A solution of 0.513 gm (2 mMol) 5-carboxy-3-(1-methyl-1,2,5,6-tetrahydropyridin-4-yl)-1H-indole in 5.1 mL ethanol was cooled in an ice bath while 0.51 mL sulfuric acid was added dropwise. The resulting mixture was heated at reflux for 5 hours. The now homogeneous solution was poured into 50 mL cold water and was then made basic with saturated ammonium hydroxide. The light yellow precipitate was collected by filtration and then recrystallized from ethanol to provide 0.24 gm (42%) of the desired compound as light yellow crystals.
