N-Boc-5-bromoindole → 5-[(1-Tert-butoxycarbonyl-2-propyl-pyrrolidin-2-yl)-hydroxy-methyl]-indole-1-carboxylic acid tert-butyl ester

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Reaction Steps

To a stirred solution of 5-bromo-indole-1-carboxylic acid tert-butyl ester (0.700 g, 2.37 mmol) in ether (20 mL) at −78° C. and under nitrogen was added tert-butyllithium (3.64 mL of 1.43 M solution in pentanes, 5.21 mmol) dropwise. After 30 minutes, a solution of 2-formyl-2-propyl-pyrrolidine-1-carboxylic acid tert-butyl ester (0.569 g, 2.37 mmol) in ether (5 mL) was added to the reaction mixture dropwise. The reaction mixture was stirred for one hour, then quenched by the addition of saturated aqueous NH4Cl, and extracted with EtOAc. The combined organic extracts were washed with saturated aqueous NaHCO3 and brine, then dried (MgSO4), filtered and concentrated in vacuo. Purification by chromatography (silica, 0-60% EtOAc in hexanes) gave 5-[(1-tert-butoxycarbonyl-2-propyl-pyrrolidin-2-yl)-hydroxy-methyl]-indole-1-carboxylic acid tert-butyl ester (0.466 g, 1.02 mmol, 43%) as a yellow oil.

Provenance & Evidence