Easy Access to Coumarin Derivatives Using Alumina Sulfuric Acid as an Efficient and Reusable Catalyst under Solvent-Free Conditions

Table 1

Pechman condensation of resorsinol with ethylacetoacetate using different types of alumina-based catalyst^a.

Entry	Catalyst	Yield (%)
1	Al2O3 (Neuter)	5
2	Al2O3 (Acidic)	10
3	Al2O3/H3PO4	60
4	Al2O3/HNO3	50
5	Al2O3/H2SO4	80
6	Al2O3/HClO4	80
7	H2SO4	80
8	ASA	85

aReaction conditions: resorcinol (1 mmol), ethylacetoacetate (1 mmol), ASA (0.04 g), and solvent free, 110°C.