An Efficient One-Pot Multi-Component Synthesis of 3,4-Dihydropyrimidin-2-(1H)-Ones/Thiones Catalyzed by Bismuth (III) Sulfate Trihydrate under Solvent-Free Conditions

Table 1

Bismuth (III) sulfate trihydrate catalyzed synthesis of 5-(ethoxycarbonyl)-4-phenyl-6-methyl-3,4-dihydropyrimidin-2(1H)-one (5a) in different solvents conditions.

Entry	Solvent	Catalyst (mol%)	Time (min)	Yield (%)
1	Ethanol	10	120	25
2	Methanol	10	120	25
3	Acetonitrile	10	120	40
4	Dichloromethane	10	120	33
5	Chloroform	10	120	35
6	Ethyl acetate	10	120	45
7	THF	10	120	20
8	Solvent-free	5	120	65
9	Solvent-free	10	60	89
10	Solvent-free	15	120	78
11	Solvent-free	20	120	55
12	Solvent-free	0	360	10

Reaction conditions: 2 mmol benzaldehyde, 2.5 mmol ethyl acetoacetate, 2.5 mmol urea/thiourea, and Bismuth (III) sulfate trihydrate (10 mol%) were refluxed with stirring for 60 min.