Alternatively, noribogaine hydrochloride was prepared from ibogaine hydrochloride by first converting it to a free base, ibogaine, by treating with methanol followed by treatment with a base such as potassium carbonate in a solvent such as methylene chloride. Ibogaine was then converted to noribogaine hydrobromide by treating with boron tribromide or other conventional demethylating agent in a solvent such as methylene chloride followed by quenching with methanol to give noribogaine hydrobromide. Noribogaine hydrobromide was then converted to the free base by treating with a base such as potassium carbonate in a solvent such as methylene chloride, followed by purification over silica, and then by conversion to the hydrochloride salt using HCl in a solvent such as isopropanol as shown in Scheme 3 below.
