Pachysandra Alkaloids. XIII. Structure and Stereochemistry of Spiropachysine, a Novel Spiro-lactam Alkaloid

Abstract

The structure of spiropachysine, a major alkaloid of the leaves of Pachysandra terminalis SIEB. et ZUCC. (Buxaceae), was investigated and assigned to the formula I, including absolute configuration, on the basis of chemical and spectroscopic evidences. The stereochemistry at the C₃-position was clarified by the circular dichroism study in comparison with the compounds having analogous aromatic chromophores and the known absolute stereochemistry. This alkaloid is unique in the structural feature possessing a five-membered spiro-lactam system.