H), 5.43 (ddt, J = 17.1,
10.2, 6.1 Hz, 1 H), 4.80–4.77 (m, 1 H), 4.75–4.71 (m, 1 H), 3.00 (dt,
J = 6.1, 1.7 Hz, 2 H), 2.40 (s, 3 H), 0.45 (s, 6 H).
13C NMR (125 MHz, CDCl3): δ = 153.8, 144.3, 138.9, 136.44, 136.41,
134.1, 134.0, 133.9, 129.8, 128.7, 128.2, 116.9, 33.8, 21.7, –1.7.
HRMS (APCI): m/z [M + H]+ calcd for C20H25O2SSi: 357.1339; found:
357.1338.
IR (neat): 2954, 2925, 2873, 1446, 1288, 1244, 1137, 1084, 1045, 833,
750, 725, 688, 620 cm–1
.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

J
C. Fopp et al.
Feature
Synthesis
1H NMR (300 MHz, C6D6): δ = 7.90–7.87 (m, 2 H), 7.36 (s, 1 H), 7.03–
6.97 (m, 3 H), 1.45–1.35 (m, 6 H), 1.31–1.19 (m, 6 H), 0.92–0.80 (m, 15
H), 0.43 (s, 27 H).
13C NMR (75 MHz, C6D6): δ = 162.4, 156.5, 143.1, 132.4, 128.9, 127.4,
29.1, 27.7, 13.9, 11.6, 2.1.
[α]D20 –203.03 (c 0.7, CH2Cl2).
IR (neat): 2948, 2893, 2362, 1713, 1245, 1141, 828, 687, 623 cm–1
1H NMR (400 MHz, C6D6): δ = 7.77–7.70 (m, 2 H), 6.97–6.92 (m, 2 H),
6.53 (t, J = 1.5 Hz, 1 H), 6.15 (d, J = 1.7 Hz, 1 H), 5.25–5.21 (m, 1 H),
3.64 (d, J = 16.5 Hz, 1 H), 3.10 (ddd, J = 16.5, 1.5, 0.9 Hz, 1 H), 1.97 (s, 3
H), 1.35 (s, 9 H), 0.35 (s, 27 H).
.
HRMS (ESI): m/z [M + Na]+ calcd for C29H60NaO2SSi4Sn: 727.2306;
found: 727.2335.
13C NMR (100 MHz, C6D6): δ = 165.7, 159.9, 141.0, 140.3, 139.7, 135.1,
129.9, 127.4, 125.3, 80.3, 31.6, 28.1, 21.1, 1.5.
HRMS (ESI): m/z [M + Na]+ calcd for C26H48NaO3SSi4: 575.2293; found:
575.2313.
(Z)-2-{2-[(2′-Bromo-1,1′-biphenyl-2-yl)thio]penta-1,4-dien-1-yl}-
1,1,1,3,3,3-hexamethyl-2-(trimethylsilyl)trisilane (13)
Prepared according to General Procedure 3 (reaction time of 22 h for
the silylzincation step) from (2′-bromo-1,1′-biphenyl-2-yl)ethynyl-
sulfide (1d) (72 mg, 0.25 mmol) and allyl bromide as the electrophile
(0.12 mL, 1.4 mmol, 5.5 equiv). Purification of the crude product (Z/E
>98:2) by flash chromatography on silica gel (n-pentane) afforded an-
alytically pure 13 (64 mg, 44% yield, Z/E >98:2) as a colorless oil.
(S,E)-1,1,1,3,3,3-Hexamethyl-2-[2-(p-tolylsulfinyl)-2-(tributyl-
stannyl)vinyl]-2-(trimethylsilyl)trisilane (16)
Prepared according to General Procedure 3 from (R)-ethynyl(p-
tolyl)sulfoxide (1b) (41 mg, 0.25 mmol) and n-Bu3SnCl (0.37 mL, 1.4
mmol, 5.4 equiv) as the electrophile. Purification of the crude product
(E/Z >98:2) by flash chromatography on silica gel (n-
pentane/Et2O = 100:0 then 95:5 then 90:10) afforded analytically
pure 16 (107 mg, 59%, E/Z >98:2).
IR (neat): 2948, 1560, 1456, 1427, 1244, 1029, 834, 752, 688, 624 cm–1
.
1H NMR (300 MHz, C6D6): δ = 7.47 (dd, J = 8.0, 1.2 Hz, 1 H), 7.35 (dd,
J = 8.0, 1.5 Hz, 1 H), 7.19–7.16 (m, 1 H), 7.10–7.04 (m, 2 H), 7.03–6.93
(m, 2 H), 6.77 (ddd, J = 9.1, 7.4, 1.7 Hz, 1 H), 6.18 (s, 1 H), 5.89–5.76
(m, 1 H), 4.98–4.87 (m, 2 H), 3.11 (dt, J = 6.8, 1.2 Hz, 2 H), 0.30 (s, 27
H).
13C NMR (75 MHz, C6D6): δ = 150.2, 142.3, 141.9, 136.3, 135.6, 133.0,
131.7, 130.7, 130.1, 129.9, 129.5, 128.6, 127.1, 126.3, 124.3, 116.6,
43.9, 1.7.
[α]D20 –146.96 (c 1.0, CH2Cl2).
IR (neat): 2952, 2921, 1459, 1396, 1243, 1077, 1040, 826 cm–1
.
1H NMR (500 MHz, C6D6): δ = 7.69 (d, J = 8.2 Hz, 2 H), 7.16 (s, 1 H),
6.98 (d, J = 8.2 Hz, 2 H), 1.99 (s, 3 H), 1.62–1.51 (m, 3 H), 1.50–1.40 (m,
3 H), 1.36–1.27 (m, 6 H), 1.08–0.99 (m, 3 H), 0.95–0.88 (m, 12 H), 0.35
(s, 27 H).
13C NMR (125 MHz, C6D6): δ = 175.7, 149.2, 143.3, 139.9, 129.7, 125.5,
29.4, 27.8, 21.0, 14.0, 12.0, 1.4.
HRMS (ESI): m/z [M + Na]+ calcd for C26H41BrNaSSi4: 599.1082; found:
599.1100.
HRMS (ESI): m/z [M + Na]+ calcd for C30H62NaOSSi4Sn: 725.2514;
found: 725.2538.
(S,Z)-1,1,1,3,3,3-Hexamethyl-2-[2-(p-tolylsulfinyl)penta-1,4-dien-
1-yl]-2-(trimethylsilyl)trisilane (14)
Prepared according to General Procedure 3 from (R)-ethynyl(p-
tolyl)sulfoxide (1b) (41 mg, 0.25 mmol) and allyl bromide (0.12 mL,
1.4 mmol, 5.5 equiv) as the electrophile. Purification of the crude
product (Z/E >98:2) by flash chromatography on silica gel (n-
pentane/Et2O = 95:5) afforded analytically pure 14 (77 mg, 68% yield,
Z/E >98:2) as a colorless oil.
(S,E)-1,1,1,3,3,3-Hexamethyl-2-[2-(phenylselenyl)-2-(p-tolyl-
sulfinyl)vinyl]-2-(trimethylsilyl)trisilane (17)
Prepared according to General Procedure 3 from (R)-ethynyl(p-
tolyl)sulfoxide (1b) (41 mg, 0.25 mmol) and phenylselenium chloride
(265 mg, 1.4 mmol, 5.5 equiv) as the electrophile. Purification of the
crude product (E/Z >98:2) by flash chromatography on silica gel (n-
pentane/Et2O = 95:5 then 90:10) afforded analytically pure 17 (93
mg, 66%, E/Z >98:2) as a colorless oil.
[α]D20 –290.72 (c 1.0, CH2Cl2).
IR (neat): 2947, 2892, 1396, 1243, 1046 cm–1
.
1H NMR (400 MHz, C6D6): δ = 7.71–7.65 (m, 2 H), 6.97–6.90 (m, 2 H),
6.48 (t, J = 1.3 Hz, 1 H), 5.60 (dddd, J = 17.0, 10.0, 7.7, 6.3 Hz, 1 H),
4.92–4.87 (m, 1 H), 4.78 (dq, J = 17.0, 1.6 Hz, 1 H), 3.37 (ddq, J = 16.7,
6.3, 1.2 Hz, 1 H), 2.64 (ddq, J = 16.7, 7.7, 1.2 Hz, 1 H), 1.98 (s, 3 H), 0.34
(s, 27 H).
13C NMR (100 MHz, C6D6): δ = 160.7, 141.0, 140.3, 135.3, 135.0, 129.9,
125.1, 117.9, 33.1, 21.1, 1.4.
[α]D20 –163.49 (c 1.0, CH2Cl2).
IR (neat): 2947, 2892, 1438, 1244, 1054, 820, 739, 689, 621, 502 cm–1
1H NMR (400 MHz, CDCl3): δ = 7.55–7.50 (m, 2 H), 7.50–7.46 (m, 2 H),
7.34–7.28 (m, 2 H), 7.28–7.22 (m, 3 H), 6.52 (s, 1 H), 2.41 (s, 3 H), 0.17
(s, 27 H).
.
13C NMR (100 MHz, CDCl3): δ = 154.6, 142.7, 141.2, 139.4, 136.3,
129.8, 129.6, 129.4, 128.7, 125.1, 21.6, 1.2.
HRMS (ESI): m/z [M + Na]+ calcd for C24H40NaOSSeSi4: 591.0934;
HRMS (ESI): m/z [M + Na]+ calcd for C21H40NaOSSi4: 475.1769; found:
475.1780.
found: 591.0942.
(S,Z)-tert-Butyl 5-[1,1,1,3,3,3-Hexamethyl-2-(trimethylsilyl)trisi-
lan-2-yl]-2-methylene-4-(p-tolylsulfinyl)pent-4-enoate (15)
(E)-5-(Dimethylphenylsilyl)penta-1,4-dien-4-yl N,N-Diisopropyl-
carbamate (18)
Prepared according to General Procedure 3 from (R)-ethynyl(p-
tolyl)sulfoxide (1b) (41 mg, 0.25 mmol) and tert-butyl 2-(bro-
momethyl)acrylate (297 mg, 1.35 mmol, 5.4 equiv) as the electro-
phile. Purification of the crude product (Z/E >98:2) by flash chroma-
tography on silica gel (cyclohexane/EtOAc = 100:0 then 98:2 then
95:5) afforded analytically pure 15 (103 mg, 75%, Z/E >98:2) as a col-
orless oil.
Prepared according to General Procedure 1 (–78 °C) from ethynyl N,N-
diisopropylcarbamate (1f) (49 mg, 0.29 mmol). Purification of the
crude product (E/Z >98:2) by flash column chromatography on silica
gel (n-pentane/Et2O = 100:0 then 90:10) afforded analytically pure 18
(41 mg, 42%) as a pale yellow oil.
IR (neat): 3068, 2965, 1705, 1633, 1427, 1327, 1302, 1263, 1212,
1111, 1089, 1042, 1006, 916, 814 cm–1
.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

K
C. Fopp et al.
Feature
Synthesis
1H NMR (500 MHz, CDCl3): δ = 7.56–7.54 (m, 2 H), 7.34–7.32 (m, 3 H),
5.86 (ddt, J = 17.0, 10.1, 7.0 Hz, 1 H), 5.16 (s, 1 H), 5.14–5.08 (m, 2 H),
4.00–3.89 (m, 1 H), 3.68–3.57 (m, 1 H), 3.13 (d, J = 7.0 Hz, 2 H), 1.26
(d, J = 6.8 Hz, 6 H), 1.06 (d, J = 6.9 Hz, 6 H), 0.34 (s, 6 H).
13C NMR (125 MHz, CDCl3): δ = 162.0, 152.1, 139.4, 134.2, 133.9,
128.9, 127.8, 117.7, 111.3, 47.0, 45.7, 40.6, 21.2, 20.6, –1.4.
(E)-Diethyl {1-[Dimethyl(phenyl)silyl]penta-1,4-dien-2-yl}phos-
phonate (25)
Prepared according to General Procedure 1 (0 °C) from diethyl ethyn-
ylphosphonate (1h) (46 mg, 0.28 mmol). Purification of the crude
product (E/Z >98:2) by flash column chromatography on silica gel
(cyclohexane/EtOAc = 60:40) afforded analytically pure 25 (81 mg,
85%, E/Z >98:2) as a yellow oil.
HRMS (APCI): m/z [M + H]+ calcd for C20H32NO2Si: 346.2197; found:
IR (neat): 2984, 1637, 1586, 1428, 1391, 1247, 1163, 1113, 1053,
346.2196.
1020, 955, 813, 771, 731, 698 cm–1
.
(Z)-5-[1,1,1,3,3,3-Hexamethyl-2-(trimethylsilyl)trisilan-2-yl]pen-
ta-1,4-dien-4-yl N,N-Diisopropylcarbamate (20)
1H NMR (500 MHz, CDCl3): δ = 7.51–7.49 (m, 2 H), 7.36–7.31 (m, 3 H),
6.98 (d, J = 34.0 Hz, 1 H), 5.68 (ddt, J = 17.0, 10.2, 6.5 Hz, 1 H), 4.94–
4.89 (m, 2 H), 4.01–3.97 (m, 4 H), 3.05–3.00 (m, 2 H), 1.29 (t, J = 7.1
Hz, 6 H), 0.44 (s, 6 H).
Prepared according to General Procedure 3 from ethynyl N,N-diiso-
propylcarbamate (1f) (42 mg, 0.25 mmol) and allyl bromide (0.12 mL,
1.4 mmol, 5.5 equiv) as the electrophile at 60 °C. Purification of the
crude product by flash chromatography on silica gel
(cyclohexane/EtOAc = 99:1 then 97:3) afforded product 20 contami-
nated with 3f (56 mg, 20/3f = 65:35, 34% calculated yield of 20).
1H NMR (400 MHz, CDCl3): δ = 5.84–5.74 (m, 1 H), 5.10–4.91 (m, 2 H),
5.01 (s, 1 H), 4.46–4.31 (m, 1 H), 3.20 (d, J = 6.7 Hz, 2 H), 3.14–3.01 (m,
1 H), 1.37 (d, J = 6.7 Hz, 6 H), 0.94 (d, J = 6.7 Hz, 6 H), 0.34 (s, 27 H).
13C NMR (125 MHz, CDCl3): δ = 146.9 (d, JC–P = 1.4 Hz), 146.2 (d, JC–P
=
63.5 Hz), 137.6, 135.2, 133.8, 129.4, 128.0, 116.3, 61.8 (d, JC–P = 5.8
Hz), 36.7 (d, JC–P = 14.3 Hz), 16.4 (d, JC–P = 6.2 Hz), –1.4.
HRMS (APCI): m/z [M + H]+ calcd for C17H28O3PSi: 339.1540; found:
339.1537.
Diethyl {1-[1,1,1,3,3,3-Hexamethyl-2-(trimethylsilyl)trisilan-2-
yl]-penta-1,4-dien-2-yl}phosphonate (26)
HRMS (ESI): m/z [M + Na]+ calcd for C21H47NaNO2Si4: 480.2576;
found: 480.2563.
Prepared according to General Procedure 3 from diethyl ethynylphos-
phonate (1h) (41 mg, 0.25 mmol) and allyl bromide (0.12 mL, 1.4
mmol, 5.5 equiv) as the electrophile. Purification of the crude product
(Z)-2-[2-(4-Methoxyphenoxy)penta-1,4-dien-1-yl]-1,1,1,3,3,3-
hexamethyl-2-(trimethylsilyl)trisilane (21)
(Z/E = 84:16)
by
flash
chromatography
on
silica
gel
(cyclohexane/EtOAc = 99:1 then 90:10 and 80:20) afforded two frac-
tions containing, respectively, analytically pure (Z)-26 (82 mg, 72%,
Z/E >98:2) and (E)-26 (16 mg, 14%, E/Z >98:2).
Prepared according to General Procedure 3 from 1-(ethynyloxy)-4-
methoxybenzene (1g) (37 mg, 0.25 mmol) and allyl bromide (0.12
mL, 1.4 mmol, 5.5 equiv) as the electrophile. Purification of the crude
product (Z/E >98:2) by flash chromatography on silica gel (n-
pentane/Et2O = 99:1) afforded 21 (62 mg, 57%, Z/E >98:2) as a color-
less oil.
(Z)-26
IR (neat): 2980, 2947, 2894, 1442, 1392, 1244, 1059, 1030, 958, 832,
749, 687, 616 cm–1
.
IR (neat): 2947, 2893, 1622, 1502, 1242, 1209, 1090, 1040, 829, 745,
687, 623 cm–1
.
1H NMR (300 MHz, C6D6): δ = 6.86 (dt, J = 57.7, 1.4 Hz, 1 H), 5.85–5.72
(m, 1 H), 5.04–4.95 (m, 2 H), 3.95–3.85 (m, 4 H), 3.11–3.05 (m, 2 H),
1.05 (t, J = 7.1 Hz, 6 H), 0.44 (s, 27 H).
1H NMR (300 MHz, C6D6): δ = 6.88–6.80 (m, 2 H), 6.69–6.62 (m, 2 H),
5.80–5.66 (m, 1 H), 4.98–4.94 (m, 1 H), 4.93–4.88 (m, 1 H), 4.84 (s, 1
H), 3.26 (s, 3 H), 2.87 (d, J = 6.6 Hz, 2 H), 0.34 (s, 27 H).
13C NMR (75 MHz, C6D6): δ = 163.8, 156.0, 149.3, 134.8, 120.5, 116.9,
114.9, 99.6, 55.1, 38.5, 1.4.
13C NMR (75 MHz, C6D6): δ = 146.4 (d, JC–P = 20.8 Hz), 144.2 (d, JC–P
=
177.8 Hz), 136.2 (d, JC–P = 6.0 Hz), 117.0, 61.2 (d, JC–P = 5.8 Hz), 40.8 (d,
JC–P = 14.5 Hz), 16.5, 16.4, 2.1.
HRMS (ESI): m/z [M + Na]+ calcd for C18H43NaO3PSi4: 473.1919; found:
HRMS (ESI): m/z [M + Na]+ calcd for C21H40NaO2Si4: 459.1998; found:
473.1902.
459.1993.
(E)-26
(E)-2-[2-(4-Methoxyphenoxy)-2-(tributylstannyl)vinyl]-
1,1,1,3,3,3-hexamethyl-2-(trimethylsilyl)trisilane (22)
IR (neat): 2950, 2896, 1244, 1052, 1023, 959, 912, 831, 779, 690, 615
cm–1
.
Prepared according to General Procedure 3 from 1-(ethynyloxy)-4-
methoxybenzene (1g) (37 mg, 0.25 mmol) and n-Bu3SnCl (0.37 mL,
1.4 mmol, 5.4 equiv) as the electrophile. Purification of the crude
product (E/Z >98:2) by flash chromatography on silica gel (n-
pentane/Et2O = 99:1) afforded 22 (88 mg, 51%, E/Z >98:2) as a color-
less oil.
1H NMR (500 MHz, CDCl3): δ = 6.92 (d, J = 31.3 Hz, 1 H), 5.77 (ddt,
J = 16.9, 10.2, 6.6 Hz, 1 H), 5.17–5.10 (m, 1 H), 5.09–5.05 (m, 1 H),
4.08–3.95 (m, 4 H), 3.18–3.10 (m, 2 H), 1.29 (t, J = 7.1 Hz, 6 H), 0.21 (s,
27 H).
13C NMR (125 MHz, CDCl3): δ = 144.8 (d, JC–P = 164.3 Hz), 144.0, 135.5,
116.9, 61.7 (d, JC–P = 5.9 Hz), 39.6 (d, JC–P = 16.0 Hz), 16.5 (d, JC–P = 6.5
Hz), 1.4.
IR (neat): 2953, 2925, 2853, 1500, 1242, 1208, 1041, 1013, 828, 688,
621 cm–1
.
1H NMR (400 MHz, C6D6): δ = 7.00–6.94 (m, 2 H), 6.73–6.67 (m, 2 H),
5.18 (s, 1 H), 3.26 (s, 3 H), 1.53–1.46 (m, 6 H), 1.38–1.29 (m, 6 H), 0.93
(t, J = 7.3 Hz, 9 H), 0.84–0.80 (m, 6 H), 0.38 (s, 27 H).
13C NMR (100 MHz, C6D6): δ = 177.9, 156.3, 152.4, 120.6, 115.0, 114.1,
55.1, 29.5, 27.8, 14.0, 12.0, 1.4.
(E)-Diethyl {2-[1,1,1,3,3,3-Hexamethyl-2-(trimethylsilyl)trisilan-
2-yl]-1-(tributylstannyl)vinyl}phosphonate (27)
Prepared according to General Procedure 3 from diethyl ethynylphos-
phonate (1h) (41 mg, 0.25 mmol) and n-Bu3SnCl (0.37 mL, 1.4 mmol,
5.4 equiv) as the electrophile. Purification of the crude product (E/Z
HRMS (ESI): m/z [M + Na]+ calcd for C30H62NaO2Si4Sn: 709.2744;
found: 709.2765.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L

L
C. Fopp et al.
Feature
Synthesis
>98:2)
by
flash
chromatography
on
silica
gel
(13) 1-Alkoxyalkynes: Murakami, M.; Amii, H.; Takizawa, N.; Ito, Y.
Organometallics 1993, 12, 4223.
(14) 1-Phenylthioalkynes: Casson, S.; Kocienski, P.; Reid, G.; Smith,
N.; Street, J. M.; Webster, M. Synthesis 1994, 1301.
(cyclohexane/EtOAc = 99:1) afforded analytically pure 27 (88 mg,
50%, E/Z >98:2).
IR (neat): 2955, 2927, 2897, 2361, 2342, 1464, 1391, 1242, 1057,
(15) Ynamides: (a) Timbart, L.; Cintrat, J.-C. Chem. Eur. J. 2002, 8,
1637. (b) Naud, S.; Cintrat, J.-C. Synthesis 2003, 1391.
(16) Ynamides: Saito, N.; Saito, K.; Sato, H.; Sato, Y. Adv. Synth. Catal.
2013, 355, 853.
(17) The Cu(I)-catalyzed addition of silicon nucleophiles released
from Si–B interelement compounds is known but without
C(sp2)–B bond formation, see: (a) Arylsulfonylalkynes: Linstadt,
R. T. H.; Peterson, C. A.; Lippincott, D. J.; Jette, C. I.; Lipshutz, B.
H. Angew. Chem. Int. Ed. 2014, 53, 4159. (b) Ynamides:
Vercruysse, S.; Jouvin, K.; Riant, O.; Evano, G. Synthesis 2016, 48,
3373.
1032, 955, 833, 750, 687, 610 cm–1
.
1H NMR (300 MHz, C6D6): δ = 7.58 (d, J = 73.1 Hz, 1 H), 4.00–3.90 (m,
4 H), 1.69–1.56 (m, 6 H), 1.48–1.33 (m, 6 H), 1.16–0.92 (m, 6 H), 1.15–
1.07 (m, 9 H), 0.96 (t, J = 7.3 Hz, 6 H), 0.45 (s, 27 H).
13C NMR (75 MHz, C6D6): δ = 164.4 (d, JC–P = 8.1 Hz), 154.6 (d, JC–P
141.7 Hz), 61.4 (d, JC–P = 5.7 Hz), 30.0, 28.5, 17.2 (d, JC–P = 6.4 Hz), 14.6,
=
11.9, 2.7.
HRMS (ESI): m/z [M + Na]+ calcd for C27H65NaO3PSi4Sn: 723.2665;
found: 723.2694.
(18) Fopp, C.; Romain, E.; Isaac, K.; Chemla, F.; Ferreira, F.; Jackowski,
O.; Oestreich, M.; Perez-Luna, A. Org. Lett. 2016, 18, 2054.
(19) Romain, E.; Fopp, C.; Chemla, F.; Ferreira, F.; Jackowski, O.;
Oestreich, M.; Perez-Luna, A. Angew. Chem. Int. Ed. 2014, 53,
11333.
(20) Computational evidence for such a mechanism was reported for
the silylzincation of 1-phenylallene with Me3SiZnMe, see:
Yonehara, M.; Nakamura, S.; Muranaka, A.; Uchiyama, M. Chem.
Asian J. 2010, 5, 452.
(21) Such a mechanism is reminiscent of the trans-selective radical
carbozincation of alkynes with dialkylzinc reagents, see:
(a) Maury, J.; Feray, L.; Bertrand, M. Org. Lett. 2011, 13, 1884.
(b) Chemla, F.; Dulong, F.; Ferreira, F.; Nüllen, M.; Pérez-Luna, A.
Synthesis 2011, 1347. (c) Chemla, F.; Dulong, F.; Ferreira, F.;
Pérez-Luna, A. Beilstein J. Org. Chem. 2013, 9, 236.
Acknowledgment
This research was supported by the Deutsche Forschungsgemein-
schaft (Oe 249/7-1) and by the Agence Nationale de la Recherche (SA-
TRAZ Project, grant no. 2011-INTB-1015-01).
Supporting Information
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0036-1588106.
S
u
p
p
ortiInfogrmoaitn
S
u
p
p
ortioInfgrmoaitn
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–L