Pyridine/potassium tert-butoxide catalyzed benzannulation of β-diketones with dimethyl acetylenedicarboxylate

Article abstract of DOI:10.1055/s-0029-1217035

A benzannulation reaction of β-diketones with dimethyl acetylenedicarboxylate catalyzed by pyridine and potassium tertbutoxide is described. Fully substituted benzenes are synthesized from simple and commercially available starting materials under mild co

Full text of DOI:10.1055/s-0029-1217035

PAPER
4137
Pyridine/Potassium tert-Butoxide Catalyzed Benzannulation of b-Diketones
with Dimethyl Acetylenedicarboxylate
Benzannulation
o
i
f
b
-
Dik
n
etones
w
ithDime
t
H
hyl
A
cetylenedica
r
u
boxylate , Ling-Guo Meng, Yan-Ling Liu, Mao Liang, Song Xue*
Department of Applied Chemistry, Tianjin University of Technology, Tianjin 300384, P. R. of China
Fax +86(22)60214250; E-mail: xuesong@ustc.edu.cn
Received 23 July 2009; revised 17 August 2009
to report this procedure to synthesize fully substituted
Abstract: A benzannulation reaction of b-diketones with dimethyl
acetylenedicarboxylate catalyzed by pyridine and potassium tert-
butoxide is described. Fully substituted benzenes are synthesized
from simple and commercially available starting materials under
mild conditions in high yields.
benzenes from the reaction of dimethyl acetylenedicar-
boxylate (4) with b-diketones in the presence of pyridine
and potassium tert-butoxide under mild conditions.
O
O
Key words: benzannulation, dimethyl acetylenedicarboxylate, py-
ridine, b-diketones, potassium tert-butoxide
O
O
O
EtO
OEt
DMAP (20 mol%)
+
R
OEt CH2Cl2, r.t., 3 d
R
1
2
Highly substituted benzenes are important synthetic inter-
mediates in organic chemistry. Great efforts have been
made to develop new methods for the synthesis of these
highly substituted aromatic compounds.1 There are fa-
mous aromatic annulations including transition-metal-
catalyzed cycloaddition,2,3 the Dötz reaction,4 the Reppe
reaction,5 carbonyl condensation reaction,6 and electrocy-
clic reaction.7 Nevertheless, regiochemistry and available
starting materials limit the application of these reactions.
It is still a challenge to develop new methods for the syn-
thesis of highly substituted benzenes.
O
3a: R = Me, 55%
3b: R = Ph, 65%
Scheme 1 DMAP-catalyzed benzannulation of ethyl propiolate
with b-diketones
O
CO2Me
CO2Me
CO2Me
O
O
+
CO2Me
CO2Me
5a
CO2Me
Recently, reaction based on nucleophilic catalysis via
conjugate addition of N- and P-nucleophiles has proven to
be useful in the development of cycloaddition providing
various carbo-8 and heterocycles.9 We reported earlier a
benzannulation reaction of 1,3-dicarbonyl compounds 1
with ethyl propiolate (2) for the synthesis of substituted
aromatic compounds.10 The reaction catalyzed by 4-(di-
methylamino)pyridine (DMAP) under mild conditions af-
forded tetrasubstituted benzenes 3 in moderate yields
(Scheme 1). Acetylenic ketones, in place of ethyl propi-
olate, showed higher reactivity in benzannulation reaction
and gave 1,3,5-trisubstituted benzenes in excellent yields
in the presence of DMAP and b-diketones.11 Our ongoing
interest in the chemistry of zwitterionic species prompted
us to investigate the benzannulation reaction of dimethyl
acetylenedicarboxylate (4) with b-diketones. Previously,
Nair et al. had described an efficient protocol for the syn-
thesis of fully substituted benzenes from the reaction of
dimethyl acetylenedicarboxylate with b-keto esters.12
During the course of our investigation on the reaction of
dimethyl acetylenedicarboxylate (4) with b-diketones
(Scheme 2), it was found that potassium tert-butoxide is
crucial for this benzannulation reaction. Herein, we wish
1a
4
Scheme 2 Reaction of pentane-2,4-dione (1a) with dimethyl acety-
lenedicarboxylate (4)
Our studies were initiated by the addition of 25 mol%
DMAP to a solution of pentane-2,4-dione (1a) and dime-
thyl acetylenedicarboxylate (4) in dimethoxyethane
(DME). However, only 18% yield of the benzannulation
product 5a was obtained after stirring the mixture at room
temperature for 48 hours (Table 1). Pyridine as catalyst
could give the product 5a in 35% yield. The yield of 5a in-
creased to 52% when 25 mol% of potassium tert-butoxide
was added to the reaction mixture in the presence of pyri-
dine. The yield was not improved by further increasing the
amount of potassium tert-butoxide or pyridine to 50
mol%. In the absence of pyridine, potassium tert-butoxide
(50 mol%) gave only 15% yield of the desired product.
The choice of solvent has an effect on the reaction yield.
Acetonitrile as solvent gave the product in 68% yield. Us-
ing tetrahydrofuran, toluene, or DME as solvent, the de-
sired product was produced in a relatively lower yield.
Shortening the reaction time to 12 hours generated 72%
yield of the product. However, the yield decreased signif-
icantly when the reaction time was shortened to 6 hours.
Pyridine is the most suitable organic catalyst. DMAP,
Et3N, and PPh3 instead of pyridine afforded the product 5a
SYNTHESIS 2009, No. 24, pp 4137–4142
x
x.
x
x
.
2
0
0
9
Advanced online publication: 12.10.2009
DOI: 10.1055/s-0029-1217035; Art ID: F14509SS
© Georg Thieme Verlag Stuttgart · New York

4138
B. Hu et al.
PAPER
in 51%, 27%, and 38% yield, respectively. On the other
hand, NaH and NaOMe as additive in place of potassium
tert-butoxide could give the product 5a in 45% and 56%
yield, respectively. When zeolite 4A (120 mg) was used
as additive, the desired product was obtained in 42%
yield.
Table 2 Benzannulation of b-Diketones 1 with Dimethyl Acety-
lenedicarboxylate (4) Catalyzed by Pyridine and KOt-Bu
Entry R1
R2
Product
Yield
(%)a
1
2
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
5a
72
86
83
87
89
86
87
93
88
86
93
91
Ph
5b/6b (2.7:1)b
5c
Table 1 Benzannulation of Pentane-2,4-dione (1a) with Dimethyl
Acetylenedicarboxylate (4)
3
4-MeC6H4
4-MeOC6H4
4-FC6H4
Entry Lewis base
(mol%)
Additive
(mol%)
Solvent
Time Yield
4
5d
(h)
48
24
24
24
24
24
24
24
24
24
24
12
6
(%)a
18
35
52
53
50
15
63
59
59
46
68
72
54
51
27
38
45
56
42
5
5e/6e (1.3:1)b
5f/6f (1:1.6)b
5g/6g (1.3:1)b
5h/6h (1:5.2)b
5i/6i (1:4.1)b
5j/6j (4.5:1)b
5k
1
2
DMAP (25)
pyridine (25)
pyridine (25)
pyridine (25)
pyridine (50)
pyridine (0)
pyridine (25)
pyridine (25)
pyridine (25)
pyridine (25)
pyridine (25)
pyridine (25)
pyridine (25)
DMAP (25)
Et3N (25)
–
DME
6
4-ClC6H4
4-BrC6H4
4-O2NC6H4
3-BrC6H4
2-MeOC6H4
thiophen-2-yl
2-naphthyl
–
DME
7
3
KOt-Bu (25)
KOt-Bu (50)
KOt-Bu (25)
KOt-Bu (50)
KOt-Bu (25)
KOt-Bu (25)
KOt-Bu (25)
KOt-Bu (25)
KOt-Bu (25)
KOt-Bu (25)
KOt-Bu (25)
KOt-Bu (25)
KOt-Bu (25)
KOt-Bu (25)
NaH (25)
DME
8
4
DME
9
5
DME
10
11
12
13
14
15
16
17
6
DME
7
CH2Cl2
THF
5l/6l (2.6:1)b
8
3,4-(MeO)2C6H3 Et
5m/6m (1:1.1)b 85
9
DMF
Ph
Ph
5n
5o
5p
97
96
98
77
10
12
13
14
15
16
17
18
19
20
toluene
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
4-MeC6H4
4-MeOC6H4
(E)-PhCH=CH
4- MeC6H4
Ph
(E)-PhCH=CH 5r
a Isolated yield.
b Determined by 1H NMR analysis.
12
24
24
18
18
18
and potassium tert-butoxide gave a 2.7:1 mixture of two
benzannulation isomers 5b and 6b in 86% yield.
PPh3 (25)
pyridine (25)
pyridine (25)
pyridine (25)
The two isomers could not be separated by column chro-
matography, but their structures were easily assigned on
the basis of NMR spectra. The 13C carbon signal of methyl
group (R2) in the isomer 5b, in which methyl group was
directly attached to the benzene ring, was at about d =
17.1, whereas the 13C carbon signal of methyl group (R2)
in the isomer 6b was positioned at about d = 31.8. The
substituents on the benzene ring have no obvious influ-
ence on the reaction yield, but have remarkable effect on
the selectivity for isomers 5 and 6. As can be seen from
Table 2, an aromatic b-diketone containing an electron-
donating group at para position of its benzene ring pre-
ferred to form the isomer 5. For example, substrate with
methyl group on the aromatic ring afforded the corre-
NaOMe(25)
Zeolite 4A
a Isolated yield.
By using conditions optimized for the formation of 5a, a
variety of b-diketones has been examined (Scheme 3), and
the representative results are shown in Table 2. It was
found that aromatic b-diketones afforded the correspond-
ing products in good to excellent yields. For example,
treatment of 1-phenylbutane-1,3-dione (1b) with dimeth-
yl acetylenedicarboxylate (4) in the presence of pyridine
O
CO2Me
CO2Me
O
CO2Me
CO2Me
CO2Me
pyridine (25 mol%)
KOt-Bu (25 mol%)
R2
O
O
R1
+
+
R1
R2
R1
CO2Me
CO2Me
6
MeCN, r.t., 12 h
R2
CO2Me
CO2Me
5
1
CO2Me
4
Scheme 3
Synthesis 2009, No. 24, 4137–4142 © Thieme Stuttgart · New York

PAPER
Benzannulation of b-Diketones with Dimethyl Acetylenedicarboxylate
4139
sponding product 5c as a colorless crystalline solid in 83% and afforded the corresponding products 5n–p in excel-
yield, and its isomer 6c was not observed. The structure of lent yields.
5c was characterized based on the spectral data and fur-
ther confirmed unambiguously using single crystal X-ray
analysis (Figure 1).13 On the other hand, the aromatic b-
diketone bearing an electron-withdrawing group, such as
a nitro group, at the benzene ring para position afforded
the isomer 6h as the major product. It is notable that these
results are in contrast to our previous observation
(Scheme 1).10 In the course of the benzannulation reaction
of aromatic b-diketones with ethyl propiolate (2), tetra-
substituted benzenes 3 were generated to form a biaryl de-
rivative, in which the aromatic group is directly attached
on benzene ring. In addition, aromatic b-diketone contain-
ing methoxy or methyl group on its aromatic ring gave no
or poor yield of the four-substituted benzene.
Based on the work of Nair et al.,12 a plausible mechanism
of the benzannulation reaction of b-diketone with dimeth-
yl acetylenedicarboxylate is shown in Scheme 4. Pyridine
and potassium tert-butoxide might act as base to deproto-
nate the active methylene of b-diketone to generate the an-
ion 7, which adds to dimethyl acetylenedicarboxylate (4)
to give the intermediate 8. The intermediate 8 reacts with
another molecule of dimethyl acetylenedicarboxylate (4)
to give the intermediate 9, followed by intramolecular nu-
cleophilic addition to form 10. The selectivity for isomers
5 and 6 was determined in this step based on the electronic
effect and steric effect. Subsequently, the intermediate 10
underwent proton transfer and dehydration to give prod-
uct 5.
In summary, we have described a benzannulation reaction
of b-diketones 1 with dimethyl acetylenedicarboxylate (4)
catalyzed by pyridine and potassium tert-butoxide under
mild conditions. This methodology supplies a facile way
to synthesize fully substituted benzenes with high yields
from simple and commercially available starting materi-
als. The presented procedure leads to building blocks and
potential intermediates in organic synthesis.
1H NMR (300 MHz) and 13C NMR (75 MHz) spectra were recorded
on a Bruker AC 300 spectrometer using TMS as an internal stan-
dard. High-resolution mass spectra were obtained with a Micromass
GCT TOF mass spectrometer. IR spectra were recorded on a Per-
kin-Elmer FT210 spectrophotometer. Chromatographic purifica-
tion was performed on silica gel (100–200 mesh) and analytical
TLC on silica gel 60-F254 was detected by fluorescence. Petroleum
ether (PE) used for chromatography was of the fraction boiling in
the range 60–90 °C.
Figure 1 X-ray crystal structure of 5c
The heteroaromatic b-diketone, such as 1-(thiophen-2-
yl)butane-1,3-dione, subjected to this benzannulation re-
action gave the product 5k in 93% yield and its isomer 6k
was not observed. When R1 was an aromatic group, and
R2 was changed from a methyl group to an aromatic
group, the benzannulation reaction proceeded smoothly
Benzannulation of b-Diketones 1 with Dimethyl Acetylenedicar-
boxylate (4); General Procedure
To a stirred solution of the desired b-diketone 1 (0.30 mmol) in
MeCN (2 mL) was added dimethyl acetylenedicarboxylate (4; 107
mg, 0.75 mmol) followed by pyridine (6 mg, 0.075 mmol) and
CO2Me
R1
O
O
O
R2
O
O
O
O
CO2Me
OMe
OMe
4
base
–
R1
R2
R1
R2
–
1
7
8
O
CO2Me
CO2Me
R1
O
R1
O–
R2
MeO2C
O
R1
O
O
R2
R2
CO2Me
CO2Me
CO2Me
CO2Me
–
MeO2C
CO2Me
CO2Me
MeO2C
CO2Me
CO2Me
CO2Me
5
10
9
Scheme 4 Possible mechanism for the reaction of b-diketones with dimethyl acetylenedicarboxylate (4)
Synthesis 2009, No. 24, 4137–4142 © Thieme Stuttgart · New York

4140
B. Hu et al.
PAPER
KOt-Bu (9 mg, 0.075 mmol). The reaction mixture was stirred at r.t.
for 12 h. The solvent was removed under reduced pressure, and the
residue was purified by column chromatography on silica gel using
PE–EtOAc (10:1) as eluent to afford the desired product (Table 2).
1H NMR (300 MHz, CDCl3): d = 7.81–7.77 (s, 2 H), 7.23–7.15 (m,
2 H), 3.93–3.87 (m, 9 H), 3.59 (s, 3 H), 3.55 (s, 3 H for 6e), 2.18 (s,
3 H), 1.96 (s, 3 H for 6e).
13C NMR (75 MHz, CDCl3): d = 202.9, 193.8, 166.7, 165.9, 165.7,
145.5, 143.3, 137.4, 135.7, 133.1, 131.0, 130.8, 130.7, 130.5, 116.6,
115.31, 53.4, 53.3, 53.1, 52.9, 31.3, 17.1.
5a
Yield: 79 mg (72%); oil.
IR (neat): 1733 cm–1.
1H NMR (300 MHz, CDCl3): d = 3.93 (s, 3 H), 3.90 (s, 3 H), 3.88
(s, 3 H), 3.85 (s, 3 H), 2.53 (s, 3 H), 2.31 (s, 3 H).
HRMS (ESI): m/z calcd for C22H19FO9 + Na [M + Na] +: 469.0905;
found: 469.0907.
5f and 6f
Yield: 119 mg (86%); colorless crystalline solid mixture of 5f and
6f (1:1.6). Spectral data are given for the obtained mixture of 5f and
6f.
IR (KBr): 1733, 1674 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.70 (d, J = 8.1 Hz, 2 H), 7.44 (d,
J = 8.1 Hz, 2 H), 7.42 (d, J = 6.3 Hz, 2 H for 6f), 7.14 (d, J = 6.3 Hz,
2 H for 6f), 3.95–3.82 (m, 9 H), 3.59 (s, 3 H), 3.56 (s, 3 H for 6f),
2.17 (s, 3 H), 1.97 (s, 3 H for 6f).
13C NMR (75 MHz, CDCl3): d = 202.7, 194.2, 167.1, 166.7, 166.2,
165.8, 165.7, 165.6, 165.2, 145.5, 143.2, 140.9, 137.5, 137.2, 136.7,
135.8, 135.7, 134.9, 133.8, 133.2, 131.1, 130.6, 130.3, 129.6, 129.2,
128.6, 53.4, 53.3, 53.1, 52.9, 31.4, 17.1.
13C NMR (75 MHz, CDCl3): d = 203.0, 167.1, 166.7, 165.6, 146.3,
137.6, 133.6, 132.5, 130.4, 128.8, 53.3, 53.1, 53.0, 31.8, 16.5.
HRMS (ESI): m/z calcd for C17H18O9 + Na [M + Na]+: 389.0843;
found: 389.0845.
5b and 6b
Yield: 111 mg (86%); colorless crystalline solid mixture of 5b and
6b (2.7:1). Spectral data are given for the obtained mixture of 5b
and 6b.
IR (KBr): 1736, 1678 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.76–7.73 (m, 2 H), 7.64–7.58 (m,
1 H), 7.50–7.48 (m, 2 H), 3.91–3.88 (m, 9 H), 3.55 (s, 3 H), 3.50 (s,
3 H for 6b), 2.19 (s, 3 H), 1.91 (s, 3 H for 6b).
HRMS (ESI): m/z calcd for C22H19ClO9 + Na [M + Na]+: 485.0610;
found: 485.0603.
13C NMR (75 MHz, CDCl3): d = 195.4, 167.3, 166.8, 165.8, 165.3,
143.7, 138.7, 137.4, 135.9, 134.3, 132.5, 131.0, 129.3, 129.2, 128.9,
53.5, 53.3, 53.2, 53.0, 52.8, 14.3.
HRMS (ESI): m/z calcd for C22H20O9 + Na [M + Na]+: 451.0999;
found: 451.1007.
5g and 6g
Yield: 132 mg (87%); colorless crystalline solid mixture of 5g and
6g (1.3:1). Spectral data are given for the obtained mixture of 5g and
6g.
IR (KBr): 1752, 1734 cm–1.
5c
Yield: 110 mg (83%); colorless crystalline solid; mp 140–141 °C.
IR (KBr): 1739 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.62–7.59 (m, 2 H), 7.11–7.07 (m,
2 H), 3.93–3.91 (m, 9 H), 3.60 (s, 3 H), 3.56 (s, 3 H for 6g), 2.18 (s,
3 H), 1.98 (s, 3 H for 6g).
13C NMR (75 MHz, CDCl3): d = 202.5, 194.4, 167.0, 166.5, 166.5,
166.2, 165.8, 165.7, 165.5, 165.2, 145.4, 143.1, 137.4, 137.2, 136.7,
135.7, 135.4, 133.3, 132.5, 132.1, 131.5, 131.1, 130.9, 130.6, 129.6,
123.9, 53.3, 53.2, 53.1, 52.9, 31.4, 17.0.
1H NMR (300 MHz, CDCl3): d = 7.63 (d, J = 7.5 Hz, 2 H), 7.26 (d,
J = 7.5 Hz, 2 H), 3.91 (s, 3 H), 3.90 (s, 3 H), 3.88 (s, 3 H), 3.56 (s,
3 H), 2.42 (s, 3 H), 2.19 (s, 3 H).
13C NMR (75 MHz, CDCl3): d = 194.9, 167.3, 166.8, 165.8, 165.3,
145.3, 143.8, 137.2, 135.8, 134.2, 132.3, 130.6, 129.8, 129.4, 53.3,
53.1, 53.0, 52.8, 21.9, 17.0.
HRMS (ESI): m/z calcd for C22H19BrO9 + Na [M + Na]+: 529.0105;
found: 529.0100.
HRMS (ESI): m/z calcd for C23H22O9 + Na [M + Na] +: 465.1156;
found: 465.1157.
5h and 6h
Yield: 133 mg (93%); colorless crystalline solid mixture of 5h and
6h (1:5.2). Spectral data are given for the obtained mixture of 5h
and 6h.
IR (KBr): 1752, 1734 cm–1.
5d
Yield: 124 mg (87%); colorless crystalline solid; mp 124–125 °C.
IR (KBr): 1752, 1734 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.72–7.70 (d, J = 9.0 Hz, 2 H),
6.95–6.92 (d, J = 9.0 Hz, 2 H), 3.92 (s, 3 H), 3.90 (s, 3 H), 3.88 (s,
3 H), 3.87 (s, 3 H), 3.57 (s, 3 H), 2.19 (s, 3 H).
1H NMR (300 MHz, CDCl3): d = 8.33–8.31(m, 2 H), 7.60–7.58 (m,
2 H), 3.93–3.78 (m, 9 H), 3.63 (s, 3 H for 5h), 3.58 (s, 3 H), 2.18 (s,
1 H for 5h), 2.01(s, 3 H).
13C NMR (75 MHz, CDCl3): d = 193.8, 167.3, 166.9, 165.9, 165.5,
164.5, 143.8, 137.2, 135.9, 132.2, 131.8, 130.7, 130.5, 129.7, 114.4,
55.8, 53.4, 53.2, 53.1, 53.0, 17.1.
HRMS (ESI): m/z calcd for C23H22O10 + Na [M + Na]+: 481.1105;
found: 481.1101.
13C NMR (75 MHz, CDCl3): d = 201.8, 166.0, 165.5, 165.2, 165.0,
148.3, 148.1, 145.6, 137.9, 137.0, 135.8, 135.0, 134.7, 134.2, 131.2,
130.6, 129.9, 129.4, 128.2, 124.1, 123.9, 123.4, 53.2, 53.0, 31.6,
17.1.
HRMS (ESI): m/z calcd for C22H19NO11 + Na [M + Na]+: 496.0850;
found: 496.0846.
5e and 6e
Yield: 119 mg (89%); colorless crystalline solid mixture of 5e and
6e (1.3:1). Spectral data are given for the obtained mixture of 5e and
6e.
IR (KBr): 1752, 1734 cm–1.
5i and 6i
Yield: 134 mg (88%); colorless crystalline solid mixture of 5i and
6i (1:4.1). Spectral data are given for the obtained mixture of 5i and
6i.
IR (KBr): 1752, 1734 cm–1.
Synthesis 2009, No. 24, 4137–4142 © Thieme Stuttgart · New York

PAPER
Benzannulation of b-Diketones with Dimethyl Acetylenedicarboxylate
4141
1H NMR (300 MHz, CDCl3): d = 7.59–7.56 (m, 1 H), 7.38 (s, 1 H),
7.37–7.27 (m, 2 H), 3.93–3.82 (m, 9 H), 3.61 (s, 3 H for 5i), 3.58 (s,
3 H), 2.18 (s, 3 H for 5i), 1.99 (s, 3 H).
13C NMR (75 MHz, CDCl3): d = 202.5, 166.4, 166.2, 165.8, 165.5,
145.3, 138.2, 137.3, 137.1, 136.9, 136.7, 135.7, 133.3, 132.5, 132.0,
131.6, 131.2, 130.9, 130.8, 130.4, 128.1, 122.9, 53.5, 53.3, 53.22,
52.9, 31.4, 17.1.
(m, 1 H), 2.49–2.45 (m, 1 H), 2.23–2.21 (m, 2 H for 6m), 1.21 (t,
J = 6.9 Hz, 3 H), 0.83 (t, J = 7.2 Hz, 3 H for 6m).
13C NMR (75 MHz, CDCl3): d = 206.7, 193.4, 167.3, 167.2, 166.8,
166.4, 166.1, 165.9, 165.6, 154.4, 149.7, 149.6, 149.1, 145.2, 142.9,
142.5, 138.4, 136.7, 132.3, 131.8, 131.3, 131.1, 130.0, 127.8, 125.7,
122.0, 112.4, 111.2, 110.3, 110.0, 56.3, 56.1, 56.0, 53.4, 53.2, 53.1,
53.0, 37.1, 22.8, 14.3, 7.7.
HRMS (ESI): m/z calcd for C22H19BrO9 + Na [M + Na]+: 529.0105;
HRMS (ESI): m/z calcd for C25H26O11 + Na [M + Na]+: 525.1367;
found: 529.0103.
found: 525.1369.
5j and 6j
5n
Yield: 111 mg (86%); colorless crystalline solid mixture of 5j and
Yield: 143 mg (97%); light yellow solid; mp 49–50 °C.
6j (4.5:1). Spectral data are given for the obtained mixture of 5j and
6j.
IR (KBr): 1736, 1662 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.91–7.89 (m, 1 H), 7.57–7.51 (m,
1 H), 7.09–7.04 (m, 1 H), 6.99–6.91 (m, 1 H), 3.93–3.85 (m, 9 H),
3.58 (s, 3 H), 3.55 (s, 3 H), 2.21 (s, 3 H), 1.95 (s, 3 H for 6j).
13C NMR (75 MHz,CDCl3): d = 193.6, 167.5, 167.0, 166.0, 165.7,
159.8, 156.4, 147.2, 137.0, 135.7, 134.9, 131.9, 131.4, 131.1, 129.5,
129.3, 126.2, 121.1, 120.9, 112.6, 111.0, 56.0, 55.5, 53.2, 53.0,
52.9, 52.7, 30.3, 16.8.
IR (KBr): 1739, 1676 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.48–7.40 (m, 3 H), 7.27–7.24 (m,
2 H), 7.13–7.10 (m, 3 H), 7.02–6.98 (m, 2 H), 3.92 (s, 3 H), 3.91 (s,
3 H), 3.62 (s, 3 H), 3.47 (s, 3 H).
13C NMR (75 MHz, CDCl3): d = 195.2, 166.9, 166.5, 165.8, 165.7,
143.3, 140.5, 136.9, 135.2, 133.4, 133.0, 131.8, 131.2, 129.2, 128.9,
128.6, 128.4, 128.1, 53.5, 53.4, 53.1, 52.7.
HRMS (ESI): m/z calcd for C27H22O9 + Na [M + Na]+: 513.1156;
found: 513.1149.
HRMS (ESI): m/z calcd for C23H22O10 + Na [M + Na]+: 481.1105;
5o
found: 481.1104.
Yield: 149 mg (96%); colorless crystalline solid; mp 217–219 °C.
IR (KBr): 1752, 1734 cm–1.
5k
1H NMR (300 MHz, CDCl3): d = 7.39 (d, J = 7.8 Hz, 2 H), 7.25 (d,
J = 8.7 Hz, 2 H), 6.94–6.90 (m, 4 H), 3.89 (s, 3 H), 3.88 (s, 3 H),
3.57 (s, 3 H), 3.49 (s, 3 H), 2.31 (s, 3 H), 2.20 (s, 3 H).
13C NMR (75 MHz, CDCl3): d = 194.5, 166.9, 166.5, 165.8, 165.6,
144.3, 143.4, 140.7, 138.3, 137.1, 134.6, 132.7, 132.3, 131.7, 131.0,
129.4, 129.1, 128.7, 53.4, 53.2, 52.9, 52.6, 21.8, 21.2.
Yield: 121 mg (93%); colorless crystalline solid; mp 106–108 °C.
IR (KBr): 1752, 1734 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.79–7.77 (m, 1 H), 7.27–7.25 (m,
1 H), 7.12–7.09 (m, 1 H), 3.93–3.88 (m, 9 H), 3.61 (s, 3 H), 2.30 (s,
3 H).
13C NMR (75 MHz, CDCl3): d = 187.2, 167.2, 166.7, 165.8, 165.4,
143.9, 142.7, 137.3, 136.1, 135.1, 132.2, 130.7, 128.7, 53.5, 53.3,
53.2, 17.0.
HRMS (ESI): m/z calcd for C29H26O9 + Na [M + Na]+: 541.1469;
found: 541.1463.
HRMS (ESI): m/z calcd for C20H18O9S + Na [M + Na]+: 457.0564;
5p
found: 457.0561.
Yield: 153 mg (98%); colorless crystalline solid; mp 142–143 °C.
IR (KBr): 1752, 1734 cm–1.
5l and 6l
1H NMR (300 MHz, CDCl3): d = 7.47 (d, J = 8.7 Hz, 2 H), 7.16–
7.12 (m, 5 H), 6.73 (d, J = 8.7 Hz, 2 H), 3.92 (s, 3 H), 3.91 (s, 3 H),
3.79 (s, 3 H), 3.62 (s, 3 H), 3.48 (s, 3 H).
Yield: 131 mg (91%); colorless crystalline solid mixture of 5l and
6l (2.6:1). Spectral data are given for the obtained mixture of 5l and
6l.
13C NMR (75 MHz, CDCl3): d = 193.5, 167.0, 166.6, 165.9, 165.8,
163.9, 143.4, 140.5, 137.0, 135.4, 133.4, 132.9, 131.7, 131.1, 130.1,
129.2, 128.6, 128.4, 128.1, 113.8, 55.6, 53.5, 53.4, 53.1, 52.8.
HRMS (ESI): m/z calcd for C28H24O10 + Na [M + Na]+: 543.1262;
found: 543.1254.
IR (KBr): 1736, 1674 cm–1.
1H NMR (300 MHz, CDCl3): d = 8.08 (s, 1 H), 7.97–7.88 (m, 3 H),
7.68–7.56 (m, 3 H), 3.93–3.85 (m, 9 H), 3.49 (s, 3 H), 3.43 (s, 3 H
for 6l), 2.22 (s, 3 H), 1.87 (s, 3 H for 6l).
13C NMR (75 MHz, CDCl3): d = 195.4, 167.3, 166.9, 165.9, 165.3,
145.5, 143.8, 137.4, 136.2, 136.1, 133.9, 133.2, 132.7, 130.7, 130.1,
129.3, 129.0, 128.8, 128.5, 128.1, 127.4, 127.3, 126.2, 123.8, 53.5,
53.3, 53.2, 53.0, 31.3, 15.5.
5r
Yield: 125 mg (77%); colorless crystalline solid; mp 199–201 °C.
IR (KBr): 1752, 1734 cm–1.
HRMS (ESI): m/z calcd for C26H22O9 + Na [M + Na]+: 501.1156;
found: 501.1151.
1H NMR (300 MHz, CDCl3): d = 7.48–7.46 (m, 2 H), 7.38–7.23 (m,
3 H), 7.36–7.33 (m, 4 H), 7.26–7.25 (m, 2 H), 6.93 (d, J = 16.5 Hz,
1 H), 6.88 (d, J = 13.2 Hz, 1 H), 6.73 (d, J = 16.5 Hz, 1 H), 3.91 (s,
6 H), 3.84 (s, 3 H), 3.78 (s, 3 H).
13C NMR (75 MHz, CDCl3): d = 194.5, 167.3, 166.4, 165.9, 146.7,
142.2, 138.8, 137.0, 136.1, 135.5, 134.2, 132.4, 131.9, 131.8, 131.3,
129.2, 128.9, 128.8, 127.1, 122.2, 53.5, 53.4, 53.3.
5m and 6m
Yield: 128 mg (85%); colorless crystalline solid mixture of 5m and
6m (1:1.1). Spectral data are given for the obtained mixture of 5m
and 6m.
IR (KBr): 1752, 1734 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.61–7.59 (m, 1 H), 6.90–6.89 (m,
2 H), 3.96–3.83 (m, 15 H), 3.58 (s, 3 H), 3.54 (s, 3 H), 2.73–2.68
HRMS (ESI): m/z calcd for C31H26O9 + Na [M + Na]+: 565.1469;
found: 565.1461.
Synthesis 2009, No. 24, 4137–4142 © Thieme Stuttgart · New York

4142
B. Hu et al.
PAPER
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Acknowledgment
We are grateful to the National Natural Science Foundation of
China (20772116) and the Tianjin Natural Science Foundation
(09JCZDJC24400) for financial support.
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(13) X-ray data of 5c have been deposited at CCDC as deposition
number CCDC 727040. Empirical Formula: C23H22O9;
Formula Weight: 442.41; Crystal color, Habit: colorless,
prismatic; Crystal Dimensions: 0.12 × 0.10 × 0.08 mm;
Crystal System: monoclinic; Lattice Type: primitive; Lattice
Parameters: a = 13.259 (3) Å, b = 6.2983 (13)Å, c = 26.596
(5) Å, b = 98.07 (3)°, V = 2199.0(8) Å3; Space group: P2 (1)/
c; Z value = 4; Dcalc = 1.336 g/cm3; F000 = 928; Residuals:
R, Rw: 0.0597, 0.1465.
Synthesis 2009, No. 24, 4137–4142 © Thieme Stuttgart · New York