Oxidation, bisbenzylisoquinolines potassium permanganate

Oxidation with potassium permanganate in aqueous acidic solution has been of utility in determining the nature and substitution of the lower half (benzyl half) of various bisbenzylisoquinoline alkaloids. In general, the major oxidative product is either a biphenyletherdicarboxylic acid or a biphenyldicarboxylic acid. It is... 

Oxidation of bisbenzylisoquinoline alkaloids with potassium permanganate has been found to be controllable enough to permit fission of only one of the two benzylisoquinoline systems. In this way the O-acetyl derivatives of the isomeric alkaloids tiliacorine and dinklacorine have been oxidised to the aldehydo-isoquinolones (67, R =Me, R =Ac) and (67, R =Ac,R =Me) respectively (Shamma and J.E. Foy, J.org.Chem., 1976, 1293 ... 

It is known that tetrahydrobenzylisoquinolines can be cleaved to isoquinolones using potassium permanganate. A method has now been developed for the oxidation of isoquinolinium salts. Taking papaverine methiodide as an example, this salt is first treated with aqueous alkali to supply the enamine 5. Treatment of a benzene solution of the enamine with oxygen in the presence of cuprous chloride provides the isoquinolone 6 in 0% yield. (For the oxidation of bisbenzylisoquinolines to isoquinolones, see Secs. 5.4 and 6.1.)... 

Potassium permanganate in acetone oxidation of a bisbenzylisoquinoline results in selective cleavage at the C-1 to C-a benzylic bond of the isoquinoline moiety which is unsubstituted at C-8. Relative stereochemistry does not affect the site of the oxidation. The product is an aldehydo lactam showing 1640-1645 cm" and 1690-1720 cm (5.82-5.92 and 6.08-6.17/a) which can be used for characterization purposes. The C-8 hydrogen peri to the new lactam carbonyl appears in the NMR spectrum as a singlet between 87.20 and 7.42. To exemplify, in the case of the oxidation of (H-)-hernandezine, the C-8 peri proton singlet is found at 87.23. The yields range from 5 to 35% and it is preferable to protect phenolic functions by acetylation prior to oxidation. ... 

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