Eine neue Synthese von 8‐Hydroxy‐2‐methyl‐1,2,3,4‐tetrahydroisochinolin

A new Synthesis of 8‐Hydroxy‐2‐methyl‐1,2,3,4‐tetrahydroisoquinoline Vilsmeier formylation of N ‐[2‐(3,5‐dimethoxyphenyl)ethyl]‐trifluoroacetamide ( 5 ) yielded the aldehyde 6 , which under mild basic conditions was hydrolyzed to 7 and cyclized to 6,8‐dimethoxy‐3,4‐dihydroisoquinoline ( 3 ). Methylation of 3 and reduction of the double bond in 10 afforded 6,8‐dimethoxy‐2‐methyl‐1,2,3,4‐tetrahydroisoquinoline ( 11 ). The methoxyl group at C(6) was selectively demethylated and the free hydroxyl group in 12 was phosphorylated to give 13 . Reduction of the latter with potassium in liquid ammonia yielded 8‐methoxy‐2‐methyl‐1,2,3,4‐tetrahydroisoquinoline ( 2 ), which was demethylated to the title compound 1 .