Schizanthines N, O, and P, Tropane Alkaloids from the Aerial Parts of <i>Schizanthus tricolor</i>

Three tropane alkaloids, named schizanthines N, O, and P (<b>1</b>−<b>3</b>), have been isolated from the crude alkaloid extract of the endemic Chilean plant <i>Schizanthus tricolor</i>. On the basis of extensive NMR studies and MS fragmentation analysis, their structures were determined to be 3α-(<i>E</i>)-4-hydroxysenecioyloxy-6β-angeloyloxytropane (<b>1</b>), 3α-(<i>E</i>)-4-hydroxysenecioyloxy-6β-senecioyloxytropane (<b>2</b>), and 3α-mesaconyloxy-6β-senecioyloxytropane (<b>3</b>). Compounds <b>1</b> and <b>2</b> are the first isomeric alkaloids in the tropane series possessing a hydroxysenecioyl substituent as an esterifying moiety.