Table 1. Optimization of Reaction Conditions for the Sonochemical Synthesis of 3-Hydroxy-5,5-dimethyl-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)cyclohex-2-enone 4(a)^a.

entry	source of iodine	solvent	time (h)b	yieldc
1	−	−	2	NR
2	−	H2O	2	NR
3	NaI	H2O	1	28
4	KI	H2O	1	33
5	CuI	H2O	1	55
6	ZnI2	H2O	1	47
7	I2 (15 mol %)	−	1.5	62
8	I2 (15 mol %)	H2O	1	79
9	I2(20mol %)	H2O	1	84
10	I2 (20 mol %)	H2O	1.5	84
11	I2 (25 mol %)	H2O	1	83

^aReaction conditions: 2-aminopyridine (1 mmol) 1(a), acetophenone (1 mmol) 2(a), and dimedone (1 mmol) (3).

^bAll the reactions were monitored by TLC.

^cIsolated yield.