Palladium-Catalyzed Alkynylation of Morita-Baylis-Hillman Carbonates with (Triisopropylsilyl)acetylene on Water

Article abstract of DOI:10.1021/acs.joc.5b00728

Direct alkynylation of Morita-Baylis-Hillman carbonates with (triisopropylsilyl)acetylene catalyzed by a Pd(OAc)₂-NHC complex was developed "on water" to give the corresponding 1,4-enynes. The significant effects of water amount in the solvent

Full text of DOI:10.1021/acs.joc.5b00728

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Article
Palladium-Catalyzed Alkynylation of Morita-Baylis-Hillman
Carbonates with (Triisopropylsilyl)acetylene on Water
Yangxiong Li, Li Liu, Delong Kong, Dong Wang, Weichun Feng, Tao Yue, and Chao-Jun Li
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.5b00728 • Publication Date (Web): 19 May 2015
Downloaded from http://pubs.acs.org on May 21, 2015
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Palladium-Catalyzed Alkynylation of Morita-Baylis-Hillman Carbonates
with (triisopropylsilyl)acetylene on Water
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Yangxiong Li,1 Li Liu,1* Delong Kong,1 Dong Wang,1Weichun Feng,3 Tao Yue3 and
Chaojun Li 2*
1 Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of
Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of
Sciences, Beijing 100190, China
2Department of Chemistry, McGill University, Montreal, Quebec, Canada H3A 0B8
3 Chemical Technology Academy of Shandong Province
*Corresponding Author: lliu@iccas.ac.cn;
_____________________________________________________________________
ABSTRACT ： The direct alkynylation of MBH carbonates with
(triisopropylsilyl)acetylene catalyzed by Pd(OAc)2ꢀNHC complex was developed “on
water” to give the corresponding 1,4ꢀenynes. The great effects of water amount in
solvent on the further transformations of the product 1,4ꢀenynes were investigated.
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INTRODUCTION
The Pdꢀcatalyzed allylation of carbon nucleophiles with allylic compounds
ꢀallylpalladium complexes (TsujiꢀTrost reaction) represents one of the most
via
π
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important developments in modern synthetic chemistry.1 Recently, the TsujiꢀTrost
reaction of allyl ester with terminal alkynes (or corresponding metal reagent) has
received considerable attention because it provides a convenient and direct
approach to construct 1,4ꢀenyne moiety.2 At the same time, the extensive use of
organic solvents has led to concerns regarding their toxicity, hazard, pollution and
waste treatment issues. Water, being cheap, readily available, nonꢀtoxic and
nonꢀflammable, has shown extensive potentials in organic reactions. In view of
sustainable chemistry, the interest in metalꢀcatalyzed processes in aqueous media
and air conditions has been increasing dramatically.3 It is noteworthy that
although the aqueous TsujiꢀTrost reaction has been developed widely,4 yet, there
has been no example of using terminal alkyne as a pronucleophile for aqueous
TsujiꢀTrost reaction.5 It is probably attributed to low acidity of terminal alkynes
as pronucleophiles and the TsujiꢀTrost reaction is very sensitive to the acidity of
the CꢀH bonds of the pronucleophiles.5ꢀ6 Therefore, the quest for waterꢀstable and
more efficient catalyst systems for the coupling of allyl esters with terminal
alkynes in water remains a great challenge.
Allylic alkylation of Morita–Baylis–Hillman (MBH) adducts, which possess
both allylic hydroxyl and Michael acceptor units in the same molecule, has been
widely applied in the synthesis of natural products and bioactive compounds.7 The
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reaction of MBH adducts with alkynyl metal could provide allylic substitution
products,8 however terminal alkynes were seldom directly used as nucleophiles in the
alkynylation of MBH adducts.8d Very recently, we reported a direct coupling of
terminal alkynes with allylic alcohols catalyzed by Pd(PPh3)4 with a N,Pꢀligand.9
Based on our ongoing interest in the transformations of the MBH adducts, as well as
organic reactions in aqueous media,10ꢀ11 herein, we wish to report the alkynylation of
MBH carbonates with (triisopropylsilyl)acetylene catalyzed by [PdꢀNHC] complex on
water under an air atmosphere.
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RESULTS AND DISCUSSION
Initially, the reaction of (triisopropylsilyl)acetylene(1) and MBH carbonate
2a was investigated under the catalysis of Pd(PPh3)4 with N,Pꢀligand L1 in water
alone.9 However, only 12% yield of the product 3a was obtained (Table 1). Thus,
we turned our attention to more electronꢀrich ligand to effect the aqueous
TsujiꢀTrost reaction of (triisopropylsilyl)acetylene. NꢀHeterocyclic carbene
Figure 1. NHC Ligands
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(NHC) ligands have been successfully applied in various transition metal
catalyzed reactions due to its strong bonding to metal centers and good stability
towards air and moisture.12 As shown in Figure 1 and Table 1, the use of the NHC
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ligands L3ꢀL6 in the Pdꢀcatalyzed coupling reaction of terminal alkyne (1) and
MBH carbonate 2a in water provided the desired product 3a in 38~54% yield,
respectively (entries 6~9). It was found that the catalytic activity strongly
depended upon the molecular structure of the NHC ligand used. When thiazolyl
NHC ligands L7ꢀL9 were used, 20~21% yield of 3a was obtained (entries 10~12).
The desired product 3a was obtained in 37% yield in the presence of the Pd
catalyst, prepared in situ from PdCl2 and NHC ligand L2 (Table 1, entry 2). The
use of the Pd(TFA)2 with L2 gave an increased yield (68%, entry 3).In the
presence of a base (10 mol %) such as triethylamine (TEA) as additive the yield
of product 3a was increased to 61% (entry 4). The best result (71% yield, entry 5)
was obtained with the combination of Pd(OAc)2 with NHC Ligand L2
.
Table 1. Optimization of the NHC Ligandsa
COOMe
OBoc
iPr
Si iPr
iPr
[Pd-NHC]
water
COOMe
+
iPr
iPr
Si
3a
2a
1
iPr
Entry
Pd salts
NHC Ligands
Yield(%)
1
2
3
Pd(PPh3)4
PdCl2
L1
L2
L2
12
37
68
Pd(TFA)2
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Pd(OAc)2
L2+TEA
L2
61
71
38
52
54
38
20
20
21
NR
14
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
ꢀꢀꢀ
6
L3
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7
L4
8
L5
9
L6
10
11
12
13
14
L7
L8
L9
L2
Pd(OAc)2
ꢀꢀꢀ
aReaction conditions: 1 (0.5 mmol), MBH carbonate 2a (0.2 mmol), [PdꢀNHC] catalysts (10 mol %), 2 mL water,
under air atmosphere, 70 oC for 10 h. [PdꢀNHC] catalysts were prepared in situ at rt by mixing Pd(OAc)2 (10 mol
%), NHC ligands (20 mol %) and tꢀBuOK (24 mol %) in THF (2 mL) for 2 h, followed by the removal of the
solvent under reduced pressure.
Notably, no reaction was observed in the absence of Pd(OAc)2 (entry 13).
Moreover, when Pd(OAc)2 was employed alone without the use of NHC ligand, a
poor yield of 3a (14%) was obtained (entry 14), suggesting that both Pd(OAc)2
and NHC ligands L2 are necessary and cooperatively catalyze this reaction.
Subsequently, the solvent effect was examined (Table 2) using the reaction
of
1 with 2a in the presence of Pd(II)ꢀcatalyst catalyst, prepared in situ from
Pd(OAc)2 (10 mol %) and NHC ligand L2 (20 mol %). When organic solvents
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such as THF, acetone, DMF and dioxane were used, very little desired product 3a
was isolated (4~23 % yields, Table 2, entries 1~4).
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It was noteworthy that with the increase of proportion of water in a mixture
of dioxaneꢀwater (>1 : 1), the yield of 3a increased despite the reaction system
becoming heterogeneous (entries 8~11). For the yield of product 3a, the
heterogeneous system was better than the homogeneous system (entries 4~7 vs
8~11). On the other hand, under the solventꢀfree conditions the product 3a was
obtained in 44% yield (entry 15), which was relatively lower than the best result
(71% yield) under waterꢀonly conditions (entry 11). When the reaction was scaled
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up in 10 folds with the substrate 2a (2 mmol) and
1 (5 mmol) under the same
conditions, the yield of 3a was increased up to 94%. These interesting results are
consistent with the suggestion of the reaction proceeding “on water”, put forward
by Shapless.13 The on water reaction in heterogeneous aqueous media offers
better results than the same reactions proceeding in homogeneous aqueous media
and under solventꢀfree conditions.
Table 2. Optimization of the Solvent and Temperaturea
Entry
Solvent
Temperature(oC)
Yield(%)
1
2
3
4
THF
acetone
DMF
70
70
70
70
20
7
4
Dioxaneb
23
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dioxaneꢀwater
5
6
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70
70
70
34
11
20
44
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(3 : 1)b
dioxaneꢀwater
(2 : 1)b
dioxaneꢀwater
(1 : 1)b
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dioxaneꢀwater
(1 :2)c
dioxaneꢀwater
(1 : 3)c
70
dioxaneꢀwater
(1 : 4)c
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15
70
70
90
50
30
70
64
71
Waterc
water
water
water
ꢀꢀꢀ
55
48
trace
44
aReaction conditions: 1 (0.5 mmol), MBH carbonate 2a (0.2 mmol), [PdꢀNHC] catalyst (10 mol %), solvent (2
o
mL), under air atmosphere, 70 C for 10 h. [PdꢀNHC] catalyst was prepared in situ at rt by mixing Pd(OAc)2 (10
mol %), NHC ligands L2 (20 mol %) and tꢀBuOK (24 mol %) in THF (2 mL) for 2 h, and then the solvent was
removed under reduced pressure. bHomogeneous. cHeterogeneous.
Screening of different reaction temperatures at 30 oC~90 oC revealed that 70
oC is the optimal temperature, and lowering or rising the reaction temperature
would result in decreased yields (Table 2, entries 11~14).
With the optimized reaction conditions in hand, various substituted MBH
carbonates 2a-r, were reacted with (triisopropylsilyl)acetylene (
1) in water,
affording the corresponding 1,4ꢀenynes products 3a in good to excellent yields.
ꢀr
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COOR2
Si
OBoc
[Pd-NHC]
(10 mol%)
COOR2
R1
iPr
Si iPr
iPr
R1
H2O, 70 oC
+
iPr
iPr
3a-r
2a-r
1
iPr
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COOMe
R
COOMe
R
COOMe
R
H3C
Cl
F
3a, 71%
CH3
3c, 91%
3b, 84%
COOMe
R
COOMe
R
H3C
COOMe
R
3f, 72%
3i, 86%
3e, 74%
3d, 72%
3g, 70%
3j, 54%
F
COOMe
H3CO
COOMe
COOMe
Br
R
R
R
3h, 77%
3k, 89%
F3C
COOMe
COOMe
NC
COOMe
R
R
R
3l, 77%
3o, 73%
COOMe
COOMe
COOtBu
F
R
R
R
3m, 85%
3n, 75%
COOn-Bu
R
COOMe
COOMe
S
R
R
3r, 78%
3p, 75%
3q, 65%
iPr
R=
Si
iPr
iPr
aReaction conditions: 1 (0.5 mmol), MBH carbonate 2a-r (0.2 mmol), [PdꢀNHC] catalyst (10 mol %) in water (2
mL) at70 oC for 10 h. [PdꢀNHC] catalyst was prepared in situ at rt by mixing Pd(OAc)2 (10 mol %), NHC ligands
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L2 (20 mol %) and tꢀBuOK (24 mol %) in THF (2 mL) for 2 h, and then the solvent was removed under reduced
pressure.
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Scheme1. Pd(OAc)2ꢀL2 catalyzed allylation of 1 with MBH carbonatesa
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The results are summarized in Scheme 1. The substituents, either
electronꢀwithdrawing or electronꢀdonating except CN (2j) on the phenyl ring of
the MBH carbonates did not influence the reaction yield significantly. If the ester
group was changed from methyl to tꢀbutyl or nꢀbutyl, the yields of products 3o
and 3p still remained 73% and 75%, respectively. In addition, if the phenyl ring
of the MBH carbonates was replaced by cinnamenyl or thienyl, the yields of
products 3q and 3r was 65% and 78%, respectively. For simple allylic carbonate,
tertꢀbutyl (1ꢀphenylallyl) carbonate could also react with (triisopropylsilyl)acetylene
(1) to afford the corresponding 1,4ꢀenyne product in a little low yield (56%).
The proposed mechanism for this coupling reaction is shown in Figure 2.
The departure of the OBoc group of MBH carbonate released carbon dioxide and
tertꢀbutoxide anion, then generated a
hydroxyl anion. Coordination of terminal alkyne to
The hydroxyl anion may help to deprotonate the terminal alkyne to form
πꢀallyl palladium intermediate
A and a
A
generated intermediate
B.
intermediate
C
. Subsequently, intermediate
C
transformed into 1,4ꢀenyne via
reductive elimination.
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COOR2
R1
6
7
R
8
9
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COOR2
OBoc
L2
Pd-
R1
COOR2
R1
L2
Pd-
C
tBuOH
+
OH
+
tBuO
CO2
R
H2O
H2O
COOR2
R1
L2
Pd-
A
HO
COOR2
R1
R
H
L2
Pd-
R
H
B
Figure 2.A tentative mechanism for the [PdꢀNHC] catalyzed coupling of MBH
carbonates with (triisopropylsilyl)acetylene
The great effects of water amount in solvent on subsequent desilylation of
1,4ꢀenyne were observed. When 3a was treated with TBAF in THF in the presence
of without water or 1 equiv water, 1,3ꢀenyne 4a was obtained (Table 3, entry 1ꢀ2).14
As the amount of water in the system was changed, the product mixtures of
rearrangement product 4a, desilylation product 5a and cyclization product 6a could
be obtained in different ratios, respectively. If the amount of water was 40 equiv,
desilylation product 5a was obtained in 81% yield exclusively (entry 6). When DBU
was added in the reaction of 3a in the presence of 10 equiv water in TBAF/THF,
cyclization product 6a was formed in 78% yield and prevented the production of 4a
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(entry 4).15 While the amount of water was increased to 70 equiv, no reaction was
observed (entry 7).
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Table 3.Optimization of the amount of water in the conversion of 3aa
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Entry
H2O(eq)
4a
75%
39%
32%
0
5a
0
6a
0
1
2
0
1
0
0
3
10
10
20
40
70
0
61%
78%
23%
0
4b
5
0
0
52%
81%
0
6
0
7
0
0
aReaction conditions: 1,4ꢀenyne 3a(0.2 mmol),H2O(x equiv), TBAF (0.6 mmol) in THF (2 mL) at 40 oC for 24 h.
bDBU(1 equiv)
Under the optimized conditions, the desilylation products 5a
ꢀ
c
were obtained
in good yields by treating 1,4ꢀenynes
water in THF (Table 4, entries 1ꢀ3).
3 with TBAF in the presence of 40 equiv
Then, corresponding 1,4ꢀenyne products
3 could also be transformed to
naphthalene derivatives 6a in high yields by treated with TBAF in the presence
ꢀg
of DBU in THF with small amount of water (Table 4, entries 4ꢀ10).
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Table 4 Conversion of 1,4ꢀenynes 3 to 5 and 6a,b
O
COOMe
COOMe
O
condition A
condition B
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R
R
R
iPr
iPr
Si
CH3
6a-g
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5a-c
3
iPr
Yield (%)
81
1,4-Enyne Condition
Product
Entry
1
COOMe
3a
3b
A
A
5a
COOMe
2
3
5b
86
52
H3C
COOMe
A
B
B
3n
5c
F
CO2Me
4
5
3a
3n
6a
78
CH3
CO2Me
6b
55
83
F
CH3
CH3
CH3
CO2Me
3b
3l
B
B
6
7
8
6c
H3C
CO2Me
6d
85
83
CO2Me
6e
3m
B
B
Ph
CH3
CH3
CO2Me
6f
3q
3r
9
82
80
CO2Me
S
10
6g
B
CH3
a Reaction conditions A: 3 (0.2 mmol), H2O (40 equiv.), TBAF (0.6 mmol) in THF (2 mL) at 40 oC for 24 h. b
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Reaction conditions B: 3 (0.2 mmol), H2O (10 equiv.), TBAF (0.6 mmol) and DBU (1 equiv.) in THF (2 mL) at 40
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oC for 24 h.
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A
proposed mechanism for the conversion of 1,4ꢀenyne is shown in Figure 3.
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By treating 1,4ꢀenyne with TBAF, intermediate was generated, which was
I
converted to the desilylation product 5a with slightly big amount of water.
Meanwhile, allene intermediate II could be formed through 1,3ꢀhydrogen shift of
intermediate I. From allene intermediate II, the cyclization product 6a through
6ꢀπ electron cyclization and product 4a through 1,3ꢀhydrogen rearrangement
were obtained.
Figure 3.A proposed mechanism for the conversion of 1,4ꢀenyne
CONCLUSION
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In conclusion,
a
direct alkynylation of MBH carbonates with
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(triisopropylsilyl)acetylene catalyzed by Pd(OAc)2ꢀNHC complex was developed
“on water”. The reaction provided the corresponding 1,4ꢀenynes in good yields,
which could be further deprotected the silyl group to access 1,3ꢀenyne derivatives,
1,4ꢀenyne derivatives and 1ꢀmethylnaphthalene derivatives by changing the
addition of different amounts of water in a oneꢀpot reaction. The amount of water
in the solvent employed strongly influenced the subsequent conversion of
1,4ꢀenyne. Starting from 1,4ꢀenyne, the cyclization products were synthesized in
high yields.
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EXPERIMENTAL SECTION
Typical
procedure
for
[Pd-NHC]
catalyzed
alkynylation
of
Morita-Baylis-Hillman (MBH) carbonates with (triisopropylsilyl)acetylene:
Pd(OAc)2 (0.0045 g, 0.02 mmol, 10 mol %), NHC ligand L2 (0.0136 g, 0.04 mmol,
20 mol %) and tꢀBuOK (0.0054 g, 0.048 mmol, 24 mol %) were added to a dried
Schlenk tube under N2 atmosphere. THF (2 mL) was added, and the solution was
deoxygenated (three vacuum–argon cycles) at room temperature. The mixture was
stirred at room temperature for 2 h, and then the solvent was removed under reduced
pressure. Then, (triisopropylsilyl)acetylene (0.091 g, 0.5 mmol), MBH carbonates
2a-r (0.2 mmol) and 2 mL water were added under air atmosphere at room
temperature and heated at 70 ℃ for 10 h. The reaction mixture was cooled to room
temperature and extracted with dichloromethane (150 mL). The combined organic
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layers were dried over MgSO4, filtered and concentrated under reduced pressure to
give the crude product. The products 3a-r were isolated from the dark crude mixture
by flash column chromatography (the eluent used was 30:1 petroleum ether :
ethylacetate).
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The conversion of 1,4-enynes 3 into desilylation derivatives 5: The 1,4ꢀenyne 3a
(0.0712 g, 0.2 mmol) was dissolved in anhydrous THF (2 mL) under argon
atmosphere in a 25 mL Schlenk flask. Then, H2O (144 mg, 8 mmol) and TBAF (0.4
mL, 0.4 mmol, 1M in THF) were added into the solution and the mixture was stirred
for 24 h at 40 ℃. The reaction mixture was poured into water (100 mL) and extracted
with dichloromethane (150 mL). The combined organic layers were dried over
MgSO4, filtered and concentrated under reduced pressure to give the crude product.
The product 5 was isolated from the crude mixture by flash column chromatography
(the eluent used was 30:1 petroleum ether : ethyl acetate).
The conversion of 1,4-enynes 3 into 1-methylnaphthalene derivatives 6: The
1,4ꢀenyne 3a (0.0712 g, 0.2 mmol) was dissolved in anhydrous THF (2 mL) under
argon atmosphere in a 25 mL Schlenk flask. Then, H2O (36 mg, 2 mmol), DBU (30.4
mg, 0.2 mmol) and TBAF (0.4 mL, 0.4 mmol, 1M in THF) were added into the
solution and the mixture was stirred for 24 h at 40 ℃. The reaction mixture was
poured into water (100 mL) and extracted with dichloromethane (150 mL). The
combined organic layers were dried over MgSO4, filtered and concentrated under
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reduced pressure to give the crude product. The product 6 was isolated from the crude
mixture by flash column chromatography (the eluent used was 30:1 petroleum ether :
ethyl acetate).
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(E)-methyl-2-benzylidene-5-(triisopropylsilyl)pent-4-ynoate (3a): Colourless oil,
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50.4 mg, yield 71%. H NMR (300 MHz, CDCl3ꢀd1) δ 7.76 (s, 1H), 7.59 (d, J = 6.8
Hz, 2H), 7.40 (td, 3H), 3.85 (s, 3H), 3.43 (s, 2H), 1.06 (d, 21H) ppm; 13C {1H} NMR
(75 MHz, CDCl3ꢀd1) δ 167.7, 140.3, 134.9, 129.7, 128.9, 128.5, 127.9, 105.6, 81.4,
52.2, 19.4, 18.6, 11.2 ppm; HRMSꢀEI (m/z): calcd for C22H32O2Si, [M]+ : 356.2172;
found, 356.2177.
(E)-methyl-2-(4-methylbenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3b):
Colourless oil, 62 mg, yield 84%. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.74 (s, 1H), 7.50
(d, J = 8.1 Hz, 2H), 7.22 (d, J = 8.0 Hz, 2H), 3.84 (s, 3H), 3.44 (s, 2H), 2.38 (s, 3H),
1.06 (d, J = 2.8 Hz, 21H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.8, 140.4,
139.2, 132.1, 129.8, 129.2, 127.0, 105.8, 81.2, 52.1, 21.3, 19.4, 18.5, 11.2 ppm;
HRMSꢀAPCI (m/z): calcd for C23H35O2Si, [M+H]+ : 371.2395; found, 371.2400.
(E)-methyl-2-(4-chlorobenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3c):
Colourless oil, 71.0 mg, yield 91%. IR (KBr, cmꢀ1):2943, 2891, 2865, 2172, 1720,
1636, 1592, 1463, 1219, 1014. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.69 (s, 1H), 7.53 (d,
J = 8.5 Hz, 2H), 7.37 (d, J = 8.5 Hz, 2H), 3.85 (s, 3H), 3.40 (s, 2H), 1.05 (d, J = 2.5
Hz, 21H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.4, 138.9, 134.9, 133.4,
131.0, 128.7, 128.5, 105.1, 81.8, 52.3, 19.3, 18.5, 11.2 ppm; HRMSꢀAPCI (m/z):
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calcd for C22H32O2ClSi, [M+H]+ : 391.1853; found, 391.1854.
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(E)-methyl-2-(2-methylbenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3d):
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Colourless oil, 53.3 mg, yield 72%. H NMR (300 MHz, CDCl3ꢀd1) δ 7.81 (s, 1H),
7.56 – 7.51 (m, 1H), 7.22 (td, J = 7.0, 3.6 Hz, 3H), 3.85 (s, 3H), 3.29 (s, 2H), 2.30 (s,
3H), 1.06 (d, J = 3.2 Hz, 21H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.5,
139.3, 137.0, 134.3, 130.0, 128.9, 128.8, 128.8, 125.8, 105.9, 81.2, 52.1, 19.9, 19.4,
18.6, 11.2 ppm; HRMSꢀAPCI (m/z): calcd for C23H35O2Si, [M+H]+ : 371.2397; found,
371.2401.
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(E)-methyl-2-(3-methylbenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3e):
1
Colourless oil, 54.8 mg, yield 74%. H NMR (300 MHz, CDCl3ꢀd1) δ 7.73 (s, 1H),
7.38 (d, 2H), 7.29 (t, J = 7.5 Hz, 1H), 7.17 (d, J = 7.5 Hz, 1H), 3.84 (s, 3H), 3.42 (s,
2H), 2.38 (s, 3H), 1.06 (d, J = 2.7 Hz, 21H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1)
δ 167.7, 140.4, 138.2, 134.9, 130.2, 129.7, 128.4, 127.7, 126.9, 105.7, 81.2, 52.1, 21.4,
19.4, 18.6, 11.2 ppm; HRMSꢀAPCI (m/z): calcd for C23H35O2Si, [M+H]+ : 371.2396;
found, 371.2400.
(E)-methyl-2-(3-fluorobenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3f):
Colourless oil, 53.9 mg, yield 72%. IR (KBr, cmꢀ1):2943, 2865, 2173, 1720, 1637,
1583, 1486, 1286, 1207, 1154. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.70 (s, 1H), 7.41 –
7.31 (m, 3H), 7.11 – 7.02 (m, 1H), 3.85 (s, 3H), 3.42 (s, 2H), 1.05 (d, J = 2.4 Hz, 21H)
ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.3, 164.3, 161.1, 138.9, 138.8, 137.1,
137.0, 130.1, 130.0, 129.1, 125.5, 125.4, 116.5, 116.1, 115.7, 105.0, 81.9, 77.4, 77.0,
76.58, 52.3, 19.3, 18.5, 11.2 ppm; HRMSꢀAPCI (m/z): calcd for C22H32O2FSi,
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[M+H]+ : 375.2145; found, 375.2150.
(E)-methyl-2-(4-bromobenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3g):
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Colourless oil , 60.8 mg, yield 70%. IR (KBr, cmꢀ1):2942, 2864, 2172, 1720, 1636,
1587, 1488, 1204, 1074. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.67 (s, 1H), 7.55 – 7.51
(m, 2H), 7.49 – 7.43 (m, 2H), 3.85 (s, 3H), 3.39 (s, 2H), 1.05 (d, J = 2.6 Hz, 21H)
ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.4, 138.9, 133.9, 131.7, 131.2, 128.7,
123.3, 105.1, 81.9, 52.3, 19.3, 18.5, 11.2 ppm; HRMSꢀAPCI (m/z): calcd for
C22H32O2BrSi, [M+H]+ : 435.1347; found, 435.1349.
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(E)-methyl-2-(2-fluorobenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3h):
Colourless oil, 57.6 mg, yield 77%. IR (KBr, cmꢀ1):2943, 2865, 2173, 1723, 1640,
1611, 1578, 1294, 1211, 1102. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.75 (s, 1H), 7.60 (d,
J = 7.0 Hz, 2H), 7.40 (dd, J = 12.1, 4.4 Hz, 3H), 4.25 (t, J = 6.5 Hz, 2H), 3.42 (s, 2H),
1.76 – 1.67 (m, 2H), 1.47 (dd, J = 15.0, 7.4 Hz, 2H), 1.06 (d, J = 2.6 Hz, 21H), 0.97 (t,
J = 7.4 Hz, 3H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.1, 162.3, 158.9,
132.8, 132.7, 130.9, 130.8, 130.6, 129.9, 124.1, 124.0, 123.1, 122.9, 115.7, 115.4,
105.2, 81.7, 52.3, 19.6, 18.5, 11.2 ppm; HRMSꢀAPCI (m/z): calcd for C22H32O2FSi,
[M+H]+ : 375.2145; found, 375.2150.
(E)-methyl-2-(3-methoxybenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3i):
Colourless oil, 66.4 mg, yield 86%. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.73 (s, 1H),
7.31 (t, J = 7.9 Hz, 1H), 7.16 (d, J = 7.6 Hz, 1H), 7.10 (s, 1H), 6.91 (d, J = 8.2 Hz,
1H), 3.84 (s, 3H), 3.83 (s, 3H), 3.44 (s, 2H), 1.05 (d, J = 2.4 Hz, 21H) ppm; 13C {1H}
NMR (75 MHz, CDCl3ꢀd1) δ 167.6, 159.6, 140.2, 136.2, 129.5, 128.2, 122.1, 115.1,
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114.4, 105.6, 81.3, 55.2, 52.2, 19.5, 18.5, 11.2 ppm; HRMSꢀAPCI (m/z): calcd for
C23H35O3Si, [M+H]+ : 387.2343; found, 387.2350.
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(E)-methyl-2-(3-cyanobenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3j):
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Colourless oil, 41.1 mg, yield 54%. IR (KBr, cmꢀ1):2942, 2864, 2232, 2172, 1720,
1484, 1277, 1232, 1206, 1120. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.85 (s, 1H), 7.80 (d,
J = 7.9 Hz, 1H), 7.68 (s, 1H), 7.65 (d, J = 7.8 Hz, 1H), 7.54 (d, J = 7.8 Hz, 1H), 3.86
(s, 3H), 3.39 (s, 2H), 1.04 (s, 21H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 166.9,
137.5, 136.2, 133.7, 132.8, 132.2, 130.5, 129.4, 118.2, 113.1, 104.3, 82.5, 52.5, 19.3,
18.5, 11.1 ppm; HRMSꢀAPCI (m/z): calcd for C23H32O2NSi, [M+H]+ : 382.2191;
found, 382.2196.
(E)-methyl-2-(3-(trifluoromethyl)benzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3k): Colourless oil , 75.5 mg, yield 89%. IR (KBr, cmꢀ1):2944, 2866, 2173, 1722,
1
1463, 1437, 1217, 1199, 1076. H NMR (300 MHz, CDCl3ꢀd1) δ 7.79 (dd, J = 11.7,
5.3 Hz, 3H), 7.62 (d, J = 7.8 Hz, 1H), 7.53 (t, J = 7.7 Hz, 1H), 3.86 (s, 3H), 3.41 (s,
2H), 1.05 (d, J = 2.2 Hz, 21H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.2,
138.4, 135.7, 132.7, 131.4, 130.9, 129.8, 129.1, 126.3, 126.3, 125.5, 125.4, 122.0,
104.6, 82.1, 52.3, 19.3, 18.5, 11.2 ppm; HRMSꢀAPCI (m/z): calcd for C23H32O2F3Si,
[M+H]+ : 425.2112; found, 425.2118.
(E)-methyl-2-(naphthalen-2-ylmethylene)-5-(triisopropylsilyl)pent-4-ynoate (3l):
Colourless oil, 62.5 mg, yield 77%.IR (KBr, cmꢀ1): 3056, 2941, 2864, 2172, 1712,
1635, 1595, 1504, 1463, 1257. 1H NMR (300 MHz, CDCl3ꢀd1) δ 8.10 (s, 1H), 7.90 (s,
1H), 7.84 (dd, J = 8.6, 4.4 Hz, 3H), 7.64 (dd, J = 8.6, 1.6 Hz, 1H), 7.54 – 7.47 (m, 2H),
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3.87 (s, 3H), 3.51 (s, 2H), 1.08 (d, J = 2.9 Hz, 21H) ppm; C {1H} NMR (75 MHz,
CDCl3ꢀd1) δ 167.7, 140.3, 133.2, 132.5, 129.6, 128.5, 128.2, 128.2, 127.7, 127.0,
126.9, 126.5, 105.7, 81.5, 52.2, 19.6, 18.6, 11.3 ppm; HRMSꢀAPCI (m/z): calcd for
C26H35O2Si, [M+H]+ : 407.2397; found, 407.2400.
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(E)-methyl-2-([1,1'-biphenyl]-4-ylmethylene)-5-(triisopropylsilyl)pent-4-ynoate
(3m): Colourless oil, 73.4 mg, yield 85%. IR (KBr, cmꢀ1):3056, 3030, 2941, 2864,
2172, 1712, 1633, 1603, 1488, 1205. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.81 (s, 1H),
7.66 (ddd, J = 9.8, 7.1, 5.9 Hz, 6H), 7.51 – 7.44 (m, 2H), 7.42 – 7.35 (m, 1H), 3.88 (s,
3H), 3.51 (s, 2H), 1.09 (s, 21H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.7,
141.8, 140.3, 139.9, 133.9, 130.34, 128.9, 127.9, 19.5, 18.6, 11.3 ppm; HRMSꢀAPCI
(m/z): calcd for C28H37O2Si, [M+H]+ : 433.2555; found, 433.2557.
(E)-methyl-2-(4-fluorobenzylidene)-5-(triisopropylsilyl)pent-4-ynoate
(3n):
Colourless oil , 56.1 mg, yield 75%. IR (KBr, cmꢀ1): 2943, 2865, 2172, 1719, 1601,
1509, 1463, 1289, 1201, 1160. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.71 (s, 1H), 7.59 (dd,
J = 8.6, 5.5 Hz, 2H), 7.10 (dd, J = 12.0, 5.3 Hz, 2H), 3.85 (s, 3H), 3.41 (s, 2H), 1.05
(d, J = 2.5 Hz, 21H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.5, 161.3, 139.1,
131.8, 131.7, 131.1, 131.1, 127.8, 115.8, 115.5, 105.3, 81.6, 52.2, 19.3, 18.5, 11.2
ppm; HRMSꢀAPCI (m/z): calcd for C22H32O2FSi, [M+H]+ : 375.2146; found,
375.2150.
(E)-tert-butyl-2-benzylidene-5-(triisopropylsilyl)pent-4-ynoate (3o): Colourless
oil , 58.1 mg, yield 73%. IR (KBr, cmꢀ1):2958, 2943, 2892, 2865, 2172, 1716, 1635,
1
1463, 1217, 1199. H NMR (300 MHz, CDCl3ꢀd1) δ 7.67 (s, 1H), 7.57 (d, J = 7.0 Hz,
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2H), 7.43 – 7.33 (m, 3H), 3.36 (s, 2H), 1.56 (s, 9H), 1.08 (d, J = 3.2 Hz, 21H) ppm;
13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 166.2, 139.1, 135.42, 129.8, 129.6, 128.6,
128.4, 106.1, 81.0, 80.8, 28.1, 19.5, 18.6, 11.3 ppm; HRMSꢀAPCI (m/z): calcd for
C25H38O2NaSi, [M+Na]+ : 421.2531; found, 421.2533.
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(E)-butyl-2-benzylidene-5-(triisopropylsilyl)pent-4-ynoate (3p): Colourless oil ,
59.7 mg, yield 75%.IR (KBr, cmꢀ1): 2943, 2892, 2865, 2173, 1711, 1636, 1463, 1391,
1
1216, 1162. H NMR (300 MHz, CDCl3ꢀd1) δ 7.75 (s, 1H), 7.60 (d, J = 7.0 Hz, 2H),
7.40 (dd, J = 12.1, 4.4 Hz, 3H), 4.25 (t, J = 6.5 Hz, 2H), 3.42 (s, 2H), 1.76 – 1.67 (m,
2H), 1.47 (dd, J = 15.0, 7.4 Hz, 2H), 1.06 (d, J = 2.6 Hz, 21H), 0.97 (t, J = 7.4 Hz, 3H)
ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.3, 140.1, 135.1, 129.7, 128.9, 128.5,
128.3, 105.8, 81.2, 65.0, 30.8,19.4, 19.3, 18.6, 13.8, 11.2 ppm; HRMSꢀAPCI (m/z):
calcd for C25H39O2Si, [M+H]+ : 399.2707; found, 399.2714.
(2E,4E)-methyl-5-phenyl-2-(3-(triisopropylsilyl)prop-2-yn-1-yl)penta-2,4-dienoat
e (3q): Colourless oil, 45.8 mg, yield 60%. IR (KBr, cmꢀ1): 2941, 2864, 2171, 1711,
1623, 1462, 1383, 1202, 1075. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.42 (d, J = 7.5 Hz,
2H), 7.34 (d, J = 11.5 Hz, 1H), 7.30 – 7.22 (m, 3H), 7.16 (dd, J = 11.5, 7.5 Hz, 1H),
6.83 (d, J = 15.3 Hz, 1H), 3.73 (s, 3H), 3.41 (s, 2H), 0.93 (s, 21H) ppm; 13C {1H}
NMR (75 MHz, CDCl3ꢀd1) δ 167.6, 140.7, 140.1, 136.3, 129.0, 128.7, 127.3, 126.4,
123.6, 105.5 81.1, 52.1, 18.5, 18.0, 11.2ppm; HRMSꢀAPCI (m/z): calcd for
C48H68O4NaSi2, [2M+Na]+ : 787.4548; found, 787.4536.
(E)-methyl-2-(thiophen-2-ylmethylene)-5-(triisopropylsilyl)pent-4-ynoate
(3r):
Colourless oil, 56.5mg, yield 78%. IR (KBr, cmꢀ1): 2943, 2864, 2172, 1713, 1623,
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1463, 1421, 1273, 1207, 1088. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.78 (s, 1H), 7.45 (d,
1H), 7.38 (d, 1H), 7.07 – 7.02 (m, 1H), 3.76 (s, 3H), 3.54 (s, 2H), 0.93 (s, 21H)ppm;
13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.7, 137.7, 132.6, 132.1, 129.8, 127.7, 124.6,
104.2, 80.9, 52.3, 19.4, 18.6, 11.2 ppm; HRMSꢀAPCI (m/z): calcd for
C40H60O4NaS2Si2, [2M+Na]+ : 747.3363; found, 747.3358.
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(E)-methyl-2-benzylidenepent-3-ynoate (4a): Colourless oil, 30.0 mg, yield 75%. IR
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(KBr, cmꢀ1):3025, 2951, 2851, 2227, 1721, 1597, 1447, 1434, 1261, 1207, 1141. H
NMR (300 MHz, CDCl3ꢀd1) δ 8.00 (dd, J = 6.6, 3.0 Hz, 2H), 7.85 (s, 1H), 7.46 – 7.34
(m, 3H), 3.86 (s, 3H), 2.17 (s, 3H) ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 166.6,
144.7, 134.5, 130.3, 130.1, 128.4, 113.2, 95.6, 75.4, 52.7, 5.0 ppm; HRMSꢀAPCI
(m/z): calcd for C26H24O4Na, [2M+Na]+ : 423.1567; found, 423.1565.
(E)-methyl-2-benzylidenepent-4-ynoate (5a): Colourless oil, 32.4 mg, yield 81%. IR
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(KBr, cmꢀ1):3294, 2951, 2863, 2119, 1715, 1635, 1435, 1271, 1222, 1090. H NMR
(300 MHz, CDCl3ꢀd1) δ 7.79 (s, 1H), 7.53 (d, J = 7.3 Hz, 2H), 7.41 (dt, J = 8.5, 6.9
Hz, 3H), 3.87 (s, 3H), 3.38 (d, J = 2.6 Hz, 2H), 2.08 (t, J = 2.7 Hz, 1H) ppm; 13C {1H}
NMR (75 MHz, CDCl3ꢀd1) δ 167.5, 140.9, 134.8, 129.5, 129.1, 128.6, 127.3, 81.6,
68.8, 52.3, 17.9 ppm; HRMSꢀAPCI (m/z): calcd for C26H24O4Na, [2M+Na]+ :
423.1567; found, 423.1567.
(E)-methyl 2-(4-methylbenzylidene)pent-4-ynoate (5b)：Colourless oil, 36.8 mg,
yield 86%. IR (KBr, cmꢀ1): 3295, 2951, 2864, 2120, 1716, 1635, 1512, 1463, 1270,
1117. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.76 (s, 1H), 7.43 (d, J = 8.0 Hz, 2H), 7.24 (d,
J = 8.0 Hz, 2H), 3.86 (s, 3H), 3.39 (d, J = 2.5 Hz, 2H), 2.39 (s, 3H), 2.07 (t, J = 2.5
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Hz, 1H)ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.7, 141.0, 139.4, 132.0, 129.7,
129.4, 126.4, 81.8, 68.7, 52.3, 21.4, 17.9ppm; HRMSꢀAPCI (m/z): calcd for C14H15O2,
[M+H]+ : 215.1066; found, 215.1068.
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(E)-methyl 2-(4-fluorobenzylidene)pent-4-ynoate (5c):Colourless oil, 22.7 mg,
yield 52%. IR (KBr, cmꢀ1):3294, 2951, 2865, 2119, 1715, 1601, 1509, 1463, 1289,
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1087. H NMR (300 MHz, CDCl3ꢀd1) δ 7.74 (s, 1H), 7.53 (dd, J = 8.6, 5.5 Hz, 2H),
7.12 (t, J = 8.6 Hz, 2H), 3.87 (s, 3H), 3.36 (d, J = 2.6 Hz, 2H), 2.09 (t, J = 2.7 Hz,
1H)ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.4, 164.7, 161.4, 139.7, 131.7,
131.6, 130.9, 130.9 , 127.2, 127.1, 115.9, 115.7, 81.4, 69.0, 52.4, 17.8ppm;
HRMSꢀAPCI (m/z): calcd for C13H12O2F, [M+H]+ : 219.0816; found, 219.0818.
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Methyl-4-methyl-2-naphthoate (6a): Colourless oil, 31.2 mg, yield 78%. H NMR
(300 MHz, CDCl3ꢀd1) δ 8.47 (s, 1H), 8.02 (d, J = 8.1 Hz, 1H), 7.96 (d, J = 8.1 Hz,
1H), 7.91 (s, 1H), 7.64 (t, J = 7.3 Hz, 1H), 7.55 (t, J = 7.3 Hz, 1H), 3.98 (s, 3H), 2.73
(s, 3H)ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.4, 134.8, 134.8, 132.7, 130.0,
129.5, 128.1, 126.9, 126.3, 125.6, 124.1, 52.2, 19.4 ppm; HRMSꢀAPCI (m/z): calcd
for C13H13O2, [M+H]+ : 201.0910; found, 201.0908.
Methyl-6-fluoro-4-methyl-2-naphthoate (6b): Colourless oil, 24.0 mg, yield 55%.
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IR (KBr, cmꢀ1): 2951, 2864, 1719, 1636, 1508, 1437, 1234, 1200, 1103, 1003. H
NMR (300 MHz, CDCl3ꢀd1) δ 8.45 (s, 1H), 8.04 – 7.85 (m, 2H), 7.60 (dd, J = 10.8,
2.1 Hz, 1H), 7.32 (td, J = 8.7, 2.1 Hz, 1H), 3.97 (s, 3H), 2.67 (s, 3H)ppm; 13C {1H}
NMR (75 MHz, CDCl3ꢀd1) δ 167.2, 163.8, 160.5, 136.0, 134.2, 132.6, 132.5, 129.6,
129.3, 126.5, 116.8, 116.5, 108.2, 107.9, 52.2, 19.3 ppm; HRMSꢀAPCI (m/z): calcd
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for C13H12O2F, [M+H]+ : 219.0816; found, 219.0818.
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Methyl-4,6-dimethyl-2-naphthoate (6c): Colourless oil, 35.5 mg, yield 83%. H
NMR (300 MHz, CDCl3ꢀd1) δ 8.42 (s, 1H), 7.88 (s, 1H), 7.85 (d, J = 8.3 Hz, 1H),
7.78 (s, 1H), 7.38 (d, J = 8.3 Hz, 1H), 3.97 (s, 3H), 2.70 (s, 3H), 2.57 (s, 3H)ppm; 13C
{1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.5, 138.2, 135.0, 134.0, 130.8, 129.8, 129.3,
128.5, 126.1, 125.7, 123.3, 52.1, 22.2, 19.4 ppm; HRMSꢀAPCI (m/z): calcd for
C14H15O2, [M+H]+ : 215.1066; found, 215.1068.
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Methyl-4-methylanthracene-2-carboxylate (6d): Colourless oil, 42.5 mg, yield 85%.
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IR (KBr, cmꢀ1): 3051, 2978, 2929, 1712, 1466, 1453, 1301, 1274, 1226, 1107. H
NMR (300 MHz, CDCl3ꢀd1) δ 8.99 – 8.90 (m, 1H), 8.47 (s, 1H), 8.11 (s, 1H), 7.99 –
7.90 (m, 1H), 7.81 – 7.75 (m, 2H), 7.71 – 7.62 (m, 2H), 4.00 (s, 3H), 3.19 (s, 3H)ppm;
13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.1, 136.0, 134.3, 133.3, 133.2, 131.1, 130.7,
129.4, 128.9, 128.3, 127.9, 127.8, 126.9, 126.0, 52.2, 27.4 ppm; HRMSꢀAPCI (m/z):
calcd for C17H15O2, [M+H]+ : 251.1066; found, 251.1070.
Methyl-4-methyl-6-phenyl-2-naphthoate (6e): Colourlessoil , 45.8 mg, yield 83%.
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IR (KBr, cmꢀ1): 3029, 2979, 2931, 2864, 1710, 1608, 1487, 1373, 1256, 1107. H
NMR (300 MHz, CDCl3ꢀd1) δ 8.49 (s, 1H), 8.18 (s, 1H), 8.03 (d, J = 8.5 Hz, 1H),
7.94 (s, 1H), 7.81 (dd, J = 8.5, 1.3 Hz, 1H), 7.74 (d, J = 7.5 Hz, 2H), 7.52 (t, J = 7.5
Hz, 2H), 7.43 (d, J = 7.5 Hz, 1H), 3.99 (s, 3H), 2.78 (s, 3H)ppm; 13C {1H} NMR (75
MHz, CDCl3ꢀd1) δ 167.4, 141.1, 140.9, 135.0, 135.0, 131.8, 130.6, 129.3, 129.0,
127.8, 127.6, 126.9, 126.1, 126.1, 122.2, 52.2, 19.5 ppm; HRMSꢀAPCI (m/z): calcd
for C19H17O2, [M+H]+ : 277.1223; found, 277.1226.
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Methyl-2-methyl-[1,1'-biphenyl]-4-carboxylate (6f): Colourless oil, 37.1 mg, yield
82%. 1H NMR (300 MHz, CDCl3ꢀd1) δ 7.89 (s, 1H), 7.83 (d, J = 8.0 Hz, 1H), 7.37 (t,
J = 7.2 Hz, 2H), 7.31 (d, J = 7.2 Hz, 1H), 7.27 – 7.17 (m, 3H), 3.87 (s, 3H), 2.25 (s,
3H)ppm; 13C {1H} NMR (75 MHz, CDCl3ꢀd1) δ 167.2, 146.6, 141.0, 135.7, 131.5,
129.9, 128.9, 128.2, 127.4, 127.0, 100.0, 52.1, 20.5 ppm; HRMSꢀAPCI (m/z): calcd
for C15H15O2, [M+H]+ : 227.1066; found, 227.1064.
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Methyl-4-methylbenzo[b]thiophene-6-carboxylate (6g): Colourless oil, 33.0 mg,
1
yield 80%. H NMR (300 MHz, CDCl3ꢀd1) δ 8.45 (s, 1H), 7.82 (s, 1H), 7.64 (d, J =
13
5.5 Hz, 1H), 7.43 (d, J = 5.5 Hz, 1H), 3.95 (s, 3H), 2.65 (s, 3H)ppm; C {1H} NMR
(75 MHz, CDCl3ꢀd1) δ 167.3, 142.5, 139.3, 132.8, 129.8, 126.0, 125.2, 122.3, 122.0,
52.1, 19.6 ppm; HRMSꢀAPCI (m/z): calcd for C11H11O2S, [M+H]+ : 207.0474; found,
207.0473.
Acknowledgements
AcknowledgementsꢀꢀꢀꢀWe thank the National Natural Science Foundation of China
(Nos. 21420102003 and 21232008), the Ministry of Science and Technology of China
(973 Program 2011CB808600), Shandong Province independent innovation and
achievements transformation of special (2014XGC06001) and the Chinese Academy
of Sciences for financial support.
Supporting information
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The characterization data is available free of charge via the Internet at
http://pubs.acs.org/.
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