A clean, facile, and stereospecific synthesis of α-oxoketene O,S-acetals in water

Article abstract of DOI:10.1055/s-0028-1083333

A facile and practical method for the stereospecific synthesis of α-oxoketene O,S-acetals in water has been developed. Catalyzed by tetrabutylammonium bromide at room temperature, the one-pot reaction of various β-dicarbonyl compounds, 2-bromoethanol, and

Full text of DOI:10.1055/s-0028-1083333

824
PAPER
A Clean, Facile, and Stereospecific Synthesis of a-Oxoketene O,S-Acetals in
Water
Synthesis of
a
-Oxo
a
ketene
O
,
S
n
-Acetals in
Water Li, Qian Zhang,* Xin Cheng, Qun Liu,* Xiaohong Xu
Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. of China
E-mail: zhangq651@nenu.edu.cn
Received 25 September 2008; revised 6 November 2008
O
O
O
Abstract: A facile and practical method for the stereospecific syn-
R2
R1
R2
S
CS2, BrCH2CH2OH
thesis of a-oxoketene O,S-acetals in water has been developed. Cat-
alyzed by tetrabutylammonium bromide at room temperature, the
one-pot reaction of various b-dicarbonyl compounds, 2-bromoetha-
nol, and carbon disulfide, in the presence of potassium carbonate,
leads to the corresponding a-oxoketene O,S-acetals stereospecifi-
cally in good to excellent yields. The catalyst in the aqueous phase
can be recycled after the separation of the organic products.
K2CO3, TBAB, H2O
r.t.
R1
O
O
1
2
Scheme 1
Key words: a-oxoketene O,S-acetals, one-pot synthesis, stereo-
some organic reactions.7 Organic reactions in water, with-
out the use of an organic solvent, also benefit from the fact
that water is an easily available, inexpensive, safe, and en-
vironmentally benign solvent. Later, extensive work re-
vealed that a variety of organic reactions8 including the
aldol,9a allylation,9b Diels–Alder,9c Michael,9d Mannich-
type,9e and even dehydration reactions9f can be realized in
the presence of various catalysts, such as inverse phase-
transfer catalysts and surfactant-type Lewis or Brønsted
acids, in water. As part of our research on the chemistry of
a-EWG ketene S,S-acetals10–13 and encouraged by our re-
cent report on their clean syntheses,13 herein, the success-
fully synthesis of a-oxoketene O,S-acetals in water is
realized.
specificity, tetrabutylammonium bromide, water
Over the past decades, the utility of a-oxoketene S,S-ace-
tals as versatile intermediates1 and odorless thiol
equivalents2 in organic synthesis has been recognized. In
contrast, the chemistry of a-oxoketene O,S-acetals has re-
mained largely unexplored. Generally, a-oxoketene O,S-
acetals are prepared via alkylation of xanthates3 or dis-
placement of the alkylsulfanyl group of an a-oxoketene
dithioacetal by a alkoxy group.4 However, these methods
require a two-step operation starting from an active meth-
ylene compound. Although it has been reported that a-oxo-
ketene O,S-acetals can be prepared directly from b-
dicarbonyl compounds, 2-bromoethanol, and carbon dis-
ulfide under basic conditions, the product yields were rel-
atively low (24–58%) because the corresponding a-
oxoketene S,S-acetals were formed as the byproducts (18–
26%).5 In a recent report by Vila and co-workers, some a-
EWG ketene O,S-acetals (EWG = electron-withdrawing
group) and analogues were synthesized from the reaction
of dithiocarbonates (xanthates) with base and an alkylat-
ing agent through extrusion of sulfur.6 However, insepa-
rable mixtures of geometrical isomers were observed
when two different EWGs were present in the starting
xanthates. In this paper, we would like to report a facile
and practical method for the synthesis of a-oxoketene
O,S-acetals. As a result, a-oxoketene O,S-acetals 2 were
synthesized stereospecifically from the reaction of b-di-
carbonyl compounds 1, carbon disulfide, and 2-bromo-
ethanol under basic conditions in a one-pot procedure
with water as the solvent (Scheme 1).
In the initial experiment, we first tested the reaction by
mixing N-(2-methoxyphenyl)-3-oxobutanamide (1a, 1.0
equiv) with carbon disulfide (1.1 equiv), 2-bromoethanol
(1.2 equiv), potassium carbonate (4.0 equiv), and tetrabu-
tylammonium bromide (0.1 equiv) in water (10 mL); after
12 hours at room temperature, the desired N-(2-methoxy-
phenyl)-2-(1,3-oxathiolan-2-ylidene)-3-oxobutanamide
(2a) was obtained in 61% yield together with the corre-
sponding dithioacetal 3a (Table 1, entry 1) as a byproduct
in 11% yield. To optimize the reaction conditions, several
reactions were carried out and the results are listed in
Table 1. It was found that the feed order of the reagents
had a substantial effect on the dispersion of product
(Table 1, entries 1–3). For example, following the proce-
dure described in our previous work,13a the reaction was
performed with 1a (1.0 equiv) and carbon disulfide (1.1
equiv) in the presence of potassium carbonate (4.0 equiv)
and tetrabutylammonium bromide (0.1 equiv) in water (10
mL) at room temperature for one hour and subsequent
alkylation with 2-bromoethanol (1.2 equiv) for another 12
hours to afford the desired 2a in 35% yield and the corre-
sponding dithioacetal 3a in 60% yield (Table 1, entry 2).
When the mixture of 1a (1.0 equiv), potassium carbonate
(4.0 equiv), tetrabutylammonium bromide (0.1 equiv),
and water (10 ml) was stirred at room temperature for one
The use of water as a solvent in organic chemistry was re-
discovered in the 1980s in Breslow’s work, which showed
that a hydrophobic effect can strongly enhance the rates of
SYNTHESIS 2009, No. 5, pp 0824–0828
x
x
.
x
x
.2
0
0
9
Advanced online publication: 27.01.2009
DOI: 10.1055/s-0028-1083333; Art ID: F20608SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of a-Oxoketene O,S-Acetals in Water
825
Table 1 Reaction of 1a with Carbon Disulfide and 2-Bromoethanol in Water under Different Conditionsa
O
O
O
S
O
S
O
S
K2CO3, CS2,
O
O
BrCH2CH2OH
N
+
N
H
H
TBAB, H2O
r.t.
N
OMe
OMe
H
OMe
1a
2a
3a
Entry
TBAB (mmol)
K2CO3 (mmol)
H2O (mL)
Time (h)
Yield (%)
2ab
3a
1
2
0.5
20
20
20
15
25
20
20
20
20
20
20
10
10
10
10
10
10
10
10
0
12
13
14
18
14
12
16
24
14
14
15
61
35
81
61c
82
80
54d
0
11
0.5
60
3
0.5
trace
trace
trace
trace
trace
trace
0
4
0.5
5
0.5
6
1.25
0.25
0.0
7
8
9
2nd usee
3nd usef
4nd useg
78
77
70
10
11
0
trace
trace
0
a 1a (5 mmol), CS2 (6 mmol), 2-bromoethanol (5.5 mmol) were added in all the reactions.
b Isolated yields.
c The substrate was recovered in 36% yield.
d The substrate was recovered in 29% yield.
e Aqueous filtrate from entry 3.
f Aqueous filtrate from entry 9.
g Aqueous filtrate from entry 10.
hour and subsequent co-addition of carbon disulfide (1.1 products 2k–m were also formed stereospecifically (Z or
equiv) and 2-bromoethanol (1.2 equiv) in one portion and E configuration).
then stirred for 13 hours, product 2a was obtained in 81%
Based on the experimental results mentioned above, a
yield with a trace amount of 3a (entry 3). It was also found
possible mechanism for the reaction of 1 with carbon
that 4.0 equiv of potassium carbonate and 10 mol% of tet-
disulfide and 2-bromoethanol is proposed as shown in
rabutylammonium bromide was enough to provide 2a ef-
Scheme 2. The intermediate 1,3-oxathiolane-2-thione A
ficiently (entries 4–8). In addition, the catalyst (TBAB)
is initially generated in the presence of potassium carbon-
can be recycled, at least several times, by reuse of the
ate. Next nucleophilic attack of the deprotonated active
methylene compounds 4 on A occurs to form intermediate
6, which could be stabilized by the intramolecular
aqueous phase after the separation of organic products
(entries 9–11). Surprisingly, 2a was found to be the only
regioisomer (Z-configuration) with OCH2 cis to the acetyl
group as observed in its X-ray diffraction analysis
(Figure 1).14
To test the general applicability of this protocol, a series
of active methylene compounds 1b–p were selected for
investigation. Subjected to the optimized reaction condi-
tions as described in Table 1, entry 3, acetylacetamide
compounds 1a–j (Table 2, entries 1–10) were converted
into the corresponding O,S-acetals 2a–j in high yields. In
addition, the O,S-acetals 2k–p (Table 2, entries 11–16)
were obtained in moderate to good yields starting from ac-
tive methylene compounds 1k–p. It is worth noting that
Figure 1 The ORTEP drawing of 2a
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826
Y. Li et al.
PAPER
Table 2 Preparation of a-Oxoketene O,S-Acetals 2 from Active
Methylene Compounds 1 in Water
S
K2CO3
O
S
+
CS2
BrCH2CH2OH
O
O
O
R2
R1
R2
R1
R2
R1
S
S
S
K2CO3, TBAB, H2O
A
+
CS2, BrCH2CH2OH
r.t.
TBA
R1
O
O
O
O
O
K2CO3, H2O
TBAB
A
O
O
O
R1
O
R2
R2
H2O
1
2
3
1
4
– TBAB
Entry Product R1
R2
Time
(h)
Yield (%)
of 2/3a
R1
O
O
O
O
O
– H2S
1
2
2a
2b
2c
2d
2e
2f
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Ph
2-MeOC6H4NH
2-ClC6H4NH
2-MeC6H4NH
NHPh
14
12
12
13
15
13
16
14
12
13
22
20
14
20
22
19
81/–b
82/–b
86/–b
80/–b
82/–b
76/–b
81/–b
80/–b
67/10
70/8
O
R2
R1
R2
R1
R2
SH
SH
H
O
S
S
O
S
6
2
5
3
O
S
O
O
O
4
R1
R2
CS2
R1
R2
BrCH2CH2OH
– TBAB
5
4-ClC6H4NH
4-MeC6H4NH
4-MeOC6H4NH
2,4-Me2C6H3NH
NHMe
4
OH
S
S
S
6
TBA
7
8
O
O
O
O
7
2g
2h
2i
R1
R2
K2CO3
TBAB
R1
R2
8
S
S
S
S
9
TBA
9
3
HO
10
11
12
13
14
15
16
2j
NH2
Scheme 2 A proposed mechanism for the reaction of 1 with carbon
disulfide and 2-bromoethanol in the presence of tetrabutylammonium
bromide and potassium carbonate in water
2k
2l
OEt
65/12
70/10
63/13
60/12
32/18
54/16
Ph
2m
2n
2o
2p
OEt
um carbonate in water. The simple procedure, mild condi-
tions, good yields, and, especially, the relation to the
current environmental concerns, make this protocol most
attractive for academic research and practical applica-
tions.
Me
OEt
Ph
Me
OEt
Ph
a Isolated yields.
b A trace amount of 3 was detected.
All reagents were purchased from commercial sources and used
without treatment, unless otherwise indicated. The products were
purified by column chromatography over silica gel; PE = petroleum
O–H···O bond. The subsequent elimination of H2S affords
(Z)-O,S-acetals 2. Further evidence for the formation of
the intermediate A15 in the above proposed mechanism
1
ether. H NMR and 13C NMR spectra were recorded at 500 MHz
and 125 MHz, respectively, with TMS as internal standard. IR spec-
tra (KBr) were recorded on a FTIR spectrophotometer in the range
was provided by the reaction of carbon disulfide (1.0 of 400–4000 cm–1. Compounds 2k,l,n,o are known compounds.5
equiv) and 2-bromoethanol (1.0 equiv) in the presence of
potassium carbonate (2.2 equiv) and tetrabutylammonium
bromide (0.1 equiv) in water. As a result, A was obtained
in 44% isolated yield. In addition, 2a was obtained in 28%
(Z)-N-(2-Methoxyphenyl)-2-(1,3-oxathiolan-2-ylidene)-3-oxo-
butanamide (2a); Typical Procedure
3-Oxo-N-phenylbutanamide 1a (0.885 g, 5 mmol), K2CO3 (2.758 g,
20 mmol), and TBAB (0.161 g, 0.5 mmol) were dissolved in H2O
yield when the reaction of intermediate A (1.0 equiv) and
1a (1.0 equiv) was performed in the presence of potassium
carbonate (2.2 equiv) and tetrabutylammonium bromide
(0.1 equiv) in water for one hour. On the other hand, the
intermediate 4 reacted with carbon disulfide and 2-bromo-
ethanol to provide intermediate 8 and, thus, lead to the for-
mation of S,S-acetals 3 as byproducts.
(10 mL) at r.t. and stirred for 1.0 h. Then the mixture of CS2 (0.456
g, 6 mmol) and 2-bromoethanol (0.682 g, 5.5 mmol) was added
dropwise. The resulting mixture was stirred for another 13.0 h at r.t.
The precipitated solid was collected by filtration, washed with H2O
(3 × 10 mL). The crude product was purified by flash column chro-
matography (PE–Et2O, 1:2) to afford 2a (1.186 g, 81%) as a white
solid; mp 124–126 °C.
IR (KBr): 2360, 1646, 1362, 1119, 746 cm–1.
In summary, a clean, facile, practical and stereospecific
synthesis of a-oxoketene O,S-acetals has been developed
based on the reaction of active methylene compounds
with carbon disulfide and 2-bromoethanol catalyzed by
tetrabutylammonium bromide in the presence of potassi-
1H NMR (500 MHz, CDCl3): d = 2.54 (s, 3 H), 3.17 (t, J = 7.0 Hz,
2 H), 3.94 (s, 3 H), 4.73 (t, J = 7.0 Hz, 2 H), 6.88 (d, J = 8.5 Hz, 1
H), 6.94 (d, J = 8.0 Hz, 1 H), 7.00 (d, J = 8.0 Hz, 1 H), 8.44 (d,
J = 8.0 Hz, 1 H), 11.68 (s, 1 H).
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Synthesis of a-Oxoketene O,S-Acetals in Water
827
13C NMR (125 MHz, CDCl3): d = 29.8, 33.0, 55.8, 74.3, 107.9,
110.0, 120.4, 120.7, 123.2, 128.5, 148.9, 164.1, 186.1, 197.2.
(Z)-2-(1,3-Oxathiolan-2-ylidene)-3-oxo-N-(4-tolyl)butanamide
(2f)
White solid; mp 152–154 °C.
IR (KBr): 1645, 1455, 1310, 1079, 937 cm–1.
1H NMR (500 MHz, CDCl3): d = 2.30 (s, 3 H), 2.53 (s, 3 H), 3.15
(t, J = 7.5 Hz, 2 H), 4.72 (t, J = 7.5 Hz, 2 H), 7.10 (d, J = 8.0 Hz, 2
H), 7.49 (d, J = 8.5 Hz, 2 H), 11.32 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 20.8, 29.9, 33.1, 74.4, 107.5,
120.5 (2 C), 129.3 (2 C), 133.2, 135.9, 164.1, 186.4, 197.4.
MS (EI): m/z = 278.2 [M + 1]+.
MS (EI): m/z = 294.0 [M + 1]+.
Anal. Calcd for C14H15NO4S: C, 57.32; H, 5.15; N, 4.77. Found: C,
57.20; H, 4.98; N, 4.51.
(Z)-N-(2-Chlorophenyl)-2-(1,3-oxathiolan-2-ylidene)-3-oxo-
butanamide (2b)
White solid; mp 144–146 °C.
IR (KBr): 3105, 3002, 1360, 1652, 1452, 1082, 935 cm–1.
1H NMR (500 MHz, CDCl3): d = 2.56 (s, 3 H), 3.20 (t, J = 7.5 Hz,
2 H), 4.77 (t, J = 7.5 Hz, 2 H), 7.01 (d, J = 7.5 Hz, 1 H), 7.23 (t,
J = 8.0 Hz, 1 H), 7.37 (d, J = 8.0 Hz, 1 H), 8.45 (d, J = 8.5 Hz, 1 H),
11.89 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 29.9, 33.1, 74.6, 107.4, 122.2,
123.7, 123.9, 127.1, 129.1, 135.8, 164.5, 187.0, 197.2.
Anal. Calcd for C14H15NO3S: C, 60.63; H, 5.45; N, 5.05. Found: C,
60.39; H, 5.20; N, 5.31.
(Z)-N-(4-Methoxyphenyl)-2-(1,3-oxathiolan-2-ylidene)-3-oxo-
butanamide (2g)
White solid; mp 136–138 °C.
MS (EI): m/z = 298.2 [M + 1]+.
IR (KBr): 1641, 1452, 1236, 1079, 639 cm–1.
Anal. Calcd for C13H12ClNO3S: C, 52.44; H, 4.06; N, 4.70. Found:
C, 52.09; H, 4.27; N, 4.95.
1H NMR (500 MHz, CDCl3): d = 2.53 (s, 3 H), 3.16 (t, J = 7.0 Hz,
2 H), 3.78 (s, 3 H), 4.73 (t, J = 7.0 Hz, 2 H), 6.84 (d, J = 9.0 Hz, 2
H), 7.50 (d, J = 8.5 Hz, 2 H), 11.25 (s, 1 H).
(Z)-2-(1,3-Oxathiolan-2-ylidene)-3-oxo-N-(2-tolyl)butanamide
(2c)
White solid; mp 120–122 °C.
IR (KBr): 3248, 3038, 2917, 1654, 1305, 1074, 753 cm–1.
1H NMR (500 MHz, CDCl3): d = 2.35 (s, 3 H), 2.55 (s, 3 H), 3.17
(t, J = 7.0 Hz, 2 H), 4.75 (t, J = 7.0 Hz, 2 H), 7.01 (d, J = 7.5 Hz, 1
H), 7.17 (d, J = 7.0 Hz, 1 H), 7.19 (d, J = 8.0 Hz, 1 H), 8.12 (d,
J = 8.0 Hz, 1 H), 11.33 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 18.3, 29.9, 33.19, 74.5, 107.5,
121.9, 123.8, 126.3, 128.3, 130.1, 136.8, 164.2, 186.8, 197.5.
13C NMR (125 MHz, CDCl3): d = 29.9, 33.1, 55.4, 74.4, 107.4,
113.9 (2 C), 122.2 (2 C), 131.7, 155.9, 164.0, 186.3, 197.4.
MS (EI): m/z = 294.3 [M + 1]+.
Anal. Calcd for C14H15NO4S: C, 57.32; H, 5.15; N, 4.77. Found: C,
57.16; H, 4.88; N, 4.81.
(Z)-N-(2,4-Dimethylphenyl)-2-(1,3-oxathiolan-2-ylidene)-
3-oxobutanamide (2h)
White solid; mp 84–86 °C.
IR (KBr): 1653, 1539, 1360, 1073, 938 cm–1.
1H NMR (500 MHz, CDCl3): d = 2.28 (s, 3 H), 2.31 (s, 3 H), 2.56
(s, 3 H), 3.18 (t, J = 7.5 Hz, 2 H), 4.75 (t, J = 7.0 Hz, 2 H), 7.00 (d,
J = 6.0 Hz, 2 H), 7.95 (d, J = 8.0 Hz, 1 H), 11.20 (s, 1 H).
MS (EI): m/z = 278.1 [M + 1]+.
Anal. Calcd for C14H15NO3S: C, 60.63; H, 5.45; N, 5.05. Found: C,
60.35; H, 5.28; N, 5.21.
13C NMR (125 MHz, CDCl3): d = 18.1, 20.8, 29.9, 33.1, 74.4, 107.6,
(Z)-2-(1,3-Oxathiolan-2-ylidene)-3-oxo-N-phenylbutanamide
(2d)
White solid; mp 110–112 °C.
122.2, 126.8, 128.5, 130.8, 133.5, 134.3, 154.9, 164.2, 197.5.
MS (EI): m/z = 292.1 [M + 1]+.
IR (KBr): 3032, 2919, 1651, 1302, 1078, 754 cm–1.
Anal. Calcd for C15H17NO3S: C, 61.83; H, 5.88; N, 4.81. Found: C,
61.55; H, 5.97; N, 4.63.
1H NMR (500 MHz, CDCl3): d = 2.54 (s, 3 H), 3.18 (t, J = 7.5 Hz,
2 H), 4.74 (t, J = 7.5 Hz, 2 H), 7.06 (t, J = 7.5 Hz, 1 H), 7.30 (t,
J = 7.0 Hz, 2 H), 7.61 (t, J = 8.0 Hz, 2 H), 11.41 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 30.1, 33.4, 74.7, 107.6, 120.7 (2
C), 123.9, 129.0 (2 C), 138.7, 164.5, 186.9, 197.7.
(Z)-N-Methyl-2-(1,3-oxathiolan-2-ylidene)-3-oxobutanamide
(2i)
Light yellow solid; mp 136–138 °C.
IR (KBr): 3303, 1647, 1490, 1276, 1176, 1084, 632 cm–1.
1H NMR (500 MHz, CDCl3): d = 2.47 (s, 3 H), 2.87 (s, 3 H), 3.14
(t, J = 7.5 Hz, 2 H), 4.70 (t, J = 7.5 Hz, 2 H), 9.13 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 25.9, 29.8, 33.0, 73.1, 107.2,
166.7, 185.3, 197.1.
MS (EI): m/z = 264.0 [M + 1]+.
Anal. Calcd for C13H13NO3S: C, 59.30; H, 4.98; N, 5.32. Found: C,
59.57; H, 4.62; N, 5.14.
(Z)-N-(4-Chlorophenyl)-2-(1,3-oxathiolan-2-ylidene)-3-oxo-
butanamide (2e)
MS (EI): m/z = 202.1 [M + 1]+.
White solid; mp 171–173 °C.
IR (KBr): 2359, 1646, 1539, 1302, 1077, 935 cm–1.
Anal. Calcd for C8H11NO3S: C, 47.75; H, 5.51; N, 6.96. Found: C,
47.42; H, 5.63; N, 7.09.
1H NMR (500 MHz, CDCl3): d = 2.53 (s, 3 H), 3.19 (t, J = 7.0 Hz,
2 H), 4.76 (t, J = 7.0 Hz, 2 H), 7.25 (d, J = 8.5 Hz, 2 H), 7.57 (d,
J = 8.5 Hz, 2 H), 11.49 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 30.2, 33.4, 74.8, 107.5, 121.9 (2
C), 128.7, 128.9 (2 C), 137.4, 164.6, 187.1, 197.7.
(Z)-2-(1,3-Oxathiolan-2-ylidene)-3-oxobutanamide (2j)
White solid; mp 178–180 °C.
IR (KBr): 3415, 1613, 1455, 1267, 1081 cm–1.
1H NMR (500 MHz, CDCl3): d = 2.47 (s, 3 H), 3.18 (t, J = 7.5 Hz,
2 H), 4.75 (t, J = 7.0 Hz, 2 H), 5.50 (s, 1 H), 8.94 (s, 1 H).
MS (EI): m/z = 298.1 [M + 1]+.
13C NMR (125 MHz, CDCl3): d = 29.9, 33.0, 74.4, 107.0, 168.1,
186.0, 196.5.
Anal. Calcd for C13H12ClNO3S: C, 52.44; H, 4.06; N, 4.70. Found:
C, 52.06; H, 4.24; N, 4.98.
Synthesis 2009, No. 5, 824–828 © Thieme Stuttgart · New York

828
Y. Li et al.
PAPER
MS (EI): m/z = 188.1 [M + 1]+.
(3) Purkayastha, M. L.; Chandrasekharam, M.; Vishwakarma, J.
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Perkin Trans. 1 1994, 1749. (c) Wang, M.; Xu, X.; Sun, S.;
Liu, Q. Synth. Commun. 2004, 34, 287.
Anal. Calcd for C7H9NO3S: C, 44.91; H, 4.85; N, 7.48. Found: C,
45.02; H, 4.97; N, 7.63.
Ethyl 2-(1,3-Oxathiolan-2-ylidene)-3-oxo-3-phenylpropanoate
(2m)
White solid; mp 60–62 °C.
IR (KBr): 3060, 2907, 2341, 1595, 1386, 1014, 930 cm–1.
1H NMR (500 MHz, CDCl3): d = 1.03 (t, J = 7.5 Hz, 3 H), 3.26 (t,
J = 7.0 Hz, 2 H), 4.11 (q, J = 7.0 Hz, 2 H), 4.48 (t, J = 7.0 Hz, 2 H),
7.44 (t, J = 7.5 Hz, 2 H), 7.53 (t, J = 7.0 Hz, 1 H), 7.85 (d, J = 7.0
Hz, 2 H).
13C NMR (125 MHz, CDCl3): d = 14.0, 30.6, 60.5, 73.8, 103.8,
128.3 (2 C), 129.0 (2 C), 132.8, 138.1, 166.5, 175.8, 191.5.
(5) Zhang, S.; Liu, Q.; Chen, Y. Indian J. Chem., Sect. B: Org.
Chem. Incl. Med. Chem. 2000, 39, 147.
(6) Fabre, S.; Vila, X.; Zard, S. Z. Chem. Commun. 2006, 4964.
(7) (a) Breslow, R.; Rideout, D. C. J. Am. Chem. Soc. 1980, 102,
7816. (b) Breslow, R. Acc. Chem. Res. 1991, 24, 159.
(8) (a) Li, C. Chem. Rev. 1993, 93, 2023. (b) Kobayashi, S.;
Manabe, K. Acc. Chem. Res. 2002, 35, 209. (c) Lindström,
U. M. Organic Reactions in Water; Blackwell: Oxford,
2007.
(9) (a) Mase, N.; Nakai, Y.; Ohara, N.; Yoda, H.; Takabe, K.;
Tanaka, F.; Barbas, C. F. III J. Am. Chem. Soc. 2006, 128,
734. (b) Loh, T. P.; Li, X. R. Eur. J. Org. Chem. 1999, 8,
1893. (c) Tiwari, S.; Kumar, A. Angew. Chem. Int. Ed. 2006,
45, 4824. (d) Gu, Y.; Ogawa, C.; Kobayashi, S. Org. Lett.
2007, 9, 175. (e) Hamada, T.; Manabe, K.; Kobayashi, S.
J. Am. Chem. Soc. 2004, 126, 7768. (f) Manabe, K.; Iimura,
S.; Sun, X.-M.; Kobayashi, S. J. Am. Chem. Soc. 2002, 124,
11971.
(10) For selected examples of [5+1] annulation, see: (a) Bi, X.;
Dong, D.; Liu, Q.; Pan, W.; Zhao, L.; Li, B. J. Am. Chem.
Soc. 2005, 127, 4578. (b) Dong, D.; Bi, X.; Liu, Q.; Cong, F.
Chem. Commun. 2005, 3580. (c) Bi, X.; Dong, D.; Li, Y.;
Liu, Q. J. Org. Chem. 2005, 70, 10886. (d) Zhang, Q.; Sun,
S.; Hu, J.; Liu, Q.; Tan, J. J. Org. Chem. 2007, 72, 139.
(e) Zhao, L.; Liang, F.; Bi, X.; Sun, S.; Liu, Q. J. Org. Chem.
2006, 71, 1094. (f) Hu, J.; Zhang, Q.; Yuan, H.; Liu, Q.
J. Org. Chem. 2008, 73, 2442.
(11) For selected examples of intramolecular anti-Michael
reaction, see: (a) Li, Y.; Liang, F.; Bi, X.; Liu, Q. J. Org.
Chem. 2006, 71, 8006. (b) Bi, X.; Zhang, J.; Liu, Q.; Tan, J.;
Li, B. Adv. Synth. Catal. 2007, 349, 2301.
MS (EI): m/z = 279.0 [M + 1]+.
Anal. Calcd for C14H14O4S: C, 60.42; H, 5.07. Found: C, 60.58; H,
4.92.
2-(1,3-Oxathiolan-2-ylidene)-1,3-diphenylpropane-1,3-dione
(2p)
White solid; mp 155–157 °C.
IR (KBr): 1647, 1616, 1595, 1256, 1004, 536 cm–1.
1H NMR (500 MHz, CDCl3): d = 3.27 (t, J = 7.0 Hz, 2 H), 4.55 (t,
J = 7.0 Hz, 2 H), 7.20 (t, J = 7.0 Hz, 2 H), 7.27 (t, J = 7.0 Hz, 1 H),
7.33 (t, J = 7.5 Hz, 2 H), 7.43 (d, J = 7.5 Hz, 1 H), 7.48 (d, J = 7.5
Hz, 2 H), 7.79 (d, J = 7.5 Hz, 2 H).
13C NMR (125 MHz, CDCl3): d = 30.4, 74.1, 113.2, 128.2 (2 C),
128.3 (2 C), 128.5 (2 C), 129.5 (2 C), 131.4, 133, 138.9, 139.7,
180.0, 191.6, 193.6.
MS (EI): m/z = 311.0 [M + 1]+.
Anal. Calcd for C18H14O3S: C, 69.66; H, 4.55. Found: C, 69.95; H,
4.37.
(12) For selected examples of domino reactions, see: (a) Liang,
F.; Zhang, J.; Liu, Q. Adv. Synth. Catal. 2006, 348, 1986.
(b) Liang, F.; Li, D.; Zhang, L.; Gao, J.; Liu, Q. Org. Lett.
2007, 9, 4845. (c) Liang, F.; Li, Y.; Li, D.; Cheng, X.; Liu,
Q. Tetrahedron Lett. 2007, 48, 7938. (d) Chen, L.; Zhao,
Y.; Liu, Q.; Cheng, C.; Piao, C. J. Org. Chem. 2007, 72,
9259.
Acknowledgment
Financial supports of this research by the NNSFC (20772015),
Training Fund of NENU’S Scientific Innovation Project
(NENU-STC07006) and Science Foundation for Young Teachers of
Northeast Normal University (20070305) are gratefully appreciated.
(13) (a) Ouyang, Y.; Dong, D.; Yu, H.; Liang, Y.; Liu, Q. Adv.
Synth. Catal. 2006, 348, 206. (b) Wang, Y.; Dong, D.;
Yang, Y.; Huang, J.; Ouyang, Y.; Liu, Q. Tetrahedron 2007,
63, 2724. (c) Ouyang, Y.; Dong, D.; Pan, W.; Zhang, J.; Liu,
Q. Tetrahedron 2006, 62, 10111.
(14) Crystal data for 3d: C14H15NO4S, white needle crystals,
M = 293.33, monoclinic, C2/c, a = 15.640(5) Å,
b = 8.249(5) Å, c = 23.035(5) Å, a = 90.000(5)°,
b = 106.460(5)°, g = 90.000(5)°, V = 2850(2) Å3, Z = 8,
T = 293(2) K, F000 = 1232, R1 = 0.0490, wR2 = 0.1237. The
CCDC deposition number 661621.
References
(1) For reviews on a-oxoketene S,S-acetals, see: (a) Dieter, R.
K. Tetrahedron 1986, 42, 3029. (b) Junjappa, H.; Ila, H.;
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(2) For selected examples of odorless thiol equivalents, see:
(a) Liu, Q.; Che, G.; Yu, H.; Liu, Y.; Zhang, J.; Zhang, Q.;
Dong, D. J. Org. Chem. 2003, 68, 9148. (b) Dong, D.;
Ouyang, Y.; Yu, H.; Liu, Q.; Liu, J.; Wang, M.; Zhu, J.
J. Org. Chem. 2005, 70, 4535. (c) Dong, D.; Yu, H.;
Ouyang, Y.; Liu, Q.; Bi, X.; Lu, Y. Synlett 2006, 283.
(15) Kihara, N.; Nakawaki, Y.; Endo, T. J. Org. Chem. 1995, 60,
473.
Synthesis 2009, No. 5, 824–828 © Thieme Stuttgart · New York