Ammonium Hydroxide → HCID 21584357, compound

Participants

Reaction Steps

To a solution of 1-propyl-3,4-dihydroisoquinoline (7.4 g, 42 mmol) [E. Spath, F. Berger, and W. Kuntara, Chem. Ber., 1930, 63B, 134] in concentrated sulfuric acid (100 ml) at 0° C. was added in a single portion potassium nitrate (4.5 g, 45 mmol). The solution was allowed to slowly warm to ambient temperature overnight. The reaction mixture was poured onto ice and was basified with concentrated ammonium hydroxide. The resulting solid that formed in the cooled solution could not be filtered off satisfactorily. Hence, the reaction mixture was extracted twice with dichloromethane and the dried (magnesium sulfate) organic phases were concentrated in vacuo to give the intermediate 7-nitro-1-propyl-3,4-dihydroisoquinoline as an oil (8.78 g, 94%). This solid was taken up in methanol (200 ml), cooled to 0° C., and sodium borohydride (3.0 g) was added in portions over 0.5 h. After stirring for an additional 0.5 h, the reaction mixture was acidified to pH 5 using 6M hydrochloric acid. The solvent was concentrated at the rotoevaporator and the residue was partitioned between dichloromethane and dilute sodium hydroxide solution. The dried (magnesium sulfate) organic phase was concentrated to give the crude product as the free base. This was taken up in ethanol (200 ml) and hydrochloric acid in ethanol was added until acidic. The resulting solid which formed was collected to afford the title compound (5.60 g, 52%) as a pale yellow solid, m.p. 229-30.5° C. (dec.).

Provenance & Evidence