Hydrochloric Acid → 7-Fluoro-2,3,4,9-tetrahydro-1H-beta-carboline

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Reaction Steps

6-Fluorotryptamine (0.71 g) was dissolved in tetrahydrofuran (30 ml), a 4N hydrochloric acid-ethyl acetate solution (1.2 ml) was added dropwise, and the mixture was stirred at room temperature. The solvent was evaporated under reduced pressure. Glyoxylic acid monohydrate (Aldrich Co., 403 mg), a 1N potassium hydroxide solution (3.98 ml) and water (80 ml) were added to the obtained residue, and the mixture was stirred with heating at 80° C. for 1.5 hr. After ice-cooling, the precipitate was collected by filtration and washed with water to give a pale-brown solid. Water (80 ml) and concentrated hydrochloric acid (2 ml) were added to the obtained solid, and the mixture was stirred with heating at 80° C. for 1 hr. Concentrated hydrochloric acid (2 ml) was further added, and the mixture was heated under reflux for 1 hr. The insoluble material was hot filtrated, and the filtrate was adjusted to pH 12 or above with a 6N aqueous sodium hydroxide solution. The precipitated solid was collected by filtration, washed with water, and dried to give 7-fluoro-2,3,4,9-tetrahydro-1H-β-carboline (516 mg, yield 68%).

Provenance & Evidence