Sulfuric Acid → 9-Bromo-10-fluoro-3,4,7,8-tetrahydro-[1,4]diazepino[7,1-a]isoquinoline-2,5-dione

Participants

Reaction Steps

methyl 2-(5-bromo-6-fluoro-1,2,3,4-tetrahydroisoquinolin-1-yl)acetate. MeOH (620 mL) was cooled to −15° C. and conc. Sulfuric acid (73.7 mL, 1383 mmol) was added slowly (exotherm) under cooling. To this solution, methyl 2-(2-acetyl-5-bromo-6-fluoro-1,2,3,4-tetrahydroisoquinolin-1-yl)acetate (47.6 g, 138 mmol) was added and the reaction mixture was stirred under reflux for 96 h. The reaction mixture was cooled to RT and slowly added to a solution of NaHCO3 (244 g) in water (500 mL). The slightly basic aqueous solution was extracted with AcOEt (3×). The combined organic layers were washed with saturated aqueous NaHCO3 and brine. The organic layer was dried with sodium sulfate, filtered and the solvent was removed under reduced pressure. The crude product was dried under high vacuo to yield the title compound as yellow foam (41.58 g) which was used without further purification. UPLC-MS: MS 302.1/304.1 (M+H+); UPLC rt 0.51 min.

Provenance & Evidence