Berbamunine oxidation

Oxidation has been used to convert one type of dimeric skeleton to another. Thus, a mixture (421) of racemic berbamunine and magnoline, prepared via the bis diazoketone 422, was oxidized with buffered K3Fe(CN)6 to 423, which was methylated to a mixture of pakistanamine (46) isomers (283). Electroreduction... 

Zenk, M.H. Gerardy, R. Stadler, R. Phenol oxidative coupling of benzylisoquinoline alkaloids is catalyzed by regio- and stero-selective cytochrome P-450 linked plant enzymes salutaridine and berbamunine. J. Chem. Soc. Chem. Com-mun. 1989, 1725-1727. 

Two syntheses of racemic and/or enantiomeric mixtures of pakistanamine are now available. In the first synthesis, ferricyanide oxidation of racemic berbamunine [ -(53)] resulted in formation of an isomeric mixture (54), which upon treatment with diazomethane provided an oil. Chromatography of this oil yielded racemic material corresponding to pakistanamine (55). More recently, irradiation of the dimeric bromophenol (58) in refluxing liquid ammonia containing potassium t-butoxide gave rise to pakistanamine in 25—30% yield. ... 

Kametani s group subjected a mixture of berbamunines to ferricyanide oxidation to furnish the phenolic proaporphine-benzylisoquinolines 1. Diazomethane methylation then afforded a compound similar to pakistanamine. ... 

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