Table 1. Optimization Experiments for the Condensation Reaction.

entry	light	ZnO-ZnS (g)	time (min)	yield (%)
1			30	7
2	green LED, 25 W		30	15
3	dark	0.01	30	38
4	20 × 1 W (white LED)	0.01	30	65
5	25 W (green LED)	0.01	30	87

Dimedone, benzaldehyde, and 4-hydroxycoumarin were condensed in acetonitrile under air at room temperature. 1 mmol of each reagent was used.