Silver(I)-catalyzed reaction of terminal alkynes with (diacetoxyiodo) benzene: A convenient, efficient and clean preparation of α-acetoxy ketones

Article abstract of DOI:10.1016/j.tet.2013.04.122

Silver(I)-catalyzed reaction of terminal alkynes with (diacetoxyiodo) benzene in wet acetonitrile at room temperature afforded the corresponding α-acetoxy ketones in 55-93% yields. The salient features of this reaction are the effective utilization of PhI

Full text of DOI:10.1016/j.tet.2013.04.122

Tetrahedron 69 (2013) 5937e5944
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Silver(I)-catalyzed reaction of terminal alkynes with (diacetoxyiodo)
benzene: a convenient, efficient and clean preparation of a-acetoxy
ketones
,
b
,
a
Guisheng Deng a , Jing Luo
*
a College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081, China
b Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Hunan Normal University), Ministry of Education, Changsha,
Hunan 410081, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Silver(I)-catalyzed reaction of terminal alkynes with (diacetoxyiodo)benzene in wet acetonitrile at room
temperature afforded the corresponding a-acetoxy ketones in 55e93% yields. The salient features of this
reaction are the effective utilization of PhI(OAc)2, high chemoselectivity, excellent yields, mild reaction
conditions and the experimental simplicity. A plausible mechanism has been proposed based on the
experimental results.
Received 4 February 2013
Received in revised form 17 April 2013
Accepted 26 April 2013
Available online 2 May 2013
Ó 2013 Elsevier Ltd. All rights reserved.
Keywords:
Alkynes
(Diacetoxyiodo)benzene
a
-Acetoxy ketones
Silver(I)
Catalysis
1. Introduction
benzene (DIB)-induced oxidation of terminal alkynes in different
acids (e.g., H2SO4,19 HOAc20,21) has been confirmed to be an effec-
a
-Acetoxyketones are one class of useful and important syn-
tive procedure for synthesis of a-acetoxy ketones. However, despite
thetic intermediates.1e7 To date many procedures have been de-
veloped to prepare these compounds, such as the anodic oxidation
of enol acetates in acetic acid,6 acetolysis of epoxides in the cho-
these efforts, the drawback of the above-mentioned approaches is
low chemoselectivity,19 higher reaction temperature,20,21 excessive
usage of PhI(OAc)2,21 lower yield19 or the limitation on use of only
aliphatic terminal alkynes as substrates.18 Therefore, research to-
wards exploring new activators for the hypervalent iodine(III)-
mediated direct transformation of terminal alkynes (particularly,
lestane series,7 the acetolysis of -bromo ketones,8 the acetylation
a
of
of
a
a
-hydroxyl ketones,9 the metal-catalyzed OeH insertion reaction
-diazo ketones with carboxylic acids,10 the conjugate addition
of acyloxy groups to alkynylphenyliodonium tetrafluoroborates
under both basic and acidic conditions,11 the oxidation of trime-
thylsilyl enol ethers with lead tetraacetate12 and the oxidation of
ketones with lead tetraacetate6,13 or with manganese(III) acetate in
acetic acid.14 Some other oxidants were also used in the trans-
formation of ketones into
suffered from multi-steps, the low yields or environmental
problem.
terminal aryl alkynes) to the corresponding
still very necessary and exigent.
a-acetoxy ketones is
In view of the catalytic role22 of the silver(I) ion in the addition
of various reagents across carbonecarbon multiple bonds and our
interest,23 we envisioned that a suitable silver(I) ion could improve
the reaction of terminal alkynes with PhI(OAc)2 via interaction of
the carbonecarbon triple bond and the metal ion to provide a more
a
-acetoxy ketones.15,16 However, they
efficient access to a-acetoxy ketones.
Recently, one-pot preparation of
a-acetoxy ketones from ter-
minal alkynes, has been paid many attention,17 such as the mer-
cury(II) acetate-catalyzed one-pot oxidation of terminal alkynes by
sodium perborate in acetic acid.18 In particular, (diacetoxyiodo)
2. Results and discussion
In the initial stages of this investigation, phenylacetylene was
selected as the standard substrate to establish an effective reaction
system based on the above-mentioned protocol. The mixture of
phenylacetylene 1a (1 equiv) and PhI(OAc)2 (1 equiv) in wet
* Corresponding author. Tel.: þ86 731 8887 2531; e-mail addresses: gsdeng@
hunnu.edu.cn, g_s_deng@sina.com (G. Deng).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.04.122

5938
G. Deng, J. Luo / Tetrahedron 69 (2013) 5937e5944
acetonitrile was treated with or without 10 mol % silver acetate at
25 ꢀC for 14 h. When no silver(I) compounds were used, the desired
product 3a was obtained only in 9% yield (Table 1, entry 1). Phe-
lower than that obtained in 10 mol % AgOAc-catalyzed system
when using 20 mol %, 30 mol %, 50 mol % and 100 mol % AgOAc
(Table 1, entries 21e24). Obviously, the best result was obtained in
the presence of 10 mol % silver acetate. Only 1 equiv of PhI(OAc)2
was required to accomplish the reaction.
nylacetylene 1a was completely converted to a-acetoxy acetophe-
none 3a in the presence of 10 mol % CH3COOAg in high isolated
yield (up to 93%) without by-product (Table 1, entry 2). A compli-
cated reaction was observed when CF3COOAg, CF3SO3Ag or AgF
were utilized as catalyst. In the cases, the desired product 3a was
obtained in low yield (Table 1, entries 3e5). When AgCl, AgBr, AgI,
Ag2O and Ag2SO4 were employed, the heterogeneous reactions
cleanly afforded product 3a in 76%, 79%, 73%, 80% and 75% yields,
respectively (Table 1, entries 6e10). Among the investigated sil-
ver(I) compounds, the best result was obtained from silver acetate.
A survey of solvents indicated that the reaction is sensitive to
the reaction medium. For example, silver acetate-catalyzed re-
action in wet THF afforded the desired product 3a in poor yield
because of the formation of unknown by-product (Table 1, entry
11). Moderate yields were obtained when wet dioxane, CH2Cl2,
CHCl3, benzene, toluene and MeOH were chosen as solvents (Table
1, entries 12e17). The yield dramatically decreased when the re-
action was carried out in dry acetonitrile (Table 1, entry 18). The
result strongly suggests that a small amount of water is extremely
important but is not necessary to this transformation. Wet aceto-
nitrile proved to be optimal for the reaction (Table 1, entry 2).
It is well-known that more catalysts can accelerate reactions.
Thus, we began to investigate the effect of the amount of silver
acetate on the reaction to determine an optimal loading of the
catalyst. Utilization of 1 mol %, 5 mol % and 10 mol % silver acetate in
wet CH3CN gave 3a in 52%, 82% and 93% yields, respectively (Table
1, entries 19e20 and 2). As expected, the yields were accelerated.
However, in contrast with the results anticipated, the yields were
Under these optimized conditions, the reaction of various al-
kynes with PhI(OAc)2 afforded expected products 3. These results
were summarized in Table 2. The use of phenylacetylene as a sub-
strate gave a-acetoxy acetophenone in 93% yield (Table 2, entry 1).
When aryl acetylenes bearing electron-rich groups, such as alkyl
and alkoxy at the 3 or 4-position of benzene ring were employed as
substrates, a longer time was needed for complete reaction (Table 2,
entries 2e6). When the groups were changed to electron-deficient
groups, such as halo and nitro at the 2 or 4-position of benzene ring,
the reaction gave rise to the corresponding product 3 in excellent
yields in relatively short reaction time (Table 2, entries 7e9). The
reaction of aliphatic terminal alkynes, such as 1-hexyne also
afforded desired product 3j in 55% isolated yield and 2-oxohexane-
1,1-diyl diacetate as by-product in 18% isolated yield (Table 2, entry
10), however, the reactivity is lower than that of phenylacetylene
and the aryl alkynes with electron-deficient groups at benzene
ring. Additionally, a variety of 1-propyne derivatives, such as 3-
bromo-1-propyne and propynyl ether or amine, were trans-
formed to the corresponding products in moderate to good yields
(Table 2, entries 11e16). In addition, the compound 1q with two
terminal acetylenic bonds is also a suitable substrate. PhI(OAc)2
(2 equiv) reacted with the two terminal triple bonds, yielding
diacetoxy diketone 3q as unique product without -acetoxy ketone
a, -
a0
a
4 with one triple bond intact (Table 2, entry 17). Obviously, the
result is different from that reported in literature.21 A variety of
terminal alkynes were cleanly converted to the corresponding a-
acetoxy ketones without the formation of by-product except p-
methoxy phenylacetylene 1f and 1-hexyne 1j (Table 2, entries 6
and 10). However, 1-phenyl-1-butyne 1r failed to afford the cor-
responding product (Table 2, entry 18). Moreover, the reaction
showed tolerance towards the internal carbonecarbon triple or
double bond and aldehyde group (Table 2, entries 12, 13 and 15).
Table 1
Optimization of reaction conditionsa
O
Ag(I)
OAc
Ph
+ PhI(OAc)2
Ph
solvent, 25 oC, 14 hrs
It is generally accepted that the synthesis of
proceeds through a Michael-type addition of a nucleophile to the
electron-deficient -carbons of the alkynyliodonium salts 6, which
a-acetoxy ketones
1a
2
3a
Entry
Ag(I)
The amount of
catalyst (mol %)
Solventb
Yieldc (%)
b
are produced by the reaction of terminal alkynes with
PhI(OAc)2.11,21,24 If so, both an acetate anion and water should be
considered as possible nucleophiles in this reaction. The reaction of
2-propyn-1-ol 1s provided 2-oxopropane-1,3-diyl diacetate 3s as
a unique product without the expected 3-hydroxy-2-oxopropyl
acetate 3s-OH (Table 2, entry 19), which should be produced by
a Michael-type addition of water to the corresponding alkynylio-
donium salts 6s via intermediate 8s-OH (Scheme 1, Eq. 1).11,21,24 The
transformation of 3s-OH into 3s has been excluded because acet-
ylation of hydroxy groups did not take place by the reaction of 3s-
OH with 1 equiv of HOAc under these conditions (Scheme 1, Eq. 2).
This indicates that the reaction do not involve the formation of 3s-
OH via intermediate 8s-OH. More importantly, in the absence of
water the reaction of 2-propyn-1-ol 1s gave 3s in similar yield (79%)
(Scheme 1, Eq. 3) albeit longer reaction time was required com-
paring with the reaction in wet CH3CN (Table 2, entry 19). There-
fore, there is obvious evidence against the addition of water as
a nucleophile in this reaction. To explain the transformation of the
hydroxy group of 1s to an acetoxy group under these conditions, we
1
2
3
4
5
6
7
8
None
d
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
THF
Dioxane
CH2Cl2
CHCl3
Benzene
Toluene
MeOH
Dry CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
9
93
44d
38d
52d
76
79
73
80
75
10d
60
62
59
52
64
55
35e
25
43
51
60
82
52
CH3COOAg
CF3COOAg
CF3SO3Ag
AgF
AgCl
AgBr
AgI
Ag2O
Ag2SO4
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
CH3COOAg
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
100
50
30
20
5
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
should consider
a reaction process involving a reactive in-
1
termediate that can undergo the acetylation of the hydroxy group.
We hereby propose an interpretation of a key intermediate, namely,
a
All reactions were performed by using phenylacetylene (1 mmol) and PhI(OAc)2
(1 mmol) in solvent (10 ml) at 25 ꢀC for 14 h.
(b
-acetoxyviny1)phenyliodonium acetates 8s,11 which may un-
b
Reaction was carried out in the solvent containing 1% water except dry solvent.
Isolated yields.
Unknown by-product was formed.
The reaction worked under anhydrous conditions.
dergo an intramolecular 1,4-shift of the acetyl group via a five-
membered transition state, shown by the arrow (Scheme 1, Eq.
4). Perhaps the intermediate 8s is produced by Michael-type
c
d
e

G. Deng, J. Luo / Tetrahedron 69 (2013) 5937e5944
5939
Table 2
Substrate scope of the PhI(OAc)2-mediated reaction of alkynesa
O
10 mol% CH3COOAg
+ PhI(OAc)2
R
OAc
wet CH3CN, 25 o
C
R
1
2
3
Entry
1
Substrate
React. time (h)
14
Product
Yieldb (%)
93
O
OAc
1a
1b
3a
3b
3c
O
OAc
2
3
4
18
18
20
87
85
83
O
OAc
O
1c
OAc
n-Pr
1d
n-Pr
3d
O
OAc
t
Bu
5
6
20
18
82
1e
t
Bu
3e
3f
O
OAc
72c
CH3O
CH3O
Cl
O
Cl
OAc
7
13
85
1g
3g
O
OAc
F
8
9
12
12
92
86
1h
F
3h
3i
O
OAc
O2N
1i
O2N
O
10
11
12
15
14
14
55d
86
OAc
1j
3j
3k
3l
O
Br
Br
OAc
O
1k
O
O
n-Pr
82
n-Pr
OAc
1l
Ph
O
OAc
13
14
Ph
O
18
14
75
87
1m
O
3m
3n
O
Ph
O
Ph
O
OAc
1n
O
O
O
OAc
15
16
20
18
60
CHO
1o
1p
CHO
O
3o
3p
Ph2N
64
Ph2N
OAc
(continued on next page)

5940
G. Deng, J. Luo / Tetrahedron 69 (2013) 5937e5944
Table 2 (continued )
Entry
Substrate
React. time (h)
Product
Yieldb (%)
O
O
O
O
OAc
OAc
17
26
57 (3q/4¼100:0)e
O
1q
O
3q
O
O
O
OAc
4
C2H5
18
48
14
d
df
1r
O
HO
19
83
OAc
AcO
1s
3s
a
Reaction conditions: alkynes (1 mmol), PhI(OAc)2 (1 mmol), CH3COOAg (0.1 mmol), CH3CN (10 ml).
Isolated yield.
A small amount of unknown by-product was formed.
A small amount of 2-oxohexane-1,1-diyl diacetate was produced.
PhI(OAc)2 (2 mmol).
b
c
d
e
f
No reaction.
H2O
OAc
Ph
OAc
O
O
OAc
I
HO
OAc
I
HO
C C
6s
I
Ph
CH
HO
(1)
(2)
Ph
HO
HO
HO
3s-OH
8s-OH
O
O
10 mol% CH3COOAg
wet CH3CN, 25 oC, 14hrs
OAc
OAc
AcO
+
HOAc
3s-OH
3s
O
O
10 mol% CH3COOAg
dry CH3CN, 25 oC, 48hrs
HO
HO
OAc
AcO
+ PhI(OAc)2
2
OAc
HO
(3)
(4)
1s
3s
3s-OH
0%
79%
OAc-
O
OAc
Ph
OAc
O
O
OAc
I
O
OAc
AcO
I
C C
I
Ph
CH
AcO
Ph
HO
3s
6s
8s
Scheme 1. A hypothesis for the transformation of the hydroxy group of 1s to an acetoxy group.
addition of an acetate anion to the alkynyliodonium salts 6s
according to the literature (Scheme 1, Eq. 4).11,21,24 If so, what is the
role of silver(I) in the reaction?
PhI(OAc)2. In pathway A, maybe in situ-generated alkynyl silver(I) 5
from terminal alkynes 125 facilitates the formation of alkynylio-
donium salts 6. In pathway B, the formation of complex 7 of Agþ
with the carbonecarbon multiple bond of alkynyliodonium salts 6
possibly increases its electron-deficient nature to accelerate the
As outlined in Scheme 2, there are two alternative pathways
that Agþ promotes the reaction of the terminal alkynes with
PhI(OAc)2 2
AgY
R
I
Ph
Pathway A
Pathway B
R
Ag
R
R
1
OAc
5
Ag+ + OAc-
HY
6
OAc-
O
Ag+
OAc
Ph
AcO
R
Ph
I
Ph
OAc
OAc
R
I
I
CH
R
OAc
Ag+
7
3
6
8
Scheme 2. A hypothesis for Agþ-catalyzed reaction of terminal alkynes with PhI(OAc)2.

G. Deng, J. Luo / Tetrahedron 69 (2013) 5937e5944
5941
conjugate addition of acetate anion towards the alkynyliodonium
salts resulting in the formation of key intermediates 8.
2(5H)-ones.22a Cyclic carbonates have also been synthesized using
this type of reaction.22b Recently, Yamada, et al. reported that
silver(I) promoted the incorporation of CO2 into o-alkynylanilines
to afford the corresponding benzoxazine-2-ones bearing Z exo-
olefin.22c In these reaction sequences, the lactonization at the
To test the hypothesis, control experiments have been accom-
plished. Utilization of pure phenylethynyl silver(I) 5a in the re-
action with PhI(OAc)2 gave 3a in only 6% yield (Scheme 3, Eq. 1).
Considering that 1 equiv of acetate acid was formed in the trans-
formation of phenylacetylene 1a into the corresponding alkynyl
silver(I),25 1 equiv of acetate acid was added to the heterogeneous
reaction of phenylethynyl silver(I) 5a with PhI(OAc)2 to achieve
a consistent condition. The result is similar to that in absence of
silver(I) (Table 1, entry 1). Therefore, the alkynyl silver(I) does not
play a role in the silver(I)-mediated reaction of terminal alkynes
with PhI(OAc)2 although alkynyl silver(I) is indeed generated in
situ. The conjugate addition of HOAc towards phenyl-
ethynylphenyliodonium tetrafluoroborate 926 in the presence or
absence of 10 mol % AgOAc afforded 3a in 20% and 12%11 yields,
respectively (Scheme 3, Eq. 2). Obviously, Agþ does not activate the
carbonecarbon multiple bond of alkynyliodonium salts 6. The
control experiment results strongly suggest that both alkynyl sil-
ver(I) 5 and alkynyliodonium salt 6 are not key intermediates in the
reaction with silver(I) activation. In contrast, alkynyl silver(I) 5 does
not favour the formation of product 3 probably due to its low sol-
ubility and poor reactivity in wet CH3CN (Table 1, entries 19e22).
Acetic acid seems to be able to facilitate the process according to
literature.21 In order to prove that the role of silver(I) or acetic acid
is the key part for this system, the reaction with 10 mol % acetic acid
activation was carried out (Scheme 3, Eq. 3). The yield is similar to
that in the case without acetic acid activation (Table 1, entry 1).
Even the use of acetic acid as solvent gave 3a in only 9% yield.21
When the reaction was activated with another 10 mol % AgOAc,
the yield obviously increases up to 59% (Scheme 3, Eq. 4), but is
apparently lower than that in the standard condition (Table 2, entry
Ag(I)-activated CeC triple bond leading to the formation of
b-
acetoxyvinyl silver intermediates22a has been suggested as a key
step. On the basis of the mechanism for above-mentioned sil-
ver(I)-promoted lactonization22 and these observations made by
us and the others,11,21,24,27,28
silver(I)-catalyzed reaction involving
a
plausible mechanism of the
-acetoxyviny1) phenyl-
(
b
iodonium acetates 8 is proposed as shown in Scheme 4. We be-
lieve that the reaction starts from Ag(I)-activated alkynes 10.
Based on anti-addition rule,11,29 the addition of trace amount ac-
etate anion in available commercial source to the complexes 10
followed by the reaction with PhI(OAc)2 gives the (
b
-acetoxyvinyl)
iodonium 824a and 1 equiv of acetate anion via
b-acetoxyvinyl
silver intermediates 1122a and regenerates silver ion catalyst. The
acetate anion elimination of intermediates 8 yields iodonium
ylides 12. Hydrolysis of the ylides 12 by water gives alkyliodonium
salts 13 and HOAc. Therefore, use of various silver(I) compounds in
the reaction affords total 2 equiv of acetate anion, which again
participates in subsequent reaction as nucleophile. Whereafter, the
substitution of the phenyliodonium group of the salts 13 with
acetate anion affords a
-acetoxy ketones 3.11,24
The reaction process outlined in Scheme 4 addresses the role of
silver(I) and water in the sequential transformations: namely,
silver(I)-activated carbonecarbon triple bond of the terminal al-
kynes 1 possesses higher electron-deficient nature than that of the
corresponding alkynes 1, tremendously promoting an in-
termolecular addition of acetate anion to the carbonecarbon triple
bond; ionization of acetic acid in water yields acetate anion, which
O
HOAc (1 eq.), CH3CN
OAc
Ph
Ph
Ag + PhI(OAc)2
2
(1)
(2)
Ph
25 oC, 14 hrs
5a
3a
6% yield
O
HOAc, cat.
80 oC, 24 hrs
OAc
I+Ph BF4
-
Ph
3a
9
Catalyst
10 mol%AgOAc
none
12%
Isolated yield 20%
O
HOAc (10 mol%)
OAc
Ph
Ph
+ PhI(OAc)2
(3)
(4)
Ph
CH3CN, 25 oC, 14 hrs
1a
2
3a
9% yield
O
HOAc, cat.
OAc
PhI(OAc)2
+
Ph
25 oC, 14 hrs
1a
2
3a
Catalyst
10 mol%AgOAc
none
9%
Isolated yield 59%
Scheme 3. Control experiments.
1). These results indicate not only that silver(I) instead of acetic acid
plays an important role in activation but that acetic acid is not the
best reaction solvent.21
is stronger nucleophile than its conjugate acid.11,21 In addition,
hydrolysis of the ylides 12 proceeds in the medium containing
water.11
In the early time, Negishi, et al. found that the Ag(I)-catalyzed
cyclization of (Z)-2-en-4-ynoic acids gave (Z)-5-alkylidenefuran-
In conclusion, we have demonstrated the silver(I)-catalyzed
reaction of terminal alkynes with PhI(OAc)2 for first time, and

5942
G. Deng, J. Luo / Tetrahedron 69 (2013) 5937e5944
HOAc + H2O
H3O+
OAc-
Ag+
AcO
R
AcO
R
H
H
I
key step
O
PhI(OAc)2
2
R
H
R
H
1
Ag
Ph
Ag+ + OAc-
Ag(I)
10
11
OAc
8
O
H
O
OAc-
PhI
H2O
O
IPh
OAc
R
R
OAc-
3
13
HOAc
R
I
Ph
12
Scheme 4. A plausible mechanism of the silver(I)-catalyzed reaction.
developed an efficient protocol for the preparation of
a-acetoxy
NMR (125.8 MHz, CDCl3, ppm) d 192.26, 170.35, 138.65, 134.55,
ketones starting from terminal alkynes in good to excellent yields.
Irrespective of the precise mechanism of the reaction, however, this
is an important alternative to existing approaches to synthesis of a-
acetoxy ketones starting from terminal alkynes (particularly, ter-
minal aryl alkynes) in view of the experimental simplicity, the
mildness of the reaction conditions, high chemoselectivity, efficient
use of PhI(OAc)2 and excellent yields.
134.15, 128.61, 128.16, 124.82, 65.97, 21.20, 20.44. IR (KBr): 2851,
2730, 1756, 1590, 1366, 1221, 1042, 777, 694, 628, 541 cmꢁ1. MS (EI)
192 (Mþ), 150, 119 (100), 105, 91, 77, 43. HRMS calcd for
[C11H13O3þH]: 193.0865, found: 193.0862.
3.2.4. 2-Oxo-2-(4-propylphenyl)ethyl
(500 MHz, CDCl3, ppm)
acetate
(3d). 1H
NMR
d
7.82 (d, J¼7.0 Hz, 2H), 7.27 (d, J¼7.0 Hz,
2H), 5.31 (s, 2H), 2.63 (t, J¼7.5 Hz, 2H), 2.21 (s, 3H), 1.69e1.61 (m,
3. Experimental
2H), 0.93 (t, J¼7.5 Hz, 3H). 13C NMR (125.8 MHz, CDCl3, ppm)
d
191.60, 170.20, 149.25, 131.77, 128.73, 127.67, 65.79, 37.85, 23.94,
3.1. General procedure
20.33,13.50. IR (KBr): 2961, 2930, 2861,1755,1700,1606,1416,1375,
1224, 1090, 965, 813, 607, 569 cmꢁ1. MS (EI) 220 (Mþ), 147, 139, 119,
91, 58, 43 (100). HRMS calcd for [C13H17O3þH]: 221.1178, found:
221.1180.
Solvents containing 1% water were used. Infrared (IR) spectra
were recorded on a Nicolet Nexus TT-IR spectrophotometer. 1H
NMR and 13C NMR spectra were recorded on a Bruker Avance-500
Spectrometer in CDCl3 solution using tetramethylsilane as an in-
ternal standard. MS (FAB) and HRMS spectra were recorded on
Waters ZQ2000 and Bruker APEX IV, respectively. For thin layer
chromatography (TLC) analysis throughout this work, Merck 25 TLC
aluminium sheets (silica gel 60 GF254, 0.25 mm) were used. The
products were purified by preparative column chromatography on
3.2.5. 2-(4-(tert-Butyl)phenyl)-2-oxoethyl acetate (3e). 1H NMR
(500 MHz, CDCl3, ppm)
2H), 5.32 (s, 2H), 2.21 (s, 3H), 1.33 (s, 9H). 13C NMR (125.8 MHz,
CDCl3, ppm) 191.63, 170.24, 157.57, 131.51, 127.58, 125.65, 65.84,
d
7.85 (d, J¼8.0 Hz, 2H), 7.49 (d, J¼8.0 Hz,
d
35.05, 30.86, 20.40. IR (KBr): 2963, 2867, 1752, 1702, 1599, 1222,
1089, 981, 832, 724, 645, 575 cmꢁ1. MS (EI) 234 (Mþ), 161, 139, 119,
91, 75, 58, 43 (100). HRMS calcd for [C14H19O3þH]: 235.1334, found:
235.1339.
silica gel ZCX-a (300e400 mesh).
3.2. General procedure for preparation of
starting from terminal alkynes 1
a-acetoxy ketones 3
3.2.6. 2-(4-Methoxyphenyl)-2-oxoethyl acetate (3f).30 1H NMR (500
MHz, CDCl3, ppm)
5.29 (s, 2H), 3.86 (s, 3H), 2.22 (s, 3H). 13C NMR (125.8 MHz, CDCl3,
ppm) 190.53, 170.36, 163.94, 129.93, 127.10, 113.93, 65.65, 55.39,
20.45. IR (KBr): 2937, 2840, 1755, 1689, 1597, 1441, 1214, 1167, 1090,
967, 831, 775, 608, 563 cmꢁ1. MS (EI) 208 (Mþ), 135 (100), 107, 92,
77, 65, 58, 43.
d
7.88 (d, J¼9.0 Hz, 2H), 7.94 (d, J¼9.0 Hz, 2H),
To a mixture of PhI(OAc)2 (1 mmol, 322 mg) and CH3COOAg
(0.1 mmol, 17 mg) in CH3CN (10 ml) was added alkyne (1 mmol).
The mixture was stirred at room temperature. When PhI(OAc)2 was
completely disappeared by TLC analysis, the mixture was concen-
trated in vacuum. The residue was purified by column chroma-
tography on silica gel with EtOAc/petroleum ether 6:1 as eluent.
d
3.2.7. 2-(3-Chlorophenyl)-2-oxoethyl acetate (3g).30 1H NMR (500
3.2.1. 2-Oxo-2-phenylethyl acetate (3a).21 1H NMR (500 MHz,
MHz, CDCl3, ppm)
d
7.86 (t, J¼2.0 Hz, 1H), 7.77 (d, J¼8.0 Hz, 1H),
7.57e7.44 (m,1H), 7.42 (t, J¼8.0 Hz,1H), 5.29 (s, 2H), 2.21 (s, 3H). 13C
CDCl3, ppm)
d
7.93e7.91 (m, 2H), 7.61 (tt, J¼7.5, 1.0 Hz, 1H), 7.49 (t,
J¼7.5 Hz, 2H), 5.35 (s, 2H), 2.23 (s, 3H). 13C NMR (125.8 MHz, CDCl3,
NMR (125.8 MHz, CDCl3, ppm)
d 191.00, 170.15, 135.51, 135.02,
133.62, 130.07, 127.69, 125.65, 65.77, 20.29. IR (KBr): 3070, 2925,
1755, 1730, 1580, 1425, 1370, 1211, 1083, 848, 785, 739, 679,
599 cmꢁ1. MS (EI) 212 (Mþ), 139, 111, 85, 71, 57, 43 (100).
ppm) d 192.19, 170.47, 134.20, 133.92, 128.89, 127.77, 66.04, 20.59. IR
(KBr): 3423, 2917, 2855, 2357, 1751, 1696, 1380, 1219, 1046,
687 cmꢁ1. MS (EI) 192 (Mþ), 105 (100), 91, 77, 65, 51, 43.
3.2.8. 2-(4-Fluorophenyl)-2-oxoethyl acetate (3h).30 1H NMR (500
3.2.2. 2-Oxo-2-(p-tolyl)ethyl acetate (3b).21 1H NMR (500 MHz,
MHz, CDCl3, ppm)
d
7.96e7.93 (m, 2H), 7.15 (t, J¼7.5 Hz, 2H), 5.30 (s,
CDCl3, ppm)
2H), 2.40 (s, 3H), 2.21 (s, 3H). 13C NMR (125.8 MHz, CDCl3, ppm)
191.62, 170.21, 144.68, 131.60, 129.37, 127.70, 65.82, 21.56, 20.40. IR
(KBr): 2957, 2922, 1748, 1698, 1602, 1369, 1225, 1085, 964, 808, 777,
603, 559 cmꢁ1. MS (EI) 192 (Mþ), 119 (100), 91, 85, 65, 58, 43.
d
7.81 (d, J¼7.0 Hz, 2H), 7.27 (d, J¼7.0 Hz, 2H), 5.30 (s,
2H), 2.21 (s, 3H). 13C NMR (125.8 MHz, CDCl3, ppm)
d
191.57, 170.20,
166.91, 164.87, 130.49, 130.46, 130.34, 130.27, 115.96, 115.78, 65.65,
20.25. IR (KBr): 3390, 2921, 2801, 2606, 2428, 2063, 1926, 844, 736,
566, 492 cmꢁ1. MS (EI) 196 (Mþ), 123 (100), 95, 75, 58, 43.
d
3.2.9. 2-(4-Nitrophenyl)-2-oxoethyl acetate (3i).31 1H NMR (500
3.2.3. 2-Oxo-2-(m-tolyl)ethyl acetate (3c). 1H NMR (500 MHz,
MHz, CDCl3, ppm)
d
8.35 (d, J¼7.5 Hz, 2H), 8.10 (d, J¼7.5 Hz, 2H),
CDCl3, ppm)
d
7.72 (s, 1H), 7.69 (d, J¼7.5 Hz, 1H), 7.42e7.36 (m, 1H),
5.34 (s, 2H), 3.86 (s, 3H), 2.24 (s, 3H). 13C NMR (125.8 MHz, CDCl3,
7.34 (d, J¼7.5 Hz, 1H), 5.32 (s, 2H), 2.40 (s, 3H), 2.21 (s, 3H) ppm. 13C

G. Deng, J. Luo / Tetrahedron 69 (2013) 5937e5944
5943
ppm)
d
191.00, 170.24, 150.69, 138.60, 128.88, 124.04, 66.02, 20.37.
115, 81, 61, 43 (100). HRMS calcd for [C16H18O8þH]: 339.1080,
IR (KBr): 2946, 2855, 1752, 1704, 1525, 1369, 1348, 1218, 974, 855,
found: 339.1076.
810, 747, 686 cmꢁ1. MS (EI) 223 (Mþ), 150, 104, 92, 78, 58, 43 (100).
3.2.18. 2-Oxopropane-1,3-diyl diacetate (3s).33 1H NMR (500 MHz,
3.2.10. 2-Oxohexyl acetate (3j).21 1H NMR (500 MHz, CDCl3, ppm)
CDCl3, ppm)
ppm) d 197.92,170.04, 66.19, 20.25. IR (KBr): 3440, 2925, 2855,1743,
d
4.73 (s, 4H), 2.14 (s, 6H). 13C NMR (125.8 MHz, CDCl3,
d
4.66 (s, 2H), 2.42 (d, J¼7 Hz, 2H), 2.17 (s, 3H),
d
1.63e1.57 (m, 2H),
1.36e1.32 (m, 2H), 0.91 (t, J¼7 Hz, 3H). 13C NMR (125.8 MHz, CDCl3,
1640, 1441, 1378, 1225, 1051, 874, 599 cmꢁ1. MS (EI) 174 (Mþ), 116,
101, 58, 43 (100).
ppm)
d 203.91, 170.15, 67.83, 38.35, 25.23, 22.11, 20.33, 13.64. IR
(KBr): 2930, 2845, 1744, 1378, 1226, 1049, 857, 600 cmꢁ1
.
3.3. Reaction of phenylethynyl silver 5a with PhI(OAc)2
3.2.11. 3-Bromo-2-oxopropyl acetate (3k). 1H NMR (500 MHz,
CDCl3, ppm)
4.91 (s, 2H), 3.95 (s, 2H), 2.18 (s, 3H). 13C NMR
(125.8 MHz, CDCl3, ppm)
d
To a mixture of PhI(OAc)2 (1 mmol, 322 mg), CH3COOAg
(0.1 mmol, 17 mg), phenylethynyl silver (1 mmol, 209 mg) in CH3CN
(10 ml) was added HOAc (1 mmol, 60 mg). The mixture was stirred
at room temperature for 14 h. The mixture was concentrated in
vacuum. The residue was purified by column chromatography on
d
195.76, 170.10, 66.01, 30.36, 20.34. IR
(KBr): 2930, 2843, 1744, 1371, 1226, 1047, 857, 703, 612 cmꢁ1. MS
(EI) 196 (Mþ2), 194 (Mþ), 150, 134, 120, 102, 73, 43 (100). HRMS
calcd for [C5H8BrO3þH]: 194.9657, found: 194.9651.
silica gel with EtOAc/petroleum ether 6:1 as eluent to afford
acetoxy acetophenone 3a in 6% yield.
a-
3.2.12. 3-(Hex-2-yn-1-yloxy)-2-oxopropyl acetate (3l). 1H NMR
(500 MHz, CDCl3, ppm)
d
4.87 (s, 2H), 4.21 (t, J¼1.0 Hz, 2H), 4.20 (s,
2H), 2.18e2.14 (m, 2H), 2.13 (s, 3H), 1.52e1.47 (m, 3H), 0.94 (t,
3.4. Reaction of phenylethynylphenyliodonium tetra-
J¼7.0 Hz, 3H). 13C NMR (125.8 MHz, CDCl3, ppm)
d 201.89, 170.14,
fluoroborates 9 with HOAc11
88.65, 74.51, 66.81, 59.33, 21.80, 20.56, 20.33, 13.35. IR (KBr): 2963,
2872,1740,1421,1379,1226,1097,1072, 604 cmꢁ1. MS (EI) 212 (Mþ),
169, 141, 99, 79, 53, 43 (100). HRMS calcd for [C16H17O4þH]:
213.1127, found: 213.1120.
A mixture of phenylethynylphenyliodonium tetrafluoroborates
(1 mmol, 392 mg) in HOAc (2 ml) was stirred in the presence or
absence of CH3COOAg (0.1 mmol, 17 mg) at 80 ꢀC for 24 h. The
mixture was concentrated in vacuum. The residue was purified by
column chromatography on silica gel with EtOAc/petroleum ether
3.2.13. (E)-3-(Cinnamyloxy)-2-oxopropyl acetate (3m).21 1H NMR
(500 MHz, CDCl3, ppm)
d 7.40e7.39 (m, 2H), 7.34e7.31 (m, 2H),
6:1 as eluent to afford
yield, respectively.
a-acetoxy acetophenone 3a in 20% and 12%
7.27e7.24 (m, 1H), 6.62 (d, J¼16 Hz, 1H), 6.26 (dt, J¼16, 6 Hz, 1H),
4.90 (s, 2H), 4.22 (d, J¼6 Hz, 2H), 4.17 (s, 2H), 2.16 (s, 3H). 13C NMR
(125.8 MHz, CDCl3, ppm)
d 202.04, 170.19, 136.11, 133.75, 128.55,
Acknowledgements
127.96, 126.50, 124.36, 73.52, 72.21 66.76, 20.35. IR (KBr): 3433,
2937, 2860, 1738, 1640, 1400, 1117, 1060, 675, 558 cmꢁ1. MS (EI) 249
Mþ1þ, 207, 191, 177, 133, 131, 117 (100), 115, 105, 91, 79, 65, 43.
The project was supported by Hunan Provincial Innovation
Foundation for Postgraduate (Grant No. CX2011B212).
3.2.14. 3-(Benzyloxy)-2-oxopropyl
(500 MHz, CDCl3, ppm) 7.38e7.33 (m, 5H), 4.90 (s, 2H), 4.59 (s,
2H), 4.14 (s, 2H), 2.16 (s, 3H). 13C NMR (125.8 MHz, CDCl3, ppm)
201.96, 170.24, 136.70, 128.60, 128.21, 127.90, 73.76, 73.71, 66.83,
20.41. IR (KBr): 2930, 2863, 1748, 1375, 1230, 1110, 1090, 745, 695,
612 cmꢁ1. MS (EI) 222 (Mþ), 161, 148, 115, 77, 55, 43 (100).
acetate
(3n).32 1H
NMR
Supplementary data
d
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2013.04.122.
These data include MOL files and InChiKeys of the most important
compounds described in this article.
d
3.2.15. 3-(2-Formylphenoxy)-2-oxopropyl acetate (3o). 1H NMR
References and notes
(500 MHz, CDCl3, ppm)
d
10.51 (s, 1H), 7.88 (dd, J¼8, 2 Hz, 1H), 7.58
(dt, J¼8, 2 Hz, 1H), 7.14 (t, J¼8 Hz, 1H), 6.87 (d, J¼8 Hz, 1H), 5.01 (s,
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d
199.37, 188.88, 170.25, 159.23, 136.00, 129.68, 125.13, 122.21,
112.31, 71.71, 66.70, 20.33. IR (KBr): 3444, 2919, 2854, 1738, 1682,
1596, 1471, 1384, 1233, 1058, 753 cmꢁ1. MS (EI) 236 (Mþ), 218, 194,
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(s, 2H), 4.54 (s, 2H), 2.14 (s, 3H). 13C NMR (125.8 MHz, CDCl3, ppm)
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d
6.94e6.92
(m, 2H), 6.83e6.81 (m, 2H), 4.97 (s, 4H), 4.68 (s, 4H), 2.12 (s, 6H). 13C
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