12
CHEN AND YEH
120.0, 106.7, 40.2, 34.3, 33.7, 23.1, 21.5, and 21.0; IR
(CH2Cl2) 1,602, 1,572, and 1,515 cm−1; MS (ESI) m/e
325.2 ([M + Na]+, 28), 288.1 (49), 265.1 (12), 247.1 (100),
233.1 (18), 190.0 (10), and 143.1 (11); HRMS (ESI) m/e
calcd for C22H22ONa [M + Na]+ 325.1568, found
325.1561.
to give 9f (25.8 mg, 0.081 mmol, 27%) as a yellow brown
oil: 1H NMR (400 MHz, CDCl3) δ 7.30–7.26 (m, 2H),
7.22–7.17 (m, 1H), 7.17–7.13 (m, 4H), 6.85–6.80 (m, 2H),
5.59 (s, 1H), 3.85–3.78 (m, 3H), 3.78 (s, 3H), 2.69–2.56 (m,
2H), 2.07 (dddd, J = 12.8, 7.5, 5.3, 2.3 Hz, 1H), 1.96–1.87
(m, 1H), 1.81–1.70 (m, 1H), and 1.64 (dddd, J = 12.9, 10.3,
7.7, 2.5 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ 158.2,
152.9, 150.4, 145.8, 130.6, 129.7, 128.2, 128.0, 126.1,
120.0, 113.9, 106.7, 55.3, 40.2, 33.9, 33.7, 23.1, and 21.5;
IR (CH2Cl2) 1,612, 1,512, and 1,455 cm−1; MS (EI, 70 eV)
m/e 318.1 ([M]+, 100), 290.1 (13), 287.1 (7), 197.1 (22),
169.1 (9), and 121.1 (17); HRMS (EI) m/e calcd for
C22H22O2 [M]+ 318.1620, found 318.1625.
4.3.4
| 2-([1,1’-Biphenyl]-4-ylmethyl)-4-phenyl-
4,5,6,7-tetrahydrobenzofuran (9d)
The crude mixture obtained from the cycloisomerization of
5d (109.3 mg, 0.300 mmol) was purified by flash column
chromatography over silica gel (hexanes) to give 9d
(72.2 mg, 0.198 mmol, 66%) as a pale yellow solid: mp
105–106ꢀC; 1H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 7.2
Hz, 2H), 7.52 (d, J = 8.2 Hz, 2H), 7.42 (dd, J = 8.5,
6.9 Hz, 2H), 7.35–7.26 (m, 5H), 7.22–7.15 (m, 3H), 5.68 (s,
1H), 3.94 (s, 2H), 3.83 (dd, J = 7.4, 5.7 Hz, 1H), 2.71–2.58
(m, 2H), 2.08 (dddd, J = 12.8, 7.4, 5.3, 2.3 Hz, 1H),
1.97–1.88 (m, 1H), 1.83–1.72 (m, 1H), and 1.65 (dddd,
J = 12.8, 10.2, 7.7, 2.5 Hz, 1H); 13C NMR (100 MHz,
CDCl3) δ 152.2, 150.6, 145.7, 141.0, 139.4, 137.6, 129.1,
128.7, 128.2, 128.0, 127.2, 127.1, 127.0, 126.1, 120.1,
107.0, 40.2, 34.4, 33.7, 23.1, and 21.5; IR (CH2Cl2) 1,602,
1,573, 1,488 cm−1; MS (EI, 70 eV) m/e 364.2 ([M]+, 100),
336.1 (13), 335.1 (6), 214.1 (5), 197.1 (18), 167.1 (29),
152.1 (11), and 141.1 (8); HRMS (EI) m/e calcd for
C27H24O [M]+ 364.1827, found 364.1820.
4.3.7
| Ethyl 3-([4-phenyl-4,5,6,7-tetrahydrobenzofuran-2-yl]
methyl)benzoate (9h)
The crude mixture obtained from the cycloisomerization of
5h (126.2 mg, 0.350 mmol) was purified by flash column
chromatography over silica gel (1:50 ethyl acetate/hexanes)
to give 9h (88.3 mg, 0.245 mmol, 70%) as a pale yellow
solid: mp 66–67ꢀC; 1H NMR (400 MHz, CDCl3) δ
7.94–7.87 (m, 2H), 7.42 (d, J = 7.6 Hz, 1H), 7.35 (t,
J = 7.6 Hz, 1H), 7.30–7.25(m, 2H), 7.23–7.18 (m, 1H),
7.17–7.14 (m, 2H), 5.63 (s, 1H), 4.36 (q, J = 7.1 Hz, 2H),
3.94 (s, 2H), 3.81 (dd, J = 7.4, 5.7 Hz, 1H), 2.69–2.55 (m,
2H), 2.07 (dddd, J = 13.1, 7.4, 5.3, 2.2 Hz, 1H), 1.97–1.87
(m, 1H), 1.82–1.70 (m, 1H), 1.64 (ddt, J = 12.8, 10.2,
5.1 Hz, 1H), and 1.38 (t, J = 7.1 Hz, 3H); 13C NMR
(100 MHz, CDCl3) δ 166.6, 151.7, 150.7, 145.6, 138.8,
133.2, 130.7, 129.9, 128.4, 128.2, 128.0, 127.7, 126.1,
120.1, 107.2, 60.9, 40.2, 34.5, 33.6, 23.1, 21.4, and 14.3; IR
(CH2Cl2) 1,718, 1,605, 1,589 cm−1; MS (ESI) m/e 383.2
([M + Na]+, 100), 359.2 (22), 262.1 (2), 261.6 (9), 143.1
(8), and 102.1 (6); HRMS (ESI) m/e calcd for C24H24O3Na
[M + Na]+ 383.1623, found 383.1619.
4.3.5
| 2-(Naphthalen-1-ylmethyl)-4-phenyl-
4,5,6,7-tetrahydrobenzofuran (9e)
The crude mixture obtained from the cycloisomerization of
5e (101.5 mg, 0.300 mmol) was purified by flash column
chromatography over silica gel (hexanes) to give 9e
(50.8 mg, 0.150 mmol, 50%) as a yellow oil: 1H NMR
(400 MHz, CDCl3) δ 8.09–8.03 (m, 1H), 7.86–7.81 (m,
1H), 7.74 (d, J = 8.0 Hz, 1H), 7.51–7.43 (m, 2H),
7.43–7.38 (m, 1H), 7.35 (d, J = 6.7 Hz, 1H), 7.26–7.21 (m,
2H), 7.16 (tt, J = 7.3, 2.2 Hz, 1H), 7.14–7.09 (m, 2H), 5.57
(s, 1H), 4.35 (d, J = 2.0 Hz, 2H), 3.78 (dd, J = 7.4, 5.7 Hz,
1H), 2.70–2.56 (m, 2H), 2.06 (dddd, J = 12.9, 7.6, 5.3,
2.3 Hz, 1H), 1.94–1.85 (m, 1H), 1.80–1.70 (m, 1H), and
1.67–1.57 (m, 1H); 13C NMR (100 MHz, CDCl3) δ 151.9,
150.4, 145.7, 134.4, 133.9, 132.0, 128.6, 128.2, 128.0,
127.3, 126.9, 126.0, 125.9, 125.6, 125.5, 124.1, 120.1,
107.3, 40.2, 33.8, 32.2, 23.1, and 21.4; IR (CH2Cl2) 1,599,
1,568, 1,493, 1,224, 778, 698 cm−1; MS (EI, 70 eV) m/e
338.1 ([M]+, 100), 310.1 (14), 309.1 (5), 197.1 (18), 141.1
(24), and 115.0 (8); HRMS (EI) m/e calcd for C25H22O
[M]+ 338.1671, found 338.1669.
4.3.8
| Ethyl 4-([4-phenyl-4,5,6,7-tetrahydrobenzofuran-2-yl]
methyl)benzoate (9i)
The crude mixture obtained from the cycloisomerization of
5i (126.2 mg, 0.350 mmol) was purified by flash column
chromatography over silica gel (1:50 ethyl acetate/hexanes)
to give 9i (98.4 mg, 0.273 mmol, 78%) as a pale yellow oil:
1H NMR (400 MHz, CDCl3) δ 7.99–7.94 (m, 2H),
7.32–7.26 (m, 4H), 7.22–7.18 (m, 1H), 7.17–7.13 (m, 2H),
5.64 (s, 1H), 4.36 (q, J = 7.1 Hz, 2H), 3.94 (s, 2H), 3.81
(dd, J = 7.4, 5.7 Hz, 1H), 2.69–2.55 (m, 2H), 2.07 (dddd,
J = 13.1, 7.4, 5.3, 2.2 Hz, 1H), 1.97–1.87 (m, 1H),
1.82–1.70 (m, 1H), 1.64 (dddd, J = 12.8, 10.2, 7.8, 2.5 Hz,
1H), and 1.38 (t, J = 7.2 Hz, 3H); 13C NMR (100 MHz,
CDCl3) δ 166.5, 151.3, 150.8, 145.6, 143.7, 129.8, 128.7
(2C), 128.2, 127.9, 126.1, 120.2, 107.3, 60.8, 40.2, 34.7,
33.6, 23.1, 21.4, and 14.3; IR (CH2Cl2) 1,716, 1,611, and
1,576 cm−1; MS (ESI) m/e 383.2 ([M + Na]+, 100), 361.2
(21), 359.2 (36), 302.6 (15), 294.1 (19), 282.1 (16), 255.1
4.3.6
| 2-(4-Methoxybenzyl)-4-phenyl-
4,5,6,7-tetrahydrobenzofuran (9f)
The crude mixture obtained from the cycloisomerization of
5f (95.5 mg, 0.300 mmol) was purified by flash column
chromatography over silica gel (1:50 ethyl acetate/hexanes)