Isoquinoline → 5-Bromoisoquinoline

Participants

Reaction Conditions

Reaction Steps

Into a 250 mL 3-necked round bottom flask was placed H2SO4 (150 mL). To the above was added isoquinoline (17 g, 131.62 mmol) in several batches, while cooling to a temperature of 0° C. To the above was added NBS (29.2 g, 164.04 mmol) in several batches, while cooling to a temperature of −25-−22° C. The resulting solution was allowed to react, with stirring, for 2 hours while the temperature was maintained at −25-−22° C. The resulting solution was allowed to react, with stirring, overnight while the temperature was maintained at room temperature. The reaction progress was monitored by TLC (ethyl acetate/petroleum ether=1:5). The reaction mixture was then quenched by the adding 1000 mL of H2O/ice. Adjustment of the pH to 8-10 was accomplished by the addition of NH3. H2O (30%). The resulting solution was extracted four times with 500 mL of ethyl acetate and the organic layers combined and dried over Na2SO4. The residue was purified by eluting through a column with a 1:5 ethyl acetate/petroleum ether solvent system. This resulted in 22.24 g (81%) of 5-bromoisoquinoline as a white solid.

Provenance & Evidence