Bousmekines A-E, New Alkaloids from Two Bousigonia Species: B.angustifolia and B. mekongensis

Four new monoterpenoid indole alkaloids, bousmekines A-D ( 1 – 4 ), and one new pyranopyridine alkaloid, bousmekine E ( 5 ), were isolated from the twigs and leaves of Bousigonia angustifolia and Bousigonia mekongensis . Their structures including absolute configurations were elucidated by a combination of MS, NMR, ECD calculation, and single-crystal X-ray diffraction analysis. Compound 2 was an eburnea-type MIAs characterized by a rare chlorine...