Alkaloids of the Australian Rutaceae: Lunasia quercifolia. II. The Nature of Lunasine

Abstract

The principal component of the mixture of water-soluble alkaloids of Lunasia quercifolia is shown to be the quaternary 4-methoxy-1-methylquinolinium structure IV corresponding to the 1-methyl-4-quinolone alkaloid lunacrine. The formation of IV from lunacrine and methyl iodide involves addition of the methyl group to the quinolone oxygen atom. It is suggested that this, as with the γ-pyrones, is the usual mode of reaction of 4-quinolone with alkyl halides. The properties of 4-methoxyquinolinium salts are discussed in relation to the conversion of furoquinoline alkaloids to the iso-alkaloids.