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

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Abstract
A new Synthesis of 8‐Hydroxy‐2‐methyl‐1,2,3,4‐tetrahydroisoquinolineVilsmeier 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.