Isolation and stereochemistry of two new alkaloids from Stemona tuberosa

Abstract Two new stenine-type alkaloids, neotuberostemonol ( 3 ) and neotuberostemoninol ( 4 ), along with the known compound neotuberostemonine ( 2 ), were isolated from Stemona tuberosa Lour. Their structures were characterized by X-ray crystallography in combination with spectroscopic methods, and their absolute configurations were inferred from the known configuration of tuberostemonine ( 1 ). In the crystalline state, weak C–H⋯O hydrogen bonds play an important role in the molecular packing of 3 and 4 .