May 2011
Synthesis of Tetracyclic System of 2,4-Di(tert-butyl)-6,7-
689
dihydrofuro[20,30:3,4]cyclohepta[1,2-b]indole
8.35 (d, J ¼ 9.0 Hz, 2H, HAr); 13C NMR (75 MHz, deuterio-
chloroform): d 22.2, 26.4 (3C), 29.1 (3C), 32.7, 36.9, 44.0,
103.8, 108.4, 112.8, 113.8, 120.5, 123.3, 123.6, 124.0 (2C),
127.5, 131.0 (2C), 135.9, 137.5, 140.7, 146.0, 150.3, 163.7,
167.4, 214.7; ms: m/z 500 (100) [Mþ], 485 (26), 352 (15), 336
(18), 276 (25), 266 (25), 250 (26), 236 (21), 150 (36), 120
(67), 104 (15), 92 (17), 84 (16), 57 (75), 43 (25). Anal. Calcd.
for C30H32N2O5: C, 71.98; H, 6.44; N, 5.60. Found: C, 71.83;
H, 6.58; N, 5.55.
1-[3-(5-tert-Butyl-2-furyl)-5,6-dimethoxy-1-(4-methyl-benzoyl)-
1H-indol-2-yl]-4,4-dimethylpentan-3-one (14e). This compound
was obtained from 12e according to the general procedure B
(2 mL of POCl3, reaction time 15 h) in 54% yield as white
solid. For spectral data of 14e, see [10].
1H, HFur), 7.19–7.24 (m, 1H, HAr), 7.31–7.37 (m, 1H, HAr),
7.47–7.51 (m, 1H, HAr), 7.97–8.01 (m, 1H, HAr), 7.98 (d, J ¼
9.0 Hz, 2H, HAr), 8.39 (d, J ¼ 9.0 Hz, 2H, HAr); 13C NMR
(75 MHz, deuteriochloroform): d 25.8, 29.1 (3C), 30.8 (3C),
32.7, 35.9, 104.1, 112.2, 113.7, 114.9, 120.3, 122.9, 124.0
(2C), 124.1, 124.3, 126.6, 130.7 (2C), 131.0, 136.8, 141.0,
144.6, 146.8, 150.2, 162.3, 166.8; ms: m/z 482 (66) [Mþ], 467
(26), 425 (100), 331 (46), 316 (31), 276 (32), 260 (37), 57
(21), 43 (24). Anal. Calcd. for C30H30N2O4: C, 74.67; H, 6.27;
N, 5.80. Found: C, 74.44; H, 6.38; N, 5.72.
2,4-Di(tert-butyl)-7-(4-methoxybenzoyl)-6,7-dihydrofuro-[20,30:
3,4]cyclohepta[1,2-b]indole (15d). This compound was obtained
from 12d according to the general procedure B using 5 mL of
POCl3 in 34% yield as beige solid (petroleum ether); M.p.
148–149ꢀC; IR (potassium bromide): 2964, 1676, 1608, 1512,
1452, 1364, 1308, 1260, 1212, 1172, 1028, 976, 852, 820,
7-Benzoyl-2,4-di(tert-butyl)-6,7-dihydrofuro[20,30:3,4]-cyclo-
hepta[1,2-b]indole (15a). This compound was obtained from
12a according to the general procedure B using 5 mL of
POCl3 in 49% yield as yellow needles (petroleum ether), M.p.
202–203ꢀC; IR (potassium bromide): 2964, 1680, 1448, 1376,
1
760, and 748 cmꢁ1; H NMR (300 MHz, deuteriochloroform):
d 1.20 (s, 9H, t-Bu), 1.43 (s, 9H, t-Bu), 2.90 (d, J ¼ 7.2 Hz,
2H, CH2), 3.91 (s, 3H, OCH3) 5.26 (t, J ¼ 7.2 Hz, 1H, ACH),
6.45 (s, 1H, HFur), 6.99 (d, J ¼ 8.7 Hz, 2H, HAr), 7.16–7.22
(m, 1H, HAr), 7.26–7.31 (m, 1H, HAr), 7.51–7.55 (m, 1H,
HAr), 7.80 (d, J ¼ 8.7 Hz, 2H, HAr), 7.96–7.99 (m, 1H, HAr);
13C NMR (75 MHz, deuteriochloroform): d 25.8, 29.2 (3C),
30.8 (3C), 32.7, 35.9, 55.6, 104.0, 112.1, 112.7, 114.0 (2C),
114.6, 119.9, 121.9, 123.1, 123.5, 126.2, 127.5, 132.5 (2C),
132.7, 137.2, 144.1, 147.5, 161.7, 163.7, 168.3; ms: m/z 467
(83) [Mþ], 410 (100), 276 (14), 261 (23), 136 (41), 135 (64),
107 (80), 92 (38), 76 (32), 57 (76), 43 (39). Anal. Calcd. for
C31H33NO3: C, 79.63; H, 7.11; N, 3.00. Found: C, 79.77; H,
6.97; N, 3.01.
Synthesis of 5,5-dimethyl-1-[2-(4,4-dimethylpentan-3-on-
1-yl)-1H-indol-3-yl]hexane-1,4-dione (16). A total of 35% hy-
drochloric acid (7 mL) was added to the cooled solution (10–
12ꢀC) of compound 12a (1.0 g, 2.2 mmol) in AcOH (25 mL).
The reaction mixture was kept at 45ꢀC for 9 h. After comple-
tion of the reaction (TLC monitoring), the mixture was poured
into water, neutralized with NaHCO3, and extracted with
CH2Cl2 (3 ꢂ 50 mL). The extract was dried with anhydrous
Na2SO4 and evaporated to dryness. Compound 16 was isolated
by column chromatography (eluent: petroleum ether–acetone–
CH2Cl2, 15:5:3) in 38% yield as a white solid. For spectral
data of 16, see [10].
1-[3-(5-tert-Butyl-2-furyl)-1-(4-toluenesulfonyl)-1H-indol-2-
yl]-4,4-dimethylpentan-3-one (17a). This compound was syn-
thesized from 13a according to general procedure B using 5
mL of POCl3 in 47% yield. For spectral data of 17a, see [10].
1-[3-(5-tert-Butyl-2-furyl)-5,6-dimethoxy-1-(4-toluene-sulfonyl)-
1H-indol-2-yl]-4,4-dimethylpentan-3-one (17b). This compound
was synthesized from 13b according to general procedure B
using 5 mL of POCl3 in 53% yield. For spectral data of 17b,
see [10].
Synthesis of bis(5-tert-butyl-2-furyl)(2-hydroxy-5-nitrophe-
nyl)methane (19). 2-(tert-Butyl)furan (3.76 mL, 26.4 mmol)
and 1 N solution of PPA ethyl ester (20 mL) were added to
the solution of aldehyde 18a (2 g, 12 mmol) in methylene
chloride (100 mL). The reaction mixture was stirred at 40–
45ꢀC for 3 h and poured into water (150 mL). Organic layer
was separated; aqueous fraction was extracted with methylene
chloride (2 ꢂ 30 mL). The combined organic fractions were
dried with Na2SO4 and filtered. The solvent was evaporated
under reduced pressure. Residue was dissolved in methylene
1360, 1328, 1312, 1208, 1152, 744, 720, and 700 cmꢁ1 1H
;
NMR (300 MHz, deuteriochloroform): d 1.20 (s, 9H, t-Bu),
1.43 (s, 9H, t-Bu), 2.83 (d, J ¼ 7.2 Hz, 2H, CH2), 5.18 (t, J ¼
7.2 Hz, 1H, ACH), 6.45 (s, 1H, HFur), 7.18–7.23 (m, 1H, HAr),
7.28–7.33 (m, 1H, HAr), 7.50–7.61 (m, 3H, HAr), 7.63–7.69
(m, 1H, HAr), 7.79–7.83 (m, 2H, HAr), 7.97–8.00 (m, 1H,
HAr); 13C NMR (75 MHz, deuteriochloroform): d 25.8, 29.1
(3C), 30.8 (3C), 32.7, 35.9, 104.1, 112.7, 112.8, 114.9, 119.9,
122.2, 123.4, 123.7, 126.4, 128.7 (2C), 129.9 (2C), 132.2,
133.0, 135.5, 137.2, 144.2, 147.3, 161.9, 169.0; ms: m/z 437
(37) [Mþ], 422 (44), 381 (82), 380 (100), 302 (15), 276 (32),
260 (15), 135 (66), 105 (65), 76 (32), 59 (18), 45 (12), 43
(58). Anal. Calcd. for C30H31NO2: C, 82.35; H, 7.14; N, 3.20.
Found: C, 82.41; H, 6.97; N, 3.18.
7-(4-Bromobenzoyl)-2,4-di(tert-butyl)-6,7-dihydrofuro-[20,
30:3,4]cyclohepta[1,2-b]indole (15b). This compound was
obtained from 12b according to the general procedure B using
10 mL of POCl3 in 41% yield as yellow needles (CH2Cl2–pe-
troleum ether); M.p. 206–207ꢀC; IR (potassium bromide):
2952, 1680, 1592, 1544, 1448, 1324, 1268, 1204, 1016, 976,
1
832, and 756 cmꢁ1; H NMR (300 MHz, deuteriochloroform):
d 1.20 (s, 9H, t-Bu), 1.43 (s, 9H, t-Bu), 2.87 (d, J ¼ 7.2 Hz,
2H, CH2), 5.22 (t, J ¼ 7.2 Hz, 1H, ACH), 6.45 (s, 1H, HFur),
7.18–7.24 (m, 1H, HAr), 7.29–7.34 (m, 1H, HAr), 7.51–7.53
(m, 1H, HAr), 7.65–7.72 (m, 4H, HAr), 7.97–7.99 (m, 1H,
HAr); 13C NMR (75 MHz, deuteriochloroform): d 25.7, 29.1
(3C), 30.8 (3C), 32.7, 35.9, 104.0, 112.5, 112.9, 114.8, 120.0,
122.4, 123.6, 123.9, 126.3, 128.1, 131.4 (2C), 131.8, 132.1
(2C), 134.2, 137.0, 144.3, 147.1, 161.9, 167.9; ms: m/z 518/
516 (100/100) [Mþ], 460/458 (91/89), 331 (24), 316 (23), 276
(44), 260 (53), 185/183 (50/52), 76 (62), 57 (70), 43 (46).
Anal. Calcd. for C30H30BrNO2: C, 69.77; H, 5.85; N, 2.71.
Found: C, 69.79; H, 5.92; N, 2.57.
2,4-Di(tert-butyl)-7-(4-nitrobenzoyl)-6,7-dihydrofuro-[20,30:3,
4]cyclohepta[1,2-b]indole (15c). This compound was obtained
from 12c according to the general procedure B using 10 mL
of POCl3 in 21% yield as orange solid (CH2Cl2–petroleum
ether); M.p. 191–192ꢀC; IR (potassium bromide): 2964, 1680,
1524, 1452, 1348, 1324, 1208, 1156, 1092, 980, 860, 836,
1
752, 728, and 708 cmꢁ1; H NMR (300 MHz, deuteriochloro-
form): d 1.20 (s, 9H, t-Bu), 1.43 (s, 9H, t-Bu), 2.83 (d, J ¼
7.2 Hz, 2H, CH2), 5.17 (t, J ¼ 7.2 Hz, 1H, ACH), 6.46 (s,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet