Acetic Acid → 2-Allyl-1-[1-(4-chlorophenyl)cyclobutyl]-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline oxalate

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Reaction Steps

A mixture of 1-[1-(4-chlorophenyl)cyclobutyl]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (7.29 g prepared as described in Example 50), allyl bromide (2.66 g), anhydrous potassium carbonate (5.52 g) and acetone (100 ml) was heated under reflux for 2 hours. The reaction mixture was filtered and the solvent was removed by evaporation to give a residue which was digested with a 9:1 mixture of petroleum ether and triethylamine. The solution was decanted from a residual tar, filtered and the solvent removed to give a residue. A sample of this residue (3 g) was heated under reflux in a nitrogen atmosphere with glacial acetic acid (50 ml) and 48% hydrobromic acid (50 ml) for 7 hours. The reaction mixture was added to ice/water and excess aqueous ammonia solution added slowly under nitrogen. The resulting mixture was extracted with ethyl acetate. The organic layer was evaporated and the residue dissolved in ethyl acetate. Addition of a solution of oxalic acid in ethyl acetate gave 2-allyl-1-[1-(4 -chlorophenyl)cyclobutyl]-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline oxalate [m.p. 85° C. (dec)] which was dried in air.

Provenance & Evidence