N,N-diphenylaminoacetaldehyde diethyl acetal (3.5 g) and 3,4-dihydroxyphenethylamine hydrochloride (2.1 g) were added to a mixture of n-butyl alcohol (35 ml), water (5 ml) and conc. hydrochloric acid (2 drops) and then the mixture was refluxed for 6.5 hours in a stream of nitrogen. The reaction mixture was concentrated to dryness and the residue was washed with acetone and collected by filtration to recover the starting material, 3,4-dihydroxyphenethylamine (1.2 g). The filtrate was concentrated to give 1-(N,N-diphenylaminomethyl)6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline hydrochloride (1.5 g), oil.
