Cephalocyclidin A, a novel pentacyclic alkaloid from Cephalotaxus harringtonia var. nana.

A novel alkaloid with an unprecedented fused-pentacyclic skeleton and six-consecutive asymmetric centers, cephalocyclidin A (1), has been isolated from the fruits of Cephalotaxus harringtonia var. nana, and the structure was elucidated on the basis of spectroscopic data. The relative and absolute stereochemistry of 1 was determined by a combination of NOESY correlations, X-ray crystallographic data, and the exciton chirality method.