Hydrochloric Acid → ethyl 4-acetoxy-1-cyclopropyl-1H-indole-6-carboxylate

Participants

Reaction Steps

14.57 g of Na was added portionwise to 400 ml of EtOH. To the mixture was added a solution of 38.91 g of 1-cyclopropyl-1H-pyrrole-2-carbaldehyde and 48.23 ml of diethyl succinate in 100 ml of EtOH at 50° C., then the mixture was refluxed overnight. 140 ml of 5N HCl was added to the mixture at 0° C. and EtOH was evaporated. The concentrate was extracted with CHCl3 and the extract was dried over Na2SO4 and concentrated to give red oil. The material was dissolved in 400 ml of acetic anhydride and 47.40 g of AcOK was added thereto. The mixture was refluxed for 30 min and allowed to cool to room temperature. The mixture was filtrated and the filtrate was concentrated. The residue was purified on SiO2 column chromatography (n-hexane-EtOAc system) to give 72.3 g of ethyl 4-acetoxy-1-cyclopropyl-1H-indole-6-carboxylate as red oil.

Provenance & Evidence