36
G. A. MESHRAM AND V. D. PATIL
advantages include the low cost, ease of catalyst handling, requirement of very small
amount of catalyst such as 0.1 mmol (30 mg), mild reaction conditions and excellent
yields. The remarkable selectivity under mild and neutral conditions and the commer-
cially available, inexpensive catalyst are attractive features of this method.
General Experimental Procedure for Bis(Indolyl) Methanes
A mixture of benzaldehyde (2 mmol), indole (4 mmol), and [Cu(BF4)2 ꢀSiO2]
(0.1 mmol, 30 mg) was stirred magnetically at 80ꢁC with DCM, and the progress
of the reaction was monitored by thin-layer chromatography (TLC). After com-
pletion of the reaction (TLC), the catalyst was separated by filtration. The filtrate
was dried over anhydrous Na2SO4 and then evaporated under a vacuum to afford
the crude product, which was further purified by column chromatography. In all
the cases, the product obtained after the usual work up gave satisfactory spectral
data.
Spectral Data for Selected Compounds
3,30-Bis(indolyl) phenyl methane (1b). Palered solid, yield 96%, mp
1
123–125.; IR (KBr): 735, 1094, 1342, 1458, 1483, 2927, 2956, 3045, 3387 cmꢂ1; H
NMR (300 MHz, CDCl3): d ¼ 7.78 (br s, 2H), 7.36 (d, J ¼ 8.1 Hz, 2H), 7.10–7.36
(m, 9H), 6.95 (t, J ¼ 7.5 Hz, 2H), 6.46 (d, J ¼ 1.8 Hz, 2H), 5.82 (s, 1H): 13C NMR
(CDCl3): 143.0, 136.2, 128.5, 128.6, 127.3, 126.5, 123.4, 121.3, 119.4, 119.0, 118.9,
111.3, 40.6.
3,30-Bis(indolyl)-4-methoxyl phenyl methane (3b). Brown needles, yield
95%, mp 193–195, IR (KBr): 740, 780, 1015, 1090, 1132,1341, 1450, 1607, 2922,
1
3052, 3386, 3422 cmꢂ1: H NMR (300 MHz, CDCl3): d ¼ 7.90 (br s, 2H), 6.9–7.9
(m, 12H), 6.4 (s, 2H), 6.1 (s, 1H), 3.95(s, 3H): 13C NMR (CDCl3): 39.4, 55.6,
102.3, 111.3, 119.7, 122, 123.8, 128.2, 129.9, 135.8,136.8, 157.8: EIMS m=z 352.
3,30- Bis(indolyl)-4-dimethylamino phenyl methane (7b). Pink solid,
yield 93%, mp 168–170; IR (KBr): 740, 760, 1015, 1095, 1222, 1350, 1456, 1512,
1
2920, 3062, 3342, 3418, 3520 cmꢂ1; H NMR (300 MHz, DMSO) d: 11.30 (br s,
2H), 8.30 (d, J ¼ 2.0 Hz, 2H), 8.02 (dd, J ¼ 8.8, 2.0 Hz, 2H), 7.50 (dd, J ¼ 9.2,
1.6 Hz, 2H), 7.43 (d, J ¼ 7.6 Hz, 2H), 7.36 (t, J ¼ 7.6 Hz, 2H), 7.25 (d, J ¼ 7.2 Hz,
1H), 7.20 (s, 2H), 6.23(s, 1H); 13C NMR (DMSO): 148.6, 145.2, 144.2, 133.1,
133.5, 132.6, 131.7, 130.2, 125.8, 121.4, 121.5, 117.3, 43.7, MS (ESI) m=z: 411.34.
3,30-Bis(indolyl)-4-methyl phenyl methane (8b). Pale red solid, yield 95%,
mp 95–98; IR (KBr): 742, 788, 999, 1090, 1225, 1340, 1457, 1508, 2925, 3056, 3386,
3420 cmꢂ1; 1H NMR (300 MHz, CDCl3) d: 7.84 (br s, 2H), 7.42 (d, J ¼ 8.0 Hz, 2H),
7.30 (d, J ¼ 8.3 Hz, 2H), 7.26 (d, J ¼ 8.0 Hz, 2H), 7.15 (dd, J ¼ 7.6 Hz, 2H), 7.03 (d,
J ¼ 8.0 Hz, 2H), 7.00 (t, J ¼ 7.2 Hz, 2H), 6.64 (s, 2H), 5.83 (s, 1H), 2.33 (s, 3H); 13C
NMR (CDCl3) d: 141.2, 136.5, 136.5, 129.2, 128.5, 127.3, 123.4, 122.1, 120.2, 119.5,
119.2, 111.2, 40.2, 21.3.
3,30-Bis(indolyl)-4-chloro phenyl methane (11b). Pale solid, yield 94%, mp
74–76: IR (KBr): 743, 787, 1010, 1100, 1130, 1325, 1456, 1603, 2920, 3050, 3382,