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 2 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