Sulfuric Acid → 1H-3-Benzazepine, 2,3,4,5-tetrahydro-7,8-dimethoxy-1-phenyl-

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Reaction Steps

A solution of 30.1 g. (0.1 mol) of N-[2-(3,4-dimethoxyphenyl)ethyl]-2-phenyl-2-hydroxyethylamine in 120 ml. of trifluoroacetic acid and 8.2 ml. of concentrated sulfuric acid is heated at reflux for two hours. After cooling to room temperature, the trifluoroacetic acid is removed under reduced pressure and 100 ml. of ice-water is added. This mixture is basified to pH 9-10 with 10% sodium hydroxide solution and thoroughly extracted with ethyl acetate. The extract is dried and evaporated to give 7,8-dimethoxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine as an oil. Various salts can readily be prepared from the free base. For example, 5 g. (0.0176 mol) dissolved in dry ether is treated with methanesulfonic acid dropwise until no further precipitate is formed. The solid is filtered and washed with dry ether to give 7,8-dimethoxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine methanesulfonate, m.p. 133°-136° C.

Provenance & Evidence