Stepinonine, an Unusual Bisbenzylisoquinoline

The chemistry of the monophenolic yellow alkaloid ( —)-stepinonine, C36H34N2O7, isolated from Stephania japonica Miers, has been investigated by Ibuka, Konoshima, and Inubushi. The alkaloid shows a conjugated carbonyl band at 1663cm (6.02/x), and can be reduced with sodium boro-hydride to tetrahydrostepinonine whose IR spectrum is devoid of carbonyl absorption. A -Methylation of this derivative furnished A-methyltetrahydro-stepinonine whose A-methyl PMR signal appeared unusually upheld at 82.16. 

Finally, stepinonine was converted into a separable mixture of the known O-methylrepandine and (9-methyloxyacanthine by rearrangement of the appropriate ketone with zinc in acetic acid.  

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