Oxoaporphine Alkaloids: Conversion of Lysicamine into Liriodendronine and its 2‐ O ‐Methyl Ether, and Antifungal Activity

Pschorr reaction of diazonium salt 7 in aqueous methanolic sulfuric acid afforded, besides lysicamine 2 , the orange colored sulfate of oxodibenzopyrrocoline ( 8 ). The structure is fully supported by an X‐ray analysis of its picrate salt. Selective ether cleavage of lysicamine ( 2 ) with 48% HBr afforded a hydrobromide of 9 , and free betaine 9 on treatment with pyridine‐water. Both compounds methylated on treatment with etherial diazomethane on nitrogen to give the known 2‐ O N ‐dimethylliriodendronine ( 11 ). Liriodendronine ( 10 ) was obtained from lysicamine ( 2 ) on heating with pyridine ·HBr at 189°C, and treatment with pyridine‐water, as a dark violet betaine. Betaine 12 was obtained by heating 11 ·HCl to 200°C. The quaternary salts of lysicamine, lysicamine methiodide ( 3 ) and lysicamine methosulfate ( 4 ) were comparable in anticandidal activity to liriodenine ( 1 ), but were not as active as liriodenine methiodide ( 13 ).