6
6
D. Fang, H.-B. Zhang, and Z.-L. Liu
Vol 47
Table 2
1-Methyl-3-propanesulfonic acid imidazolium hydrogen
1
a
sulfate ([MIMPSA]HSO ). H NMR (300 MHz, D O): d 8.47
(
Reusing of the ionic liquid [TEBSA]ꢂHSO
4
.
4
2
s, 1H, CH), 7.24 (d, J ¼ 1.5 Hz, 1H, CH), 7.17 (d, J ¼ 1.5
Hz, 1H, CH), 4.08 (t, J ¼ 6.9 Hz, 2H, NACH ACACASO ),
.62 (s, 3H, NACH
), 2.64 (t, 2H, J ¼ 7.5 Hz, 2H, NACAC
ACH ASO ), 2.01–2.06 (m, 2H, NACACH C
Entry
Run
Isolated yield (%)
2
3
3
3
1
2
3
4
5
6
7
8
9
Fresh
89
90
90
88
89
90
89
88
88
86
87
13
2
3
2
ACASO
3
).
1
2
3
NMR (75.5 MHz, D O): d 136.53, 124.32, 122.57, 48.13,
2
þ
4
7.66, 36.46, 25.48. MS (m/z): 302.0 (M ), 300.93 (100).
1
-Butyl-3-methylimidazolium hydrogen sulfate ([bmim]
). H NMR (300 MHz, D O): d 8.62 (s, 1H, H-2),
4 2
4
1
HSO
.33v7.38 (m, 2H, H-4, H-5), 4.09 (t, 2H, J ¼ 7.1 Hz), 3.79
(s, 3H), 1.68–1.78 (m, 2H), 1.16–1.24 (m, 2H), 0.79 (t, 3H, J
5
6
7
7
8
13
¼7.4 Hz). C NMR (75.5 MHz, D O): d 136.35, 124.07,
2
þ
1
1
0
1
9
10
122.80, 49.85, 36.33, 31.80, 19.31, 13.25. m/z: 236 (M ), 139
(
þ
100, M -HSO
0
4
).
N,N,N ,N -Tetramethyl-N,N -dipropanesulfonic acid ethyle-
0
0
a
Acidic ionic liquids are 5 mmol benzaldehyde, 5 mmol malononitrile,
ꢁ
1
nediammonium hydrogen sulfate ([EDPSA]ꢂHSO ). H NMR
4
5
mmol dimedone, 0.5 mmol catalyst, 90 C, 1.0 h.
(
8
300 MHz, D O): d 3.60 (s, 4H, ACH A), 3.24 (t, 4H, J ¼
2
2
.4 Hz, ACH
2
A), 2.89 (s, 12H, CH
3
), 2.64 (t, 4H, J ¼ 6.9 Hz,
¼
8.5 Hz, NACH
NACAC ACH ASO
ASO ), 1.53–1.59 (m, 6H, NACACH ACACH ), 1.22–1.30
2
ACACACH
3
), 2.85 (t, 2H, J ¼ 7.0 Hz,
ACH A), 1.85–1.95 (q, 4H, J ¼ 7.65 Hz, ACH A). Anal.
2
2
2
3
), 2.00–2.06 (m, 2H, NACACH
2
AC
Calcd. For C12H32N2O14S4: C, 25.89; H, 5.79; N, 5.03;
Found: C, 25.65; H, 5.80; N, 4.81. m/z: 556.88 (M ), 361.07
(M -2H SO ,100).
þ
3
2
3
þ
(
m, 6H, NACACACH ACH ), 0.84 (t, 9H, J ¼ 7.5 Hz,
2
3
2
4
1
). C NMR (75.5 MHz, D
3
NACACACACH
3
2
O): d 58.49,
0.66, 48.42, 23.93, 20.36, 19.16, 14.46. MS (m/z): 405.29
General procedure for the synthesis of 5-oxo-5,6,7,8-
tetrahydro-4H-benzo[b]pyrans. To a round-bottomed flask
charged with aromatic aldehyde (5 mmol) 1, malononitrile or
ethyl cyanoacetate (5 mmol) 2, 5,5-dimethyl-1,3-cyclohexane-
dione (dimedone) or 1,3-cyclohexanedione (5 mmol) 3 in
5 mL of water was added acidic ionic liquid (0.5 mmol) under
stirring. The mixture was then stirred for a certain time at
5
(
þ
M ), 406.28, 404.28 (100).
N-Propanesulfonic acid pyridinium hydrogen sulfate
1
(
6
[PyPSA]HSO ). H NMR (300 MHz, D O): d 8.62 (d, J ¼
4
2
.0 Hz, 2H, H-2, H-6), 8.30 (t, J ¼ 7.8 Hz, 1H, H-4), 7.84 (t,
J ¼ 6.9 Hz, 2H, H-3, H-5), 4.51 (t, J ¼ 7.5 Hz, 2H, NACH
ACACASO ), 2.73 (t,
ACH ASO ), 2.18–2.23 (m, 2H, NACACH ACASO ).
2
ꢁ
3
J
¼
7.2 Hz, 2H, NACACAC
90 C. On completion (monitored by TLC), the precipitated
13
C
crude product was collected by filtration and recrystallized
form ethanol (95%) to afford pure 5-oxo-5,6,7,8-tetrahydro-
4H-benzo[b]pyrans 4. The filtrated containing ionic liquid
2
3
2
3
NMR (75.5 MHz, D O): d 146.35, 144.70, 128.82, 60.28,
2
4
7.48, 26.47.
Table 3
a
4
.
Synthesis of 5-oxo-5,6,7,8-tetrahydro-4H-benzo[b]pyrans catalyzed by [TEBSA]ꢂHSO
ꢁ
b
Entry
Ar
R
1
R
2
Time (h)
Mp ( C) [Lit.]
Yields (%)
1
2
3
4
5
6
7
8
9
C
6
H
5
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CN
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
H
3
3
3
3
3
3
3
3
3
3
3
3
1.0
1.0
1.0
1.0
1.5
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.5
1.5
1.5
226-228 [13]
197-199 [13]
212-214 [13]
230-232 [13]
191-193 [2b]
214-215 [13]
230-232 [13]
209-211 [13]
205-207 [13]
208-210 [13]
179-180 [13]
189-191 [13]
190-192 [2b]
210-212 [2b]
225-227 [6b]
198-200 [2b]
220-222 [2b]
155-157 [13]
185-187 [13]
89
93
86
92
87
91
91
91
94
92
93
87
92
86
93
92
87
88
89
3 6 4
p-CH OC H
o-CH
m-HOC
p-FC H
o-ClC
m-ClC
p-ClC
p-BrC
m-NO C H
2 6 4
3
C
6
H
4
6
H
4
6 4
6 4
H
6 4
H
6 4
H
6 4
H
1
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
8
9
2 6 4
p-NO C H
2,4-Cl C H
2 6 3
3 6 4
p-CH OC H
o-ClC
p-ClC
m-NO
2,4-Cl
p-ClC
m-NO
6
H
H
4
H
6
4
H
H
2
C
6
H
4
2
C
6
H
3
H
6
H
4
CO
CO
2
Et
Et
CH
CH
3
2
C
6
H
4
2
3
a
Acidic ionic liquids are 5 mmol benzaldehyde, 5 mmol malononitrile (or ethyl cyanoacetate), 5 mmol dimedone (or 1,3-cyclohexanedione), 0.5
ꢁ
mmol catalyst, 90 C.
b
Isolated yields.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet