Synthesis of azo-linked diindolyl methanes using Fe³⁺-montmorillonite K10 under solvent-free condition

Peer review under responsibility of Taibah University.

Figures & data

Scheme 1 Synthesis of azo-linked diindolylmethanes using Fe⁺³-montmorillonite K10.

Table 1 The solvent and catalyst amount optimization on the synthesis of 3a.

Entry	Solvent	Amount of catalyst	Reaction time (min)	Yield (%)^a
1	Toluene	0.1	720	35
2	CHCl3	0.1	660	40
3	CH3CN	0.1	540	55
4	H2O	0.1	480	50
5	EtOH	0.1	420	60
6	–	0.1	4	94
7	–	0.01	13	47
8	–	0.03	11	55
9	–	0.05	9	56
10	–	0.15	7	57

a Isolated yield.

Table 2 Synthesis of azo-linked diindolylmethane derivatives (3a–k) using montmorillonite Fe³⁺-K10 under solvent free-conditions.

Entry	Ar	Product	Solvent free		Mp (°C)
			Time (min)	Yield (%)^a^c
3a	C6H5		4 (15)^b	94 (78)^b	263
3b	C6H5		6	90	265
3c	4-NO2C6H4		4 (15)^b	92 (75)^b	>320
3d	4-NO2C6H4		3	96	>320
3e	4-NO2C6H4		4	94	>320
3f	4-CH3C6H4		12	75	>320
3g	4-CH3C6H4		9	89	258
3h	4-BrC6H4		5	99	263
3i	4-BrC6H4		5	98	263
3j	2-CH3-4-NO2C6H3		8	96	>320
3k	2-CH3-4-NO2C6H3		10	90	259

a Isolated yield.

b in the presence of K10.

c All compounds were characterized by IR, ¹H NMR, ¹³C NMR, mass spectroscopy and elemental analysis.

Scheme 2 The comparative reaction for the Synthesis of azo-linked diindolylmethanes.