芳香環状異項環の分極 (第128報)

2-Metyl-7-oxo-Δ⁸-oktahydroisochinolinの合成

抄録

Reduction of 5-methoxyisoquinoline (I) with liquid ammonia-sodium-methanol by the Birch method, followed by hydrolysis with 10% sulfuric acid afforded 1, 2, 3, 4-tetrahydroderivative (II) in nearly quantitative yield. Further treatment of (II) with liquid ammonia-lithium-methanol resulted in recovery of the starting material. The same treatment of 2-methyl-5-methoxy-1, 2, 3, 4-tetrahydroisoquinoline (III) with liquid ammonia-lithium-methanol, followed by treatment with 10% sulfuric acid give α, β-unsaturated ketonic base in 4% yield, besides recovery of the majority of the starting material.
The same reduction of 2-methyl-7-methoxy-1, 2, 3, 4-tetrahydroisoquinoline (VI) afforded a base assumed to be 2-methyl-7-oxo-Δ⁸-octahydroisoquinoline (VII) in 40-50% yield. (VII) shows anomalous absorption in its ultraviolet spectrum, similar to 2-methyl-6-oxo-Δ⁵⁽¹⁰⁾-octahydroisoquinoline. Catalytic reduction of (VII) with palla-dium-barium sulfate or platinum oxide respectively gave 2-methyl-7-oxodecahydroiso-quinoline (VIII) and 2-methyl-7-hydroxy-decahydroisoquinoline.