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Communication | Regular issue | Vol 2, No. 4, 1974, pp.433-437
Published online, 1st January, 1970
DOI: 10.3987/R-1974-04-0433
Abnormal Hofmann Degradation of Tetrahydroprotoberberinium Salts

Tetsuji Kametani,* Makoto Takemura, Keiichiro Fukumoto, Tsunekazu Terui, and Atsuko Kozuka

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan


Hofmann degradation of 7,8,13,13a-tetrahydro-9-hydroxy-2,3,10-trimethoxy-7-methylprotoberberinium iodide (2) with methanolic potassium hydroxide gave 1,2,3,4-tetrahydro-1-(3-hydroxy-4-methoxy-2-methoxymethylbenzyl)-6,7-dimethoxy-2-methylisoquinoline (13) in addition to the normal methine base (7). Abnormal Hofmann degradation was observed with nandinine methiodide (4) and its isomer (5). Moreover, this communication discusses the reaction mchanism of the abnormal Hofmann degradation and the biogenesis of the protoberberine alkaloid mecambridine (19).