Acetic Acid Mixture with Hydrobromic Acid → 1H-Indole, 5-bromo-3-(2-pyrrolidinylmethyl)-, (R)-

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Reaction Steps

To 3-(1-benzyloxycarbonylpyrrolidin-2(R)-ylmethyl)-5-bromo-1H-indole (see Preparation 35B) (10.0 g, 24.2 mmol) was added dropwise hydrogen bromide/acetic acid (36% w/w) (17 ml) at 0° C., with stirring. After 50 minutes at 0° C. the solvent was removed by evaporation under reduced pressure, and the residue azeotroped with toluene. The resulting oil was partitioned between dichloromethane and 2M aqueous sodium carbonate. The separated aqueous phase was re-extracted with dichloromethane and the combined organic phases dried (Na2SO4) and evaporated under reduced pressure. Purification by column chromatography on silica gel, eluting with a gradient of dichloromethane: methanol:0.88 aqueous ammonia (95:5:0 to 95:5:2), yielded the title compound as an oil (2.01 g). Found: C,54.75; H,5.41; N,9.63. C13H15BrN2.1/5CH2Cl2 requires: C,54.84; H,5.37; N,9.67%.

Provenance & Evidence