Application of organolithium and related reagents in synthesis. part 22. synthetic strategies based on ortho-aromatic metallation. a concise regiospecific conversion of benzoic acids into the 4-pyridyl-2H-phthalazin-1-ones

摘要

The synthesis of phthalazin-1-ones 6, 7, 8 via the reaction of 3-hydroxyisoindolin-1-ones 3, 4, 5 with hydrazine hydrate is described. Starting compounds 3, 4, 5 were regiospecifically prepared upon the lithiation (n-BuLi) of the benzanilides 1 and subsequently the reaction of the dilithiated anilides 2 with methyl pyridinecarboxylates.