Terengganensines A and B, dihydroeburnane alkaloids from Kopsia terengganensis

Five known indole alkaloids, (+)-quebrachamine, (−)-eburnamine, (+)-isoeburnamine, (−)-eburnaminol and (+)-larutensine, and two new alkaloids, terengganensines A 1 and B 2, possessing a unique dihydroeburnane skeleton were isolated from the bark of Kopsia terengganensis. The structures of the new compounds were elucidated by spectral methods.