Chemical constituents from Dehaasia triandra. II. Five new alkaloids, secoxanthoplanine, dehydroisocorydione, 11,8′- O-bisisocorydine, (8,8′- R)- and (8,8′- S)- bisisocorydine, isolated from the leaves

Abstract

A continuous study on the constituents from the leaves of Dehaasia triandra Merr. resulted in the isolation of five additional novel alkaloids- secoxanthoplanine ( 1), dehydroisocorydione ( 2), (8,8′- R)- ( 3) and (8,8′- S)-bisisocorydine ( 4), and 11,8′- O-bisisocorydine ( 5). Compounds 3 and 4 are the first C-C linked bisaporphines at C-8 while 5 is the first bisaporphine with a diphenyl ether-linkage at C-8 and C-11. Besides elucidation based on a spectral analysis, the structures of 1, 3 and 4 were further confirmed by semisynthesis.