Molecular Iodine: A Powerful Catalyst for the Knoevenagel Condensation of Isatins with Malononitrile

Table 3

Comparison of the effect of catalysts in synthesis of 3a.

Entry	Reagent and conditions	Time (min)	Yield (%)^b	Reference
1	Piperidine acetate, CH3CN, reflux	120	85	[5]
2	DBU, EtOH, reflux	15	88	[6]
3	Piperidine, EtOH, reflux	15	84	[6]
4	Al2O3, acetone, MW	5	78	[7]
5	I2, EtOH, 60°C	5	97	The study