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 2

KOH-alumina (10 mol%) catalyzed solvent-free synthesis of substituted pyridazines under microwave (MW) irradiation.

Entry	Substrate 2 (R^3)	Substrate 1 R^1/R^2	Product 4	Time (min)	Yield (%)^a	M.p. (°C)^c
1	R^3 = C6H5	R^1 = R^2 = C6H5	4a	6	89	182–184^[21]
2	R^3 = 4-CH3C6H4	R^1 = R^2 = C6H5	4b	5	86	160–162^[21]
3	R^3 = 2-CH3OC6H4	R^1 = R^2 = C6H5	4c	10	76	137–139
4	R^3 = 4-CH3OC6H4	R^1 = R^2 = C6H5	4d	8	85^b	164–166^[21]
5	R^3 = 4-BrC6H4	R^1 = R^2 = C6H5	4e	8	81	147–149^[21]
6	R^3 = 4-ClC6H4	R^1 = R^2 = C6H5	4f	6	76	179–181^[21]
7	R^3 = 4-NO2C6H4	R^1 = R^2 = C6H5	4g	6	73^b	164–166^[21]
8	R^3 =	R^1 = R^2 = C6H5	4h	8	77^b	190–192^[21]

^aSolated yield. ^bPurified by column chromatography. ^cLiterature references.