Methyl 3-cyclohexyl-1H-indole-6-carboxylate → Methyl 2-bromo-3-cyclohexyl-1H-indole-6-carboxylate

Temperature

0 °C

Adapting the procedure of L. Chu (Tet. Lett 1997, 38, 3871) methyl 3-cyclohexyl-6-indole carboxylate (4.65 g, 18.07 mmol) was dissolved in a mixture of THF (80 mL) and CHCl3 (80 mL). The solution was cooled in an ice bath and pyridinium bromide perbromide (pyridine tribromide, 7.22 g, 22.6 mmol, 1.25 equivalent) was added. After stirring for 1.5 h at 0° C., the reaction was judged complete by TLC. It was diluted with CHCl3 (200 mL), washed with 1M NaHSO3 (2×50 mL), saturated aqueous NaHCO3 (2×50 mL) and brine (50 mL). After drying over Na2SO4, the solvent was removed under reduced pressure and the residue crystallized from TBME—hexane. The desired 2-bromoindole derivative was collected by filtration, washed with hexane and dried (3.45 g). Evaporation of mother liquors gave a red solid that was purified by flash chromatography using 15% EtOAc in hexane yielding an additional 3.62 g of pure material. Total yield was 5.17 g (85% yield).

1. temperatureThe solution was cooled in an ice bath
2. washwashed with 1M NaHSO3 (2×50 mL), saturated aqueous NaHCO3 (2×50 mL) and brine (50 mL)
3. dry with materialAfter drying over Na2SO4
4. customthe solvent was removed under reduced pressure
5. customthe residue crystallized from TBME—hexane
6. filtrationThe desired 2-bromoindole derivative was collected by filtration
7. washwashed with hexane
8. customdried (3.45 g)
9. customEvaporation of mother liquors
10. customgave a red solid that
11. customwas purified by flash chromatography

ORD record

ord-4244d1b60c6f4f2e8ae60cfd9273bf47

Source dataset

uspto-grants-2007_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07157486B2