The indium-catalysed hydration of alkynes using substoichiometric amounts of PTSA as additive

Article abstract of DOI:10.1016/j.tet.2013.03.079

A general, efficient and highly regioselective protocol using an indium(III) trifluoromethanesulfonate and PTSA (TsOH·H₂O) catalytic system for the transformation of various alkynes to the corresponding ketones has been successfully developed.

Full text of DOI:10.1016/j.tet.2013.03.079

Tetrahedron 69 (2013) 3775e3781
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The indium-catalysed hydration of alkynes using substoichiometric
amounts of PTSA as additive
*
*
Qi Gao, Shenyan Li, Yingming Pan , Yanli Xu, Hengshan Wang
Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education of China), School of Chemistry & Chemical
Engineering of Guangxi Normal University, Guilin 541004, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
A general, efficient and highly regioselective protocol using an indium(III) trifluoromethanesulfonate and
PTSA (TsOH$H2O) catalytic system for the transformation of various alkynes to the corresponding
ketones has been successfully developed.
Received 29 November 2012
Received in revised form 8 March 2013
Accepted 19 March 2013
Ó 2013 Elsevier Ltd. All rights reserved.
Available online 22 March 2013
Keywords:
Hydration
Alkynes
Ketones
Indium(III) trifluoromethanesulfonate
PTSA
1. Introduction
2. Results and discussion
The hydration of alkynes to corresponding carbonyl compounds
is a useful and fundamental functional group transformation in
organic synthesis.1 Traditional methods for the hydration of al-
kynes were carried out using toxic Hg salts.2 However, the use of
toxic mercury salts produces a series of pollution problems. Sub-
sequently, transition-metal catalysts such as Ru,3ae3e Os,3f Rh,3g
Ir,3h Pd,3i Pt,3j Fe,3k,3l Ag3m and Au3ne3p have been reported to ca-
talyse the hydration of alkynes in good yields, but these methods
have some drawbacks including the use of precious metal catalysts
together with ligands, the requirements of some pressure (in
Schlenk tube), long reaction time or limited substrate availability.3
These imperfections limit wide applications and large scales syn-
theses. Therefore, the development of a general, efficient, cheap
and readily available catalyst for the hydration of alkynes to cor-
responding carbonyl compounds is still in great demand. More
recently, it was found that the In(III) salts are effective at activating
the carbonecarbon triple bonds.4 Herein, we report a mild and
convenient catalytic system for alkynes hydration, using In(OTf)3 in
conjunction with PTSA cocatalyst, which displays high efficiency
and wide application.
Initially, a variety of Brønsted acids were screened using
diphenylacetylene 1a as a model substrate (Table 1). The reaction of
Table 1
Screening of Brønsted acids for the hydration of 1aa
Entry
Brønsted acid
Yieldb (%)
1
2
3
4
PTSA (20 mol %)
PTSA
PTSA (50 mol %)
TfOH
72
85
86
10
0
5
TFA
6
7
Oxalic acid
AcOH
0
0
8
9
10
11
12c
HCl
H2SO4
HNO3
H3PO4
d
15
30
20
36
0
a
Reaction conditions: alkyne 1a (1.0 mmol), water (0.2 mL), In(OTf)3
(2 mol %), Brønsted acid (30 mol %), DCE (2.0 mL) at reflux for 14 h.
* Corresponding authors. Tel.: þ86 773 5846279; fax: þ86 773 5803930; e-mail
addresses: panym2004@yahoo.com.cn (Y. Pan), wang_hengshan@yahoo.com.cn
(H. Wang).
b
Isolated yield of pure product based on 1a.
c
The reaction time was 2 days.
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.03.079

3776
Q. Gao et al. / Tetrahedron 69 (2013) 3775e3781
1a and 0.2 mL of water gave 2a in 85% yield in the presence of
30 mol % of PTSA and mol % of In(OTf)3 in DCE (1,2-
corresponding ketones in good to excellent yields (Table 3, entries
1e9). Remarkably, electron-rich terminal alkynes provided the
desired products in higher yields than electron-poor terminal al-
kynes did. Alkyne 1k with a methoxyl in the ortho-position of the
aryl ring also reacted rapidly with water affording the corre-
sponding ketone 2k in 85% yield (Table 3, entry 10). But, compared
to 1f, the yield decreased from 96% to 85%, presumably due to the
steric effect of the substituent in the ortho-position of 1k. Addi-
tionally, alkyne bearing a heterocyclic aromatic substituent such as
1l was found to afford the desired product 2l in excellent yield
(Table 3, entry 11).7 Besides, alkyne bearing polycyclic aromatic
substituent such as 1m was treated with water giving the corre-
sponding ketone 2m in 85% yield (Table 3, entry 12). Interestingly,
1n produced 2n rather than the desired methyl ketone, presumably
due to the MeyereSchuster rearrangement (Table 3, entry 13).
Notably, internal alkynes such as 1o, 1s and 1t gave the desired
products 2o, 2s and 2t in 96%, 83% and 81% yields, respectively
(Table 3, entries 14, 18 and 19).8 Of note, the hydration of 1s and 1t
afforded 2s and 2t with complete regioselectivity, respectively.
What is more, some alkyl alkynes (1p, 1q and 1r) also worked well
in this condition (Table 3, entries 15e17). These results indicated
the superiorities of the In(OTf)3/PTSA catalytic system.
In addition, the hydration of the 1,4-diethynylbenzene 1u was
also examined (Scheme 1). The reaction occurred under the same
reaction conditions to afford three products: 2u (29%), 3u (46%) and
4u (21%).
We also explored the mechanism of the reaction. The reaction of
1s with TsOH (4-methylbenzenesulfonic acid anhydride) in the
presence of In(OTf)3 in DCE at 60 ꢀC proceeded efficiently to form
two adducts C1 and C2, which could be isolated and the ratio of
isomers is 1:2 (for details, see Supplementary data). Other possible
isomers could not be detected (Scheme 2). The attack of the TsOH
on the electron-poor alkynyl moiety could be controlled by elec-
tronic factors.9
2
dichloroethane) at reflux (Table 1, entry 2). When the amount of
PTSA was decreased to 20 mol %, the yield of product 2a decreased
to 72% (Table 1, entry 1). However, no obvious improvement in the
yield of 2a could be obtained, as the amount of PTSA was increased
to 50 mol % (Table 1, entry 3). The reaction using TfOH, HCl, H2SO4,
HNO3 or H3PO4 produced the desired product 2a only in low yields
(Table 1, entries 4 and 8e11). Other Brønsted acids such as TFA,
oxalic acid and AcOH were inactive for alkyne hydration under the
same conditions (Table 1, entries 5e7). Control experiments con-
firmed that in the absence of the acid, the reaction led to recovery
of starting materials even with prolonging the time to 2 days (Table
1, entry 12).
As PTSA proved to be the most effective Brønsted acid, a variety
of Lewis acids and solvents were screened using diphenylacetylene
1a as a model substrate (Table 2). The desired product 2a was ob-
tained in 72% yield using 2 mol % InCl3 (Table 2, entry 1). To our
delight, the isolated yield of the product 2a increased to 85% by
using In(OTf)3 instead of InCl3 (Table 2, entry 2).5 This is in sharp
contrast to the Au-catalysed hydration of alkynes.6 However, when
the PTSA alone was used for the hydration of 1a, only a small
amount of the product was observed (Table 2, entry 15). Then, other
Lewis acids such as Fe(OTf)3, FeCl3, Zn(OTf)2, ZnCl2, BiCl3 and CuCl
were evaluated and it was found that they were inferior to In(OTf)3
(Table 2, entries 3e8). In addition, it was found that the solvent
played a crucial role in this hydration reaction. When the reaction
was carried out in toluene or CH3NO2, the yield of the product 2a
obviously decreased (Table 2, entries 9 and 10). In other solvents,
such as CH3CN, THF, CH3COCH3 or DCM, most of starting material
1a was recovered (Table 2, entries 11e14). The above investigations
showed that the In(OTf)3 and PTSA catalytic system was the best
combination for the hydration of diphenylacetylene.
On the basis of the experiments mentioned above, a plausible
mechanism was proposed as shown in Scheme 3. Firstly, the indium
Table 2
Optimization of Lewis acids and solvents for the hydration of 1aa
cation coordinates to the alkyne to form an Inepealkyne complex
A. The p-toluenesulfonic acid as the nucleophile attacks the indium
cation-coordinated carbonecarbon triple bonds to form a vinyl-
indium species B1. B2 can be obtained from B1 through the pro-
tonationedeprotonation of B1 via the cationic indium carbine E.
Then, the intermediate B1 and B2 liberate the adduct C1 and C2 and
the indium catalyst by protodemetallation. Subsequently, vinyl
sulfonate intermediate C1 and C2 are attacked by water and yields
enol D1 and D2.10 Finally, the isomerizations of D1 and D2 produce
the ketone 2s.
Entry
Lewis acids
Solvent
Yieldb (%)
1
2
3
4
5
6
7
8
InCl3
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
Toluene
CH3NO2
CH3CN
THF
CH3COCH3
DCM
DCE
72
85
30
26
20
19
31
24
35
20
0
In(OTf)3
Fe(OTf)3
FeCl3
Zn(OTf)2
ZnCl2
BiCl3
CuCl
3. Conclusion
9
In(OTf)3
In(OTf)3
In(OTf)3
In(OTf)3
In(OTf)3
In(OTf)3
d
In summary, a general, efficient and highly regioselective pro-
tocol using In(OTf)3 with PTSA catalytic system for the trans-
formation of various alkynes to the corresponding ketones has been
successfully developed. It should be noted that functional groups
such as halogen atom, ester, or cyano on ethynylbenzene were
readily carried through the hydration reaction, allowing for the
subsequent elaboration of the products.
10
11
12
13
14
15
0
0
0
15
a
Reaction conditions: alkyne 1a (1.0 mmol), water (0.2 mL), Lewis acids (2 mol %),
PTSA (30 mol %), solvent (2.0 mL) at reflux for 14 h.
b
Isolated yield of pure product based on 1a.
4. Experimental section
With these optimal reaction conditions in hand, the scope of the
catalytic system was examined. The typical results are depicted in
Table 3. To our delight, not only terminal alkynes, but also internal
alkynes produced the desired products in high to excellent yields
with complete regioselectivity. The hydration of ethynylbenzene
derivatives possessing an electron-donating groups or electron-
withdrawing groups (1be1j) efficiently proceeded to afford the
4.1. General methods and materials
Melting points were uncorrected. NMR spectra were in CDCl3
(1H at 500 MHz or 400 MHz and 13C at 125 MHz or 100 MHz).
Column chromatography was performed on silica gel (300e400
mesh). Unless otherwise noted, all reagents were obtained com-
mercially and used without further purification.

Q. Gao et al. / Tetrahedron 69 (2013) 3775e3781
3777
Table 3
Hydration of various alkynes catalysed by In(OTf)3/PTSAa
Entry
1
Alkyne
Product
Time (h)
3
Yieldb (%)
89
90
93
92
96
82
80
77
72
1b
1c
2b
2
3
4
5
6
7c
8
9
3.5
3.5
4
2c
1d
2d
1e
2e
2f
0.3
7
1f
1g
2g
2h
8
1h
19
24
1i
2i
2j
1j
10
11
0.5
0.3
85
95
1k
1l
2k
2l
12
4
1
6
85
90
1m
2m
13
2n
1n
1o
14d
96
2o
(continued on next page)

3778
Q. Gao et al. / Tetrahedron 69 (2013) 3775e3781
Table 3 (continued )
Entry
Alkyne
Product
Time (h)
5
Yieldb (%)
85
15
16
1p
1q
2p
5.3
5.8
83
87
2q
17
18
1r
2r
12
14
83
81
1s
2s
19
1t
2t
a
Reaction conditions: alkynes 1 (1.0 mmol), water (0.2 mL), In(OTf)3 (2 mol %), PTSA (30 mol %), DCE (2.0 mL) at reflux.
Isolated yield of pure product based on 1.
The reactions were carried out in a sealed tube.
b
c
d
The reactions were carried out in a sealed tube and the yield was determined by GC.
Scheme 1. The hydration of the 1,4-diethynylbenzene.
(0.2 mL) in a 10 mL sealed tube was stirred at reflux for 6 h. Analysis
of the resulting mixture by gas chromatography showed the for-
mation of 2o in 96% yield.
4.4. General procedure for the hydration of alkyne 1u
The reaction mixtureof In(OTf)3 (11.2 mg, 2 mol %), PTSA (57.1 mg,
30 mol %), DCE (2.0 mL), alkyne 1u (1.0 mmol) and water (0.2 mL) in
a 10 mL flask was stirred at reflux for 24 h. Upon completion, DCE
was removed under reduced pressure using an aspirator, and then
the residue was purified by flash chromatography (PE/EA) on silica
gel to afford three products: 2u (29%), 3u (46%) and 4u (21%).
Scheme 2. From alkyne to vinyl sulfonates.
4.2. General procedure for the hydration of alkynes 1ae1n
and 1pe1t
4.5. General procedure from alkyne to vinyl sulfonates
The reaction mixture of In(OTf)3 (11.2 mg,
2 mol %), 4-
The reaction mixture of In(OTf)3 (11.2 mg, 2 mol %), PTSA
(57.1 mg, 30 mol %), DCE (2.0 mL), alkynes 1ae1n or 1pe1t
(1.0 mmol) and water (0.2 mL) in a 10 mL flask or in a 10 mL sealed
tube was stirred at reflux and monitored periodically by TLC. Upon
completion, DCE was removed under reduced pressure using an
aspirator, and then the residue was purified by flash chromatog-
raphy (PE/EA) on silica gel to afford corresponding carbonyl com-
pounds 2ae2n or 2pe2t.
methylbenzenesulfonic acid anhydride (51.6 mg, 30 mol %), DCE
(2.0 mL), and methylphenylacetylene 1s (116.2 mg, 1.0 mmol) in
a 10 mL flask was stirred at 60 ꢀC and monitored periodically by
TLC. Upon completion, DCE was removed under reduced pressure
using an aspirator, and then the residue was purified by flash
chromatography (PE/EA¼30:1) on silica gel to afford C1 and C2.
4.6. Characterization of the compounds
4.3. General procedure for the hydration of alkyne 1o
4.6.1. 1,2-Diphenylethanone (2a).11 White solid; mp: 56e57 ꢀC; 1H
The reaction mixture of In(OTf)3 (11.2 mg, 2 mol %), PTSA
(57.1 mg, 30 mol %), DCE (2.0 mL), alkyne 1o (1.0 mmol) and water
NMR (500 MHz, CDCl3):
d
8.08 (d, J¼7.3 Hz, 2H), 7.61e7.55 (m, 1H),
7.48 (t, J¼7.8 Hz, 2H), 7.41e7.28 (m, 5H), 4.32 (s, 2H); 13C NMR

Q. Gao et al. / Tetrahedron 69 (2013) 3775e3781
3779
Scheme 3. Proposed mechanism for the In(OTf)3/PTSA catalysed hydration reaction.
(125 MHz, CDCl3):
d
197.3, 136.4, 134.4, 132.9, 129.3, 128.4, 128.4,
2H), 2.64 (s, 3H); 13C NMR (100 MHz, CDCl3):
d
196.5, 139.9, 132.5,
126.7, 45.2; MS: m/z¼197 [MþHþ].
128.7, 117.9, 116.4, 26.7; MS: m/z¼146 [MþHþ].
4.6.2. Acetophenone (2b).12 Colourless oil; 1H NMR (500 MHz, CDCl3):
4.6.11. 1-(2-Methoxyphenyl)ethanone(2k).12 Yellow oil; 1H NMR
(500 MHz, CDCl3): 7.64e7.58 (m, 1H), 7.31e7.30 (m, 1H), 6.84e6.82
(m, 2H), 3.75 (s, 3H), 2.48 (s, 3H); 13C NMR (125 MHz, CDCl3):
199.0,
d
7.99e7.85 (m, 2H), 7.54e7.53 (m, 1H), 7.44e7.42 (m, 2H), 2.58 (s,
d
3H); 13C NMR (125 MHz, CDCl3):
d
197.5,136.6,132.6,128.1,127.8, 26.1;
d
MS: m/z¼121 [MþHþ].
158.5, 133.3, 129.8, 127.7, 120.0, 111.2, 55.0, 31.3; MS: m/z¼151
[MþHþ].
4.6.3. 1-(m-Tolyl)ethanone (2c).12 Colourless oil; 1H NMR (500 MHz,
CDCl3): 7.81e7.72 (m, 2H), 7.39e7.31 (m, 2H), 2.59 (s, 3H), 2.41 (s,
d
4.6.12. 1-(Thiophen-2-yl)ethanone (2l).17 Pale yellow oil; 1H NMR
3H); 13C NMR (125 MHz, CDCl3):
d
198.4, 138.3, 137.1, 133.8, 128.7,
(500 MHz, CDCl3):
d
8.10 (d, J¼5.0 Hz, 1H), 7.59e7.52 (dd, J¼5.0,
128.4, 125.5, 26.7, 21.3; MS: m/z¼135 [MþHþ].
1.0 Hz 1H), 7.35e7.32 (m, 1H), 2.54 (s, 3H); 13C NMR (125 MHz,
CDCl3):
d
192.2, 142.7, 133.2, 132.2, 127.0, 27.5; MS: m/z¼127
4.6.4. 1-(4-Ethylphenyl)ethanone (2d).13 Colourless oil; 1H NMR
[MþHþ].
(500 MHz, CDCl3):
d
7.89 (d, J¼7.7 Hz, 2H), 7.28 (d, J¼7.7 Hz, 2H), 2.71
(q, J¼7.3 Hz, 2H), 2.58 (s, 3H), 1.26 (t, J¼7.6 Hz, 3H); 13C NMR
4.6.13. 1-(6-Methoxynaphthalen-2-yl)ethanone (2m).18 White solid;
mp: 108 ꢀC; 1H NMR (500 MHz, CDCl3):
(125 MHz, CDCl3):
d
197.9, 150.1, 135.0, 128.5, 128.1, 29.0, 26.6, 15.2;
d
8.36 (s,1H), 7.98 (dd, J¼8.6,
MS: m/z¼149 [MþHþ].
1.8 Hz, 1H), 7.82 (d, J¼9.0 Hz, 1H), 7.73 (d, J¼8.7 Hz, 1H), 7.18 (dd,
J¼8.9, 2.5 Hz, 1H), 7.12 (d, J¼2.5 Hz, 1H), 3.92 (s, 3H), 2.67 (s, 3H); 13C
4.6.5. 1-(4-Propylphenyl)ethanone (2e).14 Colourless oil; 1H NMR
NMR (125 MHz, CDCl3): d 197.9, 159.7, 137.2, 131.1, 130.0, 127.8, 127.1,
(500 MHz, CDCl3):
d
7.82 (d, J¼8.3 Hz, 2H), 7.19 (d, J¼8.3 Hz, 2H), 2.57
124.6, 119.7, 105.7, 55.4, 26.6; MS: m/z¼201 [MþHþ].
(t, J¼7.2 Hz, 2H), 2.50 (s, 3H), 1.66e1.54 (m, 2H), 0.89 (t, J¼7.4 Hz,
3H); 13C NMR (125 MHz, CDCl3):
d
197.3, 148.2, 134.7, 128.4, 128.2,
4.6.14. 3,3-Diphenylacrylaldehyde (2n).3m Pale yellow oil; 1H NMR
37.7, 26.2, 24.0, 13.5; MS: m/z¼163 [MþHþ].
(400 MHz, CDCl3):
d
9.54 (d, J¼8.0 Hz, 1H), 7.48e7.29 (m, 10H), 6.61
(d, J¼8.0 Hz, 1H); 13C NMR (100 MHz, CDCl3):
d 193.3, 162.1, 139.6,
4.6.6. 1-(4-Methoxyphenyl)ethanone (2f).12 Colourless oil; 1H NMR
136.6, 130.6, 130.4, 129.4, 128.6, 128.5, 128.2, 127.2; MS: m/z¼209
(500 MHz, CDCl3):
d
7.94 (d, J¼8.8 Hz, 2H), 6.93 (d, J¼8.8 Hz, 2H),
[MþHþ].
3.87 (s, 3H), 2.56 (s, 3H); 13C NMR (125 MHz, CDCl3):
d 196.8, 163.5,
130.6, 130.4, 113.7, 55.4, 26.3; MS: m/z¼151 [MþHþ].
4.6.15. 2-Butanone (2o).19 Colourless oil; 1H NMR (500 MHz, CDCl3):
d
2.30 (q, J¼7.3 Hz, 2H), 1.98 (s, 3H), 0.88 (t, J¼7.4 Hz, 3H);
4.6.7. 1-(4-Bromophenyl)ethanone (2g).12 Pale yellow solid; mp:
13C NMR (125 MHz, CDCl3):
d
209.8, 37.0, 29.6, 7.9; MS: m/z¼73
51e52 ꢀC; 1H NMR (500 MHz, CDCl3):
d
7.81 (d, J¼8.3 Hz, 2H), 7.60
[MþHþ].
(d, J¼8.3 Hz, 2H), 2.58 (s, 3H); 13C NMR (125 MHz, CDCl3):
135.6, 131.7, 129.6, 128.1, 26.4; MS: m/z¼200 [MþHþ].
d 196.7,
4.6.16. Heptan-2-one (2p). Colourless oil; 1H NMR (500 MHz,
CDCl3):
d
2.33 (t, J¼7.5 Hz, 2H), 2.05 (s, 3H), 1.52e1.46 (m, 2H),
4.6.8. 1-(4-Fluorophenyl)ethanone (2h).12 Colourless oil; 1H NMR
(500 MHz, CDCl3): 8.02e7.94 (m, 2H), 7.16e7.09 (m, 2H), 2.58 (s,
1.25e1.16 (m, 4H), 0.80 (t, J¼7.1 Hz, 3H); 13C NMR (125 MHz, CDCl3):
d
d
209.05, 43.53, 31.16, 29.60, 23.35, 22.26, 13.70; MS: m/z¼115
3H); 13C NMR (125 MHz, CDCl3):
d
196.5, 166.7, 164.7, 133.5, 130.94
[MþHþ].
and 130.86, 115.69 and 115.52, 26.5; MS: m/z¼139 [MþHþ].
4.6.17. 4-Phenylbutan-2-one (2q).3m Colourless oil; 1H NMR (500 MHz,
4.6.9. Methyl 4-acetylbenzoate (2i).15 Pale yellow solid; mp:
CDCl3):
d
7.31e7.27 (m, 2H), 7.22e7.19 (m, 3H), 2.90 (t, J¼7.6 Hz, 2H),
91e94 ꢀC; 1H NMR (400 MHz, CDCl3):
d
8.11 (d, J¼8.6 Hz, 2H), 7.99 (d,
2.76 (t, J¼7.6 Hz, 2H), 2.14 (s, 3H); 13C NMR: (125 MHz, CDCl3)
d 207.74,
J¼8.6 Hz, 2H), 3.94 (s, 3H), 2.63 (s, 3H); 13C NMR (100 MHz, CDCl3):
140.80, 128.29, 128.10, 125.91, 44.91, 29.84, 29.51; MS: m/z¼149
d
197.5, 166.2, 140.2, 133.9, 129.8, 128.2, 52.4, 26.8; MS: m/z¼179
[MþHþ].
[MþHþ].
4.6.18. 2-(3-Oxobutyl)isoindoline-1,3-dione (2r).20 White solid; mp:
4.6.10. 4-Ethynylbenzonitrile (2j).16 White solid; mp: 59e61 ꢀC; 1H
110e111 ꢀC; 1H NMR (500 MHz, CDCl3):
d
7.76e7.74 (m, 2H),
NMR (400 MHz, CDCl3):
d
8.04 (d, J¼8.5 Hz, 2H), 7.77 (d, J¼8.5 Hz,
7.66e7.64 (m, 2H), 3.87 (t, J¼7.5 Hz, 2H) 2.82 (t, J¼7.5 Hz, 2H), 2.12

3780
Q. Gao et al. / Tetrahedron 69 (2013) 3775e3781
1599; (e) Labonne, A.; Kribber, T.; Hintermann, L. Org. Lett. 2006, 8, 5853; (f)
(s, 3H); 13C NMR (125 MHz, CDCl3):
d
205.66, 167.86, 133.84, 131.83,
Harman, W. D.; Dobson, J. C.; Taube, H. J. Am. Chem. Soc. 1989, 111, 3062; (g)
Blum, J.; Huminer, H.; Alper, H. J. Mol. Catal. 1992, 75, 153; (h) Ogo, S.; Uehara,
K.; Abura, T.; Watanabe, Y.; Fukuzumi, S. J. Am. Chem. Soc. 2004, 126, 16520; (i)
Imi, K.; Imai, K.; Utimoto, K. Tetrahedron Lett. 1987, 28, 3127; (j) Francisco, L. W.;
Moreno, D. A.; Atwood, J. D. Organometallics 2001, 20, 4237; (k) Wu, X. F.;
Bezier, D.; Darcel, C. Adv. Synth. Catal. 2009, 351, 367; (l) Cabrero-Antonino, J. R.;
123.05, 41.39, 32.78, 29.73; MS: m/z¼218 [MþHþ].
4.6.19. Propiophenone (2s).12 Colourless oil; 1H NMR (500 MHz,
CDCl3):
d 7.99e7.94 (m, 2H), 7.58e7.51 (m, 1H), 7.48e7.42 (m, 2H),
3.00 (q, J¼7.2 Hz, 2H), 1.22 (t, J¼7.2 Hz, 3H); 13C NMR (125 MHz,
ꢀ
Leyva-Perez, A.; Corma, A. Chem.dEur. J. 2012, 18, 11107; (m) The Thuong, M. B.;
Mann, A.; Wagner, A. Chem. Commun. 2012, 434; (n) Mizushima, E.; Sato, K.;
Hayashi, T.; Tanaka, M. Angew. Chem., Int. Ed. 2002, 41, 4563; (o) Casado, R.;
Contel, M.; Laguna, M.; Romero, P.; Sanz, S. J. Am. Chem. Soc. 2003, 125, 11925;
CDCl3):
d
200.8, 136.8, 132.8, 128.5, 127.9, 31.7, 8.2; MS: m/z¼135
[MþHþ].
ꢀ
(p) Marion, N.; Ramon, R. S.; Nolan, S. P. J. Am. Chem. Soc. 2009, 131, 448.
4.6.20. 1-Phenylbutan-1-one(2t).11 Colourless oil; 1H NMR (500 MHz,
4. (a) Xu, Y. L.; Pan, Y. M.; Wu, Q.; Wang, H. S.; Liu, P. Z. J. Org. Chem. 2011, 76, 8472;
(b) Gibeau, A. L.; Snyder, J. K. Org. Lett. 2011, 13, 4280; (c) Sarma, R.; Prajapati, D.
Chem. Commun. 2011, 9525; (d) Sarma, R.; Rajesh, N.; Prajapati, D. Chem.
Commun. 2012, 4014.
CDCl3):
d 7.89e7.87 (m, 2H), 7.46e7.43 (m, 1H), 7.37e7.34 (m, 2H),
2.84 (t, J¼7.3 Hz, 2H), 1.73e1.65 (m, 2H), 0.93 (t, J¼7.3 Hz, 2H); 13C
NMR (125 MHz, CDCl3): d 199.83, 136.73, 132.50, 128.19, 127.66, 40.08,
5. The yield of the large-scale synthesis of 1,2-diphenylethanone 2a from 1,2-
diphenylethyne 1a (10 mmol, 1.78 g) was 83%.
6. Only 53% yield was obtained in this catalytic system. See: Ref. 3n.
17.38, 13.52. MS: m/z¼149 [MþHþ].
4.6.21. 1-(4-Ethynylphenyl)ethanone (2u).21 White solid; mp: 70e71 ꢀC;
1H NMR (400 MHz, CDCl3):
d
7.89 (d, J¼8.6 Hz, 2H), 7.56 (d, J¼8.5 Hz,
2H), 3.25 (s, 1H), 2.59 (s, 3H); 13C NMR (100 MHz, CDCl3):
d 197.2, 136.7,
132.2, 128.1, 126.9, 82.7, 80.4, 26.6; MS: m/z¼145 [MþHþ].
4.6.22. 1,10-(1,4-Phenylene)diethanone (3u).12 White solid; mp:
111e112 ꢀC; 1H NMR (400 MHz, CDCl3):
d
8.02 (s, 4H), 2.63 (s, 6H);
7. Israelsohn has also reported that PtCl4 could catalyze the hydration of 1-(thi-
ophen-2-yl)ethanone. However, an unsatisfactory yield was obtained. See: Is-
raelsohn, O.; Vollhardt, K. P. C.; Blum, J. J. Mol. Catal. A: Chem. 2002, 184, 1.
13C NMR (100 MHz, CDCl3):
d
197.4, 140.1, 128.4, 26.9; MS: m/z¼163
[MþHþ].
4.6.23. 1,10-(Buta-1,3-diene-2,3-diylbis(4,1-phenylene))diethanone
(4u). Pale green solid; mp: 149e151 ꢀC; 1H NMR (400 MHz, CDCl3):
d
8.01 (d, J¼8.7 Hz, 4H), 7.65 (d, J¼8.6 Hz, 4H), 5.75 (d, J¼4.2 Hz, 2H),
5.51 (d, J¼4.2 Hz, 2H), 2.63 (s, 6H); 13C NMR (100 MHz, CDCl3):
d
197.0, 152.4, 138.2, 136.0, 128.9, 125.5, 106.4, 26.7; MS: m/z¼291
[MþHþ].
4.6.24. (Z)-1-Phenylprop-1-en-1-yl 4-methylbenzenesulfonate (C1)
and (E)-1-phenylprop-1-en-1-yl 4-methylbenzenesulfonate (C2). Pale
8. Rebacz, N. A.; Savage, P. E. have also reported the hydration of 1-phenyl-1-
propyne catalyzed by indium(III) trifluoromethanesulfonate, but required
a high-temperature. See: Rebacz, N. A.; Savage, P. E. Ind. Eng. Chem. Res. 2010,
49, 535.
9. Cui has also reported a gold complex-catalyzed addition of sulfonic acids to
alkynes for synthesis of vinyl tosylates and vinyl mesylates with highly re-
gioselectivity where the reaction performs under precious metal catalysts and
ligands. See: (a) Cui, D. M.; Meng, Q.; Zheng, J. Z.; Zhang, C. Chem. Commun.
2009, 1577; (b) Reetz, M. T.; Sommer, K. Eur. J. Org. Chem. 2003, 18, 3485.
yellow oil; 1H NMR (500 MHz, CDCl3):
d
7.70 (d, J¼8.3 Hz, 2H), 7.65
(d, J¼8.3 Hz, 4H), 7.31e7.27 (m, 3H), 7.26 (s, 9H), 7.21 (dd, J¼14.8,
7.8 Hz, 10H), 5.83 (q, J¼7.0 Hz,1H), 5.72 (q, J¼7.4 Hz, 2H), 2.42 (s, 3H),
2.40 (s, 6H), 1.77 (d, J¼7.4 Hz, 6H), 1.74 (d, J¼7.1 Hz, 3H); 13C NMR
(125 MHz, CDCl3):
d 134.7, 133.7, 133.3, 132.7, 129.4, 129.3, 128.5,
128.4,128.2,128.1,128.0,127.9,125.4,118.0,117.3, 21.5,13.0,12.1; MS:
m/z¼289 [MþHþ]; Anal. Calcd for C16H16O3S: C, 66.64; H, 5.59.
Found: C, 66.52; H, 5.78.
Acknowledgements
This study was supported by the project 973 (2011CB512005),
the National Natural Science Foundation of China (41206077
and 81260472), and Guangxi Natural Science Foundation of China
(2012GXNSFAA053027, 2011GXNSFD018010 and 2010GXNSFF013001).
10. A similar transforion has also been reported. See: (a) Martínez, A. G.; Herrera,
A.; Martínez, R.; Teso, E.; García, A.; Osío, J.; Pargada, L.; Unanue, R.; Sub-
ramanian, L. R.; Hanack, M. J. Heterocycl. Chem. 1988, 25, 1237; (b) Martínez, A.
Supplementary data
ꢀ
G.; Fernandez, A. H.; Alvarez, R. M.; Vilar, E. T.; Fraile, A. G.; Barcina, J. O.; Ig-
lesias, L. P. Tetrahedron Lett. 1987, 28, 1929.
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2013.03.079.
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