Trifluoroacetic acid → 6-Bromo-8-fluoro-3,4-dihydro-2H-pyrazino[1,2-a]indol-1-one

Temperature

0 °C

To a stirred solution of ethyl 7-bromo-1-(2-(tert-butoxycarbonylamino)ethyl)-5-fluoro-1H-indole-2-carboxylate (step A) (1.43 g, 3.33 mmol) in dichloromethane (15.2 ml) was added drop wise at 0° C. trifluoroacetic acid (4.79 g, 3.23 ml, 42.0 mmol). Afterwards the solution was allowed to stir for 15 min at 0° C., and for 30 min at room temperature. The reaction mixture was evaporated and the remaining material was solved in methanol (15.2 ml). Potassium carbonate (1.83 g, 13.3 mmol) was added and the mixture was allowed to stir at room temperature for 17 h. The mixture was evaporated, water (50 ml) was added and the mixture was extracted with dichloromethane (2×40 ml). The combined organic layers were washed with brine (50 ml), dried (MgSO4) and evaporated. The crude product (0.86 g) was purified by trituration with dichloromethane (3 ml) and heptane (15 ml) to yield the title compound as an off-white solid (0.85 g, 90%), MS (ISN) m/z=283.2 [(M+H)+], mp 253.5° C.

1. waitfor 30 min at room temperature
2. customThe reaction mixture was evaporated
3. stirringto stir at room temperature for 17 h
4. customThe mixture was evaporated
5. additionwater (50 ml) was added
6. extractionthe mixture was extracted with dichloromethane (2×40 ml)
7. washThe combined organic layers were washed with brine (50 ml)
8. dry with materialdried (MgSO4)
9. customevaporated
10. customThe crude product (0.86 g) was purified by trituration with dichloromethane (3 ml) and heptane (15 ml)

ORD record

ord-e74a77eb4110403e988c47f4b1f6151a

Source dataset

uspto-grants-2016_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09284321B2