sodium azide in dimethyl sulfoxide Ambient temperature;

1: 3-bromobenzo[b]furan With sodium hexamethyldisilazane in tetrahydrofuran T=0°C; 0.25 h; Inert atmosphere; 2: N,N-dimethyl-formamide in tetrahydrofuran T=0°C; 5.5 h; Inert atmosphere; 3: With phosphoric acid in tetrahydrofuran; water Inert atmosphere; regioselective reaction;

in diethyl ether; water; N,N-dimethyl-formamide

phosphorus oxytribromide in chloroform