Structural Revision of Macropodumine A and Structure of 2-Deoxymacropodumine A, Daphniphyllum Alkaloids with 11-Membered Macrolactone Rings.

An unusual Daphniphyllum alkaloid, 2-deoxymacropodumine A (1), possessing an 11-membered macrolactone ring, was obtained from an extract of the stems of Daphniphyllum angustifolium. The structure of 1 was elucidated by 1D and 2D NMR spectroscopic methods and chemical calculations. Based on a comparison of the experimental and calculated NMR data, the structure of macropodumine A (2'), an analogue of 1, was also revised.