Structure determination of grandifotane A from Khaya grandifoliola by NMR, X-ray diffraction, and ECD calculation.

Grandifotane A (1), a limonoid with an unprecedented carbon skeleton, was isolated from the stem bark of Khaya grandifoliola. The structure of 1 with the absolute configuration was determined by spectroscopic data, X-ray crystallography, and ECD calculation. A biogenetic route for grandifotane A (1) involving an enzymatic Baeyer-Villiger oxidation as the key step is proposed.