Studies on the Syntheses of N-Heterocyclic Compounds. IX. On the Reduction of 2-Aryl-5, 8-disubstituted Pyrimido[4, 5-d]pyridazine

Abstract

Reduction of 2-aryl-5, 8-disubstituted pyrimido[4, 5-d]pyridazine (4) to 2-aryl-3, 4-dihydro-5, 8-disubstitutedpyrimido[4, 5-d]pyridazine (5) was carried out with sodium borohydride, lithium aluminum hydride, sodium isopentoxide, and a catalyst. Acylation of 3, 4-dihydro-compound (5) gave 2-aryl-3-acyl-3, 4-dihydro-5, 8-dimorpholinopyrimido[4, 5-d]-pyridazine (16), and alkylation of 5 gave 2-aryl-3-alkyl-3, 4-dihydro-5, 8-dimorpholinopyrimido[4, 5-d]pyridazine (12). Among these compounds, 2-aryl-5, 8-disubstituted-3, 4-dihydropyrimido[4, 5-d]pyridazine (5a-g) showed a strong diuretic activity.