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 3

Influence of temperature on the solvent-free synthesis of ethyl-6-methyl-4-phenyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate in the presence of Al(NO₃)₃·9H₂O^a.

Entry	Temperature (^°C)	Time (min.)	Yield (%)
1	r.t.	300	53
2	40	210	65
3	60	150	76
4	80	30	97

aAll reactions were carried out with benzaldehyde (2 mmol), ethyl acetoacetate (2 mmol), urea (3 mmol), and Al(NO₃)₃·9H₂O (0.3 mmol).