From Protoberberinium Salts

For the derivation of ( )-a- and ( )-j8-hydrastine from berberine through the intermediacy of oxybisberberine, see Sec. 19.3.5. 

When dehydronorcoralydinephenolbetaine, derived from dehydronorcor-alydine as shown, was briefly exposed to sunlight in the presence of rose bengal, and the product immediately reduced with borohydride, the corresponding phthalideisoquinoline 8 was obtained.  

A recent stereospecific conversion of berberine to j8-hydrastine proceeds through the intermediacy of oxyberberine. Short photooxidation of this pyridone—readily derived from berberine—in the presence of oxygen provided a y-lactol. A -Methylation and reduction then supplied racemic j8-hydrastine, practically unadulterated with the diastereomeric a-hydrastine (see also Sec. 

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The pseudobenzylisoquinoline alkaloids are fairly widespread in nature, being found among members of Berberidaceae, Annonaceae, Fumariaceae, and Ranunculaceae. The biogenesis of the pseudobenzylisoquinoline alkaloids assumes their formation from protoberberinium salts by C-8—C-8a bond scission in a Baeyer-Villiger-type oxidative rearrangement to produce the enamides of type 73 and 74. These amides may be further biotransformed either to rugosinone (76) type alkaloids by hydrolytic N-deformylation followed by oxidation or to ledecorine (75) by enzymatic reduction. These transformations were corroborated by in vitro studies (80-82). It is suggested that enamide seco alkaloids may be precursors of aporphine alkaloids (80), on one hand, and of cularine alkaloids (77), on the other. 

A new biogenetic route to the aporphines has been proposed which does not involve phenolic oxidative coupling, and which proceeds through the intermediacy of protoberberinium salts.6 The alkaloid polycarpine (44) must be derived biogenetically from palmatine (45), and indeed oxidation of (45) in vitro with m-chloroperoxybenzoic acid, followed by hydrolysis, leads to polycarpine (44). Since it is known that photocyclization of simple benzylisoquinoline... 

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