Ammonium Chloride → Ethyl 4-bromo-1H-indole-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of 23 mL of ethyl azidoacetate and 7.6 mL of 2-bromobenzaldehyde in 40 mL ethanol was added dropwise to a solution of 4.5 g sodium in 180 mL ethanol, in a bath at −10° C., at a rate such that the reaction temperature does not rise above 8° C. After the addition is complete, the mixture is stirred at 5-10° C. for 30 min. The reaction mixture is then poured into a mixture of 28 g of NH4Cl in 1 L ice, and extracted with 1:4 CH2Cl2hexane. The organic phase is filtered through 150 mL silica gel, which is rinsed with 200 mL of the same solvent. This is evaporated to near dryness, diluted with 300 mL xylene, and stabilised with 60 mg of 2,5-di-t-butylhydroquinone. This mixture is heated with a distillation head until 50 mL of xylene has distilled. The mixture is cooled and evaporated in vacuo to a volume of 80 mL, which is diluted with 80 mL of hexane. A white solid forms upon cooling to 0° C., which is filtered off.

Provenance & Evidence