Synthesis of multisubstituted enamides via pd-catalyzed chloroallylation of ynamides

Article abstract of DOI:10.1021/jo2015278

An atom-economic approach to the regio- and stereoselective assembly of highly substituted enamides is described via the Pd-catalyzed chloroallylation of ynamides at room temperature, which offers a simple and practical alternative to the stereodefined mu

Full text of DOI:10.1021/jo2015278

NOTE
pubs.acs.org/joc
Synthesis of Multisubstituted Enamides via Pd-Catalyzed
Chloroallylation of Ynamides
Zenghui Lu, Wei Kong, Zheliang Yuan, Xueyan Zhao, and Gangguo Zhu*
Department of Chemistry, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, China
S Supporting Information
b
ABSTRACT: An atom-economic approach to the regio- and stereo-
selective assembly of highly substituted enamides is described via the
Pd-catalyzed chloroallylation of ynamides at room temperature, which
offers a simple and practical alternative to the stereodefined multi-
substituted enamides.
Scheme 1. Pd-Catalyzed Haloallylation of Alkynes
he prevalence of enamides as substrates for asymmetric
hydrogenation, heterocycle syntheses and other synthetic
T
useful transformations renders this class of compounds one of
the most important building blocks in organic chemistry.1À3 In
addition, the enamide motif appears in a number of pharmaceu-
tically attractive natural products such as salicylihalamides, as
well as the antitumor macrolides lobatamides and oximidines.4
As such, it is of central importance to develop methods allowing
the effective synthesis of enamides. Besides the classical method
using the condensation of carbonyl compounds,5 various other
strategies including hydroamination of acetylenes,6 methylena-
tion of amides,7 and transition-metal-catalyzed amidation of
alkenyl halides8À12 have emerged in the past decades. But
nevertheless, the existing methods mainly afford disubstituted
enamides and often require rigorous conditions, such as the
exclusion of moisture and air, elevated temperature, and utiliza-
tion of excess strong base. As such, it is highly desirable to
develop general and practical methods for the stereoselective
preparation of sterically demanding enamides,13À16 such as
tertiary amides-containing tetrasubstituted enamides.
On the other hand, the halopalladation reaction proves to be a
powerful and attractive reaction in organic synthesis because
carbonÀcarbon and carbonÀhalide bonds are formed atom-
economically and simultaneously.17 However, the halopalladation
of acetylenes is still traditionally limited to the terminal alkynes or
activated alkynes,17À31 and the regio- as well as stereoselective
halopalladation of unsymmetrical internal alkynes has not been
achieved until our recent works on the halopalladation of
haloalkynes32À34 and aromatic ynol ethers35 (Scheme 1). Pursu-
ing our interest in this area, we envisioned that the haloallylation36
of ynamides37À40 would constitute a straightforward pathway for
the regio- and stereoselective synthesis of multisubstituted en-
amides. To this end, we hope to report such a new protocol
possessing the distinctive advantages in terms of the atom-
economy and practicability over the precedent procedures.5À16
Conditions for the Pd-catalyzed haloallylation of ynamides were
explored using aromatic ynamide 1a as the substrate. As a result,
treatment of 1a with 5 mol % of PdCl2 in THF at room temperature
for 4 h formed enamide 3aa in 30% yield (entry 1, Table 1).
The screening of the solvents using PdCl2 as the catalyst proved
that dichloroethane (DCE) was the most suitable solvent for this
reaction, producing enamide 3aa in 88% yield (entries 1À8,
Table 1). Furthermore, the reaction could be scaled up to 10 mmol
to give 3aa in 86% yield with 2.5 mol % of PdCl2 as the catalyst
(entry 8, Table 1). The stereochemistry of the enamide products
was determined by X-ray diffraction analysis of enamide 3ca.
Among the catalysts we tested, PdCl2 worked the best, although
other palladium sources such as Pd(OAc)2, Pd(PhCN)2Cl2, and
Pd(MeCN)2Cl2 also worked well (entries 9À11, Table 1). Finally,
we chose 5 mol % of PdCl2 as the catalyst, dichloroethane as the
solvent, and room temperature as the optimal reaction conditions
for the chloroallylation of ynamides.
With the optimized reaction conditions in hand, we then
probed the scope and limitations of this reaction using various
ynamides, and the results are summarized in Table 2. Pleasingly,
various functional groups including F, Cl, Br, and OMe groups
were well tolerated in this transformation (entries 1À9, Table 2).
For example, ynamide 1b resulted in the desired enamide 3ba in
84% yield under the standard conditions (entry 1, Table 2).
When ortho-substituted ynamide 1j was employed as a substrate,
the reaction formed enamide 3ja as two rotamers at a ratio of 5:1
Received: July 22, 2011
Published: September 19, 2011
r
2011 American Chemical Society
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|

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NOTE
Table 1. Screening of the Reaction Conditionsa
Table 3. Pd-Catalyzed Haloallylation of 1a with 2a
entry
PdX2
PdCl2
solvent
yieldb (%)
1
2
THF
30
PdCl2
DMSO
dioxane
toluene
HOAc
EtOAc
CH2Cl2
DCE
NR
76
3
PdCl2
4
PdCl2
79
5
PdCl2
23
6
PdCl2
83
7
PdCl2
80
88 (86)c
8
PdCl2
9
Pd(OAc)2
Pd(PhCN)2Cl2
Pd(MeCN)2Cl2
DCE
83
10
DCE
84
11
DCE
80
a Reaction conditions: 1a (0.25 mmol), 2a (0.50 mmol), and Pd cata-
lyst (0.013 mmol) in 1 mL of solvent at rt for 4 h. b Isolated yield.
c 10 mmol scale.
Table 2. Chloroallylation of Ynamides with 2aa
a Reaction conditions: 1 (0.25 mmol), 2 (0.37À0.50 mmol), and PdCl2
(0.013 mmol) in 1 mL of DCE at rt for 8 h. b Isolated yield. c The reaction
was performed at 50 °C. d 4E/4Z = 2/1.
in 70% yield (entry 9, Table 2). This was confirmed by variable
temperature NMR experiments and GCÀMS analysis. Beside
the aromatic ynamides, the reaction of aliphatic ynamide 1l also
proceeded to provide enamide 3la in 72% yield (entry 11,
Table 2). In addition, the effects of substituents on the nitrogen
atom of ynamides were also briefly investigated. For instance,
ynamides with an N-butyl group 1m and an N-phenyl group 1n
produced the corresponding enamides 3ma and 3na in respec-
tive yields of 71% and 85% (entries 12 and 13, Table 2).
Interestingly, phenylethynyl oxazolidinone (1q) and indole-
derived ynamide (1r) afforded the desired products 3qa and
3ra in good yields, while phenylethynyl pyrrolidinone (1s) was
reluctant to couple with 2a, even at elevated temperature (entries
16À18, Table 2).
Next, the haloallylation reaction was studied using substituted
allyl halides and ynamide 1a (Table 3). For example, allylic
chloride 2b afforded the desired enamide 3ab in 66% yield with
2:1 mixture of E/Z isomers (entry 1, Table 3). Additionally, the
reaction of 2-chloro-substituted allyl chloride (2c) and 2-methyl-
substituted allyl chloride (2d) occurred smoothly to give the
corresponding products 3ac and 3ad in 60% and 72% yields,
respectively (entries 2 and 3, Table 2). However, crotyl chloride
(2e) and allyl bromide (2f) failed to give the desired enamides
due to the formation of some unidentified byproducts (entries 4
and 5, Table 2).
We then sought to examine the synthetic utility of this
chloroallylation strategy for the synthesis of tetrasubstituted
enamides. For example, we tried the Suzuki coupling of enamide
3aa and the tetrasubstituted enamides 4 were obtained in good
yields by treating 3aa with 1.5 equiv of PhB(OH)2, 2.0 equiv of
K3PO4, 5 mol % of Pd(OAc)2, and 10 mol % of Xphos41 in THF
(Scheme 2).
a Reaction conditions: 1 (0.25 mmol), 2a (0.50 mmol), and PdCl2 (0.013
mmol) in 1 mL of DCE at rt for 3À6 h. b Isolated yield. c 5:1 mixture of
two rotamers. d E/Z = 13/1. e The reaction was carried out at 50 °C.
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NOTE
Scheme 2. Suzuki Coupling of 3aa
the literature,39,40 and the characteristic data of unreported ynamides are
listed as follows.
Ynamide 1b: yield 78% as a white solid; mp 78À80 °C; H NMR
1
(CDCl3, 400 MHz) δ 2.95 (s, 3 H), 4.70 (s, 2 H), 6.92À7.03 (m, 2 H),
7.31À7.52 (m, 7 H); 19F NMR (CDCl3, 282 MHz) δ À110.8; 13C
NMR (CDCl3, 100 MHz) δ 39.0, 55.9, 70.5, 81.6, 115.6 (d, J = 21.9 Hz),
118.5 (d, J = 3.7 Hz), 128.8, 128.9, 129.0, 133.5 (d, J = 8.3 Hz), 134.5,
162.4 (d, J = 247.9 Hz); MS (EI, m/z) 303 (M+, 10), 224 (25), 197 (17);
HRMS (EI) calcd for C16H14FNO2S (M+) 303.0729, found 303.0720.
Ynamide 1d: yield 82% as a yellow solid; mp 76À78 °C; 1H NMR
(CDCl3, 400 MHz) δ 2.94 (s, 3 H), 4.70 (s, 2 H), 7.15À7.24 (m, 2 H),
7.39À7.49 (m, 7 H); 13C NMR (CDCl3, 100 MHz) δ 39.1, 55.9, 70.8,
83.1, 121.5, 122.1, 128.9, 128.9, 129.0, 131.6, 132.7, 134.4; MS (EI, m/z)
365 (4), 363 (M+, 4), 286 (10), 360 (10); HRMS (EI) calcd for
C16H14BrNO2S (M+) 362.9929, found 362.9935.
Scheme 3. Proposed Mechanism
Ynamide 1e: yield 81% as a yellow oil; 1H NMR (CDCl3, 400 MHz)
δ 2.96 (s, 3 H), 4.72 (s, 2 H), 7.15 (t, J = 8.0 Hz, 1 H), 7.25À7.33 (m, 1
H), 7.38À7.55 (m, 7 H); 13C NMR (CDCl3, 100 MHz) δ 39.2, 55.9,
70.4, 83.3, 122.1, 124.6, 128.9, 128.9, 129.0, 129.7, 129.8, 131.0, 133.8,
134.4; MS (EI, m/z) 365 (3), 363 (M+, 3), 286 (7), 360 (8); HRMS (EI)
calcd for C16H14BrNO2S (M+) 362.9929, found 362.9930.
1
Ynamide 1g: yield 65% as a white solid; mp 88À90 °C; H NMR
(CDCl3, 400 MHz) δ1.31 (s, 9 H), 2.93 (s, 3 H), 4.71 (s, 2 H), 7.32 (s, 4 H),
7.39À7.52 (m, 5 H); 13C NMR (CDCl3, 100 MHz) δ 31.2, 34.8,
38.9, 55.9, 71.6, 81.3, 119.4, 125.3, 128.7, 128.8, 129.0, 131.4, 134.6,
151.5; MS (EI, m/z) 341 (M+, 20), 262 (30), 206 (46), 179 (20); HRMS
(EI) calcd for C20H23NO2S (M+) 341.1449, found 341.1453.
Ynamide 1i: yield 83% as a white solid; mp 104À106 °C; 1H NMR
(CDCl3, 400 MHz) δ 2.95 (s, 3 H), 3.86 (s, 3 H), 3.88 (s, 3 H), 4.71
(s, 2 H), 6.78 (d, J = 8.4 Hz, 1 H), 6.86 (d, J = 2.0 Hz, 1 H), 6.96À7.21
(m, 1 H), 7.39À7.51 (m, 5 H); 13C NMR (CDCl3, 100 MHz) δ 38.9,
55.9, 55.9, 55.9, 71.4, 80.5, 111.0, 114.5, 114.7, 125.2, 128.7, 128.8, 129.0,
134.7, 148.6, 149.5; HRMS (ESI) calcd for C18H19NO4S (M+) 345.1035,
found 345.1030.
To shed light on the possible mechanism of this reaction,
ynamide 1a was treated with 0.5 equiv of allylpalladium(II)
chloride dimer in dichloroethane at room temperature. However,
no desired enamide product 3aa was detected, and ynamide 1a
was recovered in 86% yield after stirring for 10 h. As such, the
allylpalladium intermediate seems to be unlikely for this reaction
and achloropalladation mechanismisthusproposedinScheme3.
It is well documented that the polarization of the triple bond of
ynamides enables the regioselective addition of nucleophiles at
the α-position to the nitrogen atom.37,38 Thus, the cis-halopalla-
dation of ynamides selectively forms the vinyl palladium inter-
mediate I, followed by the carbopalladation with allyl halide 2
to yield the alkyl palladium intermediate II. Finally, β-Cl
elimination42,43 produces enamide 3, together with the regen-
eration of the palladium catalyst (Scheme 3).
In conclusion, we have succeeded in implementing an efficient
method for the regio- and stereoselective synthesis of highly
substituted enamides by the Pd-catalyzed chloroallylation of
ynamides with allyl chlorides. It is worth to mention that the
reaction is typically performed only in the presence of 5 mol % of
PdCl2 at room temperature, and the omission of special ligands,
bases, and inert atmosphere makes it mild, practical and atom-
economic procedure for the preparation of multisubstituted
enamides. Further synthetic applications of this method will be
described in due course.
1
Ynamide 1j: yield 81% as a yellow solid; mp 70À72 °C; H NMR
(CDCl3, 400 MHz) δ 2.97 (s, 3 H), 4.74 (s, 2 H), 7.19À7.55 (m, 9 H);
13C NMR (CDCl3, 100 MHz) δ 39.1, 56.0, 69.1, 87.2, 122.6, 126.5,
128.9, 128.9, 128.9, 129.1, 129.2, 132.6, 134.4, 135.3; MS (EI, m/z) 321
(2), 319 (M+, 7), 242 (7), 262 (21); HRMS (EI) calcd for
C16H14ClNO2S (M+) 319.0434, found 319.0435.
Ynamide 1k: yield 72% as a white solid; mp 118À120 °C; 1H NMR
(CDCl3, 400 MHz) δ 2.98 (s, 3 H), 4.76 (s, 2 H), 7.41À7.55 (m, 8 H),
7.72À7.81 (m, 3 H), 7.88 (s, 1 H); 13C NMR (CDCl3, 100 MHz) δ 39.1,
56.0, 72.1, 82.3, 119.8, 126.6, 126.6, 127.6, 127.7, 128.0, 128.3, 128.8,
128.9, 129.1, 131.0, 132.6, 133.0, 134.6; MS (EI, m/z) 335 (M+, 20), 281
(18), 256 (43), 229 (30); HRMS (EI) calcd for C20H17NO2S (M+)
335.0980, found 335.0976.
1
Ynamide 1l: yield 70% as a yellow solid; mp 38À40 °C; H NMR
(CDCl3, 400 MHz) δ 0.89 (t, J = 6.4 Hz, 3 H), 1.26 (s, 12 H), 1.39À1.52
(m, 2 H), 2.17À2.30 (m, 2 H), 2.83 (s, 3 H), 4.54 (s, 2 H), 7.30À7.51
(m, 5 H); 13C NMR (CDCl3, 100 MHz) δ 14.1, 18.4, 22.7, 28.7, 28.8,
29.1, 29.3, 29.5, 31.9, 38.1, 55.6, 71.3, 73.1, 128.5, 128.6, 128.9, 134.9;
HRMS (ESI) calcd for C19H29NO2S (M+) 335.1919, found 335.1927.
Ynamide 1n: yield 87% as a yellow solid; mp 66À68 °C; 1H NMR
(CDCl3, 400 MHz) δ 3.17 (s, 3 H), 7.31À7.61 (m, 10 H); 13C NMR
(CDCl3, 100 MHz) δ 36.9, 71.0, 82.0, 122.3, 125.6, 128.2, 128.4, 128.4,
129.5, 131.6, 138.7; MS (EI, m/z) 271 (M+, 50), 264 (35), 219 (52), 192
(50);HRMS(EI) calcdforC15H13NO2S(M+) 271.0667, found 271.0664.
General Procedure for Pd-Catalyzed Chloroallylation of
Ynamides with Allyl Chloride. To a mixture of 1a (71 mg, 0.25
mmol) and PdCl2 (2.2 mg, 0.013 mmol) in 1 mL of DCE was added
2a (42 μL, 0.50 mmol). After being stirred for 4 h at rt, the reaction
mixture was concentrated and purified by column chromatography on
silica gel to give 80 mg (yield 88%) of 3aa as a white solid: mp 56À58 °C;
’ EXPERIMENTAL SECTION
General Methods. Unless otherwise noted, the reactions were
conducted under air atmosphere. Column chromatography was
1
performed using silica gel (300À400 mesh). H NMR and 13C NMR
spectra were recorded on a 400 MHz NMR spectrometers. MS and
microanalysis were performed in the state authorized analytical center of
Zhejiang Normal University. PdCl2, Pd(OAc)2, Pd(MeCN)2Cl2, and
Pd(PhCN)2Cl2 were obtained commercially and used without further
purification.
General Procedure for the Preparation of Ynamides.
Ynamides were prepared according to the method reported by Hsung.39
The spectroscopic data of ynamides 1a,c,f,h,m,oÀs were consistent with
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NOTE
Rf = 0.37 (hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 2.81
(s, 3 H), 3.23 (d, J = 6.0 Hz, 2 H), 4.26 (d, J = 13.6 Hz, 1 H), 4.43 (d, J =
13.6 Hz, 1 H), 4.95À5.04 (m, 2 H), 5.55À5.72 (m, 1 H), 6.75 (d, J =
7.2 Hz, 2 H), 7.08À7.32 (m, 8 H); 13C NMR (CDCl3, 100 MHz) δ 39.9,
40.7, 52.9, 117.1, 126.1, 127.3, 127.6, 127.9, 128.3, 128.5, 130.0, 132.2,
133.6, 138.1, 143.0; MS (EI, m/z) 363 (1), 361 (M+, 3), 326 (5), 284
(6); HRMS (EI) calcd for C19H20ClNO2S (M+) 361.0903, found
361.0906.
Compound 3ba: yield 84% as a white solid; mp 78À80 °C; Rf = 0.35
(hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 2.93 (s, 3 H),
3.13À3.25 (m, 2 H), 4.21 (d, J = 13.2 Hz, 1 H), 4.47 (d, J = 13.2 Hz, 1
H), 4.98À5.06 (m, 2 H), 5.55À5.67 (m, 1 H), 6.63À6.72 (m, 2 H), 6.77
(t, J = 8.8 Hz, 2 H), 7.08 (d, J = 7.2 Hz, 2 H), 7.20À7.30 (m, 3 H); 19F
NMR (CDCl3, 282 MHz) δ À114.5; 13C NMR (CDCl3, 100 MHz) δ
39.5, 40.8, 52.7, 114.5 (d, J = 21.3 Hz), 117.3, 126.0, 128.4, 128.5, 129.7
(d, J = 8.0 Hz), 130.0, 132.1, 133.5, 133.8 (d, J = 3.4 Hz), 142.6, 161.9
(d, J = 245.1 Hz); MS (EI, m/z) 381 (0.6), 379 (M+, 2), 344 (4), 302 (8),
300 (26); HRMS (EI) calcd for C19H19ClFNO2S (M+) 379.0809, found
379.0808.
Compound 3ca: yield 76% as a white solid; mp 70À72 °C; Rf = 0.27
(hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 2.94 (s, 3 H),
3.13À3.26 (m, 2 H), 4.20 (d, J = 13.2 Hz, 1 H), 4.47 (d, J = 13.2 Hz,
1 H), 4.95À5.04 (m, 2 H), 5.53À5.67 (m, 1 H), 6.62 (d, J = 8.4 Hz, 2 H),
7.01À7.15 (m, 4 H), 7.20À7.32 (m, 3 H); 13C NMR (CDCl3, 100 MHz)
δ 39.4, 40.5, 52.7, 117.3, 126.1, 127.7, 128.3, 128.4, 129.3, 129.9, 131.9,
133.1, 133.3, 136.3, 142.5; MS (EI, m/z): 397 (2), 395 (M+, 3), 362 (3),
360 (10); HRMS (EI) calcd for C19H19Cl2NO2S (M+) 395.0514, found
395.0516.
135.1, 137.0, 142.9; MS (EI, m/z) 377 (1), 375 (M+, 3), 298 (7), 296
(20); HRMS (EI) calcd for C20H22ClNO2S (M+) 375.1060, found
375.1064.
Compound 3ga: yield 73% as a yellow oil; Rf = 0.48 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 1.30 (s, 9 H), 2.83 (s, 3 H), 3.22 (dd,
J = 6.0, 1.3 Hz, 2 H), 4.24 (d, J = 13.6 Hz, 1 H), 4.44 (d, J = 13.6 Hz, 1 H),
4.95À5.11 (m, 2 H), 5.62À5.74 (m, 1 H), 6.73À6.79 (m, 2 H), 7.03À7.09
(m, 2 H), 7.13À7.27 (m, 5 H); 13C NMR (CDCl3, 100 MHz)
δ 31.3, 34.5, 39.9, 40.7, 53.1, 116.9, 124.5, 126.0, 127.5, 128.2, 128.4,
129.8, 132.5, 133.7, 135.1, 142.8, 150.2; MS (EI, m/z) 419 (1), 417
(M+, 3), 341 (6), 338 (20); HRMS (EI) calcd for C23H28ClNO2S
(M+) 417.1529, found 417.1526.
Compound 3ha: yield 77% as a yellow oil; Rf = 0.28 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 2.87 (s, 3 H), 3.16À3.25 (m, 2 H),
3.77 (s, 3 H), 4.24 (d, J = 13.6 Hz, 1 H), 4.43 (d, J = 13.6 Hz, 1 H),
4.97À5.06 (m, 2 H), 5.57À5.70 (m, 1 H), 6.65 (d, J = 8.0 Hz, 2 H), 6.73
(d, J = 8.4 Hz, 2 H), 7.09 (d, J = 7.2 Hz, 2 H), 7.20À7.30 (m, 3 H); 13C
NMR (CDCl3, 100 MHz) δ 39.9, 40.8, 53.0, 55.2, 113.0, 116.9, 125.7,
128.3, 128.4, 129.2, 129.9, 130.3, 132.5, 133.7, 142.6, 158.8; MS
(EI, m/z) 393 (1), 391 (M+, 3), 314 (9), 312 (28); HRMS (EI) calcd
for C20H22ClNO3S (M+) 391.1009, found 391.1010.
Compound 3ia: yield 71% as a yellow oil; Rf = 0.17 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 2.97 (s, 3 H), 3.12À3.28 (m, 2 H),
3.78 (s, 3 H), 3.85 (s, 3 H), 4.17 (d, J = 13.6 Hz, 1 H), 4.38 (d, J = 13.6 Hz,
1 H), 4.96À5.08 (m, 2 H), 5.60À5.70 (m, 1 H), 6.38 (dd, J = 8.4,
2.0 Hz, 1 H), 6.60 (d, J = 8.4 Hz, 1 H), 6.72 (d, J = 2.0 Hz, 1 H), 7.02 (d, J =
7.2 Hz, 2 H), 7.13À7.22 (m, 3 H); 13C NMR (CDCl3, 100 MHz) δ 39.8,
40.7, 53.2, 55.8, 55.8, 110.2, 111.7, 116.9, 120.2, 125.8, 128.1, 128.2, 129.7,
130.5, 132.8, 133.5, 142.4, 148.0, 148.2; MS (EI, m/z):423 (1), 421(M+, 3),
344 (11), 342 (35); HRMS (EI) calcd for C21H24ClNO4S (M+) 421.1115,
found 421.1117.
Compound 3ja: yield 70% as a yellow oil; 5:1 mixture of two
rotamers; Rf = 0.44 (hexanes/EtOAc = 6/1); 1H NMR (C2D6SO,
400 MHz, 90 °C) δ 2.84 (s, 3 H), 3.21À3.42 (m, 2 H), 4.39 (s, 2 H),
4.92À5.10 (m, 2 H), 5.50À5.71 (m, 1 H), 7.07À7.31 (m, 9 H); 13C
NMR (C2D6SO, 100 MHz, 90 °C) δ 39.0, 53.6, 117.7, 126.5, 128.4,
128.7, 129.5, 129.7, 129.7, 129.8, 129.8, 131.5, 132.3, 132.5, 134.7, 136.5,
140.4; MS (EI, m/z) 397 (2), 395 (M+, 3), 362 (3), 360 (10); HRMS
(EI) calcd for C19H19Cl2NO2S (M+) 395.0514, found 395.0508.
Compound 3ka: yield 80% as a yellow oil; Rf = 0.40 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 2.83 (s, 3 H), 3.28À3.34 (m, 2 H),
4.29 (d, J = 13.6 Hz, 1 H), 4.45 (d, J = 13.6 Hz, 1 H), 4.98À5.12 (m, 2 H),
5.62À5.78 (m, 1 H), 7.01À7.09 (m, 4 H), 7.17 (t, J = 7.6 Hz, 2 H),
7.31À7.40 (m, 1 H), 7.44À7.50 (m, 2 H), 7.60À7.69 (m, 2 H), 7.78À7.90
(m, 1 H); 13C NMR (CDCl3, 100 MHz) δ 39.8, 40.8, 52.8, 117.2, 125.9,
126.1, 126.2, 126.3, 126.8, 127.2, 127.5, 128.4, 128.4, 128.5, 130.0, 132.2,
132.4, 132.6, 133.6, 135.6, 143.2; MS (EI, m/z): 413 (2), 411 (M+, 6), 334
(26), 332 (79); HRMS (EI) calcd for C23H22ClNO2S (M+) 411.1060,
found 411.1058.
Crystal data for 3ca (C19H19Cl2NO2S, 395.05): orthorhombic, space
group P2(1)/c, a = 7.0335(5) Å, b = 35.053(2) Å, c = 8.2257(6) Å, U =
1946.4(2) Å3, Z = 4, specimen 0.312 Â 0.106 Â 0.035 mm3, T = 296(2)
K, SIEMENS P4 diffractometer, absorption coefficient 0.453 mmÀ1
,
reflections collected 14402, independent reflections 3411 [R(int) =
0.0603], refinement by full-matrix least-squares on F2, data/restraints/
parameters 3411/2/235, goodness-of-fit on F2 = 1.036, final R indices
[I > 2σ(I)] R1 = 0.0497, wR2 = 0.1122, R indices (all data) R1 = 0.1072,
wR2 = 0.1288, largest diff peak and hole 0.161 and À0.224 e ÅÀ3. Crystal
data of 3ca have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication no. CCDC 834590.
Compound 3da: yield 75% as a white solid; mp 106À108 °C; Rf =
1
0.35 (hexanes/EtOAc = 6/1); H NMR (CDCl3, 400 MHz) δ 2.95
(s, 3 H), 3.13À3.24 (m, 2 H), 4.21 (d, J = 13.2 Hz, 1 H), 4.48 (d, J =
13.2 Hz, 1 H), 4.98À5.06 (m, 2 H), 5.57À5.64 (m, 1 H), 6.57 (d, J =
8.4 Hz, 2 H), 7.08 (d, J = 7.2 Hz, 2 H), 7.19À7.33 (m, 5 H); 13C NMR
(CDCl3, 100 MHz) δ 39.4, 40.5, 52.7, 117.4, 121.4, 126.1, 128.4, 128.5,
129.7, 130.0, 130.7, 132.0, 133.4, 136.8, 142.6; MS (EI, m/z): 441 (1),
439 (M+, 1), 406 (4), 404 (4); HRMS (EI) calcd for C19H19BrClNO2S
(M+) 439.0008, found 439.0009.
Compound 3ea: yield 73% as a white solid; mp 70À72 °C; Rf = 0.34
(hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 2.92 (s, 3 H),
3.10À3.23 (m, 2 H), 4.20 (d, J = 13.2 Hz, 1 H), 4.48 (d, J = 13.2 Hz,
1 H), 4.95À5.05 (m, 2 H), 5.52À5.66 (m, 1 H), 6.55 (s, 1 H), 6.92 (d, J =
7.6 Hz, 1 H), 7.01À7.12 (m, 3 H), 7.22À7.34 (m, 4 H); 13C NMR
(CDCl3, 100 MHz) δ 39.4, 40.5, 52.6, 117.5, 121.5, 126.5, 127.1, 128.5,
128.6, 129.1, 129.9, 130.4, 130.4, 131.8, 133.1, 139.9, 142.2; MS (EI, m/z):
441 (2), 439 (M+, 2), 406 (7), 404 (7); HRMS (EI) calcd for
C19H19BrClNO2S (M+) 439.0008, found 439.0013.
Compound 3la: yield 72% as a yellow oil; Rf = 0.48 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 0.88 (t, J = 6.8 Hz, 3 H), 0.95À1.30
(m, 14 H), 1.86 (t, J = 8.8 Hz, 2 H), 2.86 (d, J = 6.0 Hz, 2 H), 3.03 (s, 3 H),
4.20 (d, J = 13.2 Hz, 1 H), 4.77 (d, J = 13.2 Hz, 1 H), 4.88À4.97 (m, 2 H),
5.51À5.62 (m, 1 H), 7.29À7.37 (m, 5 H); 13C NMR (CDCl3, 100 MHz)
δ 14.1, 22.7, 27.0, 29.3, 29.3, 29.5, 29.8, 31.9, 33.0, 36.3, 38.9, 51.9, 116.5,
122.2, 128.4, 128.5, 130.0, 132.9, 134.4, 145.6; HRMS (ESI) calcd for
C22H34ClNO2S (M+) 411.1999, found 411.2002.
Compound 3fa: yield 84% as a white solid; mp 102À104 °C; Rf =
0.40 (hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 2.29 (s,
3 H), 2.82 (s, 3 H), 3.22 (d, J = 6.0 Hz, 2 H), 4.27 (d, J = 13.6 Hz, 1 H),
4.42 (d, J = 13.6 Hz, 1 H), 4.98À5.05 (m, 2 H), 5.59À5.67 (m, 1 H),
6.68 (d, J = 8.0 Hz, 2 H), 6.94 (d, J = 7.6 Hz, 2 H), 7.11 (d, J = 7.2 Hz,
2 H), 7.21À7.32 (m, 3 H); 13C NMR (CDCl3, 100 MHz) δ 21.2, 40.0,
40.7, 53.0, 117.0, 125.9, 127.8, 128.3, 128.4, 128.5, 130.0, 132.4, 133.7,
Compound 3ma: yield 71% as a yellow oil; E/Z > 13/1; Rf = 0.46
(hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 0.78 (t, J =
7.2 Hz, 3 H), 0.95À1.15 (m, 2 H), 1.25À1.42 (m, 2 H) 2.85 (s, 3 H),
3.27À3.48 (m, 4 H), 5.05À5.21 (m, 2 H), 5.71À5.86 (m, 1 H),
7.27À7.44 (m, 5 H); 13C NMR (CDCl3, 100 MHz) δ 13.6, 19.9,
29.6, 39.1, 40.8, 49.1, 117.2, 126.6, 127.7, 128.0, 128.2, 132.4, 138.5,
142.6; MS (EI, m/z) 329 (0.7), 327 (M+, 2), 292 (7), 250 (2), 248 (6).
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NOTE
Anal. Calcd for C16H22ClNO2S: C, 58.61; H, 6.76; Cl, 10.81; N, 4.27.
Found: C, 58.78; H, 6.95; Cl, 10.64; N, 4.16.
(m, 2 H), 7.10À7.31 (m, 8 H); 13C NMR (CDCl3, 100 MHz) δ 22.6, 39.9,
44.6, 53.0, 112.7, 126.7, 127.2, 127.6, 128.0, 128.3, 128.5, 130.0, 133.7,
138.0, 140.4, 143.1; MS (EI, m/z): 377 (3), 375 (M+, 10), 298 (14),
296 (46); HRMS (EI) calcd for C20H22ClNO2S (M+) 375.1060, found
375.1066.
Compound 3na: yield 85% as a colorless oil; Rf = 0.44 (hexanes/
EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 2.97 (s, 3 H), 3.27À3.37
(m, 2 H), 5.04À5.13 (m, 2 H), 5.68À5.82 (m, 1 H), 7.03À7.11 (m, 2 H),
7.19À7.33 (m, 8 H); 13C NMR (CDCl3, 100 MHz) δ 39.4, 40.2, 117.3,
126.3, 127.1, 127.8, 127.9, 128.0, 128.1, 129.1, 132.1, 138.2, 139.5, 142.5;
MS (EI, m/z) 349 (2), 347 (M+, 6), 270 (18), 268 (56); HRMS (EI) calcd
for C18H18ClNO2S (M+) 347.0747, found 347.0748.
Compound 3oa: yield 76% as a yellow oil; Rf = 0.57 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 2.44 (s, 3 H), 3.16À3.32 (m, 2 H),
4.08 (d, J = 13.2 Hz, 1 H), 4.31 d, J = 13.2 Hz, 1 H), 4.95À5.08 (m, 2 H),
5.56À5.71 (m, 1 H), 6.62 (d, J= 7.2 Hz, 2 H), 6.94 (d, J= 7.2 Hz, 2 H), 7.11
(t, J = 7.2 Hz, 2 H), 7.18À7.31 (m, 6 H), 7.54 (d, J = 8.4 Hz, 2 H); 13C
NMR (CDCl3, 100 MHz) δ 21.6, 41.0, 52.0, 117.0, 125.6, 127.1, 127.5,
128.1, 128.2, 128.3, 128.9, 129.4, 130.2, 132.4, 133.5, 135.2, 138.4, 143.9,
144.3; MS (EI, m/z) 439 (1), 437 (M+, 3), 284 (5), 282 (14); HRMS (EI)
calcd for C25H24ClNO2S (M+) 437.1216, found 437.1214.
General Procedure for the Suzuki Coupling of 3aa. To a
mixture of PhB(OH)2 (37 mg, 0.30 mmol), Pd(OAc)2 (2.3 mg, 0.01
mmol), K3PO4 (43 mg, 0.40 mmol), and Xphos (9.5 mg, 0.02 mmol) in
2 mL of THF was added 3aa (72 mg, 0.20 mmol) under nitrogen. After
being stirred at 70 °C for 6 h, the reaction was quenched with water,
extracted with EtOAc, dried, and concentrated. Column chromatogra-
phy on silica gel gave 53 mg (yield: 65%) of 4a as a colorless oil: Rf = 0.36
(hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 1.90 (s, 3 H),
2.92À3.06 (m, 1 H), 3.08À3.21 (m, 1 H), 3.98 (d, J = 14.0 Hz, 1 H),
4.23 (d, J = 14.0 Hz, 1 H), 4.82À4.98 (m, 2 H), 5.51À5.65 (m, 1 H),
6.83À7.01 (m, 2 H), 7.10À7.25 (m, 5 H), 7.29À7.45 (m, 8 H); 13C
NMR (CDCl3, 100 MHz) δ 40.1, 41.6, 52.6, 116.4, 127.1, 128.0, 128.3,
128.3, 128.4, 128.6, 128.9, 129.8, 130.2, 134.9, 135.2, 135.9, 136.4, 139.9,
140.6; HRMS (ESI) calcd for C25H25NO2S (M+) 403.1606, found
403.1608.
Compound 4b: yield 72% yield as a yellow oil; Rf = 0.46 (hexanes/
EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 1.92 (s, 3 H), 2.94À3.08
(m, 1 H), 3.09À3.21 (m, 1 H), 3.81 (s, 3 H), 4.00 (d, J = 14.2 Hz, 1 H),
4.21 (d, J = 14.2 Hz, 1 H), 4.82À4.98 (m, 2 H), 5.52À5.76 (m, 1 H),
6.83À6.98 (m, 4 H), 7.19À7.25 (m, 5 H), 7.27À7.39 (m, 5 H); 13C
NMR (CDCl3, 100 MHz) δ 40.1, 41.6, 52.5, 55.3, 113.8, 116.3, 127.0,
128.0, 128.3, 128.6, 128.7, 128.9, 130.2, 131.2, 134.6, 135.4, 136.1, 139.0,
140.1, 159.5; HRMS (ESI) calcd for C26H27NO3S (M+) 433.1712,
found 433.1709.
Compound 3pa: yield 81% as a white solid; mp 78À80 °C; Rf = 0.57
(hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 2.37 (s, 3 H),
3.26À3.37 (m, 2 H), 3.49À3.61 (m, 1 H), 3.68À3.78 (m, 1 H),
5.02À5.16 (m, 4 H), 5.38À5.52 (m, 1 H), 5.55À5.82 (m, 1 H), 7.18
(d, J = 8.0 Hz, 2 H), 7.27À7.35 (m, 5 H), 7.52 (d, J = 8.4 Hz, 2 H); 13
C
NMR (CDCl3, 100 MHz) δ 21.6, 40.8, 51.8, 117.1, 120.2, 126.4, 127.5,
127.9, 128.4, 128.7, 129.4, 131.5, 132.6, 135.2, 138.8, 143.1, 144.1;
HRMS (ESI) calcd for C21H22ClNO2S (M+) 387.1060, found
387.1059.
Compound 3qa: yield 68% as a colorless oil; Rf = 0.41 (hexanes/
EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 3.33 (d, J = 6.4 Hz, 2 H),
3.53 (t, J = 8.0 Hz, 2 H), 4.14 (t, J = 8.0 Hz, 2 H), 5.03À5.14 (m, 2 H),
5.68À5.77 (m, 1 H), 7.20À7.33 (m, 5 H); 13C NMR (CDCl3, 100 MHz)
δ 39.7, 45.1, 62.3, 117.3, 123.8, 127.3, 128.0, 128.4, 132.4, 138.1,
140.9, 155.8; HRMS (ESI) calcd for C14H14ClNO2 (M+) 263.0713,
found 263.0706.
Compound 4c: yield 70% yield as a colorless oil; Rf = 0.37 (hexanes/
EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz) δ 1.98 (s, 3 H), 2.40 (s, 3 H),
3.02À3.20 (m, 2 H), 4.03 (d, J = 14.2 Hz, 1 H), 4.18 (d, J = 14.2 Hz,
1 H), 4.84À5.01 (m, 2 H), 5.54À5.72 (m, 1 H), 6.85À7.02 (m, 2 H),
7.03À7.18 (m, 7 H), 7.19À7.35 (m, 2 H), 7.36À7.53 (m, 3 H); 13C
NMR (CDCl3, 100 MHz) δ 21.3, 40.1, 41.6, 52.6, 116.4, 127.1, 128.0,
128.3, 128.6, 128.9, 129.1, 129.8, 130.2, 133.5, 134.9, 135.3, 136.0,
138.2, 139.4, 140.7; HRMS (ESI) calcd for C26H27NO2S (M+)
417.1762, found 417.1760.
Compound 3ra: yield 84% as yellow oil; Rf = 0.56 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 3.51À3.68 (m, 2 H), 5.15À5.30
(m, 2 H), 5.85À5.98 (m, 1 H), 6.55À6.63 (m, 1 H), 6.92À7.24 (m, 6
H), 7.28À7.31 (m, 1 H), 7.46 (d, J = 7.2 Hz, 1 H), 7.58À7.69 (m, 1 H);
13C NMR (CDCl3, 100 MHz) δ 39.8, 103.3, 103.6, 115.7, 117.6, 118.2,
122.4, 123.3, 126.1, 127.0, 128.0, 128.4, 129.8, 131.0, 132.7, 135.6, 137.3,
138.8; MS (EI, m/z) 320 (24), 318 (M+, 75), 303 (40), 283 (75); HRMS
(EI) calcd for C20H15ClN2 (M+) 318.0924, found 318.0917.
Compound 3ab: yield 66% as a colorless oil; 4E/4Z = 2/1; Rf = 0.47
(hexanes/EtOAc = 6/1); 1H NMR (CDCl3, 400 MHz), major isomer δ
0.82À1.02 (m, 3 H), 1.22À1.42 (m, 4 H), 1.22À1.42 (m, 2 H), 2.79
(s, 3 H), 3.14À3.23 (m, 2 H), 4.25 (d, J = 13.6 Hz, 1 H), 4.41 (d, J =
13.6 Hz, 1 H), 5.11À5.28 (m, 1 H), 5.32À5.43 (m, 1 H), 6.68À6.81
(m, 2 H), 7.05À7.41 (m, 8 H); 13C NMR (CDCl3, 100 MHz), major
isomer δ 13.9, 22.0, 31.4, 32.1, 39.7, 39.9, 52.9, 123.4, 127.1, 127.5,
128.0, 128.3, 128.4, 130.1, 130.2, 133.6, 133.7, 138.2, 144.0; MS (EI, m/z)
419 (2), 417 (M+, 5), 340 (15), 338 (43). Anal. Calcd for C23H28ClNO2S:
C, 66.09; H, 6.75; Cl, 8.48; N, 3.35. Found: C, 66.33; H, 6.52; Cl,
8.21; N, 3.59.
’ ASSOCIATED CONTENT
S
Supporting Information. Spectroscopic data of yna-
b
mides 1b,d,e,g,iÀl,n and all of the products as well as the
crystallographic data of 3ca (CIF). This material is available free
of charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: gangguo@zjnu.cn.
’ ACKNOWLEDGMENT
Compound 3ac: yield 60% as a yellow oil; Rf = 0.34 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 2.76 (s, 3 H), 3.44À3.56 (m, 2 H),
4.26 (d, J = 13.6 Hz, 1 H), 4.43 (d, J = 13.6 Hz, 1 H), 5.07À5.13 (m, 2 H),
6.69À6.78 (m, 2 H), 7.07À7.28 (m, 8 H); 13CNMR(CDCl3, 100 MHz) δ
39.9, 45.8, 53.0, 114.2, 127.6, 127.8, 128.1, 128.5, 128.6, 128.7, 130.0, 133.5,
136.7, 137.1, 140.5; HRMS (ESI) calcd for C19H19Cl2NO2S (M+)
395.0514, found 395.0518.
Compound 3ad: yield 72% as a yellow oil; Rf = 0.46 (hexanes/EtOAc =
6/1); 1H NMR (CDCl3, 400 MHz) δ 1.67 (s, 3 H), 2.82 (s, 3 H), 3.14
(d, J = 14.6 Hz, 1 H), 3.29 (d, J = 14.6 Hz, 1 H), 4.29 (d, J = 13.6 Hz,
1 H), 4.46 (d, J = 13.6 Hz, 1 H), 4.59 (s, 1 H), 4.69 (s, 1 H), 6.77À6.82
We thank the National Natural Science Foundation of
China (Nos. 20902084, 21172199) and QianjiangTalents Project
of the Science and Technology Office in Zhejiang Province
(2010R10016) for their financial support.
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