Pd/Cu-catalyzed oxidation of alkynes into 1,2-diketones using DMSO as the oxidant

Article abstract of DOI:10.1016/j.tet.2012.04.069

A facile and practical method for the palladium/copper-catalyzed transformation of internal alkynes into 1,2-diketones has been described, affording the desired products in moderate to excellent yields. The mechanistic studies were also preliminarily pursued using diphenyl sulfoxide as the oxidant, and the diphenyl sulfide was isolated as the reduced product.

Full text of DOI:10.1016/j.tet.2012.04.069

Tetrahedron 68 (2012) 4950e4954
Contents lists available at SciVerse ScienceDirect
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Pd/Cu-catalyzed oxidation of alkynes into 1,2-diketones using DMSO as the
oxidant
,
,
b
a,
Ang Gao a b, Fan Yang a , Ji Li , Yangjie Wu
*
*
a The College of Chemistry and Molecular Engineering, Key Laboratory of Chemical Biology and Organic Chemistry of Henan Province, Key Laboratory of Applied Chemistry of Henan
Universities, Zhengzhou University, Zhengzhou 450052, PR China
b Institute of Chemistry, Henan Academy of Sciences, Zhengzhou 450002, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A facile and practical method for the palladium/copper-catalyzed transformation of internal alkynes into
1,2-diketones has been described, affording the desired products in moderate to excellent yields. The
mechanistic studies were also preliminarily pursued using diphenyl sulfoxide as the oxidant, and the
diphenyl sulfide was isolated as the reduced product.
Received 8 January 2012
Received in revised form 10 April 2012
Accepted 18 April 2012
Available online 26 April 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Oxidation
Palladium catalysis
Alkynes
1,2-Diketones
Dimethyl sulfoxide
1. Introduction
conditions using diphenyl sulfoxide as oxidant, which enlightened
us on the essence of sulfoxide in these reactions.5b Inspired by these
1,2-Dicarbonyl derivatives are very useful building blocks in the
construction of a variety of organic intermediates,1 especially in the
synthesis of biologically active heterocyclic compounds,2 such as
imidazoles, quinoxalines, and indolone-N-oxide.3 Some of these
compounds show good antitumor activity or/and can be used as
selective cyanide anion indicators or photoinitiators.4
promising reports, our work was focused on the direct palladium/
copper-catalyzed oxidation of internal alkynes into 1,2-dicarbonyl
derivatives in DMSO. In this transformation, the DMSO would
also behave as an oxidant.
2. Results and discussion
Over the past decade, lots of synthetic protocols for the prepa-
ration of 1,2-diaryldiketones have been reported.5 Since the in-
ternal alkynes as the starting material could be easily accessible via
Sonogashira coupling,6 the direct oxidation of internal alkynes into
1,2-dicarbonyl derivatives appears to be one of the most straight-
forward methods. Great progress on this type of transformation has
been made during the last few years. For example, Yusubov and Chi
introduced the PdCl2 catalyzed oxidation of internal alkynes in
DMSO, while the scope of this reaction was quite narrow and only
two examples (1-phenylprop-1-yne and 1-phenylpent-1-yne)
were involved.5m Subsequently, Wan’s group reported palladium-
catalyzed synthesis of 1,2-diketones via the oxidation of internal
alkynes using oxygen as the oxidant.5d And then, Li and co-workers
described a Au/Ag-catalyzed protocol, which could undergo in mild
In our initial study, we launched our efforts to transform 1,2-
diphenylethyne (1a) to the benzil (2a), and the product (2a)
could be obtained in a yield of 17% in DMSO after 20 h using
Pd(OAc)2 as the catalyst in the absence of the cocatalyst (Table 1,
entry 1). Gratifyingly, with the addition of the cocatalyst (e.g., FeCl3
and CuBr2), the yield of the desired product could increase dra-
matically, albeit the reaction did not occur at all with AgOAc as the
cocatalyst (Table 1, entries 2e4). Especially, with CuBr2 as the co-
catalyst, the benzil (2a) could be afforded in a yield of 99% (Table 1,
entry 4), while the desired product was not observed at all in the
absence of the palladium catalyst (Table 1, entry 5). These results
indicated that both of the palladium and copper species played
a critical role on the catalytic efficiency (Table 1, entries 1e5).
However, when the reaction time or temperature decreased to 12 h
and 80 ꢀC, the reaction only gave the benzil in yields of 78% and
72%, respectively (Table 1, entries 6 and 7). This oxidative reaction
could also be performed in DMSO under the nitrogen atmosphere,
* Corresponding authors. Tel./fax: þ86 371 67979408; e-mail addresses: yangf@
zzu.edu.cn (F. Yang), wyj@zzu.edu.cn (Y. Wu).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2012.04.069

A. Gao et al. / Tetrahedron 68 (2012) 4950e4954
4951
Table 1
Optimization of reaction conditionsa
Entry
Catalyst
Solvent
t (h)
T (ꢀC)
Yieldb (%)
1
2
3
4
5
6
Pd(OAc)2
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
Dioxane
DMF
20
20
20
20
20
12
84
20
20
20
20
20
20
20
120
120
120
120
120
120
80
120
120
120
120
100
120
120
17
0
93
99
0
78
72
95
90
90
70
0
Pd(OAc)2/AgOAc
Pd(OAc)2/FeCl3
Pd(OAc)2/CuBr2
CuBr2
Pd(OAc)2/CuBr2
Pd(OAc)2/CuBr2
Pd(OAc)2/CuBr2
PdCl2/CuBr2
Pd(PPh3)2Cl2/CuBr2
Pd(dba)2/CuBr2
Pd(OAc)2/CuBr2
Pd(OAc)2/CuBr2
Pd(OAc)2/CuBr2
7
8c
9
10
11
12
13
14
0
0
DMA
Bold values in entry 4 represents the optimal conditions.
a
Reaction conditions: 0.5 mmol 1a and 10 mol % of catalyst in 2 mL solvent in air.
Isolated yield.
Under the nitrogen atmosphere.
b
c
generating the benzil in 95% yield (Table 1, entry 8). Then, other
palladium catalysts were evaluated and the benzil was formed in
moderate to good yields (Table 1, entries 9e11). Some other sol-
vents such as dioxane, DMF and DMA were also examined, and no
product was detected (Table 1, entries 12e14).
With the optimized reaction conditions in hand, the scope of the
oxidation of alkynes was explored (Tables 2 and 3). Generally, the
substituent and electronic effects have no significant influence on
this transformation, and the reaction could tolerate a broad scope
of substituents such as MeO, CHO, NO2, CN, SiMe3, and F, affording
the desired products in moderate to good yields (Table 2). It should
be noted that the oxidation of some heterocyclic and fused aro-
matic ring alkynes could also afford the corresponding 1,2-
dicarbonyl derivatives in good yields (Table 3, entries 1e3).
However, when one of the two substituents is an alkyl group (1r),
the oxidation only gave the product in a low yield of 33% (Table 3,
entry 4).
This oxidative reaction could generate the benzil in 95% yield
under the nitrogen atmosphere, which suggested that the solvent
(DMSO) may serve as an oxidant (Table 1, entry 8). To clarify the
mechanism of the oxidation of internal alkynes, mechanistic
studies were also pursued (Scheme 1). According to this hypothesis,
the reductive product of DMSO would be dimethyl sulfide. But
unfortunately, dimethyl sulfide is quite volatile, which is difficult to
be detected. So we took diphenyl sulfoxide (3) instead of DMSO,
and diphenyl sulfide (4) as the reductive product could be detected
and isolated easily. However, diphenyl sulfoxide is a solid and
cannot be used as the solvent, and thus the reaction was performed
Table 2
Oxidation of alkynesa
Entry
R1
R2
Substrate
Product/yieldb (%)
1
2
3
4
5
6
7
8
H
H
H
H
H
H
H
H
Me
tert-Butyl
MeO
n-C5H11
NO2
CN
CHO
F
SiMe3
Me
MeO
MeO
CN
1b
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
1m
1n
2b, 83
2c, 78
2d, 70
2e, 85
2f, 65
2g, 75
2h, 88
2i, 80
2j, 90
2k, 91
2l, 87
2m, 71
2n, 75
O
9
H
Et
Et
10
11
12
13
n-C5H11
tert-Butyl
a
Reaction conditions: 0.5 mmol alkyne, 10 mol % of Pd(OAc)2 and 10 mol % of CuBr2 in 2 mL DMSO at 120 ꢀC in air for 20 h.
Isolated yield.
b

4952
A. Gao et al. / Tetrahedron 68 (2012) 4950e4954
Table 3
3. Conclusion
Oxidation of alkynesa
In summary, we have developed a new and facile pathway to
1,2-diketones via the Pd/Cu-catalyzed oxidation of internal alkynes
in DMSO under ligand- and additive-free conditions. This catalytic
system showed high efficiency and good functional group toler-
ance. The preliminary mechanistic studies demonstrated that the
solvent of DMSO could also behave as the oxidant. Further appli-
cation of this synthetic methodology is currently underway.
Entry
R1
R2
Substrate
Product/yieldb (%)
1
2
3
4
Ph
Ph
p-FC6H4
Ph
3-Pyridyl
1-Naphthyl
1-Naphthyl
Me
1o
1p
1q
1r
2o, 72
2p, 87
2q, 71
2r, 33
4. Experimental
4.1. General methods
a
Reaction conditions: 0.5 mmol alkyne, 10 mol % of Pd(OAc)2 and 10 mol % of
CuBr2 in 2 mL DMSO at 120 ꢀC in air for 20 h.
All commercial materials were used without further purifica-
b
Isolated yield.
tion. 1H and 13C NMR spectra were recorded in CDCl3 solution on
Scheme 1. Mechanistic studies of oxidation of alkynes.
in dioxane with the addition of 5 equiv sulfoxide as the oxidant.
When the reaction was carried out in dioxane under the nitrogen
atmosphere in the absence of diphenyl sulfoxide, no product was
observed. But with the addition of 5 equiv diphenyl sulfoxide (3),
the isolated yield of the product (2a) was up to 92% (0.46 mmol),
and 0.83 mmol diphenyl sulfide (4) was also obtained. To our de-
light, the mole ratio of 4/2a (1.8:1) is approximately equal to 2:1,
which suggests that two molecules of DMSO could oxidize one
molecule of alkyne and the two oxygen atoms in the benzil (2a)
should come from the sulfoxide.
On the basis of the above results, a possible catalytic cycle for
palladium-catalyzed oxidation of alkynes is outlined in Scheme 2,
which includes: (i) the coordination of Pd(II) to the triple bond of
the internal alkyne (1a), resulting in the formation of the in-
termediate I; (ii) the attack of R2SO to intermediate I to form the
vinyl palladium species II; (iii) nucleophilic addition of another
molecule of R2SO to the intermediate II accompanied by the leaving
a Bruker DPX-400 spectrometer. Melting points were measured
using a WC-1 microscopic apparatus and were uncorrected. GC
analysis was performed on Agilent 4890D gas chromatograph.
Mass spectra were measured on an LC-MSD-Trap-XCT instrument.
High-resolution mass spectra were measured on a MALDI-FTMS. IR
spectra were recorded on a Bruker Alpha FT-IR Spectrometer. Ethyl
acetate and petroleum ether were used for column chromatogra-
phy without purification. Other solvents were purified according to
the standard methods. Pd(OAc)2, CuBr2, and diphenyl sulfoxide
were purchased from Alfa-Aesar Chemicals and used without fur-
ther purification. The other chemicals were from commercial
sources and used as-received unless otherwise noted.
4.2. The general procedure for preparation of internal
alkynes
Alkynes of 1b, 1k, 1l, and 1r were purchased from Alfa-Aesar
Chemicals and used without further purification, other alkynes
were prepared according to the reported procedure.7 The known
compounds (1a, 1ce1k, 1o, 1p, 1r) were characterized by compar-
ing their mp, 1H, 13C NMR to those previously reported.
of the R2S, affording the palladium species III; (iv) b-elimination of
the intermediate III, leading to the desired 1,2-dicarbonyl com-
pound (2a) and another molecule of R2S as well as the active pal-
ladium(II) species.

A. Gao et al. / Tetrahedron 68 (2012) 4950e4954
4953
4.3.1. 1,2-Diphenylethane-1,2-dione (2a).5d Yellow solid, mp
94e95 ꢀC; 1H NMR (CDCl3, 400 MHz):
d
7.98 (d, 4H, J¼7.6 Hz), 7.67
(t, 2H, J¼7.4 Hz), 7.52 (t, 4H, J¼7.6 Hz); 13C NMR (CDCl3, 100 MHz):
d
194.61, 134.94, 132.94, 129.92, 129.04; MS (C14H10O2): 210.0 (Mþ).
4.3.2. 1-Phenyl-2-(p-tolyl)ethane-1,2-dione (2b).5g Yellow solid, mp
96 ꢀC; 1H NMR (CDCl3, 400 MHz):
7.95 (m, 2H), 7.86 (d, 2H,
d
J¼8.2 Hz), 7.64 (t, 1H, J¼7.4 Hz), 7.49 (t, 2H, J¼7.7 Hz), 7.30 (d, 2H,
J¼8.1 Hz), 2.43 (s, 3H); 13C NMR (CDCl3, 100 MHz):
d 194.73, 194.27,
146.18, 134.74, 133.06, 129.98, 129.82, 129.80, 129.71, 128.94, 21.88;
MS (C15H12O2Na): 247.2 (MþNaþ).
4.3.3. 1-(4-tert-Butylphenyl)-2-phenylethane-1,2-dione (2c). Yellow
oil; 1H NMR (CDCl3, 400 MHz):
d
7.96 (m, 2H), 7.91 (d, 2H, J¼8.5 Hz),
7.63 (m, 1H), 7.54e7.48 (m, 4H), 1.34 (s, 9H); 13C NMR (CDCl3,
100 MHz): 194.76, 194.28, 159.01, 134.74, 133.07, 130.43, 129.87,
d
128.94, 126.02, 35.37, 30.94; IR (KBr, cmꢁ1):
n 3077, 3039, 2955,
2928, 2860, 1665; HRMS-ESI (m/z): [MþNa]þ calcd for C18H18O2Na
289.1204; found 289.1209.
4.3.4. 1-(4-Methoxyphenyl)-2-phenylethane-1,2-dione
(2d).5d Yellow oil; 1H NMR (CDCl3, 400 MHz):
d 7.95 (t, 4H,
Scheme 2. Proposed mechanism for oxidation of alkynes.
J¼8.7 Hz), 7.63 (t, 1H, J¼7.4 Hz), 7.49 (t, 2H, J¼7.7 Hz), 6.97 (d, 2H,
J¼8.8 Hz), 3.87 (s, 3H); 13C NMR (CDCl3, 100 MHz):
d 194.82, 193.12,
Characterization data for the unknown internal alkynes:
164.967 134.67, 133.17, 132.34, 129.85, 128.91, 126.06, 114.34, 55.61;
MS (C15H12O3Na): 263.1 (MþNaþ).
4.2.1. 1-Methoxy-4-[2-(4-pentyloxyphenyl)ethynyl]benzene
(1m). White solid; mp: 54e55 ꢀC; yield: 80%; 1H NMR (CDCl3,
4.3.5. 1-(4-Pentyloxyphenyl)-2-phenylethane-1,2-dione
(2e).8a Yellow oil; 1H NMR (CDCl3, 400 MHz):
d 7.98e7.92 (m, 4H),
400 MHz):
d 7.45e7.42 (m, 4H), 6.87e6.84 (m, 4H), 3.96 (t, 2H,
J¼6.6 Hz), 3.81 (s, 3H), 1.79 (t, 2H, J¼7.2 Hz), 1.44e1.37 (m, 4H), 0.93
7.66e7.62 (m, 1H), 7.49 (t, 2H, J¼7.7 Hz), 6.97e6.94 (m, 2H), 4.03 (t,
(t, 3H, J¼7.0 Hz); 13C NMR (CDCl3, 100 MHz):
d 159.23, 158.87,
2H, J¼6.5 Hz), 1.84e1.77 (m, 2H), 1.47e1.35 (m, 4H), 0.92 (t, 3H,
J¼7.1 Hz); 13C NMR (CDCl3, 100 MHz):
d
194.89, 193.15, 164.64,
132.73, 132.71, 115.66, 115.30, 114.37, 113.82, 87.93, 87.70, 67.92,
55.16, 28.78, 28.05, 22.33, 13.89; IR (KBr, cmꢁ1):
n 2967, 2932, 2928,
134.65, 133.19, 132.34, 129.85, 128.90, 125.79, 114.77, 68.46, 28.64,
2859, 2210; HRMS-ESI (m/z): [MþH]þ calcd for C20H23O2 295.1698;
28.02, 22.35, 13.94; MS (C19H20O3Na): 319.2 (MþNaþ).
found 295.1694.
4.3.6. 1-(4-Nitrophenyl)-2-phenylethane-1,2-dione
solid, mp 141 ꢀC; 1H NMR (CDCl3, 400 MHz):
8.37e8.34 (m, 2H),
(2f).8b Yellow
4.2.2. 4-[2-(4-tert-Butylphenyl)ethynyl]benzonitrile
(1n). White
d
solid; mp: 101e102 ꢀC; yield: 85%; 1H NMR (CDCl3, 400 MHz):
8.18e8.16 (m, 2H), 8.00e7.98 (m, 2H), 7.71e7.72 (m, 1H), 7.55 (t, 2H,
J¼7.8 Hz); 13C NMR (CDCl3, 100 MHz):
d
192.82, 192.05, 151.13,
d
7.59 (q, 4H, J¼7.7 Hz), 7.47 (d, 2H, J¼8.5 Hz), 7.41e7.38 (m, 2H),
1.33 (t, 9H, J¼5.3 Hz); 13C NMR (CDCl3, 100 MHz):
d 152.46, 131.89,
137.27, 135.44, 132.35, 130.93, 130.03, 129.20, 124.09; MS
(C14H9NO4): 255.2 (Mþ).
131.89, 131.43, 128.39, 125.41, 119.05, 118.47, 111.11, 93.98, 87.08,
34.78, 31.01; IR (KBr, cmꢁ1):
n 3078, 3039, 2957, 2861, 2228, 2215;
HRMS-ESI (m/z): [MþH]þ calcd for C19H18N 260.1439; found
4.3.7. 1-(4-Cyanophenyl)-2-phenylethane-1,2-dione (2g).5d Yellow
solid, mp 111e112 ꢀC; 1H NMR (CDCl3, 400 MHz):
d 8.08e8.06 (m,
260.1436.
2H), 7.97e7.94 (m, 2H), 7.81e7.78 (m, 2H), 7.68e7.66 (m, 1H), 7.52
(t, 2H, J¼7.8 Hz); 13C NMR (CDCl3, 100 MHz):
d 192.94, 192.34,
4.2.3. 1-[2-(4-Fluorophenyl)ethynyl]naphthalene (1q). Yellow oil;
yield: 70%; 1H NMR (CDCl3, 400 MHz):
d
8.40 (d, 1H, J¼8.2 Hz), 7.85
135.83, 135.34, 132.69, 132.39, 132.11, 130.15, 129.99, 129.96, 129.15,
128.58, 117.84, 117.51; MS (C15H9NO2): 235.2 (Mþ).
(t, 2H, J¼8.5 Hz), 7.73 (d, 1H, J¼7.0 Hz), 7.61 (m, 3H), 7.54 (m, 1H),
7.46 (t, 1H, J¼7.8 Hz), 7.08 (t, 2H, J¼8.6 Hz); 13C NMR (CDCl3,
4.3.8. 1-(4-Formylphenyl)-2-phenylethane-1,2-dione (2h).5d Yellow
100 MHz):
d
162.57 (d, J¼248.1 Hz), 133.53 (d, J¼8.3 Hz), 133.19,
solid, mp 64e67 ꢀC; 1H NMR (CDCl3, 400 MHz):
d
10.12 (s, 1H), 8.14
(d, 2H, J¼8.3 Hz), 8.03e7.97 (m, 4H), 7.69 (t, 1H, J¼7.4 Hz),
7.56e7.50 (m, 2H); 13C NMR (CDCl3, 100 MHz):
193.53, 193.40,
130.35, 128.83, 128.34, 126.79, 126.45, 126.11, 125.27, 120.69, 119.48
(d, J¼3.5 Hz), 115.73 (d, J¼21.9 Hz), 93.17, 87.19; IR (KBr, cmꢁ1):
2965, 2920, 2849, 2211; HRMS-ESI (m/z): [MþH]þ calcd for C18H12
247.0923; found 247.0928.
n
F
d
191.29, 139.98, 136.96, 135.21, 132.55, 130.36, 129.94, 129.92, 129.11;
MS (C15H10NO3): 238.1 (Mþ).
4.3. General procedures for oxidation of alkynes
4.3.9. 1-(4-Fluorophenyl)-2-phenylethane-1,2-dione (2i).5d Yellow
Alkyne (0.5 mmol), Pd(OAc)2 (10 mol %), and CuBr2 (10 mol %)
were added to DMSO (2.0 mL) in an oven-dried flask under air. The
reaction mixture was heated in an oil bath at designated temper-
ature for 20 h. After the reaction was complete, 10 mL water was
added and the mixture was extracted with ethyl acetate. The
combined organic phases were dried over anhydrous Na2SO4 and
filtered. The solvent was removed under reduced pressure. The
residue was purified by column chromatography (hexane/ethyl
acetate) to afford the pure products.
solid, mp 68e70 ꢀC; 1H NMR (CDCl3, 400 MHz):
d 8.04e8.00 (m,
2H), 7.98e7.96 (m, 2H), 7.66e7.67 (m, 1H), 7.51 (t, 2H, J¼7.8 Hz), 7.18
(t, 2H, J¼8.6 Hz); 13C NMR (CDCl3, 100 MHz):
d 194.05, 192.71,
166.75 (d, J¼256.6 Hz), 134.98, 132.81, 132.70 (d, J¼10.0 Hz), 129.89,
129.47 (d, J¼1.9 Hz), 129.03, 116.37 (d, J¼22.1 Hz); MS (C14H9O2F):
228.2 (Mþ).
4.3.10. 1-(4-Trimethylsilylphenyl)-2-phenylethane-1,2-dione
(2j). Yellow solid, mp 60e63 ꢀC; 1H NMR (CDCl3, 400 MHz):

4954
A. Gao et al. / Tetrahedron 68 (2012) 4950e4954
d
7.97e7.90 (m, 4H), 7.67e7.63 (m, 3H), 7.48 (t, 2H, J¼7.8 Hz), 0.29
134.06, 132.79 (d, J¼9.7 Hz), 130.92, 129.83 (d, J¼2.9 Hz), 129.51,
(s, 9H); 13C NMR (CDCl3, 100 MHz):
d
194.85, 194.61, 149.89, 134.79,
128.81, 128.45, 127.16, 125.86, 124.39, 116.38 (d, J¼22.1 Hz); IR (KBr,
133.79, 133.00, 132.96, 129.83, 128.96, 128.61, -1.49; IR (KBr, cmꢁ1):
n
cmꢁ1):
n
2968, 2925, 2851, 1668; HRMS-ESI (m/z): [MþNa]þ calcd
3066, 2957, 2897, 2802, 1675; HRMS-ESI (m/z): [MþNa]þ calcd for
for C18H11O2FNa 301.0641; found 301.0636.
C17H18O2SiNa 305.0974; found 305.0971.
4.3.18. 1-Phenylpropane-1,2-dione (2r).8c Yellow oil; 1H NMR
4.3.11. 1-(4-Ethylphenyl)-2-(p-tolyl)ethane-1,2-dione (2k). Yellow
(CDCl3, 400 MHz):
d
8.00 (d, 2H, J¼8.0 Hz), 7.63 (t, 1H, J¼7.4 Hz),
solid, mp 62e65 ꢀC; 1H NMR (CDCl3, 400 MHz):
d
7.85 (t, 4H,
7.49 (t, 2H, J¼7.7 Hz), 2.52 (s, 3H); 13C NMR (100 MHz, CDCl3):
J¼8.8 Hz), 7.31e7.27 (m, 4H), 2.70 (q, 2H, J¼7.6 Hz), 2.40 (s, 3H), 1.23
d 200.47, 191.34, 134.53, 131.73, 130.26, 128.79, 26.31; MS (C9H8O2):
(t, 3H, J¼7.6 Hz); 13C NMR (CDCl3, 100 MHz):
d
194.48, 152.13,
148.2 (Mþ).
146.02, 130.84, 130.66, 130.07, 129.95, 129.65, 128.49, 29.12, 21.85,
15.00; IR (KBr, cmꢁ1):
n 3029, 2968, 2931, 2875, 1668; HRMS-ESI
Acknowledgements
(m/z): [MþNa]þ calcd for C17H16O2Na 275.1048; found 275.1045.
We are grateful to the National Natural Science Foundation of
China (Nos. 21172200, 21102134) and the Innovation Fund for
Outstanding Scholar of Henan Province (No. 621001100) for fi-
nancial support to this research.
4.3.12. 1-(4-Ethylphenyl)-2-(4-methoxyphenyl)ethane-1,2-dione
(2l). Yellow oil; 1H NMR (CDCl3, 400 MHz):
d 7.94e7.89 (m, 2H),
7.86 (d, 2H, J¼8.2 Hz), 7.29 (d, 2H, J¼8.2 Hz), 6.96e6.92 (m, 2H),
3.85 (s, 3H), 2.69 (q, 2H, J¼7.6 Hz), 1.22 (t, 3H, J¼7.6 Hz); 13C NMR
(CDCl3, 100 MHz):
d 194.59, 193.37, 164.86, 152.06, 132.29, 130.93,
References and notes
130.08, 128.46, 126.14, 114.27, 55.57, 29.11, 15.00; IR (KBr, cmꢁ1):
n
2968, 2934, 2841, 1665; HRMS-ESI (m/z): [MþNa]þ calcd for
1. (a) Babudri, F.; Fiandanese, V.; Marchese, G.; Punzi, A. Tetrahedron Lett. 1995, 36,
7305e7308; (b) De Kimpe, N.; Stanoeva, E.; Boeykens, M. Synthesis 1994,
427e431 and references cited therein.
C17H16O3Na 291.0997; found 291.0994.
2. (a) Singh, S. K.; Saibaba, V.; Ravikumar, V.; Rudrawar, S. V.; Daga, P.; Rao, C. S.;
Akhila, V.; Hegde, P.; Rao, Y. K. Bioorg. Med. Chem. 2004, 12, 1881e1893; (b)
McKenna, J. M.; Halley, F.; Souness, J. E.; McLay, I. M.; Pickett, S. D.; Collis, A. J.;
Page, K.; Ahmed, I. J. Med. Chem. 2002, 45, 2173e2184; (c) Callahan, J. F.; Burgess,
J. L.; Fornwald, J. A.; Gaster, L. M.; Harling, J. D.; Harrington, F. P.; Heer, J.; Kwon,
C.; Lehr, R.; Mathur, A.; Olson, B. A.; Weinstock, J.; Laping, N. J. J. Med. Chem.
2002, 45, 999e1001; (d) Barta, T. E.; Stealey, M. A.; Collins, P. W.; Weier, R. M.
Bioorg. Med. Chem. Lett. 1998, 8, 3443e3448.
4.3.13. 1-(4-Methoxyphenyl)-2-(4-pentyloxyphenyl)ethane-1,2-
dione (2m). Yellow oil; 1H NMR (CDCl3, 400 MHz):
d 7.96e7.92 (m,
4H), 6.98e6.94 (m, 4H), 4.03 (t, 2H, J¼6.5 Hz), 3.88 (s, 3H),
1.83e1.79 (m, 2H), 1.46e1.37 (m, 4H), 0.93 (t, 3H, J¼7.1 Hz); 13C
NMR (CDCl3, 100 MHz):
d 193.45, 193.39, 164.69, 164.39, 132.24,
126.19, 125.88, 114.58, 114.14, 68.33, 55.50, 28.56, 27.93, 22.26,
3. (a) Hui, X.; Desrivot, J.; Bories, C.; Loiseau, P. M.; Franck, X.; Hocquemiller, R.;
13.86; IR (KBr, cmꢁ1):
n 2965, 2932, 2858, 1672, 1666; HRMS-ESI
ꢀ
Figadere, B. Bioorg. Med. Chem. 2006, 16, 815e820; (b) Li, X.; Zhao, G.; Cao, W.-G.
(m/z): [MþNa]þ calcd for C20H22O4Na 349.1416; found 349.1413.
Chin. J. Chem. 2006, 24, 1402e1405; (c) Bhosale, R. S.; Sarda, S. R.; Ardhapure, S.
S.; Jadhav, W. N.; Bhusare, S. R.; Pawar, R. P. Tetrahedron Lett. 2005, 46,
7183e7186; (d) Wolkenberg, S. E.; Wisnoski, D. D.; Leister, W. H.; Wang, Y.; Zhao,
Z.; Lindsley, C. L. Org. Lett. 2004, 6, 1453e1456; (e) Deng, X.-H.; Mani, N. S. Org.
Lett. 2006, 8, 269e271; (f) Prasad, K. R. K.; Joshi, N. N. J. Org. Chem. 1996, 61,
3888e3889.
4.3.14. 1-(4-tert-Butylphenyl)-2-(4-cyanophenyl)ethane-1,2-dione
(2n).8a Yellow solid, mp 59e62 ꢀC; 1H NMR (CDCl3, 400 MHz):
d
8.08 (d, 2H, J¼8.4 Hz), 7.90 (d, 2H, J¼8.6 Hz), 7.81 (d, 2H, J¼8.4 Hz),
4. (a) Mousset, C.; Giraud, A.; Provot, O.; Hamze, A.; Bignon, J.; Liu, J.-M.; Thoret, S.;
7.55 (d, 2H, J¼8.6 Hz), 1.35 (s, 9H); 13C NMR (100 MHz, CDCl3):
Dubois, J.; Brion, J.-D.; Alami, M. Bioorg. Med. Chem. Lett. 2008, 18, 3266e3271;
ꢂ
d
192.72, 192.63, 159.71, 135.98, 132.69, 130.18, 130.01, 129.87,
ꢁ
ꢁꢂ
ꢁꢂ
ꢂ
(b) Kosa, C.; Mosnacek, J.; Lukac, I.; Hrdlovic, P.; Chmela, S; Habicher, W. D. J.
126.23, 117.75, 117.61, 35.47, 30.92; MS (C19H17NO2): 291.3 (Mþ).
ꢁ
ꢁꢂ
Appl. Polym. Sci. 2006, 100, 4420e4428; (c) Husar, B.; Commereuc, S.; Lukac, I.;
Chmela, S; Nedelec, J. M.; Baba, M. J. Phys. Chem. B 2006, 110, 5315e5320; (d)
ꢂ
Corrales, T.; Catalina, F.; Peinando, C.; Allen, N. S. J. Photochem. Photobiol., A 2003,
159, 103e114; (e) Mosnacek, J.; Weiss, R. G.; Lukac, I. Macromolecules 2002, 35,
3870e3875.
4.3.15. 1-Phenyl-2-(pyridin-3-yl)ethane-1,2-dione
(2o).8c Yellow
d 9.17(m, 1H),
ꢁꢂ
ꢁꢂ
solid, mp: 62e65 ꢀC; 1H NMR (CDCl3, 400 MHz):
5. (a) Muzart, J. J. Mol. Catal. A: Chem. 2011, 338, 7e17; (b) Xu, C.-F.; Xu, M.; Jia, Y.-X.;
Li, C.-Y. Org. Lett. 2011, 13, 1556e1559; (c) Ren, W.; Liu, J.-F.; Chen, L.; Wan, X.-B.
Adv. Synth. Catal. 2010, 352, 1424e1428; (d) Ren, W.; Xia, Y.-Z.; Ji, S.-J.; Zhang, Y.;
Wan, X.-B.; Zhao, J. Org. Lett. 2009, 8, 1841e1844; (e) Chu, J.-H.; Chen, Y.-J.; Wu,
M.-J. Synthesis 2009, 13, 2155e2162; (f) Mousset, C.; Provot, O.; Hamze, A.;
Bignonb, J.; Brion, J.-D.; Alami, M. Tetrahedron 2008, 64, 4287e4294; (g) Wan, Z.;
Jones, C. D.; Mitchell, D.; Pu, J. Y.; Zhang, T. Y. J. Org. Chem. 2006, 71, 826e828; (h)
Giraud, A.; Provot, O.; Peyrat, J.-F.; Alami, M.; Brion, J.-D. Tetrahedron 2006, 62,
7667e7673; (i) Katritzky, A. R.; Zhang, D.; Kirichenko, K. J. Org. Chem. 2005, 70,
3271e3274; (j) Antoniotti, S.; Dunach, E. Eur. J. Org. Chem. 2004, 3459e3464; (k)
Chang, C.-L.; Kumar, M.-P.; Liu, R.-S. J. Org. Chem. 2004, 69, 2793e2796; (l)
Khurana, J. M.; Kandpal, B. M. Tetrahedron Lett. 2003, 44, 4909e4912; (m) Yu-
subov, M. S.; Filimonov, V. D.; Chi, K.-W. Russ. Chem. Bull. 2001, 50, 649e653; (n)
Dayan, S.; Ben-David, I.; Rozen, S. J. Org. Chem. 2000, 65, 8816e8818; (o) Che, C.-
M.; Yu, W.-Y.; Chan, P.-M.; Cheng, W.-C.; Peng, S.-M.; Lau, K.-C.; Li, W.-K. J. Am.
Chem. Soc. 2000, 122, 11380e11392.
8.88e8.86 (m, 1H), 8.31e8.29 (m, 1H), 8.01e7.99 (m, 2H), 7.69e7.67
(m, 1H), 7.56e7.47 (m, 3H); 13C NMR (CDCl3, 100 MHz):
d
192.85,
192.69, 154.76, 151.27, 136.83, 135.22, 132.42, 129.99, 129.09, 128.64,
123.83; MS (C13H9NO2): 211.2 (Mþ).
4.3.16. 1-(Naphthalen-1-yl)-2-phenylethane-1,2-dione
(2p).8d Yellow solid, mp 60e62 ꢀC; 1H NMR (400 MHz, CDCl3):
d
9.30 (d, 1H, J¼8.6 Hz), 8.09 (d, 1H, J¼8.2 Hz), 8.01e8.03 (m, 2H),
7.93e7.89 (m, 2H), 7.73e7.71 (m, 1H), 7.64e7.61 (m, 2H), 7.51e7.46
(m, 3H); 13C NMR (CDCl3, 100 MHz):
197.11, 194.52, 135.91, 135.00,
d
134.69,134.03,133.33,130.89,129.95,129.39,128.98,128.76,128.57,
127.07, 125.88, 124.37; MS (C18H12O): 260.3 (Mþ).
6. (a) Doucet, H.; Hierso, J.-C. Angew. Chem., Int. Ed. 2007, 46, 834e871; (b) Chin-
chilla, R.; Najera, C. Chem. Rev. 2007, 107, 874e922.
4.3.17. 1-(4-Fluorophenyl)-2-(naphthalen-1-yl)ethane-1,2-dione
7. (a) Yang, F.; Cui, X.-L.; Li, Y.-N.; Zhang, J.-L.; Ren, G.-R.; Wu, Y.-J. Tetrahedron 2007,
63, 1963e1969; (b) Yang, F.; Wu, Y.-J. Eur. J. Org. Chem. 2007, 3476e3479.
8. (a) Friedman, A.; Gugig, W.; Mehr, L.; Becker, E. I. J. Org. Chem. 1959, 24, 516e520;
(b) Thomas, K. R. J.; Lin, J. T.; Tao, Y.-T.; Chuen, C.-H. Adv. Mater. 2002, 14,
822e826; (c) Walsh, C. J.; Mandal, B. K. J. Org. Chem. 1999, 64, 6102e6105; (d)
Montevecchi, P. C.; Navacchia, M. L.; Spagnolo, P. Tetrahedron 2008, 64,
7929e7936.
(2q). Yellow solid, mp 67e70 ꢀC; 1H NMR (CDCl3, 400 MHz):
d 9.28
(d, 1H, J¼8.6 Hz), 8.13 (d, 1H, J¼8.2 Hz), 8.08e8.05 (m, 2H), 7.94 (d,
1H, J¼7.9 Hz), 7.89 (d, 1H, J¼7.2 Hz), 7.75e7.76 (m, 1H), 7.63e7.64
(m, 1H), 7.52e7.48 (m, 1H), 7.22e7.17 (m, 2H); 13C NMR (100 MHz,
CDCl3):
d
196.66, 192.86, 166.65 (d, J¼256.4 Hz), 136.11, 135.05,