Al(NO₃)₃ · 9H₂O: An Efficient Catalyst for the One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Both under Reflux or Solvent-Free Conditions

Table 2

Synthesis of ethyl-6-methyl-4-phenyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate in the presence of Al(NO₃)₃·9H₂O in various solvents under reflux and solvent-free conditions^a.

Entry	Solvent	Time (h:min)	Yield (%)
1	CH3CN	7:00	30
2	EtOH	7:00	92
3	MeOH	7:00	60
4	CHCl3	7:00	Negligible
5	EtOH/H2O (1: 1)	7:00	30
6	H2O	7:00	25
7	H2O^b	7:00	30
8	H2O^c	7:00	25
9	EtOH^b	7:00	80
10	EtOH^c	7:00	70

aAll reactions were carried out with benzaldehyde (2 mmol), ethyl acetoacetate (2 mmol), urea (3 mmol), Al(NO₃)₃·9H₂O (0.3 mmol); bcatalyst: Al(NO₃)₃·9H₂O/SDS (1: 3) (15% mol); ccatalyst: Al(DS)₃ (0.3 mmol).