4-bromo-1H-indole-2-carboxylic acid → tert-butyl 4-bromo-1H-indole-2-carboxylate

Participants

Reaction Steps

To 7 g 4-Bromo-1H-indole-2-carboxylic acid in 150 ml toluene, 28 ml Di-tert-butoxymethyl-dimethyl-amine were added dropwise at 80° C. The reaction mixture was heated under reflux for additional 12 h. After removal of the solvents under reduced pressure the residue was dissolved in 200 ml DCM and washed with sat. aqueous NaHCO3 solution (2×50 ml). The organic layer was dried over MgSO4 and concentrated under reduced pressure. The residue was purified by chromatography on silica gel eluting with n-heptane/ethyl acetate 9:1. The fractions containing the product were collected and concentrated under reduced pressure. Yield: 6.5 g . MS (ESI+): m/e=297.

Provenance & Evidence