Cascade cyclization of 3(5)-aminopyrazoles with aromatic aldehydes and cyclohexanediones

Three-component condensation of 5(3)-amino-3(5)-methylpyrazole with aromatic aldehydes and 1,3-cyclohexanedione afforded mixtures of 3-methyl-4-aryl-2,4,6,7,8,9-hexa hydro-5H-pyrazolo3,4-b]quinolin-5-ones and 2-methyl-9-aryl-5,6,7,9-tetrahydro pyrazolo5,1-b]quinazolin-8(4H)-ones. The reaction of 3-aminopyrazolo-4-carbonitrile and ethyl 3-aminopyrazolo-4-carboxylate with aldehydes and cyclo hexanedione or dimedome is regioselective and leads to the formation of partially hydrogenated pyrazolo 5,1-b]quinazolin-8-one systems. In all compounds the dihydroazine ring exists in the enamine tautomeric form.