Isao Noguchi

Studies on the syntheses of heterocyclic compounds. Part CCCII. Alternative total syntheses of (±)-nandinine, (±)-canadine, and berberine iodide

Mannich reaction of 1-(2-bromo-5-hydroxy-4-methoxybenzyl)-1,2,3,4-tetrahydro-6,7-methylenedioxyisoquinoline (IX) gave 12-bromonandinine (II) which was debrominated to afford (±)-nandinine (I). Methylation of (±)-nandinine with diazomethane gave (±)-canadine (III), dehydrogenation of which with iodine afforded berberine iodide (XI).

Total synthesis of (±)-glaucine methopicrate by phenolic oxidative coupling

Phenolic oxidative coupling of 1-(3,4-dihydroxybenzyl)-1,2,3,4-tetrahydro-7-hydroxy-6-methoxy-2,2-dimethyl-isoquinolinium iodide gave 2,3,5-trihydroxy-6-methoxyaporphine methopicrate, which was methylated with diazomethane to give glaucine methopicrate, identical with an authentic sample obtained by an alternative synthetic method.

Formation of indole derivatives by phenolic oxidative coupling

Ferric chloride oxidation of 3-hydroxy-4-methoxyphenethylamine (3) and N-(3-hydroxy-4-methoxyphenethyl)-ethylamine (6) afforded the corresponding indole derivatives (10) and (11), respectively, in moderate yield. The synthesis of the indole derivative (13) from N-(3-hydroxybenzyl)dopamine (7) by phenolic oxidative coupling with potassium ferricyanide is also described.

Studies on the syntheses of heterocyclic compounds. Part CXXXV. The structure of corpaverine

Synthetic 1,2,3,4-tetrahydro-8-hydroxy-6,7-dimethoxy-1-(4-methoxybenzyl)-2-methylisoquinoline has been shown to differ from natural corpaverine. Separation of the natural product by recrystallisation and thin-layer chromatography has shown it to be a mixture of, or a molecular compound of, capaurine and sendaverine.