DIONCOPHYLLINE-D AND 8-O-METHYLDIONCOPHYLLINE-D, 7,8'-COUPLED NAPHTHYLISOQUINOLINE ALKALOIDS FROM TRIPHYOPHYLLUM-PELTATUM

The isolation and structural elucidation of two novel naphthylisoquino line alkaloids, dioncophylline D and its 8-O-methyl analogue, from the West African liana Triphyophyllum peltatum are described. Their struc tures are based on the rare 7,8'-coupling between the two molecular mo ieties. The absolute configuration at the stereocentres of the isoquin oline half was established by oxidative degradation to give R-3-aminob utyric acid and D-alanine. Both alkaloids are characterized by a rapid rotation around the biaryl axis. The two new alkaloids are apparently found in young (carnivorous) plants, exclusively. (C) 1998 Elsevier S cience Ltd. All rights reserved.