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. 2020 Mar 16;10(18):10848–10853. doi: 10.1039/c9ra10014h

TLIM-catalyzed synthesis of bis(indolyl)methanes.

Entrya R1 R2 R3 R4 Product Time/h Yieldb/%
1 H H H 4-ClC6H5 3a 36 93(90d)
2 H H H 3-NO2-C6H5 3b 36 85
3 H H H 4-NO2-C6H5 3c 36 87
4 H H H 2-F-C6H5 3d 36 99
5 H H H 4-CN-C6H5 3e 36 98
6 H H H C6H6 3f 36 98
7 H H H 4-CH3-C6H5 3g 36 95
8 H H H 4-OCH3-C6H5 3h 36 95
9 H H H 4-OH-3-OCH3-C6H4 3i 36 88
10 H H H 2-OH-3-OCH3-C6H4 3j 36 88
11 H H H C3H7 3k 72 87
12 H H H Hc 3l 36 75
13 H H H 2-Thienyl 3m 72 89
14 H H H 2-Pyridyl 3n 72 72
15 H H H 4-t-C4H9-C6H5 3o 72 95
16 H CH3 H 4-Cl-C6H5 3p 36 96d
17 CH3 H H 4-Cl-C6H5 3q 36 98d
18 OCH3 H H 4-Cl-C6H5 3r 36 88d
19 Cl H H 4-Cl-C6H5 3s 36 90d
20 H H CH3 4-Cl-C6H5 3t 36 93d
21 H H H 4-Cl-C6H5 3a 36 94e
22 H H H 4-Cl-C6H5 3a 36 86f
23 H H H 4-Cl-C6H5 3a 36 81g
24 H H H 4-Cl-C6H5 3a 36 77h
25 H H H 4-Cl-C6H5 3a 36 74i
a

Reaction conditions: TLIM (10 mg), aldehyde (1 mmol), indole (2 mmol), water (5 mL), 55 °C.

b

HPLC yield.

c

Reaction conditions: TLIM (10 mg), formaldehyde aqueous solution (37%, 3 mmol), indole (2 mmol), water (5 mL), 55 °C.

d

Isolated yield.

e

Reaction conditions: TLIM (100 mg), 4-chlorobenzaldehyde (10 mmol), 1H-indole (20 mmol), water (50 mL), 55 °C, HPLC yield.

f

HPLC yield of 3a (run 2).

g

HPLC yield of 3a (run 3).

h

HPLC yield of 3a (run 4).

i

HPLC yield of 3a (run 5).