Pyridazinones represent an important class of heterocyclic compounds with diverse
biological activity, making them promising candidates for therapeutic applications.
Among them, 3(2H)-pyridazinones and their 4,5-dihydro derivatives stand out due to
their hypotensive, cardiotonic, and antiaggregatory effects.
In this master’s thesis, we focused on the synthesis of less-studied 6-substituted
tetrahydropyridazin-3(2H)-ones. As starting materials, γ-keto acids were used and
converted into the corresponding 4,5-dihydropyridazin-3(2H)-ones via reaction with
hydrazine hydrate. A major challenge in the synthetic route was the reduction of the imine
bond present in the dihydro derivatives. Since no broadly applicable method for this
transformation is described in the literature, we investigated various reduction conditions,
with special emphasis on selective hydrogenation. The influence of different catalysts,
solvents, acids, and bases on the reduction outcome, conversion, and selectivity of the
products was systematically studied.
Furthermore, we explored the possibility of synthesizing 6,6-disubstituted
tetrahydropyridazin-3(2H)-ones by nucleophilic addition of Grignard and organolithium
reagents. This work contributes to a better understanding of the synthetic strategies for
six-membered pyridazinone systems, sheds light on their reactivity, and opens new
perspectives for future research in medicinal and pharmaceutical chemistry.
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