Furo-pyridines, bromination

The crude 7-bromo lactone, prepared by iV-bromosuccinimide bromination of furo[3,4-b]-pyridin-5(7//)-one, reacts with hydrazine or methylhydrazine to give pyrido[2,3-r/]pyridazin-5(6/7)-one (3a) or its 6-mcthyl derivative 3b.8... 

To furo[3,4-i]pyridin-5(7//)-one (0.2 g, t.5mmol)inCC14(30 mL) were added NBS(0.28 g, 1.57 mmol) and DBPO (0.1 g, 0.4 mmol). The mixture was refluxed on a water bath for 2.5 h and the succinimide which had separated from the solution was filtered off. The filtrate was treated with 5% NaHSOj to remove free bromine, washed with H20, dried (CaCl2), and then evaporated. The residue was dissolved in EiOH (10 mL) and hydrazine hydrate (0.3 g, 6 mmol) was added and the solution refluxed on a water bath for 1 h. After cooling, the crystalline mass was recrystallized (EtOH) yield 0.11 g (51% overall) mp 261-263 °C. 

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