Table 1.

Optimization of reaction of 4-thiazolidinone 4a and arylhydrazonal 5a.

Entry	Solvent	Additive	T (°C)	Time	Product (% Yield)
1	EtOH	AcONH4 or AcONa	reflux	12 h	—
2	1,4-dioxane	AcONH4 or AcONa	reflux	12 h	—
3	CH3CN	AcONH4 or AcONa	reflux	12 h	—
4	DMF	AcONH4 or AcONa	reflux	12 h	—
5	AcOH	AcONH4	reflux	4 h	43a
6	AcOH	AcONH4	MW(125 °C, 250 W)	25 min	65b
7	AcOH	AcONH4	Q-tube(150 °C)	30 min	81a
8	AcOH	AcONa	MW(130 °C, 250 W)	30 min	73
9	AcOH	AcONa	Q-tube(150 °C)	30 min	86
10	AcOH	AcONa	Q-tube(160 °C)	30 min	92
11	AcOH	AcONa	Q-tube(170 °C)c	25 min	98

Reaction conditions: ^a4-thiazolidinone 4a (5 mmol), arylhydrazonal 5a (5 mmol) and additive (10 mmol) in solvent (10 mL), ^b4-thiazolidinone 4a (2 mmol), arylhydrazonal 5a (2 mmol) and additive (4 mmol) in solvent (5 mL). ^cTemperature of the oil bath.