5-Bromo-1-(triisopropylsilyl)-1H-pyrrolo[2,3-b]pyridine → 2-[hydroxy-(1-triisopropylsilanyl-1H-pyrrolo[2,3-b]pyridin-5-yl)-methyl]-2-propyl-pyrrolidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

To a stirred solution of 5-bromo-1-triisopropylsilanyl-1H-pyrrolo[2,3-b]pyridine (0.587 g, 1.66 mmol) in ether (20 mL) at −78° C. and under nitrogen was added tert-butyllithium (2.30 mL of 1.51 M solution in pentanes, 3.49 mmol) dropwise. After 90 minutes, a solution of 2-formyl-2-propyl-pyrrolidine-1-carboxylic acid tert-butyl ester (0.400 g, 1.66 mmol) in ether (1 mL) was added to the reaction mixture dropwise. After stirring for one hour, the reaction mixture was warmed to ambient temperature over 30 minutes. The reaction mixture was quenched by the addition of saturated aqueous NH4Cl (20 mL) then extracted with EtOAc. The combined extracts were washed with saturated aqueous NaHCO3 and brine, then dried (MgSO4), filtered and concentrated in vacuo to a yellow oil (0.90 g). Purification by chromatography (silica, 5-20% EtOAc in hexanes) gave 2-[hydroxy-(1-triisopropylsilanyl-1H-pyrrolo[2,3-b]pyridin-5-yl)-methyl]-2-propyl-pyrrolidine-1-carboxylic acid tert-butyl ester (0.576 g, 1.12 mmol, 53%) as a colourless gum.

Provenance & Evidence