7-BROMO-2-CHLORO-QUINOLINE

Synthesis

General procedure for the synthesis of 7-bromo-2-chloroquinoline from 7-bromoquinolin-2(1H)-one: To an inert reactor equipped with a mechanical stirrer, a reflux condenser, a charging funnel and a caustic scrubber were added 7-bromo-2-hydroxyquinoline (1.22 kg, 5.45 mol), dichloromethane (9.706 kg) and dimethylformamide (0.276 kg). Thionyl chloride (0.973 kg, 8.17 mol, 1.5 eq.) was added slowly and dropwise. The reaction mixture was gradually heated to reflux and kept at reflux until the reaction was complete (about 2 hours). After completion of the reaction, the mixture was cooled to 20-25 °C, USP grade purified water (3.663 kg) was added and stirred. Subsequently, a solution of potassium carbonate (0.828 kg) dissolved in USP grade purified water (0.828 kg) was slowly added with stirring. Stirring was stopped after 15 minutes and left to stratify. After confirming that the pH of the aqueous layer was greater than 7, the dichloromethane layer was separated and washed with USP grade purified water (3.663 kg). USP grade purified water (7.326 kg) was added to the dichloromethane solution and the dichloromethane was removed by distillation until the product precipitated from the aqueous layer. The reactor was cooled to 20-25 °C, the product was collected by filtration and washed with USP grade purified water (2 x 1.22 kg). The product was dried in a vacuum oven at 40-50 °C to give the final 7-bromo-2-chloroquinoline (1.154 kg, 78.8% yield). The product was analyzed by NMR and the results were consistent with the expected structure.

References

[1] Patent: WO2009/2955, 2008, A1. Location in patent: Page/Page column 10
[2] Journal of Medicinal Chemistry, 2011, vol. 54, # 16, p. 5836 - 5857