5-Bromo-1-(triisopropylsilyl)-1H-indole → 2-benzyl-2-(1-triisopropylsilanyl-1H-indole-5-carbonyl)-pyrrolidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 5-bromo-1-triisopropylsilanyl-1H-indole (0.55 g, 1.57 mmol) in THF (10 mL) at −78° C. under nitrogen atmosphere was added tert-butyllithium (2.02 mL of 1.55 M solution in pentanes, 3.13 mmol) dropwise. After one hour, the reaction mixture was added rapidly to a cold (−78° C.) solution of (R)-2-benzyl-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester (0.50 g, 3.13 mmol) in THF (10 mL). The reaction mixture was stirred at −78° C. for one hour, then warmed to room temperature and stirred for two hours. The reaction mixture was quenched by the addition of saturated aqueous NH4Cl (20 mL) then extracted with EtOAc. The combined extracts were washed with brine then dried (MgSO4), filtered and concentrated in vacuo. Purification by chromatography (silica, 0-20% EtOAc in hexanes) gave 2-benzyl-2-(1-triisopropylsilanyl-1H-indole-5-carbonyl)-pyrrolidine-1-carboxylic acid tert-butyl ester (0.145 g, 0.259 mmol, 16%) as a colourless gum.

Provenance & Evidence