Pd-catalyzed regio- and stereoselective addition of boronic acids to silylacetylenes: A stereodivergent assembly of β,β-disubstituted alkenylsilanes and alkenyl halides

Article abstract of DOI:10.1021/jo500925p

An efficient Pd-catalyzed addition of boronic acids to silylacetylenes is described, providing β,β-disubstituted (E)- or (Z)-alkenylsilanes in satisfactory yields with excellent regio- and stereoselectivity under mild reaction conditions. It represents the first highly regio- and stereoselective addition of boronic acids to aryl and alkenyl silylacetylenes. Moreover, the sequential Pd-catalyzed boron addition/N-halosuccinimide-mediated halodesilylation reaction results in a stereodivergent approach to β,β-disubstituted alkenyl halides, which can serve as versatile synthetic intermediates for the stereodivergent assembly of (E)- and (Z)-trisubstituted alkenes via transition-metal-catalyzed cross-coupling reactions.

Full text of DOI:10.1021/jo500925p

Article
pubs.acs.org/joc
Pd-Catalyzed Regio- and Stereoselective Addition of Boronic Acids to
Silylacetylenes: A Stereodivergent Assembly of β,β-Disubstituted
Alkenylsilanes and Alkenyl Halides
Wei Kong, Chao Che, Jialin Wu, Liai Ma, and Gangguo Zhu*
Department of Chemistry, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, China
S
* Supporting Information
ABSTRACT: An efficient Pd-catalyzed addition of boronic acids to
silylacetylenes is described, providing β,β-disubstituted (E)- or (Z)-
alkenylsilanes in satisfactory yields with excellent regio- and stereoselectivity
under mild reaction conditions. It represents the first highly regio- and
stereoselective addition of boronic acids to aryl and alkenyl silylacetylenes.
Moreover, the sequential Pd-catalyzed boron addition/N-halosuccinimide-
mediated halodesilylation reaction results in a stereodivergent approach to
β,β-disubstituted alkenyl halides, which can serve as versatile synthetic
intermediates for the stereodivergent assembly of (E)- and (Z)-
trisubstituted alkenes via transition-metal-catalyzed cross-coupling reactions.
of organoboron compounds to aryl silylacetylenes constitutes
an unmet goal. Recently, regio- and stereoselective hydro-
arylation of ynol ethers5 and ynamides6 has been realized in our
group, furnishing stereodefined heteroatom-substituted olefins
in good yields. As part of our ongoing studies in this field, we
herein describe a Pd-catalyzed regio- and stereoselective
addition of boronic acids to silylacetylenes that results in the
stereodivergent formation of β,β-disubstituted alkenylsilanes8 in
good yields with excellent regio- and stereoselectivity. It
constitutes the first regio- and stereoselective hydroarylation
or hydroalkenylation of aryl and alkenyl silylacetylenes with
boronic acids. Meanwhile, an operationally simple and
stereodivergent method for the assembly of β,β-disubstituted
(Z)- and (E)-alkenyl halides9 via a sequential boron addition/
N-halosuccinimide-mediated halodesilylation reaction has been
developed, thus providing a stereodivergent and expeditous
approach to stereodefined trisubstituted (Z)- and (E)-alkenes
by the cross-coupling strategy.
INTRODUCTION
■
Since the pioneering work of Hayashi,1 transition-metal-
catalyzed addition of boronic acids to alkynes has emerged as
a powerful tool for the elaboration of di- or trisubstituted
alkenes, which are versatile structural units in organic
chemistry.2,3 In this respect, control of the regioselectivity is
an essential issue for the design and development of
synthetically useful alkyne hydroarylation reactions. To date,
the utilization of strong electron-withdrawing or coordinating
groups stands out as an effective strategy to achieve the
regioselective boron addition reaction of unsymmetrical
acetylenes. Alternatively, substitution of the C−C triple
bonds with heteroatoms can sometimes solve the problem of
regiocontrol in alkyne hydroarylation with organoboron
reagents.4−7 Studies by Michelet and Genet
̂
indicated that a
stereospecific hydroarylation of alkyl trimethylsilylacetylenes
could be achieved with a Rh catalyst in a water/toluene biphasic
system; however, a 1:1 mixture of two inseparable regioisomers
was observed for aryl substrates under the same reaction
conditions (Scheme 1).4 Therefore, the stereospecific addition
RESULTS AND DISCUSSION
■
We began our investigations by examining the reaction between
2-triethylsilyl-1-phenylacetylene (1a) and 4-tolylboronic acid
(2a) utilizing Pd(OAc)2 as the catalyst. As shown in Table 1,
we found promising results when 5 mol % Pd(OAc)2 and 10
mol % PCy3 were used in dioxane at room temperature under a
N2 atmosphere for 11 h, which provided β,β-disubstituted
alkenylsilane 3 in 68% yield with excellent stereoselectivity (E/
Z > 96:4) (Table 1, entry 1). Encouraged by this result, we
further examined other solvents for this reaction. Replacing
dioxane with EtOH, DMF, toluene, or MeCN significantly
Scheme 1. Summary of This Work
Received: April 26, 2014
Published: June 5, 2014
© 2014 American Chemical Society
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a
Table 1. Optimization of the Reaction Conditions
Table 2. Scope of Addition of Boronic Acids to
a b
,
Silylacetylenes
b
c
entry
ligand
PCy3
solvent
E/Z
yield (%)
1
2
3
4
5
6
dioxane
EtOH
DMF
toluene
CH3CN
THF
>96:4
>98:2
−
68
PCy3
26
PCy3
trace
trace
trace
78
PCy3
−
−
PCy3
PCy3
>97:3
d
7
PCy3
THF
−
−
trace
trace
10
8
9
PPh3
THF
P(4-tol)3
P(3-tol)3
P(t-Bu)3
Xphos
dppe
THF
>98:2
10
11
12
13
THF
−
−
−
−
trace
7
THF
THF
trace
trace
88
THF
e
14
ef
,
PCy3
THF
>97:3
15
PCy3
THF
62:38
90
a
Reaction conditions: 1a (0.25 mmol), 2a (0.50 mmol), Pd(OAc)2 (5
mol %), and ligand (10 mol %) under N2 at rt for 11 h, unless
b
c
d
otherwise specified. Determined by GC. Isolated yields. Under an
e
f
air atmosphere. 2a (0.75 mmol) was used. 28 h.
diminished the reaction yield, while using THF as the solvent
led to a better result (Table 1, entries 2−6). It should be noted
that running the reaction under an atmosphere of air resulted in
almost no product formation (Table 1, entry 7), indicating that
a Pd(0) species might be involved in this transformation. A
brief scan over ligands demonstrated that PCy3 served as the
privileged ligand (Table 1, entries 8−13). The utilization of 3
equiv instead of 2 equiv of 2a resulted in full conversion of 1a,
generating (E)-3 in 88% isolated yield with >97% E selectivity
(Table 1, entry 14). Interestingly, increasing the reaction time
from 11 to 28 h dramatically decreased the stereoselectivity
(Table 1, entry 15),10 implying that (E)-3 might be the
kinetically controlled product.
Next, we carried out a substrate scope study on boronic acids
(Table 2). In particular, the steric effect of the boronic acid had
little influence on the hydroarylation reaction when there was
substitution at the ortho position of the aryl ring of 2 [Table 2,
(E)-3 and (E)-4]. The reaction was insensitive to changes in
the electronic nature of the boronic acid employed, delivering
the desired β,β-disubstituted (E)-alkenylsilanes in satisfactory
yields with excellent stereoselectivity [Table 2, (E)-5 through
(E)-9]. Pleasingly, the reaction also applied well to alkenylbor-
onic acids, as demonstrated by the production of 1,3-
dienylsilanes (Z)-13 and (Z)-14. Heteroarylboronic acid 2m
also participated well in this transformation, giving (E)-15 in
91% yield.
The scope of this reaction with regard to silylacetylenes was
subsequently investigated. For example, the addition of
PhB(OH)2 (2h) to silylacetylenes 1b and 1c provided (Z)-3
and (Z)-5 in yields of 88 and 80%, respectively. Hence, it
enables a stereodivergent protocol for the construction of β,β-
disubstituted (E)- and (Z)-alkenylsilanes by a simple choice of
different types of starting materials. A variety of functional
groups such as F, CO2Et, Ac, and alkenyl groups were perfectly
tolerated under the optimized reaction conditions [Table 2,
(Z)-7 through (Z)-9 and (E)-14]. The presence of sulfur-
containing heterocycles did not interfere with the hydro-
a
Reaction conditions: 1 (0.25 mmol), 2 (0.75 mmol), Pd(OAc)2 (5
mol %), and PCy3 (10 mol %) under N2 at 27 °C for 11 h, unless
otherwise noted. Except where noted otherwise, the desired products
were obtained with >95:5 stereoselectivity and no regioisomers were
b
c
d
e
detected. Isolated yields are shown. 22 h. 2 equiv of 2g was used. 6
h. A mixture of three isomers (61:34:5) was obtained.
f
phenylation reaction [Table 2, (Z)-15].11 Furthermore,
triethylsilylacetylene (1i) was also good for this reaction, giving
(E)-1612 in 84% yield. Treatment of 2-trimethylsilyl-1-phenyl-
acetylene (1j) with 2a under the standard conditions for 6 h
furnished (E)-17 in 86% yield. Interestingly, the hydro-
phenylation of 1-hexynyltriethylsilane (1k) formed the
expected β,β-disubstituted alkenylsilane (E)-18 with excellent
regio- and stereoselectivity after 22 h, while the reaction of 1-
hexynyltrimethylsilane (1l) enabled the formation of 19 as a
mixture of three isomers under the reaction conditions for 6 h.
These results indicated that the steric hindrance of silyl groups
could improve the regioselectivity of carbopalladation of
alkynes.13 The regio- and stereochemistry of this Pd-catalyzed
boron addition reaction was determined by NOE analysis (see
the Supporting Information).
On the basis of the above results and previous reports,2 a
plausible mechanism for this Pd-catalyzed regio- and stereo-
selective addition of boronic acids to silylacetylenes is proposed
in Scheme 2. Palladium intermediate A, generated by the
oxidative addition of Pd(0) species with the boronic acid (2),5a
reacts with 1 to form species B regio- and stereoselectively,
since the silyl group can stabilize the adjacent C−Pd bond in
the carbopalladation step.14 Then hydrolysis of the Pd−B bond
of B and subsequent reductive elimination produces the β,β-
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procedure gave rise to 1,3-dienyl iodide (E)-26 in 70% yield
with excellent regio- and stereoselectivity, while hydro-
alkenylation of 1j with 2l and subsequent iododesilylation
produced (Z)-26 with moderate stereoselectivity (Z/E =
74:26), probably because of the reduced thermodynamic
stability. In contrast, the one-pot process was not suitable for
the formation of alkenyl bromides, but fortunately, a two-step
procedure was found to be successful, leading to (E)- and (Z)-
28 in high yields with excellent stereoselectivity using NBS as
the halogenation reagent.
Scheme 2. A Possible Mechanism
Finally, the synthetic usefulness of this reaction was further
exemplified by the stereodivergent access to trisubstituted
alkenes that it provides. For example, treatment of (E)-20 with
1.2 equiv of 2c, 5 mol % Pd(OAc)2, 10 mol % PPh3, and 1.5
equiv of Cs2CO3 in dioxane at 60 °C overnight gave (E)-2916
in 83% yield upon isolation (eq 1), while the Suzuki−Miyaura
coupling17 of (Z)-20 provided (Z)-2916 in high yield (eq 2).
Thus, both trisubstituted (E)- and (Z)-olefins can be
synthesized by this protocol.
disubstituted alkenylsilane with regeneration of the Pd(0)
species. Of course, the hydropalladation mechanism2a cannot
be ruled out at the current stage.
On the other hand, stereodefined β,β-disubstituted alkenyl
halides are versatile building blocks in organic synthesis that can
act as convenient precursors for the preparation of stereo-
defined trisubstituted alkenes via transition-metal-catalyzed
cross-coupling reactions. However, there are only a limited
number of methods for the regio- and stereoselective
construction of these motifs.9 With the current boron addition
reaction in hand, we decided to explore a mild as well as
efficient protocol for the synthesis of β,β-disubstituted alkenyl
halides.
After some trials, we found that Pd-catalyzed coupling of 2a
and 1a followed by stirring with 2 equiv of NIS15 in MeCN at
room temperature for 10 h generated β,β-diarylethenyl iodide
(E)-20 in 80% yield based on 1a, whereas the sequential
hydrophenylation/iododesilylation process from 1b produced
(Z)-20 in 83% yield (Table 3). Thus, this approach offers a
stereodivergent and one-pot route to β,β-disubstituted vinylic
halides. The structure of (E)-25 was determined by X-ray
crystallography. Interestingly, subjecting 1g to the one-pot
CONCLUSION
■
We have developed a simple catalytic system to achieve regio-
and stereoselective boron addition of silylacetylenes with the
readily available Pd(OAc)2 catalyst under mild reaction
conditions. Notably, it represents the first highly regio- and
stereoselective addition of boronic acids to aryl and alkyl
silylacetylenes. A variety of β,β-disubstituted (E)- or (Z)-
alkenylsilanes can be successfully assembled in satisfactory
yields with excellent regio- and stereoselectivity. Moreover, a
stereodivergent approach to β,β-disubstituted alkenyl halides
has been realized via the Pd-catalyzed boron addition and
subsequent halodesilylation reaction with NIS or NBS.
Ultimately, this provides an effective and stereodivergent
route to trisubstituted (E)- and (Z)-alkenes via the Suzuki−
Miyaura coupling of β,β-disubstituted alkenyl halides thus
obtained, and therefore, we believe that it will be useful for the
construction of complex molecules.
Table 3. Stereodivergent Synthesis of β,β-Disubstituted
a b
,
Alkenyl Halides
EXPERIMENTAL SECTION
■
General. Unless otherwise noted, materials obtained from
commercial suppliers were used directly without further purification.
Toluene, THF, and dioxane were distilled from sodium prior to use.
1H, 13C, and 19F NMR spectra were measured on a 600 MHz NMR
spectrometer using CDCl3 as the solvent with tetramethylsilane
(TMS) as the internal standard. Chemical shifts (δ) are given in parts
per million relative to TMS, and the coupling constants are given in
hertz. High-resolution mass spectrometry (HRMS) analyses were
carried out using a TOF MS instrument with an ESI source. Column
chromatography was performed using silica gel (300−400 mesh).
a
Reaction conditions: (i) 1 (0.25 mmol), 2 (0.75 mmol), Pd(OAc)2
(5 mol %), and PCy3 (10 mol %) under N2 at rt for 11 h; (ii) NIS
(0.50 mmol), MeCN, rt, 10 h. Si = SiEt3; NIS = N-iodosuccinimide;
b
c
NBS = N-bromosuccinimide. Isolated yields are shown. NIS (1.0
d
mmol) and 36 h were used. 2 h was used for iododesilylation
reaction. 1j was employed as the starting material and 1 h was used
for iododesilylation reaction. Z/E = 74:26. A two-step procedure was
used. E/Z = 91:9. Z/E = 91:9.
e
f
g
h
i
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General Procedure for the Pd-Catalyzed Regio- and Stereo-
selective Addition of Boronic Acids to Silylacetylenes. To a
mixture of 2a (102 mg, 0.75 mmol), Pd(OAc)2 (2.8 mg, 0.0125
mmol), and PCy3 (7.0 mg, 0.025 mmol) was added a solution of 1a
(54 mg, 0.25 mmol) in 1 mL of THF under a nitrogen atmosphere.
After 11 h of stirring at 27 °C, the reaction mixture was quenched with
water, extracted with EtOAc, washed with brine, dried over anhydrous
Na2SO4, and concentrated. Column chromatography on silica gel
using petroleum ether as the eluent gave 68 mg (88% yield) of (E)-3
7.94 (d, J = 8.4 Hz, 2H), 7.31−7.36 (m, 5H), 7.15−7.24 (m, 2H), 6.35
(s, 1H), 4.36 (q, J = 7.1 Hz, 2H), 1.37 (t, J = 7.1 Hz, 3H), 0.86 (t, J =
7.9 Hz, 9H), 0.38 (q, J = 7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ
166.4, 157.1, 147.7, 142.1, 129.5, 129.4, 129.4, 129.3, 127.9, 127.6,
127.1, 60.8, 14.3, 7.5, 4.3; HRMS (ESI) calcd for C23H31O2Si (M +
H)+ 367.2093, found 367.2083.
Compound (Z)-8. 81% yield (74 mg); colorless oil; Rf = 0.58
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
8.04 (d, J = 8.1 Hz, 2H), 7.21−7.32 (m, 7H), 6.31 (s, 1H), 4.40 (q, J =
7.1 Hz, 2H), 1.42 (t, J = 7.1 Hz, 3H), 0.86 (t, J = 7.9 Hz, 9H), 0.37 (q,
J = 7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ 166.5, 157.0, 147.6,
142.9, 129.5, 129.4, 129.1, 128.1, 127.8, 127.7, 127.1, 61.0, 14.3, 7.5,
4.4; HRMS (ESI) calcd for C23H31O2Si (M + H)+ 367.2093, found
367.2074.
1
as a colorless oil. Rf = 0.74 (petroleum ether); H NMR (600 MHz,
CDCl3) δ 7.30−7.35 (m, 3H), 7.15−7.22 (m, 4H), 7.05−7.10 (m,
2H), 6.20 (s, 1H), 2.32 (s, 3H), 0.85 (t, J = 7.9 Hz, 9H), 0.34 (q, J =
7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ 157.8, 143.0, 140.8,
137.4, 129.5, 128.7, 127.7, 127.3, 127.1, 125.5, 21.1, 7.5, 4.4; HRMS
(ESI) calcd for C21H29Si (M + H)+ 309.2039, found 309.2026.
Compound (Z)-3. 88% yield (68 mg); colorless oil; Rf = 0.72
Compound (E)-9. 75% yield (63 mg); colorless oil; Rf = 0.36
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.21−7.30 (m,
7.86 (d, J = 8.4 Hz, 2H), 7.33−7.38 (m, 5H), 7.15−7.22 (m, 2H), 6.37
(s, 1H), 2.57 (s, 3H), 0.86 (t, J = 7.9 Hz, 9H), 0.38 (q, J = 7.9 Hz,
6H); 13C NMR (151 MHz, CDCl3) δ 197.7, 157.0, 148.0, 142.1,
135.9, 129.9, 129.5, 128.2, 128.0, 127.7, 127.4, 26.7, 7.6, 4.4; HRMS
(ESI) calcd for C22H29OSi (M + H)+ 337.1988, found 337.1961.
Compound (Z)-9. 90% yield (76 mg); colorless oil; Rf = 0.36
5H), 7.07−7.14 (m, 4H), 6.20 (s, 1H), 2.37 (s, 3H), 0.86 (t, J = 7.9
Hz, 9H), 0.37 (q, J = 7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ
158.1, 143.9, 139.9, 137.0, 129.4, 128.4, 127.9, 127.5, 127.3, 126.3,
21.3, 7.6, 4.5; HRMS (ESI) calcd for C21H29Si (M + H)+ 309.2039,
found 309.2017.
1
Compound (E)-4. 90% yield (69 mg); colorless oil; Rf = 0.73
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.23−7.27 (m,
7.96 (d, J = 8.1 Hz, 2H), 7.32 (d, J = 8.0 Hz, 2H), 7.22−7.29 (m, 5H),
6.31 (s, 1H), 2.65 (s, 3H), 0.86 (t, J = 7.9 Hz, 9H), 0.37 (q, J = 7.9 Hz,
6H); 13C NMR (151 MHz, CDCl3) δ 197.9, 156.8, 148.0, 142.9,
136.0, 129.8, 128.1, 127.9, 127.9, 127.8, 127.1, 26.7, 7.5, 4.4; HRMS
(ESI) calcd for C22H29OSi (M + H)+ 337.1988, found 337.1961.
Compound 10. 96% yield (71 mg); colorless oil; Rf = 0.69
3H), 7.20−7.22 (m, 2H), 7.10−7.18 (m, 4H), 5.74 (s, 1H), 2.14 (s,
3H), 0.88 (t, J = 7.9 Hz, 9H), 0.47 (q, J = 7.9 Hz, 6H); 13C NMR (151
MHz, CDCl3) δ 159.5, 146.0, 143.3, 135.0, 130.2, 129.7, 129.5, 128.6,
127.6, 127.4, 127.1, 125.4, 20.6, 7.6, 4.8; HRMS (ESI) calcd for
C21H29Si (M + H)+ 309.2039, found 309.2036.
1
Compound (E)-5. 78% yield (63 mg); colorless oil; Rf = 0.60
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.30−7.40 (m,
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
3H), 7.15−7.30 (m, 7H), 6.24 (s, 1H), 0.86 (t, J = 7.9 Hz, 9H), 0.36
(q, J = 7.9 Hz, 6H); 13C NMR (CDCl3, 150 MHz): δ 158.0, 143.6,
142.8, 129.5, 128.0, 127.7, 127.5, 127.4, 127.2, 126.7, 7.5, 4.4; HRMS
(ESI) calcd for C20H27Si (M + H)+ 295.1882, found 295.1877.
Compound (E)-11. 85% yield (72 mg); colorless oil; Rf = 0.67
7.30−7.35 (m, 3H), 7.16−7.24 (m, 4H), 6.80 (d, J = 8.8 Hz, 2H), 6.13
(s, 1H), 3.79 (s, 3H), 0.85 (t, J = 7.9 Hz, 9H), 0.34 (q, J = 7.9 Hz,
6H); 13C NMR (151 MHz, CDCl3) δ 159.2, 157.4, 143.0, 136.3,
129.5, 128.4, 127.7, 127.3, 124.2, 113.3, 55.2, 7.5, 4.5; HRMS (ESI)
calcd for C21H29OSi (M + H)+ 325.1988, found 325.1968.
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
Compound (Z)-5. 80% yield (65 mg); colorless oil; Rf = 0.61
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
7.22−7.30 (m, 5H), 7.12 (d, J = 8.6 Hz, 2H), 6.86 (d, J = 8.6 Hz, 2H),
6.17 (s, 1H), 3.84 (s, 3H), 0.87 (t, J = 7.9 Hz, 9H), 0.39 (q, J = 7.9 Hz,
6H); 13C NMR (151 MHz, CDCl3) δ 159.0, 157.8, 144.0, 135.3,
130.6, 127.9, 127.5, 127.3, 126.3, 113.0, 55.2, 7.6, 4.5; HRMS (ESI)
calcd for C21H29OSi (M + H)+ 325.1988, found 325.1977.
7.27−7.38 (m, 3H), 7.16−7.20 (m, 2H), 6.82−6.85 (m, 1H), 6.67−
6.72 (m, 2H), 6.11 (s, 1H), 5.92 (s, 2H), 0.84 (t, J = 7.9 Hz, 9H), 0.34
(q, J = 7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ 157.4, 147.5,
147.2, 142.9, 138.3, 129.5, 127.7, 127.4, 125.0, 121.4, 107.6, 107.5,
101.0, 7.5, 4.4; HRMS (ESI) calcd for C21H27O2Si (M + H)+
339.1780, found 339.1771.
1
Compound (E)-12. 81% yield (70 mg); colorless oil; Rf = 0.72
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.69−7.79 (m,
Compound (E)-6. 76% yield (67 mg); colorless oil; Rf = 0.74
1
3H), 7.55−7.58 (m, 2H), 7.30−7.46 (m, 5H), 7.24−7.28 (m, 2H),
6.39 (s, 1H), 0.88 (t, J = 7.9 Hz, 9H), 0.40 (q, J = 7.9 Hz, 6H); 13C
NMR (151 MHz, CDCl3) δ 157.9, 142.8, 140.8, 133.1, 132.8, 129.6,
128.4, 127.8, 127.5, 127.5, 127.4, 127.4, 126.7, 126.0, 126.0, 125.2, 7.6,
4.5; HRMS (ESI) calcd for C24H29Si (M + H)+ 345.2039, found
345.2033.
(petroleum ether/CH2Cl2 = 1:1); H NMR (600 MHz, CDCl3) δ
7.31−7.37 (m, 3H), 7.19−7.23 (m, 2H), 6.87−6.89 (m, 1H), 6.74−
6.78 (m, 2H), 6.14 (s, 1H), 3.86 (s, 3H), 3.82 (s, 3H), 0.85 (t, J = 7.9
Hz, 9H), 0.35 (q, J = 7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ
157.5, 148.8, 148.3, 142.8, 136.5, 129.5, 127.7, 127.3, 124.5, 120.2,
110.3, 110.2, 55.9, 55.8, 7.6, 4.4; HRMS (ESI) calcd for C22H31O2Si
(M + H)+ 355.2093, found 355.2081.
Compound (Z)-13. 80% yield (57 mg); colorless oil; Rf = 0.70
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.26−7.35 (m,
Compound (E)-7. 93% yield (73 mg); colorless oil; Rf = 0.72
1
3H), 7.11−7.14 (m, 2H), 6.33 (d, J = 15.5 Hz, 1H), 5.64 (s, 1H),
5.13−5.22 (m, 1H), 2.02 (q, J = 7.1 Hz, 2H), 1.31−1.38 (m, 2H), 0.85
(t, J = 7.4 Hz, 3H), 0.80 (t, J = 7.9 Hz, 9H), 0.25 (q, J = 7.9 Hz, 6H);
13C NMR (151 MHz, CDCl3) δ 157.2, 141.4, 137.1, 134.4, 129.2,
127.8, 127.5, 126.9, 34.7, 22.3, 13.8, 7.5, 4.2; HRMS (ESI) calcd for
C19H31Si (M + H)+ 287.2195, found 287.2182.
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.30−7.39 (m,
3H), 7.22−7.27 (m, 2H), 7.14−7.22 (m, 2H), 6.92−6.96 (m, 2H),
6.17 (s, 1H), 0.85 (t, J = 7.9 Hz, 9H), 0.36 (q, J = 7.9 Hz, 6H); 19F
NMR (CDCl3, 565 MHz) δ −115.1; 13C NMR (151 MHz, CDCl3) δ
162.5 (d, J = 245.6 Hz), 157.0, 142.7, 139.9 (d, J = 3.2 Hz), 129.5,
128.9 (d, J = 7.9 Hz), 127.9, 127.6, 126.5, 114.8 (d, J = 21.2 Hz), 7.6,
4.4; HRMS (ESI) calcd for C20H26FSi (M + H)+ 313.1788, found
313.1782.
Compound (E)-14. 79% yield (63 mg); colorless oil; Rf = 0.71
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.29−7.38 (m,
Compound (Z)-7. 93% yield (73 mg); colorless oil; Rf = 0.70
9H), 7.20−7.25 (m, 2H), 6.41 (d, J = 16.0 Hz, 1H), 5.70 (s, 1H), 1.03
(t, J = 7.9 Hz, 9H), 0.78 (q, J = 7.9 Hz, 6H); 13C NMR (151 MHz,
CDCl3) δ 156.5, 143.6, 137.4, 133.1, 131.9, 130.0, 128.7, 128.5, 128.0,
127.7, 127.2, 126.5, 7.7, 5.1; HRMS (ESI) calcd for C22H29Si (M +
H)+ 321.2039, found 321.2030.
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.22−7.28 (m,
5H), 7.15−7.19 (m, 2H), 7.00−7.05 (m, 2H), 6.25 (s, 1H), 0.86 (t, J =
7.9 Hz, 9H), 0.37 (q, J = 7.9 Hz, 6H); 19F NMR (565 MHz, CDCl3) δ
−114.8; 13C NMR (151 MHz, CDCl3) δ 162.3 (d, J = 246.1 Hz),
156.9, 143.4, 138.8 (d, J = 3.5 Hz), 131.1 (d, J = 7.9 Hz), 128.0, 127.7,
127.2, 127.2, 114.7 (d, J = 21.3 Hz), 7.5, 4.4; HRMS (ESI) calcd for
C20H26FSi (M + H)+ 313.1788, found 313.1779.
Compound (Z)-14. 35% yield (28 mg); colorless oil; Rf = 0.70
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.32−7.38 (m,
5H), 7.24−7.29 (m, 2H), 7.17−7.22 (m, 3H), 7.07 (d, J = 15.9 Hz,
1H), 6.02 (d, J = 16.0 Hz, 1H), 5.94 (s, 1H), 0.83 (t, J = 7.9 Hz, 9H),
0.29 (q, J = 7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ 156.9, 140.7,
Compound (E)-8. 77% yield (70 mg); colorless oil; Rf = 0.60
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
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Article
137.2, 135.5, 132.0, 131.5, 129.3, 128.5, 127.7, 127.5, 127.2, 126.6, 7.5,
4.2; HRMS (ESI) calcd for C22H29Si (M + H)+ 321.2039, found
321.2051.
78.5; HRMS (ESI) calcd for C14H11FI (M + H)+ 324.9889, found
324.9882.
Compound (Z)-22. 84% yield (68 mg); colorless oil; Rf = 0.62
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.18−7.30 (m,
Compound (E)-15. 91% yield (68 mg); colorless oil; Rf = 0.69
7H), 7.07−7.12 (m, 2H), 6.92 (s, 1H); 19F NMR (565 MHz, CDCl3)
δ −113.3; 13C NMR (151 MHz, CDCl3) δ 162.3 (d, J = 247.5 Hz),
151.7, 141.0, 137.6 (d, J = 3.6 Hz), 131.3 (d, J = 8.2 Hz), 128.4, 128.2,
127.5, 115.3 (d, J = 21.6 Hz), 79.3; HRMS (ESI) calcd for C14H11FI
(M + H)+ 324.9889, found 324.9880.
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.31−7.37 (m,
3H), 7.26−7.29 (m, 2H), 7.17−7.19 (m, 1H), 6.86−6.89 (m, 1H),
6.55−6.57 (m, 1H), 6.22 (s, 1H), 0.84 (t, J = 7.9 Hz, 9H), 0.32 (q, J =
7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ 151.0, 149.1, 141.7,
129.2, 127.7, 127.7, 127.5, 126.0, 125.4, 124.9, 7.5, 4.2; HRMS (ESI)
calcd for C18H24SSi (M + H)+ 301.1446, found 301.1438.
Compound (E)-23. 71% yield (67 mg); colorless oil; Rf = 0.50
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
Compound (Z)-15. 95% yield (71 mg); colorless oil; Rf = 0.71
1
7.95 (d, J = 8.3 Hz, 2H), 7.33−7.47 (m, 3H), 7.22−7.30 (m, 4H), 7.09
(s, 1H), 4.36 (q, J = 7.1 Hz, 2H), 1.38 (t, J = 7.1 Hz, 3H); 13C NMR
(151 MHz, CDCl3) δ 166.2, 151.9, 145.1, 141.2, 129.8, 129.6, 129.3,
128.5, 128.2, 127.4, 81.4, 61.0, 14.3; HRMS (ESI) calcd for C17H16IO2
(M + H)+ 379.0195, found 379.0180.
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.26−7.36 (m,
6H), 6.95−7.03 (m, 2H), 6.26 (s, 1H), 0.90 (t, J = 7.9 Hz, 9H), 0.49
(q, J = 7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ 150.5, 144.1,
143.8, 130.5, 128.0, 127.9, 127.7, 127.2, 126.4, 125.7, 7.7, 4.4; HRMS
(ESI) calcd for C18H24SSi (M + H)+ 301.1446, found 301.1424.
Compound (E)-16.12 84% yield (46 mg); colorless oil; Rf = 0.70
Compound (Z)-23. 76% yield (72 mg); white solid, mp 37−39 °C;
1
1
Rf = 0.49 (petroleum ether/EtOAc = 20:1); H NMR (600 MHz,
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.41−7.47 (m,
CDCl3) δ 8.10 (d, J = 8.3 Hz, 2H), 7.34 (d, J = 8.3 Hz, 2H), 7.25−7.31
(m, 3H), 7.16−7.20 (m, 2H), 7.00 (s, 1H), 4.40 (q, J = 7.1 Hz, 2H),
1.41 (t, J = 7.1 Hz, 3H); 13C NMR (151 MHz, CDCl3) δ 166.2, 151.9,
146.3, 140.5, 130.0, 129.6, 129.5, 128.5, 128.3, 127.4, 79.6, 61.0, 14.3;
HRMS (ESI) calcd for C17H16IO2 (M + H)+ 379.0195, found
379.0198.
Compound (E)-24. 72% yield (62.5 mg); white solid, mp 87−89
°C; Rf = 0.30 (petroleum ether/EtOAc = 20:1); 1H NMR (600 MHz,
CDCl3) δ 7.86 (d, J = 8.4 Hz, 2H), 7.38−7.46 (m, 3H), 7.30 (d, J = 8.4
Hz, 2H), 7.24 (d, J = 6.9 Hz, 2H), 7.11 (s, 1H), 2.57 (s, 3H); 13C
NMR (151 MHz, CDCl3) δ 197.4, 151.7, 145.2, 141.1, 136.2, 129.3,
128.5, 128.4, 128.2, 127.6, 81.8, 26.6; HRMS (ESI) calcd for C16H14IO
(M + H)+ 349.0089, found 349.0102.
Compound (Z)-24. 81% yield (70.5 mg); white solid, mp 80−82
°C; Rf = 0.30 (petroleum ether/EtOAc = 20:1); 1H NMR (600 MHz,
CDCl3) δ 8.01 (d, J = 8.2 Hz, 2H), 7.37 (d, J = 8.2 Hz, 2H), 7.26−7.32
(m, 3H), 7.17−7.20 (m, 2H), 7.00 (s, 1H), 2.64 (s, 3H); 13C NMR
(151 MHz, CDCl3) δ 197.6, 151.8, 146.6, 140.4, 136.4, 129.7, 128.5,
128.4, 128.3, 127.4, 79.8, 26.6; HRMS (ESI) calcd for C16H14IO (M +
H)+ 349.0089, found 349.0097.
2H), 7.30−7.34 (m, 2H), 7.22−7.26 (m, 1H), 6.89 (d, J = 19.3 Hz,
1H), 6.43 (d, J = 19.3 Hz, 1H), 0.99 (t, J = 7.9 Hz, 9H), 0.66 (q, J =
7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ 144.8, 138.5, 128.5,
127.9, 126.3, 125.9, 7.4, 3.5.
Compound (E)-17. 86% yield (57 mg); colorless oil; Rf = 0.72
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.53−7.58 (m,
3H), 7.38−7.44 (m, 4H), 7.29 (d, J = 8.0 Hz, 2H), 6.48 (s, 1H), 2.54
(s, 3H), 0.10 (s, 9H); 13C NMR (151 MHz, CDCl3) δ 156.9, 142.7,
140.4, 137.4, 129.6, 128.7, 128.5, 127.8, 127.2, 127.1, 21.1, 0.0; HRMS
(ESI) calcd for C18H23Si (M + H)+ 267.1569, found 267.1557.
Compound (E)-18. 45% yield (31 mg); colorless oil; Rf = 0.76
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.36−7.39 (m,
2H), 7.28−7.33 (m, 2H), 7.22−7.26 (m, 1H), 5.63 (s, 1H), 2.52−2.63
(m, 2H), 1.26−1.34 (m, 4H), 0.99 (t, J = 7.9 Hz, 9H), 0.86 (t, J = 6.8
Hz, 3H), 0.68 (q, J = 7.9 Hz, 6H); 13C NMR (151 MHz, CDCl3) δ
158.9, 144.2, 128.1, 127.0, 126.2, 124.6, 35.3, 31.5, 23.0, 14.0, 7.7, 4.8;
HRMS (ESI) calcd for C18H31Si (M + H)+ 275.2195, found 275.2186.
Compound 19. 82% yield (48 mg); colorless oil; Rf = 0.75
1
(petroleum ether); H NMR (600 MHz, CDCl3) data for the major
isomer18 δ 7.03−7.21 (m, 5H), 5.54 (s, 1H), 2.38−2.44 (m, 2H),
1.11−1.15 (m, 4H), 0.66−0.70 (m, 3H), 0.00 (s, 9H).
Compound (E)-25. 82% yield (72 mg); white solid, mp 79−81 °C;
1
Rf = 0.56 (petroleum ether/EtOAc = 20:1); H NMR (600 MHz,
Compound (E)-20. 80% yield (64 mg); white solid, mp 49−51 °C;
CDCl3) δ 7.34−7.43 (m, 3H), 7.24 (d, J = 7.0 Hz, 2H), 6.80 (s, 1H),
6.66−6.73 (m, 3H), 5.93 (s, 2H); 13C NMR (151 MHz, CDCl3) δ
152.1, 147.6, 147.6, 141.9, 135.5, 129.4, 128.3, 128.0, 121.8, 108.0,
107.9, 101.2, 77.3; HRMS (ESI) calcd for C15H12IO2 (M + H)+
350.9882, found 350.9878.
Crystal data for (E)-25 (C15H11IO2, 350.14): monoclinic, space
group P21, a = 9.8867(5) Å, b = 5.6677(3) Å, c = 11.9084(6) Å, U =
660.06(6) Å3, Z = 2, T = 293(2) K, absorption coefficient 2.416 mm−1,
1
Rf = 0.51 (petroleum ether); H NMR (600 MHz, CDCl3) δ 7.34−
7.44 (m, 3H), 7.25 (d, J = 7.2 Hz, 2H), 7.05−7.13 (m, 4H), 6.87 (s,
1H), 2.31 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 152.5, 142.0,
138.4, 138.1, 129.4, 129.0, 128.3, 127.9, 127.4, 77.9, 21.2; HRMS
(ESI) calcd for C15H14I (M + H)+ 321.0140, found 321.0131.
Compound (Z)-20. 83% yield (66 mg); white solid, mp 34−36 °C;
1
Rf = 0.53 (petroleum ether); H NMR (600 MHz, CDCl3) δ 7.25−
7.29 (m, 3H), 7.19−7.23 (m, 4H), 7.14−7.18 (m, 2H), 6.88 (s, 1H),
2.39 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 152.6, 141.4, 138.8,
137.8, 129.3, 129.0, 128.3, 128.0, 127.6, 78.5, 21.4; HRMS (ESI) calcd
for C15H14I (M + H)+ 321.0140, found 321.0115.
reflections collected 3006, independent reflections 2300 (Rint
=
0.0290), refinement by full-matrix least-squares on F2, data/restraints/
parameters 2300/1/163, goodness of fit on F2 = 1.005, final R indices
[I > 2σ(I)] R1 = 0.0409, wR2 = 0.0776, R indices (all data) R1 =
0.0513, wR2 = 0.0851, largest diff. peak and hole 0.696 and −0.478 e·
Å−3. Crystallographic data for the structure of (E)-25 have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC 997720.
Compound (E)-21. 70% yield (59 mg); white solid, mp 69−71 °C;
1
Rf = 0.61 (petroleum ether/EtOAc = 20:1); H NMR (600 MHz,
CDCl3) δ 7.33−7.44 (m, 3H), 7.25 (d, J = 6.7 Hz, 2H), 7.14 (d, J = 8.8
Hz, 2H), 6.77−6.81 (m, 3H), 3.78 (s, 3H); 13C NMR (151 MHz,
CDCl3) δ 159.5, 152.1, 142.1, 133.9, 129.4, 128.8, 128.3, 127.9, 113.7,
76.6, 55.3; HRMS (ESI) calcd for C15H14IO (M + H)+ 337.0089,
found 337.0076.
Compound (Z)-25. 40% yield (35 mg); colorless oil; Rf = 0.55
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
7.21−7.29 (m, 5H), 6.72−6.77 (m, 2H), 6.71−6.79 (m, 2H), 6.00 (s,
2H); 13C NMR (151 MHz, CDCl3) δ 152.2, 147.5, 147.2, 141.3,
135.5, 128.3, 128.1, 127.6, 123.3, 110.0, 108.2, 101.2, 78.7; HRMS
(ESI) calcd for C15H12IO2 (M + H)+ 350.9882, found 350.9866.
Compound (E)-26. 70% yield (58 mg); colorless oil; Rf = 0.64
Compound (Z)-21.19 75% yield (63 mg); colorless oil; Rf = 0.63
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
7.26−7.30 (m, 3H), 7.18−7.24 (m, 4H), 6.93 (d, J = 8.7 Hz, 2H), 6.84
(s, 1H), 3.85 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 159.2, 152.2,
141.6, 133.9, 130.8, 128.3, 128.0, 127.7, 113.5, 78.2, 55.2.
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.42−7.45 (m,
Compound (E)-22. 85% yield (69 mg); colorless oil; Rf = 0.60
2H), 7.35−7.39 (m, 3H), 7.24−7.33 (m, 6H), 6.47 (d, J = 16.0 Hz,
1H), 6.36 (s, 1H); 13C NMR (151 MHz, CDCl3) δ 149.2, 139.9,
136.6, 136.5, 130.3, 128.8, 128.7, 128.3, 128.3, 128.0, 126.9, 82.1;
HRMS (ESI) calcd for C16H14I (M + H)+ 333.0140, found 333.0132.
Compound (Z)-26. 58% yield (48 mg); colorless oil; Z/E = 74:26;
Rf = 0.66 (petroleum ether); 1H NMR (600 MHz, CDCl3) data for the
1
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.32−7.45 (m,
3H), 7.23−7.27 (m, 2H), 7.16−7.23 (m, 2H), 6.93−6.98 (m, 2H),
6.88 (s, 1H); 19F NMR (565 MHz, CDCl3) δ −113.6; 13C NMR (151
MHz, CDCl3) δ 162.6 (d, J = 248.5 Hz), 151.7, 141.7, 137.4 (d, J = 3.3
Hz), 129.4, 129.2 (d, J = 8.2 Hz), 128.4, 128.1, 115.3 (d, J = 21.5 Hz),
5803
dx.doi.org/10.1021/jo500925p | J. Org. Chem. 2014, 79, 5799−5805

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Article
major isomer δ 7.48−7.18 (m, 10H), 7.06 (d, J = 15.8 Hz, 1H), 6.76
(s, 1H), 6.15 (d, J = 15.8 Hz, 1H); 13C NMR (151 MHz, CDCl3) data
for the major isomer δ 152.2, 139.8, 136.6, 132.7, 130.2, 129.1, 128.6,
128.5, 128.0, 127.9, 126.6, 84.2; HRMS (ESI) calcd for C16H14I (M +
H)+ 333.0140, found 333.0149.
AUTHOR INFORMATION
Corresponding Author
*E-mail: gangguo@zjnu.cn.
Notes
■
Compound (E)-27. 75% yield (59 mg); colorless oil; Rf = 0.66
(petroleum ether); H NMR (600 MHz, CDCl3) δ 7.40−7.45 (m,
The authors declare no competing financial interest.
1
3H), 7.27−7.30 (m, 2H), 7.22−7.25 (m, 1H), 6.97 (s, 1H), 6.90 (m,
1H), 6.66−6.70 (m, 1H); 13C NMR (151 MHz, CDCl3) δ 146.2,
144.6, 141.2, 129.1, 128.4, 128.3, 127.4, 126.5, 125.9, 77.5; HRMS
(ESI) calcd for C12H10IS (M + H)+ 312.9548, found 312.9533.
Compound (Z)-27. 86% yield (67 mg); colorless oil; Rf = 0.68
(petroleum ether); 1H NMR (600 MHz, CDCl3) δ 7.41 (d, J = 5.0 Hz,
1H), 7.27−7.35 (m, 5H), 7.14−7.18 (m, 1H), 7.04−7.10 (m, 1H),
6.76 (s, 1H); 13C NMR (151 MHz, CDCl3) δ 145.9, 142.3, 142.2,
129.7, 128.3, 128.3, 128.0, 126.6, 126.6, 78.2; HRMS (ESI) calcd for
C12H10IS (M + H)+ 312.9548, found 312.9546.
ACKNOWLEDGMENTS
■
We are grateful for the financial support from the Natural
Science Foundation of Zhejiang Province (LR12B02001), the
National Natural Science Foundation of China (21172199),
and the Open Research Fund of the Key Laboratory of the
Ministry of Education for Advanced Catalysis Materials
(ZJHX201310).
REFERENCES
■
Compound (E)-28.20 83% yield (57 mg); colorless oil; E/Z = 91:9;
(1) Hayashi, T.; Inoue, K.; Taniguchi, N.; Ogasawara, M. J. Am.
Chem. Soc. 2001, 123, 9918.
1
Rf = 0.58 (petroleum ether); H NMR (600 MHz, CDCl3) δ 7.27−
7.42 (m, 5H), 7.08−7.10 (m, 4H), 6.72 (s, 1H), 2.32 (s, 3H); 13C
NMR (151 MHz, CDCl3) δ 146.6, 139.2, 138.0, 137.9, 129.6, 129.1,
128.2, 127.9, 127.5, 104.3, 21.1.
(2) For selected reports, see: (a) Oh, C. H.; Jung, H. H.; Kim, K. S.;
Kim, N. Angew. Chem., Int. Ed. 2003, 42, 805. (b) Kim, N.; Kim, K. S.;
Gupta, A. K.; Oh, C. H. Chem. Commun. 2004, 618. (c) Zeng, H.; Hua,
R. J. Org. Chem. 2008, 73, 558. (d) Lautens, M.; Yoshida, M. Org. Lett.
2002, 4, 123. (e) Panteleev, J.; Huang, R. Y.; Lui, E. K. J.; Lautens, M.
Org. Lett. 2011, 13, 5314. (f) Zhang, W.; Liu, M.; Wu, H.; Ding, J.;
Cheng, J. Tetrahedron Lett. 2008, 49, 5214. (g) Arcadi, A.; Aschi, M.;
Chiarini, M.; Ferrara, G.; Marinelli, F. Adv. Synth. Catal. 2010, 352,
493. (h) Gourdet, B.; Smith, D. L.; Lam, H. W. Tetrahedron 2010, 66,
6026. (i) Shirakawa, E.; Takahashi, G.; Tsuchimoto, T.; Kawakami, Y.
Chem. Commun. 2001, 2688. (j) Lin, P.-S.; Jeganmohan, M.; Cheng,
C.-H. Chem.Eur. J. 2008, 14, 11296. (k) Yamamoto, Y.; Kirai, N.;
Harada, Y. Chem. Commun. 2008, 2010. For a recent review, see:
(l) Yamamoto, Y. Chem. Soc. Rev. 2014, 43, 1575.
(3) (a) Flynn, A. B.; Ogilvie, W. W. Chem. Rev. 2007, 107, 4698.
(b) Negishi, E.; Huang, Z.; Wang, G.; Mohan, S.; Wang, C.; Hattori,
H. Acc. Chem. Res. 2008, 41, 1474 and references therein.
(4) Genin, E.; Michelet, V.; Genet
689, 3820.
(5) (a) Bai, Y.; Yin, J.; Kong, W.; Mao, M.; Zhu, G. Chem. Commun.
2013, 49, 7650. (b) Cui, W.; Ying, J.; Zheng, R.; Cheng, C.; Bai, Y.;
Zhu, G. J. Org. Chem. 2014, 79, 3487.
(6) Yang, Y.; Wang, L.; Zhang, J.; Jin, Y.; Zhu, G. Chem. Commun.
2014, 50, 2347.
Compound (Z)-28. 79% yield (54 mg); colorless oil; Z/E = 91:9; Rf
1
= 0.56 (petroleum ether); H NMR (600 MHz, CDCl3) δ 7.26−7.30
(m, 3H), 7.18−7.23 (m, 6H), 6.72 (s, 1H), 2.39 (s, 3H); 13C NMR
(151 MHz, CDCl3) δ 146.7, 140.9, 137.8, 136.0, 129.6, 128.9, 128.4,
128.0, 127.7, 104.8, 21.4; HRMS (ESI) calcd for C15H14Br (M + H)+
273.0279, found 273.0281.
General Procedure for the Stereodivergent Synthesis of
Trisubstituted Alkenes via Suzuki−Miyaura Coupling. To a
mixture of 2c (46 mg, 0.3 mmol), Pd(OAc)2 (2.8 mg, 0.0125 mmol),
PPh3 (6.6 mg, 0.025 mmol), and Cs2CO3 (122 mg, 0.375 mmol) was
added a solution of (E)-20 (80 mg, 0.25 mmol) in 1 mL of dioxane
under a nitrogen atmosphere. After stirring at 60 °C overnight, the
reaction mixture was quenched with water, extracted with EtOAc,
washed with brine, dried over anhydrous Na2SO4, and concentrated.
Column chromatography (petroleum ether/EtOAc = 50:1) on silica
gel generated 62 mg (83% yield) of (E)-2916 as a colorless oil. Rf =
̂
, J.-P. J. Organomet. Chem. 2004,
1
0.36 (petroleum ether/EtOAc = 50:1); H NMR (600 MHz, CDCl3)
δ 7.28−7.35 (m, 3H), 7.16−7.23 (m, 4H), 7.09 (d, J = 8.0 Hz, 2H),
6.93 (d, J = 8.7 Hz, 2H), 6.88 (s, 1H), 6.65 (d, J = 8.8 Hz, 2H), 3.72
(s, 3H), 2.33 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 158.2, 140.7,
140.7, 140.4, 137.0, 130.7, 130.4, 130.1, 128.8, 128.6, 127.25, 127.16,
126.8, 113.3, 55.1, 21.1.
(7) (a) Ruan, J.; Li, X.; Saidi, O.; Xiao, J. J. Am. Chem. Soc. 2008, 130,
2424. (b) Ruan, J.; Xiao, J. Acc. Chem. Res. 2011, 44, 614. (c) Harada,
Y.; Nakanishi, J.; Fujihara, H.; Tobisu, M.; Fukumoto, Y.; Chatani, N.
J. Am. Chem. Soc. 2007, 129, 5766.
Compound (Z)-29.16 81% yield (56 mg); colorless oil; Rf = 0.65
1
(petroleum ether/EtOAc = 20:1); H NMR (600 MHz, CDCl3) δ
7.22−7.32 (m, 5H), 7.07−7.16 (m, 4H), 6.98 (d, J = 8.6 Hz, 2H), 6.87
(s, 1H), 6.67 (d, J = 8.7 Hz, 2H), 3.73 (s, 3H), 2.38 (s, 3H); 13C NMR
(151 MHz, CDCl3) δ 158.2, 143.8, 140.5, 137.5, 136.9, 130.7, 130.2,
130.1, 129.4, 128.1, 127.4, 127.4, 127.1, 113.3, 55.1, 21.3.
(8) For selected reports on the stereoselective synthesis of β,β-
disubstituted alkenylsilanes, see: (a) Wong, T.; Romero, M. A.; Fallis,
A. G. J. Org. Chem. 1994, 59, 5527. (b) Itami, K.; Mitsudo, K.; Kamei,
T.; Koike, T.; Nokami, T.; Yoshida, J. J. Am. Chem. Soc. 2000, 122,
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Yoshida, J. J. Am. Chem. Soc. 2001, 123, 11577. (d) Aronica, L. A.;
Raffa, P.; Caporusso, A. M.; Salvadori, P. J. Org. Chem. 2003, 68, 9292.
(e) Belema, M.; Nguyen, V. N.; Zusi, F. C. Tetrahedron Lett. 2004, 45,
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S.; Takagi, K. Org. Lett. 2009, 11, 3546.
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disubstituted alkenyl halides, see: (a) Van Horn, D. E.; Negishi, E. J.
Am. Chem. Soc. 1978, 100, 2252. (b) Wang, C.; Tobrman, T.; Xu, Z.;
Negishi, E. Org. Lett. 2009, 11, 4092. (c) Lahrache, H.; Robin, S.;
Rousseau, G. Tetrahedron Lett. 2005, 46, 1635. (d) Lee, S. I.; Hwang,
G.-S.; Ryu, D. H. Synlett 2007, 59. (e) Tsuji, H.; Fujimoto, T.; Endo,
K.; Nakamura, M.; Nakamura, E. Org. Lett. 2008, 10, 1219. (f) Wang,
Y.; Lam, H. W. J. Org. Chem. 2009, 74, 1353. (g) Tripoteau, F.;
Verdelet, T.; Hercouet, A.; Carreaux, F.; Carboni, B. Chem.Eur. J.
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T.-H. Tetrahedron 2012, 68, 4846.
1-(4-Methylphenyl)-1-phenylethene.21 To 1 mL of HOAc was
added 3 (66.5 mg, 0.25 mmol, E/Z = 58:42). After 10 h of stirring at
90 °C, the reaction mixture was quenched with water, extracted with
EtOAc, washed with brine, dried over Na2SO4, and concentrated.
Column chromatography on silica gel using petroleum ether as the
eluent gave 42 mg (87% yield) of the title compound as a colorless oil.
1
Rf = 0.62 (petroleum ether); H NMR (600 MHz, CDCl3) δ 7.28−
7.36 (m, 5H), 7.23 (d, J = 7.9 Hz, 2H), 7.14 (d, J = 7.9 Hz, 2H), 5.43
(s, 1H), 5.40 (s, 1H), 2.36 (s, 3H); 13C NMR (151 MHz, CDCl3) δ
149.8, 141.6, 138.6, 137.5, 128.8, 128.3, 128.12, 128.09, 127.6, 113.6,
21.2.
ASSOCIATED CONTENT
■
S
* Supporting Information
Spectroscopic data for products 3−29 and 1-(4-methylphenyl)-
1-phenylethene and X-ray data for (E)-25 (CIF). This material
is available free of charge via the Internet at http://pubs.acs.org.
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The Journal of Organic Chemistry
Article
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