ACETOGENIC ISOQUINOLINE ALKALOIDS .60. 5'-O-DEMETHYL-8-O-METHYL-7-EPI-DIONCOPHYLLINE-A AND ITS REGULARLY CONFIGURATED ATROPISOMER FROM TRIPHYOPHYLLUM-PELTATUM

The isolation and structure elucidation of two new minor naphthylisoqu inoline alkaloids from the stem bark of Triphyophyllum peltatum is des cribed. From extended spectroscopic investigations, mainly NMR and CD spectroscopy, one of the alkaloids is deduced to be 5'-O-demethyl-8-O- methyl-7-epi-dioncophylline A. This new natural product is, thus, the first dioncophylline A analogous naphthylisoquinoline alkaloid from T. peltatum with an opposite configuration at the biaryl axis. Moreover, low amounts of an additional new alkaloid were isolated, whose spectr al data suggest 5'-O-demethyl-8-O-methyl-dioncophylline A, i.e. the co rresponding 'normal' atropodiastereomer.