Structural Revision of Harrisonin and 12 β-Αcetoxyharrisonin, Two Limonoids from <i>Harrisonia abyssinica</i>

Abstract

The structures of the known limonoids harrisonin (1) and 12β-acetoxyharrisonin (2), isolated from the root bark of Harrisonia abyssinica, were reanalyzed by modern 1D and 2D NMR spectroscopic methods, and the molecular structure and relative configuration of 12β-acetoxyharrisonin were determined by single-crystal X-ray diffraction. The spectral findings obtained require revision of the structures of these compounds from 1 and 2 to 3 and 4, respectively. The new molecular structures 3 and 4 display a novel limonoid skeleton with a unique five-membered ring B.