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CDCl3; d, ppm): 7.79 (d, J¼8.1 Hz, 2H), 7.16 (d, J¼8.1 Hz,
2H), 2.91 (t, J¼7.0 Hz, 2H), 2.49 (d, J¼7.0 Hz, 2H), 2.33 (s,
3H), 2.07 (s, 3H), 1.93 (quintet, J¼7.0 Hz, 2H). 13C NMR
(75 MHz, CDCl3; d, ppm): 208.6, 199.5, 143.9, 134.5,
129.4, 128.3, 42.8, 37.4, 30.0, 21.7, 18.4. IR (neat; cmꢁ1):
n 1710, 1674. HRMS (EI): calcd for C13H16O2 (M+),
204.1150; found, 204.1159.
(300 MHz, CDCl3; d, ppm): 7.88 (d, J¼9.0 Hz, 2H), 6.87
(d, J¼9.0 Hz, 2H), 3.79 (s, 3H), 2.88 (t, J¼7.0 Hz, 2H),
2.45 (t, J¼7.0 Hz, 2H), 2.31 (t, J¼7.0 Hz, 2H), 1.93 (quintet,
J¼7.2 Hz, 2H), 1.54 (td, J¼7.0 Hz, 2H), 0.84 (t, J¼7.0 Hz,
2H). 13C NMR (75 MHz, CDCl3; d, ppm): 208.8, 198.5,
163.6, 130.4, 130.1, 113.8, 55.5, 44.8, 41.8, 37.3, 18.6,
17.4, 13.8. IR (KBr; cmꢁ1): n 1710, 1666. HRMS (EI): calcd
for C15H20O3 (M+), 248.1412; found, 248.1417.
4.3.4. 3-Methyl-1-p-tolyl-pentane-1,4-dione (10b). Light
yellow oil (46 mg, 75% yield). 1H NMR (300 MHz, CDCl3;
d, ppm): 7.79 (d, J¼8.1 Hz, 2H), 7.16 (d, J¼8.1 Hz, 2H),
3.44 (dd, J¼18.0, 8.7 Hz, 1H), 3.19–3.12 (m, 1H), 2.87 (dd,
J¼18.0, 4.8 Hz, 1H), 2.33 (s, 3H), 2.23 (s, 3H), 1.13 (d,
J¼7.2 Hz, 3H). 13C NMR (75 MHz, CDCl3; d, ppm):
211.6, 198.2, 144.0, 134.2, 129.3, 128.2, 41.85, 41.81, 28.7,
21.6, 16.8. IR (neat; cmꢁ1): n 1718, 1682. HRMS (EI):
calcd for C13H16O2 (M+), 204.1150; found, 204.1145.
4.3.10. 1-(4-Methoxy-phenyl)-3-methyl-heptane-1,4-di-
one (10e). Light yellow oil (49 mg, 66% yield). H NMR
1
(300 MHz, CDCl3; d, ppm): 7.87 (dd, J¼6.9, 2.1 Hz, 2H),
6.85 (dd, J¼6.9, 2.1 Hz, 2H), 3.79 (s, 3H), 3.43 (dd,
J¼17.6, 9.0 Hz, 1H), 3.19–3.11 (m, 1H), 2.83 (dd, J¼17.6,
4.5 Hz, 1H), 2.51–2.50 (m, 2H), 1.60–1.53 (m, 2H), 1.10
(d, J¼7.2 Hz, 3H), 0.86 (t, J¼7.2 Hz, 3H). 13C NMR
(75 MHz, CDCl3; d, ppm): 213.9, 197.3, 163.6, 130.4,
129.9, 113.8, 55.5, 43.5, 41.6, 41.2, 17.1, 17.0, 13.9. IR
(neat; cmꢁ1): n 2933, 1711, 1675, 1601, 1260. HRMS
(EI): calcd for C15H20O3 (M+), 248.1412; found, 248.1413.
4.3.5. 1-(4-Methoxy-phenyl)-hexane-1,5-dione (9c).
1
White solid (12 mg, 18% yield). Mp: 80–81 ꢂC. H NMR
(300 MHz, CDCl3; d, ppm): 7.88 (d, J¼9.0 Hz, 2H), 6.87
(d, J¼9.0 Hz, 2H), 3.79 (s, 3H), 2.88 (t, J¼7.2 Hz, 2H),
2.49 (t, J¼7.2 Hz, 2H), 2.07 (s, 3H), 1.93 (quintet,
J¼7.2 Hz, 2H). 13C NMR (75 MHz, CDCl3; d, ppm):
208.6, 198.4, 163.6, 130.4, 130.1, 113.8, 55.6, 42.8, 37.2,
30.0, 18.6. IR (KBr; cmꢁ1): n 1710, 1668. HRMS (EI): calcd
for C13H16O3 (M+), 220.1099; found, 220.1097.
4.4. General procedure for preparation of 2,3,5-tri-
substituted furans
A 25 mL round-bottomed flask was equipped with a stirring
bar and charged with methanol (3 mL). p-TsOH$H2O
(171 mg, 0.9 mmol) and 1,2-disubstituted cyclopropanol
7a (57 mg, 0.3 mmol) were added under nitrogen. The reac-
tion mixture was stirred for 5 h under nitrogen at reflux.
Then the reaction mixture was concentrated under reduced
pressure on the rotary evaporator. To the residue was added
water (5 mL) and the solution extracted with diethyl ether
(3ꢀ10 mL). The combined organic layers were washed
twice with brine and then dried over anhydrous magnesium
sulfate, filtered, and concentrated under reduced pressure.
The residue was purified by silica gel chromatography
with petroleum ether/EtOAc (50:1–25:1), affording 11a in
(47 mg) 91% yield.
4.3.6. 1-(4-Methoxy-phenyl)-3-methyl-pentane-1,4-dione
(10c). Light yellow crystals (48 mg, 72% yield). Mp: 51–
53 ꢂC. 1H NMR (300 MHz, CDCl3; d, ppm): 7.87 (dd,
J¼6.9, 2.0 Hz, 2H), 6.85 (dd, J¼6.8, 2.0 Hz, 2H), 3.79 (s,
3H), 3.41 (dd, J¼18.0, 8.6 Hz, 1H), 3.21–3.17 (m, 1H),
2.28 (dd, J¼18.0, 4.8 Hz, 1H), 2.22 (s, 3H), 1.13 (d,
J¼7.2 Hz, 3H). 13C NMR (75 MHz, CDCl3; d, ppm):
211.8, 197.2, 163.7, 130.4, 129.9, 113.8, 55.5, 41.9, 41.6,
28.8, 16.8. IR (KBr; cmꢁ1): n 2924, 1711, 1672, 1599,
1260. HRMS (EI): calcd for C13H16O3 (M+), 220.1099;
found, 220.1097.
4.4.1. 2,3-Dimethyl-5-phenyl-furan (11a). Light yellow
1
4.3.7. 1-Thiophen-2-yl-hexane-1,5-dione (9d). White solid
oil. H NMR (300 MHz, CDCl3; d, ppm): 7.52 (dd, J¼8.4,
1
(12 mg, 20% yield). Mp: 30–32 ꢂC. H NMR (300 MHz,
1.2 Hz, 2H), 7.25 (t, J¼8.4 Hz, 1H), 7.11 (td, J¼8.4,
1.2 Hz, 2H), 6.35 (s, 1H), 2.19 (s, 3H), 1.89 (s, 3H). 13C
NMR (75 MHz, CDCl3; d, ppm): 151.0, 147.4, 131.4,
128.6, 126.6, 123.4, 116.2, 108.5, 11.6, 10.0. IR (neat;
cmꢁ1): n 1601, 1555, 1260. HRMS (EI): calcd for
C12H12O (M+), 172.0888; found, 172.0891.
CDCl3; d, ppm): 7.66 (dd, J¼3.9, 0.9 Hz, 1H), 7.56 (dd,
J¼4.8, 0.9 Hz, 1H), 7.05 (dd, J¼4.8, 3.9 Hz, 1H), 2.88 (t,
J¼7.2 Hz, 2H), 2.50 (t, J¼7.2 Hz, 2H), 2.07 (s, 3H), 1.94
(quintet, J¼7.2 Hz, 2H). 13C NMR (75 MHz, CDCl3; d,
ppm): 208.4, 192.8, 144.3, 133.6, 132.0, 128.2, 42.6, 38.2,
30.0, 18.7. IR (KBr; cmꢁ1): n 1715, 1600. HRMS (EI): calcd
for C10H12O2S (M+), 196.0588; found, 196.0564.
4.4.2. 2,3-Dimethyl-5-p-tolyl-furan (11b). White solid
1
(50 mg, 90% yield). Mp: 52–54 ꢂC. H NMR (300 MHz,
4.3.8. 3-Methyl-1-thiophen-2-yl-pentane-1,4-dione (10d).
Light yellow oil (46 mg, 78% yield). H NMR (300 MHz,
CDCl3; d, ppm): 7.40 (d, J¼8.1 Hz, 2H), 7.06 (d,
J¼8.1 Hz, 2H), 6.28 (s, 1H), 2.24 (s, 3H), 2.17 (s, 3H), 1.87
(s, 3H). 13C NMR (75 MHz, CDCl3; d, ppm): 151.2, 147.0,
136.4, 129.3, 128.7, 123.3, 116.1, 107.7, 21.3, 11.5, 10.0.
IR (KBr; cmꢁ1): n 2924, 1554, 1504, 1055, 808. HRMS
(EI): calcd for C13H14O (M+), 186.1045; found, 186.1053.
1
CDCl3; d, ppm): 7.67 (d, J¼3.9 Hz, 1H), 7.56 (d,
J¼5.1 Hz, 1H), 7.05 (dd, J¼4.8, 3.9 Hz, 1H), 3.40 (dd,
J¼17.4, 8.4 Hz, 1H), 3.18–3.13 (m, 1H), 2.83 (dd, J¼17.4,
4.8 Hz, 1H), 2.21 (s, 3H), 1.14 (d, J¼7.2 Hz, 3H). 13C
NMR (75 MHz, CDCl3; d, ppm): 211.3, 191.5, 143.9,
133.7, 132.1, 128.2, 42.2, 41.9, 31.6, 28.7, 16.8. IR (neat;
cmꢁ1): n 1710, 1659. HRMS (EI): calcd for C10H12O2S
(M+), 196.0558; found, 196.0554.
4.4.3. 5-(4-Methoxy-phenyl)-2,3-dimethyl-furan (11c).
1
White solid (56 mg, 92% yield). Mp: 54–56 ꢂC. H NMR
(300 MHz, CDCl3; d, ppm): 7.45 (dd, J¼6.9, 2.1 Hz, 2H),
6.80 (dd, J¼6.9, 2.1 Hz, 2H), 6.22 (s, 1H), 3.74 (s, 3H),
2.18 (s, 3H), 1.89 (s, 3H). 13C NMR (75 MHz, CDCl3; d,
ppm): 158.6, 151.1, 146.6, 124.7, 124.6, 116.0, 114.1,
4.3.9. 1-(4-Methoxy-phenyl)-octane-1,5-dione (9e). White
solid (18 mg, 24% yield). Mp: 66–67 ꢂC. 1H NMR