Potassium Hydroxide Impregnated Alumina (KOH-Alumina) as a Recyclable Catalyst for the Solvent-Free Multicomponent Synthesis of Highly Functionalized Substituted Pyridazines and/or Substituted Pyridazin-3(2H)-ones under Microwave Irradiation

Table 1

Optimization of the reaction condition and the catalyst recyclability with compound 4a.

Entry	Reaction conditions	Time (min)	Yield (%)^a
1	KOH-alumina (5 mol%)	3	57
2	KOH-alumina (5 mol%)	10	64
3	KOH-alumina (10 mol%)	2	60
4	KOH-alumina (10 mol%)	4	72
5	KOH-alumina (10 mol%)	6	89
6	KOH-alumina (10 mol%)	8	88
7	KOH-alumina (recycled once)	15	61
8	KOH-alumina (recycled twice)	18	30
9	KOH-alumina (recycled three times)	22	27

^aIsolated yields.