O-Demethylation of Berberinium Salts

Conditions have been reported for a one-step ( -demethylation-(9-acylation. Berberine was thus converted to 9-0-acylberberrubine salts.  

The chemistry of protoberberine-acetone adducts has been reconsidered within the context of ease of alkylation and oxidation. Naruto and his students have reported that reactive alkyl halides such as methyl iodide react with berberine-acetone to yield, in addition to the expected berberine and 13-methylberberine, the bridged derivatives 38 and 39.  

They also found that while palmatine-acetone oxidizes with permanganate to afford the expected 8,14-propano derivative 40, similar oxidation of 13-methyl-palmatine-acetone led to cleavage of the 13-14 bond to yield the amidoketone 

14-Propano bridge formation must be fairly facile since it has been observed that the crude acetone adducts of a mixture of quaternary protober-berines were contaminated with small amounts of propano derivatives such as 42, as a result of intramolecular condensation.  

Berberine-acetone when subjected to mild permanganate oxidation is converted to neoxyberberine-acetone and to the lactamic acid 43 reminiscent of Perkin s berberal.  

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