A Green and Efficient Method for the Preparation of 3,4-Dihydropyrimidin-2(1H)-ones Using Quaternary Ammonium-Treated Clay in Water

Table 1

Optimization of experimental conditions for synthesis of DHPMs.

Entry	Catalyst	Temperature	Time (h)	Result
1	CTAB-modified clay (0.02 g)	Reflux	0.5	Not completed, 44% yield
2	CTAB-modified clay (0.04 g)	Reflux	0.5	Not completed, 77% yield
3	CTAB-modified clay (0.05 g)	Reflux	0.5	Completed, 89% yield
4	CTAB-modified clay (0.05 g)	r.t	0.5	Not completed, 35% yield
5	Clay	Reflux	0.5	No reaction

Reaction conditions: benzaldehyde (1 mmol), acetylacetone (1 mmol), and urea (1.5 mmol).