Lithium hydroxide, monohydrate → Indole-2-carboxylic acid

Participants

Reaction Steps

To a solution of the above ether (770 mg, 2.1 mmol) in THF/MeOH (25 mL/10 mL) was added LiOH.H2O (218.1 mg, 2.50 eq) dissolved in 3 mL of water. The clear reaction solution was stirred at room temperature for 5 h, then concentrated in vacuo. The residual aqueous solution was diluted with water (15 mL), and extracted with ether. The organic layer was disgarded. The aqueous layer was acidified to pH 5 with 1.4 N HCl (˜2.5 mL). A large amount of white precipitates were extracted with 200 mL of EtOAc and washed with brine. The combined organics were dried over MgSO4, filtered and concentrated in vacuo to give the desired indole-2-carboxylic acid intermediate (644 mg, 90.5%) as a white foam.

Provenance & Evidence