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N. Kurono et al. / Tetrahedron 60 (2004) 1791–1801
4.5.17. 1,2,3,4,4a,9b-Hexahydrodibenzofuran (5e). Con-
figurations of 5e was determined by DIFNOE spectrum. IR
(100), 131 (10), 130 (11), 117 (37), 40, (21); HRMS calcd
for C11H15N m/z 161.1204. Found m/z 161.1221.
1
(neat) 1596, 1474, 1226 cm21; H NMR (CDCl3) d 7.16–
7.08 (2H, m), 6.87 (1H, dd, J¼1.0, 7.6 Hz), 6.80 (1H, d,
J¼7.6 Hz), 4.67 (1H, dt, J¼5.0, 7.3 Hz), 3.19 (1H, q,
J¼7.3 Hz), 2.04–1.75 (3H, m), 1.62–1.44 (4H, m), 1.42–
1.26 (1H, m); EIMS m/z (relative intensity) 174 (100), 159
(33), 145 (56), 131 (84), 120 (36), 91 (21); HRMS calcd for
C12H14O m/z 174.1045. Found m/z 174.1048. Anal. calcd
for C12H14O: C, 82.72; H, 8.10. Found: C, 82.50; H, 8.01.
4.5.23. 2,3-Dihydro-1,3,3-trimethylindole (8c).25 IR (neat)
3022, 1608, 1491, 1462 cm21; 1H NMR (CDCl3) 7.09 (1H,
dt, J¼1.3, 7.6 Hz), 7.01 (1H, dd, J¼1.3, 7.6 Hz), 6.70 (1H,
dt, J¼1.3, 7.6 Hz), 6.49 (1H, dd, J¼1.3, 7.6 Hz), 3.06 (2H,
s), 2.75 (3H, s), 1.30 (6H, s); 13C NMR (CDCl3) d 151.97,
139.21, 127.42, 121.49, 117.82, 107.29, 70.30, 40.23, 35.97,
27.37 (two signals).
4.5.18. 2,3-Dihydro-3-(1-formyl-1-methylethyl)benzo-
4.5.24. 3-Isopropyl-2,3-dihydro-1-methylindole (8d). IR
(neat) 3046, 1609, 1491, 1458 cm21; H NMR (CDCl3) d
1
furan (6a). IR (neat) 1723, 1594, 1484, 1460, 1232 cm21
;
1H NMR (CDCl3) d 9.56 (1H, s), 7.15 (2H, m), 6.86 (1H, dd,
J¼1.0, 7.6 Hz), 6.80 (1H, m), 4.56 (1H, dd, J¼4.0, 9.2 Hz),
4.38 (1H, dd, J¼4.0, 9.2 Hz), 3.66 (1H, dd, J¼4.0, 9.2 Hz),
1.12 (3H, s), 1.03 (3H, s); EIMS m/z (relative intensity) 190
(17), 119 (100), 91 (78); HRMS calcd for C12H14O2 m/z
190.0994. Found m/z 190.0986. Anal. calcd for C12H14O2:
C, 75.76; H, 7.42. Found: C, 75.54; H, 7.42.
7.09 (2H, m), 6.66 (1H, dt, J¼0.7, 7.3 Hz), 6.46 (1H, dd,
J¼0.7, 7.3 Hz), 3.30 (1H, t, J¼8.2 Hz), 3.12 (2H, m), 2.73
(3H, s), 2.02 (1H, m), 0.99 (3H, d, J¼6.9 Hz), 0.88 (3H, d,
J¼6.9 Hz); 13C NMR (CDCl3) d 153.91, 132.85, 127.71,
124.60, 117.50, 107.21, 58.55, 47.35, 36.35, 30.73, 20.83,
19.10; EIMS m/z (relative intensity) 175 (23), 158 (19), 133
(11), 132 (100), 117 (30); HRMS calcd for C12H17N m/z
175.1361. Found m/z 1751355.
4.5.19. 2,3-Dihydro-3-formylmethyl-3-methylbenzo-
furan (6b).24 IR (neat) 1722, 1598, 1481, 1460,
4.5.25. 3-Benzyl-2,3-dihydro-1-methylindole (8e). IR
(neat) 3026, 1607, 1492, 1460 cm21; H NMR (CDCl3) d
1
1243 cm21
;
1H NMR (CDCl3) d 9.70 (1H, dd, 1.7,
2.3 Hz), 7.16 (2H, m), 6.91 (1H, dt, J¼1.0, 8.3 Hz), 6.81
(1H, d, J¼8.3 Hz), 4.44 (1H, d, J¼9.2 Hz), 4.35 (1H, d,
J¼9.2 Hz), 4.34 (1H, d, J¼9.2 Hz), 2.85 (1H, dd, J¼2.3,
16.8 Hz), 2.72 (1H, dd, J¼1.7, 16.8 Hz), 1.46 (3H, s); 13C
NMR (CDCl3) d 200.8, 159.0, 133.8, 128.7, 122.8, 120.9,
120.7, 110.1, 82.2, 53.5, 25.3; EIMS m/z (relative intensity)
176 (66), 133 (100), 105 (53), 77 (26); HRMS calcd for
C11H12O2 m/z 176.0837. Found m/z 176.0835.
7.34–7.21 (5H, m), 7.11 (1H, dt, J¼0.7, 7.6 Hz), 6.93 (1H,
dd, J¼0.7, 7.3 Hz), 6.66 (1H, dt, J¼0.7, 7.3 Hz), 6.51 (1H,
dd, J¼0.7, 7.3 Hz), 3.49 (1H, m), 3.28 (1H, t, J¼8.6 Hz),
3.11 (1H, dd, J¼6.0, 13.5 Hz), 3.02 (1H, dd, J¼6.6, 8.6 Hz),
2.78 (1H, dd, J¼9.6, 13.5 Hz), 2.73 (3H, s); 13C NMR
(CDCl3)
d
153.14, 140.20, 133.30, 128.97 (two
signals), 128.39 (two signals), 127.78, 126.15, 123.65,
117.68, 107.37, 61.69, 42.37, 60.06, 36.08; EIMS m/z
(relative intensity) 223 (12), 132 (100), 117 (25), 91 (10);
HRMS calcd for C16H17N m/z 223.1361. Found m/z
223.1361.
4.5.20. 3-(1-Formylethyl)-2,3-dihydrobenzofuran (6c).
1
IR (neat) 1723, 1596, 1483, 1461, 1230, 1017 cm21; H
NMR (CDCl3) d 9.76 (0.4H, s), 9.72 (0.6H, s), 7.15 (2H, m),
6.93–6.79 (2H, m), 4.62 (1H, m), 4.30 (1H, m), 3.94 (0.4H,
m), 3.83 (0.6H, m), 2.84 (0.4H, m), 2.70 (0.6H, quint,
J¼7.3 Hz), 1.14 (1.8H, d, J¼7.3 Hz), 1.06 (1.2H, d,
J¼7.6 Hz); 13C NMR (CDCl3) d 203.4, 160.4, 128.8,
126.9, 125.4, 120.5, 109.7, 75.0, 50.4, 41.9, 10.4; EIMS m/z
(relative intensity) 176 (35), 119 (100), 91 (98); HRMS
calcd for C11H12O2 m/z 176.0837. Found m/z 176.0843.
4.5.26. 3-Methy-1,2,3,4-tetrahydro-1-naphthol (9a).26 IR
1
(neat) 3332, 1455, 1056 cm21; H NMR (CDCl3) d 7.35–
7.18 (4H, m), 2.80 (1H, m), 2.41 (1H, m), 2.19 (1H, m), 1.88
(2H, m), 1.08 (1H, d, J¼6.3 Hz).
4.5.27. 3-Methychroman (9b).27 IR (neat) 2922, 1734,
1
1456, 1261 cm21; H NMR (CDCl3) d 6.7–7.2 (4H, m),
4.17 (1H, ddd, J¼2.0, 5.6, 10.6 Hz), 3.68 (1H, t, J¼9.6 Hz),
2.83 (1H, ddd, J¼2.0, 5.6, 16.2 Hz), 2.44 (1H, dd, J¼9.6,
16.2 Hz), 2.15 (1H, m), 1.04 (3H, d, J¼6.6 Hz).
4.5.21. 2,3-Dihydro-1,3-dimethylindole (8a). IR (neat)
1
3048, 1610, 1492, 1462 cm21; H NMR (CDCl3) d 7.08
(2H, m), 6.70 (1H, dt, J¼0.7, 7.6 Hz), 6.49 (1H, dd, J¼0.7,
7.6 Hz), 3.52 (1H, t, J¼8.3 Hz), 3.27 (1H, m), 2.79 (1H, t,
J¼8.3 Hz), 2.74 (3H, s), 1.31 (3H, d, J¼6.9 Hz); 13C NMR
(CDCl3) d 152.88, 135.31, 127.42, 122.91, 117.93, 107.35,
64.13, 36.23, 35.31, 18.22; EIMS m/z (relative intensity)
147 (62), 146 (16), 143 (15), 132 (100), 131 (16), 117 (34);
HRMS calcd for C10H13N m/z 147.1048. Found m/z
147.1041.
4.5.28. 1,3-Dimethy-1,2,3,4-tetrahydroquinoline (9c).28
IR (neat) 3024, 1605, 1492, 1459 cm21
;
1H NMR
(CDCl3) d 7.07 (1H, t, J¼9.8 Hz), 6.95 (1H, d, J¼6.8 Hz),
6.59 (2H, m), 3.15 (1H, ddd, J¼2.0, 4.2, 11.0 Hz), 2.88 (3H,
s), 2.72–2.79 (2H, m), 2.41 (1H, dd, J¼10.7, 15.8 Hz), 2.12
(1H, m), 1.03 (3H, d J¼6.5 Hz).
4.6. Typical procedure for radical cyclization using
Bu3SnH and AIBN
4.5.22. 3-Ethyl-2,3-dihydro-1-methylindole (8b). IR
1
(neat) 3046, 1609, 1492, 1461 cm21; H NMR (CDCl3) d
7.07 (2H, m), 6.58 (1H, dt, J¼0.7, 7.6 Hz), 6.48 (1H, dd,
J¼0.7, 7.6 Hz), 3.38 (1H, t, J¼8.3 Hz), 3.11 (1H, m), 2.92
(1H, t, J¼8.3 Hz), 2.74 (3H, s), 1.88 (1H, m), 1.55 (1H, m)
1.00 (3H, t, J¼7.6 Hz); 13C NMR (CDCl3)d 153.19, 134.05,
127.48, 123.43, 117.61, 107.21, 61.89, 42.37, 36.17, 26.65,
11.93; EIMS m/z (relative intensity) 161 (32), 133 (11), 132
To a solution of substrate (0.5 mmol) and toluene (25 ml)
was added n-Bu3SnH (0.55 mmol) and AIBN (0.1 mmol) at
room temperature. The solution was heated under reflux for
4 h. The solvent was evaporated and diluted with hexane.
The solution was extracted with CH3CN. The combined
CH3CN extracts were washed with hexane, dried over