Copper-Catalyzed Silylcupration of Activated Alkynes

Article abstract of DOI:10.1055/s-0035-1562460

A highly efficient catalytic silylcupration of activated alkynes is reported. Upon reaction with silylboronates and methanol in THF at room temperature in the presence of copper(I) fluoride tris(triphenylphosphine), a range of ynamides and propiolates were found to undergo a smooth silylcupration. This reaction, which tolerates various functional groups, affords a straightforward and efficient entry to the corresponding β-silylenamides and -acrylates, which were formed with high levels of regio- and stereoselectivities.

Full text of DOI:10.1055/s-0035-1562460

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2016, 48, A–I
paper
A
S. Vercruysse et al.
Paper
Synthesis
Copper-Catalyzed Silylcupration of Activated Alkynes
Sébastien Vercruyssea
Kévin Jouvinb
Olivier Riant*a
Gwilherm Evano*c
EWG
R3R42Si Bpin
MeOH
CuF(PPh3)3·2MeOH
(2 mol%)
EWG
R1
N
H
R2
N
R2
R1
SiR3R4
2
or
or
THF, rt
R1O2C
H
R2
a Institute of Condensed Matter and Nanosciences, Molecules, Solids
and Reactivity (IMCN/MOST), Université Catholique de Louvain, Place
Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
olivier.riant@uclouvain.be
b Institut Lavoisier de Versailles, UMR CNRS 8180, Université de Ver-
sailles Saint-Quentin-en-Yvelines, 45, avenue des Etats-Unis, 78035
Versailles Cedex, France
R1O2C
R2
SiR3R4
2
27 examples, 15–99% yield
high regio- and stereoselectivities
c Laboratoire de Chimie Organique, Service de Chimie et Physico-
Chimie Organiques, Université libre de Bruxelles (ULB), Avenue F. D.
Roosevelt 50, CP160/06, 1050 Brussels, Belgium
gevano@ulb.ac.be
Dedicated to the memory of Jean Normant, a wonderful man and a truly inspiring chemist
Received: 15.06.2016
Accepted after revision: 16.06.2016
Published online: 08.08.2016
1. EtCu·MgBr2
Et2O, –10 °C
2
Et
E
E
Bu
2. E
Bu
DOI: 10.1055/s-0035-1562460; Art ID: ss-2016-c0357-op
1
3
6
Abstract A highly efficient catalytic silylcupration of activated alkynes
is reported. Upon reaction with silylboronates and methanol in THF at
room temperature in the presence of copper(I) fluoride tris(triphenyl-
phosphine), a range of ynamides and propiolates were found to under-
go a smooth silylcupration. This reaction, which tolerates various func-
tional groups, affords a straightforward and efficient entry to the
corresponding β-silylenamides and -acrylates, which were formed with
high levels of regio- and stereoselectivities.
1. BuCu·MgBr2
Et2O/pentane, 20 °C
5
Bu
2. E
4
Scheme 1 First examples of carbocupration of alkynes
Indeed, the nature of the solvent, the presence of salts, the
temperature and, more importantly, the nature of both the
organocopper and the alkyne have been shown to have a
great impact on the success of the process.2 Concerning the
organocopper reagent, it could be successfully extended to
stannyl-,4 silyl-,4c,5 boryl-,6 and hydrocuprations,7 both stoi-
chiometrically and catalytically. The influence of the nature
of the alkyne is probably stronger and if terminal alkynes
are ideal substrates for carbocuprations and related pro-
cesses, internal alkynes typically undergo poorly regiose-
lective carbocuprations leading to mixtures of regioisomer-
ic alkenylcopper reagents and the reaction is, in addition,
generally sluggish.
Indeed, both substituents in dialkyl-substituted acety-
lenes have a similar effect on the polarization of the alkyne
yielding to inefficient carbocuprations. A general solution
to this limitation relies in the introduction of a functional
group (FG) judiciously placed in the proximity of the
alkyne. This group can either strongly polarize the alkyne –
such as in ynol ethers,8 ynamines,8,9 propiolates,10,11 fluoro-
alkylated alkynes,12 or P-alkynylphosphines 7,13 among
others – or act as a powerful directing group as is the case
with propargylic ethers14 or acetals,15 O-alkynylcarba-
Key words copper catalysis, silylcupration, ynamides, propiolates, sil-
ylboronates
The carbocupration of alkynes is one of the most im-
portant method for the preparation of polysubstituted
alkenes due to the high levels of stereoselectivity usually
obtained with this reaction. Since its discovery by Normant
and Bourgain in 1971 who reported the regio- and stereo-
selective addition of ethylcopper (2) to hexyne (1) and the
carbocupration of acetylene (4) (Scheme 1),1 it has evolved
as an especially efficient synthetic tool for the stereocon-
trolled synthesis of alkenes.2 The high regioselectivity ob-
tained with terminal alkynes, the broad functional group
compatibility, the highly selective syn-addition, and the
synthetic usefulness of the resulting vinylcopper, which can
be trapped by a variety of electrophiles or transmetalated
with various metals and then participate in different cross-
coupling reactions, are notable feature of this venerable re-
action.
The carbocupration of alkynes, which can also be per-
formed in a catalytic manner when catalytic amounts of
copper(I) salts are used in combination with Grignard or or-
ganozinc reagents,3 can be influenced by many parameters.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

B
S. Vercruysse et al.
Paper
Synthesis
mates,16 alkynyl sulfoxides,17 or ynamides 10,18 and oth-
ers,19 which results in highly regioselective carbocuprations
(Scheme 2).
31% yield. Switching to copper(I) fluoride tris(triphenyl-
phosphine)32 was found to be especially fruitful since a
clean reaction occurred in most solvents (entries 4–6), ex-
cept in the case of DMF (entry 7). Importantly, a single re-
gioisomer was formed, demonstrating the efficiency of the
tosyl group to act as a directing group since the regioselec-
tivity was reversed compared to the silylcupration of
ynamines.33 Moreover, a single stereoisomer, whose stereo-
chemistry was assigned on the basis of NOE experiments,
resulting from a syn-silylcupration, was observed.
R2
FG
Cu
R1
Cu
FG
R2
R1
R2Cu
or
FG
R1
7
8
9
if FG = EDG (OR, NR2, ...)
if FG = EWG (CO2R,
RF, PR2, POR2...)
R2
Cu
FG
R2Cu
R1
n
FG
R1
n
10
11
Table 1 Optimization of the Copper-Catalyzed Silylcupration of
Ynamide 12a
if FG = OR, NR2,
CH(OR)2, OCONR2, SOR,
NREWG, SiR2(2-pyr)...
Cu catalyst
Scheme 2 Regioselective directed carbocupration of disubstituted
alkynes
PhMe2Si Bpin 13a
(1.1 equiv)
MeOH (1.5 equiv)
H
N
SiMe2Ph
Ph
Ts
N
Ph
Ts
solvent, rt, 16 h
Bn
On the basis of these simple concepts, the directed car-
bocupration of disubstituted alkynes was extensively stud-
ied and found various applications for the stereoselective
elaboration of highly substituted alkenes, notably in natural
product synthesis. In contrast, its extension to the silylcu-
pration of alkynes was less studied, despite a strong syn-
thetic potential brought by the incorporation of the silicon
moiety. For this reason, and due to our combined interest in
the chemistry of hetero-substituted alkynes20 and copper-
catalyzed additions to conjugated systems,21 we decided to
investigate the copper-catalyzed silylcupration of two
classes of activated alkynes: ynamides and propiolates. Re-
sults from these studies are reported in this manuscript.
We initiated our studies by examining the copper-cata-
lyzed silylcupration of ynamides, a reaction that could pro-
vide a straightforward entry to β-silylenamides together
with bringing additional insights into the reactivity of
ynamides.22 While their carbocupration had been exten-
sively explored, notably by the Marek group,18,23 the silylcu-
pration of ynamides was only reported in a stoichiometric
manner using a large excess of silylcopper reagents.24,25 In
order to develop a catalytic version of this reaction, the
source of nucleophilic silicon was to be selected first.
Among all silicon–metal species reported to date and
used in combination with a copper catalyst, including
Si–Mg,26 Si–Al,26a,27 Si–Zn,4c,27,28 Si–Si29 and Si–B5c,30 species,
Suginome’s silylboronate 13a31 was chosen due to its facile
preparation, its stability, and its easy transmetalation to
copper(I). The copper-catalyzed silylcupration was there-
fore optimized with this reagent and ynamide 12a as a
model substrate using 1.5 equivalents of methanol as the
proton source at room temperature for 16 hours (Table 1).
The efficiency of a combination of copper(I) chloride, sodi-
um tert-butoxide, and BINAP to promote the reaction in
various solvents was first evaluated (Table 1, entries 1–3);
while we were glad to note the formation of the desired si-
lylated enamide 14a in all trials, the conversions were low
regardless of the solvent used and gave, in the best case,
Bn
14a
12a
Entry Catalyst
Solvent
toluene
Yield (%)a
1
2
3
CuCl (5 mol%), NaOt-Bu (5.5 mol%),
BINAP (5.5 mol%)
10
30
31
CuCl (5 mol%), NaOt-Bu (5.5 mol%),
BINAP (5.5 mol%)
THF
CuCl (5 mol%), NaOt-Bu (5.5 mol%),
BINAP (5.5 mol%)
MeOH
4
5
6
7
CuF(PPh3)3·2MeOH (2 mol%)
CuF(PPh3)3·2MeOH (2 mol%)
CuF(PPh3)3·2MeOH (2 mol%)
CuF(PPh3)3·2MeOH (2 mol%)
toluene
THF
89
98
98
48
MeOH
DMF
a Yield of isolated, pure product.
Having in hand the optimized conditions for the copper-
catalyzed silylcupration of ynamides, we then moved to the
study of its scope and limitations. With this goal in mind, a
set of representative ynamides 12, readily prepared using
our previously reported procedures,20a,b were submitted to
the catalytic silylcupration. Results from these studies, col-
lected in Scheme 3, show the broad applicability of our pro-
cedure. Indeed, the influence of the substituent on the
starting sulfonamide did not have a marked effect on the
outcome of the silylcupration since benzyl (14a), phenyl
(14b), and homobenzyl (14c) groups were equally well tol-
erated. Similarly, changing the nature of the electron-with-
drawing group on the starting ynamide did not affect the
reaction, which afforded the corresponding β-silyl ene-
oxazolidinone 14d and ene-pyrrolidinone 14e derivatives
in good to excellent yields. After evaluating the influence of
the nature of the electron-withdrawing group in 12, we
then examined the impact of the substituent on the triple
bond by reacting various ynamides possessing representa-
tive substituents under our standard conditions. Electron-
neutral, electron-rich, and electron-deficient arenes were
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

C
S. Vercruysse et al.
Paper
Synthesis
well tolerated and a furan-substituted ynamide 12i per-
formed equally well. The reaction was, however, less effi-
cient when increasing the steric hindrance close to the tri-
ple bond. Indeed, the silylcupration of 12g required 10
mol% of the copper catalyst to afford 60% yield of 14g to-
gether with 39% of the starting material that could be re-
covered at the end of the reaction. Importantly, a double
bond (14j) and an alkyl chain (14k) were also found to be
compatible with the reaction conditions while a trimethyl-
silyl-substituted ynamide only gave 16% of the correspond-
ing β,β-disilylated enamide 14l, which can be attributed to
a diminished reactivity of the starting ynamide and a poor
stability of the resulting enamide. Finally, a terminal
ynamide was found to react equally well, affording the cor-
responding enamide 14m in 93% yield. In all cases, a single
regioisomer was observed and the reaction was also found
to be totally stereoselective.
In parallel to the study of the scope of the copper-cata-
lyzed silylcupration with respect to the nature of all sub-
stituents on the starting ynamide, the possibility of using
other silylboronates was then briefly investigated. To this
aim, ynamides 12a and 12d were reacted with triethylsi-
lylpinacolboronate 13b34 under our standard conditions.
While this reagent turned out to be less reactive than di-
methylphenylsilylpinacolboronate (13a), the reaction still
performed nicely and the corresponding silylated enamides
14a′ and 14d′ could be isolated as single regio- and stereo-
isomers (Scheme 4). As a note, the stereochemistry of the
latter could be confirmed by X-ray crystal structure analy-
sis, which confirm the syn-silylcupration yielding to the E-
isomer of 14d′ (Figure 1); this reaction therefore nicely
complements the trans-selective radical silylzincation of
terminal ynamides reported by Oestreich and Perez-
Luna.25a
CuF(PPh3)3·2MeOH
(2 mol%)
CuF(PPh3)3·2MeOH
(2 mol%)
PhMe2Si Bpin 13a
Et3Si Bpin 13b
H
N
SiMe2Ph
R2
(1.1 equiv)
MeOH (1.5 equiv)
H
N
SiEt3
Ph
(1.5 equiv)
MeOH (1.5 equiv)
EWG
Ts
N
R2
N
Ph
EWG
Ts
THF, rt, 16 h
THF, rt, 16 h
56%
R1
Bn
R1
14 (E/Z > 95:5)
Bn
14a' (E/Z > 95:5)
12
12a
CuF(PPh3)3·2MeOH
(2 mol%)
Et3Si Bpin 13b
(1.5 equiv)
MeOH (1.5 equiv)
H
N
SiMe2Ph
H
N
SiMe2Ph
Ph
H
N
SiMe2Ph
Ph
H
N
SiEt3
Ph
O
Ts
Ph
Ts
Ts
O
O
Bn
Ph
Ph
N
Ph
THF, rt, 16 h
61%
14a (98%, 68%a)
14b (92%)
14c (74%)a
SiMe2Ph
O
14d' (E/Z > 95:5)
12d
H
N
H
N
SiMe2Ph
Ph
H
N
SiMe2Ph
Ph
Scheme 4 Variation of the silylboronate in the copper-catalyzed silyl-
O
O
Ts
cupration of ynamides
Bn
O
14d (98%, 84%a)
14e (75%)a
14f (70%)a
H
N
SiMe2Ph
H
N
SiMe2Ph
H
N
SiMe2Ph
Ts
Ts
Ts
Bn
Bn
O
Bn
14g (60%, 99% brsm)b
Cl
14h (98%)
14i (87%)
H
N
SiMe2Ph
SiMe3
H
N
SiMe2Ph
H
SiMe2Ph
O
Ts
Ts
Ts
N
Figure 1 X-ray crystal structure of 14d′ confirming the regioselectivity
and the syn-stereoselectivity of the silylcupration
O
Bn
Ph
Bn
14k (75%)a
14j (85%)
14l (16%)
H
SiMe2Ph
N
H
After demonstrating the generality of the copper-cata-
lyzed silylcupration of ynamides, in which the electron-
withdrawing group of the electron-rich alkynes act as a re-
markably efficient directing group that overcomes the nat-
ural polarization of the triple bond, we then decided to
move to another class of activated alkynes substituted with
an electron-withdrawing group directly attached to the tri-
ple bond. Propiolates were therefore selected for this study,
Ph
14m (93%)c
Scheme 3 Scope of the copper-catalyzed silylcupration of ynamides.
a Reaction performed with 1.5 equiv of PhMe2SiBpin. b Reaction per-
formed with 10 mol% of CuF(PPh3)3·2MeOH. c Reaction performed with
4.0 equiv of MeOH.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

D
S. Vercruysse et al.
Paper
Synthesis
their stoichiometric35 or catalytic29c silylcupration (or con-
jugate silylation11) usually suffering from low levels of ste-
reoselectivity.
tle influence on the outcome of the reaction since electron-
neutral (16a–d) and electron-rich (16e) aromatic groups as
well as alkyl chains (16f–j) gave similar results. Moreover, a
terminal propiolate was also found to be an excellent sub-
strate for the silylcupration, the corresponding silylated ac-
rylate 16k being formed, as a single isomer, in 99% yield. Fi-
nally, it ought to be mentioned that a range of functional
groups such as a benzyl ether (16h), a benzylamine (16i),
and even a carbonate (16j) were well tolerated, further
highlighting the synthetic potential of this silylcupration.
Finally, the silylcupration of 2-pyridylpropiolate (15l)
was investigated to examine the influence of the pyridyl
group, which could potentially act as a directing group and
might therefore reverse the regioselectivity of the silylcu-
pration (Scheme 6). Indeed, the β-silyl-β-2-pyridylpropio-
late (16l) was isolated in 15% yield only together with Z-ac-
rylate 17 and over-reduced ester 18; these products result-
One of the first trials with these substrates under slight-
ly modified conditions turned out to be rather successful:
upon reaction with 1.1 equivalents of dimethylphenylsi-
lylpinacolboronate (13a) and methanol (4.0 equiv for a
clean reaction) in the presence of 2 mol % of copper(I) fluo-
ride tris(triphenylphosphine) in THF at room temperature,
methyl 3-phenylpropiolate (15a) was readily converted into
the corresponding methyl 3-dimethylphenylsilyl-3-pheny-
lacrylate (16a) in 98% yield and as a single regio- and ste-
reoisomer. The stereochemistry of 16a was assigned on the
basis of NOE experiments, therefore demonstrating further
the efficiency of our procedure (Scheme 5). A series of
propiolates 15 were next engaged in the silylcupration to
delineate its scope and limitations; results from this study
are summarized in Scheme 5.
ing from
a pyridyl-directed silylcupration/desilylation
sequence and further reduction, respectively.
CuF(PPh3)3·2MeOH
(2 mol%)
PhMe2Si Bpin 13a
H
SiMe2Ph
N
(1.1 equiv)
MeOH (4.0 equiv)
H
SiMe2Ph
R2
MeO2C
R1O2C
R2
THF, rt, 16 h
R1O2C
16l (15%, E/Z > 95:5)
15
16 (E/Z > 95:5)
CuF(PPh3)3·2MeOH
(2 mol%)
PhMe2Si Bpin 13a
(1.0 equiv)
MeOH (4.0 equiv)
+
H
H
H
SiMe2Ph
H
SiMe2Ph
Ph
H
SiMe2Ph
Ph
N
MeO2C
N
MeO2C
Ph
EtO2C
tBuO2C
MeO2C
THF, rt, 16 h
16a (98%)
16b (99%)
16c (92%)
15l
H
SiMe2Ph
17 (64%, E/Z > 95:5)
+
H
SiMe2Ph
Ph
H
SiMe2Ph
C4H9
MeO2C
H
H
H
H
BnO2C
MeO2C
MeO2C
N
16d (90%)
16e (98%) OMe
16f (85%)
H
SiMe2Ph
18 (18%)
H
SiMe2Ph
C6H13
H
SiMe2Ph
OBn
Ts
N
Scheme 6 2-Pyridyl-directed copper-catalyzed silylcupration of propi-
MeO2C
MeO2C
MeO2C
olates
Bn
16g (92%)
16h (95%)
16i (92%)
SiMe2Ph
H
SiMe2Ph
H
OCO2Me
In conclusion, we have reported a general and efficient
procedure for the copper-catalyzed silylcupration of acti-
vated alkynes. Upon reaction with silylboronates and meth-
anol in THF at room temperature in the presence of cop-
MeO2C
EtO2C
H
16j (99%)
16k (99%)
Scheme 5 Copper-catalyzed silylcupration of propiolates
per(I) fluoride tris(triphenylphosphine),
a
range of
As evidenced by these results, the silylcupration pro-
ceeded smoothly in all cases, the corresponding β-silylacry-
lates 16 being isolated in excellent yields in most cases and
as single regioisomers. They were also formed as single ste-
reoisomers resulting from a syn-silylcupration, which is in
sharp contrast with previously reported silylcuprations of
propiolates.29c,35 The reaction was found to be fairly general
and tolerated a range of esters such as methyl (16a,e–j),
ethyl (16b,k), tert-butyl (16c), and benzyl (16d) esters. The
nature of the substituent on the starting propiolate had lit-
ynamides and propiolates were found to undergo a smooth
silylcupration. High levels of regioselectivity were obtained
in most cases, which results from a directed silylcupration
in the case of ynamides and from the innate polarization of
the triple bond starting from propiolates. Moreover, the re-
action was found to be totally syn-stereoselective, which
represents a net improvement compared to results previ-
ously reported with propiolates. Overall, this reaction,
which tolerates various functional groups, affords
a
straightforward and efficient entry to β-silylenamides and
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

E
S. Vercruysse et al.
Paper
Synthesis
-acrylates, useful building blocks, and further expands the
carbocupration of alkynes initiated by Professor Jean
Normant some 45 years ago.
(E)-2-Dimethylphenylsilyl-2-phenyl-1-(N-phenylethyl-N-
tosyl)aminoethene (14c)
Prepared according to General Procedure 1 using 1.5 equiv of
PhMe2SiBpin and obtained in 74% yield (95 mg, 0.186 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.57 (d, J = 8.3 Hz, 2 H), 7.48 (dd, J = 7.3,
2.1 Hz, 2 H), 7.41–7.33 (m, 3 H), 7.28 (d, J = 8.1 Hz, 2 H), 7.16–7.10 (m,
6 H), 6.73–6.66 (m, 4 H), 6.60 (s, 1 H), 3.16–3.08 (m, 2 H), 2.51–2.44
(m, 5 H), 0.32 (s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 143.8, 139.4, 138.3, 137.6, 136.4, 134.2,
133.2, 131.5, 129.8, 129.4, 128.8, 128.4, 128.3, 128.3, 128.0, 127.2,
126.4, 126.4, 48.5, 34.9, 21.7, –2.7.
All solvents were reagent grade. THF was freshly distilled from sodi-
um/benzophenone under argon. CuF(PPh3)3·2MeOH,32 PhMe2SiBpin,31
Et3SiBpin,34 and ynamides20a,b were prepared according to literature
procedures. Reactions were magnetically stirred. Flash chromatogra-
phy was performed with silica gel 60 (particle size 35–70 μm) sup-
plied by SDS. Yields refer to chromatographically and spectroscopical-
ly pure compounds. 1H NMR spectra were recorded using an internal
deuterium lock at r.t. on a Bruker 300 MHz spectrometer. Internal ref-
erences of δH 7.26 was used for CDCl3. Data are presented as follows:
chemical shift (in ppm on the δ scale relative to δTMS = 0), multiplicity
(standard abbreviations), coupling constant (J/Hz), and integration.
13C NMR spectra were recorded at 75 MHz. Internal references of δC
77.16 was used for CDCl3. High-resolution mass spectra were ob-
tained on a Thermo Scientific QExactive spectrometer.
HRMS (ESI): m/z [M + H]+ calcd for C31H34O2N32S28Si: 512.2075; found:
512.2076.
(E)-2-Dimethylphenylsilyl-1-(oxazolidin-2-onyl)-2-phenylethene
(14d)
Prepared according to General Procedure 1 and obtained in 98% yield
(79 mg, 0.244 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.49–7.43 (m, 2 H), 7.37–7.31 (m, 3 H),
7.20–7.13 (m, 3 H), 6.93–6.85 (m, 2 H), 6.82 (s, 1 H), 4.07 (app t, J = 8.3
Hz, 2 H), 3.03 (app t, J = 8.0 Hz, 2 H), 0.36 (s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 156.9, 139.3, 137.4, 134.2, 129.4, 129.4,
129.3, 127.8, 127.7, 126.2, 121.3, 62.5, 44.8, –3.1.
Copper-Catalyzed Silylcupration of Ynamides; General Procedure 1
An oven-dried Schlenk flask was charged with the starting ynamide
12 (0.250 mmol), CuF(PPh3)3·2MeOH (4.7 mg, 0.005 mmol, 2 mol%),
and THF (1 mL). After complete dissolution, MeOH (15 μL, 0.370
mmol, 1.5 equiv) was added and the mixture was stirred for 1 addi-
tional min. Then, PhMe2SiBpin (75 μL, 0.275 mmol, 1.1 equiv) was
added dropwise and the reaction mixture was stirred at r.t. (typically,
16 h). The solution was then rapidly filtered over a short plug of silica
gel (eluted with PE/Et2O, 2:1) and the filtrate was concentrated. The
resulting residue was finally purified by column chromatography
over silica gel to give the desired β-silylenamide.
HRMS (APCI): m/z [M + H]+ calcd for C19H22NO228Si: 324.1414; found:
324.1414.
(E)-2-Dimethylphenylsilyl-2-phenyl-1-(pyrrolidin-2-onyl)ethene
(14e)
Prepared according to General Procedure 1 using 1.5 equiv of
PhMe2SiBpin and obtained in 75% yield (60 mg, 0.187 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.52–7.40 (m, 2 H), 7.39–7.28 (m, 3 H),
7.21–7.11 (m, 3 H), 7.06 (s, 1 H), 6.91–6.77 (m, 2 H), 2.88 (t, J = 7.1 Hz,
2 H), 2.32 (t, J = 8.1 Hz, 2 H), 1.76 (app quint, J = 7.6 Hz, 2 H), 0.35 (s, 6
H).
13C NMR (CDCl3, 75 MHz): δ = 175.4, 140.3, 137.8, 134.2, 129.3, 129.2,
129.2, 127.8, 127.6, 126.0, 122.0, 48.2, 30.5, 18.6, –2.9.
(E)-1-(N-Benzyl-N-tosyl)amino-2-dimethylphenylsilyl-2-phenyl-
ethene (14a)
Prepared according to General Procedure 1 and obtained in 98% yield
(122 mg, 0.245 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.61 (d, J = 8.2 Hz, 2 H), 7.34–7.15 (m,
10 H), 7.08–6.95 (m, 3 H), 6.86–6.80 (m, 2 H), 6.57 (s, 1 H), 6.38–6.31
(m, 2 H), 4.14 (s, 2 H), 2.46 (s, 3 H), 0.20 (s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 143.7, 139.1, 137.7, 136.6, 136.5, 134.1,
131.4, 130.5, 129.8, 129.2, 128.1, 128.0, 128.0, 127.8, 127.6, 127.2,
127.2, 126.3, 50.5, 21.7, –2.8.
HRMS (ESI): m/z [M + H]+ calcd for C20H24ON28Si: 322.1622; found:
322.1631.
(E)-1-(N-Benzyl-N-tosyl)amino-2-dimethylphenylsilyl-2-(naph-
thalene-2-yl)ethene (14f)
HRMS (ESI): m/z [M + H]+ calcd for C30H32NO232S28Si: 498.1917; found:
498.1912.
Prepared according to General Procedure 1 using 1.5 equiv of
PhMe2SiBpin and obtained in 98% yield (134 mg, 0.245 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.74–7.70 (m, 1 H), 7.64 (d, J = 8.3 Hz, 2
H), 7.50 (d, J = 8.4 Hz, 1 H), 7.41–7.33 (m, 6 H), 7.30–7.24 (m, 4 H),
7.20–7.09 (m, 3 H), 6.76 (d, J = 6.8 Hz, 2 H), 6.65 (s, 1 H), 6.63 (br s, 1
H), 6.54 (dd, J = 8.4, 1.7 Hz, 1 H), 4.09 (s, 2 H), 2.52 (s, 3 H), 0.22 (s, 6
H).
13C NMR (CDCl3, 75 MHz): δ = 143.8, 137.6, 136.8, 136.6, 136.4, 134.2,
133.1, 132.0, 131.7, 130.8, 129.9, 129.3, 128.1, 127.9, 127.8, 127.6,
127.6, 127.5, 127.3, 127.3, 126.8, 126.3, 125.9, 125.6, 50.7, 21.8, –2.7.
(E)-2-Dimethylphenylsilyl-2-phenyl-1-(N-phenyl-N-tosyl)amino-
ethene (14b)
Prepared according to General Procedure 1 and obtained in 92% yield
(111 mg, 0.229 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.53–7.47 (m, 2 H), 7.43–7.35 (m, 3 H),
7.31 (d, J = 8.3 Hz, 2 H), 7.19 (d, J = 8.2 Hz, 2 H), 6.95–6.80 (m, 7 H),
6.59–6.54 (m, 2 H), 6.46–6.39 (m, 2 H), 2.42 (s, 3 H), 0.29 (s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 143.9, 139.2, 138.7, 137.4, 135.0, 134.8,
134.3, 129.6, 129.5, 129.3, 128.8, 128.4, 128.2, 127.9, 127.8, 127.5,
127.2, 125.1, 21.7, –2.9.
HRMS (APCI): m/z [M + H]+ calcd for C34H34NO232S28Si: 548.2074;
found: 548.2074.
HRMS (ESI) m/z [M + H]+ calcd for C29H30NO232S28Si: 484.1761; found:
484.1765.
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(E)-1-(N-Benzyl-N-tosyl)amino-2-(2,6-dimethylphenyl)-2-dimeth-
ylphenylsilylethene (14g)
1H NMR (CDCl3, 300 MHz): δ = 7.62 (d, J = 8.1 Hz, 2 H), 7.35–7.19 (m,
12 H), 5.23 (s, 1 H), 4.13 (s, 2 H), 2.43 (s, 3 H), 2.21 (q, J = 7.6 Hz, 2 H),
0.51 (t, J = 7.6 Hz, 3 H), 0.28 (s, 6 H).
Prepared according to General Procedure
1 using 10 mol% of
13C NMR (CDCl3, 75 MHz): δ = 148.4, 143.6, 138.0, 135.8, 134.8, 134.0,
132.4, 129.7, 129.4, 129.1, 128.4, 127.9, 127.8 (2C), 54.7, 23.3, 21.7,
13.4, –2.2.
HRMS (ESI): m/z [M + H]+ calcd for C26H32NO232S28Si: 450.1918; found:
450.1919.
CuF(PPh3)3·2MeOH and obtained in 60% yield (79 mg, 0.150 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.52–7.42 (m, 4 H), 7.42–7.34 (m, 3 H),
7.21 (d, J = 8.0 Hz, 2 H), 7.16–7.10 (m, 3 H), 7.02 (s, 1 H), 6.93–6.86 (m,
1 H), 6.80–6.61 (m, 4 H), 4.21 (s, 2 H), 2.43 (s, 3 H), 1.38 (s, 6 H), 0.22
(s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 143.9, 139.1, 137.6, 137.2, 137.1, 136.0,
134.1, 131.7, 129.9, 129.3, 128.1, 128.0, 127.3, 127.1, 127.1, 126.6,
126.0, 119.5, 48.9, 21.8, 20.4, –1.7.
(E)-2-Dimethylphenylsilyl-1-(oxazolidin-2-onyl)-2-trimethylsilyl-
ethene (14l)
HRMS (APCI): m/z [M + H]+ calcd for C32H36NO232S28Si: 526.2231;
found: 526.2232.
Prepared according to General Procedure 1 and obtained in 16% yield
(13 mg, 0.041 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.58–7.53 (m, 2 H), 7.41–7.36 (m, 3 H),
6.34 (s, 1 H), 4.13 (app t, J = 8.3 Hz, 2 H), 3.35 (app t, J = 8.3 Hz, 2 H),
0.47 (s, 6 H), 0.15 (s, 9 H).
(E)-1-(N-Benzyl-N-tosyl)amino-2-(4-chlorophenyl)-2-dimethyl-
phenylsilylethene (14h)
13C NMR (CDCl3, 75 MHz): δ = 147.6, 134.2, 134.0, 129.6, 128.9, 128.2,
127.7, 61.9, 47.8, –0.6, –2.0.
Prepared according to General Procedure 1 and obtained in 98% yield
(130 mg, 0.244 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.60 (d, J = 8.3 Hz, 2 H), 7.38–7.16 (m,
10 H), 6.95 (d, J = 8.5 Hz, 2 H), 6.82 (d, J = 7.8 Hz, 2 H), 6.53 (s, 1 H),
6.25 (d, J = 8.5 Hz, 2 H), 4.15 (s, 2 H), 2.47 (s, 3 H), 0.21 (s, 6 H).
HRMS (ESI): m/z [M + H]+ calcd for C16H26NO232S28Si2: 320.1497;
found: 320.1496.
13C NMR (CDCl3, 75 MHz): δ = 152.4, 143.9, 137.5, 137.2, 136.3, 136.1,
134.1, 132.1, 132.0, 129.9, 129.4, 129.4, 128.2, 128.1, 128.0, 127.5,
127.3, 127.3, 51.0, 21.8, –2.9.
(E)-2-Dimethylphenylsilyl-1-(N-phenylpropyl-N-tosyl)amino-
ethene (14m)
Prepared according to General Procedure 1 using 4.0 equiv of MeOH
and obtained in 93% yield (105 mg, 0.233 mmol).
HRMS (ESI): m/z [M]+ calcd for C30H3135ClNO232S28Si: 532.1528; found:
1H NMR (CDCl3, 300 MHz): δ = 7.58 (dt, J = 8.4, 1.9 Hz, 2 H), 7.46–7.43
(m, 2 H), 7.37–7.33 (m, 3 H), 7.28–7.22 (m, 4 H), 7.20–7.11 (m, 3 H),
6.94 (d, J = 17.1 Hz, 1 H), 4.51 (d, J = 17.1 Hz, 1 H), 3.35 (t, J = 7.5 Hz, 2
H), 2.61 (t, J = 7.5 Hz, 2 H), 2.41 (s, 3 H), 1.89 (app quint, J = 7.5 Hz, 2
H), 0.33 (s, 6 H).
532.1532.
(E)-1-(N-Benzyl-N-tosyl)amino-2-dimethylphenylsilyl-2-(furan-2-
yl)ethene (14i)
Prepared according to General Procedure 1 and obtained in 87% yield
(106 mg, 0.217 mmol).
13C NMR (CDCl3, 75 MHz): δ = 143.8, 141.1, 139.0, 137.6, 136.4, 129.9,
1H NMR (CDCl3, 300 MHz): δ = 7.63 (d, J = 8.3 Hz, 2 H), 7.37–7.11 (m,
11 H), 6.91–6.86 (m, 2 H), 6.27–6.23 (m, 2 H), 5.88 (m, 1 H), 4.38 (s, 2
H), 2.43 (s, 3 H), 0.28 (s, 6 H).
129.1, 128.5, 127.9, 126.9, 126.1, 101.4, 43.9, 33.0, 28.5, 21.2, –1.9.
HRMS (ESI): m/z [M + H]+ calcd for C26H32NO232S28Si2: 450.1918;
found: 450.1917.
13C NMR (CDCl3, 75 MHz): δ = 151.3, 143.8, 141.4, 137.5, 136.3, 135.9,
134.1, 132.4, 129.7, 129.2, 128.3, 128.1, 127.8, 127.5, 127.4, 120.6,
111.2, 110.0, 50.7, 21.7, –2.4.
(E)-1-(N-Benzyl-N-tosyl)amino-2-phenyl-2-triethylsilylethene
(14a′)
HRMS (ESI): m/z [M + H]+ calcd for C28H30NO332S28Si: 488.1710; found:
488.1709.
Prepared according to General Procedure 1 using 1.5 equiv of
Et3SiBpin and obtained in 56% yield (67 mg, 0.140 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.70 (d, J = 8.1 Hz, 2 H), 7.35 (d, J = 8.1
Hz, 2 H), 7.20–7.15 (m, 3 H), 7.11–7.01 (m, 3 H), 6.92–6.86 (m, 2 H),
6.47 (s, 1 H), 6.35 (d, J = 7.9 Hz, 2 H), 4.10 (s, 2 H), 2.49 (s, 3 H), 0.76 (t,
J = 7.8 Hz, 9 H), 0.45 (q, J = 8.2 Hz, 6 H).
(E,E)-1-(N-Benzyl-N-tosyl)amino-2-dimethylphenylsilyl-4-phenyl-
butadiene (14j)
Prepared according to General Procedure 1 and obtained in 85% yield
(111 mg, 0.212 mmol).
13C NMR (CDCl3, 75 MHz): δ = 143.7, 139.8, 136.8, 136.5, 130.6, 130.4,
1H NMR (CDCl3, 300 MHz): δ = 7.67 (d, J = 8.3 Hz, 2 H), 7.37–7.13 (m,
15 H), 7.06–7.01 (m, 2 H), 6.88 (dd, J = 16.6, 0.9 Hz, 1 H), 6.18 (d, J =
16.6 Hz, 1 H), 5.80 (s, 1 H), 4.48 (s, 2 H), 2.40 (s, 3 H), 0.36 (s, 6 H).
129.8, 128.1, 128.0, 127.7, 127.6, 127.3, 127.2, 126.1, 50.6, 14.2, 7.1,
2.9.
ESIMS: m/z = 478.2.
13C NMR (CDCl3, 75 MHz): δ = 143.9, 137.8, 137.5, 136.2, 135.6, 135.3,
134.4, 134.0, 133.3, 129.8, 129.3, 128.6, 128.5 (2 C), 128.0, 127.7,
127.6 (2 C), 126.5, 126.5, 54.2, 21.7, –1.8.
(E)-1-(Oxazolidin-2-onyl)-2-phenyl-2-triethylsilylethene (14d′)
Prepared according to General Procedure 1 using 1.5 equiv of
Et3SiBpin and obtained in 61% yield (46 mg, 0.152 mmol).
HRMS (ESI): m/z [M+ H]+ calcd for C32H34NO232S28Si: 524.2074; found:
1H NMR (CDCl3, 300 MHz): δ = 7.31–7.14 (m, 3 H), 7.07–6.93 (m, 2 H),
6.72 (s, 1 H), 4.10 (app t, J = 8.3 Hz, 2 H), 3.04 (app t, J = 8.0 Hz, 2 H),
0.92 (t, J = 7.8 Hz, 9 H), 0.58 (q, J = 7.8 Hz, 6 H).
524.2076.
(E)-1-(N-Benzyl-N-tosyl)amino-2-dimethylphenylsilylbut-1-ene
(14k)
13C NMR (CDCl3, 75 MHz): δ = 157.0, 140.2, 129.1, 129.0, 127.8, 126.1,
Prepared according to General Procedure 1 using 1.5 equiv of
PhMe2SiBpin and obtained in 75% yield (84 mg, 0.187 mmol).
119.8, 77.6, 77.2, 76.4, 62.5, 45.0, 7.4, 2.9.
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HRMS (ESI): m/z [M + H]+ calcd for C17H26NO228Si: 304.1727; found:
HRMS (APCI): m/z [M + H]+ calcd for C24H25O228Si: 373.1618; found:
304.1729.
373.1614.
Copper-Catalyzed Silylcupration of Propiolates; General Proce-
dure 2
Methyl (E)-3-Dimethylphenylsilyl-3-(4-methoxyphenyl)acrylate
(16e)
An oven-dried Schlenk flask is charged with the starting propiolate
15 (0.250 mmol), CuF(PPh3)3·2MeOH (4.7 mg, 0.005 mmol, 2 mol%),
and THF (1 mL). After complete dissolution, MeOH (50 μL, 1.25 mmol,
4.0 equiv) was added and the mixture was stirred for 1 additional
min. Then, PhMe2SiBpin (75 μL, 0.275 mmol, 1.1 equiv) was added
dropwise and the reaction mixture was stirred at r.t. (typically 16 h).
The solution was then rapidly filtered over a short plug of silica gel
(eluted with PE/Et2O, 2:1) and the filtrate was concentrated. The re-
sulting residue was finally purified by column chromatography over
silica gel to give the desired β-silylacrylate.
Prepared according to General Procedure 2 and obtained in 98% yield
(80 mg, 0.245 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.50–7.45 (m, 2 H), 7.40–7.33 (m, 3 H),
6.82–6.75 (m, 4 H), 6.21 (s, 1 H), 3.78 (s, 3 H), 3.53 (s, 3 H), 0.37 (s, 6
H).
13C NMR (CDCl3, 75 MHz): δ = 165.8, 161.8, 158.2, 136.0, 134.3, 133.1,
129.7, 128.9, 128.1, 127.4, 113.4, 55.2, 51.3, –3.4.
HRMS (APCI): m/z [M + H]+ calcd for C19H23O328Si: 327.1411; found:
327.1412.
Methyl (E)-3-Dimethylphenylsilylhept-2-enoate (16f)
Methyl (E)-3-Dimethylphenylsilyl-3-phenylacrylate (16a)
Prepared according to General Procedure 2 and obtained in 85% yield
(59 mg, 0.213 mmol).
Prepared according to General Procedure 2 and obtained in 98% yield
(73 mg, 0.245 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.53–7.47 (m, 2 H), 7.39–7.32 (m, 3 H),
6.07 (s, 1 H), 3.69 (s, 3 H), 2.64 (dd, J = 8.4, 6.4 Hz, 2 H), 1.32–1.23 (m,
4 H), 0.86–0.79 (m, 3 H), 0.42 (s, 6 H).
1H NMR (CDCl3, 300 MHz): δ = 7.55–7.43 (m, 2 H), 7.43–7.30 (m, 3 H),
7.30–7.11 (m, 3 H), 6.97–6.70 (m, 2 H), 6.21 (s, 1 H), 3.49 (s, 3 H), 0.37
(s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 165.8, 165.3, 136.7, 134.1, 129.5, 128.0,
13C NMR (CDCl3, 75 MHz): δ = 165.7, 162.4, 141.2, 135.8, 134.4, 129.8,
127.5, 51.0, 31.9, 31.5, 23.3, 13.9, –3.1.
128.9, 128.1, 128.0, 126.4, 126.1, 51.3, –3.5.
HRMS (ESI): m/z [M + H]+ calcd for C16H25O228Si: 277.1618; found:
HRMS (ESI): m/z [M + H]+ calcd for C18H21O228Si: 297.1305; found:
277.1618.
297.1300.
Methyl (E)-3-Dimethylphenylsilylnon-2-enoate (16g)
Ethyl (E)-3-Dimethylphenylsilyl-3-phenylacrylate (16b)
Prepared according to General Procedure 2 and obtained in 92% yield
(70 mg, 0.230 mmol).
Prepared according to General Procedure 2 and obtained in 99% yield
(77 mg, 0.248 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.52–7.46 (m, 2 H), 7.39–7.32 (m, 3 H),
6.06 (s, 1 H), 3.69 (s, 3 H), 2.62 (t, J = 7.4 Hz, 2 H), 1.29–1.15 (m, 8 H),
0.84 (t, J = 6.9 Hz, 3 H), 0.42 (s, 6 H).
1H NMR (CDCl3, 300 MHz): δ = 7.54–7.49 (m, 2 H), 7.43–7.36 (m, 3 H),
7.31–7.13 (m, 3 H), 6.90–6.84 (m, 2 H), 6.25 (s, 1 H), 3.97 (q, J = 7.1 Hz,
2 H), 1.02 (t, J = 7.1 Hz, 3 H), 0.42 (s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 165.8, 165.4, 136.7, 134.2, 129.5, 128.0,
13C NMR (CDCl3, 75 MHz): δ = 165.4, 161.3, 141.3, 135.7, 134.3, 129.7,
127.5, 51.1, 31.8, 31.6, 29.9, 29.8, 22.7, 14.2, –3.1.
129.6, 128.0, 127.8, 126.1, 126.1, 60.1, 13.9, –3.6.
HRMS (APCI): m/z [M + H]+ calcd for C18H29O228Si: 305.1931; found:
HRMS (APCI): m/z [M + H]+ calcd for C19H23O228Si: 311.1461; found:
305.1932.
311.1456.
Methyl (E)-4-Benzyloxy-3-dimethylphenylsilylbut-2-enoate (16h)
tert-Butyl (E)-3-Dimethylphenylsilyl-3-phenylacrylate (16c)
Prepared according to General Procedure 2 and obtained in 95% yield
(81 mg, 0.238 mmol).
Prepared according to General Procedure 2 and obtained in 92% yield
(78 mg, 0.230 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.51–7.44 (m, 2 H), 7.38–7.21 (m, 6 H),
7.18–7.12 (m, 2 H), 5.96 (t, J = 2.3 Hz, 1 H), 4.76 (d, J = 2.3 Hz, 2 H),
4.39 (s, 2 H), 3.66 (s, 3 H), 0.46 (s, 6 H).
1H NMR (CDCl3, 300 MHz): δ = 7.49–7.44 (m, 2 H), 7.39–7.33 (m, 3 H),
7.25–7.14 (m, 3 H), 6.86–6.78 (m, 2 H), 6.13 (s, 1 H), 1.14 (s, 9 H), 0.36
(s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 165.9, 164.0, 138.2, 137.6, 134.3, 129.2,
13C NMR (CDCl3, 75 MHz): δ = 165.4, 158.2, 141.6, 136.0, 134.4, 131.9,
128.3, 127.9 (2 C), 127.5, 126.6, 73.2, 72.3, 51.3, –1.9.
129.6, 128.0, 127.7, 126.4, 125.9, 80.5, 27.7, –3.5.
HRMS (APCI): m/z [M + H]+ calcd for C20H25O328Si: 341.1567; found:
HRMS (APCI): m/z [M + H – t-Bu]+ calcd for C17H17O228Si: 283.1149;
341.1567.
found: 283.1147.
Methyl (E)-3-Dimethylphenylsilyl-4-(N-benzyl-N-tosylamino)but-
Benzyl (E)-3-Dimethylphenylsilyl-3-phenylacrylate (16d)
2-enoate (16i)
Prepared according to General Procedure 2 and obtained in 90% yield
(84 mg, 0.225 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.54–7.50 (m, 2 H), 7.48–7.37 (m, 3 H),
7.33–7.24 (m, 6 H), 7.15–7.09 (m, 2 H), 6.91–6.85 (m, 2 H), 6.32 (s, 1
H), 5.00 (s, 2 H), 0.43 (s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 165.2, 162.1, 141.1, 135.7, 135.6, 134.3,
129.7, 129.0, 128.4, 128.3, 128.1, 128.0, 127.9, 126.3, 126.1, 66.1, –3.6.
Prepared according to General Procedure 2 and obtained in 92% yield
(114 mg, 0.231 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.60 (d, J = 8.3 Hz, 2 H), 7.45–7.40 (m, 2
H), 7.38–7.29 (m, 3 H), 7.28–7.11 (m, 5 H), 7.09–6.96 (m, 2 H), 5.98 (s,
1 H), 4.56 (d, J = 1.1 Hz, 2 H), 4.10 (s, 2 H), 3.59 (s, 3 H), 2.41 (s, 3 H),
0.45 (s, 6 H).
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13C NMR (CDCl3, 75 MHz): δ = 165.6, 158.7, 143.3, 136.5, 136.2, 135.9,
134.2, 131.6, 129.6, 129.4, 129.3, 128.1, 127.9, 127.4 (2 C), 52.7, 51.2,
48.0, 21.5, –2.8.
HRMS (APCI): m/z [M + H]+ calcd for C27H32NO432S28Si: 494.1822;
found: 494.1816.
References
(1) Normant, J. F.; Bourgain, M. Tetrahedron Lett. 1971, 27, 2583.
(2) For reviews, see: (a) Normant, J. F.; Alexakis, A. Synthesis 1981,
841. (b) Lipshutz, B. H.; Sengupta, S. Org. React. 1992, 41, 135.
(c) Chemla, F.; Ferreira, F. In The Chemistry of Organocopper
Compounds; Rappoport, Z.; Marek, I., Eds.; Wiley: Chichester,
2009, 527–584. (d) Müller, D. S.; Marek, I. Chem. Soc. Rev. 2016,
46, in press; DOI: 10.1039/c5cs00897b.
Methyl (E)-3-Dimethylphenylsilyl-6-methoxycarbonyloxyhex-2-
enoate (16j)
Prepared according to General Procedure 2 and obtained in 99% yield
(83 mg, 0.247 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.51–7.46 (m, 2 H), 7.40–7.35 (m, 3 H),
6.11 (s, 1 H), 4.07 (t, J = 6.5 Hz, 2 H), 3.76 (s, 3 H), 3.69 (s, 3 H), 2.73–
2.65 (m, 2 H), 1.70–1.63 (m, 2 H), 0.44 (s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 165.6, 163.7, 156.0, 136.3, 134.2, 129.8,
128.6, 128.2, 68.2, 54.8, 51.3, 28.8, 27.8, –3.2.
(3) Murakami, K.; Yorimitsu, H. Beilstein J. Org. Chem. 2013, 9, 278.
(4) For selected references, see: (a) Piers, E.; Morton, H. E. J. Org.
Chem. 1980, 45, 4264. (b) Singer, R. D.; Hutzinger, M. W.;
Oehlschlager, A. C. J. Org. Chem. 1991, 56, 4933. (c) Barbero, A.;
Pulido, F. J. Chem. Soc. Rev. 2005, 34, 913. (d) Weickgenannt, A.;
Oestreich, M. Chem. Eur. J. 2010, 16, 402.
(5) For selected references, see: (a) Fleming, I.; Newton, T. W.;
Roessler, F. J. Chem. Soc., Perkin Trans. 1 1981, 2527. (b) Barbero,
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HRMS (APCI): m/z [M + H]+ calcd for C17H25O528Si: 337.1466; found:
337.1466.
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distinguish the carbocupration and the 1,4-addition since both
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Ethyl (E)-3-Dimethylphenylsilylacrylate (16k)
Prepared according to General Procedure 2 and obtained in 99% yield
(58 mg, 0.247 mmol).
1H NMR (CDCl3, 300 MHz): δ = 7.52–7.49 (m, 2 H), 7.39–7.36 (m, 3 H),
7.36 (d, J = 18.9 Hz, 1 H), 6.27 (d, J = 18.9 Hz, 1 H), 4.20 (q, J = 7.2 Hz, 2
H), 1.29 (t, J = 7.2 Hz, 3 H), 0.42 (s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 165.9, 147.5, 136.5, 135.5, 134.0, 129.6,
128.1, 60.7, 14.4, –3.0.
HRMS (APCI): m/z [M + H]+ calcd for C13H19O228Si: 235.1149; found:
235.1148.
Methyl (E)-3-Dimethylphenylsilyl-3-(pyridin-2-yl)acrylate (16l)
Prepared according to General Procedure 2 and obtained in 15% yield
(11 mg, 0.037 mmol) along with the previously reported methyl (Z)-
3-(pyridin-2-yl)-acrylate (17)36 (67%, 27 mg, 0.167 mmol) and methyl
3-(pyridin-2-yl) propanoate (18)37 (18%, 7 mg, 0.045 mmol).
1H NMR (CDCl3, 300 MHz): δ = 8.58–8.50 (m, 1 H), 7.62–7.54 (m, 3 H),
7.32–7.27 (m, 3 H), 7.18–7.07 (m, 2 H), 6.60 (s, 1 H), 3.50 (s, 3 H), 0.42
(s, 6 H).
13C NMR (CDCl3, 75 MHz): δ = 167.0, 155.7, 155.0, 149.0, 137.1, 136.4,
135.1, 133.8, 128.7, 127.6, 121.8, 121.4, 51.5, –0.9.
HRMS (APCI): m/z [M + H]+ calcd for C17H20O2N28Si: 298.1258; found:
298.1259.
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Acknowledgment
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This work was supported by the Université Catholique de Louvain, the
Université libre de Bruxelles (ULB), and the Université de Versailles
Saint-Quentin-en-Yvelines. S.V. and K.J. respectively acknowledge the
Fonds pour la formation àla Recherche dans l’Industrie et dans l’Agri-
culture (F.R.I.A.) and the Ministère de la Recherche for graduate fel-
lowships. We thank Mr. François Billard (UCL) and Mr. Morgan
Lecomte (ULB) for their precious assistance with the preparation of
this manuscript.
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Supporting Information
(20) For selected contributions to the chemistry of heterosubsituted
alkynes, see: (a) Coste, A.; Karthikeyan, G.; Couty, F.; Evano, G.
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0035-1562460.
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

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S. Vercruysse et al.
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I