N-bromosuccinmide in chloroform T=20°C; 18 h;

2-hydroxy-1,3-isoindolinedione; oxygen; anhydrous cobalt diacetate; metachloroperbenzoic acid in acetonitrile T=20°C; 4 h; Title compound not separated from byproducts.;

2-hydroxy-1,3-isoindolinedione; oxygen; anhydrous cobalt diacetate in acetic acid T=100°C; 3 h; Title compound not separated from byproducts.;