G. Bringmann et al., DIONCOPHYLLINE-D AND 8-O-METHYLDIONCOPHYLLINE-D, 7,8'-COUPLED NAPHTHYLISOQUINOLINE ALKALOIDS FROM TRIPHYOPHYLLUM-PELTATUM, Phytochemistry, 49(4), 1998, pp. 1151-1155
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.