An Efficient One-Pot Green Protocol for the Synthesis of 5-Unsubstituted 3,4-Dihydropyrimidin-2(1H)-Ones Using Recyclable Amberlyst 15 DRY as a Heterogeneous Catalyst via Three-Component Biginelli-Like Reaction

Table 4

Amberlyst 15 DRY catalyzed synthesis of 5-unsubstitued 3,4-dihydropyrimidin-2(1H)-ones 2(a–f).

Entry	R	Products^a	Yield^b (%)	M.P (°C)
1	C6H5	2a	90	233–236
2	4-(Cl)–C6H4	2b	92	267–269
3	4-(CH3)–C6H4	2c	86	248–250
4	4-(CH3O)–C6H4	2d	84	259–261
5	2-(Cl)–C6H4	2e	91	260–263
6	3-(CH3O) –C6H4	2f	88	256–258

^aReaction conditions: acetophenone (1.0 mmol), benzaldehyde (1.0 mmol), and urea (1.5 mmol) in dry ethanol (10 mL), ion exchange resin (50 mg) at refluxing temperature. ^bIsolated yields.