Methanol → HCID 57743038, compound
Reaction equation
[Br:1][C:2]1[C:3]([C:11]([OH:13])=[O:12])=[C:4]2[NH:10][CH:9]=[N:8][C:5]2=[N:6][CH:7]=1.OS(O)(=O)=O.[CH3:19]O>>[Br:1][C:2]1[C:3]([C:11]([O:13][CH3:19])=[O:12])=[C:4]2[NH:10][CH:9]=[N:8][C:5]2=[N:6][CH:7]=1Participants
4
Procedure
Absolute methanol (30 ml) is added to 6-bromo-1H-imidazo[4,5-b]pyridine-7-carboxylic acid x208 (Zerenex; 2.2 g, 9.1 mmol). Concentrated H2SO4 (4 ml) is added to the obtained suspension at 0° C. The reaction mixture is refluxed under protection from the air moisture and vigorous stirring for 10 h. The reaction mixture is then evaporated to half-volume in the vacuum of a rotary evaporator and neutralized under cooling with ice with aqueous ammonia to pH 8-9. The formed precipitate is quickly separated by filtration, washed with ice-cold water (2×30 ml), and dried over P2O5 at 1 mmHg overnight to afford methyl 6-bromo-1H-imidazo[4,5-b]pyridine-7-carboxylate x209 (1.63 g).