12880
Z. Liang et al. / Tetrahedron 63 (2007) 12877–12882
solid after being stirred at 40 ꢀC for 12 h under Ar, mp: 108–
109 ꢀC (petroleum ether). 1H NMR (300 MHz, CDCl3)
d 7.49 (s, 1H), 6.84 (s, 1H), 2.28 (s, 6H), 1.27 (s, 18H);
13C NMR (75 MHz, CDCl3) d 167.9, 150.7, 136.3, 116.4,
116.0, 103.7, 72.8, 30.7, 28.0, 20.6; MS (EI) m/z (%): 354
(4.0), 270 (100); IR (neat) n (cmꢁ1): 2969, 2231, 1775,
1495, 1367, 1190, 1106; Anal. Calcd for C22H26O4: C,
74.55, H, 7.39; Found: C, 74.54, H, 7.36.
73%) as a white solid after being stirred at 0 ꢀC for
30 min, mp: 74–75 ꢀC (petroleum ether/ethyl ether). 1H
NMR (300 MHz, CDCl3) d 7.26 (s, 1H), 6.52 (s, 1H), 5.83
(br s, 2H), 1.32 (s, 18H); 13C NMR (75 MHz, CDCl3)
d 157.4, 133.9, 105.0, 102.9, 100.4, 72.0, 31.1, 28.3; MS
(EI) m/z (%): 270 (100.0); IR (neat) n (cmꢁ1): 3499, 2969,
2928, 1631, 1496, 1272; Anal. Calcd for C18H22O2: C,
79.96, H, 8.20; Found: C, 80.02, H, 8.15.
4.1.4. 2,4-Di(oct-10-ynyl)-1,5-diacetoxybenzene (3g). The
reaction of 2 (500 mg, 1.13 mmol), Et3N (2 mL), 1-octyne
(495 mg, 4.5 mmol), PdCl2(PPh3)2 (32 mg, 0.046 mmol),
and CuI (17 mg, 0.09 mmol) in DMF (2 mL) afforded the
coupling product 3g (412 mg, 90%) as an oil after being
4.1.8. 2,4-Di(oct-10-ynyl)-1,5-dihydroxybenzene (4g). The
reaction of 3g (300 mg, 0.73 mmol) and LiOH$H2O
(132 mg, 3.14 mmol) in a mixed solvent (MeOH/THF/
H2O¼1:1:1, 20 mL) afforded the product 4g (186 mg,
1
78%) as an oil after being stirred at 0 ꢀC for 30 min. H
1
stirred at 40 ꢀC for 3.5 h under Ar. H NMR (300 MHz,
NMR (300 MHz, CDCl3) d 7.24 (s, 1H), 6.52 (s, 1H), 5.92
(br s, 2H), 2.42 (t, J¼6.9 Hz, 4H), 1.64–1.52 (m, 4H),
1.50–1.22 (m, 12H), 0.90 (t, J¼6.9 Hz, 6H); 13C NMR
(75 MHz, CDCl3) d 157.6, 133.9, 103.0, 100.6, 96.7, 73.6,
31.3, 28.7, 28.6, 22.5, 19.5, 14.0; MS (EI) m/z (%): 326
(M+, 100); IR (neat) n (cmꢁ1): 3497, 2930, 2858, 1629,
1586, 1492, 1354, 1272, 1146; HRMS Calcd for
C22H30O2: 326.2246; Found: 326.2253.
CDCl3) d 7.48 (s, 1H), 6.86 (s, 1H), 2.38 (t, J¼6.9 Hz,
4H), 2.29 (s, 6H), 1.61–1.48 (m, 4H), 1.46–1.21 (m, 12H),
0.89 (t, J¼6.9 Hz, 6H); 13C NMR (75 MHz, CDCl3)
d 168.2, 150.7, 136.6, 116.6, 116.0, 95.8, 74.2, 31.3, 28.5,
28.4, 22.5, 20.7, 19.4, 14.0; MS (EI) m/z (%): 410 (M+,
12.6), 326 (100); IR (neat) n (cmꢁ1): 2932, 2859, 2233,
1776, 1493, 1190, 1128; HRMS Calcd for C26H34O4Na+
(M+Na+): 433.2349; Found: 433.2357.
4.2. Double cycloisomerization of 4
4.1.5. 2,5-Di (oct-10-ynyl)-1,4-dihydroxybenzene (4b).
Typical Procedure B. To the solution of 3b (340 mg,
0.82 mmol) in a mixed solvent (MeOH/THF/H2O¼1:1:1,
20 mL) was added NaOH (140 mg, 3.5 mmol) at 0 ꢀC. The
resulting solution was stirred at this temperature for
30 min as monitored by TLC. The mixture was neutralized
with aq HCl, extracted with ethyl ether, washed with brine,
and dried over MgSO4. Evaporation and flash column chro-
matography on silica gel (petroleum ether/ethyl acetate¼
10:1) gave 4b (184 mg, 68%) as a white solid, mp: 87–
4.2.1. 2,6-Dibutylbenzo[1,2-b:4,5-b0]difuran (5a). Typical
Procedure C: Condition A. To a reaction tube were added
sequentially 4a (50 mg, 0.19 mmol), Cs2CO3 (120 mg,
0.37 mmol), and DMA (2 mL). The reaction mixture was
stirred for 2.5 h at 80 ꢀC, quenched with water, extracted
with ether, and washed with brine. Evaporation and flash col-
umn chromatography on silica gel (petroleum ether) gave 5a
(38 mg, 76%) as a white solid, mp: 55–56 ꢀC (petroleum
ether). 1H NMR (300 MHz, CDCl3) d 7.43 (s, 2H), 6.40 (s,
2H), 2.77 (t, J¼7.8 Hz, 4H), 1.80–1.70 (m, 4H), 1.50–1.40
(m, 4H), 0.97 (t, J¼7.2 Hz, 6H); 13C NMR (75 MHz,
CDCl3) d 159.8, 151.6, 125.8, 101.9, 100.6, 29.7, 28.3,
22.3, 13.8; MS (EI) m/z (%): 270 (50.3), 227 (100.0); IR
(neat) n (cmꢁ1): 2960, 2932, 1606, 1437; Anal. Calcd for
C18H22O2: C, 79.96, H, 8.20; Found: C, 80.11, H, 8.18.
1
88 ꢀC (petroleum ether/ethyl ether). H NMR (300 MHz,
CDCl3) d 6.84 (s, 2H), 5.42 (s, 2H), 2.46 (t, J¼6.9 Hz,
4H), 1.64–1.55 (m, 4H), 1.47–1.26 (m, 12H), 0.90 (t,
J¼6.6 Hz, 6H); 13C NMR (75 MHz, CDCl3) d 149.8,
116.2, 111.2, 99.1, 74.5, 31.3, 28.59, 28.55, 22.5, 19.6,
14.0; MS (EI) m/z (%): 326 (M+, 100); IR (neat) n (cmꢁ1):
3309, 2928, 2859, 2225, 1422, 1193; Anal. Calcd for
C22H30O2: C, 80.94, H, 9.26; Found: C, 81.14, H, 9.27.
The following compounds were prepared according to
Condition A.
The following compounds were prepared according to
Procedure B.
4.2.2. 2,6-Dioctylbenzo[1,2-b:4,5-b0]difuran (5b). The re-
action of 4b (62 mg, 0.19 mmol) and Cs2CO3 (126 mg,
0.39 mmol) in DMA (2 mL) afforded the product 5b
(19 mg, 31%) as a white solid after being stirred at 80 ꢀC
for 5.5 h, mp: 62–63 ꢀC (petroleum ether). 1H NMR
(300 MHz, CDCl3) d 7.42 (s, 2H), 6.40 (s, 2H), 2.76 (t,
J¼7.8 Hz, 4H), 1.80–1.70 (m, 4H), 1.50–1.25 (m, 12H),
0.89 (t, J¼6.9 Hz, 6H); 13C NMR (75 MHz, CDCl3)
d 159.9, 151.6, 125.8, 101.9, 100.6, 31.6, 28.9, 28.7, 27.6,
22.6, 14.1; MS (EI) m/z (%): 326 (M+, 52.4), 255 (100);
IR (neat) n (cmꢁ1): 2930, 2848, 1603, 1470, 1437; Anal.
Calcd for C22H30O2: C, 80.94, H, 9.26; Found: C, 80.90,
H, 9.41.
4.1.6. 2,4-Bis(phenylethynyl)-1,5-dihydroxybenzene (4e).
The reaction of 3e (278 mg, 0.71 mmol) and LiOH (68 mg,
2.83 mmol) in a mixed solvent (MeOH/THF/H2O¼1:1:1,
10 mL) afforded the product 4e (198 mg, 91%) as a brown
solid after being stirred at 0 ꢀC for 35 min, mp: 114–
1
115 ꢀC (petroleum ether/ethyl ether). H NMR (300 MHz,
CDCl3) d 7.55–7.51 (m, 5H), 7.43–7.36 (m, 6H), 6.65 (s,
1H), 6.07 (s, 2H); 13C NMR (75 MHz, CDCl3) d 158.4,
134.6, 131.5, 128.7, 128.5, 122.3, 102.9, 101.4, 95.5, 82.0;
MS (EI) m/z (%): 310 (100.0); IR (neat) n (cmꢁ1): 3497,
1626, 1595, 1501, 1271; Anal. Calcd for C22H14O2: C,
85.14, H, 4.55; Found: C, 85.15, H, 4.65.
4.2.3. 2,6-Dibutylbenzo[1,2-b:5,4-b0]difuran (5c). The re-
action of 4c (50 mg, 0.19 mmol) and Cs2CO3 (120 mg,
0.37 mmol) in DMA (2 mL) afforded the product 5c
(8 mg, 16%) as a white solid after being stirred at 80 ꢀC
for 11 h, mp: 38 ꢀC (petroleum ether). 1H NMR
4.1.7. 2,4-Di(tert-butylethynyl)-1,5-dihydroxybenzene
(4f). The reaction of 3f (220 mg, 0.62 mmol) and LiOH
(59 mg, 2.46 mmol) in a mixed solvent (MeOH/THF/
H2O¼1:1:1, 10 mL) afforded the product 4f (122 mg,