Sulfuric Acid → 9-Nitro-1,2,3,5,6,10b-hexahydropyrrolo[2,1-a]isoquinoline hydrochloride

Participants

Reaction Steps

To concentrated sulfuric acid (200 ml) at -10° C. was added portionwise 1,2,3,5,6,10b-hexahydropyrrolo[2,1-a]isoquinoline (20.5 g, 118 mmol) over 2 h. After addition was complete, potassium nitrate (1 1.6 g, 0.115 mol) was added portionwise over 3 h. The reaction mixture was stirred for an additional 3 h and then poured onto ice and made basic with concentrated ammonium hydroxide. The product was extracted twice with dichloromethane. The dried (magnesium sulfate) organic phase was concentrated to give a red oil which was immediately dissolved in isopropanol (200 ml) and made acidic with saturated isopropanol-HCl. The resulting precipitate was collected to give a tan solid (18.9 g). Recrystallization from 95% ethanol (100 ml) afforded the title compound as an off-white solid (11.5 g, 62%), m.p. 243-5° C. This was converted to the free base by dissolving in water, making basic with dilute base, and extracting with dichloromethane to give 96% recovery of the product.

Provenance & Evidence