5-Bromo-6-methoxy-2-methylquinoline → 5-Bromo-2-methylquinolin-6-ol

Participants

Reaction Conditions

Reaction Steps

A mixture of 5-bromo-2-methyl-6-methoxyquinoline (30 g, 0.12 mol) in 48% HBr (135 mL) was heated to reflux for 7 h then cooled to 5° C. in 1 h to give a brown and thick slurry. The slurry was stirred at 0-5° C. for 1 h then filtered, washed with EtOAc (2×50 mL) and dried in a vacuum oven to give 34.9 g (92%) of the hydrobromide of the title compound as a brown solid. 1H NMR (DMSO) δ 8.26 (d, J=8.7 Hz, 1H), 7.85 (d, J=9.1 Hz, 1H), 7.56 (d, J=9.1 Hz, 1H), 7.45 (d, J=8.7 Hz, 1H), 2.64 (s, 3H). A slurry of the hydrobromide salt of 5-bromo-2-methyl-6-quinolinol (3.4 g, 10.5 mmol) and Amberlyst A-21 ion-exchange resin (1.7 g, pre-washed with MeOH then dried in oven) in MeOH (35 mL) was stirred at room temperature for 3 h. The mixture was then filtered and concentrated in vacuo to give 2.5 g (100%) of a yellow solid. Rf=0.36 (1:1) EtOAc:heptane; 1H NMR (DMSO) δ 8.26 (d, J=8.4 Hz, 1H), 7.82 (d, J=9.3 Hz, 1H), 7.47 (t, J=9.1 Hz, 2H), 2.66 (s, 3H).

Provenance & Evidence